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CT.TjI-^I->IJ-jT3r-JJJJJJJ-J^-J^I^lJJJ^^ 


Presented  in  honor  of 
lliai  ^aughl ' 

..llliam  R.    Laughlin 


coi.i.Kc;!-:  OF   osteopa mic    physicians 

AND  SURGEONS  •    LOS  ANGELES,  CALIFORNIA 


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WILLIAM   ROSS  LAUGHLIN 

M.S.  -  D.O. 

Los  Angeles,  California 


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UNIVERSITY  OF  CALIFORNIA 

'\I.IFORNIA  COLLEGE  OF  MEDICINE 

LIBRARY 

Jill  2  fil971 

IRVINE.  CALIFORNIA  9266-f 


HU^IA^T  AN^ATOMY 


MOBRIS 


ARRANGEMENT 

SUBJECTS  AND   AUTHORS. 

SECOND  EDITION. 

OSTEOLOGY,  hy  J.  Bland  Sutton,  F.R.c.s.,  Examiner  in  Anat- 
omy ill  K.i>:<l  Colk'tie  of  .Surgeons  :  Ltcturer  ou  Comparative  Anatomy,  and 
Senior  Denioiisti-ator  of  Anatomy,  .Middlesex  Hospital. 

JOINTS.  By  the  Editor,  Henry  Morris,  F.R.C.S.,  Surgeon  to,  and 
Lecturer  ou  Surgeiy  at,  Middlesex  Hospital  ;  Examiner  on  Anatomy  in 
Koyal  College  of  Surgeons  ;  Examiner  in  Surgery  in  the  University  of 
Loudon,  etc. 

MUSCLES.  I'.y  J.  N.  C.  Davies-CoUey,  f.k.c.s.,  Mem.  Path,  and 
Clin.  Soc,  London  ;  Fellow  Medico-Ciiir.  Soc. ;  Surgeon  to,  and  Lecturer  on 
Surgery  (late  Lecturer  on  Anatomy),  Guy's  Hospital,  etc. 

BLOOD-VESSELS    AND     LYMPHATICS.     By   "William   J. 

"Walsham,  f.k.c.s.,  Author  of  •' ^Manual  of  Practical  Surgery,"  Senior 
A.s-sistaut  Surgeon  to,  aud  Lecturer  on  Anatomy  at,  St.  Bartholomew's  Hos- 
pital ;  Surgeon  Metropolitan  Hospital,  etc. 

NERVOUS  SYSTEM.  By  H.  St.  John  Brooks,  m.d.,  of  Dublin, 
Secretary  for  Ireland  of  Anat.  Soc.  of  Great  Britain  ;  Chief  Demonstrator  of 
Auatumy,  Univei-sity  of  l)ul)lin,  etc.  Revised  by  Arthur  Robinson,  Lec- 
turer on  Anatomy,  Middlesex  Ho.spital  Medical  School. 

EYE.  By  R.  Marcus  Gunn,  f.k.c.s.,  Mem.  Path.,  Ophthal.,  and 
Xeurol.  Soc. ;  Surgeon  to  Koyal  Loudon  and  to  the  Western  Ophthalmological 
Hosjiitals.  etc. 

TONGUE.  NOSE,  EAR,  HEART.  VOICE,  RESPIRATION. 
By  Arthur  Hensman,  f.k.c.s..  Aural  Surgeon  (late  Senior  Demonstrator 
of  Anatomy)  Middlesex  Hospital  ;  Lectureron  Aural  Surgery  and  Anatomy, 
Middlesex  Hospital  Medical  School.  Revised  by  Arthur  Robinson,  of  the 
Middlesex  Hospital  Medical  School. 

ORGANS  OF  DIGESTION.  By  Frederick  Treves,  f.k.c.s., 
Surgeon  and  Lectureron  Surgery,  London  Hospital ;  late  Hunteriau  Professor 
of  AuatijiMy,  Koyal  College  of  Surgeons,  etc. 

URINARY  AND   GENERATIVE   ORGANS.     THE  SKIN. 

By  ■William  Anderson,  f.k.c.s..  Surgeon  to,  and  Lecturer  on  Anatomy, 
Skin  Department  St.  Thonnis'  Hospital  ;  Professor  of  Surgerj' aud  Pathology, 
Royal  Academy  :  late  Vice-President  Anatomical  Society,  etc. 

SURGICAL  AND  TOPOGRAPHICAL  ANATOMY.  By  W. 
H.  A.  Jacobson,  f.k.c.s..  Assistant  Surgeon  to  Guy's  Hospital ;  Surgeon  to 
Royal  Hospital  for  Children  and  Women  ;  Lecturer  on  Anatomy  (late  Teacher 
of  Operative  Surgery),  Guy's  Hospital  Medical  School.  Author  of  "The 
Operations  of  Surgery,"    "  Diseases  of  the  Male  Organs  of  Generation,"  etc. 

VESTIGIAL  AND  ABNORMAL  STRUCTURES.  By  Arthur 
Robinson,  .m.d.,  .m.k.c.s.,  Lectureron  ,\iiatoniy  in  the  .Middlesex  Hospital 
Medical  School  ;  Examiner  iu  Anatomy  for  the  Conjoint  Board  of  England. 


PUBLISHERS'   NOTICE. 

The  Illustrations  in  this  l)Ook,  for  the  most  j^art,  liave  been 
engraved  from  drawings  made  by  special  artists.  They  are 
generally  from  original  sources  ;  those  that  are  not,  have  been 
duly  credited  ;  all,  however,  with  few  exceptions,  owing  to 
re-drawing  and  engraving,  are  protected  by  copyright. 


HUMAN   ANATOMY 

A  COMPLETE   SYSTEMATIC  TREATISE 


BY  VABTOT-c;    \I'T1Ior!« 


INCLUDING  A  SPECIAL  SECTION  ON  SURGICAL  AND 
TOPOGRAPHICAL  ANATOMY 


V 


EDTTEn    BY 


HEISTRY    MORRIS,   M.A.  AND    M.B.  LOND. 

SENIOR   SURGEON  TO  THE  MIDDLESEX   HOSPITAL;    EXAMINER   IN  SURGERY    IN  THE   UNIVERSITY  OF   LONDON;    MEMBER 

OF    THE    COUNCIL,    AND    CHAIRMAN    OF    THE    COURT    OF    EXAMINERS   OF    THE    ROYAL    COLLEGE 

OF   SURGEONS    OF  ENGLAND;     HONORARY    MEMBER    OF    THE    MEDICAL 

SOCIETY    OF    THE    COUNTY    OF    NEW     YORK 


1IIlustratc^ 

BY  SEVEN  HUNDRED  AND  NINETY  WOODCUTS 

THE    GREATER    PART   OF  WHICH    ARE    ORIGINAL  AND    MADE    EXPRESSLY  FOR   THIS  WORK 

BY    SPECIAL   ARTISTS 

OVER  200   PRINTED   IN   COLORS 


Sccon^  jEMtion,  1Rc\nc<^  an^  J£nlaroc^ 


PJIILADELPIIIA 
P.    BLAKISTOX'S    SON   Sl    CO. 

10  12    WALNUT    STREET 

1899 


Coi'VRuniT.  1S98,  by  P.  Blakiston's  Son  &  Co. 


WM.   F.  FELL  &  CO., 

ELECTROTYPERS    AND    PRINTERS, 

1220-24    SANSOM    STREET, 

PHILADELPHIA. 


ALPHABETICAL  LIST  OF  CONTRIBUTORS 

TO  THE   FIRST  EDITION 


WILLIAM  ANDERSON 
H.  ST.   JOHN   BROOKS 
J.  N.  C.  DAVIES-COLLEY 
R.  MARCUS   GUNN 
ARTHUR   HENSMAN 
W.  H.   A.  JACOBSON 
HENRY   MORRIS 
J.  BLAND   SUTTON 
FREDERICK   TREVES 
W.   J.   WALSH  AM 


TO  THE  SECOND   EDITION 


The  same,  ^ith  Arthir  Robtxpon  in  place  of  H.  St.  John  Brooks 
and  also  in  place  of  Arthur  Hensman 


EDITOR'S  PREFACE  TO  THE  FIRST  EDITION. 


This  Treatise  on  Human  Anatomy  is  designed  for  the  use  of  Students  pre- 
paring for  the  Conjoint  Board  of  the  Koyal  Colleges  of  Physicians  and  Surgeons, 
for  the  Fellowship  of  the  lioyal  College  of  Surgeons,  and  for  the  Examinations 
in  Anatomy  at  the  various  Universities. 

It  aims  at  being  a  complete  and  systematic  description  of  every  part  and  organ 
of  the  human  body  so  far  as  it  is  studied  in  the  dissecting  room. 

Histology  and  development — except  the  mode  and  dates  of  development  of 
the  bones,  and  in  a  few  other  instances — are  not  included,  as  it  is  felt  that  these 
subjects  are  more  appropriately  dealt  with  in  books  on  Physiology  than  they  can 
conveniently  be  in  works  on  Anatomy. 

The  different  sections  have  been  written  by  separate  Authors,  who  are  known 
to  have  devoted  special  attention  to  the  subjects  allotted  to  them.  To  these 
gentlemen  my  best  thanks  are  due  for  their  generous  assistance  and  able  co- 
opemtion. 

AVhilst  each  Author  is  alone  responsible  for  the  subject-matter  of  the  article 
which  follows  his  name,  the  proof-sheets  of  other  articles  besides  his  own  have  in 
certain  cases  been  submitted  to  him,  so  that  several  of  the  articles  may  be  consid- 
ered to  have  received  the  apj)r()val  and  endorsement  of  two,  three,  or  more 
Authors.  This  has  been  particularly  the  case  with  the  sections  on  Osteology, 
Arthrology,  Myology,  and  Neurology.  There  is,  therefore,  reason  to  believe  that 
such  important  points  as  the  attachments  of  ligaments  and  of  muscles,  and  the 
nerve-supply  of  muscles,  etc.,  will  be  found  to  be  in  perfect  accord  in  the  various 
sections  in  which  they  are  referred  to  or  described. 

In  the  illustrations  of  the  bones,  the  origins  of  muscles  are  indicated  by  red 
lines,  the  insertions  by  blue  lines,  and  the  attachments  of  ligaments  by  dotted 
black  lines. 

A  feature  of  the  book  which,  it  is  confidently  hoped,  will  facilitate  the  work 
of  students,  is  the  mode  of  describing  the  illustrations. 

This  plan  was  decided  upon  at  a  conference  of  all  the  Authors  and  one  of  the 
artists.  It  consists  in  printing  the  descriptions  in  different  types  at  the  end  of  the 
pointers.  Thus  it  will  be  found  that  muscles,  fasci:c,  and  ligaments  are  in  one 
kind  of  type;  arteries,  veins,  and  lymphatics  in  another;  bones  in  a  third  ;  and 
nerve-structures  in  a   fourth.      The  names  of  special   organs — such  as  the  liver, 

V 


VI 


EDIToirS  PREFACE   TO    THE  FIRST  EDITION. 


lu„crs,  etc. are   printed    in  tlio  >aiiu'  type  as  the  bones,  so  as  to  avoid  too  great  a 

variety  of  lettering. 

Several  of  the  illustrations  are  repeated  in  different  parts  of  the  book,  Avith 
the  object  of  sparing  the  ii-ader  the  tronble  of  referring  from  one  section  to  another 
when  reference  is  made  in  the  letterpress  to  snch  figures. 

As  much  uniformity  as  possible  has  been  observed  in  the  size  and  general  style 
of  the  drawings ;  but  exceptions  will  be  found  in  the  section  on  Surgical  and 
ToiJoirraphical  Anatomy,  for  which  many  of  the  illustrations  have  been  borrowed 
from  another  work,  published  by  Messrs.  J.  and  A.  Churchill,  namely,  Bellamy's 
'  Surgical  Anatomy.' 

I  have  to  acknowledge  with  grateful  thanks  the  assistance  I  have  received 
from  Mr.  (tordox  Brodie,  who  made  several  dissections  from  which  drawings 
were  taken;  from  Mr.  J.  Bland  Suttox  and  Mr.  Frank  Steele  in  reading 
over  proof-sheets  ;  from  Mr.  Burghard  for  the  care  Avith  which  he  has  drawn 
up  the  Index  and  Tables  of  Contents ;  and  from  all  the  artists  named  on  the 
title-page. 

Mr.  Bhr.teau  and  Mr.  Balcomb  have  drawn  a  very  large  proportion  of  the 
figures  ;  and,  with  Mr.  Smit  and  ^Ir.  Parker,  have  shown  a  degree  of  interest 
in,  and  given  an  amount  of  titue  and  trouble  to  the  illustrations  for  which  they 
merit  the  fullest  recognition. 

The  beautiful  anatomical  dissections  in  the  Hunterian  Museum  which  have 
been,  by  permission,  copied  for  this  Treatise  are  from  the  hand  of  Mr.  William 
Pearson,  to  whose  great  skill  in  dissecting  I  have  much  pleasure  in  referring. 

Too  nuich  praise  cannot  be  given  to  all  engaged  in  the  actual  printing  of  the 
book  for  the  painstaking  care  they  have  devoted  to  it;  especially  to  the  difficult 
and  precise  work  of  properly  'registering'  and  printing  the  coloured  illustrations. 

I  need  only  say,  in  conclusion,  that  I  shall  not  consider  my  prolonged  and 
laborious  task  has  been  in  vain  if  it  be  found  that  the  Treatise  adequately  meets 
the  requirements  of  Students,  for  whom  it  is  written. 

Henry  Morris. 
8  Cavendish  Square  :  January  1893. 


PREFACE  TO  THE  SECOND  EDITION. 


In  preparing  this  Edition  the  work  luis  been  carefully,  and  it  is  hoped  thor- 
oughly, revised,  both  in  regard  to  the  descriptive  text  and  the  illustrations.  Some 
new  cuts  have  been  added,  and  in  a  few  instances  new  ones  have  been  substituted 
for  those  in  the  First  Edition. 

A  description  of  the  Skin  has  been  added  by  Mr.  Anderson  ;  and  an  additional 
section  at  the  end  of  the  volume,  on  "Vestigial  and  Abnormal  Structures,"  has 
been  supplied  by  the  pen  of  Dr.  Robinson. 

The  Editor  has  been  fortunate  in  obtaining  the  assistance  of  the  original 
authors  of  the  various  sections  in  all  cases  but  two.  Dr.  Arthur  liobinson  has 
revised  the  section  on  the  Xervous  System  instead  of  Dr.  H.  St.  John  Brooks ; 
and  also  those  which  were  written  by  the  late  Mr.  Arthur  Hensman. 

The  Editor  has  to  thank  many  kind  friends,  and  others  personally  unl<nown 
to  him,  both  in  the  United  Kingdom  and  in  America,  for  numerous  and  valuable 
suggestions,  and  for  corrections  of  typographical  errors,  which  regrettably  but 
almost  unavoidably  had  crept  into  the  first  edition.  Great  attention  has  been 
given  to  all  of  these  suggestions.  Many  of  them  have  been  adopted,  and,  if  all 
have  not  been,  it  is  because  they  were  n(jt  in  accord  with  the  object  and  intention 
of  the  work.  For  instance,  one  friendly  critic  thinks  that  in  order  t(»  make  it 
complete  as  a  text-book  the  Minute  Anatomy  of  the  Viscera  must  be  added ;  this 
would  be  entirely  inconsistent  with  our  aim,  M'hich  is  to  make  the  book  complete 
as  "  a  systematic  description  of  every  part  and  organ  of  the  human  body  as  it  is 
studied  in  the  dissecting  room."  Minute  anatomy  must  be  studied,  of  course  ; 
but  in  the  histological  laboratory,  not  in  the  dissecting  room,  or  at  the  demon- 
strator's classes  on  Topographical  Anatomy. 

It  is  hoped  that  this  revised  edition  will  receive  the  confidence  of  the 
Teachers,  and  find  favour  with  the  Students  whose  labours  the  book  is  intended  to 
facilitate. 

Cavexdish  Squaee,  London  :  September  7,  189S. 


VI 1 


CONTENTS 


SECTION  I 

OSTEOLOGY 

By  J.  Bland  Sutton 


PAGE 

The  Skeleton 1 

A  Classified  List  of  the  Bones  to  show 

their  Mode  of  Development     ...  2 

The  Spine 5 

Characters  of  a  Typical  Vertebra    .    .  6 

The  Cervical  Vertebrae 7-11 

The  Thoracic  or  Dorsal  Vertebrae    .    .  12 

The  Lumbar  Vertebrae 12 

The  Sacral  and  Coccygeal  Vertebrae   .  14-17 

The  Spinal  Column  in  general     ...  17 

Ossification  of  the  Vertebrae    ....  19 

Serial  Morphology  of  the  Vertebrae    .  22 

The  Bones  of  the  Skull 24-62 

The  Appendicular  Elements  of  the  Skull  62 

Mandible  (Lower  Jaw)      62 

Hyoid  Bone 66 

Styloid  Process 67 

Ear  Bones 68 


PAGK 

The  Skull  as  a  whole- 
Exterior  of  the  Skull 69 

The  Orbits        76 

The  Nasal  Fossae 7a 

Interior  of  the  Skull 81 

The  Teeth 86 

Mori)hology  of  the  Skull 89 

Metamorphosis  of  the  Branchial  Bars  90 

Skull  at  Birth 90 

Peculiarities  of  Individual  Bonos  at 

Birth      92 

Nerve-Foramina  of  the  Skull  ....  96 

The  Ribs  and  Sternum 98 

The  Thorax 108 

The  Bones  of  the  Upper  Extremity    .    .  109-138 

The  Hip-Bone 138 

The  Pelvis 145 

The  Bones  of  the  Lower  Extremity   .    .  147-175 


SECTION   II 

THE  A  R  TIC  CLA  TIONS 
By  Henry  Morris 


Structures  entering  into  the  formation  of 

Joints 176 

The  various  kinds  of  Articulations     ...      177 
The  various  Movements  of  Joints  ....      179 

The  Articulations  of  the  Skull 179 

TheTemporo  mandibular  Articulation      180 
The  Ligaments  and   Joints   between 
the  Skull  and  Spinal  Column,  and 
between  the  Atlas  and  Axis         .    .      183 
The  Articulation  of  the  Atlas  with 

the  Occiput 183 

The  Articulations    between    the 

Atliisand  Axis 185 

The  Ligaments  uniting  the  Occi- 
put and  .Axis 188 

The  Articulations  of  the  Trunk 190 


The  Articulations    of   the  Verteliral 

Column 190 

The  .Articulations  of  the  Bodies  of 

the  Vertebne 1!»0 

The  Ligaments  uniting  the  Articular 

Processes 191 

The  Ligaments  uniting  the  Lamina.-      194 

The  Ligaments  uniting  the  Spinous 

Processes 195 

The  Ligaments  uniting  the  Trans- 
verse Proces.ses 197 

The  Articulations  of  the  Pelvis  with  the 

Spine 198 

The  Articulations  of  the  Pelvis  ....       200 

The  Sacro-iliac  Synchondrosis  and 
Sacro-sciatic  Ligaments     ....      200 


COyTEXTS 


PAGE 

The  Sacro-coccygeal  Articulation     .  204 

The  Inter-foocygeal  Joints    ....  205 

The  Symphysis  l*u))is 205 

The  Articulations  of  the  Ribs  with  the 

Vertebnc  .    .        208 

The  Costo-central  Articulation     .    .  208 

The  Costo-transverse  Articulation  .  210 
The  Articulations  at  the  Front  of  the 

Thorax 211 

The  Choudro-sternal  Articulations  212 

The  Costo-choudral  Joints    ....  212 
The  Union  of  the  Segments  of  the 

Sternum 212 

The  Interchoudral  Articulations     .  214 

Movements  of  the  Thorax  as  a  whole    .  215 

The  Articulations  of  the  Upper  Extremity  216 

The  Sterno-clavicular  Articulation      .  216 

The  Scapuloclavicular  Union  ....  219 

The  Acromio-clavicular  Joint  ...  219 

The  Coraco-clavicular  Union    .    .    .  220 

The  Proper  Scapular  Ligaments  .    .  221 

The  Shoulder- Joint    .    .    T 222 

The  Elbow-Joint 227 

The  Union  of  the  Radius  with  the 

Ulna      229 

The  Superior  Radio-ulnar  Joint  .    .  230 

The  Mid  Radio-ulnar  Union     ...  230 

The  Inferior  Radio  ulnar  Joint   .    .  232 

The  Radio-carpal  Articulation     ....  233 

The  Carpal  Joints 237 

The  Union  of  the  First  Row  of  Carpal 

Bones 237 

The  Union  of  the  Pisiform  with  the 

Bones  of  the  First  Row 237 

The  Union  of  the  Second  Row  of  Car- 
pal Bones 237 

The  Medio-carpal  Joint 238 

The  Carpo- metacarpal  Joints 240 

The     Four    Inner    Carpometacarpal 

Joints 241 

The  Carpometacarpal  Joint  of   the 

Thumb 242 

The  Intermetacarpal  Articulations     .    .  242 
The  Union  of  the  Heads  of  the  Meta- 
carpal Bones 243 


PAGE 

The  Metacarpo-phalangeal  Joints   .    .    .  243 
The  Metacarpo-phalangeal  Joints  of 

the  Four  Inner  Fingers 243 

The    Metacarpo-phalangeal    Joint    of 

the  Thumb 244 

The  Interphalaugeal  Articulations      .    .  245 

The  Articulations  of  the  Lower  Limb    .    .  246 

The  Hip-Joint 246 

The  Knee  Joint 253 

The  Tibio  fibular  Union 263 

Tiie  Superior  Tibiofibular  Joint     .    .  263 

The  Middle  Tibiofibular  Union  .    .    .  264 

The  Inferior  Tibiofibular  Articulation  265 

The  Ankle-Joint 266 

The  Tarsal  Joints 269 

The  Calcaneo-astragaloid  Union  .    .    .  269 
The    Posterior    Calcaneo  astragaloid 

Joint      269 

The      Anterior      Calcaneo-astragaloid 

Joint      . 270 

The  Articulations  of  the  Anterior  Part 

of  the  Tarsus 271 

The  Cubo  scaphoid  Union     ...  271 

The  Scapho-cuneiform  Articulation  272 

The  Intercuneiform  Articulation    .  272 

The   Cubo-cuneiforni    Articulation  272 
The  Medio-tarsal  or  Transverse  Tarsal 

Joints 273 

The  Astragalo-scaphoid  Articulation  273 

The  Calcaneo-cuboid  Articulation  .  274 

The  Tarso-metatarsal  Articulations    .    .  276 

The  Internal  Tarso-metatarsal  Joint  277 

The  Middle  Tarso-metatarsal  Joint  277 

The  Cubo-metatarsal  Joint   ....  278 

The  Intermetatarsal  Articulations      .    .  279 
The  Union  of  the  Heads  of  the  Met- 
atarsal Bones   ....            ...  279 

The  Metatarsophalangeal  Articulations  279 
The  Metatarsophalangeal  Joiuts  of 

the  Four  Outer  Toes              .    .  279 
The  Metatarsophalangeal  Joint  of 

the  Great  Toe  ... ' 280 

The  Interphalangeal  Joiuts  .    .    .        .    .  280 

Morphology  of  Ligaments 281 


SECTION  III 

THE  MUSCLES 
By  J.  N.  C.  Davies-Coli.ey 


fJeneral  Remarks  on  Muscles 282 

Muscles  of  the  Upper  Extremitv' — 

I'osterior  Division  of  the  Group  of 
Muscles  passing  from  the  Trunk 
to  the  Upper  Extremity    ....      288 

First  Layer ' 288 

Second  Layer 290-293 

Anterior  Division  of  the  Group  of 
Muscles  passing  from  the  Trunk 
to  the  Upper  Extrennty    ....      293 

First  Layer 294-296 

Second  Layer 296-298 

Third  Layer 298-300 

Muscles  which  pass  from  the  Scapula 
to  the  Upper  Limb 300-305 


Group  of  Mitscles  which   move   the 

Elbow-Joint 306 

Fasciie  of  the  Upper  Arm  ....  306 
Flexors  of  the  Forearm  ....  307-309 
Extensors  of  the  Forearm     ....      309 

Muscles  of  the  Forearm 311 

Muscles  of  the  Front  of  the  Forearm      311 

First  Layer 312-315 

Second  Laver 315-318 

Third  Layer 318-320 

Fourth  Laver 321 

Radial  Group  of  Mu.scles  ....  321-324 
]\Iuscles  of  the  Back  of  the  Forearm      324 

Superficial  Laver 324-328 

Deep  Layer  .  ' 328-332 


CONTENTS 


XI 


PAGB 

The  Fiisciie  of  the  Haud  ....      332 

The  Palmar  Fascia 3I!:{ 

Mu.scles  of  the  Hand 334 

Superlicial 334 

Deep  Mu.scles  of  the  Palm    ....      335 

Central  Group 335-339 

Muscles    of    the    Thenar    Emi- 
nence           339-343 

Muscles  of  the  Hypotheuar  Emi- 
nence           343 

Muscles  of  the  Lower  Extremity  — 

Muscles  and  Fasciie  of  the  Thigh   .    .      344 
M  uscles  of  the  Front  of  the  Thigh  346-351 

The  (Jluteal  Muscles 351 

First  Layer 351-353 

Second  Layer 353 

Third  Layer 354 

The  External  Rotators  of  Thigh    354-358 
The  Adductors  of  the  Thigh    .    .  358-362 
The  Hamstring  Muscles    ....  363-365 

The  Anterior  Muscles  of  the  Thigh      365 
The  Deep  Fascia  of  the  Leg  and  Annu- 
lar Ligaments  .......      368 

Mu.scles  of  the  back  of  the  Leg  .    .      369 

First  Layer 369-371 

Second  Layer 371-373 

Third  Layer 373 

Fourth  Layer 376 

The  Fascia  and  Muscles  of  the  Sole  of 

the  Foot 377 

First  Layer 378-381 

Second  Layer 381,  382 

Third  Layer 382-385 

Fourth  Laver 385 

Muscles  of  the"  Front  of  the  Leg  .  387-391 
Muscle  on  the  Dorsum  of  the  Foot  .  .  391 
Muscles  on    the   Outer  Side  of   the 

Leg        392,  393 

Muscles  of  the  Thorax 395 


PAliE 

The  Diaphragm 399 

The  Abdominal  Parietes 401 

The  Abdominal  Muscles 401 

Anterior  Vertical  Mu.scles 402 

Transverse  and  Oblique  Muscles     .  404-410 

Posterior  Vertical  I\lu.scle 410 

Mascles  of  the  liack 411 

rhird  Layer 411-413 

General    Arrangement  of   the   Muscles 

acting  upon  the  Spinal  Column   .    .      413 
The  Vertebral  Aponeurosis  ....  413 

Fourth  Layer 414 

Fifth  Layer 415-420 

Sixth  Layer 420-423 

Seventh  Layer 423 

The  Suboccipital  Muscles 424 

Muscles  of  the  Head  and  Neck 425 

Superficial  Muscles  of  Neck  and  Scalp  .  426-429 
Muscles  of  the  Eyelids  and  Eyebrows  .  429-431 
Extrinsic  Muscles  of  the  Auricle     ....      431 

Muscles  of  the  Nose 432 

Muscles  of  the  Mouth 434 

Transverse  Muscles  of  the  Mouth  .    .    .      436 
Angular  Mu.scles  of  the  Mouth    ....      436 

Labial  Grou])  of  jNI  uscles 438 

Muscles  radiating  from  the  Mouth  .    .         440 

Muscles  of  Mastication 440-444 

Mu.scles  and  Fasciae  of  the  Front  of  the 

Neck 444 

First  Group 445 

Second  Group — Infra-hyoid      ....      447 

Superficial  Layer 447 

Second  Layer 448 

Third  Group — Supra-hyoid  ....  449-451 
Extrinsic  Muscles  of  the  Tongue  .  .  451-454 
Deep  Muscles  of  the  Front  of  the  Neck    .      454 

Outer  Group 454 

Inner  Group 456 

Abnormal  Muscles.     [By  J.  B/and  Sidton)      458 


SECTION  IV 

ARTERIES,  VEINS,  AND  LYMPHATICS 

By  W.  J.  Walsham 


The  Arteries 462 

The  Pulmonary  Artery 462 

The  Right 464 

The  Left 466 

The  Systemic  Arteries 466 

The  Aorta 466 

Arch  of  the  Aorta 467 

Variations  in  the  Arch  of  the  Aorta  .  470 
Branches  of  the  Arch  of  the  Aorta     .  472 
Coronary  Arteries  and  their  Varia- 
tions    472 

Innominate  Artery 474 

Branches  and  Variations   ....  475 

Common  Caroti<l  Arteries          .    .    .  475 
Thoracic  Portion  of  Left  Common 

Carotid 475 

Common  Carotid  in  the  Neck  .    .  476 

Branches  and  Variations   .    .    .  479 

External  Carotid  Artery 480 

Branches  and  Variations  .    .    .  480-497 

Internal  Carotid  Artery 497 

Branches  499-505 


Subclavian  Artery 50.7 

Variations 508 

Branches 508-513 

Distribution  of  the  Cerebral  Arteries  513 

Axillary  Artery 520 

Branches  and  Variations  ....  521 

Brachial  Artery 526 

Branches  and  Variations  ....  .529 

Ulnar  Artery 531 

Branches  and  Variations       .    .    .  531 

Superficial  Palmar  Arch 536 

Variations 537 

Branches 538 

Radial  Artery 538 

Variations 540 

Branches 540 

Deep  Palmar  Arch 543 

Branches  and  Variations  ....  543 

Descending,  or  Thoracic  Aorta    ....  545 

Visceral  Branches 545 

Parietal  Branches 548 

Abdominal  Aorta 550 


Xll 


CONTENTS 


PAGE 

Variatious 552 

Parietol  l^ranohes 553,  554 

Visceral  lirauclies 555-563 

Teriuiiial  Branches 563 

Middle  Sacral  Artery -''OS 

Branches  and  Variatious   ....  564 

Coinnion  Iliac  Arteries 564 

Variatious 565 

Collateral  Circulation 565 

Branches ...  565 

Internal  Iliac  Artery 566 

Variations 567 

Branches  of  Posterior  Division  567-569 

Branches  of  Anterior  Division  569-576 

External  Iliac  Artery 576 

Branches  aud  Variatious  ....  577 

Collateral  Circulation 577 

Femoral  Artery 579 

Branches  and  Variations  ....  581 

Popliteal  Artery 586 

Branches  and  Variatious  ....  586 

Posterior  Tibial  Artery 590 

Branches 591 

External  Plantar  Artery 593 

Branches 593 

Internal  Plautar  Artery    .        ...  596 

Branches 596 

Anterior  Tibial  Artery 596 

Branches 598 

Dorsalis  Pedis  Artery 600 

Branches 600 

The  Veins 602 

Veins  of  the  Thorax 602 

Pulmonary  Veius 602 

Vena  Cava  Superior 603 

Innominate,     or     Brachio-cephalic 

Veins 603 

Variations 605 

Azygos  Veins 606 

Veins  of  the  Heart 609 

Veins  of  the  Head  and  Neck    ....  611 
Superficial  Veins  of  the  Head  and 

Neck      611-617 

Deej)  Veins  of  the  Head  and  Neck  .  617 

Veins  of  the  Diploe 618 

Venous  Sinuses  of  the  Cranium  .  619 

Veins  of  the  Brain 623 

Veins  of  the  Nasal  Cavities  .    .    .  625 

Veins  of  the  Ear 625 

Veins  of  the  Orbit 625 


PAGE 

Veins  of  the  Pharynx  and  Larynx  626 

Deep  Veins  of  the  Neck    ....  627 

Spinal  Veins 628 

Veins  of  the  Abdomen  and  Pelvis  .    .  630 

Inferior  Vena  Cava 631 

Variations 633 

Common  Iliac  Veius 634 

Variations 634 

Portal  Vein  aud  its  Tributaries   ,    .  634 

Veins  of  the  Pelvis 638 

Veius  of  the  Upper  Extremity     .    .    .  639 

Superficial  Veius  of  the  Upper  Ex- 
tremity        639 

Deep  Veins  of  the  Upper  Extremity  643 

Veius  of  the  Lower  Extremity    .    .    .  644 

Superficial  Veins  of  the  Lower  Ex- 
tremity        644 

Deep    Veins    of    the    Lower    Ex- 
tremity        646 

The  Lymphatics 648 

Lymphatics  of  the  Head  aud  Neck     .  648 
Superficial  Lymphatic  Vessels  and 

Glands  of  the  Head  aud  Neck     .  649 
Deep  Lymphatic  Vessels  and  Glands 

of  the  Head  and  Neck    .    .        .    .  651 

Lymphatics  of  the  Upper  Extremity  653 
Superficial  Lymphatic  Vessels  and 

Glands  of  the  Upper  Extremity  .  655 
Deep  Lympliatic  Vessels  and  Glands 

of  the  Upper  Extremity    ....  655 

Lymphatics  of  the  Thorax 656 

Parietal     Lymphatic    Vessels    and 

Glands  of  the  Thorax    ....  656 
Visceral     Lymphatic    Vessels    and 

Glands  of  the  Thorax    ...        .  658 

Thoracic  Duct 659 

Variations 660 

Lymphatics  of  the  Abdomen  and 

Pelvis 660 

Parietal  Lymphatic  Vessels  aud 
Glands  of  the   Abdomen   and 

Pelvis    .    .                    ....  660 

Visceral  Lymphatic  Vessels  aud 
Glands  of  the   Abdomen  and 

Pelvis 662 

Lymphatics  of  the  Lower  Extremity  667 
Superficial  Lymphatic  Vessels  and 

Glands  of  the  Lower  Extremity  667 
Deep     Lymphatic    Vessels    and 

Glands  of  the  Lower  Extremity  667 


SECTION  V 

THE  NERVOUS  SYSTEM 
By  H.  St.  John  Brooks 

Revised  for  Second  Edition  by  ARTHUR  ROBINSON,  M.  D. 


Neurolofiy 669 

The  Meuiuf^es  671 

Lymphatics  of  the  I'.raiu  and  Spinal 

"Cord 678 

The  Encephalon 679 

Base  of  the  lirain 679 

Cerebral  Hemispheres 681 


Lobes  of  Cerebral  Hemispheres  with 

the  Fissures  and  Convolutions  .    .    .  684 

Basal  Ganglia  of  the  Hemispheres  .    .  699 

The  Thalamencephalou 704 

The  Mesencephalou 710 

The  Epencephalon 713 

The  Metencephalon 720 


CONTENTS 


Xlll 


Cranio-cerebral  Topography 727 

Tlie  Spiual  Cord I'M 

Exterual  Characters 7M 

Internal  Structure 737 

Deep  Origin  of  the  Spinal  Nerves  .    .  7:58 

The  Peripheral  Nervous  System 743 

Cranial  Nerves 743 

First  or  Olfactory  Nerve 745 

Second  or  Optic  Nerve 746 

Third  or  Oculo-motor  Nerve     .    .    .  747 

Fourth  or  Trochlear  Nerve  ....  748 

Fifth  or  Trigeminal  Nerve    ....  749 

Firstor  Ophthalmic  Division    .    .  751 

Lenticular  Ganglion 752 

Second  or  Maxillary  Division  .    .  753 

Meckel's  Ganglion 755 

Third  or  Mandibular  Division      .  756 
Submandibular     (Submaxillary) 

Ganglion 759 

Otic  Ganglion      760 

Sixth  or  Abducent  Nerve 760 

Seventh  or  Facial  Nerve 761 

Eighth  or  Auditory  Nerve    ....  765 

Ninth  or  Glosso-pharyngeal  Nerve  767 

Tenth  or  Pneumogastric  Nerve    .    .  769 

Eleventh  or  Spinal  Accessory  Nerve  773 

Twelfth  or  Hypoglossal  Nerve     .    .  774 

Spinal  Nerves 776 

Posterior  Primary  Divisions     .    .    .  779 

Anterior  Primary  Divisions  ....  782 

Cervical  Nerves 782 


Cervical  Plexus 783 

Superficial  Branches  ....  783 

Deep  r>rauches 785 

Brachial  Plexus 786 

Branches  given  off  above  the 

Clavicle 787 

Branches  given  olf  below  the 

Clavicle 788 

Thoracic  Nerves 799 

Lumbar  Nerves 802 

Lumbar  Plexus 802 

Sacral  and  Coccygeal  Nerves    ....  809 

Fourth  Sacral  Nerve 809 

Coccygeal  Plexus 809 

Sacral  Plexus 809 

The  Great  Sciatic  Nerve 814 

Sympathetic  Nerves 826 

Gaugliated    Cords  of   the  Sympa- 
thetic       826 

Cervical  Portion 827 

Superior  Cervical  Ganglion  .    .  827 

Middle  Cervical  Ganglion     .    .  830 

Inferior  Cervical  Ganglion    .    .  830 

Thoracic  Portion     .......  830 

Lumbar  Portion 833 

Sacral  Portion 833 

Great  Prevertebral  Plexuses    .    .    .  834 

Cardiac  Plexus 834 

Solar  Plexus 835 

Hypogastric  Plexus 837 

Pelvic  Plexuses 837 


SECTION  VI 
ORGANS   OF  SPECIAL  SENSE 

PART    I:    THE    EYE 

By  R.  Marcus  Gunn 


The  Eye 839 

The  Eyeball  and  its  Surroundings  .    .  839 

General  Surface  View 839 

Examination  of  the  Eyeball     .    .    .  843 

Cavity  of  the  Orbit     ........  854 

General   Arrangement  of  its  Con- 
tents    854 


The  Optic  Nerve 860 

Bloodvessels    and    Nerves  of   the 

Orbit 862 

The  Eyelids 865 

The  Lachrymal  Apparatus   ....  867 


PART  11:  THE  EAR,  THE  TONGUE,  THE  NOSE 

Bv  AKTiin:  Hknsman 

Revised  for  Second  Edition  by  AnTIIlIl  UOIUXSOX,  M.  I). 


The  Ear 870 

Tiie  External  Ear 870 

The  Middle  Ear 873 

The  Internal  Ear  or  Labyrinth    .    .  879 

The  Tongue 884 


The  Nose 8H9 

The  Cartilages 890 

JMuscles 891 

The  Skin 892 

The  Vessels      893 

Communications 897 


XIV 


COXTEXTS 


SECTION  VII 

THE  THORAX,  INCLUDING  THE  ORGANS   OF  VOICE, 
RESPIRATION,  AND   CIRCULATION 

By  Akthuk  Hensmax 

Revised  for  Second  Edition   bv   ARTHUR  ROBINSON,  M.  D. 


PAGE 

The  Thorax 898 

The  Organs  of  Voice 901 

The  Larvux 901 

The  Trachea 913 

The  Bronchi 915 

The  Thj^roiil  Body  or  Gland    ....  915 

The  Thymus  Body  or  Gland    ....  918 

The  Organs  of  Respiration 920 

The  Lungs 920 

The  Pleurae 920 


PAGE 

The  Organs  of  Circulation 925 

The  Pericardium 925 

The  Heart 920 

The  Openings  and  their  Valves   .    .  932 
The  Relations  of  the   Chief  Open- 
ings one  to  the  other  and  to  the 

Chest  Wall 935 

The  Vessels  and  Nerves 936 

Peculiarities  of  the  Foetal  Heart  .    .  939 


SECTION  VIII 
THE  ORGANS   OF  DIGESTION 

PART  I:    THE   ORGANS  ABOVE   THE   DIAPHRAGM 
By  Arthur  Hensman 

Revised  for  Second  Edition  by  ARTHUR  ROBINSON,  M.  D. 


The  Mouth 942 

The  Palate 943 

The  Salivary  Glands 946 


The  Pharynx 949 

The  CEsophagus 952 


PART  II:     THE  ABDOMINAL  VISCERA 

By  Frederick  Treves 


The  Peritoneum 954 

The  Abdomen 959 

The  Stomach 960 

The  Intestines 964 

The  Small  Intestine 964 

Tlie  Large  Intestine 969 

The  Liver 976 


Varieties  of  the  Liver 986 

The  Pancreas 986 

The  Spleen 988 

The  Evolution  of  the  Peritoneum  and  an 
Explanation  of  its  Arrangement  in  the 

Human  Body 991 


SECTION  IX 

THE  URINARY  AND  REPRODUCTIVE  ORGANS 
By  William  Axdkrsox 


The  Kidneys 1005 

The  Suprarenal  Bodies 1013 

The  Renal  Ducts 1014 

The  Bladder 1016 


The  Male  Reproductive  Organs 1021 

The  Prostate 1021 

The  Testicles  with  their  Ai)pendages 

and  Coverings 1023 


COMEMS 


XV 


PA  (it; 

The- Spermatic  Cord 1030 

The  Penis lu;il 

The  Urethra 1U35 

The  Female  Organs  of  Generation  ....  1U38 

The  Vagina 1042 

The  Uterus 1044 

The  Fallopian  Tul)es  or  Oviducts   .    .  1051 

The  Ovaries      1052 


PAGE 

Yessels  and  Nerves  of  the  Uterus  and 

its  Appendages    ........  1053 

Development  of  the  Uenito- Urinary  Organs  1055 

The  Perimeum 1058 

The  Male  Perina-um 1058 

The  Pelvic  Fascite  and  Muscles   .    .    .  1060 

The  Perinajum  Proper 1065 

The  Female  Perinaium 1068 

The  Mammae 1069 


THE   SKIN. 
By  William  Axdeksox. 


Structure  of  the  Skin 1074   I   The  Appendages  of  the  Skin 

Vessels  of  the  Skin 1076 


1077 


SECTION  X 

SURGICAL  AXD   TOPO GRAPHICAL  ANATOMY 
By  W.  H.  a.  Jacobsox 


Snperticial  Anatomy  of  the  Head  and  Neck  1080 

Cranio-cerebral  Topography  ....  1086 

The  Heatl  and  Face 1091 

The  Eyelids  and  Lachrymal  Appara- 
tus    1092 

The  Mouth 1095 

The  Palate 1097 

The  Nose 1097 

The  Neck ,  1099 

Superficial  Auatomv  of  the  Thorax     .    .    ,  1108 

The  Abdomen  .    _    ". 1114 

The  Periuseum  and  Genitals 1122 

Female  External  Genitals 1129 

Hernia 1131 

Parts  involved  in  Inguinal  Hernia  .    .  1131 

Parts  involved  in  Femoral  Hernia  .    .  1137 

Parts  involved  in  Umbilical  Hernia    .  1141 


The  Back 1142 

Superficial  Anatomv  of  the  Upper  Limb    .  1149 

The  Shoulder  ' 1149 

The  Elbow 1155 

The  Forearm 1159 

The  Wrist  and  Hand 1163 

The  Lower  Extremity 1172 

The  Thigh 1172 

The  Buttocks 1180 

The  Knee 1182 

The  Popliteal  Space 1186 

The  Leg 1188 

The  Ankle 1194 

The  Foot 1198 

Arches  of  the  Foot  ........  1202 

The  Regions  of  the  Abdomen 1206 


SECTION    XI 


VESTIGIAL  AXD  ABXORMAL  STRUCTURES 


By  Arthur  Eobixson 


The  Skeleton 1209 

The  Skull 1209 

The  Sternum 1210 

The  Ribs       1210 

Upper  Limb 1211 

Humerus 1211 

The  Lower  Limb 1211 


The  Nervous  Svstem  . 
The  Eye  ..'.... 
Vascular  System  .  .  . 
Genito-Urinarj-  System 

Female 

Male 

Integument      .... 


1211 
1212 
1213 
1214 
1214 
1215 
1215 


INDEX 1217 


LIST    OF    ILLUSTRATIONS 


FIG.  PAGE 

1 .  The  Tibia  ami  Fibula  in  section  to  show  the  Epiphyses, 3 

2.  A  Vertebral  Centrum  in  section  to  show  the  Pressure  Curves, 4 

3.  A  I)i;igram  to  show  the  Pressure  and  Tension  Curves  of  the  Femur,    .    .    After  Wagstaffe,  4 

4.  A  Diagram  showing  Pressure  and  Tension  Curves  in  the  Head  of  the  Humerus, 

After  Wagstaffe,  4 

5.  A  Thoracic  Vertebra  (side  view),      6 

6.  A  Thoracic  Vertebra, 6 

7.  A  Cervical  Vertebra, 7 

8.  The  First  Cervical  Vertebra  or  Atlas, 8 

9.  The  Axis 8 

10.  The  Cervical  Vertebrae  (anterior  view)  {Colotired), 9 

11.  The  Cervical  Vertebraj  (po.sterior  view)  {Coloured), 10 

12.  Peculiar  Thoracic  Vertebrae,      11 

13.  A  Lumbar  Vertebra  (side  view), 13 

14.  A  Lumbar  Vertebra.     (Showing  the  compound  nature  of  the  transverse  process.      Upper 

view),      13 

15.  Variation  in  the  Fifth  Lumbar  Vertebra, ; After  Turner,  14 

16.  A  Variation  in  the  Fifth  Lumbar  Vertelira, After  Turner,  14 

17.  The  Sacrum  and  Coccyx  (anterior  view)  (Co?OM»-e(7), 15 

18.  The  Sacrum  (posterior  view)  (Coloured), 16 

19.  Base  of  Sacrum, 16 

20.  The  Spine  (lateral  view),         18 

21.  A  Divided  Thoracic  Vertebra, After  Turner,  19 

22.  A  Vertebra  at  Birth, 20 

23.  Lumbar  Vertebra  at  the  Eighteenth  Year  with  Secondary  Centres, 20 

24.  Immature  Atlas  (third  year), 21 

25.  Development  of  the  Axis,      21 

26.  The  Axis  (from  an  Adult)  in  Section,      21 

27.  An  Immature  Cervical  Vertebra,      22 

28.  0-!sificatiou  of  the  Fifth  Lum])ar  Vertebra, 22 

29.  ^lorpbology  of  the  Transverse  and  Articular  Processes,      23 

30.  The  Occii)ital  (external  view)  {Coloured), .    .  25 

31.  Occipital  Bone,  Cerebral  Surface,      26 

3-2.  Cerebral  Surface  of  the  Occipital,  showing  an  Occasional  Disposition  of  the  Channels,    .    .  27 

33.  The  Foramen  IMaguum  at  the  Sixth  Year, 27 

34.  The  Occipital  at  Birth  (anterior  view), 28 

35.  The  Occipital  with  a  Separate  Interparietal, 29 

36.  The  Sphenoid  (viewed  from  aliove), 30 

37.  The  Left  Half  of  the  Sphenoid, 31 

38.  The  Sphenoid  (anterior  view), 31 

39.  Pigbt  Half  of  Sphenoid  (anterior  view)  {Coloured), 32 

40.  The  Under  Surface  of  Pre-sphenoid  at  the  Sixth  Year, 33 

41.  The  Sphenoid  at  Birth, 34 

4*2.  Tile  Jugum  Sphenoidale, 34 

43.  The  Left  Temporal  Bone  (outer  view), 35 

44.  The  Left  Temporal  Bone  (inner  view), 36 

45.  The  Foramina  in  the  Fundus  of  the  Left  Internal  Auditory  Sleatus  of  a  Child  at  Birth 

(|)  (diagrammatic), 36 

46.  The  Ijcft  Temporal  Bone  (inferior  view) 37 

47.  Temporal  Bone  with  Muscle  Attachments  {Coloured),      38 

4H.  The  Inner  Wall  of  Tvmpanum  (Coloured), "^0 

49.  The  Left  Osseous  Labyrinth  (from  a  cast), After  Henle,  41 

50.  The  Cochlea  in  Sagittal  Section, After  Henle,  42 

51.  The  Temiioral  Bone  at  Birth  (outer  view), ^3 

52.  Temporal  Bone  at  Birth  (inner  view), ^3 

53.  Temporal  Bone  at  the  Sixth  Year, ■*"* 

*  xvii 


xviii  LIST  OF  ILLUSTRATIONS 

HG.  PAGE 

54.  The  Left  Parietal  (outer  surface », 45 

55.  The  Left  Parietal  ^iimer  surface), 45 

56.  The  Frontal  (anterior  view), 4(> 

57.  The  Frontal  Bone  (inferior  view), 47 

58.  The  Frontal  lione  at  Birth, 48 

59.  Section  through  the  Nasal  Fossa  to  show  the  Mesethmoid, 49 

60.  The  Ethiuoicr(side  view),            50 

6L  Section  throujih  the  Nasal  Fossa  to  show  the  Lateral  Mass  of  the  Ethmoid.     It  shows  also 

the  Outer  Wall  of  the  Left  Nasal  Fo.ssa, 51 

62.  The  Splieuoidal  Turhinal  at  the  Sixth  Year, , 51 

63.  The  Sphenoidal  Turhiuals  from  an  Old  Skull, 52 

64.  The  Inferior  Turhinal,  Adult  Sphenoidal  Turbinal  and  Lachrymal  Bones, 52 

65.  Tlie  Vomer  (side  view), 54 

66.  The  Left;  Nasal  Bone, •  54 

67.  The  Left  Maxilla  (outer  view), 56 

68.  The  Left  Maxilla  (inner  view), 56 

69.  The  Maxilla  at  Birth, 57 

70.  Palate  (Left)  Bone  (inner  view), 59 

71.  Palate  Bone  (posterior  view), 60 

72.  The  Left  :\lalar  Bone, 61 

73.  Tlie  Mandible  (outer  view)  (Co^owrefZ), 63 

74.  The  Mandible  (inner  view)  (C'o/oitrerf), 64 

7.'..  The  Mandible  at  Birth, 65 

76.  The  Skull  of  an  Old  Woman  Eightj^-three  Years  Old,  to  show  the  Changes  in  the  Mandible 

and  Maxilla, 65 

77.  The  Hyoid, 66 

78.  The  Bones  of  the  Ear, 3Iodified  from  Henle,  68 

79.  The  Skull  (norma  lateralis)  (Co/owrerf), 69 

80.  A  Section  of  the  Skull,  showing  the  Inner  Wall  of  the  Orbit,  the  Inner  Wall  of  the 

Antrum,  and  the  Spheno-niaxillarv  Fossa, 71 

81.  Hard  Palate  of  a  Child  Five  Years  Old, 72 

82.  The  Skull  (norma  basilaris)  [Coloured), 74 

83.  The  Skull  (norma  basilaris) 75 

84.  The  Skull  (norma  facialis)  {Coloured), 76 

85.  The  Skull  (norma  facialis), 77 

86.  The  Inner  Wall  of  the  Orbit, 78 

87.  Section  through  the  Nasal  Fossa  to  show  the  Septum.     Left  Half,  with  Septum  looking 

towards  Right  Nasal  Fossa, 79 

88.  Section  through  the  Nasal  Fossa  to  show  the  Outer  Wall  with  the  Meatuses, 80 

89.  The  Posterior  Nares 81 

90.  The  Skull  in  Sagittal  Section, 82 

91.  The  Skull  in  Horizontal  Section, 84 

92.  The  Skull  in  Horizontal  Section 85 

93.  The  Teeth  of  an  Adult, 87 

94.  A  Molar  Tooth  in  Section,  and  a  Canine  Tooth, 87 

95.  The  Temporary  Teeth, 88 

96.  The  Chondro-cranium, 90 

97.  The  Cranium  at  Birth, 91 

98.  The  Cranium  at  Birth 91 

99.  The  Cranium  at  Birth  in  Sagittal  Section  {Coloured), 92 

100.  The  Occipital  at  Birth,      92 

101.  The  Sphenoid  at  Birth,      93 

102.  The  Temporal  Bone  at  Birth, 93 

103.  The  Temporal  Bone  at  Birth  (outer  view), .    .  94 

1(»4.  Tenijioral  Bone  at  I'.irth  (inner  view), 94 

10.-).  The  Frontal  at  Birth, 94 

106.  The  Maxilla  at  Birth 95 

107.  The  Mandible  at  Birth, 95 

108.  The  Seventh  Rib  of  the  Left  Side  (seen  from  below), 99 

109.  First  and  Second  Rihs  {Coloured), 100 

110.  The  Vertebral  Ends  of  Tenth,  Eleventh,  and  Twelfth  Ribs, 101 

HI.   Rib  at  Pubertv, 102 

112.  The  Thorax  at  the  Eighth  Month  (Co/owm/), 103 

113.  The  Sternum  (anterior  view)  {Coloured), 105 

114.  The  Sternum  (posterior  view)  (Co/oHn'</),       106 

115.  Posterior  Surface  of  the  Manubrium  (Presternum),  with  Sternal  Ends  of  Clavicle  and 

the  First  Costal  Cartilage  (Crt/oHm/),     .                    107 

116.  Two  Stages  in  the  Formation  of  the  Cartilaginous  Sternum, After  Euge,  108 

117.  The  Thorax  (front  view),      109 

118.  The  Left  Clavicle  (superior  surface)  {Coloured), 110 

119.  The  Left  Clavicle  (inferior  surface)  {Coloured), 110 

120.  The  Left  Scapula  (dor.'sal  .surface)  {Coloured), 112 

121.  The  Left  Scapula  (ventral  .surface)  (Co/owmZ), 113 

122.  Ossification  of  the  Scapula,      115 


LlSl   OF  ILLVSTRATIOXS  xix 

FIG.  I'AGE 

123.  The  Left  Humerus  (anterior  view)  (Coloured), 116 

124.  The  Left  Humerus  (posterior  view)  {Coloured), 117 

125.  The  Left  Humerus  with  a  .Supracoudyloid  Process  and  some  Irregular  Muscle  Attach- 

ments (anterior  view)  (Coloured), 118 

126.  Ossilicatiou  of  the  Humerus, 119 

127.  The  Head  of  the  Humerus  at  the  Sixth  Year  (in  section), 121 

128.  Upper  End  of  Lel't  Ulna  (outer  view)  (C'oZoM/erf), 122 

129.  The  Left  Ulna  and  Radius  (antero-internal  view)  (CoZowred), 123 

130.  The  Left  Ulna  and  Kadius  (postero-exterual  view)  (Co/o»r(Y/), 124 

131.  Articuhxr  Facets  on  the  Lower  End  of  Left  Kadius  and  Ulna, 126 

132.  Posterior  View  of  tlie  Lower  End  of  the  Eadius  and  Ulna, 126 

133.  Ossification  of  the  Radius  and  Uhui,     .    •     • 127 

131.  Tiie  Left  Hand  (dor.sal  surface)  ((V,/oum/), 129 

135.  The  Left  Hand  (palmar  surface)  (Coloured), 130 

136.  The  Left  Scaphoid, 131 

137.  The  Lett  Semilunar,      :    .    .    .    .  131 

138.  The  Left  Cuneiform, 131 

139.  The  Lett  Pisiform 131 

140.  The  Left  Trapezium, 131 

141.  The  Left  Trapezoid, 132 

142.  The  Left  Magnum, 132 

143.  Tlie  Left  Unciform, 133 

144.  The  First  (Left)  Metacaipal, 134 

145.  The  Second  (Left)  Metacarpal, 134 

146.  The  Third  ( Lett )  Metacarpal 135 

147.  The  Fourth  (Left)  Metacarpal, 136 

14s.  The  Fifth  (Left)  Metacarpal, 136 

149.  The  Phalanges  of  the  Third  Diyit  of  the  Hand  (Dorsal  view), 137 

150.  Ossification  of  the  Metacarpals  and  Phalanges, 138 

151.  Tlie  Lett  Hip-bone  (internal  surface)  (Coloured), 140 

152.  The  Lett  Hip-bone  (posterior  view)  (Coloured), 141 

153.  An  Immature  Innominate  Bone,  sliowing  a  Cotyloid  Bone,      142 

154.  The  Pelvis  of  a  Ffjetus  at  Birth,  to  show  the  Three  Portions  of  the  Innominate  Bones,    .  142 

155.  Hip-bone,  showing  Secondary  Centres,      144 

156.  Hip-bone  (inner  surface)  at  the  Eighth  Year, 144 

157.  Tlie  Pelvis  (Male),      145 

15s.  The  Left  Femur  (anterior  view)  (Coloured), 148 

159.  The  Lett  I'eniur  (posterior  view)  {Coloured), 149 

160.  Tlie  Femur  at  Birth 150 

161.  The  Lett  Femur  at  the  Twentieth  Year  (posterior  view), 151 

162.  The  Left  Patella, 152 

163.  The  Left  Tibia  and  Fibula  (anterior  view)  (Co/oMrerf), 154 

164.  The  Left  Tibia  and  Fibula  (posterior  view)  (Co/oKrpd), 155 

165.  The  Tibia  and  Fibula  at  the  Sixteenth  Year, 157 

166.  The  Left  Foot  (dorsal  surface)  (Co/o«m/), 160 

l(i7.  The  Left  Foot  (plantar  surface)  (Coloured), 161 

168.  The  Left  Astragalus  (plantar  view), 162 

169.  An  Astragalus  with  the  Os  Trigonum, 162 

170.  The  Left  Calcaneum  (dorsal  view), 164 

171.  The  Calcaneum  at  the  Fifteenth  Year,  showing  the  Epiphysis, 164 

172.  The  Left  Cuboid  (inner  view), ' 1«5 

173.  The  Left  Cuboid  (inner  view), 165 

174.  The  Left  Cuboid  (inner  view), 165 

175.  The  Left  Scaphoid  (anterior  view), 166 

176.  The  Left  Scaphoid,  showing  a  Facet  for  the  Cuboid,      166 

177.  The  Left  Internal  Cuneiform  (internal  surface),      167 

178.  The  Left  Internal  Cuneitbrm  (external  surface), 167 

179.  The  Left  Middle  Cuneitbrm  (internal  surface), 168 

180.  The  Left  Middle  Cuneiform  (external  surface) 168 

181.  The  Lett  External  Cuneiform  (internal  surface), 168 

182.  The  Left  External  Cuneiform  (external  surface), 169 

183.  The  First  (Left)  Metatarsal, 169 

184.  The  Second  (Left)  Metatarsal, 1*0 

1^5.  The  Third  (Left)  Metatarsal 1"! 

186.  The  Fourth  (Left)  Metatarsal, 1"1 

187.  The  Fifth  (Left)  Metatarsal, l~"-2 

188.  The  Phalanges  of  the  Middle  Toe l^j^ 

189.  .\  Longitudinal  Section  of  the  Bones  of  the  Lower  Limb  at  Birth, IJ-^ 

19(1.  The  Secondary  Ossific  Centres  of  the  Foot 1~-1 

191.  External  View  of  Temporo-inandihular  Joint 181 

192.  Internal  View  of  Temporo-niandibular  .Toint 181 

193.  Vertical  Section  through  the  Condyle  of  Jaw  to  show  the  Two  Synovial  Sacs  and  the 

Interarticular  Fibro-cartilage, 182 

194.  Anterior  View  of  the  Upper  End  of  the  Spine, 184 


LIST  OF  ILLUSTRATIOXS 


TAGE 


195  Yertioal   Autero-posterior   Section  of  Spinal  Column    through    Median    Line,  sliowing 

Ligaments,      1B6 

196  Horiz<)utal  Section  through  the  Lateral  Masses  of  the  Atlas  and  the  Top  of  the  Odontoid 

I'locess, 187 

197.  The  Superficial  Layer  of  the  Posterior  Common  Vertebral  Ligament  has  been  removed 

to  show  its  Deep  or  Short   Fibres.     These   Deep   Fibres  form  the  Occipito-cervical 

Ligament, 188 

198.  Vertical  Transverse  Section  of  the  Spinal   Column  and  the  Occipital  Bone  to  show 

Ligaments,      189 

199.  Horizontal  Section  through  an  Intervertebral  Disc  and  the  corresponding  Eibs,      ....  191 

200.  The  Anterior  Common   Ligament  of  the  Spine,  the  Stellate,  Interaiticular,  and   the 

Superior  Costotransverse  Ligaments, 191 

201.  Posterior  Common  Ligament  of  the  Spine  (thoracic  region), 192 

202.  Posterior  Common  Ligament  (lumbar  region), 193 

203.  Ligamenta  Siil)(lava  in  the  Lumbar  Region,  seen  from  within  the  Spinal  Canal,    ....  195 

204.  Side  View 'of  Ligamentum  Nuohfe, 196 

205.  The  Interspinous  and  Supraspinous  Ligaments  in  the  Lumbar  Eegion, 197 

206.  Anterior  View  of  the  Ligaments  between  the  Spine  and  Pelvis, 199 

207.  Vertical  Antero-posterior  Section  of  the  Pelvis, 201 

208.  Sacro-sciatic  Ligaments  (posterior  view),      203 

209.  Ligaments  connecting  Sacrum  and  Coccyx  posteriorly,      20-1 

210.  Anterior  View  of  the  Symphysis  Pubis  l^Male),  showing  the  Decussation  of  the  Fibres  of 

the  Anterior  Ligament, 206 

211.  Anterior  View  of  the  Symphysis  Pubis  (Female),  showing  greater  Width  between  the 

Bones, 206 

212.  Posterior  View  of  the  Symphysis  Pubis,  showing  the  Backward  Projection  of  the  Sym- 

physial  Suljstance  and  the  Decussation  of  the  Fibres  from  the  Inferior  Pubic  Ligament,  207 

213.  Section  of  Symphysis  to  show  the  Synovial  Cavity, 207 

214.  The  Capsular  Ligaments  of  the  Costo-vertebral  Joints, 209 

215.  Showing  the  Anterior  Common  Ligament  of  the  Spine,  and  the  Connection  of  the  Ribs 

with  the  Vertebree, 209 

216.  Horizontal  Section  through  the  Intervertebral  Disc  and  Ribs,      210 

217.  The  Sternum,      213 

218.  Diagram  of  Axis  of  Rilj-movement After  Kirkes,  215 

219.  Posterior  View  of  the  Steruo-costo-clavicular  Joint, 217 

220.  Anterior  View  of  the  Steruo-costo-cLivicular  Joint, 217 

221.  Section  through  Sterno-clavicular  Joint, 218 

222.  Anterior  View  of  Shoulder,  showing  also  Coraco-clavicular  and  Coraco-acromial   Liga- 

ments,         220 

223.  Posterior  View  of  the  Shoulder-joint,  showing  also  the  Acromio-clavicular  Joint  and  the 

Si)ecial  Ligaments  of  the  Scapula, 222 

224.  Vertical  Section  tlirough  the  Shoulder-joint  to  show  the  Gleno-humeral  Ligament,  .    .    .  223 

225.  Fcetal  Shoulder-joint,  showing  the  Gleno-humeral  Ligament,  and  also  the  Short  Head 

of  the  Biceps,  being  continuous  with  the  Coraco-acromial  Ligament, 224 

226.  Outer  View  of  the  Shoulder-joint,  showing  the  Coraco-humeral  and  Transverse  Humeral 

Ligaments, 224 

227.  Biceps  Tendon,  bifurcating  and  Blending  on  each  Side  with  the  Glenoid  Fibro  cartilage,  225 

228.  Internal  View  of  the  Elbow-joint,      . 228 

229.  External  View  of  the  Elbow-joint, 228 

230.  Orbicular  Ligament 230 

230  A.  Upper  Portions  of  Left  Ulna  and  Radius  with  Oblique  and  Orbicular  Ligaments  :  to 

show  an  Occasional  Slip  from  the  Oblique  Ligament  to  the  Lower  Part  of  the  Orbic- 
ular Ligament, 231 

231.  Anterior  View  of  Wrist 234 

232.  Posterior  View  of  AVrist, 235 

233.  Front  of  Wrist  with  Anterior  Annular  Ligament 236 

234.  Posterior  View  of  Wrist,  with  Capsule  cut  to  show  Articular  Surfaces, 238 

235.  Synovial  Membranes  of  Wrist,  Hand,  and  Fingers, 239 

236.  Anterior  and  Posterior  View  of  Ligaments  of  the  Fingers, 244 

237.  Anterior  View  of  the  Capsule  of  the  Hip-joint, 247 

238.  Posterior  View  of  the  Capsule  of  the  Hip'-joint 248 

239.  Section  through  the  Hip-joint,  showing  the  Cotvloid  Ligament,  Ligamentum  Teres,  and 

Retiiiacula,      ' 249 

240.  Hip-joint  after  dividing  the  Capsular  Ligament  and  disarticulating  the  Femur,      ....  250 

241.  Portions  of  Ischium  and  Pubes,  showing  the  Cotyloid  Notch  and  the  Ligamentum  Teres 

attached  outside  the  Acetal)ulum,      250 

242.  Ligamentum  Teres,  lax  in  Flexion, 251 

243.  Ligamentum  Teres,  very  lax  in  complete  Extension 252 

244.  Ligamentum  Teres,  drawn  tiglit  in   Flexion  combined   with   Rotation  outwards  and 

Adduction, 253 

245.  Posterior  View  of  the  Knee-joint, 255 

246.  Anterior  View  of  the  Internal  Ligaments  of  the  Knee-joint, 256 

247.  Structures  lying  on  the  Head  of  the  Tibia  (right  kneelj 257 

248.  Anterior  View  of  the  Knee-joint,  showing  the  Synovial  Ligaments, 258 


LIST  OF  ILL  i  STRA  TIONS  xxi 

FIG.  PAGE 

249.  Vertical  Section  of  the  Knee-joint  in  the  Antero-posterior  Direction, 260 

2.i().   The  Lateral  Lijianieuts  ot  the  Knee  in  Flexion  and  Extension 261 

251.  Section  ol'  Knee,  showing  Crncials  in  Extension,    .    .    .    .  ' 262 

252.  Crucial  Ligaments  in  Flexion, 263 

252  A.  Lower  Ends  of  Left  Tibia  and  Fibula,  showing  the  Ligaments, 265 

252  B.  Right  Ankle-joint,  showing  the  Ligaments, 266 

253.  Inner  View  of  the  Ankle  and  the  Tarsus,  showing  the  Groove  for  tlie  Tendon  of  the 

Tibialis  Posticus, 267 

254.  Ligaments  seen  from  the  Back  of  the  Ankle-joint, 268 

255.  External  View  of  the  Ligaments  of  the  Foot  and  Ankle, 271 

256.  View  of  the  Foot  from  al)ove,  with  the  Astragalus  removed   to  show  the  Inferior  and 

External  Calcaneo-scaphoid  Ligaments, 274 

257.  Ligaments  of  the  Sole  of  the  Left  Foot, 275 

258.  Section  to  show  the  Sj'novial  Cavities  of  the  Foot, 278 

259.  Diagram  showing   Peuniform   Muscle,    the   Peroneus  Longus  ;   and   Bipenniform,  the 

Tibialis  Posticus, 284 

260.  Diagram  illustrating  the  advantage  of  Oblique  Insertion  of  Tendons, 286 

261.  Diagram  illustrating  the  advantage  of  Oblique  In!-eitiou  of  Tendons, 287 

262.  I^irst  Layer  of  Muscles  of  the  Back,      289 

263.  The  Levator  Anguli  Scapulte  and  Khomboidei, 291 

264.  The  Pectoralis  Major  and  Deltoid, 295 

265.  The  Subclavius  and  the  Upper  I'oition  of  the  Sen atus  Magnus, 296 

266.  The  Pectoralis  Minor,  Obliquus  Internus,  Pyramidalis,  and  Rectus  Abdominis,     ....  297 

267.  Serratus  Magnus, 299 

268.  Back  View  of  the  Scapular  Muscles  and  Triceps, 302 

269.  Front  View  of  the  Scapular  IMuscles, 304 

270.  Superficial  View  of  the  Front  of  the  Upper  Arm, 306 

271.  Deep  View  of  the  Front  of  the  Upper  Arm, 308 

272.  Front  of  the  Forearm  :  First  Layer  of  Muscles, 312 

273.  Front  of  the  Forearm  :  Second  Layer  of  Muscles, 316 

274.  Diagram  of  the  Great  Palmar  Bursa, 317 

275.  Front  of  the  Forearm  :  Third  Layer  of  Muscles, 319 

276.  Muscles  of  the  Radial  Side  and  the  Back  of  the  Forearm, 322 

277.  Tendons  upon  the  Dorsum  of  the  Hand, 325 

278.  The  Deep  Layer  of  the  Back  of  the  Forearm 329 

279.  Diagram  of  a  Vertical  Section  through  the  .Middle  of  the  Hand, 334 

280.  The  Superficial  Muscles  of  the  Palm  of  the  Hand, 336 

281.  The  Palmar  luterossei, 3:'>7 

282.  The  Dorsal  luterossei, 338 

283.  The  Deeper  JMuscles  of  the  Palm  of  the  Hand, 340 

284.  The  Pronator  Quadratus  and  Deep  View  of  the  Palm, 342 

285.  Obliquus  Externus  and  Fascia  Lata,      345 

286.  Psoas,  Iliacus,  and  Quadratus  Lumborum, 347 

287.  Muscles  of  the  Front  of  the  Thigh 349 

288.  The  External  Rotators  and  the  Hamstring  Muscles, 355 

289.  The  Deep  Muscles  of  the  Front  of  the  Thigh, 3o9 

290.  The  Deep  Muscles  of  the  Back  of  the  Thigh,  .    .        360 

291.  Superficial  Muscles  of  the  Back  of  the  Thigh  and  Leg, 370 

292.  The  Deep  Muscles  of  the  Back  of  the  Leg 375 

293.  First  Layer  of  the  ISIuscles  of  the  Sole, 378 

294.  Second  Layer  of  the  Muscles  of  the  Sole, 380 

295.  Third  Layer  of  the  Muscles  of  the  Sole, 383 

296.  Fourth  Layer  of  the  Muscles  of  the  Sole, 386 

297.  The  Muscles  of  the  Front  of  the  Leg, 388 

298.  The  Muscles  of  the  Dorsum  of  the  Foot,      390 

299.  The  External  Intercostals  and  Levatores  Costarum, 394 

300.  The  Intercostal  Muscles, 396 

301.  The  Muscles  attached  to  the  Back  of  the  Sternum, 398 

302.  Diaphragm,      400 

303.  External  Oblique  and  Ilio-tibial  Band,      405 

304.  Transversalis  Abdominis  and  Sheath  of  Rectus 409 

305.  The  Third  and  Fourth  Layers  of  the  Muscles  of  the  Back, 412 

306.  The  Fifth  Layer  of  the  Muscles  of  the  Back,       416 

307.  Tlie  Filth  Layer  of  the  Muscles  of  the  Back,  after  separating  the  Outer  and   Middle 

Divisions, 418 

308.  The  Sixth  Layer  of  the  Mn.scles  of  the  Back 421 

309.  The  Superficial  Muscles  of  the  Head  and  Neck, 427 

310.  The  Tensor  Tarsi  and  Corrugator  Supercilii 430 

311.  The  Deeper  Laver  of  the  Muscles  of  the  Face  and  Neck, 435 

312.  The  Temporal  Muscle 442 

313.  The  Pterygoid  Muscles 443 

314.  Anterior  and  Lateral  Cervical  Muscles 446 

315.  Side  View  of  the  Muscles  of  the  Tongue, 453 

316.  The  Muscles  of  the  Front  of  the  Neck, 456 


xxii  IJST  OF  ILLUSTRATIONS 

J.- Hi.  PAGE 

Ml.  Auterior  View  of  the  Heart  with  the  Large  Arteries  ami  Veins  (To/oioyy/) 463 

;>I8.  The  Heart,  with  the  Arch  of  the  Aorta,  the  Pulmonary  Artery,  the  Ductus  Aiteriosus, 

and  the  Vessels  concerned  in  the  Fa-tal  Circuhition  (Co/oM>«/ 1, 464 

:;i9.  Diagram  of  the  Kelations  of  the  Pulmonary  Artery  and  its  Right  and  Left   Branches 

{ColournD, ]l'alsham  465 

;>20.   Posterior  View  of  Heart  and  Greater  Vessels  (fWoMJ-ed), 465 

321.  The  Arch  of  the  Aorta,  with  the  Pulmonary  Artery  and  Chief  Branches  of  the  Aorta 

{Coloured), 467 

322.  Scheme  of  the  Relations  of  the  First  Portionof  the  Arch  of  the  Aorta  (Coloured),  U'alsliam  468 

323.  Sclieme  of  the  Relations  of  the  Transverse  Portion  of  the  Arch  of  the  Aorta  [Coloured),  469 

Walshavi 

324.  The  Heart  and  Great  Vessels,  with  the  Root  of  the  Lungs,  seen  from  behind  {Coloured),  470 

325.  Scheme  of  the  Kelations  of  the  Third  Portion  of  the  Arch  of  the  Aorta  {Coloured),      .    .  471 

Wulsliam 

326.  Scheme  of  the  Coronary  Arteries  [Coloured),       Wuhham  473 

327.  Scheme  of  the  Relations  of  the  Innominate  Artery  (Co/oMrec/), Walshom  474 

328.  Scheme  of  the  Relations  of  the  Left  Common  Carotid  and   Left  Subclavian   Arteries 

within  the  Thorax  {Coloured), Walsham  476 

329.  The  Common  Carotid,  the  External  and  Internal  Carotid  and  the  Subclavian  Arteries 

of  the  Right  Side  and  their  Branches  (Co/oiurt/), 477 

330.  The  Collateral   Circulation  after   Ligature  of  the  Common  Carotid  and  Subclavian 

Arteries  {Coloured),      478 

331.  Scheme  of  Right  Ascending  Pharyngeal  Artery  {Coloured),      Walshnm  481 

332.  Scheme  of  Left  Superior  Thyroid  Artery  (Co/owrefZ), M'alsham  483 

333.  Scheme  of  the  Right  Lingual  Artery  (Co?o«;«/), Wahham  484 

334.  Scheme  of  the  Right  Facial  Artery  (rWo»)vf/), Walsham  486 

335.  Scheme  of  Right  Occipital  and  Posterior  Auricular  Arteries  (Co/oured),    .    .    .     Walsham  489 

336.  Scheme  of  Left  Internal  Maxillary  Artery  {Coloured), Walsham  493 

337.  The  iMiddle  Meningeal  Artery  within  the  Skull  (Co/oftm/), 494 

338.  The  Internal  Carotid  Artery,  and  Deep  Branches  of  the  External  Carotid  Artery,  Left 

Side  {Coloured), 497 

339.  The  Left  Ophthalmic  Artery  and  Vein  (Co/owrerf), 500 

340.  The  Arteries  of  the  Brain  [Coloured), 5(i4 

341.  The  Right  Subclavian  Artery  (Co/o«m/),      .  507 

342.  Scheme  of  the  Left  Vertebral  Artery  (Co/o?<rerf), Wahham  509 

343.  Scheme  of  Anastomoses  of  the  Right  Scapular  Arteries  (CoZowrerf), Walsham  515 

344.  Scheme  of  the  Right  Internal  Mammary  Artery  {Coloured), Walsham  517 

345.  Scheme  of  the  Right  Superior  Intercostal  Arterj'  {Coloured), Walsham  519 

346.  The  Lower  Part  of  the  Axillary,  the  Brachial,  and  the  Radial  and  Ulnar  Arteries,  Right 

Side  {Coloured), 522 

347.  The  Dorsal  Scapular  Artery,  Right  Side  {Coloured), 523 

348.  The  Right  Posterior  Circumflex  Artery  (CWo((7T(?), 524 

349.  The  Anastomoses  about  the  Scapula  (Coloured), 525 

350.  TheErachial  Artery,  Leftside  (CoZoKcerf), 527 

351.  The  Brachial  Artery  at  the  Bend  of  the  Elbow,  Left  Side,  Front  View  {Coloured),    ...  528 

352.  The  Arteries  of  the  Forearm  with  the  Superficial  Palmar  Arch  (Coloured),      .....  532 

353.  The  Back  of  the  Left  Forearm,  with  the  Posterior  Intero.sseous  Artery  and  Branches  of 

the  Radial  at  the  Back  of  the  Wrist  (Co/o«<m/), 534 

354.  Anastomoses  and  Distribution  of  the  Arteries  of  the  Hand  (Coloured),      .    .    .     Walsham  536 

355.  The  Arteries  of  tlie  Right  Forearm  and  the  Deep  Palmar  Arch  {Coloured), 537 

356.  Diagram  of  the  Relation  of  the  Arteries  of  the  Left  Forearm  to  the  Bones  {Coloured),      .  539 

Walsham 

357.  The  Bend  of  the  Elbow,  Left  Side  {Coloured), 540 

358.  The  Radial  Artery  at  the  Wrist,  Left  Forearm  (Coloured), 542 

359.  Anastomoses  and  Distribution  of  the  Arteries  of  the  Hand  (Co?oH»Tf?), 544 

360.  The  Arch  of  the  Aorta,  the  Thoracic  Aorta,  and  the  A])dominal  Aorta,  with  the  Superior 

and  Inferior  Vena  Cava  and  the  Innominate  and  Azygos  Veins  (Co/oMrcrf), 546 

361.  Scheme  of  the  Thoracic  Aorta  ((WoHJTf/), Walsham  547 

362.  Scheme  of  Intercostal  Artery  (CoZojf/rrf), .          Walsham  549 

363.  The  .Vbdominal  Aorta  and  its  Branches,  with  the  Inferior  Vena  Cava  and  its  Tril)utaries 

(Coloured), 551 

364.  Scheme  of  the  Abdominal  Aorta  (Coloured), Walsham  552 

365.  The  Cceliac  Artery  and  its  Branches  (  Co/oiOYV?), 555 

366.  The  Superior  Mesenteric  Artery  and  Vein  frWoiOfr?), 559 

367.  The  Inferior  Mesenteric  Artery  and  Vein  (T'o/ofuvY?), 563 

368.  Side  View  of  Pelvis  and  Upper  Third  of  Thigh,  with  the  E.xternal  Iliac,  Internal  Iliac, 

and  Femoral  Arteries  and  their  Branches,  Left  Side  (Co/(>«/«/), 566 

369.  The  Gluteal  Reirion,  with  the  Gluteal,  Sciatic,  and  Pudic  Arteries  (Co?o«mO, -''68 

370.  Scheme  of  the  Ovarian  and  ITterine  and  Vaginal  Arteries  (Co/owrer/), 571 

370a.  The  Arteries  of  the  Perina-um  (CrtA)/n«f),      574 

371.  Scheme  of  the  Pndic  Artery  and  its  lininches  fCo/o«>Tf/), 575 

372.  The  Femoral -Artery  in  Scarpa's  Triangle  (ro/ofoTf?) 580 

373.  To  show  the  Anastomoses  of  the  Arteries  of  the  Lower  Extremity  (Co?o!<>Y(Z), 582 

After  Smith  and  Walsham 


LIST  OF  ILL  USTRA  TIOXS  x.x iii 

FIG.  PAGK 

374.  Relations  of  the  Popliteal  Artery  to  r>one.s  and  Muscles,  Left  Side  (Co/o«rerf), 587 

375.  Side  View  of  the  Right  Popliteal  Artery  [Colonrcil), 588 

'Mii.  The  Anastomo.sis  about  the  Left  Kuee-joint  {Co/o«?-fd), Walsham  589 

377.  The  Popliteal,  the  Po.sterior  Tibial,  and  the  Peroneal  Artery,  Right  Side  (Coloured),    .    .  591 

378.  The  Plantar  Arteries,  Left  Foot  (r'o/o((m/),      594 

379.  Right  Plantar  Arteries  (Deep)  {Coloured), 595 

380.  The  Anterior  Tibial  Artery,  Dorsal  Artery  of  the  Foot,  and  Anterior  Peroneal  Artery, 

and  their  Branches,  Left  Side  (^'o/oKca/), 597 

381.  Scheme  of  the  Distribution  and  Anastomoses  of  the  Arteries  of  the  Right  Foot  (Coloured),  599 

Walaham 

381a.  The  Vena  Cava  Superior  and  the  Innominate  Veins  (Colotired), 604 

382.  The  Superior  and  Inferior  Venae  Cavaj,  the  Innominate  Veins,  and  the  Azygos  Veins 

[Coloured], 607 

383.  The  Coronary  Sinus  (CoZojtmZ), ''09 

384.  Scheme  of  the  Coronary  Veins  (C«/o«r«Z  I, Walsham  610 

385.  The  Superficial  Veins  and  Lymphatics  of  the  Scalp,  Face,  and  Neck  (Coloured),  WaMam  612 

386.  The  Veins  of  the  Diploe  (CoZojtm/), .; <|1^ 

387.  The  Venous  Sinuses  (Coloured),  .    . 620 

388.  The  Venous  Sinuses  (longitudinal  section)  (rWfHtred), 621 

389.  The  Veins  of  the  Orbit  (Co/o?(mO, ^-^ 

390.  The  Spinal  Veins  (Coloured), 6^9 

391.  The  Abdominal  Aorta  and  Inferior  Vena  Cava  (Co/ottrcrf), .    .  632 

392.  The  Veins  of  the  Stomach  and  the  Portal  Vein  (CoZoMrerf), Walsham  635 

393.  The  Superior  Mesenteric  Vein  (Co/oMre<Z), 636 

394.  The  Interior  Mesenteric  Vein  (Co?OMrerf), 637 

395.  The  Bend  of  the  Elbow  with  the  Supertlcial  Veins,  Leftside  (Co/owmZ), 640 

396.  Superficial  Veins  and  Lymphatics  of  the  Left  Forearm  and  Arm  (Co/oMr«/),    .     Walsham  642 

397.  The  Superficial  Veins  and  Lymphatics  of  the  Left  Lower  Limb  (Co/oHre<Zj,     .     Walsham  645 

398.  The  Superficial  Lymphatics  of  the  Scalp,  Face,  and  Neck  (CWoJimft,    ....      Walsham  650 
398a.   Diagram  of  the  Superficial  Lymphatic  Vessels  and  Glands  of  the  Head  and  Neck,  .    .  651 

Afler  Skertvood 

398b.  Diagram  of  the  Deep  Lymphatic  Vessels  and  Glands  of  the  Head  and  Neck,        ....  652 

After  Sherrvood 

399.  The  Superficial  Lymphatics  of  the  Left  Upper  Limb  and  Axillary  Glands  (Coloured),   .    .  654 

Walsham 
399a.   Diagram  of  the  Superficial  and  Deep  Lymphatic  Vessels  and  Glands  of  the  Upper  Ex- 
tremity including  the  Superficial  Lymphatic  Vessels  of  the  Back  and  Chest, 657 

After  Sherwood 
399b.  Diagram  of  the  Arrangement  of  the  Lymphatics  of  the  Uterus,  Fallopian  Tubes,  Ova- 
ries, Vagina,  and  External  Vulva,     .... After  Sheru-ood  663 

400.  The  Superficial  Lymphatics  of  the  Left  Lower  Limb  (CoZojirerf), Walsham  666 

400a.  Diagram  of  the  Superficial  and  Deep  Lymphatic  Vessels  and  Glands  of  the  Lower  Ex- 
tremity, including  the  Superficial  Lymphatics  of  the  External  Genitals  and  the  Lym- 
phatics of  the  Gluteal  and  Ischial  Regions,      After  Sheru-ood  668 

401.  Diagrammatic  Sagittal  Section  of  a  Vertebrate  Brain, After  Huxley  669 

402.  Diagrammatic  Horizontal  Section  of  a  Vertebrate  Brain,      After  Huxley  670 

403.  Coronal  Section  of  the  Head  passing  through  the  Mastoid  Process, ■  673 

404.  Coronal  Section  of  the  Head  passing  through  the  Posterior  Horns  of  the  Lateral  Ventri- 

cles,         ^^"^ 

405.  The  Cranium  opened  to  show  the  Falx  Cerebri,  the  Tentorium  Cerebelli,  and  the  places 

where  the  Cranial  Nerves  pierce  the  Dura  Mater  (CoZowrerf),      ....                Sappey  67o 

406.  Coronal  Section  through  the  Great  Longitudinal  Fissure,  showing  the  Meninges,  ....  676 

Key  and  Retzius 

407.  Cranial  Nerves  in  the  Base  of  the  Skull  (CoZoitrerf), •    •  ^^"'"^ 

408.  View  ofthe  Base  of  the  Brain  (CoZowmZ), After  Beaunis  680 

409.  The  Fissures  and  Convolutions  of  the  Cerebrum,  viewed  from  above  (Co/ottred),    ....  682 

410.  Lateral  View  of  the  Fissures  and  Convolutions  of  the  Cerebrum  ((IWowrerf), 683 

411.  Convolutions  and  Fissures  on  the  Mesial  and  Tentorial   Surfaces  of  the   Hemisphere 

(Coloured),    .    .        .    .                    ,^,  •  i/','  rq^ 

412.  Mesial  Section  of  Entire  Brain Af'^r  Ii''»'<^  ''^-^ 

413.  A  Dissection  of  the  White  Matter  of  the  Posterior  Part  of  the  Right  Cerebral  Hemisphere,  ()93 

Schwnlbe 

414.  Diagrammatic  Coronal  Section  of  Third  and  Lateral  Ventricles  ( Coloured),      695 

From  Schu-alhe,  slightly  modified 

415.  Coronal  Section  of  the  Hemispheres  passing  through  the  Anterior  Coruua  of  the  Lateral 

Ventricles, i  -ir  "    '  • ' 

416.  Coronal  Section  of  the  Head  passing  through  the  Posterior  Horns  of  the  Lateral  Ventri- 

cles,                                ,  o  ■*■    ■  ' 

417.  A  Dissection  of  the  De.scending  Cornu  of  the  Lateral  Ventricle,  with  a  Sagittal  Section 

through  the  Basal  Ganglia,  .    .                '    '    'i  '    "      rri  ' 

418.  A  Dissection  showingthe  Free  or  Intraventricular  Portion  of  the  Caudate  Nucleus.     The 

Mesial  and  Tentorial  Surfaces  of  the  Hemisphere  are  also  shown.  .    . ;    •  6-' 

419.  Horizontal  Section  of  the  Cerebrum Ifter  Landois  and  Stirling  ;;^  " 

420.  Horizontal  Section  of  the  Cerebral  Hemispheres, '    * 


xxiv  LIST  OF  ILLUSTRATIONS 


FK 


4'21.  Coronal  Section  through  the  Anterior  Part  of  the  Third  Ventricle 704 

4-2-3.  Coronal  Section  throuiih  the  Middle  Commissure  of  the  Third  Ventricle,      .    .     Schwalbe  7U(J 

423!  Coronal  Section  tlirongh  the  Third  Ventricle  Ijehind  the  :Middle  Commissure,   Gegenhaur  707 

424!   Deep  Origin  of  the  Tliird  Nerve, After  K ran se  711 

425.  Lateral  View  of  Mesencephalon,  Pons,  and  Medulla, Gegenbaur  712 

426.  Inferior  Surface  of  the  Cerebellum,    ... 715 

427.  Right  Half  of  the  Encephalic  Peduncle  as  seen  from  the  Inside  of  a  Median  Section 

^Coloured) Allen  Thomson,  after  Ixciehert  718 

428    Metencephalon,    Mesencephalon,   and    Thalamencephalon,    from    the    Dorsal    Surface 

(Coloured), -^/'f'"  Obersteiner  721 

429.  Transverse  Section  through  the  Upper  Part  of  the  Pons, Sclnvalbe  722 

430.  Transverse  Section  of  the  Pons  near  the  Centre  of  the  Fourth  Ventricle,  .    .    .      Sc/nvalbe  724 
431    Trausverse  Section  of  the  Medulla  a  little  above  the  Lower  E.xtremity  of  the  Fourth 

Ventricle After  Kranse  725 

432.  Transverse  Section  of  the  Medulla  in  the  Region  of  the  Decussatio  Lemuisci,  .      Schwalbe  726 

433!  DrawingofaCastof  the  Head  of  an  Adult  Male  (Co/o((m/), Cunningham  729 

434.  Drawingof  a  Cast  of  the  Head  of  a  Newly-born  Male  Infant  (Co/oMrerf),  •    ■   Cunningham  730 

435.  Transve'r.se  Section  of  the  Spinal  Cord  and  its  Membranes,   .    .    .    .  After  Key  and  Retzius  731 

436.  View  of  the  Membranes  of  the  Spinal  Cord, •    •    ■    AV/Z.s  732 

437.  Posterior  View  of  the  Medulla  Oblongata  and  of  the  Spinal  Cord,  -^ith  its  Coverings  aud 

the  Roots  of  the  Nerves, Hirschfeld  and  Lereille  733 

438.  Anterior  aud  Posterior  View  of  the  Spinal  Cord, Modified  from  Quain  735 

439.  Sections  through  Different  Regions  of  the  Spinal  Cord, After  Schwalbe  736 

440.  Diagram  showing  Paths  Traversed  by  Sensory  aud  JNIotor  Nerve-fibres  and  their  Course 

to  aud  from  the  Corte.x  of  the  Brain  (Co/oiner/), 739 

440a.  Diagram  of  the  Tracts  of  the  Spinal  Cord  and  of  the  Deep  Origins  of  the  Spinal  Nerves 

(Coloured), •  ''^'^ 

441.  Surface  Origin  of  the  Cranial  Nerves  (CoZoiorrf),     ....     After  Allen  Thomson.— Quain  744 

442.  Nervesof  the  Nasal  Cavity  (Co/o«mO, •    •  '''^^ 

443.  Deep  Origin  of  the  Third  Nerve, ^^f(er  Krause  748 

444.  Sectious  through  the  Origin  of  the  Fourth  Nerve, Stilling  749 

445.  Nervesof  the  Orbit,  from  the  Outer  Side  (Co/oMrf^?), 751 

From  Sappey,  after  Hirschfeld  and  LeveilU 

446.  The  Maxillary  Nerve  seen  from  without  {Coloured), Bennnis  753 

447.  Distribution  of  the  IMandibular  Division  of  the  Trigeminal  Nerve, Hcnle  757 

448.  Diagrammatic  Lateral  View  of  the  Origin  of  the  Facial  Nerve, Krause  761 

449.  Superficial  Distribution  of  the  Facial  and  other  Nerves  of  the  Head  (Co/owef/),      ....  763 

After  Hirschfeld  and  LeveilU 

450.  Transverse  Section  of  the  Pons,  passing  through  the  most  Distal  of  the  Striae  MeduUares,  766 

Krause 

451.  Distribution  of  the  Pneumogastric  Nerve,  viewed  from  behind  (Co/oMrerf),   .    .    .    Krause  770 

452.  Distribution  of  the  Posterior  Primary  Divisions  of  the  Spinal  Nerves, Henle  780 

453.  Diagram  of  the  Cervical  Plexus, 782 

454.  Superficial  Branches  of  the  Cervical  Plexus  (Co/oiorr/),  .    .    .  After  Hirschfeld  and  LeveilU  784 

455.  Diagram  of  the  Brachial  Plexu.s, 786 

456.  Distriljution  of  Cutaneous  Nerves  on  the  Anterior  and  Posterior  Aspects  of  the  Superior 

Extremity, 789 

457.  A  Dissection  showing  the  Arrangement  of  the  Nerves  in  front  of  the  Elbow  (Coloured),    .  791 
457a.  Dissection  of  the  Left  Arm   from  the  Front,  Showing  Portions  of  the  Ulnar,  Median, 

Musculo  cutaneous,  and  Musculo  spiral  Nerves  (Oo/oMr«/), 792 

458.  Superficial  Nerves  of  the  Palm  (Co/oH/w/), FAlis  793 

459.  A  Di,s.section  of  the  Cutaneous  Nerves  on  the  Dorsal  Aspect  of  the  Haud  and  Fingers 

(Coloured), H.  St.  J.  B.  796 

460.  Cutaneous  Nerves  of  the  Thorax  and  Abdomen,  viewed  from  the  Side,     .    .    After  Henle  800 

461.  Diagram  of  the  Lumbar  aud  Sacral  Plexu.ses 3Iodificd  from  Paterson  803 

462.  Branches  of  the  Lumbar  and  Sacral  Plexus  viewed  from  before  (Co/oKrcf/), 804 

After  Hirsclifeld  and  Leveilh^ 

463.  Anterior  Crural  and  Obturator  Nerves  (Co/ottrerf), Ellis  806 

464.  Distribution  of  Cutaneous  Nerves  on  the  Posterior  and  Anterior  Aspects  of  the  Inferior 

Extremity,       807 

465.  Diagram  of  the  Lumbar  and  Sacral  Plexuses, 3Iodified  from  Paterson  811 

466.  A  Dis.section  of  the  Luml)ar  and  Sacral  Plexuses,  from  behind  (Co/o?o-«/), 812 

467.  A  Dissection  of  the  Nerves  in  the  Gluteal  Region  {(hloured), 813 

468.  DistriVjution  of  the  Musculo-cutanoous  and  Anterior  Tibial  Nerves  on  the  Anterior  Aspect 

of  the  Leg  and  on  the  Dorsum  of  the  Foot  (ro^oHcerf),  .    .    .    .    Hirschfeld  and  LeveilU  816 

469.  Superficial  Nerves  in  the  Sole  of  the  Foot  (fWof/m/) Ellis  818 

469.\.   Diagram  of  the  Cutaneous  Nerve  Areas  of  the  Head  and  Neck  (CoZojorrf), 822 

469b.  Diagram  showing  the  Areas  of  Distribution  of  Cutaneous  Nerves  (ro?o;rr«7)i 8-4 

470.  The  Cervical    Poition  of  the  Sympathetic  and  the  Distribution  of  the  Pneumogastric 

Nerve,  viewed  from  1)ehind  [Coloured), Krause  829 

470a 832 

471.  Luml)ar  Portion  of   the  Gangliated  Cord,    with  the  Solar  and  Hypogastric  Plexuses 

(Coloured), ...  ...  '      '.    .        .    .  IFenle  836 

472.  View  of  Eyeball,  etc.,  obtained  on  drawing  the  Lids  forciI)ly  apart, 841 

After  Merkel,  slightly  modifcd 


LIST  OF  ILLUSTRATIONS  xxv 

FIG.  PACK 

473.  Left  Fundus  Oculi,  as  seeu  by  direct  Oplitlialnioscopic  IMetliod,      842 

474.  Diagrannnatic:  View  of  the  Inseition.s  of  tho  Ocular  Muscles, After  Merkel  844 

475.  Equatorial  Section  of  Eyeball  :  Anterior  Segment  viewed  from  behind,    .    .  Aflcr  Merkel  845 
47().  Diagrammatic  Horizontal  Section  of  Eyeball  and  Orbit  (Cb/owrcf/), 847 

After  Fttclis,  mueh  modified 

All.  Semi-diagrammatic  Horizontal  Section  through  Eyeball  and  Optic  Nerve, 849 

After  E/finyer,  redueed  and  altered 

478.  Diagrammatic  Representatiou  of  the  Blood-vessels  of  the  Eyei)all  (Oi/o?<r('f/),  .    .    .Leber  851 

479.  Surface  of  Choroid  and  Iris  exposed  by  removal  of  Sclerotic  and  Cornea,  showing  DLstri- 

butiou  of  Blood-vessels  and  Nerves  (CWoHrw/)., After  Zinn  852 

480.  The  Lymphatics  of  the  Eyeball  (Co/oMie(Z I, Diagrammatic,  after  Fuchs  853 

481.  Left  Eyeball  seen  in  its  Normal  Position  in  the  Orbit,  with  View  of  the  Ocular  Muscles,  854 

After  Merkel,  modified 

482.  Section  through  Contents  of  Right  Orbit,  8-11  mm.  behind  the  Eyeball,  viewed  from 

behind  {Coloured), After  Lanr/e  855 

483.  Diagrammatic  Representations  of  Origins  of  Ocular  Muscles  at  the  Apex  of  the  Rigiit 

Orbit, V .    .    .    .  After  Sclnvalbe  856 

484.  View  of  Left  Orbit  from  above,  showing  the  Ocular  Muscles,  From  Hirschfeld  and  Lereill^  857 

485.  Vertical  Section  through  the  Eyeball  and  Orbit  in  the  direction  of  the  Orbital  Axis,  with 

Closed  Eyelids  (CWoit/erf), Semi-diagTavDnatic,  after  Sehwulhe  858 

48fi.  Horizontal  Section  through  Left  Orbit,  viewed  from  above,     ....     After  J'ouGerlaek  859 

487.  Transverse  Section  through  Optic  Nerve,  showing  the  Relations  of  its  Sheaths  and  Con- 

nective Tissue  Framework,      861 

488.  Longitudinal  Section  through  Termination  of  Optic  Nerve, o  861 

489.  The  Blood-vessels  of  the  Left  Orbit,  viewed  from  above  (Co/oMre(/), 862 

490.  Section  through  Contents  of  Right  Orbit,  1-2  mm.  in  front  of  the  Optic  Foramen,  viewed 

from  behind  (Coloured), After  Lange  863 

491.  Vertical  Transverse  Section  through  the  Upper  Eyelid,     .    .    .  After  ]Valdeijer  and  Fuels  865 

492.  Lachrymal  Apparatus, After  Selncalhe  868 

493.  External  View  of  the  Left  Auricle 870 

494.  Section  through  the  Orifice  of  the  Right  External  Auditory  Meatus, 871 

495.  External  and  Internal  Surface  of  the  Cartilage  of  the  Right  Pinna  and  its  Muscles,  etc.,  872 

496.  Section  of  the  ISIiddle  and  External  Ear, 873 

497.  External  View  of  the  Left  Membrana  Tympani, 874 

498.  Internal  View  of  Right  Membrana  Tympani  (ro/o(n-«/") 875 

498a.  Horizontal  Section  of  Left  Temporal  Bone,  showing  the  Various  Parts  of  the  Ear,  .    .    .  876 

499.  Section  of  the  Tympanum,  etc., 877 

500.  The  Osseous  Labyrinth  of  the  Right  Side, 3Iodified  from  Hnemmerring  879 

501.  Interior  of  the  Osseous  Labyrinth  of  the  Left  Side,    ....     3Iodifiedfrom  Soemmerriny  880 

502.  Interior  of  the  Osseous  Cochlea, 880 

503.  Section  of  the  Osseous  Cochlea, 881 

504.  Membranous  Labyrinth  (magnified),  with  Nerves, Modifi( d  from  Breschet  882 

505.  Enlarged  Diagrammatic  View  of  Membranous  Labyrinth, 882 

506.  Enlarged  View  of  Longitudinal  Section  of  the  First  Turn  of  the  Cochlea,  showing  the 

Positions  and  Boundaries  of  the  Three  Scala', .    .  883 

507.  Dorsum  of  the  Tongue,      885 

508.  The  F(etal  Tongue, 886 

509.  Under  Surface  of  the  Tongue  with  Muscles, H><6 

510.  Transverse  Section  through  the  Left  Half  of  the  Tongue  (magnified), 887 

511.  Side  View  of  the  Tongue,  with  its  Muscles, 887 

512.  Side  View  of  the  Nose,  showing  its  Cartilages,  etc., 889 

513.  Anterior  View  of  the  Nose,  showing  its  Cartilages,  etc., H90 

514.  Under  View  of  the  Nose,  showing  its  Cartilages,  etc., )-:91 

515.  Section  showing  Bony  and  Cartil.ngiuous  Septum, 892 

516.  Muscles  of  the  Nose, Iffer  Bourgeri/  893 

517.  Oblique  Section  passing  through  the  Nasal  Fosstc,  just  in  front  of  the  Posterior  Narcs 

(seen  from  behind), 894 

518.  Section  of  the  Nose,  showing  the  Turbinal  Bones  and  Meatuses,  with  the  Openings  in 

Dotted  Outline, .  895 

519.  Transverse  Section    passing  through  the  Nasal  Fossa'  and  Antra  at  the  Posterior  Ex- 

tremity of  the  Middle  Turbinal  Bone  (seen  from  the  front),    895 

520.  Nervesoi"  the  Nasal  Cavity  ((7o?oHm/', 896 

521.  Anterior  View  o  the  Thorax,  with  Outlines  of  the  Diaphragm  and  Lungs, 899 

522.  Superior  View  of  a  Section  of  the  Thorax,  passing  through  the  Sternum  immediately 

below  the  First  Costo-sternal  Articulation,  through  the  Trachea  at  its  Division,  and 

through  the  Body  of  the  Fourth  Thoracic  Vertebra  (ro/o»(;vv/).  .    .  ...     Braune  900 

523.  Front  View  of  the  Cartilages  of  the  Larynx,    ....     Modified  from  Bourgeri/ and  Jaeoh  902 

524.  Side  View  of  the  Cartilages  of  the  Larynx  (Cotoured),    Modified  from  Bourgeri/  and  Jaeob  903 

525.  Front  View  of  the  Cricoid  and  Arytenoid  Cartilages  (Co/oj<rerf), 904 

Modified  from  Bourgery  and  Jaeoh 

526.  Back  View  of  the  Cricoid  and  .\rytenoid  Cartilages  (Co/oMr«/), 904 

Modified  from  Bourgeri/  and  Jaeob 

527.  Superior  View  of  the  Cartilages  of  the  Larynx,  906 

528.  Side  View  of  the  Muscles  and  Ligaments  of  the  Larynx, 907 


X  X  \- i  L  IS T  OF  ILL  i  '.S  TRA  TIOXS 


KIG. 


529.  Scheme  of  Rima,  showing  Action  of  Crico-arytenoideus  Posticus,  which  draws  the  Aryte- 

noid Cartilage  from  I  to  11  ( (></('«/•«/),     Modified  from  Stirling  908 

530.  Posti-riur  View  of  Thyroid  Cartilage  with  Epiglottis, 908 

531.  Scheme  Showing  Action  of  Tliyro-ary  teuoid  drawing  the  Vocal  Cords  and  Vocal  Processes 

Irom  II  to  1  (Co/oM/-«/), ....      Modified  from  St irliiuj  909 

53:2.  Scheme  showing  Action  of  Aryteuoideus   drawing   Aiyteuoid   Cartilage  from  Nentral 

Position  I  to  II  {Coloured) Modified  from  SUrlitig  f)09 

533.  View  of  Interior  of  Larynx  as  seen  during  Inspiration, 911 

534.  View  of  Interior  of  Larynx  as  seen  during  Vocalisation, 911 

535.  Nerves  of  the  Larynx  (i)o.sterior  view)  (Co/oH/r</j, 912 

536.  Anterior  View  of  the  Larynx,  with  the  Trachea  and  Bronchi,     .    3Iodified  from  Bourgery  914 

537.  View  of  Thyroid  llody 916 

538.  Thyroid  Body,  with  Middle  Lobe  and  Levator  Muscle, 917 

539.  The  Suspensory  Ligaments  of  the  Thyroid  Body, After  Berry  917 

540.  Thymus  Gland  in  a  Ciiild  at  Birth,                         918 

541.  Thymus  Gland  in  a  Child  at  the  Age  of  Two  Years, 919 

542.  Anterior  View  of  F(£tal  Heart,  Ve.-^sels,  and  Lungs, 921 

543.  Anterior  View  of  the  Thorax  with  Chest  Wall  removed,  showing  the  Lungs, 922 

Modified  from  Bourgery 

544.  Posterior  View  of  the  Thorax  with  Chest  Wall  removed,  showing  the  Lungs, 923 

Modified  from  Bourgery 

545.  Anterior  View  of  the  Lungs  :  Pericardium, Modified  from  Bourgery  924 

546.  Anterior  View  of  the  Heart  with  the  Larger  Vessels  (  CWo«/«Z) 927 

547.  Showing  the  Po.sition  of  the  Heart  and  its  Valves  in   Kelation  to  the   Chest  Walls 

(Coloured), Uedueed  from  Hensman  and  Fisher  928 

548.  Transverse  Section  passing  through  the  Auricles  of  the  Heart,  showing  the  Auriculo  ven- 

tricular Orifices  and  the  Semilunar  Valves  of  the  Pulmonary  Artery  and  Aorta  (seen 

from  ahove),        929 

549.  Anterior  View  of  the  Right  Chambers  of  the  Heart,  with  the  Great  Vessels, 930 

550.  Transverse  Section  through  the  Heart  near  its  Apex,  Showing  the  Relative  Thickness  of 

its  Muscular  Walls,  the  Bulging  of  the  Septum  towards  the  Riglit  Ventricle,  and  the 

shape  of  the  Cavities, 931 

551.  Interior  View  of  the  Aortic  Semilunar  Valves, 932 

552.  View  of  the  Auricular  Cavities  from  below  (the  Transverse  Section  passing  above  their 

Middle) 933 

553.  Posterior  View  of  the  Left  Chambers  of  the  Heart,  with  the  Great  Vessels  and  the  Coro- 

nary Sinus  laid  open, .  934 

554.  Showing  the   Position   of  the   Heart  and   its  Valves  in  Relation  to  the  Chest  Walls 

(Coloured), tleduced  from  Hensman  and  Fisher  935 

555.  Anterior  View  of  the  Heart,  showing  its  Arteries  and  Veins  (Co/oioec?), 936 

556.  Posterior  View  of  the  Heart,  showing  its  Arteries  and  Veins  (C'o?Ofn-«7), 937 

557.  Anterior  View  of  a  Foetus.     The  Heart,  A^essels,  and  Chief  Organs  displayed,  with  the 

Placenta  and  Umbilical  Cord  (Co/o«re^),                  938 

558.  Anterior  View  of  Heart  and  Great  Vessels  of  Foetus,  the  Anterior  Chest  Wall  being  re- 

moved and  the  Heart  Sac  opened,           .            940 

558a.  Palato  glossus  Muscle,  seen  from  the  Mouth,  with  Section  of  Base  of  Tongue  (modified),  943 

558b.  View  of  Muscles  of  Soft  Palate,  as  seen  from  within  the  Pharynx 945 

Modified  from  Bourgery 

559.  The  Salivary  Glands, '.    .  " 947 

559a.  The  Muscles  of  the  Pharynx, 950 

560.  Section  showing  the  Posterior  Wall  of  the  Pharynx,  with  the  Pharyngeal  Bursa,  Fauces, 

etc., 951 

561.  Transverse  Section  of  the  Peritoneal  Sac  at  about  the  Level  of  the  Umbilicus, 9.54 

562.  Transverse  Section  of  the  Abdomen  at  the  Level  of  the  Foramen  of  Winslow, 955 

563.  Diagram  to  .show  the  Peritimeum  as  seen  in  a  Vertical  Section, Allen  Thomson  956 

564.  Diagram  to  show  the  Peritoneum  as  seen  in  Vertical  Section, Allen  Thomson  958 

5()5.  The  Viscera  as  seeu  on  fully  opening  the  Abdomen  without  Disarrangement  of  the  Inter- 
nal Parts After  Sara zin  959 

566.  Posteiior  Surface  of  the  Stomach, 961 

567.  Anterior  Surface  of  the  Stomach, 961 

568.  -Muscular  Coat  of  the  Stomach,    .    .    , Lusehka  963 

569.  Muscular  Coat  of  the  Stomach, Lusehka  963 

.570.  The  Duodenum  from  in  front, 965 

.571.  The  Duodenum  from  behind, 966 

572.  The  Fossa  Duodeno-jejunalis, Treres  966 

573.  Portion  of  the  Small  intestine,  laid  open  to  show  the  Valvulte  Conniventes,    .    .   Brinion  968 

574.  Vessels  of  the  Small  Intestine, 969 

.575.  The  Four  Types  of  Cajcum Treres  970 

.576.  Section  of  the  Ascending  Colon, Allen   Thomson  972 

577.  View  of  the  Deeper  Abdominal  Vi.scera, Riidinf/er  974 

.578.  The  Viscera  of  the  F<et  us Bildinger  977 

.579.  Superior  Surface  of  the  Liver .  978 

580.  The  Inferior  Surface  of  the  Liver, 978 

581.  Posterior  Surface  of  the  Liver, 979 


LIST  OF  ILLUSTRATIONS  xxvii 

FIG.  PAfiK 

bS'-l.  Relation  of  the  Ahdomiiial  Visceni  to  the  Parietes, Treves  9«0 

5»;J.   Ivelatiou  of  the  Alxloiiiiiial  Viscera  to  the  Pariett's Treves  981 

584.   Kelatioii  of  .Structures  at  and  below  the  Tran.sverse  Fis.sure,       Thane  !)H3 

58").    Section  of  a  Portal  Canal,             Qiuiin  !)H4 

586.  Abdominal  Viscera,  from  Itehind, Rudivijir  985 

587.  The  Pancreas  and  its  Duct, .  987 

588.  Outer  Aspect  of  the  Spleen,      y88 

589.  Inner  Aspect  of  the  Spleen, 989 

590.  Transver.se  Section  of  the  Body  at  the  Lower  Part  of  the  Epigastric  Region,    .    K'udhHjcr  989 

591.  View  of  the  Spleen,  etc.,  from  behind, R'udinyer  990 

592.  Diagram  of  the  Primitive  Alimentary  Canal, 992 

59.5.   Diagram  of  the  PriTuitive  Alimentary  Canal, 99:^ 

5!)4.  Alimentary  Canal  of  <sV(/<///(rr/u//y« /;i«CH/o,w, 994 

59.").  Alimentary  Canal  of  .S((/(/)y/(n(r/r«  Hi«c-«/o.sf/, 995 

59().   Alimentary  Canal  of  Cholwpus  Hoff'vuinni, 996 

597.  Diagram  to  show  the  Rotation  of  the  Intestinal  Canal, 997 

598.  Diagram  to  show  the  Relation  of  the  Peritoneum  to  the  Duodenum, 998 

599.  Diagram  to  show  the  Lines  along  which  the  Peritoneum  leaves  the  Wall  of  the  Abdomen 

to  invest  the  Viscera, ('unniiujhmn  999 

600.  Diagram  to  show  the  Formation  of  the  Great  Omentum, lOUO 

601.  Great  Omentum  in  J/r(crojji(.s"  pe>uV/7/((/H8, 1001 

602.  Formation  of  Great  Omentum  as  seen  in  Vertical  Section, lOol 

(>(i:5.   iielatiou  of  Great  Omentum  to  Transverse  Colon,                       1002 

604.  Transverse  Section  of  the  Abdomen  at  the  Level  of  the  Foramen  of  Winslow, 1002 

6(»5.  liites{\ne  oi'  3I((cr()pi(s pcnicilUdufi, 1003 

6(Ki.   T)\\oiXe\v.\\  Fold  oi  MacropuK  peniciUdtus,        1003 

607.  Postero  internal  Aspect  of  the  Left  Kidney, 1005 

608.  Diagram  showing  Relation  of  Kidney  to  Capsule, 1006 

609.  .Section  of  Kidney  showing  the  Sinus, After  Henle  1007 

610.  Diagram  of  Relations  of  Posterior  Surface  of  Kidney, 1007 

611.  The  Abdominal  Viscera,  seen  from  behind.      From  the  model  of  His  1008 

612.  Diagram  showing  Anterior  Relations  of  Kidneys  and  Suprarenal  Bodies, 1009 

613.  Horizontal  Section  of  Kidney,  showing  the  Sinus,     .        1011 

614.  Scheme  of  Tubules  and  Vessels  of  the  Kidney, 1012 

615.  Diagram  showing  Anterior  Eelatious  of  Kidneys  and  Suprarenal  Bodies, 1013 

616.  Upper  Portion  of  Duct After  Hcnte  1015 

617.  Median  Sagittal  Section  of  the  Male  Pelvis, 1017 

H38.  The  Posterior  Wall  of  the  Bladder, After  Henle  1019 

619.  Section  of  the  Female  Pelvis, After  Henle  1020 

620.  Semi-diagrammatic  Section  of  the  Male  Pelvis, 1022 

621.  Horizontal  Section  of  the  Scrotum  and  Testicle  (diagrammatic), 1023 

622.  The  Left  Testicle  with  Vessels  and  Duct, After  Sappey  1025 

623.  Diagram  of  the  Testicular  Tubules 1027 

624.  Vasa  Deferentia  and  Vesiculse  Semi nales, After  Sappey  1028 

625.  Vas  Deferens  and  Vesicula  Seminalis  dissected, Aft(  r  Sappry  1029 

626.  Section  of  the  Spermatic  Cord, After  Jienie  1031 

627.  Transverse  Section  through  the  Body  of  the  Penis  iColoxtred), 1032 

628.  Transverse  Section  of  the  Penis  through  the  Base  of  the  Glans 1033 

629.  The  Male  Perinseum  (Coloured) 3IodiJied  from  Hirschfeld  and  Leveill^  1034 

630.  The  Male  Urethra,  cleft  dorsallv  to  show  Ventral  Mucous  Wall, 1036 

631.  The  E.Mternal  Genitals  of  the  Female 1039 

632.  Diagrammatic  Representation  of  the  Perinfeal  Structures  in  the  Female, 1040 

633.  Section  of  the  Female  Pelvis, After  Henle  1041 

634.  Horizontal  Section  of  Vagina  and  adjacent  Stmctures, .    After  Henle  1043 

635.  The  Female  Organs  of  Generation, 3fodified  frnm  Sappry  1045 

636.  The  Posterior  Surface  of  the  L'torus After  Sapjicy  1045 

637.  Frontal  Section  of  the  Virgin  Uterus, After  Sappey  1046 

638.  SagittalSectionofthe  Virgin  Uterus After  Sappey  1046 

6.39.  The  Broad  Ligament  and  its  Contents,  seen  from  the  Front, After  Sappey  1048 

640.  Diagrammatic  Section  of  the  Broad  Ligament, 1049 

641.  .Section  of  the  Pelvis  showing  the  Ligaments  of  the  Uterus 1050 

642.  The  Broad  Ligament  and  its  Contents,  seen  from  tlie  Front After  Sappey  1051 

643.  Diagram  of  the  Arteries  and  Lymphatics  of  the  Female  Generative  Organs 1054 

644.  Diagram  of  the  Primitive  Genito-urinary  Organs  before  Differentiation  of  Sex,  After  Henle  1055 

645.  Development  of  the  Urino  generative  Organs,  Female  Type After  Henle  10.56 

646.  Development  of  the  Urino-generative  Organs,  JLile  Type [ftcr  Henle  10.57 

647.  The  Male  Perinajum  (rV)/oj<»-crf),      Modified  from  Hirsehfeld  and  Leieill^  10.59 

648.  Diagram  of  the  Pelvic  Fascia; If"^" 

649.  Muscles  of  the  Floor  of  the  Pelvis 1061 

650.  Diagram  showing  Lines  of  Attachment  of  the  Fa.sciai  and  Muscles  of  the  Pelvis,      .    .  1062 

651.  Muscles  of  the  Floor  of  the  Pelvis 1063 

652.  Sagittal  Section  through  the  Perinseal  Ledge  and  Ischio-rectal  Fossa  to  the  Left  of  the 

Middle  Line  (diagrammatic), lOfi' 

653.  Section  showing  the  Ischio-rectal  Fossa  in  its  Relations  to  the  Pelvic  Vi-scera, 1064 


xxviii  LIST  OF  ILLUSTRATIOXS 


FIO, 


PAGE 

654.  Diagram  of  the  Superficial  aud  Deep  Triangular  Ligaments  (ro/o«?ef7), 1066 

655.  Vertical  Frontal  Section  of  the  Pelvis,  showing  Fascia;,   .    .        .      Modijicd  from  Braune  1067 

656.  Diagrammatic  Kepresentation  of  the  Perinoeal  Structures  in  the  Female, 1069 

657.  The  Female  Mamma  during  Lactation, ' After  Luschka  1070 

658.  Development  of  the  Mamma  of  the  Female  Embrj'O, After  Longer  1071 

659.  The  Skull  [Coloured) 1081 

660.  Temporal  Bone,  showing  Suprameatal  Triangle, 1082 

661.  Sagittal  Section  through  Roof  and  Floor  of  Tympanic  Cavity, 1083 

662.  Horizontal  Section  of  Left  Temi)()ral  ISone,  showing  the  Various  Parts  of  the  Ear,     .    .    .  1084 

663.  Section  through  the  Scalp,  Skull,  and  Dura  Mater Tillaux  1085 

664.  The  Outline  of  the  Brain  and  its  Fissures  in  Kelation  to  the  Sutures  of  the  Skull,     .    .    .  1087 

665.  Drawing  of  a  Cast  of  the  Head  of  an  Adult  Male  (Co/o«/-e(/), Cunningham  1089 

666.  Cranio-cerebral  Topography, Anderson  and  Makins  1090 

667.  Scheme  of  the  Facial  Artery  (C(j/«KmO, 1092 

668.  Vertical  Transverse  Section  through  the  Upper  Eyelid,    .    .    .  After  Waldeyer  and  Fuchs  1093 

669.  The  Lachrymal  Apparatus  and  Nasal  Duct, Bellamy  1094 

670.  Side  of  the' Face  and  Mouth  Cavity,  showing  the  Three  Salivary  Glands, 1095 

671.  Section  of  the  Skull  and  Brain  in  the  Median  Plane,        Braune  1096 

672.  Section  of  the  Nose,  showing  the  Turbinal  Bones  and  Meatuses,  -with  the  Openings  in 

Dotted  Outline 1098 

673.  Section  showing  Bony  and  Cartilaginous  Septum, 1098 

674.  Thymus  Gland  in  a  Child  at  Birth, ,        .    .  1100 

675.  Anterior  and  Lateral  Cervical  Muscles, 1101 

676.  Region  of  the  Third  Part  of  the  Subclavian  Artery, Bellamy  1103 

677.  The  Collateral  Circulation  after  Ligature  of  the  Common  Carotid  and  Subclavian  Arte- 

ries {Coloured), 1104 

678.  Diagram  of  the  Layers  of'the  Deep  Cervical  Fascia  in  an  Aut«ro-posterior  Section  oppo- 

site to  the  Sternum,       Tillaux  1105 

679.  Diagram  of  the  Arrangement  of  the  Deep  Cervical  Fascia,  the  Section  passing  through 

the  Clavicle, Tillaux  1106 

680.  Section  of  Neck  through  the  Sixth  Cervical  Vertebra, Braune  1107 

681.  The  Arch  of  the  Aorta,  with  the  Pulmonary  Arter3'^  and  Chief  Branches  of  the  Aorta 

{Coloured), 1109 

682.  Section  of  the  Sixth  Left  Intercostal  Space,  at  the  Junction  of  the  Anterior  and  Posterior 

Thirds, Tillaux  1110 

683.  Outline  of  the  Heart,  its  Valves,  and  the  Lungs  (shaded) Holdcn  1111 

684.  Diagram  of  the  Relations  of  the  Thoracic  Viscera  to  the  Walls  of  the  Chest,     .    .  Bellamy  1 112 

685.  ObliquusExternus  and  Fascia  Lata, 1115 

686.  The  Viscera  as  seen  on  fully  opening  the  Abdomen  without  Disarrangement  of  the  Inter- 

nal Parts,     After  Sarazin  1116 

687.  Section  of  Abdomen  between  the  Third  and  Fourth  Lumbar  Vertebrae,    ....   Braune  1117 

688.  Diagram  showing  Relation  of  Kidney  to  Capsule, 1118 

689.  Transverse  Section  of  the  Abdomen  through  the  Kidnej'S  and  Pancreas,  at  the  level  of 

the  First  Lumbar  Vertebra, Braune  1120 

690.  The  Abdominal  Aorta  and  Inferior  Vena  Cava  (Co^oxrerf), 1121 

691.  The  Male  Perimeum  (C'oZoHmi),      3Iodified  from  Hirschfeld  and  LeveilU  1123 

692.  Deep  Dissection  of  Male  Perineum, Roser  1124 

693.  The  Arteries  of  the  Perina^um  (Co7o«rff7), 1125 

694.  Sagittal  Section  of  Male  Pelvis  in  the  Mesial  Line, Braune  1125 

695.  Scheme  of  the  Pudic  Artery  and  its  Branches  (ro/oMJw/), 1126 

696.  Section  showing  the  Ischio-rectal  Fossa  in  its  Relations  to  the  Pelvic  Viscera, 1127 

697.  Diagram  of  the  Pelvic  Fasciaj, 1128 

698.  Diagrammatic  Representation  of  the  Perinseal  Structures  in  the  Female, 1129 

699.  Section  of  the  Female  Pelvis, After  Hcnle  1130 

700.  The  Parts  concerned  in  Inguinal  Hernia, 1132 

701.  Diasection  of  Inguinal  Canal  (ro/oMJYr/), Wood  1133 

702.  Dissection  of  the  Lower  Part  of  the  Abdominal  Wall  fronr  Avithin,  the  Peritoneum  hav- 

ing been  removed,      Wood  11.34 

703.  Vertical  Section  of  Pelvis  passing  through  the  Heads  of  the  Thigh  Bones,  .    .    .  Blandin  1135 

704.  Irregularities  of  the  Obturator  Artery, After  C:! ray  1140 

705.  Diagram  and   Table   showing  the   Approximate  Relation  to  the  Spinal  Nerves  of  the 

various  Motor,  Sen.sory,  and  Reflex  Functions  of  the  Spinal  Cord, Gotrers  1143 

706.  Chief  Arterial  Anastomoses  on  the  Scapula  (Co/oiuw?), 1144 

707.  Arrangement  of  Lumbar  Aponeurosis  at  Level  of  Third  Lumbar  Vertebra, 1144 

708.  Relation  of  the  Abdominal  Viscera  to  the  Anterior  Parietes, Treres  1145 

709.  Relation  of  the  Abdominal  Viscera  to  the  Parietes, 7Wves  1146 

710.  Abdominal  Viscera,  from  behind Jiiidinger  1147 

711.  View  of  the  Spleen,  etc.,  from  behind, Rildinger  1148 

712.  Transverse  Section  through  the  IJight  Shoulder-joint,  showing  the  Structures  in  contact 

with  it, Braune  11.50 

713.  The  Brachial  Artery  (To/o/fm/), wrA 

714.  Section  through  the  Middle  of  the  Right  Upper  Arm, Heath  1152 

715.  Diagrammatic  Section  of  Shoulder  through  Occipital  Groove Anderson  1152 

716.  Back  View  of  the  Scapular  Muscles  and  Triceps,    .    .    .    .* 1153 


LIST  OF  ILL  ISTRA  TIOXS  x x ix 

Fia.  i'A(,K 

717.  Vertical  Section  of  the  Elbow, Braune  1154 

718.  Lougitiulinal  Section  of  the  EUjow-joint, Jiranue  115.'") 

71!).   JJend  of  the  Ellmw, ! BUokUh  \\w 

720.  The  Hend  of  the  Elhow  with  the  Superficial  Veins  (Co7o?«-«/), 115() 

721.  The  Kruchial  Artery  at  the  Bend  of  the  Elbow  (Co/o»/-erf), 1157 

722.  Diagram  of  the  Anastomoses  of  the  Brachial  Artery, 1158 

723.  Section  through  the  Middle  of  the  Kight  Forearm, IIcuUi  11.59 

724.  The  Arteries  of  the  Forearm  with  the  Superficial  Pal  mar  Arch  (  ro/o((r«/) IIGO 

725.  Distribution  of  Cutaneous  Nerves  on  the  Anterior  and  Posterior  Aspects  of  the  Superior 

Extremity, llfil 

72().  Superficial  Veins  and  Lymphatics  of  the  Forearm  and  Arm  {Coloured), Il(i2 

727.  Relation  of  the  Palmar  Arches  to  the  Folds  of  the  Palm, TiUau.c  11()3 

728.  Anastomoses  and  l)istri])ution  of  the  Arteries  of  the  Hand  (C'o/o»;ef/), 1U)4 

729.  The  Superficial  Muscles  of  the  Palm  of  the  Hand, 1165 

730.  The  Deeper  Muscles  of  tlie  Palm  of  the  Hand, 116(J 

731.  Section  through  region  of  Wrist,  a  little  above  the  Joint.     Right  side,  Upi>er  Half  of  the 

Section, .•■ ...     TilUnix  1107 

732.  Transverse  Section  of  the  Wrist,  through  the  Middle  of  the  Pisiform  Bone, 11(57 

733.  Diagram  of  the  Great  Palmar  Bursa, 11()8 

734.  Section  of  Carpus,  through  the  Unciform  Bone, BelUimy  ofler  llcnle  1109 

735.  Horizontal  Section  of  the  Hand  through  the  Carpo- metacarpal  Joints,  Bellamy  after  llenJe  1109 
7.30.  Tendons  upon  the  Dorsum  of  the  Hand, 1170 

737.  Diagram  of  a  Vertical  Section  through  the  Middle  of  the  Hand, 1171 

738.  Trausver.se  Section  of  the  Hip-joint  and  its  Relations, Braune  1173 

739.  The  Muscles  attached  to  the  Pubes, 1 1 74 

740.  Diagram  of  Arteries  of  Thigh, 1175 

741.  Section  of  the  Right  Thigh  at  the  Apex  of  Scarpa's  Triangle,     .    .        Heath  1176 

742.  Superficial  Dissection  of  the  front  of  the  Thigh, Hirschfcld  and  Lereille  1176 

743.  Anterior  Crural  and  Obturator  Nerves  (Co/oM/Tf/), Ellis  1177 

744.  Section  of  Thigh  through  upper  part  of  Hunter's  Canal, If.  A.  1178 

745.  Superficial  Muscles  of  the  Back  of  the  Thigh  and  Leg, 1179 

746.  Position  and  Direction  of  the  Superficial  Incisions  which  must  be  made  to  receive  the 

Gluteal,  Sciatic,  and  Pudic  Arteries, 1180 

747.  Section  through  the  Hip  and  Gluteal  Region, 1181 

748.  The  Gluteal  Region,  with  the  Gluteal,  Sciatic,  and  Pudic  Arteries  {Coloured),     Walsham  1182 

749.  Deep  Dissection  of  the  Gluteal  Region, 1]>*3 

750.  Horizontal  Section  of  the  Knee  joint, 1184 

751.  Vertical  Section  of  the  Knee-joint  in  the  Antero-posterior  Direction, 1185 

752.  Side  View  of  the  Popliteal  Artery  {Coloured), 11^7 

753.  Deep  View  of  the  Popliteal  Space, Ilirselifcld  and  Lerailh'  11H3 

754.  Anastomoses  of  Tibial  Arteries, ...  .    .  1189 

755.  The  Anterior  Tibial  Artery,  Dorsal  Artery  of  the  Foot,  and  Anterior  Peroneal  Artery, 

and  their  Branches  (Coloured), 1190 

756.  Relations  of  the  Popliteal  Arterv  to  Bones  and  Muscles  (Co/oH)Y(/), 1191 

757.  Section  ofthe  Right  Leg  in  the  Upper  Third Heath  1192 

758.  Branches  of  the  External  Popliteal  Nerve  ((7o?o?/refi), 1193 

759.  The  Muscles  of  the  Front  of  the  Leg, 1195 

760.  Transverse  Section  through  the  Lower  Third  of  the  Left  Leg,  immediately  above  the 

Aidvle-joiut,         Braune  1196 

761.  Relations  of  Parts  behind  the  Inner  Malleolus, Heath  1196 

762.  Articulations  of  the  Foot,  Dorsal  Aspect,  Bellamy  1198 

763.  Vertical  Section  through  the  Cuneiform  and  Cuboid  Bones, 1199 

764.  Superficial  Nerves  in  the  Sole  of  the  Foot  (Co/oHm/), FJlis  1200 

765.  Plantar  Arteries  (Deep)  (Co/owm/) 1201 

766.  Longitudinal  Section  of  Foot, Braune  1201 

767.  The  Arch  in  the  Ordinary  Position  of  Standing, E/lis  {of  Gloucester)  1202 

76S.  This  shows  the  ElVect  of  Mu.scnlar  Action  in  throwing  up  the  .Vrch 1203 

769.  Tlie  Superficial  Veins  and  Lymphatics  of  the  Left  Lower  Limb  I  Crt/o(/><'</) 1204 

770.  Distribution  of  Cutaneous  Nerves  on  the  Posterior  and  Anterior  Aspects  of  the  Inferior 

Extremity 1205 

771.  Diagram  of  the  Abdominal  Regions, l-O? 


SECTION    1 

OSTEOLOGY 

By  J.  BLAND  SUTTON,  F.E.C.S. 

ASSISTANT-SURGEON    TO    THE  MIDDLESEX   HOSPITAL,   AND    SURGEON   TO  THE  CHELSEA   HOSPITAL   FOR   WOMEN,   LONDON 


{ 


THE   SKELETON 

THE  skeleton  contains  206  distinct  bones.  Tliey  are  arranged  by  anato- 
mists in  two  sets: — the  bones  of  the  trunk  and  the  bones  of  the  limbs.  Tlie 
skeleton  of  the  trunk  is  made  up  of  the  skull,  which  contains  twenty-nine 
bones  exclusive  of  the  teeth;  the  vertebral  column,  consisting  of  twenty-six  separate 
bones;  twenty-four  ribs,  and  the  sternum.  The  skeleton  of  the  upper  limbs 
comprises  sixty-four  bones;  and  that  of  the  lower  limbs,  including  the  patelhe, 
sixty-two. 

Several  of  the  skull  bones  are  compound,  that  is,  in  the  immature  skeleton  they 
consist  of  separate  elements  which  ultimately  unite  to  form  a  single  bone.  In 
order  to  comprehend  the  nature  of  such  bones,  it  is  necessary  to  examine  them  in 
the  various  stages  through  which  they  pass  in  the  embryo  and  child.  Thus  the 
student,  anxious  to  convince  himself  of  Man's  place  in  nature,  studies  carefully  the 
development  and  ossification  of  l)ones,  and  compares  them  with  the  bones  of  other 
\'ertel)rata.  He  then  finds  that  many  elements  which  make  a  compound  bone  are 
osteological  units  for  the  Comparative  Anatomist. 

Com})arisons  of  this  nature  constitute  the  science  of  Morphology,  one  of  the 
most  fascinating  departments  of  Biology. 

It  is  the  duty  of  the  student  to  follow  the  descriptions  with  the  actual  bones  in 
his  hand.  He  should  also  remember  that  many  variations  occur  in  the  outlines 
and  markings  of  bones.  Hence  the  various  types  descril)ed  and  figured  represent 
the  average  of  a  large  number  of  bones  examined.  It  is  very  rare  to  meet  with 
bones  which  accurately  correspond  to  the  description  in  every  detail. 

In  order  to  appreciate  the  mor])hology  of  the  skeleton,  the  osteogenesis  or  mode 
of  development  of  bones  must  be  studied  as  well  as  their  topography  or  position. 
Some  1)ones  arise  by  ossification  in  membrane,  others  in  cartilage.  In  the  early 
eml)ryo,  many  portions  of  the  skeleton  are  rei)resented  by  cartilage  which  becomes 
infiltrated  by  lime  salts — calcification.  This  earthy  material  is  taken  uj)  and 
redeposited  in  a  regular  manner — ossification.  Portions  of  the  original  cartilage 
persist  at  the  articular  ends  of  bones,  and,  in  young  bones,  at  the  epiphysial  lines. 
Long  bones  increase  in  length  at  the  epiphysial  cartilages,  and  increase  in  thick- 
ness by  ossification  of  the  deeper  layers  of  the  investing  membrane  or  periosteum. 
These  jirocesses — intercartilaginous  and  intermembranous  ossitieation — proeee(l  con- 
currently in  the  limb-l)ones  of  a  young  and  growing  mammal. 

Tliere  is  no  bone  in  the  human  skeleton  whicli.  thougli  pre-f<irmed  in  cartilage, 
is  perfected  in  tliis  tissue.  The  ossification  is  completed  in  mi-mbrane.  On  the 
1  1 


2  THE  SKELKTOX 

other  hand,  tlu-rf  an-  nunifrous  instances  in  the  skull,  of  IxHies  the  ossilieatinn  of 
whicli  begins  in,  and  is  j)erfeeted  1)V,  the  internienil)ranons  method.  OssiHeation  in 
a  few  instances  conniiences  in  membrane,  but  later  invades  tracts  of  cartilage; 
occasionally  the  process  l)egins  in  perichondrium  and  remains  restricted  to  it,  never 
invading  the  underlying  cartilage,  which  gradually  disappears  as  the  result  of 
continui'd  jiressure  exerted  upon  it  by  the  growing  bone.  The  vomer  and  nasal 
bones  are  the  best  examples  of  this  mode  of  develo})ment. 

A  Classifikd  List  of  the  Bones  to  snow  their  INIode  of  Development 

1.  All  the  limb-bones  and  those  of  the  vertebral  colunm  are  pre-formed  in  car- 
tilage and  perfected  in  membrane,  with  the  exception  of  the  clavicles.  These  begin 
in  membrane,  proceed  in  cartilage,  and  are  finally  perfected  m  membrane. 

•2.   The  Skull. 

Membrane-Bones 

Parietals.  Interparietal  portion  of  occii)ital. 

Frontal.  "Wormian  l)ones  and  the  epipterics. 

Scjuaniosals.  Tympanies. 

Maxilke.  Mandible  (except  part  near  the 

Malars.  symphysis). 

Palates.  Lachrymals. 

Nasals.  Vomer. 

Cartilage  Bones 

Sphenoid.  Occipital  (except  inter})arietal  i)()rtion). 

Petrosals.  Ethmoid. 

Mallei.  Incudes. 

Stapes.  Styloid  processes. 

Hyoid.  Symphysial  portion  of  the  mandible. 

Inferior  turbinals.  Internal  pterygoid  plate. 

Many  of  the  skull  bones  are  composite,  that  is,  they  consist  of  two  or  more  ele- 
ments Avhich  remain  separate  in  other  vertebrates.     To  this  group  belong: — 

The  Occipital.  Maxill*.  Frontal. 

Temporals.  Hyoid.  INlaiars. 

Ethmoid.  Sphenoid.  j\ran(li])k'. 

The  dt'tails  of  the  development  and  ossification  of  each  bone  are  added  to  the 
description. 

The  limb-bones  differ  in  several  important  particulars  from  those  of  the  skull. 
Some  of  the  long  l)ones  have  many  centres  of  ossification,  but  the  centres  are  of 
very  different  morphological  value  from  those  of  the  skull.  Speaking  generally,  it 
is  only  the  ]irimary  nuclei  that  have  any  especial  value  for  the  morphologist.  The 
primary  nuc-leus  of  a  long  bone  appears  l)efore  birth.  In  only  three  instances  does 
a  secondary  centre  appear  before  birth;  e.g.  the  condyles  of  the  femur,  the  head  of 
the  tibia,  and  occasionally  in  the  head  of  the  humerus.  Many  primary  ossitic 
nuclei  api)ear  after  l)irth;  for  example,  those  for  the  cari)al  bones,  the  cuneiform 
and  scaphoid  (navicular)  bones  <^f  the  foot,  the  coracoid  process  of  the  sca]»ula, 
and  the  third,  fourth  and  fifth  ])ieces  of  the  sternum. 

When  a  bone  ossifies  from  one  nucleus  only,  this  nucleus  may  a]t])ear  before 
or  after  birth.  Examples:  the  astragalus  at  the  seventh  month  of  embryonic  life, 
and  the  trapezoid  at  the  eighth  year.  When  a  bone  possesses  one  or  more  secondary 
centres,  the  primary  nucleus,  as  a  rule,  appears  early.  Examples:  the  femur, 
humerus,  phalanges,  and  the  calcaneum. 

Secondary  centres  which  remain  for  a  time  distinct  from  the  main  portion  of  a 
bone  are  termed  epiphyses.  An  e))i])hysis  may  arise  from  a  single  nucleus,  as  is 
the  case  with  the  lower  end  of  the  femur;  or  fn^m  several,  as  at  the  u])i)er  i-nd  of 
the  humerus.      Promincnees  al)out  the  ends  oi  long  l)ones  may  be  cap])ed  l)y  sepa- 


OSSIFICA  TIOy—R  I X  ES  OF  EPIPII }  ".S'^.S  3 

rate  epiphyses,  as  is  the  case  at  the  upper  end  of  the  femur.  Epiphyses,  though  of 
no  morphological  value,  seem  to  follow  certain  rules,  thus: — 

1.   Those  epi])hyses  which  appear  last  are  the  first  to  unite  with  the  shaft. 

Exception. — The  distal  epiphysis  of  the  fibula  is  visible  three  years  before  the 
jiroximal,  l)ut  fuses  Avith  the  shaft  much  earlier  than  it.  It  should  be  rememl)ered 
that  the  proximal  end  of  the  fibula  in  man  and  many  other  mannnals  is  vestigial. 


Fro.  1. — Tm:  Tibi.a  and  Fibula  in  section  to  show  the  Epiphyses. 


CENTRE  OF  OSSIFICATION  OF  EPIPHYSIS 
EPIPHYSIAL  LINE 


i 


SHAFT  OF  FIBULA 


SHAFT  OF  TIBIA  IN  SECTION 


EPIPHYSIS  OF  TIBIA 


EPIPHYSIS  OF  FIBULA 


2.  The  epiphvsis  towards  which  the  nutrient  arterv  is  directed  unites  first  witli 
the  shaft. 

3.  \\'hen  a  bone  has  only  one  t-jiiphysis,  the  nutrient  artery  is  directed  towards 
the  extremity  which  has  no  epiphysis. 

4.  The  centres  of  ossification  appear  earliest  for  those  ei^iphyscs  which  bear  the 
largest  relative  proportion  to  the  shafts  of  the  bones  to  which  they  belong. 

5.  When  an  eiiiphysis  ossifies  from  more  than  one  centre,  the  various  nuclei 
coalesce  before  the  shaft  and  ei)iphysis  consolidate. 

On  section,  the  shaft  of  a  fcjetal  long  bone  is  found  occupied  with  red  marrow 
lodged  in  bony  cells  which  do  not  ])resent  any  definite  arrangement.  In  an  adult, 
the  central  jjortion  of  the  shaft  of  a  long  bone  is  filled  with  fat.  or  marrow,  heM 


4  THE  SKELETON 

totrethor  by  a  delicate  reticulum  of  connective  tissue;  the  space  containing'  the 
marrow  is  the  medullary  cavity.  The  expanded  ends  of  the  bone  contain  a  network 
of  eancellous  tissue,  the  spaces  being  filled  with  red  marrou:  This  cancellous  tissue 
differs  from  that  of  the  f(etal  bone  in  that  it  is  arranged  in  a  definite  manner  accord- 
ing to  the  direction  of  pressure  and  the  tension  exerted  Ity  muscles.  Pressure 
lines  are  Avcll  shown  in  the  vcrtebne.      In  a  vertical  section  through  the  centiuiu  i)t' 


Fk;.  J.  — a  Yekteukal  Cextklm  ix  sectiox  to  show  the  Pressukk  Ccrves. 


a  vertebra  the  fibres  of  the  cancellous  tissue  are  seen  to  be  arranged  vertically  and 
horizontally  ;  the  vertical  fibres  are  curved  with  their  concavities  directed  tOAvards 
the  centre  of  the  bone.  The  horizontal  fibres  are  slightly  curved  parallel  with  the 
upper  and  lower  surfaces,  with  their  convexities  towards  the  centre  of  the  bone. 
They  are  not  so  defined  as  the  vertical  set.      ( Wagstaffe. ) 

The  arrangement  of  the  cancelli  in  individual  l)ones  is  a  consequence  of  the 


Fig.  3. — A  Diagram  nt  show  the 
Pressire  and  Texsiox  Curves  of 
the  Femur.     (After  Wagstaffe.) 


Fig.  4. — A  Diagram  showing  Pres- 
sure axi)  Texsiox  Curves  in 
the  Head  of  the  Humerus.  (After 
Wagstaffe. ) 


mechanical  conditions  to  which  the  hone  is  subject.  This  is  well  illustrated  in  the 
femur.  In  the  u])per  end  of  this  bone,  the  cancellous  tissue  is  arranged  in 
divergent  curves.  One  set  springs  from  the  inner  wall  and  spreads  into  the  greater 
trochanter;  a  second  series  of  curves  crosses  this  and  forms  a  set  of  Gothic  arclu's, 
and  is  continued  into  the  neck  and  head;  a  third  set  springs  from  the  lower  thick 
wall  of  the  neck  and  s]»reads  into  the  up))er  part  of  the  head,  and  ends  perpen- 
dicularly in  the  articular  surface  mainly  along  the  lines  of  greatest  pressure.     A 


THE  SPINE  5 

nearly  vertical  plane  of  compact  tissue  projects  into  the  neck  of  the  l)one  from  the 
inferior  cervical  tul)ercle  towards  the  great  troclianter.  This  is  ])laced  in  the  line 
through  which  the  Aveight  of  the  l)ody  falls,  and  adds  to  the  stability  of  the  neck 
of  the  Ijone:  it  is  said  to  be  liable  to  absorption  in  old  age.  In  the  lower  end  of 
the  bone,  the  vertical  and  horizontal  tibres  are  so  disposed  as  to  form  a  rectangular 
niesliwork. 

Tlie  i)lan  of  construction  exhil)ited  by  the  femur  is  the  most  complex  in  the 
skeleton,  l)ut  the  principles  involved  are  the  same  in  all  bones.  An  interesting 
disposition  of  these  curves  is  exhibited  in  the  head  of  the  humerus.  The  pressure 
curves  radiate  in  two  directions:  one  set  at  right  angles  to  the  articular  surface  of 
the  head  of  the  bone;  the  other  at  right  angles  to  the  greater  tuberosity.  The 
last  set,  like  those  in  the  greater  trochanter,  are  the  result  of  tension  exerted  by  the 
muscles  attached  to  these  })rominences. 

The  shafts  of  long  bones  at  the  time  of -birth  are  mainly  cylindrical  and  free 
from  ridgt'S.  The  majority  of  the  lines  and  ridges  so  conspicuous  on  tlie  shafts  of 
long  l)ones  in  adults  are  due  to  the;  ossification  of  muscle-attachments.  The  more 
developed  the  muscles,  the  larger  the  ridges  become. 

The  surfaces  of  bones  are  variously  modified  by  environing  conditions.  Pres- 
sure at  the  extremities  causes  enlargement,  and  movement  renders  them  smooth. 
The  two  causes  combined  produce  an  articular  surface,  ^^'hen  rounded  and  sup- 
ported upon  a  constricted  portion  of  bone,  an  articular  sin-face  is  termed  a  head, 
sometimes  a  condyle  ;  when  depressed,  a  glenoid  fossa.  Blunt,  non-articular  j»ro- 
cesses  are  called  tuberosities  ;  smaller  ones,  tubercles  ;  sliarp  prtijections,  spines. 
Slightly  elevated  ridges  of  l)ones  are  crests  ;  when  narrow  and  i)ronounced,  lines 
and  borders.  A  shallow  depression  is  a  fossa ;  when  narrow  and  deep,  a  groove  ; 
a  perforation  is  usually  called  a  foramen.  The  majority  of  terms — such  as  canal, 
spine,  notch,  sulcus,  and  the  like — are  so  obvious  as  to  render  explanation  need- 
less. 


( 


THE   SPINE 

The  spine  (vertebral  column)  consists  of  thirty-three  superimposed  ])ones 
termed  vertebrae.  Of  these  the  upper  twenty-foiu*  remain  separate  throughout  life 
and  form  three  groups.  The  first  seven  are  called  cervical,  the  succeeding  twelve 
thoracic  (dorsal),  and  the  next  five  lumbar.  In  adult  life  the  last  nine  verteljrte 
ankylose  to  form  two  composite  bones  named  the  sacrum  and  the  coccyx.  The 
sacrum  is  formed  by  the  fusion  of  five  vertebra?  from  tlie  twenty-fifth  to  the  twenty- 
ninth  inclusive;  the  four  terminal  are  vestigial,  and  form  tlie  coccyx.  In  order  to 
gain  a  general  notion  of  the  characters  of  a  vertebra,  it  is  desirable  to  select  a  bone 
from  the  middle  of  the  thoracic  series. 

A  vertebra  consists  of  a  body  and  an  arc-h:  The  body  or  centrum  is  a  solid  disc 
of  ])one  slightly  concave  on  its  superior  and  inferior  aspects,  and  wider  transversely 
than  antero-posteriorly.  The  upper  and  lower  surfaces  are  rough  for  intervertebral 
discs,  and  the  margins  are  slightly  lipped.  The  circumference  of  the  body  is,  in 
front,  concave  vertically,  but  convex  from  side  to  side;  posteriorly  it  is  excavated, 
and  presents  foramina  for  the  escape  of  veins  from  the  cancellous  tissue.  On  the 
sides  of  the  body,  at  the  upi)er  and  lower  angles,  there  are  four  demi-facets;  wlien 
two  vertebne  are  superimposed,  the  adjacent  demi-facets  form  a  complete  articular 
facet  for  tlie  head  of  a  rib. 

The  arch  is  formed  liy  two  pedicles  and  two  lamina\  and  has  connectcfl  with 
it  seven  processes — one  spinous,  two  transverse  and  four  articular.  The  pedicles  are 
two  constricted  short  piers  of  l)one  prcijecting  horizontally  backwards  from  the 
upper  angles  of  the  posterior  surface.  The  lower  liorder  of  each  jx'dicle  is  deeply 
notched;  hence,  when  two  vertebra?  are  in  jwsition  the  notches  are  converted  into 
inter\^ertebral  foramina  for  the  transmission  of  spinal  nerves  and  vessels. 


6  THE  SKELETON 

The  laminae  are  broad  plates  of  bone  continuous  with  tlie  pedieles;  each 
lamina  meets  its  fellow  dorsally  to  complete  the  neural  arch,  and  conjointly  form 
the  spinous  process.  The  superior' l)orders  of  the  laminje  are  rough  for  the  inser- 
tion of  liiiauitiita  subflava.  The  anterior  surface,  in  its  upper  part,  is  smooth 
where  it  bounds  tlie  neural  canal.      The  lower  part  is  rough  for  the  origin   of   the 


Fio.  "). — A  Thoracic  Yeetebka.     (Side  view.) 

d:mi-facet  for  head  of  f.ib 


SUPERIOR  ARTICULAR  PROCESS 
PEDICLE 


FACET  FOR  TUBERCLE  OF  RIB 


TRANSVERSE  PROCESS 


SPINOUS  PROCESS 


ligamenta  subflava.     This  rough  surface  is  continuous  with  tlie  inferior  border  of 
the  spinous  process. 

The  spinous  process  projects  backwards  and  dowuAvards  from  the  confluent 
laminae.  To  its  upper  and  lower  liorders  the  interspinous  ligaments  are  attached; 
its  tip  is  rounded  for  the  supraspinous  ligament.      It  is  mainly  a  muscular  process. 


Fig.  6. — A  Thoracic  Yerterra. 

UMINA 


SPINOUS  PROCESS 


FACET  FOR  TUBERCLE  OF  RIB 


DEMI-FACET  FOR  HEAD 


TRANSVERSE  PROCESS 


Till'  articular  processes  are  four  in  nmnber:  two  are  superior;  they  s])ring 
iron)  tlie  junction  of  the  pedicles  with  the  lamin;e  and  have  their  articular  facets 
directed  backwards,  with  a  slightly  outward  tendency;  their  anterior  surfaces 
complete  tlie  intervertel)ral  foramina;  posteriorly  their  inargins  give  attachment  to 
ca]tsular  ligaments.  Tlie  inferior  articular  ]trocesses  are  slightly  concave  oval  facets 
on  the  lower  and  outer  angles  of  the  anterior  surfaces  of  the  lamina\  They  are 
directed  forwards  and  sliglitlv  inwards. 


THE  CERVICAL   VERTEBRA^:  7 

The  transverse  processes  are  two  in  nmnlter.  and  jut  outwards  from  the  pedieles 
and  lamina'  l)etwcen  the  superior  and  inferior  articular  processes.  The  tip  presents 
an  oval  facet  for  articulation  with  tlie  tuhercle  «»r  the  rib.  ■  When  tlie  rilj  is  in  situ, 
its  neck  forms  with  tlie  process  a  costo-transverse  foramen.  The  transverse  pro- 
cesses, in  addition  to  supporting  the  ribs,  afford  powerful  leverage  to  muscles. 

THE  CERN'ICAL  VERTEBRA 

A  typical  cervical  vertebra  (from  the  third  to  sixth  inclusive)  ])resents  the 
following  characters:  The  centrum  is  smaller  than  in  other  regions  of  the  colunm, 
and  is  of  oval  shape,  the  major  axis  being  transverse.  The  upper  surface  has  its 
lateral  margins  raised  into  prominent  lips,  whilst  the  lower  surface  is  somewhat 
concave,  its  anterior  margin  being  lipped  so  as  to  slightly  overlap  the  anterior 
surface  of  the  vertebra  below.  The  inferior  lateral  margins  are  rounded,  and  come 
into  relation  with  the  raised  edges  of  the  centrum  next  below. 

The  pedicles  are  directed  ol)liquely  outwards,  and  the  intervertebral  notch  is 
narrower  alcove  than  below.  The  laminae  are  long  and  narrow.  The  spinous  pro- 
cess is  short,  and  bifid  at  the  extremity. 

Articular  processes. — Both  the  upper  and  lower  articular  ]^rocesses  are 
situated  at  the  junction  of  the  pedicle  with  the  lamina'  and  they  form  the  upper 
and  lower  extremities  of  a  small  column  of  ]ion<'.     The  facets  of  the  upper  })ro- 


COSTAL  PROCESS  — 
COSTO-TRANSVERSE  FORAMEN 
TRANSVERSE  PROCESS 

SUPERIOR  ARTICULAR  PROCESS 

INFERIOR  ARTICULAR  PROCESS 

LAMINA 


SPINOUS  PROCESS 


PEDICLE 


cesses  look  backwards  and  upwards  and  those  of  the  lower  ]>roccsscs  forwards  and 
downwards. 

The  transverse  process  presents  near  its  base  the  costo-transverse  foramen 
for  the  transmission  of  the  vertebral  artery,  vein,  and  a  plexus  of  sympathetic  nerves. 
The  process  Ijehind  the  foramen  has  a  shallow  groove  for  the  corresponding  s]»inal 
nerve.  The  extremity  of  the  transverse  process  is  bifid;  each  arm  is  terminated  by 
a  tubercle  referred  to  as  anterior  and  i)Osterior.  The  costo-transverse  foramen  is 
very  characteristic  of  a  cervical  vertebra.  It  is  bounded  iiUernally  by  the  j)edi(le. 
posteriorly  Ijy  the  transverse  process,  anteriorly  by  the  costal  process,  and  exter- 
nally by  the  costo-transverse  lamella  which  runs  obli(jUely  upwards  and  forwards 
in  the  ui)])er  vertel)nc  and  horizontally  in  the  lower. 

Tlie  spinal  foramen  of  all  the  cervical  vertel)ra'  is  large,  and  somewhat  triangular 
in  form. 

Peculiar  cervical  vertebrae. — The  various  cervical  vertebrae  possess  distinguish- 
ing features.  The  first,  second,  and  seventh  have  characters  so  different  from  tlieir 
fellows  as  to  render  them  peculiar. 


The  Atlas  ok  Fihst  Cervkal  Vertebra 

This  vertebra  has  neither  lioily  iK.r  spinous  j.rocess;  it  is  an  irregular  ring  of  bone 
with  two  thicker  portions,  the  lateral  masses,  united  anteriorly  by  a  bridge,  tlie 
anterior  arch,  which  constitutes  one-fifth  of  tin-  entire  circumference.     This  arch 


8  THE  sk'i:Li:rox 

pretitnits  a  tubercle  on  its  anterior  fate  for  the  anterior  vertel)ral  liframent  and  the 
longas  colli  nui.-icle ;  its  posterior  surface  has  a  circuhir  facet  for  the  odontf^id  process 
of  the  axis.     The  upper  and  lower  Iwrders  are  for  ligaments. 

The  lateral  masses  are  united  posteriorly  by  a  larger  arch  of  Iwne,  forming  two- 
tiftlis  of  the  c-ircumference.  Posteriorly  this  arch  has  a  tubercle,  representing  a 
rudimentary  si)inous  process.  The  upper  and  under  surfaces  of  the  arch  afford 
attachments  to  ligaments.  At  the  junction  of  the  posterior  arch  Avith  the  lateral 
masses  there  is,  on  the  upper  surface,  a  deep  groove  which  lodges  the  vertebral 
arti'rv  and  the  suboccipital  (first  spinal)   nerve.     A  bridge  of  bone  (the  ossified 


Fig.  8.— The  First  Cervical  Vertebra  or  Atlas. 


ANTERIOR  TUBERCLE 

SUPERIOR  ARTICULAR  PROCESS 

COSTAL  PROCESS 

COSTO-TRANSVERSE  FORAMEN 

TRANSVERSE  PROCESS 

GROOVE  FOR  VERTEBRAL 
ARTERY 


POSTERIOR  TUBERCLE 


oblique  ligament)  sometimes  converts  this  into  a  foramen.  A  similar,  but  nuich 
shallower,  notch  is  present  on  the  under  surface;  this,  with  the  axis,  forms  an 
intervertebral  foramen  for  the  second  nerve.  The  atlas  and  axis  are  peculiar  in  that 
the  first  and  second  spinal  nerves  issue  behind  the  articular  processes,  whereas  the 
remaining  spinal  nerves  emerge  in  front  of  the  articular  facets  of  the  vertebrae. 
Each  lateral  mass  has,  on  its  upper  surface,  an  elongated,  deeply  concave  articular 
fossa  or  cup.  These  articular  cups  convierge  anteriorly.  Occasionally  each  presents 
two  oval  facets  united  by  an  isthmus.  These  cups  receive  the  occipital  condyles  and 
permit  nodding  movements   of   the   head.       The  inferior  articular  processes  are 

Fig.  9.— The  Axis. 

odontoid  process  • 

"^  """  '  ^    facet  for  atlas 


GROOVE  FOR  TRANSVERSE  LIGAMENT 
LAMINA 


SUPERIOR  ARTICULAR  PROCESS 


COSTO-TRANSVERSE  FORAMEN 
BODY 


COSTAL  PROCESS 


INFERIOR  ARTICULAR  PROCESS 


( ircular  and  almost  flat;  they  are  directed  downwards,  with  an  inclination  inwards, 
rest  u})r)n  the  axis,  and  permit  rotatory  movements  of  the  liead.  I>et\veen  the 
upjx'r  and  lower  articular  surfaces  on  the  inside  of  the  ring,  two  tubercles  exist  for 
the  transverse  ligament.  This  ligament  divides  the  space  within  the  ring  into  an 
anterior  smaller  segment  for  the  odontoid  })rocess  of  the  axis,  and  a  larger  ])ortion 
— tlie  spinal  foramen  of  other  vertebr£e — for  the  si)inal  cord  and  its  memljranes. 

The  transverse  processes  are  large,  to  serve  for  the  attachment  of  muscles  which 
helj)  to  rotate  tlie  licail.  The  costo-transverse  foramina  are  large,  but  the  costal 
processes  are  slender. 


EXCKl'TIOXAL  CKRVirAL   VKRTKHR.E 


Tin-:  Axis  ok  Skcoxd  Ckrvkal  Vertebra 

The  Axis  is  easily  r('co<rnise(l  l>y  tin-  large  rounded  odontoid  process  which  sur- 
mounts its  ui)per  surface.  The  centrum  has  a  nu)rei)roniinent  lij)  than  the  other 
cervical  vertebrie,  and  the  anterior  siu-face  has  a  median  ridge  separating  two 
lateral  de]M-cssions. 

The  odontoid  process  is  an  irregularly  rounded  peg  of  hone.  The  anterior 
surface  has  an  oval  facet  for  the  anterior  arch  of  the  atlas.  Posteriorly  it  presents 
a  deeply  cut  smooth  groove  for  the  transverse  ligament.  To  the  apex,  a  thin  narrow 
fihrous  hand  (the  suspensory  ligament)    is   attached.      On   each   side  of  the  apex 

Fig.   H).— The  Ckkvical  Vektebr.^.     (Anterior  view.) 

ANTERIOR  TUBERCLE  OF  ATLAS 
TO  WHICH  THE  longus  coUi  IS  INSERTED 


Rectus  capitis  antieus 
minor 


THE  UPPER  OBLIQUE 
PORTION  OF  longus 
colli 


THE  UPPER  OBLIQUE 
PORTION  OF  longus 
colli  AND  INSER- 
TION OF  INFERIOR 
OBLIQUE  PORTION 


THIS  AND  THE  THREE  SUC- 
CEEDING PROCESSES  GIVE 
ORIGIN  TO  THE  rectus 
capitis  antieus  ma- 
jor AND  INSERTION  TO 
THE  scalenus  antieus 


ORIGIN  OF  VERTICAL  PORTION  OF  THE  longus  colli; 
ITS  INSERTION  IS  INTO  THE  SECOND,  THIRD,  AND  FOURTH  VERTEBR/E 

there  is  an  oblique  facet  for  the  check  ligaments  which  connect  it  with  the  occipital 
l>one.  The  pedicles  are  stout  and  broad;  they  support  the  oval,  upwardly 
<lirected.  articular  surfaces  for  the  atlas.  The  inferior  articular  surfaces  do  not 
diifer  from  the  cervical  type.  The  transverse  are  smaller  than  the  costal 
processes. 

Tii<-  spinous  process  is  stout  and  strong,  deeply  concave  on  its  under  asjx'ct, 
and  artords  lirm  attachment  for  muscles,  especially  those  which  help  to  rotate  the 
head. 


The  Seve.nth   Cervical  Vertebra 

This  vertebra  has  a  longer  s])inous  ))rocess  than  any  other  cervical  vertebra, 
hence  it  is  sometimes  called  vertebra  prominens.     The  extremity  of  this  process 


10 


THE  SKKLEYOX 


IS  n..t  l.ih.l,  but  has  two  small  lateral  tnl.crcles  which  give  attachment  to  the  li-ra- 
mentum  niich*.  The  transverse  processes  are  of  large  size;  the  costal  processes 
are  very  small;  and  the  costo-transverse  foramina  are  the  smallest  of  the  series 
or  wantnig.  \  ery  frequently  the  costal  process  is  segmented  off,  and  constitutes  a 
cervical  ril),  sometnius  ot  large  size. 

Occasionally  a  demi-facet  exists  on  each  side  of  the  lower  border  of  the  centrum 
for  the  h(jad  o  the  hrst  rib.  When  this  demi-facet  is  present,  there  is  usually  a 
well-developed  cervical  ril).  u»udii^   a 


Fk;.   n.— The  Cervical  Vertebr.^^:.     (Posterior  view.) 

Rectus  capitis  posticus  minor 


Bectus  capitis 
lateralis 


Superior  oblique 
Inferior  oblique 


Rectus  capitis  posticus 

major     fThe    pointer 

crosses  the  origin  of 

the  inferior  oblique) 

Semispinalis  colli 


Cervicalis  transversus 


Semispinalis  colli 


Cervicalis  transversus 
Cervicalis  aacendeus 


Semispinalis  colli 


Carvicalis  transversus 
Cervicalis  aseendens 


Cervicalis  transversus 
Cervicalis  aseendens 

Semispinalis  col'i 


Levator  eostge  forigin) 
Aceessorius  i  insertion) 

Interspiuales 


Interspinales 
Trapezius 

Rhomboideus  minor 
Serratus   posticus  superior 
Splenius 
Complexus 


TRANSVERSE  PROCESS 

OF  ATLAS 
Levator  anguli 
scapulas  forigin) 
Splenius  colli 
(insertion! 


Levator  anguli  scapulae 
Splenius  colli 
Scalenus  medius 
(insertion) 


Levator  anguli  scapulae 
Splenius  colli 
Scalenus  medius 


Complexus 


Levator  anguli  scapulae 
Splenius  colli 
'sometimes) 
Scalenus  medius 

Complexus  and  multifidus 
spinas 


Scalenus  medius 
Scalenus  posticus 

Complexus  and  traehelo- 

mastoid 
Multifldus  spinse 

Scalenus  medius 
Scalenus  posticus 

Complexus  and  trachelo- 

mastoid 
Multifldus  spinas 

Scalenus  medius 
Scalenus  posticus 

Complexus  and  trachelo- 

mastoid 
Multifldus  spinae 
(The  large  surface  is  for 

the  multifldus  spinas) 


Multifidus  spinae  (and  to 
each  spinous  process  as 
high  as  the  second) 


The  cervical  vertebrcT  also  exhibit  great  variation  in  reganl  to  tlie  extremities 

1  mv',  '^"i"f  P^"^^«-^^«-     As  a  rule  among  Euroi.eans,  the  s  4>nd     hiVd      mrt^^^ 

il '^  ^Sh >? rn';^''  f  •"^-     ^"^'^^^  ^''^'^  seventh^xli^' t  a^l^dl^^^y  to 

Isnine  ^nd    X  "  T"^^^  ^'""  "^f  ^""'"'''^  i^^hev.le,-  sometimes  the  sixth  has 

1    tb  .  ^e   -vi   ,7  '"^r^'  »="<;>  t  "^  ^»'vonth  presents  the  same  condition.     Occasionallv 

.11  the  ceivical  ^pmcs,  with  the  exception  of  the  second,  are  non-bifid  and  even  n 

spnus  arc  rclatnelv  sliorter  and  more  stunted  than  in  Europeans  generally,  and,  as 


MUSCULA  R   A  TTA  CJIMEy  TS 


11 


a  rule,  are  simple.  The  only  cervical  vertel^ra  which  presents  a  bifid  spine  in  all 
races  is  the  axis;  even  this  may  be  non-bifid  in  the  Negro,  and  occasionally  in  the 
European.      (Owen,  Turner,  Cunningham.) 

The  laminae  of  the  lower  cervical  vertebrae  frequently  present  over  the  inferior 
articular  processes  distinct  tubercles  from  which  fasciculi  of  the  inidtifidus  sp'nut 
muscle  arise.  They  are  usually  confined  to  the  sixth  and  seventh  vertebrte,  but  are 
fairly  frequent  on  the  fifth,  and  are  occasionally  seen  on  the  fourth. 


Fig.  12. — Peculiar  Thoracic  Vertebrj;:. 


AN  ENTIRE  FACET  ABOVE;  A  DEMI- 
FACET  BELOW.  IN  SHAPE  THE 
BODY  RESEMBLES  THAT  OF  A 
CERVICAL   VERTEBRA 


USUALLY  A  DEMI-FACET  ABOVE 
(SOMETIMES  IT  HAS  A  DEMI-FACET 
BELOW) 


USUALLY  AN  ENTIRE  FACET  ABOVE. 
OCCASIONALLY  THIS  FACET  IS  IN- 
COMPLETE. THE  FACET  ON  THE 
TRANSVERSE  PROCESS  IS  USUALLY 
SMALL 


AN      ENTIRE      FACET      ABOVE.  NONE 

ON  TRANSVERSE  PROCESS,  WHICH 
IS  SMALL.  SOMETIMES  IT  HAS  A 
WELL-MARKED  MAMMILLARY  TU- 
BERCLE. THIS  IS  THE  ANTI-CLINAL 
VERTEBRA 


N  ENTIRE  FACET  ABOVE;  NO  FACET 
ON  TRANSVERSE  PROCESS.  CENTRUM 
LARGE.  INFERIOR  ARTICULAR  PRO- 
CESSES TURN  OUTWARDS  AS  IN  A 
LUMBAR  VERTEBRA;  IT  HAS  ALSO 
A  WELL-MARKED  MAMMILLARY  PRO- 
CESS 


A  large  number  of  muscles  are  attached  to  the  ecrv'ical  vertebra'. 

To  the  atlas  : — Rectus  capitis  anticus  minor,  rectus  capitis  posticus  minor, 
rectus  capitis  lateralis,  superior  i)bli(iue,  inferior  oblique,  longus  colli,  splenius 
colli,  intertransversales,  levator  anguli  scapula?. 

To  the  axis  :— Rectus  capitis  posticus   major,  inferior   ol)li<iue,  longus   colli, 


12  THE  SKELETON 

splenius  colli,  intertransversales,  interspinales,  levator  anguli  scapula?,  transversalis 
cervicis,  scalenus  medius,  seniispinalis  colli,  and  niultifidus  spinae. 

To  the  seventh  : — Ti-a])ezius,  complexus,  serratus  posticus  superior,  splenius, 
rhomboideus  minor,  niultilidus  spina.%  seniispinalis,  eight  intertransversales,  inter- 
spinales,  levator  costa%  scalenus  posticus,  accessorius,  scalenus  rnedius,  trachelo- 
mastoid,  and  the  longus  colli. 


THE  THORACIC  OR  DORSAL  VERTEBRA 

The  general  characters  of  the  thoracic  vertebrae  have  already  been  considered 
in  tlie  description  of  the  type  verte])ra.  Their  most  distinguishing  features  are  the 
facets  on  the  transverse  processes  and  sides  of  the  bodies  for  the  tubercles  and 
heads  of  ribs. 

Peculiar  thoracic  vertebrae. — Several  vertebra?  in  this  series  differ  from  the 
type  form.     The  exceptional  are — the  first,  ninth,  tenth,  eleventh,  and  twelfth. 

The  first  has  a  Iwdy  resembling  a  cervical  vertebra,  the  upper  s\n-face  being 
concave  and  lipped  laterally;  it  has  two  entire  facets  above  for  the  first  pair,  and 
two  demi-facets  below  for  the  second  pair  of  ribs.  The  spinous  process  is  thick, 
strong,  almost  horizontal,  and  more  prominent  than  that  of  the  vertebra  promi- 
nens.     Occasionally  the  transverse  process  is  perforated  near  its  root. 

The  ninth  has  demi-facets  above,  and  usually  none  below;  when  the  inferior 
demi-facets  are  i)resent,  this  vertebra  is  not  exceptional. 

The  tenth  usually  has  an  entire  costal  facet  at  its  upper  border,  on  each  side, 
but  occasionally  only  demi-facets.  It  has  no  loAver  demi-facets,  and  the  facets  on 
the  transverse  processes  are  usually  small. 

The  eleventh  has  a  large  body  resemliling  a  lumbar  vertebra.  The  rib  facets  are 
on  the  pedicles;  they  are  complete  and  of  large  size.  The  transverse  processes 
are  short  and  have  no  facets  for  the  tubercles  of  the  eleventh  pair  of  ril^s. 

In  many  mammals,  the  spines  of  the  anterior  vertebrae  are  directed  backwards, 
and  those  of  the  posterior  directed  forwards;  in  the  centre  of  the  column  there  is 
usually  one  spine  vertical.  This  is  called  the  anti-clinal  vertebra.  It  is  at  this 
])oint  that  the  thoracic  begin  to  assume  the  characters  of  lumbar  vertebrae.  In 
man,  the  eleventh  thoracic  is  the  anti-clinal  vertebra. 

The  twelfth  resembles  in  general  characters  the  eleventh,  but  may  be  distin- 
guished from  it  in  having  the  inferior  articular  processes  convex  and  turned 
outwards  as  m  the  lumbar  vertebrae.  It  also  resembles  a  lumbar  vertebra  b)''  pos- 
sessing well-marked  mammillary  and  accessory  tubercles.  These  tubercles  are 
occasionally  present  on  the  tenth  and  eleventh  vertebrae. 

A  peculiarity,  more  frequent  in  the  thoracic  and  lumbar  than  in  the  cervical 
and  sacral  regions  of  the  column,  is  the  existence  of  a  half-vertebra.  Such  speci- 
mens have  a  wedge-shaped  half-centrum,  to  which  are  attached  a  lamina,  a  trans- 
verse, superior  and  inferior  articular,  and  half  a  spinous  process.  As  a  rule,  a 
half-vertebra  is  ankylosed  to  the  vertebra;  aljove  and  below. 


LUMBAR  VERTEBRAE 

The  distinguishing  features  of  lumbar  vertebrae  are  their  large  size;  the  margins 
of  the  centrum  are  prominent;  the  pedicles  are  stout  and  strong;  the  inferior 
intervertebral  notches  are  deep,  and  the  laminae  are  thick  and  strong.  The  sujx-rior 
articular  ])rocesses  have  concave  facets  directed  l)a(kwar(ls  and  inwards,  and  their 
]»()steri()r  l)orders  are  surmounted  by  rounded  mammillary  ]irocesses  or  tul)ercles. 
The  infciior  articular  processes  have  facets  which  look  forwards  and  outwards. 
The  transverse  ]tn)cesses  are  long,  slender,  and  each  presents  near  the  base,  on  the 
posterior  aspect,  a  small  accessory  tubercle.  The  spinous  })rocesses  are  thick, 
broad,  and  project  horizontally  l)ark\vards. 

Tlie  transverse  processes  of  tlie  kuiibar  vertebrae  are  more  complex  than  they  at  first 
ajipear.    Each  is  c(imi>uuiiiled  of  a  transverse  and  a  costal  jirocess.     The  accessory  jirocess  represents 


L  UMBA  R   I  'ER  TEBR^ 


13 


the  tip  of  the  parfinlli/  sii/ypressed  traiiscerse  process,  ami  the  part  in  front  is  an  nndifferentiateil 
rib.  lietwcori  tlie  tiaii.sversie  and  custal  eleiueiits  sume  largo  vascular  luramiiia  are  usually 
present,  representing  the  costo-trausverse  foramina  of  other  vertebrae.     Oecasionally  the  costal 


Fig.   ]:>. — A  Lvmbau  ViiUTKUiiA.     (Side  view.) 

SUPERIOR  ARTICULAR  PROCESS 


MAMMILLARY  PROCESS 


TRANSVERSE  PROCESS 


ACCESSORY  PROCESS 


INFERIOR  ARTICULAR  PROCESS 


element  differentiates,  and  becomes  a  well-tleveloped  lumbar  rib.  A  glance  at  the  sjjine  will  show 
that  the  acces.sory  tuben-les  are  in  line  with  the  thoracic  transverse  processes,  and  the  costal  ele- 
ments are  in  .series  with  the  ribs  (see  also  fig.  29). 


Fig.  14. — A  Lumbar  Vkrtebra. 
(Showing  the  comijouud  nature  of  the  transverse  process.     Upper  view.) 


MAMMILURY  PROCESS 


ACCESSORY  PROCESS  OR 
TIP  OF  THE  TRUE 
TRANSVERSE  PROCESS 

COSTAL  ELEMENT 
COSTO-TRANSVERSE 
FORAMINA 


Till'  fifth  luniliar  vertebra  has  several  (li.^tinLrdisliiiiLT  features.  The  centrum 
is;  niueh  thicker  in  front  than  behind.  The  inferior  articular  jtroeesses  are  widely 
hsejiarated  to  articulate  with  the  first  sacral  vertelira.  The  transverse  processes 
are  short  and  massive,  and  the  ))e(lieles  are  nia.ssive  an<l  Hattened  I'mni  ai>ove 
ddwnwards;  thr  spinous  process  i-  small. 


14 


THE  SKELETON 


The  pedicles  of  this  voitebra  are  liable  to  a  remarkable  deviation  from  the  conditions  found 
in  other  parts  of  the  spine.  The  peculiarity  consists  of  a  complete  solution  in  the  continuity  of 
the  arch  inimediatelv  behind  the  superior  articular  processes.  In  such  sitecuuens  the  anterior 
part  consists  of  the  body  carryinji  the  pedicles,  transverse  and  superior  articular  i)roce.sses  ;  win  st 
the  posterior  segment  is  coini)osed  of  the  lamiiuB,  spine,  and  inferior  articular  processes.  J  he 
jiosterior  segment  of  the  ring  of  this  vertebra  may  even  consist  of  two  pieces.     There  is  reason  to 

Fig.  ir>.— Vakiatiox  in  the  Fifth  Lumbak  Vektebka.     (After  Turner.) 


believe  that  this  abnormality  of  the  fifth  lumbar  vertebra  occurs  in  five  per  cent,  of  all  subjects 
examined.  Sir  William  Turner,  in  his  report  on  the  human  skeletons  in  the  Challenger 
Reports,  found  seven  examples  among  thirty  skeletons  examined.  The  skeletons  in  which  this 
occurred  were  :  a  Malay,  an  Andamanese,  a  Chinese,  two  Bushmen,  an  Esquimau,  and  a  Negro. 
Turner  has  also  seen  it  in  the  skeleton  of  a  Sandwich  Islander.  A  similar  condition  is  occasion- 
ally met  with  either  laterally  or  bilaterally  in  the  thoracic  vertebrae. 


Fig.  16.— a  Variation  in  the  Fifth  Lumbak  Vertebra.     (After  Turner.) 


.^„-^ 


Each  of  the  five  lumbar  vertebrae  is  readily  recognisable.  The  body  of  the  first  is  deeper 
behind  than  in  iiont,  the  body  of  the  second  is  of  equal  de]ith  in  front  and  behind,  the  bodies  of 
the  third,  fourth  and  fifth  are  deeper  in  front  than  behind,  but  the  third  has  long  transverse  i>ro- 
cesses  and  its  lower  articular  facets  are  not  very  widely  sejiarated  ;  the  fourth  has  much  shorter 
transverse  processes  and  the  lower  articular  facets  are  very  wide  apart,  and  the  filth  is  easily  dis- 
tinguished by  the  special  leatures  already  described. 


THE  SACRAL  AND  COCCYGEAL  VEPxTEBR^ 

In  the  adult  skck'ton,  tlie  five  vertebnr  sucoeedinj]^  the  lumbar  series  are  firmly 
anlvvlosed  to  form  a  single  bone,  the  sacrum  :  the  components  of  the  sacrum  are 
termed  sacral  vertt'brai.  Beyond  the  fifth  sacral,  four,  and  occasionally  five,  other 
rudimentary  vertebne  to  which  the  adjective  coccygeal  is  a])plicd.  are  ankylosed 
in  adult  life,  to  form  a  single  piece,  the  coccyx.  In  advanced  life  the  coccyx 
unites  with  the  sacrum. 


THE  SACRUM 


15 


THE  SACRUM 

This  is  a  large  triangular  bone,  firmly  wedged  between  the  innominate  bones. 
It  forms  the  posterior  boundary  of  the  true  pelvic  cavity.  The  sacrum  is  curved 
upitn  itself  with  the  concavity  looking  forwards.  The  upper  end  of  the  curve 
forms,  Avith  the  body  of  the  fifth  luml)ar  vertel)ra,  an  anterior  projection  known 
as  the  promontory.  The  middle  portion  of  the  anterior  face  of  the  sacrum 
exliiltits  four  transverse  ridges  corresponding  to  the  intervertebral  spaces.  The 
intci'vening  juirtions  are  the  bodies  of  the  vertebra\  The  upper  two  sacral  verte- 
brae are  almost  equal  in  size  to  those  of  the  lumbar  series,  Imt  the  three  lower 
rapidly  diminish  in  size  from  above  downwards.  The  ridges  terminate  laterally 
in  the  anterior  sacral  foramina,  four  pairs  in  all,  which  are  the  interverte- 
bral foramina  of  tlie  sacral  vertcbne,  and  transmit  the  anterior  divisions  of  the  first 


Fig.  17.— The  Sacrum  and  Coccvx.     (Anterior  view.) 


TUBEROSITY 


Pyriformis 


Coccygeus 


Coccygeua 


Levator  Ani 


four  sacral  nerves.  The  ui)per  two  are  also  traversed  ])v  the  lateral  saeral 
arteries.  The  l)one  immediately  »^utside  the  foramina  corresponds  to  the  costal 
processes,  and  the  ])ortion  formed  by  the  second,  third,  and  fourth  sacral  vertel>r;e 
gives  origin  to  the  pijrifonni.-<  mi/.-irlr.  The  lateral  i»art  of  the  fifth  sacral  vertebra 
gives  partial  insertion  to  the  rocn/f^en.':. 

The  i)Osterior  surface  is  strongly  convex  and  rougli.  Tlie  midille  line  is 
occujned  by  four  tubercles  representing  the  suppressed  spinous  processes.  Of 
these  the  first  is  the  largest,  the  .second  and  third  may  lie  ionfiuent,  and  the  fourth 
is  often  absent.  The  bone  on  each  side  of  the  spines  is  formed  by  the  ankylosed 
laminae.  In  the  fourth  sometimes,  but  always  in  the  fiftli.  the  lamina'  fail  to 
meet  in  the  middle  line,  and  this  leaves  a  gap.  the  hiatus  sacralis.  Th«'  median 
l)orders  of  this  hiatus  are  ])rolonged  downwards  as  rounded  processes,  the  sacral 
cornua,  to  whicli  the  posterior  sacro-coecygeal  ligaments  are  attached.  External 
to  the  laminae  is  a  second  series  of   small  itrominences:    these  are  the  articular 


16 


THE  SKELETON 


processes.     The  first  pair  are  large  for  tlie  last  lumbar  vertebra,  the  second  and 
third  are  small,  and  the  fourth  and  fifth  are  inconspicuous. 

Inmu'diatelv  external  to  the  articular  processes  are  the  posterior  sacral 
foramina,  four  on  each  side;  thev  are  smaller  than  the  anterior,  and  give  exit  to 
the  postin-ior  divisions  of  the  first  four  sacral  nerves.     External  to  the  foramina 


18.— The  Sacrum.     (Posterior  view.) 


ARTICULAR  PROCESS 


AURICULAR  SURFACE 


ARTICULAR  PROCESS 
TRANSVERSE  PROCESS 


SACRAL  FORAMEN 


HIATUS  SACRALIS 

LEADING  INTO  THE 

SACRAL  CANAL 

SACRAL  CORNU 


SPINOUS  PROCESS \C-^      »k       % 
Latissimus  dorsi  ~^iX|        pTj 


Multifldus  spinae 


Erector  spinae 


Qluteus  mazimus 


NOTCH  FOR  FIFTH  SACRAL  NERVE 


there  are  five  eminences  on  each  side,  representing  the  fused  transverse  processes. 
The  first  pair  are  large  and  conspicuous,  and  all  give  attachment  to  ligaments  and 
muscles;  the  second  form  part  of  the  articular  surface  for  the  ilium.  The  furrow 
formed  by  the  laminae,   and  bounded  on  the  median  aspect  by  the  spinous,  and 


Fig.  19. — Base  of  Sacrum. 


ARTICULAR  PROCESS 

LAMINA 

SACRAL  CANAL 


■¥ 


f^^>  .'^K  ^'"^l 


externally  l)y  the  articular  processes,  is  known  as  the  sacral  groove,  and  it  lodges 
th<'  iiinltifidiix  spin^T  iiiusclo. 

The  up[)cr  surface,  or  base,  of  the  sacrum  rcsenil)les  the  corresponding  aspect 
of  a  lumbar  vertebra,  and  its  articular  processes  have  well-marked  mammillary 
tul)ercles.  The  conjoint  transverse  and  costal  processes  form  on  each  side  a  broad 
surface,  the  wing  or  ala.     From  ils  margin  the  i{iaca--i  has  a  small  point  of  origin. 


77/ A'  SI'IXAL   COLUMN  17 

Tlif  apex  is  directed  downwards  and  forwards,  and  is  formed  l)y  the  inferior 
aspect  of  tlie  l)ody  of  the  tifth  sacral  vertel)ra;  it  articulates  by  means  of  an  inter- 
vertebral disc  Avith  the  coccyx.  In  advanced  life  the  coccyx  and  sacrum  ankylose 
at  this  spot. 

The  lateral  surface  i>rpsents  in  the  upper  two-thirds  a  broad  irregular  tract 
called  the  auricular  process,  which  is  rough  and,  in  the  recent  state,  covered 
with  til)ro-cartilage  for  union  with  the  ilium.  The  margins  are  rough  for  liga- 
ments. Below  the  auricular  surface  each  lateral  l)order  forms  a  tuberosity  and 
gives  attachment  to  the  greater  and  lesser  sacro-sciatic  ligaments.  Near  the 
extremity  it  presents  a  notch  which  is  converted  into  a  foramen  by  articulation 
with  the  coccyx.  Through  the  space  tlius  enclosed,  the  anterior  branch  of  the  fifth 
sacral  nerve  issues.  Sometimes  the  foramen  is  represented  by  a  notch  even  when 
the  sacrum  and  coccyx  are  articulated.  The  middle  of  the  sacrum  is  occupied  by 
a  continuation  of  the  spmal  canal.  It  is  triangular  in  form  at  the  base,  and  flat- 
tened towards  the  apex.  It  lodges  the  terminal  branches  of  the  cauda  equina,  the 
filum  terminale,  and  the  lower  extremity  of  the  dura  mater. 

The  sacrum  exhibits  sexual  and  racial  differences.  In  the  female  it  is  usually 
wider,  much  less  curved,  and  is  directed  more  obliquely  backwards,  than  in  the 
male,  and  in  the  lower  races  the  sacrum  is  relatively  kmger  than  in  the  higher. 

Muscles. — The  following  muscles  a-re  attached  to  the  sacrum: — Pyriformis, 
coccvgeus,  iliacus,  latissimus  dorsi,  multifidus  spina?,  erector  spina?,  gluteus  maxi- 
mus";  and  the  occasional  muscles,  namely,  curvator  coccygis,  extensor  coccygis, 
and  the  agitator  cauda?. 

Ligaments. — Anterior  and  posterior  common  ligaments  of  the  spine;  anterior 
and  posterior  sacro-coccygeal ;  greater  and  lesser  sacro-sciatic,  anterior  and  posterior 
sacro-iliac,  two  capsular,  ligamenta  subflava,  and  the  supraspinous. 


THE  COCCYX 

The  coccyx  in  the  adult  is  made  up  of  four  and  occasionally  five  vestigial  ver- 
tebne  ankylosed  to  one  another.  Rarely  the  number  of  segments  is  reduced  to 
tln-('c.  The  first  two  segments  contain,  in  addition  to  the  body  of  a  vertebra,  traces 
of  articular  and  transverse  processes  :  the  rest  are  mere  nodules  of  bone,  repre- 
senting centra.  The  anterior  surface  gives  attachment  to  the  anterior  sacro-coccy- 
geal ligament;  and  near  its  tip  to  the  levator  an! :  it  is  in  relation  with  the  posterior 
surface  of  the  second  part  of  the  rectum. 

The  posterior  surface  is  convex,  and  presents  above  a  laterally  projecting  ])rocess, 
the  rudimentary  transverse  process  of  the  first  segment,  and  along  its  margin  affords 
attachment  to  the  f/liitfiis  iiHixiiiins  muscle. 

The  lateral  borders  are  thin:  they  receive  parts  of  the  greater  sacro-sciatic  liga- 
ments and  of  the  cocny^f'/s-  muscle.  The  base  has  an  oval  facet  for  the  fifth  sacral 
vertebra,  and  presents  the  two  long  coccygeal  cornua,  formed  by  the  remains  of 
the  pedicles  and  superior  articular  processes  of  the  first  segment,  for  the  posterior 
sacro-coccygeal  ligament.  The  junction  of  the  coccyx  and  sacrum  completes  the 
foramen  of  exit  for  the  fifth  sacral  nerve.  In  many  skeletons  the  foramen  is  incom- 
plete externally.  The  apex  is  rounded  and  gives  attachment  to  the  sjihlnder  ani, 
and  in  front  to  the  levator  ani  muscles  on  each  side  of  the  median  line. 


THE  SPINAL  COLUMN  IN  GENERAL 

^^'lu■n  the  various  vertebrfe  are  in  their  relative  positions,  the  whole  is  termed 
the  spinal  column.  It  occupies  the  median  line  of  the  posterior  aspect  of  the  trunk. 
Suixriorly,  it  supports  the  head;  laterally,  it  gives  attachment  t(»  the  ribs;  these  in 
their  turn  receive  the  weight  of  the  upjjcr  limbs.  Inferiorly,  the  sacrum  affords 
attachment  to  the  innominate  bones,  by  which  the  weight  of  the  trunk  is  trans- 
mitted to  the  lower  limbs.     The  spinal  colunm  is  the  axis  of  the  skeleton. 

It  varies  in  length  in  different  persons,  but  on  an  average  it  measures,  from  the 
atlas  to  the  tip  of  the  coccvx,  following  the  curve.  70  cm.  (2S"j.  Of  this,  the 
2 


18 


THE  SKELETON 


Fig.  2u. — The  Spine.     (Lateral  view.) 


VERTEBRA  PROMINENS 


THE  ELEVENTH  THORACIC  IS  THE 
ANTl-CUNAL  VERTEBRA 


'm 


'w 


Vm.  y   THORACIC 


1 21 


iin 


|-    LUMBAR 


■   SACRAL 


iSfe.^^   j 


THE  VKRTEBR.E  19 

cervical  sijine  iiK-asures  12'")  cm.  (o"),  the  tlioracic  27 'o  cm.  (11"),  tlic  lumbar 
17 '5  cm.  (7"j,  and  the  sacro-coccygeal  portion  12-r)  cm.  (5"). 

Viewed  in  profile,  the  column  ijresents  four  curves  :  the  first,  or  cervical,  is 
convex  anteriorly;  the  thoracic  is  much  larger  and  longer,  with  its  concavity  for- 
ward; the  lumbar  curve  lias  its  convexity  directed  anteriorly,  and  ends  somewhat 
abruptly  at  the  sacro-vertebral  angle ;  and  to  this  succeeds  the  pelvic  curve, 
which  corresponds  to  the  hollow  of  the  sacrum.  In  addition  to  these,  the  whcjle 
column  has  a  slight  lateral  curve  with  the  convexity  to  the  right,  probably  due  to 
nuiscular  action. 

Viewed  from  the  front,  the  superimposed  bodies  present  three  pyramids.  The 
first  is  formed  by  the  cervical  vertebrie  from  the  second  to  the  seventh.  The  bodies 
of  the  lumbar  and  thoracic  vertebnx>  form  a  much  longer  pyramid.  The  third  is 
inverted,  and  formed  by  the  sacrum  and  coccyx. 

Posteriorly,  the  colunni  presents  a  median  and  two  lateral  rows  of  processes. 
The  median  row  is  formed  by  the  spinous  "processes.  In  the  cervical  spine,  with 
the  exception  of  the  first  and  the  seventh,  they  are  bifid.  In  the  thoracic  set  they 
end  in  rounded  tubercles,  are  long,  and  for  the  most  part  directed  obliquely  down- 
M'ards,  but  in  the  lower  part  they  become  more  horizontal  until  the  eleventh  is 
reached.  The  spine  of  the  eleventh  thoracic  vertebra  is  small  and  almost  horizontal; 
this  is  the  aitti-cHnal  vertebra.     In  the  lumliar  region  the  spinous  processes  are  short, 

Fui.  -Jl. — A  Divn)ED  Thokacic  Vertebra.     (After  Turner.) 


stout  plates  of  l)one,  with  their  l^orders  set  vertically;  in  the  sacrum  they  are  ves- 
tigial, and  in  the  coccyx  completely  suppressed. 

The  lateral  rows  are  formed  by  the  transverse  processes,  which  are  most  marked 
in  the  thoracic  region,  where  they  are  rib-bearers.  In  the  cervical  spine  they  are 
in  the  same  ]:»lane  as  the  ribs.  The  articular  processes  in  the  cervical  region  are  in 
series  with  tlie  transverse  processes  of  the  thoracic  vertel)ra}. 

Between  the  ridges  formed  by  the  spinous  and  transverse  processes  we  recognise 
the  vertebral  grooves  in  which  muscles  are  lodged.  The  floor  of  each  groove  is 
formed  by  the  laminae  and  articular  processes,  with  their  manmiillary  tubercles  in 
the  lumbar  and  lower  thoracic  regions.  Similar  tubercles  are  present  on  the  inferior 
articular  processes  of  the  three  lower  cervical  vertebra".  The  inter\'ertebral  foramina, 
oval  in  shape,  are  small  in  the  cervical,  l^ut  gradually  increase  in  size  in  the  thoracic, 
and  arc  largest  in  the  lumbar  region. 

Ossification. — The  various  ossific  centers  for  the  vertebra^  are  deposited  in  the 
cartilage  which,  very  early  in  embryonic  life,  surrounds  the  notochord  and  gradually 
encloses  the  spinal  cord. 

A  typical  vertebra  arises  from  three  primary  and  numerous  secondary  centres. 
The  primary  centres  ajipear  during  the  sixth  week  of  embryonic  life.  In  the 
thoracic  region  the  nucleus  for  the  body  is  first  seen,  but  in  the  cer\'ical  region  the 
lateral  centres  make  their  appearance  somewhat  earlier.  The  nucleus  for  the  body 
is  deposited  around  the  centre,  and  tpiickly  becomes  bilol>ed.  This  bilobed,  or 
dumb-bell,  shajjc  is  often  so  jn-onounced  as  to  give  rise  to  the  appearance  of  two 


20  THE  SKELETON 

distinct  niuk-i.  Sometimes  the  nucleus  is  double,  and  remains  separate  throughout 
life,  tlie  vertebra  l»eing  divided  by  a  vertical  fissure  (fig.  21).  The  bifid  character 
of  the  nucleus  of  the  vertebral  l)ody  is  further  emphasised  by  the  occasional  occur- 
rence of  half-vertcbn¥.  The  lateral  centres  are  deposited  near  the  bases  of  the 
superior  articular  processes,  and  give  rise  to  the  pedicles,  lamina?,  articular  pro- 
cesses, and  a  large  part  of  the  transverse  and  spinous  processes. 

At  h\T\\\  a  vertebra  consists  of  three  parts — a  body  and  two  lateral  masses 
connected  by  hyaline  cartilage.  The  line  of  union  of  the  lateral  masses  with  the 
V)odies  is  known  as  the  aearo-centml  suture  (fig.  22),  and  this  is  not  obliterated  for 
several  years  after  l)irth.  An  examination  of  a  thoracic  vertebra  at  the  fifth  year 
will  show  tliat  a  portion  of  the  body  of  each  vertebra  is  derived  from  the  lateral 

Fig.  22. — A  Vektebra  at  Birth. 


UTERAL  MASS 


NEURO-CENTRAL  SUTURE 
CENTRUM  OR  BODY 

masses,  and  that  the  demi-facets  for  the  rib-heads  are  situated  behind  the  neuro- 
central  suture,  and  therefore  belong  to  the  pedicles. 

During  the  early  years  growth  progresses  rapidly,  and  at  puberty  the  secondary 
centres  make  their  appearance  in  the  cartilaginous  tips  of  the  transverse  and 
spinous  processes.  During  the  seventeenth  year  a  meniscus  of  bone  forms  around 
the  margins  of  the  superior  and  inferior  surfaces  of  the  centra.  These  are  the 
epiphysial  discs;  they  are  thickest  at  the  periphery,  and  gradually  become  thin 
towards  the  central  perforation.  By  the  twenty-fifth  year  the  various  secondary 
nuclei  have  coalesced  wdth  the  main  bone,  and  the  vertebra  is  then  complete. 

In  several  verteVjrse  the  mode  of  ossification  deviates  from  the  account  given 
above,  and  requires  separate  consideration. 

The  atlas. — This  bone  has  three  primary  centres — one  for  each  lateral  mass 

Fig.  23.— Lumbar  Vertebra  at  the  Eighteenth  Year  with  Secondary  Centres. 

epiphysial  plate  or  disc 

—    mammillary  tubercle 
-transverse  process 


-SPINOUS  PROCESS 
EPIPHYSIAL  PLATE  OR  DISC 


(neural  arch)  ap])earing  in  tlie  sixth  week  of  embryonic  life.  The  third  appears 
a  few  montlis  after  Ijirth  for  the  anterior  arch.  The  lateral  portions  coalesce 
]»osteri(>iiy  al)OUt  the  fourth  year;  the  union  with  the  anterior  nucleus  is  delayed 
until  the  sixth  year.  An  additional  centre  occasionally  appears  for  the  posterior 
segment. 

The  axis. — This  is  the  most  exceptional  of  all  the  vertebrtc.  It  has  the  usual 
three  primary  nuclei — one  for  the  body,  and  one  on  each  side  for  the  neural  arch. 
The  centre  for  the  body  appears  in  the  embryo  about  the  fifth  month,  and  a  feAV 
weeks  later,  two  laterally  disposed  nuclei  are  seen  for  the  base  of  the  odontoid 
process;  these  fuse  together  in  the  middle  line,  and  by  the  third  year  ankylose 
peripherally  to  the  centrum  of  the  axis.  The  line  of  iinion  between  the  body  of 
the  axis  and  the  odontoid  ])rocess  is  indicated  even  in  advanced  life  by  a  persistent 


THE  VERTEBRAE 


21 


loiitifular-shaped  cartilage.  During  the  second  year  a  nucleus  appears  at  the  tij) 
of  the  odontoid  process;  it  joins  the  main  mass  at  the  fourth  year.  An  epiphysial 
meniscus  Ioy  the  inferior  and  superior  surfaces  of  the  centrum  of  the  axis  appears 
ahout  the  seventeenth  year.  As  a  rule,  the  superior  meniscus  is  represented  Ity 
a  few  earthy  granules. 

Fig.  24.— Immaturk  Atlas.     (Third  year.) 


The  sixth  and  seventh  vertebrae. — In  the  cervical  vertebrae  the  pedicles,  or 
anterior  extremities  of  the  neural  arches,  take  a  much  larger  share  in  forming  the 
centrum  than  is  the  case  Avith  the  remaining  vertebrae.  The  sixth,  seventh,  and 
possir)ly  other  cervical  vertebrae  present  an  additional  centre  on  each  side  of  the 
neural  arch  for  the  costal  process;  it  appears  before  birth.     The  costal  processes  of 


Fig.  25. — Development  of  the  .Axis. 


Suspensory  ligament 

NUCLEUS  FOR  TIP  OF  OOONTOIO  PROCESS 


LATERAL  CENTRES  FOR  OOONTOIO  PROCESS 


EPIPHYSIAL  PLATE  OR  DISC 
PEDICLE 


CENTRUM  OR  BODY 
EPIPHYSIAL  PLATE 


the  seventh  cervical  not  infrequently  fail  to  ankylose  with  the  vertebra;  when  this 
is  the  case,  the  processes  l)ecome  cervical  riljs.  Sometimes  these  ribs  are  of  large 
size. 

The  lumbar  vertebrae. — In  the  lumVnir  vertebra?,  two  additional  centres  make 


Fig.  26.— The  Axis  (from  an  Adilt)  in  Section. 


OOONTOIO  PROCESS 


CARTILAGE  REPRESENTING  THE  INTER- 
VERTEBRAL DISC  BETWEEN  THE  ODON- 
TOID PROCESS  AND  THE  BODY  OF  THE 
AXIS 


BODY  OF  AXIS 


their  appearance,  about  puberty,   namely,   for   the   mammillary  tubercles  on  the 
jjosterior  aspect  of  each  superior  articular  process. 

The  fifth  lumbar  occasionally  diff(>rs  in  the  mode  of  ossification  of  its  arch;  in 
many  skeletons  this  arch  is  derived  from  four  nuclei.  There  is  a  nucleus  on  each 
side  for  the  pedicle,  the  transverse  pnxess,  and  the  superior  articular  process;  and 


•>0 


THE  SKELETOX 


one  on  each  side  for  the  hmiina,  inferior  articular  process,  and  the  lateral  half  of 
the  spinous  process  (fig.  28).  The  pedicles  may  fail  to  join  the  laminae;  more 
rarely  the  laniin;e  fail  to  fuse  (fig.  16). 

The  sacral  vertebrae. — In  addition  to  the  three  primary  vertediral  centres, 
the  three  upper  sacral  vertebrae  have  each  an  extra  pair  corresponding  to  the 
costal  processes  of  the  seventh  cervical  vertebra;  they  appear  at  the  seventh  month. 
These  processes  are  very  large  in  the  first  sacral,  smaller  in  the  second,  and  very 
small  in  the  third.  Although  the  various  primary  centres  of  the  sacral  vertebra? 
appear  much  later  than  in  other  regions  of  the  column,  yet  they  are  all  visiljle  at 
Itirth.     The  centrum  of  each  sacral  vertelira  develops  a  superior  and  an  inferior 

Fig.  27. — Ax  Immature  Cervical  Vertebra. 


NEURO-CENTRAL  SUTURE 


epiphysial  meniscus,  and  eventually  the  five  vertebrae  fuse  to  form  a  single  bone, 
the  sacrum.  Even  in  advanced  life  the  intervertebral  discs  between  the  sacral 
vertebrae  persist  in  the  centre  of  the  bone.  The  ear-shaped  lateral  articular  facet 
on  the  side  of  the  sacrum  arises  from  two  additional  centres  on  each  side,  about  the 
eighteenth  year.     The  total  number  of  ossific  centres  for  the  sacrum  is  thirty-five. 

The  coccygeal  vertebrae. — These  are  cartilaginous  at  birth.  A  few  months 
later  the  first  segment  ossifies.  The  remaining  three  ossify  from  above  downwards 
before  the  twentieth  year.  By  the  twentieth  year  the  first  three  have  usually 
coalesced.  The  fourth  fuses  with  them  later,  and  the  coccyx  ankyloses  with  the 
sacrum,  as  a  rule,  late  in  life. 


Fig.  28.— Ossification  of  the  Fifth  Lumbar  Vertebra. 


NEURO-CENTRAL  SUTURE 
CENTRUM 


The  Serial  Morphology  of  the   Vertebrce 

Although  at  first  sight  many  of  the  vertebrae  exhibit  peculiarities,  nevertheless  a  study  of 
tlie  mode  by  which  they  develop,  and  their  variations,  indicates  the  serial  homology  of  the  con- 
stituent parts  of  the  vertebrae  in  each  region  of  the  column. 

The  centrum,  or  body  of  the  vertebra,  is  that  part  which  immediately  surround.s  tlie  noto- 
chord.  This  part  is  present  in  all  the  vertebras  of  man,  but  the  centrum  of  the  atlas  is  dissociated 
from  its  neural  arch,  and  ankylu.sed  to  the  body  of  tlu;  axis.  The  reasons  for  regarding  the  odon- 
toid process  as  the  body  of  the  atlas  are  these  :  In  the  embryo  the  notochord  passes  through  it 
on  its  way  to  the  base  of  the  cranium.  Between  the  odontoid  process  and  the  body  ol'  the  axis, 
there  is  a  swelling  of  the  notochord  in  the  early  embryo  as  in  other  interveitebral  i-egions.  This 
swelling  is  later  indicated  by  a  small  intervertebral  disc  hidden  in  the  bone,  Imt  i)ersistent  even  in 
old  age.  The  odontoid  process  arises  from  primary  centres,  and  in  chelonians  it  remains  as  a 
separate  ossicle  throughout  life  ;  in  Ornithorhynchus  it  remains  distinct  for  a  long  time,  and  it  has 
been  found  separate  even  in  an  adult  man.  Lastly,  in  man  and  many  mammals,  an  epiphysial 
I)late  develops  between  it  and  the  true  body  of  the  axis. 


THE   VKRTKHR.E 


23 


The  anterior  segment  of  the  atlas  is  most  probably  an  enlarged  hypapopliysls  or  subvertebral 
wedge-bone,  which,  in  lizards,  exists  on  the  ventral  aspect  of  the  column  oetween  individual 
centra.  Siujilar  ossicles  occur  in  the  lumbar  region  of  the  mole.  (Froriep  regard.s  this  segment 
as  the  ossified  primitive  ventral  arch  which  precedes  the  body  and  which  disappears  after  the 
formation  of  the  latter  in  all  the  other  vertebrae.) 


Fig.  29.— Morphology  of  the  Transverse  and  Articular  Processes. 


CERVICAL 
VERTEBRA 


TRANSVERSE  PROCESS 
COSTO-TRANSVERSE  FORAMEN 


NEURO-CENTRAL  SUTURE 
CERVICAL  RIB 


COSTAL  PROCESS 


TRANSVERSE  PROCESS 
COSTO-TRANSVERSE  FORAMEN 


NEURO-CENTRAL  SUTURE 
RIB 


TRANSVERSE  PROCESS 
LUMBAR  RIB 


SACRAL 
VERTEBRA 


NEURO-CENTRAL  SUTURE 
COSTAL  PROCESS 


The  neural  arches  and  spinous  processes  are  easily  recognised  throughout  the  various  parts  of 
the  column  in  which  complete  vertebrfc  are  present.  _  .  .       , 

The  articular  processes  are  of  no  morphological  value,  and  do  not  require  consideration  here. 

The  transverse  processes  offer  more  difficulty.  They  present  themsolve.?  in  the  simplest  form 
in  the  thoracic  series.     Here  they  articulate  with  the  tubercles  of  the  ribs.     The  transverse  pro- 


24 


THE  SKELETOX 


cess  and  the  neck  of  the  rib  enclose  an  arterial  foramen,  the  costo-transverse.  In  the  cervical 
reirion  this  rib,  or  costal  element,  and  the  transverse  process  are  fused  together,  but  the  conjoint 
I)rocess  thus  formed  is  jnerced  by  the  costo-transverse  foramen.  The  compound  nature  of  the 
l)rocess  is  indicated  by  the  fact  that  the  anterior  or  costal  processes  in  the  lower  cei-vical  vertebrae 
arise  from  additional  centres  and  occasit)nally  retain  their  independence  as  cervical  ribs.  These 
l)rocesses  in  Sauropsida  (birds  and  reptiles)  are  represented  by  free  ribs.  In  the  lumbar  region, 
the  compound  nature  of  the  transverse  process  is  further  marked.  The  true  transverse  process  is 
sreatly  suppressed,  and  its  extremity  is  indicated  by  the  accessory  tubercle.  Anterior  to  this  in 
the  adult  vertebra  a  group  of  holes  represents  the  costo-transverse  foramen,  and  the  portion  in 
Iront  of  this  is  the  costal  element.     Occasionally  it  will  persist  as  an  independent  ossicle,  the 

lumbar  rib.  t,.    i  •      i      /. 

In  the  sacral  series  the  costal  elements  are  peculiarly  modified  m  the  first  three  vertebrae  to 
form  piers  of  bone  for  articulation  with  the  ilium.  The  costo-transverse  foramina  are  completely 
obscured.  In  rare  instances  the  first  sacral  vertebra  will  articulate  with  the  ilium  on  one  side, 
but  remain  free  on  the  other.  Under  such  conditions  the  free  process  exactly  resembles  the 
elongated  transverse  jjrocess  of  a  lumbar  vertebra.  The  first  three  sacral  vertebrae  which  develop 
a  costal  iirocess  (rib)  for  articulation  with  the  ilium  are  true  sacral  vertebrae.  Those  ankylosed 
below  these  are  pseudo-sacral.  A  glance  at  fig.  29  will  show  the  homology  of  the  various  parts  of 
a  vertebra  from  the  cervical,  thoracic,  lumbar  and  sacral  regions. 

The  mammillary  processes  are  vestiges  of  the  greatly  elongated  articular  processes  of  such 
mammals  as  the  dog,  armadillo,  &c. 


THE  BONES  OF  THE  SKULL 

The  skeleton  of  the  head  is  called  the  skull :  it  contains,  in  the  adult,  twenty- 
nine  separate  bones.  For  descriptive  purposes  they  are  divided  in  two  groups  : 
those  of  the  skull  proper,  and  the  appendicular  elements. 


I.  The  Skull 


r  Occipital. 
(a)  Basilar  Bones  J  Sphenoid. 
I  Temporals 


(/>)  Roof  Bones 


r  Parietals. 
-{  Frontal. 
I  Epipterics. 


(r)  Nasal  Region 


((/)  Facial  Bones 


Maxilla?. 

Palatines. 

Malars. 


[-  Ethmoid. 

I  Sphenoidal  tur- 

binals. 
!  Turbinals. 

Lachrymals. 

Vomer. 
I  Nasals. 


Mandible. 
Malleus. 


II.  Appendicular  Elements 

Incus.  Hyoid. 

Stapes.  Styloid. 


Internal  pterygoid. 


The  epipterics  are  not  always  separate  in  the  adult  skull:  the  s^^/ok/ ankyloses 
with  the  temporal,  and  the  internal  •pterygoid  Avith  the  sphenoid. 


THE  OCCIPITAL 

This  bone  forms  tlie  l)ack  and  a  portion  of  the  base  of  the  skull.  At  birth  it 
consists  of  four  distinct  parts  disposed  around  the  foramen  magnum  (fig.  34). 
These,  in  the  adult,  fuse  together  and  form  a  single  bone,  which  ankyloses  with 
the  sphenoid.  The  four  ])arts  of  the  occipital  are — the  squamo-occipital,  two 
ex-occipitals,  and  a  basi-occipital.  The  lines  of  union  of  these  parts  are  easily 
distinguished  even  in  the  oldest  skull. 


THE  OCCIPITAL 


25 


The  squamo-occipital  is  suucer-shaped,  deeply  concave  on  its  cerebral,  l)ut 
convex  on  its  external  aspect.  It  consists  of  two  parts  which  have  different  modes 
of  origin.  The  posterior  surface  is  divided  by  a  ridge,  the  superior  nuchal  line, 
into  a  lozenge-shaped  superior  portion  with  a  smooth  surface  and  an  inftiior  louuh 
j)ortion.  The  upi)er  is  the  interparietal,  and  tlie  lower  the  supra-occipital  seg- 
ment. The  interparietal  portion  not  infrec^uentlv  persists  as  an  indcpt  iid^nt  ossicle 
(fig.  35). 

The  supra-occipital  is  dividiMJ  into  two  lateral  lialves  by  a  median  vertical  ridge 
— the  external  occipital  crest — which  ascends  from  the  middle  of  the  i)osterior 
margin  of  the  foramen  magnum,  to  terminate  at  the  external  occipital  protuber- 
ance, or  inion,  near  the  middle  of  the  squamo-occipital.  The  protulxrance  and 
crest  give  attachment  to  the  ligamentum  nucha?. 

Each  lateral  half  of  the  supra-occipital  presents  three  pairs  of  transverse  ridges, 
the  nuchal  lines.  Of  these  the  superior  is  usually  the  least  conspicuous,  but 
most  curved;  frequently  it  is  absent;  l)eginning  at  the  external  occipital  protuljer- 
ance,  it  curves  outwards  to  the  lateral  angle.  It  affords  attachment  to  the  epi- 
cranial aponeurosis  and  to  few  fibres  of  the  occipito-fruntali-i  muscle. 


Fio.  30. — The  Occipital.     (External  view.) 

Trapezius  INION  OR  EXTERNAL-OCCIPITAL  PROTUBERANCE 


SUPERIOR  NUCHAL  LINE 

Occipito-frontalis 

MIDDLE  NUCHAL  LINE 

Sterno-mastoid 

Splenius  capitis 

Rectus  cap.  post.  min. 
Rectus  cap.  post.  maj. 

Superior  oblique 

INFERIOR  NUCHAL  LINE 


Rectus  capitis  lateralis 


POSTERIOR  CONDYLOID 
FORAMEN 


JUGUUR  PROCESS 


BA3I-0CC1PITAL 


The  middle  nuchal  line  (sometimes  called  the  superior  curved  line)  commences 
a  little  distance  Ix'low  the  protuberance,  and  curves  outwards  to  end  below  the 
lateral  angle.  In  some  cases  the  sui)erior  and  middle  nuchal  lines  are  confluent 
in  their  outer  thirds,  and  form  a  prominent  ridge  for  the  insertion  of  the  sterno- 
mastoid  and  splenius  capitis  muscles.  When  these  muscles  are  well  developed,  there 
is  a  fairly  wide  interval  ])etween  the  lines. 

The  inferior  nuchal  line  begins  near  tlie  middle  of  the  crest  and  cur\-(\«^  down- 
wards to  the  jugular  ])rocess. 

Of  the  spaces  deliminated  by  these  lines,  that  between  the  superior  and  middle 
is  occupied  ^yy  the  trapezius,  and  frequently  by  the  sterno-mastoid  and  splenins  capitis 
muscles.  The  space  lietween  the  middle  and  inferior  receives  the  complexus  and 
superi(n-  oblique,  and  the  space  between  the  inferior  line  and  the  foramen  magnum 
IS  occupied  V)y  the  rectus  capitis  posticus  minor,  and  the  rectus  capitis  postims  vuijar 
muscles. 

The  cerebral  surface  is  deeply  concave,  an<l  divided  by  crucial  ridges  into 
four  fossae,  of  which  the  upi)er  two  accommodate  the  occipital  l()bes  of  the  cere- 
brum, the  lower  i)air  the  cereljellar  hemis])heres.  The  ridges  intersect  one  another, 
and  at  the  point  where  they  cross,  an  eminence,  the  internal  occipital  protuber- 


2() 


THE  SKKLKTOX 


ance,  is  soon.  Tho  vortical  ridge  runs  ujiwards  to  the  superior  angle  of  the  bone 
and  furnishes  attachment  for  the  falx  cerebri;  the  portion  of  the  ridge  below  the 
1  irotuboranco,  tho  internal  occipital  crest,  is  for  tho  falx  cerebelli.  As  it  approaches 
tho  foramen  magnum  tliis  ridge  divides,  becoming  lost  upon  its  margins.  The 
auirlo  of  divorgonce  is  sometimes  occupied  by  a  shallow  fossa  for  the  extremity  of 
the  vermiform  ]»rocess  of  the  cerebellum,  and  is  called  the  vermiform  fossa.  The 
liorizontal  ridge  is  deeply  grooved;  to  the  edges  of  the  groove  the  tentorium  cere- 
liolli  is  attached;  the  grooves  lodge  the  greater  part  of  the  lateral  sinuses.  To  one 
side  of  the  internal  occipital  protuberance,  usually  tho  right,  the  furrow  for  the 
sinus  is  deeper  and  frequently  forms  a  circular  fossa  Avhich  receives  the  torcular. 
This  fossa  is  sometimes  exactly  in  the  middle  line. 

The  squamo-occiintal  has  three  angles  and  four  borders.  The  superior  angle 
tits  into  the  space  formed  by  the  union  of  the  two  parietals.  Tho  lateral  angles 
mark  the  external  limits  of  the  middle  nuchal  lines,  and  occupy  the  angle  formed 
bv  the  parietal  and  mastoid  ])ortion  of   tho  petrosal  on    each  side.      The  ridge 

Fig.  31. — Occipital  Bone,  Cerebral  Surface. 

SUPERIOR  ANGLE 


FOR    SUPERIOR  LONGITUDINAL 
SINUS  AND  FALX  CEREBRI 


CEREBRAL  FOSSA 


GROOVE  FOR  LATERAL  SINUS 


LATERAL  ANGLE 


CEREBELLAR  FOSSA 

GROOVE  FOR  LATERAL  SINUS 

JUGULAR  PROCESS     - 
FOR  PETROSAL 


BASI-OCCIPITAL 


between  the  su]H'rior  and  lateral  angles  is  tho  superior  border ;  it  is  serrated 
deeply,  and  artictilatos  with  the  posterior  border  of  tho  parietal  to  form  the  lamb- 
doid  suture.  Tho  inferior  border  extends  from  the  lateral  angle  to  the  jugular 
process  ;  it  articidatcs  with  tlie  mastoid  portion  of  the  petrosal. 

Tho  ex-occipitals  form  the  lateral  boundaries  of  the  foramen  magnum.  The 
lateral  surface  of  oaih  ox-occipital  is  extended  outwards  to  form  a  (juadrilatoral 
buttress  of  bone,  the  jugular  process.  This  has  an  outer  rough  surface  for  articu- 
lation with  the  jugular  surface  of  the  petrosal.  Its  anterior  border  is  doo])ly  notched 
to  form  the  posterior  lioundary  of  the  jugtdar  foramen,  and  the  notch  is  directly 
continuous  with  a  groove  on  the  upper  surface  which  lodges  the  termination  of  tho 
lateral  sinus.  Its  under  surface  gives  attachment  to  the  rectus  capitis  lateralis  antl 
the  olili({ue  occipito-atlantal  ligament.  The  pneumatic  mastoid  colls  occasionally 
extend  into  this  process.  Ixaroly  a  process  of  bone  projects  from  its  under  surface 
and  represents  the  paroccipital  process  present  in  many  manunals.  The  rest  of  the 
ex-occipitals  enter  into  the  formation  of  the  condyles,  and  will  be  separately  de- 
scribed. 


FORAMEN  MA GNUM 


27 


The  basi-occipital  is  a  quadrilateral  plate  of  bone.  Its  sii])erior  surface  is 
concave  for  tlic  incdulla  olylongata.  Inferiorly  it  is  rough,  and  presents  the 
pharyngeal  tubercle,  to  which  the  median  portion  of  the  fibrous  bag  of  the  pharynx 
is  attaclied.      in  front  of  the  tubercle  near  the  anterior  end  of  the  bone  there  is 


Fig.  32. — Ckkebral  Surface  of  the  Occipital,  showing  an  Occasional  Disposition  <jf 

THE  Channels. 


VERMIFORM  FOSSA 


POSTERIOR  CONDYLOIO 

FORAMEN 

ANTERIOR  CONDYLOID 

FORAMEN 


often  a  shallow  fossa,  which  originally  received  the  primitive  anterior  extremity  of 
the  foregut.  The  rectus  capitis  anticus  major  and  minor-  muscles  are  inserted  into 
this  surface.  Anteriorly  the  basi-occipital  is,  in  the  adult,  ankylosed  to  the  basi- 
sphenoid.  Posteriorly  it  has  a  smooth,  rounded,  narrow,  concave  border  forming 
the  anterior  boundary  of  the  foramen  magnum. 

Fig.  33. — The  Fokamen  Magnim  at  the  Sixth  Year. 


POSTERIOR  CONDYLOID  FORAMEN 


ex-og:ipital  portion  of  the 

CONDYLE 

JUGULAR  PROCESS 

ANTERIOR  CONDYLOID  FORAMEN 
BASI-OCCIPITAL  PORTION  OF  THE 
CONDYLE 


BASI-OCCIPITAL 


The  extremities  of  this  liorder  enlarge  to  join  the  ex-occipitals,  and  form  tlie 
anterior  extremities  of  the  condyles.  The  lateral  l)orders  are  rough  below,  and 
articulate  witli  tlie  inferior  borders  of  the  petrosals.  Aliove  they  are  grooved  for  the 
inferior  petrosal  sinus. 

The  foramen  magnum  is  oval  in  shaiie.  with  its  major  axis  in  the  long  a.xis  of 


28 


THE  SKELETON 


the  skull.  Ill  front  of  the  middle  it  is  encroached  u])on  l)y  the  condyles.  It  is 
bounded  posteriorly  by  the  supra-occipital,  anteriorly  by  the  basi-occipital,  and 
laterally  ])y  the  ex-occipitals.  Sometimes  a  facet  exists  at  the  anterior  margin  for 
articulation  with  the  odontoid  process.  This  is  the  tertiary  occipital  condyle.  The 
margin  of  the  foramen  gives  attachment  behind  the  condyles  to  the  posterior  occipito- 
atlantal  ligament. 

The  condyles  are  two  oval  processes  of  bone,  with  smooth  articular  surfaces, 
covered  in  tlie  recent  state  with  cartilage.  They  are  received  into  the  superior 
articular  cups  of  the  atlas.  The  condyles  converge  anteriorly  but  diverge  posteriorly. 
Their  margins  give  attachment  to  capsular  ligaments,  and  a  prominent  tubercle  in 
the  middle  of  the  median  border  of  each  condjde  is  for  the  check  ligament.  A  for- 
amen, the  anterior  condyloid,  traverses  the  upper  part  of  each  condyle;  it  trans- 
mits the  hypoglossal  nerve,  and  a  twig  of  the  ascending  pharyngeal  artery  with  its 
vense  comites;  frequently  this  foramen  is  divided  by  a  delicate  spicule  of  bone. 
Posterior  to  each  condyle  is  a  depression,  the  posterior  condyloid  fossa,  which  receives 


Fig.  34. — The  Occipital  at  Birth.     (Anterior  view.) 


INTERPARIETAL  PORTION    (DEVELOPS  IN 
MEMBRANE) 


THE  INTERPARIETAL  AND  SUPRA- 
OCCIPITAL  PORTIONS  FORM  THE 
SQUAMO- OCCIPITAL  OF  THE 
ADULT 

SUPRA-OCCIPITAL    PORTION    (DEVELOPS 
IN  CARTILAGE) 


BASI-OCCIPITAL 


the  hinder  edge  of  the  articular  cavity  of  the  atlas  when  the  head  is  extended;  the 
floor  of  this  depression  is  occasionally  perforated  by  the  posterior  condyloid  foramen, 
which  transmits  a  vein  from  the  lateral  sinus. 

Articulations. — The  occipital  bone  is  connected  by  suture  with  the  two  parie- 
tals,  the  two  temporals,  and  the  sphenoid;  by  means  of  the  condyles  it  articulates 
with  the  atlas;  and  under  the  exceptional  condition  of  a  tertiary  occipital  condyle, 
with  the  odontoid  process  of  the  axis. 

Muscles. — Attached  to  the  occipital  bone: — 


OcciiHto-frontalis. 
Trapezius. 

Sterno-cleido-mastoid. 
Complexus. 
Splenius  capitis. 
Superior  oblique. 


Rectus  capitis  anticus  major. 
Rectus  capitis  anticus  minor. 
Rectus  capitis  posticus  major. 
Rectus  capitis  posticus  minor. 
Rectus  capitis  lateralis. 
Azygos  pharyngei  (when  present). 


Tin:  srin:.\oin 


29 


Ligaments  : — 

Ligamentum  nuchse. 

Capsular. 

Posterior  occii)ito-atlantal. 

Anterior  occipito-atlantal. 

Oblique  occipito-atlantal. 


Suspensory  ligament. 

Cheek  ligaments. 

Vertical  slip  of  the  crucial. 

Posterior  common  ligament  of  spine. 

Anterior  common  ligament  of  sjjine. 


The  til)rous  bag  of  the  })harvnx 

Blood-supply. — The  occipital  bone  receives  branches  from  the  occipital,  pos- 
terior auiicular,  middle  meningeal,  vertebral  and  ascending  pharyngeal  arteries. 

Development. — The  interparietal  portion  of  the  occipital  is  a  menil)rane-bone, 
and  arises  usually  by  two  and  occasionally  by  four  centres  about  the  twelfth  week; 
these  nuclei  rapidh^  become  confluent  and  fuse  with  the  supra-occi{)ital  portion 
about  the  fifteenth  Aveek.  Occasionally  this  fusion  fails.  The  centres  for  the  rest 
of  the  bone  are  dt'i)osited  in  cartilage.     The  nucleus  for  the  basi-occii)ital  appears 


Fig.  35. — The  Occii-rrAL  with  a  Separate  Interparietal. 


INTER  PA  RliETAL. 


r 


W'     '     SUPRAQCCIPiTAL 


in  the  tenth  week,  and  is  quickly  followed  by  a  nucleus  for  each  ex-occipital;  the 
su|)ra-occipital  ossifies  from  two  laterally  disposed  nuclei,  Avhich  <juickly  coalesce 
and  fuse  with  the  interparietal  portion  near  the  situation  of  the  future  occi})ital 
protuberance.  For  many  weeks  two  deep  lateral  fissures  separate  the  interparietal 
and  supra-occipital  portions,  and  a  membranous  space,  extending  from  the  centre 
of  the  squamo-occipital  to  the  foramen  magnum,  partially  separates  the  lateral 
portions  of  the  supra-occipital.  This  space  becomes  occupied  by  a  sjMcule  of  bone, 
and  is  of  interest,  because  through  it  hernia  of  the  brain  and  its  membranes,  known 
as  occii)ital  meningocele  or  encephalocele,  occurs. 

At  birth  the  occipital  consists  of  four  parts:  the  squamo-occipital.  tAvo  ex-occip- 
itals,  and  the  l)asi-occipital,  united  V)v  strips  of  cartilage.  The  ex-occipitals  and 
scjuamo-occipital  fuse  together  about  the  fifth  year,  and  unite  with  the  basi-occi}>ital 
before  the  seventh  year.  The  posterior  tAvo-thirds  of  each  occipital  condyle  belongs 
to  the  ex-occipitals,  and  the  anterior  third  to  the  basi-occipital  (fig.  33). 

Not  infrequently  the  interparietal  portion  remains  separate  throughout  life,  and 
may  even  be  represented  by  numerous  detached  ossicles  or  Wormian  l)ones.  By 
the  tAventy-fifth  year  the  basi-occii)ital  is  firmly  ankylosed  to  the  si)henoid. 


THE  SPHENOID 

The  sphenoid  forms  a  large  part  of  the  base  of  the  skull  in  the  region  of  the 
anterior  and  middle  fossae.  It  is  very  irregular  in  shape,  and  is  best  descrilied  as 
consisting  of  a  l)ody,  two  pairs  of  wings,  and  two  ])airs  of  processes. 


80 


THE  SKELETON 


The  body  is  irrogulavly  cuboiJal  in  sliai)e.  Tlu'  superior  surface  presents  the 
following  points  for  exanhnation.  In  front,  there  is  a  prominent  si»ine,  which 
is  received  ))etween  the  diverging  ala?  of  the  crista  galli,  and  is  known  as  the 
ethmoidal  spine.  The  surface  behind  this  is  smooth,  and  is  formed  l)y  extensions 
of  the  lesser  or  orliital  wings;  it  frequently  ]iresents  two  parallel  longitudinal 
grooves  for  the  olfactory  bull)S.  This  smootli  surface  is  terminated  l)y  a  ridge,  the 
fimbus,  behind  which  'is  the  optic  groove  lodging  the  optic  chiasma,  and  leads  on 
each  side  into  the  optic  foramen.  The  groove  is  bounded  posteriorly  by  the 
olivary  eminence,  a  ridge  of  Inme  indicating  the  line  of  union  of  the  pre-  and 
post-sphenoid.  Behind  this  ridge  the  bone  i)resents  a  deep  hollow,  the  pituitary 
fossa,  in  which  the  pituitary  body  is  lodged.  The  floor  of  this  fossa  i)resents 
numerous  foramina  for  blood-vessels,  and  at  birth  the  superior  orifice  of  a  narrow 
passage  termed  the  cranio-pharyngeal  canal.  The  j^ituitary  fossa  presents  on 
each  side,  slightly  ]iosterior  to  the  olivary  eminence,  a  tubercle  of  variable  size,  the 
middle  clinoid  process.  This  is  occasionally  prolonged  to  meet  the  anterior 
clinoid  process  on  the  orbital  wing.  The  posterior  boundary  is  formed  by  a 
quadrilateral  plate  of  bone,  the  dorsum  ephippii.  The  superior  angles  of  this 
plate  are  surmounted  by  the  posterior  clinoid  processes,  which  give  attachment 
to  the  tentorium  cerebelli.  A  little  below  the  clinoid  process,  on  each  side  of  the 
dorsum  ephii)pii,   there  is  a   deep  notch,   converted  into  a  foramen  l)y  the  dura 


Fig.  30. — The  Sphenoid.     (Tiewed  from  above. 


OPTIC  FORAMEN 
SPHENOIDAL  FISSURE 

FORAMEN  ROTUNDUM 


FORAMEN  OVALE 
FORAMEN  SPINOSUM 


SPINE  OF  THE  SPHENOID 
EXTERNAL  PTERYGOID  PLATE 

INTERNAL  PTERYGOID  PLATE 

PTERYGOID  NOTCH 

HAMULAR  PROCESS 


mater,  for  the  passage  of  the  sixth  cranial  nerve.  The  dorsum  is  slightly  concave 
posteriorly,  and  supports  the  basilar  artery  and  the  pons. 

The  inferior  surface  of  the  body  has  a  prominent  median  ridge,  the  rostrum, 
which  is  received  l)et\veen  the  alffi  of  the  vomer.  The  rest  of  the  surface  is  rough, 
and  covered  l)y  the  mucous  memljrane  belonging  to  the  roof  of  the  pharynx. 

The  anterior  surface  presents  in  the  middle  line  a  vertical  ridge  of  bone,  the 
sphenoidal  crest,  which  articulates  with  the  peri)endicular  plate  of  the  ethmoid. 
On  each  side  of  tlie  crest  is  a  groove  which  forms  part  of  the  roof  of  the  nose;  it  is 
bounded  externally  by  a  more  or  less  circular  orifice  which  leads  into  the  sphe- 
noidal sinuses.  Still  more  externally  is  a  rough  area  for  articulation  with  the 
lateral  mass  of  the  ethmoid.  These  sinuses  are  irregularly  shaped,  unsymmetrical 
cavities,  separated  from  one  another  by  a  thin  vertical  se]itum;  in  adult  Iwnes  they 
may  extend  into  the  roots  of  the  pterygoid  processes,  and  even  into  the  base  of  the 
occipital  bone.  The  sinuses  communicate  with  the  nasal  fossa  of  their  respective 
sides.  The  lateral  margins  of  the  antei'ior  surface  are  serrated  for  articulation  with 
the  posterior  border  of  the  os  planum  on  each  side  of  the  ethmoid.  The  su[)erior 
mai'gin  articulates  with  the  cribriform  plate  of  the  ethmoid. 

The  posterior  surface  or  basi-sphcnoid  is,  in  the  adult,  ankylosed  to  the  basi- 
occij)ital.  The  two  bones  are  separated  by  a  disc  of  hyaline  cartilage  until  the 
eighteenth  year;  by  the  twenty-fifth  year  ankylosis  is  complete. 

Tlie  lateral  surface  enters  into  the  formation  of  the  jjosterior  part  of  the  inner 


THE  SPHENOID 


31 


wall  of  the  or])it;  it  forms  the  inniT  l)oundary  of  the  sphenoidal  fissure,  and  more 
posteriorly  is  grooved  for  the  internal  earotid  artery  and  eavernous  sinus. 

Tlie  process  of  hone  over  wliieh  this  artery  turns  is  the  lingula ;  it  constitutes  a 
flying  Inittress  for  the  su)»p()rt  of  the  greater  wings. 

The  lesser  or  orbital  wings  (()rl)ito-sphenoids)  are  thin,  triangular,  horizontal 
plates  of  ])on(?  resting  U})on  that  portion  of  the  sphenoid  anterior  to  the  olivary 
ridge  (pre-sphenoid).     The  superior  surface  of  each  wing  is  smooth  and  slightly 


Fig.  37. — The  Llit  II.\lk  of  thk  Sphenoid. 


ANTERIOR  CLINOID  PROCESS 

MIDDLE  CLINOID  PROCESS 

POSTERIOR  CLINOID  PROCESS 


ETHMOIDAL  SPINE 

THE  LIMBUS 
OPTIC  GROOVE 
OLIVARY  EMINENCE 

DORSUM  EPHIPPII 

FOR  OCCIPIfAU 


concave,  and  forms  the  posterior  part  of  the  anterior  fossa  of  the  skull;  the  under 
surfaces  constitute  a  portion  of  the  roof  of  each  orbit,  and  l)0und  superiorly  the 
sphenoidal  fissures.  The  anterior  })order  is  serrated  for  articulation  with  the 
horizontal  plate  of  the  frontal  bone.  The  posterior  border,  smooth  and  rounded, 
is  received  into  the  Sylvian  fissure  of  the  cerebrum.  The  inner  extremity  is  i)ro- 
longcd  to  form  the  anterior  clinoid  process  to  which  the  tentorium  cerebelh  is 
attached.      Each  lesser  wing  is  connected  to  the  body  of  the  bone  by  two  processes 


Fig.  38. — The  Sphenoid.     (Anterior  view 


OPTIC  FORAMEN 


SPHENOIDAL  FISSURE 


ORBITAL     SURFACE    (THE 
POINTER   CROSSES  THE      "C 
MALAR  CREST) 


cXT.  PTERYGOID  PUTE 


FORAMEN  ROTUNOUM 


PTERYGOID  NOTCH 
HAMUUR  PROCESS 


PTERYGO-PALATINE  CANAL 


or  roots;  of  these,  the  upper  is  thin  and  fiat,  the  lower  one  is  thicki^r,  and  ])resents 
near  its  junction  with  the  body  a  small  tubercle  for  the  attachment  of  the  common 
tendon  of  three  ocular  muscles.  The  opening  between  the  roots  is  tlie  optic 
foramen,  and  transmits  the  optic  nerve  and  o})hthalmic  artery. 

The  greater  wings  ( ;ili-si)henoids)  are  two  large  plat(\s  of  l)one  ankylosed  to  the 
l^'xly  by  means  of  the  lingulae.  Each  wing  has  three  surfaces.  The  superior  or 
cerebral  surface  is  concave  and  smooth;  it  supports  tlie  teinporo-spheiioidal  lobe 
of  the  ceriliium,  and  presents  several  foramina.    At  the  anterior  and  internal  part  is 


32  THE  SKELETON 

till-  foramen  rotundum  for  the  second  division  of  the  fifth  nerve;  behind  and 
external  to  thi^  i:?  the  foramen  ovale,  for  the  motor  root  and  the  third  divi.sion  of 
the  fifth  nerve,  tlie  small  ju'trosal  nerve,  the  small  meningeal  artery,  and  an  emis- 
sary vein  from  the  caverndus  sinus.  Behind  and  external  to  the  foramen  ovale  is 
the  small  eireular  foramen  spinosum,  for  the  middle  meningeal  artery,  its  venae 
comites,  and  the  recurrent  branch  of  the  third  division  of  the  fifth  nerve.  To  the 
inner  side  of  the  foramen  ovale  a  small  opening,  the  foramen  Vesalii,  is  occasion- 
ally present;  it  transmits  a  vein.  A  foramen  may  exist  near  the  foramen  ovale  for 
tlie  small  superficial  petrosal  nerve,  the  canaliculus  innominatus.  The  external 
surface  is  divided  by  the  prominent  malar  crest  into  an  orbital  and  a  temporo- 
zygomatic portion.  The  orbital  surface  forms  the  chief  part  of  the  outer  wall 
of  the  orbit;  its  internal  segment  forms  part  of  the  spheno-maxillary  fossa,  and 
})resents  the  anterior  orifice  of  the  foramen  rotundum.  Near  the  middle  of  the 
upper  border  there  is  a  small  tubercle  for  the  origin  of  the  outer  head  of  the  external 
rectus  muscle;  and  at  the  highest  part  of  this  surface  one  or  more  foramina  are  often 
present,  for  the  transmission  of  twigs  from  the  middle  meningeal  artery  to  the  orbit 
and  the  lachrymal  gland.  The  malar  crest  is  serrated  for  articulation  with  the 
malar  bone;  its  lower  angle,  in  many  bones,  articulates  with  the  maxilla.  A 
foramen  exists  in  the  suture  between  the  sphenoid  and  malar,  for  the  temporal  twig 
of  tlie  orbital  nerve.     The  surface  of  bone  outside  this  ridge  is  subdivided  by  a  low 

Fig.  39. — Kight  Half  of  Sphenoid.     (Anterior  view.) 


Ext.  Pterygoid  Muscle 


THE  ALAR  SPINE 


TEMPORAL  SURFACE 


SPHENOIDAL  CREST 

RIDGE   WHICH    FORMS    THE    UPPER  '"HKs  A'i'iMii'.^SfMt' —  SPHENOIDAL  SINUS 

BOUNDARY  OF  THE  SPHENO-MAX- 
ILLARY FISSURE 


crest,  the  pterygoid  ridge.  The  surface  above  the  ridge  forms  part  of  the  temporal 
fossa,  and  affords  attachment  to  the  temporal  muscle;  the  part  below  the  crest  be- 
Vmgs  to  the  zygomatic  fossa;  it  furnishes  attachment  to  the  external  pterygoid  muscle, 
and  is  continuous  with  the  outer  surface  of  the  external  pterygoid  plate;  it  contains 
the  inferior  orifices  of  the  foramina  spinosum,  ovale,  and  Vesalii,  and  forms  part  of 
the  roof  of  the  zygomatic  fossa. 

The  circumference  of  the  great  wing,  commencing  at  its  anterior  attachment  to 
the  body,  is  at  first  smooth,  and  forms  the  lower  boundary  of  the  sphenoidal 
fissure  ;  this  serves  for  the  passage  of  the  third,  fourth,  first  division  (ophthalmic) 
of  the  fifth,  and  the  sixth  nerves,  with  the  ophthalmic  vein.  External  to  this,  the 
margin  is  broad  and  serrated  for  the  frontal  bone;  quite  at  the  tip  it  is  bevelled  on 
its  inner  aspect  for  the  anterior  inferior  angle  of  the  parietal;  behind  this,  the  edge, 
at  first  thin  and  bevelled,  becomes  gradually  broader,  and  deeply  serrated  for  the 
squamosal,  and  runs  into  the  prominent  alar  spine  of  the  sphenoid,  to  which 
the  si)heno-mandil)ular  ligament  is  attached  and  which  is  grooved  internally  by 
the  chorda  tympani  nerve.  That  portion  of  the  circumference  extending  from  the 
spine  to  the  body  of  the  sphenoid  articulates  by  the  outer  third  with  the  petrosal, 
but  the  inner  two-thirds  forms  the  anterior  boundary  of  the  foramen  lacerum 
medium,  and  contains  the  posterior  orifice  of  the  Vidian  canal. 

Projecting  at  right  angles  from  the  greater  wing,  near  its  junction  with  the 
lingulse,  are  the  pterygoid  processes.     Of  these,  the  external  plate,  broad  and 


THE  SPHEXOrn 


33 


thin,  forms  by  its  outer  surface  tlie  iiuier  wall  of  the  zyjromatic  fossa,  tind  affords 
attaehuicut  to  the  external  pten/(/oid  nuiscle.  From  its  imu-r  surface  the  internfd 
pterj/goid  takes  origin. 

The  internal  pterygoid  plate  is  narrower  and  longer  than  the  external.  Its 
inner  surface  forms  part  of  the  outer  l)0undary  of  the  nasal  fossa,  and  l)y  a  thin 
li'dge  of  bone,  called  the  vaginal  process,  extends  to  the  under  surface  of  the  basi- 
sphenoid  to  articulate  with  the  ala  of  the  vomer,  and  anteriorly  with  the  sjilicnoidal 
process  of  the  palate  bone.  Inunediately  al»ove  this  ledge  of  Ixme  is  the  pterygo- 
palatine groove  (converted  into  a  canal  by  the  si)henoidal  j)roeess  of  the  palate 
bone),  for  an  artery  and  nerve  (»f  the  same  name.  At  the  point  where  the  internal 
pterygoid  plate  conies  into  relation  with  the  great  wing  and  the  lingula,  there  is  the 
Vidian  canal.  This  canal  is  3  cm.  long,  and  transmits  the  Vidian  nerve  and 
artery.  The  outer  surface  of  the  internal  pterygoid  plate  forms  the  inner  boundary 
of  the  pterygoid  fossa  ;  its  -posterior  border  is  prolonged  into  a  hamular  process, 
smooth  on  its  under  aspect,  for  the  bursa  between  it  and  the  tensor  (cireumflexus) 
palatl.  From  the  lower  third  of  the  posterior  border  and  the  hamular  process  the 
(<iij)erior  constrictor  of  tlie  ])harvnx  takes  origin. 

The  anterior  borders  of  these  processes  diverge  below,  and  have  rough  edges  for 
articulation  with  the  tul)erosity  of  the  palate  Ixme;  the  gap  between  them  is  the 
pterygoid  notch.  Superiorly,  the  pterygoid  ])rocesses  form  a  triangular  surface, 
which  constitutes  the  posterior  boundary  of  the  spheno-maxillarv  fossa,  and  presents 
above  the  anterior  orifice  of  the  Vidian,  and  more  internallv  the  commencement  of 


Fig.  40.— Thk  L'ndei:  Sikiwce  of  Pkk-Sphenoid  at  the  Sixth  Year. 


PTERYGO-PALATiNE  GROOVE 


OPTIC  FORAMEN 


ViD.AN   CANAL 
VAGINAL  PROCESS 


the  ]>terygo- palatine  canal.  The  anterior  border  of  the  internal  pterygoid  ]>late 
articulates  with  the  posterior  ])order  of  the  vertical  ])late  of  the  )»alate  bone. 

The  recess  between  thetwo  ])terygoid  ])lates  posteriorly  is  subdivided.  Theu]>i)er, 
smaller  and  shallower  depression  is  the  scaphoid  fossa;  it  gives  attachment  to 
the  tensor  (cireumflexus)  palatl  externally,  and  the  cartilage  of  the  Eustachian  tube 
internally.  The  lower,  deeper  and  larger,  is  the  pterygoid  fossa;  it  lodges  the 
internal  jttenjgoid  and  tensor  piditti  muscles.  The  fossa  is  comi)lete(l  l)y  the  tuber- 
osity of  the  ])alate  bone. 

Articulations. — The  sphenoid  articulates  with  the  following  Itones:  ethmoid, 
frontal.  i)arietal,  temporal,  epipteric,  palate,  vomer,  occipital,  malar,  sphenoidal 
turbinals,  and  occasionally  with  the  maxilla. 

Muscles. — It  gives  origin  to  the  following  nniscles: — 


Tem])oral. 
Internal  jttervgoid. 
External  pterygoid. 
Tensor  tympani. 
Tensor  palati. 


External  rectus  of  the  eyeball. 
Internal  rectus        ''  " 

Su))erior  rectus       "  " 

Superior  oblique    "  " 

Levator  palpebrte. 


Ligaments. — The  sphenoid  has  numerous  intrinsic  ligaments  which  occasion- 
ally ossify  and  produce  adventitious  foramina.  Of  these,  the  more  important 
are: — 

Inter-dinoid. — This  passes  fr<»iii  the  anterior  to  the  posterior  clinoid  processes. 
3 


34  THE  SKELETOX 

Crtror/c'ow7//(o/V/.— From  tin- anterior  to  the  iiiidille  clinoid  process.  The  ossifi- 
cation of  this  ligament  gives  rise  to  a  ring  of  l)one  through  which  the  internal 
carotid  arterv  passes. 

Pterygo-spiiious. — This  is  attached  to  the  spine  of  the  sphenoid  and  the  external 
ptervgoicl  plate  near  the  upper  third. 

Several  other  insigniticant  bands  have  received  names,  but  they  are  of  no  im- 
portance. 

Blood-supply. — Tlie  sjthenoid  is  supplied  l)y  branches  of  the  middle  and  small 
meningeal  arteries;  also  the  anterior  deep  ti'inporal  and  other  branches  of  the  in- 

FiG.  41.— The  Sphenoid  at  Bikth. 


VIDIAN   CANAL  LINGULA 


temal  maxillary,  such  as  the  Vidian,  pterygo-palatine  and  spheno-palatine.  The 
bodv  of  the  l^one  also  receives  t"v\dgs  from  the  internal  carotid. 

Ossification. — The  sphenoid  is  ossified  in  cartilage  from  twelve  ossific  nuclei 
which  appear  in  pairs.  The  nuclei  are  di\dsible  into  two  sets, — those  for  the  pre- 
sphenoid,  and  those  for  the  post-sphenoid. 

The  post-sphenoid  centres  consist  of  four  pairs  disposed  as  follows: — One  for 
each  ali-sphenoid  (great  wing).  A  pair  of  median  nuclei  for  the  basi-sphenoid, 
and  a  nucleus  for  each  lingula  (sphenotic  nucleus),  and  one  for  each  internal 
pterygoid.     The  external  i)terygoid  is  an  outgrowth  from  the  great  wing. 

The  pre-sphenoid  centres  consist  of  a  nucleus  for  each  orbito-sphenoid  (lesser 
wings),  and  a  median  pair  for  the  body  of  the  pre-sphenoid.     These  nuclei  ap})ear 


Fig.  4-2. — The  Jugum  Sphkxoiuale. 


at  intervals  from  the  eiglith  week  to  the  end  of  the  third  month  in  the  following 
order:  ali-sphenoid,  basi-sphenoid,  linguhe,  internal  pterygoids,  oritito-sphenoid, 
and  pre-sphenoid.  The  various  earthy  si)ots  fuse  together,  so  as  to  form  at  birtii 
three  pieces.  Tlic  median  piece  consists  of  the  basi-si)henoid  and  Hngulfe,  con- 
joined with  the  prt'-sphenoid  carrying  the  orljito-sphenoids;  the  two  lateral  pieces 
are  the  ali-sphenoids  (greater  wings)  carrying  the  internal  pterygoid  plates.  Tlie 
greater  wings  are  joined  to  the  lingula?  by  cartilage.  The  dorsum  ephij)pii  is  car- 
tilaginous at  birth.  In  tlie  course  of  the  first  year  the  orbito-si)henoids  fuse  in  the 
middle  line  to  form  the  jugum  sphenoidale,  which  excludes  the  anterior  part  of 
the  pre-sphenoid  from  the  cranial  cavity.  The  greater  wings  fuse  with  the  lingula? 
in  the  course  of  the  first  year. 


THE  TEMPORAL   BONES 


THE  TEMPORAL  BONES 


The  adult  temporal  bone  consist*;  of  three  })arts,  so  firmly  united  as  to  afford 
little  trace  of  its  complex  origin.  At  Inrth  the  three  parts  are  easily  separable  as 
the  squamosal,  petrosal,  and  tympanic. 

Tlu'  squamosal  resembles  a  large  scale;  it  is  attached  at  right  angles  to  thf 
petrosal,  and  furuis  part  of  the  side  wall  of  the  skull.  It  is  thin,  and  in  i)lact*s 
translucent.  The  outer  surface  is  smooth  and  forms  part  of  the  temporal  fossa;  it 
presents  one,  and  occasionally  two  nearly  vertical  grooves  for  the  deep  temporal 
arteries.  A  ridge  of  bone,  the  supra-mastoid  crest,  runs  immediately  above  the 
external  auditory  meatus,  and  is  continued  onwards  to  the  zygoma. 

The  zygoma  is  a  narrow  projecting  bar  of  bone,  jutting  forwards  and  lying 
parallel  witli  the  squamosal*  It  has  two  surfaces  and  two  borflers.  The  outer 
surface  is  subcutaneous;  the  inner  looks  towards  the  temporal  fossa.  The  inner 
surface  and  lower  border  give  origin  to  the  masseter  muscle.  The  upper  border 
receives  the  temporal  fascia.  The  tip  of  the  zygoma  is  serrated  for  articulation 
with  the  malar.  Posteriorly,  tlie  lower  border  ends  in  a  tubercle,  which  is  the 
meeting  point  of  two  ridges;  of  these,  the  anterior  passes  inwards  at  right  angles 
to  the  zygoma,  and  expands   into  the   articular   eminence   which  serves  as  an 


Fi(i.  4;i.— Thk  Left  Temporal  Bone.     lOuter  view.) 


ZYGOMATIC  TUBERCLE 

GLENOID  FOSSA 

GLASERIAN  FISSURE 

TYMPANIC  PLATE 

STYLOID  PROCESS 


TEMPORAL  FOSSA 
POST-GLENOiO  TUBERCLE 
AUDITORY   MEATUS 

AURICULAR  FISSURE 


articular  facet  for  the  condyle  of  the  mandilile  when  the  mouth  is  opened.  The 
second  ridge  runs  1)ackwards  and  forms  the  upper  boundary  of  the  glenoid  fossa, 
and  curving  downwards  ends  in  a  tubercle,  the  post-glenoid  tubercle,  immediatt4y 
anterior  to  tlie  Glaserian  fissure.  The  oval  dee}j  depression  between  these  ridges 
is  the  glenoid  fossa,  which  receives  the  condyle  of  the  mandible.  This  fossa  is 
limited  posteriorly  l»y  the  Glaserian  fissure. 

The  inner  surface  of  the  squamosal  presents  furrows  for  the  convolutions  of 
the  l»rain  and  grooves  for  the  middle  meningeal  arteries.  The  line  of  union  between 
the  squamosal  and  petrosal  is  sometimes  indicated  ])ya  persistent  petro-squamosal 
suture.      Rarely  the  two  portions  remain  permanently  separate. 

The  superior  Ixmler  of  the  squamosal  is  thin,  and  bevelled  on  the  cerel)ral 
surface  where  it  overlaps  the  parietal;  anteriorly  it  is  serrate(l  for  the  ))osterior 
border  of  the  greater  wing  of  the  sphenoid.  Posteriorly  it  joins  the  rough  serrated 
margin  of  the  petrosal  to  form  the  i)arietal  notch. 

The  petrosal  element  is  a  four-sided  pyramid  of  very  dense  bone;  its  base  is 
formed  Ijy  the  mastoid  process;  the  apex  is  rough  and  forms  part  of  the  boundary 
of  the  foramen  lacerum  medium.  Two  sides  of  the  pyramid  j^roject  into  the  cranial 
cavity,  of  which  one  fonns  the  j)Osterior  boundary  of  the  middle  fossa,  and  the 
other  the  anterior  boundary  of  the  ])Osterior  fossa  of  the  cranium.  Of  the  two 
remaining  surfaces,  one  a])pears  on  the  under  surface  iif  the  skull,  and  the  fourth 
constitutes  the  inner  wall  of  the  recess  called  the  tynqianum. 


36 


THE  SKELETON 


Tlie  posterior  surface  is  l)ounded  above  by  the  superior  border,  Avhicb  serves 
for  the  attaehnient  oi  the  tentorium  cerebelh,  and  is  grooved  lor  the  su})erior  petrosal 
sinus;  near  the  apex,  this  border  presents  the  trigeminal  notch  (eonverted  into 
a  foramen  by  the  tentorium)  for  the  transmission  of  the  trigeminal  nerve.  This 
border  in  old  skulls  sometimes  terminates  in  a  spiculum  of  bone — the  petro-sphe- 
noidal  process — and  extends  to  the  dorsum  ephippii,  and  eompletes  a  foramen 
(petro-sphenoidal)  whieh  transmits  the  sixth  nerve.  Near  the  middle  of  the 
posterior  surfaec  is  an  oblique  inlet,  the  internal  auditory  meatus,  which  receives 


Fig,  44.— The  Left  Temporal  Bone.     (luner  view.) 


FOR  MIDDLE   MENINGEAL  ARTERY  f" 


LATERAL  SINUS 

THE  GROOVE  FOR  SUPERIOR 

PETROSAL  SINUS                 feg;,     '■g— 
MASTOID  FORAMEN  — ^^,    V 
AQUEOUCTUS  VESTIBULI  ^        — ^ 


AQUEDUCTUS  COCHLE/f 


PETROSAL 


REMNANT  OF  FLOCCULAR  FOSSA 
INTERNAL  AUDITORY   MEATUS 


FOR  OCCIPITAL 


the  auditory  and  facial  nerves  and  the  auditory  artery.  The  meatus  is  altout  10 
mm.  deep,  and  to  be  properly  examined  the  surface  of  the  bone  should  be  cut 
away,  or  the  parts  studied  in  the  petrosal  of  a  foetus  at  or  near  the  ninth  month, 
for  it  is  at  this  date  relatively  large  and  shallow. 

The  fundus  of  the  meatus  is  divided  by  a  transverse  ridge  of  bone,  the  f ale  if  or  yn  crest,  into  a 
superior  and  inferior  fossa.  Of  these,  the  superior  is  the  smaller,  and  presents  anteriorly  the 
beginning  of  the  aqueduct  of  Fallopius  ;  this  transmits  the  seventh  nerve.  The  rest  of  the  sur- 
face above  the  crest  is  dotted  with  small  foramina  (the  superior  cribriform  area)  which  transmit 
nerve-twigs  to  the  fovea  hemielliptica  and  the  ampullae  of  the  superior  and  external  semicircular 
canals.     Below  the  crest  there  are  two  depressions  and  an  opening.     Of  these,  an  anterior  cuiled 


Fig.  45.— The  Foramina  in  the  Fundus  of  the  Left  Internal  Auditory  Meatus  of  a 
Child  at  Birth  (y).     (Diagrammatic.) 

SUPERIOR  FOSSA 


SUPERIOR  CRIBRIFORM  AREA 


MIDDLE  CRIBRIFORM  AREA 
FORAMEN  SINGULARE 


ENTRANCE  TO  THE  AQUEDUCT  OF  FALLOPIUS 


FALCIFORM  CREST 

'^         S^rff^ ORIFIC 

•aitr. 

SPIRAL  CRIBRIFORM  TRACT 


■|CE  OF  THE  CANAL  OF  THE   MODIOLUS 


tract  (the  spiral  crihrifurm  tract)  with  a  central  foramen  (foramen  centrale  codilearc)  marks 
the  base  of  the  (•(tchlea  ;  the  central  foramen  indicates  the  orifice  of  the,  canal  of  the  modio- 
lus, and  the  smaller  foramina  transmit  the  cochlear  twigs  of  the  auditory  nerve.  The  pos- 
terior opening  (loranien  singulare)  is  fur  the  nerve  to  the  ami)ulla  of  the  jiosterior  semicircular 
canal.  The  middle  depression  (middle  cribriform  area)  is  dotted  with  minute  foramina  for  the 
nerve-twigs  to  the  saccule,  which  is  lodged  in  the  fovea  hemisjiherica.  The  inferior  fossa  is  sub- 
divided l»y  a  low  vertical  crest.  The  fossa  in  front  of  the  crest  is  the  fosfntla  cochlenris,  and  the 
recess  behind  it  is  the  fossitla  vcstihiilaris. 


Behind  the  meatus  is  a  small  slit  (aqueductus  vestibuli)  which  lodges  the 
ductus  endolymphaticus;  in  the  adult  it  is  occupied  by  a  small  arteriole  and  venule 


THE  TEMPORAL   BOXES  37 

and  a  })roc('SS  of  dura  niatcT.  Occasionally  a  l»ri.stle  can  1)0  passed  along  this  pas- 
sage into  the  vestibule.  Above,  and  anterior  to  this,  is  a  second  slit  also  lodging  a 
process  of  the  dura  mater.  This  is  a  remnant  of  the  floccular  fossa,  so  conspicu- 
ous in  the  f<ptus.      Posteriorly,  this  surface  has  a  deep  groove  for  the  lateral  sinus. 

The  anterior  face  of  the  pyramid  is  sci)arated  from  the  squamosal  by  the 
petro-squamous  suture,  wliicli  may  })ersist  throughout  life.  It  presents  the 
following  points  of  interest:  near  the  apex  it  has  a  shallow  dei)ression  for  the  Gas- 
serian  ganglion,  and  the  recess  of  dura  mater  (Meckel's  cave)  in  Avhich  it  lies. 
Behind  these  are  two  small  foramina,  overshadowed  by  a  thin  osseous  lip.  Of  these, 
the  larger  and  more  internal  is  the  hiatus  Fallopii,  wliich  transmits  a  small  artery 
from  the  middle  meningeal  and  the  greater  petrosal  nerve.  The  smaller  and  exter- 
nal foramen  is  for  the  lesser  petrosal  nerve.  Still  more  externally  there  is  a  thin 
translucent  plate  of  bone,  the  tegmen  tympani.  Behind,  and  slightlv  internal  to 
this,  there  is  a  ridge  formed  l)y  the  superior  semicircular  canal. 

The  inferior  or  basilar  surface  is  very  irregular,  and  has  the  following  points 
of  interest.  At  the  apex  is  a  quadrilateral  smooth  space  for  the  tensor  ti/mjimii  and 
levator  palnti  muscles.  Behind  this  is  the  large  circular  orifice  of  the  carotid  canal, 
for  the  transmission  of  the  carotid  artery  and  a  plexus  of  sympathetic  nerves. 
Internal  to  this,  near  the  inner  border  of  the  bone,  is  the  orifice  of  the  aqueductus 
cochleae  nluetus  perilymphaticus).     In  the  adult  it  transmits  a  small  vein  from 


Fig.    Ui. — Tin-;   Lkit  Tk.mpok.vl  Boxk.     (Inferior  view.) 

CAROTID  CANAL  ■ 


SURFACE  FOR  SPHENOID 

Tensor  tympani  and 

levator  palati 

TYMPANIC  CANALICULUS 

AQUEDUCTUS  COCHLE/t 
AURICULAR  CANALICULUS         .  .  .^^ 

JUGULAR  FOSSA ^I^^:  j) 

JUGUUR  SURFACE 
STYLO-MASTOID  FORAMEN 


ARTICUUTION  FOR  OCCIPITAL 


OCCIPITAL  GROOVE 


ARTICULAR  EMINENCE 


ZYGOMATIC  TUBERCLE 
GLASERIAN   FISSURE 
STYLOID   PROCESS 
EXTERNAL  AUDITORY  MEATUS 
AURICULAR  FISSURE 


MASTOID  PROCESS 
DIGASTRIC  GROOVE 


the  cochlea  to  the  internal  jugular.  Posteriorly  is  the  elli])tical  jugular  fossa  with 
smooth  walls  for  the  ampulla  which  receives  the  lateral  and  inferior  ixtrosal  sinuses. 
and  forms  the  commencement  of  the  internal  jugular  vein.  In  the  ridge  of  bone 
between  the  fossa  and  the  carotid  canal  there  is  a  small  foramen,  the  tympanic 
canaliculus,  for  the  tympanic  branch  of  the  glosso-jjliaryngcal  nerve.  On  the 
outer  wall  of  the  fossa  a  similar  minute  foramen,  the  auricular  canaliculus,  ])er- 
mits  the  jtassage  inwards  of  the  auricular  branch  (Arnold's  nen-e)  of  the  vagus 
nerve.  Bcidnd  the  fossa  is  the  rough  jugular  surface,  which  receives  the  jugular 
process  of  the  occipital.  Firmly  ankylosed  to  the  inner  surface  of  the  tympanic 
plate  is  the  styloid  process,  varying  in  length  from  one  to  five  cm.  At  its  base 
is  the  stylo-mastoid  foramen,  from  which  Lssues  the  facial  ner\'e;  the  stylo- 
mastoid artery  enters  the  Fallopian  canal  through  this  opening.  Running  back- 
wards from  this  foramen  are  two  grooves;  the  outer  is  the  digastric  groove, 
from  which  the  digastric  muscle  arises.  The  inner  is  narrower  and  shallower: 
it  lodges  the  occipital  artery. 

Of  the  outer  surface,  the  only  part  which  appears  externally  is  the  mastoiil 
process;  the  rest  is  occupied  by  a  recess  known  as  the  tympanum.  The  mastoid 
process  is  a  nij)] de-shaped  prominem-e  of  bone.  fornie<i  jiartly  by  the  sipiamosal, 
l)Ut  mainly  by  the  petrosal.  Its  ujjjjcr  limit  is  the  supra-mastoid  crest.  Below 
the  crest  an  irregular  furrow  crosses  the  surface  of  the   process   from   the   jxirietal 


38 


rilK  SKELETOX 


notch  downwards,  to  the  middle  of  the  meatus.  Tliis  furrow  (squamo-mastoid)  is 
often  dott(Ml  witli  holes,  and  represents  the  line  of  union  of  squamosal  and  petrosal. 
The  mastoid  }»rt)eess  <rives  attaehment  to  the  sterno-maMoid,  .splenius  capitis,  trachelo- 
iiia-'<t<ii(L  occlpito-froiitdlis.  and  retvdhens  aurem  muscles. 

The  tympanum  is  hidden  hy  the  tympanic  pl<tt(\  which  extends  downwards 
from  the  Glaserian  fissure  to  form  the  vaginal  process.  Anteriorly  it  extends 
forwards  and  ankyloses  with  the  outer  wall  of  the  carotid  canal.  The  Glaserian 
fissure  separates  it  from  the  squamosal.  This  fissure  transmits  the  tympanic 
branch  of  the  internal  maxillary  artery,  and  lodges  the  slender  process  of  the 
malleus.  A  narrow  subdivision  of  this  fissure,  canal  of  Huguier,  is  traversed  1)y 
the  chorda  tympani  nerve.  The  tympanic  i)late  forms  the  anterior,  lower,  and 
part  of  the  posterior  walls  of  the  external  auditory  meatus.  It  is  limited  poster- 
iorlv  by  tlie  auricular  lissure,  through  which  the  auricular  twig  of  the  vagus  nerve 


issues. 


The  external  auditory  meatus  assumes  the  form  of  an  elliptical  bony  tube. 
Its  outer  margin  is  rough  and  gives  attachment  to  the  cartilaginous  portion  of  the 
pinna.  Between  the  posterior  edge  of  the  meatus  and  the  mastoid  process  is  the 
auricular  fissure.     The  tympanic  orifice  of  the  meatus  is  smooth,  and  presents  a 


Fio.  47.— Temporal  Bone  with  Muscle  Attachments. 


TYMPANIC  PLATE 


Stylo-glossus  Stylo-pharyngeu8 

Stylo-hyoid 


Retrahens  aurem 
Oceipito-fron  talis 

Sterno-inastoid 

Trachelo-mastoid 
Splenius  capitis 


well-marked  groove  for  the  tympanic  membrane.  This  is  very  conspicuous  in 
young  bones.  The  direction  of  the  meatus  is  somewhat  oblique.  In  children,  and 
occasionally  in  adults,  a  circular  opening  exists  in  the  anterior  wall  of  the  meatus 
(Hg.  r,.S). 

Articulations. — The  temporal  bone  articulates  Avith  the  occipital,  parietal, 
sphenoid,  malar,  and  by  a  movalde  joint  with  the  mandi1)l(\  Occasionally  the 
sfjuamosal  presents  a  process  which  articulates  with  the  frontal.  A  fronto- 
squamosal  suture  is  common  in  the  skulls  of  the  lower  races  of  nu'n,  and  is 
normal  in  the  skulls  of  the  chimpanzee,  gorilla,  and  gibbon. 

The  muscles  connected  with  the  temj)oral  bone  are: — 


To  the  mastoid  process 


Stemo-mnstoid. 
Splenius  capitis. 
Trachelo-mastoid. 
Digastric. 
Occipito-frontalis. 
Retrahens  aurem. 


THE  rYMPAXVM  39 

{  Stylo-glossus. 
To  thf  styloid  })rocess \  Stylo-hyoid. 

^  Stylo-piiaryngeus. 
To  the  zygoma Masseter. 

Intrinsic  muscles .|  «^<^P^^i"^- 

I  lensor  tym])am. 

To  tlie  petrosal Levator  palati. 

Ligaments  : — 

Capsular  1  Stylo-hyoid. 

Interaiticular       I  of  temporo-mandi-  Stylo-maxillary. 

Internal  lateral    |         bular  joint.  Petro-sphenoidal. 

External  lateral  J 

Ligaments  connected  with  the  ear-bones  : — 

Anterior  ligament  of  malleus. 
External  ligament  of  malleus. 
Superior  ligament  of  malleus. 
Ligament  <jf  incus. 

The  blood-supply. — Arteries  supplying  the  temporal  bone  are  derived  from 
various  sources.     The  chief  are: — 

Stylo-mastoid  from  posterior  auricular:  it  enters  the  stylo-mast oid  foramen. 

Tympanic  from  internal  maxillary:  it  passes  through  the  Glaserian  fissure. 

Petrosal  from  middle  meningeal:  transmitted  by  the  hiatus  Fallopii. 

Tympanic  from  internal  carotid  whilst  in  the  carotid  canal. 

Auditory  from  the  basilar:  it  enters  the  internal  auditory  meatus,  and  is  distri- 
buted to  the  cochlea  and  vestibule. 

Other  less  important  twigs  are  furnished  by  the  middle  meningeal,  the  men- 
ingeal branches  of  the  occipital,  and  by  the  ascending  pharyngeal  artery.  The 
s(|uamosal  is  supplied  on  its  internal  surface  by  the  middle  meningeal,  and  ex- 
ternally l)y  the  branches  of  the  deep  temporal  from  the  internal  maxillar}'. 

Note. — The  description  of  the  Stvloid  Proces.s  and  of  the  J]ar-bones  is  given  on  pages 
ri6-68. 

THE  TYMPANUM 

The  tympanum  is  an  irregular  cavity  in  the  temporal  bone.  At  birth  it  is  a 
recess  in  the  outer  wall  of  the  petrosal,  partially  closed  externally  by  the  scjuamosal. 
When  the  various  elements  of  the  temporal  bone  coalesce,  and  the  tympanic  plate 
l>ecomes  fully  developed,  then  the  cavity  is  completely  surrounded  by  bony  walls, 
except  where  it  communicates  with  the  external  auditory  meatus. 

The  roof,  or  legmen  tympani,  is  a  translucent  plate  of  bone  belonging  to  the 
petrosal;  it  separates  the  tympanum  from  the  middle  fossa  of  the  skull.  The  iloor 
is  the  plate  of  bone  which  forms  the  roof  of  the  jugular  fossa. 

The  inner  wall  is  formed  by  the  external  surface  of  the  petrosal  bone,  and  pre- 
sents the  following  points  for  study: — In  the  angle  between  it  and  the  roof  is  a 
liorizontal  ridge  which  extends  l)ackwards  as  far  as  the  posterior  wall,  and  then 
turns  downwards  in  the  angle  ])etween  the  inner  and  posterior  walls.  This  is  the 
Fallopian  canal;  it  is  occupied  by  the  facial  nerve  (seventh).  Near  the  roof,  but 
>»elow  the  Fallopian  canal,  is  the  fenestra  ovalis,  which  leads  into  the  vestibule: 
this  fenestra  receives  the  base  of  the  stapes.  Below  and  in  front  of  the  fenestra 
ovalis  is  the  promontory,  which  contains  the  commencement  of  the  first  turn  of 
the  cochlea.  In  the  lower  and  posterior  part  of  the  promontory  is  the  fenestra 
rotunda ;  this,  in  the  recent  state,  is  closed  by  the  secondary  membrane  of  the 
tympanum.  In  the  macerated  Ijone  it  leads  into  the  sjjiral  canal  of  the  coclilea. 
The  promontcjry  is  also  furrowed  by  some  delicate  channels  (sometimes  canals)  for 


40 


THE  SKELETOX 


tho  tvnipanic  bnincli  of  tin'  .<rloH;s<i-i)liaryngeal  nerve,  which  enters  the  tympanum 
through  the  tympanic  canaliculus.  The  posterior  wall  of  the  tymijanum  is 
formed  l)y  the  mastoid  jiroccss.  At  tlie  superior  and  external  angle  of  this  wall  an 
opening  leads  into  the  mastoid  antrum.  Immediately  l)elow  this  o])ening  there 
is  a  small  hollow  cone,  the  posterior  pyramid  ;  its  cavity  is  continuous  Avith  the 
descending  limh  of  the  Fallopian  ranal.  One  or  more  bony  spicule  often  connect 
the  apex  of  the  pyramid  with  the  promontory.  The  cavity  of  this  cone  is  occui)ied 
l)y  the  stapedius  and  the  tendon  of  the  muscle  emerges  at  the  apex. 

The  roof  and  floor  converge  towards  the  anterior  extremity  of  the  tympanum, 
which  is,  in  consequence,  very  narrow,  and  occupied  by  tAvo  canals:  the  loner  for 
the  Eustachian  tube,  the  upper  for  the  tensor  tympani  muscle.  These  grooves  are 
sometimes  described  together  as  the  canalis  musculo-tubarius.  In  carefully  pre- 
])ared  l)ones  the  upper  canal  is  a  small  horizontal  hollow  cone  (anterior  pyramid), 
12  nun.  in  length,  which  lodges  the  tensor  tympani  muscle;  the  apex  is  just  in  front 
of  the  fenestra  ovalis,  and  is  perforated  to  permit  the  passage  of  the  tendon  of  the 
muscle.  As  a  rule  the  thin  Avails  of  the  canal  are  damaged,  and  represented  merely 
l)y  a  thin  ridge  of  l:)one.  The  posterior  portion  of  this  ridge  projects  into  the  tym- 
l)anum,  and  is  knoAvn  as  the  processus  cochleariformis.  The  thin  septum 
betAveen  the  canal  for  the  tensor  tympani  and  the  tulje  is  pierced  by  a  narrow  canal 
Avhich  is  traversed  by  the  small  deep  petrosal  nerve.  The  outer  wall  is  occupied 
mainly  by  the  external  auditory  meatus.     This  opening  is  closed  in  the  recent  state 


Fig.  48. — The  Ixxer  Wall  of  Tymp.^xim. 


CAROTID  CANAL 

Tensor  Tympani 
GROOVE  FOR  EUSTACHIAN 
TUBE 
Levator  Palati 

CANAL  FOR  SMALL  DEEP 
PETROSAL  NERVE 


Stylo-pharyngeus 


Styli 


EXTERNAL  SEMICIRCULAR 

CANAL 
MASTOID  ANTRUM 

FALLOPIAN  CANAL 


ITER  CHORO/€  POSTERIUS 
STYLO-MASTOIO  FORAMEN 


l>y  the  tympanic  membrane  The  rim  of  l)one  to  wliich  tlie  membrane  is  attached  is 
incomplete  above;  the  defect  is  knoAvn  as  the  notch  of  Rivinus.  Anterior  to  this 
notrh.  in  the  angle  betAveen  theS(iuamosaland  the  tympanic  plate,  is  the  Glaserian 
fissure,  and  the  small  passage  Avhich  transmits  the  chorda  tympani  nerve  sometimes 
called  the  canal  of  Huguier. 

The  tympanic  cavity  may  l)e  divided  into  three  parts.  The  part  l)elow  the  Ica'cI 
of  the  superior  margin  of  the  external  auditory  meatus  is  the  tympanum  proper; 
the  portion  al)ove  this  level  is  the  attic  of  the  tympanum;  it  receives  the  head  of 
the  malleus,  the  body  of  the  incus,  and  leads  posteriori)^  into  a  recess  known  as  the 
mastoid  antrum. 

The  mastoid  antrum. — This  is  quite  distinct  from  the  mastoid  cells.  It  is  an 
air-chamber  comnumicating  Avith  the  attic  of  the  tynq^anum.  It  is  sei)arated  from 
the  middle  cranial  fossa  by  the  ]>osterior  portion  of  tlie  tegmen  tympani;  the  floor 
is  formed  by  tl>e  mastoid  portion  of  the  petrosal;  it  commiinicatcs  Avith  the 
mastoid  cells.  The  outer  Avail  is  formed  by  the  squamosal  beloAV  the  supra-mastoid 
crest.  In  cliildren,  the  outer  wall  is  exceedingly  thin.  l)ut  in  the  adult  it  is  of  con- 
siderable thickness.  The  external  semicircular  canal  projects  into  tlie  antrum 
on  its  inner  wall,  and  is  very  conspicuous  in  the  foetus. 


A  canal  occasionally  leads  from  the  ma.stoid  aiitram  throueh  the  petrous  bone  to  open  in  the 
recess  which  indicates  the  position  of  tho  floccular  fossa;  it  is  termed  the  petro-mastoid  canal. 
(<lruber.) 


THE  TYMPAM'M  41 

The  Fallopian  canal. — This  canal  begins  at  the  anterior  anjrle  of  the  .sujierior 
fossa  of  tile  internal  auditory  meatus,  and  passes  directly  outwards  to  the  hiatus 
Fallopii;  it  then  turns  abruptly  backwards  and  forms  a  horizontal  ridge  on  the 
inner  wall  of  the  tym})anum,  lying  in  the  angle  between  it  and  the  tegmen 
tynipani.  It  passes  immediately  above  the  fenestra  ovalis,  and  extends  as  far 
backwards  as  the  entrance  to  the  mastoid  antrum;  here  it  c(jmes  into  contact  with 
the  inferior  aspect  of  the  projection  formed  by  the  external  semicircular  canal.  It 
then  turns  vertically  downwards,  running  in  the  angle  between  the  internal  an<l 
posterior  walls  of  the  tym])anun)  to  terminate  at  the  stylo-mastoid  foramen. 

The' canal  is  traversed  by  the  facial  (seventh)  nerve.  Numerous  openings  exist 
in  the  walls  of  this  passage.  At  the  hiatus,  the  greater  and  smaller  superficial 
petrosal  nerves  escape  from,  and  a  l)ranch  from  the  middle  meningeal  artery  enters, 
the  canal.  In  the  vertical  part  of  its  course  the  cavity  of  the  posterior  pyramid 
opens  into  it.  There  is  also  a  small  orifice  l\v  "which  the  auricular  branch  of  the 
vagus  joins  the  facial,  and  near  its  termination  the  iter  chordae  posterius  for  the 
chorda  tympani  nerve  leads  from  it  into  the  tympanum. 

The  vestibule. — This  is  an  oval  chamber  situated  between  the  Itase  of  the 
internal  auditory  meatus  and  the  inner  wall  of  the  tympanuuK  with  which  it  com- 
numicates  by  way  of  the  fenestra  ovalis.  Anteriorly  the  vestil)ule  leads  into  the 
cochlea,  and  posteriorly  it  receives  the  extremities  of  the  semicircular  canals.  It 
measures  about  3  mm.  transversely,  and  is  somewhat  longer  antero-posteriorly. 

Its  inner  wall  presents  at  the  anterior  part  a  circular  depression,  the  fovea 
hemispherica,  Avhich  is  finely  perforated  for  the  passage  of  nerve-twigs.  This 
fovea  is  separated  by  a  vertical  ridge  (the  crista  vestibuli )  from  the  vestibular 

Fig.  49.— The  Left  Osseous  LABYnivxir.     (After  Heule.     From  a  cast. ) 

SUPERIOR  SEMICIRCULAR  CANAL 


EXTERNAL  SEMICIRCULAR  CANAL 

POSTERIOR  SEMICIRCULAR  CANAL 
FENESTRA  ROTUNDA  FENESTRA  OVALIS  OR  VESTIBULI 

orifice  of  the  aqueductus  vestibuli,  which  passes  obliquely  1)ackwards  to  open  on 
the  posterior  surface  of  the  petrosal  bone. 

The  roof  contains  an  oval  depression — the  fovea  hemielliptica.  Antei'iorly 
the  vestibule  leads  into  the  cochlea.  Posteriorly  it  receives  the  five  openings  of 
the  semicircular  canals. 

The  semicircular  canals  are  three  in  number.  Each  forms  al)OUt  two-thirds 
of  a  circle;  they  lie  in  different  planes.  One  extremity  of  each  canal  is  dilated  to 
form  an  ampulla. 

The  superior  canal  lies  transversely  to  the  long  axis  of  the  petrosal,  and  is 
nearly  vertical;  its  highest  liml)  makes  a  projection  on  the  anterior  surface  of  the 
bone.  The  ampulla  is  at  the  outer  end;  the  inner  end  opens  into  the  vestil)ule 
conjointly  witli  the  superior  limb  of  the  posterior  canal. 

The  posterior  canal  is  nearly  vertical  and  lies  antero-posteriorly.  It  is  the 
longest  of  the  three;  its  upper  extremity  joins  the  inner  limb  of  the  sujierior 
canal,  and  ojiens  in  common  with  it  into  the  vestibule.  The  lower  is  the  ampul- 
lated  end. 

The  external  canal  is  placed  horizontally  and  arches  outwards;  its  external 
limb  forms  a  prominence  in  the  mastoid  antrum.  This  canal  is  the  shortest;  its 
am])ulla  is  at  the  outer  end  near  the  fenestra  ovalis. 

The  cochlea. — This  is  a  cone-shaped  cavity  lying  with  its  base  upon  the  intenial 
audit(jry  meatus,  and  the  apex  directed  outwards.  It  measures  about  five  milli- 
metres in  length,  and  the  diameter  of  its  base  is  about  the  same.  The  centre  of  this 
cavity  is  occupied  by  a  column  of  Ixjne — the  modiolus — around  wliidi  a  delicate 
bony  lamella  appears  to  be  wound.     This  lamella  is  the  osseous  spiral  lamina, 


42  THE  SKELETOX 

wliicli  gives  attachment  to  the  structures  which  form  collectively  the  membranous 
cochlea.  Tlie  lamina  makes  two  and  a  half  turns  in  all.  The  first  turn  is  the 
largest,  and  forms  a,  liulging,  the  promontory,  on  the  inner  wall  of  the  tympanum. 
The  lamina  terminates  at  the  aj)ex  of  the  cochlea  in  a  hooklike  process — the 
hamulus. 

Tlie  modiolus  is  traversed  by  a  central  canal,  and  presents  many  canaliculi  for 
the  transmission  of  the  twigs  of  the  cochlear  division  of  the  auditory  nerve.  There 
is  also  a  canal  which  winds  round  the  modiolus  at  the  ])ase.  of  the  spiral  lamina, 
known  as  the  spiral  canal  of  the  modiolus. 

The  portion  of  tlie  cochlea  above  the  lamina  is  the  scala  vestibuli ;  the  part 
below,  that  is,  on  the  basal  aspect  of  the  lamina,  is  the  scala  tympani ;  it  opens 
into  the  tympanum  by  way  of  the  fenestra  rotunda.  Near  the  commencement  of 
th(>  scala  tympani,  and  close  to  the  fenestra  rotunda,  is  the  cochlear  orifice  of  the 
aqueductus  cochleae  (ductus  perilymphaticus).     In  the  adult  this  opens  on  the 

Fig.  50. — The  Cochlea  in  Saggital  Section.     (After  Henle.) 


INTERNAL  AUDITORY  MEATUS 


THE  SPIRAL  CANAL 


inferior  surface  of  the  petrosal  near  the  apex,  and  transmits  a  small  vein  from  the 
cochlea  to  the  jugular  fossa. 

Measurements  of  the  principal  parts  connected  with  tlie  auditory  organs: — 

Internal  auditory  meatus    ....  Length  of  anterior  Avail,  18-14  mm. 

"  posterior  wall,  6*7  mm. 

External  auditory  meatus       .    .    .  14-16  mm.      (Gruber.  ) 

Tympanum       Length,  13  mm. 

Height  in  centre  of  cavity,  15  mm. 
Width  opposite  the  membrana  tympani,  2  mm. 
"  "  tubal  orifice,  3-4  mm. 

(Von  Troltsch. ) 
The  capsule  of  the  osseous  labyrinth  is  in  length  22  mm.      (Schwalbe. ) 
Superior  semicircular  canal  measures  along  its  convexitv  20  mm. 
The  posterior  "  "  "  "  "       "   22  mm. 

The  external    ''  "  "  .  "  "  15  mm. 

The  canal  is  in  diameter  1*5  mm.      (Huschke. ) 
The  ampulla  of  the  canal,  2*5  mm. 

The   Ossification  of  The  Temporal  Bone 

At  ])iith  the  tcniporiil  bone  consists  of  three  parts  easily  separable  in  the  niaccrated  skull  : 
they  are  the  petrosal,  sqiiamosfd,  and  the  tympanic.  (The  styloid  process  is  cartilaginous  with 
the  exception  of  its  basal  element,  the  tynipano-hyal,  which,  with  the  ear-bones,  will  be  described 
with  the  appendicular  elements  of  the  cranium.) 

The  sijuaniosal  and  tympanic  bones  develop  in  membrane.  The  squamosal  is  formed  from 
one  centre,  which  appears  as  early  as  the  eiahth  week.  Ossification  extends  into  the  zygoma, 
which  grows  concurrently  with  the  squamosal.  At  first  the  tymjianlc  border  is  nearly  straight, 
but  soon  assumes  its  characteristic  horseshoe;  shape.  At  birth  the  post-glenoid  tubercle  is 
conspicuous,  and  at  the  hinder  end  of  the  squamosal  there  is  a  recess  where  it  comes  into  relation 
with  the  mastoid  antrum.  The  centre  appears  for  the  tympanic  bone  about  the  twelfth  week. 
At  birth  it  is  a  horseshoe-shaped  ossicle  slightly  aidcylosed  to  the  lower  border  of  the  squamosal, 
the  open  arms  being  directed  upwards.     The  tip  of  the  anterior  arm   terminates  in  a  small 


THE  TYMPANUM 


43 


irrcirular  process,  aud  the  inner  aspect  presents,  in  the  lower  half  of  its  circumference,  a  groove 
{or  the  reception  of  the  tympanic  membrane. 

Up  to  the  middle  of  the  fifth  month  the  jicriotic  capsule  is  cartihiirinous  ;  it  then  ossifies  so 
rapidly  that  by  the  end  of  the  sixth  month  its  chief  portion  is  converted  into  porous  bone.  The 
ossific  material  is  deposited  in  four  centres,  or  groups  of  centres,  named  according  to  their  relation 
to  the  ear-capsule  in  its  embryonic  position. 

The  nuclei  are  deposited  in  the  following  order  : — 

1.  The  opisthotic  appears  at  the  end  of  the  filth  month.  The  osseous  material  is  seen  first 
on  the  promontory,  and  it  quickly  surrounds  the  fenestra  rotunda  from  above  downwards,  and 
forms  the  floor  of  the  vestibule,  the  lower  part  of  the  fenestra  ovalis,  and  the  internal  auditory 


Fig.  51. — The  Temporal  Bone  at  Birtit.     (Outer  view.) 


POST-GLENOID  TUBERCLE 
GLASERIAN   FISSURE 


TYMPANIC  FISSURE   — 


SQUAMOSAL 


,»'.-  ^  ''     y  ~  ',-'/"    PETRO-SQUAMOUS  SUTURE 


STYLO-MASTOID  FORAMEN 
TYMPANO-HYAL 


-   CAROTID  CANAL 


meatus  ;  it  also  invests  the  cochlea.     Subsequently  a  plate  of  bone  arises  from  it  to  surround  the 
internal  carotid  artery  and  form  the  floor  of  the  tympanum. 

2.  The  pro-otic  nucleus  is  deposited  behind  the  internal  auditory  meatus  near  the  inner  limb 
of  the  superior  semicircular  canal.  It  covers  in  a  part  of  the  cochlea,  the  vestibule,  and  the 
internal  auditory  meatus,*  completes  the  fenestra  ovalis,  and  invests  the  superior  semicircular 
canal. 

3.  The  pterotic  nucleus  ossifies  the  tegmen  tympani  and  covers  in  the  external  semicircular 
canal ;  the  ossific  matter  is  first  deposited  over  the  outer  limb  of  this  canal. 

4.  The  epiotic  is  the  last  to  appear,  and  is  first  seen  at  the  most  posterior  part  of  the  posterior 
semicircular  canal ;  it  is  often  double.     This  centre  gives  rise  to  the  mastoid  process. 

At  birth  the  bone  is  of  loose  and  open  texture,  resembling  biscuit  or  unglazed  porcelain,  thus 
off"ering  a  striking  contrast  to  the  dense  and  ivory-like  petrosal  of  the  adult.     It  also  diflfers  from 


Fig. 


-Temporal  Bone  at  Birth.     (Inner  view. 


HIATUS  FALLOPII 
FLOCCULAR  FOSSA 
AQUEDUCTUS  VESTIBULI 
INTERNAL  AUDITORY  MEATUS 


the  adult  bone  in  several  other  particulars.  The  floccular  fossa  is  widely  open  and  conspicuous. 
A''<)ltolini  has  pointed  out  that  a  small  canal  leads  from  the  floor  of  the  floccular  fossa  and  opens 
posteriorly  on  the  mastoid  surface  of  the  bone  ;  it  may  open  in  the  mastoid  antrum.  The  hiatus 
Fallopii  is  unclosed,  and  the  tympanic  recess  is  filled  with  gelatinous  connective  tissue.  The 
mastoid  process  is  not  developed,  and  the  jugular  fossa  is  a  shallow  depression. 

After  birth  the  parts  grow  rapidly.  The  tympanum  becomes  permeated  with  air  ;  the  various 
elements  fuse  ;  and  the  tymjianic  annulus  grows  rapidly  and  forms  the  tympanic  plate.  Growth 
in  the  tymi)anic  bone  takes  place  most  rapidly  from  the  tubercles  at  its  upjier  extremities,  and  in 
consequence  of  the  slow  growth  of  the  lower  segment  a  deep  notch  is  formed  ;  gradually  the 
tubercles  coalesce,  leaving  a  foramen  in  the  anterior  part  of  the  bony  meatus  which  persi^ts  until 
puberty,  and  even  in  the  adult.  In  most  skulls  a  cleft  capable  of  receiving  the  nail  remains  be- 
tween the  tympanic  element  and  the  ma.stoid  process  ;  this  is  the  auricular  fissure.  The  anterior 
portion  of  the  tympanic  plate  forms  with  the  inferior  border  of  the  .s(iuamosal  a  cleft  known  as 


44 


THE  SKELETON 


the  (ila.seiian  fissure,  which  is  subsequently  encroaclied  upon  by  the  growth  of  the  petrosal.  As 
the  tympanic  plate  increases  in  size  it  joins  the  outer  wall  of  the  carotid  canal  and  i)resents  a 
prominent  lower  edge,  known  as  the  vaginal  process. 

The  mastoid  process  becomes  distinct  about  the  first  year,  coincident  with  the  obliteration 
of  the  petro-s(iuamous  suture.  It  increases  in  thickness  by  deposit  from  the  periosteum. 
Towards  puberty,  rarely  earlier,  the  process  becomes  pneumatic,  the  air-cells  being  lined  by  deli- 


FiG.  53. — Tempor.\l  Bone  at  the  Sixth  Year. 


AUDITORY  MEATUS   _> 
OPENING  IN  THE  TYMPANIC  PLATE 
GLASERIAN   FISSURE 


{         5l_  wormun  bone  in  the  parietal 

<  ^  NOTCH 


cate  mucous  membrane.     In  old  skulls  the  air-cells  may  extend  into  the  jugular  process  of  the 
occipital  bone. 

At  birth  the  mastoid  antram  is  relatively  large  and  bounded  externally  by  a  thin  i)late  of 
bone  belonging  to  the  squamosal.  As  the  mastoid  increases  in  thickness  the  antrum  comes  to  lie 
at  a  greater  depth  from  the  surface  and  becomes  relatively  smaller. 


THE  PARIETAL 

The  two  parietals  form  a  large  portion  of  the  vault  and  sides  of  the  skull;  they 
are  interposed  Ijetween  the  frontal  anteriorly  and  the  occipital  posteriorly.  Each 
parietal  presents  two  surfaces,  four  borders,  and  four  angles.  The  external  surface 
is  convex  and  smooth :  the  convexit}',  best  marked  in  young  bones,  is  greatest  near 
the  centre,  wliich  is  termed  the  parietal  eminence.  Crossing  the  middle  of  the  bom- 
are  the  two  temporal  ridges  ;  the  lower  is  fre(|uently  the  better  marked,  and  limits 
the  origin  of  the  tcniporal  muscle.  The  upper  ridge  is  less  constant,  and  gives  attach- 
ment to  the  temporal  fascia.  The  internal  surface  is  concave  and  marked  Avith 
<lepressions  corresponding  to  the  cerebral  convolutions.  Numerous  vertical  deej) 
furrows  for  the  branches  of  the  middle  meningeal  artery  radiate  from  the  anterior 
inferior  angle  and  lower  border  of  the  bone.  Along  the  superior  margin  of  the 
bone  there  is  a  groove  which,  when  articulated  with  the  opposite  bone,  forms  a 
furrow  which  receives  the  superior  longitudinal  sinus.  In  adult  bones  numerous 
deep  circular  depressions  for  Pacchionian  bodies  are  found  near  tliis  groove.  The 
superior  Itorder  is  deeply  serrated  for  the  opposite  parietal,  the  union  with  which 
forms  the  sagittal  suture.  The  anterior  and  posterior  borders  are  deeply  serrated: 
the  anterior  articulates  with  the  frontal  to  form  the  coronal,  and  the  jxjsterior  with 
the  squamo-occipital  to  form  the  lambdoid  sutures.  The  inferior  border  is 
bevelled  and  overla])f)ed  by  the  squamosal  to  form  the  squamous  suture.  Of  the 
angles,  the  anterior  inferior  is  prolonged  downwards  and  avticidates  with  the  sum- 
mit of  the  greater  wing  of  the  sphenoid.  The  posterior  inferior  angle  articulates 
with  the  mastoid  portion  of  the  petrosal;  on  its  inner  surface  it  lias  a  liorizontal 
groove  for  lodging  a  portion  of  the  lateral  sinus.  The  superior  angles  present  noth- 
ing worthy  of  note. 


Tin:  PARIKTALS 


45 


Fig.  54.— The  Left  Parietal.     (Outer  siarlace.) 

SUPERIOR  BORDER  PARIETAL  FORAMEN 


.-.^^^^""'^ 


PORTION  COVERED  BY  __^ 
APONEUROSIS  OF  00-  ^ 
CIPITO-FRONTALIS 


SUPERIOR  TEMPORAL 
RIDGE 


INFERIOR  TEMPORAL 
RIDGE 

FOR  TEMPORAL  MUSCLE, 
AND  FORMS  PART  OF 
THE  TEMPORAL  FOSSA 


ANTERIOR  INFERIOR 
ANGLE 


Fig.  55.— The  Left  Parietal.     (Inner  surface.) 

PARIETAL  FORAMEN  GROOVE  FOR  SUPERIOR  LONGITUDINAL  SINUS  DEPRESSIONS  FOR  PACCHIONIAN  BODIES 


GROOVE  FOR  LATERAL  SINUS  GROOVES  FOR  MIDDLE  MENINGEAL  ARTERY 


46 


THE  SKELETUX 


Articulations. — The  parietal  articulates  with  its  fellow,  the  occipital,  squa- 
mosal frontal,  si)henoid,  and  the  epipteric  bones  when  present.  Occasionally  the 
squamosal  and  epipteric  may  exclude  the  parietal  from  union  with  the  greater  wing 
of  the  si)henoid. 

Blood-supply. — From  the  middle  meningeal,  occipital,  and  supraorbital 
arteries. 

Ossification. — The  parietal  ossifies  from  an  earthy  si)ot  deposited  in  the  outer 
layer  of  the  meml^ranous  wall  of  the  skull  about  the  seventh  week.  This  bone  is 
sometimes  divided  bv  a  horizontal  suture. 


THE  FRONTAL 

This  bone  bears  much  the  same  relation  to  the  anterior  part  of  the  skull  that 
the  occipital  bears  to  the  posterior.  It  has,  not  inaptly,  been  compared  to  a  cockle 
shell.      The  inner  or  posterior  surface  is  concave,  forming  a  deep  fossa  for  the 


Fig.  56. — The  Fkontal.     (Anterior  view.) 


TEMPORAL  RIDGE 


SUPRAORBITAL  NOTCH 
__  EXTERNAL  ANGUUR 
PROCESS 


recei)tion  of  the  frontal  lobes  of  the  cerebrum.  There  is  a  gap  in  tlie  lower  part  of 
the  hone  known  as  the  ethmoidal  notch,  which  overlaps  by  its  thin  edges  the 
cribriform  plate  of  the  ethmoid  and  forms,  with  that  bone,  the  internal  orifices  of 
the  anterior  and  posterior  ethmoidal  canals.  The  anterior  part  of  this  notch 
articulates  Avith  the  crista  galli,  and  the  small  hole  in  the  line  of  suture  is  the 
foramen  caecum.  Prolonged  vertically  upwards  from  the  point  of  union  with  the 
crista  is  a  ridge  of  bone,  which  gradually  opens  out  to  form  a  furrow  for  the 
reception  of  the  superior  longitudinal  sinus;  the  ridge  serves  for  the  attachment  of 
the  anterior  ])art  of  the  falx  cerel)ri.  The  thin  lamina?  of  bone  on  each  side  of  tlie 
ethmcjidal  notcli  are  termed  orbital  plates,  because  they  form  the  greater  j)art  of 
the  roof  of  each  orbit.  As  a  rule,  they  present  deep  depressions  for  the  convo- 
lutions on  the  orbital  surface  of  the  cerebrum.  The  rest  of  the  cerebral  surface  of 
the  frontal  is  fairly  smooth,  and  presents  a  few  furrows  for  meningeal  arteries,  and, 
near  the  median  groove,  pits  for  Pacchionian  bodies. 

The  external  surface   is  convex  and  smooth,  often   divided  by  an  imperfect 


THE  FROXTAL 


47 


fissure,  the  remains  of  the  metopic  suture,  -svhich  indicates  the  line  of  union  of 
the  two  bones  representing  the  Irontal  in  early  life.  On  each  side  of  this  suture  a 
little  Ijelow  the  centre  is  the  frontal  eminence.  Below  tlie  eminences,  separated 
l)y  shallow  grooves,  are  tlie  two  converging  superciliary  ridges,  which  approach 
each  other  in  the  median  line  to  form  the  nasal  eminence.  The  smooth  space 
l)ounded  l)y  the  converging  superciliaiy  ridges  is  tlie  glabella.  Below  these  ridges 
the  hone  presents  the  sharp  supraorbital  ridges  which  end  internally  at  the 
internal  angular,  and  externally  at  tlie  external  angular  processes.  Each  ridge 
lias  a  narrow,  deep  supraorbital  notch  (sometimes  a  complete  foramen)  at  the 
junction  of  the  inner  Avitli  tlie  middle  third.  At  the  bottom  of  this  notch  or 
foramen  a  small  opening  communicates  with  the  diploe.  The  external  angular 
jtrocesses  are  prominent  and  articulate  Avith  the  malar  bones;  from  each  process  a 
ridge  extends  upwards  and  Ijackwards,  marking  off  the  lateral  aspect  of  the  bone, 
where  it  assists  in  the  formation  of  the  temporal  ridge  and  fossa.  The  internal 
angular  processes  articulate  with  the  lachrymal  bones,  and  are  separated  by  a 
serrated  interval,  the  nasal  notch,  wdiich  receives  the  upper  borders  of  the  nasal 
bones,  and  outside  these  the  nasal  processes  of  the  maxillae.  The  notch  has  in  the 
middle  a  long  pointed  process,  the  nasal  spine,  which  lies  between  the  upper  part 
of  the  nasal  bones  and  the  mesethmoid.  On  each  side  of  the  spine  an  opening 
leads  into  the  large  frontal  sinuses. 

The  under  surfaces  of  the  orbital  plates  are  smooth  and  concave;  they  form  the 


ARTICULATION     WITH 
NASAL   BONE 
ARTICUUTION  WITH  MAX- 
ILLA 
ARTICULATION   WITH 
LACHRYMAL 


ARTICULATION    WITH    OS 
PLANUM 
ARTICULATION  WITH 

MALAR 
ARTICULATION  WITH 
GREATER  WING  OF 
SPHENOID 
ARTICULATION  WITH 
LESSER  WING  OF 
SPHENOID 


Fig.  57. — The  Frontal  Boxe. 
nasal  spine 


[Inferior  view.  1 


TROCHLEAR  FOSSA 


LACHRYMAL  FOSSA 


—    jRBITAL  SURFACE 


ETHMOIDAL  NOTCH 


roofs  of  the  orbits.  Each  is  sharply  limited  anteriorly  by  the  sujDraorl lital  ridge, 
and  presents  at  the  outer  angle  the  lachrymal  fossa  for  the  reception  of  the 
lachrymal  gland.  Near  the  internal  angle  there  is  the  small  shallow  supra- 
trochlear fossa  for  the  pulley  of  the  superior  obliqvie  muscle.  A  sharp  ridge  runs 
backwards  from  the  internal  angular  process,  and  articulates  successively  with  the 
lachrymal  and  the  os  planum  of  the  ethmoid.  It  has  two  notches,  which  are 
converted  into  the  anterior  and  posterior  ethmoidal  canals  by  articulation  with  the 
OS  planum.  The  posterior  border  of  each  orbital  plate  articulates  with  the  lesser 
wing  of  the  sphenoid  (orbito-sphenoid),  and  is  continuous  with  a  rough  triangular 
surface  for  the  greater  wing  (ali-sphenoid).  This  triangular  surface  is  continuous 
anteriorly  with  the  serrated  malar  ridge  of  the  frontal,  and,  laterally,  with  that 
border  of  the  bone  which  articulates  with  the  parietals  to  form  the  coronal  suture. 
Between  the  ethmoidal  notch  and  the  inner  margin  of  the  orljital  surface  there  is 
an  irregular  surface  which  forms  the  roofs  of  the  ethmoidal  cells. 

Articulations. — The  frontal  articulates  with  the  parietal,  sphenoid,  ethmoid, 
lachrymal,  malar,  maxilla,  and  nasal  l)ones;  with  the  epipterics  when  present, 
and  occasionally  (as  explained  on  page  38)  with  the  squamosal,  and  with  the 
sphenoidal  turbinal  when  it  creeps  into  the  orbit. 

It  has  the  following  muscles  attached  to  it: — 


Corrugator  supercilii. 
Temporal. 


Occipito-frontalis. 
Orbicularis  palpebrarum. 


4S 


THE  SKELKTOX 


The  blood-supply. — Arterial  twigs  derived  from  tlie  middle  and  small  menin- 
geal arteries  enter  it  on  the  eerebral,  and  branches  from  the  frontal  and  sui)raorbital 
arteries  on  the  outer  surface.  The  horizontal  plate  derives  twigs  from  the  ethmoidal 
and  otlier  branches  of  the  ophthalmic  artery. 

Ossification. — The  frontal  <levelops  from  two  eartliy  spots  dei)osited  in  the 
outer  layer  ol'  tlie  meml)ranous  wall  of  the  cranium,  in  "the  situations  ultimately 
known  as  the  frontal  eminences.  Tliese  nuclei  api)ear  about  the  eighth  week,  and 
(juicklv  spread  througli  tlie  membrane.  At  birth  the  bones  are  quite  distinct. 
yubse("iuently  they  articulate  with  each  other  in  the  median  line  to  form  the 
metopic  suture.  In  a  few  cases,  the  bones  remain  distinct  throughout  life.  In  the 
majority  of  cases  the  suture  is  obliterated;  ankylosis  commences  about  the  second 


Fig.  58.— The  Frontal  Bone  at  Birth. 


year.     In  adult  skulls,  traces  of  the  metopic  suture  may  often  be  seen  in  the  region 
of  the  glabella. 

After  the  two  halves  of  the  bone  have  united,  osseous  material  is  deposited  at 
the  lower  end  of  the  metopic  suture  to  form  the  nasal  spine,  which  is  one  of  the 
distinguishing  features  of  the  human  frontal  bone.  The  spine  appears  about  the 
twelfth  year,  and  soon  consolidates  with  the  bone  above.  Accessory  nuclei  are 
sometimes  seen  between  this  bone  and  the  lachrymal;  they  may  persist  as  Wormian 
ossicles. 

The  frontal  sinuses  appear  about  the  seventh  year  as  prolongations  from  the 
anterior  ethmoidal  cells.  Occasionally  they  invade  the  horizontal  plate,  and  extend 
over  the  roof  of  the  orbit. 


THE  EPIPTERIC  AND  WORMIAN  BONES 

The  epipterics  are  bones  of  variable  size  which  occupy  the  antero-lateral  fonta- 
nelles,  regions  indicated  in  the  adult  skull  by  the  name  pterion.  Each  epipteric 
bone  is  wedged  between  the  squamosal,  frontal,  greater  wing  of  sphenoid,  and  the 
parietal,  and  is  present  in  most  skulls  between  the  second  and  iifteenth  year. 
After  that  date  it  may  persist  as  a  separate  ossicle,  or  unite  with  the  frontal  or  the 
sijuamosal.  In  this  case  it  will  cause  a  fronto-squamosal  suture,  and  exclude 
the  parietal  from  the  s[)henoid.  More  conunonly  the  epipteric  joins  the  sphenoid. 
In  some  skulls  it  is  scarcely  as  large  as  a  split  pea,  in  others  it  is  as  broad  as  the 
thumb-nail.  The  e})ipteric  bone  is  pre-formed  in  membrane,  and  ap})ears  in  the 
course  of  the  first  year. 

The  W^ormian  bones  are  small,  irregular-shaped  ossicles,  often  found  in  the 
sutures  of  the  skull,  es])ecially  those  in  relation  with  the  )»arictal  bt)nes.  Wormian 
bones  sometimes  occur  in  great  mmiber;  as  many  as  a  hundred  have  been  counted 
in  one  skull.      They  are  rarely  present  in  the  facial  sutures. 


THE  ETHMOID 


49 


THE  ETHMOID 

The  ethmoid  is  a  bone  of  delicate  texture,  situated  at  the  anterior  part  of  the 
skull-base;  it  is  roughly  cuboidal  in  shape,  and  its  delicacy  is  due  to  the  fact  that 
it  is  honeycombed  by  air-cells.  The  bone  consists  of  four  })arts:  the  horizontal  or 
cril)riforni  })late,  two  lateral  masses,  and  a  perpendicular  i)late. 

The  cribriform  plate  forms  jjart  of  the  anterior  cerejjral  fossa,  and  is  received 
into  the  etlimoidal  notch  of  the  frontal  bone.  Standing  vertically  upon  this  plate 
is  the  crista  galli.  To  the  posterior  border  of  the  crista  the  falx  cerebri  is 
attaclied;  this  border  divides  posteriorly  to  enclose  the  ethmoidal  spine  of  the 
sphenoid.  The  anterior  aspect  of  the  base  of  the  crista  constitutes  the  anterior 
bt)rder  of  the  cribriform  plate;  it  is  rough  for  articulation  with  the  frontal.  In  the 
suture  between  the  two  bones  there  is  usually  an  opening,  the  foramen  caecum, 
wliich  when  present  transmits  a  small  vein.  On  each  side  of  the  crista  galli  the 
cribriform  plate  lodges  the  olfactory  bulb,  and  is  perforated  for  the  transmission  of 
the  filaments  of  the  olfactory  nerves.  On  each  side,  near  the  anterior  part  of  the 
crista,  there  is  a  narroAv  longitudinal  slit  for  the  nasal  branch  of  the  fifth  nerve. 


Fio.  59.— Section  through  the  Nasal  Fossa  to  show  the  Mesethmoid. 


CREST  OF  SPHENOIl 


GROOVE  FOR  NASAL  NERVE 


CREST  OF  PALATE  BONE 
SPINE  OF  PALATE  BONE 


NASAL  SPINE  OF  FRONTAL 


CREST  OF  MAXILLA 


The  perpendicular  plate  (mesethmoid)  is  directly  continuous  with  the  crista 
on  the  under  aspect  of  the  cribriform  plate.  It  is  a  lamella  of  bone,  trapezoid  in 
shape,  which  forms  the  upper  part  of  the  nasal  septum;  usually  it  is  laterally 
(lefiected.  Its  anterior  border  articulates  with  the  nasal  spine  of  the  frontal,  and 
the  crest  of  the  nasal  bones.  The  inferior  border  has  the  triangular  cartilage 
attached  to  it.  The  posterior  border  is  subdivided:  the  upper  half  articulates  with 
the  crest  of  the  sphenoid,  and  the  lower  articulates  with  tlie  vomer.  The  surfaces 
of  tliis  plate  present,  especially  in  their  upper  parts,  numerous  foramina  for  vessels, 
and  grooves  for  filaments  of  the  olfactory  nerves. 

The  lateral  mass,  or  labyrinth,  of  the  ethmoid  consists  t)f  two  scroll-like 
pieces  of  bone,  the  superior  and  inferior  turbinals  (ethmo-turl)inals);  a  smooth, 
(juadrilateral  plate  of  bone,  the  os  planum,  and  a  number  of  air-cells. 

The  OS  planum  is  on  the  outer  side  of  the  lateral  mass,  and  forms  a  large  jior- 
tion  of  the  inner  wall  of  the  orbit.  By  the  anterior  l»order  it  articulates  with  the 
lachrymal,  by  the  posterior  border  with  the  sphenoid  and  the  orltital  ]»rocess  of  the 
])alate  bone;  the  inferior  border  articulates  with  the  inner  margin  of  the  orlntal 
Xjlate  of  the  maxilla,  and  by  the  sujx'rior  l»order  with  the  horizontal  plate  of  the 
frontal.  Two  notches  in  the  superior  border  lead  into  grooves  running  liorizontally 
across  the  lateral  masses  to  the  cribriform  plate.  These  ethmoidal  grooves  are 
4 


50 


THE  SKELETON 


convertt'd  into  candi-^  ))y  the  frontal  Ijone.  The  anterior  canal  tran^^niits  the  anterior 
ethmoidal  artery  and  nasal  nerve;  the  posterior  is  for  the  posterior  ethmoidal  artery, 
and  a  Immch  of  the  nasal  ner\e. 

The  superior  and  middle  turbinals  project  on  the  inner  aspect  of  the  lateral 
mass;  thev  coalesce  anteriorly,  hut  are  separated  posteriorly  hy  a  space,  termed  the 
superior  meatus.  Eawh  turl»inal  has  an  attached  upper,  and  a  free,  slightly  con- 
voluted, lower  honk'r.  In  the  recent  state  they  are  covered  with  mucous  memlirane, 
and  present  numerous  forannna  for  Ijlood-vessels,  and  grooves  for  twigs  of  the 
olfactory  nerves. 

On  the  under  surface  of  each  lateral  mass,  near  the  anterior  corner  of  the  os 
planum,  an  irregular  hunina  of  hone  projects  downwards  and  Ijackwards.  This  is 
the  unciform  process  :  it  articulates  with  the  ethmoidal  process  of  the  inferior 
turhinal,  and  forms  a  small  part  of  the  inner  wall  of  the  antrum.  The  anterior 
part  of  the  lateral  mass  projects  forwards  in  front  of  the  os  planum  and  articulates 
with  the  inner  surface  of  the  nasal  process  of  the  maxilla. 

The  ethmoidal  cells  occupy  the  space  betAveen  the  os  planum  and  the  turl)inals; 
they  are  divided  l)y  a  thin  septum  into  an  anterior  and  a  posterior  set.  The  cells 
are  imperfect  in  the  ethmoid;  they  require  the  juxtaposition  of  other  bones  to  make 
them  complete.     Above,  they  are  closed  by  the  horizontal  plate  of  the  frontal, 

Fig.  60.^-The  Ethmoid.     (Side  view.) 

/Tf- CRISTA  GALLI 


ANTERIOR  ETHMOIDAL  GROOVE 


UNCIFORM  PROCESS 


INFERIOR  TURBINAL 


POSTERIOR  ETHMOIDAL  GROOVE 


SPHENOIDAL  TURBINAL 
MIDDLE  TURBINAL 


posteriorly  by  the  sphenoidal  turhinal  and  the  orbital  process  of  the  palate,  inferiorly 
by  the  maxilla,  and  anteriorly  by  the  lachrymal.  The  anterior  set  communicate 
with  the  frontal  cells  above,  whilst  below  they  open  into  the  middle  meatus  of  the 
nose  by  a  sinuous  canal,  the  infundibulum.  The  posterior  cells  open  into  the 
superior  meatus,  and  occasionally  communicate  with  the  sphenoidal  cells. 

The  cells  are  sometimes  divided  into  groups,  according  to  the  bone  which  lies  in 
innnediate  juxtaposition.  Those  along  the  superior  <Hlge  are  the  fronto-ethmoidal ; 
those  beneath  the  lachrymal,  lachrymo-ethmoidal,  usually  two  in  number. 
Those  along  the  lower  edge  are  the  maxillo-ethmoidal ;  and  ]iosteriorly  there  are 
the  spheno-ethmoidal,  ccjmpleted  l)y  the  sithenoidal  turl)inals,  and  a  palato- 
ethmoidal cell. 

Articulations. — The  ethmoid  articulates  with  tin'  frontal,  sphenoid,  two  i)alate 
l)ones,  two  nasals,  vomer,  two  inferior  turlnnals,  the  sphenoidal  turbinals,  two  max- 
illie,  and  two  lachrymal  bones.  The  posterior  surface  of  each  lateral  mass  comes 
into  relation  with  the  sphenoid  on  each  side  of  the  crest  and  rostrum,  and  heljis 
to  close  in  the  s|)henoi(lal  simis. 

Blood-supply. — The  anterior  and  ])osterior  ethmoidal,  and  from  the  nasal 
or  s|)heno-]ialatine  branch  of  the  internal  maxillary  artery. 

Ossification. — Tlie  ethmoid  has  three  centres  of  ossitii-ation.  Of  these,  a 
nucleus  api)ears  in  the  fourth  month  of  intra-uterine  life  in  each  lateral  cartilage. 


THE  SPHENOIDAL  TURBIXAL 


51 


At  birth  tliis  bone  is  represented  by  two  scroll-like  Itones,  very  delicate,  and  covered 
with  irregular  dej^ressions,  which  give  it  a  worm-eaten  appearance.  Six  months 
after  ])irth  a  nucleus  appears  in  the  ethmo-vomerine  plate  for  the  mesethmoid. 
This  gradually  extends  into  the  crista  galli.  During  the  third  year  the  lateral 
masses  and  tlie  mesethmoid  (perpendicular  plate)  ankylose.  The  criljriform  plate 
is  derived  from  the  lateral  masses. 

The  ethmoidal  cells  do  not  make  their  appearance  before  the  third  year,  and  they 
gradually  produce  attenuation  of  the  lateral  masses.     In  many  places  there  is  so 


Fig.  61.— Skction  through  the  Nasal  Fossa  to  show  the  Lateral  Mass  of  the 
Ethmoid,     It  shows  also  the  Outer  Wall  of  the  Left  Nasal  Fossa. 


BODY  OF  SPHENOID 

SPHENOIDAL  SINUS 

SPHENO-PALATINE  FORAMEN 

MIDDLE  MEATUS 

INTERNAL  PTERYGOID  PLATE 

PALATE  BONE 


FRONTAL  SINUS 

SUPERIOR  TURBINAL 
MIDDLE  TURBINAL 
INFUNDBULUM 

INFERIOR  T'-RBINAL 

ANTERIOR  NASAL  SPINE 

ANTERIOR  PALATINE  FORAMEN 


much  absorption  of  bone  that  the  cells  perforate  the  ethmoid  in  situations  where 
it  is  overlapped  by  other  bones.  Along  the  lower  border  of  the  bone,  near  its  articu- 
lation with  the  maxilla,  the  aljsoi-ption  leads  to  the  partial  detachment  of  a  narrow 
strip  known  as  the  uncinate  or  unciform  process.  Sometimes  a  second  but  smaller 
hook-like  process  is  formed,  above  and  anterior  to  the  large  one.  This  process  is 
so  very  fragile  that  it  is  difficult  to  preserve  it  in  disarticulated  bones.  The  relations 
of  the  uncinate  process  are  best  studied  by  removing  the  outer  wall  of  the  antrum. 


THE  SPHENOIDAL  TURBINAL 

These  l)ones  (often  referred  to  as  the  bones  of  Bertin)  are  two  hollow  cones, 
flattened  externally  in  three  planes.  They  may  be  obtained  as  distinct  ossicles 
about  the  fifth  year.     At  this  date  they  are  wedged  in  between  the  under  surface 

Fig.  62.— The  Sphenoidal  Turbixal  at  the  Sixth  Year. 


of  the  })re-sphenoid  and  the  orl)ital  and  si)henoidal  processes  of  the  palate  bone. 
The  apex  of  the  cone  is  directed  backwards,  and  appears  near  the  vaginal  jn-ocess 
of  the  sphenoid.  Of  its  three  surfaces,  the  outer  one  is  in  relation  with  the 
spheno-maxillary  fossa,  and  occasionally  extends  upwards  between  the  sphenoid 
and  the  os  planum  of  tlie  ethmoid  to  appear  on  the  inner  wall  of  the  orbit  (fig.  64). 


52 


THE  SKELETON 


The  inferior  sjurfaee  forms  the  upper  lioumlary  of  the  i<i)heno-palatine  foramen, 
and  enters  into  tlie  formation  of  the  posterit)r  \yAYi  of  tlie  roof  of  the  nasal  fossa. 
The  superior  surface  lies  flattened  against  the  under  surface  of  the  pre-sphenoid. 
The  base  of  the  cone  is  in  contact  with  the  posterior  surface  of  the  lateral  mass  of 
the  ethmoid. 

The  deposits  of  earthy  matter  from  which  the  si)henoidal  turV)inals  are  formed 
are  laid  down  at  the  fifth  month. 

At  birth  these  bones  are  visible  as  small  triantrular  ossifications  in  the  peri- 
chondrium of  the  ethmo-vomerine  plate  near  its  junction  with  the  pre-sphenoid, 
and  encloses  a  small  recess  which  becomes  a  sphenoidal  sinus.  By  the  third  year 
the  recesses  have  become  completely  enclosed  and  the  bones  have  become  hollow 


Ficj.  63.— The  Sphenoidal  Tcrbinals  from  an  Old  Skull. 


SPHENOIDAL  TURBINAL 


ROSTRUM  OF  SPHENOID 


cones,  the  circular  orifice  representing  the  base  eventually  becoming  the  orifice  of 
the  sphenoidal  sinus.  As  the  cavity  enlarges,  the  median  Avail  atrophies  so  that 
the  inner  Avail  of  the  sinus  is  formed  by  the  pre-sphenoid.  As  the  turbinal  en- 
larges it  ankyloses  Avith  adjacent  bones.  In  many  skulls  it  joins  the  lateral  mass 
of  the  ethmoid;  more  frequently  it  fuses  with  the  pre-sphenoid;  less  frequently 
Avith  the  palate.  After  the  twelfth  year  they  can  rarely  be  separated  from  the  skull 
Avithout  damage.  In  many  disarticulated  skulls  they  are  so  broken  up  that  a  por- 
tion is  found  on  the  sphenoid,  fragments  on  the  palate  bones,  and  the  remainder 
attached  to  the  ethmoid. 

Sometimes,  even  in  very  old  skulls,  they  are  represented  by  a  triangular  plate 
of  extreme  tenuity  on  each  side  of  the  rostrum  of  the  sphenoid  (fig.  63). 


Fig.  64. — The  Inferior  Turbinal,  Adult  Sphenoidal  Turbinal  and  Lachrymal  Bones. 


THE  CREST  OF  LACHRYMAL 
Tensor  tarsi 

THE  ORBITAL  SURFACE 
LACHRYMAL  GROOVE 


HAMULAR  PROCESS 

TURBINAL  PROCESS 

THE  LACHRYMAL  PROCESS 

THE  ETHMOIDAL  PROCESS 


THE  MAXILLARY  PROCESS 


THE  SPHENOIDAL  TURBINAL  WITH 
AN  ORBITAL  PROCESS 


MIDDLE  TURBINAL 


THE  INFERIOR  TURBINAL 

These  are  a  pair  of  delicate,  scroll-like  bones,  and  may  be  regarded  as  dis- 
memberments of  the  lateral  masses  of  the  ethmoid,  Avith  which  they  are  closely 
related.     Each  bone  presents  two  surfaces,  tAvo  borders,  and  two  extremities. 


THE  LACHRYMAL   AM)   VOMER  o3 

The  outer  surface  is  concave,  and  overhung  l)y  the  auricular  or  maxillary 
process.  The  inner  surface  is  convex  and  pitted  with  depression;^.  The  superior 
border  presents  from  l)efore  liackwards  three  processes:  the  tirst  is  called  the 
lachrymal  process,  l)ecause  it  articulates  with  tlie  turbinal  process  of  the  lachrymal 
hone.  The  margin  of  bone  at  the  l)ase  of  this  process  comes  into  relation  with 
the  nasal  process  of  the  maxilla.  The  second  vertical  spiculuni  is  the  ethmoidal 
process,  which  joins  the  uncinate  process  of  the  ethmoid.  The  third  or  maxillary 
process  is  a  thin  lamella  of  bone,  turned  downwards;  it  overhangs  the  oritice  of 
the  maxillary  sinus,  and  serves  to  fix  the  bone  firmly  to  the  outer  wall  of  the 
nasal  fossa.  The  margin  posterior  to  the  maxillary  process  comes  into  relation 
with  the  inferior  turbinal  crest  of  the  palate  bone.  The  inferior  l)order  is  rounded 
and  free.  It  is  the  thickest  part  of  the  bone.  The  extremities  are  narrow,  the 
posterior  ])eing  the  more  pointed. 

Articulations. — The  inferior  turbinal  articulates  with  the  maxilla,  lachrymal, 
palate,  and  ctlimoid. 

The  inferior  turbinal  is  ossified  in  cartilage  from  a  single  nucleus  which  appears 
about  the  fifth  month  of  intra-uterine  life. 

At  birth  it  is  a  relatively  large  bone,  and  fills  up  the  lower  part  of  the  nasal 
fossa. 


THE  LACHRYMAL 

The  lachrymal  bones  are  extremely  thin  and  delicate,  quadrilateral  in  shape, 
and  situated  at  the  anterior  part  of  the  inner  wall  of  the  orbit.  They  are  the 
smallest  of  the  facial  bones. 

The  outer  or  orbital  surface  is  divided  by  a  vertical  ridge  into  two  unequal 
})ortions.  The  anterior  smaller  portion  is  deeply  grooved  to  form  the  lachrymal 
sulcus,  which  lodges  the  lachrymal  sac  and  forms  the  commencement  of  the 
lachrymal  duct.  The  portion  Ixdiind  the  ridge  is  smooth,  and  forms  part  of  the 
inner  wall  of  the  orbit.  The  ridge  gives  origin  to  the  tensor  tarsi  muscle,  and 
terminates  inferiorly  in  a  hook-like  process,  the  hamulus,  which  curves  forwards  to 
articulate  with  the  lachrymal  tubercle  of  the  maxilla  and  completes  the  superior 
orifice  of  the  lachrymal  canal.  The  inner  surface  is  in  relation  with  the  two 
anterior  cells  of  the  ethmoid  (lachry mo-ethmoid),  and  forms  part  of  the  infundi- 
bulum.  The  superior  l^orcler  is  short,  and  articulates  with  the  internal  angular 
process  of  the  frontal.  The  lower  border  posterior  to  the  crest  joins  the  inner  edge 
of  the  orbital  plate  of  the  maxilla.  The  narrow  piece,  anterior  to  the  ridge,  is 
prolonged  downwards  to  join  the  lachrymal  spine  of  the  inferior  turbinal,  and  is 
called  the  turbinal  process.  The  anterior  border  comes  into  relation  with  the 
posterior  border  of  the  nasal  process  of  the  maxilla.  The  posterior  border  articu- 
lates with  the  OS  planum  of  the  ethmoid. 

Articulations. — The  lachrymal  articulates  with  the  ethmoid,  maxilla,  frontal 
and  inferior  turl)inal  bones. 

Blood-supply. — Its  arteries  are  derived  from  the  infraorbital,  the  nasal  l)ranch 
of  the  ophthalmic,  and  the  anterior  ethmoidal. 

Ossification. — This  bone  arises  in  the  membrane  overlying  the  cartilage  of  the 
fronto-nasal  j)late.  Its  mode  of  ossification  is  very  variable.  As  a  rule  it  is  de- 
scribed as  coming  from  one  nucleus.  Not  unfrequently  the  hamulus  is  a  separate 
element.  Sometimes  the  Ijone  is  divided  horizontally,  and  a  process  of  the  os 
planum  projects  between  the  two  halves  to  join  the  nasal  process  of  the  maxilla. 
More  rarely  the  bone  is  represented  by  a  group  of  detached  ossicles  resembling 
Wormian  l^ones. 


THE  VOMER 

The  vomer  is  an  irregular  four-sided  plate  of  l)one  constituting  the  lower  i)ortion 
of  the  nasal  septum.  It  is  usually  described  as  resembling  a  ploughshare  in  shape. 
Each  lateral  surface  is  covered  by  the  thick  nuicous  membrane  of  the  nasal  sinus, 
and  is  traversed  by  a  narrow  but  well-marked  groove,  which  lodges  the  naso- 


54 


THE  SKELETON 


palatine  nerve  from  the  ^:i)heno-i)alatine  ganglion;  lience  it  is  sometimes  called  the 
na--<o-p(d(itlnc  (jroorc. 

The  superior  horder  of  the  hone  is  expanded  laterally  into  two  aJiv.  Tlie  groove 
Ix'tween  them  lodges  the  rostrum  of  the  sphenoid,  whilst  the  margin  of  each  ala 
eomes  into  contact  with  the  sphenoidal  process  of  the  jjalate  hone.  Between  the 
al{e  and  the  sphenoid  a  canal  exists  on  each  side  of  the  rostrum  for  hlood-vessels. 
The  inferior  horder  is  uneven,  and  is  received  into  the  groove  formed  hy  the  crests 
of  the  opposed  maxillae  and  the  palatine  bones  of  each  side.  The  anterior  border 
joins  posteriorly  the  mesethmoid,  and  in  front  the  triangular  (median)  nasal 
cartilage.  The  posterior  l)order,  smooth,  rounded,  and  covered  by  mucous  mem- 
brane, serves  to  separate  the  posterior  nares.  The  anterior  and  inferior  borders 
meet  each  other  at  the  apex  of  the  bone. 

Articulations. — Tlie  vomer  articulates  with  the  sphenoid,  palates,  ethmoid, 
and  maxilhe,  and  with  the  triangular  cartilage. 


ANTERIOR  BORDER 

GROOVE  FOR  NASO-PALATINE  NERVE 

GROOVE  FOR  SEPTAL  CARTILAGE 

INFERIOR  BORDER 


Fig.  Go. — The  Vomek.     (Side  view.) 


POSTERIOR  BORDER 


Blood-supply. — Its  arteries  are  derived  from  the  anterior  and  posterior 
ethmoidal,  the  naso-palatine,  and  the  pterygo-palatine  arteries,  and  twigs  from  the 
posterior  palatines  through  Stenson's  canals. 

Ossification. — The  vomer  is  a  membrane-bone,  and  arises  from  a  single  centre 
deposited  in  the  lower  border  of  the  perichondrium  of  the  ethmo-vomerine  plate  as 
early  as  the  eighth  week.  From  this  single  centre  a  lamina  of  bone  extends  on 
each  side  of  the  cartilage  plate.  For  many  weeks  the  vomer  is  a  shallow  bony 
trough.  Gradually  it  presses  upon  and  induces  alisorption  of  the  enclosed  cartil- 
age, and  1)V  degrees  the  laminge  fuse,  and  form  a  rectangular  plate  of  bone.  At 
birth  the  vomer  presents  an  expanded  lo^^"x?r  border,  especialh^  in  cases  of  cleft 
jtalate. 

THE  XA.SAL 

These  are  two  oblong  bones  situated  in  the  middle  line  at  the  upper  part  of  the 
face,  and  forming  the  bridge  of  the  nose.  Each  bone  has  two  surfaces  and  four 
liorders.  The  facial  surface  is  concave  from  above  down^vards,  but  convex  from 
side  to  side.     Near  its  centre  is  a  foramen  for  the  transmission  of  a  small  tributarv 


Fio.  fifi.— The  Left  Nasal  P.oxe. 


SUPERIOR  BORDER 

MEDIAN  BORDER 
OUTER  BORDER 

INFERIOR  BORDER 


MEDIAN  BORDER 


GROOVE  FOR  NASAL  NERVE 


to  the  facial  vein.  The  posterior  or  nasal  sunace  is  concave  laterally,  and 
traversed  l)y  a  longitudinal  groove  for  the  nasal  branch  of  the  ophthalmic  nerve. 
In  life  this  surface  has  a  covering  of  mucous  membrane.  The  short  sui)erior 
l)order  is  tliick  and  serrated  for  articulation  Avith  the  nasal  notch  of  the  frontal. 
The  inferior  border  is  thin,  and  serves  for  the  attachment  of  the  lateral  nasal 
cartilages.      Plach  bone  articulates  with  its  fellow  bv  the  median  ])<)rder.  wliicli  is 


THE  MAXILLA  56 

prolonged  luu-kAvards  to  form  a  crot;  this  crest  comes  into  relation  with  the  nasal 
spine  of  the  frontal  and  the  anterior  border  of  the  mesethmoid.  The  outer  border 
articulates  witli  the  nasal  process  of  the  maxilla. 

Articulations. — The  nasal  bone  articulates  witli  its  fellow,  the  frontal,  maxilla. 
and  ethmoid. 

Blood-supply. — Twigs  to  this  bone  are  furnished  by  the  nasal  branch  of  the 
ojihthalmic,  the  frontal,  the  angular,  and  the  anterior  ethmoidal  arteries. 

Ossification. — Each  nasal  bone  is  developed  from  a  single  earthy  nucleus  in  the 
membrane  overlying  the  fronto-nasal  cartilage.  The  nucleus  is  easily  seen  during 
the  eighth  week.  The  bone  by  its  pressure  soon  produces  aV)sorption  of  the  under- 
lying cartilage.  At  l)irth  the  nasal  bones  are  nearly  as  wide  as  they  are  long, 
whereas  in  the  adult,  the  length  of  the  bones  is  three  times  greater  than  the  width. 


THE  MAXILLA 

The  maxilla^  are  two  hollow  irregular  cuboidal  bones  with  two  prominent  pro- 
cesses.    They  form  a  large  portion  of  the  facial  skeleton. 

This  bone  is  occupied  by  a  large  cavity,  the  antrum.  The  body  presents  four 
surfaces.  Of  these  the  facial  surface  looks  forwards  and  outwards  and  presents 
the  following  points  of  interest: — The  socket  for  the  canine  tooth  causes  a  low 
elevation,  the  canine  eminence,  having  to  its  inner  side  the  incisive  fossa,  from 
Avhieli  the  depressor  ahe  nasi  arises.  On  the  outer  side  of  the  eminence  is  the 
canine  fossa,  which  gives  origin  to  the  levator  anguli  oris.  Above  this  fossa  is  the 
infraorbital  foramen,  through  which  the  terminal  Vjranches  of  the  infraorbital 
nei-ve  and  artery  emerge.  From  the  ridge  al)Ove  this  foramen  the  levator  lahii  siqx- 
rioris  arises. 

A  ridge  of  bone  extending  upwards  from  the  socket  of  the  second  molar  tooth 
separates  the  facial  from  the  zygomatic  surface.  Near  the  middle  of  the  zygo- 
matic surface  are  the  orifices  of  the  canals  for  the  posterior  dental  ner^-es  and 
vessels.  The  posterior  inferior  angle  of  this  surface  is  termed  the  tuberosity ;  from 
it  a  few  fibres  of  the  internal  pteri/(/oid  nniscle  arise.  This  tuberosity  is  most  promi- 
nent after  eruption  of  the  wisdom  tooth;  the  rough  surface  along  its  inner  border  is 
for  the  tuberosity  of  the  palate  bone;  the  smooth  surface  immediately  above  forms 
the  anterior  boundary  of  the  spheno-maxillary  fossa,  and  enters  into  the  formation 
of  the  descending  palatine  canal. 

The  orbital  surface  is  irregularly  triangular  and  forms  the  greater  part  of  the 
floor  of  the  orbit.  Anteriorly  it  is  rounded  and  forms  part  of  the  circumference 
of  the  orbit;  externally  it  is  rough  for  suture  with  the  malar  bone;  the  rough 
surface  ends  in  a  backwardly  projecting  spine  which  occasionally  joins  the  sphenoid 
and  forms  the  anterior  limit  of  the  spheno-maxillary  fissure.  The  posterior 
margin,  smooth  and  rounded,  forms  the  inferior  limit  of  the  spheno-maxillary 
Assure.  The  internal  border  is  nearly  straight;  quite  at  the  posterior  part  is  a 
gap  for  the  orlntal  process  of  the  palate  bone;  anteriorly  it  articulates  with  the 
OS  i)lanum  of  the  ethmoid;  beyond  this  it  receives  the  lachrymal  bone,  and  in  the 
anterior  angle  it  is  smooth  and  rounded,  forming  part  of  the  circumference  of  the 
orbital  orifice  of  the  lachrymal  duct. 

The  orbital  surface  is  traversed  b}'  the  infraorbital  groove,  which,  commenc- 
ing at  the  posterior  border,  deepens  as  it  passes  forwards  and  enters  the  infra- 
orbital canal.  This  groove  receives  the  second  division  of  the  fifth  nerve  and  the 
infraorbital  artery.  The  infraorbital  canal  runs  under  the  margin  of  the  orbit 
and  opens  on  the  facial  surface.  It  transmits  the  infraorbital  artery  and  nerve. 
At  the  termination  of  the  groove  a  smaller  canal  tunnels  the  anterior  wall  of  tlie 
antrum,  and  conveys  the  anterior  dental  nerves  and  vessels  to  the  upper  incisor, 
canine,  and  l)icuspid  teeth.  External  to  the  commencement  of  the  lachrymal  duct 
there  is  a  shallow  depression  frcmi  which  the  inferior  oblique  takes  origin. 

The  internal  or  nasal  surface  forms  the  outer  wall  of  the  nasal  fossa,  and  is 
prolonged  inwards  to  form  ])art  of  the  floor  of  this  fossa.  The  posterior  half  of  this 
surface  is  deficient,  and  leads  by  a  large  irregular  aperture  into  the  antrum  ;  below 
and  behind  this  opening  the  bone  is  rough  for  articulation  with  the  vertical  plate 


56 


THE  SKKLKTOX 


of  till'  palate  hoiu'.  The  extreme  posterior  border  receives  the  tuberosity  of  the 
])alate  hone;  the  grocjve  in  front  of  it  forms  jxirt  of  the  ])osterior  palatine  canal. 
.Vnterior  to  this  surface  the  hone  l)ecomes  suddenly  smooth;  Ijetween  the  smooth 
and  roujzh  portions  is  the  maxillary  fissure  for  the  reception  of  the  thin  maxillary 
process  on  the  anterior  border  of  the  vertieal  plate  of  the  palate  bone.  In  the 
antrle  between  this  surface  and  the  nasal  process  is  a  deep  groove  converted  by  the 
laehrvmal  and  inferior  turV)inal  into  the  nasal  duct.     Running  liackwards  from 


Fig.  Gl. — The  Left  ^Iaxim.a.     (Outer  view.) 


INfRAORBITAL  FORAMEN 

NASAL  NOTCH 

CANINE  FOSSA 

NASAL  SPINE 

INCISIVE  FOSSA 

CANINE  EMINENCE 


BORDER  OF  SPHENO-MAXILLARY 

FISSURE 
FOR  SPHENOID 

ZYGOMATIC  SURFACE 
MALAR  PROCESS 
POSTERIOR  DENTAL  CANALS 


the  anterior  margin  is  the  inferior  turbinated  crest  which  articulates  with  the 
lowest  turbinal  bone.  The  surface  above  the  crest  forms  part  of  the  middle 
nieatus,  and  the  surface  below  belongs  to  the  inferior  meatus  of  the  nose,  and  is 
directly  continuous  with  the  superior  surface  of  the  i)alatine  process.  Near  its 
anterior  border  is  the  orifice  of  the  anterior  palatine  canal. 

The  inferior  or  palatine   surface  is  formed  by  the  palatine  process  and  the 
alveolar  liorder.     The  palatine  process  forms  the  anterior  part  of  the  roof  of  the 


Fig.  68.— The  Left  Maxii.la.     (Inner  view.) 

NASAL  PROCESS 


POSTERIOR  PALATINE  GROOVE 
PALATINE  PROCESS 


RIDGE  FOR  MIDDLE  TURBINAL 


—  LACHRYMAL  GROOVE 

RIDGE  FOR  INFERIOR  TURBINAL 


ANTERIOR  PALATINE  GROOVE 


inouth.  It  is  concave,  rough,  and  pitted  with  foramina  for  vessels.  Where  it 
joins  the  alveolar  border  a  groove  (sometimes  a  canal)  exists  for  the  anterit)r 
palatine  nerve  and  ])osterior  palatine  vessels.  When  the  bones  of  opposite  sides 
are  placed  in  apposition  the  palatine  fossa  is  formed;  running  outwards  from  this 
to  the  space  between  the  second  incisor  and  canine  tooth,  the  maxillo-premaxillary 
suture  can  be  detected  in  young  bones.  Tlie  posterior  border  articulates  with  the 
horizontal  process  of  the  palate  bone,  whilst  the  median  border  joins  its  fellow  to 
form  above,  a  ]irominent  crest  upon  which  the  vcMuer  is  received. 


THE  MAXILLA 


57 


The  anterior  palatine  fossa  is  situated  in  the  meso-palatine  suture  near  its 
anterior  termination.  In  its  typical  form  the  fossa  contains  four  i)assages:  two  are 
small  and  dis])()sed  one  l)ehind  the  other  exactly  in  the  suture;  these  are  the 
foramina  of  Scarpa  for  the  naso-palatine  nerves,  the  left  nerve  emerging  from  the 
anterior  foramen.  The  lateral  and  larger  orifices  diverge  to  open  on  each  side  of  the 
crest.  They  are  called  Stenson's  canals,  and  lodge  recesses  of  the  nasal  mucous 
membrane  and  remnants  of  Jacobson's  organs. 

Th(^  alveolar  ridge  forms  the  outer  limit  of  this  surface;  it  is  creseentic  in 
shape,  spongy  in  texture,  and  presents  cavities  in  which  teeth  are  lodged.  When 
the  teeth  are  complete  in  number,  eight  cavities  are  i)resent;  of  these  the  pit  for 
th(!  canine  tootli  is  the  deepest,  those  for  the  molars  are  the  widest  and  present 
subdivisions.  Along  the  outer  aspect  of  the  alveolar  l)order  the  buccinator  arises  as 
far  forwards  as  the  first  molar  tooth. 

The  nasal  process  is  somewhat  triangular,  rising  vertically  from  the  nasal 
angle  of  the  maxilla.  Its  outer  surface  gives  attachment  to  the  orbicularis  palpe- 
brannn,  the  tendo  oculi,  and  the  levator  labii  superioris  alseque  nasi.  The  internal 
surface  forms  one  of  the  lateral  boundaries  of  the  nasal  fossa.  Superiorly  it 
articulates  with  the  frontal;  below  this  is  the  superior  turbinated  crest  for  articu- 
lation with  the  middle  turliinal.  The  space  between  this  and  the  inferior  turbin- 
ated crest  forms  ])art  of  the  middle  meatus.  The  anteri(jr  l)order  articulates  with 
the  nasal  l)one;  the  posterior  is  thick  and   vertically  grooved  to  form   {)art   of   the 


Fig.  (iii. — Thk  Maxili.a  at  Birth. 

PftEMAXILLARY   P3RTI0N 


Outer  view. 


Inferior  view. 


Inner  view. 


nasal  duct.  The  inner  margin  of  this  groove  articulates  with  tlie  lachrymal  Ixme. 
The  point  where  the  outer  margin  of  the  groove  joins  the  orl)ital  plate  is  indicated 
by  the  lachrymal  tubercle. 

The  malar  process  is  rough  and  triangular,  and  forms  the  summit  (jf  the 
ridge  of  bone  separating  the  facial  and  zygomatic  surfaces.  It  articulates  with  the 
malar  bone,  and  from  its  inferior  angle  a  few  fibres  of  the  ina^^neter  take  origin. 

Tlie  antrum  or  maxillary  sinus,  as  the  air-chamber  occupving  the  body  of  the 
bone  is  called,  is  somewhat  pyramidal  in  shape;  the  base  lieing  represented  by  the 
nasal  or  internal  surface,  ancl  the  apex  corresponding  to  the  malar  process.  In 
addition  to  these  it  has  four  walls:  the  superior  is  formed  I)y  the  orI)ital  plate,  and 
the  inferior  by  the  alveolar  ridge.  The  anterior  wall  corres})onds  to  the  facial  sur- 
face of  the  maxilla,  and  the  posterior  is  formed  by  the  zygomatic  surface.  Tin- 
inner  l^oundary  or  base  presents  a  very  irregular  oritice  at  its  posterior  })art;  this 
is  partially  filled  in  by  the  vertical  plate  of  the  palate  bone,  the  uncinate  process  of 
the  ethmoid,  the  maxillary  process  of  the  inferior  turbinal,  and  a  small  portion  of 
the  lachrymal  bone.  Even  when  these  bones  are  in  situ,  the  nasal  oritice  is  very 
irregular  in  shape,  and  requires  the  mucous  membrane  to  form  the  definite  rounded 
aperture  (or  apertures,  for  they  are  often  multi])le)  known  as  the  opening  of  the 
antrum.  The  cavity  of  the  antrum  varies  considerably  in  size  and  shai)e.  In  the 
young,  it  is  small  and  the  walls  are  thick:  as  life  advances,  the  antrum  enlarges 
at  the  expense  of  its  walls,  and  in  old  age  they  are  often  of  extreme  tenuity; 
occasionally  the  cavity  extends  into  the  suljstance  of  the  malar  bone.     The  Hoor  of 


58  THE  SKELETON 

till'  antrum  is,  as  a  rulr,  very  uneven,  due  to  prominences  corresponding  to  the 
roots  of  the  molar  teeth.  In  most  cases  the  bone  separating  the  teeth  from  tlie 
antrum  is  very  thin,  and  not  rarely  the  roots  project  uncovered  into  it.  The 
teeth  which  come  into  closest  relationship  with  the  antrum  are  the  first  and  second 
molars,  but  the  sockets  of  any  of  the  teeth  lodged  in  the  maxilla  may,  under 
diseased  conditions,  communicate  with  it.  Although,  as  a  rule,  the  cavity  of  the 
antrum  is  single,  yet  specimens  occasionally  come  to  hand  in  which  it  is  divided 
l)y  bony  sei)ta  into  chambers,  and  it  is  far  from  uncommon  to  find  it  divided  into 
recesses  l>y  bony  processes.  In  many  maxilhe,  the  roof  of  the  antrum  presents 
near  its  anterior  aspect  Avhat  appears  to  be  a  thick  rib  of  bone;  this  is  hollow  and 
corresponds  to  the  infraorl)ital  canal. 

The  most  satisfactory  method  of  studying  the  relation  of  the  bones  closing  in 
the  base  of  the  antrum  is  to  cut  away  the  outer  wall  of  the  cavity  (see  fig.  80). 

Articulations. — The  maxilla  articulates  with  its  felloAV,  and  with  the  fronted, 
nasal,  laclu-ymal,  ethmoid,  palate,  vomer,  malar  and  inferior  turbinal  bones.  Occa- 
sionally it  articulates  with  the  greater  wing,  and  less  frequently  with  the  pterygoid 
})rocess  of  the  sphenoid  bone. 

The  muscles  attached  to  it  are  mainly  those  known  as  muscles  of  expression: — 

Compressor  naris.  Levator  anguli  oris. 

Orbicularis  palpebrarum.  Inferior  oblique. 

Orbicularis  oris.  Depressor  alae  nasi. 

Levator  labii  superioris.  Buccinator. 

Levator  labii  superioris  alaeque  nasi.  Internal  pterygoid. 

Masseter. 

Blood-supply. — The  maxilla  is  a  very  vascular  bone,  and  its  arteries  are  nume- 
rous and  large.  They  are  derived  from  the  infraorbital,  alveolar,  descending  palatine, 
naso-])alatine.  ethmoidal,  frontal,  nasal,  and  facial  vessels. 

Ossification. — The  maxilla  arises  from  four  centres  Avliich  are  deposited  in 
membrane. 

The  various  centres  may  be  termed  premaxillary,  maxillary,  malar,  and  pre- 
palatine.  They  arise  about  the  eighth  week  of  embryonic  life,  and  fuse  very 
raj)  idly. 

(rt)  The  premaxillary  nucleus  gives  rise  to  that  portion  of  the  bone  which 
lodges  the  incisor  teeth.  It  sends  a  narrow  process  upwards  which  forms  part  of 
the  outer  boundary  of  the  anterior  narial  aperture.  On  the  palatine  aspect  it 
furnishes  a  spiculum  which  surrounds  the  anterior  and  mesial  aspect  of  Stenson's 
(tanal.  The  posterior  limit  is  indicated  up  to  the  end  of  the  first  dentition  by  the 
maxillo-premaxillarv  suture.  The  greater  part  of  this  centre  is  formed  in  mem- 
brane, but  the  inner  part  subsequently  invades  the  ethmo-vomerine  cartilage. 

(ft)  The  maxillary  nucleus  forms  the  nasal  process,  and  the  greater  part  of  the 
body  of  the  maxilla. 

(c)  The  malar  centre  gives  origin  to  that  portion  of  the  bone  lying  external  to 
the  infraorbital  groove. 

{d)  The  prepalatine  centre  gives  rise  to  the  nasal  surface  of  the  maxilla  and 
the  palatine  process  posterior  to  Stenson's  canal.  This  i)ortion  is  in  shape  similar 
to  the  j)alate  bone. 

THE  PALATE  BONE 

The  palate  bone  is  R'ctangular  in  shape,  and  wedged  between  the  maxilla  and 
the  pterygoid  processes  of  the  sphenoid.  It  has  a  horizontal  and  a  vertical  plate, 
a  tuberosity,  and  two  processes. 

The  horizontal  plate  is  smaller  than  the  vertical;  it  is  (luadrilaternl  in  shape. 
The  ui)])er  surface  forms  the  posterior  part  of  the  floor  of  the  nasal  fossa;  the 
inferior  surface  completes  the  hard  jjalate  posteriorly,  and  presents  near  its  pos- 
terior border  a  transverse  ridge,  which  gives  attachment  to  the  temor  pahiti  muscle. 
The  anterior  l)order  is  rough  for  articulation  with  the  palatine  process  of  the 
maxilla.      The  posterior  border  is  free,  curved,  and  sharp;  it  gives  attachment  to 


I 


THE   I' A  LATE  BOXE 


59 


the  soft  palate.  The  inner  border  is  broad,  and  rough  for  articulation  with  its 
fellow.  When  the  palate  bones  are  in  apposition,  these  Ixjrders  fonn  a  ridge  con- 
tinuing the  crest  formed  by  the  palatine  processes  of  the  maxilla);  this  crest 
receives  the  inferior  border  of  the  vomer.  The  posterior  extremity  of  the  crest 
forms  the  posterior  nasal  spine,  from  which  the  azygos  uvulas  arises. 

The  vertical  plate  is  thin;  of  its  two  surfaces,  the  outer  is  rough  for  articula- 
tion Avith  the  maxilla,  except  a  small  portion  near  the  middle  close  to  the  anterior 
border  where  it  hjoks  into  the  antrum,  and  a  small  triangular  surface  at  the  upper 
end  where  it  forms  part  of  the  spheno-maxillary  fossa.  Towards  the  posterior 
border  there  is  a  vertical  groove,  which  forms  with  the  maxilla  the  posterior  palatine 
canal;  it  transmits  the  descending  jialatine  nerves  and  vessels.  The  canal  may  be 
more  or  less  complete  in  the  palate  bone.  The  internal  surface  has  two  transverse 
ridges  separating  three  shallow  depressions.  Of  these  depressions  the  lower  forms 
part  of  the  inferior  meatus  of  the  nose,  and  the  limiting  ridge  or  crest  articulates 
with  the  inferior  turbinal.  Above  this  is  the  dejiression  for  part  of  the  middle 
meatus;  the  ridge  above  is  for  the  second  turbinal.  The  upj^er  groove  is  narrower 
and  deeper  than  the  lower  two,  and  forms  a  large  part  of  the  superior  meatus.  The 
ridges  are  known  as  the  turbinated  crests.  The  borders  of  the  vertical  plate  are 
terminated  by  irregular  prominences,  wliich  enter  into  complex  union  with  sur- 
rounding bones. 

Fig.  70.— Palate  (Left)  Boxe.     (Inner  \ievc.) 


SPHENOIDAL  PROCESS 
SPHENO-PALATINE  NOTCH 
(WHEN  THE  FORAMEN  IS 
COMPLETE  IN  THE  PALATE 
BONE,  IT  IS  DUE  TO  ANKY- 
LOSIS WITH  SPHENOIDAL 
TURBINAL) 


ORBITAL  PROCESS 
(ETHMOIDAL  SURFACE) 


SUPERIOR  MEATUS 
SUPERIOR  TURBINATED  CREST 


MIDDLE  MEATUS 

INFERIOR  TURBINATED  CREST 
INFERIOR  MEATUS 


The  posterior  border  is  vertical,  and  comes  into  relation  with  the  anterior 
border  of  the  internal  pterygoid  process;  below,  it  terminates  in  a  prominent 
tuberosity.  This  presents  three  grooves  or  flutes:  the  inner  receives  the  internal 
l)terygoid,  the  outer  tlie  external  pterygoid  process,  Avhile  the  middle  groove  com- 
pletes the  pterygoid  fossa,  and  affords  attachment  to  a  few  fibres  of  the  internal 
pterygoid  nniscle;  X\\e  sv  per  lor  constrictor  of  the  pharynx  also  arises  from  this  process. 
The  tuberosity  is  tunnelled  l)y  canals:  to  the  nasal  side  are  the  accessory  palatine 
canals  ;  near  its  junction  Avith  the  horizontal  plate  is  the  orifice  of  the  posterior 
palatine  canal ;  and  outside  this  occasionally  may  be  found  the  nnnute  external 
palatine  canals  (fig.  81). 

Tlie  sphenoidal  process,  which  is  a  process  of  variable  shape,  surmounts  the 
posterior  l)ordcr;  it  has  three  surfaces  and  two  borders.  The  superior  surface 
comes  into  ai)i)osition  with  the  sphenoidal  turbinal  bone,  and  forms  jjart  of  the 
pterygo-palatine  canal.  The  internal  surface  forms  part  of  the  outer  wall  of  the 
nasal  fossa,  and  is  prolonged  on  to  the  roof,  and  comes  in  contact  with  the  ala  of 
the  vomer.  The  outer  surface  is  subdivided  by  a  thin  lip  into  an  anterior  smooth 
portion  for  the  spheno-maxillary  fossa,  and  a  posterior  rough  i)art  for  the  base  of 
the  internal  pterygoid  plate.  (If  the  borders,  the  posterior  is  thin  and  articulates 
with  the  internal  i)terygoid  plate;  the  anterior  border  forms  the  posterior  boundary 
of  the  spheno-palatine  foramen. 

The  anterior  border  of  the  vertical  plate  is  thin,  sharp,  and  ])resents  near  the 
middle  the  maxillary  process,  which  is  received  into  the  maxillary  lissure  of  the 
maxilla  near  the  lower  border  of  the  opening  of  the  antrum. 


60  THE  SKELETON 

.Superiorly  this  border  is  terminated  l>y  tlic  orbital  process.  This  process 
presents  tive  surfaces;  of  these,  three  are  artieuhir.  The  posterior  surface  joins  the 
walls  of  the  sphenoidal  turbinal  bone,  its  air-cells  extending  occasionally  into  this 
part  of  the  palate  bone.  In  the  same  way  the  posterior  ethmoidal  cells  extend  into 
the  inner  surface  of  the  orbital  process,  where  they  articulate  with  the  lateral  mass. 
The  anterior  surface  is  a  continuation  of  the  outer  aspect  of  the  A'ertical  plate,  and 
rests  upon  the  maxilla.  O!  the  two  non-articular  surfaces,  the  one  directed 
upwards  and  outAvards  is  slightly  concave,  and  forms  part  of  the  floor  of  the 
orbit  at  its  junction  with  the  inner  wall.  The  outer  smooth  surface  looks 
directly  into  the  zygomatic  fossa,  extends  into  the  spheno-maxillary  fossa,  and 
forms  the  anterior  boundary  of  the  spheno-palatine  foramen.  These  surfaces 
are  often  conveniently  named  according  to  the  bones  with  which  they  articu- 
late, or  the  fossae  which  they  help  to  form:  thus,  the  anterior  or  maxillary; 
internal  or  ethmoidal ;  posterior  or  sphenoidal ;  superior  or  orbital ;  external 
or  zygomatic. 

Between  the  orl)ital  and  sphenoidal  processes  is  the  spheno-palatine  notch, 
which  is  converted  by  the  sphenoidal  turbinal  into  a  complete  foramen.  Occa- 
sionally it  is  complete  in  the  palate  bone.  It  transmits  the  spheno-palatine  nerve 
and  artery;  the  foramen  opens  into  the  back  part  of  the  nasal  fossa,  close  to  its 
roof.      When  the  spheno-palatine  foramen  is  complete  in  the  palate  bone,  it  is 

Fig.  71. — Palate  Bone.     (Posterior  view.) 


ORBITAL  SURFACE  — 

ORBITAL  PROCESS 
ZYGOMATIC  SURFACE ^^SISK^i.-  (SURFACE  FOR  SPHENOIDAL  TURBINAL) 


SPHENO-PALATINE  FORAMEN 
(USUALLY  A  NOTCH) 


GROOVE  FOR  EXTERNAL  PTERYGOID 


SPHENOIDAL  PROCESS 


GROOVE  FOR  PTERYGOID  FOSSA 
GROOVE  FOR  INTERNAL  PTERYGOID   f:^ — {&  i^^ SPINE  OF  PALATE 


often  due  to  ankylosis  between  the  palate  and  the  sphenoidal  turbinal;  the  latter, 
being  extremely  fragile,  easily  breaks  during  the  process  of  disarticulation. 

Articulations.— The  palate  bone  articulates  Avith  its  fellow,  the  sphenoid, 
maxilla,  vomer,  sphenoidal  turbinal,  inferior  turbinal,  and  ethmoid  bones.  As  tin- 
surfaces  and  lines  of  union  of  the  orbital  and  sphenoidal  processes  are  somewhat 
intricate,  the  student  should,  when  studying  this  bone,  refer  to  the  following 
figures.  The  orbital  and  zygomatic  surfaces  are  shown  in  fig.  80.  The  relation  of 
the  sphenoidal  process  to  the  nasal  fossa  in  fig.  61.  The  relations  of  the  pterygoid 
processes  to  the  tuberosity  of  the  palate  are  shown  in  fig.  81.  ^\'ith  the  help  of 
these  drawings  the  student  will  be  aV)le  to  understand  the  position  of  this  bone, 
which  assists  in  forming  the  boundary  of  the  following  cavities:  viz.  the  nasal, 
orbital,  spheno-maxillary,  and  antral;  and  the  ethmoidal  cells. 

The  muscles  attached  to  it  are: — 

Internal  pterygoid.  Tensor  palati.  Azygos  uvute. 

Superior  constrictor  of  pharynx. 

Blood-supply. — Its  arteries  are  derived  from  the  descending  palatine,  the 
spheno-i»alatinc.  and  pterygo-palatine. 

Ossification. — The  palate  bone  arises  from  one  nucleus,  which  is  deposited  in 
membrane,  and  appears  about  the  eighth  week  of  embryonic  life.  The  sjiot  where 
the  carthv  matter  is  first  seen  ultimatelv  becomes  the  angle  where  the  vertical  and 


THE  MALAR   BOXES 


61 


liorizontal  plates  join.  At  birth  the  two  plates  are  nearly  equal,  but  as  the  nasal 
sinuses  increase  in  height  the  vertical  plate  is  lengthened,  until  it  becomes  twice 
the  length  of  the  horizontal  plate. 

THE  MALAR 

The  malar  bone,  somewhat  quadrilateral  in  shape,  is  situated  at  the  outer  and 
upper  part  of  the  side  of  the  face,  and  forms  the  prominence  known  as  the  cheek. 

Each  bone  has  a  convex  external  surface,  presenting  near  the  centre  one  or  two 
minute  orifices  for  the  transmission  of  the  malar  nerves  and  arteries.  This  surface 
is  largely  covered  by  the  orhkularh  palpchrarvrn,  and  gives  origin  to  the  zygomaticus 
major  and  minor. 

The  internal  surface  is  concave,  and  aljruptly  excluded  from  the  orl)it  by  a 
prominent  ledge  of  bone,  the  orbital  process,  which  forms  the  anterior  boundarv 
of  the  temporal  fossa.  A  large  part  of  this  surface  is  rough  for  articulation  Avith 
the  malar  process  of  the  maxilla.  The  orbital  process  of  the  malar  is  at  right 
angles  with  the  external  surface,  and  presents  the  orbital  orifice  of  the  malar  canal; 


Fig.  72. — The   Lkft  Malar  Boxe. 

frontal  process 


ORBITAL  BORDER 

MALAR  CANAL 

MAXILLARY  PROCESS 

ANTERIOR  BORDER 


POSTERIOR  BORDER 


ZYGOMATIC  PROCESS 


INFERIOR  BORDER 


NOTCH  FOR  TEMPORAL  NERVE 

FOR  SPHENOID 
MALAR  CANAL 


ORBITAL  PROCESS 


MALAR  CANAL 
MAXILLARY  PROCESS 


MAXILLARY  SURFACE 


this  canal  is  usually  single,  but  it  may  bifurcate  as  it  traverses  the  bone,  one 
branch  emerging  on  the  external,  the  other  on  the  internal  surface.  The  thin  edge 
of  this  process  articulates  inferiorly  with  the  orbital  plate  of  the  maxilla,  and  ends 
in  a  point  known  as  the  maxillary  process.  The  superior  portion  articulates  with 
the  malar  crest  on  the  external  surface  of  the  greater  wing  of  the  sphenoid;  in  the 
suture  between  these  bones  a  notch  (sometimes  a  foramen)  exists  for  the  temporal 
branch  of  the  fifth  nerve.  When  the  orbital  surface  is  large,  it  excludes  the 
sphenoidal  wing  from  articulation  with  the  maxilla  at  the  anterior  extremity  of  the 
spheno-maxillary  fissure.  AMien  this  is  the  case,  the  border  presents  near  its 
middle  a  short  non-serrated  margin. 

The  malar  bone  presents  superiorly  the  frontal  process,  wliich  articulates  with 
the  external  angular  process  of  the  frontal  bone.  The  maxillary  process  articu- 
lates with  the  maxilla,  and  occasionally  forms  the  superior  segment  of  tlie  infra- 
orl)ital  foramen.  The  zygomatic  process  is  directed  backwards,  and  is  serrated 
mainly  on  its  inner  aspect  for  articulation  with  the  zygoma. 

Of  the  four  borders,  the  orbital  is  the  longest,  and  extends  from  the  frontal 
to  the  maxillary  process.     It  is  thick,  rounded,  and  forms  the  anterior  third  of 


r,2  THE  SKELETOX 

the  outer  anil  a  lart^e  portion  of  tlie  lower  wall  and  inferior  circumference  of  the 
orbit.  The  inferior  is  continuous  with  the  zygoma,  and  gives  origin  to. the 
anterior  fibres  of  the  masseter.  The  anterior  border  is  in  relation  with  the  maxilla, 
and  near  the  margin  of  the  orbit  gives  origin  to  a  portion  of  the  levator  labri  superi- 
oris.  The  posterior  border  extends  from  the  frontal  to  the  zygomatic  process,  and 
presents  a  doul)l('  curve;  it  gives  attachment  to  the  temporal  fascia.  This  Ijorder 
is  directly  continuous  below  with  the  upi)er  border  of  the  zygoma,  and  above  with 
the  temporal  ridge. 

Articulations. — The  malar  articulates  with  the  maxilla,  frontal,  sphenoid,  and 
temporal  l)ones. 

Blood-supply, — The  arteries  of  the  malar  are  derived  from  the  infraorl)ital, 
lachrymal  l)ranches  of  the  ophthalmic,  transverse  facial,  and  deep  temporal  arteries. 

The  muscles  connected  with  it  are: — 

Zygomaticus  major.  Zygomaticus  minor. 

Levator  lal;)ii  superioris.  Masseter. 

Ossification. — The  malar  is  a  membrane-bone,  and  arises  from  two  and  occa- 
sionally three  centres,  which  appear  in  the  eighth  week  of  embryonic  life,  and 
grow  with  astonishing  rapidity:  the  bone  quickly  attains  a  relatively  large  size. 

Occasionally  the  two  primary  nuclei  fail  to  coalesce,  and  the  bone  is  represented 
in  the  adult  by  two  portions  separated  by  a  horizontal  suture.  Such  bipartite 
malars  have  been  observed  in  skulls  obtained  from  at  least  a  dozen  different  races 
of  men.  Bipartite  malars  have  been  seen  with  the  suture  vertical.  That  the  bone 
may  arise  from  three  centres  is  shown  by  the  fact  that  tripartite  malars  have  been 
observed. 

At  birth  the  maxillary  process  reaches  as  far  forwards  as  the  outer  Ixu-der  of  the 
infraorbital  canal;  subsequently  it  may  send  a  process  over  the  canal. 


TRE  APPENDICULAR  ELEMENTS  OF  THE  SKULL 

The  bones  which  form  this  group  are  the  mandible  (lower  jaw),  malleus,  incus, 
stapes,  hyoid,  the  styloid  process  of  the  temporal  bone,  and  the  internal  pterygoid 
process  of  the  sphenoid. 


THE  MANDIBLE  OR  LOWER  JAW 

The  mandible  (lower  jaio  or  inferior  maxilla)  is  in  shape  like  a  horseshoe;  it  con- 
sists of  a  horizontal  portion  or  body,  and  two  vertical  portions  or  rami. 

The  body  consists  of  a  right  and  a  left  half,  meeting  in  the  middle  line  to  form 
the  symphysis.  Each  lialf  presents  two  surfaces  and  two  borders.  The  external 
surface  is  smooth  and  generally  convex,  and  presents  the  following  points  of 
interest: — The  symphysis  ends  inferiorly  in  a  triangular  surface  which  forms  the 
chin.  Near  the  symphysis  is  the  incisive  fossa,  from  which  the  levator  menti 
arises;  external  to  this  is  the  mental  foramen  through  which  the  mental  nerve 
and  artery  issue.  This  foramen  is  in  a  line  with  the  second  bicuspid  tooth.  Ex- 
tending backwards  and  u})wards  from  the  mental  protuberance,  so  as  to  become 
continuous  with  the  anterior  border  of  the  coronoid  process,  is  the  external  oblique 
line  ;  along  its  up])er  l)order  the  depressor  lahii  infcrloris  and  depressor  anguli  oris 
arise.  The  internal  surface  presents,  at  a  point  corresponding  to  the  symphysis, 
two  ])airs  of  genial  tubercles.  The  upper  pair  give  origin  to  the  genio-hi/o-glossi, 
and  the  lower  ])air  afford  insertion  to  the  r/enio-hyoid  nmscles.  The  tubercles  occa- 
sionally form  a  single,    median,    irregularly    shaped  eminence.      By    the    side   of 


THE  MANDIBLE 


63 


the  licnial  tubercles  there  is  a  shallow  smooth  depression,  the  sublingual  fossa ; 
below  this  is  the  digastric  fossa  for  the  insertion  of  the  anterior  l)elly  of  the  diiias- 
tric  muscle.  Posterior  to  the  genial  tubercles,  the  internal  oblique  line  (mylo- 
hyoid ridge)  commences  and  extends  backwards,  becoming  more  and  more  promi- 
nent as  it  approaches  the  alveolar  border.  The  mylo-hyoid  muscle  arises  along  the 
whole  length  of  this  ridge.  At  the  posterior  part  the  mperior  constrictor  takes  origin, 
and  the  pterygo-maxillary  ligament  is  attached  to  its  posterior  extremity.  Below 
the  internal  oblique  line  is  the  submaxillary  fossa,  which  is  in  n'lation  with  the 
su  bm  axilla  ry  gla  n  d . 

The  inferior  border  of  the  body  of  the  mandible  is  smooth  and  rounded;  in  the 
anterior  part  of  its  extent  it  gives  attachment  to  the  platysma;  near  its  junction  with 
the  ramus  there  is  a  groove  for  the  facial  artery.  The  superior  border  is  comjjosed 
of  spongy  bone,  and  is  named  the  alveolar  process;  it  presents  sockets  or  alveoli 
for  eight  teeth.  From  the  external  surface  of  the  alveolar  process,  as  far  forwards 
as  the  first  molar  tooth,  the  buccinator  muscle  takes  origin. 


Fig.  73.— The  Mandible.     (Outer  view.) 

Temporal        CORONOID  PROCESS        SIGMOID  NOTCH     External  pterygoid 


CONDYLE 
NECK 

Capsular 
/  ■/  and 

* '        External 
'  lateral 

/  ligament 


THE  CHIN  OR 
MENTAL  PRO- 
TUBERANCE 


Platysma 


Depressor  anguli  oris 

EXTERNAL  OBLIQUE  LINE 


GROOVE  FOR  FACIAL  ARTERY 


The  ramus  is  quadrilateral  in  shape.  It  has  two  surfaces,  four  l)orders,  and 
two  processes.  The  external  surface  is  for  the  insertion  of  the  nin.^sseter  muscle. 
The  internal  surface  presents  near  its  middle  the  mandibular  (inferior  dental) 
foramen  which  leads  into  the  mandibular  (inferior  dental)  canal  which  traverses 
the  body  of  the  bone  and  emerges  at  the  mental  foramen.  This  canal  ])resents  a 
series  of  fine  apertures  above,  through  which  filaments  of  the  mandibular  nerve 
and  artery  pass  to  the  teeth.  In  its  posterior  two-thirds,  the  canal  is  nearer  the 
internal,  in  its  anterior  third,  it  is  nearer  the  external  surface  of  the  mandil)le.  The 
posterior  orifice  of  the  canal  is  surmounted  by  the  mandibular  spine  to  which  the 
spheno-mandibular  ligament  is  attached.  Running  ob]i(pioly  downwards  behind 
this  spine  is  the  mylo-hyoid  groove,  which  lodges  the  mylo-hyoid  nerve  and 
artery.  In  the  embryo,  ^Sleckel's  cartilage  also  occujjies  the  groove.  The  triangular 
rough  space  behind  this  groove  is  for  the  insertion  of  the  internal  pterygoid  muscle. 

The  inferior  border  of  the  ramus  is  thick,  rounded,  and  continuous  with  the 
lower  liorder  of  the  body  of  the  bone.  The  posterior  l)order  is  roundi^l:  to  its 
lower  part  the  stylo-mandibular  ligament  is  attached.     This  border  is  surmounted 


(-.4 


THE  SKELETON 


l>v  tlK'  condyle,  whieh  is  connected  with  tlic  ninius  liy  a  somewhat  constricted 
portion,  the  neck. 

The  condyle  is  oval  in  shape,  Avith  its  long  axis  transverse  to  the  upper  l)order 
of  the  ramus,  but  oblique  with  regard  to  the  median  axis  of  the  skull,  so  that  the 
outer  is  more  anterior  than  the  inner  angle,  and  presents  the  condyloid  tubercle 
for  the  external  lateral  ligament  of  the  temporo-mandibular  articulation.  The 
(X)nvex  surface  of  the  condyle  is  covered  with  cartilage  and  rests  in  the  glenoid 
fossa;  the  neck  is  flattened  in  fntnt  and  presents  a  pit,  for  the  insertion  of  a  portion 
of  the  external  ptcri/fiaid  muscle.  The  superior  border  of  tlie  ramus  is  known  as  the 
sigmoid  notch ;  it  is  terminated  anteriorly  by  the  coronoid  process.  This  is  a 
})t)inted  process  with  two  borders  and  two  surfaces;  the  inner  surface  presents  a 
ridge,  commencing  at  the  tip,  and  becoming  continuous  with  the  inner  edge  of 
the  alveolus.  To  this  ridge,  to  the  area  of  bone  in  front  of  it  and  the  tip  of  the 
coronoid  process,  the  temporal  muscle  is  inserted;  its  outer  surface  affords  attachment 
to  the  masseter  and  a  few  fibres  of  the  temporal.  The  anterior  border  of  the  ramus 
is  continuous  with  the  external  oblique  line  on  the  body  of  the  bone. 

Blood-supply. — The  mandible  is  very  vascular,  and  receives  a  large  supply 


Fig.  74. — The  Mandible.     (Inuer  view.) 


External 
pterygoid 


Capsule 


MANDIBULAR 
SPINE 

MANDIBULAR 

FORAMEN 

Spheno-mandi- 

bular  ligament 

Superior 

constrictor 

Mylo-hyoid 

groove 

Internal 
pterygoid 

Stylo- 
mandibular 
ligament 


GROOVE  FOR  SUB- 
LINGUAL GLAND 
Genio-hyo- 

'^  I       glossus 

Genio-hyoid 


Mylo-hyoid 

INTERNAL  OBLIQUE  LINE 


GROOVE  FOR  SUBMAXILLARY  GLAND 


from  the  mandibular  branch  of  the  internal  maxillary  artery.     This  constitutes  its 
main  supply.      It  receives  twigs  also  from  the  faciid  artery. 
It  gives  attachment  to  the  following  muscles  : — 


Buccinator. 

Depressor  labii  inferioris. 

Depressor  anguli  oris. 

Levator  menti. 

Genio-hyo-glossus. 

Superior  constrictor  of  pharynx. 

Masseter. 

Orbiculari.' 


Internal  pterygoid. 

External  pterygoid. 

Platysma  myoides. 

(lenio-hyoid. 

Mylo-hyoid. 

Digastric. 

Temporal. 


Ossification. — The  mandil»le  has  six  ]t(>ints  of  ossification  for  each  lateral  half. 
All  these,  with  the  exception  of  one,  are  deposited  in  memlirane.  The  nuclei  are 
deposited  very  early  (between  the  sixth  and  eighth  week),  and  fuse  so  rapidly  that 
observations  on  the  development  of  this  bone  are  unusually  difficult. 


THE  MAMJIBLE 


65 


Its  six  ('cntrcs  are  mainly  named  according  to  their  jjosition. 

The  mento-Meckelian. — This  is  deposited  in  the  distal  end  rif  Meckel's 
(mandibular)  cartilage,  and  gives  rise  to  that  portion  of  the  bone  Ijetween  the 
symphysis  and  the  mental  foramen. 

The  dentary. — This  forms  the  lower  border  and  outer  plate,  and  supports  the 
teetli.  hence  its  name. 

Fk;.  7."). — The  Mani>ii{i,k  at  Birth. 


OUTER   VIEW 


INNER   VIEW 


The  coronoid. — This  gives  rise  to  the  process  of  that  name. 
The  condyloid. — This  forms  the  condyle  and  adjacent  portion  of  the  neck  nf 
the  bone. 

The  angular. — This  gives  rise  to  the  angle  of  the  bone. 

The  splenial. — This  centre  appears  three  weeks  later  than  the  portions  already 

Fig.  76. — The  Skull  of  ax  Old  Woman  Eighty-three  Years  Old.  to  show  the 
Changes  in  the  Mandible  and  Maxilla. 


mentioned.  It  forms  the  inner  plate  of  the  mandible  from  near  the  symphysis  to 
the  mandilnilar  foramen.  The  mandibular  spine  represents  the  posterior  extremity 
of  the  splenial.  Its  line  of  junction  with  the  dentary  is  indicated  in  the  adult  bone 
by  the  mylo-hyoid  groove. 

At  birth  the  mandible  is  represented  bv  two  nearly  horizontal  troughs  of  bone 
5 


66  THE  SKELETON 

lodging  unerupted  teeth.  Eaoli  half  is  joined  at  the  symphysis  by  fibrous  tissue. 
The  upi)er  eclge  of  the  symphysis  and  the  condyles  are  nearly  on  a  level.  The 
mandiV)ular  nerve  lies  in  a  shallow  groove  between  the  dentary  and  splenial  plates. 
During  the  first  year  the  two  halves  ankylose,  union  taking  place  from  below 
upwards,  but  the  ankylosis  is  not  complete  until  the  second  year.  After  the  first 
dentition,  the  ranuis  forms  with  the  l)ody  of  the  mandible  an  angle  of  al)out  140°, 
and  the  mental  foramen  is  situated  midway  between  the  upper  and  lower  l)ordi'rs 
of  the  bone  opposite  the  second  milk-molar.  In  the  adult,  the  angle  formed  by  the 
ramus  and  body  is  nearly  a  right  angle,  and  the  mental  foramen  is  opposite  the 
second  bicuspid,  so  that  its  relative  position  remains  unaltered  after  the  first  denti- 
tion. In  old  age,  after  the  fall  of  the  teeth,  the  alveolar  margin  is  absorbed,  the 
angle  formed  by  the  ramus  and  body  becomes  obtuse,  and  the  mental  foramen 
approaches  the  alveolar  margin.  In  a  young  and  vigorous  adult  the  mandible 
is,  with  the  exception  of  the  petrosal,  the  densest  boiie  in  the  skeleton,  and  resists 
decay  longest;  in  old  age  it  becomes  exceedingly  porous,  and  often  so  soft  tliat  it 
may  be  broken  easily. 


THE  HYOID,  THE  STYLOID   PROCESS,  AND   THE  EAR-BOXES 

The  hyoid  or  lingual  bone  consists  of  a  body  and  four  processes.  The  body 
(basi-hyal)  forms  the  central  portion  of  the  bone;  it  is  somewhat  oblong  in  shape. 
Its  anterior  aspect  is  convex  and  divided  by  a  transverse  ridge  into  a  suj)eri()r 
and  an  inferiijr  portion.      Frequently  it  presents  a  median  vertical  ridge,  and  at  tlie 

Fig.  77. — Thk  Hvoin. 

GREATER  CORNU 


lESSER  CORNU 


point  where  the  horizontal  and  vertical  ridges  intersect,  a  tubercle,  sometimes 
measuring  four  millimetres  in  length,  is  formed.  The  whole  of  the  anterior  surface 
is  crowded  with  the  origin  and  insertions  of  muscles.  The  posterior  surfacic  is 
deeply  concave. 

The  inferior  border  is  free,  the  superior  gives  attachment  to  the  thyro-hyoid 
membrane.  Between  this  membrane  and  the  concavity  of  the  hyoid  there  is  a 
large  bursa.  The  lateral  borders  are  in  relation  with  the  greater  (•ornua,  but 
remain  separated  from  them  until  late  in  life. 

The  greater  cornua  (thyro-hyals)  i)roject  backwards  and  ui)wards.  Their 
upper  and  lower  borders  and  anterior  surfaces  are  occupied  with  muscles.  Each 
corner  terminates  posteriorly  in  a  rounded  tubercle,  to  which  the  thyro-hyoid 
ligament  is  attached. 

The  lesser  cornua  (cerato-hyals)  are  small  conical  pieces  of  bone  occupying 
the  upper  ])art  of  the  suture  between  the  body  and  the  greater  cormia.  Their  tips 
are  continuous  with  the  stylo-hyoid  ligaments. 

Muscles  attached  to  the  hyoid  bone  : — 

Lingualis.  Digastric.  INIylo-hyoid. 

Genio-hyo-glossus.  Genio-hyoid.  Hyo-glossus. 

Middle  constrictor.  Thyro-hy<Md.  Hyo-epiglottideus 

Sterno-hyoid.  Omo-hyoid.  (when  present). 


IIYOW   BOXE  AM)   STYLOID   PROCESS  67 

Ligaments  : — 

Tliyro-hyoid.  Stylo-hyoid;  and  the  thyro-hyoid  membrane. 

Blood-supply. — The  hyoid  receives  twifrs  from  the  arti'rics  supplying  the 
n)uscles  attached  to  it,  in  addition  to  direct  supply  from  the  superior  thyroid  and 
linjfual  art<Tics. 

Ossification. — At  the  third  month  the  hyoid  consists  of  hyaline  cartilage;  it 
is  directly  continuous  with  the  styloid  process.  In  the  fourth  month,  a  nucleus 
aj)i)ears  on  each  side  of  the  middle  line;  they  become  quickly  confluent  to  form  the 
l)ody  of  the  bone.  In  the  fifth  month  each  greater  cornu  has  a  conspicuous 
nucleus.     The  centres  for  the  lesser  cornua  are  delayed  until  the  second  year. 

The  greater  cornua  remain  separate  from  the  body  until  after  middle  life.  The 
lesser  cornua  rarely  ankylose  with  the  body  of  the  bone.  As  a  rule,  they  are  small 
and  inconsi)ieuous;  occasionally  they  are  very  long,  and  are  sometimes  continuous 
with  tlie  styloid  i)rocess  of  their  respective  sides. 

The  styloid  process  is  a  thin  cyHndrical  spike  of  bone  wedged  in  between  the 
tympanic  plate  and  the  petrosal  immediately  anterior  to  the  stylo-mastoid  foramen. 
It  consists  of  two  parts:  a  tympano-hyal  segment  which  in  the  adult  is  hidden 
behind  the  tympanic  plate,  and  a  free  projecting  portion  of  variable  length.  As  a 
rule  it  varies  from  five  to  fifty  millimetres.  When  short  it  is  hidden  by  the  vaginal 
process,  but  it  may  reach  to  the  hyoid  bone.  Its  base  forms  the  anterior  boundary 
of  the  stylo-mastoid  foramen.  The  free  portion  gives  origin  to  the  following 
muscles:  The  stijlo-phnryngeits  arises  from  the  base  posteriorly;  the  stylo-hyoid  from 
the  outer  aspect  near  the  middle;  and  the  stylo-glossus  from  the  front  near  the  tip. 
The  extremity  of  the  process  is  continuous  with  the  stylo-hyoid  ligament.  A  band 
of  fibrous  tissue — the  stylo-mandibular  ligament — passes  from  the  process  below 
the  origin  of  the  stylo-glossus  to  the  angle  of  the  mandible. 

Muscles  attached  to  the  styloid  process  : —  Ligaments  : — 

Stylo-glossus.  Stylo-hyoid . 

Stylo-hyoid.  Stylo-mandi  bu  la  r. 

Stylo-pharyngeus. 

The  morphology  and  development  of  this  process  are  described  on  })ag('  90. 

The  malleus. — This  is  the  most  external  of  the  auditory  ossicles,  and  comes 
in  relation  with  the  tymj^anic  membrane.  Its  upper  portion,  or  head,  is  lodged  in 
the  attic  of  the  tympanum.  It  is  of  rounded  shape,  and  presents  posteriorly  an 
elliptical  depression  for  articulation  with  the  incus.  Below  the  head  is  a  constricted 
portion  or  neck.  From  beneath  the  neck  three  processes  diverge.  The  largest  is 
the  handle  or  manubrium,  Avhich  is  slightly  twisted  and  flattened.  It  forms  an 
obtuse  angle  with  the  head  of  the  bone,  and  lies  between  the  membrana  tympani 
and  the  mucous  membrane  covering  its  inner  surface. 

The  tensor  tympani  tendon  is  inserted  into  the  manubrium  near  its  junction  Mith 
the  neck  on  the  inner  side.  The  slender  process  (gracilis  or  Folian)  is  a  long, 
slender,  delicate  spiculum  of  bone  (rarely  seen  of  full  length  except  in  the  foetus), 
projecting  nearly  at  riglit  angles  to  the  anterior  aspect  of  the  neck,  and  extending 
obli({uely  downwards.  It  lies  in  the  Glaserian  fissure,  and  in  the  adult  usually 
l)ecomes  converted  into  connective  tissue,  except  a  small  basal  stump.  The  short 
process  is  a  conical  projection  from  the  outer  aspect  of  the  base  of  the  manubrium. 
Its  apex  is  connected  to  the  upper  part  of  the  tympanic  memln'ane,  and  its  base 
receives  the  external  ligament  of  the  malleus.  The  malleus  also  gives  attachment 
to  the  suspensory  ligament,  and  to  the  long  anterior  ligament  of  the  malleus  which 
Avas  formerly  descrilied  as  the  laxator  tympani  muscle. 

The  incus. — This  bone  is  situated  between  the  malleus  externally,  and  the 
stapes  internally.  It  presents  for  examination  a  body  and  two  processes.  The 
body  is  deeply  excavated  anteriorly  for  the  reception  of  the  head  of  the  malleus. 
The  short  process  projects  backwards,  and  is  connected  by  means  of  ligamentous 
fibres  to  the  posterior  wall  of  the  tympanum,  near  the  entrance  to  the  mastoid 
antrum.     The  long  process  is  slender,  and  directed  downwards  and  inwards;  it 


6S 


THE  SKELETON 


lic'^  paralkl  Avith  tlie  handle  of  the  malleus.  On  the  inner  aspect  of  the  distal 
t'xt remit V  of  this  i)rocess  is  the  orbicular  tubercle,  connected  with  the  process  by 
a'  narrow  neck.  Its  free  surface  articulates  with  the  head  of  the  stapes.  The 
orbicular  tubercle  is  separate  in  early  life.  ^    i-      .   i  ,      •       ,  ^^ 

The  stapes  is  the  innermost  ossicle.  It  has  a  head  directed  horizontally  out- 
wards ca]n)ed  at  its  outer  extremitv  by  a  disc  resembling  the  head  of  the  radius. 
Tiie  cup-sliaped  depression  receives  the  orbicular  tubercle  of  the  incus.     The  base 

Fig.  78.— The  Bones  of  the  Eak.     (Modified  from  Henle.) 


LEFT   MALLEUS 


FOSSA  FOR  INCUS 


HEAD  OF  MALLEUS 


SHORT  PROCESS 
SLENDER  PROCESS 


HANDLE  OR  MANUBRIUM 


LEFT   INCUS 


SHORT  PROCESS 


ANTERIOR  CRUS 


POSTERIOR  CRUS 


—  ARTICULAR  SURFACE  FOR  MALLEUS 


ORBICULAR  TUBERCLE 


BASE  OF  STAPES 


occupies  the  fenestra  ovalis,  and  like  this  opening  the  inferior  border  is  straight, 
and  the  superior  curved.  The  base  is  connected  with  the  head  by  means  of  two 
crura,  and  a  narrow  i)icce  of  bone  called  the  neck.  Of  the  two  crura,  the  anterior 
is  th(!  shorter  and  straigliter.  The  crura  with  the  base  form  a,  stirrup-shaped  arch, 
of  whicli  tlic  inner  margin  presents  a  groove  for  the  reception  of  the  membrane 
which  is  stretched  across  tlie  hollow  of  the  stapes.  In  the  early  endiryo  this  hollow 
is  traversed  by  tlie  stapedial  artery.  The  neck  is  very  short,  and  receives  on  its 
posterior  border  tlie  tendon  of  the  stapedius  muscle. 


THE  EXTERIOR  OF  THE  SKULL 


69 


THE  EXTERIOR  OF  THE  SKULL 

The  skull,  when  viewed  from  above,  presents  an  oval  outline;  the  posterior  part  is 
broader  than  the  anterior.  The  bones  seen  in  this  view  are  the  frontal,  parietals, 
and  the  interparietal  portion  of  the  occipital.  In  a  skull  of  average  width  the 
zygomata  come  into  view,  but  in  very  broad  skulls  they  are  obscured. 

The  sutures  of  the  vertex  are: — 

The  metopic,  which  is,  in  most  skulls,  merely  a  median  fissure  in  the  frontal 
bone  just  above  the  glabella ;  occasionally  it  involves  the  whole  length  of  the  bone. 
It  is  due  to  the  persistence  of  the  fissure  normally  separating  the  two  halves  of  tlie 
bone  in  the  infant: 

Fig.  79. — The  Skull.     (Norma  lateralis.) 


The  sagittal  is  situated  between  the  two  parietals,  and  extends  from  the  bregina 
to  the  lambda. 

The  coronal  lies  between  the  frontal  and  parietals,  and  extends  from  pterion  to 
pterion. 

The  lambdoid  is  formed  by  the  parietals  and  interparietal  portion  of  the  occi- 
pital.    It  extends  from  asterion  to  asterion. 

The  occipital  suture  is  only  present  when  the  interparietal  exists  as  a  separate 
element  (fig.  35 ). 

The  more  important  regions  are: — 

The  bregma,  which  indicates  the  situation  of  the  anterior  fontanelle,  and 
marks  the  confluence  of  the  coronal,  the  sagittal,  and,  when  present,  the  metopic 
sutures. 

The  lambda,  where  the  sagittal  enters  the  lambdoid  suture;  it  marks  the  situa- 
tion of  the  posterior  fontanelle. 


70  THE  SKELETON  ■ 

The  obelion,  a  little  anterior  to  the  lambda,  is  usually  indicated  by  a  median 
or  two  lateral  foramina.  It  indicates  the  spot  where  the  sagittal  suture  first  suffers 
obliteration. 

Vieued  from  hihind,  the  skull  appears  irregularly  globular;  the  inferior  part  of 
its  circumference  being  somewhat  flattened.  The  limits  of  the  flattened  portion 
are  indicated  bv  the  mastoid  jirocesses. 

The  centre  is  occui)ied  by  the  occipital  protuberance  ;  this,  with  the  occipital 
crest  and  the  three  ijairs  of  nuchal  lines,  give  to  the  lower  half  a  xX)ugh  and  uneven 
ajipearance.  The  sutures  in  this  view  are  the  terminations  of  the  sagittal,  lamb- 
doi(hd  and,  wht-n  itnsent,  the  occipital  suture. 

Tlie  occipital  point  (fig.  90j  is  the  most  posterior  part  of  the  skull,  and  is 
exactly  oi)posite  the  o})hryon. 

The  inion  corresponds  to  the  external  occipital  protuberance. 

The  lateral  a>>pect  of  the  skull  is  very  uneven;  it  presents  three  recesses  or  fossae. 
Its  irregularity  is  increased  by  the  zygoma. 

The  temporal  fossa,  semilunar  in  shape,  is  limited  above  by  the  superior 
temporal  ridgf,  and  below  by  the  zygoma. 

The  temporal  ridge  begins  at  the  external  angular  process  of  the  frontal  bone, 
and  curves  upwards  and  backwards  to  cross  the  frontal  and  parietal  bones;  it  then 
descends  along  the  mastoid  portion  of  the  temporal  bone  to  become  continuous 
with  the  upper  border  of  the  zygoma.  In  many  skulls  this  ridge  is  double.  The 
lower  ridge  gives  origin  to  the  temporal  muscle.  The  upper  is  the  least  constant; 
it  diverges  from  the  lower  ridge  as  it  approaches  the  coronal  suture.  At  the  middle 
of  the  parietal  bone  the  two  ridges  are  often  ten  millimetres  apart.  This  ridge  gives 
attachment  to  the  temporal  fascia.  The  fossa  is  almost  entirely  occupied  by  the 
temporal  muscle. 

The  zygomatic  fossa  is  limited  anteriorly  by  the  zygomatic  surface  of  the 
maxilla;  internally  liy  the  external  pterygoid  plate;  externally  by  the  zygomatic 
arch  and  the  rannis  of  the  mandible;  and  posteriorly  by  a  line  drawn  from  the 
foramen  spinosum  to  the  zygomatic  tubercle.  The  outer  surface  of  the  greater 
wing  of  the  sphenoid  internal  to  the  pterygoid  ridge  and  a  small  piece  of  the 
s(|uamosal  form  part  of  the  upper  boundary  of  the  fossa. 

The  chief  objects  of  interest  in  this  region  are: — The  spheno-maxillary  and 
pterygo-maxillary  fissures,  the  pterygoid  ridge  on  the  sphenoidal  wing,  the 
foramen  ovale,  foramen  spinosum,  and  the  articular  eminence  of  the 
scjuamosal. 

The  spheno-maxillary  fissure  is  horizontal  in  position,  and  lies  between  the 
orbital  border  of  tlie  maxilla  and  the  greater  wing  of  the  sphenoid;  externally  it  is 
completed  usually  by  the  malar;  freciuently  the  sphenoid  will  join  the  maxilla  and 
exclude  the  malar  bone  froiu  the  fissure;  internally  it  is  terminated  by  the  zygo- 
matic surface  of  the  orbital  i)roccss  of  the  palate  bone.  Through  this  fissure  the 
(trbital,  spheno-maxillary,  and  zygomatic  fossa?  communicate.  The  zygomatic  fossa 
lodges  the  temporcd,  external  pterygoid,  and  internal  pterygoid  muscles. 

The  pterygo-maxillary  fissure  forms  a  right  angle  with  the  preceding.  It  is 
situated  between  the  maxilla  and  the  anterior  border  of  the  pterygoid  process  of  the 
s]»henoid.  At  its  lower  angle  the  external  pterygoid  plate  occasionally  articulates 
with  theniaxilla.  The  pterygo-maxillary  fissure  leads  from  the  zygomatic  fossa 
directly  into  the  spheno-maxillary  fossa,  a  small  space  shaped  like  an  inverted 
jtyramid,  situated  l)etween  the  maxilla  and  the  roots  of  the  pterygoid  processes. 
The  roof  of  this  fossa  is  formed  by  the  under  surface  of  the  greater  wing  of  the 
s]»hen()i(l.  The  anterior  boundaries  are  a  small  portion  of  the  zygomatic  surface  of 
the  maxilla  and  the  orbital  process  of  the  palate;  posteriorlv  it  has  the  roots  of  the 
pterygoid  i>rocesses,  and  the  lower  part  of  the  orbital  surface  of  the  greater  wing  of 
the  sphenoid;  and  internally  the  vertical  ])late  of  the  palate  bone.  The  apex  of  the 
l)yramid  leads  into  the  posterior  palatine  canal.  The  inner  w\all  presents  the 
spheno-palatine  foramen  wliidi  leads  into  the  nasal  fossa.  The  ])osterior  wall 
has  three  o])enings  in  the  following  order,  from  without  inwards,  and  from  al)ove 
downwards:  the  foramen  rotundum,  Vidian  canal,  and  pterygo-palatine  canal. 
Anteriorly  it  communicates  with  the  orbit  by  the  spheno-maxillary  fissure; 
and  externally  the-  pterygo-maxillary  fissure  "leads  into  the  zvgomatic  fossa. 


THE  GLENOID   FOSSA 


71 


This  fossa  is  mainly  of  interest  on  account  of  its  relation  to  the  sphenopalatine 
(Meckel' sj  ganglion.  The  various  foramina  and  canals  connected  with  the  fossa 
serve  for  the  transmission  of  the  nerves  connected  with  this  ganglion  and  the 
terminal  l)ranches  of  the  internal  maxillary  artery. 

In  addition  to  the  fossae,  the  lateral  region  presents  the  glenoid  fossa  with  its 
articular  eminence,  the  external  auditory  meatus,  the  mastoid  and  styloid  processes, 
and  the  following  sutures: — 

The  spheno-parietal,  which  lies  between  the  greater  wing  of  the  sphenoid  and 
the  anterior  inferior  angle  of  the  parietal. 

The  squamous  is  formed  by  the  squamosal  overlapping  the  lower  border  of  the 
])arietal. 

The  parieto-mastoid,  which  lies  between  the  posterior  inferior  angle  of  the 
parietal  and  the  mastoid  portion  f»f  the  petrosal. 

Tlie  zygomatic  suture  is  formed  by  the  union  of  the  zygoma  with  the  malar  bone. 

The  squamo- sphenoidal  is  situated  between  the  anterior  border  of  the  squamo- 
sal and  the  greater  wing  of  the  sphenoid. 

The  spheno-malar  suture  is  formed  by  the  orVjital  process  of  the  malar  and  the 


Fig.  80.- 


-A  Sectiox  of  the  Skull,  showing  the  Inner  Wall  of  the  Okiut.  the  Inner 
Wall  of  the  Antrim,  and  the  Spheno-maxillary  Fossa. 


FRONTAL  S!NUS 


NASAL  BONE- 

NASAL  PROCESS  OF  MAXILLA 
LACHRYMAL 

LACHRYMAL  CANAL 

ORIFICE  OF  ANTRUM 

INFERIOR  TURBINAL 

PALATE  BONE 

ANTERIOR  NASAL  SPINE 


ANTERIOR  ETHMOID  CANAL 
POSTERIOR  ETHMOID  CANAL 


OPTIC  FORAMEN 

OS  PUNUM  OF  ETHMOID 


-4^  VIDIAN  CANAL.  LEADING  INTO  THE 
SPHENO-MAXILLARY  FOSSA 
SPHENOID 


/-  EXTERNAL  PTERYGOID  PLATE 
—  PALATE  BONE 


malar  ridge  on  the  greater  wing  of  the  sphenoid.  Near  its  middle  the  suture  is 
perforated  by  the  spheno-malar  foramen,  which  allows  the  temporal  branch  of 
the  orbital  nerve  and  a  branch  of  the  lachrymal  artery  to  escape  from  tlie  orl)it. 
This  foramen  in  some  adult  skulls  is  complete  in  the  malar. 

The  fronto-squamosal  is  an  occasional  suture;  when  it  is  present,  the  anterior 
inferior  angle  of  tlie  parietal  is  excluded  from  the  greater  wing  of  the  sphenoid. 

The  more  important  regions  are: — 

The  pterion,  which  marks  the  situation  of  the  anterior  lateral  fontanelle,  is 
the  meeting-place  of  the  coronal,  .squamous,  spheno-parietal,  squamo-sphenoidal, 
and  the  fronto-squamosal  sutures.  Freciuently  it  is  occuj)ied  in  the  adult  by  the 
epipteric  ossicle. 

Th(^  asterion  indicates  the  situation  of  the  posterior  lateral  fontanelle  and 
marks  the  confluence  of  the  squamosal,  parieto-mastoid.  lambdoid,  the  occipito- 
mastoid, and  occasionally  the  occipital  sutures.  Sometimes  it  is  occupied  l>y  a 
^\'ormian  bone. 

The  stephanion  is  the  spot  where  the  superior  temporal  ridge  cuts  the  coronal 
suture. 

The  auricular  {loint  is  the  centre  of  the  external  auditory  meatus. 


7> 


THE  SKELETOX 


The  BASE  OF  TiiF.  SKULL  is  Very  invjiular,  and  extends  from  the  ineisor  teeth  to  the 
occipital  {)rotuhcrance.  Laterally  it  is  limited  liy  the  zygomatic  arches.  Anteriorly 
it  presents  the  hard  i)alate.  \Mien  the  skull  is  inverted,  the  hard  j^alate  stands  at 
a  higher  level  than  the  rest;  it  is  bounded  anteriorly  and  laterally  l)y  the  alveolar 
ridges  containing  the  teeth.  The  bones  appearing  in  the  intermediate  space 
are  the  premaxillary  and  palatine  portions  of  the  maxillae,  and  the  horizontal 
plates  of  the  i^alate  "bones.  The  bone  is  rough  for  the  attachment  of  the  muco- 
perio.^teum.     The  following  points  are  readily  recognised  (fig.  81): — 

The  meso-palatine  suture  commences  at  the  alveolar  point,  traverses  the 
anterior  ]>alatinc  fossa,  and  terminates  at  the  posterior  nasal  spine. 

The  transverse  palatine  suture  between  the  palate  bones  and  palatine  processes 
of  the  maxillai. 

In  young  skulls  the  maxillo-premaxillary  sutures,  and  behind  the  incisor 
teeth  four  small  openings  known  as  the  gubernacular  canals. 

The  anterior  palatine  fossa  containing  the  termination  of  four  canals:  two 
small  orifices,  foramina  of  Scarpa,  situated  one  l)ehind  the  other  in  the  meso- 
palatine  suture;  and  two  larger  openings,  the  foramina  of  Stenson.  Scarpa's 
foramina  transmit  the  naso-palatine  nerves;  Stenson' s  are  in  relation  with  Jacob- 
son's  organs. 

At  the  posterior  angles  of  the  hard  palate  are  the  posterior  palatine  foramina, 


Fig.  81.— Hard  Palate  of  a  Child  Five  Years  Old. 


GUBERNACULAR  CANALS 


ANTERIOR  PALATINE   FOSSA 
MAXILLO-PREMAXILLARY   SUTURE 


PALATE  PROCESS  OF  MAXILLA 


.--  POSTERIOR  PALATINE  FORAMEN 
-  ACCESSORY  PALATINE  CANALS 


through  which  the  posterior  palatine  vessels  and  the  anterior  i)alatino  nerves 
emerge  on  to  the  palate;  a  thin  lip  of  bone  separates  them  from  the  accessory 
palatine  foramina  for  the  posterior  palatine  nerves.  The  accessory  foramina  are 
ill  tlic  tulxTdsity  of  the  ])alate  bone. 

The  hamular  process  of  the  internal  pterygoid  plate  is  the  most  posterior  limit 
of  the  hard  palate 

At  the  ])osterior  extremity  of  each  alveolar  ridge  is  the  tuberosity  of  the  maxilla. 
Between  the  tuberosities  of  the  maxilla  and  the  palate  bone  are  a  few  minute 
foramina  (varia])le  in  number  and  not  always  present),  the  external  palatine 
canals  for  tin;  external  palatine  nerves. 

Behind  the  hard  ])alatc  are  the  posterior  nares,  se]:)arated  from  each  other  liy 
the  vomer.  Eacli  is  bounded  externally  by  the  internal  pterygoid  plate;  below  by 
the  horizontal  ])late.  of  thc^  palate  bone";  above  by  the  under  surface  of  the  body 
of  the  sphenoid,  with  the  ala  of  the  vomer  and  a'i)ortion  of  the  sphenoidal  process 
of  the  ])alate  bone. 

E.xternal  to  the  nares  there  is  on  each  side  a  vertical  fossa  lying  betwcnui  the 
pterygoid  plates.  It  extends  u])wards  to  the  under  surface  of  the  greater  wings  of 
the  spluMioid;  it  is  completed  anteriorly  by  the  coalescence  of  the  pterygoid  i)lates, 
and  below  l)y  th(^  tul)erosity  of  the  palate  bone.  It  contains  the  following  points 
of  interest : — 


AXTERIOR  ASPECT  OF  THE  SKULL  73 

An  elongated  furrow,  tlic  scaphoid  fossa,  for  the  /^'//no/' j/^//*/// imisdc  ;iii<l  the 
cartilage  of  the  Eustachian  tul»('. 

The  general  cavity  of  the  pterygoid  fossa  which  lodges  the  ten'^or  palfifi  and 
iiiternal  jttcrj/f/oid  muscles. 

Frequently  there  is  a  notch  in  tlie  external  ])terygoid  plate  close  heside  the 
foramen  ovale. 

The  posterior  termination  of  the  Vidian  canal. 

If  a  line  he  drawn  across  the  skuU-hase  from  one  zygomatic  tuhercle  to  the 
other,  it  will  fall  immediately  behind  the  external  pterygoid  plate  and  bisect 
the  foramen  spinosum  on  each  side.  A  second  transverse  line,  drawn  across  the 
opisthion  or  posterior  margin  of  the  foramen  magnum,  will  fall  behind  the  mastoid 
j)rocesses.  The  space  between  these  imaginary  lines  may  be  called  the  sub-cranial 
region;  that  behind  the  second  line  the  sub-occipital  region.  In  addition  to  these 
there  is  a  lateral  space  anterior  to  the  first  line  known  as  the  zygomatic  region. 
Each  will  require  se})arate  consideration. 

The  SUB-CRANIAL  REGION  is  formed  by  the  following  bones: — In  the  centre,  the 
under  surface  of  the  bodies  of  the  sphenoid  and  occipital  l)ones.  Laterally,  the  pe- 
trosal, a  small  })iece  of  the  greater  wing  of  the  sphenoid  and  of  the  squamosal,  and 
part  of  the  ()ccii)ital.     It  i)resents  the  following  points  in  the  middle  line  for  stud}': — 

The  pharyngeal  tubercle. 

The  foramen  magnum  and  the  occipital  condyles.  The  most  anterior  point 
of  the  foramen  is  termed  the  basion,  and  the  most  posterior  point  the  opisthion. 

On  each  side  will  he  seen: — The  anterior  condyloid  foramen  for  tlie  hypo- 
glossal nerve  and  a  meningeal  l)ranch  of  the  ascending  pharyngeal  artery. 

The  posterior  condyloid  fossa  with  the  posterior  condyloid  foramen  (this 
foramen  is  not  constant). 

The  sphenotic  (middle  lacerated)  foramen  and  the  orifice  of  the  Vidian  canal. 

The  canalis  musculo-tubarius  for  the  tensor  tympani  muscle  and  Eustachian 
tul)e. 

The  carotid  canal. 

Aqueductus  cochleae,  or  ductus  perilymphaticus. 

The  jugular  foramen  and  fossa  for  the  glosso-pharyngeal,  vagus,  and  spinal 
accessory  nerves,  the  internal  jugular  vein,  and  a  meningeal  l)ranch  of  the  ascend- 
ing pharyngeal  artery. 

The  tympanic  canaliculus  for  Jacobson's  nerve.  (Tynqianic  of  glosso- 
pharyngeal. ) 

The  alar  spine  of  the  sphenoid;  this  is  sometimes  fifteen  millimetres  in  length. 

The  glenoid  fossa  with  the  Glaserian  fissure.  This  lodges  the  slender  pro- 
cess of  the  malleus,  the  tympanic  twig  of  the  internal  maxillary  artery.  A  small 
passage  l)eside  it,  the  canal  of  Huguier,  conducts  the  chorda  tympani  nerve  from 
the  tympanum. 

The  external  auditory  meatus. 

Tlie  auricular  fissure  for  the  tympanic  branch  of  the  vagus. 

The  tympanic  plate  and  vaginal  ])rocess. 

Tlie  styloid  process. 

The  stylo-mastoid  foramen  for  the  stylo-mastoid  artery  and  the  exit  of  the 
facial  nerve. 

The  mastoid  process  Avith  the  digastric  and  occipital  grooves. 

The  SUB-OCCIPITAL  REGION  presents  chiefly  muscular  ridges.  They  are  the 
superior,  middle,  and  inferior  nuchal  lines,  with  the  external  occipital  protuber- 
ance and  the  external  occipital  crest.  Behind  the  mastoid  process  is  an  opening 
of  varialile  size,  the  mastoid  foramen;  a  ])ranch  of  the  occipital  artery  enters,  and 
a  vein  from  tlie  lateral  sinus  issues  from  this  foramen. 

The  ANTERIOR  ASPECT  of  the  skull  is  oval  in  outline,  but  presents  a  very  irregular 
surface.  Its  U])per  portion,  or  forehead,  presents  the  frontal  eminences  and 
superciliary  ridges.  In  the  middle  line  is  the  prominence  formed  liy  tlie  nasal 
hones,  Avith  a  deep  pyramidal  recess,  the  orbits,  on  each  side.  Below  the  nasal 
bones  are  the  entrances  to  the  nasal  sinuses  and  the  various  recesses  connected 
with  them.  The  teeth  form  a  conspicuous  feature  in  this  view  of  the  skull,  the 
outline  of  which  is  completed  by  the  mandible. 


74 


THE  SKELETON 


Fig.  82. — The  Skill.     (Xorniii  basilaris.) 

■^ — Ti 


Masseter 


Tensor  palati 
Azygos  uvulae 

Superior  eonstrietor 

Internal  pterygoid 

Tensor  palati 

Tensor  tympani 
ywii.ii        '        Levator  palati 
L       ' — ffc —   Rectus  capitis  antieus  major 


Rectus  capitis  antieus  minor 


^'.~~     Anterior  common  ligament  of  spine 
y  ^—    Vertical  part  of  crucial  ligament 

Check  ligament 
Capsular  ligament 


Posterior  oeeiplto-atlantal  ligament 
Superior  oblique 

""'?rri       Rectus  capitis  posticus  major 
Rectus  capitis  posticus  minor 


Iiigamcntum  nuchse 
Trapezius 


EXTERIOR  OF  THE  SKULL 


75 


Fkj.  83. — The  Skull.     (Norma  basilaris.) 


SCARPA'S  FORAMEN f-i»   /i|((,7<  «l 

STENSON'S  FORAMEN Mm        yU^ 

SCARPA'S  FORAMEN 
ANTERIOR  PALATINE  FOSSA 


PALATINE  GROOVE 
POSTERIOR  PALATINE  FORAMEN 

SPINE  OF  THE  PALATE  BONE 
HAMULAR  PROCESS 


SPHENOIDAL  PROCESS  OF  PALATE 


SPHENOTIC  (MIDDLE  LACERATED) 
FORAMEN 


PHARYNGEAL  TUBERCLE !_'>    (j, 

CAROTID  CANAL 


TUBERCLE  FOR  CHECK  LIGAMENT 


POSTERIOR  CONDYLOID  FORAMEN 


EXTERNAL  OCCIPITAL  PROTUBERANCE 


EXTERNAL  OCCIPITAL  CREST U,,  <U  J>VJ 


76 


THE  SKELKTOX 


The  bones  visible  in  this  view  of  the  skull  are:  the  frontal,  nasals,  lachrymals, 
orbital  surfaces  of  the  lesser  and  the  greater  wings,  and  a  portion  of  the  body  of  the 
sphenoid,  the  ossa  plana  of  the  ethmoid,  and  the  orbital  })rocesses  of  the  palate 
bones,  the  malars,  maxilla?,  inferior  turljinals,  and  the  mandible. 

The  foramina  are:  the  supraorbital,  infraorbital,  optic,  temporal,  and  mental; 
the  lachrymal  duct;  the  malar  and  ethmoidal  canals;  and  the  spheno-maxillary 
and  sphenoidal  fissures. 

Tlic  orbits  are  tw(^  cavities  of  pyramidal  sha23e,  which  lodge  the  eyeball  and  its 


Fig.  84. — The  .Skull.     (Norma  facialis.) 


Zygomaticus 


Zygomaticus 
minor 


SURFACE  COVERED  8Y 
occipito-frontaiis 


Corrugator 
supereilii 


Teudo  oeuli 
Orbicularis 

palpebrarum 
Levator  labii  supe- 

rioris  alaeque  nasi 


Levator  labii 
superioris 


Levator  anguli  oris 
Compressor  naris 

Depressor  alae  nasi 
Orbicularis  oris 


associated  muscles,  nerves,  and  vessels.  The  apex  of  each  orbit  corresponds  to 
the  optic  foramen,  a  circular  orifice  which  transmits  the  optic  nerve  and  oph- 
thalmic artery.  The  base  looks  forwards  and  outAvards.  It  is  formed  by  the 
frontal  bone  al)ove,  the  nasal  process  of  the  maxilla  on  the  inner  side,  the  malar 
bone  externally,  and  below  ]>y  the  malar  and  bodv  of  the  maxilla.  The  following 
points  are  seen  around  the  base:— The  suture  between  the  external  angular  process 
of  the  frontal  bone  and  the  malar;  the  supraorbital  notch  (sometimes  a  complete 


THE  ORBITS 


77 


foramen);  and  the  suture  between  the  frontal  ])one  and  the  na.sal  process  of  the 
niaxilhi;  and  in  the  inferior  segment  of  the  eircumference  is  the  malo-maxillary 
suture.  Oeeasionally,  the  infraorl)ital  foramen  opens  by  a  narrow  fissure  into 
the  orbit. 

Tlie  roof  (.f  tlie  orl)it  is  formed  mainly  by  the  orbital  plate  of  the  frontal  bone, 
and  eom])l('ted  posteriorly  by  the  lesser  wing  of  the  sphenoid.  At  the  outer  angle 
it  presents  the  lachrymal  fossa  for  the  lachrymal  gland,  and  at  the  inner  angle  a 
depression  for  the  pulley  of  the  svperior  oblique  nuiscle. 


Fio.  Ho.— The  Skull.     (Norma  facialis.) 


SUPERCILIARY  RIDGE 


SUBNASAL  POINT 


CANINE  EMINENCE 
ALVEOLAR  POINT  . 


I 


The  floor  is  formed  by  the  orbital  plate  of  the  maxilla,  the  orbital  process  of 
the  malar,  and  the  orbital  process  of  the  palate  bone.  At  its  inner  angle  it  presents 
the  lachrymal  canal,  and  near  this  a  depression  for  the  origin  of  the  inferior  oblique 
muscle.  The  floor  has  a  furrow  for  the  infraorbital  artery  and  the  second  division 
of  the  fifth  nerve.  The  furrow  terminates  anteriorly  in  the  infraorbital  canal, 
through  which  the  infraorbital  nerve  and  artery  emerge  on  the  face.  Near  the 
commencement  of  the  canal  a  narrow  passage,  the  anterior  dental  canal,  runs  for- 


78 


THE  SKELETOX 


wards  and  downwards  in  the  anterior  wall  of  the  antrum;  it  conducts  nerves  to 
the  incisor  and  canine  teeth. 

The  outer  wall  is  very  oblique;  it  is  formed  by  the  orl)ital  surface  of  the  greater 
wing  of  the  splicnoid,  and  the  malar.  Between  it  and  the  roof,  near  the  apex,  is 
the  sphenoidal  fissure,  by  means  of  which  the  third,  fourth,  ophthalmic  division 
of  the  tifth,  and  sixth  nerves  enter  the  orbit  from  the  cranial  cavity.  The  lower 
margin  of  the  fissure  presents  near  the  middle  a  small  tubercle,  from  which  One 
head  of  the  external  rectus  muscle  arises.  Between  the  outer  wall  and  the  floor, 
near  the  apex,  is  the  spheno-maxillary  fissure,  which  alloAvs  the  second  division  of 
the  fifth  nerve  to  enter  the  infraorbital  groove  from  the  spheno-maxillary  fossa. 
At  the  anterior  margin  of  the  fissure,  the  sphenoidal  wing  occasionally  articulates 
witli  the  maxilla,  but  frefjuently  it  is  excluded  by  the  malar.  In  front  of  the  anterior 
extremity  of  this  fissure  is  the  orbital  orifice  of  the  malar  canal.  Near  the  outer 
extremity  of  the  sphenoidal  fissure  a  few^  small  foramina  may  be  seen,  especially 
in  old  skulls,  which  allow  branches  of  the  middle  meningeal  artery  to  creep  into 
the  orbit.  A  vertical  fissure,  the  spheno-malar,  traverses  the  outer  wall.  It  con- 
tains the  very  small  spheno-malar  foramen,  which  allows  the  temporal  branch  of 

Fig.  86. — The  Ixxer  Wai.i.  of  the  Orbit. 


FRONTAL  SINUS 


NASAL  PROCESS  OF  MAXILU 
LACHRYMAL 

UCHRYMAL  CANAL 

ORIFICE  OF  ANTRUM 

INFERIOR  TURBINAL 

PALATE  BONE 

ANTERIOR  NASAL  SPINE 


ANTERIOR  ETHMOID  CANAL 
[•OSTERIOR  ETHMOID  CANAL 


OPTIC  FORAMEN 

OS  PLANUM  OF  ETHMOID 


^t-   -fi+-   SPHENO-PALATINE  FORAMEN 
-\— 4-  VIDIAN  CANAL,  LEADING  INTO  THE 
l>-  SPHENO-MAXILLARY  FOSSA 

SPHENOID 


EXTERNAL  PTERYGOID  PLATE 


—     PALATE  BONE 


the  orbital  nerve  to  escape  from  the  orljit.  This  foramen  is  sometimes  confined  to 
the  malar  Ixmc 

The  inner  wall,  narrow  and  straight,  is  formed  by  the  lachrymal,  os  planum 
of  the  ethmoid,  and  a  part  of  the  body  of  the  sphenoid.  The  ethmoid  section  of 
the  transverse  suture  contains  the  orifices  of  the  anterior  and  posterior  ethmoidal 
canals:  the  former  transmits  the  nasal  nerve  and  anterior  ethmoidal  artery;  the 
latter  the  posterior  ethmoidal  artery,  and  a  branch  of  the  nasal  nerve. 

Anteriorly  is  the  lachrymal  groove,  and  behind  this  the  crest  which  gives  origin 
to  the  tensor  tarsi.  This  wall  has  three  vertical  sutures:  one  between  the  nasal 
process  of  the  maxilla  and  the  lachrymal,  the  ethmo-lachrymal,  and  one  between 
the  OS  planum  and  ])ody  of  the  sphenoid.  Occasionally  the  sphenoidal  turbinal 
bone  appears  in^  the  orl)it  between  the  os  planum  of  the"  ethmoid  and  the  body  of 
the  sphenoid  (fig.  64). 

The  orbit  communicates  with  the  cranial  cavity  })y  the  optic  foramen  and  sphe- 
noidal fissure;  with  the  nasal  fossa  by  means  of  the  lachrvmal  duct;  with  the  zygo- 
matic and  spheno-maxillary  fossffi  "by  way  of  the  spheiio-maxillarv  fissure.  ^  In 
addition  to  these  large  openings,  the  orbit  has  five  other  foramina— the  infra-orbital, 
malar,  si)heno-malar,  and  the  anterior  and  posterior  ethmoidal  canals — opening  into 
it  or  lea-ding  from  it. 


THE  NASAL  FOSS.E  79 

In  old  skulls  the  frontal  sinuses  occasionally  extend  into  that  ])ortion  of  the 
horizontal  plate  of  the  frontal  bone  which  forms  the  roof  of  the  orbit. 

The  following  muscles  arise  within  the  orbit : — the  four  recti,  the  mperior 
oblique,  and  levator  palpebrx  svperioris,  near  the  apex;  the  inferior  oblique  on  the 
floor  of  the  orbit  external  to  the  lachrymal  canal;  and  the  tensor  tarsi  from  the 
lachrymal  crest.  The  margins  of  the  s])heno-maxillary  fissure  give  attachment  to 
the  orbit alis  muscle  (see  section  on  the  Eye). 

The  nasal  fossae  or  sinuses  are  two  irregular  cavities  situated  on  each  side  of 
a  median  vertical  septum,  extending  from  the  anterior  part  of  the  skull-base  to  the 
superior  surface  of  the  hard  palate.  They  are  somewhat  oblong  in  section,  but  are 
narrower  above  than  below. 

Each  fossa  presents  a  roof,  floor,  imier  and  outer  wall,  and  opens  in  front  Ijy 
the  anterior  naris,  and  communicates  behind  with  the  pharynx  Ijy  the  posterior 
naris. 

The  roof  resembles  that  of  a  house  with  two  sloping  edges  and  an  intermediate 
level  portion.  The  anterior  slope  is  formed  by  the  posterior  surface  of  the  nasal 
bone  and  the  nasal  spine  of  the  frontal.  ■  The  horizontal  portion  corresponds  to  the 
cribriform  plate  of  the  ethmoid  and  the  sphenoidal  turbinal.     The  posterior  slope 

Fig.  87. — Section  through  the  Nasal  Fossa  to  show  the  Septum.    Left  Half,  with 
Septum  looking  towards  Right  Nasal  Fossa. 


CREST  OF  SPHENOID    "^r   J  ' 'A^  ^^^Pf*^^^  *  "^^X      '  NASAL  SPINE  OF  FRONTAL 


GROOVE  FOR  NASAL  NERVE  iV^^jj^  ^-v.^ 

CREST  OF  PALATE  BONE 

SPINE  OF  PALATE  BONE -  ^^-  hit^Z^^        j;-^=,__i£"2= CREST  OF  MAXILLA 


is  formed  by  the  inferior  surface  of  the  body  of  the  sphenoid,  an  ala  of  the  vomer, 
and  a  small  portion  of  the  sphenoidal  process  of  each  palate  bone.  The  sphenoidal 
sinus  opens  at  the  upper  and  back  part  of  the  roof  into  the  spheno-ethmoidal  recess 
or  superior  meatus  of  the  nose. 

The  floor  is  wider  than  the  roof,  concave  from  side  to  side,  and  has  a  slight 
backward  slope.  It  is  formed  mainly  by  the  palatine  process  of  the  maxilla,  and 
comj^leted  posteriorly  by  the  horizontal  plate  of  the  palate  bone.  Near  its  anterior 
part,  close  beside  the  septum,  is  the  anterior  palatine  canal. 

The  septum,  or  inner  wall,  is  formed  by  the  crest  of  the  sphenoid,  the  crest  of 
the  nasal  bones,  nasal  spine  of  frontal,  the  mesethmoid,  vomer,  and  the  median 
crest  formed  by  the  apposition  of  the  palatine  plates  of  the  maxillae  and  the  hori- 
zontal plates  of  the  palate  bones.  The  anterior  border  has  a  triangular  outline, 
limited  above  by  the  mesethmoid,  and  below  by  the  vomer.  This  receives  the 
triangular  cartilage  of  the  nose.  The  posterior  border  is  formed  by  the  pharyngeal 
edge  of  the  vomer.  The  septum  is  usually  deflected  to  one  side,  and  is  occasionally 
perforated.  Sometimes  a  stri])  of  cartilage,  continuous  Avith  the  triangular  cartilage, 
persists  between  the  vomer  and  mesethmoid. 

The  outer  wall  is  formed  by  tlie  nasal  process  and  inner  wall  of  the  maxilla, 
the  lachrymal,  the  ethmoidal  and  inferior  turbinals,  the  vertical  plate  of  the  palate 


so 


THE  SKELETON 


bone,  and  the  inner  surfaeoof  the  internal  i.terytroid  plate.  The  outer  wall  presents 
three  recesses  or  meatuses.  The  superior  meatus,  the  shortest,  is  situated  between 
the  superior  and  middle  turbinal;  it  opens  ]K)steriorly;  two  orifices  are  in  relation 
with  it,  namely,  the  orifice  of  the  posterior  ethmoidal  cells  and  the  spheno- 
palatine foramen.  The  middle  meatus  lies  between  the  middle  and  inferior 
turbinals.  It  oi)ens  anteriorly  and  posteriorly.  This  meatus  has  two  orifices  com- 
numieating  with  it — the  opening  of  the  antrum  (which  is  of  very  irregular  shape) 
and  the  termination  of  the  infundibulum.  The  inferior  meatus  is  situated  be- 
twei-n  the  inferior  turl)inal  and  the  lloor  of  the  fossa;  it  i)resents  near  its  anterior 
part,  under  cover  of  the  turbinal,  the  terminal  orifice  of  the  nasal  duct.  This  is 
the  largest  meatus,  and,  like  the  middle,  opens  anteriorly  and  posteriorly. 

The  anterior  narial  orifices  are  bounded  above  by  the  lower  border  of  the  nasal 
bones,  laterally  l)y  the  maxilhe,  and  inferiorly  by  the  premaxillary  portions  of  the 
maxillie.  In  the  recent  state  they  are  separated  l)y  the  triangular  cartilage;  in  the 
dried  skull  the  most  anterior  inferior  limit  is  the  anterior  nasal  spine. 

The  posterior  narial  orifices  are  bounded  above  by  the  al?e  of  the  vomer,  the 
sphenoidal  process  of  the  palate  bones,  and  the  under  surface  of  the  sphenoid; 
externally  by  the  internal  pterygoid  plates;  and  inferiorly  by  the  posterior  border 


Fig.  88. — Skotion  thbough  the  Nasal  Fossa  to  show  the  Outer  Wall  with 

THE  Meatuses. 


CRISTA  GALLI 


BODY  OF  SPHENOID 

SPHENOIDAL  SINUS 

SPHENO-PALATINE  FORAMEN 

MIDDLE  MEATUS 

INTERNAL  PTERYGOID  PLATE    

PALATE  BONE    <Y  I         '^ 


FRONTAL  SINUS 


SUPERIOR  TURBINAL 
'—  MIDDLE  TURBINAL 
NFUNDIBULUM 


INFERIOR  TURBINAL 
ANTERIOR  NASAL  SPINE 

ANTERIOR  PALATINE  FORAMEN 


of  the  horizontal  ]»la.tes  of  the  palate  bones.  They  are  divided  by  the  posterior 
border  of  the  vomer  and  the  posterior  nasal  spine. 

The  nasal  fossa  communicate  with  all  the  more  important  fossae  and  sinuses  of 
the  skull.  By  means  of  the  foramina  in  the  roof  they  are  in  connection  with  the 
cranial  cavity.  The  infundibulum  brings  each  fossa  in  communication  with  the 
frontal  and  anterior  ethmoidal  cells.  The  posterior  ethmoidal  and  the  sphenoidal 
cells  open  into  the  superior  meatuses.  The  spheno-palatine  foramina  connect  them 
witli  the  splieno-maxillary  fossffi,  and  an  irregular  orifice  in  each  outer  wall  causes 
them  to  comnmni(-ate  with  the  antra.  The  nasal  ducts  connect  them  with  the 
orbits,  and  the  anterior  palatine  canals  with  the  buccal  cavity. 

The  sutures  visible  in  an  anterior  view  of  the  skull  are  numerous,  and  for  the 
most  part  uiiiiii]»ortant: — 

The  transverse  suture  extends  from  one  external  angular  process  to  the  other. 
The  upper  part  of  the  suture  is  formed  by  the  frontal  bone;  below  are  the  malar, 
greater  and  lesser  wings  of  the  sphenoid,  os  planum,  lachrymal,  maxillary,  and 
nasal  bones.  A  i)ortion  of  this  complex  suture,  lying  between  the  si)henoidril  and 
frontal  bones,  a])pears  in  the  anterior  cranial  fossa. 

Other  and   less  important  fissures   are  the   internasal,    naso-maxillary,   inter- 


INTERIOR  OF  THE  SKULL 


81 


maxillary,  and  malo-maxillarv.     The  small  sutures  visil)lc  in  tlic  orl)it  have  l)eeu 

already  mentioned  in  dcscrihing  that  eavity. 

The  f()ll()win<f  points  are  seen  in  an  anterior  view  of  the  eranium: — 
Tlie  glabella,  a  smooth  space  hetween  tlie  converging  superciliary  ridges. 
The  ophryon  is  the  most  anterior  point  of  the  metopic  suture. 


Fig.  89. — Thk  Postkriok  Nares. 

pterygo-palatine  canals 


FORAMEN  OVALE 


SCAPHOID  FOSSA 


PTERYGOID  FOSSA 
EXTERNAL  PTERYGOID  PLATE 

TUBEROSITY  OF  PALATE  BONE 


INTERNAL  PTERYGOID  PLATE 


HAMULAR  PROCESS 


SPINE  OF  PALATE  OR  POSTERIOR 
NASAL  SPINE 


Tlie  nasion  is  the  central  point  of  the  transverse  suture. 

The  subnasal  point  is  the  middle  of  the  inferior  border  of  the  anterior  nasal 
a{)erture  at  tlie  base  of  the  nasal  spine. 

The  alveolar  point  is  the  centre  of  the  anterior  margin  of  the  upper  alveolar 
arch. 


THE  INTERIOR  OF  THE  SKULL 

In  order  to  study  the  interior  of  the  skull  it  is  necessary  to  make  sections  in 
three  directions, — sagittal,  coronal,  and  horizontal.  This  enables  the  student  to 
examine  the  various  points  with  facility,  and  displays  the  great  pro[)ortion  the 
brain  cavity  bears  to  the  rest  of  the  skull.  The  sagittal  section  should  be  made 
slightly  to  one  side  of  the  median  line  in  order  to  i)reserve  the  nasal  septum.  The 
black  line  (fig.  90)  drawn  from  the  basion  (anterior  margin  of  the  foramen  mag- 
num) to  the  gonion  (the  anterior  extremity  of  the  sphenoid)  represents  the  basi- 
cranial  axis  ;  whilst  the  line  drawn  from  the  gonion  to  the  subnasal  point  lies 
in  the  basi-facial  axis.  These  two  axes  form  an  angle  termed  tlie  cranio-facial, 
which  is  useful  in  making  comparative  measurements  of  crania.  A  line  prolonged 
vertically  upwards  from  the  basion  will  strike  the  bregma.  This  is  the  basi- 
bregmatic  axis,  and  gives  the  greatest  height  of  the  cranial  cavity.  A  line  drawn 
from  the  ophryon  to  the  occipital  point  indicates  the  greatest  length  of  the 
cranium. 

Near  its  middle,  the  cranial  cavity  is  encroached  upon  by  the  ]ietrosal;  the 
walls  are  (channelled  vertically  by  narrow  grooves  for  the  middle  and  small  meningeal 
arteries,  and  towards  the  base  and  at  the  vertex  broader  furrows  are  found  for  the 
venous  sinuses. 

The  coronal  section  is  most  instructive  when  made  in  the  basi-bregmatic  axis. 
The  section  will  pass  through  the  petrosal  in  such  a  way  as  to  traverse  the  two 
external  auditory  passages  and  expose  the  tympanum  and  vestibule,  and  will  also 
partially  traverse  the  internal  auditory  meatuses.  Such  a  section  will  divide  the 
parietal  bones  slightly  posterior  to  "the  parietal  eminences,  and  a  hue  drawn 
transversely  across  the  section  at  the  miil-])oint  Avill  give  the  greatest  transverse 
6 


82 


THE  SKELETON 


measurement  of  the  cranial  cavity.  A  skull  tlivided  in  this  way  facilitates  the 
examination  of  the  parts  about  the  posterior  nares. 

The  horizontal  section  of  the  skull  should  be  made  through  a  line  extending 
from  tlie  ophryon  to  tlic  occipital  point,  passing  laterally  a  few  millimetres  above 
the  pterion  on  each  side.  It  is  of  great  advantage  to  study  the  various  parts  on 
the  floor  (»f  tiie  cranial  cavity  in  a  second  skull  having  the  dura  mater  and  its 
various  j)rocesses  in  situ. 

The  floor  of  the  cranial  cavity  presents  three  irregular  depressions  termed  the 
anterior,  middle,  and  jiosterior  fossae. 

The  Anterior  Fo.ssa. — The  floor  of  this  fossa  is  on  a  higher  level  than  the  rest 
of  the  cranial  floor.  It  is  formed  by  the  horizontal  plate  of  the  frontal  bone,  the 
cribriform  j^late  of  the  ethmoid,  and  the  lesser  wings  of  the  sphenoid,  which  meet 
each  other  and  exclude  the  pre-sphenoid  from  the  anterior  fossa.  The  free  margins 
of  the  lesser  wings  and  the  optic  groove  mark  the  limits  of  this  fossa  ])Osteriorly. 
The  central  portion  of  the  fossa  is  depressed  on  each  side  of  the  crista  galli,  the 


Fig.  90.— The  Skull  in  Sagittal  Section. 


BREGMA 


^-^OPHRYON 


OH    EXTERNAL 

OCCIPITAL    PRO 

TUBERANCE 


depressions  forming  a  part  of  the  roofs  of  the  nasal  sinuses;  laterally,  the  floor  of 
this  fossa  is  convex  where  it  corresponds  to  the  roof  of  the  orbits,  and  is  marked 
by  irregular  furrows.  It  supports  the  frontal  lobes  of  the  cerebrum.  The  sutures 
traversing  the  floor  of  the  fossa  are  the  fronto-ethmoidal,  forming  three  sides  of  a 
rectangle,  that  ])ortion  of  the  transverse  facial  suture  which  traverses  the  roof  of 
the  orbit,  and  the  ethmoido-sphenoidal  suture,  the  centre  of  which  corresponds  to 
the  gonion.     The  points  of  interest  in  the  fossa  are: — 

A  groovi!  for  the  su]ierior  longitudinal  sinus. 

The  foramen  caecum  which  transmits  a  small  vein. 

Tlie  crista  galli. 

Tlie  ethmoidal  fissure  tor  the  nasal  branch  of  the  fifth  nerve. 

The  cranial  orifice  of  the  anterior  ethmoidal  canal,  transmitting  the  nasal 
branch  of  tlie  fiftli  nerve,  and  a  inriiiuMcal  brancli  of  the  anterior  ethmoidal  artery. 

Ethmoidal  foramina  for  the  olf,\(tory  filaments. 

Cranial  orifice  of  thr  posterior  ethmoidal  canal,  transmitting  a  meningeal 
branch  of  the  i)Osterior  ctlmioidal  artery. 


IXTERIOR    OF  THE  SKULL  83 

The  ethmoidal  spine  of  the  splienoid. 

Furrows  for  meningeal  arteries. 

The  MIDDLE  CRANIAL  FOSSA  presciits  a  central  isthmus  and  two  lateral  depressed 
portions.  It  is  limited  anteriorly  by  the  posterior  borders  of  the  lesser  wings  of  the 
si)henoid  and  the  anterior  margin  of  the  optic  groove.  The  posterior  limits  are  the 
dorsum  ephippii  and  the  superior  borders  of  the  petrosals.  Laterally  it  is  bounded 
by  the  squamosals,  tlie  great  wings  of  the  sphenoid,  and  the  parietal  bones.  The 
lloor  is  formed  by  the  body  and  greater  wings  of  the  sphenoid,  and  the  anterior 
surfaces  of  tlie  petrosals.  It  contains  the  following  sutures  :  spheno-parietal, 
petro-sphenoid,  squamo-sphenoidal,  s(}uamous,  and  a  portion  of  the  transverse 
suture.  The  central  portion  or  isthmus  of  the  middle  fossa  presents  the  following 
points  from  before  l)ackwards: — 

The  optic  groove,  which  lodges  the  optic  chiasma. 

The  optic  foramina,  transmitting  the  optic  nerve  and  ophthalmic  artery. 

The  olivary  process,  indicating  the  line  of  ankylosis  betAveen  pre-  and  post- 
sphenoid. 

The  anterior  clinoid  processes. 

The  pituitary  fossa,  with  the  middle  clinoid  processes,  and  grooves  for  the 
internal  carotid  arteries.  The  dorsum  ephippii,  with  the  posterior  clinoid 
processes,  and  notches  for  the  sixth  pair  of  cranial  nerves. 

This  central  de})ression  is  in  direct  relation  with  the  parts  of  the  brain  sur- 
rounding the  circle  of  Willis. 

The  lateral  depressions  receive  the  temporo-sphenoidal  lobes  of  the  brain,  and 
are  marked  by  numerous  furrows  roughly  corresponding  to  the  convolutions  of  the 
cerebrum.  Numerous  narroAV  diverging  channels  pass  upwards  from  the  fossa 
towards  the  vertex ;  these  lodge  the  ramifications  of  the  middle  and  small  meningeal 
arteries. 

The  f<3llowing  openings  occur  on  each  side  of  this  fossa: — 

The  sphenoidal  fissure,  leading  into  the  orbit  and  transmitting  the  third, 
fourth,  ophthalmic  division  of  the  fifth  and  the  sixth  nerves,  and  ophthalmic  vein. 

In  the  greater  Aving  of  the  sphenoid  near  its  union  with  the  frontal  l;)one  there 
are  small  openings  allowing  twigs  of  the  middle  meningeal  artery  to  enter  the 
orbit. 

The  foramen  rotundum,  which  conducts  tlie  second  division  of  the  fifth  nerve 
into  the  sphcno-niaxillary  fossa. 

The  foramen  ovale  :  this  transmits  the  third  division  of  the  fifth  nerve  with  its 
motor  root,  the  small  meningeal  artery,  and  the  small  superficial  petrosal  nerve. 

The   foramen  Vesalii  (not  always  present)  for  a  small  vein. 

The  foramen  spinosum,  for  the  middle  meningeal  artery  and  its  venae 
comites. 

The  middle  lacerated  foramen,  which  transmits  at  its  inner  angle  the  internal 
carotid  artery,  with  the  carotid  plexus  of  nerves. 

On  the  posterior  wall  of  this  fossa  the  objects  of  interest  are: — 

A  depression  which  lodges  the  Gasserian  ganglion. 

The  hiatus  Fallopii,  for  the  great  superficial  petrosal  nerve,  and  a  twig  from 
the  middle  meningeal  artery. 

A  foramen  for  the  small  superficial  petrosal  nerve. 

A  minute  foramen  for  the  external  superficial  petrosal  nerve. 

An  eminence  formed  by  the  superior  semicircular  canal. 

Anterior  and  slightly  external  to  the  ridge  formed  by  the  superior  semicircular 
canal,  the  bone  is  exceedingly  thin  and  translucent.  This  is  the  roof  of  the  tym- 
panum (tegmen  tympani).  When  the  dura  mater  is  in  situ,  the  depression  lodging 
the  Gasserian  ganglion  is  converted  into  a  foramen,  traversed  by  the  fifth  nerve. 
The  notch  in  the  side  of  the  dorsum  ephippii  for  the  sixth  ners'e  is  also  a  foramen 
when  the  dura  mater  is  present.  In  many  skulls  the  middle  clinoid  process  is  pro- 
longed to  meet  the  anterior  clinoid  process,  and  thus  forms  a  foramen  for  the  inter- 
nal carotid  artery.  The  grooves  for  the  middle  meningeal  arteries  are  sometimes 
(•anals  or  tunnels  in  a  part  of  their  course,  especially  in  old  skulls.  The  grooves 
radiate  from  the  foramen  spinosum  and  extend  to  the  vault.  The  bones  most 
deei)ly  marked  are  the  squamosal,  the  greater  wing  of  the  sphenoid,  and  the 
parietal. 


84 


THE  SKELETON 


Fig.  hi.— The  Skill  ix  Horizoxtal  Section. 


ETHMOIDAL  FISSURE  FOR  NASAL 

NERVE 
ANTERIOR  ETHMOIDAL  CANAL  (FOR 
NASAL  NERVE) 

ETHMOIDAL  FORAMINA  FOR  OLFAC- 
TORV  NERVE 


OPTIC  FORAMEN  (FOR  SECOND  OR 
OPTIC  NERVE) 


FORAMEN  ROTUNDUM  (SECOND 
DIVISION  OF  FIFTH  NERVE) 

FORAMEN  OVALE  (THIRD  DIVISION 

OF  FIFTH  NERVE) 
NOTCH  FOR  SIXTH  NERVE 


DEPRESSION  FOR  FIFTH  NERVE 
HIATUS  FALLOPII 


INTERIOR  AUDITORY  MEATUS 
(SEVENTH  AND  EIGHTH   NERVES) 


JUGULAR   FORAMEN   (NINTH,  TENTH, 
AND  ELEVENTH  NERVES) 


ANTERIOR  CONDYLOID  FORAMEN 
(TWELFTH  NERVE) 


INTERIOR  OF  THE  SKULL 


85 


Fig.  92. — The  Skill  in  Horizontal  Section. 


RIDGE  FOR  FALX  CEREBRI 
CRISTA  GALLI 

ANTERIOR  FOSSA 
CRIBRIFORM  PLATE 


LESSER  WING  OF  SPHENOID 


THE  LIMBUS 
GFTIC  GROOVE 


PITUITARY  FOSSA 


DORSUM  EPHIPPII 
PETRO-SPHENOIDAL  PROCESS 


MIDDLE  FOSSA 


FORAMEN   MAGNUM 


POSTERIOR  FOSSA 


INTERNAL  OCCIPITAL  CREST 


INTERNAL  OCCIPITAL  PROTU- 
BERANCE 


"-tSgi 


86  THE  SKELETON 

The  POSTERIOR  iRANiAL  FOSSA  is  tlu'  (Icepcst  poi'tiou  of  the  cavity.  It  is  bounded 
by  the  dovsuin  ephippii  and  the  superior  borders  of  the  petrosals,  tlie  mastoid 
portion  of  the  petrosals,  the  posterior  inferior  angle  of  the  parietals,  and  the  squanio- 
oecipital  below  the  level  of  the  crest  (supra-occipital).  The  upi)er  limits  are 
indicated  by  the  grooves  for  the  lateral  sinuses.  It  is  marked  by  the  following 
sutures : — the  petro-occipital,  occipito-mastoid,  parieto-mastoid,  and,  in  young 
skulls,  the  basilar  suture. 

The  ridges  limiting  this  fossa  give  attachment  to  the  tentorium  cerebelli,  and 
the  fossa  lodges  the  cerebellum  with  the  pons  and  medulla.  It  communicates  with 
the  general  cranial  cavity  by  means  of  the  foramen  of  Pacchionius  when  the  ten- 
torium is  /*(  dtu. 

It  has  the  following  objects  of  interest: — 

The  clivus,  extending  from  the  dorsum  ephii)pii  to  the  anterior  margin  of  the 
foramen  magnum.  This  is  in  relation  with  the  basilar  artery,  the  i)ons,  the 
medulla,  the  sixth  nerves  and  the  basilar  sinus. 

The  notch  for  the  sixth  nerve  on  each  side  of  the  dorsum  epliii)pii.  This  is 
sometimes  a  foramen,  termed  the  petro-sphenoid. 

The  foramen  magnum,  ])resenting  on  eacli  side  a  tubercle  for  the  check  liga- 
ments; and  tlic  anterior  condyloid  foramen  (sometimes  sul)divided  by  a  spicu- 
lum  of  bone)  for  the  hypoglossal  nerve.  Behind  the  foramen  there  is  a  vertical 
ridge  of  bone,  the  internal  occipital  crest,  for  the  falx  cerebelli.  This  sometimes 
presents  a  depression  known  as  the  vermiform  fossa. 

The  anterior  boundaries  of  the  fossa  present: — 

A  notch  for  the  passage  of  the  fifth  nerve.  This  is  a  foramen  when  the  ten- 
torium is  present. 

The  internal  auditory  meatus,  for  the  facial  and  auditory  nerves,  and  tlie 
auditory  branch  of  the  liasilar  artery. 

The  jugular  foramen,  which  transmits  the  glosso-pharyngeal,  vagus,  and  spinal 
accessory  nerves,  the  internal  jugular  vein,  the  meningeal  branch  of  the  ascending 
pharyngeal  artery,  aqueductus  vestibuli  and  hiatus  subarcuatus. 

Tlie  termination  of  the  groove  for  the  lateral  sinus,  with  the  internal  orifice  of 
the  mastoid  foramen. 

The  cranium  of  an  average  European  has  a  capacity  of  1450  cc.  The  circumfer- 
ence, taken  in  a  plane  passing  through  the  ophryon  anteriorly,  the  occipital  point 
posteriorly,  and  the  pterion  laterally,  is  52  cm.  The  length  from  the  ophryon  to 
the  occipital  point  is  17  cm. ;  the  'width  between  the  parietals  at  the  level  of  the 
zygomata  is  12-5  cm. ;  and  the  height  from  the  basion  to  the  bregma  is  nearly  the 
same.     The  cranio-facial  angle  is  about  96°. 


THE  TEETH 

An  adult   individual  with  perfect  dentition  possesses  thirty-two  teeth,  equally 

distril)uted  to  the  maxilla  and  mandible.     The  upper  set  are   called   maxillary 

teeth  and  the  lower  set  mandibular.     The  four  central  teeth  in  each  dental  arch  are 

termed  incisors;  the  tooth  next  these  on  each  side  is  the  canine;  behind  these  are  two 

premolars  or  bicuspids;  and  lastly,  three  molars.     This  relation  of  teeth  is  expressed 

by  means  of  a  formula: — 

.2     1         2      S 
I  —  c  -  mm  ~  in     =  32. 
2     1^      2      ;? 

Each  tooth  has  a  portion  coated  with  enamel  exposed  al)ove  the  gum — named 
the  crovvn  ;  and  a  portion  coated  with  cementum  embedded  in  bone — this  is  tlie 
root.     The  line  of  union  of  the  crown  and  root  is  termed  the  neck. 

The  surface  of  the  tooth  directed  towards  the  lips  and  cheek  is  called  labial 
and  buccal  respectively,  and  that  towards  the  tongue  lingual.  It  is  also  necessary 
to  apply  definite  terms  to  the  opposed  surfaces  of  teeth,  hence  the  surface  directed 
towards  tlie  middle  line  of  the  mouth  if  the  alveolar  arch  were  straightened  out 
is  median,  and  the  opposite  side  is  distal.  Each  tooth  has  distinguishing  fea- 
tures. 


THE  TEETH 


87 


The  incisors. — The  central  maxillary  incisor  is  very  much  larger  than  the 
lateral,  the  crown  is  somewhat  oblong  in  outline,  its  length  exceeding  the  breadth. 
The  median  is  longer  than  the  distal  border.  The  labial  surface  is  convex,  the 
hngual  concave,  and  terminates  near  the  gum  in  a  low  eminence,  the  basal  ridge 
or  cingulum.  In  recently  erupted  teeth,  the  cutting  edge  is  elevated  into  three 
ismall  (usiis;  these  soon  wear  down  and  leave  a  straight  edge.  The  root  is  long, 
single,  and  flattened  laterally. 

The  maxillary  lateral  incisors  are  much  smaller  than  the  centrals,  which  they 


Fig.  9.3. — The  Teeth  of  an  Adult. 

canine  bicuspids  molars 


WISDOM  TOOTH 


UPPER   OR 

MAXILLARY 

TEETH 


(*>  ll-  in,     LOWER  OR 

MANDIBU- 

\  f  \   /[      LAR   TEETH 

5 


resemble  in  the  general  contour  of  the  crown.  The  distal  angle  of  the  crown  is 
more  rounded  than  in  the  central  incisors,  and  the  cingulum  is  more  pronounced. 
The  root  is  single.     The  maxillary  incisors  are  lodged  in  the  premaxilla. 

The  mandibular  central  incisors  are  much  narrower  than  those  of  the  upper  set, 
and  less  than  half  their  width  in  the  cutting  edges,  and  the  crown  becomes  contracted 
towards  the  neck.  The  cingulum  is  scarcely  marked,  and  the  root  single.  The 
lower  lateral  incisors  are  distinctly  larger  than  the  lower  centrals  in  every  direction. 


Fig.  94.— a  Molar  Tooth   in  section,  and  a  Canine  Tooth. 

CROWN  ---^ 

CUSP fr^^yy  f^' """^ 

NECK ^^-^.'       -PULP  CAVITY 

KlJl 

NECK 

CINGULUM 


The  distal  angle  of   the  crown  is  rounded  off;    the  root  is  single  and  frequently 
presents  on  each  side  a  longitudinal  groove. 

The  canines. — These  differ  from  the  incisors  in  possessing  larger  crowns,  and 
thick  long  roots.  The  crown  ends  in  a  blunt  point,  and  the  cutting  edge  slopes 
away  on  each  side.  The  slope  towards  the  bicuspid  is  the  longer,  and  causes  the 
crown  to  be  asymmetrical.  The  lingual  surface  presents  a  median  and  two  lateral 
ridges;  they  converge  towards  the  well-marked  cingulum,  which  is  often  produced 
into  a  distinct  cusp. 


88 


THE  SKFJ.ETOX 


The  luandibular  canines  have  not  sueh  pronounced  features  as  the  maxillary; 
the  i)<)int  is  hhmter.  and  the  median  ridge  is  absent  from  the  lin<>;ual  surface. 

The  maxillary  premolars  or  bicuspids. — The  crown  of  the  first  i)remolar 
has  a  ^'rinding  surface  which  is  somewliat  (quadrilateral  in  outline;  the  lal)ial  is, 
however,  longer  tlian  the  lingual  border.  It  has  two  cusps,  of  which  the  laljial  is 
much' the  larger.  The  cusps  or  tubercles  are  separated  by  a  pit,  but  are  connected 
l)v  a  narrow  ridge  along  the  median  and  distal  l^orders.  The  median  border  is 
nearly  straight,  the  distal  is  convex.  The  root  may  be  single  or  it  may  l)e  bifur- 
cated near  the  apex  or  marked  by  a  longitudinal  depression,  or  lie  double  through- 
out the  greater  part  of  its  length;  it  may  in  some  specimens  have  three  distinct 
roots  like  a  molar. 

The  second  bicuspid  differs  from  the  first  in  having  its  cusps  nearly  equal  in 
size.      Its  root  is  more  deeply  grooved. 

The  mandibular  bicuspids  are  smaller  than  the  upper  and  differ  from  them  in 
shajH'.  The  labial  cusp  is  larger  than  the  lingual;  the  cusps  are  connected  by  a 
low  ridge,  the  grinding  surface  presents  two  small  ])its.  The  root  is  single,  rounded, 
and  tapering. 

The  second  lower  bicuspid  is  larger  than  the  first.  The  labial  cusp  is  higher 
and  stouter,  and  the  distal  border  is  much  more  pronounced.  Its  root  is  also 
single  and  tapering. 

The  maxillary  molars. — The  first  and  second  resemble  each  other  so  closely 


Fiu.  95.— The  Temporary  Teeth. 

INCISORS  CANINE  MILK  MOLARS 


■^Wtm     MAXILLARY   OR   UPPER   SET 


MANDIBULAR   OR    LOWER   SET 


that  one  description  will  serve  for  the  two.  The  grinding  surface  is  quadrilateral 
l)ut  with  rounded  angles.  It  has  four  cusps,  two  buccal  and  two  lingual.  Of 
these,  the  anterior  lingual  is  the  largest,  and  is  connected  with  the  posterior  buccal 
by  an  oblique  ridge  of  enamel.  The  groove  separating  the  buccal  and  lingual  cusps 
extends  on  to  the  sides  of  the  croAvn  and  is  lost  near  the  neck.  The  median  and 
distal  borders  usually  present  a  slight  ridge.  The  roots  are  three  in  number,  two 
on  the  labial,  and  one  on  the  palatine  aspect;  this  last  is  usually  referred  to  as  the 
palatiiif  r(»nt,  ;md  often  diverges  from  the  crown  at  a  considerable  angle. 

The  mandibular  molars. — The  first  is  the  most  constant  in  form.  It  has  five 
cusps  on  the  grinding  surface.  Four  occupy  the  angles  and  are  separated  by  a 
crucial  fissure.  The  fifth  cusp  is  situated  at"  the  posterior  extremity  of  the  longi- 
tudinal fissure.  It  has  two  roots,  placed  one  in  front  of  the  other;  they  are 
inclined  somewhat  backwards,  and  present  a  vertical  groove  which  is  sometimes  so 
deep  as  to  divide  each  root,  producing  four  roots.  One  root  only  may  divide  in 
this  way. 

Tlie  second  molar  differs  from  the  first  in  the  frequent  absence  of  the  fifth 
cusp;  when  present  it  is  feebly  developed.  The  roots  have  a  tendency  to  become 
conHucnt. 

The  third  molars  (wisdom  teeth). — The  upper  third  molar  resembles  in  its 
grinding    surface  tlie  adjacent    molars.     The  two  palatine  tubercles  are  usually 


MORPHOLOGY  OF  THE  SKILL  89 

l)leiidcd,  and  the  roots  coalesce  and  taper  to  a  cone.  Tlie  apex  is  often  licnl. 
The  characters  of  this  tooth  are  very  varial)le. 

The  third  lower  molar  has  a  larger  crown  than  the  corresponding  tooth  in  the 
uii])er  set;  it  resembles  the  adjacent  molars  and  has  usually  tive  cusps.  It  has  two 
roots  which  may  be  confluent. 

The  L'eJdfidiis  of  tlie  Croicns  of  the  Upper  dud  Luircr  Teeth  to  one  anotJier. — In  a 
normal  condition  the  upper  teeth  form  a  larger  arch  than  tlie  lower.  The  ujjjjcr 
incisors  and  canines  close  in  front  of  tlie  lower;  occasionally  they  fall  upon,  but 
rarely  fall  liehind  them.  The  laljial  tul)ercles  of  the  liicuspids  and  molars  of  the 
lower  jaw  are  received  in  the  depressions  between  the  la])ial  and  lingual  tul)ereles 
of  the  upper  set  of  teeth;  hence  the  labial  tubercles  of  the  upper  overlap  the 
corresponding  tubercles  in  the  lower  teeth. 

In  consequence  of  the  difference  in  width  of  the  crowns  of  the  upper  and  lower 
incisors,  it  liappens  that  in  closure  of  the  mouth  each  tooth  impinges  upon  two 
teeth. 

The  milk  teeth. — These  are  smaller  in  numljcr  and  size  than  the  teeth  of  the 
permanent  set.      The  formula  is: — 

di  -  dc  i-  dui  -  =  20. 
2         12 

The  teniporarv  teetli  are  smaller  than  their  successors;  the  enamel  of  the  crown 
terminates  in  a  thick  edge;  and  the  tubercles  on  the  crowns  of  the  molars  are  less 
regular  and  pronounced. 

The  incisors  are  similar  to  those  of  the  permanent  set,  l)Ut  tlie  canines  have 
shorter  and  Ijroader  crowns  than  their  successors. 


TILE  MORFLLOLOGY  OF  TILE   SKULL 

la  Man  the  skull  during  development  passes  through  three  stages.  At  first  the  brain 
vo.>icles  are  enclosed  in  a  sac  of  indifferent  tissue  which  ultimately  becomes  tough  and  fibrous. 
Tliis  is  the  membranous  cranium ;  a  portion  of  it  is  represented  in  the  adult  by  tlie  chua  mater, 
the  remainder  is  converted  into  the  membrane-bones.  Gradually  the  sides  and  base  of  tlie 
membranous  cranium  become  cartilaginous  :  in  due  C(jurse  osseous  tissue  appears  in  themem- 
branous  tracts,  and  later  in  the  cartilage.  Eventually  an  osseous  box  is  formed,  consisting  of 
membrane-bones  and  cartilage  bones  intricately  interwoven. 

A  study  of  the  skull  in  the  chondral  stage  is  very  instructive.  It  consists  of  two  parts  :  (1) 
The  skull  jiroper  ;  and  (2)  the  ai)])endicular  elements. 

The  skull  ]iroper  consists  of  three  regions  : — 

The  basi-cranial  or  notochordal  region,  which  ultimately  gives  rise  to  the  chief  jKirts  of  the 
occipital  lione  and  a  part  (^f  the  sphenoid. 

Anterior  to  tliis  is  the  trabecular  region,  from  which  the  remainder  of  the  sphenoid  is  subse- 
•  lueiitly  developed. 

The  most  anterior  portion  is  the  ethmo-vomerine  region,  from  which  the  nasal  septum  and 
its  associated  cartilages  arise.  Wedged  in  on  each  side  between  the  basi-cranial  and  trabecular 
regions  is  tlie  complicated  periotic  capsule. 

The  appendicular  elements  of  the  cranium  are  a  number  of  cartilaginous  rods,  which  undergo 
a  remarkable  inetaniori>liosis,  and,  in  the  adult,  are  represented  by  the  ear-bones,  the  styloid 
process,  and  the  hyoid. 

The  chondro-cranium  at  the  third  month  presents  the  following  parts.  Seen  fi-om  above, 
the  cartilage  extends  from  the  cranial  base  to  a  spot  midway  between  the  base  and  the  vertex, 
shading  off  indefinitely  on  the  membranous  wall.  The  conspicuous  oval  masses  on  each  side  are 
the  periotic  cartilages,  in  which  the  floccular  fossae  are  consiiicuous  objects.  Each  ]ieri(itic 
cartilage  is  joined  to  the  sidienoiil  by  a  strip,  termed  the  sphenotic  cartilage,  which  usually 
persists  in  the  adult  skull.  At  this  date  the  cartilage  for  the  orbito-sphenoid  (the  so-called  lesser 
wing)  is  co-extensive  with  the  ali-sphenoid,  and  forms  i^ait  of  the  lateral  wall  of  the  skull.  J  he 
snout-like  appearance  of  the  anterior  part  of  the  skull  is  caused  by  the  fronto-nasal  iilate.  On 
each  side  of  the  ethmo-vomerine  plate  near  its  anterior  terniinatidii  there  are  tw(t  small  concave 
pieces  of  cartilage  for  Jacobson's  organ.  They  are  sometimes  referred  to  as  the  plougiisliare 
cartilages  owing  to  their  shape. 


•10 


THE  SKELETON 


The  Afetamorphosis  of  the  Brdiuliinl  Bars 

These  rods  of  cartilivao  arc  named,  from  before  backwards,  the  mandibular,  hyoid,  and 
thyroid  bars.  Tliey  may  with  care  be  easily  dissected  in  tlie  foetus  between  the  third  and  fourth 
months.     Their  metaiudrphosis  is  as  Ibllows  : — 

The  two  extremities  of  the  mandibular  bar  ossify ;  tlie  distal  end  ultimately  forms 
that  portion  of  the  mandible  adjacent  to  the  symi)hysis;  the  proximal  end  ossifies  as  the 
malleus.  The  intermediate  portion  disappears;  the  only  vesti^^e  is  a  band  of  fibrous  tissue, 
tlu'  spheno-mandibular  ligament,  extending  from  the  spine  of  the  sphenoid  to  the  spine  of  the 
mandible. 

The  hyoid  bar  I'usi's  distally  with  the  thyroid  bar,  and  is  represented  by  tlie  hyoid  bone.  Its 
]troximal  end  becomes  the  incus,  tympano-hyal,  and  styloid  process;  the  intervening  strip  is 
rei)resented  in  the  adult  by  the  stylo-hyoid  ligament. 

The  styloid  process  has  two  centres  of  ossification.     A  nucleus  appears  anterior  to  the  stylo- 


FiG.  9G.— The  CHoximo-CnAXirM. 


ETHMOID  CARTILAGE 


OPTIC  FORAMEN 

FORAMEN  ROTUNOUM 

FORAMEN  OVALE 

HIATUS  FALLOPII 
INTERNAL  AUDITORY  MEATUS 

JUGULAR  FORAMEN 


ANTERIOR  CONDYLOID  FORAMEN  _ 

CONDYLES  —  *^^ 


—  NASAL  CARTILAGES 


ORBITO-SPHENOID 
ALI-SPHENOID 
PERIOTIC  CAPSULE 


,    ___^,   Nfe  t ^v  lU AQUEOUCTUS  VESTIBULI 

h  fl,       '  _^        ]  }''A FLOCCULAR  FOSSA 

A  /  n  ^'/^__L_  MASTOID  FORAMEN 

!  »   .^ OCCIPITAL  CARTILAGE 


mastoid  foramen,  and  is  known  as  the  tympano-hyal.  At  birth  the  true  styloid  process  is  carti- 
laginous. In  \\w.  second  year  it  ossifies,  and  subsequently  becomes  firmly  ankylosed  to  the 
tympano-hyal.  Occasionally  the  hyoid  bar  may  ossify  throughout.  When  this  is  the  case  the 
styloid  jtrocess  reaches  to  the  hyoid  and  replaces  the  stylo-hyoid  ligament. 

The  stapes  originates  in  a  piece  of  cartilage  which  is  traversed  by  the  temi)orary  stapedial 
artery.  Its  centres  of  ossification  require  investigation.  The  internal  pterygoid  ])late  arises  in 
a  i)iece  of  cartilage  which  represents  the  palato-quadrate  of  lower  vertebrates.  The  internal 
pterygoid  i)lat('  is  an  ai)pendicular  element  engrafted  on  to  the  sphenoid.  In  many  mammals  it 
IS  a  sei)arate  bone  throughout  life.  In  the  same  way  the  styloid  process  is  an  appendicular 
element  ankylosed  to  the  petrosal  and  the  tympanic  plate  ;  in  many  mammals  it  remains  separate 
throughout  life. 


The   SkuU  at  Birth 

The  .skull  at  birth  presents,  when  compared  with  the  adult  skull,  several  important  and 
interesting  features.  Its  peculiarities  may  be  considered  under  three  headings  : — The  peculi- 
arities of  the  foetal  skull  as  a  whole;  the  condition  of  individual  bones;  the  remnants  of  the 
chondral  skull. 

The  general  characters  of  the  fcEtal  skull. — The  most  striking  features  of  the  skull  at  birth 
are,  its  relatively  large  size  in  comjiarison  with  the  body,  and  the  jiredominauce  of  the  cerebral 
over  the  facial  portion  of  the  skull ;  the  latter  is,  in  fact,  very  small. 

The  frontal  and  parietal  eminences  are  large  and  conspicuous;  the  sutures  are  absent ;  the 
adjacent  margins  of  the  bones  of  the  vault  are  se])arated  by  septa  of  fibrous  tissue  contiiuious 
with  the  (hira  mater  internally  and  the  pericranium  externally;  hence  it  is  difficult  to  separate 
the  roof  bones  from  the  underlying  dura  inater,  each  bone  being  lodged  as  it  were  in  a  dense 
membranous  sac.  The  bones  of  the  vault  con.sist  of  a  single  layer  without  any  dijiloe,  and  their 
cranial  surfaces  present  no  digital  impressions.  Six  memlmmous  spaces  exist,  nameil  fontanelles  : 
two  are  median,  named  anterior  and  posterior;  and  two  exist  on  each  side,  termed  anterior  and 
j)osterior  lateral  fontanelles.     Kuch  angle  ol"  the  parietal  bones  is  in  relation  with  a  Ibntanelle. 


MORPHOLOGY  OF  THE  SKCLL 


91 


The  anterior  foiitanelle  is  lozenge-shaped,  the  posterior  triangular.     The  lateral  fontauelles  are 
irreL'ular  in  outline. 

Turning  to  the  base  of  the  skull,  the  most  striking  points  are  the  absence  of  the  ma.stoid 


Fig.  97.— The  Cranum  at  Birth. 


Fig.  98.— The  Craxilm  at  Birth. 


processes  and  the  large  angle  which  the  pterygoid  plates  form  with  the  skull-base,  whereas  in  the 
adult  the  angle  is  almost  a  right  one.  The  base  of  the  skull  is  relatively  short,  and  the  lower 
border  of  the  mental  symphysis  Ls  on  a  level  with  the  occipital  condyles. 


92 


THE  SKELETON 


The  facial  skeleton  is  relatively  small  in  consequence  of  the  small  size  of  the  mxsal  fossae, 
the  small  size  of  the  antrum,  and  the  rudimentary  condition  of  the  alveolar  borders  of  the 
maxilhe  and  mandible ;  these  are  as  wide  as  they  are  high,  and  are  almost  filled  with  the 
turbiuals. 

Fig.  99.— Tuk  Craxium  at  IIiktit  ix  Sagittal  Skctxon. 


Fig.  100. — The  Occipital  at  Birth. 


INTERPARIETAL  PORTION    (DEVELOPS  IN 
MEMBRANE) 


THE  INTERPARIETAL    AND    SUPRA- 
OCCIPITAL  PORTIONS  FORM  THE 

SQUAMO- OCCIPITAL     OF     THE 
ADULT 

SUPRA-OCCIPITAL    PORTION    (DEVELOPS 
IN  CARTILAGE) 


BASI-OCCIPITAL 


The  Peculiarities  of  Individual  Bones  at  Birth 

The  occipital  consists  of  four  distinct  parts:  the  basi-occipital,  two  ex-occipitals,  and  the 
squamo-occipital;  these  I'our  })arts  are  united  by  hyaline  cartilage.  (\)niiiared  with  the  adult 
bone,   the    following  are  the  most  important  i)oints  of  distinction  : — There  is  no   pharyngeal 


MORPHOLOGY  OF  THE  SKULL 


93 


tubercle  or  jugular  process  ;  the  squaiuo-occiijital  presents  two  deep  fissures  separating  the 
interparietal  fruni  the  suiiraoccipital  portion,  and  extending  nearly  as  lar  inwards  as  the  occipital 
protuberance.     The  grooves  for  the  lateral  sinus  are  absent. 

The  sphenoid  in  a  macerated  foetal  skull  falls  into  three  pieces.  The  main  ])ortion  consists 
of  the  united  pre-  and  post-sphenoid  with  the  orbito-sphenoids  and  lingulae.  The  pre- 
sphenoid  is  quite  solid  and  connected  with  the  ethmo-vomerine  cartilage,  ami  presents  no  traces 
of  the  air  siimses  Mdiich  occupy  this  ]iart  in  the  adult  skull.  The  pre-si)henoid  by  its  upjier 
surface  forms  part  of  the  anterior  cranial  fossa,  from  which  it  is  subsequently  excluded  by  the 
orbito-sphenoids.  The  optic  ioramina  are  large  and  triangular  in  shape.  The  lingulae  stand 
out  from  the  basi-sphenoid  as  two  lateral  buttresses,  and  the  floor  of  the  sella  turcica  presents 
the  cranio-pharyngeal  canal,  which  in  a  recent  bone  is  occupied  by  fibrous  tissue.     The  dorsum 


Fig.   101. — TiiE  Sphenoid  at  Birth. 


^^/?,'71'MT} 


VIDIAN   CANAL  LINGULA 

ephippii  is  yet  cartilaginous.  The  ali-sphenoids  with  the  pterygoid  processes  are  separated  from 
the  rest  of  the  bone  by  cartilage.  The  foramen  rotundum  is  complete,  but  the  luture  foramen 
ovale  is  merely  a  deep  notch  in  its  posterior  border,  and  there  is  no  foramen  spinosum.  The 
pterygoid  processes  are  short,  and  each  internal  pterygoid  plate  presents  a  broad  surface  for 
articulation  with  the  lingulse.  The  Vidian  canal  is  a  groove  between  the  internal  pteiygoid 
plate,  the  lingula,  and  greater  wing. 

The  temporal  bone  at  birth  consists  of  three  parts  (excluding  the  ear-bones)  :  the  petrosal, 
squamosal,  and  tympanic.  The  petrosal  presents  a  large  and  conspicuous  floccular  fossa  ;  tlie 
hiatus  Fallopii  is  a  shallow  bay  lodging  the  geniculate  ganglion  of  the  facial  nerve.     There  is  a 


\ 


Fig.  102.— The  Temporal  Bone  at  Birth. 

squamosal 


relatively  large  mastoid  antrum,  but  no  mastoid  jnocess.  The  styloid  process  is  uno.^sitied,  but 
the  tympano-hyal  may  be  detected  as  a  minute  rounded  nodule  of  bone  near  the  stylo-mastoid 
foramen. 

The  squamosal  has  a  very  shallow  glenoid  fossa  and  a  relatively  large  post-glenoid  tubercle. 
The  posterior  part  of  the  inferior  border  is  prolonged  downwards  into  an  uncinate  proce^s  to 
clo.se  externally  the  mastoid  antmm. 

The  tympanic  bone  or  annulus  is  a  delicate  horseshoe-shaped  ossicle,  attached  by  its  aiiti  rior 
and  posterior  horns  to  the  inferior  l)order  of  the  squamosal. 

The  ear-bones  are  chiefly  of  interest  from  their  size,  for  they  are  as  large  at  birth  as  in  the 
adult.     Tlie  processus  gracilis  (Folian  process)  may  be  2  cm.  in  length. 


94 


THE  SKELETON 


Tlie  frontal  (-(.nsists  of  two  bones  separated  by  a  median  vertical  (metopic)  suture.  The 
frontal  eiuiiu  nee  is  very  conspicuous,  but  the  superciliary  ridges  and  frontal  sinuses  are  wanting. 
Tlie  iKusil  spine,  which  later  becomes  one  of  the  most  conspicuous  features  of  this  bone,  is  absent. 
Tliere  is  no  temijoral  ridge.  ...  , 

The  parietal  is  simiJy  a  quadrilateral  lamina  of  bone,  concave  on  its  inner  and  convex  on  the 


Yui.  103.— Thk  Temporal  Bonk  at  I;irth.     (Outer  view.') 


S-/—-/A      P^RO-SQUAMOUS  SUTURE 
ETROSAL 


POST-GLENOID  TUBERCLE 
GLASERIAN  FISSURE 
TYMPANIC  ANNULUS 


,TYLO-MASTOiO  FORAMEN 
TYMPANO-HYAL 


CAROTID  CANAL 


Fig.  104. — Temporal  Bone  at  Birth.     (Inner  view.) 


—  HIATUS  FALLOPM 

—  FLOCCULAR  FOSSA 
-■   AQUEDUCTUS  VESTIBUL! 

INTERNAL  AUDITORY  MEATUS 


(juter  surface.  The  parietal  eminence,  which  indicates  the  spot  in  which  the  ossification  of  the 
bone  commenced,  is  large  and  conspicuous.  The  grooves  for  blood-sinuses,  as  in  other  crania! 
bones,  are  absent.  Each  angle  of  the  parietal  is  in  relation  with  a  foutanelle.  As  in  the  adult, 
the  anterior  inferior  angle  of  the  bone  is  prolonged  downwards  towards  the  ali-sphenoid. 

The  ethmoid  consists  of  two  lateral  portions  separated  by  the   still  cartilaginous  ethmo- 

FiG.  105. — The  Frontal  at  Birth. 


vomerine  plate.     The  ethmoid  cells  are  represented  liy  shallow  depressions,  and  tlie  uiuinate  i)ro- 
cess  is  undeveloped. 

The  sphenoidal  turbinals  are  two  small  triangular  pieces  of  bone  lying  in  the  perichondrium 
on  each  side  oi"  the  cthmo-vomeriue  plate  near  its  junction  with  the  pre-sphenoid.  (Indicated  by 
the*  in  fig.  99.) 


MORPHOLOGY  OF  THE  SKULL 


95 


TIr'  maxilla  preseuts  the  fullDwinc:  characters  : — The  maxillo-premaxillary  suture  i.s  visible 
on  the  palatine  aspect  of  the  bone.  The  alveolar  border  presents  five  sockets  for  teeth.  The 
infraorbital  foramen  communicates  with  the  floor  of  the  orbit  by  a  deep  fissure  ;  this  fissure 
sometimes  persists  in  the  adult.     The  antrum  is  a  shallow  ^Toove. 

The  mandible  at  birth  consists  of  two  halves  united  by  fibrous  tissue  in  the  line  of  the  future 
symphysis.  Each  half  is  a  bony  trough  lodging  teeth.  The  trough  is  divided  by  thin  osseous 
partitions  into  five  compartments  :  of  these,  the  fifth  is  the  largest,  and  is  often  subdivided  by  a 
ridge  of  bone.  The  floor  is  traversed  by  a  furrow  as  far  foi^ward  as  the  fourth  socket  (that  for 
the  finst  milk  molar),  where  it  turns  outwards  at  the  mental  foramen.  This  furrow  lodges  the 
mandibular  (inferior  dental)  ueiTe  and  artery,  which  enter  by  the  large  mandibular  foramen.  The 
comlyle  is  on  a  level  with  the  mental  extremity  of  the  bone. 


Fig.  106. — The  Maxilla  at  Birth. 

premaxillary  portion 


Outer  view. 


Inferior  view. 


Inner  view. 


The  palate  bones  diff'er  mainly  from  the  adult  bone  in  that  the  vertical  and  horizontal  plates 
are  of  the  same  length  ;  thus  the  nasal  fossae  in  the  foetus  are  as  wide  as  they  are  high,  whereas 
in  the  adult  the  height  of  each  nasal  fossa  greatly  exceeds  the  width. 

Concerning  the  remaining  bones  little  need  be  said.  The  vomer  is  a  delicate  trough  of  bone 
for  the  reception  of  the  inferior  border  of  the  ethmo-vomerine  plate  ;  its  inferior  border,  that 
which  rests  upon  the  palate,  is  broad,  and  the  bone  presents  quite  a  different  appearance  from 
the  adult  vomer.  The  nasal  bones  are  short  but  broad  ;  the  malar  and  inferior  turbinals  are 
relatively  very  large  ;  and  the  lachrymals  are  thin,  frail,  and  delicate  lamell;«. 

The  hyoid  con.sists  of  its  usual  five  parts.  There  is  a  median  nucleus  for  the  basi-hyal,  and 
one  on  each  side  for  the  greater  cornua  (thyro-hyals).     The  lesser  cornua  are  cartilaginous. 


Fig.  1»»7.— Thk  ^NlAxniBLfi  at  Birth. 


OUTER   VIEW 


INNER   VIEW 


Remnants  of  the  cartilaginous  cranium. — It  has  already  been  pointed  out  that  at  an  early 
date  the  base  of  the  skull  and  the  face  are  represented  by  liyaline  cartilage,  whitJi  for  the  most 
part  is  replaced  by  bone  before  birth.  Even  at  birth  remnants  of  this  primitive  chondral  skull 
are  abundant.  In  the  cranium,  cartilaginous  tracts  exi.st  between  the  various  i)ortions  of  the 
occipital  bone,  as  well  as 'at  the  line  of  junction  of  the  occipital  with  the  i)etrosal  ami  sphenoid. 
The  dorsum  ephippii  is  entirely  cartilaginous  at  birth,  and  the  la.^t  portion  of  this  cartilage 
disappears  with  the  ankj'losis  of  the  basi-uceipital  and  basi-s|)henoid  about  the  twenty-fifth  year. 
A  similar  strip  of  cartilage  lying  between  the  jugular  proce.ss  and  the  jugular  .surface  of  the 
petrosal  persists  until  late  in  life.  A  strij)  of  cartilage  unites  the  ali-si)henoids  with  the  linffulas, 
and  for  at  least  a  year  after  birth  this  cartilage  is  continuous  with  that  which  throughout  life 


()(3  THE  SKKLKTOX 

ocrui.ios  tlio  pplicuotic  (niiilille  laccruteil)  fuiaiuen.  A  strip  of  cartilage  exists  along  the  posterior 
Imrder  of  tlie  orliito-spheiioid,  and  not  unfrequently  extends  outwards  to  the  pterion.  In  the 
adult  skull  it  is  ri'plai-cd  by  liganientcms  tissue. 

The  etlini(i-vi>nifiine  i)late  is  entirely  cartilagiiiuus,  and  near  the  end  of  the  nose  supports 
the  lateral  nasal  cartilages,  renniants  of  the  fronto-nasal  plate.  The  fate  of  the  etlnno-vouierine 
iilate  is  instructive.  The  ui)per  ])art  is  ossified  to  fonu  the  mesethmoid  ;  the  lower  jKirt  atrophies 
frouj  the  pressure  exerted  l)y  the  vomer ;  the  tip  remains  as  the  triangular  cartilage.  The 
lateral   snout-like   extremities  of  the   ironto-nasal   plate    persist  as    the   lateral   cartilages  of 

Among  the  appendicular  elements  of  the  skull,  the  styloid  process  and  a  large  portion  of  the 
hyoid  are  cartilaginous  at  birth. 

The  Newe-foramina  of  the   Skull 

Tiie  various  foramina  and  canals  in  the  skull  which  give  passage  to  nerves  may  be  arranged 
in  two  f^roups,  primary  and  secondary.  Primary  foramina  indicate  the  spots  where  the  nerves 
([uit  tlie  general  cavity  of  the  dura  mater,  and  as  this  membrane  indicates  the  limit  of  the 
primitive  cranium,  a  cranial  nerve,  in  a  morphological  sense,  becomes  extra-cranial  at  the  point 
where  it  pierces  this  membrane.  In  consequence  of  the  complicated  and  extraordinary  modi- 
fications tlie  vertebrate  skull  has  undergone,  many  nei-ves  traverse,  in  the  adult  skull,  bony 
tunnels  and  canals  which  are  not  represented  in  the  less  complex  skulls  of  low  vertebrates 
such  as  sliarks  and  rays.  To  such  foramina  and  canals  the  terms  secondary  or  adventitious 
may  be  ai)plicd. 

Nerve-foramina  are  further  interesting  in  that  they  occupy  sutures,  or  indicate  the  points  of 
union  of  two  or  more  ossific  centres.  To  this  rule  the  foramen  rotundum  is  the  only  exception  in 
the  human  skull. 

The   Primary  Foramina 

1.  Foramen  magnum. — This  is  bounded  by  four  distinct  centres,  the  supra-,  basi-,  and  two 
ex-occijiitals.  It  transmits  the  spinal  accessory  nerve,  the  vertebral  artery  and  its  anterior  and 
posterior  spinal  branches,  the  spinal  cord  and  its  membranes. 

2.  The  anterior  condyloid. — At  birth  this  is  a  deep  notch  in  the  anterior  extremity  of  the 
ex-occipital,  and  becomes  a  com])lete  foramen  when  the  basi-  and  ex-occipitals  fuse.  Occasionally 
it  may  be  complete  in  the  ex-occijiital,  but  it  indicates  accurately  the  line  of_  union  of  these  two 
elfinents  of  the  occipital  bone.  It  transmits  the  hypoglossal  nerve,  the  meningeal  branch  of  the 
ascending  pharyngeal  artery,  and  its  venas  comites. 

3.  Jugular  foramen. — This  occupies  the  jietro-occipital  suture,  and  is  formed  by  the  basi-  and 
ex-occipital  in  conjunction  with  the  petrosal.  It  transmits  the  glossopharyngeal,  pneumogastric, 
and  spinal  accessory  nerves,  a  meningeal  branch  of  the  ascending  pharyngeal  artery,  and  receives 
the  lateral  and  inferior  petrosal  sinuses. 

4.  Auditory. — This  marks  the  point  of  confluence  of  the  groups  of  centres  termed  pro-otic 
and  opisthotic.  It  transmits  the  facial  and  auditory  nerves  with  the  auditory  twig  of  the 
basilar  arteiy. 

5.  Trigeminal. — This  is  only  a  foramen  when  the  dura  mater  is  present  in  the  skull.  It  is  a 
notch  at  the  apex  of  the  petrosal  converted  into  a  foramen  by  the  tentorium.  The  main  trunk  of 
the  trigeminal  nerve  with  the  small  motor  root  traverses  it  to  entet"  the  Meckelian  cave. 

G.  Petro-sphenoidal. — This  is  a  notch  between  the  sidt;  of  the  dorsum  ephippii  and  apex 
of  the  ))etrosal  which  Itecoines  converted  into  a  foramen  by  dura  mater. 

7.  Optic. — This  foramen  is  formed  by  the  confluence  of  the  orbito-  and  pre-sphenoidal  centres. 
It  opens  into  the  orbit  and  transmits  the  optic  nerve  and  ophthalmic  artery. 

The   Secondary   Nerve-foramina 

Foramina  transmitting  the  various  subdivisions  of  the  fifth  nerve. — The  primary  foramen 
of  exit  i'or  the  trigcininal  nerve  is  formed  partly  of  bone  and  partly  of  membrane  at  the  apex  of 
the  petrosal.     'I'lu;  three  divisions  of  the  nerve  issue  through  secondary  foramina. 

(a)  The  sphenoidal  fissure  is  an  elongated  chink,  bouiidc(l  above  by  the  orbital  wing  and 
below  by  the  greater  wing  of  the  sphenoid,  internally  by  the  body  of  the  sphenoid,  and  externally 
by  the  frontal.  It  opens  into  the  orbit,  and  transmits  the  third,  fourth,  first  (ophthalmic) 
division  of  the  fii'tji,  and  sixth  nerves,  also  the  ophthalmic  vein. 

(/>)  The  foramen  rotundum  is  the  only  exception  to  the  rule  relating  to  the  formation  of 
ncrvij-foraniina :  it  is  i)robably  a  segment  of  the  sphenoidal  fissure.  The  foramen  is  really  a 
canal  running  from  the  middle  cranial  fossa  to  the  spheno-niaxillaiy  fossa,  and  transmits  the 
second  or  maxillary  <livision  of  the  trigeminal. 

(c)  The  foramen  ovale  at  birth  is  a  gap  in  the  hinder  border  of  the  greater  wing  (ali-sphe- 
noid)  of  the  sphcMioid,  and  is  converted  into  a  Ibramen  by  the  petrosal  ;  subse(|uently  it  becomes 
complete  in  the  si)henoid.  It  transmits  the  third  or  mandibular  division  of  the  trigeminal  and 
the  small  or  motor  root,  the  small  superficial  jietrosal  nerve  (which  occasionally  jjasses  through 
a  separate  foramen),  and  the  small  meningeal  artery  with  its  vv.uie  comites. 


MORPHOLOGY  OF  THE  SKULL  97 

The  ethmoidal  canals. — Tlicf^e  eouiinence  in  the  suture  between  the  os  }ilanuiu  and  the 
frontal  l)(ine,  and  traverse  the  sjiaee  between  the  upper  surface  of  the  hiteral  mass  of  the  ethmoid 
and  the  liorizontal  phite  of  the  frontal,  to  emerge  on  the  eribriform  plate  ;  they  are  situated 
outside  the  dura  mater.  The  anterior  foramen  transmits  the  nasal  branch  of  the  ophthalmic, 
which  subse(|uently  gains  the  nasal  cavity  by  passing  through  the  nasal  slit  (ethmoidal  fis.sure) 
by  the  side  of  the  crista  galli. 

The  infraorbital  canal  indicates  the  line  of  confluence  of  the  maxillaiy  and  malar  centres  of 
the  superior  maxilla;  occasionally  it  is  completed  by  the  malar;  rarely  it  is  incijmplete  above, 
and  communicates  by  a  narrow  fissure  with  the  orbit.  It  lodges  the  infraorbital  nerve  and 
artery. 

The  spheno-malar  foramen  is  situated  in  the  suture  between  the  malar  and  the  greater 
wing  of  the  sphenoid  (ali-sphenoid) ;  it  transmits  the  temporal  branch  of  the  orbital  nerve  an<l 
a  branch  of  the  lachrymal  artery.  In  the  adult  this  Ibramen  may  be  wholly  confined  to  the 
malar  bone. 

The  malar  canals  traverse  the  malar  bone,  and  indicate  the  line  of  confluence  of  the  two 
chief  centres  for  this  bone.  The  malar  twigs  of  the  orbital  nerve  i.ssue  from  them  accompanied 
by  arterial  twigs. 

The  spheno-palatine  foramen  is  a  deep  groove  between  the  orbital  and  sphenoidal  processes 
of  the  palate  bone,  converted  into  a  foramen  by  the  sphenoidal  turbinal.  It  is  traversed  by  the 
naso-i)alatine  nerv(!  and  arterj'  as  they  enter  the  nasal  from  the  spheno-maxillary  fossa. 

Scarpa's  foramina  are  two  minute  openings  in  the  meso-palatine  suture  where  it  is  in  relation 
with  the  anteri(n'  i>alatine  fossa.     Thej'  are  traversed  by  the  naso-palatine  nerves. 

The  pterygo-palatine  foramen  is  situated  between  the  sphenoidal  process  of  the  palate  bone, 
the  inter'ial  pteryg(jid  [ilate  of  the  sphenoid,  and  the  sphenoidal  turbinal.  The  pterj'go-palatine 
nerve  and  aitery  jiass  through  it. 

The  Vidian  canal  is  trumpet-shaped  :  the  narrower  end  is  situated  in  the  sphenotic  foramen  ; 
the  broader  orifice  opens  on  the  itosterior  wall  of  the  spheno-maxillary  fossa.  The  canal  is  ]0 
mm.  long  ;  in  the  foetal  skull  it  is  a  chink  between  the  base  of  the  internal  jjteiygoid  plate,  the 
ali-sphenoid,  and  the  lingula  of  the  sphenoid.  The  canal  is  traversed  by  the  Vidian  branch  of 
the  spheno-palatine  ganclion  and  the  Vidian  arteiy. 

The  posterior  palatine  canal  is  a  passage  left  between  the  maxilla,  the  vertical  plate  and 
tuberosity  of  the  palate  bone,  and  the  internal  pterygoid  plate  ;  it  commences  on  the  hard  jialate 
by  the  posterior  palatine  foramen.  The  descending  palatine  nerve  and  ailery  traverse  this  canal. 
Several  f(»ramina  ojien  from  it.  In  the  suture  between  the  vertical  plate  of  the  jialate  bone  and 
the  maxilla,  two  small  oj»enings  allow  minute  nerves  to  issue  for  the  middle  and  inierior  turbinal.s. 
In  the  fissures  between  the  tuberosities  of  the  palate  and  maxillae,  and  the  pteiygoid  plates,  the 
middle  and  external  palatine  nerves  i.ssue.  These  foramina  are  sometimes  called  accessory  and 
external  palatine  canals. 

The  mandibular  or  inferior  dental  canal  runs  between  the  dentary  and  splenial  elements  of 
the  mandible.  The  po.sterior  orifice  of  the  canal  is  the  mandibular  (inferior  dental)  foramen  ; 
the  anterior  orifice,  the  mental  foramen,  indicates  the  line  of  union  of  the  mento-Meckehan  and 
dentary  centres.  The  mandibular  nerve  and  artery  enter  the  canal  at  its  posterior  orifice  ;  the 
mental  foramen  allows  the  mental  nerve  to  escape  from  the  canal  accompanied  by  the  mental 
artery. 

Foramina  transmitting  the  facial  nerve  and  its  branches. — The  main  trunk  of  the  facial 
enters  the  internal  auditory  meatus  and  traverses  the  Fallopian  canal.  In  the  early  embryo  the 
neiTe  lies  on  the  petrosal,  and  is  not  covered  in  with  bone  until  the  fifth  month  of  foetal  life. 
The  terminal  orifice,  the  stylo-mastoid  foramen,  is  situated  between  the  tjTiipanic,  tympano- 
hyal,  and  epiotic  elements  of  the  comjilex  temporal  bone. 

The  '  iter  chordae  posterius  '  is  a  chink  between  the  squamosal  and  the  tj'nipanic  elements, 
and  allows  the  chorda  tympani  nerve  to  enter  the  tympanum.  The  fissure  of  exit  for  this  nerve 
is  the  subdivision  of  tlie  Glaserian  fissure  termed  the  canal  of  Huguier,  or  'iter  chordae 
anterius.'  The  Glaserian  fissure  lies  between  the  tj^mpanic  plate  and  the  sf|uamosal.  It  trans- 
mits the  tympanic  branch  of  the  internal  maxillary  artery,  and  lodges  the  slender  process  of  the 
malleus. 

The  spheno-maxillary  fissure  is  situated  between  the  posterior  border  of  the  orbital  plate  of 
the  maxilla  and  a  smooth  ridge  on  the  orbital  surface  of  the  greater  wing  of  the  sphenoid.  It 
transmits  the  superior  maxillary  division  (second)  of  the  fifth  nerve. 


98  THE  SKELETON 


THE  RIBS  AND  STERNUM 

The  ribs. — These  fonn  a  series  of  narrow  ilattened  hones,  twenty-four  in 
nuniher,  arranged  in  tweh'e  ]iairs,  extending  from  the  sides  of  the  thoraeie  vertehne 
towards  the  median  line  on  the  anterior  as})ect  of  the  trunk. 

The  lirst  seven  pairs  are  termed  true  ribs,  lieeause  their  anterior  ends  are 
direetly  eoimected  by  means  of  cartihige  with  the  sides  of  the  sternum.  The  lower 
five — false  ribs — are  classed  into  two  sets:  the  eighth,  ninth,  and  tenth  are 
connected  together  l:)y  their  costal  cartilages;  the  eleventh  and  twelftli  have  their 
anterior  extremities  free,  and  are  called  in  consequence  floating  ribs.  Thus  the 
first  seven  are,  vertebro-sternal ;  the  eighth,  ninth,  and  tenth,  vertebro-chon- 
dral ;  the  eleventh  and  twelftli.  vertebral  ribs. 

The  rihs  increase  in  length  from  the  first  to  the  seventh,  and  then  decrease  from 
this  rib  to  the  twelfth. 

In  l)readth  they  increase  frc^m  liehind  forwards;  the  greatest  In-eadth  of  a  rih  is 
at  its  junction  with  the  costal  cartilage.  The  two  or  three  upper  ribs  form  nearly 
a  right  angle  with  the  spine,  Init  the  succeeding  set  curve  obliquely  downwards. 
The  ol)liquity  is  greatest  at  the  ninth,  and  then  decreases  in  the  ribs  below. 

Typical  characters  of  a  rib. — The  seventh  is  regarded  as  the  most  typical  ril). 
It  presents  a  vertebral  extremity  or  head ;  a  narrow  portion  or  neck ;  a  sternal 
end;  and  an  intermediate  portion,  the  shaft. 

The  head  has  two  facets  divided  by  a  horizontal  crest.  The  crest  is  connected 
by  an  interosseous  ligament  with  an  intervertebral  disc;  the  facets  articulate  with  the 
demi-facets  on  the  sides  of  the  liodies  of  two  vertebrae.  As  a  rule,  the  lower  facet 
is  the  larger,  and  articulates  with  the  thoracic  vertebra,  to  which  the  rib  corresponds 
in  num])er.  This  is  the  primary  facet,  and  is  the  one  represented  in  those  ribs 
which  possess  only  a  single  facet  on  the  rib-head.  The  anterior  margin  is  lipped 
for  the  costo- vertebral  (stellate)  ligament. 

The  neck  is  that  portion  of  the  ril^  extending  from  the  head  to  the  tubercle. 
The  posterior  surface  of  the  neck  is  in  relation  with  the  transverse  process  of  the 
lower  vertebra  with  which  the  head  articulates;  it  forms  the  anterior  boundary  of 
the  costo-transverse  foramen,  and  is  rough  where  it  gives  attachment  to  the 
middle  costo-vertel)ral  ligament.  The  superior  liorder  of  the  neck  is  continuous 
with  the  corresponding  border  of  the  shaft,  and  at  the  point  where  the  neck  ends 
this  border  is  produced  so  as  to  form  a  crest  (crista  colli  superior)  for  tlie  anterior 
costo-transverse  ligament.  The  inferior  border  of  the  neck  is  continuous  with  the 
ridge  of  the  subcostal  groove.  This  difference  in  the  relation  of  the  neck  to  the 
upper  and  lower  l)i)rders  of  the  ril)  shaft  is  useful  in  determining  to  which  side  a 
rib  belongs. 

The  tubercle  consists  of  an  upper  part,  rough  for  the  posterior  costo-transverse 
(rhomboid)  ligament,  and  a  lower  faceted  portion  for  articulation  with  the  ti})  of 
the  transverse  process.  The  tubercle  projects  below  the  lower  edge  of  the  ril)  to 
form  a  crest  (crista  colli  inferior),  marking  the  beginning  of  the  subcostal  groove. 

The  shaft  has  two  surfaces  and  two  borders.  It  is  strongly  curved.  At  first 
the  curve  is  in  the  same  i)lane  as  the  neck,  but  it  quickly  turns  forwards  at  a  si)ot 
on  the  i)osterior  surface  of  the  shaft  known  as  the  angle,"  where  it  gives  attachment 
to  the  sacro-luiithalis  muscle  and  some  of  its  subdivisions.  The  rib  has  also  a  second 
or  ui)ward  curve  beginning  at  the  angle.  These  curves  are  expressed  by  describing 
the  main  curve  as  disposed  around  a  vertical,  and  the  second  or  ujiward  curve 
around  a  transverse  axis. 

When  a  rib,  except  the  first  and  twelfth,  is  laid  Avith  its  lower  edge  uj^on  the 
table,  the  rib-head  rises  and  the  rib  touches  the  table  at  two  places,  viz.  at  tlie 
sternal  end,  and  in  the  neighbourhood  of  the  angle. 

The  external  surface  of  the  ril)  is  convex,  and  gives  attachment  to  muscles. 
Near  its  anterior  extremity  it  forms  a  somewhat  abrui)t  curve,  indicated  by  a  ridge 
on  the  bone,  Avhicli  gives  attaclunent  to  the  serratm  magnus  nmscle,  and  is  some- 
times called  the  anterior  angle. 


THE  RIBS 


99 


The  internal  surface  is  concave  and  presents  the  subcostal  groove  near  its 
inferior  border.  Tlie  groove  is  best  marked  near  the  angle,  and  lodges  the  inter- 
costal vessels  and  nerves.  The  ridge  limiting  the  groove  above  is  continuous  witli 
the  inferior  border  of  the  neck  of  the  rib;  its  gives  attachment  to  the  hitniuil 
intercostal  muscles. 


Fig.  108.— The  Sevexth  Rib  of  the  Left  Side.     (Seen  from  lielow.) 


SUBCOSTAL  GR03VE 


ARTICULAR    PORTION 
OF  TUBERCLE 


STERNAL  END  FOR  COSTAL  CARTILAGE 


The  superior  border  is  rounded,  and  affords  attachment  to  the  internal  and 
external  intercodal  muscles.  The  inferior  border  commences  abruptly  near  the 
angle,  and  gives  attachment  to  the  external  intercostal  muscles. 

The  sternal  end  of  the  shaft  is  cupped  for  the  reception  of  tlie  costal  car- 
tilay-e. 


K.K) 


THE  SKELETON 


TIk'   si'venth   rib   and   its  costal   cartilage   give   attachment   to   the    following 
muscles  : — 


Internal  intereostals  (sixth  and  seventh). 
External  intercostals  (sixth  and  seventh). 
Levatores  costarum  (seventh). 
Infracostal  (when  present). 
Diaphragm. 
Transversalis. 


External  oblique  abdominis. 
Rectus  abdominis  (costal  cartilage). 
Triangularis  sterni  (costal  cartilage). 
8erratus  magnus. 
Ilio-costalis,  or  sacro-lumbalis. 
Musculus  accessorius. 


Longissimus  dorsi. 
It  gives  attachment  to  the  folloAving  ligaments  : — 


Anterior  costo-vertebral   or   costo- 

central  (stellate). 
Middle  costo-transverse  (interosseous) 
The  capsular. 

Fig.  109.— First  and  Second  Ribs 


Superior  costo-transverse. 

Posterior  costo-transverse  (rhomboid). 

The  interarticular. 


Levator  eostje  and 
accessorius 


Scalenus  medius 


GROOVE  fOR  SUBCLAVIAN 
ARTERY 


Scalenus  antieu; 


GROOVE  FOR  SUBCLAVIAN 
VEIN 


Levator  eostae 
Accessorius 

(insertion) 
Cervicalis  ascendens 

(origin) 
Serratus  posticus 

superior 

'insertion) 

Scalenus  posticus 


Third  digitation  of 
serratus  magnus 


External 
intercostals 


Blood-supply. — Tlie  ril)s  are  very  vascular  and  derive  numerous  branches  from 
the  intercostal  arteries.  The  branches  in  the  shaft  run  towards  the  rib-head.  Those 
of  the  head  and  neck  take  a  contrary  direction,  and  run,  as  a  rule,  towards  the 
shaft.  In  tlie  neighljourhood  of  the  tuberosity  the  vessels  seem  to  run  in  any 
direction. 

Peculiar  ribs. — Several  of  the  ribs  differ  in  many  particulars  from  tliis  general 
description.     Tlicy  are  the  first,  second,  tenth,  eleventh,  and  twelfth. 

The  first  rib  is  the  broadest  and  most  sharplv  curved.  The  head  is  small,  and, 
as  a  rule,  is  furnished  with  only  one  articular  "facet.  The  tubercle  is  large  and 
l.roininent,  the  neck  narrow.  The  shaft  is  broad,  has  no  angle,  and  is  curved 
around  a  vertical  axis  only.  The  upper  surface  presents  two  shallow  grooves 
separated  near  the  inner  border  by  a  rough  surface  (Lisfranc's  or  Scalene  tubercle) 


Tin-:  RIBS 


101 


for  the  scalenus  anticus  muscle.  The  groove  in  front  of  this  surface  is  for  the  sub- 
clavian vein,  the  groove  behind  it  is  for  the  subclavian  artery.  Between  the  groove 
for  the  artery  and  the  angle  there  is  a  rough  surface  for  the  scalenus  medius  muscle; 
anterior  to  this  rough  surface  and  close  beside  the  groove  is  an  area  from  which  the 
first  digitation  of  the  serratus  magnus  takes  origin.  The  under  surface  is  smooth 
and  lacks  a  groove.  The  outer  border  is  thick,  and  rounded  for  the  internal  and 
external  intercostal  muscles. 

The  costal  cartilage  of  this  rib  fuses  Avith  the  manubrium  of  the  sternum;  occa- 
sionally the  sternal  extremity  and  costal  cartilage  of  this  rib  are  rei»laced  by  fibrous 
tissue. "  When  a  well-developed  cervical  rib  is  present,  the  head  of  the  first  may 
present  two  facets  as  in  a  typical  rib. 

The  first  rib,  with  its  costal  cartilage,  gives  attachment  to  the  following 
muscles  : — 


Internal  intercostal. 
External  intercostal. 
Levator  costee. 
Scalenus  anticus. 
Scalenus  medius. 


Sul»clavius  (costal  cartilage). 
Sterno-hyoid  (costal  cartilage). 
Pectoralis  major  (costal  cartilage). 
Serratus  magnus. 
Musculus  accessorius. 


Fig.  110. — The  Vertebral  Ends  of  Texth.  Elevexth,  axd  Twelfth  Ribs. 

ANGLE 


SINGLE  FACET  (SOMETIMES 
TWO  FACETS  ARE  PRE- 
SENT) 


SINGLE    FACET     (THIS  RIB 

HAS   AN    ANGLE.   BUT  NO 

TUBEROSITY       AND  NO 
NECXi 


SINGLE  FACET  (THIS  RiB 
HAS  NEITHER  TUBER- 
OSITY, ANGLE,  NOR  NECKl 


xn 


Blood-supply, — This  is  derived  mainly  from  the  superior  intercostal  branch  of 
the  subclavian  artery. 

The  second  rib,'  like  the  first,  is  strongly  curved;  its  posterior  angle  is  faintly 
marked;  and  the  shaft,  like  that  of  the  first,  can  lie  flat  on  the  table.  It  has  a 
prominent  anterior  angle  for  the  serratus  magnus. 

It  gives  attachment  to  the  following  muscles  : — 

Internal  intercostals  (first  and  second).  Serratus  magnus. 

External  intercostals  (first  and  second).  Serratus  posticus  superior. 

Levator  costse.  Scalenus  posticus. 

Pectoralis  major  (costal  cartilage).  Musculus  accessorius. 

Cer\acalis  ascendens. 

Blood-supply. — ^Superior  intercostal  branch  of  the  subclavian  artery,  and  the 
first  aortic  intercostal. 


102 


THE  SKELETON 


The  tenth  rib  lias  usually  a  single  facet  on  its  head.  Occasionally  a  second  is 
}»resent.  When  this  is  the  case,  the  ninth  thoracic  vertebra  is  not  exceptional,  and 
presents  two  (U-nn-facets. 

The  eleventh  rib  has  a  single  facet  on  the  head.  The  angle  is  feebly  marked, 
and  the  subcostal  groove  shallow.     It  lacks  a  neck  and  tubercle. 

The  twelfth  rib  has  a  large  head  furnished  with  one  facet.  The  shaft  is 
narrow,  and  its  length  extremelv  variable.  It  may  be  as  short  as  3  cm. ,  or  attain 
a  length  of  20  cm.  (8"). 

Tlie  twelfth  rib  eives  attachment  to  the  following  muscles: — 


Internal  intercostal. 
External  intercostal. 
Levator  costfe. 
Diaphragm. 

Transversalis  abdominis. 
External  oblique. 


Internal  oblique. 
Serratus  posticus  inferior. 
Musculus  accessorius. 
Sacro-lumbalis  or  ilio-costalis. 
Erector  spinae. 
Quadratus  lumborum. 
Latissimus  dorsi. 


Fig.  111. — Rib  at  Puberty. 


EPIPHYSIS  FOR  THE  HEAD.     APPEARS  AT 
FIFTEEN  ;  FUSES  AT  TWENTY-THREE 


EPIPHYSIS  FOR  TUBERCLE.     APPEARS  AT 
FIFTEEN;  FUSES  AT  TWENTY-THREE 


THE  CARTILAGINOUS  SHAFT  COMMENCES  TO  OSSIFY 
AT  THE  EIGHTH  WEEK  OF  INTRA-UTERINE  LIFE 


Tiic  costal  cartilages  are  bars  of  hyalin<'  cartilage  attached  to  the  anterior 
extremities  of  the  ribs;  they  represent  unossified  epiphyses.  Like  the  shaft  of 
a  ril),  each  has  an  outer  and  inner  surface;  the  outer  surfaces  give  origin  and 
insertion  to  large  muscles;  and  the  inner  surfaces,  from  the  second  to  the  seventh 
inclusive,  are  in  relation  with  the  triangularw  sterni.  The  upper  and  lower  borders 
serve  for  the  attachment  of  the  internal  intercostal  muscles.  The  upper  seven 
cartilages,  and  occasionally  the  eighth,  are  connected  with  the  sternum.  The  first 
fuses  with  the  manubrium;  the  remaining  six  are  received  in  small  articular  con- 
cavities, and  retained  by  means  of  Hgaments.    The  cartilages  of  the  vertebro-chondi-al 


THE  RIBS 


Wi 


ribs  are  united  to  one  another  and  to  the  seventli  costal  cartilage  by  ligaments 
(sometimes  by  short  vertical  bars  of  cartilage),  and  those  of  the  vertebral  ribs  end 
freely.  The  inner  surfaces  of  the  lower  six  afford  attachment  to  the  diaphragm 
and  the  transversal  is  muscle. 

The  second,  third,  fourth,  and  fifth  costal  cartilages  articulate  with  tlie  sides  of 
the  sternum,  at  a  spot  corresponding  to  the  junction  of  two  sternebne.  The  sixtli 
and  seventh  (and  eighth  when  this  reaches  the  sternum)  are  arranged  irregularly. 
As  a  rule  the  sixth  lies  in  a  recess  in  the  side  of  the  fifth  sternebra;  the  seventh 
corresponds  to  the  line  of  junction  of  the  meso-  and  metasternum;  and  the  eighth 
articulates  with  the  metasternum  (see  fig.  112). 

Blood-supply. — The  twigs  for  the  costal  cartilages  are  derived  from  the  terminal 
twigs  of  the  aortic  intercostals,  and  from  the  internal  mammary  arteries. 

Development. — At  the  eighth  week  of  intra-uterine  life  the  ribs  are  cartilag- 
inous. About  this  date  an  earthy  spot  appears  near  the  angle  of  each  rib,  and 
spreads  with  great  rapidity  along  the  shaft,  and  by  the  fourth  month  reaches  as  far 
as  the  costal  cartilage;  the  proportion  borne  1)y  the  rib-shaft  to  the  costal  cartilage  is 
about  the  same  at  this  date  as  in  adult  life.  Whilst  the  ribs  are  in  a  cartilaginous 
condition,  eight  of  them  reach  the  sternum;  even  after  ossification  has  taken  place, 

Fio.  112. — The  Thorax  at  the  Eighth  Month. 
(On  the  left  side  eight  cartihiges  reach  the  sternum.) 


the  costal  cartilage  of  the  eighth  rib,  in  many  instances,  articulates  with  the  sternum 
as  late  as  the  eighth  month  (fig.  112).  This  relationship  ma}'  persist  through  life, 
but  usually  the  cartilage  retrogresses,  and  is  replaced  by  ligamentous  tissue.  About 
the  fifteenth  year  a  secondary  centre  appears  for  the  head  of  each  rib,  and  a  little 
later  one  makes  its  appearance  for  the  tubercle,  except  in  the  tenth,  eleventh,  and 
twelfth  ribs.  The  secondary  centres  fuse  with  the  ribs  about  the  twenty-third 
year.  The  rib-shaft  increases  in  length  mainh*  at  its  line  of  junction  Avith  the 
costal  cartilage. 

Variations  in  the  y^umber  and  Shape  of  the  Ribs 

The  ribs  may  be  increased  in  number  by  addition  either  at  the  cervical  or  lumbar  end  of  the 
series,  but  it  is  extremely  rare  to  find  an  additional  rib  or  pair  of  ribs  in  both  the  cervical  and 
lumbar  regions  in  the  same  subject. 

Cervical  ribs  are  fairly  common ;  as  a  rale  thej'  are  of  small  size  and  rarely  extend  more 
than  a  few  millimetres  beyond  the  extremity  t)f  the  transverse  process.  Occasionally  they 
exceed  such  insignificant  proportions  and  reach  as  far  as  the  sternum  :  between  these  two  ex- 
tremes many  varieties  occur.  As  a  rule,  the  existence  of  a  cervical  rib  is  not  detected  until  the 
skeleton  is  macerated  ;  hence  we  know  little  of  the  correlated  arrangement  of  soit  parts.  In 
one  fortunate  case  Turner  was  able  to  make  a  thorough  dissection  of  a  specimen  in  which  a 
comi»lete  cei-vical  rib  existed.  Its  head  articulated  with  the  body  of  the  seventh  cervical  ver- 
tebra and  had  a  stellate  ligament.  The  tuberele  was  well  developed,  and  articulated  with  the 
transverse  process.     The  costal  cartilage  blended  with  that  of  the  first  thoracic  rib,  and  gave 


104  THE  SKELETON 

attachiiieiit  to  the  costo-clavicular  ligament.  Between  it  and  the  first  thoracic  rib  there  was  a 
well-marked  intercostal  space  occupied  by  intercostal  muscles.  It  received  the  attachment  of  tlie 
S(utleniis  miticiis  and  innlins  muscles,  and  it  was  crossi'd  by  the  subclavian  artery  and  vein.  The 
nerves  of  the  intercostal  space  were  supplied  in  pint  by  the  eiglith  cervical  and  tir.^t  dorsal,  'i'he 
artery  of  the  space  was  derived  from  the  dee])  cervical,  which,  with  the  superior  intercostal, 
arose  from  the  root  of  the  vertebral.  The  head  of  the  first  thoracic  lib  in  this  specimen  articu- 
lated with  the  seventh  cervical,  as  well  as  with  the  first  thoracic  vertebra.  An  interesting  fact 
is  also  recorded  in  the  careful  account  of  this  specimen  : — There  was  no  movable  twelfth  thoracic 
rib  on  the  same  side  as  this  well-developed  cervical  rib,  and  the  twelfth  thoracic  vertebra  had 
mammillary  and  accessory  processes,  and  a  strong  elongated  costal  process,  and  was  in  linear 
series  with  the  lumbar  transverse  processes. 

Grnl)er  and  Turner  from  a  careful  and  elaborate  study  of  this  question  summarise  the  varia- 
tions in  the  cervical  rib  thus  : — It  may  be  very  short  and  possess  only  a  head,  neck,  and  tubercle. 
A\'lu'n  it  extends  l)eyond  the  transverse  process,  its  shaft  may  end  freely  or  join  the  first  thoracic 
rib  :  this  union  may  be  effected  bj'  bone,  cartilage,  or  ligament.  In  very  lare  instances  it  may 
have  a  costal  cartilage  and  join  the  manubrium  of  the  sternum.  Not  unfrequently  a  jirocess, 
or  eminence,  exists  on  the  first  thoracic  rib  at  the  spot  when  it  articulates  with  a  cervical  rib. 

Lumbar  ribs  are  of  less  significance  than  cervical  ribs  and  rarely  attain  a  great  length. 
Their  jiresence  is  easilj'  accounted  for,  as  they  are  the  diff"erentiated  costal  elements  of  the  trans- 
verse processes.  They  are  never  so  complete  as  in  ceiTical  ribs,  and  articulate  only  with  the 
tran.sverse  processes ;  the  head  never  reaches  as  far  as  the  body  of  the  vertebra,  and  there  is  no 
neck  or  tubercle.     An  extra  levator  casta'  muscle  is  associated  with  a  lumbar  rib. 

Not  the  lea.st  interesting  variation  of  a  rib  is  that  known  as  the  bicipital  rib.  This  condi- 
tion is  seeti  exclusively  in  connection  with  the  first  thoracic  rib.  The  vertebral  end  consists 
of  two  limbs  which  lie  in  different  transverse  planes.  These  bicipital  ribs  have  been  especially 
studied  in  whales  and  man.  This  abnormality  is  due  to  the  fusion  of  two  ribs,  either  of  a 
cervical  rib  with  the  shaft  of  the  first  thoracic  ;  or  the  more  common  form,  the  fusion  of  the  first 
and  second  true  ribs. 

Among  unu.sual  variations  of  ribs  should  be  mentioned  the  replacement  of  the  costal  cartilage 
ami  a  portion  of  the  rib-shaft  by  fibrous  tissue,  a  process  which  occurs  as  a  normal  event, 
during  development,  in  the  eighth  rib. 

Sometimes  the  shafts  of  two  or  more  ribs  may  become  united  by  small  quadrilateral  jilates 
of  bone  extending  across  the  intercostal  spaces. 

The  sternum  is  a  thin  flat  bone  situated  in  the  anterior  wall  of  the  thorax.  In 
the  young  subject  it  consists  of  six  pieces,  or  sternebrae.  Of  these,  the  four  middle 
fuse  together  to  form  the  gladiolus  (mesosternum);  the  superior  remains  distinct 
throughout  life  as  the  manubrium  (pre-sternum);  and  the  lower  segment,  also 
distinct  until  very  advanced  life,  is  the  xiphoid  (metasternum).  The  anterior 
surface  of  the  adult  sternum  is  convex,  and  gives  origin  to  the  pedoralis  major  nmscle 
of  each  side;  near  its  superior  angle  the  sterno-mastoirl  muscle  arises.  This  surface 
is  traversed  by  five  lines,  indicating  the  former  segmentation  of  this  bone.  The 
posterior  surface  is  concave,  and  traversed  by  five  lines  corresponding  to  those  on 
the  anterior  surface.  At  the  upper  part  it  gives  origin  to  the  sterno-hyoid  and  sterno- 
thyroid muscles.  The  posterior  surface  of  the  lower  four  segments  gives  origin  to 
the  triangularis  .sterni.  The  xiphoid  is  usually  perforated;  a  branch  of  each  internal 
mammary  artery  traverses  the  foramen;  and  on  each  side  of  it  a  portion  of  the 
diaphrayn)  is  attached.  Occasionally  the  xiphoid  is  bifid.  The  superior  border 
presents  the  interclavicular  notch,  to  wliich  the  fibres  of  the  interclavicular  liga- 
ment are  attached;  this  border  terminates  at  each  end  in  an  articular  notch  for  the 
sternal  end  of  the  clavicle.  The  margins  of  the  notch  give  attachment  to  the  sterno- 
cjavicular  ligaments.  The  lateral  borders  of  the  sternum  present  a  series  of  depres- 
sions, which  receive  the  sternal  extremities  of  the  costal  cartilages  of  the  first  seven 
ribs,  and  o(;casionally  that  of  the  eighth  (see  fig.  112).  The  borders  intervening  be- 
tween these  depressions  or  notches  are  in  relation  with  the  internal  intercostal  muscles. 

In  order  to  appreciate  the  nature  of  these  notches,  it  is  advantageous  to  studv 
the  sternum  in  a  young  subject.  Each  typical  sternebra  presents  four  angles;  each 
angle  presents  a  demi-facet.  Between  every  two  sternebric  there  is  an  iiitersterne- 
bral  disc;  when  two*  sternel)ra3  are  in  position,  each  notch  for  a  costal  cartilage  is 
formed  by  a  sternebra  nhovo  and  below  with  an  intersternebral  disc;  in  the  middle, 
thus  repeating  the  relation  of  the  rib-head  to  the  vertebral  centra.  Later  in  life 
thes(>  fuse  more  or  less  together,  except  in  the  case  of  the  first  and  second  sternebraN 
which  usually  remain  sei)arate  to  the  end  of  life.  The  first  (pre-sternum)  is  the 
most  modified  of  all  the  sternebra?.  and  dift'ers  from  them  in  the  fact  that  the  costal 
cartilage  of  the  first  rib  is  continuous  with  it,  and  in  the  fact  that  it  supi>orts  the 


THE  STERNUM 


105 


clavicles.  Occasionally  a  rounded  pisiform  bone  is  seen  on  each  side,  ini mediately 
internal  to  the  articular  notch  for  the  clavicle;  these  are  the  episternal  Ijones. 
The  last  sternebra,  or  xiphoid,  is  the  least  developed  and,  though  calcified  in  old 
age,  rarely  ossifies.  Its  tip  is  directly  continuous  Avith  the  linea  alba,  and  the  base 
gives  slight  attachment  to  the  rectus  abdominis  muscle. 


Fig.  113. — The  Sternum.     (Anterior  view.) 

INTERCLAVICULAR  NOTCH 


CLAVICULAR  NOTCH 


FOR  FIRST  COSTAL  CARTILAGE 


XIPHOID  FORAMEN 


Sterno-mastoid 


MANUBRIUM  OR  PRE-3TERNUM 


Pectoralia  major 


3LADI0LUS  OR  MESOSTERNUM 


Rectus  abdominis 


Aponeurosis  of  trausversalis 
and  external  oblique 


XIPHOID  OR  METASTERNUM 


The  following  muscles  are  attached  to  the  sternum  :- 


Pectoralis  major. 
Sterno-cleido-mastoid. 
Internal  intercostals. 
Kectus  abdominis. 


Triangularis  sterni. 
Transversalis. 
Diaphragm. 
Sterno-hvoid. 


Sterno-thvroid. 


lOG 


THE  SKELETON 


Ligaments.— In  addition  to  the  ligaments  proper  to  the  costal  cartilages,  the 
following  require  enumeration : — 

Interclavicular.  Posterior  storno-clavicular. 

Anterior  gtcrno-clavicular.  Interarticular  fibro-cartilage. 

Linea  alba. 


Fig.  114.— The  Steknum.     (Posterior  view.) 


CLAVICULAR  NOTCH 

Sterno-hyoid 

Sterno-thyroid 


TriangulariE  atemi 


Diaphragm 


FOR  ?lnST  COSTAL  CARTILAGE 


Blood-supply.— Tlie  arteries  of  the  sternum  are  derived  mauily  from  the 
internal  nianimarv  arteries  by  direct  l^ranches  termed  sternal:  many  twigs  are 
furnished  by  the  perforating  "branches  of  the  internal  mammary,  and  also  by  the 
terminal  twigs  of  the  aortic  intercostals.  ,       i      *  +v,o 

Development.— The  sternum  results  from  the  fusion  of  the  ventral  ends  oi  tne 


THE  STKRM-M 


10/ 


cartilaginous  bars  which  in  the  early  embryo  represent  the  ribs.  At  first  these 
bars  fuse  together  laterally,  and  for  some  time  the  sternum  is  represented  by  two 
strips  of  cartilage  separated  by  a  median  fissure.  Very  early  this  gap  is  bridged 
over  anteriorly.  Nine  costal  cartilages  are  in  relation  with  the  sternum  at  this 
stage.  Gradually  the  lateral  strips  unite  with  each  other  to  form  the  mesosternum. 
The  ninth  costal  cartilage  divides:  one  part  remains  attached  to  the  sternum  and 
becomes  the  xiphoid,  Avhilst  the  end  still  attached  to  the  rib  acquires  a  new  attach- 
ment to  the  eighth  cartilage.  The  ends,  still  adherent  to  the  sternum,  may  remain 
separate  and  give  rise  to  a  bifid  metasternum  (xiphoid);  much  more  frequently 
they  unite,  leaving  a  small  foramen.  The  eighth  cartilage  may  retain  its  sternal 
attachment  permanently. 

At  first  the  sternum  and  costal  cartilages  are  continuous;  a  Joint  soon  forms 
between  the  pre-sternum  and  mesosternvim.  Gradually  joints  arise  between  the 
costal  cartilages  and  the  sternum  (except  in  the  case  of  the  first).  The  division 
of  the  mesosternum  into  sternebrse  is  a  still  later  process,  and  arises  during  the 
process  of  ossification. 

Ossification. — The  transformation  of  the  sternum  into  bone  is  a  slow  and 
irregular  process.  The  pre-sternum  (manubrium)  has  a  mesial  nucleus  about  the 
sixth  month  of   intra-uterine  life;    later,   several   smaller   accessory  centres   may 

Fig.  115. — Posteeior  Surface  of  the  Man'ubrium  (Pre-sterxum),  with  Sternal  Exds 
OF  Clavicle  and  the  First  Costal  Cartilage. 


Sterno-hyoid 


Sterno-thyroid 


appear.  The  mesosternum  usually  ossifies  from  seven  centres.  The  second  sterne- 
bra  ossifies  from  a  single  median  nucleus  about  the  eighth  month.  Below  this, 
three  pairs  of  ossific  nuclei  appear,  and  they  may  remain  long  separate.  Of  these, 
two  pairs  for  the  third  and  fourth  sternebrae  are  visible  at  birth.  The  pair  for  the 
fifth  sternebra  make  their  appearance  towards  the  end  of  the  first  year.  The 
various  lateral  centres  unite  in  pairs,  and  at  the  sixth  year  the  sternum  consists  of 
six  sternebrie,  the  lowest  (metasternum)  being  cartilaginous.  Gradually  the  four 
pieces  re])resenting  the  mesosternum  fuse  with  one  another,  and  at  twenty-five  they 
form  a  single  piece,  but  exhibit,  even  in  advanced  life,  traces  of  their  original 
separation. 

The  metasternum  is  always  imperfectly  ossified,  and  does  not  ankylose  with  the 
mesosternum  till  after  middle  life.  The  pre-sternum  and  mesosternum  rarely  fuse. 
The  dates  given  above  for  the  various  nuclei  are  merely  approximate,  for  they 
are  extremely  variable,  not  only  in  appearing,  but  in  their  number.  The  same 
remark  ajjplies  also  to  the  age  at  which  the  various  segments  ankylose;  hence  the 
sternum  affords  very  uncertain  data  as  to  age. 

Abnormalities  of  the  sternum. — The  mode  of  development  of  the  sternum  as 
described  above  is  of  importance  in  connection  with  some  deviations  to  which  it  is 
occasionally  sul)ject.  At  an  early  jjcriod  it  consists  of  two  lateral  halves;  in  some 
rare  instances  these  have  failed  to  unite,  and  thus  give  rise  to  the  anomaly  of  a 


lOS 


THE  SKELETON 


completely  cleft  t^ternuni.  The  union  of  the  two  halves  may  occur  in  the  region  of 
the  manul)riuni,  but  fail  below  this  point;  in  some  instances  the  upper  and  lower 
segments  have  duly  coalesced  with  the  opposite  side,  but  union  has  failed  in  the 
middle  segments.  The  clefts  resulting  from  these  failures  of  coalescence  are  in 
manv  instances  so  small  as  not  to  be  of  anv  moment,  and  not  even  recognised  until 


Fii;.  llfi.— Two  Stages  ix  the  Fokmatiox  of  the"  Cartilaginous  Sternum.     (After  Ruge.) 


CLAVICLE    /       y 


B 


the  skeleton  has  been  prepared.  In  a  few  individuals  they  have  been  so  extensive 
as  to  allow  the  pulsation  of  the  heart  to  be  perceptible  to  the  hand,  and  even  to  the 
ej'e,  through  the  skin  covering  the  defect  in  the  bone. 

A  common  variation  in  the  sternum  is  asymmetr}'  of  the  costal  cartilages. 
Instead  of  corresponding,  the  cartilages  may  articulate  with  the  sternum  in  an  alter- 
nating mamuT.     Tlio  cause  of  this  asymmetry  is  not  known. 


THE  THORAX 


The  thorax  is  a  bony  cage  of  conical  shape,  formed  by  the  thoracic  vertebrae, 
the  ribs  with  their  costal  cartilages,  and  the  sternum.  The  thorax  is  compressed 
antero-posteriorly  so  that  it  measures  less  in  the  sagittal  than  in  the  transverse  axis; 
it  is  also  deeper  posteriorly  than  anteriorly.  Its  jxisterior  boundaries  are  formed 
by  the  thoracic  vertel)ne  and  the  ril)s  as  far  outward  as  their  angles;  the  backward 
curve  of  the  ribs  ])ro(luces  on  each  side  of  the  vertebrse  a  deep  furrow,  the  costo- 
vertebral groove,  in  Avhich  the  erector  spinas  muscle  and  its  subdivisions  are 
lodged. 

The  anterior  boundary  is  formed  b}^  the  sternum  and  costal  cartilages.  This 
surface  is  slightly  convex,  and  has  a  slight  inclination  forwards  in  its  lower 
part. 

The  lateral  boundaries  are  formed  l)y  the  ribs  from  their  angles  to  the  costal 
cartilages. 

The  top  of  the  thorax  presents  an  elliptical  aperture,  the  thoracic  inlet,  Avhich 
measures,  on  an  average,  12-5  cm.  (5";  transversely,  and  6-2  cm.  (2V')  in  its 
sagittal  axis. 

The  lower  opening  of  the  thorax  is  very  irregular,  and  forms  two  curved  lines 


THE  CLAVICLE 


109 


ascondintr  from  tlic  last  rib  to  the  lower  border  of  the  gladiolus  (mesosternuiu). 
These  two  borders  form  the  subcostal  angle,  and  the  xiphoid  (metasternum) 

Fkj.  117.— The  Thorax.     (Frout  view.) 


projects  into  the  middle  of  it.     The  intervals  between  the  ribs  are  the  intercostal 
spares,  and  are  eleven  in  number  on  each  side. 


THE  CLA  VICLE 

The  clavicle  is  a  rod  of  bone  passing  from  the  top  of  the  sternum  to  the  acro- 
mion process  of  the  scapula.  It  presents  two  curves:  an  inner,  with  the  convexity 
ihrected  forwards;  and  an  outer,  the  smaller,  with  the  convexity  directed  back- 
wards. The  clavicle  consists,  for  descriptive  purposes,  of  an  outer  tiattenefl,  and 
an  inner  prismatic  portion. 

The  outer  third  has  two  surfaces  and  two  borders.  The  superior  surface 
looks  directly  upwards,  and  affords  attachment  to  the  trapezius  muscle  posteriorly, 
and  the  dcltirid  anteriorly;  a  small  tract  intervening  between  the  muscles  is  subcu- 
taneous. The  inferior  "surface  is  rough,  and  at  its  most  j)osterior  part  presents 
tlie  tuberosity  (or  conoid  tubercle)  of  tlie  clavicle;  it  overhangs  the  coracoid 
])n)(ess  and  gives  attachment  to  the  conoid  ligament.  From  the  tuberosity  a  ridge, 
the  oblique  line,  runs  outwards  and  forwards;  to  it,  the  trapezoid  ligament  is 
attached.     The  anterior  border  is  thin;  presents  often  a  small  jirominence,  the 


no 


THE  SKELETON 


deltoid  tuberch',  and  gives  origin  to  the  deltoid  muscle.     Tlie  posterior  border  is 
thick  and  rounded;  into  it  the  trapezius  is  inserted. 

The  inner  two-thirds  is  prismatic  in  form;  it  has  three  surfaces  and  three 
borders.  Of  these,  the  anterior  surface  is  convex  and  presents  near  the 
sternal  end  a  rough  surface  for  the  clavicular  portion  of  the  pedoredis  imijor, 
and  a  rough  surface  above  for  the  stenio-cleido-mastoid.  Near  the  middle  of 
the  shaft  it  is  smooth  and  covered  by  the  thin  platysmn  mijoides ;  sometimes  a 
small  canal  passes  at  right  angles  through  this  surface  of  the  clavicle;  it  is  traversed 
l)y  a  cutaneous  l)ranch  from  the  cervical  plexus.  The  posterior  surface  is 
concave,   and   forms  an   arch   over   the   brachial   plexus   and    subclavian   artery. 


Fig.  118.— The  Left  Clavicle.     (Superior  surfiice.) 

AXTERIOr. 

Deltoid  Peetoralis  major 


Trapezius 


PusTKRIOR 


Sterno-mastoid 


The  inferior  surface  commences  externally  as  a  groove  for  the  subclavius,  the 
floor  of  the  groove  being  continuous  with  the  inferior  surface  of  the  outer  third 
of  the  clavicle,  and  frequently  presents  the  orifice  of  the  nutrient  foramen. 
Internally,  this  groove  becomes  very  narrow,  and  runs  on  to  the  rough  surface 
for  the  rhomboid  ligament.  On  the  sternal  side  of  the  rhomboid  impression 
there  is  often  a  facet  where  the  clavicle  plays  on  the  first  costal  cartilage.  Near 
this  facet  the  sterno-Jn/oid  muscle  finds  an  attachment,  and  occasionally  the  sterno- 
thyroid. Of  the  three  borders,  the  superior  separates  the  anterior  and  posterior 
surfaces;  it  is  faintly  marked  toAvards  the  sternal  end;  externally,  it  becomes 
continuous  with  the  posterior  border  of   the  outer  third.     The  anterior  border 


Fig.  119. — The  Left  Clavicle.     (Inferior  surface.) 
Posterior 


Oblique 

line  for 
Capsular        trapezoid    Tuberosity  for 
ligament       ligament    conoid  ligament 


Subolaviua 


Rhomboid 
ligament  and 
Sterno- 
hyoid    Sterno-lbyroid 


FACET  FOR  FIRST 
COSTAL  CARTILAGE 


STERNAL  FACET 


ACROMIAL  FACET 


Peetoralis  major 
Anterior 


separates  the  anterior  and  inferior  surfaces;  it  is  continuous  with  the  anterior 
l)()rder  of  the  flattened  ])ortion.  Tlie  posterior  border  se))arates  the  inferior  and 
posterior  surfaces,  and  forms  the  posterior  lij)  of  the  groove  for  the  suhcliirius ;  it 
begins  at  the  conoid  tuljl'rcle,  and  ends  at  the  rhomboid  depression.  The  inner 
or  sternal  end  of  the  clavicle  is  broad  and  expanded;  it  ])laysupon  a  fibro-cartilage 
interposed  between  it  and  the  clavicular  facet  of  the  manubrium  of  the  sternum, 
and  its  borders  are  rough  for  the  attachment  of  the  sterno-clavicular  and  inter- 
clavicular ligaments.  The  acromial,  or  outer  end,  presents  a  smooth  articular 
facet,  directed  slightly  downwards  for  the  acromion;  its  edges,  especially  the 
superior,  are  rough  for  the  attachment  of  the  acromio-clavicular  ligaments. 


THE  SCAPULA  111 

The  following  muscles  are  attached  to  the  clavicle: — 

Sterno-cleido-mastoid.  Trapezius. 

Pectoralis  major.  Sterno-hyoid. 

Subclavius.  Stemo-thyroid  (occasionally). 

Deltoid. 

Ligaments  : — 

Interclavicular.  Interarticular  (acromio-clavicular) . 

Interarticular  (sternal).  Conoid. 

Capsular  (sterno-clavicular).  Trai)ezoid. 

Rhomboid  or  costo-clavicular.  Costo-coracoid  membrane. 

Capsular  (acromio-clavicular).  Deep  cervical  fascia. 

Blood-supply. — The  nutrient  artery  is  a  Ijninch  of  the  suprascapular;  it  enters 
the  bone  on  the  under  surface  of  the  shaft  near  the  middle  of  the  subcla^dan  groove. 
It  is  directed  towards  the  acromial  end.  The  acromial  end  of  the  clavicle  receives 
numerous  branches  from  the  acromio-thoracic  artery,  and  twigs  from  the  arteries 
in  the  muscles  attached  to  it. 

Ossification. — The  clavicle  is  ossified  from  two  centres.  The  primary  nucleus 
appears  in  the  sixth  week  of  eml^ryonic  life  in  the  tissue  immediately  overlying  the 
cartilaginous  pre-coracoid  bar  (see  p.  115).  The  cla^dcle  begins  as  a  membrane- 
bone,  but  the  ossification  quickly  extends  into  the  underlying  cartilage;  it  is 
therefore  a  dermal  splint  engrafted  on  cartilage.  About  the  seventeenth  year  a 
secondary  nucleus  appears  at  the  sternal  end.  Consolidation  is  complete  by  the 
twentieth  year. 


THE  SCAPULA 


The  scapula  is  a  large  flat  bone,  triangular  in  shape,  situated  on  the  posterior 
aspect  of  the  thorax,  and  resting  on  the  ribs  from  the  second  to  the  seventh.  Of 
its  two  surfaces  the  anterior  is  deeply  concave,  forming  the  subscapular  fossa, 
which  is  marked  by  several  ridges  commencing  at  the  posterior  border  of  the  bone 
and  passing  obliquely  upwards;  these  ridges  divide  this  surface  into  several  shallow 
grooves  from  which  the  suhHcapularls  muscle  takes  origin:  the  highest  groove  is  the 
deepest.  The  outer  third  of  this  surface  is  smooth,  and  overlapped  by  the  sub- 
scapular muscle:  the  superior  and  inferior  angles  are  somewhat  triangular,  and 
connected  by  a  narrow  ridge  of  bone  along  the  posterior  border.  This  ridge  and 
its  terminal  surfaces  serve  for  the  insertion  of  the  seiratus  magnvs. 

The  posterior  surface,  or  dorsum,  is  generally  convex;  it  is  unequally  divided 
by  a  prominent  ridge  of  bone,  the  spine.  The  hollow  above  the  spine  is  the  supra- 
spinous fossa,  and  lodges  the  supra-.spinatus  muscle.  The  part  below  the  spine  is 
the  infraspinous  fossa;  it  is  larger  than  the  supraspinous  fossa,  and  is  limited 
inf(n-iorly  by  a  ridge  which  runs  from  the  glenoid  fossa  backwards  to  join  the 
posterior  border  a  short  distance  above  the  inferior  angle.  To  this  oblique  ridge 
the  stout  aponeurosis  is  attached  which  separates  the  teres  major  and  teres  minor 
muscles  from  the  infraspinatus  muscle.  The  infraspinatus  arises  from  the  inner 
two-thirds  of  the  infraspinous  fossa,  and  overlaps  the  outer  third.  The  supra-  and 
infraspinous  fossse  communicate  with  each  other  around  the  outer  end  of  the 
spine;  this  part  corresponds  to  the  neck  of  the  scapula,  and  the  groove  is  the 
scapular  notch ;  it  transmits  the  suprascapular  nerve  and  artery  from  one  fossa  to 
the  other.  The  surface  of  bone  lielow  the  ol)lique  ridge  presents  two,  and  occa- 
sionally three,  facets  for  muscles:  the  long  narrow  outer  one  is  for  the  origin  of  the 
teres  minor  ;  this  is  cro.ssed  near  its  middle  by  a  groove  for  the  dorsal  artery  of  the 


112 


THE  SKELETON 


scapula.  The  second  facet  is  broader,  and  gives  attachment  to  the  teres  major 
muscle.  In  bones  from  a  muscular  subject  the  third  facet,  quite  at  the  inferior 
angle,  is  for  a  few  fibres  of  the  latissimus  dorsi. 

The  spine  commences  at  the  posterior  border  of  the  scapula  by  a  broad  trian- 
gular surface;  it  then  crosses  the  dorsal  surface  obliquely  to  the  glenoid  fossa, 
becoming  more  prominent  as  it  passes  outwards  till  it  reaches  the  neck  of  the 
scapula;  from  this  point  it  forms  the  overhanging  acromion  process.  The  spine 
presents  a  superior  surface  which  gives  origin  to  the  siipra-spinatus  muscle,  and  an 
inferior  surface  which  affords  origin  to  the  infraspinatus  muscle.  It  has  a  promi- 
nent crest,  Avhich  is  continuous  posteriorly  with  the  vertebral  border,  and,  at  its 


Fig.  120. — The  Left  Scapula.     (Dorsal  surface.) 

Omo-hyoid  and  the  transverse  ligament 


Coraco-acromial      Peetoralis 
ligament  minor 


SUPERIOR  AMGLE 


AXILLARY  BOEDER 


Teres  major 


Rhomboideus 
major 


VERTEBRAL 
BORDER 


INFERIOR  ANGLE 


Latissimus  dorei 


commencement,  is  smooth  for  a  bursa  between  it  and  the  trapezius.  The  crest  is 
subcutaneous,  and  presents  two  lips — a  superior  for  the  insertion  of  the  trapezius, 
and  an  inferior  li]i  for  the  origin  of  the  deltoid.  The  crest  is  continued  into  the 
acromion  process. 

The  acromion  process  forms  the  summit  of  the  shoulder,  and  presents  two 
surfaces,  two  borders,  and  a  tip.  The  up])er  surface  affords  origin  at  its  posterior 
part  to  a  portion  of  the  deltoid.  The  under  surface  is  concave  and  smooth.  Its 
inner  border,  a  continuation  of  the  superior  lip  of  the  crest,  receives  the  trapezius, 
and  presents  near  the  tip  a  small  articular  facet  for  the  outer  end  of  the  clavicle; 
the  edges  of  the  facet  are  rougli  for  tlie  acromio-clavicular  ligaments.     The  outer 


THE  SCAPULA 


n?> 


border  is  continuous  with  the  inferior  lip  of  the  crest,  with  which  it  forms  an 
angle;  it  gives  origin  to  the  deltoid.  The  tip  of  the  acromion  afi"ords  attachment  to 
the  eoraco-acroniial  Hgament. 

Of  the  three  borders  i)resented  by  the  scapula,  the  external,  or  axillary,  is  the 
thickest,  and  extends  from  the  posterior  inferior  angle  to  the  lower  margin  of  the 
glenoid  cavity.  Near  its  junction  with  the  glenoid  cavity  there  is  a  rough  surface, 
from  which  the  long  head  of  the  triceps  arises;  below  this  is  the  groove  for  the 
dorsal  artery  of  the  scapula.  The  subscapidaris  muscle  encroaches  on  this  border 
from  the  anterior  surface,  and  the  teretes  from  the  posterior  aspect.  The  posterior 
or  vertebral,  border,  sometimes  called  the  base,  is  the  longest;  it  extends  from 
tlie  posterior  superior  to  the  posterior  inferior  angle.     It  is  very  narrow    but 


Fig.  121.— The  Left  Scapula.     (Veutral  surface.) 


Serratus  magnus 


SUPRASCAPULAR  NOTCH     Conoid  lig. 
\ 


Trapezoid  ligament 


Coraco-acromial 

ligament 

Biceps  and  coraco- 

brachialis 

CLAVICULAR  FACET 

Biceps 


Triceps  (middle  or  long 
bead) 


Serratus  magnus 


affords  attachment  to  three  muscles:  namely,  the  levator  nngidi  scapulse  above  the 
spine;  the  rhomboideus  minor  on  a  level  with  the  spine;  and  the  rhomhoidcus 
major,  through  the  intervention  of  a  fibrous  arch  from  the  spine  to  the  inferior 
angle.  The  superior  border  is  the  shortest  and  thinnest,  ending  externally  in  the 
coracoid  process.  At  the  base  of  the  coracoid  is  the  suprascapular  notch  to 
the  edges  of  which  the  transverse  ligament  is  attached.  Not  unfrcquently  the  notch 
is  replaced  by  a  suprascapular  foramen.  This  notch  or  foramen  transmits  the 
suprascapular  nerve,  and  occasionally  the  su])rascai)ular  artery,  but  as  a  rule  the 
artery  passes  over  the  ligament.  From  the  adjacent  Itorders  of  the  notch  and  from 
the  ligament,  the  omo-fii/oid  takes  origin.  The  anterior  angle  of  the  sca})ula  is 
formed  by  the  glenoid   cavity.     This  cavity  is  sliall««w  and  pyriform,  with  its 


114  77/ A'  SKELETON 

major  axis  vertical;  the  lower  end  is  the  In-oader;  the  upper  end  or  apex  gives 
oritiin  to  the  long  tendon  of  the  hkeps.  The  margins  are  raised,  and  afford  attach- 
ment to  the  glenoid  ligament.  In  the  recent  state,  the  cavity  is  covered  with 
h valine  cartilage,  and  forms  an  articular  fossa  for  the  head  of  the  humerus.  The 
niargin  is  somewhat  defective  where  it  is  overarched  liy  the  acromion.  The  cir- 
cumference is  rough  for  the  attachment  of  the  capsulai-  ligament.  Beyond  this  is 
a  narrow  constricted  i»ortion,  called  the  neck  of  the  scapula. 

Projecting  upwards  from  the  neck  is  tlie  coracoid  process,  a  ])rominehce  of 
bone  anterior  to,  hut  jiarallel  with,  the  acromion.  It  consists  of  two  parts — vertical 
and  horizontal.  The  vertical  i)ait  is  compressed  from  within  outwards;  it  is  con- 
tinuous ahove  with  the  horizontal  i)art  and  below  with  the  neck  of  the  scapula;  its 
outer  bordi'r  lies  al)ove  the  glenoid  cavity  and  gives  attachment  to  the  coraeo- 
humeral  ligament,  and  its  inner  border  Avhich  forms  the  outer  boundary  of  the  sui)ra- 
sca{)ular  niitch  gives  attachment  to  the  suprascapular  ligament;  its  anterior  and 
posterior  surfaces  are  in  relation  with  the  .siib.scapularis  and  siipraspmatus  respec- 
tively. The  horizontal  })art  runs  forwards  and  outwards;  it  is  compressed  from 
above  downwards;  its  inner  extremity  gives  attachment  to  the  conoid  ligament, 
and  its  outer  extremity,  or  apex,  is  for  the  attachment  of  the  short  head  of  the 
biceps  and  the  coraco-hrachialis ;  the  p^ectoralis  minor  is  attached  to  part  of  the 
anterior  border  and  the  upper  surface,  and  the  postero-internal  part  of  the  upper 
surface  is  occupied  by  the  trapezoid  ligament.  The  posterior  border  gives  attach- 
ment to  the  coraco-acromial  ligament. 

Muscles. — The  following  are  attached  to  the  scapula: — 

Su]>ra-siiinatus.  Latissimus  dorsi. 

Infra-spinatus.  Trapezius. 

Subscapularis.  Rhomboideus  major. 

Teres  major.  Rhomboideus  minor. 

Teres  minor.  Levator  anguli  scapulae. 

Omo-hyoid.  Biceps. 

Pectoralis  minor.  Coraco-brachialis. 

Serratus  magnus.  Triceps  (long  head). 

Deltoid. 
Ligaments  : — 

Conoid.  Capsular  (shoulder-joint). 

Trapezoid.  Coraco-humeral. 

Costo-coracoid  membrane.  Gleno-humeral. 

Costo-coracoid  ligament.  Glenoid. 

Capsular  (acromio-clavicular).  Rhomboid  loop. 

Coraco-acromial.  Spino-glenoid  or  inferior 
Suprascapular  (transverse).  transverse. 

Blood-supply.— The  scapula  is  supphed  by  the  following  arteries: — Twigs 
from  the  sub.scai)ular  artery  and  from  the  subscapular  branch  of  the  suprascapular 
enter  tlie  bone;  on  the  anterior  surface.  The  dorsal  artery  of  the  scapula  distributes 
l)ranc]ies  in  the  infraspinous,  whilst  the  suprascapular  artery  supphes  the  supra- 
spinous fossa,  the  spine,  the  glenoid  fossa,  and  sends  branches  "into  the  infraspinous 
fossa.     The  acromion  is  supi)lied  l)y  branches  of  the  acromio-thoracic  artery. 

Ossification. — The  8cai)ula  is  ossified  from  seven  centres.  Two  may  be  con- 
sidered as  primary,  and  the  remainder  as  secondary  nuclei.  The  centre  for  the 
body  ai)pears  in  a  phito  of  cartilage  near  the  neck  of  the  scapula  about  the  eighth 
week  of  mtra-uterine  life,  and  (pijckly  forms  a  triantrular  plate  of  bone,  from  which 
the  spine  appeai-s  as  a  slight  ridg(>  about  the  middle' of  the  third  month.  At  birth 
the  glenoid  fossa  and  part  of  the  scaindar  neck,  the  acromion,  coracoid,  and  verte- 
bral border  are  cartilaginous.  During  tlie  first  vear  a  nucleus  appears  for  the 
coracoid,  and  at  the  tentii  year  a  second  centre  ap)iears  for  the  base  of  the  coracoid 
and  the  U|»per  ])art  of  the  glenoid  cavitv. 

During  the  (ifleenth  year  the  coracoid  is  ankvlosed  to  the  scai)ula,  and  the 
secondary  centres  appear.     Two  nuclei  are  deposited  in  the  acromial  cartilage,  and 


THE  HUMERUS 


115 


fuse  to  form  the  acromion,  and  join  the  spine  at  the  twentieth  year.  This  union 
of  the  acromion  and  spine  may  be  fitjrous,  hence  the  acromion  is  often  found 
separate  in  macerated  specimens.  The  cartilage  along  the  vertebral  border  ossifies 
from  two  centres:  one  in  the  middle,  and  one  at  the  posterior  inferior  angle.  A 
thin  scale  may  occasionally  be  detected  at  the  tip  of  the  glenoid  fossa. 

Morphology. — It  is  impossible  to  comprehend  the  significance  of  the  scapular 
nviclei  without  considering  briefly  the  morphology  of  the  shoulder  (pectoral) 
girdle. 

In  its  most  generalised  form  the  shoulder  girdle  consists  of  cartilage,  which  is 
disposed  in  three  parts.  Of  these,  a  dorsal  segment  represents  the  scapula  and  a 
ventral  bar,  reaching  to  the  sternum,  represents  the  coracoid.  The  meeting  place 
of  the  coracoid  and  sca})ula  is  the  glenoid  fossa.     Anterior  to  the  coracoid  there  is 

Fig.  122. — Ossificatiox  of  the  Scapula. 

The  Scapula  at  the  third  year, 
showing  the  coracoid  element.    (Anterior  view.) 


The  Scapula  at  birth.     (Anterior  view.) 

a  third  piece,  more  or  less  parallel  with  the  coracoid,  named  the  pre-coracoid.  The 
human  shoulder  girdle  is  modified  from  the  type  form,  mainly  in  the  suppression 
of  the  pre-coracoid  and,  in  part,  of  the  coracoid.  The  suppression  is  brought  about 
by  the  clavicle,  which  commences  to  ossify  in  the  membrane  overlying  the  pre- 
coracoid  ;  it  then  invades  and  replaces  the  cartilage. 

The  scapular  end  of  the  coracoid  ossifies  and  becomes  the  coracoid  process  of 
the  scapula;  the  ventral  end  degenerates  to  form  the  costo-coracoid  ligament, 
which  lies  in  the  free  border  of  the  membrane  of  that  name.  The  dorsal  cartilage 
ossifies  and  becomes  the  scapula;  the  large  tract  of  cartilage  on  the  vertebral  border 
of  the  young  scapula  represents  the  large  suprascapular  cartilage  of  batrachians. 
The  suprascapular  notch  indicates  the  line  of  union  of  scapular  and  coracoid 
elements.  In  the  embryo  the  notch  is  bridged  over  by  cartilage,  which  may  ossify 
or  become  lijjament. 


THE  HUMERUS 


The  humerus  is  the  longest  bone  of  the  upper  limb.  Its  upper  extremity 
presents  a  hemispherical  surface  covered  with  cartilage,  and  known  as  the  head. 
The  head  articulates  with  the  glenoid  cavity  of  the  scapula,  and  is  directed  upwards, 
inwards,  and  backwards.  Below  the  articular  surface,  the  bone  is  rough  and  con- 
stricted, constituting  the  anatomical  neck.  To  the  outer  side  i>f  tlio  head  are  two 
tuberosities,  separated  by  the  bicipital  groove.     The  greater  tuberosity   is  the 


116 


THE  SKELETON 


hi-her  an.l  m.^re  posterior;  it  is  marked  by  three  facets  for  the  insertion  ot  nuiscles: 
an\ii,i>er  one  for  Ihe  .npra-^pinaU,..  a  inicklle  for  the  tnfra-spinatas,  and  an  inferior 
for  the  terc.  mlnnr.  The  lesser  tuberosity  is  the  more  prominent;  it  serves  for 
the  insertion  of  the  srd..capuhns.  The  furrow  between  the  tuberosities  lodges  the 
long  tendon  <.f  the  biceps,  extends  downwards  in  the  axis  ot  tlie  humeral  shaft,  and, 

Fig.  1-23.— The  Lkft  Humekls.     (Anterior  view.) 


Supra-spinatus 


Subscapularis 


Latissimus  dorsi 


Teres  major  ■ 


:v:i 


W 


BICIPITAL  GROOVE 
Peetoralis  major 


Coraco-brachialis 


Bractaialis  anticus 


Supinator  longus 


Extensor  carpi  radialis  longior 


Pronator  radii  teres 

Flexor  carpi  radialis 

Falmaris  loncus 

Flexor  sublimis  digitorum 

Flexor  carpi  uluaris 


Extensor  carpi  radialis  brevior 
Extensor  communis  digitorum 
Extensor  minimi  digit! 
Extensor  carpi  uluaris 
Supinator  brevis 


gradually  becoming  shallower,  ends  near  the  junction  of  the  upper  and  middle 
third  of  the  l)one.  The  margins  of  this,  the  bicipital  groove,  are  called  lips,  and 
afford  attaeliment  to  muscles.  The  pertordlis  iiutjur  ()c(ui)ies  the  whole  length  of 
the  outer  lip.  The  inner  li])  receives,  below,  the  teres  major,  and  above,  the 
Intmimiis  dorsi ;  the  tendon  of  the  latter  muscle  is  also  attached  to  the  floor  of 
the  groove.     Between  the  tuberosities,  the  transverse  humeral  ligament  converts 


THE  HUMERUS 


11" 


the  groove  into  a  canal.  In  addition  to  the  long  tendon  of  the  biceps  and  its  tube 
of  synovial  membrane,  the  groove  transmits  a  branch  of  the  anterior  circumtlex 
artery.  The  constriction  immediately  below  the  tuberosities  is  the  surgical  neck. 
The  shaft  is  prismatic  in  its  upper  third,  but  flattened  below.  Three  borders 
and  three  surfaces  may  be  recognised.     The  anterior  border  commences  at  the 

Fig.  124.— The  Left  Humerus.     (Posterior  view.) 


Capsular  ligament 
Infra-spinatua 


Teres  minor  ■ 


Triceps  'external  head 


MUSCULO-SPIRAL  GROOVE  • 


Triceps  (internal  head)  . 


Capsular  ligament 

OLECRANON  FOSSA  . 

EXTERNAL  CONDYLE 
Anconeus  and  external  lateral  ligament 


;\'|^_  INTERNAL  CONDYLE 

»:1    ~ 


GROOVE  FOR  ULNAR  NERVE 
Flexor  carpi  ulnaris 


greater  tuberosity,  as  the  anterior  or  outer  lip  of  the  bicipital  groove,  and,  passing 
do\mwards,  skirts  the  radial  side  of  the  coronoid  fossa,  to  become  continuous  with 
the  ridge  separating  the  capitellum  and  trochlea.  The  radial  or  outer  border 
extends  from  the  posterior  border  of  the  greater  tuberositv  to  the  radial  condyle. 
This  border  is  not  well  marked  in  the  upper  part  of  the  shaft;  near  the  middle  it  is 


118 


THE  SKELETON 


intci  TupttHl  l)y  the  musculo-spiral  groove  ;  the  lower  half  is  termed  the  external 
condylar  ridge,  and  ali'urds  atlaehiuent  to  the  supinator  longus  and  cxtcn-'^or  carpi 
radialis  loiK/i'ir  museles,  and  the  external  intermuscular  septum.  The  ulnar  or 
internal  border  commences  at  the  lesser  tuberosity,  as  the  inner  lip  of  the  l»ici])ital 
groove,  and  extends  downwards  to  the  ulnar  (internal)  condyle.     Near  its  centre 


Fk;.  125.— The  Left  Hr^ERUs  with  a  Sppracondvloid  Process  and  some  Irkegular 
MiscLE  Attachments.     (Auterior  view.) 


LESSER  TUBEROSITY 
Subscapularis 

Capsular  ligament 


Coraco-brachialis  brevis 
(Kotator  humeri i 


BICIPITAL  GROOVE 


Coraco-brachialis 


Third  head  of  biceps 


Brachialis  amicus 


Coraco-brachialis  . 

SUPRACONOYLOID  PROCESS 


rr. 


5_L'/.^; 


Ml 


•  GREATER  TUBEROSITY 
Transverse  humeral  ligament 


Fourth  head  of  biceps 


ROUGH  SURFACE  FOR  deltoid 


—  THE  EXTERNAL  CONDYLAR  RIDGE 


Pronator  radii  teres 


Capsular  ligament 

CORONUID  FOSSA 


INTERNAL  CONDVLE 
Internal  lateral  ligament  . 


PA  DIAL  DEPRESSION 

iV'r  EXTERNAL  CONDYLE 
'-  CAPITELLUM 


is  a  ridge  for  the  insertion  of  the  coraro-hrarhialis,  and  hdow  tliis  the  foranieii  for 
the  nutrient  artery. 

The  three  ])onlers  considered  al)ove  l)()und  tliree  surfaces.  The  external  sur- 
face lies  between  the  anterior  and  radial  borders.  Near  its  middle  is  a  rouo-h 
impression  for  the  insertion  of  ih^^  deltoid ;  somewhat  lower  is  the  termination  of 


THE  HUMERUS 


119 


the  musculo-spiral  groove.  The  internal  surface  lies  between  the  anterior  and 
ulnar  borders.  The  lower  halves  of  the  internal  and  external  surfaces  afford  origin 
to  the  brachiab's  anticus  muscle.  The  internal  surface  usually  presents,  about 
5  cm.  (2")  above  the  ulnar  condyle,  an  elongated  rough  surface.  This  is  the 
supracondyloid  ridge  ;  it  is  occasionally  replaced  by  a  prominent  spine  of  bone, 
the   supracondyloid  process   (fig.   125),  from   which   a  band  of  fibrous  tissue 

Fig.  126.— Ossification  of  the  Humerus, 


UNITES  WITH  THE  SHAFT  AT  THE  TWENTIETH  YEAR. 
THE  UPPER  EPIPHYSIS  IS  FORMED  BY  THE  UNION  OF 
THE  NUCLEUS  FOR  THE  HEAD,  GREATER  TUBEROSITY, 
AND  THAT  FOR  THE  LESSER  TUBEROSITY.  THESE 
FORM  A  COMMON  EPIPHYSIS  BEFORE  UNITING  WITH 
THE  SHAFT 


SHAFT  BEGINS  TO  OSSIFY  IN  THE  EIGHTH  WEEK  OF 
INTRA-UTERINE  LIFE 


ri 


r//..  ♦ 


NUCLEUS    FOR    THE    INTERNAL    CONDYLE    APPEARS    AT. 

FIFTH;  FUSES  AT  THE  EIGHTEENTH  YEAR 
NUCLEUS  FOR  TROCHLEA  APPEARS  AT  THE  TENTH  YEAR- 


i:^" 


UGLEUS   FOR   EXTERNAL   CONDYLE   APPEARS   AT   FOUR- 
TEENTH  YEAR 

iry NUCLEUS  FOR  CAPITELLUM  APPEARS  IN  THE  THIRD  YEAR 


THE  CENTRES  FOR  THE  hADiAL  Cuf.DVLE. 

TROCHLEA,  AND  CAPITELLUM  UNITE  TOGETHER  AND  FORM  AN  EPIPHYSIS 

WHICH   FUSES  WITH  THE  SHAFT  AT  THE  SEVENTEENTH  YEAR 


extends  to  the  ulnar  condyle,  forming  a  ring,  transmitting  the  median  nerve  and 
the  brachial  artery.  The  nerve  is  not  always  accompanied  by  the  artery;  in  some 
instances  of  high  division  of  the  brachial  the  foramen  transmits  the  interosseous 
artery.  The  process  gives  origin  to  the  pronator  radii  teres,  and  sometimes  aflords 
insertion  to  a  part  of  the  roraro-hrarhialis. 

The   posterior    surface    lies    between   the   ulnar   and  radial  borders.       It   is 
oblic^uely  divided  by  the  musculo-spiral  groove.     The  surface  above  the  groove 


120  THE  SKELETOX 

serves  for  the  origin  of  the  external  head;  the  part  below  for  the  internal  head  of 

the  Irlreps.  i-  i        i 

Tlu'  lower  extremity  uf  the  humerus  is  flattened,  and  presents  trom  the  uhiar 
to  the  radial  side  the  following  parts:— a  prominent  process,  the  ulnar  (internal) 
condyle,  from  which  the  pronator  radii  teres  arises,  and  to  the  lower  part  of  which 
the  internal  lateral  ligament  is  attached.  From  this  ligament  the  flexor  carpi 
radiali.-<,  palmaris  longus,  flexor  siiblimis  digitorinn,  and  flexor  carpi  tdnaris  muscles 
arise.  Posteriorly  the  condyle  forms  with  the  trochlea  a  groove  traversed  by  the 
ulnar  nerve.  External  to  the  condyle  there  is  the  inferior  articular  surface,  sub- 
divided by  a  low  ridge  into  the  trochlea  and  the  capitellum.  The  trochlea  is,  in 
shajte,  like  the  section  of  a  pulley  wheel;  the  ulnar  extends  much  lower  than  the 
radial  edge;  the  articular  surface  is  sliarply  indicated  anteriorly  and  posteriorly. 
The  trochlea  fits  into  the  greater  sigmoid  cavity  of  the  ulna.  Above  the  trochlea  on 
the  anterior  surface  is  the  rounded  coronoid  fossa,  which  receives  the  coronoid 
process  of  the  ulna  when  the  forearm  is  flexed.  On  the  posterior  aspect  there  is  the 
olecranon  fossa,  for  the  reception  of  the  anterior  edge  of  the  olecranon  in  extension 
of  the  forearm.  These  fossae  in  most  humeri  are  separated  by  a  thin  translucent 
disc  of  lione,  sometimes  merely  by  fibrous  tissue,  so  that  in  macerated  bones  a 
perforation,  the  supratrochlear  foramen,  exists.  The  radial  head  or  capitellum 
is  received  by  the  dei)ressi()n  <m  the  summit  of  the  radius;  it  is  limited  to  the 
anterior  and  lower  surface  of  the  humerus.  Above,  it  terminates  in  a  shallow  fossa, 
wliich  receives  the  edge  of  the  radius  in  flexion.  The  ridge  between  the  trochlea 
and  the  capitellum  corresponds  to  the  interval  between  the  ulna  and  radius;  the 
shallow  groove  on  the  outer  side  of  the  ridge  receives  the  inner  margin  of  the  head 
of  the  radius.  External  to  the  capitellum  is  the  external  or  radial  condyle.  It 
is  less  prominent  than  the  ulnar  condyle,  and  gives  attachment  to  the  external 
lateral  ligament  of  the  elbow,  and  to  a  tendon  from  which  five  extensor  muscles 
arise — viz.  extensores  carpi  radialis  brevior,  digitorinn  communis,  minimi  digiti,  carpi 
tdnaris,  and  the  supinator  hrevis.  On  the  posterior  aspect  this  condyle  extends  to 
the  edge  of  the  trochlea,  and  gives  origin  to  the  anconeus. 

Muscles. — The  humerus  affords  attachment  for  the  following  muscles  : — 

Supra-spinatus.  Flexor  carpi  radialis. 

Infra-spinatus.  Palmaris  longus. 

Teres  major.  Flexor  sublimis  digitorum. 

Teres  minor.  Flexor  carpi  ulnaris. 

Subscapularis.  Supinator  longus. 

Deltoid.  Extensor  carpi  radialis  longior. 

Pectoralis  major.  Extensor  carpi  radialis  brevior. 

Coraco-V^rachialis.  Extensor  digitorum  communis. 

Latissimus  dorsi.  Extensor  minimi  digiti. 

Biceps  (occasionally).  Extensor  carpi  ulnaris. 

Brachialis  anticus.  Supinator  brevis. 

Triceps.  Anconeus. 

Pronator  radii  teres. 

Ligaments.— To  the  upper  extremity  of  the  humerus  the  following  ligaments 
are  attached: — 

Capsular.  Gleno-humeral. 

Coraco-liumeral.  Transverse  humeral. 

To  the  lower  extremity: — 

Internal  hiteral  ligament   "I 

External  lateral  ligament  I 

Anterior  ligament  j  '^^  "^^  elbow-joint. 

Posterior  ligament  j 

Arteries.- The  blood-suiiply  of  the  humerus  is  derived  from  the  suprascapular 
and  the  anterior  and  i)()stenor  circumflex  arteries.     Branches  from  these  arteries 


THE  HUMERUS  121 

enter  the  foramina  -wliieh  cluster  around  the  circumference  of  the  head  and  tul)er- 
osities.  .Vt  the  top  of  the  l^icipital  groove  there  is  a  large  nutrient  foramen,  which 
transmits  a  branch  from  the  anterior  circumflex  artery.  The  nutrient  artery  of  the 
shaft  is  derived  from  a  muscular  In-anch  of  the  brachial;  it  enters  the  bone  near  the 
middle  of  the  inner  1)order  inmiediately  l)elo\v  the  insertion  of  the  coraco-brachialis, 
and  is  directed  to  the  distal  end.  The  lower  extremity  is  nourished  by  numerous 
twigs  derived  from  the  anastomotic,  the  superior  and  inferior  profunda,  and  the 
recurrent  branches  of  the  radial,  ulnar,  and  interosseous  arteries. 

Ossification. — The  humerus  ossifies  from  one  primary  and  six  secondar}' 
nuclei.  The  centre  for  the  shaft  appears  about  the  eighth  week  of  intra-uterine 
life,  and  extends  very  rapidly.  At  birth  the  bone  presents  two  cartilaginous 
extremities,  which  ossify  in  the  following  manner: — A  nucleus  for  the  head  appears 
early  in  the  first  year;  it  is  not  unfrequently  present  at  birth  (Spencer).  The 
nucleus  for  the  greater  tuberosity  appears  in  the  third  year.  In  the  fifth  year  a 
centre  may  l^e  deposited  for  the  lesser  tuberosit}^,  but  this  is  not  constant.  The 
three  nuclei  coalesce  to  form  a  disc  of  bone,  which  unites  with  the  shaft  about  the 
twentieth  year. 

The  inferior  extremity  ossifies  from  four  centres :  the  centre  for  the  capitellum 

Fig.  127.— The  Head  of  the  Humeeus  at  the  Sixth  Year.     (Iu  section.) 

THE  CENTRE  FOR  THE   HEAD  APPEARS   DURING  THE   FiRST 

YEAR;  IT  IS  SOMETIMES  PRESENT  AT  BIRTH 

THE  CENTRE  FOR   THE    GREATER   TUBEROSITY    APPEARS    IN 

THE  THIRD  YEAR 


appears  in  the  third  3'ear,  and  those  for  the  inner  (ulnar)  condyle,  the  trochlea, 
and  external  (radial)  condyle  at  the  fifth,  tenth,  and  fourteenth  years  respectively. 
The  nuclei  for  the  capitellum,  trochlea,  and  radial  condyle  coalesce  before  uniting 
with  the  shaft,  which  they  do  in  the  seventeenth  year.  The  ulnar  condyle  joins 
the  shaft  somewhat  later. 

A  study  of  the  upper  end  of  the  humeral  shaft  before  its  union  with  the 
epijihysis  is  of  interest  in  relation  to  what  is  known  as  the  neck  of  the  humerus. 
The  term  neck  is  applied  to  three  parts  of  this  bone.  The  anatomical  neck  is  the 
constriction  to  which  the  capsular  ligament  is  attached.  This  is  accurately  indi- 
cated by  the  constriction  which  lies  internal  to  the  tuberosities;  the  upper  extremity 
of  the  humeral  shaft  before  its  union  Avith  the  epiphysis  terminates  in  a  low  three- 
sided  pyramid,  the  surfaces  of  Avhich  are  separated  from  one  another  by  ridges. 
The  inner  of  these  three  surfaces  underlies  the  head  of  the  bone,  and  the  two  outer 
surfaces  underlie  the  tuberosities.  The  axis  of  the  inner,  isolated  portion  forms 
with  the  shaft  an  angle  of  130°;  it  constitutes  the  morphological  neck  of  the 
humerus,  and  is  of  the  same  nature  as  the  neck  of  the  femur.  The  surgical  neck 
is  an  indefinite  area  below  the  tuberosities  where  the  lione  is  liable  to  fracture. 


1-22 


THE  SKELETON 


THE   ULNA 

Tlie  ulna  is  tlu-  inner  l)one  uf  the  forearm:  it  lies  parallel  with,  but  is  longer  than, 
the  radius.  The  upper  extremity  is  the  thickest  and  strongest  part  of  the  ulna, 
and  is  of  irregular  shape.  The  superior  articular  surface  is  called  the  greater 
sigmoid  cavity,  and  receives  the  trochlea  of  the  humerus;  it  is  transversely  con- 
stricted near  its  middle.  The  prominence  above  the  constriction  is  termed  the 
olecranon,  the  part  below  the  coronoid  process. 

The  olecranon  process  is  the  highest  part  of  the  ulna;  into  its  upper  surface 
the  triceps  is  inserted,  antl  the  anterior  margin  of  this  surface  affords  attachment  to 
the  po.steri()r  ligament  of   the  elbow.     The  anterior  surface  of    the  olecranon  is 


Fig.  128. — Uppkk  End  of  Left  Ui.xa.     (Outer  view.) 

OLECRANON 
GREATER  SIGMOID  FOSSA 


Orbicular  ligament 


Oblique  ligament 


Flexor  profundus  digitorum 


LESSER  SIGMO'D  FOSSA 


Supinator  brevis 


Interosseous  membrane 


articular,  and  forms  the  ui)per  and  back  part  of  the  greater  sigmoid  cavity,  and  its 
margms  give  attachment  to  ligaments.  The  posterior  surface  of  this  process  is 
triangular,  and  separated  from  the  skin  merely  by  a  bursa.  On  the  inner  side 
there  is  a  tubercle  for  the  origin  of  ihe  jiexor  carpi  ulnaris ;  and  below  this  a  fasci- 
culus of  the  internal  lateral  ligament  of  the  ell>ow  is  inserted.  The  outer  side 
gives  attachment  to  ])art  of  the  anconeus. 

The  coronoid  process  forms  the  lower  lip  of  the  greater  sigmoid  eavitv:  its 
upper  sin-laee  is  aiti.ulnr  and  forms  nearly  a  right  angle  with  the  olecranon  portion. 
The  anterior  edge  of  the  coronoid  jirocess  is  sometimes  called  the  apex  The 
inferior  aspect  is  rough  for  the  insertion  of  the  hmchialis  anticus  muscle  and  the 
lower  outer  angle  has  a  tub.-rcle  to  which  the  ol)lique  ligament  is  attached  The 
inner  edge  has  a  smooth  tul)ercle  from  which  the  flexor  mblimis  diqitorvm  arises- 
the  ridge  of  bone  immediately  below  this  tubercle  gives  origin  to  the  lesser  head  of 
ihc  pronator  radn  teres,  and  below  this  again  the  rounded  accessory  l)undle  of  the 
flexor  longiis  polhcin  arises. 


THE  VLXA 


123 


A  triangular  depressed  surface,  posterior  to  the  sublimis  tubercle,  gives  origin  to 
the  upper  fibres  of  the  Hexor  profundus  digitorum.  To  the  outer  side  of  the  rough 
surface  for  the  br((ch!ali.^  antlcm  is  a  triangular  space,  the  base  of  which  is  repre- 
sented by  the  lesser  sigmoid  cavity,  which  receives  the  lateral  articular  surface  of 
the  head  of  the  radius;  the  anterior  and  posterior  margins  of  this  cavity  afford 
attachment  to  the  orbicular  ligament.  The  rest  of  the  triangle  is  depressed,  and 
gives  origin  to  the  supinator  brevis. 

Fig.  1-29.— The  Left  Ulna  and  Radius.     (Antero-interual  view.) 

Capsular  ligament  - 


Internal  lateral  ligament 


Tubercle  for  the  flexor  sublimis 
digitorum 
Internal  lateral  ligament 

Braehialis  antieus 
Pronator  radii  teres  'lesser  head) 

Flexor  longus  poUicis  'aeeeesory  head 


Interosseous  membrane 


Flexor  profundus  digitorum 


Pronator  quadratus 


Anterior  radio-ulnar  ligament 
Internal  lateral  ligament 


GREATER  SIGMOID  FOSSA 

HEAD  OF  RADIUS 
NECK  OF  RADIUS 
Lower  limit  of  orbicular  ligament 

Oblique  ligament 

BICIPITAL  TUBERCLE 

Oblique  ligament 
Supinator  brevis 

Flexor  sublimis  digitorum 

OBLIQUE  LINE 

RADIUS 

Pronator  radii  teres 

Flexor  longus  pollicis 


Interartieular  flbro-cartilage 


Pronator  quadratus 

Supinator  longus 
External  lateral  ligament 

Anterior  radio-carpal  ligament 


The  shaft  throughout  the  greater  part  of  its  extent  is  prismatic,  but  tajiers 
towards  the  lower  extremity,  becoming  thin  and  rounded  in  its  lower  third.  It  has 
three  borders  and  three  surfaces. 

Of  the  three  borders,  the  outer  (or  interosseous)  is  the  most  marked:  it 
commences  at  the  apex  of  the  triangle  from  which  the  supinator  brevis  arises,  be- 
comes very  prominent  in  the  middle  of  the  bone,  but  is  indefinite  near  its  termina- 
tion; the  interosseous  membrane  is  attached  to  it.  The  anterior  border  is  directly 
continuous  with  the  inner  edge  of  the  rough  surface  for  the  braehialis  antieus,  and 


rj4 


THE  SKELETON 


terminates  infrriorlv  in  front  of  the  styloid  process;  throughout  the  greater  part 
of  its  extent  it  is  rounded,  and  affords  origin  to  the  //(wr  y>/v>f(^K/(^^!  r%/ton(?n ;  m 
its  lower  foiu-th  it  is  rough  and  prominent  for  the  jmmutor  quadratus.  The 
posterior  border  extends  from  the  tubercle,  near  the  tip  of  the  olecranon,  to  the 
back  part  of  the  stvloid  process.  The  upper  three-fourths  gives  attachment  to  an 
aponeurosis,  from  Which  the  flexor  and  extensor  cariyi  vlnarh  and  the  flexor  j^rofimdus 
diiiitonim  muscles  arise. 


Fio.  1:50. —Thk  Left  Ulxa  axd  Kadils.     (Postero-exterual  view. 

Triceps 
Capsular  ligament 


^^^^^^ 


Lower  limit  of  orbicular  ligament 


Biceps 


Supinator  brevis 


Extensor  primi  interuodii  pollicis 


RADIUS 


Grooves  for  extensor  oasis,  and  extensor 
primi  interuodii  pollicis 

For  extensor  carpi  radialis  longior 

and  brevior 

Extensor  sccuudi  interuodii  pollicis 


OLECRANON 


SUBCUTANEOUS  SURFACE 


£xtensor  ossis  metacarpi  pollicis 


AN  APONEUROSIS  IS  ATTACHED  TO  THIS  BORDER 
FROM  WHICH  THE  flexor  AND  extensor 
carpi  ulnaris,  AND  flexor  profundus 
digitorum  ARISE 

Extensor  secundi  Internodii  pollicis 


ULNA 
Extensor  indicis 


—  Extensor  minimi  digitl 
Extensor  carpi  ulnaris 

Internal  lateral  ligament 


/j'/      \-\ Extensor  carpi  ulnaris 


Extensor  communis  digitorum       Posterior 
and  extensor  Indiois  radio-carpal 

ligament 


Posterior  radio-ulnar  ligament 


Of  the  three  surfaces,  the  anterior  lies  l)etween  the  anterior  and  interosseous 
borders;  it  is  concave  for  tlie  greater  ])art  of  its  extent.  The  upper  three-fourths 
gives  origin  to  the  flexor  profiindus  diffitorum,  the  lower  fourth  to  the  pronator 
quadrntm;  the  \\\t\wv  limit  of  tlie  surface  for  the  pronator  is  sometimes  indicated  by 
an  oblicpie  ridge.  Tlie  internal  surface  is  bounded  by  the  anterior  and  ])osterior 
borders.  The  upper  three-fourths  is  o(cu])ied  l)y  tlie  flexor  profundtix  diqitorum;  the 
remainder  is  sul)cutaneous.     The  posterior  surface"  lies  ])etween  the  interosseous 


THE  ULNA  125 

and  i)()sterior  Ijurders.  Its  upper  fourth  is  marked  off  by  an  oblique  ridge  run- 
ning from  the  lesser  sigmoid  cavity  to  the  posterior  border.  The  surface  above  the 
line  receives  the  insertion  of  the  anconeus ; .  from  the  line  itself  a  few  fibres  of 
supinator  brevis  arise.  The  surface  below  the  oblique  line  is  subdivided  by  a 
vertical  ridge;  the  portion  lying  between  this  ridge  and  the  posterior  border  is  in 
relation  with  the  extenmr  carpi  uhiari><.  Between  this  line  and  the  interosseous 
border  the  following  muscles  arise  in  order  from  above  downwards:  extensor  oms 
metararpi  pollich,  the  crtrnsor  secundi  internodii  pjollicis,  and  the  extensor  indicis. 

The  lower  extremity  of  the  ulna  is  of  small  size  and  consists  of  two  parts,  a 
head  and  styloid  process,  separated  from  each  other,  on  the  under  surface,  by  a 
groove  into  which  an  interarticular  cartilage  is  inserted.  That  part  of  the  head 
adjacent  to  the  groove  is  semilunar  in  shape  and  plays  upon  the  interarticular 
cartilage  which  excludes  it  from  the  wrist-Joint.  The  margin  of  the  head  is  also 
semilunar,  and  is  received  into  the  sigmoid  cavity  of  the  radius.  The  styloid 
process  projects  from  the  inner  and  back  part  of  the  bone,  and  appears  as  a  con- 
tinuation of  the  posterior  liorder.  To  its  extremity  the  internal  lateral  ligament  is 
attached,  and  its  posterior  surface  is  grooved  for  the  passage  of  the  tendon  of  the 
exteii-<nr  carpi  ulnaris. 

Muscles. — The  following  are  attached  to  the  ulna: — 

Triceps.  Flexor  carpi  ulnaris. 

Anconeus.  Extensor  ossis  metacarpi  poUicis. 

Brachialis  anticus.  Extensor  secundi  internodii  pollicis. 

Pronator  quadratus.  Extensor  indicis. 

Flexor  sublimis  digitorum.  Pronator  radii  teres. 

Flexor  profundus  digitorum.  Supinator  brevis. 

Flexor  longus  pollicis.  Extensor  carpi  ulnaris. 

Ligaments: — 

Internal  lateral  of  elbow.  Interosseous  membrane. 

Anterior  of  elbow.  Anterior  radio-ulnar. 

Posterior  of  elbow.  Posterior  radio-ulnar. 

Orbicular.  Internal  lateral  of  Avrist- joint. 

Oblique.  Interarticular  fil^ro-cartilage. 

Blood-supply. — The  nutrient  vessel  enters  the  shaft  near  the  middle  of  the 
anterior  surface;  it  is  derived  from  the  anterior  interosseous  trunk,  and  is  directed 
towards  the  proximal  end.  The  upper  extremity  receives  branches  from  the 
anterior  and  posterior  ulnar  recurrent  and  from  the  interosseous  recurrent.  The 
lower  end  receives  twigs  from  the  anterior  and  posterior  interosseous  arteries. 

Ossification. — The  ulna  is  ossified  from  three  centres.  The  primary  nucleus 
appears  near  the  middle  of  the  shaft  in  the  eighth  week  of  embryonic  life.  At 
birth  the  greater  portion  of  the  olecranon  process  is  cartilaginous.  During  the 
fourth  year  a  nucleus  appears  for  the  distal  epiphysis.  The  cartilaginous  ole- 
cranon is  mainly  ossified  from  the  shaft,  and  in  the  course  of  the  tenth  year  a 
scale-like  epiphysis  appears  at  its  summit.  This  unites  during  the  sixteenth  year. 
The  distal  epiphysis  consolidates  about  the  eighteenth  year. 


I2r. 


Tin:  SKELETOX 


THE  RADIUS 

The  radius  is  shorter  than  the  ulna  and  lies  parallel  with  it.     The  upper  end 
or  head,  is  surmounted  hx  a  c-ireular  dise,  of  which  the  superior  surface  is  deprc'ssed 
for  the  reception  of  the  capitcllum  of  the  humerus,  especially  m  Hexion  ot  the  tore- 
•irm      The  mart,nn  of  the  head  is  also  articular;  it  is  deeper  on  the  uhiar  aspect, 
where  it  is  receiViHl  i)v  the  lesser  sigmoid  cavity  of  the  uhia;  the  rest  of  the  circum- 


I'u;.  i:51.-AKTurL.\u  Facets  on  the  Lower  End  of  Left  EADirs  and  Ulxa. 

Posterior 

RADIUS  ULNA 


FOR  SCAPHOID 
FOR  SEMILUNAR  — ^^ 


STVLOlO  PROCESS  OF  ULNA 


HEAD  OF  ULNA:  IT  ARTICULATES  WITH 
THE  INTERARTICULAR  FIBRO-CARTiLAGE 
OF  THE  WRIST-JOINT 


ference  is  embraced  by  the  orbicular  ligament.  Below  the  cartilage-covered  surface 
of  the  bone  there  is  a  constricted  portion,  or  neck,  which  is  in  relation  by  its  outer 
side  with  the  supinator  breviii. 

Bi'neath  the  n(>ck,  on  the  antero-internal  aspect  of  the  bone,  there  is  an  oval 
eminence,  the  bicipital  tuberosity,  divided  longitudinally  into  a  rough  posterior 
portion  for  the  bicejis  tendon,  and  a  smooth  anterior  surface  in  relation  with  the 
bursa  which  is  situated  between  the  tendon  and  the  tuberosity. 

The  radius  has  three  borders  and  three  surfaces.     Of  the  three  borders,  the 

Fig.  132. — Posteriok  View  of  the  Lower  End  of  the  Radius  and  Ulna. 


Insertion  of  aupinator  loneus 

Ext.  ossis  metacarpi  pollicia  and 
Ext.  primi  intcrnocfii  pollicis 
ExtenBOr  carpi  radialia 
longior  and  brevior 
TUBERCLE  FOR  POSTERIOR  ANNULAR 

LIGAMENT 

Extensor  secundi  internodii 

polliciu 


STYLOID  PROCESS 


Ext.  commuDis  dlgltorum  and 

extensor  indicis 
Extensor  minimi    digit!   lies   in 

the  groove  between  the  radius 

and  ulna 
Extensor  carpi  ulaaris 

STYLOID  PROCESS 


interosseous  is  the  best  marked.  Commencing  at  tiie  posterior  edge  of  the 
bici])ital  tuberosity,  it  extends  as  a  sharp  ridge  until  it  ai)proaches  the  distal  ex- 
tremity of  thebone;  it  then  divides  to  l)ecome  continuous  with  the  anterior  and 
l)o.<terior  margins  of  tlie  sigmoid  cavity.  It  aflPords  attachment  to  the  interosseous 
membrane.  The  anterior  border  starts  from  the  bicipital  tul)erosity,  crosses 
ol)li(|Uely  to  1]i(>  outer  side  of  tlie  l)one,  and  descends  to  the  anterior  border  of  the 
styloid  process.  The  upi^er  third  of  this  border  is  called  the  oblique  line,  and 
limits  the.  insertion  of  tlie  bitpinator  hrevis  and  the  origui  of  ihefiexor  longus  polUcis, 


THE  RADIUS 


127 


and  affords  attachment  to  the  jiexor  imbliniis  digitorum.  The  posterior  border 
begins  at  the  back  of  the  tuberosit}^  and  extends  to  the  middle  tubercle  on  the 
posterior  aspect  of  the  lower  extremity.  The  anterior  surface  is  bounded  by  the 
anterior  and  interosseous  borders.  The  upper  tAvo-thircls  is  occupied  by  the  flexor 
longus  polUcls,  and  a  little  less  than  the  lower  third  by  the  lyronator  quadratus.  The 
external  surface  lies  between  the  anterior  and  posterior  border.s.  The  upper  third 
affords  insertion  to  the  supinator  brevis ;  at  its  centre  there  is  a  rough,  low,  vertical 
ridge  for  the  pronator  radii  teres ;  below  this,  the  bone  is  smooth  and  overlapped  ])v 
the  tendons  of  the  extensores  carpi  radialis  longior  and  brevior,  and  crossed  by  tlie 
extensor  ossis  metacarpi  poUicis  and  extensor  primi  internodii  pollicis.     The  posterior 


Fig.  V.\:\. — Ossification  of  the  Radius  and  Ulna. 


I 


APPEARS  AT  TUf  TENTH  YEAR;    FUSES  AT  THE 

SIXTEENTH  YEAR 


APPEARS  AT  THE  FIFTH  YEAR;    FUSES  AT  THE 
SEVENTEENTH  YEAR 


APPEARS  AT  THE  FOURTH   YEAR;    FUSES  AT  THE 

EIGHTEENTH  YEAR 
APPEARS  AT  THE  SECOND  YEAR;    FUSES  AT  THE 

TWENTIETH   YEAR 


surface  lies  between  the  interosseous  and  posterior  borders.  The  upper  third  gives 
origin  to  the  extensor  ossis  metacarpi  and  the  extensor  primi  internodii  pollicis,  and 
the  lower  third  is  covered  by  tendons. 

The  lower  extremity  of  the  radius  is  quadrilateral;  its  carpal  surface  is  articu- 
lar and  divided  by  a  ridge  into  an  inner  quadrilateral  portion,  concave  for  articula- 
tion with  the  semilunar  bone;  and  an  outer  triangular  portion,  extending  on  to  the 
styloid  process:  this  is  concave  to  receive  the  superior  surface  of  the  scaphoid  bone. 
The  inner  side  of  the  lower  end  presents  the  sigmoid  cavity  for  the  reception  of 
the  rounded  margin  of  the  head  of  the  ulna.  The  anterior  sm-face  is  a  raised 
ridge  to  which  the  anterior  ligament  of  the  wrist-joint  is  attached.  The  outer 
surface  is  represented  by  the  styloid  process,  to  the  base  of  Avhich  the  siqmuttor 
longus  is  inserted;  and  the  tip  of  the  process  serves  for  the  attachment  of  the 
external  lateral  ligament  of  the  wrist.     It  is  also  marked   by  a  shallow  furrow 


128  THE  SKELETON 

for  the  tendon*^  of  the  exicmor  ossis  metacarpi  and  extensor  primi  internodii  pollicis. 
The  po.^terior  surface  is  convex,  and  marked  by  three  prominent  ridges  separatmg 
three  furrows.  The  posterior  annular  ligament  is  attached  to  these  ridges,  to 
the  '^tvloid  process,  and  to  the  inner  margin,  thus  forming  with  the  bone  a  series 
of  tunnels.  The  outermost  is  broad,  shallow,  and  frequently  subdivided  by  a  low 
ridge  The  outer  subdivision  is  for  the  extensor  carpi  radiahs  longtor,  the  inner 
for  tiie  extensor  carpi  radialis  brevier.  The  middle  groove  is  narrow  and  deep  for 
the  tendon  of  the  extensor  secundi  internodii  pollicis.  The  innermost  is  shallow  and 
transmits  the  exten.^or  indicis  and  the  extensor  communis  digitorum  which  overlies 
the  indicis,  the  posterior  branch  of  the  anterior  interosseous  artery  and  the  pos- 
terior interosseous  nerve,  ^\'hen  the  radius  and  ulna  are  articulated,  an  additional 
groove  is  formed  for  the  extensor  minimi  digiti. 

Muscles. — The  following  muscles  are  attached  to  the  radius: — 

Biceps.  Pronator  quadratus. 

Supinator  brevis.  Extensor  ossis  metacarpi  pollicis. 

Supinator  longus.  Extensor  primi  internodii  pollicis. 

Pronator  radii  teres.  Flexor  longus  polHcis. 

Flexor  sublimis  digitorum. 

Ligaments: — 

Oblique  ligament.  Posterior  annular. 

Interosseous  membrane.  External  lateral  of  wrist. 

Anterior  radio-ulnar.  Interarticular  fibro-cartilage  of  wrist. 

Posterior  radio-ulnar.  Anterior  radio-carpal. 

Posterior  radio-carpal. 

Blood-supply. — The  nutrient  artery  is  derived  from  the  anterior  interosseous 
trunk ;  it  enters  the  shaft  near  the  middle  of  the  anterior  surface,  and  runs  towards 
the  proximal  end  of  the  bone.  The  head  of  the  bone  is  supplied  by  the  radial 
recurrent  and  interosseous  recurrent  arteries.  The  low^er  end  is  supplied  by  the 
anterior  and  posterior  interosseous  arteries  and  numerous  twigs  from  the  carpal 
arches. 

Ossification. — The  radius  is  ossified  by  one  primary  and  two  secondary  centres. 
The  shaft  begins  to  ossify  at  the  eighth  week  of  embryonic  life.  The  nucleus  for 
the  lower  end  appears  in  the  second  year,  whilst  that  for  the  upper  end  is  deposited 
in  the  fifth  year.  The  head  ankyloses  with  the  shaft  at  the  seventeenth  year,  but 
consolidation  is  delayed  at  the  lower  end  until  the  twentieth  year. 


THE  RAND 

The  skeleton  of  the  bund  consists  of  three  parts — the  carpus,  metacarpus,  and 
phalanges. 

TIIE  CARPUS 

The  carpus  contains  eight  bones,  arranged  in  two  rows,  four  bones  in  each  row. 
Enumcnitcd  from  the  radial  to  tlie  ulnar  side,  the  bones  of  the  proximal  row  are, 
the  scaphoid,  semilunar,  cuneiform,  and  pisiform  ;  those  of  the  distal  row,  the 
trapezium,  trapezoid,  magnum,  ;in(l  unciform.  The  anterior  and  posterior 
surfaces  of  all  the  (•ar])al  l)ones,  except  the  i)isiform  and  cuneiform,  are  non-artic- 
ular; the  anterior  surfaces  of  the  bones  of  the  upper  row  are  larger  than  the  pos- 
terior, but  in  the  lower  row  this  arrangement  is  reversed. 


THE  CARPUS 


129 


The  Scaphoid 

This  is  the  largest  bone  of  the  proximal  row.  Its  superior  surface  is  somewhat 
triangular  and  convex  for  articulation  with  the  lower  end  and  styloid  process  of  the 
radius.  Its  inferior  surface  has  two  facets:  a  large  one  for  the  trapezium,  and  a 
small  one  for  the  trapezoid.  The  dorsal  surface  is  occupied  by  a  long,  deep 
groove  for  ligaments.  The  palmar  surface  is  rough  and  concave  above;  below,  it 
has  a  prominent  tuberosity  for  the  attachment  of  the  anterior  annular  ligament  and 


Extensor  carpi 
radialis  lougior 

Extensor  carpi 
radialis  brevier 


Extensor  primi 
internodii  pollieis 


Ext.  secundi 
interaodii  _ 
pollieis 


Fio.  134.— The  Left  Haxd.     (Dorsal  surface.) 

SEMILUNAR 
SCAPHOID^ 


jl^^^^tV"!  S  I  F  o  R  n 


UNCIFORM 


TRAPEZIUM 


Extensor  carpi  ulnaris 


Extensor  communis  digitorura 


Extensor  communis  digitorum 

THIRD,  UNGUAL,  OR  TERMINAL  PHALANX 


the  abductor  p()lllcls  muscle.  The  outer  (radial)  surface  is  rough  for  ligaments. 
The  inner  (ulnar)  surface  is  occu})ied  by  two  articular  facets,  of  which  the  ujiper 
one  is  crescentic  in  sha])e  for  the  semilunar  bone,  Avlnlst  the  lower  is  deeply  concave 
for  the  reception  of  tlu-  head  of  the  magnum. 

Articulations. — \\'ith  radius,  trapezium,  trapezoid,  magnum,  and  semilunar. 


The  Semilunar 

The  semilunar  has  a  convex  superior  surface  for  articulation  with  the  lower 
end  of  the  radius  and  the  tibro-cartilage  of  the  wrist.      Its  inferior  surface  is 
9 


130 


THE  SKELETON 


deei>lv  concave  for  the  head  of  the  nnignuni.  The  uhiar  ridge  of  the  inferior  artic- 
ular surface  is  faceted  for  tlie  unciform:  The  outer  (radial)  surface  has  a  narrow 
semilunar  faert  for  the  scaphoid,  whilst  the  inner  (ulnar)  aspect  ot  the  bone  pre- 
sents a  .luadrilateral  faeet  for  the  l)ase  of  the  cuneitorm.  The  palmar  and  dorsal 
surfaces  are  rough  and  non-articular.  . 

Articulations.— \\'ith  the  radius,  scaphoid,  cuneitorm,  magnum,  and  uneitorm. 


Fig.  135.— The  Left  Haxp.     (Palmar  surface.) 

Fleior  brevis 

pollioiB  Abductor  poUicia 


Flexor  carpi  ulnaria 

Abductor  minimi  -      — 
digiti 


Flexor  brevis  and 
opponens  minimi 
digiti 


Flexor  carpi 
ulnaria 


Adductor  pollioiB 

Opponens  minimi 
digiti 


Abductor  and 
flexor  brevis 
minimi  digiti 


Opponens  pollieia 

Occasional  insertion  into  trapezium 
Extensor  ossis  metaearpi  pollicis 
Flexor  carpi  radialis 

Interosseas  primus  volaria 
Opponeas  pollicis 


Flexor  brevis  and 
Abductor  pollicis 

Flexor  brevis  and 
Adductor  pollicis 


Flexor  lougus 
pollicis 


Flexor  profundus  digitorum 


The  Cuneiform 

The  cuneiform  (or  pyramidal  hone)  rests  hy  its  l)ase  on  the  uhiar  side  of  the 
semihmar;  its  apex  is  (Hrt-ctcd  downwards  and  to  the  uhiar  side,  and  serves  for  the 
attaehment  of  the  internal  lateral  ligament  of  the  wrist.  The  base  i)resents  a  faeet 
for  the  semilunar.  The  inferior  surface  has  a  sinuous  articular  surface  for  the 
uneiform  hone.  Tiie  superior  surface  has  a  convex  smooth  portion,  where  it 
l)lays  ui)on  the  interartieular  cartilage  which  intervenes  between  it  and  the  lower 
end  of  the  ulna;  the  remainder  of  this  surface  is  rough  for  ligaments.     The  palmar 


THE  CARPUS 


181 


surface  has  a  conspicuous  facet  for  the  pisiform  bone  near  the  inner  extremity,  and 
the  dorsal  surface  is  rough  for  ligaments. 

Articulations. — Pisiform,  semilunar,  and  unciform. 


FOR  LIGAMENT 
FOR  TRAPEZOID 
FOR  TRAPEZIUM 


F'iG.  136. — Tin:  Left  Scaphoid. 


FOR  SEMILUNAR  _ 


FOR  MAGNUM  — 


Fig.  1;]7.— The  Left  Semilunar. 

for  cuneiform 


FOR  UNCIFORM 
FOR  MAGNUM 


The  Pisiform 

The  pisiform  resemljles  closely  a  split  pea.     Its  dorsal  aspect,  corresponding 
\.  to  the  cut  surface  of  the  pea,  articulates  with  the  facet  on  the  i^almar  surface  of  the 
cuneiform.     The  rest  of  this  bone  is  rough  for  the  anterior  annular  ligament  and 
the  tendon  of  i\\Q  flexor  carpi  idnaris. 


Fig.  138. — The  Left  Cuneiform. 


FOR  SEMILUNAR 
FOR  PISIFORM 


Fig.  139. — The  Left  Pisiform. 


F3R  CUNEIFORM 


The  Trapezium 

The  trapezium  is  the  first  l)one  of  the  distal  row;  it  is  very  irregular  in  shape. 
[The  inferior  surface  is  saddle-shaped,  and  articulates  with  the  base  of  the  first 


Fig.  140.— The  Left  Trapezium. 


FOR  SCAPHOID 
FOR  TRAPEZOID 


FOR  SECOND  METACARPAL 


GROOVE  FOR  FLEXOR  CARPI  RADIALIS 


FOR  FIRST  METACARPAL 


I  metacarpal  })one.     The  superior  surface  has  a  facet  for  the  scaphoid.     The  inner 
(ulnar)  surface  has  two  facets;  the  lower  and  smaller  is  for  the  base  of  the  second 


132 


THE  SKELETON 


metacarpal,  the  upper  and  larger  for  the  trapezoid.  The  radial  and  dorsal  sur- 
faces are  r()U<rh  for  li<j;anients.'  The  palmar  surface  i)re8ents  a  prominent  ridge, 
Avhieli  has  to  its  ulnar  side  a  deep  groove  which  transmits  the  tendon  of  the  fexor 
carpi  radial  is.  To  the  ridge  of  the  trapezium  the  anterior  annular  ligament  is 
attached.  The  palmar  surface  affords  attachment  to  the  abductor,  flexor  ossis,  flexor 
brer  is,  and  sometimes  a  ])ortion  of  the  extensor  os-ns  metacarpi  pollicis. 

Articulations. — With  the  scaphoid,  trapezoid,  and  the  first  and  second  meta- 
carjial  l)ones. 

The  TRArEzoiD 

The  trapezoid  is  also  very  irregular  in  shape,  and  much  smaller  than  the 
trapezium.  It  has  a  broad  dorsal  surface;  the  narrow  palmar  surface  gives 
origin  to  a  few  fibres  of  the  inner  head  of  the/<'.ror  brer  is  pollicis.      The  portion  of 


Fig.  141.— The  Left  Trapezoid. 

palmar  surface . 

for  trapezium 
for  second  metacarpal 


l)(jne  between  these  surfaces  is  constricted  and  mapped  out  into  articular  facets;  of 
these,  the  inferior  is  most  conspicuous;  it  is  sacldle-shaped  for  the  base  of  the 
second  metacarpal.  The  radial  surface  has  a  facet  for  the  trapezium;  the  ulnar 
surface  is  articular  for  the  magnum;  and  the  superior  surface  has  a  facet  for  the 
seajjlioid. 

Articulations. — With  the  trapezium,  magnum,  scaphoid,  second  metacarpal. 

The  Magnum 

The  magnum  is  the  largest  carpal  bone,  and  occupies  the  centre  of  the  wrist. 
The  superior  surface  is  globular,  and  sometimes  called  the  head.  It  is  received 
into  the  cup  formed  by  the  semilunar  and  scaphoid.  The  articular  surface  of  the 
head  extends  some  distance  on  to  the  dorsal  aspect  of  the  bone.  The  inferior 
surface  has  three  facets.  The  middle  is  the  largest  for  the  base  of  the  third  meta- 
ear])al.  The  small  ulnar  facet  is  for  the  fourth,  and  the  radial  facet  is  for  the 
second  metacarpal.     The  outer  (radial)  surface  articulates  with  the  trapezoid,  and 


Fig.  142.— The  Left  Magnuji. 


FOR  SEMILUNAR 
FOR  SCAPHOID 


THE   RADIAL  OR  OUTER 
SIDE 


FOR  SECOND  METACARPAL 
FOR  THIRD  METACARPAL 


FOR  SEMILUNAR 
FOR  UNCIFORM 


THE   ULNAR   OR    INNER 
SIDE 


FOR  FOURTH  METACARPAL 


j.resents  al)ove  this  small  facet  a  deep  groove  for  an  interosseous  ligament.  The 
inner  (ulnar)  surface  of  the  heme  has  a  long  articular  surface  for  the  unciform 
(sometimes  the  lower  part  of  tliis  surface  forms  a  detached  facet),  but  is  rough 
near  its  anterior  ])art  for  hgaments.  The  palmar  surface  is  convex  and  rougli, 
and  affords  origin  to  the  inner  head  of  the  flexor  brevis  pollicis.  The  rough  dorsal 
surface  is  broad,  and  has  a  dee])  concavity,  which  serves  to  make  the  head  of  the 
bone  more  i)romiuent,  and  gives  rise  to  the  appearance  of  a  neck. 

Articulations.— Trapezoid,  unciform,  semilunar,  scaphoid,  and  second,  third, 
and  fourth  n)etacarpals. 


THE  METACARPUS  133 

The  Unciform 

The  unciform  is  the  most  readily  recognised  of  all  the  carpals,  as  its  palmar 
surface  presents  a  prominent  hook-like  process;  this,  the  unciform  process,  has 
its  concavity  directed  towards  the  radial  side,  and  forms  part  of  the  inner  l)oundary 
of  the  passage  for  the  flexor  tendons;  to  the  apex  of  the  process  the  anterior  annular 
ligament  gains  an  attachment.  It  also  affords  origin  to  i\\e  flexor  brevis  minimi  and 
opponens  minimi  digiti  muscles.     The  dorsal  surface  is  rough  for  ligaments.     The 

Fig.  143. — The  Left  Unciform. 

unciform  process- 


FIFTH  METACARPAL 
FOURTH  METACARPAL 


inferior  surface  has  two  facets  for  the  bases  of  fourth  and  fifth  metacarpals.  The 
superior  surface  forms  the  apex  of  a  wedge,  and  is  smooth  and  rounded  for  articu- 
lating with  a  narrow  facet  on  the  ulnar  side  of  the  lower  surface  of  the  semilunar. 
The  ulnar  surface  is  mainly  articular  for  the  cuneiform,  whilst  the  radial  surface 
is  faceted  for  the  magnum. 

Articulations. — With  the  cuneiform,  semilunar,  magnum,  and  the  fourth  and 
fifth  metacarpals. 

The  central  is  an  occasional  element  of  the  carpus.  It  is  situated  on  the 
dorsal  aspect  of  the  carpus,  between  the  scaphoid,  magnum,  and  trapezoid.  This 
bone  is  a  normal  element  of  the  carpus  in  many  mammals,  even  in  the  orang  and 
gibbon.  It  is  represented  in  the  carpus  of  the  human  embryo,  but  in  most  indi- 
viduals it  undergoes  suppression  or  coalesces  with  the  scaphoid. 

Blood-supply. — The  arterial  twigs  to  the  carpal  bones  are  derived  from  the 
anterior  and  ])Osterior  carpal  branches  of  the  radial  and  ulnar  arteries.  A  large 
l)ranch  from  the  anterior  interosseous  is  also  distributed  to  the  carpus,  and  twigs  are 
furnished  to  it  from  the  posterior  interosseous  artery. 

Ossification. — At  birth  the  carpal  elements  are  cartilaginous,  and  the  nucleus 
for  each  bone  appears  in  the  following  order: — 


Magnum,  first  year. 
Unciform,  second  year. 
Cuneiform,  third  year. 
Semilunar,  fourth  year. 


Trapezium,  fifth  year. 
Scaphoid,  sixth  year. 
Trapezoid,  eighth  year. 
Pisiform,  twelfth  year. 


THE  METACARPUS 

The  metacarpus  consists  of  five  bones.  Each  metacarpal  Ijone  has  a  shaft,  a 
rounded  distal  end  termed  the  head,  and  a  square-shaped  proximal  extremity 
named  the  base.  The  shaft  is  prismatic;  two  surfaces  of  the  prism  are  lateral,  and 
the  third  dorsal.  The  lateral  surfaces  afford  attachment  to  the  interosseous  muscles: 
on  the  palmar  aspect  of  the  shaft  these  surfaces  approach  each  other,  and  for  some 
distance  are  only  separated  by  a  prominent  ridge.  The  dorsal  surface  is  smooth 
and  covered  in  the  recent  state  by  the  tendons  of  the  extensor  muscles  of  the 
fingers.  Near  the  base,  this  surface  is  divided  by  a  median  ridge;  as  this  ridge 
passes  to  the  distal  end  of  the  shaft,  it  divides  and  forms  two  ridges  which  termi- 
nate in  a  prominent  tubercle  on  each  side  of  the  head  of  the  bone.  The  smooth 
surface  on  each  side  of  the  median  ridge  on  the  dorsal  aspect,  near  the  base,  is  for 
a  dorsal  interosseous  muscle.  The  base  is  cpiadrilateral ;  its  palmar  and  dorsal  sur- 
faces are  rough  for  ligaments;  the  ui)})er  end  articulates  with  the  carpus,  and  its 
lateral  aspects  have  facets  for  adjacent  metacarpals.     The  head  has  a  semilunar 


1P.4 


THE  SKELETON 


articular  surfaeo  for  the  base  of  the  first  phalanx,  and  is  more  extensive  on  the 
])almar  than  the  dorsal  aspect.  On  its  palmar  surface  the  head  is  grooved  for  flexor 
tendons,  each  comer  of  the  groove  being  surmounted  by  a  tubercle.  The  sides  of 
th."  head  are  com])ressed,  and  each  side  is  occupied  by  a  well-marked  fossa. 

The  several  metacarpals  present  distinctive  characters.     The  First  is  the  most 


Fig.  144.— The  Fikst  (Left)  Metacakpal, 


RADIAL  SIDE 


ULNAR    SIDE 


])eculiar;  it  is  the  shortest,  and  its  shaft  resembles  that  of  a  phalanx.  It  has  a 
concave  palmar  surface,  and  the  dorsal  surface  lacks  the  bifurcated  ridge.  The 
base  has  a  saddle-shaped  articular  surface  for  the  trapezium,  and  at  its  outer 
(radial)  comer  presents  a  tubercle  for  the  insertion  of  the  extensor  ossis  metacarpi 
pollic'is.  The  head  of  the  bone  presents  on  its  palmar  aspect  two  shallow  grooves 
for  the  sesamoids  in  the  ^exor  brevis  pollicis. 


Fig.  145. — The  Second  (Left)  Metacakpal. 


RADIAL   SIDE 


(OR  TRAPEZIUM 


ULNAR   SIDE 


Muscles  : — 


FOR  THIRD  METACARPAL 
FOR  MAGNUM 


Extensor  ossis  metacarpi  pollicis. 
Opj)oncns  pollicis. 


Fir;-t  dorsal  interosseous. 
Interosseus  primus  volaris. 


Blood-supply.— The  nutrient  vessel  is  derived  from  the  ])rinceps  pollicis  arterv 
it  entir>  uu  the  ulnar  side,  and  is  directed  towards  the  head  of  the  bone. 


THE  META  CA RP US 


185 


The  8Eeoxi)  Metacarpal  is  the  longest,  and  is  easily  recognised  by  its  large 
deeply  cleft  base. 

The  dorsal  surface  affords  attachment  to  the  tendon  of  the  extensor  carpi  radialis 
loiu/ior  and  a  part  of  the  extensor  carpi  radialis  hrevior ;  to  the  palmar  surface  the 
tendon  of  the  flexor  carpi  radialis  is  inserted.  The  remaining  surfaces  present  four 
articular  facets.  The  end  of  the  bone  is  occupied  by  a  deep  groove  for  the  trape- 
zoid; the  ulnar  ridge  of  this  concavity  is  smooth  for  the  magnum,  and  is  directly 
(•(»ntinuous  with  a  long  narrow  facet  for  the  third  metacarpal.  The  radial  surface 
of  the  base  has  a  small,  somewhat  quadrangular  facet  for  the  trapezium. 

Muscles  : — 


Flexor  ear{)i  radialis. 
Extensor  earpi  radialis  longior. 
Extensor  carpi  radialis  brcvior. 


First  and  second  dorsal  interosseous. 
First  palmar  interosseous. 
Flexor  brevis  pollicis. 


Fig.  14G.— The  Third  (Left)  Metacakpal. 


RADIAL   SIDE 


FOR  SECOND  METACARPAL 


ULNAR   SIDE 


FOR  FOURTH  METACARPAL 


STYLOID  PROCESS 


Blood-supply. — The  nutrient  artery  is  derived  from  the  first  palmar  inter- 
osseous. It  enters  on  the  ulnar  side,  and  is  directed  towards  the  proximal  end  or 
base  of  the  l)one. 

The  Third  Metacarpal  is  easily  recognised  by  the  prominent  styloid  process 
Avhich  projects  from  the  radial  corner  of  the  dorsal  surface  of  the  base.  A  little 
below  this  process  the  extensor  carpi  radialis  brevior  finds  insertion.  The  carpal 
.«urface  of  the  base  is  nearly  plane  for  the  magnum.  The  radial  surface  has  a  long 
narrow  facet  for  the  second  metacarpal.  On  the  ulnar  side,  two  rounded  facets  are 
usually  seen  for  the  fourth  metacarpal.      Not  unfrequently  one  of  them  is  absent. 

Muscles  : — • 


Extensor  carpi  radialis  brevior. 


Adductor  ])ollicis. 


Second  and  third  dorsal  interosseous. 
Flexor  carpi  radialis. 


Blood-supply. — The  nutrient  artery  is  derived  from  the  interosseous:  it  enters, 
as  a  rule,  on  the  radial  side,  and  is  directed  towards  the  base. 

The  Fourth  Metacarpal  has  a  very  small  base.  By  its  carpal  surface  it  articu- 
lates with  the  unciform.  The  radial  surface  has  two  rounded  facets  for  the  third 
metacarpal;  there  is  a  small  facet  for  the  magnum  at  the  posterior  radial  coiTier. 
The  ulnar  side  has  a  narrow  articular  surface  for  the  fifth  metacarpal. 


136 


THE  SKELKWN 


Muscles  : — 

The  third  dorsal  interosseous.  The  fourth  dorsal  interosseous. 

The  second  palmar  interossemis. 

Blood-supply.— The  nutrient  artery  is  furnished  hy  the  second  interosseous;  it 
enters  on  the  radial  side  of  the  shaft,  and  is  directed  towards  the  proximal  end. 


Fkj.  147.— The  F^oirth  (Left)  Metacarpal. 


RADIAL  SIDE 


FOR  THIRD  METACARPAL 

FOR  MAGNUM 


ULNAR   SIDE 


FOR  FIFTH  METACARPAL 


The  Fifth  ^Metacarpal  is  readily  distinguished.  The  carpal  facet  is  convex 
for  the  unciform.  The  ulnar  aspect  of  the  base  forms  a  rounded  tubercle  for  the 
extensor  carpi  ulnaris,  whilst  the  radial  side  has  a  semilunar  facet  for  the  fourth 
metacarpal  bone.  The  radial  border  of  the  dorsal  surface  of  the  shaft  often  has  a 
prominent  li])  for  the  fourth  dorsal  interosseous  muscle. 


Fig.  148. — The  Fifth  (Left)  Metacarpal 


RADIAL  SIDE 


FOURTH  METACARPAL 


ULNAR    SIDE 


Muscles  : — 

Flexor  carpi  ulnaris.  Fourth  dorsal  interosseous. 

Extensor  carpi  ulnaris.  Third  palmar  interosseous. 

Opi)onens  minimi  digiti. 

Blood-supply.— The  nutrient  artery  is  derived  from  the  third  interosseous.    It 
enters  the  shaft  on  the  radial  side,  and  is  directed  towards  the  proximal  end. 


THE  PHALANGES 


137 


Ossification. — Each  metacarpal  is  ossified  from  two  centres.  Tiie  nucleus  for 
the  shaft  appears  al)out  the  eighth  week  of  embryonic  life.  At  l)irth  the  shafts  are 
well  ossified,  but  each  end  is  capped  by  a  piece  of  cartilage.  In  the  case  of  the 
first  metacarpal,  a  centre  for  the  epiphysis  appears  at  the  proximal  end  in  the 
course  of  the  third  year.  The  bases  of  the  remaining  metacarpals  are  ossified  from 
the  shaft,  but  an  epiphysis  forms  for  the  head  of  each  bone  in  the  third  year.  The 
bones  are  usually  consolidated  by  the  twentieth  year. 

In  many  cases  the  first  metacarpal  has  two  epiphyses,  one  at  the  base  and  an 
additional  one  at  the  head;  the  latter  is  never  so  large  as  in  the  other  metacarpal 
bones. 

The  third  metacarpal  occasionally  has  an  additional  nucleus  for  the  prominent' 
styloid  i^rocess  which  constitutes  such  a  distinguishing  feature  of  this  bone. 

The  styloid  process  sometimes  remains  distinct,  and  is  then  known  as  the 
styloid  bone.     Occasionally  it  fuses  with  the  trapezoid  or  magnum. 


THE  PHALANGES 

The  phalanges  are  the  bones  of  the  fingers.     They  number  in  all  fourteen:  the 
thumb  has  two,  the  other  fingers  three  each. 

Each  phalanx  has  a  shaft,  which  is  broad  and  slightly  concave  on  the  palmar. 


Fig.  149. — The  Phalanges  of  the  Third  Digit  of  the  Hand.     (Dorsal  view.) 


THIRD   TERMINAL  OR    UNGUAL 
PHALANX 


SECOND    PHALANX 


FIRST   PHALANX 


rounded  and  smooth  on  the  dorsal  aspect.  The  sides  of  the  palmar  surface  are 
raised  where  they  give  attachment  to  the  sheaths  of  the  flexor  tendons.  The  base 
of  each  phalanx  of  the  first  row  presents  a  glenoid  fossa  which  })lays  upon  the 
convex  head  of  the  metacarpal  Ijoiie.  The  distal  end  is  surmounted  by  miniature 
condyles. 


138 


THE  SKELETON 


Their 


Till-  phalan.irts  of  tlic  second  row  are  shorter  than  those  of  the  first  row. 
bases  present  two  shallow  pits,  separated  l)y  a  ridge.  ^    ,    ,     .    . 

The  terminal,  third,  or  ungual  phalanges  have  an  expanded  shatt  ior  the  sup- 
]iort  of  the  nail.      The  hases  are  iileiitieal  in  shape  with  those  of  the  second  row. 

Ossification. Each  i)halanx  ossifies  from  two  centres:  one  for  the  shaft,  which 

is  dcix.sitcd  l.ctwccn  the  eighth  and  tenth  weeks;  and  a  nucleus  for  the  epiphysis  at 


Vm.    l.")(l.— 0S.><IFIC  ATIOX    OF   THE   .MElAeARPALS    AND    PHAJ.AXUES. 


APPEARS  IN  THE  THIRD  YEAR.    CONSOLI- 
DATES IN  THE  TWENTIETH  YEAR 


EPIPHYSIS  FOR  BASE 


METACARPAL  OF  THUMB 


EPIPHYSIS  FOR  HEAD 


APPEAR  IN   THE  THIRD,   AND   CONSOLI- 
DATE IN   THE  TWENTIETH   YEAR 


I  APPEAR  BETWEEN  THE  THIRD  AND  FIFTH 
[      YEAR.     CONSOLIDATE   IN   THE    EIGH- 
TEENTH YEAR 


the  })roxinial  end,  which  appears  between  the  third  and  fifth  years.     Consolidation 
begins  at  the  seventeenth,  and  is  complete  by  the  eighteenth  year. 

The  ossification  of  the  terminal  phalanx  is  peculiar.  Like  the  other  phalanges 
it  has  a  nucleus  for  the  shaft  and  a  secondary  nucleus  for  the  epiphysis;  but  the 
centre  for  the  shaft  appears  at  the  tip  of  the  phalanx;  whereas  in  the  other  pha- 
langes the  earthy  matter  is  deposited  in  the  middle  of  the  shaft. 


TIIU  If  IP-BONE 

Till-  liip-l)one  (innominate  bone)  is  of  irregular  shape,  resembhng  somewhat 
the  blade  of  a  screw  ]>ropeller.  It  consists  of  three  parts,  which,  though  separate 
in  early  life,  are,  in  the  adult,  firmly  ankylosed.  The  three  parts  meet  together  at 
the  cotyloid  cavity  m-  acetabulum.  Tliey  are  named  ilium,  ischium,  and 
pubes. 

The  ilium  is  Dh'  upper  exi>anded  ])ortion;  it  articulates  with  the  sacrum,  and 
forms  the  ui)per  two-lifths  of  the  acetabulum.  The  ischium  is  the  lowest  part  of 
the  bone;  it  forms  the  ])()sterior  and  inferior  two-fifths  of  the  acetabulum,  and 
assists  the  pubes  to  form  the  obturator  foramen.  The  pubes  forms  the  anterior 
fifth  of  the  acetabulum,  eomjdetes  the  obturator  foramen,  and  stretches  towards 
the  median  line  to  meet  with  tlic  opposite  jtubes  to  form  a  symphysis.  Each  i)art 
requires  sej)arate  consideration. 


THE  HIP-BONB:  139 

The  ilium  has  two  surfaces:  the  external  surface,  or  dorsum,  is  convex  in  its 
general  contour.  It  is  Hmited  superiorly  by  the  semicircular  crest,  and  is  crossed 
by  the  three  gluteal  ridges.  The  superior  gluteal  ridge  commences  at  the  crest 
about  5  cm.  (2")  from  its  posterior  termination,  and  passes  downwards  to  the 
middle  of  the  greater  sciatic  ( ilio-sciatic)  notch.  The  space  included  between  this 
ridge  and  the  crest  gives  origin  to  the  gluteus  iiKtximus,  and  at  its  lower  part  to  a  few 
fibres  of  the  pyrifonnis.  The  middle  gluteal  ridge  extends  from  the  crest  2  5  cm. 
(1")  behind  its  anterior  extremity,  and  passes  across  the  dorsum  to  terminate  near 
the  posterior  end  of  the  superior  gluteal  ridge,  at  the  greater  sciatic  notch.  The 
surface  of  bone  between  this  ridge  and  the  crest  is  for  the  origin  of  the  gluteus 
medius.  The  inferior  gluteal  ridge  begins  in  the  notch  separating  the  anterior 
iliac  spines,  and  terminates  posteriorly  in  the  middle  of  the  greater  sciatic  notch. 
The  space  between  the  middle  and  inferior  ridges  gives  origin  to  the  ^/»^msmnm».s, 
except  a  small  area  adjacent  to  the  anterior  superior  iliac  spine  for  the  tensor  vagince 
femorls.  The  bone  between  the  inferior  gluteal  ridge  and  the  margin  of  the  acetab- 
ulum affords  attachment  to  the  capsule  of  the  hip-joint.  Towards  its  anterior  part 
there  is  a  rough  surface  for  the  reflected  tendon  of  the  rectus. 

The  internal  surface  of  the  ilium  consists  of  an  anterior  concave  portion,  termed 
the  iliac  fossa ;  it  lodges  the  iliacus  muscle.  The  fossa  is  limited  below  by  the 
ilio-pectlneal  line;  this  line  receives,  at  its  anterior  part,  the  insertion  of  the  psoas 
parvus.  A  small  portion  of  the  ilium  extends  below  the  ilio-pectineal  line  to  meet 
the  ischium.  The  surface  posterior  to  the  fossa  is  divided  into  an  auricular  sur- 
face for  articulation  with  the  lateral  aspect  of  the  upper  portion  of  the  sacrum,  and 
a  superior  rough  surface — the  tuberosity — for  the  posterior  sacro-iliac  and  ilio- 
lumbar ligaments.  The  crest  extends  from  the  anterior  superior  iliac  to  the  pos- 
terior superior  iliac  spine.  It  is  thickest  at  its  extremities.  The  prominent  edges, 
or  lips,  are  for  the  attachment  of  muscles  and  fasciae. 

The  outer  lip  affords  attachment  to  the  gluteal  portion  of  the  fascia  lata.  The 
external  oblique  is  inserted  into  the  anterior  half,  and  the  latissimus  dorsi  arises  for  about 
an  inch  more  posteriorly.  The  anterior  two-thirds  of  the  intermediate  space  gives 
origin  to  the  internal  oblique.  The  inner  lip,  by  its  anterior  three-fourths,  gives 
attachment  to  the  transverscdis  ;  behind  this  is  a  small  surface  for  the  quadratus  lum- 
borum,  and  the  remainder  is  occupied  by  the  erector  spina'.  The  extreme  inner 
margin  of  the  lip  in  the  anterior  two-thirds  serv^es  for  the  attachment  of  the  iliac 
fascia. 

The  anterior  border  of  the  ilium  extends  from  the  anterior  superior  spine  to 
the  margin  of  the  acetabulum.  The  anterior  superior  spine  gives  attachment  to 
Poupart's  ligament,  and  the  sartorius  which  also  arises  from  the  upper  half  of  the 
superior  iliac  notch.  This  notch  is  terminated  inferiorly  by  the  anterior  inferior 
spine  ;  it  is  smaller,  less  prominent  than  the  superior,  and  gives  origin  to  the 
straight  head  of  the  rectus  femoris  and  the  main  limb  of  the  ilio-femoral  band  of 
the  capsule  of  the  hip-joint.  Beneath  the  inferior  iliac  spine  is  the  inferior  iliac 
notch ;  it  is  broad,  but  shallow,  and  limited  liy  an  eminence,  the  ilio-pubal  ridge, 
which  indicates  the  line  of  ankylosis  of  the  pubes  and  the  ilium.  A  few  lilires  of 
the  iliacus  arise  from  this  notch. 

The  posterior  border  of  the  ilium  presents  above  the  posterior  superior  spine, 
which  gives  attachment  to  the  greater  sacro-sciatic  ligament  and  the  vw It Ifldus  spins', 
and  a  portion  of  the  oblique  sacro-iliac  ligament.  Below  this  is  a  shallow  notch 
terminating  below  in  the  posterior  inferior  spine,  corresponding  to  the  posterior 
border  of  the  auricular  surface.  This  spine  receives  a  portion  of  the  greater  sacro- 
sciatic  ligament.  Below  the  spine  the  posterior  border  of  the  ilium  forms  the  upper 
segment  of  the  greater  sciatic  notch. 

The  ischium  consists  of  a  thick  solid  body,  a  prominent  tuberosity,  and  a 
ramus. 

The  body  is  triangular;  its  outer  surface  forms  the  posterior  and  inferior  section 
of  the  acetabulum.  The  inner  surface  forms  part  of  the  true  pelvis,  and  meets  the 
ilium  a  little  distance  below  the  ilio-pectineal  line.  It  also  forms  the  floor,  or 
non-articular  portion,  of  the  acetabulum,  and  meets  the  pubes  anteriorly;  the  line 
of  junction  is  frequently  indicated  in  adult  bones  by  a  rough  line  extending  from 
the  ilio-pubal  ridge  to  the  margin  of  the  obturator  foramen.     The  free  border  of 


140 


THE  SKELETON 


this  surface  iov\w^  tlie  posterior  l)oun(larv  of  tlie  obturator  foramen.  The  inner 
surface  of  the  ischium  gives  origin  to  the  obturator  internum.  The  posterior  surface 
of  the  ischium  Hes  lietween  the  posteritjr  rim  of  the  acetahuhmi  and  the  greater 
sciatic  notcli.  Inferiorly  this  surface  is  limited  by  the  obturator  groove,  which 
receives  the  }xisterior  Hesliy  liorder  of  the  obturator  externus  when  the  thigli  is  flexed. 
The  capsule  of  the  hip-joint  is  attached  to  the  outer  part  of  the  posterior  svirface. 
The  ])i/rifonnis,  the  greater  and  lesser  sciatic  nerves,  the  sciatic  artery,   and  the 


Fig.  151. — The  Left  Hip-bone.     (luterual  suilace.) 

Quadratus  lumboruin 


Erector  spmae 


Multifldus 
spinae 


AURICUUR  SURFACE 


POST.  INF.  SPINE  OF 
ILIUM 


ANT.   INF.  SPINE  OF  ILIUM 


Psoas  miuor 


i-io-PuBAL  Rioae 


GROOVE  FOR  PUDIC 
VESSELS  AND 

NERVE 

Ot.  Bacro-BCiatic 
ligament 


3:i00VE  FOR  OBTURATOR 
NERVE  AND  VESSELS 


SYMPHY3IAL  SURFACE 
Levator  ani 


''"'AiJn°i'irm,ru^^^        S.^"*  P^°'«  "°<*        Compressor        Subpubic 
ANU  IbCHIUM  i-reetor  penis  ureihr£e  ligament 


nexje  to  the  c,uaclrat»sfemoris,  cross  it.  The  inner  l)ordcr  assists  tlic  ihum  to  com- 
plet."  till- greater  sciatic  notch,  which  is  terminated  inferiorlv  bv  the  prominent 
ischiatic  spine,  wl.i.h  gives  attacliment  to  the  lesser  sacro-sciatic  ligament,  the 
levator  a>u,imd  rocn/!,ms.  From  the  base  of  the  spine,  posteriorly,  the  gemellas 
mperwr  arises;  and  the  internal  pudic  vessels  and  nerve,  with  the  nerve  to  the 
obturator  mternus,  cross  it.  The  recess  below  the  ischiatic  spine  is  the  lesser 
sciatic  notch ;  in  the  recent  state  it  is  covered  with  cartilage,  and  presents  two, 
three,  or  four  grooves  for  the  tendinous  under  surface  of  the  obturator  internum  muscle. 


THE  HIP-BOXE 


141 


The  tuberosity  is  that  portion  of  the  ischium  which  supports  the  body  in  the 
sitting  posture.  It  is  divided  into  an  anterior  and  a  posterior  part  by  a  transverse 
line.  The  j)osterior  portion  is  subdivided  by  an  oblique  ridge  into  an  upper  and 
outer  part  for  the  semimembranosus,  and  a  lower  and  inner  part  for  the  common 
tendon  of  the  biceps  and  the  semitendinosus.  The  anterior  portion  is  separated 
into  an  inner  and  outer  section  by  an  antero-posterior  line,  the  outer  part  gives 
origin  to  the  posterior  part  of  the  adductor  magnus,  and  the  inner  part  serves  for 


Fig.  15-2. — Tin:  Lkft  Hip-bone.     ( Posterior  view. 

Posterior  limit  of  external  oblique 


Insertion  of 
external  oblique 


Internal   oblique 


XiatisEimus  dorsi 


CREST  OF  ILIUM 


SUPERIOR  GLUTEAL 
RIDGE 


Rectus  femoris 


INFERIOR  ILIAC 
NOTCH 


ARTICULAR  PORTION  OF 
COTYLOID  CAVITY 


PECTINEAL   RICCE 


Peetiaeus 

Rectus 
abdominis 
Pyramidalis 
Adductor 

longus 

Adductor 

brevis 


DESCENDING  RAMUS 
OF  PUBES 

Gracilis 


LESSER  SCIATIC  NOTCH 
Gemellus  inferior 


OBTURATOR  NOTCH 
Semimembranosus 


QuadrEtus  femoris 


Semitendinosus 
and  biceps 


Adductor  magnv 


RAMUS  OF  ISCHIUM        Obturator  c-ternus 


the  iittachincnt  of  part  of  the  falciform  process  of  the  great  sacro-sciatic  ligamer.t. 
The  surface  of  the  tul^erosity  aljove  this  lip  is  in  relation  with  the  internal  pudic 
vessels  and  nerves.  The  outer  lip  is  occupied  by  the  quadratti>>f('iiiorif<  muscle,  and 
the  surface  adjacent  to  this  is  occupied  by  the  adductor  magnus.  The  surfaces  thin 
away  to  a  sharp  margin,  Avhich  forms  part  of  the  boundary  of  the  obturator  foramen. 
The  ramus  of  the  ischium  is  a  continuation  of  the  tuberosity  running  upwards 
to  join  the  descending  ramus  of  the  pubes,  to  complete  the  obturator  foramen.  The 
outer  surface  of  the  ramus  gives  origin  to  the  adductor  magnus  and  the  obturator 


142 


THE  SKKLKTOX 


externum.     To  its  inncT  surface  the  eras  penis  is  attached;  it  also  gives  origin  to  the 
transrcrsd.s  prrinci,  the  enrtor  peni.s,  and  the  obturator  internus. 

Tin-  pubes  consists  of  a  body  an.l  two  rami.    The  hody,  quadrilateral  in  shai)e 
i<  continuous  with  tlie  ramus  of  the  ischium  l)y  means  of  a  flattened  process  termed 
the  descending  ramus.     The  outer  surface  of  the  Ixxly  gives  origm  to  tlie  (Khhx'tnr 


Yui.  15:}.  — An  Immatcre  IxxoMtx at;:  I'.oxe.  siiowinc  a  Corvi.oin  I'.oxk. 


THE  COTYLOID  BONE 


lonyii-i.  The  adductor  brevis,  the  gracilis,  and  the  obturator  e.rtcrnu--<  arise  from  the 
outer  surface  of  the  body  and  descending  ramus.  A  small  portion  of  the  adductor 
magnus  also  arises  from  the  descending  ramus.  The  posterior  surface  of  the  body 
and  that  of  the  descending  ramus  is  continuous  with  the  corresponding  surface  of 
the  ramus  of  the  ischium,  and  affords  attaehment  to  the  levator  ani  and  obturator 


Fig.  lot. — Thk  Pelvis  of  a  Fcetus  at  Bikth,  to  show  the  Three  Portions  of  the 

IXXOMIXATE   P.OXKS. 


THE  NUCLEUS  FOR  THE  ILIUM  APPEARS 
EARLY   IN   THE   SECOND    MONTH 


THE   NUCLEUS    FOR   THE   PUBES   APPEARS   ABOUT 

THE  END  OF  THE  FOURTH   MONTH 
THE    NUCLEUS    FOR   THE   ISCHIUM   APPEARS   IN 
THE  THIRD  MONTH 


internum.  Tht-  posterior  surface  of  the  descending  ramus  gives  origin  to  the  coiii- 
presmr  uretlrnv  and  a  part  of  the  erector  penia^  the  C7iis  peni.-i,  and  the  obturator 
internus.  The  inner  l)order  is  rough  and  covered  with  fibro-cartilage,  which  unites 
it  with  the  opposite  V)one  to  form  the  })ubic  sgmphi/xis.  The  outer  l)order  forms  part 
of  the  obturator  foramen.  The  inner  border  of  the  descending  ramus  forms  with 
the  ramus  of  the  ischium  the  pubic  arch. 


THE  HIP-BONE  143 

The  upper  surface  or  crest  of  the  pubes  is  limited  externally  by  the  pubic  spine, 
which  gives  attachment  to  the  outer  (inferior)  pillar  of  the  external  abdominal  ring 
or  Pouj>art's  hgament.  The  inner  extremity  of  the  crest  is  the  angle  of  the 
pubes.  Between  it  and  the  spine  the  following  structures  are  attached: — the  linea 
alba,  the  rectus  abdominui,  the  j^yamidalis,  and  the  conjoined  tendon  of  the  internal 
oblique  and  tran.-icermlU  muscles.  The  horizontal  ramus  extends  from  the  body 
of  the  pubes  to  the  ilium,  forming  by  its  outer  extremity  the  anterior  one-fifth  of 
the  articular  surface  of  the  acetabulum.  Its  line  of  jvmction  Avith  the  ilium  forms 
the  ilio-pubal  ridge.  Stretching  from  this  ridge  to  the  pubic  spine  there  is  a 
raised  edge  cDUtiniiing  the  ilio-pectineal  line.  The  surface  of  bone  in  front  of  the 
line  is  the  pectineal  surface  ;  it  gives  origin  to  the  pectineus  muscle,  and  is  limited 
below  by  the  obturator  crest,  which  extends  from  the  pubic  spine  to  the  cotyloid 
notch.  The  under  surface  of  the  horizontal  ramus  forms  the  upper  boundary  of 
the  obtvu-ator  foramen,  and  i^resents  a  deep  groove  for  the  passage  of  the  obturator 
vessels  and  nerve. 

The  acetabulum  is  a  circular  depression  in  which  the  head  of  the  femur  is 
lodged.  It  consists  of  an  articular  and  a  non-articular  portion.  The  articular 
portion  is  circumferential  and  h(jrseshoe-shaped;  the  deficienc}'  is  in  the  lower 
segment.  The  pubes  forms  one-fifth  of  the  acetabulum,  and  the  ischium  two-fifths; 
the  rest  is  formed  by  the  ilium.  In  rare  instances  the  pubes  may  be  excluded  by 
a  fourth  element,  the  cotyloid  bone.  The  non-articular  portion  is  formed  mainly 
by  the  ischium,  and  is  continuous  below  with  the  margin  of  the  obturator  foramen. 
The  articular  portion  presents  an  outer  rim  to  which  the  cotyloid  ligament  is 
attached,  and  an  inner  margin  to  which  the  synovial  membrane  is  connected  which 
excludes  the  ligamentum  teres  from  the  synovial  cavity.  The  opposite  angles  of 
the  horseshoe-shaped  margin  which  limit  the  cotyloid  notch  are  united  by  the 
transverse  ligament,  and  through  the  cotyloid  foramen  thus  formed  a  nerve  and 
vessel  enter  the  joint. 

The  obturator  (thyroid)  foramen  is  situated  between  the  ischium  and  pubes. 
Its  margins  are  thin,  and  ser\'e  for  the  attachment  of  the  obturator  foramen.  At 
the  upper  and  posterior  angle  it  is  deeply  grooved  for  the  passage  of  the  obturator 
vessels  and  nerve. 

Muscles  attached  to  the  hip-bone  are: — 

Gluteus  maximus.  Sartorius. 

Gluteus  medius.  Pectineus. 

Gluteus  minimus.  Pyramidalis. 

Tensor  vaginae  femoris.  Pyriformis. 

Rectus  femoris.  Gemellus  superior. 

Oljturator  externus.  Gemellus  inferior. 

Obturator  internus.  Gracilis. 

Latissimus  dorsi.  Adductor  magnus. 

Internal  oblique.  Adductor  longus. 

External  oblique.  Adductor  brevis. 

Transversalis.  Levator  ani. 

Erector  spina*.  Coccygeus. 

Multifidus  spina'.  Transversus  perinei. 

Quadratus  lumborum.  Erector  penis. 

IHacus.  Compressor  urethraj. 

Psoas  parvus.  Biceps  femoris. 

Quadratus  femoris.  Semitendinosus. 

Accelerator  urinte  (occasionally).  Semimembranosus. 

The  ligaments  attached  to  the  hip-bone  are: — 

Greater  sacro-sciatic.  Transverse. 

Lesser  sacro-sciatic.  Round  (ligamentum  teres). 

Ilio-lumbar.  Anterior  puliic. 

Anterior  sacro-ihac.  Posterior  pubic. 

Posterior  sacro-iliac.  Superior  pubic. 

Capsular  and  its  accessories.  Subpubic. 

Cotyloid.  Poupart's.         Triangular. 


144 


THE  SKELETON 


Blood-supply.— Tin-  ilium  receives  on  its  anterior  surface  tAvigs  from  the  iho- 
luinl.ar,  .hnp  riniuulUx  iliac,  and  obturator  arteries.  On  the  dorsum,  arteries 
enter  it  from  the  jrhiteal  and  sciatic  trunks.  ^         ^       .        i    •  n 

The  ischium  is  supplied  l.y  the  obturator,  mternal,  and  external  circumflex. 

Picj    ir,.-,.— Hip-bone,  showing  Secondary  Centres. 

APPEARS  AT  FIFTEEN.     UNITES  AT  TWENTY  " 


APPEARS  AT  FIFTEEN.     UNITES  AT  TWENTY 


THE    LINES    OF    UNION    ARE  USUALLY   OB- 
LITERATED BY  THE  SIXTEENTH  YEAR 


APPEARS  AT  SIXTEEN.     FUSES  AT  TV.: '  '  ■  — i 


APPEARS  AT  FIHEEN.     FUSES  AT  TWENTY 


Fig.  156.— Hip-bone  (Inner  Surface)  at  the  Eighth  Year. 


Till'  pubes  receives  twigs  from  the  obturator,  internal  and  external  circumflex, 
deep  e|)igastrie,  and  the  jailiic  branches  of  the  common  femoral  artery. 

Development. — The  cartilaginous  representative  of  the  hip-bone  consists  at  first 
of  an  ilio-ischiatic  and  a  pubic  segment.  These  quickly  fuse  and  form  a  continuous 
plate.  ( lit (senbeig. ;  Early  in  the  second  month  a  nucleus  appears  above  the  acetab- 
ulum for  the  ilium,  and  one  appears  a  little  later  below  the  cavity  for  the  ischium. 


THE  PELVIS 


145 


In  the  fourth  month  a  nucleus  is  seen  in  the  puliic  portion  of  the  cartilage.  At 
l>irtli  these  three  nuclei  are  of  considerable  size,  but  surrounded  by  relatively  wide 
tracts  of  cartilage.  At  the  twelfth  year  the  triradiate  cartilage  which  separates  the 
three  segments  of  the  innominate  bone  at  the  acetabulum  begins  to  ossify  by  several 
centres,  which  unite  with  the  surrounding  elements  causing  their  consolidation  from 
the  eighteenth  to  the  twentieth  year.  One  of  these  nuclei  is  larger  than  the  others 
and  is  the  acL'tal)ular  nucleus.  The  segment  it  forms  is  regarded  by  some  mori:>holo- 
gists  as  the  representative  of  the  cotyloid  or  acetabuldr  bone  constantly  present  in  a 
few  mammals,  and  is  of  sufficient  size  to  exclude  the  pubes  from  the  cotyloid  cavity. 
During  the  eighth  year  the  rami  of  the  ischium  and  pulses  coalesce.  About  the 
lifteenth  year  two  secondary  nuclei  appear  in  the  iliac  cartilage  to  form  the  crest 
and  the  anterior  inferior  spine.  An  accessory  nucleus  appears  for  the  ischial  tuber- 
osity, and  subsequently  one  for  the  pubic  crest.  These  fuse  with  the  main  bone 
about  the  twentieth  year.  The  fibrous  tissue  connected  with  the  jjubic  spine  repre- 
sents the  epipubic  bone  of  marsupial  mammals. 


THi:  PELVIS 

The  pelvis  is  composed  of  four  bones:  the  two  hip-bones,  the  sacrum,  and  the 
coccyx.  The  hip-bones  form  the  lateral  and  anterior  boundaries,  meeting  each 
other  to  form  the  pubic  symphysis;  posteriorly  they  are  separated  by  the  sacrum. 
The  hollow  of  the  pelvis  is  divided  into  the  false  and  true  jielvic  cavity. 


Fig.  157.— The  Pelvis  (Male) 


The  false  pelvis  is  tliat  part  of  the  cavity  wliich  lies  above  the  ilio-pectineal 
lines;  this  part  is  in  relation  with  the  hypogastric  and  inguinal  regions. 

The  true  pelvis  is  situated  below  the  ilio-pectineal  lines.  The  upper  circum- 
ference, called  also  the  inlet  of  the  pelvis,  is  bounded  anteriorly  by  the  spine  and 
crest  of  the  pubes,  posteriorly  by  the  l^ase  of  the  sacrum,  and  laterally  by  the  ilio- 
])ectineal  lines.  The  inlet  in  normal  pelves  is  cordate,  being  obtusely  pointed  in 
front;  posteriorly  it  is  eneroached  upon  by  the  promontory  of  the  sacrum.  It  has 
three  principal  diameters  ;  of  these,  the  antero-posterior,  called  the  conjugate 
10 


14(3  THE  SKELETON 

diameter,  is  nunisured  from  the  sacro-vertebral  angle  to  the  symphysis.  The 
transverse  cHiimeter  represents  the  greatest  width  of  the  pelvic  cavity.  The  oblique 
is  measured  from  tlie  saero-ihac  synchondrosis  to  the  ilio-pubal  ridge. 

The  cavity  of  the  true  pelvis  is  l)Ounded  in  front  by  the  synqjhysis  pubis,  behind 
l»y  the  sacrum  and  coccyx,  and  laterally  by  a  smooth  wall  of  bone  formed  in  part 
1)V  the  ilium,  in  part  by  the  ischium;  it  corresponds  to  the  acetabulum.  The  cavity 
is  shallow  in  front,  where  it  is  formed  l)y  the  pul)es,  and  is  deepest  posteriorly. 

The  lower  circumference,  or  outlet,  of  the  pelvis  is  very  irregular,  and  encroached 
upon  by  three  bony  processes:  the  posterior  process  is  the  coccyx,  and  the  two 
lateral  processes  the  ischial  tuberosities.  They  separate  three  notches.  The  anterior 
is  the  pubic  arch,  and  is  ))ounded  on  each  side  by  the  conjoined  rami  of  the 
pubes  and  ischium.  The  two  remaining  gaps  correspond  to  the  greater  and  lesser 
sciatic  notches;  they  are  bounded  by  the  ischium  anteriorly,  the  sacrum  and 
coccyx  posteriorly,  and  the  ilium  above.  These  are  converted  into  foramina  by 
the  greater  and  lesser  sacro-sciatic  ligaments. 

The  position  of  the  pelvis. — In  the  erect  position  of  the  skeleton,  the  plane  of 
the  pelvic  inlet  forms  an  angle  with  the  horizontal,  which  varies  in  individuals  from 
50°  to  ()0°.  The  base  of  the  sacrum  in  an  average  pelvis  lies  nearly  10  cm.  (4") 
above  the  u]iper  margin  of  the  symphysis  pubis. 

The  axis  of  the  pelvis. — This  is  an  imaginary  line  drawn  at  right  angles  to 
the  planes  of  the  brim,  cavity,  and  outlet,  through  their  centres. 

The  average  measurements  of  the  diameters  of  the  pelvis  in  the  three  planes  are 
given  below  (after  Lusk): — 

Diameters  At  the  brim  At  the  outlet 

Conjugate 4^  inches  3f  inches 

Transverse      5^      ^'  4^     " 

Oblique 5        "  4J     " 

Sexual  differences : — 


Male 
Bones  heavier  and  rougher. 
Ilia  less  vertical. 
Iliac  fossae  deeper. 
False  pelvis  relatively  wider. 
True  pelvis  deeper. 

"       narrower. 
Inlet  more  heart-sha])ed. 
Symphysis  deeper. 
Tuberosities  of  ischia  inflexed. 
Pubic  arch  narrower  and  more  pointed. 
Margins    of    ischio-pubic    rami    more 

everted. 
Obturator  foramen  oval. 
Sacruui  narrower  and  n)ore  curved. 
Capacity  of  true  pelvis  less. 


Female 
Bones  more  slender. 
Ilia  more  vertical. 
Iliac  fossise  shallower. 
False  pelvis  relatively  narrower. 
True  pelvis  shallower. 

"      wider. 
Inlet  more  oval. 
Symphysis  shallower. 
Tuberosities  of  ischia  everted. 
Pubic  arch  wider  and  more  rounded. 
Margins  of  ischio-i>ubic  rami  less  everted. 

Obturator  foramen  triangular. 
Sacrum  wider  and  less  curved. 
Capacity  of  true  pelvis  greater. 


THE  FEMUR  147 


THE  FEMUR 


This  bone  is  the  largest  and  longest  in  the  skeleton.  The  upper  extremity  is 
surmounted  by  a  hemispherical  cartilage-covered  articular  portion  called  the  head, 
which  is  directed  upwanls  and  inwards,  to  be  received  in  the  acetabulum  of  the  hi[)- 
bone.  A  little  below  and  behind  the  centre  of  the  head  is  a  small  rough  depression 
to  which  the  ligamentum  teres  is  attached.  The  head  is  connected  to  the  shaft  by 
the  neck,  a  stout  rectangular  process  of  bone  wdiich  forms  with  the  femoral  shaft, 
in  the  adult,  an  angle  of  125°.  Its  anterior  surface  is  in  the  same  plane  with  the 
front  aspect  of  the  shaft,  but  it  is  marked  off  from  it  by  a  ridge  to  which  the  capsule 
of  the  hip-joint  is  attached.  This  ridge  commences  at  the  greater  trochanter  in  a 
small  prominence,  the  superior  cervical  tubercle,  and  extends  obliquely  down- 
wards to  the  inferior  cervical  tubercle,  and,  winding  to  the  back  of  the  femur, 
becomes  continuous  with  the  inner  lip  of  the  linea  aspera.  The  whole  of  this 
ridge  is  called  the  spiral  line,  l)ut  the  part  between  the  cervical  tubercles  is  often 
called  the  anterior  intertrochanteric  line.  The  superior  and  inferior  tubercles 
receive  the  limbs  of  the  ilio-femoral  thickening  in  the  capsule  of  the  hip-joint. 
The  posterior  surface  of  the  neck  is  smooth  and  concave,  its  inner  two- thirds  is 
enclosed  in  the  capsule  of  the  hip-joint.  The  superior  surface  is  narrow,  and  pitted 
with  nutrient  foramina;  it  runs  downwards  to  the  greater  trochanter.  The  inferior 
surface,  concave  in  outline,  terminates  at  the  lesser  trochanter. 

The  trochanters  are  prominences  which  afford  attachment  to  muscles  wliich 
rotate  the  thigh;  they  are  two  in  number,  the  greater  and  the  lesser. 

The  greater  trochanter  is  quadrilateral,  and  surmounts  the  junction  of  the 
neck  with  the  shaft.  Of  its  two  surfaces,  the  external  is  the  broader;  it  is  bisected 
diagonally  by  a  ridge  running  from  the  posterior  superior  to  the  anterior  inferior 
angle.  The  gluteus  mecUus  is  inserted  into  this  ridge;  a  bursa  occasionally  is  inter- 
posed between  the  tendon  and  the  bone.  The  inner  surface  presents  a  deep  pit,  the 
trochanteric  fossa,  which  receives  the  tendon  of  the  obturator  externus.  The  upper 
border,  called  the  tip,  gives  attachment  from  before  backwards  to  the  tendons  of 
the  obturator  internus  with  the  gemelli,  and  the  pyriformis.  The  anterior  border 
receives  the  gluteus  minimus.  The  posterior  border  is  thick,  rounded,  and  contin- 
uous with  the  posterior  intertrochanteric  line,  which  runs  downwards  to  termi- 
nate at  the  lesser  trochanter,  a  conical  prominence  on  the  posterior  aspect  of  the 
femur  to  which  the  psoas  is  inserted.  Running  downwards  from  the  lesser  tro- 
chanter to  meet  the  spiral  line  is  a  slender  ridge,  to  which  the  iliacus  is  inserted. 
The  surface  of  bone  slightly  posterior  to  this  ridge  is  occupied  by  the  pectineus. 
This  part  of  the  femur  presents  several  converging  ridges,  which  Avill  be  most  con- 
veniently considered  with  the  linea  aspera. 

Tlie  shaft  of  the  femur  is  cylindrical  in  shape,  and  presents,  in  the  middle 
third  of  its  posterior  aspect,  a  prominent  vertical  ridge  of  bone,  the  linea  aspera, 
for  the  origin  and  insertion  of  muscles.  In  the  middle  of  the  shaft  the  linea  aspera 
presents  an  inner  lip,  an  outer  lip,  and  an  intervening  space.  ,  Towards  the  ujiper 
third  of  tlie  shaft  these  three  parts  diverge:  the  outer  lip  becomes  continuous  with 
the  gluteal  ridge,  and  ends  at  the  base  of  the  greater  trochanter.  When  very 
prominent  the  gluteal  ridge  is  termed  the  third  trochanter.  It  affords  attachment 
to  the  gluteus  rnaximus.  The  inner  lip  curves  inwards  below  the  lesser  trochanter, 
and  becomes  the  spiral  line.  The  middle  portion  of  the  linea  aspera  bifurcates, 
the  inner  portion  as  it  runs  on  to  the  lesser  trochanter  receives  the  iliacus ;  the  outer 
passes  upwards  to  the  centre  of  the  posterior  intertrochanteric  line;  it  receives 
the  quadratus  femori!<,  and  is  called  the  linea  quadrati.  The  upper  limit  of  this 
line  is  often  indicated  by  a  rounded  tubercle  wliich  j^rojects  on  the  posterior  inter- 
trochanteric line.  Towards  the  lower  third  of  the  shaft,  the  inner  and  outer  lips  of 
the  linea  aspera  diverge  to  become  continuous  with  the  condylar  ridges.  Several 
muscles  are  connected  with  the  linea  aspera.  The  vastus  interims  arises  from  the 
whole  length  of  the  inner  lip,  and  the  vastus  externus  from  the  outer  lip.  The 
adductor  magnus  is  inserted  into  the  upper  half  of  the  outer  lip,  and  the  lower  half 


14S 


THE  SKELETON 

Fig.   158.— The  Left  Femie.     (Anterior  view.) 

GREATER  TROCHANTER 


SUPERIOR  CERVICAL  TUBERCLE 


Capsule 

OF  THE  HIP-JOINT  AnACHED  TO  THE  ANTERIOR 
INTERTROCHANTERIC  LINE 


LESSER  TROCHANTER 
Psoas 


ADDUCTOR  TUBERCLt   — j 
Adductor  maenus 


Pyriformis 
Obturator  internua 


' —  Gluteus  minimus 


Vastus  externus 


External  lateral  ligament 
Popliteus 


INTERNAL  CONDYLE  EXTERNAL  CONDYLE 


THE  FEMUR 
Fig.  159.— The  Left  Femuk.     (Posterior  view.) 

Obturator  externua 
/ 


149 


Gluteus  medius 


TUBERCLE  OF  THE 
quadratus  femoris 


Vastus  externus 


GLUTEAL  RIDGE 
Gluteus  maximus 


Adductor  magnus 


OUTER  LIP  OF  THE  LINEA  ASPERA 
Biceps 


Biceps 

EXTERNAL  CONDYLAR  LINE 


Plautaris 
Gastrocnemius 


Anterior  crucial  ligament 
INTERCONOyLOlO  NOTCH 


EXTERNAL  CONDYLE 


Iiigameatum  teres 


Capsule 

POSTERIOR  INTERTROCHANTERIC  LINE 

Psoas 

LESSER  TROCHANTER 

Iliacus 

Pectlneua 


Adductor  brevis 


INTERVENING  SPACE  OF  THE  LINEA  ASPERA 
Adductor  longus 


Vastus  internus 

INNER  LIP  OF  THE  LINEA  ASPERA 


NUTRIENT  FORAMINA 


FOR  FEMORAL  ARTERY 


INTERNAL  CONOYUR  LINE 
Adductor  magnus 


ADDUCTOR  TUBERCLE 
Gastrocnemius 


•—     Internal  lateral  ligamenx 


NTERNAL  CONDYLE 


Posterior  crucial  ligament 


150 


THE  SKKLFAVN 


of  the  inner  lip.  The  adductor  loayuii  and  lyrevts  are  inserted  into  the  intervening 
space;  the  adductor  longus  takes  rather  more  than  the  middle  third,  and  overlaps 
the  lower  jtart  of  the  adductor  hrevis,  wliich  takes  rather  more  than  the  upper 
third.  The  outer  lip  in  its  lower  two-thirds  gives  origin  to  the  shorter  head  of  the 
biceps.  Tlie  condylar  lines  are  two  in  numlaer;  the  outer  is  continuous  with  the 
outer  lip  of  the  Hnca  aspera  and  terminates  inferiorly  on  the  outer  edge  of  the 
external  condyle.  From  the  ui)per  lialf  of  this  line  a  part  of  the  short  head  of  the 
biceps  arises.  '  Near  its  termination  the  line  expands  to  give  origin  to  the  plantaris 
and  the  outer  head  of  the  gastrocnemius.  The  inner  condylar  line  is  not  so  promi- 
nent as  the  outer;  it  is  continuous  with  the  imier  lip  of  the  linea  aspera,  and 
terminates  at  the  adductor  tubercle.  The  adductor  magnus  is  inserted  into  the 
whole  length  of  the  line  and  to  the  tuhercle.  Near  the  middle  of  the  line  there  is 
an  interruption  where  tlie  femoral  artery  passes  through  the  opening  in  the  tendon 
of  the  adductor  magnus.  The  inner  head  of  the  gastrocnemius  arises  from  the 
femur  immediately  ahove  the  internal  condyle.  The  space  enclosed  between  these 
diverging  lines  forms  part  of  the  anterior  boundary  of  the  popliteal  space,  and  is  in 
close  relation  with  the  popliteal  vessels.     The  shaft  of  the  femur  is  overlapped  on 


Fig.  160. — The  Fkmvr  at  Birth. 


APPEARS  EARLY  IN   THE  NINTH   MONTH   OF  INTRA-UTERINE  LIFE 


the  inner  side  Ity  the  vastus  internus,  and  on  the  outer  side  it  gives  origin  in  the 
upper  thrrc-fourths  to  the  crurens  and  is  overlapped  by  the  vastus  externus.  The 
upper  three-fourths  of  the  anterior  surface  serves  for  the  origin  of  the  crureus,  and 
the  lower  fourtli  gives  attachment  to  the  sul)crureus. 

The  lower  ('xtremity  ].resents  two  cartilage-covered  condyles,  separated  bv  a 
deep  notch.  The  external  condyle  is  more  prominent  anteriorly  and  wider  tlian 
its  fellow.  The  internal  is  more  i)rominent  ])osteriorlv,  and  narrower;  it  is  also 
longer,  to  compensate  for  tlie  ol)ii(iuity  of  the  shaft.  When  the  femur  is  properiv 
articulated,  the  inferior  surfaces  of.  the  condyles  are  nearlv  on  the  same  plane,  and 
ahnost  ])arallel  to  come  into  contact  with  the  articular  surfaces  on  the  head  of  the 
tibia.  Posteriorly  the  condyles  are  separated  bv  a  deep  pit  or  notch;  anteriorlv 
they  are  unit.'d  l)y  an  articular  surface,  over  which  the  patella  glides.  The  inner 
surface  of  tlie  internal  condyle  lias,  near  its  postenor  border,  a  rough  surface  for  the 
internal  lat.-ral  ligament  of  the  knee-joint;  above  this  is  the  adductor  tubercle. 
The  surface  of  tins  condyle,  which  bounds  the  intercondyloid  notch,  aft'ords 
attachment,  near  the  anterior  border,  to  the  posterior  crucial  litianient.  The  surface 
of  the  external  condyle  which  bounds  the  notch  gives  attacliment,  at  its  post(n-ior 


THE  FEMUR 


151 


part,  to  the  anterior  crucial  ligament.  The  outer  surface  of  the  external  condyle 
presents  near  the  lower  and  posterior  margin  a  deep  groove,  which  receives  the 
tendon  of  the  jjopliteus  muscle  when  the  leg  is  flexed.  The  anterior  end  of  the 
groove  terminates  in  a  pit  which  gives  origin  to  the  popliteus  tendon.  The  groove 
is  surmounted  by  a  tubercle  for  the  external  lateral  ligament  of  the  knee. 

The  patellar  facet  is  trochlear  in  shape;  its  outer  portion  is  more  extensive 
than  the  inner,  corresponding  to  the  disposition  of  the  articular  facets  on  the 
povsterior  surface  of  the  patella. 


Fig.   161. — The  Left  Fe.mur  at  the  Twentieth  Year.     (Posterior  view.) 


APPEARS    IN    THE    FIRST,   AND    FUSES   IN   THE 
TWENTIETH  YEAR 


APPEARS   IN  THE   FOURTH.  AND  UNITES  IN  THE 
NINETEENTH   YEAR 


APPEARS   IN   THE   FOURTEENTH,    AND    UNITES 
IN  THE  EIGHTEENTH   YEAR 


APPEARS  EARLY  IN  THE  NINTH  MONTH  OF 
INTRA-UTERINE  LIFE,  AND  UNITES  AT 
THE  TWENTY-FIRST  YEAR 


Muscles  attached  to  the  femur: 


Piriformis. 

Obturator  internus  and  gemelli. 

Obturator  externus. 

Pectineus. 

Quadratus  femoris. 

Gluteus  maximus. 

Gluteus  medius. 

Gluteus  minimus. 

Psoas. 

Iliacus. 


Adductor  brevis. 
Vastus  internus. 
Adductor  magnus. 
Adductor  longus. 
Vastus  externus. 
Crureus  and  subcrureus. 
Biceps. 

Gastrocnemius. 
Plantaris. 
Popliteus. 


152 


THE  SKELETON 


Ligaments  : — 

Capsuhir  of  hip-joint.  External  lateral  of  knee-joint. 

Litianicntiuu  teres.  Anterior  crucial. 

Internal  lateral  of  knee-joint.  Posterior  crucial. 

Posterior,  or  Winslow's. 

Blood-supply. — The  head  and  neck  of  the  femur  receive  branches  from  the 
sciatic,  i)l)turator,  and  circumflex  arteries.  The  trochanter  receives  twigs  from  the 
circumflex  arteries.  The  nutrient  vessel  for  the  shaft  is  derived  from  the  second 
perforating;  it  enters  near  the  middle  of  the  linea  aspera,  and  is  directed  towards 
the  head  of  tlie  bone.  The  condyles  are  nourished  by  articular  branches  from  the 
jtoplitcal  and  the  anastomotic  of  the  femoral. 

Ossification. — The  shaft  of  the  femur  begins  to  ossify  in  the  seventh  week  of 
intra-uterine  life.  Early  in  the  ninth  month  a  nucleus  appears  for  the  condyles. 
During  the  iirst  year  the  nucleus  for  the  head  of  the  bone  is  visible,  and  one  for 
the  greater  troclianter  in  the  fourth  year.  The  centre  for  the  lesser  trochanter  is 
visible  about  the  thirteenth  or  fourteenth  year.  The  lesser  trochanter  joins  the 
shaft  at  the  eighteenth,  the  greater  trochanter  at  the  nineteenth,  the  head  about  the 
twentieth,  and  the  condjdes  at  the  twenty-first  year. 

The  neck  of  the  femur  is  an  apophysis,  or  outgrowth  from  the  shaft.  The  line 
of  fusion  of  the  condyloid  epiphysis  passes  through  the  adductor  tubercle. 

The  morpliological  relation  of  the  patellar  facet  to  the  articular  portions  of  the 
condyles  is  worth  notice.  In  a  few  mammals,  such  as  the  ox,  this  facet  remains 
separated  from  the  condyles  by  a  furrow  of  rough  bone.  In  the  human  femur  it  is 
faintly  marked  oft"  by  a  shallow  groove  in  the  cartilage,  best  seen  in  a  recently 
opened  knee-joint.  Some  anatomists  attribute  these  grooves  in  the  cartilage  to  the 
pressure  of  the  semilunar  fil)ro-cartilages. 

The  angle  Avhich  the  neck  of  the  femur  forms  with  the  shaft  measures  at  birth, 
on  an  average,  160°.  In  the  adult  it  varies  from  110°  to  140°;  hence  the  angle 
decreases  greatly  during  the  period  of  growth.  \¥hen  once  growth  is  completed, 
the  angle,  as  a  rule,  remains  fixed.      (Humphry.) 


THE  PATELLA 


The  patella  is  a  sesamoid  bone,  somewhat  triangular  in    shape,   situated    in 
front  of  the  knee-joint.     Its  anterior  surface  is  slightly  convex,  and  pitted  with 


Fig.  162.— The  Lp:ft  Patella. 


Anterior  surface 


Po.sterior  surface 

EXTERNAL  ARTICULAR  FACET 


LATERAL  FACET 
FOR  INTERNAL 
CONDYLE 


FOR  THE 
PATELLAR 
LIGAMENT 


small  openings,  which  transmit  nutrient  vessels  to  the  interior  of  the  bone.     This 


THE  TIBIA  153 

surface  is  subcutaneous;  a  bursa  intervenes  between  it  and  the  skin.  The  posterior 
surface  is  concave,  and  in  great  part  cartilage-covered,  forming  a  compound  articu- 
lar surface  for  gliding  upon  the  femoral  condyles.  A  slightly  marked  vertical 
ridge  divides  this  surface  into  an  outer  larger  portion  for  the  external  condyle,  and 
an  inner  portion  for  the  internal  condyle.  A  slender  articular  facet  close  to  the 
inner  edge  is  sometimes  marked  off  by  a  faint  vertical  ridge;  this  facet  comes 
in  contact  with  the  internal  condyle  in  extreme  flexion  of  the  leg.  The  lower 
part  of  the  bone  is  terminated  by  a  blunt  point,  which  is  embedded  in  the  patellar 
ligament,  especially  on  the  posterior  aspect.  The  upper  two-thirds  of  the  circum- 
ference receives  directly  the  fibres  of  the  vastus  internus  and  externus,  the  crureus 
and  rectus  femoris  muscles. 

Blood-supply. — The  patella  receives  tAvigs  from  the  superficial  In-anch  of  the 
anastomotica,  anterior  tibial  recurrent,  and  the  inferior  articular  of  the  popliteal. 

Ossification. — Tlie  cartilage  for  the  patella  appears  in  the  fourth  month  of 
intra-uterine  life.     The  ossitic  nucleus  is  visible  in  the  third  year. 


TRU  TIBIA 

The  tibia  is  the  larger  bone  of  the  leg;  it  is  situated  on  the  inner  side  of,  and 
nearly  parallel  Avith,  the  fibula.  The  upper  extremity,  or  head,  consists  of  two 
lateral  eminences,  or  tuberosities.  The  superior  surfaces  of  the  tuberosities  receive 
the  condyles  of  the  fenuu',  the  articular  surfaces  being  separated  by  a  non-articular 
ridge,  to  Avhich  ligaments  are  attached.  The  internal  articular  surface  is  oval 
in  shape  and  concave  for  the  internal  condyle  of  the  femur.  The  external 
articular  surface  is  smaller,  somcAvhat  circular  in  shape,  and  presents  an  almost 
plane  surface  for  the  external  condyle.  The  peripheral  portion  of  each  articular 
surface  is  overlaid  by  a  fibro- cartilage  of  semilunar  shape,  connected  with  the 
margins  of  the  tuberosities  by  bands  of  fibrous  tissue  termed  coronary  ligaments. 
Each  semilunar  fibro-cartilage  is  attached  firmly  to  the  rough  tract  separating  the 
articular  surfaces.  This  intermediate  space  is  broad  and  depressed  in  front,  where 
it  affords  attachment  to  the  anterior  limlj  of  the  internal  and  external  semilunar 
cartilages  and  the  anterior  crucial  ligament.  Projecting  upAvards  from  the  middle  of 
this  surface  is  the  spine  of  the  tibia.  The  posterior  aspect  of  the  base  of  the  spine 
affords  attachment  to  the  posterior  limb  of  the  external  and  internal  semilunar 
fibro-cartilages,  and  limits  a  deep  notch  inclined  toAvards  the  inner  tuberosity;  this 
notch  gives  origin  to  the  jiosterior  crucial  ligament.  Anteriorly,  the  tAvo  tuberosities 
are  confluent,  and  form  a  somcAvhat  flattened  surface  of  triangular  outline;  its  apex 
forms  the  tubercle  of  the  tibia.  The  ligamentum  patellte  is  inserted  into  the 
loAver  part  of  the  tuljercle;  the  upper  part  is  smooth  and  separated  from  the  liga- 
ment l)v  a  bursa.  Laterally,  the  inner  tuberosity  is  less  prominent  though  more 
extensive  than  the  outer;  near  the  posterior  part  of  its  circumference  there  is  a  deep 
horizontal  groove  for  the  central  portion  of  the  semimembranosus  tendon.  The 
margins  of  this  groove  and  the  surface  of  bone  beloAV  give  attachment  to  the  internal 
lateral  ligament  of  the  knee.  At  a  corresponding  point  of  the  outer  tuberosity  there 
is  a  rounded  articular  facet  for  the  head  of  the  fibula;  the  circumference  of  the 
facet  is  rough  for  ligaments.  Above  and  in  front  of  it  is  a  ridge  for  the  ilio-tibial 
band. 

The  shaft  is  prismatic,  and  A'ery  thick  near  the  head;  towards  the  loAver  third  it 
is  thinner  and  tapering,  and  gradually  expands  toAvards  the  loAver  end.  It  has  three 
borders  :  the  anterior  is  very  prominent,  and  known  as  the  crest  of  the  tibia  : 
commencing  on  the  outer  edge  of  the  tubercle,  it  runs  downwards  and  curves 
iuAvards,  to  terminate  at  the  anterior  margin  of  the  malleolus.  This  border  gives 
attachment  to  the  deep  fascia  of  the  leg.  The  internal  border  starts  from  the 
back  of  the  internal  tuberosity,  and  ends  at  the  posterior  margin  of  the  malleolus. 


154 


TJIK  SKELETON 


Internal  flbro-cartilage 

Coronary  ligament 

Anterior  crucial  ligament 

INNER  TUBEROSITY 

Internal  lateral  ligament 

Ligamentum  patellae 

iQuadriceps  extensor) 

Gracilis 

SartoriuB 

Semitendinosus 


EXTERNAL  SURFACE  OF  TIBIA 
Tibialis  anticus 


ANTERIOR  BORDER  OR  CREST  OF  THE  TIBIA 


Fkj.  !():$.— The  Lkft  Tibia  and  Fiiui.a. 

spine  of  tibia 


(Auterior  view.) 


INTERNAL  SURFACE  OF  TIBIA 


InteroBeoous  membrane 


Anterior  ligament  of  ankle-joiiil  _ 

Internal  lateral  ligament 

INTERNAL  MALLEOLUS  _ 


External  fibro-eartilage 
Capsule 

OUTER  TUBEROSITY 

Biceps  and  the 

Anterior  tibio-flbular  ligament 

—  External  lateral  ligament 


Extensor  longus  digitorum 


reroueus  longus 


Peroneus  brevis 


Extensor  longus  digitorum 


PERONEAL  SURFACE  OF  FIBULA 


EXTENSOR  SURFACE  OF  FIBULA 
Extensor  proprius  hallucis 


-  FIBULA 


PeroneuB  tertius 


—  SUBCUTANEOUS  PORTION 


: —  Anterior  tibio-flbular  ligament 


EXTERNAL  MALLEOLUS 
External  lateral  ligament 
(Anterior  fasciculus) 


rJBJA   AND   FIBULA 


155 


Fi(i.  164.— The  Left  Tibia  and  Fibula.     (Posterior  view.) 

PCirEAL  NOTCH 


External  flbro-cartilage 


a?!-  - 


STYLOID  PROCESS   -  —    -t/VJuJ^*       ii{^^    ,' 


Posterior  tibio-fibular  ligament 


Tibialis  postieuB 


Flexor  longus  hallueis 


FLEXOR  SURFACE  CF   FIBuLA 


NUTRIENT  FORAMEN  _ 


Feroneus  breviB 


Posterior  tibio-flbular  ligament 

GROOVE  FOR  FLEXOR  LONGUS  HALLUCIS 


External  lateral  ligament 
(posterior  fasciculus 


External  lateral  ligament                 V>, 
(middle  fasciculus,        " 


Internal  flbro-cartilage 

Capsule 

Semimembranosus 


POSTERIOR  SURFACE  OF  TIBIA 


Flexor  longus  digitorum 


GROOVE  FOR  TIBIALIS  POSTICUS  AND 
FLEXOR  LONGUS  DIGITORUM 


Internal  lateral  ligament 


Posterior  ligament  of  ankle-joint 


156  THE  SKELETON 

The  internal  latrral  ligament  is  attached  to  its  upix-r  7o  em.  (3"),  and  the  middle 
third  jiive-s  origin  to  the  >ioleii.s.  The  interosseous  border  extends  from  the  tibular 
facet  on  the  outer  tuberosity  to  the  lower  end  of  the  bone;  towards  its  termination 
the  l>order  bifurcates  to  enclose  a  triangular  space  for  the  attachment  of  the  inter- 
osseous ligament  between  the  tibia  and  lilnila.  The  part  above  the  bifurcation  is 
connected  with  the  interosseous  membrane. 

These  borders  limit  three  surfaces.  The  internal  surface  is  Ijounded  by  the 
internal  l)order  and  the  crest;  it  is  broad  above,  where  it  receives  the  insertion  of 
the  sartorim,  gracilii,  and  .'<emiteii(liiwsus ;  the  rest  of  the  surface  is  convex  and 
subcutaneous.  The  external  surface  lies  between  the  crest  of  the  tibia  and  the 
interosseous  l)order.  The  u\)\)ev  two-thirds  presents  a  hollow  for  the  origin  of 
the  tibialis  anticKs;  the  rest  of  the  surface  is  overlaid  by  the  extensor  tendons  and 
the  anterior  tibial  vessels.  The  posterior  surface  is  limited  by  the  interosseous 
ridge  and  the  internal  border.  The  upper  part  presents  a  rough  oblique  ridge, 
extending  from  the  tibular  facet  on  the  outer  tuberosity  to  the  internal  ])order,  a 
little  above  the  middle  of  the  bone.  This  oblique  ridge  gives  origin  to  the  soleu.-> 
and  attachment  to  the  popliteal  fascia;  the  surface  above  is  for  the  insertion  of  the 
poplitens.  An  indefinite  vertical  ridge  commences  near  the  middle  of  the  oblique 
line,  and  marks  off  a  semilunar  space,  limited  externally  by  the  interosseous  border. 
This  is  for  the  tibialis  2:>osticus ;  it  extends  as  low  as  the  junction  of  the  middle  and 
lower  thirds.  The  portion  of  bone  inside  this  vertical  line  is  for  the  flexor  longus 
digitorum.     The  loAver  third  of  the  posterior  surface  is  covered  by  flexor  tendons. 

The  inferior  extremity  is  somewhat  quadrilateral,  and  reseml)les  the  distal  end 
of  the  radius.  Its  inferior  surface  is  articular  for  the  upper  surface  of  the  astraga- 
lus and  is  continuous  with  the  external  surface  of  the  malleolus,  which  articulates 
Avith  the  facet  on  the  inner  side  of  the  astragalus.  The  outer  surface  has  a  triangular 
rough  area  for  the  lower  end  of  the  shaft  of  the  fibula,  its  margins  being  rough  for 
ligaments.  The  anterior  border  is  slightly  convex,  and  by  its  margin  gives  attach- 
ment to  the  anterior  ligament  of  the  ankle.  The  posterior  surface  has  two  grooves: 
the  one  which  encroaches  on  the  malleolus  is  for  the  tendons  of  tibialis  jMsticus 
and  flexor  longus  digitorum,  and  an  outer  shallow^  groove  for  the  tendon  of  flexor 
longus  halbfcis.  The  inner  surface  is  prolonged  downwards  to  form  the  malleolus  ; 
from  its  tip  and  margins  the  internal  lateral  (deltoid)  ligament  of  the  ankle-joint 
arises.  The  inner  surface  of  the  malleolus  is  convex  and  subcutaneous;  the  outer, 
as  already  stated,  has  a  facet  for  the  inner  surface  of  the  astragalus. 

The  ti1)ia  affords  attachment  to  the  following  muscles  : — 

Semimembranosus.  Tibialis  posticus. 

Sartorius.  Tibialis  anticus. 

Gracilis.  Soleus. 

Semitendinosus.  Peroneus  longus. 

Quadriceps  extensor.  Flexor  longus  digitorum. 

Popliteus.  Extensor  longus  digitorum. 
Tensor  vaginse  femoris  (indirectly).        Bicej^s  femoris. 

Ligaments  : — 

Anterior  crucial.  Coronary. 

Posterior  crucial.  Anterior  tiljio-fibular  (superior). 

Internal  lateral  of  the  knee.  Posterior  tibio-fibular  (superior). 

Internal  semilunar  cartilage.  Ilio-tibial  band. 

External  semilunar  cartilag(\  Interosseous  membrane. 

Anterior  tibio-lil)ular  (inferior).  Anterior  annular  (oblique). 

Posterior  tibio-fibular  ^inferior).  Internal  annular. 

Anterior  of  ankle.  Internal  lateral  of  ankle  (deltoid). 

Anterior  annular  (transverse).  Posterior  (of  ankle). 

Transverse. 

Blood-supply.— The  tibia  is  a  very  vascular  bone.  The  nutrient  arterv  for  the 
shaft  is  furnished  I >y  tiie  posterior  tibial;  it  enters  the  bone  near  the  interosseous 


TIBIA   AXD   FIBULA 


157 


border  at  tlic  junction  of  the  upper  and  middle  thirds,  and  is  directed  downwards. 
The  head  of  the  hone  receives  numerous  l)ranclaes  from  the  inferior  articuhir 
arteries  of  the  i)0])hteal,  and  the  recurrent  branches  of  the  anterior  and  posterior 
til)ial  arteries.  The  lower  extremity  receives  twigs  from  the  posterior  and  anterior 
tibial,  the  anterior  peroneal,  and  internal  malleolar  arteries. 


Fig.  165.— The  Tibia  axd  Fibula  at  the  Sixteenth  Year. 


APPEARS  AT  BiRTH;  UNITES  AT  TWENTY-ONE;  BUT 
IS  SOMETIMES  DEUYED  TO  TWENTY-FIVE 


APPEARS  AT  THE  FIRH  YEAR;  UNITES  AT 
TWENTY- TWO 


APPEARS  AT  SECOND  YEAR;   UNITES  AT  THE 
EIGHTEENTH  YEAR 


APPEARS  AT  THE  SECOND  YEAR;    UNITES  AT 
TWENTY 


Ossification. — The  centre  for  the  shaft  of  the  tibia  appears  in  the  eighth  week 
of  intra-uterine  life.  Towards  the  end  of  the  ninth  month,  a  small  earthv  nucleus 
appears  in  the  cartilaginous  head  of  the  tibia.  The  nucleus  for  the  lower  ex- 
tremity appears  in  the  second  year,  and  unites  with  the  shaft  at  eighteen.  The 
epiphysis  for  the  head  of  the  bone  is  one  of  the  last  to  unite  with  its  shaft;  this 
event  usually  occurs  about  the  twenty-first  year,  but  may  be  delayed  until  twentv- 
five.  The  tubercle  of  the  tibia  is  usually  ossified  from  the  epiphysis;  occasionally 
it  has  an  independent  nucleus. 


158  THE  SKELETON 


THE  FIBULA 

This  is  a  long  slender  l)one  lying  postero-externally  in  the  leg,  to  the  outer  side  of 
and  somewhat  i)osteri()r  to  the  tibia,  with  which  it  articulates  both  above  and  below. 
It  is  excluded  from  the  knee-joint  but  forms  the  outer  boundary  of  the  ankle-joint. 

The  upper  extremity,  or  head,  is  a  rounded  prominence.  Its  u])per  surface  is 
rough  externally  for  the  attachment  of  the  biceps  tendon  and  the  long  external 
lateral  ligament  of  the  knee-joint;  internally  it  presents  a  round  or  oval  articular 
facet  for  the  outer  tuberosity  of  the  tibia;  the  margins  of  this  facet  give  attachment  to 
the  capsular  ligament  of  the  superior  tibio-fibular  articulation.  Posteriorly,  it  rises 
into  a  pointed  process,  the  styloid  process,  which  gives  attachment  at  its  apex  to 
the  short  external  lateral  ligament  of  the  knee  and  laterally  to  part  of  the  biceps 
tendon.  The  posterior  aspect  of  the  head  gives  attachment  to  the  soleus,  the  outer 
to  the  peroneus  longus,  the  anterior  to  the  extemor  longus  digitorum,  and  the  inner 
lies  adjacent  to  the  tibia. 

The  lower  extremity,  external  malleolus,  is  a  triangular  piece  of  bone  placed 
with  the  base  uppermost.  Its  outer  surface  is  convex  and  subcutaneous.  The  inner 
surface  is  divided  into  an  anterior  and  upper  area,  triangular  in  outline  and  convex 
from  above  downwards  for  articulation  with  the  outer  side  of  the  astragalus,  and  a 
lower  and  posterior  excavated  area,  the  digital  fossa,  in  Avhich  are  attached  the 
transverse  inferior  tibio-fibular  ligament  and  the  posterior  band  of  the  external 
lateral  ligament  of  the  ankle.  The  anterior  border  is  rough;  it  gives  attachment  to 
the  anterior  band  of  the  external  lateral  ligament  of  the  ankle,  the  anterior  inferior 
tibio-tibular  ligament,  and  the  anterior  annular  ligament.  The  posterior  border  is 
grooved  for  the  peronei  tendons,  and  the  apex  gives  attachment  to  the  middle  band 
of  the  external  lateral  ligament  of  the  ankle. 

The  shaft  is  quadrangular,  possessing  four  borders  and  surfaces.  The  antero- 
external  border  commences  in  front  of  the  head  and  terminates  lielow  by  dividing  to 
enclose  the  subcutaneous  surface  on  the  outer  side  of  the  external  malleolus.  The 
antero-internal  border  also  commences  in  front  of  the  head,  close  to  the  antero- 
extt'rnal  liorder;  it  terminates  below  by  dividing  to  enclose  a  rough  triangular 
area  innuediately  above  the  facet  for  the  astragalus;  this  area  gives  attachment 
to  the  inferior  interosseous  ligament,  and  sometimes  bears  at  its  lower  end  a 
narrow  facet  for  the  tibia.  The  postero-internal  border  commences  at  the  inner 
side  of  the  head  and  terminates  below  by  joining  the  antero-internal  border  at  the 
upper  part  of  the  lower  fourth  of  the  shaft.  The  postero-external  border  runs  from 
the  back  of  the  head  to  the  inner  border  of  the  peroneal  groove  on  the  back  of  the 
lower  extremity;  it  gives  attachment  to  the  fascia  separating  the  peronei  and  the 
flexor  muscles. 

The  anterior  or  extensor  surface  between  the  antero-internal  and  antero-external 
l)()rders  is  narrow  above  but  broader  below;  three  muscles  spring  from  it:  externally 
in  the  ui)i)('r  two-thirds  the  extensor  longus  digitorum,  and  in  the  lower  third  the 
j,n-n,irtis  tcrfiiis;  internally  in  the  middle  third  the  extensor  longus  haUiicis.  The 
internal  surface  l)etween  the  antero-  and  postero-internal  borders  is  usuallv  concave; 
it  Ls  narrow  al)ov(;  and  below,  and  broadest  in  the  middle;  it  is  frequently  crossed 
l)y  on(>  or  more  o])li(iue  ridges,  and  it  gives  attachment  to  the  <t6/a//./ ^)ox;wrs. 
The  posterior  surface  between  the  postero-internal  and  external  l^orders  is  twisted; 
it  looks  Ijackwards  al>ove  and  inwards  below;  in  its  upper  third  it  gives  attach- 
ment to  the  soleiis  and  in  the  lower  two-thirds  to  the  flexor  longus  hallucis.  The 
external  surface  ])etween  the  antej-o-  and  postero-external  borders  is  also  twisted, 
looking  outwards  abo\c  and  backwards  below,  where  it  is  continuous  with  the 
groove  on  the  peronei  tendons;  it  gives  attachment  in  its  upper  two-thirds  to  the 
pernnens  longus  and  in  the  lower  two-thirds  to  the  peroneiix  brevis. 

The  muscles  arising  from  the  libula  are: — 

Soleus.  Peroneus  tertius. 

Tibialis  i)osticus.  Flexor  longus  hallucis. 


THE  FOOT  159 

Peroneus  longus.  Extensor  longus  digitorum. 

Peroneus  brevis.  Extensor  proprius  hallucis. 

The  fibula  affords  insertion  to  the  biceps. 

The  following  ligaments  are  connected  with  it : — 

External  lateral  of  the  knee.  Transverse. 

Anterior  tibio-fibular.  Anterior  tibio-fibular  (inferior). 

Posterior  tibio-fibular.  Posterior  tibio-fibular. 

Interosseous  membrane.  External  annular. 

External  lateral  ligament  of  ankle.  Anterior  annular  (vertical). 

Blood-supply. — The  fibula  receives  the  nutrient  artery  of  its  shaft  from  the 
peroneal  Ijranch  of  the  posterior  tibial.  The  head  is  nourished  by  branches  from 
the  inferior  external  articular  branch  of  the  pophteal  artery,  and  the  malleolus  is 
supplied  mainly  by  the  peroneal,  anterior  peroneal,  and  external  malleolar  arteries. 

Ossification. — The  shaft  of  the  fibula  commences  to  ossify  in  the  eighth  week 
of  intra-uterine  life.  A  nucleus  appears  for  the  lower  in  the  second  year,  and  one 
in  the  fifth  year  for  the  upper  extremity.  The  lower  extremity  fuses  with  the  shaft 
about  twenty,  but  the  upper  one  remains  separate  until  the  twenty-second  year. 

The  human  fibula  differs  from  all  others  in  the  excessive  length  of  its  malleolus; 
in  no  other  vertebrate  does  this  process  descend  below  the  level  of  the  tibial  malle- 
olus. In  the  majority  of  mammals  the  tibial  descends  to  a  lower  level  than  the 
fibular  malleolus.  In  the  human  embryo  of  the  fourth  month,  the  outer  (fibular) 
is  very  much  smaller  than  the  inner  (tibial)  malleolus.  At  the  seventh  month 
they  are  equal  in  length;  at  birth,  the  fibular  malleolus  is  the  longer;  and  by  the 
second  year  it  assumes  its  adult  proportion.      (Gegenbaur. ) 

The  fibula  is  a  vestigial  bone  in  man,  and  survdves  mainly  on  account  of  the 
excessive  development  of  its  malleolus.  This  accounts  for  the  fact  that  the  loAver 
epiphysis,  though  appearing  first,  unites  with  the  shaft  before  the  upper  epiphysis. 
In  birds,  the  head  of  the  bone  is  large,  and  enters  into  the  formation  of  the  knee- 
joint,  whilst  the  lower  end  atrophies. 


THE  FOOT 

The  bones  comprised  in  the  skeleton  of  the  foot  are  arranged  in  three  groups: — 
tarsus,  metatarsus,  and  phalanges. 

The  tarsus  consists  of  seven  l)ones: — The  astragalus,  os  calcis  or  calcaneum, 
scaphoid,  cuboid,  and  three  cuneiform  bones. 


THE  ASTRAGALUS 

This  bone  may,  for  descriptive  purposes,  be  divided  into  a  body,  neck,  and 
head.  The  body  is  quadrilateral.  Its  upper  aspect  resembles  a  segment  of  the 
wheel  of  a  pulley;  hence  it  is  called  the  trochlear  surface.  It  is  broader  in  front 
than  ])ehind,  and  articulates  with  the  lower  end  of  the  tibia. 

The  inferior  surface  is  occupied  by  an  elongated  concave  facet  for  articulation 
with  the  calcaneum. 

The  internal  surface  presents  a  pyriform  facet,  broad  in  front,  and  continuous 
with  the  trochlea:  it  articulates  with  the  tibial  malleolus.  Below  this  facet,  the 
inner  surface  is  rough  for  the  attachment  of  the  deep  fibres  of  the  deltoid  ligament. 

The  external  surface  is  almost  entirely  occupied  by  a  triangular  concave  facet, 
broad  above  where  it  is  continuous  with  the  trochlea,  for  articulation  with  the 
fibular  malleolus. 


160 


THE  SKELETON 


The  posterior  surface  is  little  more  than  a  ridge  of  bone  traversed  obliquely 
by  a  deep  groove,  Avhich  receives  the  tendon  of  the  flexor  longus  hallucis  muscle. 
Externally,  this  groove  is  limited  by  a  prominent  tubercle,  Avhich  affords  attach- 
ment to  tile  posterior  fasciculus  of  the  external  lateral  ligament  of  the  ankle. 


Fig.  166. — The  Left  Foot.     (Dorsal  surface.) 

Teudo  Achilli: 


Extensor  brevis 
digitorum 


Extensor  longus 
hallucis 


Extensor  brevis 
digitorum 


Peroneus  brevis 


PeroneuB  tertius 


FIRST  PHALANX 


SECOND  PHALANX 
THIRD  PHALAMX 


Extensor  longus  digitorum 


The  neck  is  tin-  constricted  portion  of  the  Iwne,  and  is  continuous  posteriorly 
with  the  l)ody  of  tlie  astragalus.  Superiorly,  the  neck  is  rough,  and  lias  numerous 
foramina  for  blood-vessels.     Infcriorly,  it  presents  a  deep  groove,   directed  from 


THE  FOOT 


161 


behind  forwards  and  outwards.  When  the  astragalus  is  articulated  Avith  the 
ealcaneum,  this  furrow  is  converted  into  a  canal  in  which  is  lodged  the  calcanco- 
astragaloid  (interosseous)  ligament.  The  inner  edge  of  this  furrow  is  limited  by 
an  articular  facet,  which  runs  forwards  to  become  continuous  with  the  facet  on  the 


POSTERO-INFERIOR  SURFACE  OF  THE 
CALCANEUM 


Fui.   KJT.— The  Lkft  Foot.     (Plantar  surlaoe.) 


Abductor  minimi  digiti 
Abductor  ossis  metatarsi  quinti 

Accessorius  (outer  head, 


Flexor  brevis  hallucis 
Abductor  oasis  metatarsi  quinti  — 

Flexor  brevis  minimi  digiti 

Adductor  hallucis 
Third  plantar  interosseous 

Second  plantar  interosseous 
First  plantar  interosseous 

Flexor  brevis  minimi  digiti 

Abductor  brevis  minimi 
digiti 

Third  plantar 
interosseous 


Second  plantar 
interosseous 


rirst  plantar  interosseous 


Flaxor  brevis  digitorum 
Flexor  lougus  digitorum 


Abductor  hallucis 
Flexor  brevis  digitorum 


Accessorius  dinner  head) 


Tibialis  posticus 


Tibialis  amicus 
Peroneus  longus 


Abductor  hallucis 
Flexor  brevis  hallucis 

inner  portion  i 
Flexor  brevis  hallucis 

(outer  portion; 
Adductor  hallucis 
Transversus  pedis 


Flexor  longus  hallucis 


head  of  the  V)one,  and,  like  the  articular  surface  of  the  sustentaculum  tali  of  the 
ealcaneum  on  which  it  glides,  is  sometimes  divided. 

The  head  of  the  astragalus  is  furnished  anteriorlv  with  an  ovoid  facet,  which 
11 


H)J 


THE  SKELETON 


is  n-ceiv(_'(l  hv  the  jjosterior  surface  of  the  scaphoid.  On  the  inner  and  lower  part, 
at  the  spot  where  the  sustentaeular  facet  becomes  confluent  with  that  on  the  head, 
thert"  is  a  smaller  facet  separated  by  a  ridge:  this  plays  upon  the  calcaneo-scaphoid 
or  s])riiiLr  li.Liaiiicnt. 

The  OS  trigonum. — (Occasionally  the  small  jjortion  of  the  astragalus  posterior 
\o    tht'   trochlear   surface   containing   the    groove   Avhich    lodges   the  flexor   longus 


Fig.  168.— The  Lkft  Astragalus.     (Plantar  view.) 


GROOVE  FOR  THE  FLEXOR  LONGUS  HALLUCIS 


FOR  CALCANEUM 


FOR  THE  SUSTENTACULUM  TAL! 


FOR  THE  CALCANEO-SCAPHOID  (OR  THE 
SPRING)  LIGAMENT 


liiilhiris  tendon  is  separate  from  the  rest  of  the  astragalus,  and  is  known  as  the  os 
trigonum,  or  secondary  astragalus  (fig.  169). 

Articulations. — The  astragalus  articulates  with  four  bones,  the  tibia,  fibula, 
scaphoid,  and  calcaneum;  and  presents  seven  articular  facets;  and  when  the  facet 
for  the  sustentaculum  tali  is  divided,  as  is  so  often  the  case,  the  articular  surfaces 

Fig.  1G!).— Ax  Astragalus  with  the  Os  Tkigoxum. 

cs  trigonum 


are  increased  to  eiglit.     Sometiiiies  it  presents  a  facet  on  the  outer  margin  of  its 
head  f<»r  tlie  cuboid,  thus  increjusing  tlie  articular  surfaces  to  nine. 
Ligaments  :  — 


Internal  lateral  ligament  (deltoid). 
External  lateral  ligament. 
Astragalo-.scaphoid. 


Calcanco-astragaloid  (interosseous). 
ICxternal  calcaneo-astragaloid. 
Posterior  calcaneo-astragah )id. 


THE  CALCANEUM  103 

Blood-supply. — The  astragalus  is  supi:»lied  l)y  tlio  dorsalis  pedis  artery  and 
its  tarsal  l)rancli. 

Ossification. — The  astragalus  is  ossified  from  one,  oeeasionally  from  two, 
nuclei.  The  principal  centre  for  this  bone  appears  in  the  middle  of  the  cartilagi- 
nous astragalus  at  the  seventh  month  of  embryonic  life.  The  additional  centre  is 
de])()sitecl  in  the  posterior  portion  of  the  bone,  and  forms  that  part  of  the  astragalus 
■which,  when  it  remains  separate  from  the  rest  of  the  bone,  is  known  as  the  os 
trigonum.  At  birth,  the  astragalus  presents  some  im})ortant  i)eculiarities  in  the 
disjjosition  of  the  articular  facet  on  the  tibial  side  of  its  Ixxly,  and  in  the  oblicjuity 
of  its  neck.  If,  in  the  adult  astragalus,  a  line  be  drawn  through  the  middle  of  the 
trochlear  surface  parallel  with  its  inner  border,  and  a  second  line  be  drawn  along 
the  outer  side  of  the  neck  of  the  bone  so  as  to  intersect  the  first,  the  angle  formed 
by  these  two  lines  will  express  the  obliquity  of  the  neck  of  the  bone.  This  in  the 
adult  varies  greatly,  but  the  average  may  be  taken  as  10°.  In  the  foetus  at  birth 
the  angle  averages  35°,  whilst  in  a  young  orang  it  measures  45°.  In  the  normal 
adult  astragalus  the  articular  surface  on  the  tibial  side  is  limited  to  the  body  of  the 
l)one.  In  the  fa?tal  astragalus  it  extends  for  some  distance  on  to  the  neck,  and 
sometimes  reaches  almost  as  far  forward  as  the  scaphoid  facet  on  the  head  of  the 
bone.  This  disposition  of  the  inner  malleolar  facet  is  a  characteristic  feature  of 
the  astragalus  in  the  chimpanzee  and  the  orang.  It  is  related  to  the  inverted 
2)osition  of  the  foot  which  is  found  in  the  human  endoryo  to  near  the  period 
of  birth,  and  is  of  interest  to  the  surgeon  in  connection  with  some  varieties  of 
clul)-foot.      (Shattock  and  Parker. ) 


THE  CALCANEUM 

The  calcaneum,  or  os  calcis,  is  the  largest  tarsal  bone.  It  is  cul)oidal  in 
sliaj)e,  and  presents,  for  examination,  six  surfaces. 

The  superior  surface  has  in  its  nnddle  a  large,  oval,  convex,  articular  facet 
for  the  under  aspect  of  the  body  of  the  astragalus;  behind  the  facet,  the  bone  is 
rough  and  convex  laterally.  In  front  of  the  facet  the  bone  presents  a  deep  depres- 
sion, the  floor  of  which  is  rough  for  the  attachment  of  ligaments,  especially  the 
calcaneo-astragaloid,  and  the  origin  of  the  extensor  brer  is  digitorum  muscle;  when 
tlie  calcaneum  and  astragalus  are  articulated,  this  portion  of  the  bone  forms  a  floor 
to  a  cavity  sometimes  called  the  sinus  pedis.  Internally,  this  u])per  surface  of  the 
bone  presents  a  well-marked  lip,  th(^  sustentaculum  tali,  furnished  Avith  an  elon- 
gated concave  facet,  occasionally  divided  into  two,  for  articulation  with  the  neck  of 
the  astragalus. 

The  inferior  surface  is  narrow  and  rough;  it  ends  posteriorly  in  tAvo  tuber- 
cles :  the  inner  is  the  larger  and  broader,  the  outer  is  narrower  but  prominent. 
The  inner  tubercle  affords  origin  to  the  abductor  hallucis,  the  flexor  breris  digitorinn, 
and  the  abductor  minimi  digiti ;  the  last  muscle  also  arises  from  the  outer  tubercle, 
and  the  ridge  of  bone  connecting  the  tubercles.  The  outer  tubercle  aftords  attach- 
ment to  the  abductor  ossis  metatarsi  quinti.  The  rough  surface  in  front  of  the  tul)er- 
cles  gives  attachment  to  the  long  plantar  ligament  (calcaneo-cuboid)  and  the  outer 
head  of  i\ie  flexor  accessorius.  Near  its  anterior  end  this  surface  forms  a  rounded 
eminence,  the  anterior  tubercle,  from  which  (and  the  shallow  groove  in  front)  the 
short  plantar  (calcaneo-cuboid)  ligament  arises. 

The  external  surface  is  rough  and  slightly  convex.  Near  the  middle  of  this 
surface  there  is  a  small  tubercle  for  the  middle  fasciculus  of  the  external  lateral 
ligament  of  the  ankle-joint.  Anteriorly,  w^e  notice  the  two  shallow  peroneal 
grooves,  separated  by  a  tubercle,  which  is  sometimes  very  prominent.  The 
upper  groove  is  for  the  tendon  of  the  peroneus  breris,  and  the  lower  lodges  the 
tendon  of  the  peroneus  longus. 

The  inner  surface  is  deejdy  concave,  the  hollow  lieing  increased  l)y  the  over- 
hanging sustentaculum  tali  in  front  and  above,  and  the  ])rominent  inner  tubercle 
posteriorly.  The  under  aspect  of  tlie  sustentaculum  is  deeply  grooved  for  the 
tendon  of  the  flexor  longus  hallucis,  whilst  the  hollow  below  receives  the  plantar 
vessels  and  nerves.     Its  lower  border  serves  for  the  attachment  of  the  inner  head 


164 


THE  SKELETON 


of  the  iiexor  accemtrim.     The  margin  of  the  sustentaculum  has  attached  to  it  a  part 
of  the  (leltcud  liiraiuent. 

The  anterior  surface  is  a  concave  articular  facet  for  the  posterior  surface  ol  the 
culjoid.      Its  outer  and  superior  angle  is  somewhat  prominent. 

Fig.  170.— The  Left  Calcaneum.     (Dorsal  view.) 


INNER  TUBEflCLE 


INTEROSSEOUS  GROOVE 


FACET  FOR  ASTRAGALUS  ON  THE 
SUSTENTACULUM  TALI 


FOR  ASTRAGALUS 


PERONEAL  TUBERCLE 


Tlic  posterior  surface  is  roughly  rounded;  the  loAver  part  gives  attachment 
to  a  {lad  of  fat;  the  middle  part  serves  for  the  attachment  of  the  tendo  Adiillis.  At 
its  U])i)er  ])art  it  is  smooth,  and  is  in  relation  with  a  bursa. 

Articulations. — The  calcaneum  articulates  with  the  cuboid,  the  astragalus,  and 
with  the  OS  trigonum  when  it  exists  as  a  separate  element. 

Fig.  171.— The  Calcaneum  at  the  Fifteenth  Yeae,  showing  the  Epiphysis. 


APPEARS  AT  THE  TENTH,  AND  UNITES  AT  THE  SIXTEENTH  YEAR 


Muscles  attached  to  the  calcaneum  : — 

Extensor  brcvis  digitorum.  Aliductor  ossis  metatarsi  quinti. 

Abductor  hallucis.  •  Accessorius. 

Flexor  brevis  digitorum.  Tendo  Achillis. 

Abductor  minimi  digiti.  Plantaris. 

And  a  slip  from  the  tibialis  posticus. 
Ligaments  : — 


Internal  lateral  of  ankle. 
External  lateral  of  anklo. 


Anterior  annular. 
Calcaneo-astragaloid  ( interosseous  ) . 


THE  CUBOID 


165 


Superior  calcaneo-cuboid  ligaments 
Inferior  calcaneo-cuboid  ligaments. 
Internal  annular. 
External  annular. 


External  calcaneo-astragaloid. 
Posterior  calcaneo-astragaloid. 
Superior  calcaneo-scaphoid. 
Inferior  calcaneo-seaj  )hoid. 


Blood-supply. — The  calcaneum  is  a  vascular  bone,  and  derives  its  blood  from 
the  posterior  tibial,  and  the  internal  and  external  malleolar  arteries. 

Ossification. — The  primary  nucleus  for  this  bone  is  deposited  in  the  sixth 
month  (jf  embryonic  life.  In  the  tenth  year  a  nucleus  appears  for  the  epiphysis  at 
the  heel,  and  unites  with  the  body  of  the  bone  at  the  sixteenth  year.  The  inner 
and  outer  tubercles  are  formed  by  the  epiphysis. 


THE  CUBOID 

This  bone  is  situated  on  the  outer  side  of  the  tarsus;  its  posterior  surface 
is  reniform  in  shape  and  articular  for  the  anterior  face  of  the  calcaneum.  The 
anterior  surface  is  smaller,  and  divided  by  a  low  vertical  ridge;  the  inner  facet 
is  for  the  base  of  the  fourth,  the  outer  facet  receives  the  base  of  the  fifth  metatarsal 
l)one.  The  upper  (dorsal)  surface  is  rough  and  non-articular.  The  inferior 
(})lantar)  surface  is  divided  by  a  prominent  ridge,  which  limits  a  deep  furrow 


FOR  EXTERNAL  CUNEIFORM 


FOR  CALCANEUM 


GROOVE  FOR  TENDON  OF  TH 
PERCNEUS  L0N6US 


Fig.  172. — The  Lkft  Clbuid.     (luuer  view.) 


FOR  FOURTH  METATARSAl 


Fig.  173. — The  Left  Cuboid.     (Inner  view.) 


FOR   EXTERNAL  CUNEIFORM 
FOR  CALCANEUM 


FOR  SCAPHOID  (OCCASIONAL)   


GROOVE  FOR  TENDON   OF  THE  PERONEUS  LONGUS 


Fig.  174. — The  Left  Cuboid.     (Inner  view.) 


FOR  EXTERNAL  CUNEIFORM 
FOR  SCAPHO'O 


directed  from  without  forwards  and  inwards.     This,  the  peroneal  groove,  lodges 
the  tendon  of  the  peroneus  longiis. 

The  corner  of  the  ridge  on  the  narrow  outer  (fibular)  border  of  the  bone  is 
usually  faceted  for  a  sesamoid  bone  frequently  found  in  the  tendon  of  the  peroneus 
longus.  The  margin  of  the  ridge  and  the  surface  of  bone  behind  it  afford  attach- 
ment to  the  long  and  short  plantar  (calcaneo-cuboid)  ligaments.  The  flexor  brevis 
Jialhicis  muscle  has  a  small  attachment  to  this  part  of  the  cul^oid. 


166 


THE  SKELETON 


The  internal  surface  presents  near  its  middle  and  upper  part  an  oval  faeet  for 
articulation  with  the  external  cuneiform  lione  (fig.  172);  behind  this,  a  second  facet 
for  the  scajihoid  is  freciuentlv  seen  (fig.  173).  Generally  the  two  facets  are  con- 
tinent and  form  an  elliptical"  surface  (fig.  174).  The  remainder  of  the  internal 
surfact^  is  rough,  and  has  strong  interosseous  ligaments  attached  to  it. 

Jutting  from  the  inferior  internal  angle  of  the  posterior  surface  is  a  process  of 
l)(»n('  ( calcanean  process  of  cuboid),  which  projects  beneath  the  sustentaculum  tali. 
This  process  occasionally  terminates  in  a  rounded  facet,  which  plays  on  the  head 
of  the  astragalus  external  to  the  facet  for  the  S])ring  ligament. 

Articulations. — The  cuboid  articulates  Avith  the  calcaneum,  the  external  cunei- 
form, the  fourth  and  fifth  metatarsal  bones,  frequently  with  the  scaphoid,  and 
occasionally  with  the  astragalus. 

Muscles  attached  to  the  cuboid  : — 


Tibialis  posticus. 


Flexor  brevis  hallucis. 


Ligaments  :- 


.Superior  calcaneo-cuboid.  Inferior  calcaneo-cuboid. 

Interosseous  and  the  cubo-scaphoid  ligaments. 

Ossification. — The  cuboid  is  ossified  from  a  single  centre  which  appears  a  few 
weeks  after  birth.  Occasionally  the  nucleus  is  visible  as  a  minute  earthy  spot  in  the 
middle  of  the  cartilage  at  l)irth. 


THE  SCAPHOID 

The  scaphoid  (navicular)  lH)ne  receives  in  the  hollow  of  its  posterior  surface 
the  head  of  the  astragalus.  Anteriorly  it  is  convex,  and  divided  by  tAvo  vertical 
ridges  into  three  facets,  for  the  internal,  middle,  and  external  cuneiform  bones. 


Fig.  175. — The  Left  Scaphoid.     (Anterior  view.) 


FOR  INTERNAL  CUNEIFORM 
INNER   BORDER 

TUBEROSITY 


FOR   MIDDLE   CUNEIFORM 
OUTER    BORDER 


FOR  EXTERNAL  CUNEIFORM 


Occasionally  a  fourth  facet,  extremely  varial)lc  in  size,  is  seen  at  the  outer  inferior 
angle  for  the  culxjid. 

The  upper  (dorsal)  surface  is  rough  and  broad;  the  inferior  (plantar)  surface 


Fi(i.  17().— The  Left  Scaphoid,  showing  a  Facet  fok  the  Cuboid. 


FOR  INTERNAL  CUNEIFORM 


FOR  MIDDLE  CUNEIFORM 


FOR  EXTERNAL  CUNEIFORM 
FOR  CUBOID 


is  nothing  more  than  a  ridgo.  The  outer  surface  is  rougli  for  ligaments;  whilst 
the  inner  forms  a  large  and  i)rominent  eminence,  the  scaphoid  tuberosity,  which 
affords  an  important  attachment  for  the  tibialis  posticus  tendon. 


THE  CUNEIFORM  BOXES 


167 


Articulations. — "With  the  head  of  the  astragahi;^,  Avith  the  three  ciinciforni  bones, 
and  frequently  with  tlie  cuboid. 

Muscle  attached  to  the  scaphoid. — The  tibialis  posticus  is  inserted. 
Ligaments  : — 

Dorsal,  j)lantar,  and  interosseous  cubo-S(^aphoid. 
Dorsal  and  plantar  scapho-cuneiform. 
External  and  inferior  calcaneo-scaphoid. 
Astragalo-scaphoid. 

Ossification. — The  nucleus  for  the  scaphoid  appears  in  the  course  of  the  fourth 
year.  The  tubercle  of  the  scaphoid,  into  which  the  tibialis  posticus  acquires  its 
main  insertion,  occasionally  develoj)S  separately,  and  sometimes  remains  distinct 
from  the  rest  of  the  bone. 

THE  CUNEIFORM  BONES 

The  cuneiform  l)ones,  three  in  number,  are  named  from  within  outwards — 
internal,  middle,  and  external.     They  are  wedge-shaped. 

The  INTERNAL  CUNEIFORM  is  distinguished  by  its  large  size,  and  from  tlie 
fact  that,  when  articulated,  the  base  of  the  wedge  is  directed  downwards,  and  the 


Fig.  177. — The  Left  Interxal  Cuneiform.     (Internal  suriiice.) 


FOR  FIRST  METATARSAL 


FACET  FOR  THE  TENDON   OF  THE  TIBIALIS  ANTICUS 


sharp  border  upAvards.  The  posterior  surface  is  concave  and  pyriform  for  articu- 
lating with  the  inner  facet  of  the  scaphoid.  The  anterior  surface  is  a  reniforrn 
articular  facet  for  the  base  of  the  first  metatarsal.  The  internal  surface  is  rough, 
and  presents  an  oblique  groove  for  the  tendon  of  the  tibialis  anticus  :  this  groove  is 
limited  inferiorly  by  an  oval  facet  into  which  a  portion  of  the  tendon  is  inserted. 


Fig.  178. — The  Left  Internal  Cuneiform.     (External  surface,  i 


FOR  SECOND   METATARSAL 


FOR  MIDDLE  CUNEIFORM 


FOR  SCAPHOID 


The  external  surface  is  concave  and  rough,  except  along  the  posterior  and  supe- 
rior borders.  Near  the  anterior  extremity  of  the  superior  border  there  exists  a 
distinct  circular  facet  for  the  inner  side  of  the  base  of  the  second  metatarsal.  In 
front  of  the  facet  a  few  fibres  of  the  first  dorsal  interosseous  muscle  arise.  The 
remaining  sinuous  articular  facet  is  for  the  inner  surface  of  the  middle  cuneiform. 


168 


THE  SKELETON 


Articulations.— A\'ith  the  scaphoid,  middle  cuneiform,  and  the  first  and  second 

nu'tutarsals.  i  ^    .  j        ^ 

Muscles.— Til.ialis  amicus  and  posticus,  the  peroneus  longus,  and  hrst  dorsal 

intero.s^i'ous.  .      ,  r  xi     xu-  j 

Ossification.— A  single  nucleus,  which  appears  m  the  course  of  the  third  year 
The  MIDDLE  CUNEIFORM,  the  smallest  of  the  throe,  has  its  base  directed 

up\Yards  and  tlie  sharp  border  dowmvards.     The  posterior   concave  surface  is 

Fig.  179.— The  Left  Middle  Cuneiform.     (Internal  .surface.) 

FOR  :NTERNAL  cuneiform 
FOR  SECOND  METATARSAL 


articular  for  t"he  middle  facet  of  the  scaphoid.  The  anterior,  somewhat  narrower 
than  the  ])osterior  surface,  articulates  with  the  hase  of  the  second  metatarsal.  The 
internal  surface  has  a  facet  extending  along  its  upper  and  posterior  ])orders  for  the 


Fig.   Ij-^O. — The  Left  Middle  Cukeifoem.     (External  surface.) 


OCCASIONAL  FACET  FOR  EXTERNAL  CUNEIFORM 


FOR  EXTERNAL  CUNEIFORM 
FOR  SCAPHOID 


internal  cuneiform.  The  external  surface  has  a  facet  along  the  posterior  border, 
and  occasionally  one  at  the  anterior  inferior  angle  for  the  external  cuneiform. 

Articulations. — ^^'ith  the  internal  and  external  cuneiform  bones,  the  scaphoid 
and  thf  second  metatarsal. 

Ossification. — A  single  nucleus  appears  in  the  fourth  year. 

Tlie  EXTERNAL  CUNEIFORM  has  its  base  directed  upwards,  and  its  narrow 
border  downwards.  The  posterior  surface  is  faceted  for  the  scaphoid;  and  the 
anterior,  triangular  in  shape    articulates  with  the  base  of  the  third  metatarsal. 


Fig.  181.— The  Left  External  Cuneiform.     (Internal  surface.) 

i 


FOR  MIDDLE  CUNEIFORM 


FOR  SCAPHOID 


(p;-'-;-    •  /!  ^   FOR  SECOND  METATARSAL.     THE 

;-   %;*■-  .■■    1  THE   INFERIOR  ANGLE   IS   FOR 


CIRCULAR  FACET  AT 
THE   MIDDLE   CUNEI- 


'^' 


The  internal  surface  has  a  large  facet,  extending  along  the  posterior  border,  for 
the  middle  cuneiform;  and  on  the  anterior  border,  a  narrow  irregular  facet  for  the 
outer  border  of  the  base  of  the  second  metatarsal;  and  occasionally  a  small  facet 
at  the  anterior  inferior  angle  for  the  middle  cuneiform.  The  outer  surface  has  a 
l)roa(l  distinctive  facet,  near  its  ])osterior  superior  angle,  for  the  cuboid;  and  at  the 
anterior  superior  angle  there  is  usually  a  facet  for  the  inner  side  of  the  base  of  the 
fourth  metatarsal. 


THE  METATARSUS 


169 


Articulations. — \\\\\\  the  middle  cuneiform,  the  scaphoid,  the  (■ul)oid,  and  tlie 
sei'ond,  third,  and  fourth  metatarsals. 

Muscles. — The  flexor  brevis  hallucis  and  a  slip  from  the  tibialis  posticus. 
Ossification. — A  single  nucleus  appears  in  the  course  of  the  first  year. 


Fig.  182. — Thk  Left  External  Cuneiform.     (E.xternal  surface.) 


FOR  FOURTH  METATARSAL 
FOR  THIRD  METATARSAL 


The  three  cuneiform  bones  rest  posteriorly  against  the  scaphoid;  and  as  iliey 
are  of  unequal  length,  the  middle  being  the  smallest,  it  follows  that  when  the  bones 
are  placed  in  their  natural  positions  a  deep  gap  or  recess  is  formed  in  front.  Into 
this  recess  the  base  of  the  second  metatarsal  is  received,  thus  explaining  the  small 
facets  at  the  anterior  superior  angles  of  the  internal  and  external  cuneiforms. 


THE  METATARSUS 

The  metatarsus  consists  of  five  Ixjnes,  numbered  one  to  five,  beginning  at  the 
hallux.  Each  metatarsal  presents  a  proximal  portion  termed  the  base,  anda  distal 
end  or  head.  The  shaft  of  each  bone,  vriih  the  exception  of  the  first,  is  prismatic; 
the  base  of  the  prism  is  directed  upwards,  and  the  narrow  edge  downwards.  The 
shaft  tapers  gradually  from  the  base  to  the  head  and  is  slightly  bowed,  the  con- 
cavity being  on  the  plantar  aspect. 


Fig.  1^:5. — The  First  (Left)  Metatarsal. 


TIBIAL 

OR 

INNER   SIDE 


FIBULAR 

OR 

CUTER   SIDE 


FOR  PERONEUS  LONGUS 
FACET    FOR   SECOND  META- 
TARSAL (OCCASIONAL) 


The  base  is  prismatic:  its  terminal  surface  is  faceted  for  articulation  Avith  the 
tarsus,  and  the  adjacent  borders  of  the  base  present  small  facets,  in  most  cases  for 
adjacent  metatarsals. 

The  head  is  semicircular,  forming  a  convex  articular  surface  for  the  base  of  the 
first  phalanx.  The  compressed  sides  of  the  head  present  near  their  centres  a 
depression  surmounted  by  a  prominent  tubercle.     The  plantar  surface  is  deeply 


170 


Till-:  SKKLF/mS' 


groovi'd  for  the  paj^sage  of  flexor  tendons.  To  the  sides  of  the  head  the  lateral 
li.uaments  of  tlie  nietatarso-plialanueal  joints  are  attached. 

Tlie  FIRST  METATARSAL  is  tlie  niost  modified:  it  is  shorter,  but  much  thicker 
than  its  fellows.  The  base  ])resents  a  reniform,  slightly  concave  facet  for  the 
internal  cuneiform  l)one.  On  the  outer  (fibular)  side  of  the  base,  near  its  lower 
angle,  there  is  a  tubercle  into  which  tlie  peroncus  longus  is  inserted.  A  little  above 
this,  there  is  frequently  a  shallow  l)ut  easily  recognised  facet  where  it  comes  into 
contact  with  the  base  of  the  second  metatarsal. 

The  head  of  the  l>one  has  two  deep  grooves  on  the  plantar  surface  for  the 
sesaninids  developed  in  thv  fir. mr  hrrris  hallnris  muscle. 

Muscles. — Peroneus  longus;  til»ialis  anticus;  first  dorsal  interosseous. 

Blood-supply. — Tlie  nutrient  vessel  enters  the  shaft  on  the  fibular  side,  and  is 
directed  towards  the  head  of  tlie  bone. 

The  SECOND  METATARSAL  is  the  longest  of  the  series.  Its  base  is  prolonged 
backwards  to  occupy  the  space  between  the  internal  and  external  cuneiform  bones; 
this  leads  to  the  formation  of  a  small  facet  at  the  superior  angle  on  the  tibial  side 


Fig.  184. —The  Second  (Left")  Metatarsal. 


TIBIAL 

OR 

INNER   SIDE 


AN   OCCAS  ONAL  FACET  FOR  THE  FIRST 
METATARSAL 

■NTERNAL  CUNEIFORM 


FIBULAR 

OR 

OUTER   SIDE 


FACETS  FOR  THIRD  METATARSAL 
FACETS  FOR   EXTERNAL  CUNEIFORM 


where  it  articulates  with  the  internal  cuneiform.  It  oecasionallv  presents  a  small 
facet  for  the  first  metatarsal.  The  outer  (fibular)  side  of  the  Imse  has  two  facets, 
each  subdivided  in  well-marked  bones.  The  dorsal  facet  is  long  and  narrow;  the 
jiosterior  section  articulates  with  tlie  external  cuneiform;  the  anterior  is  for  the 
third  metatarsal.  The  lower  facet  is  somewhat  circular:  its  posterior  section  is  for 
the  external  cuneiform,  the  anterior  for  the  third  mct.-itarsal.  The  terniinal  facet 
on  the  base  is  for  the  middle  cuneiform:  thus  the  second  metatarsal  articulates 
\vith  three  cuneiform  bones. 

Muscles. — A.hhictor  liallucis;  first  and  second  dorsal  interosseous. 

Blood-supply.— The  nutrient  artery. enters  on  the  fibular  side  near  the  middle 
of  the  slialt,  and  is  directed  towards  the  base  of  the  bone. 

The  THIRD  METATARSAL  articulates  by  its  base  with  the  external  cuneiform. 
It  has  on  the  mner  (til.ial)  side  two  facets:  one  below  the  other  for  the  second 
metatarsal,  and  a  large  fac(4  (»n  the  fil)ular  side  for  the  fourth  metatarsal. 

Muscles.— Adductor  hallucis;  first  plantar;  second  and  third  dorsal  inter- 
osseous. 


THE  METATARSUS 


171 


Blood-supply. — The  nutrient  artery  enters  on  the  inner  (tiljial)  side  of  the 
shaft  near  its  middle:  it  is  directed  towards  the  base. 

The  FOURTH  METATARSAL  has  a  somewhat  quadrilateral  terminal  facet  for 
the  cuboid  bone.  On  its  inner  (tibial)  side  it  has  a  large  facet  for  the  third 
metatarsal:  the  posterior  part  of  this  is  occa.'^ionally  marked  off  for  the  external 


Fig.  185.— The  Third  (Left)  Metatarsal. 


FACETS  FOR  SECOND  METATARSAL 


TIBIAL 

OR 

INNER  SIDE 


FACETS  FOR  SECOND   METATARSAL^    ~l[ 


FIBULAR 

OR 

OUTER    SIDE 


FACET  FOR  FOURTH   METATARSAL 


Fig.  186. — The  Fourth  (Left)  Metatarsal. 


FACET  FOR  THIRD  METATARSAL 


TIBIAL  .^ 

OR  > 

INNER   SIDE 


FACET   FOR  THIRD  METATARSAL 
FACET  FOR  EXTERNAL  CUNEIFORM 


FIBULAR 

OR 

OUTER    SIDE 


FACET  FOR  FIFTH  METATARSAL 


cuneiform,  l)ut  this  is  far  from  constant.  A\'henthis  cuneiform  facet  is  present,  the 
facet  extends  to  the  base  of  the  bone.  When  absent,  the  surface  is  rough  for 
ligaments.     The  outer  (fibular)  side  has  a  single  facet  for  the  fifth  metatarsal. 

Muscles. — Adductor  hallucis;   second  plantar  interosseous;  third  and  fourth 
dorsal  interosseous. 


172 


THE  SKEJ.KTOX 


Blood-supply.— The  nutrient  artery  of  the  shaft  enters  on  the  inner  (tibial) 
side  and  runs  towards  tlie  base. 

The  FIFTH  METATARSAL  has  on  the  iibular  side  of  its  base  a  large  ni})ple- 
shaped  tuberosity,  to  wliieh  the  tendon  of  the  pewneuj^  brevu  is  inserted.  Its 
oblique  ti-rniinal  facet  articulates  with  the  cuboid,  and  on  the  tibial  side  it  has  a 
large  facet  for  the  fourth  metatarsal.  The  plantar  aspect  of  the  base  has  a  shallow 
groove  whicli  lodges  the  abductor  minimi  digiti. 

Muscles : — 


Tliird  plantar  interosseous. 
P'ourth  dorsal  interosseous. 
Poroneus  brevis. 


Peroneus  tertius. 

Abductor  ossis  metatarsi  quinti. 

Flexor  brevis  minimi  digiti. 


FxG.  187.— The  Fifth  (Left)  Metataksal. 


TIBIAL 
OR 
INNER  SIDE 


FOURTH  METATARSAL 


FIBULAR 

OR 

OUTER    SIDE 


Blood-supply. — Tlie  nutrient  artery  enters  on  the  tibial  side  of  the  shaft  and 
runs  towards  the  Ijase. 

Ossification. — Each  metatarsal  ossifies  from  two  centres.  The  j^riniary  nucleus 
for  the  diaphysis  appears  in  the  eighth  week  of  embryonic  life  in  the  middle  of  the 
cartilaginous  metatarsal.  At  birth,  each  extremity  is  represented  by  cartilage,  and 
that  at  the  ])roximal  end  is  ossified  by  extension  from  the  primary  nucleus,  except 
in  the  case  of  the  first  metatarsal.     For  this,  a  nucleus  appears  in  the  third  year. 

The  distal  ends  of  the  four  outer  metatarsals  are  ossified  by  secondary  nuclei 
which  make  tht-ir  appearance  about  the  third  year.  Very  frequently  an  epiphysis 
is  found  at  the  distal  end  of  the  first  metatarsal  as  well  as  at  its  base.  The  shafts 
and  epiphyses  consolidate  at  the  twentieth  year.  The  sesamoids  belonging  to  the 
flexor  brecia  hallucis  begin  to  ossify  about  the  fifth  year. 


THE  PHALANGES 

There  are  fourteen  phalanges  to  each  foot.  The  hallux  has  two,  and  the 
remaining  toes  three  each.  They  are  usually  distinguished  as  fir.st,  second,  and 
third.  The  la.st  are  sometimes  called  the  ungual  i)halanges,  because  they  su]i]wrt 
the  nail. 

The  i)halangesof  the  first  row  have  narrow  laterally  compressed  shafts,  rounded 
on  the  dorsal  and  concave  on  the  i»lantar  aspects.     The  base  of  each  has  a  deep 


THE  PHALAXGES 


173 


Fig.  188. — The  Phalanges  of  the  ^Middle  Toe. 


THIRD, 

TERMINAL   OR 

UNGUAL 

PHALANX 


SECOND 
PHALANX 


Fig.  189.— a  Longiti-dixal  Section  of  the  Boxes  of  the  Lower  Limb  at  Birth. 


THE  CENTRE  FOR  THE  LOWER  EXTREMITY  OF 
THE  FEMUR  APPEARS  EARLY  IN  THE  NINTH 
MONTH 

THE    CENTRE    FOR   THE    UPPER    END    Of    THE 
TIBIA  APPEARS  ABOUT  A  WEEK  BEFORE  BIRTH 


THE  CENTRE    FOR   THE   ASTRAGALUS  APPEA'.S    ^ 
IN  THE  SEVENTH   MONTH 


THE  CENTRE    FOR   THE    CALCANEUM    APPEARS 
!N  THE  SIXTH  MONTH 


CAflTIUGE  FOR  THE  PATELLA  APPEARS  ABOUT  THE  FOURTH 
MONTH  OF  INTRA-UTERINE  LIFE 


^E  CENTRE  FOR  THE  SCAPHOID  APPEARS  IN  THE  FOURTH  YEAR 
FOR  THE  INTERNAL  CUNEIFORM  APPEARS  IN  THE  THIRD  YEAR 


FIRST  PHALANX  OF  HALLUX 


SECOKD  PHALANX  OF  HALLUX 


174 


THE  SKELETOX 


glenoid  fo^sa  for  the  convex  head  of  tlie  coiTesi)onding  metatarsal,  whilst  the  head 
has  a  trochlear  surface  for  the  second  })halanx.  , 

The  phalancres  of  the  second  row  are  stunted,  msignificant  hones.  1  hen- 
shaft^  are  Hatter  than  those  of  the  lirst  row,  l)esides  heing  much  shorter.  The 
bases  have  two  depressions,  separated  by  a  vertical  ridge.  The  heads  present 
trochlear  surfaces  for  tlie  ungual  ]ihalanges.  .in.ii 

Thr  third,  terminal,  or  ungual  i)lialanges  are  easily  recognised.  Ihe  bases 
articulate  with  the  second  phalanges;  the  shafts  are  expanded  to  support  the  nails, 
and  their  plantar  surfaces  are  rough  where  they  come  into  relation  with  the  pulp 
of  the  digit. 

Fig.  190.— Thk  Secoxdary  Ossific  Centres  of  the  Foot. 

the  centre  for  the  epiphysis  for  the  calca- 
neum  appears  at  the  tenth  year;  consoli- 
dates at  the  sixteenth  year 


THE  CENTRE  FOR  THE  EPIPHYSIS  FOR  THE  META- 
TARSAL OF  THE  HALLUX  APPEARS  AT  THE  THIRD 
YEAR;   CONSOLIDATES  AT  THE  TWENTIETH  YEAR 


THE  CENTRES  FOR  THE  BASE  OF  THE  TERMINAL 
PHAUNGES  APPEAR  AT  SIXTH  YEAR;  AND  CON- 
SOLIDATE AT  THE  EIGHTEENTH  YEAR 


THE  CENTRES  FOR  THE  HEADS  OF  THE  METATARSALS 
APPEAR  AT  THE  THIRD  YEAR;   AND  CONSOLIDATE  AT  THE  TWENTIETH  YEAR 


The  first  phalanx  of  the  hallux  gives  insertion  to  the  following  muscles: — 
Flexor  brevis  hallucis;  abductor  ludlucis;  transversus  pedis;  adductor  hallucis; 
extensor  brevis  digitorum. 

The  first  phalanx  of  second  toe  :  The  first  and  second  dorsal  interosseous. 

The  first  phalanx  of  third  toe  :  Third  dorsal  interosseous;  first  plantar  inter- 
osseous. 

The  first  phalanx  of  fourth  toe  :  Second  ])lantar  interosseous;  fourth  dorsal 
interosseous. 

The  first  phalanx  of  fifth  toe  :  Third  ])lantar  interosseous;  flexor  Imwis 
minimi  tligiti;  and  abductor  minimi  digiti. 

The  second  phalanx  of  hallux:  F]<'X()r  longus  hallucis;  extensor  ])roprius 
hallucis. 

The  second  phalanges  of  the  remaining  toes:  Extensor  longus  digitorum; 
flexor  brevis  digitorum. 


THE  PHALANGES  17.', 

The  third  phalanges  :  Flexor  longus  digitorum;  extensor  longiis  digitorum. 

Ossification. — Like  the  phalanges  of  the  fingers,  those  of  the  toes  ossify  from  a 
primary  and  a  secondary  nucleus.  The  centres  for  the  shaft  appear  during  the 
eightli  and  tenth  ^yeeks  of  embryonic  life;  the  secondary  centres  ap])ear  as  thin 
scale-like  ei)i])hyses  at  the  proximal  ends  between  the  fourth  and  eighth  years. 
They  consolidate  earlier  than  the  corresponding  epiphyses  in  the  fingers. 

tlie  ungual  phalanges,  like  those  of  the  fingers,  ossify  from  the  tlistal 
extremity. 

The  ayerage  dates  of  ossification  of  the  l)oncs  of  the  foot: — 

Calcaneum Sixth  month. 

Epiphysis Tenth  year. 

Astragalus Seyenth  montli. 

Cuboid At,  or  near,  the  ninth  month. 

Scaphoid Fourth  or  fifth  year. 

Internal  cuneiform Third  year. 

Middle  cuneiform Fourth  year. 

External  cuneiform First  year. 

Metatarsals Eiglith  to  ninth  week. 

Epiphyses Third    year;     consolidate    at    the 

twentieth  year. 
Phalanges Eighth  to  tenth  week. 

Epiphyses Fourth  to  eighth  year;  consolidate 

about  the  eighteenth  year. 


SECTION    II 

THE    ARTICULATIONS 

Bv  HENRY  MORRIS,  M.A.,  M.B.,  Lond.:  F.R.C.S.Eng. 

SENIOR    SrR(.KON    TO    AND    I,ATE    LECTURER    ON    SURGERY    (FORMERLY    LECTURER  ON   ANATOMY)    AT  THE   MIDDLESEX 

hospital;    MEMBER  OP  THE  COUNCIL  AND  OF  THE  COURT  OF   EXAMINERS  OF  THE   ROYAL  COLLEGE  OF 

SURGEONS,   ENGLAND;    EXAMINER    IN   SURGERY   IN    THE   UNIVERSITY   OF   LONDON 


THE  section  devoted  to  the  Articulations  or  Joints  deals  with  the  union  of  tlie 
various  and  dissimilar  parts  of  the  human  skeleton.  The  following  struc- 
tures enter  into  the  formation  of  joints. 

Bones  constitute  the  basis  of  most  joints.  The  articular  ends  are  expanded, 
and  are  composed  of  cancellous  tissue,  surrounded  by  a  dense  and  strong  shell  of 
compact  tissue.  This  shell  has  no  Haversian  canals  (the  vessels  of  the  cancellous 
tissue  turn  back  and  do  not  perforate  it),  or  large  lacunse,  and  no  canaliculi,  and 
is  thus  well  adapted  to  bear  pressure.  The  long  bones  articulate  by  their  ends, 
the  flat  by  their  edges,  and  the  short  at  various  parts  on  their  surfaces. 

Thi'  Cartilage  Avhich  covers  the  articular  ends  of  the  bones  is  called  articular, 
and  is  of  tin*  hyaline  variety.  It  is  firndy  implanted  on  the  bone  b}^  one  surface, 
while  the  otlier  is  smooth,  polished,  and  free,  thus  reducing  friction  to  a  mini- 
nuun,  while  its  slight  elasticity  tends  to  break  jars.  It  ends  abruptly  at  the  edge 
of  the  articulation,  and  is  thickest  over  the  areas  of  greatest  pressure. 

Another  form  of  cartilage,  the  white  fibrous,  is  also  found  in  joints: — 

(i)  As  interarticular  cartilage  in  diarthrodial  joints — viz.,  the  knee,  temporo- 
mandibular, sterno-clavicular,  radio-carpal,  and  occasionally  in  the  acromio- 
clavicular. It  is  interposed  between  the  ends  of  the  bones.  ]iartially  or  completely 
dividing  tlie  synovial  cavity  into  two.  It  serves  to  adjust  dissimilar  bony  surfaces, 
adding  to  the  security  of,  while  it  increases  the  extent  of  motion  at,  the  joint;  it 
also  acts  as  a  Iniffer  to  V)reak  shocks. 

(ii)  As  circumferential  or  marginal  fibro-cartilages,  which  serve  to  deepen  the 
sockets  for  the  reception  of  the  heads  of  bones — e.g.  the  glenoid  and  cotyloid 
litraments  of  the  shoulder  and  hip.  Another  form  of  marginal  plate  is  seen  in  the 
glenoid  ligaments  of  the  fingers  and  toes,  Avliich  deepen  the  articulations  of  the 
phalanges  and  add  to  their  security. 

(iii)  As  connecting  fibro-cartilage.  The  more  pliant  and  clastic  is  the  more 
cellular  form,  and  is  found  in  the  intervertebral  discs;  while  the  less  yielding  and 
more  fibrous  form  is  seen  in  the  sacro-iliac  and  i)ubic  articulaticms,  where  there  is 
little  or  no  movement. 

The  Ligaments  which  bind  the  .bones  together  are  strong  bands  of  white 
fibrous  tissue,  t'oniiing  a  more  or  less  perfect  capsule,  round  the  articulation.  They 
are  ))liant  but  inextensile,  varying  in  shape,  strength,  and  thickness  according  to 
the  kind  of  articulation  into  which  they  enter.  They  are  closely  connected  with 
the  periosteum  of  the  bones  they  unite.  In  some  cases — as  the  ligamenta  subflava 
which  unite  jiarts  not  in  contact— they  are  formed  of  yellow  elastic  tissue. 

The  synovial  membrane  lines  the  interior  of  the  fibrous  ligaments,  thus  ex- 

176 


VARIOUS  ARTICULATIONS  177 

eluding  them,  as  vceW  as  the  eushions  or  pads  of  fatty  tissue  situate  -within  and  the 
tendons  which  perforate  the  fibrous  capsule,  from  the  articular  cavity.  It  is  a  thin 
delicate  membrane,  frequently  forming  folds  and  fringes  Avhich  project  into  the 
cavity  of  the  joint;  or,  as  in  the  knee,  stretches  across  the  cavity,  forming  a  so- 
called  synovial  ligament.  In  these  folds  are  often  found  pads  of  fatty  tissue,  which 
fill  up  interstices,  and  form  soft  cushions  between  the  contiguous  bones.  Some- 
times these  fringes  become  villous  and  pedunculated,  and  cause  pain  on  movement 
of  the  joints.  They  contain  fibro-fatty  tissue,  Avith  an  isolated  cartilage  cell  or  two. 
The  synovial  membrane  is  Avell  supplied  with  blood,  especially  near  the  margins  of 
the  articular  cartilages  and  in  the  fringes.  It  secretes  a  thick  glairy  fluid  like  Avhite 
of  egg,  called  synovia,  which  lubricates  the  joint.  Another  variety  of  s^movial 
membrane  is  seen  in  the  bursae,  which  are  interposed  l)etween  various  moving 
surfaces.  In  some  instances  bursse  in  the  neighbourhood  of  a  joint  may  communi- 
cate with  the  synovial  cavity  of  that  joint. 


THE  VARIOUS  KIXDS  OF  ARTICULATIONS 

There  are  three  chief  varieties  of  joints — viz.,  synarthrodial,  or  immovable; 
anqihiarthrodial.  or  yielding;  and  diarthrodial,  or  moval)le  joints. 

Synarthrosis  is  the  term  applied  to  all  immovable  joints  in  which  the  apposed 
surfaces  or  edges  of  the  bones  are  in  direct  contact,  as  in  the  face  bones^  except  the 
mandible,  and  all  those  of  the  skull;  or  where  bone  and  cartilage  are  in  immediate 
union,  as  in  the  case  of  the  first  rib  and  the  sternum,  and  the  costal  cartilages  and 
the  ribs.  The  unions  of  the  bones  of  the  skull  and  face  are  usually  called  sutures, 
of  which  there  are  three  chief  varieties  — 

(1)  True  sutures,  where  the  edges  of  bones  are  firmly  implanted  into  one 
another  by  means  of  projecting  processes,  as  in  the  sagittal,  lambdoid,  and  coronal 
sutures. 

(2)  False  sutures,  Avhere  the  rough  edges  of  the  bones  are  in  simple  contact 
without  interlocking,  as  in  the  intermaxillary  suture;  or  where  they  overlap  one 
another,  as  in  the  squamous  suture. 

(3)  Grooved  sutures,  where  the  edge  or  plate  of  one  bone  is  received  into  a 
corresponding  groove  in  the  other,  as  in  the  rostrum  of  the  si:)henoid  and  vomer,  or 
vomer  and  palatine  processes  of  the  maxilla-,  and  the  horizontal  plates  of  the  palate 
bones. 

Amphiarthrosis  is  the  term  applied  to  mixed  joints  which  permit  of  slight 
movements,  the  opposed  bony  surfaces  being  firmly  united  by  a  plate  or  disc  of 
fibro-cartilage.  There  is  sometimes  a  partial  synovial  membrane.  Examples  are 
seen  in  the  spine,  sacro-iliac,  and  pubic  joints. 

Diarthrosis  is  the  term  applied  to  all  movable  joints  in  which  the  bones  have 
smooth  cartilage-covered  surfaces,  lubricated  by  synovia,  and  bound  together  by 
more  or  less  perfect  capsules.  This  class  is  subdivided  into  the  following 
varieties : — 

1.  Enarthrosis,  or  ball-and-socket  joint,  where  the  more  or  Icv^s  spherical  head 
of  one  bone  is  adjusted  to  a  socket  on  the  other,  as  in  the  hip-  and  shoulder-joints. 
They  are  the  most  movable  of  all  articulations,  combining  angular  movements  in 
all  directions  with  axial  rotation. 

2.  Condylarthrosis,  or  an  articulation  having  on  one  bone  an  elongated  surface 
called  "  condyle  "  and  on  the  other  a  glenoid  surface.  They  permit  all  the  move- 
ments of  a  ball-and-socket  joint  except  axial  rotation. 

3.  Ginglymus,  trochlearthrosis,  or  hinge-joint,  where  there  is  a  pulley  or  troch- 
lea on  one  bone  and  a  surface  adapted  for  moving  round  it  on  the  other.  The 
movement  is  principally  in  two  directions,  namely,  flexion  and  extension,  though 
some   slight  amount   of   lateral  movement   is  also  permitted.     The  most   perfect 

12 


178  THE  ARTICILATIONS 

examples  of  this  form  of  joint  are  the  ellww  and  ankk'.  The  knee  is  a  miuh 
less  perfect  instance. 

4.  Trochoides,  or  wheel-like  joints,  where  one  bone  rotates  upon  another.  This 
name  is  given  to  an  articulation  in  which  either  a  pivot  revolves  in  a  ring,  as  in  the 
sui)erior  radio-ulnar;  or  the  ring  revolves  about  a  pivot,  as  in  the  atlanto-odontoid, 
and  in  a  nuich  less  i)erfect  form  in  the  inferior  radio-ulnar  joint.  Rotation  is  the 
only  movement. 

o.  Arthrodia,  a  more  or  less  simple  gliding  joint  formed  l)y  the  apposition  of 
two  plane,  or  nearly  ])lane,  or  concavo-convex  surfaces.  The  amount  of  movement 
is  very  varial)le  in  the  different  joints.  Whilst  in  some,  as  the  intermetacarpal,  it 
is  so  slight  that  the  joints  have,  by  some  writers,  !)een  descril)ed  as  amphiarthrosis, 
others  are  capal:)le  of  all  the  movements  of  a  Imll-and-socket  joint  except  rotation. 

The  articular  processes  of  the  vertebrae  and  the  carpal  and  tarsal  joints  are  good 
examples  of  the  ordinary  arthrodia,  but  under  this  head  are  also  included  the 
' '  saddle-shaped ' '  articulations,  such  as  the  sterno-costo-clavicUlar  and  the  carpo- 
metacarpal of  the  thuml:),  which  permit  the  four  angular  movements  and  circum- 
duction, l)ut  not  rotation. 

Table  of  the  Various  Classes  of  Joints 

Class.  Examples. 

I.   Synarthrosis 

(a)  True  sutures Lambcloid,  sagittal,  coronal. 

(J))   False  suturt'S Internasal.     Intermaxillary.    Costo-chon- 

dral. 
(c)    Grooved  sutui'es Vomer  and  rostrum  of  sphenoid. 

II.   Amphiarthrosis Bodies  of   vertebrae.     Symphysis   pubis, 

sacro-iliac,  sacro-coccygeal. 
III.   Diarthrosis 

(.a)  Enarthrosis Shoulder.     Hip.     Astragalo-scaphoid. 

(ft)   Condylartln-osis Temijoro-mandibular.     Occipito-atlantal. 

Radio-carpal.       Metacarpo-phalangeal. 
Metatarso-phalangeal. 
(c)    Ginglynuis  or  Trochlearthrosis  .  Elbow.     Ankle.     Knee.     Interphalangeal 

of  fingers  and  toes. 
{(1)  Troehoides   or   Lateral  Gingly- 

mus Atlanto-odontoid.     Superior  Radio-ulnar. 

Inferior  Radio-ulnar. 
(e)    Arthrodia: 

(1)  Simple Lateral  atlanto-axoidean.     The  joints  be- 

tween the  articular  processes  of  the 
vertebra3,  costo-transverse  and  inter- 
chondral.  Acromio-clavicular.  Carpal. 
Carpo-metacarpal  of  four  fingers.  Inter- 
metacarpal. Tarsal.  Tarso-metatarsal. 
Intermetatarsal.  Calcaneo-astragaloid. 
Superior  and  inferior  tibio- fibular. 

(2)  Saddle-shaped Sterno-costo-clavicular.       Carpo-metacar- 

I)al  of  thumb.     Calcaneo-cuboid. 


MOVEMEXTS  OF  JOINTS  179 


THE  VARIOUS  310 YEMENIS  OF  JOINTS 

The  movements  which  may  take  place  at  a  joint  are  either  gliding,  angular, 
rotatory,  or  circumductory. 

The  gliding  motion  is  the  simplest,  and  is  common  to  all  diarthrodial  joints:  it 
consists  of  a  simple  sliding  of  the  apposed  surfaces  of  the  Ijones  upon  one  another, 
without  angular  or  rotatory  motion.  It  is  the  only  kind  of  motion  permitted  in  the 
carpal  and  tarsal  joints,  and  in  those  between  the  articular  processes  of  the  vertel^ra?. 

The  angular  motion  is  more  elaborate,  and  increases  or  diminishes  the  angle 
between  diti'erent  parts.  There  are  four  varieties,  viz. :  flexion  and  extension,  which 
bend  or  straighten  the  various  joints,  and  take  place  in  a  forAvard  and  backward 
direction  (in  a  perfect  hinge-joint  this  is  the  only  motion  permitted);  and  adduction 
and  abduction,  which,  except  in  the  case  of  the  fingers  and  toes,  signifies  an  approach 
to,  or  deviation  from,  the  centre  line  of  the  boch'.  In  the  case  of  the  hand,  the  line 
to  or  from  which  adduction  and  abduction  are  made  is  drawn  through  the  middle 
finger,  while  in  the  foot  it  is  through  the  second  toe. 

Rotation  is  the  revolution  of  a  bone  al^out  its  own  axis  without  much  change 
of  position.  It  is  only  seen  in  enarthrodial  and  trochoidal  joints.  The  knee  also 
permits  of  slight  rotation  in  certain  positions,  Avhich  is  a  distinctive  feature  of  this 
articulation. 

Circumduction  is  the  movement  compounded  of  the  four  angular  movements 
in  quick  succession,  by  which  the  moving  bone  describes  a  cone,  the  proximal  end 
of  the  l^one  forming  the  apex,  while  the  distal  end  describes  the  base  of  the  cone. 
It  is  seen  in  the  hip  and  shoulder,  as  well  as  in  the  carpo-metacarpal  joint  of  the 
thumb,  which  thus  approximates  to  the  ball-and-socket  joint. 

In  some  situations  where  a  variety  of  motion  is  required,  strength,  security,  and 
celerity  are  obtained  by  the  combination  of  two  or  more  joints,  each  allowing  a 
different  class  of  action,  as  in  the  case  of  the  Avrist,  the  ankle,  and  the  head  with 
the  spine.  Many  of  the  long  muscles,  which  pass  over  two  or  more  joints,  act  on 
all,  so  tending  to  co-ordinate  their  movements  and  enabling  them  to  be  produced 
with  the  least  expenditure  of  power.  Muscles  also  act  as  elastic  ligaments  to  the 
joints;  and  when  acting  as  such,  are  diff users  and  combiners,  not  })roducers  of 
movement;  the  short  muscles  producing  the  movement,  the  long  dift'using  it,  and 
thus  allowing  the  short  muscles  to  act  on  more  than  one  joint. 

^Muscles  are  so  disposed  at  their  attachments  near  the  joints  as  never  to  strain 
the  ligaments  by  tending  to  pull  the  bones  apart,  but,  on  the  contrary,  they  add  to 
the  security  of  the  joint  by  bracing  the  bones  firmly  together  during  their  action. 

The  articulations  may  be  divided  for  convenience  of  description  into  those:  1. 
of  the  Skull;  2.  of  the  Trunk;  3.  of  the  Upper  Limb;  and  4.  of  the  Lower  Limb. 


1.  THE  ARTICULATIONS   OF  THE  SKULL 

The  articulations  of  the  skull  comprise  (1)  the  temporo-mandibular;  and  (2) 
those  between  the  skull  and  the  spinal  column,  namely  (a)  betAveen  the  occiput 
and  atlas;  (6)  betAveen  the  atlas  and  axis;  and  (c)  the  ligaments  Avhich  connect  the 
occiput  ancl  axis. 

The  union  of  the  atlas  and  axis  is  described  in  this  section  because,  firstly,  there 
is  often  a  direct  communication  betAveen  the  synovial  cavity  of  the  transverse 
axoidean  and  the  occipito-atlantal  joints;  secondly,  the  rotatory  movements  of  the 
head  take  place  around  the  odontoid  process;  and,  thirdly,  important  ligaments  from 
the  odontoid  process  pass  over  the  atlas  to  the  occiput. 


180  THE  ARTICULATIONS 

(1)  THE  TEMPORO-MANDIBULAR  ARTICULATION 

Class. — Diarthrosis.  Subdivision. — Condi/larthrosis. 

The  parts  entering  into  tlie  formation  of  this  joint  are: — the  anterior  i)ortion  of 
tlie  glenoid  fossa  and  glenoid  ridge  (eniinentia  articularis)  of  the  temporal  l)(>ne 
above,  and  the  eondyle  of  the  lower  jaw  below.  Both  are  covered  with  articular 
cartilage,  which  extends  over  the  front  of  the  glenoid  ridge  to  facilitate  the  play  of 
the  interarticular  cartilage.     The  ligaments  Avhich  unite  the  bones  are : — 

1.  Capsular.  3.  Spheno-mandibular. 

2.  Interarticular  filiro-cartilage.  4.   Stylo-mandibular. 

The  capsular  ligament  is  often  described  as  consisting  of  four  j^ortions,  which 
are,  however,  continuous  with  one  another  around  the  articulation. 

1.  The  anterior  portion  consists  of  a  few  stray  fibres  connected  with  the 
anterior  margin  of  the  tibro-cartilage,  and  attached  below  to  the  anterior  edge  of 
the  condyle,  and  alcove  to  the  front  of  the  glenoid  ridge.  Some  fibres  of  insertion 
of  the  external  pterygoid  pass  between  them  to  be  inserted  into  the  margin  of  the 
fibro-cartilage. 

2.  The  posterior  portion  is  attached  above,  just  in  front  of  the  Glaserian 
fissure,  and  is  inserted  into  the  Ijack  of  the  jaw  just  below  its  neck. 

3.  The  external  portion  or  external  lateral  ligament  (fig.  191)  is  the 
strongest  part  of  the  capsule.  It  is  broader  aljove,  where  it  is  attached  to  the 
lower  edge  of  the  zygoma  in  nearly  its  wdiole  length,  as  well  as  to  the  tubercle  at 
the  point  where  the  two  roots  of  the  zygoma  meet.  It  is  inclined  doAvnw'ards  and 
l)ackwards,  to  l)e  inserted  into  the  outer  side  of  the  neck  of  the  condyle.  Its  fibres 
diminish  in  obliquity  and  strength  from  before  backwards,  those  coming  from  the 
tubercle  being  short  and  nearly  vertical. 

4.  The  internal  portion  or  short  internal  lateral  ligament  (fig.  192)  consists 
of  well-defined  fibres,  having  a  broad  attachment,  above  to  the  outer  side  of  the  alar 
spine  of  the  sphenoid  and  inner  edge  of  the  glenoid  fossa;  and  below,  a  narrow 
insertion  to  the  inner  side  of  the  neck  of  the  condyle.  Fatty  and  cellular  tissue 
separate  it  from  the  spheno-mandibular  ligament  which  is  internal  to  it. 

The  interarticular  cartilage  (fig.  193)  is  an  oval  plate  interposed  between  and 
adapted  to  the  two  articular  surfaces.  It  is  thinner  at  the  centre  than  at  the 
circumference,  and  is  thicker  behind  where  it  covers  the  thin  bone  at  the  bottom 
of  the  glenoid  fossa  wdiich  separates  it  from  the  dura  mater,  than  in  front  where  it 
covers  the  glenoid  ridge.  Its  inferior  surface  is  concave  and  fits  on  to  the  condyle 
of  the  lower  jaw;  while  its  superior  surface  is  concavo-convex  from  before  back- 
wards, and  is  in  contact  with  the  articular  surface  of  the  temporal  bone.  It 
divides  the  joint  into  two  separate  synovial  cavities,  but  is  occasionally  perforated  in 
the  centre,  and  thus  allows  tliem  to  communicate.  It  is  connected  with  the  cap- 
sular ligament  at  its  circumference,  and  has  some  fibres  of  the  external  pterygoid 
muscle  inserted  into  its  antericir  margin. 

There  are  usually  two  synovial  membranes  (fig.  193),  the  superior  being  the 
larger  and  looser,  i)assing  down  from  the  margin  of  the  articular  surface  above,  to 
the  upper  surface  of  the  interarticular  cartilage  below;  the  lower  and  smaller  one 
passes  from  the  interarticular  cartilage  above  to  the  eondyle  of  the  jaAV  below, 
extending  somewhat  further  down  behind  than  in  front.  When  the  interarticular 
cartilage  is  perforated,  the  two  sacs  communicate. 

The  spheno-mandibular  ligament  (long  internal  lateral)  (fig.  192)  is  a  thin, 
loose  band,  situated  some  little  distance  from  the  joint.  It  is  attached  above  to 
the  alar  spine  of  tlie  s])henoid  and  contiguous  part  of  the  temporal  l)one,  and  is 
inserted  into  the  mandil)ular  spine  of  the  lower  jaw.  It  covers  the  upper  end  of 
the  mylo-hyoid  groove,  and  is  here  ])ierced  l)y  the  viylo-hyoid  nerve.  Its  origin  is 
a  little  internal  to,  and  immediately  behind,  the  origin  of  the  short  internal  lateral 
ligament.  It  is  separated  from  the  joint  and  ramus  of  the  jaw  by  the  external 
pterygoid  muscle,    intcnud  maxillary  artery  and  vein,   the  mandihular  nerve   and 


TEMPOR  0-MANDIB I  lA  R 


181 


artery,  and  the  middle  meningeal  artery.     It  is  really  the  fil)r()us  remnant  of  a  part 
of  the  mandiV)iilar  (Meckelian)  bar. 

The  stylo-mandibular  ligament  (stylo-maxillary)  (figs.  191  and  192)  is  a 
process  of  the  deep  cervical  fascia  extending  from  near  the  ti]i  of  the  styloid  process 
to  the  angle  and  posterior  border  of  the  ramus  oi  the  jaw,  between  the  masseter  and 

Fig.  191. — External  View  of  Tempoko-maxdibclar  Joint. 


jj External  portion 

of  capsule 


-  Stylo-mandibular  ligament 


Fig.  192. — Internal  View  of  Temporo-mandibular  Joint. 


Internal  portion 
of  capsule 


Spheno-mandibular 
ligament 


Stylo-mandi  bular 
ligament 


internal  pterygoid  muscles.  It  separates  the  parotid  from  the  submaxillary  gland, 
and  gives  origin  to  some  fil:)res  of  the  sti/lo-gloMus  muscle. 

The  arterial  supply  is  derived  from  the  temporal,  middle  meningeal,  and 
ascending  ])haryngeal  l)y  its  branches  to  the  Eustachian  tube. 

The  nerves  are  derived  from  the  masseteric  and  auriculo-temporal. 


l.'^2 


THE   A  n  Tin  7.  A  TIOXS 


Movements.— The  chief  movement  of  this  joint  is  of  (i)  a  ginglymoid  or 
hinge  character,  aceomi»anie(l  h}-  a  slight  gliding  action,  as  in  opening  or  sliutting 
the  mouth.  In  the  opening  movement  the  condyle  turns  like  a  hinge  on  the  fibro- 
cartilage,  while  at  the  same  time  the  fibro-cartilage,  together  with  the  condyle, 
glides  forwards  so  as  to  rise  upon  the  eminentia  articularis;  the  fibro-cartilage 
reaching  as  far  as  the  anterior  edge  of  the  eminence,  which  is  coated  with  articular 
cartilage  to  receive  it ;  but  the  condyle  never  reaches  quite  so  far  as  the  summit  of 
the  eminence.  Should  the  condyle,  however,  by  excessive  movement  (as  in  a  con- 
vulsive yawn),  glide  over  the  summit,  it  shps  into  the  zygomatic  fossa,  the  mandil)le 
is  dislocated,  and  the  posterior  portion  of  the  capsule  is  torn.  In  the  shutting 
movement  the  condyle  revolves  back  again,  and  the  fibro-cartilage  glides  back, 
carrying  the  condyle  with  it.  This  combination  of  the  hinge  and  gliding  motions 
gives  a  tearing  as  well  as  a  cutting  action  to  the  incisor  teeth,  without  any  extra 
niuscular  exertion. 

There  is  (ii)  a  horizontal  gliding  action  in  an  antero-posterior  direction,  by 
which  the  lower  teeth  are  thrust  forwards  and  drawn  back  again:  this  takes  place 


Fig. 


193. — Veetical  Section  through  the  Condyle  of  Jaw  to  show  the  Two 
Synovial  Sacs  and  the  Interaeticular  Fibko-caetilage. 


Interarticular  flbro-_4 ^ 

cartilage  ^     ■? 

SECTION  THROUGH  CONDYLE >      ;,_^    ■  !V   i 

Posterior  portion  of  tt',/'^'^      L/ 

capsule 


Spheno-mandibular  ligament 


Stylo-mandibular  ligament 


almost  entirely  in  the  upper  compartment,  because  of  the  closer  connection  of  the 
libro-cartilage  with  the  condyle  than  with  the  squamosal  bone,  and  also  because  of 
the  insertion  of  tlie  crtenutl  jderygoid  into  both  bone  and  cartilage.  In  these  two 
sets  of  movements  the  joints  of  both  sides  are  simultaneously  and  similarlv  engaged. 
The  third  form  of  movement  is  called  (iii)  the  oblique  rotatory,  and*  is  that  by 
Avhich  the  grinding  and  chewing  actions  are  performed.  It  consists  in  a  rotation  of 
the  condyle  about  the  vertical  axis  of  its  neck  in  the  lower  compai-tment,  while  the 
cartilage  glides  ol)li(iuely  forwards  and  inwards  on  one  side,  and  backwards  and 
inwards  on  the  other,  u])on  the  articular  surface  of  the  squamosal  bones,  each  side 
acting  alternately.  If  the  symphysis  be  simply  moved  from  the  centre  to  one 
side  and  back  again,  and  not  from  side  tQ  side  as  in  grinding,  the  condyle  of  that  side 
moves  round  the  vertical  axis  of  its  neck,  and  the  opi)osite  condyle  and  cartilage 
glide  forwards  and  inwards  upon  the  glenoid  fossa.  But  in  the  ordinary  grinding 
movement,  one  condyle  advances  and  the  other  recedes,  and  then  the  first  recedes 
while  the  other  advances,  slight  rotation  taking  place  in  each  joint  meanwhile. 


ATLAS  WITH  OCCIPUT  183 


(2)  THE  LIGAMENTS  AND  JOINTS  BETWEEN  THE  SKULL  AND 
SPINAL  COLUMN,  AND  BET^^  EEN  TLIE  ATLAS  AND  AXIS 

(d)  The  Aeticulatiox  of  the  Atlas  avith  the  Occiput 
Class. — Diarthrosis.         Subdivision. — Doable  Condi/larthrosis. 

This  articulation  consists  of  a  pair  of  joints  synnnetrically  situated  on  either 
side  of  the  middle  line.  The  parts  entering  into  their  formation  are  the  cup-sliaped 
superior  articular  processes  of  the  atlas,  and  the  condyles  of  the  occipital  bone. 
They  are  united  Ijy  the  folloAving  ligaments: — 

1.  Anterior  occipito-atlantal.  3.   Two  capsular. 

2.  Posterior  occipito-atlantal.  4.   Two  anterior  oblique. 

Tlie  anterior  occipito-atlantal  ligament  (fig.  194)  is  less  than  an  inch  (about 
2  cm. )  wide,  and  is  composed  of  densely  woven  filjres,  most  of  which  radiate 
slightly  outwards  as  they  ascend  from  the  front  surface  and  upper  margin  of  the 
anterior  arch  of  the  atlas,  to  the  anterior  border  of  the  foramen  magnum;  it  is  con- 
tinuous laterally  with  the  capsular  ligaments,  the  fibres  of  which  overlap  its  edges, 
and  take  an  opposite  direction  inwards  and  upwards.  The  central  fibres  ascend 
vertically  from  the  anterior  tubercle  of  the  atlas  to  the  pharyngeal  tubercle  on  the 
occipital  bone;  they  are  thicker  than  the  lateral  fibres,  and  are  continuous  below 
with  the  superficial  part  of  the  anterior  atlanto-axoidean  ligament,  and  through  it 
with  the  anterior  common  ligament  of  the  vertel;)ral  column.  It  is  in  relation,  in 
front,  Avith  the  recti  capitis  antici  minores ;  and  behind,  Avith  the  central  odontoid  or 
suspensory  ligament. 

The  posterior  occipito-atlantal  ligament  (fig.  195)  is  broader,  more  mem- 
branous, and  not  so  strong  as  the  anterior.  It  extends  from  the  posterior  surface 
and  upper  border  of  the  posterior  arch  of  the  atlas  to  the  posterior  margin  of  the 
foramen  magnum  from  condyle  to  condyle;  being  incomplete  on  either  side  for  the 
passage  of  the  vertebral  artery  into,  and  suboccipital  nerve  out  of,  the  canal.  It  is 
somcAvhat  thickened  in  the  middle  line  by  fibres,  AA'hich  pass  from  the  posterior 
tubercle  of  the  atlas  to  the  lower  end  of  the  occipital  crest.  It  is  not  tightly 
stretched  betAveen  the  bones,  nor  does  it  limit  their  moA'ements;  it  corresponds  with 
the  position  of  the  ligamenta  subflava,  but  has  no  elastic  tissue  in  its  composition. 
It  is  in  relation  in  front  Avith  the  dura  mater,  Avhich  is  firmly  attached  to  it;  and 
behind  A\'ith  the  recti  capitis  pjostici  minores^  and  enters  into  the  floor  of  the  sub- 
occipital triangle. 

The  capsular  ligaments  (figs.  194  and  195)  are  very  distinct  and  strongly 
marked,  except  on  the  inner  side,  Avhere  they  are  thin  and  formed  only  of  short 
membranous  fibres.  They  are  lax,  and  do  not  add  much  to  the  security  of  the  joint. 
In  front,  the  capsule  descends  upon  the  atlas,  to  be  attached,  some  distance  below 
the  articular  margin,  to  the  front  surface  of  the  lateral  mass,  and  to  the  l)ase  of  the 
transverse  process;  these  fibres  take  an  oblique  course  upAvards  and  inwards,  OA'er- 
lapping  the  anterior  occipito-atlantal.  At  the  sides  and  behind,  the  capsule  is 
attached  above  to  the  margins  of  the  occipital  condyles;  beloAv,  it  skirts  the  inner 
edge  of  the  foramen  for  the  A^ertebral  artery,  and  behind  is  attached  to  the  promi- 
nent tubercle  OA^erhanging  the  groove  for  that  A^essel ;  these  latter  fibres  are  strength- 
ened by  a  band  running  obliquely  upAvards  and  iuAvards  to  the  posterior  margin  of 
the  foramen  magnum. 

The  anterior  oblique  or  lateral  occipito-atlantal  ligament  (fig.  194)  is  an 
accessory  band  Avliich  strengthens  tl)e  capsule  on  the  outer  side.  It  is  an  oblique, 
thick  band  of  fil^res,  sometimes  cpiite  separate  and  distinct  from  the  rest,  passing 
upAvards  and  iuAvards  from  the  upper  surface  of  the  transverse  process  bcA'ond  the 
costo-verteV)ral  foramen  to  the  jugular  process  of  tlie  occipital  bone. 

The  synovial  membrane  of  these  joints  occasionally  communicates  Avith  the 
synovial  sac  between  the  odontoid  process  and  the  transverse  ligament. 


184 


THE  A  R  TIC  I  'LA  TIOXS 


Thv  arterial  siipj.lv  is  dcrivi'd  from  twijis  of  the  vi'rtel)ral,  and  occasionally 
from  twiiis  Iroin  the  meningeal  hranches  of  tlie  ascending  i)haryngeal. 

Thr  nerve-supply  eonies  from  the  anterior  division  of  the  suboccipital  nerve. 

Movements.— Bv  the  symmetrical  and  bilateral  arrangement  of  these  joints, 
security  and  strength"  are  gained  at  the  exi)ense  of  a  very  small  amount  of  actual 
articular  surface;  the  basis  of  sui)i)ort  and  the  area  of  action  being  equal  to  the 
width  between  the  most  distant  l>orders  of  the  joint. 

The  jirincipal  movement  permitted  at  these  joints  is  of  a  ginglymoid  character, 
producing  flexion  and  extension  upon  a  transverse  axis  drawn  across  the  condyles 
at  their  slightlv  constricted  parts. 

In  flexion,"  the  forehead  and  chin  drop,  and  what  is  called  the  nodding  move- 
ment is  made;  in  extension,  the  chin  is  elevated  and  the  forehead  recedes. 


Fig.  194.— Axtekiok  View  of  thk  Upper  End  of  the  Spine. 


The  anterior  oblique 
or  lateral  oecipito- 
atlautal  ligament 

Atlanto-axoidean 
capsular  ligament 


Capsular  ligaments  ot 
articular  piocesses 
between  axis  and 
the  third,  the  third  < 
and  fourth,  and  the 
fourth  and  fifth  cer- 
vical vertebrae 


Continuation  of 
the  anterior 
common  liga- 
ment of  the 
vertebral 
column 

Anterior  oeeipi- 
to-atlantal 
ligament 


Anterior  atlanto- 
axoidean  ligament 


Short  vertebral 
ligament 


Anterior  common 
ligament 


There  is  also  a  slight  amount  of  gliding  niovcnicnt,  either  directly  lateral,  the 
outer  edge  of  one  condyle  sinking  a  little  within  the  outer  edge  of  the  socket  of  the 
atlas,  and  that  of  tlie  opposite  con<lyle  ]n'ojecting  to  a  corresponding  degree.  The 
head  is  thus  tilted  to  one  side,  and  it  is  even  i)ossil)le  that  the  Aveight  of  the  skull 
may  l^e  borne  almost  entirely  on  one  joint,  the  articular  surfaces  of  the  other  being 
thrown  out  of  ('(jntact. 

Or  the  movement  may  l)e  obliquely  lateral,  when  the  lower  side  of  the  head 
will  be  a  trifle  in  advance  ()f  the  elevated  side.  In  this  motion,  which  takes  place 
on  the  antero-])osterior  axis,  one  condyle  advances  slightly  and  approaches  the 
middle  line,  while  the  oth.T  recedes.  "This  is  of  the  nature  of  rotation,  though 
there  is  no  true  rotation  lound  a  vertical  axis  possible  between  the  occiput  and 
atlas. 

These  lateral  movements  are  checked  by  the  lateral  odontoid  ligaments  and  the 


BETWEEN  ATLAS  AND  AXIS  185 

outer  part  of  the  capsules;  extension  is  checked  by  the  anterior  occipito-atlantal 
and  anterior  oblique  ligaments,  and  flexion  by  the  posterior  part  of  the  capsule  and 
cervico-basilar  ligaments. 


(/>)  The  Articulations  between  the  Atlas  and  Axis 

1.  The  Lateral  Atlaxto-axoidean  Joints.       I  Class.— Diarthros Is      ^ 

(  Subdivision. — Arthroaio. 

2.  The  Central  Atlanto-axoidean  Joint,  or  f  Class. — Diarthrosis. 

The  Atlanto-odoxtoid.  |  Subdivision. — Trochoides. 

The  bones  that  enter  into  the  formation  of  the  lateral  joints  are  the  inferior 
articular  processes  of  the  atlas  and  the  superior  of  the  axis;  the  central  joint  is 
formed  by  the  odontoid  process  articulating  in  front  Avith  the  atlas,  and  behind  with 
the  transverse  ligament. 

The  ligaments  which  unite  the  axis  and  atlas  are: — 

1.  The  anterior  atlanto-axoidean.  3.   Two  capsular  (for  lateral  joints). 

2.  The  posterior  atlanto-axoidean.  4.   The  transverse  ligament. 

5.   The  atlanto-odontoid  capsular  ligament. 

The  anterior  atlanto-axoidean  ligament  (figs.  194  and  195)  is  a  narrow  but 
strong  menil^rane  filling  up  the  interval  Ijetween  the  lateral  joints.  It  is  attached, 
above  to  the  front  surface  and  lower  border  of  the  anterior  arch  of  the  atlas,  and 
below  to  the  transverse  ridge  on  the  front  of  the  body  of  the  axis.  Its  fibres  are 
vertical,  and  are  thickened  in  the  median  line  by  a  dense  band  which  is  a  con- 
tinuation upwards  of  the  anterior  common  ligament  of  the  spine. 

This  band  is  fixed  above  to  the  anterior  tubercle  of  the  atlas,  where  it  becomes 
continuous  with  the  central  part  of  the  anterior  occipito-atlantal  ligament  (fig. 
194);  it  is  sometimes  separated  by  an  interval  from  the  deeper  ligament,  and  is  often 
described  as  the  superficial  atlanto-axoidean  ligament.  It  is  in  relation  with  the 
longus  colli  muscle. 

The  posterior  atlanto-axoidean  ligament  (fig.  195)  is  a  deeper,  but  thinner 
and  looser  membrane  than  the  anterior.  It  extends  from  the  posterior  root  of  the 
transverse  process  of  one  side  to  that  of  the  other,  projecting  outwards  beyond  the 
posterior  part  of  the  capsules  which  are  connected  with  it.  It  is  attached  above  to 
the  posterior  surface  and  lower  edge  of  the  i)Osterior  arch  of  the  atlas,  and  below  to 
the  superior  edge  of  the  laminse  of  the  axis  on  their  dorsal  aspect.  It  is  denser  and 
stronger  in  the  median  line,  and  has  a  layer  of  elastic  tissue  on  its  anterior  surface 
like  the  ligamenta  suljflava,  to  which  it  corresponds  in  })Osition.  It  is  connected  in 
front  with  the  dura  mater;  behind,  it  is  in  relation  M'ith  the  inferior  oblique  muscles, 
and  is  perforated  at  each  side  by  the  second  cerviccd  nerve. 

1.  The  Lateral  Atlanto-axoidean  Joints  are  provided  with  short,  liga- 
mentous fibres,  forming  capsular  ligaments  (fig.  194),  which  completely  surround 
the  lateral  articular  facets.  Outside  the  canal,  they  are  attached  some  little  dis- 
tance from  the  articular  margins,  extending  along  the  roots  of  the  transverse  pro- 
cesses of  the  axis  nearly  as  far  as  the  tips,  but  between  the  roots  they  skirt  the 
inner  edge  of  the  costo-vertebral  foramina.  They  are  strengthened  in  front  and 
behind  by  the  atlanto-axoidean  ligaments.  Internally  each  capsule  is  thinner,  and 
attached  close  to  the  articular  margins,  being  strengthened  behind  by  a  stroDS  band 
of  slightly  ol:)lique  fibres  passing  upwards  along  the  outer  edge  of  the  cervico-basilar 
ligament  from  the  body  of  the  axis  to  the  lateral  mass  of  the  atlas  behind  the  trans- 
verse ligament;  some  of  these  fibres  pass  on,  thickening  and  blending  witli  the 
occipito-atlantal  capsule,  to  be  inserted  into  the  margin  of  the  foramen  magnum. 
This  band  is  sometimes  called  the  accessory  band  (fig.  198). 

There  is  a  synovial  sac  for  each  joint. 

2.  The  Central  Atlanto-axoidean  Joint,  although  usually  described  as  one, 
is  composed  of  two  articulations,  which  are  quite  separate  from  one  another:  an 
anterior  between  the  odontoid  ]irocess  and  the  arch  of  the  atlas,  and  a  j)Osteriov 
between  the  odontoid  })rocess  and  tlie  transverse  ligament. 


186 


THE  A  R  Tim  A  TIOXS 


Tlie  transverse  ligament  (lijrs.  195,  li)G,  and  108)  is  one  of  the  most  important 
structures  in  the  Ixxly,  for  on  its  integrity  and  that  of  the  check  hgaments  our  hves 
largely  depend.  It  is  a  thick  and  very  strong  hand,  as  dense  and  closely  woven  as 
tibro-cartilage,  al)Out  a  quarter  of  an  inch  (6  mm. )  deep  at  the  sides,  and  somewhat 
more  in  the  middle  line.  Attached  at  each  end  to  a  tubercle  on  the  inner  side  of 
the  lateral  mass  of  the  atlas,  it  crosses  the  ring  of  this  bone  in  a  curved  manner,  so 
as  to  have  the  concavity  forward;  thus  dividing  the  ring  into  a  smaller  anterior  por- 
tion for  the  odontoid  process,  and  a  larger  posterior  part  for  the  spinal  cord  and  its 
mem])ranes,  and  the  spinal  accessory  nerves.  It  is  flattened  from  before  backwards, 
l)eing  smooth  in  front,  and  covered  by  synovial  meml)rane  to  allow  it  to  glide  freely 
over  the  posterior  facet  of  the  odontoid  process.     Where  it  is  attached  to  the  atlas 


Fig.  195.— Vektical  Anteeo-postekior  Section  of  Spinal  Column  through  Median 

Line,  showing  Ligaments. 


Left  lateral 
odontoid 
ligament 


Aseendi 
portion 

crucial 
ligament 


Transverse  ligament 


Inner  part  of  capsular  ligament 
of  occipito-atlantal  joint 


Posterior  occipito-atlantal 
ligament 


Descending  portion  of  crucial 
ligament 

Posterior  atlanto-axoidean 
ligament 


Interspinous  ligament 


Ligaraentum  subflavum 


Central  odontoid 

ligament 
Anterior  occipito- 
atlantal  ligament 

Allan  to-odontoid 
synovial  sac 


Anterior  atlanto- 
axoideau  ligament 


it  is  smooth  and  well  rounded  off  to  provide  aneasvfloorof  communication  between 
the  transverso-odontoid  and  occiijito-atlantal  joints. 

To  its  i)osterior  sin-face  is  added,  in  the  middle  line,  a  strong  fasciculus  of 
vertical  fibres,  passing  upwards  from  the  root  of  the  odontoid  process  to  the  basilar 
border  ot  the  foramen  magnum  on  its  cranial  aspect.  Some  of  these  fibres  are 
derived  from  the  transverse  ligament.  These  vertical  fibres  give  the  transverse 
ligament  a  cruciform  appearance;  lience  the  name,  the  crucial  ligament  ffiss  195 
and  198)  applied  to  tlie  wliolc.  ^  ^    " 

The  atlanto-odontoid  capsular  ligament  (fig.  196)  is  a  tough,  loose  mem- 
brane, comi)letely  surrounding  tlie  apposed  articular  surfaces  of  the  atlas  and 
odontoid  process.     At  the  odontoid  process  it  blends  above  with  the  front  of  the 


BETWEEN  ATLAS  AND  AXIS 


18  < 


chock  and  central  occipito-odontoid  ligaments,  and  arises  also  along  the  sides  of  the 
articular  facet  as  far  as  the  neck  of  the  process;  the  fibres  are  thick,  and  blend  with 
the  capsules  of  the  lateral  joint.  At  the  atlas  they  are  attached  to  the  non-articular 
part  of  the  anterior  arch  in  front  of  the  tubercles  for  the  transverse  ligament,  blend- 
ing, aliove  and  l^elow  the  borders  of  the  bone,  with  the  anterior  occipito-atlantal 
and  atlanto-axoidean  ligaments,  as  well  as  with  the  inner  portion  of  the  capsular 
ligaments.  It  holds  the  axis  to  the  anterior  arch  of  the  atlas  after  all  the  other 
ligaments  have  been  divided. 

The  synovial  membranes  (figs.  195  and  196)  are  two  in  number: — one  for  the 
joint  between  the  odontoid  process  and  atlas;  and  another  (transverso-odontoid) 
for  that  between  the  transverse  ligament  and  the  odontoid.  This  last  often  com- 
municates with  the  occipito-atlantal  articulations;  it  is  closed  in  by  membranous 
tissue  between  the  borders  of  the  transverse  ligament  and  the  margin  of  the  facet  on 
the  odontoid,  and  is  separated  from  the  front  sac  by  the  atlanto-odontoid  capsular 
ligament. 

The  arterial  supply  is  from  the  vertebral  artery,  and  the  nerve-supply  from 
the  loop  between  the  first  and  second  cervical  nerves. 

Movements. — The  chief  and  characteristic  movement  at  these  joints  is  the 
rotation,  in  a  nearly  horizontal  plane,  of  the  collar  formed  by  the  atlas  and  trans- 


FiG.  196. — HoRizoxTAL  Sectiox  through  the  Lateral  Masses  of  the  Atlas  axd  the 

Top  of  the  Odoxtoid  Process. 


Atlanto-odontoid 
synovial  sac 


Transverso-odon- 
toid synovial  sae 


Atlanto-odontoid 
capsular  ligament 

Transverse 
ligament 

Posterior  common 
and    cervieo-basi- 
lar  ligaments 


Dura  mater 


verse  ligament,  round  the  odontoid  process  as  a  pivot,  which  is  extensive  enough 
to  allow  of  an  all-round  vicAV  without  twisting  the  trunk.  Partly  on  account  of 
its  ligamentous  attachments,  and  partly  on  account  of  the  shape  of  the  articular 
surfaces,  the  cranium  must  be  carried  with  the  atlas  in  these  movements.  The 
rotation  is  checked  by  the  ligaments  passing  from  the  axis  to  the  occiput  (check 
ligaments),  and  also  by  the  atlanto-axoidean.  Owing  to  the  fact  that  the  facets 
of  both  atlas  and  axis,  which  enter  into  the  formation  of  the  lateral  atlanto- 
axoidean  articulations,  are  convex  from  before  backwards,  and  have  the  articular 
cartilage  thicker  in  the  centre  than  at  the  circumference,  the  motion  is  not  quite 
horizontal  but  slightly  curvilinear.  In  the  erect  position,  with  the  face  looking 
directly  forwards,  the  most  convex  portions  of  the  ai*ticular  surfaces  are  alone  in 
contact,  there  being  a  considerable  interval  between  the  edges;  during  rotation, 
therefore,  the  prominent  portions  of  the  condyles  of  the  atlas  descend  upon  those 
of  the  axis,  diminishing  the  space  l^etween  the  bones,  slackening  the  ligaments, 
and  thus  increasing  the  amount  of  rotation,  without  sacrificing  the  security  of  the 
joint  in  the  central  position. 

Besides  rotation,  forward  and  backward  movements  and  some  lateral  flexion  are 
permitted  between  the  atlas  and  axis,  even  to  a  greater  extent  than  in  most  of  the 
other  verteViral  joints. 


188 


THE  ARTICULATIOXS 


(<•)  The  Li(;ami:xt.s   uniting  tup:  Occiput  and  Axis 

The  following  ligaments  unite  bones  not  in  contact,  and  are  to  be  seen  from  the 
intt'iior  of  the  canal  after  removing  the  posterior  arches  of  axis  and  atlas  and 
posterior  ring  of  the  foramen  magnum: — 


1.  The  occipito-cervical. 

2.  The  crucial. 


3.  Two  lateral  odontoid  or  check. 

4.  The  central  odontoid  or  suspensory, 


The  occipito-cervical  or  cervico-basilar  ligament  (figs.  196,  197,  and  198) 
consi.sts  of  a  vcrv  strong  l)and  of  lil)rcs.  connected  l)elow  to  the  upper  part  of  the 
hody  of  tlie  third  vertel^ra  and  lower  ])art  of  the  l)ody  of  the  axis  as  far  as  the  root 
of  the  odontoid  i)rocess.     It  is  narrow  below,  but  widens  out  as  it  ascends,  to  be 


Fig.  197.— Thk  Siperficiai,  Layer  of  the  Posterior  Common  Vertebral  Licjamext 

HAS   been   REMOVKI)  TO   SHOW   ITS   DEEP   OR   SHORT   FIBRES.      THESE  DEEP   FIBRES   FORM 

THE  Occipito-cervical  Ligament. 


Atlanto-asoid- 
eau  capsular 
ligament 


Occipito-cervi- 
cal ligament, 
i.e.,  the  deep 
stratum  of  the 
posterior  com- 
mon vertebral 
ligament 


Transverse  process  of  atlas 


fastened  to  the  basilar  groove  of  the  occiput.  Laterally,  it  is  connected  with  the 
accessory  fibres  of  the  atlanto-axoidean  capsule.  It  is  really  only  the  upward  pro- 
longation of  the  deep  stratum  of  the  posterior  common  ligament,  the  superficial 
fibres  of  which  run  on  to  the  occipital  bone  without  touching  the  axis,  thus  giving 
rise  t<»  two  strata.      It  is  in  relation  in  front  with  the  crucial  ligament. 

Till'  crucial  ligament  lias  l)een  already  described  (see  page  186). 

The  lateral  occipito-odontoid  or  check  ligaments  (figs.  195  and  198)  are 
two  strong  rounded  cords,  which  extend  from  the  sides  of  the  apex  of  the  odontoid 
])rocess,  transversely  outwards  to  the  inner  edge  of  the  anterior  portion  of  the 
occii)ital  condyles.  They  are  to  be  seen  immediately  above  the  upper  border  of  the 
transverse  ligament,  which  they  cross  oblicjuely  owing  to  its  forward  curve  at  its 
attachments  to  the  atlas.  Some  of  their  fibres  occasionally  run  across  the  middle 
line  from  one  check  ligament  to  the  other.  At  the  odontoid  ]>rocess  they  are 
connected  with  the  atlanto-odontoid  capsule,  and  at  the  condyles  they  strengthen 
the  occi])it()-atlantal  ca])sular  ligaments. 

The  central  odontoid  or  suspensory  ligament  (figs.  195  and  198)  consists  of 


LIGAMENTS  UXITIXG  OCCIPUT  AXD   AXIS 


189 


a  slender  l)an(l  oi  tiljres  ascending  from  the  siininiit  of  tlie  odontoid  process  to  the 
under  surface  of  the  occipital  bone,  close  to  the  foramen  magnum.  It  is  best  seen 
from  the  front,  after  remoWng  the  anterior  occipito-atlantal  ligament,  or  from 
behind  l\v  drawing  aside  the  crucial  ligament. 

The  suspensory  ligament  is  tightened  by  extension  and  relaxed  by  flexion  or 
nodding;  the  lateral  odontoids  not  only  limit  the  rotatory  movements  of  the  head 
and  atlas  upon  the  axis,  but  by  binding  the  occiput  to  the  pivot,  round  which 
rotation  occurs,  they  steady  the  head  and  prevent  its  undue  lateral  inclination  upon 
the  spine.      (See  Transverse  Ligament,  p.  186.) 

By  experiments,  it  has  been  proved  that  the  head,  when  placed  so  that  tlie 
orbits  look  a  little  upwards,  is  poised  upon  the  occipital  condyles  in  a  line  drawn  a 
little  in  front  of  their  middle;  the  amount  of  elevation  varies  slightly  in  different 
cases,' Init  the  balance  is  always  to  be  obtained  in  the  human  body — it  is  one  of  the 
characteristics  of  the  human  figure.  It  sers^es  to  maintain  the  head  erect  without 
undue  muscular  effort,  or  a  strong  ligamentum  nucha?  and  prominent  dorsal  spines 


Fig.  198. — Vertical  Tkaxsveese  Section  of  the  Spixal  Columx  and  the  Occipital 

BoxE  TO  SHOW  Ligaments. 

(Tlie  oervico-basilar  (1),  though  shown  as  a  distinct  stratum,  is  really  the  deeper  part  of 

the  posterior  common  ligament  (2).) 


Vertical  portion  of  crucial     ^. 

ligament 
Central  odontoid  ligament 

Lateral  odontoid  ligaments 

Transverse  portion  of 
crucial  ligament 
Accessory  band  of  atlanto 
azoidean  capsules 
Atlanto-axoidean  joint 


Oecipito-cervieal  or  eervieo-basilar 
ligament 


Posterior  common  ligament 


such  as  are  seen  in  the  lower  animals.  Disturb  this  balance,  and  let  the  muscles 
cease  to  act,  the  head  will  either  drop  forwards  or  backwards  according  as  the 
centre  of  the  gravity  is  in  front  or  behind  the  balance  line.  The  ligaments  Avhich 
pass  over  the  odontoid  process  to  the  occiput  are  not  quite  tight  when  the  head  is 
erect,  and  only  become  so  when  the  head  is  flexed;  if  this  were  not  so,  no  flexion 
would  be  allowed;  thus,  muscular  action,  and  not  ligamentous  tension,  is  employed 
to  steady  the  head  in  the  erect  position.  It  is  through  the  combination  of  the  joints 
of  the  atlas  and  axis,  and  occiput  and  atlas  (consisting  of  two  pairs  of  joints  placed 
svmmetrically  on  either  side  of  the  median  line,  while  through  the  median  line 
there  passes  a  pivot,  also  with  a  pair  of  joints)  that  the  head  enjoys  such  freedom 
and  celerity  of  action,  remarkable  strength,  and  almost  absolute  security  against 
violence,  which  could  only  be  obtained  by  a  ball-and-socket  joint;  but  the  ordinary 
ball-and-socket  joints  are  too  prone  to  dislocations  l)y  even  moderate  twists  to  Ijc 
reliable  enough  when  the  life  of  the  individual  depends  on  the  perfection  of  the 
articulation :  hence  the  importance  of  this  combination  of  joints. 


190  THE  ARricriATioys 

THE  ARTICULATIONS  OF  THE  TRUNK 

These  may  be  divided  into  the  following  sets: — 

1.  Those  of  the  vertebral  colunm. 

(a)  Union  of  the  bodies.  (h)  Union  of  the  articular  processes. 

2.  Vertebral  cohnnn  -with  the  pelvis. 

3.  Pelvis. 

(a)  Sacro-iliac  synchondroses.         (f)  Intercoccygeal. 
(6)  Sacro-coccygeal.  {d)  Symphysis  pubis. 

4.  Ribs  with  the  vertebral  column. 

5.  The  articulations  at  the  front  of  the  thorax. 

(a)  Costal  cartilages  with  the  sternum. 
(6)  Costal  cartilages  with  the  ribs. 

(c)  Sternal. 

(d)  Certain  costal  cartilages  with  each  other. 

1.  THE  ARTICULATIONS  OF  THE  VERTEBRAL  COLUMN 

There  are  two  distinct  sets  of  articulations  in  the  vertebral  column: — 

(a)  Those  between  the  bodies  and  intervertebral  discs  which  form  amphi- 

arthrodial  joints. 
(&)  Those  between  the  articular  processes  Avhich  form  arthrodial  joints. 

The  ligaments  which  unite  the  various  parts  may  also  be  divided  into  two  sets, 
viz. — immediate,  or  those  that  bind  together  parts  which  are  in  contact;  and 
intermediate,  or  those  that  l)ind  together  parts  which  are  not  in  contact. 

Immediate. 

(a)  Those  between  the  bodies  and  discs. 
(6)  Those  between  the  articular  processes. 

Intermediate. 

(c)  Those  between  the  lamina?. 

(d)  Those  between  the  spinous  processes. 

(e)  Those  between  tlie  transverse  processes. 

(r()  TiiK  Articulations  of  the  Bodies  of  the  Vertebrae 

Class. — AiiipJiidiiJirosis. 

The  ligaments  Avhich  unite  the  bodies  of  the  vertebra?  are: — 

Intervertebral  discs.  Anterior  connnon. 

Short  lateral  ligaments.  Posterior  common. 

The  intervertebral  substances  (figs.  195  and  199)  are  tough,  but  elastic  and 
compressible  discs  of  cumjjositc  structure,  which  serve  as  the  chief  bond  of  union 
between  the  vertebra?.  They  are  twenty-three  in  number,  and  are  interjiosed 
between  the  bodies  of  all  the  vertebne  from  the  axis  to  the  sacrum  (figs.  195  and 
20()).  Similar  sulxstances  are  found  between  the  segments  of  the  sacrum  and 
coccyx,  but  they  undergo  ossification  at  their  surfaces  and  often  throughout  their 
whole  extent. 


OF  VERTEBRAL   COLUMN 


191 


Each  disc  is  composed  of  two  portions — a  circumferential  laminar,  and  a 
central  pulpy  portion;  the  former  tightly  surrounds  and  braces  in  the  latter,  and 
forms  somewhat  more  than  half  the  disc.  The  laminar  portion  consists  of  alter- 
nating layers  of  fibrous  tissue  and  fibro-cartilage;  the  component  fibres  of  these  layers 

Fig.  199. — Horizontal  Section  through  an  Intervertebral  Disc  and  the 

corresponding  kibs. 


Anterior  costo-central 
or  stellate  ligament 


Costo-central  synovial 
aac 


Middle  costo-trans 
verse  ligament 


Laminar  poirtion  of  inter- 
vertebral disc 


Central  pulpy  portion  of  inter- 
vertebral disc 


Costo-transverse  synovial  aac 


Posterior  costo-transverse 
ligament 


Fig.  200.— The  Anterior  Common  Ligament  of  the  Spine,  the  Stellate,  the  Inter- 
articular,  and  the  superior  costo-transverse  ligaments. 


The  interartieular 
ligament 


The  superior  or  anterior 
costo-transverse  ligaments 


—  The  stellate  ligament 


are  firmly  connected  with  two  vertebrae,  those  of  one  passing  obliquely  down  and 
to  the  right,  those  of  the  next  down  and  to  the  left,  making  an  X-shaped  arrange- 
ment of  the  alternate  lavers.  A  few  of  the  superficial  lamellae  project  beyond  the 
edges  of  the  bodies,  their  fibres  being  connected  with  the  edges  of  the  anterior  and 


192 


THE  A  R  TICVLA  TfOXS 


lateral  surfaces;  and  some  do  not  ronipletely  surround  the  rest,  but  terminate  at 
the  intervertebral  foramina,  so  that  on  horizontal  section  the  circumferential  portion 
is  seen  to  be  thinner  posteriorly.  The  more  central  lamelUt'  are  incomplete,  less 
firm,  and  not  so  distinct  as  the  rest;  and  as  they  near  the  pulp  they  gradually 
assume  its  characters,  becoming  more  fibro-cartilaginous  and  less  fibrous,  and  have 
cartilage  cells  in  their  structure. 

The  central  portion  is  situated  somewhat  behind  the  centre  of  the  disc,  form- 
ing a  ball  of  very  elastic  and  tightly  compressed  material,  which  bulges  freely  when 
the  confining  pressure  of  the  laminar  portion  is  removed  by  either  horizontal  or 
vertical  section.  Thus,  it  has  a  constant  tendency  to  spring  out  of  its  confinement 
in  the  direction  of  least  resistance,  and  constitutes  a  pivot  round  which  the  bodies 
of  the  vertebrae  can  twist,  tilt,  or  incline.  It  is  yellowish  in  colour,  and  is  com- 
posed of  a  fine  fibrous  matrix  containing  cartilage  cells  and  fluid  in  its  meshes. 
Together  with  the  most  central  laminae,  it  is  separated  from  innnediate  contact 

Fig.  201. — Posterior  Common  Ligament  of  the  Spine.     (Thoracic  regiou.) 
(Pedicles  cut  through,  and  posterior  arches  of  vertebrse  removed.) 


Lateral  expanded  portion 


Median  longitudinal  band 


with  thf  bone  by  a  thin  plate  of  articular  cartilage.     The  central  pulp  of  the  inter- 
vertebral substance  is  the  persistent  part  of  the  notochord. 

The  interverte})ral  substances  vary  in  shape  with  the  bodies  of  the  vertebrae  thev 
unite,  and  are  widest  and  thickest  in  the  lum1)ar  region.  In  the  cervical  and 
luml)ar  regions  they  are  thicker  in  front  than  behind,  and  caa.^c  the  convexity  for- 
wards of  tlie  cervical,  and  increase  that  of  the  lumbar;  the  curve  in  the  thoracic 
region,  almost  entirely  due  to  the  shape  of  the  bodies,  is,  however,  somcAvhat 
increased  Ijy  the  discs.  Without  the  discs  the  column  loses  a  quarter  of  its  length, 
and  assumes  a  curve  with  the  concavity  forwards,  most  marked  a  little  below  the 
mid-thoracic  region.  8ucli  is  the  curve  of  old  age.  which  is  due  to  the  shrinking 
and  drying  up  of  tlie  intervertebral  substances.  The  disc  between  the  axis  and 
third  cervical  is  the  thinnest  of  all  (fig.  195);  that  between  the  fifth  lumbar  and 
sacrum  is  the  thickest,  and  is  much  thicker  in  front  than  beliind  (fig.  20G).  The 
intervertebral  discs  are  in  relation,  in  front  with  tlie  anterior  common  ligament; 


OF  VERTEBRAL   COLUMN 


103 


behind,  witli  tlie  posterior  eonnrion  ligament:  laterally,  with  the  short  lateral;   and 
in  the  thoracic  region  with  the  interartieular  and  stellate  ligaments. 

The  anterior  common  ligament  ( hgs.  194  and  200)  commences  as  a  narrow 
hand  attached  to  the  under  surface  of  the  occipital  bone  in  the  median  line,  just 
in  front  of  the  occipito-atlantal  ligament,  of  which  it  forms  the  thickened  central 
portion.  Attached  firmly  to  the  tubercle  of  the  atlas,  it  passes  down  as  the 
central  portion  of  the  atlanto-axoidean  ligament,  in  the  mid-line,  to  the  front  of 
the  body  of  the  axis.  It  no^v  begins  to  widen  out  as  it  descends,  until  it  is  nearly 
two  inches  (5  cm. )  wide  in  the  lumbar  region.  .  Below,  it  is  fixed  to  the  upper 
segment  of  the  sacrum,  becoming  lost  in  periosteum  about  the  middle  of  that 
))one;  but  is  again  distinguishable  in  front  of  the  sacro-coccygeal  joint,  as  the 
anterior  sacro-coccygeal  ligament.  Its  structure  is  bright,  pearly-white,  and 
glistening  with  Avell-defined  I»orders  l)est  marked  in  the  thoracic  region.  It  is 
thickest  in  the  thoracic  region,  and  thicker  in  the  lumbar  than  the  cervical.  It  is 
firmly  connected  with  the  bodies  of  the  verteln-ee.  and  is  composed  of  longitudinal 


Fig.  202. — Posterior  Commox  Ligament.     (Lumbar  region.) 


Median  band 

Expanded  lateral  portion 


fibres,  of  which  the  superficial  extend  over  several,  while  the  deeper  pass  over  only 
two  or  three  vertebra?.  It  is  ctumected  with  the  tendinous  expansion  of  the  prever- 
tebral muscles  in  the  cervical,  and  the  crura  of  the  diaphragm  are  closely  attached 
to  it  in  the  lumbar  region. 

The  posterior  common  ligament  (figs.  198,  201,  202.  and  209)  extends  from 
the  occi{)ital  bone  to  the  coccyx.  It  is  Avider  aljove  than  below,  and  commences  by 
a  l)road  attachment  to  the  cranial  surface  of  the  V)asi-occipital.  In  the  cervical 
region  it  is  of.  nearly  uniform  width,  and  extends  completely  across  the  l)odies  of 
the  vertebrae,  upon  which  it  rests  quite  flat.  It  does,  however,  extend  slightly 
further  outwards  on  each  side  opposite  the  intervertebral  discs.  In  the  thoracic  and 
luml)ar  regions  it  is  distinctly  dentated,  being  broader  over  the  intervertebral  suV)- 
stances  and  the  edges  of  the  bones,  than  over  the  middle  of  the  l>odies,  where  it  is 
a  narrow  band  stretched  over  the  bones  without  resting  on  them,  some  areolar 
tissue  and  blood-vessels  being  interposed.  The  narrow^  median  portion  consists  of 
longitudinal  fibres,  some  of  which  are  superficial  and  pass  over  several  vertebrae; 
13 


104  THE  ARTICULATIONS 

and  others  are  (le(>i)or,  and  extend  only  from  one  vertebra  to  tlie  next  Init  one 
l)elow. 

The  dentated  ox  In-oader  jiortions  (fig.  202)  are  formed  by  ol)hque  fibres  wliieh, 
sprini;in<r  from  the  bo(Hes  near  the  intervertebral  foramina,  take  a  curved  course 
downwards  and  liackwards  over  an  intervertebral  substance,  and  reach  the  narrow 
portion  of  the  li,<jcanicnt  on  the  centre  of  the  vertebra  next  below;  they  then  diverge 
to  i)ass  over  another  intervertebral  disc  to  end  on  the  body  of  the  vertebra  beyond, 
near  the  intervertebral  notch.  They  thus  pass  over  two  discs  and  three  vertebra\ 
Deeper  still  are  other  fibres  thickening  these  expansions  of  the  common  ligament. 
and  extending  from  one  bone  to  the  next. 

The  last  well-marked  expansion  is  situated  between  the  first  two  segments  of 
tlie  sacrum :  below  this,  the  ligament  becomes  a  delicate  central  band  with  rudi- 
mentarv  expansions,  being  more  pronounced  again  over  the  sacro-coccygeal  joint, 
and  losing  itself  in  the  ligamentous  tissue  at  the  back  of  the  coccyx.  The  dura 
mater  is  tightly  attached  to  it  at  the  occipital  bone  and  margin  of  the  foramen 
magnum,  but  is  separated  from  it  in  the  rest  of  its  extent  Ijy  loose  cellular  tissue. 
The  filum  terminale  becomes  blended  with  it  at  the  lower  part  of  the  sacrum  and 
l)ack  of  the  coccyx. 

The  lateral  or  short  vertebral  ligaments  (fig.  200)  consist  of  numerous  short 
fibres  situated  between  the  anterior  and  posterior  common  ligaments,  and  passing 
from  one. vertebra  over  the  intervertebral  disc,  to  which  it  is  firmly  adherent,  to 
the  next  vertebra  below.  The  more  superficial  fibres  are  more  or  less  vertical,  but 
the  deeper  decussate  and  have  a  crucial  arrangement.  They  are  connected  with  the 
deej^  surface  of  the  anterior  common  ligament,  and  so  tie  it  to  the  edges  of  the 
bodies  of  the  vertebra  and  to  the  intervertebral  discs.  They  blend  liehind  witli 
the  ex])ansions  of  the  posterior  common  ligament,  and  so  complete  the  casing  round 
each  ampliiarthrodial  joint.  In  the  thoracic  region,  they  overlie  the  stellate  liga- 
ment, and  in  the  lumbar  they  radiate  towards  the  transverse  processes.  In  the 
cervical  reoion  they  are  less  w'ell  marked. 


(6)  The  Lig.\ments  connecting  the  Articular  Processes 
Class, — D'larthrosis.     Subdivision. — A  rthrodia. 

The  capsular  ligaments  (fig.  194)  which  unite  these  processes  .are  composed 
]iartly  of  yellow  elastic  tissue,  and  partly  of  white  fibrous  tissue.  In  the  cervical 
region  only  the  inner  side  of  the  capsule  is  formed  by  the  ligamenta  suliflava, 
which  in  the  thoracic  and  lumbar  regions,  however,  extend  anteriorly  to  the 
margins  of  the  intervertebral  foramina.  The  part  formed  of  white  fibrous  tissue 
consists  of  short,  well-marked  fibres,  which  in  the  cervical  region  pass  o]:)liquely 
downwards  and  forwards  over  the  joint,  between  the  articidar  i»rocesses  ancl  the 
posterior  roots  of  the  transverse  processes  of  two  contiguous  vertebrge.  In  the 
thoracic  region  the  fibres  are  shorter,  and  vertical  in  direction,  and  are  attached  to 
the  l>ases  of  the  transverse  processes;  in  the  lumbar,  they  are  obliquely  transverse. 
The  capsular  ligaments  in  the  cervical  region  are  the  most  lax,  those  in  the  lumbar 
region  are  rather  tighter,  and  those  in  the  thoracic  region  are  the  tightest. 

There  is  one  synovial  membrane  to  each  capsule. 

(c)  The  Ligaments  uniting  the  Lamina's 

The  ligamenta  subflava  (fig.  203)  are  shallow  plates  of  closelv-woven  yellow 
elastic  tissue.  interi)osed  Ijetween  the  laminae  of  two  adjacent  vertei^rtv.  The  first 
connects  the  axis  with  the  third  cervical,  nnd  the  last  the  fifth  lumbar  Avith  the 
sacrum.  Each  ligament  extends  from  the  inner  and  ])osterior  edge  of  the  inter- 
vertebral foramen  on  one  side  to  a  corresponding  point  on  the  other;  above,  it  is 
attaehed  close  to  the  inner  margin  of  the  inferior  articular  })rocess  and  to  a  well- 
marked  ridge  on  the  inner  surface  of  the  lamina?  as  far  as  the  root  of  the  si)ine; 
below,  it  is  fixed  close  to  the  inner  margin  of  the  superior  articular  process  and  to 
the  dorsal  aspect  of  tlie  upper  edir,-  ,,f  the  laminae.     Thus  each,  besides  filling  ui> 


OF  VERTEBRAL  COLUMN 


195 


tho  interlaiiiiiiav  space,  enters  into  the  formation  of  two  capsular  ligaments;  they 
do  so  to  a  greater  extent  in  the  tlioracic  and  luml)ar  regions  than  in  the  cervical, 
where  the  articular  processes  are  placed  wider  apart.  When  seen  from  the  front 
after  removing  the  bodies  of  the  vertebrae,  they  are  concave  from  side  to  side,  but 
convex  from  above  downwards;  they  make  a  more  decided  transverse  curve  than 
the  arches  l)etween  which  they  are  placed.  This  concavity  is  more  marked  in  the 
thoracic,  and  still  more  in  the  lumbar  region  than  in  the  cervical;  in  the  lumbar 
region  the  ligamenta  suVjflava  extend  a  short  distance  between  the  roots  of  the 
spinous  pi'ocess,  blending  with  the  interspinous  ligament,  and  making  a  median 
sulcus  when  seen  from  the  front;  there  is,  however,  no  separation  betw'een  the  two 
parts.      In  the  cervical  region,  where  the  sjiines  are  bifid,  there  is  a  median  fissure 


Fig. 


203. — LiCtAmenta  Subflava  in  the  Lumbae  Eegion,  seen  from  withix  the 

Spinal  Canal. 


Portion  of  ligamen- 
tum  subflavum  re- 
moved to  show  the 
articular  cavity 


in  the  yellow  tissue  which  is  filled  up  by  filjro-areolar  tissue.  The  ligaments  are 
thickest  and  strongest  in  the  lumljar  region;  narrow  but  strong  in  the  thoracic; 
thinner,  broader,  and  more  membranous  in  the  cer^'ical  region. 


{(1)  The  Ligaments  connecting  the  Spinous  Processes  with  one  another 
Supraspinous  ligament,  interspinous  ligaments,  and  the  ligamentum  nucha?. 

The  supraspinous  ligament  (fig.  205)  extends,  without  interruption,  as  a 
well-marked  band  of  longitudinal  fibres  along  the  tips  of  the  S})ines  of  the  vertebrae 
from  that  of  the  seventh  cervical  downwards  till  it  lilends  witli  tlie  fibrous  tissue 
on  the  Ijack  of  the  coccyx.  It  covers  in  the  lower  end  of  the  spinal  canal,  and 
adds  to  the  security  of  the  sacro-coccygeal  articulation. 

Its  more  superficial  fibres  are  much  longer  than  the  deep.  The  deeper  fibres 
pass  over  adjacent  spines  only,  while  the  superficial  overlie  several.  It  is  con- 
nected laterally  with  the  aponeurotic  structures  of  the  back;  indeed,  in  the 
lumbar  region,  where  it  is  well  marked,  it  appears  to  result  from  the  interweaving 
of  the  tendinous  fibres  of  the  several  muscles  which  are  attached  to  the  tips  of 
the  spinous  processes. 


im 


THE  ARTIcrLATfOyS 


In  the  ilorsal  vedon  it  is  a  round  slendtT  ronl  which  is  put  on  the  stretoli  in 
flexion  and  n-hwni  in  extension  of  the  hack. 

The  ligamentum  nuchse,  or  the  posterior  cervical  ligament  ( liii.  204),  is  the 
continuation  in  the  neck  of  the  supraspinous  li.uanient,  from  which,  however,  it 
differs  considerably.  It  is  a  slender  vertical  septum  of  an  elongated  triangular 
form,  extending  from  the  seventh  cervical  vertebra  to  the  external  protuberance 
and  the  crest  of  the  occipital  bone.  Its  anterior  border  is  firmly  attached  to  the 
tijis  of  the  s|)ines  of  all  the  cervical  vertelirae,  including  the  posterior  tul)ercle  of  tbc 
atlas,  as  well  as  to  the  occiput.  Its  posterior  border  gives  origin  to  the  trapezii, 
with  the  tendinous  til  ires  c)f  which  muscles  it  blends.     Its  lateral,  triangular  sur- 


Fio.  204. — Side  View  ok  Ligamextum  Nuch.e. 


Ligamentum  nuchae 
First  interspinalis  muscle 


faces  afford  numerous  ]ioints  of  attachment  for  the  ]iosterior  muscles  of  the  head 
and  neck. 

In  man  it  is  rudimentary,  and  consists  of  elastic  and  white  fil)rous  tissues.  As 
seen  in  the  horse,  elephant,  ox,  and  other  mammiferous  quadrupeds,  it  is  a  great 
and  im])ortant  elastic  ligament,  wdiich  even  reaches  along  the  dorsal  part  of  the 
spinal  column.  In  these  animals  it  serves  to  support  the  head  and  neck,  which 
otherwise  from  their  own  weight  would  hang  down.  Its  rudimentary  state  in  man 
is  the  direct  consequence  of  his  erect  position. 

The  interspinous  ligaments  (fig.  205)  are  thin  membranous  structures  Avliicli 
extend  l)et\vccn  the  spines,  and  are  connected  with  the  ligamenta  su])tlava  in  front. 
and  the  sui>ras])inous  ligament  l)ehind.  The  fibres  pass  oblicjuely  from  the  root  of 
one  spine  to  the  ti])  of  the  next;  they  thus  decussate.  They  are  best  marked  in  the 
lum])ar  region,  and  are  replaced  by  the  well-developed  interspinales  muscles  in  the 
cervical  retrion. 


OF  VERTEBRAL  COLUMN 


197 


(e)  The  Ligaments  connecting   the   Transverse  Processes  with  one  another 

The  intertransverse  ligaments  are  barely  Avorth  the  name;  in  the  thoracic 
region  they  form  small  rounded  handles,  and  in  the  lumbar  they  are  thin  mem- 
branous bands,  quite  incapable  of  action  as  bonds  of  union.  They  consist  of  fibres 
passing  between  the  ajjices  of  the  transverse  processes.  In  the  cervical  region  they 
are  replaced  l)y  the  intertransversales  muscles. 

The  arterial  supply  for  the  column  comes  from  twigs  of  the  vertel)ral.  ascend- 
ing pharyngeal,  ascending  cervical,  superior  and  aortic  intercostals,  lumbar,  ilio- 
lumbar, and  lateral  sacral. 

The  nerve-supply  comes  from  the  spinal  nerves  of  each  region. 

Movements. — The  spinal  column  is  so  formed  of  a  number  of  bones  and  inter- 
vertcljral  discs  as  to  serve  many  purposes.  It  is  the  axis  of  the  skeleton;  u])on  it 
the  skull  is  supported;  and  with  it  the  cavities  of  the  trunk,  and  the  liml)s  are  con- 
nected. As  a  fixed  column  it  is  capable  of  bearing  great  weight ;  and.  through  the 
elastic  inten'crtebral  substances,    of   resisting  and   breaking   the  transmission  of 


Fig.  "205. — The  Ixterspixous  and  Slpra.spixuus  Li(TA:\rKXTs  ix  the  Lumbar  Kegiox. 


The  interspinou3 
ll  ligament 


The  supraapiuoua 
ligament 


shocks.  Moreover,  it  is  flexible,  and  therefore  capable  of  movement.  Now,  the 
range  of  movements  of  the  column  as  a  whole  is  very  consideral)le;  l>ut  the  move- 
ments between  any  two  vertebrae  are  slight,  so  that  motions  of  the  spine  may  take 
])lace  without  any  change  in  the  shape  of  the  column,  and  without  any  marked 
disturbance  in  the  relative  positions  of  the  vertebrffi.  It  is  about  the  pul})y  part  of 
the  intervertebral  discs,  Avhich  form  a  central  elastic  pivot  or  ball,  upon  which  the 
middle  of  the  vertebrae  rest,  that  these  movements  take  place. 

The  amount  of  motion  is  everywhere  limited  by  the  common  verteliral  liga- 
ments, but  it  depends  partly  upon  the  width  of  the  bodies  of  the  vertebra\  and 
partly  upon  the  depth  of  the  discs,  so  that  in  the  loins,  where  the  bodies  are  large 
and  wide,  and  the  discs  very  thick,  free  motion  is  permitted;  in  the  cervical  region, 
though  the  discs  are  thinner,  yet,  as  the  bodies  are  smaller,  almost  e(jually  free 
motion  is  allowed.  As  the  ball-like  pulpy  part  of  the  intervertebral  disc  is  the 
centre  of  movement  of  each  vertelira,  it  is  olwious  that  the  motion  would  be  of  a 
rolling  character  in  any  direction  but  for  the  articular  processes,  which  serve  also  to 
give  steadiness  to  the  column  and  to  assist  in  bearing  the  superincumbent  weight. 


198  THE  ARTICULATIONS 

^^'^,•re  it  not  for  theso  ])roct'Sses,  tlie  column,  instead  of  being  a  stationary  one, 
endowed  with  the  eajiaeitv  of  movement  l)y  muscular  agency,  would  be  a  tottering 
one,  requiring  nniscles  to  steady  it.  Tlie  influence  of  tlie  articular  processes  in 
limiting  the  direction  of  inclination  will  ai)pear  from  a  study  of  the  movements  in 
tlie  three  regions  of  the  spine. 

In  the  neck,  the  obliciuity  of  the  processes  permits  all  movements,  but  is  especi- 
ally favourable  for  extension.  Flexion  is  less  free  here  than  in  the  lumbar  region, 
while  extension  is  freer.  Lateral  flexion  is  more  free  in  the  neck  than  in  any  other 
region.  Rotatory  movements  are  also  free  in  the  neck,  especially  in  the  lower  part. 
There  is  but  slight  movement  of  any  sort  between  the  axis  and  third  cervical  ver- 
tebra, owing  to"  the  shallow  intervertebral  disc  and  the  great  prolongation  of  the 
anterior  lip  of  tlie  inferior  surface  of  the  body  of  the  axis,  which  checks  forward 
flexion  considerably. 

In  the  thoracic  region,  especially  near  its  middle,  antero-posterior  flexion  and 
extension  are  very  slight;  and,  as  the  concavity  of  the  curve  here  is  forwards,  the 
flat  and  nearly  vertical  surfaces  of  the  articular  processes  prevent  anything  like 
sliding  in  a  curvilinear  manner  of  the  one  set  of  processes  over  the  sharp  upper 
edges  of  the  other,  Avhich  would  be  necessary  for  forward  flexion.  A  fair  amount 
of  lateral  flexion  would  be  permitted  but  for  the  impediment  offered  by  the  rilis; 
while  the  slightly  outward  inclination  of  the  superior  process,  and  inward  inclina- 
tion of  the  inferior,  allow  a  little  rotation,  which  is  freer  in  the  upper  than  in  the 
lower  part  of  the  thoracic  region. 

In  the  lumbar  region,  extension  and  flexion  are  very  free,  especially  between 
the  third  and  fourth,  and  fourth  and  fifth  vertebra?,  where  the  lumbar  curve  is 
sharpest;  lateral  inclination  is  also  very  free  between  these  same  vertebra?.  It  has 
been  stated  that  the  shape  and  position  of  the  articular  processes  of  the  lumbar  and 
the  lower  two  or  three  dorsal  are  such  as  to  prevent  any  rotation  in  these  regions; 
but,  owing  to  the  fact  that  the  inferior  articular  processes  are  not  tightly  embraced 
by  the  superior,  so  that  the  two  sets  of  articular  processes  are  not  in  contact  on 
both  sides  of  the  l)odies  at  the  same  time,  there  is  alwa^'S  some  space  in  Avhich 
horizontal  motion  can  occur  round  an  axis  drawn  through  the  central  part  of  the 
bodies  and  intervertebral  discs.  Thus,  the  motions  are  most  free  in  those  regions 
of  the  column  which  have  a  convex  curve  forwards,  due  to  the  shape  of  the  inter- 
vertebral discs,  Avhere  there  are  no  bony  walls  surrounding  solid  viscera,  where 
the  spinal  canal  is  largest  and  its  contents  are  less  firmly  attached,  and  where  the 
pedicles  and  articular  processes  are  more  nearly  on  a  transverse  level  with  the 
posterior  surface  of  the  bodies  of  the  vertebra?. 

Nor  must  the  uses  of  the  ligamenta  subflava  be  forgotten:  these  useful  little 
structures  (1)  complete  the  roofing-in  of  the  spinal  canal,  and  yet  at  the  same 
time  permit  an  ever-changing  variation  in  the  width  of  the  interlaminar  spaces 
in  flexion  and  extension;  (2)  they  also  restore  the  articulating  surfaces  to  their 
normal  position  with  regard  to  each  other  after  movements  of  the  colunm; 
(3)  and  by  forming  the  inner  portion  of  each  capsular  ligament  they  take  the 
place  of  muscle,  in  preventing  it  from  being  nipped  between  the  articular  surfaces 
duriner  movement. 


2.  THE     SACRO-VERTEBKAL    ARTICULATIONS,    OR    THE    ARTICULA- 
TIONS OF  THE  PELVIS  WITH  THE  SPINE 

(" )   Class. — .  1  iiqili iarthrosift. 

(Ii )  Class. — Diartltro.si.'^.     Subdivision. — Arthrodta. 

As  in  the  intervertebral  articulations,  so  in  the  union  of  the  first  portion  of  the 
sacrum  with  the  last  lumbar  vertebra,  there  are  two  sets  of  joints — viz.  (a)  an 
amphiarthrodial  one,  between  the  bodies  and  intervertebral  disc;  and  (6)  a  ])air 
of  arthrodial  joints,  between  the  articular  processes.  The  union  is  efli'ected  by  the 
following  ligaments,  which  are  connnon  to  the  sjanal  column: — (i)  anterior^  and 
(ii)  iiosterior,  connnon;  (iii)  lateral  or  short  vertebral;  (iv)  capsular;  (v)  liga- 
mentum  subflavum;   (vi)  sujira-   and  (vii)  interspinous  ligaments.      Two   special 


OF  PELVIS  WITH  THE  SPLXE 


199 


accessory  ligaments  on  either  side,  viz.  the  sacro-lumbar  and  the  iHo-lumbar,  con- 
nect the  pelvis  with  the  fourth  and  fifth  lumbar  vertebrae. 

Tlie  sacro-lumbar  ligament  (fig.  206)  is  .strong,  and  triangular  in  shape.  Its 
ai)ex  is  above  and  internal,  being  attached  to  the  whole  of  the  lower  border  and 
front  surface  of  the  transverse  process  of  the  fifth  lumbar  vertebra,  as  well  as  to  the 
pedicle  and  body.  It  is  intimately  blended  with  the  ilio-lumbar  ligament.  Below,  it 
has  a  wide  fan-shaped  attachment,  extending  from  the  edge  of  the  ilio-lumbar  liga- 
ment forwards  to  the  brim  of  the  true  pelvis;  blending  with  the  periosteum  on  tlie 
base  of  the  sacrum  and  in  the  iliac  fossa,  and  with  the  superior  sacro-iliac  liga- 
ment. By  its  sharp  internal  border  it  limits  externally  the  foramen  for  the  lad 
lumbar  nerve.  It  is  pierced  by  two  large  foramina,  which  transmit  arteries  to  the 
sacro-iliac  synchondrosis.  This  ligament  is  in  series  with  the  intertransverse 
ligaments  of  the^pinal  column. 


Fig.  2(16. — Axtkkiok  View  of  thk  Lh;amexts  between  the  .Spixe  axd  Pelvi.s. 


Foramen  for  last 
lumbar  nerve 
Intervertebral  body 
between  last  lum- 
bar and  first  sacral 
vertebra 


mary  branch  of  fourth 


The  ilio-lumbar 
ligament 


The  sacro-lumbar 
ligament 


Superior  sacro-iliac 
ligament 


Anterior  sacro-iliac 
ligament 


Great  sacro-sciatic 
ligament 


Lesser  saero-seiatic 
ligament 


The  ilio-lumbar  ligament  (tig.  206)  is  a  strong,  dense,  triangular  ligament, 
which  springs  from  the  front  surface  of  the  transverse  process  of  the  fifth  luml>ar 
\ei'tebra  as  far  as  the  body,  by  a  strong  fasciculus  from  the  posterior  surface  of  the 
]irocess  near  the  tip,  and  also  from  the  front  surface  and  lower  edge  of  the  trans- 
verse process  and  pedicle  of  the  fourth  lumbar  verteljra,  as  far  inwards  as  the  body. 
Betiveen  (lie--<e  turj  lumbar  vertebrx  it  is  inseparable  from  the  intertran.^rer.se  ligament.  At 
its  origin  from  the  transverse  process  of  the  fifth  lumbar  vertebra,  it  is  closely 
interwoven  with  the  sacro-lumbar  ligament,  and  some  of  its  fibres  spread  down- 
wards on  to  the  body  of  the  fifth  vertebra,  while  others  ascend  to  the  disc  above. 

At  the  pelvis  it  is  attached  to  the  inner  lip  of  the  crest  of  the  ilium  for  about 
two  inches  (5  cm. ).  The  highest  fibres  at  the  spine  form  the  upper  edge  of  the 
ligament  at  the  ]>elvis.  those  which  come  from  the  posterior  i)Ortion  of  the  trans- 
verse process  of  the  fifth  lumbar  vertebra  forming  the  lower,  while  the  fibres  from 
the  front  of  the  same  process  pass  nearly  horizontally  outwards. 


200  THK  jnTICl'LATlOXS 

X<'ar  the  spine  the  surfaces  look  directly  l)ackwar(ls  and  forwards,  hut  at  the 
ilium,  the  ligament  gets  somewhat  twisted,  so  that  the  jjosterior  surface  looks  a 
little  upwards,  and  the  anterior  looks  a  little  downwards. 

The  anterior  surface  forms  part  of  the  posterior  houndary  of  the  false  pelvis, 
and  overlies  the  u]iper  part  of  the  ]iosterior  sacro-iliac  ligament;  the  posterior 
surface  forms  i)artof  the  floor  of  the  sjnnal  groove,  and  gives  origin  to  the  multijidu.-i 
^pitiiv  nuiscle.  Of  the  l)orders,  the  upper  is  ohlique,  has  the  anterior  lamella  of  the 
lumhar  fascia  attached  to  it,  and  gives  origin  to  the  qvadmtus  himhorvm ;  the  lower 
is  horizontal,  and  is  adjacent  to  the  upper  edge  of  the  sncro-lumhar  ligament;  while 
the  inner  is  crescentic,  and  forms  the  outer  houndary  of  a  foramen  through  which 
the  fourth  liimlxrr  nerve  passes. 

The  arterial  supply  is  very  free,  and  comes  from  the  last  luml^ar,  ili()-luml)ar, 
and  lateral  sacral. 

The  nerve-supply  is  from  the  sympathetic,  as  well  as  frf)m  twigs  from  the 
fourth  and  lifth  lumhar  nerves. 

Movements. — The  angle  formed  l)y  the  sacrum  with  the  spinal  column  is  called 
the  sacro-vertel)ral  angle.  The  pelvic  inclination  does  not  depend  entirely  upon 
this  angle,  hut  in  great  part  upon  the  obliquity  of  the  innominate  bones  to  the 
sacrum,  so  that  in  males  in  whom  the  average  pelvic  obliquity  is  a  little  greater, 
the  average  sacro-vertebral  angle  is  considerably  less  than  in  females. 

The  sacro-vertebral  angle  in  the  male  shows  that  there  is  a  greater  and  more 
sudden  change  in  direction  at  the  sacro-vertebral  union  than  in  the  female.  A  part 
of  this  change  in  direction  is  due  to  the  greater  thickness  in  the  anterior  part  of  the 
intervertebral  substance  between  the  last  lumbar  vertebra  and  the  sacrum.  Owing 
to  the  greater  thickness  of  the  intervertebral  disc  here  than  elsewhere,  the  move- 
ments permitted  at  this  joint  are  very  free,  being  freer  than  those  between  any  two 
lumbar  vertebne.  As  the  diameter  of  the  two  contiguous  bones  is  less  antero- 
l)Osteriorly  than  laterally,  the  forward  and  backward  motions  are  much  freer  than 
the  lateral  ones.  The  l)ackward  and  forward  motions  take  place  every  time  the 
sitting  is  exchanged  for  the  standing  position,  and  the  standing  for  the  sitting  pos- 
ture; in  rising,  the  back  is  extended  on  the  sacrum  at  the  sacro-lumbar  union;  in 
sitting  down  it  is  flexed. 

The  articular  processes  provide  for  the  gliding  movement  incidental  to  the 
extension,  flexion,  and  lateral  movements;  they  also  allow  some  horizontal  move- 
ment, necessary  for  the  rotation  of  the  spine  on  the  pelvis,  or  ])elvis  on  the  spine. 
The  interior  articular  })rocesses  of  the  fifth  differ  consideralily  from  the  inferior 
jtrocesses  in  the  rest  of  the  lumbar  vertebric,  and  in  direction  they  resemble  some- 
what those  of  the  cervical  vertebra?;  while  the  superior  articular  processes  of  the 
sacrum  differ  in  a  similar  degree  from  the  superior  processes  of  the  lumliar  vertebnw 
This  difference  allows  for  the  freer  rotation  which  occurs  at  this  joint. 

The  sacro-vertebral  angle  averages  117°  in  the  male,  and  130°  in  the  female; 
while  the  pelvic  inclination  averages  155°  in  the  male,  and  150°  in  the  female. 


3.  THE  ARTICULATIONS  OF  THE  PELVIS 

This  group  may  again  be  subdivided  into — 

('0  The  sacro-iliac. 
(f>)  Tlie  sacro-coccygeal. 
('•)   The  intercoccygeal. 
{<})  The  symphysis  pubis. 

(<i)  The  S.vciio-iLiAc  Synchondrosis  and  Sacro-sciatic  Lig.vments 

Class. — Amphiarthrosis. 

Like  the  symphysis  ])ubis,  the  sacro-iliac  sj-nchondrosis  is  an  amphiarthrodial 
joint,   but   it   differs    from  it  in  having   an   interosseous   ligament  as  well    as  an 


OF  THE  PELVIS 


201 


interosseous,  or  symphysial,  cartilage.     The  bones  which  enter  into  the  joint  are 
die  sacrum  and  ilium,  and  they  are  bound  together  by  the  following  ligaments: — 


Anterior  saero-iliae. 
Posterior  sucro-iliac. 


Interosseous. 


Superior  sacro-iHac. 
Inferior  sacrcj-iliac. 


The  anterior  sacro-iliac  ligament  (figs.  200  and  207)  consists  of  well-marked 
glistening  fibres  wliich  pass  above  into  the  sujierior,  and  below  into  the  inferior, 
ligaments.  It  extends  from  the  first  three  bones  of  the  sacrum  to  the  ilium  between 
the  brim  of  the  true  pelvis  and  the  great  sacro-sciatic  notch,  blending  with  the 
periosteum  of  the  sacrum  and  ilium  as  it  passes  away  from  the  united  edges  of  the 
bones. 

The  superior  sacro-iliac  ligament  (figs.  206  and  207)  extends  across  the  ui)per 
margins  of  the  joint,  from  the  base  of  the  sacrum  to  the  iliac  fossa,   being  well 


Fig.  207. — Vertical  A xtero- posterior  Section  of  the  Pelvis. 


Superior  saoro-iliao 
ligament 


Anterior  sacro-iliac 

ligament 

Inferior  Baero-iliao 

ligament 


Small  sacro-sciatic 
ligament 


Great  sacro-sciatic 
ligament 


marked  along  the  brim  of  the  pelvis,  where  it  is  thickened  l>y  some  closely-packed 
fibres.  Behind,  it  is  far  stronger,  especially  beneath  the  transverse  process  of  the 
fifth  lumbar  vertebra.  This  ligament  is  connected  with  the  strong  sacro-lumbar 
ligament,  which  spreads  outwards  and  forwards  over  the  joint  to  reach  the  iliac 
fossa  and  ilio-pectineal  line. 

The  posterior  sacro-iliac  ligament  is  of  very  great  strength,  extending  l)etween 
the  back  of  the  sacrum  and  the  posti'rior  two  inches  of  the  iliac  crest,  including  the 
posterior  superior  spine.  Strengthening  the  upper  and  liack  part  of  this  fibrous 
expansion  are  some  strong  Inmdles  of  ligamentous  fibres,  which  extend  more  or  less 
transversely  from  the  inner  surface  of  the  iliac  crest:  (i)  to  the  articular  process  of 
the  first  sacral  vertebra;  (ii)  to  the  l)one  between  the  articular  process  and  the  first 
sacral  foramen;  and  (iii)  to  the  articular  tubercle  of  the  second  sacral  Tertcl)ra, 
forming  a  ridge  over  the  second  sacral  foramen  under  Avhich  the  nerve  passes;  an 
ol)lique  band  often  connects  this  last  fasciculus  with  the  articular  process  of  the 
first  sacral  vertebra.     Below  this,  the  fibres  pass  downwards  and  inwardis  from  the 


202  TUK  ARricriATJoys 

lust  inch  of  tlie  iliac  crest  to  the  side  of  the  sacrum  external  to  the  second  and  tliird 
])osterior  sacral  foramina.  To  the  outer  edge  of  this  ligament  is  attached  the  fascia 
covering  the  eret-tor  sjMna'  muscle. 

The  inferior  sacro-iliac  ligament  (tig.  207;  is  covered  l>ehind  hy  the  upper 
end  of  the  great  sacro-sciatic  ligament;  it  consists  of  strong. <libres  extending  from 
the  lateral  border  of  the  sacrum  below  the  articular  facet,  to  the  posterior  iliac 
spines;  some  of  the  fibres  are  attached  to  the  deep  surface  of  the  ilium  and  join  the 
interosseous  ligament. 

The  interosseous  ligament  is  the  strongest  of  all,  and  consists  of  fil)res  of 
different  lengths  passing  in  various  directions  between  the  two  bones.  Immediately 
above  the  interspinous  notch  of  the  ilium  the  fibres  of  this  ligament  are  very  strong, 
and  form  an  open  network,  in  the  interstices  of  which  is  a  quantity  of  fat  in  Avhich 
the  articular  vessels  ramify. 

The  ear-shaped  cartilaginous  plate,  which  unites  the  bones  firmly,  is  accu- 
rately applied  to  the  auricular  surfaces  of  the  sacrum  and  ilium.  It  is  about  one- 
twelfth  of  an  inch  (2  mm. )  thick  in  the  centre,  but  becomes  thinner  towards  the 
edges.  Though  closely  adherent  to  the  bones,  it  tears  away  from  one  entirely,  or 
from  both  iiartialh',  on  the  application  of  violence,  sometimes  breaking  irregularly 
so  that  the  greater  portion  remains  connected  with  one  bone,  leaving  the  other  bone 
rough  and  bare.  It  is  really  one  mass,  and  is  only  occasionally  formed  of  two  plates 
with  a  synovial  cavity  between  them.  Because  of  the  occasional  presence  of  a  more 
or  less  extensive  synovial  cavity  within  the  fibro-cartilage,  and  also  of  a  synovial 
lining  to  the  ligaments  passing  in  front  and  behind  the  articulation,  the  term 
'  Diarthro-amphiarthrosis '  has  been  given  to  this  joint,  and  also  to  the  symphysis 
pubis.  Testut  mentions  certain  folds  of  synovial  membrane  filling  up  gaps  which 
here  and  there  occur  at  margin  of  the  fibro-cartilage,  but  I  have  not  myself  seen 
such. 

The  great  or  posterior  sacro-sciatic  ligament  (figs.  206,  207  and  208)  is 
attached  al>ove  to  the  ])osterior  extremity  of  the  crest  of  the  ilium  and  the  external 
aspect  of  the  posterior  iliac  spines.  From  this  attachment  some  of  its  fibres  pass 
downwards  and  backwards  to  be  attached  to  the  outer  ])orders  and  posterior  sur- 
faces of  the  lower  three  sacral  vertebrte  and  up}ier  two  segments  of  the  coccyx; 
while  others,  after  passing  for  a  certain  distance  backwards,  curve  forwards  and 
downwards  to  the  ischium  forming  the  anterior  free  margin  of  the  ligament  where 
it  limits  posteriorly  the  sacro-sciatic  foramina.  These  fibres  are  joined  by  others 
which  arise  from  the  posterior  surfaces  of  the  lower  three  sacral  vertebrae  and  upper 
pieces  of  the  coccyx.  At  the  ischium  it  is  fixed  to  the  inner  border  of  the  great 
tuberosity,  and  sends  a  thin  sharp  process  upwards  along  the  ramus  of  the  ischium 
which  is  called  the  falciform  process  (fig.  208),  and  is  a  prolongation  of  the  pos- 
terior edge  of  the  ligament.  A  great  many  fibres  pass  on  directly  into  the  tendon 
of  the  biceps  muscle,  so  that  traction  on  this  muscle  braces  up  the  whole  liga- 
ment, and  the  coccyx  is  thus  made  to  move  on  the  sacrum.  The  ligament  may 
not  unfairly  be  described  as  a  tendinous  expansion  of  the  muscle,  whereby  its 
action  is  extended  and  a  more  advantageous  leverage  given.  It  is  broad  and  flat  at 
its  attached  ends,  but  narrower  and  thicker  in  the  centre,  looking  like  two  triangular 
expansions  joined  by  a  flat  band,  the  larger  triangle  being  at  the  ilium,  and  the 
smaller  at  the  ischium.  The  fibres  of  the  ligament  are  twisted  upon  its  axis  at  the 
narrow  part,  so  that  some  of  the  superior  fibres  pass  to  the  lower  border. 

The  posterior  surface  gives  origin  to  the  cjhiteus  mnximu.s  muscle,  and  on  it 
ramify  the  loops  from  the  jiosterior  branches  of  the  sacral  nerves;  its  anterior  sur- 
face is  closely  connected  at  its  origin  with  the  small  sacro-sciatic  ligament,  and  some 
fibres  of  Uw  pi/riformi.i  nuiscle  arise  from  it;  below,  the  obturator  mfernus  passes  out 
of  the  i)elvis  under  its  cover,  and  the  internal  pndic  re,s.-ieh  and  verve  pass  in.  At  the 
ilium,  its  })Ost.erior  t-dge  is  continuous  witli  the  v.ertebral  aponeurosis;  while  to  the 
anterior  edge  is  attached  the  thick  fascia  covering  the  gluteus  medius.  The  obtura- 
tor fiiscia  is  attached  to  its  falciform  edge.  It  is  pierced  by  the  coccygeal  branches  of 
the  sciatic,  and  a  branch  from  i\\c  fonrfh  literal  nerre. 

The  small  sacro-sciatic  ligament  (figs.  206,  207  and  208)  is  triangular  and 
thin,  springing  l»y  a  broad  l)ase  from  the  lateral  border  of  the  sacrum  and  coccyx, 
from  the  front  of  the  sacrum  both  above  and  below  the  level  of  the  fourth  sacral 


OF  THE  PELVIS 


203 


foramen,  and  from  the  coccyx  nearly  as  far  as  its  tip.  By  its  apex  it  is  attat-hed  to 
the  front  surface  and  the  borders  of  the  ischial  spine  as  far  outwards  as  its  base.  Its 
fibres  decussate  so  that  the  lower  ones  at  the  coccyx  become  the  liighest  at  the 
ischial  spine;  muscular  til)res  are  often  seen  intermingled  with  the  ligamentous. 

It  is  situated  in  front  of  the  great  sacro-sciatic  ligament,  with  which  it  is 
closely  connected  at  the  sacrum,  and  separates  the  greater  from  the  lesser  sacro- 
sciatic  foramen.  Its  front  surface  gives  attachment  to  the  coccygeus  muscle,  which 
overlies  it.  Behind,  it  is  connected  with,  and  hidden  by,  the  great  sacro-sciatic 
ligament,  so  that  only  the  outer  inch  or  less  (2  cm.)  and  a  small  part  of  its  attach- 
ment to  the  coccyx,  can  be  seen;  the  internal  pudic  nerve  also  passes  over  the 
posterior  surface. 

The  arterial  supply  comes  from  the  gluteal,  ilio-lumbar,  and  lateral  sacral. 

The  nerve-supply  is  from  the  superior  gluteal,  sacral  plexus,  and  external 
twigs  of  the  ]»()sterior  divisions  of  the  first  and  second  sacral  nerves. 

The  movements. — It  is  quite  clear,  from  the  nature  of  the  osseous  surfaces. 


Fig.  20^. — Sacro-sciatic  Ligaments.     (Posterior  view. 


Anterior  or  small  aaero- 
Bciatic  ligament 


Falciform  process  of  the 
great  ligament 


Tendon  of  biceps  muscle,  continuous  with 
the  great  saero-seiatie  ligament 


from  the  wedge-shape  of  the  sacrum,  and  the  manner  in  which  it  is  locked  in 
between  the  hip-bones,  as  well  as  from  the  amphiarthrodial  character  of  the  articu- 
lation, that  there  can  be  no  movement  at  the  sacro-iliac  joint.  "\Mnle  the  joint 
serves  the  useful  purpose  of  breaking  shocks,  the  cartilage  is  too  thin  and  too 
finnly  fixed  to  the  bones  to  allow  even  of  appreciable  yielding,  such  as  occurs  upon 
the  intervertebral  discs. 

The  double  wedge-shape  of  the  sacrum,  Mith  its  broader  surface  at  the  base  and 
in  front,  prevents  dislocation  from  forces  acting  from  above  downwards,  and  from 
before  backwards. 

The  sinuous  character  of  the  oi)posed  surfaces  of  the  sacrum  and  ilium,  the  for- 
ward and  inward  direction  of  the  til)rcsof  the  posterior  sacro-sciatic  ligament  which 
pass  from  ilium  to  sacrum,  as  well  as  the  ilio-lumbar  and  sacro-lumbar  ligaments, 
prevent  forward  displacement  of  the  base  of  the  sacrum;  while  the  sacro-sciatic 
ligaments  prevent  the  tilting  backwards  of  its  ai)ex.  Thus  rotation  forwards  is 
entirely  prevented. 

The  shape  of  the  sacrum  prevents  its  downward  displacement,  while  the  weight 


•204 


THE   A  R  TTCI  'LA  TIOXS 


of  the  fjpinc  and  the  li^raments,  which  fasten  the  sacrum  to  tlie  ilium,  are  sufficient 
to  check  its  upward  displacement. 

Tlie  anterior  and  downward  displacements  of  the  sacrum  are  prc'jnted  by  the 
interosseous  and  posterior  sacro-sciatic  ligaments,  which  pass  from  tne  ilia  to  the 
sacrum,  and  suspend  the  latter,  acting  somewhat  in  the  same  manner  as  the  chains 
of  a  susjiension  bridge.  They  also  bind  the  two  bones  more  tightly  together:  the 
greater  the  jtressure,  the  tighter  the  union.  The  suspension  bridge  arrangement  of 
the  sacro-iliac  syncliondrosis  is  admirably  adaj)ted  to  give  strength  to  the  pelvis. 

{h)  The  8acro-coccygeal  Articulation 
Class . — Amiph  ia  rtJi  ro«^s■. 

The  last  piece  of  the  sacrum  and  first  })iece  of  the  coccyx  enter  into  this  union, 
and  are  bound  together  by  the  following  ligaments: — 


Anterior  sacro-coccygeal. 
Posterior  sacro-coccvgeal. 


Supracornual. 
Intertransverse. 


Intervertebral  suljstance. 

The  intervertebral  substance  is  a  small  oval  disc,  three-quarters  of  an  inch 
(about  2  (111.  )  wide,  and  a  little  less  from  before  backwards,  closely  connected  with 
the  surrounding  ligaments.  It  resembles  the  other  discs  in  structure,  but  is  softer 
and  more  jelly-like,  though  the  laminae  of  the  fibrous  portion  are  well  marked. 


Fig.  -209. — Lioamexts  conxectixg  Sacrum  and  Coccyx  postekiorly. 


Superflcial  part  of 
the  supraspinous 
ligament,  turned 
up 


Deep  part  of  the  su- 
praspinous ligament, 
turned  up 


Intertransverse 
ligament 


The  posterior  sacro-eoecy- 
geal  ligament,  or  the  lower 
end  of  the  posterior  com- 
mon ligament 


Supracornual  ligament  eon- 
nectiug  the  cornua  of  the 
sacrum  and  coccyx,  cut  and 
turned  down 


The  anterior  sacro-coccygeal  ligament  is  a  ])rolongation  of  the  gbstening 
fibrous  structure  on  the  front  of  tlic  saciuni.  It  is  really  tlu'  lower  extreniitv  of  the 
anterior  common  ligament,  which  is  thicker  over  this  join:  than  over  the  central 
part  of  either  of  the  l»ones. 


OF  THE  SACRUM  AXD  COCCYX  205 

The  posterior  sacro-coccygeal  ligament  (fig.  209)  is  a  direct  continuation  of 
tlie  posterior  common  ligament  of  the  column,  consisting  of  a  narrow  band  of 
closely  packed  filjres,  which  become  blended  at  the  lower  l)order  of  the  first  segment 
of  the  coccyx  with  the  filuni  tcrminale  and  supracornual  ligament. 

The  supracornual  ligament  (fig.  209)  is  the  prolongation  of  the  supraspinous, 
which  becomes  inseparably  l)lcnded  with  the  aponeurosis  of  the  erector  spinse  opposite 
the  laminae  of  the  third  sacral  vertebra,  and  is  thus  prolonged  downwards  upon  the 
back  of  the  coccyx,  passing  over  and  roofing  in  the  lower  end  of  the  spinal  canal 
where  the  laminse  are  deficient.  The  median  fibres  (the  supraspinous  ligament) 
extend  over  the  back  of  the  coccyx  to  its  tip,  blending  with  the  posterior  sacro- 
coccygeal ligament  and  filum  terminale;  the  deeper  fibres  run  across  from  the  stunted 
laminae  on  one  side  to  the  next  below  on  the  opposite  side,  and  from  the  sacral 
cornua  on  one  side  to  the  coccygeal  on  the  opposite,  some  passing  between  the  two 
cornua  of  the  same  side,  and  bridging  the  aperture  through  which  the  fifth  sacral 
nerve  passes.     Its  posterior  sui'face  gives  origin  to  the  gluteus  maximus  muscle. 

The  intertransverse  ligament  (fig.  209)  is  merely  a  quantity  of  fibrous  tissue 
wliich  passes  from  the  transverse  process  of  the  coccyx  to  the  lateral  edge  of  the 
sacrum  below  its  angle.  It  is  connected  with  the  sacro-sciatic  ligaments  at  their 
attachments,  and  the  fifth  sacral  nerve  escapes  behind  it.  It  is  perforated  by  twigs 
from  the  lateral  sacral  artery  and  the  coccygeal  ner^'c. 

The  arterial  supply  is  from  the  lateral  sacral  and  sacro-median  arteries. 

The  nerves  come  from  the  fourth  and  fifth  sacral  and  coccygeal  nerves. 

The  movements  permitted  at  this  joint  are  of  a  simple  forward  and  backward, 
or  hinge-like  character.  In  the  act  of  defecation,  the  bone  is  pushed  back  Ijv  the 
fa'cal  mass,  and,  in  parturition,  l)y  the  foetus;  but  this  backward  movement  is 
controlled  by  the  upward  and  f(^rward  pull  of  the  levator  ani  and  coccygeus.  The 
external  sphincter  also  tends  to  pull  the  coccyx  forwards. 


(c)    IXTERCOCCYGEAL   JoiNTS 

The  several  segments  of  the  coccyx  are  held  together  by  the  anterior  and 
posterior  common  ligaments,  Avhich  completely  cover  the  bony  nodules  on  their 
anterior  and  posterior  aspects.  Laterally,  the  sacro-sciatic  ligaments,  being  attached 
to  nearly  the  whole  length  of  the  coccyx,  serve  to  connect  them.  Between  the  first 
and  second  pieces  of  the  coccyx  there  is  a  very  perfect  amjihiarthrodial  joint,  with 
a  well-marked  intervertebral  substance. 


(d)  The  Symphysis  Pubis 
Class,  — A  mph  la  rth  ros  is. 

The  l)ones  entering  into  this  joint  are  the  pubic  ])ortions  of  the  hip-bones. 
This  joint  is  shorter  and  l)roader  in  the  female  than  in  the  male.  The  ligaments, 
which  completely  surround  the  articulation,  are: — 

Superior.  Anterior. 

Inferior.  Posterior. 

Interosseous  cartilage. 

The  superior  ligament  (figs.  210  and  211)  is  a  well-marked  stratum  of 
yellowish  fibrc?^  whicli  extends  outwards  along  the  crest  of  the  pubes  on  each  side, 
blending  in  the  middle  line  with  the  interosseous  cartilage.  It  is  continuous  in 
front  with  the  deep  transverse  fibres  of  the  anterior  ligament,  and  behind  Avith  the 
posterior  ligament.      It  gives  origin  to  the  rectus  abdominis  tendon. 

The  posterior  ligament  (fig.  212)  is  slight,  and,  excepting  above  and  below, 
consists  of  little  more  than  thickened  periosteum.  Near  the  upper  part  is  a  Ijand 
of  strong  fibres,  reaching  the  whole  width  of  the  pubic  bones,  and  continuous  with 
the  thickened  periosteal  fibres  along  the  ilio-pectineal  line.  BeloAv,  many  of  the 
upper  and  superficial  fibres  of  the  infrapubic  ligament  ascend  over  the  back  of  the 


206 


THE  A  R  riCULA  TIOXS 


joint,  and  interlace  across  the  median  line  with  fibres  from  the  opposite  side  nearly 
as  high  as  tlie  middle  of  the  symphysis. 

The  anterior  ligament  (tigs.  2iO  and  211)  is  thick  and  strong,  and  is  closely 
connected  with  the  fascial  covering  of  the  muscles  arising  from  the  l)ody  of  the 
pubes.  It  consists  of  several  strata  of  thick  decussating  fibres  of  different  degrees 
of  ol)liquity,  the  superficial  being  the  most  oblique,  and  extending  lowest  over  the 
joint.     The  most  superficial  descending  fibres  extend  from  the  upper  border  of  the 


Fig.  -210.— Axtkkior  Vikw  of  the  Sy.mphysis  Pubis  (Male),  showing  the  Decussation 
OK  THE  Fibres  of  the  Anteeiok  Ligament. 


Superior  pubic  ligament 


Infex'ior  pubic  liga 


pubis,  cross  others  from  the  opposite  side  about  the  middle  of  the  symphysis,  and 
are  attached  to  the  ramus  of  the  opposite  bone.  The  most  superficial  ascending 
fibres  come  from  the  infrapubic  ligament,  arch  upwards,  and  decussate  with  other 
fibres  across  the  middle  line,  and  are  lost  on  the  opposite  side  beneath  the  descend- 
ing set.  There  is  another  deeper  set  of  descending  fibres  which  arise  below  the 
angle,  Init  do  not  descend  so  far  as  the  superficial;  and  a  deeper  set  of  ascending, 
which  decussate,  and  reach  higher  than  the  superficial  set,  and  are  connected  with 

Fig.  -211.— Anterior  View  of  the  Symphysis  Pubis  (Female),  showing  greater  Width 

BETWEEN   the   BONES. 
Superior  pubic  ligament 


Inferior  pubic  ligament 


tlic    infr:i]»ubic    ligament.     Some   few  transverse    fibres    pass    from    side    to    side, 
especially  al)()ve  and  Ix'low  the  ])(>ints  of  decuss^ition. 

The  inferior  or  infrapubic  ligament  (figs.  210,  211  and  212)  is  a  thick,  arch- 
like band  of  closely  ])acked  fibres  which  fills  up  the  angle  between  the  })ubic  rami, 
and  forms  a  smooth,  rounded  summit  to  the  pubic  arch.  On  section,  it  is  yellow- 
ish in  colour  and  three-eighths  of  an  inch  (1  cm.)  thick  in  the  middle  line;  it  is 
inseparably  connected  with  the  interosseous  cartilage.  Both  on  the  front  and  back 
aspects  of  the  joint  it  gives  off  decussating  fibres,  which,  by  their  interlacement  over 


THE  SYMPHYSIS  PUBIS 


207 


the  anterior  and  posterior  ligaments  of  the  symi)hysis,  add  very  materially  to  its 
security.  In  fact,  the  ligament  may  be  said  to  split  supcriorl}-  into  two  layers,  one 
])assing  over  the  front,  and  the  other  over  the  back  of  the  articulation.  It  is 
sometimes  known  as  the  ligannentum  arcuatum. 

The  interosseous  fibro-cartilage  varies  in  thickness  in  different  sul)jects,  but 
is  thicker  in  the  female  than  in  the  male.  It  is  thicker  in  front  than  behind,  and 
projects  l)eyond  tlie  edges  of  the  l)ones,  especially  jjosteriorly  (see  tig.  212),  blend- 
ing intimately  witli  the  ligaments  at  its  margins.      It  is  sometimes  uninterruptedly 

Fio.  212— PosTKKiou  View  of  the  Symphysis  Pubis,  showing  the  Backward   Pro.jec- 

TIOX   OF   THE   SYMPHYSIAL    SUBSTANCE   AND   THE   DECUSSATION   OF    THE   FiBKES   FROM   THE 

Inferior  Pubic  Ligajient. 


Inferior  pubic  ligament 

woven  throughout,  but  at  others  has  an  elongated  narrow  fissure,  partially  dividing 
the  cartilage  into  two  plates,  with  a  little  fluid  in  the  interspace  (fig.  213).  This 
is  situated  towards  the  upper  and  posterior  aspects,  but  does  not  usually  reach 
either;  it  generally  extends  aVjout  half  the  length  of  the  cartilage.  When  this  cavity 
is  large,  especially  if  it  reaches  or  approaches  very  near  to  the  circumference  of  the 
cartilage  (which,  however,  it  very  rarely  does),  it  is  thought  by  some  anatomists 
that  it  more  nearly  resembles  a  diarthrodial  than  an  amphiarthrodial  joint,  and  it 
is  then  classed  with  the  sacro-iliac  joint  under  similar  conditions,   as   '  diartliro- 

FiG.  213. — Section  of  Symphysis  to  show  the  Synovial  Cavity. 


amphiarthrosis. '  The  interosseous  cartilage  is  intimately  adherent  to  the  rough 
osseous  surface  of  the  bone,  which  is  ridged  to  give  it  a  firmer  attachment;  and,  on 
forcing  the  Ijones  apart,  it  does  not  frequently  split  into  two  plates,  but  is  torn  from 
the  V>one  on  one  side  or  the  other. 

The  arterial  supply  is  from  twigs  of  the  internal  pudic,  pubic  branches  of  the 
obturator  and  epigastric,  and  ascending  branches  of  the  internal  circumfiex  and 
superficial  external  })udic. 

The  nerve-supply  has  not  been  satisfactorily  made  out.  but  it  probably  comes, 


208  THE  ARTICULATIOXS 

in  i)art,  from  tlie  internal  piulir  and  in  part  from  the  ilio-hypogastric  and  ilio- 
inguinal. 

The  movements  amount  only  to  a  slight  yielding  of  the  cartilage;  neither 
mu.^eular  force  nor  extrinj?ic  forces  produce  any  appreciable  movement  in  the 
ordinary  condition.  Occasionally,  as  the  result  of  child-bearing,  the  joint  becomes 
unnaturally  loose,  and  then  walking  and  standing  are  painfully  unsteady.  It  is 
known  that,  during  pregnancy  and  parturition,  the  symphysial  cartilage  becomes 
softer  and  more  vascular,  so  as  to  permit  the  temporary  enlargement  of  the  pelvis; 
but  it  nuist  be  remeni1)ered  that  the  fibres  of  the  oblique  muscles  decussate,  and 
thus,  during  labour,  Avhile  they  force  the  head  of  the  foetus  down,  they  strengthen 
the  joint  l)y  bracing  the  bones  more  tightly  together. 


4.  THE  ARTICULATIONS  OF  THE  RIBS  WITH  THE  VERTEBRA 

These  consist  of  tAvo  sets,  xiz. : — 

(a)  The  costo-central :  i.e.  the  articulation  of  the  head  of  the  rib  with  the 
vertebra?. 

(6)  The  costo-transverse,  or  the  articulation  of  the  tubercle  (of  each  of  the 
first  ten  ril)s)  with  the  transverse  process  of  the  lower  of  the  two  vertebrae,  with 
which  the  head  of  the  rib  articulates:  i.e.  the  one  bearing  its  own  number,  as  the 
first  rib  with  the  first  thoracic  vertebra,  the  second  rib  Avith  the  second  thoracic 
vertebra,  and  so  on. 

(a)  The  Costo-central  Articulation 
Class. — Diarthrosis.  Subdivision. — Condylarthrosis. 

It  is  a  very  perfect  joint,  into  the  formation  of  which  the  head  of  the  rib  and 
two  vertebrae,  Avith  the  interA'erteliral  disc  betAveen  them,  enter.  In  the  case  of  the 
first,  tenth,  eleventh,  and  twelfth  ribs,  it  is  formed  by  the  head  of  the  rib  articulating 
Avith  a  single  A'crtebra. 

The  ligaments  are: — 

Capsular.  Interarticular. 

Stellate  or  anterior  costo-central. 

The  capsular  ligament  (fig.  214)  consists  of  short,  strong,  Avoolly  fibres,  com- 
pletely surrounding  the  joint,  Avhich  are  attached  to  the  bones  and  intervertebral 
substances,  a  little  beyond  their  articular  margins.  At  its  u]iper  part  it  reaches 
through  the  intervertebral  foramen  toAvards  the  back  of  the  ]>odies  of  the  vertebrae, 
being  strengthened  here  by  fibres  Avhich  at  intervals  connect  the  anterior  Avith  the 
posterior  common  ligaments.  The  lower  fibres  extend  doAvuAvards  nearly  to  the 
demi-facet  of  the  rib  beloAv;  behind,  it  is  continuous  Avith  the  middle  costo- 
transverse ligament,  and  in  front  is  overlaid  by  the  stellate. 

The  interarticular  ligament  (fig.  215)  consists  of  short,  strong  fibres,  closely 
interAVOven  A\ith  the  outermost  ring  of  the  intervertel iral  disc,  and  attached  to  the 
ti-ansvcrse  ridge  separating  the  articular  facets  on  the  head  of  the  rib.  It  completely 
divides  the  articulations  into  tAvo  parts,  but  does  not  brace  the  rib  tightly  to  the 
spine,  being  loose  enough  to  alloAV  a  moderate  amount  of  rotation  on  its  OAvn  axis. 
There  is  no  interarticular  ligament  in  the  costo-vertebral  joints  of  the  first,  tenth, 
elcA'cntb,  and  tAvelftli  ribs. 

The  anterior  costo-central  or  stellate  ligament  (figs.  215  and  216)  is  the 
most  striking  of  all,  and  consists  of  bright,  pearly-Avhite  fibres  attached  to  the 
anterior  surface,  and  upper  and  loAver  borders  of  the  neck  of  the  rib,  a  little  Avay 
beyond  the  articular  facet ;  from  this  they  radiate  upAvards,  forAvards,  and  doAvn- 
Avards,  so  as  to  form  a  continuous  layer  of  distinct  and  shari)ly  defined  fibres.  The 
middle  fibres  run  straight  forAvard'to  be  attached  to  the  iiitevertebral  disc;  the 
upper  ascend  to  the  loAver  lialf  of  the  lateral  surface  of  the  vertebra  above,  and  the 
loAver  descend  to  the  ui»i)er  half  of  the  vertebra  beloAv. 


OF  THE  RIBS  WITH  VERTEBRAE 


209 


The  stellate  ligament  is  overlapped  at  the  spine  by  the  short  verte])ral  ligaments. 
In  the  case  of  the  tirst,  tenth,  eleventh,  and  twelfth  ribs,  each  of  which  articu- 
lates with  one  vertebra,  the  ligament  is  not  quite  so  distinctly  stellate,  but  even 


Fig.  214. — The  Capsular  Ligaments  of  the  Costo-vertebrai.  Joints. 


Spinous  process  of  seventh 
cervical  vertebra 


Capsular  ligament  of  the  first  eosto-trans- 
verse  Joint 


Capsular  ligament  of  first 
costo-central  joint 


in  these  the  ascending  fibres  reach  the  vertebra  above  that  Avith  which  the  rib 
articulates. 

The  synovial  membranes  (fig.  216)  consist  of  two  closed  sacs  which  do  not 
communicate:  one  above,  and  the  other  below  the  interarticular  ligament.     In  the 


Fig.  215. — Showing  the  Anterior  Common    Ligament  of  the  Spine,  and  the  Connec- 
tion  OF  the   Ribs   with   the   VERTEBRiE. 


The  interarticular 
ligament 


The  superior  or  anterior 
eosto-transverse  ligaments 


The  stellate  ligament 


case  of  the  first,  tenth,  eleventh,  and  twelftli  articulations,  there  is  but  one  synovial 
membrane,  as  these  joints  have  no  interarticular  ligament. 

The  arterial  supply  is  from  the  intercostal  arteries,  tlu^  twigs  piercing  the 
stellate  and  capsular  ligaments. 
14 


210 


THE  A  R  TIC  I  LA  TIOXS 


The  nerve-supply  cxints  t'roin  the  anterior  primary  hranches  of  the  intercostal 
nerves. 

These  joints  api^-oach  most  nearly  in  their  movements  to  the  condylarth roses. 

The  movements  are  ginglymoid  in  character,  consisting  of  a  sHght  degree  of 
elevation  and  depression  around  an  ol)liquely  horizontal  axis  corresponcHng  with 
the  interarticular  hgament;  there  is  also  a  shght  amount  of  forward  and  Ixickward 
gliding;  and  a  slight  degree  of  screwing  or  rotatory  movement  is  also  possible. 
There  is  a  consideral)le  dilference  in  the  degree  of  mobility  of  the  different  ribs,  for 
while  the  first  rib  is  almost  immobile  except  in  a  very  deep  inspiration,  the  mobility 
of  the  others  increases  from  the  second  to  the  last;  the  two  floating  ribs  being  the 
most  mobile  of  all.  The  head  of  the  rib  is  the  most  fixed  point  of  the  costal  arch, 
and  ui>on  it  the  whole  arch  rotates;  the  interarticular  ligament  allows  only  a  very 


Fig.  216.— Horizontal  Section'  through  the  Intervertebral  Disc  and  Ribs. 


Anterior  costo-central 
or  Btellate  ligament 


Costo-central  synovial 
sac 


Middle  costo-trans- 
verse  ligament 


Laminar  portion  of  inter- 
vertebral disc 


Central  pulpy  portion  of  inter- 
vertebral disc 


Costo-tranaverse  synovial  sac 


Posterior  costo-trausverse 
ligament 


limited  amount  of  flexion  and   extension  (i.e.  elevation  and  depression),  and   of 
gliding.     Gliding  is  checked  by  the  stellate  ligament. 

In  inspiration,  the  rib  is  elevated,  and  glides  forwards  in  its  socket,  too  great 
elevation  being  checked  not  only  by  the  ligaments,  but  also  by  the  overhanging 
upper  edge  of  the  cavity  itself.  In  expiration,  the  rib  is  depressed,  and  glides 
Ijackwards  in  its  cavitv. 


(/;)  The  Costo-transverse  Articulation 
Class. — Di'ivthro.-ii.-i.  Subdivision. — Arthrodia. 

This  joint  is  formed  by  the  tubercle  of  the  rib  articulating  with  the  anterior  part 
of  the  tip  of  the  transverse  process.  The  eleventh  and  twelfth  ribs  are  devoid  of 
tliese  joints,  for  the  tubercles  of  these  ribs  are  absent,  and  the  transverse  processes 
of  the  eleventh  and  twelfth  thoracic  vertebrae  are  rudimentary. 

The  ligaments  of  the  union  are: — 


Capsular. 

Middle  costo-transverse. 


Su])erior  costo-transverse. 
P( )st('rior  costo-transverse. 


The  capsular  ligament  ( ligs.  214  and  21G)  forms  a  thin,  loose,  fil)rous 
envelope  to  the  synovial  membrane.  Its  filjres  are  attached  to  the  bones  just 
beyond  the  articular  margins,  and  arc  thickest  below,  where  they  are  not  strength- 
ened by  any  other  structure.     It  is  connected  on  the  inner  side  with  the  middle, 


OF  THE  STERXUM  211 

above  with  the  sui)cnor,  and  on  the  outer  siile  with  the  ])ostenor  costo-transverse 
hganients.     The  eleventh  and  twelfth  ribs  are  unprovided  with  a  ca])sule. 

The  middle  costo-transverse,  or  interosseous  ligament  (fig.  216),  consists 
of  short  libres  passing  between  the  Ixick  of  tlie  neck  of  the  rib  and  front  of  the 
transverse  process,  with  which  the  tubercle  articulates.  It  extends  from  the 
capsule  of  the  central  costo-vertebral  joint  to  that  of  the  costo-transverse.  It  is 
best  seen  on  horizontal  section  through  the  bones.  In  the  eleventh  and  twelfth 
ribs  tliis  ligament  is  rudimentary. 

The  posterior  costo-transverse  ligament  (iig.  216)  is  a  short  but  tliiek, 
strong,  and  bi-oad  ligament,  which  extends  outwards  and  upwards  from  the 
extremity  of  the  transverse  process  to  the  non-articular  surface  of  the  tubercle 
of  the  corresponding  rib.  The  eleventh  and  twelfth  ribs  have  no  posterior 
ligament. 

The  superior  costo-transverse  ligament  (fig.  215)  is  a  strong,  broad  band  of 
fil)res  which  ascends  outwards  from  tlie  crest  on  the  upper  border  of  the  neck 
of  the  rib,  to  the  lower  border  of  the  transverse  process  above.  A  fcAV  scattered 
posterior  fibres  pass  upwards  and  inwards  from  the  neck  to  the  transverse  process. 
It  is  best  seen  from  the  front.  Its  inner  1)order  l)ounds  the  foramen  through 
Avhich  the  posterior  branches  of  the  intercostal  vessels  and  nerves  pass.  To 
the  external  border  is  attached  the  thm  aponeurosis  covering  the  external  inter- 
costals.  Its  anterior  surface  is  in  relation  with  the  intercostal  vessels  and  nerve; 
the  posterior  with  the  lonjissimus  dorsi.  The  first  rib  has  no  superior  costo- 
transverse ligament. 

The  synovial  membrane  (fig.  216)  is  a  single  sac. 

The  arterial  and  nerve  supplies  come  from  the  posterior  l)ranches  of  the  inter- 
costal arteries  and  nerves. 

The  movements  which  take  place  at  these  j<jints  are  lindted  to  a  gliding  of  the 
tubercle  of  the  rib  upon  the  transverse  process.  The  exact  position  of  the  facet  on 
the  transverse  process  varies  slightly  from  alcove  downwards,  being  placed  higln-r 
on  the  processes  of  the  lower  vertebrae.  The  plane  of  movement  in  most  of  the 
costo-transverse  joints  is  inclined  upwards  and  liackwards  in  inspiration,  and 
downwards  and  forwards  in  expiratiijn.  The  point  round  Avhieli  these  movements 
occur  is  the  head  of  the  rib,  so  that  the  tubercle  of  the  ril)  glides  upon  the 
transverse  process  in  the  circumference  of  a  circle,  the  centre  of  which  is  at  the 
costo-central  joint. 


•l.  THE  ARTICULATIONS  AT  THE  FRONT  OF  THE  THORAX 

These  may  be  divided  into  four  sets,  viz. : — 

(a)  The  intersternal  joints,  or  the  union  of  the  several  parts  of  the  sternum 
with  one  another. 

(b)  The  costo-chondral  joints,  or  tlie  union  of  the  ribs  with  their  co.stal 
cartilages. 

(c)  The  chondro-sternal  articulations,  or  the  junction  of  the  costal  cartilages 
with  the  sternum. 

(d)  The  interchondral  joints,  or  tlie  union  of  five  costal  cartilages  (sixth, 
seventh,  eightfi,  ninth,  and  tenth)  with  one  another. 

(a)  The  Intersternal  Joints,  or  the  Union  of  the  Segments  of  the  Sternum 

WITH  ONE  another 

The  sternum  being  composed,  in  the  adult,  of  three  distinct  jneces, — the  manu- 
brium, the  gladiolus  or  body,  and  the  xiphoid. — has  two  articulations,  viz.,  the 
Superior,  Avhich  unites  the  manubrium  with  the  gladiolus,  and  tlie  Inferior,  which 
unites  the  gladiolus  with  the  xiphoid. 


212  THE  ARTICULATIONS 

1.  The  Superior  Intersternal  Articulation. 

Class.  — A  mph  iai'throsls. 

The  lower  border  of  the  manubrium  and  the  upper  border  of  the  body  of 
the  sternum  present  oval-shaped,  tlat  surfaces,  with  their  Ions  axes  transverse,  and 
covered  with  a  thin  layer  of  hyaline  cartilage.  An  interosseous  fibro-cartilage 
is  interposed  between  the  bony  surfaces:  it  corresponds  exactly  in  shape  and  inti- 
mately adlieres  to  them.  At  each  lateral  border  this  fibro-cartilage  enters  into  the 
formation  of  the  second  chondro-sternal  articulation  (fig.  217).  In  consistence  it 
varies,  being  in  some  cases  uniform  throughout,  in  others  softer  in  the  centre  than 
at  the  circumference,  and  in  others  again  an  oval-shaped  synovial  cavity  is  found 
towards  its  anterior  part.  When  such  a  ca^dty  exists  in  the  fibro-cartilage  this 
joint  has  a  remote  resemblance  to  the  diarthrodes,  and  is  classed,  with  the  sacro-iliac 
joint  and  the  symphysis  pubis  under  similar  conditions,  as  '  diarthro-amphi- 
arthrosis. ' 

The  periosteum  passes  uninterruptedly  over  the  joint  from  one  segment  of 
the  sternum  to  the  other,  forming  a  kind  of  capsular  ligament.  This  capsule  is 
strengthened,  especially  on  its  posterior  aspect,  by  longitudinal  ligamentous  fibres 
as  well  as  by  the  radiating  and  decussating  fibres  of  the  chondro-sternal  ligaments. 

In  some  instances  the  fibro-cartilage  is  replaced  by  short  bundles  of  fibrous 
tissue  which  unite  the  cartilage-coated  articular  bony  surfaces. 

2.  The  Inferior  Intersternal  Articulation. 

Class. — Syncirthrosis. 

The  gladiolus  is  joined  to  the  xiphoid  cartilage  by  a  thick  investing  membrane, 
by  anterior  and  posterior  longitudinal  fibres,  and  by  radiating  fibres  of  the  sixth 
and  seventh  chondro-sternal  ligaments.  The  chondro-xiphoid  ligament  also 
connects  the  xiphoid  with  the  anterior  surface  of  the  sixth  and  seventh  costal 
cartilages,  and  thus  indirectly  Avith  the  gladiolus;  and  some  fine  fibro-areolar 
tissue  also  connects  the  xiphoid  with  the  back  of  the  seventh  costal  cartilage. 

The  junction  of  the  xiphoid  with  the  sternum  is  on  a  level  somewhat  posterior 
to  the  junction  of  the  seventh  costal  cartilage  with  the  sternum.  The  union  is 
synarthrodial. 

{h)  The  Costo-chondral  Joints 

Class . — Syna  rth  rosis. 

The  extremity  of  the  costal  cartilage  is  received  into  a  cup-shaped  depression 
at_  the  end  of  the  rib,  which  is  somewhat  larger  than  the  cartilage.  The  two  are 
joined  together  by  the  continuity  of  the  investing  membranes,  the  periosteum  of 
the  rib  being  continuous  with  the  perichondrium  of  the  cartilage,  much  in  the  same 
way  as  the  epiphyses  of  the  bones  are  joined  to  their  shafts. 


(c)  The  Chonduo-sternal  Articulatioxs 

Class. — Diarthrost)^.  Subdivision. — (linglymits. 

Tlu'se  articulations  are  ])etween  the  lateral  borders  of  the  sternum  and  tlie  ends 
of  the  costal  cartilages.  The  union  of  the  first  rib  with  the  sternum  is  synarthrodial, 
and  tlierefore  forms  an  exception  to  the  others.  From  the  second  to  the  seventh 
inclusive,  the  articulations  have  the  following  ligaments,  which  together  form  a 
complete  capsule:— 

Anterior  chondro-sternal.  Superior  chondro-sternal. 

Posterior  chondro-sternal  Inferior  chondro-sternal. 


OF  THE  STERNUM 


213 


The  anterior  chondro-sternal  ligament  (fig.  217)  is  a  triangular  band  of 
strong  fibres  which  cover  the  inner  half-inch  of  the  front  of  the  costal  cartilage, 
and  radiate  upwards  and  downwards  upon  the  front  of  the  sternum.  8onie  of  the 
fibres  decussate  across  the  middle  line  with  fibres  of  the  opposite  ligament.  At  its 
upper  and  lower  borders  it  is  in  contact  with'the  superior  and  inferior  ligaments 
respectively. 

Fig.  217. — The  Sternuji. 
(Left  side,  showing  ligaments  ;  right  side,  the  synovial  cavities.) 


An  interartieular 
ligament 


The  plate  of  flbro- 
eartilage  between 
manubrium  and 
meso-steruum 


FOURTH  RIB  "*^^S^'' 


Interchoudral 
capsular  ligament 


The  posterior  chondro-sternal  ligament  consists  of  little  more  than  a  thick- 
ening of  the  fibrous  envelopes  of  the  bone  and  cartilage,  the  jciint  being  completed 
l)ehind  l)y  a  continuity  of  pericliondrium  with  periosteum. 

The  superior  and  inferior  ligaments  are  strong,  well-marked  bands,  which 
pass  from  the  up])er  and  lower  borders  resj^ectively  of  the  costal  cartilage  to 
the  lateral  edges  of  the  sternum.     The  sixth  and  seventh  cartilages  are  so  close 


214  THE  ARTICULATIONS 

that  tlu"  superior  ligament  of  the  seventli  is  blended  with  the  inferior  of  the 
sixth  rib. 

Dee])er  than  the  fibres  of  these  ligaments  are  short  fibres  passing  from  the  mar- 
gins of  the  sternal  facets  to  the  edges  of  the  facets  on  the  cartilages;  they  are  most 
distinct  in  the  front  and  lower  part  6f  the  joint,  and  may  encroach  so  much  upon 
the  synovial  cavity  as  to  reduce  it  to  a  very  small  size,  or  almost  obliterate  it.  This 
occurs  mostly  in  the  case  of  the  sixth  and  seventh  joints,  especially  the  latter. 

The  interarticular  ligament  (fig.  217)  is  by  no  means  constant,  but  is  usually 
present  in  the  second  joint  on  one,  if  not  on  both  sides  of  the  same  subject.  It 
consists  of  a  strong  transverse  l)undle  of  fibres  passing  from  the  ridge  on  the  facet 
on  the  cartilage  to  the  symphysial  substance  between  the  manuljrium  and  body; 
sometimes  the  upper  part  of  the  synovial  cavity  is  partially  or  entirely  obliterated 
by  short,  tine,  ligamentous  fibres. 

The  chondro-xiphoid  ligament  (fig.  217)  is  a  strong  fiat  band  of  fibres  passing 
obliqu(4y  upwards  and  outwards  from  the  front  surface  of  the  xiphoid  cartilage  to 
the  anterior  surface  of  the  sternal  end  of  the  seventh  costal  cartilage,  and  most 
frequently  to  that  of  the  sixth  also. 

Synovial  membranes. — The  union  of  the  first  cartilage  with  the  sternum  being 
synarthrodial,  it  has  no  synovial  membrane;  the  second  has  usually  two,  separated 
l)y  the  interarticular  ligament.  The  rest  usually  have  one  synovial  membrane, 
which  may  occasionally  be  subdivided  into  tAvo  (fig.  217). 

The  arterial  supply  is  derived  from  perforating  branches  of  the  internal  mam- 
mary; and  the  nerves  come  from  the  anterior  branches  of  the  intercostals. 

Movements. — Excepting  the  first,  the  chondro-sternal  joints  are  ginglymoid, 
l)ut  the  motion  of  which  they  are  capable  is  very  limited.  It  consists  of  a  hinge- 
like action  in  two  directions:  first,  there  is  a  slight  amount  of  elevation  and  depres- 
sion Avhich  takes  place  round  a  transverse  axis,  and,  secondly,  there  is  some  forward 
and  backward  movement  round  an  obhquely  vertical  axis.  In  inspiration  the 
cartilage  is  elevated,  and  the  lowest  part  of  its  articular  facet  is  pressed  into  the 
sternal  socket,  and  the  sternum  is  thrust  forwards  so  that  the  upper  and  front  edges 
of  the  articular  surfaces  separate  a  little;  in  expiration  the  reverse  movement  takes 
]ilace.  Thus  the  two  extremities  of  the  costal  arches  move  in  their  respective 
sockets  in  opposite  directions. 

This  difference  results  necessarily  from  the  fact  that  the  costal  arch  moves  upon 
the  vertebral  column,  and,  having  been  elevated,  it  in  its  turn  raises  the  sternum 
by  pushing  it  upwards  and  forwards. 

The  chondro-xiphoid  ligament  tends  to  prevent  the  xiphoid  cartilage  from 
V)eing  drawn  backwards  l»y  tlie  action  of  the  diaphragm. 


{(l)  The  Intekchondrai.  Aktktlations 
Class. — 1)1(1  rf/irosis.  Subdivision. — Artlirudia. 

A  little  in  front  of  the  point  where  the  costal  cartilages  bend  ui)\var(ls  towards 
the  median  line,  the  sixth  is  united  with  the  seventh,  the  seventh  with  the  eighth, 
the  eighth  with  the  ninth,  and  the  ninth  with  the  tenth. 

At  this  point,  each  of  the  cartilages  from  the  sixth  to  the  ninth  inclusive  is 
deeper  than  elsewhere,  owing  to  the  projection  downwards  from  its  lower  edge  of  a 
broad  blunt  process,  which  comes  into  contact  with  the  cartilage  next  In-low.  Each 
of  the  ai)i)Osed  surfaces  is  smooth,  and  they  arc  connected  at  tlieir  margins  bv  liga- 
mentous tissue,  which  forms  a  comjilete  capsule  for  the  articulation,  and  is  lined 
by  a  synovial  membrane  (fig.  217).  The  largest  of  these  cavities  is  between  the 
seventh  and  eighth;  tliose  between  the  eighth  and  ninth,  and  ninth  and  tenth,  are 
smaller,  and  are  not  free  to  ].lay  upon  each  other  in  the  whole  of  their  extent, 
being  held  together  by  ligamentous  tissue  at  their  anterior  margins.  Sometimes 
this  fi])rous  tissue  completely  obliterates  the  synovial  cavity. 

The  arteries  are  derived*  from  the  muscuio-jihrenic,  and  the  nerves  from  the 
intercostals. 

Movements.— Ky  means    of   the  costal    cartilages    and    intcnhondral    joints. 


MOVKMKXTS   OF  THE   THORAX  AS  A    WHOLE  215 

strength  witli  elasticity  is  given  to  the  wall  of  the  trunk  at  a  part  where  the 
cartilages  are  the  only  firm  structures  in  its  composition;  while  a  slight  gliding 
movement  is  permitted  hetween  the  costal  cartilages  themselves,  which  takes  place 
round  an  axis  corresponding  to  the  long  axis  of  the  cartilages.  By  this  means, 
the  outAvard  projection  of  the  lower  }nirt  of  the  thoracic  Avail  is  increased  by 
deep  inspiration. 


MOVEMENTS  OF  THE  THORAX  AS  A  AVHOLE 

Before  describing  these  movements  as  a  Avhole,  it  must  be  premised  that  there 
are  some  feAV  modifications  in  the  movements  of  certain  ribs  resulting  from  their 
shape.  Thus  the  first  rib  (and  to  a  less  extent  the  second  also),  which  is  flat  on  its 
upper  and  under  surfaces,  revolves  on  a  transverse  axis  drawn  through  the  costo- 
vertebral and  costo-transverse  joints.  During  inspiration  and  ex])iration,  the  anterior 
extremities  of  the  first  pair  of  costal  arches  play  up  and  down,  the  tubercles  and 
the  heads  of  the  ribs  acting  in  a  hinge-like  manner,  the  latter  having  also  a  slight 
screwing  motion.  By  this  movement  the  anterior  ends  of  the  costal  arches  are 
simply  raised  or  depressed,  and  the  sternum  pushed  a  little  forwards:  it  may  be 
likened  to  the  movement  of  a  pump-handle,  as  in  fig.  218,  «,  b. 

The  movements  of  the  other  ribs,  particularly  in  the  mid-region  of  the  thorax, 
are  more  complex,  for,  besides  the  elevation  of  the  anterior  extremities,  the  bodies 

Fig.  218. — Di.\GKA>r  of  Axis  ok  Kib-movemext.     (After  Kirkes.) 


and  angles  of  the  ribs  rise  nearly  as  much  as  the  extremities  themselves.  In  this 
movement  the  tubercles  of  the  ribs  glide  upwards  and  backwards  in  inspiration, 
and  downwards  and  forwards  in  expiration;  and  the  movement  may  be  likened  to 
that  of  a  bucket  handle,  as  in  fig.  218,  A,  B. 

During  inspiration,  the  cavity  of  the  thorax  is  increased  in  every  direction. 
The  antero-posterior  diameter  is  increased  by  the  thrusting  forwards  of  the 
sternum,  caused  by  the  elevation  of  the  costal  cartilages  and  fore  part  of  the  ribs, 
whereby  they  are  brought  to  nearly  the  same  level  as  the  heads  of  the  ribs.  The 
transverse  diameter  is  increased:  (i)  Behind,  by  the  elevation  of  the  middle  part 
of  the  rib.^;  for  when  at  rest  the  mid-part  of  the  rib  is  on  a  lower  level  than  either 
the  costo-vertebral  or  chondro-sternal  articulations.  Owing  to  this  obliquity  the 
transverse  diameter  is  increased  when  the  rib  is  raised,  and  the  increase  is  propor- 
tionate to  the  degree  of  oljliquity.  (ii)  By  the  eversion  of  the  lower  border  of  the 
costal  arch,  which  rolls  outwards  as  the  arch  is  raised,  (iii )  The  transverse  diameter 
is  increased  in  fi-ont  by  the  abduction  of  the  anterior  extremity  of  the  rib  at  the 
same  time  as  it  is  elevated  and  thrust  forwards. 

The  increase  in  the  vertical  diameter  of  the  thorax  is  due  to  the  elevation  of 
the  riljs,  especially  the  upper  ones,  and  the  consequent  widening  of  the  intercostal 
spaces;  but  the  chief  increase  in  this  direction  is  due  to  the  descent  of  the 
diaphragm. 

The  greatest  increase  both  in  the  antero-posterior  and  transverse  diameters  takes 
place  where  the  ribs  are  longest,  most  oblique,  and  most  curved  at  their  angles,  and 


21(5  THE  ARTICULATIONS 

where  the  bulkiest  part  of  the  hing  is  enclosed.  This  is  (jn  a  level  with  the  sixth, 
seventh,  and  eighth  rihs. 

At  the  lower  part  of  the  thorax,  where  the  ribs  have  no  relation  to  the  lungs,  and 
do  not  affect  respiration  directly  V)y  their  movements,  it  is  important  that  the  costal 
arches  should  l)e  thrown  well  outwards  in  order  to  counteract  the  compression  of 
the  abdominal  viscera  l)y  the  contraction  of  the  diaphragm. 

By  widening  and  steadying  the  lower  part  of  the  thorax  during  inspiration,  the 
attachments  of  the  muscular  fibres  of  the  diaphragm  are  widened,  and  their  power 
increased. 


THE  ARTICULATIONS  OF  THE  UPPER  EXTREMITY 

The  articulations  of  the  upper  extremity  are  the  following: — 

1.  The  sterno-costo-clavicular. 

2.  The  scapulo-clavicular  union. 

3.  The  shoulder-joint. 

4.  The  elbow-joint. 

5.  The  radio-ulnar  union. 

6.  The  radio-carpal  or  wrist-joint. 

7.  The  carpal  joints. 

8.  The  carpo-metacarpal  joints. 

9.  The  intermetacarpal  joints. 

10.  The  metacarpo-phalangeal  joints. 

11.  The  interphalangeal  joints. 

1.  THE  STERNO-COSTO-CLAVICULAR  ARTICULATION 

Class. — I)  I  arthrosis.  Subdivision. — Sad  die- shaped  Arthrodia. 

At  this  joint  the  large  iimer  end  of  the  clavicle  is  united  to  the  superior  angle 
of  the  manubrium  sterni,  the  first  costal  cartilage  also  assisting  to  support  the 
clavicle.  It  is  the  only  joint  between  the  up})er  extremity  and  the  trunk,  and  takes 
part  in  all  the  movements  of  the  upper  lind).  Looking  at  the  bones,  one  wouhl 
say  that  they  were  in  no  way  adapted  to  articulate  with  one  another,  and  yet  the}' 
assist  in  constructing  a  joint  of  great  security,  strength,  and  importance.  The 
bones  are  nowhere  in  actual  contact,  being  completely  separated  by  an  inter- 
articular  cartilage.  The  interval  Ix'tween  the  joints  of  the  two  sides  varies  from 
one  inch  to  an  inch  and  a  half  (2-5-4  cm.).     The  ligaments  of  this  joint  are: — 

(1)  Capsular.  (3)  Interarticular  fibro-cartilage. 

(2)  Interclavicular.  (4)   Rhoml)oid  or  costo-clavicular. 

The  capsular  ligament  (figs.  219  and  220)  consists  of  fibres,  having  varying 
directions  and  l)cing  of  various  strength  and  thickness,  which  comi)letely  surround 
the  articulation,  and  are  firndy  connected  with  the  edges  of  the  interarticular  fil)ro- 
cartilage.  The  fibres  at  the  back  of  the  joint,  sonietimes  styled  the  posterior 
sterno-clavicular  ligament,  are  stronger  than  those  in  front  or  below,  and  consist 
of  two  sets:  a  su])crficial,  passing  upwards  and  outwards  from  the  manubrium 
sterni,  to  the  i)rojccting  jjosterior  edge  of  the  inner  end  of  the  clavicle,  a  few 
being  prolonged  onwards  ui)on  the  i)osterior  surface  of  the  bone.  A  deeper  set  of 
fibres,  especially  thick  and  numerous  below  the  clavicle,  connect  the  interarticular 
cartilage  with  the  clavicle  and  with  the  sternum,  but  do  not  extend  from  one  lione 


THE  STERNO-COSTO-CLA  VICULAR 


217 


to  the  other.  The  fibres  m  front,  the  anterior  sterno-clavicular  ligament,  are 
well  marked,  but  more  lax  and  less  tough  than  the  posterior,  and  are  overlaid  by 
the  tendinous  sternal  origin  of  the  sternu-madoid,  the  fibres  of  which  run  parallel 
to  those  of  the  ligament.  They  extend  obliquely  upwards  and  outwards  from  the 
margin  of  the  sternal  facet  to  the  anterior  surface  of  the  cla^dcle  some  little  distance 
from  the  articular  margin.     The  fibres  which  cover  in  the  joint  below  are  short. 

Fig.  219. — Posterior  View  of  the  STERXO-cosTO-CLAVicrLAR  Joint. 


Avoolly,  and  consist  more  of  fibro-areolar  tissue  than  true  fibrous  tissue;  they 
extend  from  the  upper  border  of  the  first  costal  cartilage  to  the  lower  border  of  the 
clavicle  just  external  to  the  articular  margin,  and  fill  up  the  gap  between  it  and  the 
rhomboid  ligament.  The  superior  portion  consists  of  short  tough  fibres  passing 
from  the  sternum  to  the  interarticular  cartilage;  and  of  others  welding  the  fil:)ro- 


FiG.  220. — Anterior  View  of  Sterno-costo-clavicular  Joint. 

(The  capsule  is  cut  into  on  the  left  side  to  show  the  interarticular  fibro-cartilage  dividing  the 

joint  into  two  cavities.) 


Khomboid 
ligament 
Anterior 
sterno- 
clavicular 
ligament 


cartilage  to  the  upper  edge  of  the  clavicle,  only  a  few  of  them  passing  from  the 
clavicle  direct  to  the  sternum. 

The  interclavicular  ligament  (figs.  219  and  220)  is  a  strong,  concave  band, 
materially  strengthening  the  superior  portion  of  the  capsule.  It  is  nearly  a  quarter 
of  an  inch  (6  mm.)  deep,  with  the  concavity  upwards,  its  upper  border  tapering  to 
a  narrow,  almost  sharp  edge.      It  is  connected  with  the  posterior  superior  angle  of 


218 


THE  ARTICULATIONS 


the  sttTiial  extremity  of  each  clavicle,  and  with  the  fibres  which  weld  the  inter- 
articular  cartilage  with  the  clavicle;  and  then  passes  across  from  clavicle  to  clavicle 
along  the  }»osterior  asi)eet  of  the  iip]ier  border  of  the  manubrium  sterni.  The 
lowest  fibres  are  attached  to  the  sternum,  and  join  the  posterior  fibres  of  the  capsule 
of  each  joint.  In  the  middle  line  between  the  ligament  and  the  sternum  there  is 
an  aperture  for  tlie  i)assage  of  a  small  artery  and  vein. 

The  rhomboid  or  costo-clavicular  ligament  (figs.  219  and  220)  is  a  strong 
dense  band,  composed  of  fine  fibres  massed  together  into  a  membranous  structure. 
It  extends  from  the  anterior  edge  of  the  upper  border  of  the  first  costal  cartilage, 
upwards,  backwards,  and  distinctly  outwards  to  the  rhomboid  impression  on  the 
\mder  surface  of  the  inner  extremity  of  the  clavicle,  to  which  it  is  attached  just 
external  to  the  lower  part  of  the  capsule.  Freciuently  some  of  the  outer  fibres  i)ass 
upwards  and  inwards  behind  the  rest,  and  give  the  appearance  of  decussating.  It 
is  from  half  to  three-({uarters  of  an  inch  (1-5-2  cm.)  broad. 

The  interarticular  fibro-cartilage  (figs.  220  and  221)  is  a  flattened  disc  of 
nearly  the  same  size  and  outline  as  the  inner  articular  end  of  the  clavicle,  which  it 
fairly  accurately  fits.  It  is  attached,  above  to  the  upper  border  of  the  posterior 
edge  of  the  clavicle;  and  below  to  the  cartilage  of  the  first  rib  at  its  union  with  the 


Fro.  221. — Section  through  Stekko-clavici'lar  .Joint. 


The  interarticular 
flbro-eartilage 


The  joint  between 
the  sternum  and 
second  costal  car- 
tilage 


Sternum,  where  it  assists  in  forming  the  socket  for  the  clavicle.  At  its  circum- 
ference it  is  connected  with  the  capsular  ligament,  and  this  connection  is  very 
strong  behind,  and  still  stronger  above  where  it  is  blended  Avith  the  interclavicular 
ligament.  It  is  usually  thinnest  below,  where  it  is  connected  with  the  costal 
cartilage.  It  varies  in  thickness  in  different  parts,  sometimes  being  thinner  in  the 
centre  than  at  the  circumference,  sometimes  the  reverse,  and  is  occasionally  per- 
forated in  the  centre.      It  divides  the  joint  into  two  compartments. 

There  are  two  synovial  membranes  (figs.  220  and  221):  an  outer  one,  Avhich 
is  reflecti-d  from  the  clavicle  and  cajisule  over  the  outer  side  of  the  fibro-cartilage, 
and  is  looser  than  the  inner;  the  inner  is  reflected  from  the  sternum  over  the  inner 
side  of  the  fibro-cartilage,  costal  cartilage,  and  capsule.  Occasionally  a  connnuni- 
cation  takes  ](lai-e  lictween  tlieni. 

The  arterial  supply  is  derived  from  branches  (l)  from  the  internal  niammarv; 
(2)  from  the  su]..'ri(.r  thf)raeic  branch  of  the  axillary;  (3)  twigs  of  a  muscul'ar 
branch  often  arising  from  the  subclavian  artery  pass  over  the  interclavicular 
notcli;   (4)  twigs  of  the  suprascapular  artery. 

The  nerve-supply  is  derived  from  the  nerve  to  the  suhdavins  and  sternal 
descending  liranch  of  the  cervical  plexus. 

The  movements  permitted  at  this  joint  are  various,  though  limited  owing  to 
the  capsular  ligament  being  iiKjderately  tense  in  every  position  of   the  clavicle. 


THE  SCAPULO-CLAVICULAR  219 

Motion  takes  place  in  nearly  every  direction — viz.  upwards,  downwards,  forwards, 
backwards,  and  in  a  circuniductory  manner.  The  upward  and  downward  motions 
occur  between  the  clavicle  and  the  fibro-cartilage;  during  elevation  of  the  arm,  the 
upper  edge  of  the  clavicle  with  its  attached  fibro-cartilage  is  pressed  into  the  sternal 
S(jcket,  and  the  lower  edge  glides  away  from  the  cartilage;  during  depression  of  the 
limb,  the  lower  edge  of  the  clavicle  presses  on  to  the  cartilage,  while  the  rest  of  the 
articular  surface  of  the  clavicle  inclines  outwards,  Ijringing  with  it  to  a  slight 
degree  the  upper  edge  of  the  fibro-cartilage.  These  movements  occur  on  an  antero- 
posterior axis  drawn  through  the  outer  compartment  of  the  joint.  The  forward 
and  backward  motions  take  place  Ijetween  the  cartilage  and  sternum,  the  clavicle 
Avith  the  cartilage  rolling  Ijackwards  upon  the  sternum  when  the  shoulder  is 
brought  forwards,  and  forwards  when  the  shoulder  is  ftn-ced  backwards;  these 
iuovements  occur  round  an  axis  drawn  nearly  vertically  through  the  sternal  socket. 
The  interarticular  cartilage  serves  materially  to  l)ind  the  bones  together,  and  to 
prevent  the  inward  and  upward  displacements  of  the  clavicle.  It  also  forms  an 
elastic  buffer  which  tends  to  break  shocks.  The  capsule,  by  being  moderately 
tight,  tends  to  limit  movements  in  all  directions,  while  the  interclavicular  ligament 
is  a  safeguard  against  upward  displacement  during  depression  of  the  arm.  The 
rhomboid  ligament  prevents  dislocation  upwards  during  elevation  of  the  arm,  and 
resists  displacements  backwards. 


(2)  THE  SCAPULO-CLAVICULAR  UXIOX 

The  scapula  is  connected  with  the  clavicle  by  a  synovial  joint  Avith  its  liga- 
ments; and  also  l;)y  a  set  of  ligaments  passing  betw^een  the  coracoid  process  and  the 
clavicle.     So  that  we  have  to  consider — 

(a)  The  acromio-clavicular  articulation. 

(b)  The  coraco-clavicular  ligaments. 

(r)  Tlic  proper  scapular  ligaments  are  also  best  described  in  this  section — 
viz.  the  coraco-acromial  and  transverse. 


(a)  The  Ackomio-clavktlar  .Ioint 
Class. — DinrtJtrosi^.     Subdivision. — Arthrodia. 

The  acromio-clavicular  joint  is  surrounded  by  a  capsular  ligament  and  fre- 
quently contains  an  interarticular  fibro-cartilage. 

The  capsular  ligament  (figs.  223  and  226)  completely  surrounds  the  articular 
margins,  and  is  C(jmposed  of  strong,  coarse  fibres  arranged  in  parallel  fasciculi,  of 
fairly  uniform  thickness,  which  are  attached  to  the  borders  as  well  as  the  surfaces 
of  the  bones.  It  is  somewhat  lax  in  all  positions  of  the  joint,  so  that  the  clavicle 
is  not  tightly  braced  to  the  acromion.  The  fibres  extend  three-quarters  of  an  inch 
(2  cm.)  along  the  clavicle  posteriorly,  but  only  a  c[uarter  of  an  inch  (6  mm.) 
anteriorly.  Superiorly,  they  are  attached  to  an  obli(iue  line  joining  these  two 
points,  while  inferiorly  they  reach  to  the  ridge  for  the  trapezoid  ligament  with 
which  they  blend.  At  the  acromion  they  extend  half  Avay  across  the  upper  and 
lower  surfaces,  but  at  the  anterior  and  posterior  borders  of  that  process  they  are 
attached  close  to  the  articular  facet.  The  anterior  fibres  become  blended  with 
the  insertion  of  the  coraco-acromial  ligament.  The  fibres  are  strengthened  above 
by  the  aponeuroses  of  the  trapezius  and  rJrJtold  muscles;  and  all  run  from  the 
acromion  to  the  clavicle  inwards  and  liackwards. 

The  interarticular  fibro-cartilage  is  occasionally  present,  but  is  i;sually  im- 
perfect, only  occui)ying  the  upper  jKirt  of  the  joint;  it  may  completely  divide  the 
joint  into  two  cavities,  or  be  perforated  in  the  centre.  It  is  usually  thicker  at  the 
edge  than  in  the  centre,  and  some  of  the  fibres  of  the  capsular  ligament  are  blendi  d 
with  its  edges. 

The  synovial  membrane  lining  the  joint  is  occai^ionally  either  partially  or 
entirely  divided  into  two  Ijy  an  interarticular  fibro-cartilage. 


220 


riiE  AirriciLATioxs 


(h)  The  C'oKAco-CLAVJcuLAii  Umon 

Till-  coraco-clavicular  ligament  (figs.  222,  223  and  226)  consists  of  two  parts, 
the  conoid  and  X\iv  trapezoid  ligaments. 

The  conoid  ligament  is  the  internal  and  posterior  portion,  and  passes  upwards 
and  outwards  from  the  coracoid  process  to  the  clavicle.  It  is  a  very  strong  and 
coarsely  fasciculated  band  of  triangular  shape,  the  apex  being  fixed  to  the  inner  and 
posterior  edge  of  the  root  of  the  coracoid  process  just  in  front  of  the  suprascapular 
notch,  some  fibres  joining  the  transverse  ligament.  Its  base  is  at  the  clavicle, 
wliere  it  widens  out,  to  be  attached  to  the  posterior  edge  of  the  under  surface,  as 
well  as  to  the  conoid  tubercle.  It  is  easily  separated  from  the  trapezoid  without 
being  al)S()lutely  distinct.  A  small  bursa  often  exists  between  it  and  the  coracoid 
process;  internally,  some  of  the  fibres  of  the  svbdavius  muscle  are  often  attached 
to  it. 

The  trapezoid  ligament  is  the  anterior  and  outer  portion.      It  is  a  strong,  flat, 


Fig.  222. — Anterior  View  of  Shoulder,  showing  also  Coraco-clavicular  and 
cokaco-acromial  ligaments. 

Conoid  ligament 

Transverse  scapular  ligament     wIl      8  / 

jB&\     \/     Tiapezoid  ligament 

Coraeo-aeromial  ligament 


Short  head  of  biceps 
Subscapular  tendon 


Capsule  of  shoulder 


Long  tendon  of 
biceps 


•  luadrilateral  ])lane  of  closely-woven  fil)res,  the  surfaces  of  which  look  ui)wartls  and 
inwards  towards  the  clavicle,  and  downwards  and  outwards  over  the  upper  surface 
of  the  coracoid  i)rocess.  At  the  coracoid  it  is  attached  for  about  an  inch  (2*5  cm. ) 
to  a  rough  ridge  which  runs  forwards  from  the  angle,  along  the  anterior  border  of 
the  process.  At  the  clavicle,  it  is  attached  to  the  ol^lique  ridge  Avhich  runs  out- 
wards and  forwards  from  the  conoid  tul)ercle,  reaching  as  far  as,  and  blending  with 
the  inferior  part  of  the  acromio-clavicular  ligament.  Its  anterior  edge  is  free,  and 
overlies  the  coraeo-aeromial  ligament;  the  posterior  edge  is  shorter  than  the  anterior, 
and  is  in  contact  with  the  posterior  and  outer  ])ortion  of  the  conoid  ligament. 

Tlie  arterial  supply  is  derived  from  the  su])rascaiHdar,  acromial  branches  of 
the  aeromio-tlioracic,  and  the  anterior  circumflex. 

The  nerve-supply  is  derived  from  the  suprascapular  and  circumflex  nerves. 

Movements. — In  the  movements  of  the  shoulder  girdle,  the  scapula  moves 
U[)on  the  outer  end  of  the  clavicle,  and  the  clavicle,  in  turn,  carried  bv  the  uniting 


THE  SCAPULO-CLAVICULAR  221 

ligaments,  moves  upon  the  sternum;  so  that  the  entire  scapula  moves  in  the  arc  of 
a  circle  whose  centre  is  at  the  sterno-clavicular  joint,  and  Avhose  radius  is  the 
clavicle.  The  scai)ula,  in  moving  upon  the  clavicle,  also  moves  upon  the  thorax 
forwards  and  backwards,  upwards  and  downwards,  and  also  in  a  rotatory  direction 
upon  an  axis  drawn  at  right  angles  to  the  centre  of  the  bone.  Throughout  these 
luovemonts  the  lower  angle  and  base  of  the  scapula  are  kept  in  contact  with  the 
ribs  l)y  the  latisslinus  dorsl  which  straps  down  the  former,  and  the  rhomboids  and 
serratus  viarjnus  which  brace  down  the  latter.  The  glenoid  cavity  could  not  have 
preserved  its  obliijucly  forward  direction  had  there  been  no  acromio-clavicular 
joint,  ])ut  would  have  shifted  round  a  vertical  axis,  and  thus  the  shoulder  Avould 
have  pointed  inwards  when  the  scapula  w^as  advanced,  and  outwards  when  it  was 
drawn  backwards.  By  means  of  the  acromio-clavicular  joint,  the  scapula  can  be 
forcibly  advanced  upon  the  thorax,  the  glenoid  cavity  all  the  time  keeping  its  face 
duly  forwards.  Thus  the  muscles  of  the  shoulder  and  forearm  can  be  with  advan- 
tage combined,  as,  for  example,  in  giving  a  direct  blow.  The  acromio-clavicular 
joint  also  permits  the  lower  angle  of  the  scapula  to  be  retained  in  contact  with  the 
chest  wall  during  the  rising  and  falling  of  the  shoulder,  the  scapula  turning  in  a 
hinge-like  manner  round  the  horizontal  axis  of  the  joint. 

There  are  no  actions  in  which  the  scapula  moves  on  a  fixed  clavicle,  or  the 
clavicle  on  a  fixed  scapula;  the  two  bones,  bound  together  by  their  connecting 
ligament,  must  move  in  unison. 


(c)  The  Proper  Scapular  Ligaments 

There  are  three  proper  ligaments  of  the  scapula,  which  pass  between  different 
portions  of  the  bone,  viz. — 

Coraco-acromial.  Transverse. 

Inferior  transverse. 

The  coraco-acromial  ligament  (figs.  222  and  226)  is  a  flat,  triangular  band 
with  a  l)road  base,  attached  to  the  outer  border  of  the  coracoid  process,  and  a  lilunt 
a])ex  which  is  fixed  to  the  tip  of  the  acromion.  It  is  made  up  of  two  broad  marginal 
l)ands,  and  a  smaller  and  thinner  intervening  portion.  The  anterior  band,  which 
arises  from  the  anterior  portion  of  the  coracoid  process,  is  the  stronger,  and  some  of 
its  marginal  fibres  can  often  be  traced  into  the  short  head  of  the  l:)iceps,  which  can 
then  make  tense  this  edge  of  the  ligament.  The  posterior  band,  coming  from  tlie 
posterior  part  of  the  coracoid  process,  is  also  strong.  The  intei-mediate  part,  of 
variable  extent,  is  thin  and  membranous,  containing  but  few  ligamentous  fibres;  it 
is  often  incomplete  near  the  coracoid  process,  leaving  a  small  gap  (fig.  222).  The 
su]ierior  surface  of  the  ligament  looks  upwards  and  a  little  forwards,  and  is  covered 
l»y  the  deltoid  muscle;  the  inferior  looks  downwards  and  a  little  backwards,  and  is 
separated  from  the  capsule  of  the  shoulder-joint  by  a  bursa.  At  the  coracoid 
l)rocess  it  overlies  the  coraco-humeral  ligament.  It  is  barely  one-third  of  an  inch 
(8  mm. )  above  the  capsule  of  the  shoulder,  and  in  the  undissected  state  there  is 
scarcely  a  quarter  of  an  inch  (6  mm.)  interv^al.  The  anterior  band  projects  over 
the  centre  of  the  head  of  the  humerus,  and  is  continued  into  a  tough  fascia  under 
the  deltoid;  the  posterior  band  is  continuous  with  the  fascia  over  the  supra-spinatus 
muscle.  It  binds  the  two  processes  firmly  together,  and  so  strengthens  each;  it 
holds  the  deltoid  off  the  capsule  of  the  shoulder,  and  protects  the  joint  from  slight 
injuries  directed  downwards  and  backwards  against  it. 

The  transverse,  coracoid,  or  suprascapular  ligament  (figs.  222,  223  and 
224)  is  a  small  triangular  band  of  fibrous  tissue,  the  surfaces  of  which  look  forwards 
and  l)ackwards;  and  its  edges,  which  are  thin  and  sharp,  are  turned  upwards  and 
downwards.  It  continues  the  superior  border  of  the  scapula,  l)ridging  over  the 
suprascapular  notch.  It  is  broader  internally,  Avhere  it  springs  from  the  upper 
border  of  the  scapula  on  its  dorsal  surface;  and  narrow  externally,  where  it  is 
attached  to  the  base  of  the  coracoid  process;  some  of  its  fibres  are  inserted  under 
the  edge  of  the  trapezoid  ligament,  and  others  pass  upwards  with  the  conr)id  to 


2_>2  THE  AirricrLATJOXS 

reach  the  I'lavicle.      The  mijirasrapiddr  arter;/  pasties  over  it,  and  the  .wpni.scapular 
nerve  Ixmeath  it.      Internally,  some  fibres  of  the  omo-hyoid  muscle  arisi;  from  it. 

The  inferior  transverse  or  spino-glenoid  ligament  (tig.  228)  reaches  from 
the  external  border  of  the  si)ine  of  the  scapula  to  the  margin  of  the  glenoid  cavity, 


Fui.  22:5. — PosTKKioR  View  of  the  Shoulder-joint,  showing  also  the  Ackomio- 

CLAVICLLAK   JolXT   AND  THE   SPECIAL   LiGAMEXTS   OF  THE  SCAPl'LA. 

Transverse  ligament 


Conoid  ligament 


Acromio-clavicular  - 
ligament 


Tendon    of     infra- 
spinatus and  teres         /^ 


Inferior  transverse 
or  spino-glenoid 
ligament 
Capsule  of  shouldei- 


and  so  forms  a  foramen  imder  which  the  suprascapular  vessels  and  nerve  gain  the 
infraspinous  fossa.  It  is  usually  a  weak  membranous  structure  with  Init  few  liga- 
mentous fibres. 


3.  THE  SHOULDER-JOINT 
Class. — Dpirtlrrosls.  Subdivision. — Enarthrodla. 


The  shoulder  is  one  of  the  most  perfect,  and  most  movable  of  joints,  the  large 
ujjper  end  of  the  humerus  playing  upon  the  shallow  glenoid  cavity.  Like  the  hip, 
it  is  a  ball-and-socket  joint.  It  is  retained  in  position  much  less  by  ligaments  than 
by  muscles  and  the  effects  of  atmospheric  pressure;  and,  owing  to  the  looseness  of 
its  ca])sule,  as  well  as  to  all  the  other  conditions  of  its  construction  and  position, 
it  is  exceedingly  liable  to  be  displaced;  on  the  other  hand,  it  is  sheltered  from 
violence  by  the  two  projecting  ])rocesses — the  acromion  and  coracoid. 

The  jigauients  of  the  shoulder-joint  are: — 


C'ai)sular. 

( ileno-humeral. 


Coraco-humeral. 
Cxlenoid. 


The  capsular  ligament  (figs.  222,  223  and  224)  is  a  loose  sac,  insufficient  in 
itself  to  maintain  the  bones  in  contact.  It  consists  of  fairly  distinct  but  not  coarse 
til)res,  closely  woven  together,  and  directed,  some  straight,  others  oblic^uely,  })etween 
the  two  bones,  a  few  circular  ones  being  interwoven  amongst  them.     At  the  scapula, 


THE  SHOULDER-JOINT 


223 


it  is  fixed  on  the  dorsal  aspect  to  the  j)roniinent  rough  surface  of  the  glenoid  pro- 
cess, reaching  as  far  as  the  neck  of  the  bone.  Above,  it  is  attached  to  the  root  of 
the  coracoid  process:  in  front,  to  the  ventral  surface  of  the  glenoid  process,  at  a 
variable  distance  from  the  articular  margin,  often  reaching  half  an  inch  (12  mm.) 
u{)on  the  neck  of  the  bone,  and  thus  allowing  the  formation  of  a  pouch;  it  may 
not,  however,  extend  for  more  than  a  quarter  of  an  inch  (6  mm.)  beyond  the 
articular  margin:  below,  it  l.)lends  with  the  origin  of  the  long  head  of  the  triceps. 
At  the  humerus,  the  up})er  half  is  fixed  to  the  anatomical  neck,  sending  a  pro- 
longation downwards  between  the  two  tuberosities  which  attenuates  as  it  descends, 
and  covers  the  transverse  humeral  ligament.  The  lower  half  of  the  capsule 
descends  upon  the  humerus  further  from  the  articular  margin,  some  of  the  deeper 
fibres  being  reflected  upwards  so  as  to  be  attached  close  to  the  articular  edge,  thus 
forming  a  kind  of  fibrous  investment  for  the  neck  of  the  humerus.  This  ligament 
is  more  uniform  in  thickness  than  that  of  the  hip. 

Gleno-humeral  bands  of  the  capsule  (figs.  224  and  225). — There  are  three 


Fig.  224. — Vertical  Section  through  the  Shoulder-joint  to  show  the  Gleno- 
humeral  LlGAMEXT. 


fhe  joint  is  opeued  from  behind.) 


Supra-spinatus 
muscle 

Subacromial  bursa 
Tendon  of  biceps 
with  gleno-hume- 
ral ligament 
Tendon  of  subsca- 
pularis 


Capsular  ligament 


Suprascapular 
ligament 


Glenoid  ligimeut  or  flbro-cartilage 


accessory  bands  which  strengthen  the  capsule,  two  of  which  are  seen  superficially, 
and  consist  of  a  few  strengthening  fibres,  one  on  the  inner  aspect  reaching  from  the 
glenoid  cavity  to  the  lower  border  of  the  lesser  tu))erosity  along  the  lower  border  of 
the  subscapularis  tendon ;  and  the  inferior  reaching  from  the  under  part  of  the 
glenoid  cavity  to  the  und(n-  part  of  the  neck  of  the  humerus.  The  third,  the  superior 
band,  is  known  as  the  gleno-humeral  ligament,  and  can  only  be  seen  after  o])en- 
ing  the  capsule.  It  runs  from  the  edge  of  the  glenoid  cavity  at  the  root  of  the 
coracoid  process,  just  internal  to  the  origin  of  the  long  tendon  of  the  biceps,  and, 
passing  inwards  and  downAvards  at  an  acute  angle  to  the  tendon,  for  which  it  forms 
a  slight  groove  or  sulcus,  is  fixed  to  the  lesser  tuberosity  of  the  humerus.  It  is  a 
thin,  ribl)on-like  ])and,  of  wliich  the  up])er  surface  is  attached  to  the  capsule,  while 
the  other  is  free  and  turned  towards  tlie  joint.  In  the  ftetus  it  is  often,  and  in  tlie 
adult  occasionally,  quite  frc-e  from  tlie  capsule,  and  may  be  as  thick  as  the  long 
tendon  of  the  biceps  (fig.  225). 

The   tendons  of    the   mpra-  and  iufra-spinatus,   teres  minor,  and   subscapularis 
muscles  strengthen  and  support  the  cai)sule,  especially  near  their  points  of  inser- 


224 


THE  A  R  TIC  ULA  TIO.XS 


tion,  and  can  ho  witli  difticulty  dissected  off  from  it.  The  long  head  of  the  triceps 
supports  and  strengtliens  tlie  capsule  below.  The  capsule  also  receives  an  upward 
sliji  from  the  pertoraU.-<  vuijor.  The  supra-spinatus  often  sends  a  slip  into  the  cap- 
sule from  its  upper  edge  (fig.  224). 


Fig.  225. — Foctal  SnorLDER-joiNT,  snowiXG  the  Gleno-humeral  Ligament,  and  al-so 
THE  Shokt  Head  of  the  Biceps,  being  continuous  with  the  Coeaco-acromial 
Lkjament. 


Short  tendon  of  biceps  running 
on  into  anterior  baud  ol"  eoraco- 
acromial  ligament 


Long  tendon  of  biceps 
Gleno-humeral  ligament 
Capsule  of  shoulder,  turned  back 


Subscapularis  tendon,  cut  and 
turned  outwards 


The  coraco-humeral  ligament  (fig.  226)  is  a  strong  broad  band,  which  is 
attached  al)()ve  to  the  outer  edge  of  the  root  and  horizontal  limb  of  the  coracoid 
process  nearly  as  far  as  the  tip.  From  this  origin  it  is  directed  backwards  along  the 
line  of  the  biceps  tendon  to  blend  with  the  capsule,  and  is  inserted  into  the  greater 


Fig.  226.— Outer  View  of  the  Shoulder-joint,  showing  the  Coraco-humeral  and 
Transverse  Humeral  Ligaments. 


Trapezoid  ligament  - 


Tendon  of  subscapularis  muscle 


Capsule  of  the  acromio-elavicular 
joint 

Coraeo-aeromial  ligament 
Coraco-humeral  ligament 


Transverse  humeral  ligament 


Tendon  of  biceps 


tuberosity  of  the  humerus.  Seen  from  the  back,  it  looks  like  an  uninterrupted 
continuation  of  the  cajjsule,  while  from  the  front  it  looks  like  a  fan-shaped  pro- 
longation from  it  overlying  the  rest  of  the  ligament.  At  its  origin  there  is  some- 
times a  bursa  between  it  and  the  capsule. 


THE  SHOULDER-JOINT 


225 


The  glenoid  ligament  (figs.  224  and  227)  is  a  narrow  rim  of  dense  fibro-cartilage, 
which  surrounds  the  edge  of  and  deepens  the  glenoid  socket.  It  is  about  a  quarter 
of  an  inch  (6  mm. )  wide  above  and  below,  but  less  at  the  sides.  Its  outer  edge  is 
inseparably  welded,  near  the  bone,  with  the  capsular  ligament.  Its  structure  is 
almost  entirely  fibrous,  with  but  few  cartilage  cells  intermixed.  At  the  ujjper  part 
of  the  fossa  the  biceps  tendon  is  prolonged  into  the  glenoid  ligament,  the  tendon 
usually  dividing  and  sending  fibres  right  and  left  into  the  ligament,  which  may 
Avind  round  nearly  the  whole  circumference  of  the  socket.  It  may,  hoAvever  send 
fil)res  into  one  side  only,  usually  into  the  outer. 

The  articular  cartilage  covering  the  glenoid  fossa  is  thicker  at  the  circumfer- 
ence than  in  the  centre,  thus  tending  to  deepen  the  cavity.  It  is  usually  thickest 
at  the  lower  part  of  the  fossa;  over  the  head  of  the  humerus  the  cartilage  is  thickest 
at  and  below  the  centre. 

The  synovial  membrane  lines  the  glenoid  ligament,  and  is  then  reflected  over 
the  capsule  as  far  as  its  attachment  to  the  humerus,  from  which  it  ascends  as  far  as 
the  edge  of  the  articular  cartilage.  The  tendon  of  the  biceps  receives  a  long  tubular 
sheath,  which  is  continuous  with  the  synovial  membrane,  V)oth  at  its  attached 
extremity  and  at  the  bicipital   groove,  but  is  free  in  the  rest  of  its  extent.     The 

Fig.  227. — Biceps  Texdox,  bifurcating  axd  Blending  on  each  Side  with  the 

Glenoid  Fibro-cartilage. 


Tendon  of  biceps 


Tendon  of  biceps  blended  with 
glenoid  ligament 


synovial  cavity  sometimes  communicates  with  the  bursa  under  the  subscapularis,  and 
less  frequently  with  one  under  the  infra-spinatus  muscle.  It  also  sends  a  pouch-like 
prolongation  beneath  the  coracoid  process  when  the  fibrous  capsule  is  attached 
wdde  of  the  margin  of  the  glenoid  fossa.  A  few  fringes  are  seen  near  the  edge 
of  the  glenoid  cavity,  and  there  is  often  one  which  runs  down  the  inner  edge  of  the 
biceps  tendon,  extending  slightly  below  it  and  making  a  slight  groove  for  the 
tendon  to  lie  in. 

The  transverse  humeral  ligament  (fig.  226)  is  so  closely  connected  with  the 
capsule  of  the  shoulder  that,  although  it  is  a  proper  ligament  of  the  humerus,  it 
may  well  be  described  here.  It  is  a  strong  band  of  fibrous  tissue,  Avhich  extends 
between  the  two  tuberosities,  roofing  in  the  bicipital  canal.  It  is  covered  by  a  thin 
expansion  of  the  capsule.  It  is  limited  to  the  portion  of  the  bone  above  the  line 
of  the  epiphysis.      (C.  Gordon  Brodie.  .lourn.  Anat.  xxiv.  247.) 

The  following  muscles  are  in  relation  with  the  capsular  ligament:  above,  the 
supra-spinatus ;  externally,  the  infra-spiiiatiis  and  teres  minor ;  below,  the  long  head 
of  the  triceps ;  internally,  the  tendon  of  the  subscapularis.  The  deltoid  covers  the 
outer  and  upper  surfaces  of  the  joint,  but  is  separated  from  the  capsule  by  a  bursa, 
and  the  tendons  of  the  short  rotator  muscles.  An  uj>ward  t^lip  from  the  pectoralis 
15 


226  THE  ARTICULATIOyS 

7/iajor  joins  the  cai).<ule  In-low.  Internally  are  the  long  tendon  of  the  biceps  and  the 
gleno-hunieral  ligament. 

The  arterialsupply  is  derived  from  the  siqjrascapular.  anterior  and  posterior 
circumflex,  subscapular,  dorsalis  scapuhe,  and  a  branch  from  the  second  portion  of 
the  axillary  artery. 

The  nerve-supply  is  derived  from  the  suprascapular,  by  branches  in  both  fosste; 
and  from  the  circumlicx  and  subscapular  nerves. 

The  movements  of  the  shoulder-joint  consist  of  flexion,  extension,  adduction 
and  al)durtii)ii.  rotation  and  circumduction. 

Flexion  is  the  SAvinging  forwards,  extension  the  swinging  backwards,  of  tlie 
humerus;  alxluction  is  the  raising  of  the  arm  from,  and  adduction  depression  of 
the  arm  to,  the  side.  In  flexion  and  extension  the  head  of  the  humerus  moves 
upon  the  centre  of  the  glenoid  fossa  round  an  oljlique  line  corresponding  to  the 
axis  of  the  head  and  neck  of  the  humerus,  flexion  being  more  free  than  extension, 
and  in  extreme  flexion  the  scapula  follows  the  head  of  the  humerus,  so  as  to  keep 
the  articular  surfaces  in  apposition.  In  extension  the  scapula  moves  much  less,  if 
at  all. 

In  abduction  and  adduction  the  scapula  is  fixed,  and  the  humerus  rolls  up  and 
down  upon  the  glenoid  fossa;  during  abduction  the  head  descends  until  it  projects 
l)eyond  the  lower  edge  of  the  glenoid  cavity,  and  the  great  tuberosity  impinges 
against  the  arch  of  the  acromion;  during  adduction,  the  head  of  the  humerus 
ascends  in  its  socket,  the  arm  at  length  reaches  the  side,  and  the  capsule  is  com- 
l)letely  relaxed. 

In  circumduction,  the  humerus,  by  passing  cpiickly  through  these  movements, 
describes  a  cone,  whose  apex  is  at  the  shoulder- joint,  and  the  base  at  the  distal 
extremity  of  the  bone  or  limb. 

Rcjtation  takes  place  round  a  vertical  axis  drawn  through  the  extremities  of  the 
humerus  from  the  centre  of  the  head  to  the  inner  condyle;  in  rotation  forwards 
(that  is,  inwards)  the  head  of  the  bone  rolls  back  in  the  socket  as  the  great  tuber- 
osity and  shaft  are  turned  forwards;  in  rotation  backwards  (that  is,  outAvards)  the 
head  of  the  bone  glides  forwards,  and  the  tuberosity  and  shaft  of  the  humerus  are 
turned  liackAvards,  i.e.  outAA'ards. 

Great  freedom  of  movement  is  permitted  at  the  shoulder,  and  this  is  increased 
by  the  mobility  of  the  scapula.  Restraint  is  scarcely  exercised  at  all  upon  the 
movements  of  the  shoulder  by  the  ligaments,  but  chiefly  by  the  muscles  of  the 
joint. 

In  abduction,  the  loAver  part  of  the  capsule  is  somcAvhat,  and  in  extreme  abduc- 
tion consideral)ly,  tightened;  and  in  rotation  iuAvards  and  outAvards,  the  upper  part 
of  the  capsule  is  made  tense,  as  is  also,  in  the  latter  movement,  the  coraco-humeral 
ligament. 

The  movements  of  abduction  and  extension  have  a  most  decided  and  definite 
resistance  offered  to  them  other  than  by  muscles  and  ligaments,  for  the  great 
tuberosity  of  the  humerus,  by  striking  against  the  acromion  process  and  coraco- 
acromial  ligament,  stops  short  any  further  advance  of  the  bone  in  these  directions, 
and  thus  abduction  ceases  altogether  as  soon  as  the  arm  is  raised  to  a  right  angle 
Avith  the  trunk,  and  extension  shortly  after  the  humerus  passes  the  line  of  the 
trunk. 

Further  elevation  of  the  arm  beyond  the  right  angle  is  effected  by  the  rotation 
of  the  scajjula  round  its  OAvn  axis  by  the  action  of  the  trapezius  and  serratus 
magnus  muscles  upon  the  sterno-clavicular  and  acromio-clavicular  joints. 

The  acromion  and  coracoid  processes,  together  Avith  the  coraco-acromial  liga- 
ment, form  an  arch.  Avhich  is  separated  by  a  bursa  and  the  tendon  of  the  mpra- 
.^pimtUis  from  the  capsule  of  the  shoulder.  Beneath  this  arch  the  movements  of  the 
joint  take  ])lace,  and  against  it  the  head  and  tuberosities  are  pressed  Avhen  the 
Aveight  of  the  trunk  is  supported  by  the  arms;  the  greater  tuberosity  and  the  upper 
]Kirt  of  the  shaft  impinge  upon  it  Avhen  abduction  and  extension  are  carried  to  their 
fullest  extent. 

No  description  of  tlic  sliouldcr-joint  Avould  be  complete  without  a  short  notice 
of  the  peculiar  relation  Avhich  the  biceps  tendon  bears  to  the  joint.  It  passes  over 
the  head  of  the  humerus  a  little  to  the  inner  side  of  its  summit,  and  lies  free 


THE  ELBOW-JOIXT  227 

within  the  capsule,  surrounded  only  by  a  tubular  process  of  synovial  membrane. 
It  is  fiat,  ■with  the  surfaces  looking  upwards  and  downwards,  until  it  reaches  the 
bicipital  groove,  when  it  assumes  a  rounded  form.  It  strengthens  the  articulation 
along  the  same  course  as  the  coraco-hvuneral  ligament,  and  tends  to  prevent  the  head 
of  the  humerus  from  being  pulled  upwards  too  forcibly  against  the  under  surface  of 
the  acromion.  It  also  serves  the  purpose  of  a  ligament  by  steadying  the  head  of 
the  humerus  in  various  movements  of  the  arm  and  forearm,  and  to  this  end  is  let 
into  a  groove  at  the  upper  end  of  the  Ijone,  from  which  it  cannot  escaj)e  on  account 
of  the  abutting  tuberosities  and  the  strong  transverse  humeral  ligament  Avhich 
binds  it  down.  Further,  it  acts  like  the  four  shoulder  muscles,  which  pass  over 
the  capsule  to  keep  the  head  of  the  humerus  against  the  glenoid  socket;  and,  more- 
over, it  resists  the  tendency  of  the  pedoralis  major  and  latissimus  dorsi  muscles,  in 
certain  actions  when  the  arm  is  away  from  the  side  of  the  body,  to  pull  the  head  of 
the  humerus  below  the  lower  edge  of  the  cavity. 


4.  THE  ELBOW-.JOINT 
Class, — Diarthrosis.  Subdivision. — Ginglymus. 

The  elbow  is  a  complete  hinge,  and,  unlike  the  knee,  depends  for  its  security 
and  strength  upon  the  configuration  of  its  bones  rather  than  on  the  numljer, 
strength,  or  arrangement  of  its  ligaments.  The  bones  composing  it  are  the  lower 
end  of  the  humervis  al:)Ove,  and  the  upper  ends  of  the  radius  and  ulna  below;  the 
articular  surface  of  the  humerus  being  received  partly  within  the  great  sigmoid 
ca\dty  of  the  ulna,  and  partly  upon  the  cup-shaped  surface  of  the  radius.  The 
ligaments  form  one  large  and  capacious  capsule,  which,  by  blending  with  the 
orlncular  ligament,  and  then  passing  on  to  be  attached  to  the  neck  of  the  radius, 
embraces  the  elbow  and  the  superior  radio-ulnar  joints,  uniting  them  into  one. 
Laterally,  it  is  consideral;)ly  strengthened  by  superadded  fibres  arising  from  the 
condyles  of  the  humerus  and  inseparal)ly  connected  with  the  capsule.  For  con- 
venience of  description  it  will  be  sjioken  of  as  consisting  of  four  portions: — 

Anterior.  Internal. 

Posterior.  External. 

The  anterior  portion  (fig.  228)  is  attached  to  the  front  of  the  humerus  above 
the  articular  surface  and  coronoid  fossa,  in  an  inverted  V-shaped  manner,  to  two 
very  faintly  marked  ridges  which  start  from  the  front  of  the  internal  and  external 
condyles,  and  meet  at  a  variable  distance  aljove  the  coronoid  fossa.  Below,  it  is 
fixed,  just  beyond  the  articular  margin,  to  the  front  of  the  coronoid  process;  it  is 
intimately  blended  Avith  the  front  of  the  orbicular  ligament,  a  few  fibres  passing 
on  to  the  neck  of  the  radius.  It  varies  in  strength  and  thickness,  being  sf>me- 
times  so  thin  as  l:)arely  to  cover  the  synovial  membrane;  at  others,  thick  and  strong, 
and  formed  of  coarse  decussating  filjres,  the  majority  of  which  descend  from  the 
inner  side  outwards  to  the  radius. 

The  posterior  portion  (fig.  229),  thin  and  membranous,  is  attached  superiorly 
to  the  humerus,  in  much  the  same  inverted  V-shaped  way  as  the  anterior;  ascend- 
ing from  the  internal  condyle,  along  the  inner  side  of  the  olecranon  fossa  nearly 
to  the  top;  then,  crossing  the  bottom  of  the  fossa,  it  descends  on  the  outer  side, 
skirting  the  outer  margin  of  the  trochlear  surface,  and  turns  outwards  along  the 
]MjSterior  edge  of  the  capitellum.  Inferiorly,  it  is  attached  to  a  slight  groove  along 
the  superior  and  external  surfaces  of  the  olecranon,  and  the  rough  surface  t)f  the 
ulna  just  beyond  the  lesser  sigmoid  notch,  and  Avith  the  orlncular  ligament,  a  few 
fibres  ])assing  on  to  the  neck  of  the  radius.  It  is  composed  of  decussating  fibres, 
most  of  which  pass  vertically  or  obliquely  downwards,  a  few  taking  a  transverse 
course  at  the  summit  of  the  olecranon  fossa  where  the  ligament  is  usually  thinnest. 

The  internal  portion  (fig.  228)  is  thicker,  stronger,  and  denser  than  either  the 
anterior  or  posterior  ])ortions.  It  is  triangular  in  form,  its  apex  being  attached  to 
the  anterior  and  under  aspect  of  the  internal  condyle,  and  to  the  condyloid  edge  of 


228 


THE  ARTICl  LA  TIONS 


the  groove  between  the  trochlea  and  the  condyle.  The  fibres  radiate  downwards 
froni  tbis  attachment,  the  anterior  passing  forwards  to  be  fixed  to  the  rough  over- 
lianging  inner  edge  of  the  coronoid  i)rocess;  the  middle  descend  less  obliquely  to  a 
ridge  running  l)etween  the  coronoid  and  olecranon  j^rocesses,  while  the  posterior 


Fig.  228. — Internal  View  ok  the  Elbow-joint. 


—  Orbicular 
ligament 


Tendon 
of  biceps 


Oblique 
ligament 

_  Upper  edge 
of  inter- 
osseous 
membrane 


pass  oliliquely  backwards  to  the  inner  edge  of  the  olecranon  just  beyond  the 
articular  margin.  The  anterior  fibres  are  the  thickest,  strongest,  and  most 
pronounced. 

The  external  portion   (fig.  229)   is  attached  above  to  the  lower  part  of  the 
external  condyle,  and  from  this  the  fibres  radiate  to  their  attachment  into  the  outer 


Fig.  229. — External  View  of  the  Elbow- joint. 


Orbicular  ligament 


External  lateral 
ligament 


Posterior  ligament 


side  of  the  orl>icular  ligament,  a  few  fibres  being  prolonged  to  reach  the  neck  of  the 
radius.  The  anterior  fibres  reach  further  forwards  than  the  posterior  do  behind. 
It  is  strong  and  Avell-mnrked,  but  less  so  than  the  internal  portion. 

The  synovial  membrane  lines  the  whole  of  the  capsule,  and  extends  into  the 


OF  THE  RADIUS   WITH  THE  ULNA  229 

superior  radio-iilnar  joint,  lining  the  orl)icular  ligament.  Outside  the  synovial 
menil)rane,  l)ut  inside  the  capsule,  are  often  seen  some  pads  of  fatty  tissue;  one  is 
situated  on  the  inner  side  at  the  Ijase  of  the  olecranon,  another  is  seen  on  the  out- 
side projecting  into  the  cavity  between  the  radius  and  ulna;  this  latter,  Avith  a  fold 
of  synovial  membrane  opposite  the  front  of  the  outer  lip  of  the  trochlea,  suggests 
the  division  of  the  joint  into  two  parts — one  internally  for  the  ulna,  and  another 
externally  for  the  radius.  There  are  also  pads  of  fatty  tissue  at  tlie  bottom  of  the 
olecranon  and  coronoid  foss?e,  and  at  the  tip  of  the  olecranon  process. 

The  arterial  supply  is  derived  from  each  of  the  vessels  forming  the  free  anasto- 
mosis around  the  elbow,  and  there  is  also  a  special  branch  to  the  front  and  outer 
side  of  the  joint,  from  the  bracliial  artery,  and  the  arterial  branch  to  tlie  brachidlis 
anticus  also  feeds  the  front  of  the  joint. 

The  nerve-supply  comes  from  the  musculo-cutaneous  chiefly;  the  ulnar, 
median,  and  musculo-spiral  also  give  filaments  to  the  joint. 

The  movements  permitted  at  the  elbow  are  those  of  a  true  hinge  joint,  viz. 
flexion  and  extension.  These  movements  are  oblique,  so  that  the  forearm  is 
inclined  inwards  in  flexion,  and  outwards  in  extension;  they  are  limited  by  the 
contact  respectively  of  the  coronoid  and  olecranon  processes  of  the  ulna  Avith  their 
corresponding  fossae  on  the  humerus,  and  their  extent  is  determined  by  the  rela- 
tive proportion  l)etween  the  length  of  the  processes  and  depth  of  the  fossje  which 
receive  them,  rather  than  by  the  tension  of  the  ligaments,  or  the  bulk  of  the  soft 
parts  over  them.  The  anterior  and  posterior  portions  of  the  capsule,  together  Avith 
the  corresponding  portions  of  the  lateral  ligament,  are  not  put  on  the  stretch  during 
flexion  and  extension;  but,  although  they  may  assist  in  checking  the  A-elocity,  and 
thus  prevent  undue  force  of  impact,  they  do  not  control  or  determine  the  extent  of 
these  movements.  The  limit  of  extension  is  reached  when  the  ulna  is  nearly  in  a 
straight  line  with  the  humerus;  and  the  limit  of  flexion  Avhenthe  ulna  describes  an 
angle  of  from  30°  to  40°  Avith  the  humerus. 

The  ol )li(|uity  of  these  moA^ements  is  due  to  the  outAvard  inclination  of  the  upi)er 
and  Ijack  j^art  of  the  trochlear  surface,  and  the  greater  prominence  of  tlie  inner  lip 
of  the  trochlea  below;  thus  the  plane  of  motion  is  directed  from  behind  iuAvards 
and  forwards,  and  carries  the  hand  tOAvards  the  middle  third  of  the  clavicle.  The 
obliquity  of  the  joint,  the  iuAvard  tAvist  of  the  shaft  of  the  humerus,  and  the  back- 
ward direction  of  its  head,  all  tend  to  bring  the  hand  toAvards  the  mid  line,  under 
the  immediate  observation  of  the  eye,  Avhether  for  defence,  employment,  or  nourish- 
ment. This  is  in  striking  contrast  to  the  loAver  liml),  Avhere  the  direction  of  the 
foot  diverges  from  the  median  axis  of  the  trunk,  thus  preventing  aAvkAvardness  in 
locomotion.  In  flexion  and  extension,  the  cup-like  depression  of  the  radial  head 
glides  upon  the  capitellum,  and  the  inner  margin  of  the  radial  head  travels  in  the 
groove  betAveen  the  capitellum  and  the  trochlea.  This  alloAvs  the  radius  to  rotate 
upon  the  humerus  Avhile  following  the  ulna  in  all  its  moA^ements.  In  full  exten- 
sion and  supination,  the  head  of  the  radius  is  barel}^  in  contact  Avith  the  inferior 
surface  of  the  capitellum,  and  projects  so  much  baclnvards  that  its  posterior  margin 
can  1)e  felt  as  a  prominence  at  the  back  of  the  elboAV.  In  full  flexion  the  anterior 
edge  of  the  radial  head  is  received  into,  and  checked  against,  the  depression  aboA^e 
the  capitellum;  Avhile  in  mid-flexion  the  cup-like  depression  is  fairly  received  upon 
the  ca})itellum,  and  in  this  position,  the  raclius  being  more  completely  steadied  l)y 
the  humerus  than  in  any  other,  })ronation  and  su})inati()n  take  ])lace  most  perfectly. 


5.  THE  UNION  OF  THE  RADIUS  WITH  THE  ULNA 

The  radius  is  firmly  united  to  the  ulna  by  two  joints,  and  an  intermediate 
fibrous  union,  viz. : — 

(a)  The  superior  radio-ulnar, — Avhercat  the  head  of  the  radius  rotates  Avithin 
the  lesser  sigmoid  cavity  and  orbicular  ligament. 

(6)  The  union  of  the  shafts, — the  mid  radio-ulnar  union. 

(c)  The  inferior  radio-ulnar, — Avhereat  the  lower  end  of  the  radius  rolls  round 
the  head  of  the  ulna. 


230 


THE  ARTICl 'LA  TIOXS 


(a)  The  Superior  Radio-ulnar  Joint 
Class. — Diarthrosis.  Subdivision. —  Trochoides. 

The  l)ones  which  enter  into  tliis  joint  are,  the  iihia  hy  its  lesser  sigmoid  cavity, 
and  the  radius  hy  the  smooth  vertical  border  or  rim  on  its  head.  There  is  but 
one  ligament  special  to  the  joint,  viz. : — 

Orbicular. 

The  orbicular  ligament  consists  of  bands  of  strong  fibres,  somewhat  thicker 
than  the  lapsule  of  the  elbow-joint,  which  encircle  the  head  of  the  radius, 
retaining  it  against  the  side  of  the  ulna.  The  bulk  of  these  fiV)res  forms  about 
three-fourths  of  a  circle,  and  they  are  attached  to  the  anterior  and  posterior 
margins  of  the  lesser  sigmoid  cavity;  some  few  are  continued  round  below  the 
lesser  sigmoid  cavity,  and  form  a  complete  ligamentous  circle.  The  ligament  is 
inseparably  connected  along  its  upper  edge  and  external  (i.e.  its  non-articular) 
surface  with  tlie  anterior,  posterior,  and  external  portions  of  the  capsule  of  the 
elbow,  a  few  of  the  fibres  of  these  portions,  especially  of  the  external,  descending 


Fig.  230. — Orbicular  Ligamext. 

(The  head  of  the  radius  removed  to  show  the  membranous  connection  of  this  ligament 

with  the  radius.) 


Capsule  of  elbow -joint 
CusMon  of  falty  tissue 

Membranous  tissue  joining  the 
orbicular  ligament  to  the  neck 
of  the  radius 

RADIUS 

Orbicular  ligament 


Capsule  of  elbow 


to  be  attached  to  the  neck  of  the  radius.  The  lower  part  of  the  articulation 
is  covered  in  by  a  thin  independent  membranous  layer,  which  passes  from  the 
lower  edge  of  the  orbicular  ligament  to  the  neck  of  the  radius,  strengthened  on 
the  outer  side  by  those  fil)res  passing  down  from  the  capsule.  They  are  loose 
enough  to  allow  tlie  ])one  to  rotate  upon  its  own  axis  (fig.  230). 

Tlie  synovial  membrane  is  the  same  as  that  of  the  elbow,  and,  after  lining  the 
orbicular  ligament,  passes  on  to  the  neck  of  the  radius,  and  thence  up  to  the 
articular  cartilage. 

The  arterial  and  nerve-supply  are  the  same  as  those  to  the  outer  i)art  of  the 
elbow-joint. 

(h)  The  Mid  Radio-ulnar  Union 

There  arc  two  interosseous  ligaments  which  pass  between  the  shafts  of  the 
bones  and  unite  them  iinnly  together,  viz. : — 


Oblique  ligament. 


Interosseous  membrane. 


The  oblique  ligament  (figs.  228  and  230  A)  is  a  fairly  strong,  narrowband, 
which  i)asses  from  the  lower  end  of  the  rough  outer  border  of  the  coronoid  process. 


OF  THE  RADIUS   WITH  THE  ILXA 


281 


downwards  and  outwards  to  be  attached  to  the  posterior  edge  of  the  lower  end  of 
the  bicipital  tuberosity  of  the  radius  and  the  vertical  ridge  running  from  it  to  the 
inner  border  of  the  bone.  Some  of  its  fibres  blend  with  the  fibres  of  insertion 
of  the  biceps  tendon;  behind,  it  is  in  close  contact  with  the  supiiiator  brevi^ ; 
below,  a  thin  membrane  passes  off  from  it  to  the  upper  edge  of  the  interosseous 
membrane;  the  posterior  interosseous  vessels  pass  in  the  space  between  it  and 
the  interosseous  membrane;  occasionally  a  slip  is  continued  into  the  orbicular  liga- 
ment of  the  superior  radio-ulnar  articulation  (see  fig.  230  A). 

The  interosseous  membrane  (fig.  228)  is  attached  to  the  ulna  at  the  lowest 
part  of  the  ridge  in  front  of  the  depression  for  the  supinator  brevis,  and  along  the 
whole  length  of  the  interosseous  border  as  far  as  the  inferior  radio-ulnar  articulation, 
approaching  the  front  of  the  bone  in  the  lower  part  of  its  attachment.  To  the 
radius  it  is  attached  along  the  interosseous  border,  from  an  inch  (2 '5  cm.  j  below 
the  bicipital  tuberosity  to  the  sigmoid  notch  for  the  lower  end  of  the  ulna.  It  is 
strongest  and  broadest  in  the  centre,  where  the  fibres  are  dense  and  closely  packed; 
it  is  also  well  marked  beneath  the  pronator  quadratus,  and  thickens  considerably  at 
the  lower  end,  forming  a  strong  band  of  union  between  the  two  bones.  Its  fibres 
pass  chiefly  downwards  and  inwards,  from  the  radius  to  the  ulna,  though  some 

Fio.  230  A. — Upper  Poktions  of  Left  Ulna  and  Radius  with  Oblique  and  Orbicular 
Ligaments  :  to  Show  an  Occasional  Slip  from  the  Oblique  Ligament  to  the 
Lower  Fart  of  the  Orbicular  Ligament.  This  condition  is  present  in  the  spider  monkey 
(Ateles),  which  has  no  external  thumb  but  only  rudimentary  bones  of  one. 

(From  a  dissection  by  Mr.  W.  Pearson,  Royal  College  of  Surgeons,  England.) 


Orbicular  ligament 


Occasional  slip  from  oblique  liga- 
ment to  orbicular  ligament 


Oblique  ligament 


take  the  opposite  direction;  at  the  lower  end  some  are  transverse.  On  the  posterior 
surface  are  one  or  two  bands,  which  pass  downwards  and  outwards  from  the  ulna 
to  the  radius,  and  frequently  there  is  a  strong  1)undle  as  large  as  the  oblique  liga- 
ment; this,  which  should  be  called  the  inferior  oblique  ligament  (fig.  234), 
stretches  from  the  ulna,  an  inch  and  a  half  above  its  lower  extremity,  downwards 
and  outwards  to  the  ridge  above  and  behind  the  sigmoid  notch  of  the  radius. 

At  its  attachment  to  the  bones,  the  interosseous  membrane  blends  with  the 
periosteum.  Its  upper  border  is  connected  with  the  oblique  ligament  l)y  a  thin 
mem1)rane,  Avhich  is  pierced  by  the  posterior  interosseous  vessels;  and  the  lower 
border,  which  stretches  across  between  the  two  bones  just  above  the  inferior  radio- 
ulnar articulation,  assists  in  completing  the  caj^sule  of  that  joint.  Its  anterior 
surface  is  in  relation  with  the  flexor  profun(bi><  digitoram  and  flexor  lougtis  pollieis 
in  the  upper  three-quarters,  the  lower  fourth  being  in  relation  with  the  pronator 
quadratus.  The  anterior  interosseous  vessels  and  nerve  descend  along  the  middle  of 
the  membrane,  the  artery  being  Ijound  down  to  it.  About  an  inch  from  the  lower 
end,  it  is  pierced  by  the  anterior  interosseous  artery.  The  posterior  surface  is  in 
relation  with  the  supinator  brevis,  extensor  oss'is  metacarpi,  extensor  primi,  extensor 
secundi  internodii  pollieis,  and  the  extensor  indicis ;  at  its  lower  part,  also  with  the 
posterior  branch  of  the  anterior  interosseous  artery. 


232  THE  ARTICTLATIOXS 

(r)    THK    IXFEHIOR    IvADIO-lI.NAR    JoiNT 

Class. — DIttrthrosis.  Subdivision. — Trochoides. 

This  is,  ill  one  ivspcet.  tlie  reverse  of  the  superior;  for  the  radius,  instead  of 
presenting  a  eircuhir  head  to  rotate  upon  the  faeet  on  the  ulna,  presents  a  concave 
facet  which  rolls  round  the  ulna.  The  articulation  may  he  said  to  consist  of  two 
})arts  at  right  angles  to  each  other:  one  l)etween  the  radius  and  ulna,  and  the 
other  between  the  ulna  and  triangular  fibro-cartilage. 

The  ligaments  are: — 

Anterior  radio-ulnar.  Posterior  radio-ulnar. 

Triangular  fi})ro-cartilage. 

The  triangular  fibro- cartilage  (tigs.  234  and  235)  assists  the  radius  in  forming 
an  arch  under  whit-h  is  received  the  first  row  of  carpal  bones.  Its  base  is  attached 
to  the  margin  of  the  radius,  separating  the  sigmoid  cavity  from  the  articular 
surfaee  for  the  carpus,  while  its  apex  is  fixed  to  the  fossa  at  the  base  of  the  styloid 
process  of  the  ulna.  It  gradually  and  uniformly  diminishes  in  width  from  base  to 
apex,  becoming  rounded  Avhere  it  is  fixed  to  the  ulna;  it  is  joined  by  fibres  of  the 
internal  lateral  ligament  of  the  wrist.  It  is  about  three-eighths  of  an  inch  (1  cm. ) 
wide,  and  the  same  from  base  to  apex;  thicker  at  the  circumference  than  in  the 
centre;  smooth  and  concave  above  to  adapt  itself  to  the  ulna,  and  smooth  and 
slightly  concave  lielow  to  fit  over  the  cuneiform  bone.  Its  anterior  and  posterior 
1 »( )rders  are  united  to  the  anterior  and  posterior  radio-ulnar  and  radio-carpal  liga- 
ments. It  is  the  most  important  structure  in  the  inferior  radio-carpal  articulation, 
as  it  is  a  very  firm  bond  of  union  between  the  lower  ends  of  the  bones,  and  serves 
to  limit  their  movements  upon  one  another  more  than  any  other  structure  in  either 
tlu'  ujiper  or  lower  radio-ulnar  joints.  Its  structure  is  fibrous  nt  the  circumference, 
while  in  the  centre  there  is  a  jDreponderance  of  cells.  It  differs  from  all  other  fibro- 
cartilages  in  entering  into  two  distinct  articulations;  and  separates  entirely  the 
synovial  membrane  of  the  radio-ulnar  joint  from  that  of  the  wrist. 

The  anterior  radio-ulnar  ligament  (fig.  231)  is  attached  by  one  end  to  the 
anterior  edge  of  the  sigmoid  cavity  of  the  radius,  and  ]>y  the  other  to  the  rough 
l)one  above  the  articular  surface  of  the  ulna  as  far  inwards  as  the  notch,  as  well  as 
into  the  anterior  margin  of  the  triangular  cartilage  from  base  to  apex. 

The  posterior  radio-ulnar  ligament  (fig.  232)  is  similarly  attached  to  the 
posterior  margin  of  the  sigmoid  cavity  at  one  end,  and  at  the  other  to  the  rough 
bone  above  the  articular  surface  of  the  extremity  of  the  ulna  as  far  inwards  as  the 
groove  for  the  extemor  carpi  ulnarls,  -with  the  sheath  of  which  it  is  connected,  as 
well  as  into  the  whole  length  of  the  posterior  margin  of  the  triangular  fibro-cartilage. 
Both  the  radio-ulnar  ligaments  consist  of  thin,  almost  scattered,  fibres,  but  they 
serve  to  form  a  capsule  for  the  support  and  protection  of  the  synovial  membrane. 

The  lower  end  of  the  interosseous  membrane  extends  between  the  ulna  and 
radius  innnediately  above  their  points  of  contact.  Transverse  fibres  between  the 
t\vo  bones  form  a  sort  of  arcli  above  the  concave  articular  facet  of  the  radius,  and, 
joining  the  anterior  and  ]iosterior  radio-ulnar  ligaments,  complete  the  capsule  of  the 
inferior  r.-uho-ulnar  joint. 

The  synovial  membrane,  sometimes  called  the  membrana  sacciformis,  is 
large  and  loose  ni  i)roportion  to  the  size  of  the  joint.  It  is  not  only  interi)osed 
lietween  the  ra(nal  and  ulnar  articular  surfaces,  but  lines  the  terminal  articular 
surface  of  the  ulna  and  the  upper  surface  of  the  triangular  fibro-cartilage. 

The  arterial  supply  is  derived  from  the  anterior  interosseous  artery,  and 
branches  of  the  anterior  carpal  arch. 

The  nerve-supply  comes  from  the  anterior  interosseous  of  the  median,  and  tlie 
l)osteiior  interosseous  l)ranch  of  the  musculo-spiral. 

The  movements  of  the  radius. — The  upper  end  of  the  radius  rotates  upon 
an  axis  drawn  through  its  own  head  and  neck  within  the  collar  formed  bv  the 
lesser  sigmoid  cavity  and  the  orl)icular  ligament,  while  the  lower  end,  retained  in 
position  l)y  the  triangular  ligament,  rolls  round  the  bead  of  the  ulna.     This  rotation 


THE  RADIO-CARPAL  233 

is  called  'pronation,  when  the  radius  from  a  i)Osition  nearly  parallel  to  the  ulna  turns 
inwards  so  as  to  lie  oliliquely  across  it;  and  sirplriation,  when  the  radius  turns  V)ack 
again  from  within  outwards,  so  as  to  uncross  and  lie  nearly  parallel  with  the  ulna. 
In  these  movements,  the  radius  carries  with  it  the  hand,  Avhich  rotates  on  an  axis 
passing  a  little  to  the  inner  side  of  the  middle  line;  thus,  the  hand  when  })ronated, 
lies  with  its  dorsum  upwards,  as  in  playing  the  piano,  while  Avhen  sui)inated,  the 
])alm  lies  upwards — the  attitude  of  a  beggar  asking  alms.  "W'ard  thus  expresses 
the  relations  of  the  two  extremities  of  the  radius  in  pronation  and  supination:  '  The 
head  of  the  radius  is  so  disposed  in  relation  to  the  sigmoid  cavity  at  the  lower  end 
tliat  the  axis  of  the  former  if  prolonged  falls  upon  the  centre  of  the  circle  of  which 
tlie  latter  is  a  segment; '  the  axis  thus  passes  through  the  lower  end  of  the  ulna  at 
a  point  at  which  the  triangular  fibro-cartilage  is  attached,  and  if  prolonged  further, 
l)asses  througli  the  ring  linger.  Thus  the  radius  describes,  in  rotating,  a  Idunt- 
})ointed  cone  whose  apex  is  the  centre  of  the  radial  head,  and  whose  base  is  at  the 
wrist;  partial  rotation  of  the  Ijone  being  unaccompanied  by  any  hinge-like  or 
antero-posterior  motion  of  its  head,  and  pronation  and  supination  occurring  with- 
out disturliance  to  the  parallelism  of  the  bones  at  the  superior  radio-ulnar  joint. 
Associated  with  this  rotation  in  the  ordinary  way,  there  is  some  rotation  of  the 
humero-ulnar  shaft,  which  causes  lateral  shifting  of  the  hand  from  side  to  side; 
thus,  with  pronation  there  is  some  abduction,  and  with  supination  some  adduction 
combined,  so  that  the  hand  can  keep  on  the  same  superficies  in  both  pronation  and 
supination.  The  power  of  supination  in  man  is  much  greater  than  pronation, 
owing  to  the  immense  ]iower  and  leverage  obtained  l)y  the  curve  of  the  radius, 
and  by  the  attaclnnent  of  the  l)iceps  tendon  to  the  back  of  the  tubercle.  For  this 
reason  all  our  screw-driving  and  l)oring  tools  are  made  to  he  used  by  supination 
movements. 

In  the  undissected  state,  the  amount  of  rotation  it  is  possible  to  ol)tain  is  aljout 
135°,  so  that  neither  the  palm  nor  the  fore  part  of  the  lower  end  of  the  radius  can 
])e  turned  completely  in  opposite  directions;  yet  in  the  living  subject  this  amount 
can  be  greatly  increased  by  rotation  of  the  humero-ulnar  shaft  at  the  shoulder-joint. 

Pronation  is  checked  in  the  living  subject  by  (a)  the  posterior  inferior  radio- 
ulnar ligament,  Avhich  is  strengthened  by  the  connection  of  the  sheath  of  the  extensor 
tendons  with  it;  (b)  the  lowermost  fibres  of  the  interosseous  meml)rane;  (c)  the 
l)ack  part  of  the  internal  and  adjacent  fibres  of  the  posterior  ligament  of  the  wrist, 
and  (d)  the  meeting  of  the  soft  parts  on  the  front  of  the  forearm. 

Supination  is  checked  mainly  (a)  by  the  internal  lateral  ligament  of  the  wrist. 
l)ut  partly  also  by  (b)  the  ol)lique  radio-ulnar  ligament;  (c)  the  anterior  inferior 
radio-ulnar  ligament,  and  (d)  the  lowest  fibres  of  the  interosseous  membrane. 

The  interosseous  membrane  ser\'es,  from  the  direction  of  its  filires  downwards 
and  inwards  from  the  radius  to  the  ulna,  to  transmit  the  weight  of  the  body  from 
the  ulna  to  the  radius  in  the  extended  position  of  the  elbow,  as  in  pushing  forwards 
with  the  arms  extended,  or  in  supporting  one's  own  weight  on  the  hands,  the  ulna 
being  in  close  contact  with  the  humerus,  but  scarcely  at  all  with  the  carpus;  Avhile 
the  radius  is  scarcely  in  contact  with  the  humerus,  but  in  close  contact  with  the 
carpus.  Hence  the  weight  transmitted  l)y  the  ulna  is  communicated  to  the  radius 
l)y  the  tightening  of  the  interosseous  membrane.  Conversely,  it  falls  upon  the  hand 
with  the  arm  extended,  the  interosseous  membrane  acting  as  a  sling  to  break  the 
violence  of  the  shock,  and  preventing  the  whole  force  of  the  impact  from  expend- 
ing itself  directly  upon  the  capitellum. 


6.  THE  RADIO-CARPAL  ARTICULATIOX 

Class. — Dimihrosis.  Subdivision. — Condi/larthrosis. 

The  wrist-joint  is  formed  by  the  union  of  the  radius  and  triangular  fil)ro-car- 
tilage  above,  articulating  with  the  scaphoid,  semilunar,  and  cuneiform  l)ones  lielow; 
the  ulna  being  excluded  by  the  intervention  of  the  triangular  fibro-cartilage.  The 
radius  and  triangular  cartilage  together  i)resent  a  smooth  surface,  slightly  concave 
both  from  before  backwards,  and  from  side  to  side;  whilst  the  three  l)ones  of  the 


284 


THE  A  R  TICULA  TIOXS 


ciirpus  present  a  smooth,  convex  surface,  made  uniformly  even  by  the  interosseous 
ligaments  which  hind  them  together. 

The  capsule  of  the  Avrist-joint  has  been  usually  described  as  four  separate  liga- 
ments, and  it  will '  be  convenient  for  the  sake  of  a  complete  description  to  follow 
this  method;  but  it  must  be  understood  that  these  four  portions  are  continuous 
around  the  joint,  extending  from  styloid  process  to  styloid  process  on  both  its 
aspects. 

The  four  portions  are: — ■ 


Anterior  radio-carpal. 
Posterior  radio-carjtal. 


Internal  lateral. 
External  lateral. 


Tlie  anterior  radio-carpal  (fig.  231)  is  a  thick  strong  ligament,  attached 
superiorlv  to  the  radius  immediately  above  the  margin  of  the  terminal  articular 
facet,  to  the  curved  ridge  at  the  root  of  the  styloid  process  of  the  radius,  and  to  the- 
anterior  margin  of  the  triangular  cartilage,  blending  with  some  fibres  of  the  capsule 


Fio.  "i;}!. — AxTKinuK  View  of   Wrist. 


Anterior  radio-ulnar 
ligament 

Internal  lateral  liga- 
ment of  wrist 
Flexor  carpi  ulnaris 


^External  lateral  ligament 
of  wrist 

Anterior  radio-earpal 

ligament 

Tendon  of  flexor  carpi 

radialis 


Capsular  ligament  of  first 
carpo-metacarpal  joint 


*/   f,  X) 


of  the  inferior  radio-ulnar  joint.  It  passes  downwards  and  inwards  to  be  attached 
to  both  rows  of  carpal  bones,  especially  the  second,  and  to  the  anterior  intercarpal 
ligament.  The  strongest  and  most  oblique  fibres  arise  from  the  root  of  the  styloid 
process  of  tlie  radius,  and  pass  oblicjuely  over  the  scaphoid,  with  which  only  a  few 
fibres  are  connected,  to  lie  inserted  into  the  semilunar,  magnum,  and  cuneiform 
bones.  Another  set,  less  oblique,  ))asses  from  the  margin  of  the  facet  for  the 
semilunar  to  be  attaclied  to  the  adjacent  parts  of  the  magnum,  unciform,  and 
cuneiform  bones.  Between  the  two  sets  of  fil)res,  small  vessels  pass  into  the  joint. 
Tiic  posterior  radio-carpal  ligament  (fig.  232)  is  attached  above  the  dorsal 
edge  ot  tlie  lower  end  of  the  radius,  the  back  of  the  styloid  process,  and  the 
posterior  margin  of  the  fibro-cartilage.  It  passes  downwards  and  inwards  to  be 
connected  with  the  first  row  of  the  carpal  bones,  chiefly  with  the  semilunar  and 
cuneiform,  and  the  ])Osterior  intercarpal  ligament.  This  ligament  is  thin  and 
membranous,  and  is  strengthened  by  (i)  strong  fibres  passing  from  the  back  of  the 
fibro-cartilage,  where  they  are  blended  with  the  posterior  inferior  radio-ulnar  liga- 
ment, and,  from  the  edge  of  the  radius  just  behind  the  lesser  sigmoid  fossa,  to  the 
cuneiform  bone;   (ii)  from  the  ridge  and  groove  for  the  extensor  secundi  internodii 


THE  RADIO-CARPAL 


235 


pollicis  to  the  back  of  the  semilunar  and  cuneiform  bones;  and  (iii)  from  the 
groove  for  the  radial  extensors  to  the  back  of  the  scaphoid  and  semilunar.  It  is 
in  relation  with,  and  strengthened  V)y,  the  extensor  tendons  which  pass  over  it. 

The  internal  lateral  ligament  (fig.  232)  is  fan-shaped,  with  its  apex  above,  at 
the  styloid  process  of  the  ulna,  to  which  it  is  attached  on  all  sides,  blending  witli 
the  apex  of  the  fibro-cartilage.  Some  of  the  fibres  pass  forwards  and  outwards  to 
the  base  of  the  i)isiform  bone  and  to  the  inner  part  of  the  upper  border  of  th(^ 
anterior  annular  ligament,  where  it  is  attached  to  the  pisiform  bone;  they  form  a 
thick,  rounded  fasciculus  on  the  front  of  the  wrist.  Other  filjres  descend  verti- 
cally to  the  inner  side  of  the  cuneiform  bone,  and  others  again  outwards  to  the 
dorsal  surface  of  the  cuneiform.  The  tendon  of  the  extensor  carpi  nlnarh  is  pos- 
terior to,  and  passes  over,  part  of  the  fibres  of  the  ligament. 

The  external  lateral  ligament  (fig.  231)  consists  of  fibres  which  radiate  from 
the  fore  part  and  tip  of  the  styloid  process  of  the  radius.  Some  pass  downwards 
and  inwards,  in  front,  to  the  scaphoid  and  adjacent  edge  of  the  magnum;  some 
downwards,  a  little  forwards  and  inwards,  to  the  tubercle  of  the  scaphoid  and  ridge 

Fig.  232. — Postekiue  View  of  Wkist. 


Posterior  radio-earpa] 
ligament 


Capsule  of  earpo-meta- 
carpal  joint  of  thumb 


Posterior  radio- 
ulnar ligament 


Internal  lateral 
ligament  of  wrist 


of  the  trapezium ;  and  others  downwards  and  outwards  to  the  rough  dorsal  surface 
of  the  sca})lioid.  The  filn'es  of  this  ligament  are  not  so  long  and  strong,  nor  do 
they  radiate  so  much  as  those  of  the  internal  lateral  ligament.  It  is  in  relation 
with  the  radial  artery,  and  the  extensor  ossis  metacarpi  and  primi  internodii  pollicis, 
the  artery  separating  the  tendons  from  the  ligament. 

The  synovial  membrane  is  extensive,  but  does  not  usually  communicate  with 
the  synovial  membrane  of  the  inferior  radio-ulnar  joint,  being  shut  out  by  tlie 
triangular  (cartilage.  It  is  also  excluded,  in  almost  every  instance,  from  that  of  the 
carpal  joints  by  the  interosseous  ligaments  between  the  first  row  of  carpal  bones. 
The  styloid  process  of  the  radius  is  cartilage-covered  internalh",  and  forms  part  of 
the  articular  cavity,  while  that  of  the  ulna  does  not. 

The  arterial  supply  is  derived  from  the  anterior  and  posterior  carpal  arches,  the 
])osterior  division  of  the  anterior  interosseous,  from  twigs  direct  from  the  radial  and 
ulnar  arteries,  and  from  recurrent  branches  from  the  first  dorsal  interosseous. 

The  nerve-supply  is  derived  from  the  ulnar  and  median  in  front,  and  the  pos- 
terior interosseous  behind. 

Movements. — The  wrist  is  a  condyloid  joint,  the  carpus  forming  the  condyle. 
It  allows  of  movements  upon  a  transverse  axis,   i.e.  flexion  and  extension;  and 


236 


THE  ARTICr'LATIOXS 


around  an  antero-postorior  axis,  i.e.  abduction  and  adduction;  together  with  a 
combination  of  these  in  quick  succession — circuni(Uiction.  Lacking  only  rotation 
on  a  vertical  axis,  it  thus  possesses  most  of  the  movements  of  a  ball-and-socket 
joint,  without  the  weakness  and  liability  to  dislocation  which  are  peculiar  to  these 
joints.  This  deficiency  of  rotation  is  compensated  for  by  the  movements  of  the 
radius  at  the  radio-ulna'r  joints,  viz.  supination  and  pronation.  Its  strength  depends 
chiefly  upon  the  number  of  tendons  which  pass  over  it,  and  the  close  connection 
whicli  exists  between  the  fibrous  tissue  of  their  sheaths  and  the  capsule  of  the  wrist; 
also  upon  the  proximity  of  the  medio-carpal  and  carpo-metacarpal  joints,  which 
permits  shocks  and  jars  to  be  shared  and  distributed  lietween  them;  another  source 
of  strength  is  the  absence  of  any  long  bone  on  the  distal  side  of  the  joint.  In  flexion 
and  extension  the  carpus  rolls  forwards  and  backwards  l^eneath  the  arch  formed  by 


Fig.  233.— Fkoxt  of  Wkist  with  Anteriok  .\nnular  Ligament. 


Anterior  radio-ulnar 
ligament 


Internal  lateral  ligament  of 
wrist  with  slip  to  annular 
ligament 


Anterior  annular  ligament 


Anterior  radio-carpal 
ligament 


Tendon  of  the  flexor 
carpi  radialis 


the  radius  and  fibro-cartilage;  flexion  being  limited  l)y  the  posterior  ligament  and 
posterior  portions  of  the  lateral;  extension  l)y  the  anterior,  and  anterior  portions 
of  the  lateral  ligaments.  In  adduction  and  abduction,  the  carpal  bones  glide 
from  without  inwards  and  from  within  outwards.  Abduction  is  more  limited 
than  adduction,  and  is  checked  by  the  internal  lateral  ligament  and  by  contact 
of  the  styloid  process  of  the  radius  with  the  trapezium;  adduction  is  checked  by 
the  external  lateral  ligament  alone.  One  reason  for  adduction  being  more  free 
than  aV)duction  is  that  the  ulna  does  not  reach  so  low  down  as  the  radius,  and  the 
yielding  filiro-cartilage  allows  of  greater  movement  upwards  of  the  inner  end  of  the 
carpus.  In  circumduction  the  hand  moves  so  as  to  describe  a  cone,  the  apex  of 
wliich  is  at  the  wrist.  These  movements  are  made  more  easy  and  extensive  by  the 
slight  gliding  of  the  carpal  bom-s  upon  one  another,  and  the  comparatively  free 
motion  at  the  medio-cari)al  joint.     The  ol)li(][ue  direction  of  the  fibres  of  the  lateral 


THE  CARPAL   JOINTS  237 

ligaments  prevents  any  rotation  at  the  radio-carpal  joint,  while  it  permits  consider- 
able freedom  of  abduction  and  adduction. 


7.  THE  CARPAL  JOINTS 

The  joint;?  of  the  carpus  may  be  subdivided  into — 

(a)  The  joints  of  the  first  row. 

(6)  The  joints  of  the  second  row. 

(c)    The  medio-carpal,  or  junction  of  the  two  rows  with  each  other. 

(a)  The  Union  of  the  First  Row  of  Carpal  Bones 

Class. — Diarthrosis.  Subdivision. — Arthrodia. 

The  bones  of  the  first  row,  the  pisiform  excepted,  are  united  by  two  sets  of 
ligaments  and  two  interosseous  fibro-cartilages. 

Dorsal.  Palmar. 

Interosseous  fibro-cartilages. 

The  two  dorsal  ligaments  extend  transversely  between  the  bones,  and  connect 
the  scaphoid  with  the  semilunar,  and  the  semilunar  with  the  cuneiform.  Their 
posterior  surfaces  are  in  contact  with  the  posterior  ligament  of  the  wrist. 

The  two  palmar  ligaments  extend  nearly  transversely  between  the  bones 
connecting  the  scaphoid  with  the  semilunar,  and  the  semilunar  with  the  cuneiform. 
They  are  stronger  than  the  dorsal  ligaments,  and  are  placed  beneath  the  anterior 
ligament  of  the  wrist. 

The  two  interosseous  fibro-cartilages  (fig.  235)  are  interposed  between  the 
scaphoid  and  semilunar,  and  the  semilunar  and  cuneiform  bones,  reaching  from 
the  dorsal  to  the  palmar  surfaces,  and  being  connected  with  the  dorsal  and  palmar 
ligaments.  They  are  narrow  fibro-cartilages  which  extend  between  small  portions 
only  of  the  osseous  surfaces.  They  help  to  form  the  convex  carpal  surface  of  the 
••adio-carpal  joint,  and  are  somewhat  wedge-shaped,  their  bases  being  towards  the 
wrist,  and  their  thin  edges  between  the  adjacent  articular  surfaces  of  the  bones. 

The  synovial  membrane  is  a  prolongation  from  that  of  the  medio-carpal  joint. 

The  arterial  and  nerve-supplies  are  the  same  as  for  the  medio-carpal  joint. 

The  Union  of  the  Pisiform  Bone  with  the  Cuneiform 

This  is  an  arthrodial  joint  which  has  a  loose  fibrous  capsule  attached  to  both 
the  pisiform  and  cuneiform  bones  just  beyond  the  margins  of  their  articular  surfaces. 
It  is  lined  by  a  separate  synovial  membrane.  Two  strong  rounded  or  flattened 
bands  pass  downwards  from  the  pisiform,  one  to  the  process  of  the  unciform,  and 
the  other  to  the  base  of  the  fifth  metacarpal  bone;  these  may  be  regarded  as 
prolongations  of  the  tendon  of  the  flexor  carpi  rdnaris,  and  the  pisiform  bone  may 
be  looked  upon  in  the  light  of  a  sesamoid  bone  developed  in  that  tendon. 

(b)  The  Union  of  the  Second  Row  of  Carpal  Bones 
Class. — Diarthrosis.  Subdivision. — Arthrodia. 

The  four  bones  of  this  row  are  united  by  three  dorsal,  three  palmar,  and  two 
interosseous  ligaments. 

The  three  dorsal  ligaments  (fig.  234)  extend  transversely  and  connect  the 
trapezium  with  the  trapezoid,  the  trapezoid  with  the  magnum,  and  the  magnum 
with  the  unciform. 


238 


THE  A  R  TIC  I  'LA  TIOXS 


The  three  palmar  ligaments  are  stronger  than  the  dorsal,  and  are  deeply  placed 
beneath  the  mass  of  extensor  tendons;  they  extend  transversely  between  the  bones 
in  a  similar  manner  to  the  dorsal  ligaments. 

The  two  interosseous  ligaments  are  situated  on  either  side  of  the  magnum, 
which  they  connect  with  the  trapezoid  on  the  outer,  and  the  unciform  on  the  inner, 
side.  That  between  the  magnum  and  trapezoid  is  attached  to  the  apposed  surfaces 
near  their  dorsal,  i.e.  the  posterior  aspect.  That  between  the  magnum  and  unci- 
form (tig.  235)  is  attached  to  the  apposed  surfaces  at  their  lower  and  anterior,  i.e. 
their  palmar  aspect. 

The  synovial  membrane  is  a  prolongation  of  that  lining  the  medio-carpal  joint. 

Tlie  arterial  and  nerve-supplies  are  the  same  as  for  the  medio-carpal  joint.     ■ 

(c)  Thk  Medio-carpal  Joixt,  or  the  Union  of  the  Two  Rows  of  the  Carpus 

WITH    each    other 

(I)   Class. — Diarthrosis.         Subdivision. — Arthrodia. 
(II)   Class. — Diarthrosis.         Subdivision. — Condylarthrosis. 

The  inferior  surfaces  of  the  bones  of  the  first  row  are  adapted  to  the  superior 
articular  surfaces  of  the  bones  of  the  second  roAV.  The  line  of  this  articulation  is 
concavo-convex  from  side  to  side,  and  is  sometimes  described  as  having  the  course 


Fig.  234.— Posterior  View  of  Wrist,  with  Capsule  cut  to  show  Articular  Surfaces. 


Transverse  dorsal  ligament 


Lower  end  of  interosseous 
ligament 


Inferior  oblique  ligament 


Triangular  fibro-cartilage 
-  Band  of  posterior  ligament  of 
■wrist   left   to   keep   bones  in 
situ 


Tendon  Hexor  carpi  ulnaris 


of  a  Roman  S  placed  horizontally  (/),  a  resem])lance  by  no  means  strained,  (i) 
The  outer  j)art  of  the  first  row  consists  of  tlie  scajjhoid  alone;  it  is  convex,  and  bears 
the  trapezium  and  trapezoid,  (ii)  Then  follows  a  transversely  elongated  socket 
formed  by  tlie  inner  part  of  the  scaphoid,  the  semilunar  and  cuneiform,  into  which 
are  received  (a)  the  head  of  the  magnum,  Avhich  articulates  with  the  scajihoid 
and  semilunar;  (b)  the  upper  and  outer  angle  of  the  unciform,  which  articulates 
Avith  the  semilunar;  and  (c)  the  upper  convex  portion  of  the  internal  surface  of 
the  unciform,  which  articulates  Avith  the  external  and  concave  portion  of  the  inferior 
surface  of  the  cuneif(^rm.  (iii)  The  innermost  part  of  the  inferior  surface  of  the 
cuneiform  bone  is  convex,  and  turned  a  little  backwards  to  fit  into  the  lower  portion 
of  the  internal  surface  of  the  unciform,  Avhich  is  a  little  concave  and  turned  for- 
Avards  to  receive  it.      Tlie  central  part,  Avhich  forms  a  socket  for  the   magnum  and 


THE  CARPAL   JOINTS 


239 


unciform,  has  somewhat  the  character  of  a  condyloid  joint,  the  os  magnum  and 
unciform  being  the  condyle,  to  fit  into  the  cavity  formed  by  tlie  .scai)li()id,  semi- 
lunar, and  cuneiform;  the  other  portions  are  typically  artln-ddial.  The  ligament.s 
are:  (1)  anterior  medio-carpal ;  (2)  posterior  medio-carpal ;  fo)  transverse 
dorsal. 

The  anterior  o;-  palmar  medio-carpal  is  a  ligament  of  considerable  strength, 
consisting  mostly  of  til)res  wliich  radiate  from  the  magnum  to  the  scajjhoid,  semi- 
lunar, and  cuneiform;  some  few  fibres  connect  the  trapezoid  and  trapezium  with 


Fig.  235. — Synovial  Membranes  of  Wrist,  Hand,  and  Fingers. 


Synovial  sac  of  the  inferior  radio 
ulnar  joint 


Synovial  sac  of  the  carpus 


Synovial  sac,  occasionally  separate, 
for  the  fourth  and  fifth  metacar- 
pal bones 


Synovial  aac   of  the  wrist-joint 


Synovial  sac  of  the  carpo- 
metacarpal joint  of  the 
thumb 


Lateral  ligaments  of  the  metacarpo- 
phalangeal, and  inter-phalaugeal 
joints 


the  sca})hoid,  an<l  others  pass  between  the  unciform  and  cuneiform.  It  is  covered 
over  juid  thickened  ])y  fibrous  tissue  derived  from  the  sheaths  of  the  flexor  tendons 
and  the  fibres  of  origin  of  the  small  muscles  of  the  thuml)  and  little  finger. 

The  posterior  or  dorsal  medio-carpal  ligament  consists  of  fibres  passing 
obliquely  from  the  bones  of  the  first  row  to  those  of  the  second.  It  is  stronger  on 
the  ulnar  side  than  on  the  radial,  but  is  not  so  strong  as  the  palmar  ligament. 

The  transverse  dorsal  ligament  (fig.  234)  is  an  additional  band,  well  marked 
an<l  often  of  considerable  strength,  which  passes  across  the  head  of  the   magnum 


240  THE  AfrnccLATioys 

from  the  scaplinid  to  the  cuneiform  hone;  hesides  hinding  down  the  head  of  the 
magnum,  it  serves  to  fix  the  upper  and  outer  angle  of  the  unciform  in  the  socket 
formed  l»y  the  lirst  row. 

The  dorsal  ligaments,  like  the  palmar,  are  strengthened  by  a  tjuantity  of  fibrous 
tissue  l)elonging  to  the  sheaths  of  the  extensor  tendons,  and  by  an  extension  of 
some  of  the  fibres  of  the  capsule  of  the  wrist.  There  are  no  proper  lateral  medio- 
carpal  ligaments;  they  are  luit  prolongations  of  the  lateral  ligaments  of  the  wrist. 

Tlie  synovial  membrane  (fig.  285)  of  the  carpus  is  common  to  all  the  joints  of 
the  carjius.  and  exti'uds  to  the  bases  of  the  four  inner  metacarpal  bones.  Thus, 
besides  lining  the  inter-  or  medio-carpal  joint,  it  sends  two  processes  upwards 
l)etween  the  three  bones  of  the  first  row,  and  three  downwards  between  the  con- 
tiguous surfaces  of  the  trai)ezoid  and  trapezium,  the  trapezoid  and  magnum,  and 
magnum  and  unciform.  From  these  latter,  prolongations  extend  to  the  four  inner 
carpo-metacar))al  joints  and  the  three  intermetacarpal  joints. 

The  arterial  supply  is  derived  from  (a)  the  anterior  and  posterior  carpal 
branches  of  the  radial  and  ulnar  arteries;  (6)  the  carpal  branch  of  the  anterior 
interosseous;  (c)  the  recurrent  branches  from  the  deep  palmar  arch.  The  terminal 
twigs  of  the  anterior  and  posterior  interosseous  arteries  supply  the  joint  on  its  dorsal 
aspect. 

Th(^  nerve-supply  comes  from  the  ulnar  on  the  ulnar  side,  the  median  on  the 
radial  side,  and  tlie  posterior  interosseous  behind. 

The  movements  of  the  carpal  articulations  between  bones  of  the  same  row  are 
very  limited  and  consist  only  of  slight  gliding  upon  one  another;  but,  slight  as  they 
are,  they  give  elasticity  to  the  carpus  to  break  the  jars  and  shocks  Avhich  result 
from  blows  or  falls  upon  the  hand. 

The  movements  of  one  row  of  bones  upon  the  other  at  the  medio-carpal  joint 
are  more  extensive,  especially  in  the  direction  of  flexion  and  extension,  so  that  the 
hand  enjoys  a  greater  range  of  these  movements  than  is  permitted  at  the  wrist-joint 
alone.  At  the  wrist,  extension  is  more  free  than  flexion;  but  this  is  balanced  by 
the  greater  freedom  of  flexion  than  of  extension  at  the  medio-carpal  joint,  and  by 
flexion  at  the  carpo-metacarpal  joint,  so  that  on  the  whole  the  range  of  flexion  of 
the  hand  is  greater  than  that  of  extension. 

A  slight  amount  of  lateral  motion  accompanied  by  a  limited  degree  of  rotation 
also  takes  place;  this  rotation  consists  in  the  head  of  the  magnum  and  the  superior 
and  outer  angle  of  the  unciform  bone  rotating  in  the  socket  formed  by  the  three 
bones  of  the  upper  row,  and  in  a  gliding  forwards  and  backwards  of  the  trapezium 
and  trapezoid  upon  the  scaphoid. 

In  addition  to  the  ligaments,  the  undulating  outline  and  the  variety  of  shapes  of 
the  apposed  facets  render  this  joint  very  secure. 

Bearing  in  mind  the  mobility  of  this  medio-carpal  joint  and  of  the  carpo- 
metacarpal, Ave  see  at  once  the  reason  for  the  radial  and  ulnar  flexors  and  extensors 
of  the  caqjus  being  prolonged  down  to  their  insertion  into  the  base  of  the  meta- 
carpus, for  they  produce  the  combined  effect  of  motion  at  each  of  the  three 
transverse  articulations:  (1)  at  the  wrist;  (2)  at  the  medio-carpal;  (3)  at  the 
carpo-metacarpal  joints. 


8.  THE  CARPO-METACARPAL  JOINTS 
These  may  l)e  divided  into  two  sets,  namely: — 

(a)  The  carpo-metacarpal  joints  of  the  four  inner  fingers. 
(/))  The  carpo-metacarpal  joint  of  the  thumb. 

The  inferior  surfaces  of  three  of  the  bones  of  the  second  row  of  the  carpus 
present  a  composite  surface  for  the  four  inner  metacarpal  bones;  the  trapezium 
presents  a  distinct  and  separate  saddle-shaped  surface  for  the  base  of  the  meta- 
carpal bone  of  the  thumb. 


THE  CARPO-METACARPAL  JOINTS  241 

(a)  The  Four  Inner  Carpo-metacarpal  Joints 
Class . — Dia  rtJi  /-o^/.i'.  Subdivision . — Arth  roduL . 

These  joints  exist  between  the  trapezium,  trapezoid,  magnum,  and  unciform 
1  tones  above,  and  tlie  four  inner  metacarpal  bones  below.  The  ligaments  Avhich 
unite  them  are,  dorsal,  palmar,  and  interosseous. 

The  dorsal  ligaments  (fig.  234). — Three  dorsal  ligaments  pass  to  the  second 
metacari»al  l»one:  one  from  each  of  the  carpal  l)ones  with  which  it  articulates, 
viz.  the  trapezium,  trapezoid,  and  magnum.  Two  dorsal  bands  pass  from  the 
magnum  to  the  third  metacarpal  bone.  Tavo  dorsal  bands  pass  to  the  fourth  bone : 
viz.  one  from  the  unciform,  and  another  from  the  magnum;  the  latter  is  sometimes 
wanting.     The  fifth  l)one  has  only  one  band  passing  to  it  from  the  unciform. 

The  palmar  ligaments  (fig.  231). — One  strong  band  passes  from  the  second 
metacarpal  bone  to  the  trapezium  internal  to  the  ridge  for  the  annular  ligament;  it 
is  covered  by  the  sheath  of  \\\ii  flexor  carpi  radialis. 

Three  bands  pass  from  the  third  metacarpal:  one  outwards  to  the  trapezium,  a 
middle  one  upwards  to  the  magnum,  and  a  third  inwards  over  the  fourth  to  reach 
the  fifth  metacarpal  and  the  unciform  bones. 

One  ligament  connects  the  fourth  bone  to  the  unciform. 

One  ligament  connects  the  fifth  bone  to  the  unciform,  the  fibres  extending 
internally,  and  connecting  the  dorsal  and  palmar  ligaments.  The  ligament  to  the 
fifth  l)one  is  strengthened  in  front  by  the  prolonged  fil^res  of  the  flexor  carpi  ulnaris 
and  the  strong  inner  slip  of  the  ligament  of  the  third  metacarpal  Ijone;  and  poste- 
riorly, by  the  tendon  of  the  extensor  carpi  tdnaris. 

The  interosseous  ligament  (fig.  235)  is  limited  to  onej)artof  the  articulation, 
and  consists  of  short  strong  fibres  connecting  the  contiguous  angles  of  the  unciform 
and  magnum  with  the  third  and  fourth  metacarpal  bones  towards  their  palmar 
aspect.  There  is,  however,  a  thick  strong  ligament  connecting  the  edge  of  the 
trapezium  with  the  outer  border  of  the  base  of  the  second  metacarpal  ])one;  it  helps 
to  separate  the  carpo-metacarpal  joint  of  the  thumb  from  the  common  carpo-meta- 
(•ar])al  joint,  and  to  close  in  the  radial  side  of  the  latter  joint. 

The  synovial  membrane  is  a  continuation  of  the  medio-carpal  joint;  occa- 
sionally there  is  a  separate  membrane  between  the  unciform  and  fourth  and  fifth 
metacarpal  bones  (fig.  235);  while  that  between  the  fourth  and  magnum  is  lined 
by  the  synovial  sac  of  the  common  joint. 

The  arteries  to  the  four  inner  carpo-metacarpal  joints  are  as  follows: — 

(1)  Fur  the  index  finger:  twigs,  are  suppliecl  by  the  trunk. of  the  radial  on  the 
dorsal  and  palmar  aspects,  the  metacarpal,  the  dorsalis  indicis,  and  the  radialis 
indicis. 

(2)  For  the  middle  finger:  the  metacarpal,  first  dorsal  interosseous  by  the 
V)ranch  which  passes  upwards  to  join  the  posterior  carpal  arch,  and  a  branch  from 
the  deep  palmar  arch  which  joins  the  anterior  carpal  arch. 

(3)  For  the  ring  finger:  the  deep  palmar  arch  and  recurrent  tAvigs  from  the 
second  dorsal  interosseous  in  the  same  manner  as  for  the  middle  finger. 

(4)  For  the  little  finger:  the  ulnar  and  its  deep  branch;  also  twigs  from  the 
second  dorsal  interosseous. 

The  nerves  are  supplied  to  these  joints  by  the  deep  palmar  branch  of  the  ulnar, 
the  posterior  interosseous,  and  the  median. 

The  movements  permitted  at  these  joints,  though  slight,  serve  to  increase  those 
of  the  medio-cari^al  and  wrist-joints.  The  joint  between  the  fifth  metacarpal  and 
the  unciform  bones  approaches  somewhat  in  shape  and  mobility  the  first  carpo- 
metacarpal joint;  it  has  a  greater  range  of  flexion  and  extension,  but  its  lateral 
movement  is  nearly  as  limited  as  that  of  the  three  other  metacarpal  bones;  the 
process  of  the  unciform  bone  limits  its  flexion.  Lateral  motion  towards  the  ulnar 
side  is  checked  by  the  strong  palmar  liand  which  unites  the  base  of  the  fifth 
metacarpal  to  the  base  of  the  third,  and  the  strong  transverse  ligament  at  the  head 
of  the  bones.  The  mobility  of  the  second,  third,  and  fourth  metacarpal  bones 
is  very  limited,  and  consists  almost  entirely  of  a  slight  gliding  upon  the  carpal 
bones,  i.e.  flexion  and  extension;  that  of  the  third  and  fourth  bones  is  extremely 
16 


242  THE  ARTirVLATIOXS 

slitrht,  as  there  is  no  Ion,?  flexor  attached  to  either;  ))Ut,  owing  to  the  close  connec- 
tion of  the  bases  of  the  nietacarpal  l)ones,  the  radial  and  ulnar  flexors  and  ex- 
tensors of  the  carpus  act  on  all  by  their  i)ull  on  the  particular  l>one  into  whicli 
they  are  inserted. 

Abduction,  or  movement  toward  the  radial  side,  is  i)revented  by  the  impaction 
of  the  second  ))one  against  the  trapezium;  a  little  adduction  is  permitted,  and  is 
favoured  l)y  the  slope  given  to  the  unciform  and  fifth  metacarpal  bones. 

There  is  also  a  slight  gliding  between  the  fourth  and  fifth  bones,  when  the 
concavity  they  present  towards  the  palm  is  deepened  to  form  the  'cup  of  Diogenes.' 

(6)  The  Carpo-metacarpal  Joint  of  the  Thumb 
Class. — Diarthrosis.  Subdivision. — Saddle- shaped  Arthrodia. 

The  bones  entering  into  this  joint  are  the  base  of  the  first  metacarpal,  and  the 
trapezium.  The  first  metacarpal  bone  diverges  from  the  other  four,  contrasting 
very  strongly  with  the  position  of  the  great  toe.  It  is  due  to  this  divergence  that 
the  thumb  is  able  to  be  opposed  to  each  and  all  the  fingers.  The  ligament  which 
unites  the  bones  is  the 

Capsular. 

The  capsular  ligament  (figs.  231  and  232)  consists  of  fibres  which  pass  from 
the  margin  of  the  articular  facet  on  the  trapezium,  to  the  margin  of  the  articular 
facet  at  the  base  of  the  first  metacarpal  bone.  The  fibres  are  stronger  on  the  dorsal 
than  on  the  palmar  aspect.  They  are  not  tense  enough  to  hold  the  bones  in  close 
contact,  so  that  while  they  restrict  they  do  not  prevent  motion  in  any  direction. 
The  internal  fibres  are  stronger  than  the  external. 

The  synovial  membrane  is  lax,  and  distinct  from  the  other  synovial  mem- 
branes of  the  carpus. 

The  arteries  of  the  carpo-metacarpal  joint  of  the  thumb  are  derived  from  the 
trunk  of  the  radial,  the  arteria  princeps  pollicis,  and  the  dorsales  pollicis. 

The  nerves  are  supplied  l)y  the  Ijranches  of  the  median  to  the  thumb. 

The  movements  of  tliis  joint  are  regulated  by  the  shape  of  the  articular  sur- 
faces, rather  than  l)y  the  ligaments,  and  consist  of  flexion,  extension,  abduction, 
adduction,  and  circumduction,  but  not  rotation.  In  flexion  and  extension  the 
nietacarpal  bone  slides  to  and  fro  upon  the  trapezium;  in  abduction  and  adduction 
it  slides  from  side  to  side  or,  more  correctly,  revolves  upon  the  antero-posterior  axis 
of  tlie  joint.  The  power  of  opposing  the  thumb  to  any  of  the  fingers  is  due  to  the 
forward  and  iuAvard  obli<iuity  of  its  flexion  movement,  which  is  by  far  its  most 
extensive  motion.  Abduction  is  very  free,  while  adduction  is  limited  on  account 
of  the  proximity  of  the  second  metacarpal  bone.  The  movement  of  the  trapezium 
upon  the  rest  of  the  cari)us  somewhat  increases  the  range  of  all  the  movements  of 
the  thumb. 

9.   THE  INTERMETACARPAL  ARTICULATIONS 
Class. — Diarthrosis.  Subdivision. — ArtJirodia. 

Tlie  metacarpal  of  the  thumb  is  not  connected  with  any  other  metacarpal  bone. 
The  second,  third,  fourth,  and  iifth  metacarpal  l>ones  are  in  actual  contact  at  their 
bases,  and  are  held  firmly  together  l)y  the  following  ligaments : — 

Dorsal.  Palmar. 

Interosseous  ligaments. 

The  dorsal  ligaments  (  fig.  233)  are  layers  of  varial)le  thickness  of  strong,  short 
fibres,  wliich  ])ass  transversely  from  bone  to  bone,  filling  up  the  irregularities  on 
the  dorsal  sm-faccs. 

The  palmar  ligaments  are  transverse  layers  of  ligamentous  tissue  passing  from 


THE  METACARPO-PHALAXGEAL  JOINTS  243 

bone  to  bone;  they  cannot  l)e  well  differentiated  from  the  other  ligaments  and 
fil)rous  tissue  eoverinw;  the  1  tones. 

The  interosseous  ligaments  (fig.  23o)  pass  between  the  apposed  surfaces  of 
the  bones,  and  are  attached  to  the  distal  sides  of  the  articular  facets,  so  as  to  close 
in  the  synovial  cavities  on  this  aspect;  where  there  are  two  articular  facets,  the 
fibres  extend  upwards  lietween  them,  nearly  as  far  as  their  carpal  facets.  That 
between  the  fourth  and  fifth  is  the  weakest. 

The  arteries  to  the  intermetacarpal  joints  are  twigs  from  the  palmar  and  dorsal 
interosseous  arteries;  the  twigs  pass  upwards  between  the  interosseous  muscles. 

The  nerves  are  derived  from  the  ulnar  and  the  posterior  interosseous. 

The  synovial  membrane  is  prolonged  downwards  from  the  common  carpal  sac. 

The  Union  of  the  Heads  of  the  Metacarpal  Bones 

The  distal  extremities  of  these  bones  are  connected  together  on  their  palmar 
aspects  by  what  is  called  the  transverse  ligament.  This  consists  of  three  short 
bands  of  fibrous  tissue,  which  unite  the  second  and  third,  third  and  fourth,  and  the 
fourth  and  fifth  bones.  They  are  rather  more  than  a  quarter  of  an  inch  (6  mm.) 
deep,  and  rather  less  in  width,  and  limit  the  distance  to  which  the  metacarpal  bones 
can  be  separated.  They  are  continuous  above  with  the  fascia  covering  the  inter- 
osseous muscles;  below,  they  are  connected  with  the  subcutaneous  tissue  of  the 
Aveb  of  the  hand.  They  are  on  a  level  with  the  front  surfaces  of  the  bones,  and  are 
l)lended  on  either  side  with  the  edges  of  the  glenoid  ligament  in  front,  with  the 
lateral  ligaments  of  the  metacarpo-phalangeal  joint,  and  also  with  the  sheaths  of 
the  tendons.  In  front,  a  lumbrkal  muscle  passes  with  the  digital  artenes  and 
nerves;  while  behind,  the  interossei  muscles  pass  to  their  insertions. 


10.  THE  METACARPO-PHALANGEAL  .JOINTS 

(a)  The  ]Metacarpo-phalangeal  Joints  of  the  Four  Inner  Fingers 

Class. — Diarthrosis.  Subdivision. — Condylaiihrosis. 

In  these  joints  the  cup-shaped  extremity  of  the  base  of  the  first  phalanx  fits 
on  to  the  rounded  head  of  the  metacarpal  bone,  and  is  united  by  the  following 
ligaments: — 

Lateral.  Glenoid. 

The  glenoid  ligament  (fig.  236)  is  a  fibro-cartilaginous  plate  which  seems  more 
intended  to  increase  the  depth  of  the  phalangeal  articular  facet  in  front,  than  to 
unite  the  two  bones.  It  is  much  more  firmly  attached  to  the  margin  of  the  phalanx 
than  to  the  metacarpal  bone,  being  only  loosely  connected  with  the  palmar  surface 
of  the  latter  by  some  loose  areolar  tissue  which  covers  in  the  synovial  sac,  here 
prolonged  upon  the  surface  of  the  bone  some  little  distance.  Laterally,  it  is 
connected  with  the  lateral  ligaments  and  the  transverse  metacarpal  ligament.  It 
corresponds  to  the  sesamoid  bones  of  the  thumb;  a  sesamoid  bone  sometimes  exists 
at  the  inner  border  of  the  joint  of  the  little  finger. 

The  lateral  ligaments  (figs.  235  and  236)  are  strong  and  firmly  connect  the  bones 
with  one  anotlier;  each  is  attached  above  to  the  lateral  tubercle,  and  to  a  depression 
in  front  of  the  tubercle,  of  the  metacarpal  bone.  From  this  i)oint  the  fibres  spread 
widely  as  they  descend  on  the  side  of  the  base  of  the  ])halanx;  the  anterior  fibres 
are  connected  with  the  glenoid  ligament;  the  posterior  blend  with  the  tendinous 
expansion  at  the  l>ack  of  the  joint. 

The  joint  is  covered  in  posteriorly  by  the  expansion  of  the  extensor  tendon,  and 
some  loose  areolar  tissue  passing  from  its  under  surface  to  the  bones  (fig.  236). 

The  synovial  sac  is  loose  and  capacious,  more  especially  over  the  base  of  the 
phalanx  behind,  and  tlie  head  of  the  metacarpal  bone  in  front. 

The  arteries  come  from  the  digital  or  anterior  interosseous  vessels  of  the  deep 
arch. 


244 


THE  ARTICULATIONS 


The  nerves  are  derived  from  tlie  digital  branches,  or  from  twigs  of  the  branches 
of  the  uhiar  to  the  interosseous  muscles. 

The  movements  permitted  at  these  Joints  are:  flexion,  extension,  abduction, 
adduction,  and  circumduction.  Flexion  is  the  most  free  of  all,  and  may  be  con- 
tinued until  the  jihalanx  is  at  a  right  angle  with  the  metacarpal  bone.  It  is  on  this 
account  that  the  articular  surface  of  the  head  of  the  bone  is  prolonged  so  much 
furtlier  on  the  palmar  aspect,  and  that  the  synovial  sac  is  here  so  loose  and  ample. 
Extension  is  the  most  limited  of  the  movements,  and  can  only  be  carried  to  a  little 
beyond  the  straiglit  line.  Abduction  and  adduction  are  fairly  free,  V»ut  not  so  free 
as  flexion.  Flexion  is  associated  with  adduction,  and  extension  with  abduc- 
tion. This  may  be  proved  by  opening  the  hand,  when  the  fingers  involuntarily 
separate  as  they  extend,  while  in  closing  the  fist  they  come  together  again.  The 
free  abduction,  adduction,  and  circumduction  which  are  permitted  at  these  joints 
are  due  to  the  fact  that  the  long  axes  of  the  articular  facets  are  at  right  angles 
to  one  another. 

Fig.  236. — .Anterior  and  Posteeiok  View  of  Ligaments  of  the  Fingers. 


Transverse  ligament 
between  the  heads 
of  the  metacarpal 
bones 

Glenoid  ligament 
\\ —  Lateral  ligament 


Areolar  tissue 
capsule 

Lateral  ligament 


Glenoid  ligament 
Lateral  ligament 


Flexor  tendon 


Areolar  tissue 
capsule 
Lateral  ligament 

Extensor  tendon 


Flexor  tendon 


Slips  of  the  extensor  . 
tendon 


(h)  The  Metacarpo-phalangeal  Joint  of  the  Thumb 
Class. — Diarthrosis.  Subdivision. — Condylarthrosis. 

The  head  of  the  metacarpal  lione  of  the  thumb  differs  consideral)ly  from  the 
corresponding  ends  of  the  metacarpal  bones  of  the  fingers.  It  is  less  convex,  wider 
from  side  to  side,  the  ])almar  edge  of  the  articular  surface  is  raised  and  irregular, 
and  here  on  eitJKM-  side  of  the  median  line  are  the  two  facets  for  the  sesamoid  bones. 
The  base  of  the  first  jthalanx  of  the  thumb,  too,  is  more  like  the  base  of  the  second 
phalanx  of  one  of  the  other  fingers.     The  ligaments  are: — 

Lateral.  Posterior. 

Sesamoid  bones  in  place  of  a  glenoid  ligament. 


THE  INTERPHALANGEAL  245 

The  lateral  ligaments  are  short,  strong  bands  of  fibres,  which  radiate  from 
depressions  on  either  side  of  the  head  of  the  metacarpal  bone  to  the  base  of  the 
first  })halanx  and  sesamoid  bones.  As  they  descend  they  pass  a  little  forwards,  so 
that  the  tri-eater  nuinl)er  are  inserted  in  front  of  the  centre  of  motion. 

The  posterior  ligament  consists  of  scattered  fibres  which  pass  across  the  joint 
from  one  lateral  ligament  to  the  other,  completing  the  capsule  and  protecting  the 
synovial  sac. 

The  sesamoid  bones  are  two  in  number,  situated  on  either  side  of  the  middle 
line,  and  connected  together  by  strong  transverse  fibres  which  form  the  floor  of  the 
groove  for  the  long  flexor  tendon ;  they  are  connected  with  the  base  of  the  phalanx 
and  head  of  the  metacarpal  bone  by  strong  fibres.  Anteriorly  they  give  attach- 
ment to  the  short  muscles  of  the  thumb,  and  posteriorly  are  smooth  for  the  purpose 
of  gliding  over  the  facets.     The  lateral  ligaments  are  partly  inserted  into  their  sides. 

The  arteries  and  nerves  come  from  the  digital  branches  of  the  thumli. 

The  movements  are  chiefly  flexion  and  extension,  very  little  lateral  movement 
being  permitted,  and  that  only  when  the  joint  is  slightly  bent.  Thus  this  joint 
more  nearly  approaches  the  simple  hinge  character  than  the  corresponding  articu- 
lations of  the  fingers.  The  thumb  gets  its  freedom  of  motion  at  the  carpo- 
metacarpal joint;  the  fingers  get  theirs  at  the  metacarpo-phalangeal,  but  they  are 
not  endowed  with  so  much  freedom  as  the  thumb  enjoys. 


11.  THE  INTERPHALANGEAL  ARTICULATIONS 
Class, — Diarthrosis.  Subdivision. — G'mglynms. 

The  ligaments  which  unite  the  phalanges  of  the  thumb  and  of  the  fingers  are : — 
Glenoid.  Lateral. 

The  glenoid  ligament  (fig.  236),  sometimes  called  the  sesamoid  body,  is  very 
firmly  connected  with  the  base  of  the  distal  bone,  and  loosely,  by  means  of  fibro- 
areolar  tissue,  with  the  head  of  the  proximal  one.  It  blends  with  the  lateral 
ligaments  at  the  sides,  and  over  it  pass  the  flexor  tendons.  Occasionally  a  sesamoid 
bone  is  developed  in  the  cartilage  of  the  interphalangeal  joint  of  the  thumb. 

The  lateral  ligaments  (figs.  235  and  236)  are  strong  bands  which  are  attached 
to  the  rougli  depressions  on  the  sides  of  the  upper  phalanx,  and  to  the  projecting 
lateral  margins  of  the  lower  phalanx  of  each  joint.  They  are  tense  in  every 
position,  and  entirely  prevent  any  lateral  motion;  they  are  connected  posteriorly 
with  the  expansion  of  the  extensor  tendon. 

Posteriorly  (fig.  236)  the  joint  is  covered  in  by  the  deep  surface  of  the  extensor 
tendon,  and  a  little  fibro-areolar  tissue  extends  from  the  tendon,  and  thickens  the 
posterior  portion  of  the  synovial  sac,  completing  the  capsule. 

The  synovial  membrane  is  loose  and  ample,  and  extends  upwards  a  little  way 
along  the  shaft  of  tlie  proximal  bone. 

The  arteries  and  nerves  come  from  their  respective  digital  branches. 

The  movements  are  limited  to  flexion  and  extension.  Flexion  is  more  free, 
and  can  be  continued  till  one  bone  is  at  a  right  angle  to  the  other,  and  is  most  free 
at  the  junction  of  the  first  and  second  bones;  the  second  phalanx  can  be  flexed  on 
the  first  through  110°  to  115°  when  the  latter  is  not  flexed.  The  greater  freedom 
of  flexion  is  due  to  the  greater  extent  of  the  articular  surface  in  front  of  the  heads 
of  the  proximal  bones,  and  to  the  direction  of  the  fibres  of  the  lateral  ligaments, 
which  ])ass  a  little  forwards  to  their  insertion  into  the  distal  bone. 


246  THE  ARTICULATIOXS 


THE  ARTICULATIONS  OF  THE  LOWER  LI3IB 

The  articulations  of  the  lower  limb  are  the  following: — 

1.  The  hip-joint. 

2.  Tlie  knee-joint. 

3.  The  tibio-fibular  union. 

4.  The  ankle-joint. 

5.  The  tarsal  joints. 

6.  The  tarso-metatarsal  joints. 

7.  The  intermetatarsal  joints. 

8.  The  metatarso-phalangeal  joints. 

9.  The  interphalangeal  joints. 


1.  THE  HIP-JOINT 
Class. — Diarthrosis.  Subdivision. — Enarthrodia. 

The  hip  is  the  most  typical  example  of  a  ball-and-socket  joint  in  the  body,  the 
round  head  of  the  femur  being  received  into  the  cup-shaped  cavity  of  the  aceta- 
bulum. Both  articular  surfaces  are  coated  with  cartilage,  that  covering  the  head 
of  the  femur  being  thicker  above  where  it  has  to  l)ear  the  weight  of  the  body, 
and  thinning  out  to  a  mere  edge  below;  the  pit  for  the  ligamentum  teres  is  the 
only  part  uncoated,  but  the  cartilage  is  somewhat  heaped  up  around  its  margin. 
Covering  the  acetal)ulum,  the  cartilage  is  horseshoe-shaped,  and  thicker  above  than 
}>elow,  being  deficient  over  the  depression  at  the  bottom  of  the  acetabulum,  Avhere 
a  mass  of  fatty  tissue — the  so-called  synovial  or  Haversian  gland — is  lodged. 

The  ligaments  of  the  joint  are:^ 

Capsular.  Ligamentum  teres. 

Transverse.  Cotyloid  cartilage. 

Tlie  capsular  ligament  is  one  of  the  strongest  ligaments  in  the  body.  It  is 
large  and  somewhat  loose,  so  that  in  every  position  of  the  body  some  portion  of  it 
is  relaxed.  At  the  pelvis  it  is  attached,  superiorly,  to  the  base  of  the  anterior 
inferior  iliac  spine;  curving  backwards,  it  becomes  blended  Avith  the  deep  surface 
of  the  reflected  tendon  of  the  rectus  femoris ;  posteriorly,  it  is  attached  a  few  lines 
from  the  acetabular  rim;  and  below,  to  the  upper  edge  of  the  groove  between  the 
acetabulum  and  tuberosity  of  the  ischium.  Thus  it  reaches  the  transverse  liga- 
ment, being  firmly  l)len(led  with  its  outer  surface,  and  frequently  sends  fibres 
beyond  the  notch  to  blend  with  the  obturator  membrane.  Anteriorly  it  is  attached 
to  the  pubes  near  the  notch,  to  the  pectineal  eminence,  and  thence  backwards  to 
the  base  of  the  iliac  spine.  A  thin  strong  stratum  is  given  ofif  from  its  superficial 
aspect  behind;  this  extends  beneath  the  gluteus  minimus,  and  small  rotators,  to 
l)e  attached  above  to  the  dorsum  of  the  ilium  higher  than  the  reflected  tendon  of 
the  rectus,  and  posteriorly  to  the  ilium  and  ischium  nearly  as  far  as  the  sciatic 
notch.  As  this  expansion  passes  over  the  long  tendon  of  the  rectus,  the  tendon 
may  be  described  as  l)eing  in  part  contained  witliin  the  substance  of  the  capsule. 

At  the  femur,  the  capsular  ligament  is  fixed  to  the  anterior  portion  of  the  upper 
border  of  the  great  trochanter,  and  to  the  superior  cervical  tubercle.  Thence  it 
runs  down  the  spiral  line  as  far  as  the  inner  l)order  of  the  femur,  where  it  is  on  a 
level  with  the  lower  part  of  the  lesser  trochanter.  It  then  runs  upwards  and  back- 
wards along  an  obliipie  line  about  two-thirds  of  an  inch  (1-6  cm.)  in  front  of  the 
lesser  trochanter,  and  contiiuies  its  ascent  along  the  back  of  the  neck  nearly  }>arallel 
to  the  posterior  intertrochanteric  line,  and  from  one-half  to  two-thirds  of  an  inch 
(12  to  16  mm.)  above  it;  finally,  it  passes  nlong  the  inner  side  of  the  digital  fossa 
to  reach  the  anterior  sujjcrior  angle  of  the  great  trochanter. 


THE  HIP-JOINT 


247 


On  laying  open  the  capsule,  some  of  the  deeper  fibres  are  seen  reflected  upwards 
along  the  neck  of  the  femur,  to  be  attached  much  nearer  the  head:  these  are  the 
retinacula.  One  corresponds  to  the  upper,  and  another  to  the  lower  part  of  the 
sinral  line;  a  third  is  seen  at  the  upper  and  back  part  of  the  neck.  They  form  flat 
bands,  which  lie  on  the  femoral  neck. 

Superadded  to  the  capsule,  and  considerably  strengthening  it,  are  three  auxi- 
liary Ijands,  whose  fibres  are  intimately  blended  with,  and  in  fact  form  part  of,  the 
capsule,  viz.  tlie  ilio-femoral,   ischio-femoral,  and  pectineo-femoral  bands. 

The  ilio-femoral  (fig.  237)  is  the  longest,  widest,  and  strongest  of  the  bands. 
It  is  of  triangular  shape,  with  the  apex  attached  above  to  a  curved  line  on  the  ilium 
immediately  below  and  behind  the  anterior  inferior  spine,  and  its  base  below  to  the 
anterior  edge  of  the  greater  trochanter  and  to  the  spiral  line  as  far  as  the  inner  border 
of  the  shaft.  The  highest  or  outermost  fibres  are  coarse,  almost  straight,  and  shorter 
tlian  the  rest;  the  innermost  fibres  are  also  thick  and  strong,  but  oblique.     This 


Fig.  237. — Axteriok  View  of  the  Capsule  of  the  Hip-joixt. 


TendoB  of  rectus  pulled  up 


Tendino-troelianterie  band  passing 
between  rectus  and  vastus  externus 

Placed  on  the  weak  spot  of  capsule, 
which  is  sometimes  perforated  to 
allow  the  bursa  under  psoas  to  com- 
municate with  joint 

Ilio-femoral  band 

Pectineo-femoral  band 


varying  obliquity  of  the  fibres,  and  their  accumulation  at  the  borders,  explain  why 
this  band  has  been  described  as  the  Y-shaped  ligament.  About  the  centre  of  its  base, 
near  the  femoral  attachment,  is  an  aperture  transmitting  an  articular  twig  from 
the  transverse  branch  of  the  external  circumflex  artery. 

The  ischio-femoral  band  (fig.  238)  is  formed  of  very  strong  fibres  attached  all 
along  the  upper  border  of  the  groove  for  the  external  obturator,  and  to  the  iscliial 
margin  of  the  aceta1)ulum  above  the  groove.  Tlie  highest  of  these  incline  a  little 
upwards  as  tliey  pass  outwards  to  be  fixed  to  the  greater  trochanter  in  front  of  the 
insertion  of  the  pyriformis  tendon,  while  the  other  fibres  curve  more  and  more 
upwards  as  they  pass  outwards  to  their  insertion  at  the  inner  side  of  the  digital 
fossa,  blending  Avith  the  insertion  of  the  external  rotator  tendons.  "When  the  joint 
is  in  flexion  these  fibres  pass  in  nearly  straight  lines  to  their  femoral  attachment, 
and  spread  out  uniformly  over  the  head  of  tlie  fcnnn-;  but  in  extension  they  wind 


248 


THE  ARTICTLA  TIOXS 


over  the  ])ack  of  the  femur  in  a  zonular  manner,  embracing  the  posterior  aspect  of 
the  neck  of  the  femur. 

The  pectineo-femoral  band  (fig.  237)  is  a  distinct  but  narrow  set  of  fibres 
which  are  inclivi(hially  le.-s  marked  than  the  fibres  of  the  other  two  liands;  they  are 
fixed  al)ove  to  the  anterior  border  of  the  pectineal  eminence,  reaching  as  far  down 
as  the  pubic  end  of  the  cotyloid  notch.  Below,  they  reach  the  neck  of  the  femur, 
and  art^  fixed  aliove  and  behind  the  lowermost  fibres  of  the  ilio-femoral  band,  Avith 
which  they  blend. 

In  thickness  and  strength  the  cajisule  varies  greatly;  thus,  if  two  lines  be 
drawn,  one  from  the  anterior  inferior  spine  to  the  inner  border  of  the  femur  near 
the  lesser  trochanter,  and  the  other  from  the  anterior  part  of  the  groove  for  the 
external  oliturator  to  the  digital  fossa,  all  the  ligament  between  these  lines  on  the 
outer  and  upper  aspects  of  the  joint  is  very  thick  and  strong,  while  that  below  and 
to  the  inner  side,  except  at  the  narrow  pectineo-femoral  band,  is  thin  and  weak,  so 


Fig.  238. — Postekiok  View  of  the  Capsule  of  the  Hip-joint. 


Here  are  seen  the  reflected 
tendon  of  the  rectus  and 
the  triangular  'ilio-tro- 
ehanteric'  band 


Isehio-fenioral  band 
This  is  placed  on  the  weak 
portion  of  the  capsule 


that  the  li('ad()f  the  bone  can  be  seen  through  it.  The  capsule  is  thickest  in  the 
course  of  the  ilio-femoral  band,  towards  the  outer  part  of  which  it  measures  over  a 
quarter  of  an  inch  (6  mm.).  Between  the  ilio-femoral  and  ischio-femoral  bands 
the  capsule  is  very  strong,  and  with  it  here,  near  the  acetabulum  is  incorporated 
the  reflected  tendon  of  the  rectus,  and  here  also  a  triangular  band  of  fibres  runs 
downwards  and  forwards  to  be  attached  by  a  narrow  insertion  to  the  ridge  on  the 
front  liorder  of  the  greater  trochanter  near  the  gluteus  minimus  (the  ilio-trochan- 
tericband)  (fig.  238). 

The  eapsule  is  strengthened  also  at  this  point  bv  a  strono-  band  from  the  under 
surface  of  tlie  gluteus  minimus,  and  l)y  the  tendino-trochanteric  band  which 
passes  down  from  the  reflected  tendon  of  the  rectus  to  the  vastus  externus  (fig. 
237).  This  is  closely  l)lended  with  the  capsule  near  the  outer  edge  of  the  ilio- 
femoral ligament. 

The  thinnest  part  of  tlie  eapsule  is  Ijetween  the  pectineo-femoral  and  ilio-femoral 


THE  HIP-JOLXT 


241) 


bands;  this  is  sometimes  perforated,  allowing  the  l)ursa  nndcr  tlie  psoas  to  commu- 
nicate with  the  Joint.  The  capsule  is  also  very  thin  at  its  attachment  to  the  hack 
of  the  femoral  neck,  and  again  opposite  the  cotyloid  notch. 

The  ligamentum  teres  (figs.  289  and  240)  is  an  interarticular  flat  band  which 
extends  from  the  acetaljular  notch  to  the  head  of  the  femur,  and  is  usually  about 
an  inch  and  a  half  (3-7  cm.)  long.  It  has  two  bony  attachments,  one  on  either  side 
of  the  cotyloid  notch  immediatel}'  below  the  articular  cartilage,  while  intemiediate 
fibres  spring  from  the  under  surface  of  the  transverse  ligament.  The  ischial 
portion  is  the  stronger,  and  has  several  of  its  fibres  arising  outside  the  cavity, 
below  and  in  connection  with  the  origin  of  the  transverse  ligament,  Avhere  it  is 
also  continuous  with  the  capsule  and  periosteum  of  the  ischium.  At  the  femur 
it  is  fixed  to  the  front  part  of  the  depression  on  the  head,  and  to  the  cartilage 
round  the  margin  of  the  depression.  It  is  covered  by  a  prolongation  of  synovial 
membrane,  which  also  covers  the  cushion  of  fat  in  the  recess  of  the  acetabulum; 


Fig.  239. — Section  through  the  Hip-joixt,  showing  the  Cotyloid  Ligament, 

LlGAMEXTLM   TERES,    AND   RETIXACI'LA. 

'  ■  -  *>  .f  $  1 


Ligamentum  teres. 
The  upper  line  is 
placed  on  the  fem- 
oral, the  lower  on 
the  ischial  attach- 
ment 


Cotyloid  cartilage 


Capsular  ligament 
Reflected  fibres  of 
capsule      (retin- 
ae ula) 


Reflected  fibres  of 
capsule 


the  portion  of  the  membrane  reflected  over  the  fatty  tissue  does  not  cling  closely  to 
the  round  ligament,  but  forms  a  triangular  fold,  the  apex  of  which  is  at  the  femur. 

The  transverse  ligament  (fig.  241)  passes  across  the  cotyloid  notch  and  con- 
verts it  into  a  foramen ;  it  supports  part  of  the  cotyloid  fibro-cartilage.  and  is  con- 
nected Avith  the  ligamentum  teres  and  the  cai^sule.  It  is  composed  of  decussating 
fibres,  which  arise  from  the  margin  of  the  acetabulum  on  either  side  of  the  notch, 
those  coming  from  the  pubes  being  more  superficial,  and  passing  to  form  the  deep 
part  of  the  ligament  at  the  ischium,  while  those  superficial  at  the  ischium  are  deep 
at  the  pubes.     It  thus  comjiletes  the  rim  of  the  aceta1>ulum. 

The  cotyloid  fibro-cartilage  (figs.  239  and  240)  is  a  yellowish- white  structure, 
which  deepens  the  acetaltulum  l)y  surmounting  its  margin.  It  varies  in  strength 
and  thickness,  but  is  stronger  at  its  iliac  and  ischial  portions  than  elsewhere.  Its 
base  is  broad  and  fixed  to  the  ])ony  rim  as  well  as  to  the  articular  cartilage  of  the 
acetabulum  on  the  inner,  and  the  periosteum  on  the  outer  side  of  it,  and  blends 
inseparably  with  the  transverse  ligament  which  supports  it  over  the  cotyloid  notch. 
Its  free  margin  is  thin;  on  section  it  is  somewhat  lunated,  having  its  outer  surface 


250 


THE  ARTICULATIONS 


convex  and  its  articular  face  concave  and  very  smooth  in  adaptation  to  the  head  of 
the  bone,  which  it  tightly  embraces  a  little  beyond  its  greatest  circumference.  It 
somewhat  contracts  the  aperture  of  the  acetabulum,  and  retains  the  head  of  the 
femur  within  its  grasp  after  division  of  the  muscles  and  capsular  ligament.  It  is 
covered  on  both  aspects  by  synovial  membrane. 


Fig.  240. 


-Hip-joint  after  diviiuxg  the  Capsi'I,.\r   Ligament  and  disarticulating 
THE  Femur. 


Ligamentum  teres 


Capsular  ligament 


Capsular  ligament,  cut 
Cotyloid  ligament 


Capsular  ligament 


The  synovial  membrane  lines  the  capsule  and  both  surfaces  of  the  cotyloid 
ligament,  and  passes  over  the  border  of  the  acetabulum  to  reach  and  cover  the  fatty 
cushion  it  contains.  The  part  covering  the  fatty  cushion  is  unusually  thick,  and  is 
attached  round  the  edges  of  the  rough  bony  surface  on  which  the  cushion  rests. 
The  memljrane  is  loosely  reflected  off  this  on  to  the  ligamentum  teres,  along  which 


Fig.  241.— Portions  of  Ischium  and  Pubes,  showing  the  Cotyloid  Notch  and  the 
Ligamentum  Teres  attached  outside  the  Acetabulum. 


Transverse  ligament . 


Cotyloid  ligament 


Transverse  ligament 


Ligamentum  teres  attached 
to  ischium  outside  the 
acetabulum 


it  is  prolonged  to  the  head  of  the  femur;  thus  the  fibres  of  the  round  ligament  are 
shut  out  from  the  joint  cavity.  From  the  capsule  the  synovial  memlirane  is  also 
reflected  lielow  on  to  the  neck  (.f  the  femur,  whence  it  passes  over  the  retinacula  to 
the  margin  of  the  articular  cartilage.  A  fold  of  synovial  membrane  on  the  under 
aspect  of  the  neck  often  conveys  to  the  head  of  tlie  femur  a  branch  of  arterv — gen- 
erallv  a  branch  of  the  internal  circumflex. 


THE  HIP-JOIXT 


251 


The  arterial  supply  comes  from  (a)  the  transverse  branches  of  the  mternal 
and  external  circumtlex  arteries;  (6)  the  external  brancli  of  the  obturator  sends  a 
Vjranch  through  the  cotyloid  notch  beneath  the  transverse  ligament,  which  ramifies 
in  the  fat  at  the  bottom  of  the  acetabulum,  and  travels  down  the  round  ligament 
to  the  head  of  the  femur;  (c)  the  inferior  branch  of  the  deep  division  of  the  gluteal; 
and  {(1)  the  sciatic  arteries.  The  branch  from  the  obturator  to  the  ligamentum 
teres  is  sometimes  very  large  when  the  branch  from  the  internal  circumflex  does 
not  also  supply  the  ligament. 

The  gluteal  and  sciatic  send  several  branches  through  the  innominate  attach- 
ment of  the  capsular  ligament :  these  anastomose  freely  beneath  the  capsule  around 
the  outer  aspect  of  the  acetabulum,  and  supply  some  branches  to  enter  the  bone, 
and  others  which  enter  the  substance  of  the  cotyloid  ligament.  There  is  quite  an 
arterial  crescent  upon  the  posterior  and  postero-superior  portions  of  the  acetabulum; 
but  no  vessels  are  to  be  seen  on  the  inner  aspect  of  the  cotyloid  ligament. 

The  nerve-supply  comes  from  (a)  anterior  crural,  {h)  anterior  division  of  the 
obturator,  (c)  the  accessory  obturator,  and  (dl)  the  sacral  plexus,  by  a  twig  from 
the  nerve  to  the  quadratus  femoris,  or  from  the  upper  part  of  the  great  sciatic,  or 
from  the  lower  part  of  the  sacral  plexus. 

The  muscles  in  relation  with  the  hip-joint  are:  in  front,  the  psoaf<,  which  is 

Fig.  242. — Ligamentum  Teres,  lax  i.v  Flexiox. 


separated  from  the  capsule  by  a  bursa,  and  the  iliacus,  which  in  part  arises  from 
the  capsule;  above  are  the  straight  and  reflected  tendons  of  the  rectii.s:^  the  reflected 
tendon  being  enclosed  between  the  fibres  of  the  capsule,  and  a  band  which  passes 
down  from  the  reflected  tendon  to  the  vastus  extemus;  also  the  gluteus  minimus, 
which  is  closely  adherent  to  the  capsule;  above  and  Jaehind  are  the  piriformis, 
which  sometimes  sends  a  slip  into  the  capsule;  the  internal  obturator,  which  acts  as 
a  powerful  .strap  to  the  back  of  the  joint,  and  the  two  gemelli ;  below  and  behind 
is  the  external  obturator,  passing  over  the  capsule,  whilst  a  dense  band  of  filjro- 
cellular  tissue  connects  the  sheath  of  the  o1>turator  externus  with  the  capsule  along 
the  posterior  edgi-  of  the  nmscle;  internally  is  the  pedineus. 

The  movements. — The  hip-joint,  like  the  shoulder,  is  a  ball-and-socket  joint, 
but  with  a  much  more  complete  socket  and  a  corresjjonding  limitation  of  move- 
ment. Each  variety  of  movement  is  permitted,  \\z.  flexion,  extension,  abduction, 
adduction,  circumduction,  and  rotation;  and  any  two  or  more  of  these  movements 
not  being  antagonistic  can  be  combined,  i.e.  flexion  or  extension  associated  with 
abduction  or  adduction  can  be  combined  with  rotation  in  or  out. 

It  results  from  the  o1)liquity  of  the  neck  of  the  femur  that  the  movements  of 
the  head  in  the  acetabulum  are  always  more  or  less  of  a  rotatory  character.  This 
is  more  especially  the  case  during  flexion  and  extension,  and  two  results  follow 


252 


THE  ARTICTLATIOXS 


from  it.  First,  the  bearing  surfaces  of  the  femur  and  acetabulum  preserve  their 
apposition  to  each  other,  so  that  the  amount  of  articular  surface  of  the  head  in  the 
acctaljulum  does  not  sensibly  diminish  pari  passu  with  the  transit  of  the  joint 
from  the  extended  to  the  flexed  position,  as  would  necessarily  be  the  case  if  the 
movement  of  the  femoral  head,  like  that  of  the  thigh  itself,  was  simply  angular, 
instead  of  rotatory  and  angular.  ^Secondly,  as  rotation  of  the  head  can  continue 
until  the  ligaments  are  tight  without  being  checked  by  contact  of  the  neck  (jf  the 
thigh  l)one  witli  the  rim  of  the  acetabulum,  Hexion  of  the  thigh  so  far  as  the  joint 
is  concerned  is  practically  unlimited.  Flexion  is  the  most  important,  most  fre- 
quent, and  most  extensive  movement,  and  in  the  dissected  limb,  Ijefore  the  liga- 
ments are  disturbed,  can  be  carried  to  160°,  and  is  then  checked  by  the  lower  fibres 
of  the  ischio-femoral  ligament.  In  the  living  subject  simple  flexion  can  continue 
until  checked  by  the  contact  of  the  soft  parts  at  the  groin,  if  the  knee  be  bent;  if 
the  knee  be  straight,  flexion  of  the  hip  is  checked  in  most  persons  by  the  hamstring 
muscles  at  nearly  a  right  angle.     This  is  very  evident  on  trying  to  touch  the  ground 

Fig.  243.— Ligamentum  Teres,  very  lax  in  complete  Extension. 


with  the  fingers  without  bending  the  knees,  the  chief  strain  being  felt  at  the  pop- 
liteal space  Til  is  is  due  to  the  shortness  of  the  hamstrings.  Extension  is  limited 
by  the  ilio-fcmoral  ligament. 

Al)duction  and  outward  rotation  can  be  performed  freely  in  every  position  of 
flexion  and  extension — abduction  being  limited  by  the  pectineo-femoral  ligament; 
outward  rotation  by  the  ilio-femoral  ligament,  especially  its  inner  portion,  during 
extension;  but  by  ithe  outer  portion,  as  well  as  by  the  ligamentum  teres,  during 
flexion. 

Adduction  is  very  limited  in  the  extended  thigh  on  account  of  the  contact  with 
the  opposite  liml).  In  the  slightly  flexed  position  adduction  is  more  free  than  in 
extension,  and  is  then  limited  by  tlie  outer  fil)res  of  the  ilio-femoral  band  and  the 
su})erior  portion  of  the  ca])sule.  In  flexion  the  range  is  still  greater,  and  limited 
l)y  the  ischio-femoral  ligament,  the  ligamentum  teres  being  also  rendered  nearly 
tight.  Inward  rotation  in  the  nearly  extended  position  is  limited  by  the  ilio- 
femoral ligament;  and  in  flexion  by  the  ischio-femoral  ligament  and  the  portion  of 
the  capsule  between  it  and  the  ilio-femoral  band. 


THE  KNEE-JOIXT 


253 


The  ilio-fenioral  band  also  i)revents  the  tendency  of  the  trunk  to  roll  l)ackwarils 
on  the  thigh  bones  in  the  erect  posture,  and  so  does  away  with  the  necessity 
for  muscular  power  for  this  purpose;  it  is  put  on  stretch  in  the  stand-at-ease 
position. 

The  ligamentuni  teres  is  of  little  use  in  resisting  violence  or  in  imparting  strength 
to  the  joint.  It  assists  in  checking  rotation  outAvards,  and  adduction  during  flexion. 
A  ligament  can  only  be  of  use  when  it  is  tight,  and  it  was  found  by  trephining  the 

Fig.  244.— LiGAMEXTrM  Teres,  brawx  tight  ix  Flexion  combixed  with  Rotation 

OUTWARDS   AXD   ADDUCTION. 


bottom  of  the  acetabulum,  removing  the  fat,  and  threading  a  piece  of  whipcord 
round  the  ligament,  that  the  ligament  was  slack  in  simple  flexion,  and  very 
loose  in  complete  extension,  but  that  its  most  slack  condition  was  in  al)duction. 
It  is  tightest  in  flexion  combined  Avith  adduction  and  rotation  outwards,  and 
almost  as  tight  in  flexion  with  outward  rotation  alone,  and  in  flexion  with 
adduction  alone  (figs.  242  to  244 J. 


2.  THE  KXEE-JOIXT 


Class . — Diarth  rosis. 


Subdivision. —  Giaglymus. 


The  knee  is  the  largest  joint  in  the  body.  It  is  rightly  described  as  a  gingly- 
moid  joint,  but  there  is  also  an  arthrodial  element;  for,  in  addition  to  flexion  and 
extension,  there  is  a  sliding  backwards  and  forwards  of  the  tibia  upon  the  femoral 
condyles,  as  well  as  slight  rotation  round  a  vertical  axis.  It  is  one  of  the  most 
superficial,  and,  as  far  as  adaptation  of  the  bony  surfaces  goes,  one  of  the  weakest 
joints,  for  in  no  position  are  the  bones  in  more  than  partial  contact.  Its  strength 
lies  in  the  number,  size,  and  arrangement  of  the  ligaments,  and  the  powerful 
muscles  and  fascial  expansions  which  pass  over  the  articulation  and  enal:)le  it  to 
withstand  the  leverage  of  the  two  longest  bones  in  the  body.  It  may  be  said  to 
consist  of  two  articulations  Avith  a  common  synovial  membrane — the  patello- 
femoral  and  the  tibio-femoral,  the  latter  being  double.  It  is  comi)Osed  of  the 
condyles  and  trochlear  surface  of  the  femur,  the  tuberosities  of  the  tibia,  and  tlie 
patella,  united  by  the  following  ligaments,  which  may  be  divided  into  an  external 
and  internal  set: — 


254  THE  ARTICULATIONS 

External  Internal 

(1)  Fibrous  expansion  of  the  extensors.  (1)  Anterior  crucial. 

(2)  Capsular  or  anterior  ligament.  (2)  Posterior  crucial. 

(3)  Posterior  ligament.  (3)  Internal  semilunar  fibro-cartilage. 

(4)  External  lateral.  (4)  External  semilunar  fibro-cartilage. 

(5)  Internal  lateral.  (5)  Coronary. 

(6)  Ligamentum  patellae.  (6)  Transverse. 

External   Ligaments 

Superficial  to  the  fibrous  expansion  of  the  quadriceps  extensor  tendons  the 
fascia  lata  of  the  thigh  covers  the  front  and  sides  of  the  knee-joint. 

The  deep  fascia  of  the  thigh,  as  it  descends  to  its  attachment  to  the  tubercle  and 
oblique  lines  of  the  tibia,  not  only  overlies  but  blends  with  the  fibrous  expansion 
of  the  extensor  tendons. 

The  ol)lique  lines  of  the  tibia  curve  upwards  and  backwards  from  the  tubercle 
on  each  side  to  the  postero-lateral  part  of  the  tuberosities.  The  process  of  fascia 
attached  to  the  outer  ridge  of  the  tibia  and  to  the  head  of  the  fibula,  descends  from 
the  tensor  vaginae  femoris  and  is  very  thick  and  strong.  It  is  firmly  blended  with 
the  tendinous  fibres  of  the  vastus  externus.  The  fascia  lata,  on  the  inner  side  of  the 
patella,  besides  being  attached  to  the  inner  oblique  ridge  of  the  tibia,  sends  some 
longitudinal  fibres  lower  down  to  become  blended  Avith  the  fibrous  expansion  of  the 
sartorius.  The  fascia  is  much  thinner  on  the  inner  side  of  the  patella  than  on  the 
outer,  and  lilends  much  less  with  the  tendon  of  the  vastus  internus  than  the  outer 
part  of  the  fascia  does  with  the  vastus  externus.  A  thin  layer  of  the  fascia  lata  in 
the  form  of  transverse  or  arciform  fibres  passes  over  the  front  of  the  joint.  These 
fibres  are  specially  Avell  marked  .over  the  ligamentum  patellse,  and  blend  here 
with  the  central  portion  of  the  quadriceps  extensor  fibres. 

The  fibrous  expansion  of  the  extensor  tendons  consists  (1)  of  a  central  por- 
tion, densely  thick  and  strong,  an  inch  and  a  half  (3*7  cm.)  broad,  which  is  inserted 
into  the  anterior  two-thirds  of  the  upper  border  of  the  patella,  many  of  its  super- 
ficial fibres  passing  over  the  subcutaneous  surface  of  the  bone  into  the  ligamentum 
patella?;  (2)  of  two  lateral  portions  thinner,  but  strong.  The  lateral  portions  are 
inserted  into  the  patella  along  its  upper  border  on  either  side  of  the  central  portion 
and  also  into  its  lateral  borders,  nearer  the  anterior  than  the  posterior  surface,  as 
low  down  as  the  attachment  of  the  ligamentum  patellae;  passing  thence  along  the 
sides  of  the  ligamentum  patella?  to  the  tibia,  they  are  attached  to  the  oblique  lines 
which  extend  laterally  from  the  tubercle  to  the  inner  and  outer  tuberosities,  and 
reach  as  far  as  the  internal  and  external  lateral  ligaments.  On  the  outer  side,  the 
fibres  blend  with  the  ilio-til^ial  band  of  the  fascia  lata,  and  on  the  inner  they  extend 
below  the  oblique  line  to  blend  with  the  periosteum  of  the  shaft.  Thus  there  is  a 
large  hood  spread  over  the  whole  of  the  front  of  the  joint,  investing  the  patella,  and 
reaching  from  the  sides  of  the  ligamentum  patellfe  to  the  lateral  ligaments,  attached 
below  to  the  tibia,  and  separated  everywhere  from  the  synovial  membrane  by  a 
layer  of  fatty  tissue. 

The  ligamentum  patellae  (fig.  247)  is  the  continuation  in  line  of  the  central 
portion  of  the  conjoined  tendon,  some  fibres  of  which  are  prolonged  over  the  front 
of  the  patella  into  the  ligament.  It  is  an  extremely  strong,  flat  band,  attached 
above  to  the  lower  border  of  the  patella;  below,  it  is  fixed  to  the  lower  part  of  the 
tubercle  and  upper  part  of  the  crest  of  the  tibia,  somewhat  obUquely,  being  pro- 
longed downwards  further  on  the  outer  side,  so  that  this  border  is  fully  an  inch 
longer  tlian  the  inner  which  measures  tAVO  inches  and  a  half  (()-7  cm.)  in  length. 
Bebind,  it  is  in  contact  Avith  a  mass  of  fat  Avhich  separates  it  from  the  synovial 
membrane,  and  a  small  bursa  intervenes  between  it  and  the  head  of  the  tibia.  In 
front,  a  large  ]>ursa  sc])arates  it  from  the  subcutaneous  tissue,  and  laterally  it  is 
continuous  with  the  fibrous  expansion  of  the  extensors. 

The  internal  lateral  ligament  (fig.  245)  is  a  strong,  flat  band,  Avhich  extends 
from  the  depression  on  the  tubercle  on  the  inner  side  of  the  internal  condyle  of  the 


THE  KNEE-JOINT 


255 


femur,  to  the  inner  border  and  internal  surface  of  the  shaft  of  the  tibia,  an  inch  and 
a  half  (8-7  cm. )  below  the  tuberosity.  It  is  three  inches  and  a  half  (87  cm. )  long, 
well  defined  anteriorly,  where  it  l)lends  with  the  expansion  of  the  conjoined  extensor 
tendons;  but  not  so  Avell  defined  posteriorly,  where  it  merges  into  the  posterior 
ligament.  Some  of  the  lower  fibres  blend  with  the  descending  portion  of  the  seint- 
memhranoms  tendon.  Its  deep  surface  is  firmly  adherent  to  the  edge  of  the  internal 
semilunar  cartilage  and  coronary  ligament,  while  part  of  the  semimembranosus  tendon 
and  inferior  internal  articular  vessels  and  ner've  pass  between  it  and  the  bone.  Super- 
ficially, a  liursa  separates  it  from  the  tendons  of  the  gracilis  and  semitendinosus 
muscles  and  from  the  aponeurosis  of  the  sartorius  muscle. 

The  external  lateral  ligament  (fig.  245)  consists  of  two  portions:  the  anterior, 
which  is  the  longer  and  better  marked,  is  a  strong,  rounded  cord,  about  two  inches 
(5  cm. )  long,  attached  above  to  the  tubercle  on  the  outer  side  of  the  external  con- 


FiG.  245. — Posterior  View  of  the  Knee-joint. 


Outer  head  of  gastroeuemius 


External  lateral  ligament 
anterior  portion 


Posterior  part  of  external 
lateral  ligament 
Tendon  of  popliteus 


Tendon  of  biceps 


Posterior  superior  tibio- 
fibular ligament 


Tendon  of  adductor  magnus 


Inner  head  of 
gastrocnemius 


Tendon  of  semi-membra- 
nosus  with  its  slip  to 
thicken  the  posterior  liga- 
ment 


Internal  lateral  ligament 


dyle  of  the  femur,  just  below  and  in  front  of  the  origin  of  the  outer  head  of  the 
f/astrocnemius,  whilst  the  tendon  of  the  popliteus  arises  from  the  groove  below  and  in 
front  of  it.  Below,  it  is  fixed  to  the  middle  of  the  outer  surface  of  the  head  of  the 
fibula,  half  an  inch  (1-25  cm.)  or  more  anterior  to  the  styloid  process.  Super- 
ficially is  the  tendon  of  the  biceps,  which  splits  to  embrace  its  lower  extremity; 
while  beneath  it  pass  the  popliteus  tendon  in  its  sheath,  and  the  inferior  external 
articular  vessels  and  nerve.  Some  fibres  of  the  peroneus  longus  occasionally  arise 
from  the  lower  end  of  the  ligament.  The  posterior  jiortion  is  a  third  of  an 
inch  (8  mm.)  behind  the  anterior.  It  is  broader  and  less  defined;  fixed  below  to 
the  styloid  process,  it  inclines  u])wards  and  somewhat  Ixackwards,  and  ties  down  the 
popliteus  against  the  outer  tuljerosity,  l)lending  beneath  tlie  outer  head  of  the  r/a-s- 
trocnemius  with  the  ])osterior  ligament  of  the  knee,  of  which  it  is  really  a  portion. 

The  posterior  ligament  or  ligamentum  Winslowii  (fig.  245)  is  a  broad  dense 
structure  of   interlacing  fibres,  with  large    orifices    for  vessels  and  nerves.       It  is 


256 


THE  A  R  Tin  'LA  TIOXS 


attached  above  to  the  femur  close  to  the  articular  margins  of  the  condyles,  stretch- 
ing across  the  upper  margin  of  the  intercondyloid  notch,  to  which  it  is  connected 
by  tibro-fatty  tissue;  it  thus  reaches  across  from  the  internal  to  the  external 
lateral  ligaments.  Below,  it  is  fixed  to  the  border  of  the  outer  tuberosity  of  the 
til)ia,  to  the  bone  just  below  the  popliteal  notch,  and  to  the  shaft  of  the  tibia 
below  the  inner  tuberosity,  blending  with  the  descending  slip  of  the  semi- 
meinbranosHS  and  internal  lateral  ligament.  Superficially,  an  oblique  fasciculus 
from  the  seminicmbranosus  runs  across  the  centre,  passing  upwards  and  outwards 
from  near  the  l)ack  part  of  the  inner  tuberosity  of  the  tibia  to  the  external  condyle 
of  the  femur  where  it  joins  the  outer  head  of  the  gastrocnemius,  a  sesamoid  plate 
being  sometimes  developed  at  the  point  of  junction.     This  slip  greatly  strengthens 


Fig.  246. — Axteriok  View  of  the  Ixtekxal  Liga.mexts  of  the  Knee-joint. 


Aperture  leading  into  the 
bursa  beneath  the  quadri- 
ceps extensor 


Attachment  of  capsular,  or 
anterior  ligament  to  femur 


Fatty  tissue  within  cut  edge 
of  ligamentum  mucosum 


Anterior  crucial  ligament 


External  semilunar 
flbro-eartilage 


Coronary  ligament 


Posterior  crucial  ligament 


Internal  semilunar 
flbro-cartilage 


Transverse  ligament 
Coronary  ligament 


the  i)Osterior  ligament,  of  Avhich,  if  not  the  chief  constituent,  it  is  at  least  a  very 
important  part. 

.  Its  deep  surface  is  closely  connected  Avith  the  semilunar  cartilages  (especially 
the  inner)  and  coronary  ligaments,  and  in  the  interval  between  the  cartilages  with 
the  posterior  crucial  ligament  and  fibro-fatty  tissue  within  the  joint.  Superficially 
it  forms  part  of  the  floor  of  the  ])opliteal  space. 

The  capsular  oi-  anterior  ligament  (fig.  246)  is  thin  but  strong,  covering  the 
synovial  membrane  midcr  tin-  cjuadriceps  extensor  tendon,  and  looking  like  a  loose 
sac.  It  is  atta(;hed  to  the  femur  near  the  articular  margin  on  the  inner  side,  but 
further  away  on  the  outer;  it  passes  beneath  the  external  lateral  ligament  to  join 
the  sheath  of  the  poplHem.  Internally  it  joins  the  internal  lateral  ligament.  Below, 
it  is  fixed  to  the  upper  and  lateral  borders  of  the  patella  and  the  anterior  border 


THE  KXEE-JOIXT 


'J.OI 


of  the  head  of  the  tibia.  It  is  strengthened  superficially  between  the  femur  and 
patella  by  an  expansion  from  the  subcrureus,  and  is  separated  from  the  fibrous 
expansion  of  the  extensor  tendon  by  a  layer  of  fatty  tissue.  The  synovial  mem- 
brane lines  its  deep  surface,  and  holds  it  against  the  borders  of  the  semilunar 
cartilages;  it  is  also  attached  to  the  coronary  ligaments. 

Internal  Ligaments 

The  anterior  crucial  ligament  (figs.  246  and  247)  is  strong  and  cord-like.  It 
is  attached  to  the  inner  half  of  the  fossa  in  front  of  the  spine  of  the  tibia,  and  to 
the  outer  border  of  the  inner  articular  facet  as  far  back  as  the  inner  tubercle  of  the 
spine.  It  passes  upwards,  backwards,  and  outwards  to  the  liack  part  of  the  internal 
surface  of  the  external  condyle.  To  the  tibia,  it  is  fixed  behind  the  anterior 
extremity  of  the  internal  semilunar  cartilage.  Behind  and  to  the  outer  side  it  has 
the  anterior  extremity  of  the  external  semilunar  cartilage,  a  few  fibres  of  which 
blend  with  the  outer  edge  of  the  ligament.  Its  anterior  fibres  at  the  tibial  end  are 
strongest  and  longest,  being  fixed  highest  on  the  femur;  while  the  posterior, 
springing  from  the  spine,  are  shorter  and  more  oblique.  Near  the  spine,  a  s\i\>  is 
sometimes  given  off  to  the  posterior  crucial. 

The  posterior  crucial  ligament  (figs.  246,  247,  and  248)  is  stronger  and  less 


Fig.  247. — STRrcTiRES  lying  ox  the  Head  of  the  Tibia.     (Eight  knee.) 

Ligamentura  patellas 

Expansion  from  quadriceps 
extensor  tendon 


Transverse  ligamen 


External  semilunar  fibro- 
cartilage 
Anterior  crucial 


Internal  semilunar  flbro- 
eartilage 


Posterior  crucial 
ligament 


Tendon  of  biceps 
External  lateral  ligament 


ol)lique  than  the  anterior.  It  is  fixed  lielow  to  the  greater  portion  of  the  fossa 
Ix'hind  the  spine  of  the  tibia,  especially  the  outer  and  posterior  portion,  and  then 
inwards  and  upwards  along  the  popliteal  notch ;  being  joined  by  fibres  which  arise 
Vtetween  the  tubercles  of  the  spine,  it  ascends  to  the  anterior  part  of  the  outer 
surface  of  the  inner  condyle,  having  a  Avide  crescentic  attachment  more  than  half 
an  inch  (1  -o  cm. )  in  extent  just  above  the  articular  surface.  Behind,  it  is  connected 
at  the  tibia  directly  with  the  posterior  ligament,  and  a  little  higher  up  by  means 
of  a  quantity  of  interposed  areolar  tissue.  In  front  it  rests  upon  the  posterior 
horn  of  the  internal  semilunar  cartilage,  and  receives  a  large  slip  from  the  external 
cartilage,  which  ascends  along  it  either  in  front,  or  behind  to  the  femur;  higher 
up  in  front  it  is  connected  with  the  anterior  crucial  ligament. 

Until  they  rise  above  the  spine  of  the  tibia  the  two  crucial  ligaments  are  closely 
bound  together,  so  that  no  interspace  exists  between  their  tibial  attachments  and 
the  point  of  decussation;  the  only  space  between  them  is  therefore  a  V-shaped 
one  corresponding  to  the  upper  half  of  their  X-shaped  arrangement,  and  this  is  a 
mere  chink  in  the  undissected  state,  and  can  be  seen  from  the  front  only,  owing  to 
the  fatty  tissue  beneath  the  synovial  membrane  which  surrounds  their  femoral 
attachment. 

The  interarticular  or  semilunar  fibro-cartilages  (figs.  246  and  247)  are  two 
crescentic  jjlates  resting  upon  the  circumferential  ] tortious  of  the  articular  facets  of  the 
17 


258 


THE  A  R  TIC  I  'LA  TIOXS 


tibia,  and  moving'  with  the  tibia  upon  the  femur.  They  somewhat  deepen  the  tibial 
articuUir  surfaces,  and  are  dense  and  compact  in  structure,  becoming  looser  and 
more  fil)rous  near  their  extremities,  where  they  are  firmly  fixed  in  front  of  and 
behind  the  spine  of  the  tibia.  The  circumferential  border  of  each  is  convex,  thick, 
and  somewhat  loosely  attached  to  the  borders  of  the  tuberosities  of  the  tibia  by  the 
coronary  ligaments,  and  the  reflexion  of  the  syno\dal  membrane.  The  inner  border 
is  concave,  thin,  and  free.  lialf^an  inch  (l-o  cm.)  broad  at  the  widest  part,  they 
taper  somewhat  towards  their  extremities,  and  cover  rather  less  than  two-thirds  of 
the  articular  facets  of  the  tibia.  Their  upper  surfaces  are  slightly  concave,  and  tit 
on  to  the  femoral  condyles,  while  the  lower  are  flat  and  rest  on  the  head  of  the 
tibia;  both  surfaces  are  smootli  and  covered  by  synovial  membrane. 

The  external  semilunar  cartilage  (fig.  247)  is  nearly  circular  in  form  and  less 
firmlv  fixed  than  the  internal,  and  consequently  slides  more  freely  upon  the  tibia. 


Fig.  248. — Anterior  View  of  the  Knee-joint,  showing  the  Synovial  Ligaments. 
(Anterior  portion  of  capsule  with  the  extensor  teudou  thrown  downwards.) 


Posterior  crucial 


Ijigamentum  mucosum 


Alar  ligament 


Synovial  pouch  under  tendon 
of  quadriceps  extensor 


Alar  ligament 


Its  anterior  cornu  is  attached  to  a  narrow  depression  along  the  outer  articular  facet, 
just  in  front  of  the  external  tubercle  of  the  tibial  spine,  close  to,  and  on  the  outer 
side  of,  the  anterior  crucial  ligament;  a  small  slip  from  the  cornu  is  often  fixed  to 
the  til)ia  in  front  of  the  crucial  ligament.  The  posterior  cornu  is  firmly  attached  to 
the  tibia  behind  the  external  tubercle  of  the  spine,  blending  with  the  posterior 
crucial  ligament,  and  giving  off  a  well-marked  fasciculus,  which  runs  up  along  the 
anterior  border  of  the  ligament  to  be  attached  to  the  femur  (ligament  of  Wrisberg). 
It  also  sends  a  narrow  slip  into  the  back  part  of  the  anterior  crucial  ligament. 

Its  outer  border  is  grooved  towards  its  posterior  part  by  the  poplitem  tendon, 
which  is  held  to  it  by  fibrous  tissue  and  synovial  meml)rane',  and  separates  it  from 
the  external  lateral  ligament.  From  its  anterior  border  is  given  oft'  the  transverse 
ligament. 

The  internal  semilunar  cartilage  (lig.  247)  is  a  segment  of  a  larger  circle  than 


THE  KNEE-JOINT  259 

the  external,  and  has  an  outline  more  oval  than  circular.  Its  anterior  cornu  is 
wide,  and  has  a  broad  and  ol)lique  attachment  to  the  anterior  margin  of  the  head 
of  the  tibia.  It  reaches  backwards  and  outwards  from  the  margin  of  the  tuberosity 
towards  the  middle  of  the  fossa  in  front  of  the  til)ial  spine,  being  altogether  in  front 
of  the  anterior  crucial  ligament.  The  posterior  cornu  is  tirmly  fixed  by  a  broad 
insertion  in  an  antero-posterior  line  along  the  inner  side  of  the  posterior  fossa,  from 
the  internal  tul^ercle  of  the  spine  to  the  posterior  margin  of  the  head  of  the  tibia. 
Its  convex  border  is  connected  with  the  internal  lateral  ligament  and  the  semimem- 
brannsus  tendon.  • 

The  transverse  ligament  (figs.  246  and  247)  is  a  rounded,  slender,  short  cord, 
which  extends  from  the  convex  border  of  the  external  semilunar  cartilage  to  the 
concave  border  or  anterior  cornu  of  the  internal,  near  Avhich  it  is  sometimes  attached 
to  the  bone.  It  is  an  accessory  band  of  the  external  cartilage,  and  is  situated 
beneath  the  synovial  membrane. 

The  coronary  ligaments  (fig.  246)  connect  the  margins  of  the  semilunar  fi))ro- 
cartilages  with  the  head  of  the  tibia.  The  external  is  much  more  lax  than  the 
internal,  permitting  the  outer  cartilage  to  change  its  position  more  freely  than 
the  inner.  They  are  not  in  reality  separate  structures,  but  consist  of  fibres  of  the 
several  surrounding  ligaments  of  the  knee-joint  which  become  attached  to,  as  they 
pass  over  the  margins  of  the  fibro- cartilages. 

The  synovial  membrane  (fig.  249)  of  the  knee  forms  the  largest  synovial  sac 
in  the  bodv.  Bulging  upwards  from  the  patella,  it  follows  the  capsule  of  the  joint 
into  a  large  rul-de-snc  beneath  the  tendon  of  the  extensor  muscles  on  the  front  of 
the  femur.  It  reaches  some  distance  beyond  the  articular  surface  of  the  bone,  and 
communicates  very  frequently  with  a  large  bursa  interposed  between  the  tendon 
and  the  femur  above  the  line  of  attachment  of  the  capsular  ligament.  After  invest- 
ing the  circumference  of  the  lower  end  of  the  femur,  it  is  reflected  upon  the  fibrous 
envelope  of  the  joint  formed  by  the  capsular,  posterior,  and  lateral  ligaments.  It 
covers  a  great  portion  of  the  crucial  ligaments,  but  leaves  uncovered  the  back  of  the 
posterior  crucial  where  the  latter  is  connected  with  the  posterior  ligament,  and  the 
lower  part  of  both  crucial  ligaments  where  they  are  united.  Thus  the  ligaments 
are  completely  shut  out  of  the  synovial  cavity.  Along  the  fibrous  envelope  the 
synovial  membrane  is  conducted  down  to  the  semilunar  cartilages,  over  both  sur- 
faces of  which  it  passes,  and  is  reflected  off  the  under  surface  on  to  the  coronary 
ligaments,  and  thence  down  to  the  head  of  the  tibia,  around  the  circumference  of 
which  it  extends  a  short  way.  It  dips  down  between  the  external  cartilage  and  the 
head  of  the  tibia  as  low  as  the  superior  tibio-fibular  ligament,  reaching  inwards 
nearly  as  far  as  the  popliteal  notch,  and  forming  a  bursa  for  the  play  of  the 
popliteal  tendon. 

At  the  back  of  the  joint  two  pouches  are  prolonged  beneath  the  muscles,  one  on 
each  side  between  the  condyle  of  the  femur  and  the  origin  of  the  gastrocnemius. 

Large  processes  of  synovial  memlirane  also  project  into  the  joint,  and  being 
occupied  by  fat  serve  as  padding  to  fill  up  spaces.  The  chief  of  these  processes, 
the  ligamentum  mucosum  (figs.  248  and  249)  springs  from  the  infrapatellar  fatty 
mass.  This  so-called  ligament  is  the  central  portion  of  the  large  process  of  synovial 
membrane,  of  which  the  alar  ligaments  form  the  lateral  free  margins.  It  extends 
from  the  fatty  mass,  below  the  patella,  backwards  and  upwards  to  the  inter- 
condyloid  notch  of  the  femur,  where  it  is  attached  in  front  of  the  anterior  crucial, 
and  to  the  outer  side  of  the  posterior  crucial  ligament.  Near  the  femur  it  is  thin 
and  transparent,  consisting  of  a  double  fold  of  SAniovial  memljrane,  Init  near  the 
patella  it  contains  some  fatty  tissue.  Its  anterior  or  upper  edge  is  free,  and  fully 
an  inch  (2-5  cm.)  long;  the  posterior  or  lower  edge  is  half  the  length,  and  is 
attached  to  the  crucial  ligaments  above,  Init  is  free  below. 

Passing  backwards  from  the  capsule  on  each  side  of  the  patella  is  a  prominent 
crescentic  fold  formed  by  reduplications  of  the  synovial  membrane — these  are  the 
alar  ligaments  (fig.  248).  Their  free  margins  are  concave  and  thin,  and  are  lost 
b(4(nv  in  the  ligamentum  mucosum.  There  is  a  slight  fossa  above  and  another 
below  eacl)  ligament. 

The  arterial  supply  is  derived  from  the  anastomotica  femoris;  the  superior  and 
inferior    internal    and    external    articular;    the   azygos    articular;    the  descending 


260 


THE  ARTICULA TIONS 


branch  of  the  external  circumflex;  the  anterior  recurrent  branch  from  the  anterior 
tibial;  and  the  posterior  tibial  recurrent. 

Tlie  nerve-supply  comes  from  the  great  sciatic,  anterior  crural,  and  obturator 
sources.  The  great  sciatic  gives  off  the  internal  and  external  popliteal;  the  internal 
l)opliteal  sends  t\v(),  sometimes  three  branches — one  with  the  azygos  artery;  one 
■with  the  inferior  internal,  and  sometimes  one  with  the  superior  internal  articular 
arterv;  the  external  popliteal  gives  a  brancli  which  accompanies  the  superior,  and 
another  which  accompanies  the  inferior  articular  artery,  and  a  recurrent  branch 


Fig.  249. — Vertical  Section  of  the  Kxee-.joixt  in  the  Axtero-posteriok  Dikectiox. 
(The  bones  are  .somewhat  diawu  apart.) 


Fatty  tissue 
Opening  in  synovial 
membrane    behind 
crucial       ligament 
leading  into  inner 
half  of  joint 
Synovial  membrane  re- 
flected off  crucial  liga- 
ments 
Cut  end  of  anterior  cru- 
cial ligament 
Posterior  crucial  liga- 
ment 
Ligament  of  Winslow 


Muscular  fibres  of  quadriceps 
extensor 


Extension  of  synovial  sac  of  knee 
upon  femur 


t  '       \  _  Tendon    of    quadriceps    extensor, 
\      j.\\\'     forming  fibrous  capsule  of  joint 


Pre-patellar  bursa 


CONDYLE  OF  FEMUR  (INNER. 


Iiigamentum  mucosum 


Fatty  tissue  between 
ligamentum  patellae 
and  synovial  sac 


Bursa  beneath  ligamentum 
patellae 


which  follows  the  course  of  the  anterior  recurrent  branch  of  the  anterior  tibial 
artery.  The  anterior  crural  sends  an  articular  branch  from  the  nerve  to  the  vastus 
externus;  a  second  from  the  nerve  to  the  vastus  internus;  and  sometimes  a  third 
from  that  to  the  crurcus.  Thus  there  are  three  articular  twigs  to  the  knee  derived 
from  the  nuiscular  liranclics  of  the  anterior  crural.  (Roger  ^^'il]iams,  Journ.  Anat. 
Physiol.,  1879.)  The  obturator  Viy  its  deep  division  sends  a  branch  tliroiigh  the 
adductor  magnus  on  to  tlie  ix.pliteal  artery,  which  enters  the  joint  through  the 
posterior  ligament. 

The  movements  which  occur  at  thf  knee-joint  are  flexion  and  extension,  with 


THE  KNEE-JOINT 


261 


some  slight  amount  of  rotation  in  the  bent  position.  These  movements  are  not  so 
simple  as  the  corresponding  ones  at  the  elbow,  for  the  knee  is  not  a  simple  hinge 
joint.  The  rotation  inwards  and  outwards  are  movements  of  the  tibia  with  tlie 
fibula  upon  the  condyles  of  the  femur. 

The  knee  differs  from  a  true  hinge  jdint  like  the  ell)Ow  or  ankle,  in  the  following 
particulars : — 

1.   The  jjoints  of  contact  of  the  femur  with  the  tibia  are  constantly  changing. 


Fig.  250. — The  Lateral  Ligaments  of  the  Kxee  in  Flexion  and  Extension. 


Tlius,  in  the  flexed  position,  the  hinder  part  of  the  articular  surface  of  the  tibia  is 
in  contact  with  the  rounded  back  part  of  the  condyles;  in  the  semiflexed  position 
the  middle  parts  of  the  tibial  facets  articulate  with  the  anterior  rounded  part  of  the 
condyles;  while  in  the  fully  extended  position  the  anterior  and  middle  parts  of  the 
til)ial  facets  are  in  contact  with  the  anterior  flattened  portion  of  the  condyles.  So 
with  the  patella:  in  extreme  flexion  the  inner  articular  facet  rests  on  the  outer  part 


262 


THE  ARTICULATIONS 


of  the  internal  condyle  of  the  femur;  in  flexion  the  upper  pair  of  facets  rest 
on  the  lower  part  of  the  trochlear  surface  of  the  femur;  in  mid-flexion  the 
middle  pair  rest  on  the  middle  of  the  trochlear  surface;  while  in  extension 
the  lower  jmir  of  facets  on  the  patella  rest  on  the  upper  portion  of  the  trochlear 
surface  of  the  femur. 

This  diflferenee  may  be  descril)ed  as  the  shifting  of  the  points  of  contact  of  the 
articular  surface. 

2.  It  differs  from  a  true  hinge  in  that,  in  passing  from  a  state  of  extension  to 
one  of  flexion,  the  tibia  does  not  revolve  round  a  single  transverse  axis  drawn 
through  the  lower  end  of  the  femur,  as  the  ulna  does  round  the  lower  end  of  the 
humerus.  The  articular  surface  of  the  tibia  slides  forwards  in  extension  and  back- 
Avards  in  flexion;  thus  the  axis  round  which  the  tibia  revolves  upon  the  femur  is  a 
shifting  one,  as  is  seen  by  reference  to  fig.  250,  B,  C,  D. 

3.  Another  point  of  difference  is  that  extension  is  accompanied  by  rotation  out- 
wards, and  flexion  by  rotation  inwards.     This  rotation  occurs  round  a  vertical  axis 


Fig.  251. — Section  of  Knee,  showing  Crlcials  in  Extension. 


Anterior  crucial  ligament 

SPINE  OF  TIBIA 
Transverse  ligament 


Slip  from  external  flbro-cartilage  to 

I femur  (ligament  of  Wrisbergi 

Posterior  crucial  ligament 

External  semilunar  cartilage 


Coronary  ligament 

Antero-superior  tibio-flbular  ligament 


drawn  through  the  middle  of  the  outer  condyle  of  the  femur  and  the  outer  tuber- 
osity of  the  ti))ia,  and  is  most  marked  at  the  termination  of  extension  and  at  the 
commencement  of  flexion.  This  rotation  of  the  leg  at  the  knee  is  a  true  rotation 
about  a  vertical  axis,  and  tlius  differs  from  the  oblicjuity  of  the  flexion  and  extension 
movements  at  the  ell)o\v  wliich  is  due  to  the  oblique  direction  of  the  articular  sur- 
faces of  tlie  bom-s. 

4.  The  antero-posterior  spiral  curve  of  the  femoral  condyles  is  sucli,  that  the 
anterior  part  is  an  arc  of  a  greater  circle  than  the  posterior;  hence  certain  ligaments 
which  are  tightened  during  extension  are  relaxed  during  flexion,  and  thereby  a  con- 
sideralile  amount  of  rotatory  movement  is  permitted  in  the  flexed  position.  Tlie 
axis  of  tliis  rotation  is  vertical,  and  passes  througli  the  inner  tuliercle  of  the  spiiK^ 
of  thetiltia,  so  that  the  outer  tuberosity  moves  in  the  arc  of  a  larger  circle  than 
does  the  inner,  and  is  therefore  re(iuired  "to  move  more  freely  and  easilv;  hence  the 
shape  of  the  external  articular  facet  and  the  loose  connection  of  "the  external 
semilunar  cartilage  whicli  is  a(hi])ted  to  it. 

In  extension,  all  the  ligaments  arc  on   the  stretch  with  the  exception  of  the 


THE  TIBIO-FIBULAR   UNION 


263 


ligamentum  patellae  and  front  of  the  capsule.     Extension  is  checked  by  both  the 
crucial  ligaments  and  the  lateral  ligaments  (figs.  250,  A,  B,  and  251). 

In  flexion  the  ligamentum  patellae  and  anterior  portion  of  the  capsule  are  on 
the  stretch;  so  also  is  the  posterior  crucial  in  extreme  flexion,  though  it  is  not  quite 
tight  in  the  semiflexed  state  of  the  joint.  All  the  other  ligaments  are  relaxed  (fig. 
250,  C,  D),  although  the  relaxation  of  the  anterior  crucial  ligament  is  slight  in 
extreme  flexion  (fig.  252).  Flexion  is  only  checked  during  life  by  the  contact  of 
the  soft  parts,  i.e.  the  calf  with  the  back  of  the  thigh. 


Fig.  252. — Ckucial  Ligaments  in  Flexion. 


Posterior  crucial 


Anterior  crucial 

Internal  semilunar 
cartilage 
TraBsverse  ligament 


Slip  from  external  cartilage  to  femur 
Extsrnal  semilunar  cartilage 


Coronary  ligament 

Antero-superior  tibio-flbular  ligament 


Inward  rotation  is  checked  by  the  anterior  crucial  ligament;  the  lateral  liga- 
ments being  loose. 

Outw'ard  rotation  is  checked  by  the  lateral  ligaments;  the  crucial  ligaments  have 
no  controlling  effect  on  it,  as  they  are  untwisted  by  it. 

Sliding  movements  are  checked  by  the  crucials  and  lateral  ligaments — sliding 
forwards  especialh^  by  the  anterior,  and  sliding  backwards  by  the  posterior  crucial. 


3.  THE  TIBIO-FIBULAR  UNION 

The  fibula  is  connected  with  the  tibia  throughout  its  length  by  an  interosseous 
membrane,  and  at  the  upper  and  lower  extremities  by  means  of  two  joints.  Very 
little  movement  is  permitted  between  the  two  bones. 


(a)  The  superior  tibio-fibular  joint. 
(6)  The  middle  tibio-fibular  union, 
(c)  The  inferior  tibio-fibular  joint. 


(«)  The  Superior  Tibio-fibular  Joint 
Class, — Diarthrosis.  Subdivision. — Arthrodia. 

The  superior tibio-fiV)ular  joint  is  about  a  quarter  of  an  inch  (6  mm.)  below,  and 
quite  distinct  from,  the  knee  at  its  upper  and  anterior  part;  but  at  its  posterior  and 


264  THE  ARTICULATIOXS 

superior  aspect,  where  the  l>order  of  the  outer  tuberosity  of  the  tibia  is  bevelled 
by  the  popliteus  muscle,  the  joint  is  in  the  closest  proximity  to  the  bursa  beneath 
the  tendon  of  that  muscle,  and  is  only  separated  from  the  knee-joint  by  a  thin 
septum  of  areolar  tissue.  There  is  often  a  communication  between  the  synovial 
cavities  of  the  two  joints.     The  ligaments  uniting  the  bones  are: — 

Capsular.  Anterior  tibio-fibular. 

Posterior  tibio-fibular. 

The  capsular  ligament  is  a  well-marked  fibro-areolar  structure;  it  is  attached 
close  round  the  articular  margins  of  the  tibia  and  fibula.  In  front  it  is  shut  ofY 
completely  from  the  knee-joint  by  the  capsule  of  the  knee  and  the  coronary  liga- 
ment; but  liehind,  it  is  often  very  thin,  and  may  communicate  with  the  bursa 
under  the  popliteus  tendon. 

The  anterior  tibio-fibular  ligament  (fig.  251)  consists  of  a  few  fibres  which 
pass  upwards  and  inwards  from  the  fibula  to  the  tibia.  It  lies  beneath  the  anterior 
portion  of  the  tendon  of  the  biceps. 

The  posterior  tibio-fibular  ligament  (fig.  245)  consists  of  a  few  fibres  w^hich 
pass  upwards  and  inwards  between  the  adjacent  bones,  from  the  head  of  the  fibula 
to  the  outer  tuberosity  of  the  tibia. 

The  superior  interosseous  ligament  consists  of  a  mass  of  dense  yellow  fibro- 
areolar  tissue,  binding  the  opposed  surfaces  of  the  bones  together  for  three-quarters 
of  an  inch  (2  cm. )  below  the  articular  facets.  It  is  continuous  Avith  the  interosseous 
membrane  along  the  tibia. 

The  biceps  tendon  is  divided  by  the  long  external  lateral  ligament  of  the  knee; 
of  the  two  divisions  the  anterior  is  by  far  the  stronger,  and  is  attached  to  the 
external  tuberosity  of  the  tibia  as  well  as  to  the  front  of  the  head  of  the  fibula,  and 
thus  the  muscle,  acting  on  both  bones,  tends  to  brace  them  more  tightly  together; 
indeed,  it  holds  the  bones  strongly  together  after  all  other  connections  have  been 
severed. 

The  synovial  membrane  which  lines  the  joint  sometimes  communicates  with 
the  knee-joint  through  the  bursa  beneath  the  popliteus  tendon. 

The  arterial  supply  is  from  the  inferior  external  articular  and  recurrent  tibial 
arteries. 

The  nerve-supply  is  from  the  inferior  external  articular,  and  also  from  the 
recurrent  branch  of  the  external  popliteal. 

The  movements  are  but  slight,  and  consist  merely  of  a  gliding  of  the  two 
bones  upon  each  other.  The  joint  is  so  constructed  that  the  fibula  gives  some 
support  to  the  tibia  in  transmitting  the  weight  to  the  foot.  The  articular  facet  of 
the  tibia  overhangs,  and  is  received  upon  the  articular  facet  of  the  head  of  the 
fibula  in  an  oblique  plane.  This  joint  allows  of  slight  yielding  of  the  external 
malleolus  during  flexion  and  extension  of  the  ankle-joint,  the  whole  fibula  gliding 
slightly  upwards  in  flexion,  and  downwards  in  extension  of  the  ankle. 


(/))  The  Middle  Tibio-fibular  Union 

The  interosseous  membrane  is  attached  along  the  outer  border  of  the  tibia 
and  the  interosseous  border  of  the  filnila.  It  is  deficient  above  for  about  an  inch 
(2-5  cm.)  or  more,  measured  from  the  under  aspect  of  the  superior  joint.  Its 
upper  border  is  concave,  and  over  it  pass  the  anterior  tibial  vessels.  The  membrane 
consists  of  a  thin  ai)oneurotic  and  translucent  lamina,  formed  of  oblicjue  line  fibres, 
some  of  which  run  from  the  tibia  to  the  lil)ula,  and  some  from  the  fibula  to  the 
tibia,  but  all  are  inclined  downwards.  They  are  best  marked  at  their  attachment 
to  the  bones,  and  gradually  groAv  denser  and  thicker  as  they  approach  the  inferior 
interosseous  ligament.  The  chief  use  of  the  membrane  is  to  afford  a  surface  for  the 
origin  of  muscles.      It  is  continuous  below  with  the  inferior  interosseous  ligament. 


THE  TIBIO-FIBULAR  UNION 


265 


(c)  The  Inferior  Tibio-fibular  Articulation 
Class. — Diarthrosi.s.  Subdivision. — Arthrodia. 

This  junction  is  formed  l)y  the  lower  ends  of  the  tibia  and  fibula.  The  rough 
triangular  surface  on  each  of  these  bones  formed  by  the  bifurcation  of  their  inter- 
osseous lines  is  closely  and  firmly  united  by  the  inferior  interosseous  ligament. 
The  fibula  is  in  actual  contact  with  the  tibia  by  an  articular  facet,  which  is  small 
in  size,  crescentic  in  shape,  and  continuous  with  the  articular  facet  of  the  malleolus. 

The  ligaments  which  unite  the  bones  are: — 

1.  Anterior  inferior  tibio-fibular  ligament. 

2.  Posterior  inferior  tibio-fibular  ligament. 

3.  Transverse  ligament. 

4.  Inferior  interosseous  ligament. 

The  antero-inferior  tibio-fibular  ligament  (figs.  252  A  and  2o.5)  is  a  strong 
triangular  band  about  three-quarters  of  an  inch  (2  cm. )  wide,  and  is  attached  to  the 
lower  extremity  of  the  til)ia  at  its  anterior  and  external  angle,  close  to  the  margin 
of  the  facet  for  the  astragalus,  and  passes  downwards  and  outwards  to  the  anterior 


Fig.  252  A. — Lower  Ends  of  Left  Tibia  and  Fibula,  showing  the  Ligaments.  The 
synovial  fold  between  these  bones  has  been  removed  to  show  the  transverse  ligament  forming 
part  of  the  capsule  of  the  joint,  and  the  deeper  fibres  of  the  anterior  inferior  tibio-fibular  liga- 
ment which  come  into  contact  with  the  astragalus. 

(From  a  dis-section  by  Mr.  W.  Pearson,  of  the  Eoval  College  of  Surgeons'  Museum.) 


I  Anterior  inferior  tibio- 
j  fibula  ligament 


External  lateral  ligament 


Internal  lateral 
ligament 


Transverse  ligament 

Posterior  inferior  tibio- 
fibular ligament 


border  and  contiguous  surface  of  the  lower  end  of  the  fibula,  some  fibres  passing 
along  the  edge  nearly  as  far  as  the  origin  of  the  anterior  fasciculus  of  the  external 
lateral  ligament.  The  fibres  increase  in  length  from  aljove  downwards.  In  front 
it  is  in  relation  with  the  peroneus  tertius  and  deep  fascia  of  the  leg,  and  gives  origin 
to  fibres  of  the  anterior  ligament  Of  the  ankle-joint.  Behind,  it  lies  in  contact  with 
the  interosseous  ligament,  and  comes  into  contact  with  the  articular  surface  of  the 
astragalus  (see  figs.  252  A  and  252  B). 

The  postero-inferior  tibio-fibular  ligament  (figs.  254  and  255)  is  very  similar 
to  the  anterior,  extending  from  the  ])osterior  and  external  angle  of  the  lower  end  of 
the  tibia  downwards  and  outwards  to  the  lowest  half-inch  ( 1  '5  cm. )  of  the  border 
separating  the  internal  from  the  posterior  surface  of  the  shaft  of  the  fibula,  and  to 
the  upi)er  part  of  the  posterior  Ijorder  of  the  external  malleolus.  It  is  in  relation 
in  front  with  the  interosseous  ligament;  l^elow,  it  touches  the  transverse  ligament. 

The  inferior  interosseous  ligament  is  a  dense  mass  of  short  felt-like  fibres, 
passing  transversely  l»etween  and  liniily  uniting  the  oi)posed  rough  triangular 
surfaces  at  the  lower  ends  of  the  tiV)ia  and  fibula,  except  for  three-eighths  of  an 
inch  (1  cm.)  at  the  extremity,  where  there  is  a  synovial  cavity.  It  extends  from 
the  anterior  to  the  posterior  tibio-fibular  ligaments,  reaching  upwards  an  inch  and 
a  half  in  front  (4  cm.).  l)Ut  only  half  this  height  behind. 

The  transverse  ligament  (fig.  254)  is  a  strong  rounded  band,  attached  to  nearly 
the  whole  length  of  the  inferi(.)r  border  of  the  posterior  surface  of  the  tibia,  just  above 


266 


THE  ARTICrLATTOXS 


the  articular  facet  for  the  astrao;ahis.  It  then  incHncs  a  little  forwards  and  down- 
wards;, to  be  attaehed  to  the  internal  surface  of  the  external  malleolus,  just  above 
the  fossa,  and  the  upper  part  of  the  fossa  itself. 

The  synovial  membrane  is  continuous  with  that  of  the  ankle-joint;  it  projects 
upwards  between  the  bones  beyond  their  articular  facets  as  high  as  the  inferior 
interosseous  liijament. 

The  nerve-supply  is  the  same  as  that  of  the  ankle-joint;  the  arterial  supply 
is  from  the  peroneal  and  the  anterior  peroneal,  and  sometimes  from  the  anterior 
tibial,  or  its  external  malleolar  liranch. 

Tlie  movement  i)ermitted  at  this  joint  is  a  mere  gliding,  chiefly  in  an  upward 
ami  downward  direction,  of  the  tibula  on  the  tibia.  The  bones  are  firmly  braced 
together  and  yet  form  a  slightly  yielding  arch,  thus  allowing  a  slight  lateral 
expansion  during  extreme  flexion,  when  the  broad  part  of  the  astragalus  is  brought 
under  the  arch,  by  the  upward  gliding  of  the  fibula  on  the  tibia.  To  this  end  the 
direction  of  the  fibres  of  the  superior  and  inferior  tibio-fibular  ligaments  is  down- 
wards from  tibia  to  fibula.  This  mechanical  arrangement  secures  perfect  contact 
of  the  articular  surfaces  of  the  ankle-joint  in  all  positions  of  the  foot. 


4.  THE  ANKLE-JOINT 
Class, — Diarthrosis.  Subdivision. 


-Ginglymus. 


The  ankle  is  a  perfect  ginglymus  or  hinge  joint.  The  bones  which  enter  into 
its  formation  are:  the  lower  extremity  and  internal  malleolus  of  the  tibia,  and 
the  external  malleolus  of  the  fibula,  above;  and  the  upper  and  lateral  articular 
surfaces  of  the  astragalus  below.     The  ligaments  uniting  the  bones  are: — 


Anterior. 
Posterior. 


Internal  lateral. 
External  lateral. 


Fig.  252  B. — Right  Ankle-joint,  showing  the  Ligaments. 
(From  dissection  Viy  Mr.  W.  Pearson,  of  the  Royal  College  of  Surgeons'  Museum.  ^ 


inferior  tibio-flbular  liga 
ment  i 

Deep  fibres  of  anterior  inferior 
tibio-flbular  ligament 


^  of  ex- 
Anterior  fasciculus  I  ternal 
Posterior  fasciculus  >  lateral  ■, 
Middle  fasciculus      |    liga-    (^ 
ment 


Internal  lateral  ligament 


The  anterior  ligament  (fig.  255)  is  a  thin,  membranous  structure,  which  ex- 
tends l)etween  th(;  lateral  ligaments.  It  is  attached  above  to  the  anterior  border 
of  the  internal  malleolus,  to  a  crest  of  bone  just  above  the  transverse  groove  at  the 
lower  end  of  the  tibia,  to  the  anterior  inferior  tibio-fibular  ligament,  and  to  the 
anterior  border  of  the  external  malleolus.  Below,  it  is  attached  to  the  rough  upper 
surface  of  the  neck  of  the  astragalus,  in  front  of  the  fossa.  Internally  it  is  thicker, 
and  is  fixed  to  the  astragalus  close  to  the  facet  for  the  inner  malleolus,  being 
continuous  with  the  internal  lateral  ligament,  and  passing  forwards  to  blend 
with  the  dorsal  astragalo-sca])hoi(l  ligament.  Externally  it  is  attached  to  the 
astragalus,  just  l)elow  and  in  front  of  the  angle  between  the  superior  and  lateral 
facets,  close  to  their  edges,  and  joins  the  anterior  fasciculus  of  the  external  lateral 
ligament.     It  is  in  relation,  in  front  with  the  tibialis  anticus  muscle,  the  anterior 


THE  ANKLE-JOINT 


267 


tibial  vessels  and  nerve,  the  extensor  tendons  of  the  toes,  and  the  peroneus  tertlus  ; 
and  behind  with  a  mass  of  fat  and  synovial  membrane. 

The  posterior  ligament  (fig.  254)  is  a  very  thin  and  disconnected  membranous 
structure,  connected  above  with  the  external  malleolus,  internal  to  the  peroneal 
groove;  to  the  posterior  margin  of  the  lower  end  of  the  tibia  external  to  the  groove 
for  the  tibialis  posticus;  and  to  the  posterior  inferior  tibio-fibular  ligament.  Below, 
it  is  attached  to  the  posterior  surface  of  the  astragalus  from  the  internal  to  the 
external  lateral  ligaments.  The  passage  of  the  flexor  longus  hallucis  tendon  over 
the  back  of  the  joint  serves  the  purpose  of  a  much  stronger  posterior  ligament. 

The  internal  lateral  or  deltoid  ligament  (fig.  253)  is  attached  superiorly  to 
the  internal  malleolus  along  its  lower  border,  and  to  its  anterior  surface  superficial 
to  the  anterior  ligament;  some  very  strong  fibres  are  fixed  to  the  notch  in  the  lower 
border  of  the  .malleolus,  and,  getting  attachment  below  to  the  rough  depression  on 
the  inner  side  of  the  astragalus,  form  a  deep  portion  to  the  ligament.  The  ligament 
radiates;  the  posterior  fibres  are  short,  and  incline  a  little  backwards  to  be  fixed 


Fig. 


253. — Inner  View  of  the  Ankle  and  the  Tarsus,  showing  the  Groove   for  the 
Tendon  of  the  Tibialis  Posticus. 


Internal  lateral 
ligament 


Inferior  cal- 

eaneo-seaphoid 

ligament 


Short  plantar  ligament 


Long  plantar  ligament 


to  the  rough  inner  surface  of  the  astragalus,  close  to  the  superior  articular  facet, 
and  into  the  tubercle  to  the  inner  side  of  the  flexor  longus  hallucis  groove.  The 
fibres  next  in  front  are  numerous  and  form  a  thick  and  strong  mass,  filling  up  the 
rough  depression  on  the  inner  surface  of  the  astragalus,  whilst  some  pass  over  the 
calcaneo-astrngaloid  joint  to  the  upper  and  inner  border  of  the  sustentaculum  tali. 
The  fibres,  wliich  are  connected  above  with  the  anterior  surface  of  the  malleolus, 
pass  downwards  and  somewhat  forwards  to  be  attached  to  the  scaphoid  and  to  the 
margin  of  tlie  calcaneo-sca])li()id  ligament. 

The  external  lateral  ligament  (figs.  254  and  255)  consists  of  three  distinct  sHps. 
The  anterior  fasciculus  is  ribbon-like  and  passes  from  the  anterior  l)order  of  the 
external  malleolus  near  the  tip  to  the  rough  surface  of  the  astragalus  in  front  of  the 
external  lateral  facet,  and  overhanging  the  sinus  pedis.  The  middle  fasciculus  is 
a  strong  roundish  bundle,  which  extends  downwards  and  somewhat  backwards  from 
the  anterior  border  of  the  external  malleolus  close  to  the  attachment  of  the  anterior 
fasciculus,  and  from  the  outer  surface  of  the  malleolus,  just  in  front  of  the  apex, 


268 


THE  ARTICI 7. A  TWXS 


to  a.  tubercle  on  the  middle  of  the  out«r  surface  of  the  calcaneum.  The  posterior 
fasciculus  is  almost  horizontal;  it  is  a  strong,  thick  l)and  attached  at  one  end  to 
the  i)osterior  border  of  the  malleolus,  and  slightly  to  the  fossa  on  the  internal 
surface;  and  at  the  other  end  to  the  astragalus,  behind  the  articular  facet  for  the 
fibula,  as  well  as  to  a  tubercle  on  the  outer  side  of  the  groove  for  the  flexor  lonyus 
hallucis.  The  middle  fasciculus  is  covered  by  the  tendons  of  the  peronei  longus  and 
bren's ;  and  in  extension,  the  posterior  fasciculus  is  received  into  the  pit  on  the 
inner  surface  of  the  external  malleolus. 

The  synovial  membrane  is  very  extensive.  Besides  lining  the  ligaments  of 
the  ankle,  it  extends  upwards  between  the  tibia  and  fibula,  forming  a  short  cul-de- 
sac  as  far  as  the  interosseous  ligament.  Upon  the  anterior  and  posterior  ligaments 
it  is  very  loose,  and  extends  beyond  the  limits  of  the  articulation.  It  is  said  to 
contain  more  synovia  than  any  other  joint. 

Fig.  254. — Ligaments  seen  from  the  Back  of  the  Ankle-joint. 


Posterior  ligament  of  ankle- 
joint 


Posterior  part  of  the  internal 
lateral  ligament 


The  lower  part  of  the  inter- 
osseous membrane 


Transverse  ligament  of  inferior 
tibio-flbular  joint 


Posterior  fasciculus  of  external 
lateral  ligament 


Middle  fasciculus  of  external 
lateral  ligament 


The  nerve-supply  is  from  the  internal  saphenous,  posterior  tilnal,  and  the 
external  division  of  the  anterior  tilnal. 

The  arterial  supply  comes  from  the  anterior  tibial,  the  anterior  peroneal,  the 
external  malleolar,  the  posterior  tibial,  and  posterior  peroneal. 

Movements.— Tliis  being  a  true  hinge  Joint,  flexion  and  extension  are  the  only 
movements  of  which  it  is  capable,  there  being  no  lateral  motion,  except  in  extreme 
extension,  when  the  narrowest  part  of  the  astragalus  is  thrust  forwards  into  the 
widest  part  of  the  tibio-fibular  arch.  In  flexion  the  astragalus  is  tightly  embraced 
l)y  the  malleoli,  and  lateral  movement  is  impossible.  Flexion  is  limited  by:  (i) 
nearly  tbe  whole  of  the  fibres  of  the  internal  lateral  ligament,  none  but  the  most 
anterior  being  relaxed;  (ii)  the  jjosterior  and  middle  portions  of  the  external  lateral 
ligament,  especially  th^  })osterior;  (iii)  the  ])osterior  ligament  of  the  ankle.  It  is 
also  limited  by  the  neck  of  the  astragalus  abutting  on  the  edge  of  the  tibia. 
Extension  is  limited  by:  (i)  the  anterior  fibres  of  the  internal  lateral  ligament; 
(ii)  the  anterior  and  middle  portions  of  tlie  external  lateral  ligament;   (iii)  the 


THE   TARSAL  JOINTS  269 

inner  and  stronger  fibres  of  the  anterior  ligament.  It  is  also  limited  by  the  pos- 
terior portion  of  the  astragalus  meeting  with  the  tibia.  Thus  the  middle  portion  of 
the  external  lateral  ligament  is  always  on  the  stretch,  owing  to  its  obliquely  back- 
ward direction,  Avhereby  it  limits  flexion;  and  its  attachment  to  the  fibula  in  front 
of  tlie  malleolar  apex,  wliereby  it  prevents  over-extension  as  soon  as  the  foot  begins 
to  twist  inwards.  This  inward  twisting,  or  adduction  of  the  foot,  is  partly  due  to 
the  greater  posterior  length  of  the  inner  border  of  the  superior  articular  surface  of 
the  astragalus,  and  to  the  less  proportionate  height  posteriorly  of  the  external  border 
of  that  surface,  but  chiefly  to  the  lateral  movement  in  the  calcaneo-astragaloid 
joints.  Flexion  and  extension  take  place  round  a  transverse  axis  draAvn  through 
the  Ijody  of  the  astragalus.  The  movement  is  not  in  a  direct  antero-posterior  plane, 
but  on  a  plane  inclined  forwards  and  outAvards  from  the  middle  of  the  astragalus  to 
the  intermetatarsal  joint  of  the  second  and  tliird  toes. 


5.  THE  TARSAL  JOINTS 
These  may  again  be  divided  up  into  the  following  sub-groups: — 

(a)  The  calcaneo-astragaloid  union. 

(6)  The  articulations  of  the  anterior  portion  of  the  tarsus. 

(c)  The  medio-tarsal  joint. 


(a)  The  Calcaxeo-astragaloid  Union 

There  are  two  joints  which  enter  into  this  union — viz.  an  anterior  and  a 
posterior. 

(i)  The  Posterior  Calcaneo-astragaloid  Joint 

Class . — Diartkrosis.  Subdivision. — Arthrodia. 

The  calcaneum  articulates  with  the  astragalus  by  two  joints,  the  anterior  and 
posterior:  the  former  communicates  with  the  medio-tarsal;  the  posterior  is  sej^arate 
and  complete  in  itself.     The  two  bones  are  united  V)y  the  following  ligaments : — 

Interosseous.  External  calcaneo-astragaloid. 

Posterior  calcaneo-astragaloid.  Internal  calcaneo-astragaloid. 

The  interosseous  ligament  (figs.  255  and  256)  is  a  strong  band  connecting  the 
apposed  surfaces  of  the  calcaneum  and  astragalus  along  their  oblique  grooves.  It 
is  composed  of  several  vertical  laminae  of  fibres,  with  some  fatty  tissue  in  between. 
It  is  Ijetter  marked,  deeper,  and  broader  externally.  Strong  laminae  extend  from 
the  rough  inferior  and  external  surfaces  of  the  neck  of  the  astragalus  to  the  rough 
superior  surface  of  the  os  calcis  anteriorly,  forming  the  posterior  boundary  of  the 
anterior  calcaneo-astragaloid  joint;  these  have  been  described  as  the  anterior 
interosseous  ligament.  The  posterior  laminae  extend  from  the  roof  of  the  sinus 
pedis  to  the  os  calcis  immediately  in  front  of  the  external  facet,  thus  forming  the 
anterior  part  of  the  capsule  of  the  ])osterior  joint. 

The  external  calcaneo-astragaloid  ligament  (fig.  255)  extends  from  the 
groove  just  below  and  in  front  of  the  external  articular  facet  of  the  astragalus,  to 
the  OS  calcis  some  little  distance  from  the  articular  margin.  Its  fibres  are  nearly 
parallel  with  those  of  the  middle  fasciculus  of  the  external  lateral  ligament  of  the 
ankle,  Avhich  passes  over  it  and  adds  to  its  strength.  It  fills  up  the  interval  ]>etween 
the  middle  and  anterior  fasciculus  of  the  external  lateral  ligament,  a  considerable 
bundle  of  its  fibres  blending  with  the  anterior  border  of  the  midtlle  fasciculus. 

The  posterior  calcaneo-astragaloid  ligament  passes  from  the  external 
tubercle  and  lower  edge  of  the  groove  for  the  flexor  longus  hallucis  to  the  os  calcis, 
a  variable  distance  from  the  articular  margin. 

The  internal  calcaneo-astragaloid  ligament  is  a  narrow  band  of  well-marked 


•270  THE  ARTICULATIONS 

fibres  i)assing  obliquely  downwards  and  Ijaekwards  from  the  depression  on  the 
astragalus,  just  behind  the  inner  end  of  the  sinus  pedis,  to  the  os  ealeis  behind  the 
sustentaeulum  tali,  thus  eompleting  the  floor  of  the  groove  for  the  flexor  longus 
hallueis  tendon. 

The  synovial  sac  is  distinct  from  any  other. 

Tlu'  nerve-supply  is  from  the  })osterior  tibial  or  one  of  its  plantar  branches. 

The  arteries  are,  a  branch  from  the  posterior  tibial,  Avhich  enters  at  the  inner 
end  of  the  sinus  i)edis;  and  twigs  from  the  tarsal,  external  malleolar,  and  the 
peroneal,  which  enter  at  the  outer  end  of  the  sinus. 

(ii)   The  Anterior  Calcaneo-astragalold  Joint 
Class. — Diarthrosis.  Subdivision. — Arthrodia. 

This  joint  is  formed  liy  the  anterior  facet  on  the  upper  surface  of  the  os  calcis 
and  the  facets  on  the  lower  surface  of  the  neck  and  head  of  the  astragalus;  it  is 
bounded  laterally  and  behind  by  ligaments,  and  communicates  anteriorly  Avith  the 
astragalo-scaphoid  joint.     The  ligaments  are: — 

Interosseous.         Internal  (or  antero-internal)  calcaneo-astragaloid. 
External  calcanco-scaphoicl. 

The  interosseous  ligament  by  its  anterior  laminie  limits  this  joint  posteriorly. 
It  has  been  already  descrilji-d  (p.  269). 

The  antero-internal  calcaneo-astragaloid  ligament  consists  of  short  fibres 
attached  above  to  the  rough  depression  on  the  internal  surface  of  the  neck  of  the 
astragalus,  and  below  to  the  upper  edge  of  the  free  border  of  the  sustentaculum 
tali,  l)lending  posteriorly  with  the  inner  extremity  of  the  interosseous  ligament,  and 
anteriorly  with  the  ujjper  border  of  the  inferior  calcaneo-scaphoid  ligament.  It  is 
strengthened  by  the  internal  lateral  ligament,  the  anterior  fibres  of  which  are  also 
attached  to  the  inferior  calcaneo-scaphoid  ligament. 

The  external  calcaneo-scaphoid  (superior  calcaneo-scaphoid,  Gray)  (figs.  255 
and  256 )  limits  this,  as  well  as  the  astragalo-scaphoid  joint,  on  the  outer  side.  It  is  a 
strong,  well-marked  band,  extending  from  the  rough  upper  surface  of  the  calcaneum, 
external  to  the  anterior  facet,  to  a  slight  groove  on  the  outer  surface  of  the  scaphoid 
near  the  posterior  margin.  It  blends  below  with  the  inferior  calcaneo-scaphoid, 
and  alcove  with  the  astragalo-scaphoid  ligament.  Its  fibres  run  obliquely  forwards 
and  inwards.  The  internal  lateral,  and  middle  fasciculus  of  the  external  lateral 
ligaments  of  the  ankle-joint  also  add  to  the  security  of  these  two  j(nnts,  and  assist 
in  limiting  movements  between  the  bones  by  passing  over  the  astragalus  to  the  os 
calcis. 

The  movements  of  which  these  two  joints  are  capable  are  adduction  and  abduc- 
tion, with  some  amount  of  rotation.  Adduction,  or  inclination  of  the  sole  inwards, 
being  combined  with  some  rotation  of  the  toes  inwards,  and  of  the  heel  outwards; 
while  abduction,  or  inclination  of  the  foot  outwards,  is  associated  with  turning  of 
the  toes  outwards  and  the  heel  inwards.  Thus  the  variety  and  the  range  of  move- 
ments of  the  foot  on  the  leg,  which  at  the  ankle  are  almost  limited  to  flexion  and 
extension,  are  increased.  The  cuboid  moves  with  the  calcaneum,  while  the  scaphoid 
revolves  on  the  head  of  the  astragalus. 

In  walking,  the  heel  is  first  placed  on  the  ground;  the  foot  is  slightly  adducted; 
but  as  the  body  swings  forwards,  first  the  outer  then  the  inner  toes  touch  the  ground, 
the  astragalus  presses  against  the  scaphoid  and  sinks  upon  the  spring  ligament; 
the  foot  then  becomes  slightly  aliducted.  When  the  foot  is  firmly  placed  on  the 
ground,  the  weiglit  is  transmitted  to  it  obliquely  downwards  andinwards,  so  that 
if  the  ligaments  between  the  calcaneum  and  astragalus  did  not  check  abduction, 
inward  displacement  of  the  astragalus  from  the  til:)io-fibular  arch  would  only  be 
prevented  liy  the  tendons  passing  round  the  inner  ankle  (especially  the  tibialis 
po>iticiis).  If  the  ligaments  l)e  too  weak  to  limit  abduction,  the  weight  of  the  body 
increases  it,  and  forces  the  inner  malleolus  and  astragalus  downwards  and  inwards, 
givins  rise  to  flat  foot. 


THE   TARSAL   JOINTS 


271 


The  advantages  of  the  obliquity  and  peculiar  arrangement  of  the  posterior 
calcaneo-astragaloid  articulation  are  seen  in  walking:  (i)  for  the  posterior  facet  of 
the  calcaneum  receives  the  whole  weight  of  the  body  when  the  heel  is  first  placed 
on  the  ground;  (ii)  by  the  upward  pressure  of  this  facet  against  the  astragalus  it 
transfers  the  weight  to  the  ball  of  the  toes  as  the  heel  is  raised,  the  hinder  edge  of 
the  sustentaculum  tali  and  the  anterior  and  outer  part  of  the  upper  surface  of 
the  calcaneum  preventing  the  astragalus  from  being  displaced  too  far  forward 
by  the  superincumbent  weight;  and  (lii)  the  calcaneum  serves  to  suspend  the 
astragalus  when,  with  the  heel  raised  by  muscular  action,  the  other  foot  is  l:)eing 
swung  forwards. 

Tlie  synovial  membrane  is  the  same  as  that  of  the  astragalo-scaphoid  joint. 
The  arteries  and  nerves  are  derived  from  the  same  sources  as  those  of  the  medio- 
tarsal  joints. 


Fig.  255. — External  View  of  ihk  Ligamknisj  ut    ihl  Jroox  and  Ankle. 


Anterb-iuferior  tibio-flbular 
ligament 


Postero-inferior  tibio- 
flbular  ligament 


Fasciculus  of  posterior 
ligament  of  ankle 


Externil  cileaneo- 
scaphoid  lit;ameut 


Posterior  fasciculus  of 
external  lateral  ligament 


Internal  ealeaneo-cuboid 


Dorsal      External    Middle  fasciculus  of  external  lateral 
calcaneo-    calcaneo-  ligament  of  the  ankle 

cuboid       astragaloid 
ligament 


(h)  The  Articul.a.tions  of  the  Anterior  Part  of  the  Tarsus 

These  include  (i)  the  cubo-scaphoid;    (ii)   scapho-cuneiform;    (iii)   intercunei- 
form; and  (iv)  cubo-cuneiform  joints. 


(i)   The  Cubo-scaphoid  Union 

Class. — Diarthrosis.  Subdivision. — A  rthrodia. 

The  ligaments  which  unite  the  cuboid  and  scaphoid  are: 

Dorsal.  Plantar.  Interosseous. 

The  dorsal  cubo-scaphoid  ligament  (fig.  256)  runs  forwards  and  outwards  from 
the  outer  end  of  the  dorsal  surface  of  the  scaphoid  to  the  middle  third  of  the  inner 


272  THE  ARriri'LATIOXS 

border  of  the  cuboid  on  its  dorsal  aspect,  passing  over  the  posterior  external  angle 
of  the  external  cuneiform  l)one.      It  is  wider  externally. 

The  plantar  cubo-scaphoid  ligament  is  a  well-marked  strong  band,  which  runs 
forwards  and  outwards.  h\)\\i  the  phuitar  surface  of  the  scaphoid  to  the  depression 
on  the  inner  surface  of  the  cuV)oid.  and  slightly  into  the  plantar  surface  just  below  it. 

The  interosseous  cubo-scaphoid  ligament  is  a  strong  band  which  passes 
between  the  apixiscd  sin-faces  of  these  bones  from  the  dorsal  to  the  plantar  ligaments. 
Some  of  its  })osterior  til)res  reach  the  plantar  surface  of  the  foot  behind  the  cubo- 
scaphoitl  ligament,  and  radiate  outwards  and  backwards  over  the  inner  border  of 
the  cuboid  to  blend  with  the  anterior  extremity  of  the  short  calcaneo-cuboid 
ligament. 

(ii)  Tlie  Scapho-cuneiform  Articulation 

Class. — D'mrthro^h.  Subdivision. — ArtJirodia. 

The  ligaments  uniting  the  scaphoid  with  the  three  cuneiform  bones  are: — 

Dorsal.  Plantar. 

Internal. 

The  dorsal  scapho-cuneiform  ligament  is  ver}'  strong,  and  stretches  as  a  con- 
tinuous structure  on  the  dorsal  surface  of  the  scaphoid,  between  the  tubercle  of  the 
scaphoid  on  the  inner  side,  and  the  dorsal  cubo-scaphoid  ligament  externalh",  passing 
forwards  and  a  little  outwards  to  the  dorsal  surfaces  of  the  three  cuneiform  bones. 

The  internal  scapho-cuneiform  ligament  is  a  very  strong  thick  band  which 
connects  the  tubercle  of  the  scaphoid  with  the  inner  surface  of  the  internal  cunei- 
form bone.  It  is  continuous  with  the  dorsal  and  plantar  ligaments.  Its  lower 
border  touches  the  tendon  of  the  tibialis  2yosticus. 

The  plantar  scapho-cuneiform  ligament  forms,  like  the  dorsal,  a  continuous 
structure  extending  between  the  plantar  surfaces  of  the  bones.  Its  fibres  pass 
forwards  and  outwards.  It  is  in  relation  below  with  the  tendon  of  the  tibialis 
'posticus. 

It  must  be  uotieed  that  tlie  expanded  tendon  of  insertion  of  the  tihi'ah's  posticus,  and  the 
hgaments  uniting  tlie  scaphoid  -with  the  cuboid  and  cuneiform  bones  pass  forwards  and  outwards, 
while  tlie  peroneus  hmgus  tendon  and  the  ligaments  uniting  the  first  and  second  rows  of  bones, 
except  the  inner  half  of  tlie  dorsal  astragalo-scaphoid  ligaments,  pass  fonvardsand  inwards.  This 
arrangement  is  admirably  adapted  to  presen'e  the  arches  of  the  foot,  and  especially  the  transverse 
arch.  Had  these  tendons  and  ligaments  run  directly  fuiwarrh  all  the  strain  on  the  transverse  arch 
would  liave  fallen  on  the  interosseous  ligaments,  but  as  it  is,  the  arch  is  braced  up  by  the  above- 
mentioned  stractures. 

(iii)  TJic  Intercuneiform  and   (iv)  The  Cubo-runeifomi  Articulations 

Class. — Diarthrosis.  Subdivision. — A  rthrodia. 

The  uniting  ligaments  of  these  bones  are  divided  into  three  sets: 

Dorsal.  Plantar. 

Interosseous. 

The  dorsal  ligaments  are  three  in  number,  two  connecting  the  three  cunei- 
form liones,  and  a  third  uniting  the  external  cuneiform  with  the  cuboid.  They 
pass  between  the  contiguous  margins  of  the  bones,  and  are  blended  behind  with  the 
dorsal  ligaments  of  tlie  cubo-scaphoid  and  scapho-cuneiform  joints. 

The  plantar  ligaments  are  two  in  number:  a  very  strong  one  passes  outwards 
and  forwards  from  the  outer  side  of  the  base  of  the  internal  cuneiform  to  the  apex 
of  the  middle  cuneiform,  winding  somewhat  to  its  outer  side.  The  second  connects 
the  apex  of  the  external  cuneiform  with  the  anterior  half  of  the  inner  surface 
of  the  cuboid  along  its  plantar  border,  joining  Avith  the  plantar  scajiho-cuboid 
ligament  liehind. 

The  interosseous  ligaments  are  three  in  number.     They  are  strong  and  deep 


THE   TARSAL  JOINTS  273 

masses  of  ligamentous  tissue  which  connect  the  middle  cuneiform  with  the  internal 
and  external  cuneiform  ]iones,  and  the  external  cuneiform  with  the  cuboid;  occu- 
pying all  the  non-articular  portions  of  the  apposed  surfaces  of  the  bones.  The 
ligaments  extend  the  whole  vertical  depth  between  the  middle  cuneiform  and  the 
external,  and  the  external  cuneiform  and  the  cuboid,  and  blend  with  the  dorsal 
and  plantar  ligaments;  they  are  situated  in  front  of  the  articular  facets,  and  com- 
pletely shut  off  the  synovial  cavity  behind  from  that  in  front.  The  ligament 
between  the  internal  and  middle  cuneiform  l)ones  occupies  the  inferior  and  anterior 
two-thirds  of  the  apposed  surfaces,  and  does  not  generally  extend  high  enough  to 
separate  the  synovial  cavity  of  the  anterior  tarsal  joint  from  that  of  the  second  and 
third  metatarsal  and  cuneiform  bones.  If  it  does  extend  to  the  dorsal  surface,  it 
divides  the  facets  completely  from  one  another,  making  a  seventh  synovial  sac  in 
the  foot. 

The  synovial  cavity  will  be  described  later  on. 

The  arterial  supply  is  from  the  metatarsal  and  plantar  arteries. 

The  nerves  are  derived  from  the  anterior  tibial,  and  internal  and  external 
plantar. 

The  movement  permitted 'in  these  joints  is  very  limited,  and  exists  only  for 
the  purpose  of  adding  to  the  general  pliancy  and  elasticity  of  the  tarsus  without 
allowing  any  sensible  alteration  in  the  position  of  the  different  parts  of  the  foot,  as 
the  meclio-tarsal  and  calcaneo-astragaloid  joints  do.  It  is  simply  a  gliding  motion, 
and  either  deepens  or  widens  the  transverse  arch.  The  external  cuneiform  being 
wedged  in  between  the  others  is  less  movable,  and  so  forms  a  pivot  upon  which 
the  rest  can  move.  The  movement  is  more  produced  by  the  weight  of  the  body 
than  by  direct  muscular  action;  and  of  the  muscles  attached  to  this  part  of  the 
tarsus,  all  deepen  the  arch  save  the  tibialis  anticus,  which  pulls  the  internal  cunei- 
form up,  and  so  tends  to  widen  it. 

(c)  The  Medio-tarsal  or  Transverse  Tarsal  Joints 

The  articulations  of  the  anterior  and  posterior  portions  of  the  tarsus,  although 
in  the  same  transverse  line,  consist  of  two  separate  joints,  viz.  (i)  an  inner,  the 
astragalo-scaphoid,  which  communicates  with  the  anterior  calcaneo-astragaloid 
articulation;  and  (ii)  an  outer,  the  calcaneo-cuboid,  Avhich  is  complete  in  itself. 
The  movements  of  the  anterior  upon  the  posterior  portions  of  the  foot  take  place 
at  these  joints  simultaneously.  It  will  be  most  convenient  to  deal  Avith  the 
joints  separately  as  regards  the  ligaments;  while  the  arteries,  nerves,  and  move- 
ments will  be  considered  together. 

(i)  The  Astragalo-8caphoid  Articulation 
Class . — Diarthrosis.  Subdivision . — Enarthrodia. 

This  is  the  only  ball-and-socket  joint  in  the  tarsus.  It  communicates  with  the 
anterior  calcaneo-astragaloid  articulation,  and  tw^o  of  the  ligaments  which  close  it 
in  do  not  touch  the  astragalus,  but  pass  from  the  calcaneum  to  the  scaphoid.  The 
uniting  ligaments  are: — 

External  calcaneo-scaphoid.  Inferior  calcaneo-scaphoid. 

Astragalo-scaphoid. 

The  external  calcaneo-scaphoid  has  been  already  described  (page  283). 

The  inferior  calcaneo-scaphoid  ligament  (figs.  2oG  and  257)  is  an  exceed- 
ingly dense  tliick  plate  of  fi])ro-(,'lastic  tissue.  It  extends  from  the  sustentaculum 
tali  and  the  under  surface  of  the  calcaneum  in  front  of  a  ridge  curving  outwards  to 
the  anterior  tubercle  of  that  bone,  to  the  whole  width  of  the  under  surface  of  the 
scaphoid,  and  also  to  the  inner  surface  of  the  scaphoid  behind  the  tubercle. 
Internally  it  is  blended  with  the  anterior  portion  of  the  internal  lateral  ligament  of 
the  ankle,  and  externally  with  the  lower  border  of  the  external  calcaneo-scaphoid 
ligament.  It  is  thickest  along  the  inner  border.  Its  upper  surface  loses  the  well- 
18 


274 


THE  ARTICULATIOXS 


marked  fibrous  appoarancc  whieli  tlie  ligament  lias  in  the  sole,  and  becomes 
smooth  and  faceted.  In  contact  with  the  under  surface  of  the  ligament  the  tendon 
of  the  tibialis  posticu.s  passes,  giving  considerable  support  to  the  head  of  the 
astragalus  by  assisting  the  power  and  protecting  the  spring  of  the  ligament.  The 
fibres  of  the  ligament  run  forwards  and  inwards. 

The  astragalo-scaphoid  ligament  is  a  broad,  tlnn,  l)Ut  well-marked  layer  of 
fibres  which  })asses  from  the  dorsal  and  external  surfaces  of  the  neck  of  the  astragalus 
to  the  whole  length  of  the  dorsal  surface  of  the  scaphoid.  Many  of  the  fibres  con- 
verge to  their  insertion  on  the  scaphoid.     The  fibres  low  down  on  the  outer  side 


Fig.  2.56. — View  of  the  Foot  froiM  above,  with  the  Astragalus  removed  to  show  the 
Inferior  and  External  Calcaneo-scaphoid  Ligaments. 


Dorsal  cubo-scaphoid 
ligament 

Dorsal  caleaneo-cuboid 

ligament 

Internal  ealcaneo-cuboid 

ligament 

External  calcaneo-scaphoid 

ligament 


Cut  edge  of  interosseous 
ligament 


—  Inferior  calcaneo-scaphoid 
ligament 


Tendon  of  tibialis  posticus 


blend  a  little  way  from  their  origin  with  the  upper  edge  of  the  external  calcaneo- 
scaphoid  ligament,  and  then  pass  forwards  and  inwards  to  the  scaphoid;  those  next 
above  pass  obli(]uely  and  with  a  distinct  twist  over  the  upper  and  outer  side  of  the 
head  of  the  astragalus  to  the  centre  of  the  dorsum  of  the  scaphoid,  overlapping 
fibres  from  the  inner  side  of  the  astragalus  as  well  as  some  from  the  anterior  liga- 
ment of  the  ankle-joint. 

Synovial  membrane. — The  astragalo-scaphoid  is  lined  by  the  same  synovial 
membrane  as  the  anterior  calcaneo-astragaloid  joint. 


(ii)    The  Calcaneo-cnhoid  Articulation 
Class. — Dinrthrosis.  Subdivision. — Saddle-shaped  Arthrndia. 

The  ligaments  wliidi  unite  the  bones  forming  the  outer  part  of  tlie  niedio-tarsal 
joint  are: — 


Internal  or  interosseous  calcaneo-cul^oid. 
Long  inferior  caleaneo-cuboid. 


Dorsal  calcaneo-cul)oid. 
Short  inferior  caleaneo-cuboid. 


The  internal  or  interosseous  caleaneo-cuboid  ligament  (fig.  256)  is  a  strong 
band  of  fibres  attached  to  the  os  eakis  along  the  inner  part  of  the  non-articular 


THE   TARSAL   JOINTS 


275 


ridge  above  the  articular  facet  for  the  cul)oid,  and  also  to  the  up})er  part  of  the 
internal  surface  close  to  the  articular  margin,  and  passes  forwards  to  be  attached  to 
tlie  depression  on  the  internal  surface  of  the  cuboid,  and  also  to  the  rough  angle 
between  the  internal  and  inferior  surfaces.  At  tlie  calcaneuni  this  ligament  is 
closijly  connected  witli  the  external  calcaneo-scaphoid  ligament.  Towards  the  sole 
it  is  connected  with  the  short  inferior  calcaneo-cuboid  ligament,  and  superiorly 
with  the  dorsal  calcaneo-culxiid. 

The  dorsal  calcaneo-cuboid  (fig.  256)  is  attached  to  the  dorsal  surfaces  of  the 
two  bones,  extending  low  down  externally  to  blend  with  the  outer  part  of  the 
short  plantar  ligament.  Over  the  inner  half,  or  more,  the  ligament  stretches  some 
distance  l)eyond  the  margins  of  the  articular  surfaces,  reaching  well  forwards  upon 
the  cuboid  to  l)e  attacht^l  about  midway  between  its  anterior  and  jjosterior  borders; 


Fig.  257.  — LiGAMEisTS  of  the  Sule  of  the  Left  Foot. 


Long  plantar  or  long  inferior 
calcaneo-euboid  ligament 


Tendon  of  peroneus  longus 


GROOVE  FOR  FLEXOR  LONGUS 
HALLUCIS 

Inferior  ealeaneo-seaphoid 

ligament 
Short  plantar  or  short  inferior 
calcaneo-euboid  ligament 


T18ERCLE  OF  SCAPHOID 


NTEHNAL  CUNEIFORM 


Insertion  of  peroneus 
longuB 


l)Ut  towards  the  outer  side,  the  ligament  is  much  shorter,  and  is  attaclied  to  the 
cul)oid  beliind  its  tubercle. 

The  long  inferior  calcaneo-cuboid  (tlie  long  plantar)  (fig.  257)  is  a  strong 
dense  band  of  tiljres  which  are  attached  posteriorly  to  the  whok'  of  the  under 
surface  of  the  calcaneuni  l)etween  the  posterior  tubercles  and  the  rounded  eminence 
(the  anterior  tuljercle)  at  the  anterior  end  of  the  bone.  Most  of  its  fibres  pass 
directly  forwards,  and  are  fixed  to  the  outer  two-thirds  or  more  of  the  oblique 
ridge  behind  the  peroneal  groove  on  the  cuboid,  while  some  pass  further  forwards 
and  inwards,  expanding  into  a  broad  layer,  and  are  inserted  into  the  bases  of  the 
second,  third,  fourth,  and  inner  half  of  the  fifth  metatarsal  bones.  This  anterior 
expanded  portion  comi)letes  the  canal  for  the  peroneus  longus  tendon,  and  from  its 
under  surface  arise  the  adductor  hallucis  and  the^<'.ror  hrevis  minimi  digit i  nmscles. 

The  short  inferior  calcaneo-cuboid  (short  plantar)  (fig.  257)  is  attached  to 


276  THE  ARTICULATIONS 

the  rounded  eminence  (anterior  tubercle)  at  the  anterior  end  of  the  under  surface 
of  the  calcaneuni,  and  to  the  bone  in  front  of  it,  and  then  takes  an  obHque  course 
forwards  and  inwards,  and  is  attached  to  the  whole  of  the  depressed  inferior  surface 
of  the  cuboid  behind  the  oblique  ridge,  except  its  outer  angle.  It  is  strongest  near 
its  outer  edge,  and  is  formed  by  dense  strong  fibres. 

The  synovial  membrane  is  distinct  from  that  of  any  other  tarsal  joint. 

The  arterial  supply  i>f  the  medio-tarsal  joints  is  from  the  anterior  tibial,  from 
the  tarsal  and  metatarsal  branches  of  the  dorsalis  pedis,  and  from  the  plantar 
arteries. 

The  nerve-supply  of  the  medio-tarsal  joints  is  from  the  external  division  of 
the  anterior  tibial,  and  occasionalh'  from  the  musculo-cutaneous  or  external 
plantar. 

The  movements  which  take  place  at  the  medio-tarsal  joints  are  mainly  flexion 
and  extension,  witli  superadded  lateral  and  rotatory  movements.  Flexion  at  these 
joints  is  simultaneous  with  extension  of  the  ankle,  and  rice  verm.  Flexion  and 
extension  do  not  take  place  upon  a  transverse,  but  round  an  oblique  axis  which 
passes  from  within  outwards,  and  somewdiat  backw^ards  and  downwards  through 
the  astragalus  and  calcaneum. 

Combined  with  flexion  and  extension  is  also  some  rotatory  motion  round  an 
antero-posterior  axis  which  turns  the  inner  or  outer  border  of  the  foot  upwards. 
There  is  also  a  fair  amount  of  lateral  motion  whereby  the  foot  can  be  inclined 
inwards  (i.e.  adducted)  or  outw'ards  (i.e.  abducted). 

These  movements  of  the  medio-tarsal  joint  occur  in  conjunction  with  those  of 
the  ankle  and  calcaneo-astragaloid  joints.  Rotation  at  the  calcaneo-astragaloid 
joint  is,  however,  round  a.  vertical  axis  in  a  horizontal  plane,  and  so  turns  the 
toes  inwards  or  outwards;  whereas  at  the  medio-tarsal  union,  the  axis  is  antero- 
posterior and  the  inner  or  outer  edge  of  the  foot  is  turned  upwards.  Gliding  at  the 
calcaneo-astragaloid  joint  elevates  or  depresses  the  edge  of  the  foot,  while  at  the 
medio-tarsal  it  adducts  or  abducts  the  toes  without  altering  the  relative  position  of 
the  calcaneum  to  the  astragalus. 

Thus  flexion  at  the  medio-tarsal  joint  is  associated  with  adduction  and  inward 
rotation  of  the  foot,  occurring  simultaneously  wdth  extension  of  the  ankle;  and 
extension  at  the  medio-tarsal  joint  is  associated  with  abduction  and  outward 
rotation,  occurring  simultaneously  Avith  flexion  of  the  ankle. 

Flexion  and  adduction  are  far  more  free  than  extension  and  aViduction,  which 
latter  movements  are  arrested  by  the  ligaments  of  the  sole  as  soon  as  the  foot  is 
brought  into  the  position  in  which  it  rests  on  the  ground. 

Although  the  astragalo-scaphoid  is  a  ball-and-socket  joint,  yet,  owing  to  the 
union  of  the  scaphoid  wdth  the  cuboid,  its  movements  are  limited  by  the  shape  of 
the  calcaneo-cuboid  joint;  this  latter  being  concavo-convex  from  above  downwards, 
prevents  rotation  round  a  vertical  axis,  and  also  any  side-to-side  motion  except 
in  a  direction  obliquely  downwards  and  inwards,  and  upwards  and  outwards.  This 
is  also  the  direction  of  freest  movement  at  the  astragalo-scaphoid  joint.  Movement 
is  also  limited  l)y  the  ligamentous  union  of  the  calcaneum  with  the  scaphoid.  The 
tw'isting  movement  of  the  foot,  such  as  turning  it  upon  its  inner  or  outer  edge,  and 
the  increase  or  diminution  of  the  arch,  take  place  at  the  tarsal  joints,  especially  the 
medio-tarsal  and  calcaneo-astragaloid  articulations.  Here  too  those  changes  occur 
which,  owing  to  paralysis  of  some  muscles  or  contraction  of  others,  result  in  talipes 
equino-varus,  or  valgus. 


6.  THE  TARS0-METATAR8AL  ARTICULATIONS 

There  may  be  said  to  l)e  three  articulations  between  the  tarsus  and  metatarsus,, 
viz: — 

(a)  Tlie  Internal,  between  the  inner  cuneiform  and  first  metatarsal  bones. 

(h)  The  Middle,  between  the  three  cuneiform  and  second  and  tliird  metatarsal 
bones. 

(c)  The  Outer,   or  cnbo-metatarsal,  between  the  cuboid    and    fourth  and  fifth 
metatarsal  bones. 


THE   TARSO- METATARSAL  277 

Tlio arteries  for  the  tarso-metatarsal  joints  are  derived:  (1)  for  the  internal, 
from  the  dorsahs  pedis  and  internal  plantar;  (2;  for  the  rest,  twigs  from  the  meta- 
tarsal and  deep  plantar  arches. 

The  nerve-supply  comes  from  the  anterior  tibial  and  plantar  nerves. 

The  movements  permitted  at  these  joints  are  flexion  and  extension  of  the 
metatarsus  on  the  tarsus;  and  at  the  inner  and  outer  divisions,  slight  addtiction  and 
abduction.  In  the  outer,  the  lateral  motion  is  freer  than  in  the  inner  joint,  and 
freest  between  the  fifth  metatarsal  bone  and  the  cuboid.  In  the  inner  joint,  flexion 
is  combined  with  slight  abduction,  and  extension  with  adduction. 

There  is  also  a  little  gliding,  which  allows  the  transverse  arch  to  be  increased 
or  diminished  in  depth ;  the  inner  and  outer  two  bones  sliding  downwards,  and  the 
two  middle  a  little  upwards,  when  the  arch  is  increased;  and  vice  verm  when  the 
arch  is  flattened. 

(a)  The  Internal  Tarso-metatarsal  .Joint 
Class. — Diarthrosis.  Subdivision. — Arthrodia. 

A  complete  capsular  ligament  unites  the  first  metatarsal  with  the  internal 
cuneiform,  the  fibres  of  which  are  very  thick  on  the  under  and  inner  aspects; 
those  on  the  outer  side  pass  from  behind  forAvards  in  the  interval  between  the 
interosseous  ligaments  which  connect  the  two  bones  forming  this  joint  with  the 
second  metatarsal.  The  ligament  on  the  plantar  aspect  is  by  far  the  strongest,  and 
blends  at  the  cuneiform  bone  with  the  scapho-cuneiform  ligament. 


(b)  The  Middle  Tarso-metatarsal  Joint 
Class. — Diarthrosis.  Subdivision. — Arthrodia. 

Into  tins  union  there  enter  the  three  cuneiform  and  second  and  third  metatarsal 
Ijones,  which  are  bound  together  by  the  following  ligaments:  dorsal,  plantar,  inter- 
osseous. 

The  dorsal  ligaments. — 1.  Some  short  fibres  cross  obliquely  from  the  outer 
edge  of  the  internal  cuneiform  bone  to  the  inner  border  of  the  base  of  the  second 
metatarsal  bone;  they  take  the  place  of  a  dorsal  metatarsal  ligament  wliich  is 
wanting  between  the  first  and  second  metatarsal  bones. 

2.  Between  the  middle  cuneiform  and  the  base  of  the  second  metatarsal  bone 
some  fibres  run  directly  forwards. 

3.  The  external  cuneiform  is  connected  with  (1)  the  outer  corner  of  the  second 
metatarsal  bone  by  a  narrow  band  passing  obliquely  inwards  ;  (2)  with  the  third 
metatarsal  by  fibres  passing  directly  forwards  ;  and  (3)  with  the  fourth  metatarsal 
l)y  a  short  band  passing  obli(|uely  outwards  to  the  inner  edge  of  its  base. 

The  plantar  ligaments. — A  strong  ligament  unites  the  internal  cuneiform  and 
the  bases  of  the  second  and  third  metatarsal  bones.  The  tibialis  -posticus  is 
inserted  into  these  bones  close  beside  it.  Other  slender  ligaments  connect  the 
middle  cuneiform  Avith  the  second,  and  the  external  cuneiform  with  the  third 
metatarsal  Ijones. 

The  interosseous  ligaments. — (1)  A  strong  broad  interosseous  ligament 
extends  between  the  outer  surface  of  the  internal  cuneiform,  and  the  inner  surface 
of  the  base  of  the  second  metatarsal  bone.  It  is  attached  to  both  bones  below 
and  in  front  of  the  articular  facets,  and  separates  the  middle  from  the  internal 
tarso-metatarsal  joint.  (2)  A  second  band  is  attached  behind  to  a  fossa  on  the 
anterior  and  outer  edge  of  the  external  cuneiform  and  to  the  interosseous  ligament 
between  it  and  the  cuboid,  and  passes  horizontally  forwards  to  be  attached  to  the 
whole  depth  of  the  fourth  metatarsal  bone  behind  its  internal  lateral  facet,  and  to 
the  opposed  surfaces  of  the  third  and  fcnirth  below  their  lateral  articular  facets.  It 
separates  the  middle  tarso-metatarsal,  and  intermetatarsal  between  the  third  and 
fourth  bones,  from  the  cubo-metatarsal  joint.  It  is  more  firmly  connected  with  the 
third  bone  than  with  the  fourth.  (3)  A  slender  ligament  composed  only  of  a  few- 
fibres  often  passes  from  a  small  tubercle  on  the  inner  and  anterior  edge  of  the 


278 


THE  A  H  Tin  LA  TIONS 


external  cimeiforin  to  a  groove  on  tlie  outer  edge  of  tlie  second  metatarsal  bone 
between  the  two  lateral  facets. 

The  synovial  membrane  is  jirolonged  forwards  from  that  of  the  scapho-cunei- 
form  and  inter-cuncifonn  articulations. 


((•)  The  Cubo-metatarsal   Joint 
Class. — Dinrthrosis.  Subdivision. — Arthrod'm. 

The  bones  comprising  this  joint  are  the  fourth  and  fifth  metatarsal,  and  the 
anterior  surface  of  the  cul)oid,  iirmly  connected  on  all  sides  by 


Dorsal. 


Plantar. 


Interosseous  ligaments. 


The  plantar  cubo-metatarsal    ligament    is  a  broad,   Avell-marked  ligament, 
Avhich  extends  from  tlic  cuboid  behind  to  the  bases  of  tlie  fourth  and  fifth  meta- 


FiG.  258. — Section  to  show  the  Synovial  Cavities  of  the  Foot. 


1.  Posterior  calcanco-astragaloid. 
4.  Tarsal. 


2.  Calcaneo-cuboid. 
5.  Cubo-metatarsal. 


3.  Anterior  calcaiieo-astragalo-scaphoid. 
6.  First  metatarso-cuneiforin. 


tarsal  bones  in  front.  It  is  continuous  along  the  groove  at  the  base  of  tlie  fifth 
metatarsal  bone  ■v\nth  the  dorsal  ligament,  ancl  as  it  passes  round  the  outer  border 
of  tlie  foot  it  is  somewhat  thickened,  and  may  be  described  as  the  external  cubo- 
metatarsal  ligament.  On  its  inner  side  it  joins  the  interosseous  ligaments,  thus 
(•om|ik'tiiig  tlie  cajjsule  below.  It  is  not  a  thick  structure,  and  to  see  it  the  long 
plantar  ligament,  the  peroneus  longus,  and  external  slip  of  the  tibialis  posticus 
must  be  removed;  the  attachment  of  these  structures  to  the  fourth  and  fifth  meta- 
tarsal bones  considera})ly  assists  to  unite  them  with  the  tarsus. 

The  dorsal  cubo-metatarsal  ligament  is  composed  of  fibres  which  pass 
o])liquely  outwards  and  forwards  from  the  cuboid  to  the  bases  of  the  fourth  and 
fifth  metatarsal  hones.  They  complete  the  cajisule  above,  and  are  continuous 
externally  with  the  external  cubo-metatarsal  ligament. 

The  interosseous  ligament  shuts  off  the  cubo-metatarsal  from  the  middle  tarso- 
metatarsal joint.  It  is  attached  to  the  external  cuneiform  behind,  and  to  the 
whole  depth  of  the  fourth  metatarsal  Ix'hind  its  internal  lateral  facet,  and  to  the 
apposed  surfaces  of  the  third  and  fourth  bones  lielow  their  articular  facets.  It  is 
continuous  Ijclow  witli  the  ]ilaiitar  ligament. 

The  synovial  membrane  is  separate  from  the  other  synovial  sacs  of  the  tarsus, 
and  is  continued  between  the  fourth  and  fifth  metatarsal  bones. 


THE  METATARSO-PHALANGEAL  279 

7.  THE  IXTERMETATARSAL  ARTICULATIONS 
Class. — Di((rthroi<iK.  Subdivision. — Arthrodia. 

The  bases  of  the  metatarsal  hones  are  firmly  held  in  |)osition  V)y  dorsal,  plantar, 
and  interosseous  ligaments.  The  first  occasionally  articulates  by  means  of  a  distinct 
facet  with  the  second  metatarsal  (figs.  183  and  184,  Section  I). 

The  dorsal  ligaments  are  broad,  membranous  bands  passing  between  the  four 
outer  toes  on  their  dorsal  aspect;  but  in  place  of  one  between  the  first  and 
second  metatarsal  bones  a  ligament  extends  from  the  internal  cuneiform  to  the 
base  of  the  second  metatarsal  bone  (page  277). 

The  plantar  ligaments  are  strong,  thick,  well-marked  ligaments  Avhich  connect 
the  bones  on  their  plantar  aspect. 

The  interosseous  ligaments  are  three  in  number,  very  strong,  and  are  situated 
at  the  points  of  union  of  the  shaft  with  the  bases  of  the  bones,  and  fill  up  the 
sulci  on  their  sides.     They  limit  tlic  synovial  cavities  in  front  of  the  synovial  facets. 

The  common  synovial  membrane  of  the  tarsus  extends  between  the  second  and 
third,  and  third  and  fourth  bones;  that  of  the  cubo-metatarsal  joint  extending 
between  the  fourth  and  fifth. 

The  arterial  and  nerve-supply  is  the  same  as  for  the  tarso-metatarsal  joints. 

The  movements  consist  merely  of  gliding,  so  as  to  allow  the  raising  or  widening 
of  the  transverse  arch.  Considerable  flexibility  and  elasticity  are  thus  given  to  the 
anterior  part  of  the  foot,  enabling  it  to  become  moulded  to  the  irregularities  of  the 
ground. 

The  Union  of  the  Heads  of  the  Metatarsal  Bones 

The  heads  of  the  metatarsal  bones  are  connected  on  their  plantar  aspect  by 
the  transverse  ligament,  consisting  of  four  bands  of  fibres  passing  transversely 
from  bone  to  bone,  blending  with  the  fibro-cartilaginous  or  sesamoid  plates  of  the 
metatarso-phalangeal  joints,  and  the  sheaths  of  the  flexor  tendons  where  the}^  are 
connected  with  the  fibro-cartilages.  It  differs  from  the  corresponding  ligament 
in  the  hand  by  having  a  band  from  the  first  to  the  second  metatarsal  bone. 


8.  THE  METATARSO-PHALAXGEAL  ARTICULATIONS 

{(C)  The  Metatarso-phalanctEal  Joints  of  the  Four  Outer  Toes 

Class. — Diaii?trnsis.  Subdivision. — Condylarthrosis. 

These  joints  are  formed  by  the  concave  proximal  ends  of  the  first  phalanges 
articulating  with  the  rounded  heads  of  the  metatarsal  bones,  and  united  by  the 
following  ligaments: — 

Two  lateral.  Dorsal.  Plantar  sesamoid  plate. 

The  two  lateral  ligaments  are  strong  bands  passing  from  a  ridge  on  each  side 
of  the  head  of  the  metatarsal  bone  to  the  sides  of  the  proximal  end  of  the  first 
phalanx,  and  also  to  the  sides  of  the  sesamoid  plate  Avhich  unites  the  two  bones 
on  their  plantar  surfaces.  On  the  dorsal  aspect  they  are  united  by  the  dorsal 
ligament. 

The  dorsal  ligament  consists  of  loose  fine  fibres  of  areolo-fibrous  tissue,  extend- 
ing between  the  lateral  ligaments,  thus  completing  a  capsule.  It  is  connected  by 
fine  fibres  to  the  under  surface  of  the  extensor  tendons,  which  pass  over  and 
considerably  strengthen  this  portion  of  the  capsule. 

The  plantar  sesamoid  plate  helps  to  deepen  the  shalktw  facet  of  the  phalanx 
for  the  head  of  the  metatarsal  bone,  and  corresponds  to  the  glenoid  ligament  of 
the  fingers.  It  is  firmly  connected  to  the  lateral  ligaments  and  the  transverse  liga- 
ment, and  is  grooved  inferiorly  where  the  flexor  tendons  pass  over  it.  It  serves  to 
prevent  dorsal  dislocation  of  the  phalanx. 


280  THE  ARTICULATIONS 

The  second  metatarso-jihalanfieal  joint  is  a  quarter  of  an  inch  in  front  of  hoth 
the  first  and  third  metatarso-phalangeal  joints. 

The  third  nietatarso-i)halangeal  joint  is  a  quarter  of  an  inch  in  front  of  the 
fourtli,  and  the  fourth  three-eighths  of  an  incli  in  front  of  tlie  fifth. 

The  head  of  the  fifth  metatarsal  is  in  hne  with  the  neck  of  the  fourth. 

Thus  the  outer  side  of  the  longitudinal  arch  of  the  foot  is  shorter  than  the  inner; 
it  is  also  distinctly  shallower. 


(6)  The  Metatarso-phalangeal  Joints  of  the  Great  Toe 

The  metatarso-phalangeal  joint  of  the  great  toe  difiers  from  the  rest  in  the 
following  particulars: — 

( 1 )  The  ]x>nes  are  on  a  larger  scale,  and  the  articular  surfaces  are  more  extensive. 

(2)  There  are  two  grooves  on  the  plantar  surface  of  the  metatarsal  lione,  one 
on  each  side  of  the  median  line,  for  the  sesamoid  bones. 

(o)  The  sesamoid  bones  replace  the  fibro-cartilaginousor  sesamoid  plate.  They 
are  two  small  hemispherical  bones  developed  in  the  tendons  of  the  flexor  brevis 
hallucis,  convex  below,  but  flat  above  where  they  play  in  grooves  on  the  head  of 
the  metatarsal  bone;  they  are  united  by  a  strong  transverse  ligamentous  liand, 
which  is  smooth  below  and  forms  ]iart  of  the  channel  along  which  the  long  flexor 
tendon  plays.  They  are  firmly  united  to  the  base  of  the  phalanx  b}''  strong  short 
fibres,  but  to  the  metatarsal  bone  they  are  joined  by  somewhat  looser  fibres. 
Laterally  they  are  connected  with  the  lateral  ligaments  and  the  sheath  of  the 
flexor  tendons.  They  provide  shifting  leverage  for  the  Jiexxir  brevis  haUuci>!  as 
well  as  for  the  flexor  longus  hallucis. 

The  arteries  come  from  the  digital  and  interosseous  branches;  and  the  nerves 
from  the  cutaneous  digital,  or  horn  small  twigs  of  the  nerves  to  the  interossei 
muscles. 

The  movements  permitted  are:  flexion,  extension,  alxluction,  adduction,  and 
circumduction. 

Flexion  is  more  free  than  extension,  and  is  limited  by  the  extensor  tendons  and 
dorsal  ligaments;  extension  is  limited  b}'  the  flexor  tendons,  the  plantar  fibres  of  the 
lateral  ligaments,  and  the  sesamoid  plates.  The  lateral  motion  is  possible  from  the 
shai)e  of  the  bony  surfaces,  but  is  very  limited,  being  most  marked  in  the  great  toe. 
It  is  limited  by  the  lateral  ligaments  and  sesamoid  plates. 


9.  THE  INTERPHALANGEAL  JOINTS 
Class. — Diarthrosis.  Subdivision. — Gii)f/li/mus. 

The  articulations  between  the  first  and  second,  and  second  and  third  ]ilialanges 
of  the  toes  are  similar  to  those  of  the  fingers,  with  this  important  dift'ercnce, 
that  the  l>ones  are  smaller  and  the  joints,  especially  l)etween  the  second  and  third 
phalanges,  are  often  ankylosed.      The  ligaments  which  unite  them  are: — 

Two  lateral.  Dorsal.  Glenoid  ligament. 

The  two  lateral  ligaments  are  well  marked,  and  i)ass  on  each  side  of  the  joints 
from  a  little  rough  dei)ression  on  the  head  of  the  proximal,  to  a  rough  border  on 
the  side  of  tlie  base  of  the  distal  phalanx  of  the  joint. 

Tlie  dorsal  ligament  is  thin  and  membranous,  and  extends  across  the  joint 
from  one  lateral  ligament  to  the  other  beneath  the  extensor  tendon,  with  the  deej) 
surface  of  which  it  is  connected,  and  by  which  it  is  strengthened. 

The  glenoid  ligament  covers  in  the  joint  on  the  ))lantar  surface.  It  is  a  fibro- 
cartilaginous ])late,  connected  at  the  sides  with  the  lateral  ligaments,  and  with  the 
l>ones  l)y  short  ligamentous  fibres;  the  plantar  surface  is  smooth,  and  grooved  for 
the  flexor  tendons. 

The  arteries  and  nerves  are  derived  from  the  corresjionding  digital  branches. 

The  only  movements  permitted  at  these  joints  are  iiexion  and  extension. 


MORPHOLOGY  OF  LIGAMENTS  281 

At  the  interphalangeal  joint  of  the  great  toe  there  is  very  frequently  a  small 
sesamoid  bone  whicli  plays  on  the  plantar  surface  of  the  first  i)halanx,  in  the  same 
way  as  the  sesamoid  l)ones  of  the  metatarso-plialangeal  joint  play  upon  the  plantar 
surface  of  the  head  of  the  metatarsal  bone. 


Morphology  of  lAgaments 

The  various  ligaments  of  the  human  body  have,  in  very  many  instances,  been  evolved  as  the 
result  of  secondary  changes  in  muscles  adjacent  to  joints.  In  a  few  instances,  ligaments  repre- 
sent the  degenerate  remnants  of  cartilaginous  and  bony  elements.  0a])sular  ligaments  are  in  most 
joints  derived  from  the  periosteum,  but  they  may  be  strengthened  by  the  incorporation  of  tendons 
detached  from  adjacent  muscles. 

Muscles  arising  from,  or  inserted  into  bones  in  tlie  immediate  vicinity  of  a  joint  tend  to 
become  metamorphosed  into  tendon  near  their  attachments,  and  a  comprehensive  study  of 
myology  in  low  vertebrate  forms  indicates  that  thei'e  is  associated  with  this  tissue-change  a 
tendency  for  the  muscle  to  alter  its  point  of  attachment ;  hence  a  muscle  originally  inserted  below 
a  joint  may  eventually  come  to  have  its  insertion  above  the  joint.  In  the  same  way,  a  muscle 
arising  above  a  joint  may,  as  a  result  of  altered  environment,  sbitt  its  origin  to  some  point  below 
the  joint.  To  this  change  of  position  the  term  migration  of  muscles  has  been  applied.  In  many 
instances  a  portion  of  the  muscle  equivalent  to  the  distance  between  the  original  and  the  acquired 
attachment  ])ersists  as  a  fibrous  band  and  fulfils  the  function  of  a  ligament.  This  is  well  seen  in 
the  knee-joint,  where  the  internal  lateral  ligament  is  derived  from  the  adductor  magnus,  this 
muscle  having  shifted  its  insertion  from  the  tibia  to  the  femur.  In  the  same  waj*  the  external 
lateral  ligament  represents  the  tendon  of  the  peroneus  longus,  which  has  migrated  from  the 
femur  to  the  head  of  the  fibula. 

One  of  the  most  remarkable  examples  of  a  tendon  divorced  in  this  way  is  the  ligamentum 
teres  in  the  hip-joint.  This  curious  structure  was  in  all  probability  the  tendon  of  the  pectineus, 
which  has  been  detached  from  the  muscle  in  consequence  of  the  profound  alterations  which  have 
taken  place  in  the  limb  during  its  evolution. 

Among  other  ligaments  derived  in  a  similar  way  from  muscles  may  be  mentioned  the  greater 
sacro-sciatic  ligament.  This  was  originally  the  tendon  of  origin  of  the  biceps  femoris.  (H. 
Morris,  "A  Note  on  Three  Points  in  Anatomy,"  Med.  Times  and  Gazette,  April  7,  1S77,  p.  361.) 
The  lesser  sacro-sciatic  is  derived  from  the  fibrous  retrogression  of  portions  of  the  coccygeus.  The 
sacro-coccygeal  ligaments  represent  the  muscles  which  lift,  depress,  and  wag  the  tail  in  those 
mammals  furnished  with  such  an  appendage  ;  indeed,  these  ligaments  are  occasionally  replaced 
by  muscle-tissue. 

The  coraco-humeral  ligament  is  derived  from  the  original  tendon  of  insertion  of  the  pectoralis 
minor,  and  not  unfrequentl.y  the  muscle  is  inserted  into  the  lesser  tuberosity  of  the  humerus,  the 
ligament  being  then  replaced  by  the  tendon  of  the  muscle.  The  coraco-clavicular,  rhomboid,  and 
gleno-humeral  ligaments  are  probably  derived  from  modifications  of  the  subclavius  mu.scle. 

The  vertebral  column  contains  several  ligamentous  structures  of  great  morphological  interest. 
The  pulpy  substance  in  the  centre  of  each  intervertebral  disc  is  derived  from  the  notochord  ;  the 
suspensory  ligament  passing  from  the  tip  of  the  odontoid  process  to  the  anterior  margin  of  the 
foramen  magnum  is  a  remnant  of  the  sheath  of  the  notochord,  and  indicates  its  position  as  it 
passed  from  the  vertebral  column  into  the  base  of  the  cranium.  The  transverse  ligament  of  the 
atlas  (as  pointed  out  by  Professor  Cleland  in  1859  and  1861),  is  a  persistent  and  functional  form 
of  the  posterior  conjugal  ligament  uniting  the  rib-heads  in  seals  and  many  other  mammals,  whilst 
the  interosseous  ligament  of  the  head  of  a  rib  in  man  is  the  feeble  representative  of  this  structure 
in  the  thoracic  region  of  the  spine.  The  ligamentum  conjugale  costarum  was  described  by  Mayer 
in  1834  (Archives  d' Anatomic  de  Muller).  According  to  Luschka's  account  of  this  ligament  it 
would  seem  as  though  the  po.sterior  .superior  fibres  of  the  capsule  of  the  costo-central  joint  repre- 
sented it  in  man,  rather  than  the  interos.seous  ligament. 

Many  of  the  subcutaneous  tracts  of  fascia  and  many  aponeuroses  in  the  human  body  are 
derived  from  the  metamorphosis  and  retrogression  of  muscle-tissue. 


^^^-'■*    ^%^*,^^^r 


SECTIOISr    III 

THE  MUSCLES 

By  J.  N.  C.  DAVIP]8  COLLEY.  M.A.,  M.C.Cantab.,  F.R.C.S. 

SURGEON    TO    AND    LECTURER  ON   SURGERY    AT    GUY'S    HOSPITAL  ;     MEMBER   OF   THE   COURT   OF    EXAMINERS   OF  THE 
KOVAL  COLLEGE  OF  SURGEONS  OF  ENGLAND;   FORMERLY   LECTURER  ON   ANATOMY   AT  GUY'.S   HOSPITAL 


THE  Muscles  consist  chiefly  of  transversely  striated  fibres  arranged  in  fasciculi 
or  bundles  of  various  sizes;  and  also  of  white  fibrous  tissue,  which  forms  the 
flattened  cords  or  sheets,  the  tendons  and  aponeuroses,  as  they  are  called,  by 
which  most   of  the  muscles  at  one  or  both  ends  are  attached  to  the  bones  or 
cartilages. 

In  the  account  of  each  individual  muscle,  it  is  convenient  to  divide  the  descri]>- 
tion  into  seven  heads,  viz.: — 1.  the  name;  2.  the  shape;  3.  the  attachments;  4. 
the  structure:  5.  the  nerve-supply;  6.  the  action;  and  7.  the  relations.  A  short 
account  also  of  the  more  important  variations  will  be  added. 

1.  The  name  is  given  for  various  causes,  and  frequently  when  it  consists  of 
more  than  one  word,  for  two  or  even  three  causes,  viz. :  (a)  the  supposed  action, 
e.g.  adductor  and  sartorius;  (&)  the  shape,  e.g.  triangularis  and  lumbricalis;  (c) 
the  direction,  e.g.  rectus  (straight),  obliquus  (slanting);  (c?)  the  position,  e.g. 
subliniis  (near  the  surface),  profundus  (far  from  it),  gluteus  (in  connection  with 
the  nates);  (e)  its  divisions  and  complexity,  e.g.  biceps,  triceps,  multifidus;  (/) 
its  size,  as  magnus,  minimus,  &c. ;  (gr)  its  attachments,  e.g.  sterno  -  cleido- 
mastoideus. 

2.  The  shape  is  sometimes  difficult  to  define  on  account  of  the  irregularity  of 
the  outline,  and  curvature  of  the  surfaces  of  the  muscle.  Some  are  narrow  and 
of  a  flattened  cylindrical  form,  which  may  be  designated  riblwn-shaped.  Many  of 
these  are  diminished  at  their  extremities,  and  mav  be  called  fusiform  or  spindle- 
shaped.  Others  are  broad,  and  form  sheets  of  various  thicknesses,  which,  according 
to  their  outline,  may  be  described  as  fan-shaped,  rhomboidal,  triangular,  or  quadri- 
lateral. Many,  again,  are  compound  muscles  with  double  or  multiple  origins  or 
insertions,  which  are  called,  from  this  cause,  bicipital,  trifid,  &c.  This  is  often  the 
case  when  a  strong  muscle  arises  from  many  points  of  bone,  or  when  a  muscle 
divides  into  many  tendons  below  to  move  several  small  levers,  such  as  the  bones  of 
the  fingers  and  toes.  A  few  have  tendons  intercalated  in  their  length,  and  are 
called  biventral  or  digastric  muscles.  It  is  in  some  cases  diflicult  to  comprehend 
why  certain  nuiscles,  on  the  one  hand,  which  appear  to  be  separate,  are  grou])ed 
under  one  name  as  a  compound  muscle;  and,  on  the  other  hand,  muscles  which 
might  very  well  be  combined  are  distinguished  by  separate  names.  The  principle 
of  distinction  appears  to  have  been  to  group  muscles  which  combine  to  form  one 
belly,  and  to  separate  those  in  which  the  tendons  alone  are  united. 

3.  Of  the  attachments,  the  more  fixed  end  of  the  muscle  is  usually  called  the 
origin,  the  mure  iiioval)le  the  insertion.     In  enumerating  the  various  points  of 

282 


STRUCTURE  OF  THE  MUSCLES  283 

attachment,  it  is  very  necessary  to  bear  in  mind  not  only  those  to  bone  and 
curtilage,  but  also  those  to  the  til)roiis  septa  and  aponeuroses  which  lie  between 
and  around  the  muscles.  Such  attachments  are  best  seen  when  the  area  of 
bone  surface  available  for  origin  or  insertion  is  small.  By  this  means  a  very 
great  extension  is  given  to  this  area,  and  a  small  bony  process,  such  as  the  inner 
condyle  of  the  humerus,  is  able  to  give  a  firm  resistance  to  the  traction  of  many 
strong  muscles. 

4.  The  structure  will  include  not  only  the  direction  and  cur\'-ature  of  the  fleshy 
fibres,  and  the  extent  of  fibrous  tissue  by  which  these  fibres  arise  or  are  inserted ; 
but  also  the  internal  arrangement  of  tendons  and  muscular  fibre,  which  is  often 
of  a  somewhat  complicated  character.  The  simplest  structure  of  all  is  that  of 
muscles  with  no  tendons,  in  which  the  fleshy  fibres  run  parallel  from  one  end  to 
the  other.  Many  of  the  small  muscles  of  the  face  are  of  this  character.  The 
sterno-mastoid  and  sartorius  are  examples  also  of  muscles  in  which  the  parallel 
fleshy  fibres  form  nearly  the  whole  of  the  structure.  It  will  be  found  that  in  these 
muscles,  on  account  of  the  number  of  joints  passed  over  and  the  distance  of  the  line 
of  the  muscle  from  the  axes  of  these  joints,  the  range  of  movement  is  very  great. 
In  most  parts  of  the  body,  however,  there  would  be  a  great  waste  of  fleshy  fibre  if 
this  arrangement  prevailed.  Roughly  speaking,  we  may  say,  that  when  fleshy 
fibres  contract  fully,  their  length  is  diminished  by  one  half.  Now,  if  the  distance 
l)etween  the  movable  points  of  the  skeleton  which  are  joined  by  the  muscles  can- 
not l)e  lessened  by  this  amount,  it  is  obvious  that  some  of  the  contractile  power 
of  the  muscle  would  be  wasted.  When,  therefore,  the  movable  points  of  the 
skeleton  bridged  by  a  muscle  can  only  be  approximated  through  a  limited  space, 
it  will  be  found  that  the  parallel  fleshy  bundles  are  about  twice  the  length  of  this 
space,  and  that  the  rest  of  the  muscle  consists  of  inextensible  tendon,  which  acts 
simply  as  a  ligament  to  attach  the  contractile  muscle  to  the  bones.  But  this 
addition  of  tendon  to  the  fleshy  part  of  the  muscle  is  effected  in  various  ways.  The 
simplest  plan  is  that  in  which  the  addition  is  made  at  one  end  or  the  other  of  the 
muscle.  The  palmaris  longus  is  to  some  extent  an  example  of  such  an  arrange- 
ment. By  examining  the  bones  it  will  be  seen  that  the  front  of  the  carpus  cannot 
be  approximated  to  the  internal  condyle  of  the  humerus  by  more  than  three  inches. 
The  fleshy  bundles  are,  therefore,  of  about  twice  this  length,  and  they  are  accumu- 
lated towards  the  upper  end  of  the  muscle,  while  the  rest  of  its  length  is  occupied 
by  a  long  tendon.  A  more  common  arrangement  is  for  the  short  fleshy  fibres  to 
arise  in  succession  along  the  surface  of  a  long  bone  or  from  an  intermuscular 
septum,  and  to  pass  in  parallel  lines  to  the  end  and  side  of  a  long  tendon,  which 
gradually  thickens  with  the  increase  of  the  number  of  the  fibres  inserted  into  it. 
Such  a  muscle  is  like  a  feather,  of  which  the  quill  with  its  diminishing  upper 
extremity  Avill  represent  the  tendon,  and  the  barbs  upon  one  side  of  it  the  fleshy 
fibres.  Hence  this  arrangement  is  called  penniform,  from  penna,  a  feather  (fig. 
259).  This  form  is  found  when  consideral)le  power  is  required,  but  with  only  a 
small  range  of  movement.  To  appreciate  fully  the  effect  of  such  a  muscle,  Ave 
should  in  our  imagination  take  all  the  short  parallel  fibres  and  place  them  side  by 
side  at  the  end  of  the  tendon.  The  muscle  would  then  be  converted  into  a  very 
thick  and  short  fleshy  mass  with  a  very  long  tendon. 

Frequently  a  muscle  arises  in  two  lines  from  the  adjacent  surfaces  of  two  bones, 
from  which  two  sets  of  parallel  fibres  converge  upon  a  tendon  which  runs  down  in 
the  interval  between  the  bones.  This  arrangement  resembles  a  feather  with  barbs 
on  either  side  of  the  quill,  and  is  called  hipenniform.  Examples  of  both  these 
forms  are  found  in  the  leg.  The  peronei  arising  from  the  fibula  alone  are  penni- 
form, while  the  til)ialis  posticus  and  soleus,  arising  from  l)oth  tibia  and  fibula,  are 
bipenniform. 

In  some  cases  a  further  complication  is  introduced  by  the  origin  of  a  muscle 
from  both  sides  of  several  fibrous  septa,  as  well  as  from  the  intermediate  surfaces 
of  the  bone  to  which  the  septa  are  attached.  The  insertion  may  also  be  of  the  same 
character.  A  good  example  of  this,  which  is  called  the  mu  hi  penniform  arrange- 
ment, is  the  deltoid,  a  very  powerful  muscle  with  a  short  range  of  movement. 

In  some  few  cases  the  tendon  is  intercalated  between  two  fleshy  masses.  Such 
muscles  are  called  biventral.     The  central  tendon  may  represent  a  bony  structure 


284 


THE  MUSCLES 


found  in  lower  Vertebrata;  and  the  two  bellies  may  sometimes  be  fairly  regarded 
as  distinct  muscles,  e.g.  those  of  the  digastric  muscle.  In  some  cases  the  central 
tendon  may  be  of  some  service  in  preventing  the  pressure  upon  subjacent  tissues 
which  would  occur  if  the  muscle  were  at  this  point  fleshy  and  free  to  thicken  as  it 
contracted.  For  example,  it  has  been  suggested  that  the  central  tendon  of  the 
omo-hyoid  prevents  that  muscle  from  compressing  the  great  vessels  of  the  neck  as 
it  crosses  them  beneath  the  sterno-mastoid.  In  one  muscle,  the  rectus  abdominis, 
several  of  tlicse  tendinous  intersections  are  found. 

5.  Nerve-supply. — This  is  of  much  importance,  not  only  from  a  medical  and 
surgical  point  of  view,  when  the  paralysis  or  sjiasmodic  contraction  of  individual 
muscles  has  to  be  accounted  for,   but  also  because  of  the  light  which  it  throws 


Fig.  259. — Diagram  showing  Penniform  Muscle,  the  Peroneus  Longus  ;  and 
bipexniform,  the  tibialis  posticus. 


Peroneus  longus 


Tibialis  posticus 


Upon  tlic  actions  of  muscles,  and  the   assistance  wliich   it  sometimes  gives  us  in 
grouping  thiMu. 

6.  Action. — Most  muscles  act  upon  the  levers  formed  ))y  the  movable  bones 
and  cartilages.  It  will  be  convenient,  however,  first  to  speak  of  those  which  do 
not  act  in  this  manner.  When  a  muscle  passes  from  a  fixed  point  like  a  bone  to  a 
freely  movable  point  such  as  the  under  surface  of  the  skin  or  mucous  membrane, 
it  will  simply  tend  to  ap]>roxiniate  the  movable  ])oint  to  the  fixed  origin.  Such 
muscles  are  found  in  abundance  in  the  face,  and  the  azygos  uvula^  is  a  good 
example  of  one  Avhich  acts  upon  mucous  membrane.  Again,  the  fibres  of  many 
muscles  run  in  parallel  curves,  which  combine  to  form  a  curved  band  or  sheet. 
The  first  (>ffect  of  the  contraction  of  such  a  muscle  will  be  to  straighten  or  flatten 
out  the  curve.     If  this  lies  over  a  convex  surface,  as  is  usually  the  case,  the  action 


THEIR  ACTION  AS  LEVERS  285 

of  the  nmsc'le  will  1)e  to  eoni})ress  the  structures  lyinf;;  in  its  concavity.  The  buc- 
cinator and  alxloniinal  muscles  are  good  examples  of  tliis  form  of  muscle.  Or  if 
the  surface  upon  which  the  curved  slieet  lies  is  concave,  the  muscle  will  tend  l)y 
its  contraction  to  lift  up  the  soft  parts  u})on  its  deep  or  convex  surface.  As  an 
instance  of  this  we  have  the  influence  of  the  platysma  myoides  upon  the  fascia  and 
other  stru(!tures  which  overlie  the  great  vascular  diannels  of  the  neck  and  the 
apices  of  the  lungs. 

In  estimating  the  effect  of  muscles  acting  upon  the  levers  formed  by  the  bones, 
each  of  which  moves  upon  a  joint  as  its  fulcrum,  three  points  have  to  be  taken  into 
consideration: — (1)  the  order  of  lever;  (2)  the  distance  from  the  fulcrum,  of  the 
points  of  application  of  the  force  at  the  insertion  of  the  muscle,  and  of  the  resist- 
ance to  be  overcome;  and  (3)  the  direction  in  which  the  force  is  applied.  It  will 
be  found  that  whereas  in  most  levers  employed  in  mechanics  the  object  aimed  at 
is  what  is  called  mechanical  advantage,  i.e.  by  the  application  of  a  small  force  to 
overcome  a  greater  resistance;  in  the  human  body  the  object  is,  on  the  contrary, 
by  the  exertion  of  a  great  force  through  a  small  space  to  overcome  a  small  resist- 
ance, but  at  the  same  time  to  cause  motion  through  a  much  greater  space,  and  with 
a  much  greater  speed.  In  the  three  orders  of  levers,  the  fulcrum  is  placed  either 
between  the  power  and  the  resistance  (first  order);  or  at  one  end,  with  the  power 
at  the  other,  and  the  resistance  to  be  overcome  between  (second  order);  or  at  one 
end  with  the  power  in  the  middle,  and  the  resistance  to  be  overcome  at  the  other 
end  (third  order).  The  power  required  to  overcome  the  resistance  varies  inversely 
with  the  distance  of  its  point  of  application  from  the  fulcrum.  Where  this  distance, 
or  the  arm  of  the  lever  as  it  is  called,  is  short  compared  with  the  arm  at  w^hich  the 
resistance  acts,  then  the  power  has  to  be  greater  than  the  resistance,  and  vice  versa. 
In  the  first  order  of  levers,  if  the  power  and  resistance  act  parallel  to  one  another, 
there  may  or  may  not  be  a  gain  of  mechanical  advantage,  according  as  the  arm  at 
which  the  powder  acts  is  greater  or  less  than  the  arm  at  which  the  resistance  acts. 
In  the  second  order  of  levers  there  must  necessarily  be  mechanical  advantage;  and 
in  the  third  order  the  power  must  be  greater  than  the  resistance,  as  it  has  to  act 
upon  a  shorter  arm,  so  there  will  be  what  may  be  termed  mechanical  disadvantage. 

In  the  human  body  there  is  hardly  a  single  muscle  which  forms  a  good  example 
of  a  lever  of  the  second  order,  for  the  simple  reason  that  mechanical  advantage 
is  of  so  much  less  importance  than  a  wide  range  of  movement  with  its  attendant 
rapidity.  The  best  example  that  can  be  given  is  that  of  some  of  the  muscles  Avhich 
depress  the  mandible,  e.g.  the  anterior  belly  of  the  digastric,  which  is  inserted  into 
the  extremity  of  the  lever  formed  by  that  bone,  while  the  resistance  to  be  overcome 
— viz.  the  tonic  contraction  of  the  masseter,  temporal,  and  internal  pterygoid — is 
exerted  at  a  point  much  nearer  to  the  fulcrum  upon  which  the  mandible  turns. 

The  muscles  which  are  inserted  upon  the  tendo  Achillis  are  often  given  as  an 
example  of  this  order  of  lever,  when  by  their  contraction  they  raise  the  heel  and 
lift  up  the  body,  the  weight  of  which  acts  upon  the  lever  of  the  foot  through  the 
ankle-joint.  This  would  be  a  good  example  if  another  person  were  to  lay  hold  of 
the  tendo  Achillis,  and  by  drawing  upon  it  to  raise  the  individual  from  the  ground. 
But  the  fact  that  the  other  end  of  the  muscle  springs  from  a  j^art  of  the  mass  to 
be  raised  alters  the  conditions,  and,  as  a  matter  of  fact,  the  muscle,  instead  of 
obtaining  any  mechanical  advantage  in  its  action,  has  to  contract  with  a  force  four 
or  five  times  as  great  as  the  weight  to  be  raised. 

It  will  be  found  that  most  of  the  muscles  belong  either  to  the  third  order,  in 
which  there  is  necessarily  mechanical  disadvantage,  or  to  the  first  order;  and  in 
this  case,  the  arm  at  which  the  power  acts  is  usually  the  shorter,  so  that  the  power 
has  to  be  greater  than  the  resistance.  In  the  movements  of  the  forearm  about  the 
elbow  as  a  fulcrum,  the  triceps  acting  with  the  very  short  arm  afforded  l)y  the  pro- 
jection of  the  olecranon  and  overcomiug  a  resistance  experienced  by  the  hand  at 
the  other  end  of  the  radius  and  ulna,  will  be  a  lever  of  the  first  order.  The 
brachio-radialis  (supinator  longus)  when  used  to  flex  the  forearm  acts  at  the  lower 
end  of  the  radius,  so  as  to  overcome  the  weight  of  the  forearm  and  hand,  which 
will  act  through  a  centre  of  gravity,  which  is  about  the  middle  of  the  radius,  and 
therefore  much  nearer  to  the  fulcrum  at  the  elbow.  It  therefore  forms  a  lever  of 
the  second  order.     If   its  angle  of  insertion  were  not  so  very  small,  the  muscle 


286  THE  MUSCLES 

would  thus  obtain  a  consiflorablo  mechanical  advantage.  This  extreme  obliquity, 
however,  actually  places  the  muscle  in  a  condition  of  mechanical  disadvantage. 
Lastly,  the  biceps  and  brachialis  anticus  are  Ijoth  of  them  good  exam])les  of  the 
third  order  of  lever,  when  they  act  by  their  insertion  close  to  the  fulcrum  of 
the  elbow  to  flex  the  forearm,  the  centre  of  gravity  of  which  is  much  farther  from 
the  joint. 

The  direction  of  the  tendon  at  its  point  of  insertion  is  of  great  importance  in 
estimating  the  effect  of  the  contraction  of  any  muscle.  It  is  rarely  perjiendicular 
to  its  lever.  There  is,  therefore,  in  nearly  every  case,  a  considerable  loss  of 
meclianical  advantage;  but  it  should  be  remembered  that  this  is  more  than 
counterbalanced  by  important  gains.  In  the  first  place,  the  range  and  rapidity 
of  movement  are  greatly  increased  for  a  given  contraction  of  the  muscle;  and  in 
the  second  place  a  power  is  also  produced  by  which  the  articular  ends  of  the  bones 
connected  by  the  muscle  are  pressed  together,  so  that  the  tendency  to  dislocation 
of  the  joint  is  diminished.  A  third  advantage  is  the  compactness  given  to  the 
limb  bv  the  tendons  being  placed  in  close  apposition  to  the  bones,  an  object  which 
could  not  be  attained  unless  their  insertions  were  very  oblique. 

Take  the  case  of  the  brachio-radialis  flexing  the  forearm.  In  the  adjoining 
diagram  let  E  be  the  elbow,  B  E  the  humerus.  E  R  the  radius,  and  B  R  the  line  of 
the  ])racliio-radialis.  To  estimate  how  much  of  the  contracting  force  of  the  muscle 
is  actually  expended  in  flexing  the  forearm,  all  that  is  necessary  is  to  take  any 
point  K  in  B  R,  to  draw  K  A  perpendicular  to  E  R,  and  form  a  rectangle  R  A  K  C, 
on  R  A.  If  the  force  of  the  muscle  acting  along  R  B  be  represented  by  the  line 
R  K,  then  R  C  w'ill  represent  that  portion  of  the  force  which  tends  to  flex  the 

Fig.  260. 


elbow,  and  R  A  the  portion  which  is  devoted  to  compression  of  the  head  of  the 
radius  against  the  capitellum  of  the  humerus,  so  as  to  strengthen  the  elbow-joint. 
Again,  let  E  R'  be  the  new  position  of  the  forearm  after  the  brachio-radialis  has 
contracted.  The  arc  of  the  circle  through  w^hich  it  has  moved  will  be  indicated  by 
R  R'.  a  small  arc  drawn  with  radius  R  E,  and  centre  E.  Now  join  R'  to  B,  and 
draw  another  small  arc  R'  D  with  centre  B  and  radius  R'  B.  R  D  l^eing  the  difi"er- 
ence  between  B  R  and  B  R',  Avill  indicate  the  amount  by  which  the  length  of  the 
muscle  has  diminished  during  its  contraction,  and  R  R'  Avill  represent  the  space 
through  whi<;h  the  lower  end  of  the  radius  has  moved.  A  comparison  of  the 
lengths  of  R  D  and  R  R'  will  show  how  great  has  been  the  gain  in  range  of  move- 
ment by  the  (jblique  insertion  of  B  R.  If  the  muscle  had  been  inserted  at  right 
angles  to  E  R,  it  would,  in  order  to  produce  the  same  effect,  have  had  to  contract 
through  a  space  equal  in  length  to  R  R'.  With  its  oblique  insertion  a  contrac- 
tion equal  in  length  to  R  D  hiis  sufficed.  The  gain  in  range  (and  therefore  in 
rapidity  of  movement,  for  by  contracting  through  the  short  distance  it  causes  a 
simultaneous  motion  through  the  longer  space)  may  be  roughly  represented  by 
the  fraction  j^  j^ .  In  muscles  in  which  the  insertion  of  the  tendon  is  at  a  very 
small  angle,  the  loss  of  power  is  proportionately  greater,  and  the  gain  in  speed  and 
range  enormous.  As  instances  of  this  may  be  mentioned  the  insertions  of  the 
tendons  of  the  i)halanges,  which  ])roduce  the  comparatively  feeble,  but  exceedingly 
niml)le,  movements  of  tlie  fingers  with  a  very  small  contraction  of  the  forearm 
muscles. 

In  speaking  of  the  ilirection  of  the  muscles,  it  should  clearly  be  understood  that 


THEIR  ACTION  AS  LEVERS 


287 


this  refers  to  the  angle  of  the  attachment  of  the  tendon  to  the  lever  which  has  to 
be  moved,  and  not  to  the  general  direction,  which  is  often  changed  by  the  passage 
of  the  tendon  or  muscle  over  i)rojections  of  bone  or  under  arches  of  ligament  before 
it  reaches  its  insertion. 

The  advantage  of  an  obliciue  insertion  may  also  be  illustrated  by  the  action  of 
muscular  fibres,  which  cross  one  another  like  the  two  i)arts  of  the  letter  X  in  their 
passage  between  two  parallel  liones;  e.g.  in  the  external  and  internal  intercostal 
muscles  connecting  adjacent  ribs,  or  in  the  external  and  internal  oblique  muscles  of 
the  abdomen  in  their  passage  from  the  crest  of  the  ilium  to  the  last  rib.  If  the 
muscles  connecting  the  parallel  bones  ran  at  right  angles  to  them,  they  could  only 
by  their  contraction  dindnish  the  intervening  space  by  one-half;  whereas,  running 
obliquely,  they  produce  l)y  their  contraction  a  much  greater  approximation  of  the 
bones.  For  let  A  B  and  C  D  represent  two  parallel  bones,  and  E  F  a  muscular  fibre 
running  perpendicularly  from  one  to  the  other.  If  its  full  contraction  reduced  the 
length  of  the  fibre  by  one-half,  it  would  merely  draw  the  point  E  to  E'.  But  suppose 
that  two  muscular  fibres  C  E  and  D  E  converge  at  right  angles  to  each  other  upon 
the  point  E;  the  amount  that  they  will  have  to  contract  to  draw  E  to  E'  may  be 
readily  found  by  describing  the  arc  of  a  circle  E'  K  or  E'  L  about  C  or  D  as  a  centre, 
and  with  C  E'  or  D  E'  as  a  radius.     E  K  and  E  L  will  represent  the  contraction 

Fig.  261. 


required;  and  it  is  evident  that  if  these  oblique  fibres  contract  more  strongly,  they 
can  bring  the  bone  A  B  into  close  apposition  with  C  D. 

When  muscles  pass  over  more  than  one  joint,  their  action  is  somewhat  more 
complicated.  Usually  other  muscles  are  at  the  same  time  called  into  play,  so 
as  to  fix  some  of  the  joints,  and  enable  the  muscle  to  act  solely  upon  others. 
For  example,  when  the  muscles  arising  above  the  wrist  are  used  to  extend  the 
phalanges  of  the  fingers,  it  will  be  found  that  some  of  the  flexors  of  the  carpus 
contract  so  as  to  fix  the  wrist.  Similarly,  if  the  fingers  are  flexed  in  grasping  an 
object,  it  is  easy  to  feel  the  tendons  of  the  carpal  extensors  starting  up  into  firm 
contraction. 

Occasionally  the  passage  of  a  muscle  over  two  joints  is  used  to  ol^tain  very  swift 
and  vigorous  action.  For  example,  if  the  long  head  of  the  triceps,  which  extends  from 
the  axillary  border  of  the  shoulder-lilade  to  the  olecranon  process,  Mere  replaced 
by  an  inextensible  ligament,  wliicli  should  be  tight  with  the  arm  down  and  the 
elbow  flexed,  the  elevation  of  the  humerus  by  the  deltoid  muscle  would  necessitate 
a  corresponding  extension  of  the  elbow.  Now  put  in  the  place  of  the  inextensible 
ligament  an  actively  contracting  muscle,  and  it  is  clear  that  the  combination  of  this 
elevation  of  the  arm  by  the  deltoid  with  contraction  of  the  triceps  will  produce  a 
much  more  rapid  extension  of  the  elbow,  such  as  is  seen  in  throwing  a  spear  or  a 
stone. 


288  THE  MUSCLES 


MUSCLES  OF  THE  UPPER  EXTREMITY 

The  first  group  consists  of  those  which,  arising  from  various  parts  of  the  head, 
neck,  and  trunk,  are  inserted  into  the  bones  of  the  shoulder  girdle,  viz.  the  clavicle 
and  scapula,  or  into  the  humerus.  Of  this  group  there  are  two  divisions:  the  one 
comprising  the  nuiscles  which  take  their  origin  from  the  back  of  the  head,  neck, 
and  trunk;  the  other,  those  which  arise  from  the  front  and  sides  of  the  thorax. 


POSTERIOR  DIVISION  OF  THE  GROUP  OF  MUSCLES  PASSING 
FROM  THE  TRUNK  TO  THE  UPPER  EXTREMITY 

This  division  consists  of  two  layers,  which  lie  superficial  to  the  proper  back 
muscles.  Overlying  these  layers  is,  first,  the  superficial  fascia,  which  is  strong, 
well  provided  with  fat,  and  continuous  with  that  of  the  head,  neck,  axilla, 
and  other  adjacent  regions;  and,  secondly,  the  deep  fascia,  which  is  thin  and 
forms  the  sheath  of  the  trapezius  and  latissimus  dorsi  muscles.  Above  and  in 
front,  the  deep  fascia  is  continuous  with  the  deep  cervical  fascia;  lower  down,  with 
the  axillary  fascia,  and  that  covering  the  thoracic  and  abdominal  parietes.  Inter- 
nally it  is  attached  to  the  spines  of  the  vertebrae,  and  below  it  blends  with  the 
lumbar  aponeurosis. 

First  Layer 
Consisting  of  one  muscle — the  trapezius. 


THE  TRAPEZIUS 

Tlie  trapezius  (or  cucullaris,  as  it  has  been  called  from  its  resemblance  to  a 
cowl  =  cKCullus)  is  named  from  Tpd7:e!^a,  a  table,  on  account  of  the  four-sided 
figure  formed  by  the  muscles  of  the  two  sides.  It  is  a  fan-shaped  sheet  forming  an 
obtuse-angled  triangle,  the  long  side  of  which  corresponds  with  the  spine. 

Origin. — (1)  The  inner  third  of  the  superior  nuchal  line  of  the  occipital  bone, 
and  the  external  occipital  protuberance;  (2)  the  posterior  border  of  the  ligamentum 
nuch^e;  (o)  the  spines  of  the  seventh  cervical  and  all  the  thoracic  vertebrie,  together 
with  the  supraspinous  ligament. 

Insertion. — CI)  The  posterior  border  of  the  outer  third  of  the  clavicle  and  the 
adjacent  part  of  its  upper  surface;  (2)  the  inner  edge  of  the  upper  surface  of  the 
acromion  process;  (3)  the  upper  border  of  the  spine  of  the  scapula,  and  a  small 
tubercle  at  its  inner  extremity. 

Structure. — The  origin  of  the  muscle  is  by  short  tendinous  intermingled  with 
fleshy  iibres,  except  at  two  places,  w'here  the  tendinous  fibres  form  a  continuous 
sheet.  The  first  of  these  is  from  the  middle  of  the  ligamentum  nucha?  to  the  second 
thoracic  spine;  here  a  conspicuous  oval  aponeurosis  is  formed  by  the  tendons  of  the 
two  sides.  The  second  is  at  the  lower  acute  angle  of  the  muscle  where  it  arises 
from  the  lowest  thoracic  vertebra.  The  muscular  fibres  converge  from  the  extensive 
origin,  and  just  before  their  insertion,  the  sheet  of  the  muscle  is  folded  upon  itself, 
to  adapt  it  to  the  V-shaped  process  of  the  shoulder  girdle,  into  which  it  is  inserted 
by  fleshy  fibres,  except  at  the  inner  extremity  of  the  spine  of  the  scapula,  where  a 
tendinous  sheet  plays  over  the  triangular  base  of  that  process,  before  it  is  inserted 
into  the  tubercle  at  the  inner  end  of  the  spine.  Sometimes  a  bursa  intervenes 
between  this  sheet  and  the  triangular  surface  of  the  scapular  si)ine. 

Nerve-supply. — From  the  spinal  accessory;  and  from  the  deep  cervical  plexus 
by  branches  of  tlie  third  and  fourth  cervical  nerves,  which,  after  communicating 


THE    TRAPEZIUS 


289 


Fig.  262. — First  Laykr  of  :Mlscli:s  of  the  Back. 


Triceps 


Rhomboideus  major 
Peetoralia  major 


Gluteus  medius 


Gluteus  mazimus 


19 


290  THE  MUSCLES 

with  the  spinal  accessory,  enter  witli  it  the  deep  surface  of  the  muscle  a  short 
distance  above  the  clavicle. 

Action. — Its  upper  fibres  draw  upwards  the  outer  end  of  the  clavicle  and  the 
point  of  the  shoulder;  and  acting  from  below,  they  extend  the  head,  flex  the  neck 
towards  the  same  side,  and  turn  the  face  to  the  opposite  side.  Its  middle  fibres  draw 
the  scapula  inwards  towards  the  spine;  at  the  same  time  they  produce  a  rotation 
of  the  scapula  on  the  thorax,  by  which  the  point  of  the  shoulder  is  raised.  The 
lower  filjres  draw  the  scapula  downwards  and  inwards,  and  at  the  same  time  rotate 
it  so  as  to  raise  the  point  of  the  shoulder. 

Acting  as  a  whole,  the  muscle  draws  the  scapula  towards  the  middle  line  of  the 
back,  and  elevates  the  shoulder  by  the  rotation  it  impresses  upon  the  shoulder 
blade.  By  drawing  the  scapula  backwards,  it  gives  some  help  to  the  pectoralis 
minor  ancl  other  muscles  which  elevate  the  ribs  in  forced  inspiration.  When  it 
takes  its  fixed  point  from  the  shoulder  blade  and  clavicle,  as  when  the  hand  grasi)S 
firmly  some  immovable  ol)ject,  the  muscle  will  draw  the  spines  of  the  verteljrae 
towards  the  scapula. 

The  presence  of  the  oval  aponeurotic  patch  may  be  explained  by  the  fact  that 
the  range  of  movement  of  the  scapula  in  a  horizontal  direction  l^ackwards  and 
inwards  is  more  limited  than  when  the  inward  movement  is  coml)ined  with  an 
upward  or  downward  direction.  This  limitation  is  due  to  the  ligamentous  attach- 
ments of  the  clavicle  and  shoulder  Ijlade. 

Relations. — Superficially,  the  integuments  and  subcutaneous  nerves;  deeply, 
the  complexus,  splenii,  serratus  posticus  superior,  rhomboidei,  the  vertebral  apo- 
neurosis covering  the  continuations  upwards  of  the  erector  spinas,  the  external 
intercostals,  latissimus  dorsi,  levator  anguli  scapulae,  omo-hyoid,  scalenus  medius 
and  posticus,  the  supraspinatus,  and  a  small  portion  of  the  infrasj^inatus. 

Variations, — Occasionally  the  upper  or  the  lower  part  of  its  origin  may  ftiil.  The  clavicular 
part  of  its  insertion  sometimes  extends  far  forwards  upon  the  clavicle.  Frequently  fibres  pass 
from  its  anterior  border  to  the  inner  end  of  the  clavicle  either  in  front  of  or  behind  the  sterno- 
mastoid,  forming  an  arch  under  which  run  some  of  the  superficial  cervical  nerves.  This  arch 
may  even  extend  to  the  sternum.  A  similar  transverse  band  is  occasionally  found  in  the  upper 
part  of  the  posterior  triangle,  the  transversus  michce.  Sometimes  a  longitudinal  band  of  fibres 
covers  the  spinal  origin  of  the  trapezius. 


Second  Layer 

Consists  of  four  muscles — the  levator  anguli  scapulae,  rhomboideus  minor  and 
major;  and  the  latissimus  dorsi. 


1.  LEVATOR  ANGULI  SCAPULA 

The  levator  anguli  scapulae  (figs.  263  and  266),  named  from  its  action  in 
raising  the  posterior  superior  angle  of  the  scapula,  is  a  ribbon-shaped  muscle. 

Origin. — By  four  short  tendons  from  the  posterior  tubercles  of  the  transverse 
processes  of  the  four  upper  cervical  vertebra?. 

Insertion. — The  vertebral  border  of  the  scapula  opposite  the  supraspinous 
fossa. 

Structure. — The  tendons  of  origin,  which  are  closely  connected  with  the  inser- 
tion of  the  splenius  colli,  after  a  short  course  are  succeeded  by  muscular  fasciculi, 
and  these  unite  to  form  a  thick  band  of  parallel  fibres  which  remain  fleshy  to  their 
insertion.  The  plane  of  the  muscle  changes  as  it  descends.  Aliove,  while  lying  in 
the  posterior  triangle  of  the  neck,  its  surfaces  look  outwards  and  inwards;  below, 
they  are  directed  backwards  and  forwards. 

Nerve-supply. — From  the  cervical  plexus  by  branches  from  the  third  and 
fourth  cervical  nerve  which  enter  the  front  of  the  outer  surface  near  the  origin  of 
the  muscle. 

Action. — It  raises  the  posterior  superior  angle  of  the  scapula;  but,  by  causing 


RHOMBOID  EI 


291 


rotation  of   that  bone,   it  depresses  the   point  of   the  shoulder.     Taking  its  fixed 
l)oint  from  below,  it  is  an  extensor  and  lateral  tlexor  of  the  neck. 

Fig.  263.— The  Levatok  Axguli  Scapulj^  and  Khomboidei. 


Supraspinatus 


Teres  minor 


Infraspinatus 


Teres  major 


SerratuB  magnus 


Splenius  capitis 


Levator  anguli  scapulae 


Serratus  posticus 
superior 


—      Rhomboideus  minor 


Splenius  colli 
Khomboideus  major 


Serratus  posticus 
inferior 


Obliquus  internuB 


sier 


Relations.-Superficiallv,  the  deep  cervical  fascia,  the  platysma  myoides,  the 
no-niastoid,  the  trapezius,  the  scalenus  niedius  the  niterna  jugular  vein  he 
..1  ..n...J^  ^Prx'P   «nd  some  of  the  descendnig  branches  of  the  cervical  plexus, 


spinal  accessory  nerve,  and  some  of  the  descending 


292  THE  MUSCLES 

deeply,  the  spleniiis  colli,  the  cervicalis  ascendens,  the  serratus  posticus  superior, 
and  the  posterior  scapular  vessels. 

Variations. — The  number  of  corviciil  vertebra)  from  which  the  muscle  arises  varies,  and  it 
may  even  arise  from  the  mastoid  process  or  occipital  bone.  It  may  send  slips  to  the  serratus 
ma.trnus,  the  serratus  posticus  superior,  and  other  adjacent  muscles  ;  occasionally  also  to  the  clavicle 
and  first  two  ribs. 

2  AND  3.   RHOMBOIDEI 

The  rhomboidei — named  from  their  shape,  which  is  rhom])oidal,  or  like  a 
parallelogram — are  sometimes  looked  upon  as  a  single  muscle,  but  may  be  usually 
separated  into  the  following: — 

The  rhomboideus  minor,  the  lesser  and  upper  of  the  two,  is  a  four-sided  sheet, 
forming  an  elongated  parallelogram. 

Origin. — The  lower  part  of  the  ligamentum  nuch«,  the  spines  of  the  seventh 
cervical  and  first  thoracic  vertebrae,  and  the  supraspinous  ligament  between  them. 

Insertion. — The  vertebral  border  of  the  scapula  opposite  its  spine. 

Structure. — Its  origin  and  insertion  are  by  short  tendinous  fibres,  between 
which  its  fleshy  fibres  run  parallel  to  one  another,  downwards  and  outwards. 

Nerve-supply. — From  the  brachial  plexus  by  a  branch  of  the  fifth  cervical 
nerve,  which  enters  its  deep  aspect  near  the  upper  border  a  short  distance  above  its 
insertion. 

For  action  and  relations,  see  the  account  of  the  following  muscle. 

The  rhomboideus  major — the  lower  and  larger  of  the  two  muscles — is  a  broad 
rhoml)()idal  sheet. 

Origin. — The  spines  of  the  four  or  five  upper  thoracic  vertebrae,  and  the  supra- 
spinous ligament  between  them. 

Insertion. — The  vertebral  border  of  the  scapula  opposite  the  infraspinous  fossa. 

Structure. — At  the  origin,  it  consists  of  short  tendinous  fibres,  succeeded  by 
parallel  fleshy  bundles,  which  pass  downwards  and  outwards  to  a  narrow  tendinous 
expansion  which  is  feebly  attached  to  the  scapula  over  the  upper  three-fourths  of 
its  insertion,  but  with  thick  and  strong  fibres  near  the  inferior  angle  of  that  bone. 

Nerve-supply. — The  same  as  the  preceding,  and  entering  the  upper  part  of 
the  deep  surface  near  its  insertion. 

Action. — The  rhomboidei  draw  the  scapula  inwards  and  backwards  towards 
the  middle  line,  and  at  the  same  time  upwards.  They  also  rotate  the  scapula  so  as 
to  depress  the  point  of  the  shoulder.  In  this  way  they,  together  with  the  levator 
angidi  scapuhe,  will  help  in  drawing  down  the  arm,  after  it  has  been  elevated 
through  the  rotation  of  the  scapula  by  the  trapezius  and  serratus  magnus. 

Acting  from  the  scapula,  the  rhomboidei  will  help  the  trajjczius  in  drawing  the 
middle  line  of  the  back  towards  that  bone. 

Relations  of  the  two  rhomboidei. — Superficially,  the  trapezius  and,  at  the 
lower  part  of  the  rhomljoideus  major,  the  deep  fascia,  and  latissimus  dorsi;  deeply, 
the  serratus  posticus  superior,  splenius  colli,  the  external  intercostals,  the  posterior 
scapular  vessels,  the  angles  of  the  upper  ribs,  and  the  vertebral  ai)oneurosis  cover- 
ing the  upper  continuations  of  the  erector  spinse. 

Variations. — The  rhomboideus  minor  is  frequently  absent,  and  occasionally  there  is  no  rhom- 
boideus major.  The  fit>res  of  the  latter  muscle  may  be  inserted  almost  entirely  into  the  lower 
angle  of  the  scapula.  Occasionally  its  lower  fibres  join  those  of  the  latissimus  dorsi,  and  they 
have  also  heeu  found  continuous  with  a  part  of  the  teres  major.  An  accessory  band  may  join  the 
rhomboidei  from  the  occipital  bone  (the  occiiiito-scapularis). 


4.  LATISSIMUS  DORSI 

The  latissimus  dorsi  Cfigs.  202  and  209) — named  from  its  being  tlic  broadest  of 
the  back  nmsclcs — is  a  t'an-shaj^ed  sheet  forming  a  right-angled  triangle,  the  right 
angl(^  being  contained  between  its  upper  and  vertebral  borders. 

Origin. — (1)  The  five  or  six  lower  thoracic  spines,  and  the  supraspinous  liga- 


MUSCLES  PASSLXG    TO    THE    UPPER   EXTREMITY  293 

ment;  (2)  the  lower  part  of  the  vertebral  aponeurosis  (see  account  of  Lumbar 
Fascia,  page  408),  by  which  it  is  attached  to  the  spines  of  all  the  lumbar  and 
sacral  vertebra?;  (8)  the  posterior  third  of  the  outer  lip  of  the  crest  of  the  ilium; 
(4)  horizontal  lines  crossing  the  outer  surface  of  the  last  three  or  four  ribs  external 
to  their  angles  (these  lines  by  their  lower  borders  give  origin  to  processes  of  the 
external  ol)li4ue  muscle,  which  thus  interdigitates  with  the  latissimus  dorsi);  and 
sometimes  (5)  the  dorsal  as})ect  of  the  inferior  angle  of  the  scajjula. 

Insertion. — The  bottom  of  the  bicipital  groove  of  the  humerus,  as  far  upwards 
as  the  lesser  tuberosity. 

Structure. — Its  first  and  third  parts  arise  by  short  tendinous  fibres.  The  origin 
of  the  second  part  from  the  vertebral  aponeurosis  is  by  fleshy  fibres  in  a  line  which 
descends  obliquely  downwards  and  outwards  from  the  last  thoracic  spine  to  the 
back  of  the  crest  of  the  ilium.  Its  origin  from  the  ribs  and  scapula  is  muscular. 
The  fleshy  fibres  are  of  nearly  equal  length,  and  they  converge  upon  the  tendon 
in  such  a  way  that  those  which  arise  from  the  ribs  and  crista  ilii  are  inserted 
highest  into  the  humerus,  Avhile  those  which  spring  from  tlie  thoracic  spine  are 
attached  to  the  lower  part  of  the  bicipital  groove.  The  broad  sheet  wraps  round  the 
side  of  the  thorax,  and  is  also  folded  upon  itself,  so  that  the  anterior  surface  at  the 
origin  becomes  the  posterior  at  the  insertion.  A  groove  is  thus  formed,  in  which 
lie  the  outer  border  of  the  scapula  and  the  teres  major.  The  tendon  of  the  teres 
major  is  usually  attached  at  the  borders  to  that  of  the  latissimus  dorsi  by  strong 
connective  tissue;  but  a  bursa  intervenes  between  them  near  their  insertion. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  by  means  of 
the  long  subscapular  nerve.  This  is  derived  from  the  sixth  and  seventh  cervical 
nerves,  and  enters  the  muscle  upon  its  deep  surface  in  the  lower  part  of  the  axilla. 

Action. — It  draws  the  humerus  backwards,  downwards,  and  inwards;  at  the 
same  time  rotating  it  inwards.  The  movement  of  the  arm  in  swimming  is  a  good 
example  of  its  action.  When  the  arm  is  placed  close  to  the  side,  it  will  draw  the 
shoulder  backwards  and  downwards. 

Acting  from  the  humerus  as  a  fixed  point,  it  is  very  important  in  climbing,  as 
it  draws  the  pelvis  and  lower  part  of  the  trunk  upwards  and  forwards  towards  the 
arms. 

By  its  costal  origin  it  will  assist  in  forced  inspiration  when  the  arm  is  fixed. 

Relations. — Superficially,  the  trapezius,  fasciie,  and  integument  l)ehind,  and  the 
pectoralis  major,  axillary  vessels,  and  branches  of  the  brachial  plexus  in  front; 
deeply,  the  rhomboideus  major,  the  vertebral  aponeurosis  covering  the  upward 
continuations  of  the  erector  spinoe  muscle,  the  serratus  posticus  inferior,  external 
intercostals,  external  obliciue,  infraspinatus,  serratus  magnus,  and  teres  major 
muscles.  • 

Variations. — It  varies  in  the  height  of  its  origin  from  the  spinal  column,  and  also  in  the 
number  of  ribs  from  which  it  arises.  From  its  axillaiy  border  shps  may  cross  the  axilla  to  the 
tendon  of  the  pectoralis  major,  or  may  cross  the  great  vessels  and  nerves  to  the  coracoid  process 
or  the  deep  fascia  at  the  upper  part  of  the  arm.  _  A  slip_  of  fascia  or  muscle  may  be  continued 
down  from  its  tendon  of  insertion  to  the  olecranon  in  association  with  the  triceps. 


ANTERIOR   DIVISION   OF   THE   GROUP   OF   MUSCLES   PASSING 
FROM   THE   TRUNK   TO   THE   UPPER   EXTREMITY 

These  muscles  are  arranged  in  three  layers,  of  wliicli  the  first  two  are  formed 
by  muscles  which  arise  from  the  front  of  the  thorax:  viz.,  the  pectoralis  major  in 
the  first  layer,  and  the  subclavius  and  ])ectoralis  minor  in  the  second;  the  last  l)y  a 
single  nuiscle,  tlie  serratus  magnus,  which  takes  origin  from  the  side  of  the  thorax. 

Tbe  superficial  fascia,  which  covers  all  these  layers,  is  but  moderately  supplied 
with  fat,  and  is  continuous  Avith  that  of  all  the  adjacent  regions.  It  lies  both  over 
and  beneath  the  mammarv  gland,  and  sends  fibrous  septa  between  its  lobules. 

In  addition  to  the  superficial  fascia,  there  are  three  other  important  fasciae  in 
this  region. 


294  THE  MUSCLES 

1.  The  pectoral  fascia,  a  thin  membrane  which  forms  the  sheath  of  the  pec- 
toralis  major,  and  is  attached  to  the  clavicle  al)Ove;  while  below  it  passes  over  the 
free  edge  of  tlie  great  pectoral  muscle,  and  there  unites  with  the  axillary  fascia. 

2.  The  clavi-pectoral  fascia  arises  in  two  sheets  from  the  anterior  and  pos- 
terior borders  of  the  under  surface  of  the  clavicle.  These  sheets  unite  after  enclos- 
ing the  pubclavius  muscle,  and  form  a  single  membrane  (the  costo-coracoid) ,  which, 
after  bridging  the  space  between  the  subclavius  and  pectoralis  minor,  divides  again 
to  form  the  sheath  of  the  pectoralis  minor.  At  the  lower  border  of  this  muscle,  the 
clavi-pectoral  joins  the  axillary  fascia.  The  costo-coracoid  membrane,  which  is 
the  middle  portion  of  the  clavi-pectoral  fascia,  is  of  a  quadrilateral  shape,  and  is 
attached  above  and  below  to  the  sheaths  of  the  subclavius  and  the  pectoralis  minor 
muscles;  externally,  where  it  blends  with  the  sheath  of  the  axillary  vessels,  it  is 
very  strong;  internally,  where  it  joins  the  fascia  covering  the  front  part  of  the  first 
and  second  intercostal  spaces,  it  is  thin  and  weak. 

3.  The  axillary  fascia  is  a  strong  membrane  which  stretches  across  the  triangu- 
lar floor  of  the  axilla.  In  front,  it  joins  the  pectoral  and.  clavi-pectoral  fasciae; 
behind,  it  joins  the  sheath  of  the  latissimus  dorsi;  above,  it  is  continuous  with  the 
deep  fascia  of  the  upper  arm,  and  below  with  that  of  the  thorax. 

The  concavity  of  its  surface,  which  is  directed  downwards  and  outwards,  is 
maintained  to  a  great  extent  by  the  attachment  of  the  clavi-pectoral  fascia  above 
mentioned. 

First  Layer 

PECTORALIS  MAJOR 

The  pectoralis  major — named  from  its  being  the  larger  of  the  two  muscles 
which  arise  from  the  front  of  the  chest  (pgrtw.s  =  breast) — is  a  thick,  triangular,  fan- 
shaped  sheet;  or,  more  accurately,  it  may  be  likened  to  the  segment  of  a  circle  on 
account  of  the  curved  origin,  from  which  all  the  fibres  converge  to  the  upper  part 
of  the  humerus  as  a  centre. 

Origin. — (1)  The  anterior  surface  of  the  inner  half  of  the  clavicle  and  the 
adjacent  part  of  the  sterno-clavicular  joint;  (2)  the  side  of  the  front  of  the 
sternum,  from  the  sterno-clavicular  joint  to  the  lower  extremity  of  the  gladiolus; 
(3)  the  front  of  the  cartilages  of  the  second  to  the  sixth  ribs;  (4)  a  small  part  of 
the  outer  surface  of  the  sixth  rib  close  to  its  anterior  extremity;  (5)  the  upper  part 
of  the  aponeurosis  of  the  external  oblique  muscle  which  forms  the  front  of  the 
sheath  of  the  rectus  abdominis. 

•  Insertion. — (1)  The  external  bicipital  ridge  of  the  humerus  from  the  greater 
tuljerosity  down  to  the  impression  for  the  deltoid;  (2)  adjacent  fibrous  structures, 
esiiecially  the  tendon  of  insertion  of  the  deltoid  muscle. 

Structure. — The  clavicular  portion  is  distinct  from  the  rest,  and  might  be 
described  as  a  separate  muscle.  It  forms  a  thick  band  of  parallel  fibres,  which, 
arising  tendinous  from  the  clavicle,  become  almost  immediately  fleshy,  and  are 
inserted  into  the  humerus  by  short  tendinous  fibres  in  front  of  the  rest  of  the 
tendon  of  insertion. 

The  rest  of  the  muscle  (the  sterno-costal  portion  as  it  is  usually  named)  con- 
sists of  fleshy  fil)res  which,  arising  directly  from  the  four  other  ])arts  of  the  origin 
enumerated,  converge  and  cross  one  another  to  be  inserted  into  the  humerus  l)ehind 
the  clavicular  portion  V)y  means  of  a  peculiar  tendon. 

In  a  vertical  section  (fig.  271)  near  the  humerus  this  tendon  is  seen  to  be  folded 
upon  itself  into  a  com]  iressed  horseshoe-shape.  The  convexity  of  the  folded  tendon 
is  directed  downwards,  and  the  anterior  segment  of  the  horseshoe  is  shorter  than 
the  posterior. 

The  anterior  segment  receives  the  muscular  fibres  which  proceed  from  that 
part  of  the  origin  of  the  sterno-costal  portion  which  lies  above  the  third  costal 
cartilage,  and  Avith  the  front  of  this  segment,  the  insertion  of  the  clavicular  portion 
is  closely  lilended.  The  posterior  segment  receives  the  fibres  from  the  lower  part 
of  the  sterno-costal  portion,  the  lowest  fibres  (viz.  those  from  the  external  oblique 
aponeurosis)  being  inserted  highest,  and  the  highest  (viz.  those  irom  the  middle  of 


PECTORA  L  IS  MA  J  OR 


295 


the  sternum)  lieing  attaelied  to  the  lower  i)art  of  the  horseshoe,  where  they  become 
continuous  with  those  forming  the  anterior  segment  of  the  tendon. 

In  consequence  of  this  arrangement  the  lower  til)res  of  the  muscle  disappear 
from  view  soon  after  tlieir  origin,  and  are  concealed  by  the  clavicular  and  upper 
sterno-costal  iibres.  This  arrangement  gives  to  the  anterior  border  of  the  axilla 
a  concave  outline,  ^^"ere  it  not  for  this  decussation,  the  muscle  would  be  l)roader 
and  thinner,  and  would  cause  an  inconvenient  and  unsightly  projection  in  front  of 
the  axilla. 

The  sterno-costal  portion  may  usually  ])e  divided  into  a  superficial  and  deep 
plane,  the  superficial  being  composed  of  the  sternal  and  external  oljlique  origin; 
the  deep,  of  the  fibres  which  s]»ring  from  the  cartilages  and  the  sixth  ril). 


Fig.  264. — The  Pectoralis  Major  and  Deltoid. 


Biceps 


Teres  major 


Aponeurosis  of  external  oblique 


External  intercostal 


Nerve-supply. — From  all  the  nerves  of  the  brachial  plexus: — (1)  through  the 
external  anterior  thoracic  nerve,  which  enters  the  deep  surface  of  the  muscle  just 
below  the  middle  of  its  upper  border;  and  (2)  through  the  internal  anterior 
thoracic,  which,  after  piercing  and  supplying  the  pectoralis  minor,  enters  the  deep 
surface  of  the  muscle  a  little  lowcu-  down,  half-Avay  between  its  origin  and  insertion. 

Action. — To  adduct.  Hex,  and  rotate  inwards  the  upper  arm.  By  its  clavicular 
]»ortion  it  will  draw  the  arm  more  directly  forwards,  as  in  round-hand  bowling, 
Avhile  the  sterno-costal  portion  will  draw  the  arm  more  downwards  than  forwards. 
The  whole  muscle  will  be  used  with  great  force  in  striking  a  blow  downwards  and 
forwards.  When  the  arm  hangs  close  to  the  side,  the  pectoralis  major  will  draw 
the  scapula  forwards  and  downwards,  so  as  to  advance  and  depress  the  point  of  the 
shoulder,   as  may  be   seen  in  a   person  shivering  with  cold,     ^\'hen    the  arm  is 


296 


THE  MUSCLES 


elevated  and  fixed,  this  muscle  Avill  draw  the  front  of  the  chest  up  to  it,  as  in 
climbing.      It  will  also  raise  the  up})er  ril)s  in  forced  ins])iration. 

Relations. — Superficially,  the  ])latysma  myoides,  the  mammary  gland,  and  the 
cutaneous  nerves  from  the  descending  branches  of  the  cervical  plexus,  as  •well  as 
the  lateral  and  anterior  perforating  branches  of  the  upper  intercostals. 

Beneath,  lie  the  subclavius,  ju^ctoralis  minor,  and  serratus  magnus,  the  fascia 
covering  the  external  and  internal  intercostal  muscles,  the  coracoid  process,  and 
costo-coracoid  membrane,  with  the  structures  which  pass  through  the  membrane, 
viz.  the  cephalic  vein,  acromio-thoracic  vessels,  and  the  external  anterior  thoracic 
nerve.  Further  outwards  it  forms  jjart  of  the  anterior  wall  of  the  axilla,  and  enters 
into  relation  with  the  biceps,  the  coraco-brachialis,  and  the  axillar}'  vessels  and 
nerves. 

The  upper  border  is  separated  from  the  deltoid  by  the  cephalic  vein  and  the 
humeral  branch  of  the  acromio-thoracic  artery. 

Variations. — The  clavicular  and  sterno-costal  portions  are  often  widely  separated.  They 
may  also  be  further  subdivided  into  separate  bauds  or  sheets,  and  they  may  be  wholly  or  partly 
absent.  Occasionally,  the  muscles  of  the  two  sides  join  across  the  sternum,  or  muscular  bauds 
may  unite  the  sternal  ends  of  the  clavicles.  Bands  may  cross  from  the  axillary  border  to  the 
latissimus  dorsi  or  the  deep  fascia  of  the  upper  arm  ;  deeper  bands  may  also  pass  to  the  insertion 
of  the  pectoralis  minor,  or  the  capsule  of  the  shoulder-joint. 


Second    Layer 

1.  SUBCLAVIUS 

The  subclavius — named  from  its  position  beneath  the  clavicle  (^  clavis) — is 
almost  cylindrical,  but  may  be  more  accurately  described  as  a  thick  sheet  of  the 
shape  of  a  low  obtuse-angled  triangle,  the  obtuse  angle  being  contained  between  the 
clavicular  attachment  and  the  inner  free  border  of  the  muscle. 


Fig.  265. — The  Subclavius  and  the  Upper  Portion  of  the  Serratus  Magnus. 


Subclavius 


Serratus  maguua 


Origin. — The  upper  and  anterior  surface  of  the  first  rib  and  its  cartilage  at  their 
point  of  junction. 

Insertion. — The  groove  on  the  lower  surface  of  the  clavicle  from  the  rhomboid 
im])ression  to  the  (;onoid  tubercle. 

Structure. — It  arises  by  a  strong  tendon,  flattened  from  before  backwards, 
which  lies  close  to  the  front  of  the  rhomboid  ligament,  and  is  continued  for  a  con- 
siderable distance  along  the  lower  border  of  the  muscle.  Its  insertion  is  by  fleshy 
fi))res  which  radiate  upwards,  outwards,  and  a  little  backwards,  in  a  penniform 
manner,  from  this  tendon;  the  inner  ascending  more  vertically,  and  the  outer  very 
obli(|uely. 

Nerve-supply. — From  the  brachial  plexus  by  a  small  lu-anch  which,  arising 
from  the  fifth  and  sixth  cervical  nerves,  passes  behind  the  clavicle  and  enters  the 
middle  of  the  back  of  the  muscle. 


SUBCLA  VIUS 


29: 


Action. — To  draw  the  outer  end  of  the  clavicle,  and  with  it  the  point  of  the 
shoulder,  downwards  and  slightly  forwards;  hut  chieliv  bv  pulling  the  bone  inwards 
to  sui)plement  the  ligaments  which  i)revent  dislocation  of  "the  sterno-clavicular  joint. 

Relations.— In  front,  tlie  clavi-])eetoral  fascia  and  the  pectoralis  major;  behind, 


Fig.  266.— The  Pectoralis  Minor,  Obliquiis  Internus,  Pyramidalis,  and  Rectus 

Abdominis. 


Subseapularis 


Pectoralis  minor 


Pectoralis  major 
Teres  major 


Internal  oblique 


Pyramidalis 
Conjoined  tendon 


29S  THE  MUSCLES 

the  posterior  division  of  the  same  fascia,  the  rhomboid  hgament,  the  su])clavian 
vessels,  and  the  brachial  plexus. 

Variations. — The  subchivius  may  be  absent,  or  its  insertion  may  extend  to  the  coracoid 
process,  transverse  ligament,  and  upjjer  border  of  the  scapula.  Occasionally  the  costo-clavicular 
portion  is  sei^arate  from  the  costo-scapular.  Again,  its  origin  may  extend  inwards  to  the  sternum, 
and  the  portion  which  arises  from  the  sternum  may  be  separate  from  the  rest  of  the  muscle. 


2.  PECTORALIS  MINOR 

The  pectoralis  minor — named  from  its  being  the  smaller  of  the  two  muscles 
which  arise  from  the  front  of  the  chest — is  a  fan-shaped  or  triangular  sheet,  with  its 
inner  edge  divided  into  three  teeth. 

Origin. — (1)  The  upper  borders  and  outer  surfaces  of  the  third,  fourth,  and 
fifth  ribs  near  their  anterior  extremities;  (2)  the  fascia  covering  the  intercostal 
muscles  in  the  spaces  between  these  ribs. 

Insertion. — (1)  The  upper  surface  of  the  coracoid  process  of  the  scapula;  (2) 
the  upper  ])art  of  the  tendon  of  the  coraco-brachialis  along  its  inner  border. 

Structure. — Its  origin  is  by  aponeurotic  slips,  which,  after  becoming  fleshy, 
converge  ui)wards,  outwards,  and  somewhat  backwards,  upon  the  flattened  tendon, 
which  is  attached  chiefly  to  the  coracoid  process,  but  blends  for  an  inch  or  more 
VteloAv  that  jn'oeess  with  the  origin  of  the  coraco-brachialis. 

Nerve-supply. — From  the  inner  cord  of  the  brachial  plexus  (through  the 
eighth  cervical  nerve )  by  the  internal  anterior  thoracic,  which  enters  its  deep  sur- 
face near  the  upper  liorder,  the  nerve  subsequently  piercing  the  muscle  to  send 
filaments  to  the  pectoralis  major. 

Its  action  is  to  draw  downwards  and  forwards  the  scapula,  depressing  at  the 
same  time  the  point  of  the  shoulder.  Taking  its  fixed  point  from  the  coracoid 
process,  it  draAvs  upwards  and  outwards  the  ribs  to  which  it  is  attached,  and 
so  helps  in  forced  inspiration.  Its  connection  with  the  tendon  of  the  coraco- 
brachialis  will  enable  it  to  act  slightly  as  a  flexor  and  adductor  of  the  humerus. 

Relations, — Superficially,  the  pectoralis  major;  deeply,  tbe  external  intercostal 
muscles;  and,  near  its  insertion,  the  axillary  vessels  and  brachial  nerves. 

Variations. — The  origin  may  extend  upwards  as  far  as  the  second,  or  downwards  to  the  sixth 
rib,  and  it  may  receive  additions  from  the  pectoralis  major.  It  is  occasionally  altogether  absent. 
Its  insertion  may  be  continued  over  the  coracoid  process  to  the  capsule  of  the  shoulder-joint,  the 
greater  tuberosity  of  the  humerus,  or  the  clavicle. 


Third  Layer 

SERRATUS  MAGNUS 

The  serratus  magnus — named  from  its  serrated  or  saw-like  anterior  border 
and  large  size — is  an  irregular  quadrilateral  sheet  curved  to  the  shape  of  the  side  of 
the  thorax.  Its  anterior  attached  l)order  has  a  somewhat  sinuous  curve,  and  arises 
from  the  side  of  the  thorax  by  nine  or  ten  digitations  or  teeth,  which,  by  their  saw- 
like appearance,  give  the  muscle  its  name.  The  muscle  may  be  divided  into  an 
upper,  middle,  and  lower  part. 

Origin. — First  part,  by  two  teeth  from  the  middle  of  the  outer  surface  of  the 
first  and  second  ribs,  and  from  the  fascia  covering  the  first  intercostal  space. 
Second  part,  by  two  or  three  heads  from  the  second,  third,  and  sometimes  the 
fourth  ribs  u])on  their  outer  surface.  Third  part,  by  far  the  largest  and  strongest 
portion  of  the  muscle,  arises  from  tbe  fom-tb  or  fifth  to  the  eighth  or  ninth  ril)s  l\v 
a  series  of  teeth,  which  are  attached  in  front  near  the  upper  border  of  each  rib,  and 
behind  to  a  line  running  backwards  across  tlie  outer  surface  of  the  ril)  from  its 
u])per  to  its  lower  l)()rder.  These  attachments  form  a  curved  line  with  the  con- 
vexity forwards,  the  attachment  to  the  sixth  rib  l)eing  the  most  anterior  and 
prominent. 


SERRATUS  MAGNUS 


299 


Insertion. — The  first  part  is  attached  to  an  oval  space  upon  the  venter  of  the 
scapula  close  to  the  posterior  superior  angle.  The  second  part,  to  tin-  whole  of 
the  vertehral  l:)or(ler  of  the  scai)iila  upon  its  ventral  aspect.  The  third  part  to  the 
large  oval  space  on  the  venter  of  the  scapula  close  to  its  inferior  angle. 

Structure. — The  origin  of  the  muscle  is  by  fleshy  or  shoit  aponeurotic  fibres, 
and  in  the  first  part  these  fibres  converge  very  slightly  towards  their  fleshy  inser- 
tion. In  the  second  part  they  diverge  and  form  a  thin  sheet  attached  to  the  verte- 
])ral  border  of  the  scapula.  In  the  third  part  of  the  muscle  the  fibres  converge 
fanwise  and  form  a  very  thick  and  strong  fleshy  mass  Avhich  is  inserted  directly 
into  the  inferior  angle  of  the  scapula.  At  their  origin  the  teeth  of  this  part  of  the 
muscle  interdigitate  with  or  fit  in  l)etween  those  of  the  origin  of  the  oljlicjuus 
alxlominis  externus.  All  the  fibres  are  curved  to  adapt  themselves  to  the  convex 
wall  of  tlie  chest. 

Nerve-supply. — From  the  brachial  plexus  by  the  posterior  thoracic  nerve, 


Fig.  267. — Serratl's  Magxls. 


Tipper  part  of 
serratua  tnaguus 


Middle  part 


Lower  part 


which  is  derived  from  the  fifth,  sixth,  and  seventh  cervical  nerves.  After  running 
down  the  side  of  the  chest  upon  the  outer  surface  of  the  muscle,  the  nerve  is  dis- 
tri1)uted  by  many  branches  to  the  various  digitations. 

Action. — By  its  contraction,  this  muscle  draws  forwards  the  vertebral  border  of 
the  scapula  and,  as  the  third  part  of  it  is  much  the  strongest,  it  will  act  especially 
upon  the  inferior  angle,  and  will  rotate  tlie  scapula  so  as  to  raise  the  point  of  the 
shoulder.  It  will  therefore  help  the  trapezius  muscle  in  raising  the  shoulder, 
and  it  will  l)e  l)rought  powerfulh'  into  play  wlienever  the  shoulder  is  used  in  push- 
ing in  a  forward  direction.  It  is  most  important,  however,  in  relation  to  the 
movements  of.  the  arm.  In  order  that  the  deltoid  muscle  may  raise  the  humerus, 
it  is  necessarv  that  the  fulcrum  formed  by  the  glenoid  portion  of  the  scapula  should 
be  held  steady.  For  this  reason  the  scapula  extends  so  far  downwards  in  order 
that  the  leverage  given  to  the  third  and  most  jjowerful  portion  of  the  serratus  may 
be  as  great  as  possible.      When  the  serratus  magnus  is  paralysed,  all  the  efforts  of 


300  THE  MUSCLES 

the  deltoid  to  elevate  the  arm  are  unsuccessful,  and  only  cause  the  lower  angle  of 
the  scapula  to  project  from  the  back  of  the  thorax.  A\'hen  the  arm  has  been  ele- 
vated to  its  full  extent  by  the  deltoid,  that  is,  through  about  a  right  angle,  the 
rotation  of  the  sca})ula  due  to  the  serratus  magnus  and  trapezius  will  produce  a 
further  elevation  through  another  riglit  angle,  and  so  place  the  arm  in  a  vertical 
position.  One  of  the  results  of  the  action  of  this  muscle  is  to  keep  the  lower  angle 
of  tlie  scapula  in  close  contact  with  the  wall  of  the  thorax.  When  the  muscle  is 
paralvsed,  the  posterior  borders  and  the  inferior  angles  of  the  scapulae  project  back- 
wards from  the  thorax  like  small  wings  {iycapidx  alatx). 

Acting  from  its  scapular  insertion,  the  muscle  tends  to  draw  the  front  of  the 
chest  towards  the  scapula,  e.g.  when  it  supports  the  thorax  in  crawling  on  the 
hands  and  knees.  Judging  from  the  direction  in  which  its  fibres  are  inserted  into 
the  ribs,  most  of  them  can  have  little  if  any  action  in  elevating  the  ribs,  as  in  forced 
inspiration. 

Relations. — Superficially,  the  pectoralis  major  and  minor,  the  subscapularis 
and  latissimus  dorsi,  the  subclavian  and  axillary  vessels  and  the  brachial  plexus; 
deeply,  the  external  intercostal  muscles,  and  serratus  jDOsticus  superior. 

Variations. — It  may  arise  as  low  as  the  tenth  rib;  and  above,  it  may  receive  slijis  from  the 
cervical  transverse  processes,  or  the  levator  auguli  scapulae.  Part  or  the  whole  of  the  muscle  may 
be  deficient. 


The  Second  Group  comprises  the  muscles  which  pass  from  the  scapula  to  the 
upper  limb,  and  move  the  upper  arm.  Some  of  the  most  important  adductors, 
flexors,  and  extensors  belong  to  the  first  group;  but  abduction  and  rotation  in  both 
directions  are  provided  for  by  the  second  group. 


MUSCLES  WHICH  PASS  FROM  THE  SCAPULA  TO  THE 

UPPER  LIMB 

These  are  nine  in  number,  viz.  the  deltoid,  supra-spinatus,  infra-spinatus,  teres 
minor,  subscapularis,  teres  major,  coraco-brachialis,  biceps,  and  triceps.  The  two 
last,  however,  as  they  act  chiefly  upon  the  forearm,  will  not  be  described  in  this 
group. 

The  superficial  fascia  covering  the  muscles  contains  but  little  fat.  The  deep 
fascia  is  thin  where  it  covers  the  front  of  the  deltoid,  and  is  continuous  with  that 
whicli  invests  the  pectoralis  major  and  the  axillary  fascia.  Behind,  it  is  thicker, 
especially  where  it  covers  in  the  lower  part  of  the  infra-spinatus.  Below,  it  lilends 
with  the  deep  fascia  of  the  upper  arm.  Above,  it  is  connected  with  the  clavicle  and 
scajnila  above  the  upper  attachment  of  the  deltoid. 

It  is  also  connected,  either  directly  or  by  strong  intermuscular  septa,  with  the 
vertebral  and  axillary  borders  of  the  scapula. 

Processes  from  it  cover  the  dee]ier  surface  of  the  deltoid,  and  form  sheaths  to  all 
the  muscles  of  this  group. 

1.   DELTOID 

The  deltoid  muscle  (figs.  262  and  264) — named  from  its  resemblance  to  the 
Greek  letter  deltn  when  inverted — is  a  very  thick  triangular  sheet,  with  the  apex 
directed  downwards,  and  with  its  ])lane  curved  upon  itself  from  before  backwards, 
so  as  to  wrap  round  the  front,  outer  side,  and  back  of  the  upjicr  end  of  the 
humorus. 

Origin. — (1)  The  anterior  border  and  adjacent  part  of  the  u])per. surface  of  the 
outer  third  of  the  clavicle;  (2)  the  outer  border  and  adjacent  part  of  tlie  ujijier 
surface  of  the  acromion;  (3)  the  lower  border  of  the  spine  of  the  scai)ula  and 
the  fascia  covering  the  infra-si)iiiatus  muscle,  near  the  vertebral  border  of  the 
scapula. 


DELTOID— SUPRA-SPIXATUS  301 

Insertion. — A  rough  triangular  impression,  with  the  apex  downwards,  and 
from  two  to  three  inches  long,  just  above  the  middle  of  the  outer  surface  of  the 
humerus. 

Structure. — At  the  front  and  back  part  of  its  origin  it  arises  by  short,  tendinous 
fibres  which  end  in  parallel  muscular  bundles.  At  the  middle  part,  strong  fibrous 
septa  three  or  four  in  number  pass  downwards  from  the  acromion  process  into  the 
substance  of  the  muscle,  upon  the  surface  of  which  their  outer  edges  are  visible. 
The  fleshy  fibres  of  this  part  of  the  muscle  arise  both  from  the  acromion  and  from 
the  surfaces  of  these  septa.  The  short  strong  tendon  of  insertion  is  prolonged 
upwards  into  three  fibrous  planes,  which,  as  well  as  the  tendon,  receive  the 
fleshy  fibres  of  the  middle  part  in  multipenniform  fasliion.  The  muscular 
bundles  from  the  front  and  back  parts  of  the  origin  are  inserted  upon  the 
anterior  and  posterior  surfaces  of  the  tendon  of  insertion.  In  front,  this  tendon 
is  connected  with  that  of  the  pectoralis  major;  below,  it  gives  fibres  to  the 
external  intermuscular  septum,  and  also  to  the  upper  part  of  the  brachialis  anticus. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
fifth  and  sixth  cervdcal  nerves)  by  means  of  the  circumflex  nerve.  This  nerve 
enters  the  deep  surface  of  the  muscle  by  several  filaments  about  half  way  between 
the  origin  and  insertion. 

Action. — ^Mlen  all  its  fibres  contract  together,  it  will  abduct  the  humerus 
through  a  right  angle.  If  the  first  and  second  parts  act  alone,  they  will  flex  and 
aV)duct  the  arm,  as  when  it  is  raised  to  the  level  of  the  shoulder  and  at  the  same 
time  directed  forwards.  The  posterior  and  middle  portions  of  the  muscle  by  their 
contraction  will  abduct  the  arm,  and  at  the  same  time  extend  it,  as  when  the  arm 
is  elevated,  and  at  the  same  time  directed  backwards. 

The  movements  of  abduction,  or  of  abduction  combined  with  flexion,  are 
through  90°;  of  abduction  combined  with  extension,  only  through  45°.  In  its 
action  the  muscle  forms  a  lever  of  the  third  order.  The  greater  advantage  which  it 
gains  I)y  its  insertion  at  a  considerable  distance  from  its  fulcrum  at  the  shoulder- 
joint  is  lost  by  the  extreme  oljliquity  of  its  direction.  Hence  the  great  thickness 
and  strength  of  the  muscle,  and  the  facility  with  which  this  movement  is  lost  by 
injury  or  disease.  For  the  proper  action  of  this  muscle  in  elevation  of  the  arm,  it 
is  necessary  that  the  scapula  should  be  held  firm  by  means  of  the  serratus  magnus. 

Relations. — Superficially,  the  integument  and  deep  fascia;  upon  its  front 
border,  the  pectoralis  major,  a  small  artery,  and  the  cephalic  vein;  deeply,  the 
coracoid  process  and  upper  extremity  of  the  humerus,  the  tendons  of  the  pectoralis 
minor  and  major,  the  short  head  of  the  biceps,  coraco-brachialis,  subscapularis, 
supra-spinatus,  infra-spinatus,  teres  minor,  the  long  heads  of  the  biceps  and  triceps, 
the  outer  head  of  the  tricei)S,  the  coraco-clavicular  and  coraco-acromial  ligaments, 
the  circumflex  arteries  and  nerve,  and  a  large  bursa  which  separates  the  muscle 
from  the  greater  tuberosity  of  the  humerus  and  the  structures  attached  to  it;  below, 
it  comes  into  contact  with  the  upper  part  of  the  brachialis  anticus. 

Variations. — The  clavicular  portion  of  its  origin  may  reach  inwards  as  far  as  that  of  the  pec- 
tcjralis  major,  and  the  two  muscles  ma.v  blend  along  their  adjacent  borders.  Behind,  it  may 
receive  separate  bands  from  the  fascia  infra-spinata  or  the  borders  of  the  scapula.  Occasionall}' 
transverse  fibres  have  been  found  lying  in  the  substance  of  the  muscle  close  to  its  acromial  origin. 


2.  SUPRA-SPIXATUS 

The  supra-spinatus — named  from  its  position  above  the  spine  of  the  scapula — 
is  a  somewhat  fan-shaped,  thick  triangular  sheet. 

Origin. — (1)  The  inner  two-thirds  of  the  supraspinous  fossa;  (2)  the  upper 
surface  of  the  spine  of  the  scapula;  and  (3)  the  fascia  covering  the  muscle. 

Insertion. — (1)  The  upper  facet  of  the  greater  tuberosity  of  the  humerus;  and 
(2)  the  capsular  ligament  of  the  shoulder-joint. 

Structure. — It  arises  by  fleshy  fibres  wliich  converge  upon  a  tendon  which  is 
concealed  in  the  substance  of  the  muscle  almost  to  the  point  of  its  insertion. 

Nerve-supply. — From  the  brachial  plexus  (through  the  fifth  cervical  nerve) 


302 


THE  MUSCLES 


by  the  suprascapular  liranch  wliieli  enters  the  muscle  upon  its  deep  aspect  near  its 
upper  border. 

Action. — It  assists  the  deltoid  in  al)duetin<r  the  arm;  it  also  strengthens  the 
shoulder-joint  l)y  resisting  the  tendency  to  u})\vard  disj)lacement  of  the  head  of 
the  luunerus,  and  by  drawing  the  head  of  the  humerus  tirmly  towards  the  centre  of 
the  glenoid  cavity. 


Fig.  268. — Back  View  of  the  Scapulae  Muscles  and  Triceps. 


Supra-spinatus 


Infra-spinatus  ''^£ 
Teres  minor 


Teres  major 


Long  head  of  triceps 


Outer  head  of  triceps 


Inner  head  of  triceps 


Relations. — Su]ierficially,  the  trapezius,  deltoid,  and  coraco-acromial  ligament; 
deeply,  the  oino-hyoid  muscle  and  capsular  ligament,  the  suprascapular  vessels  and 
nerve. 


3.  INFRA-SPINATUS 

Tlie  infra-spinatus — named  from  its  position  below  the  spine  of  the  sca])ula — 
is  a  thick,  fan-shaped  slieet. 

Origin.— (1)  The  inner  two-thirds  of  tlie  infraspinous  fossa;  (2)  the  under 
surface  of  the  spine  of  the  scai)ula;  (3)  the  infraspinous  fascia,  and  a  thick  inter- 
muscular septum  which  separates  it  from  the  teres  minor  and  major  muscles. 

Insertion. — (1)  The  middle  facet  on  the  greater  tuberosity  of  the  humerus; 
and  (2)   the  ea])sule  of  the  shonlder-joint. 


TERES  MINOR— SUBSCAPULARIS  303 

Structure. — Its  origin  is  by  fleshy  til)res  which  converge  outwards  in  bipenni- 
forni  fashion  iii)(>n  the  tendon.  Frequently  that  part  which  arises  from  the  lower 
surface  of  the  s|)ine  of  the  scapula  overlies  and  is  somewhat  separate  from  the  rest. 
Its  insertion  into  the  capsule  and  tul)erosity  is  by  a  tendon  which  is  almost  entirely 
concealed  by  fleshy  fibres. 

Nerve-supply. — From  the  brachial  plexus  (through  the  fifth  cervical  nerve), 
by  the  suprascapular  branch  which  enters  the  deep  surface  of  the  muscle  at  its 
outer  part  and  near  its  upper  border. 

Action. — It  is  the  chief  external  rotator  of  the  humerus.  This  movement  of 
external  rotation  is  through  about  90°,  and  is  of  great  importance.  When  the 
elbow  is  bent,  it  produces  the  lateral  movement  of  the  hand  by  which,  in  writing, 
the  pen  is  carried  from  left  to  right  across  the  page,  ^^'hen  the  elljow  is  extended, 
the  rotation  of  the  humerus  adds  considerably  to  the  range  of  rotatory  movement 
enjoyed  by  the  hand.  The  infra-spinatus  also  adducts  the  elevated  arm,  at  the 
same  time  drawing  it  slightly  backwards,  or  extending  it.  It  helps  to  hold  the 
head  of  the  humerus  in  contact  with  the  glenoid  cavitA\ 

Relations. — Superficially,  the  infraspinous  fascia  which  separates  it  from  the 
deltoid,  trapezius,  and  latissimus  dorsi;  deeply,  the  suprascapular  and  dorsalis 
scapulae  vessels,  and  sometimes  a  small  bursa  which  intervenes  between  its  tendon 
and  the  capsule  of  the  shoulder-joint;  externally,  the  teres  major  and  minor. 

Variations. — The  slip  from  the  under  surface  of  the  spine  is  frequently  almost  as  separate 
from  the  iufra-spinatus  as  the  teres  minor,  and  sometimes  there  is  no  separation  between  the 
infra- s}iinatus  and  teres  minor. 

4.  TERES  MINOR 

The  teres  minor — named  from  its  Ijeing  the  lesser  of  two  somewhat  cylindrical 
muscles  {tere^  =^  round  or  cylindrical) — is  a  thick  but  narrow  triangular  or  fan- 
shaped  sheet. 

Origin. — (1)  The  impression  which  occupies  the  upper  two-thirds  of  the 
axillary  Ijorder  of  the  infraspinous  fossa;  (2)  septa  which  separate  it  from  the 
infra-spinatus  behind,  and  the  teres  major  in  front. 

Insertion. — (1)  The  lowest  of  the  three  facets  on  the  greater  tuberosity  of  the 
humerus  and  the  posterior  surface  of  that  bone  for  one  inch  (2 '5  cm.)  below  the 
facet;   (2)  the  capsule  of  the  shoulder-joint. 

Structure. — From  a  fleshy  origin  which  terminates  in  a  point  below,  its  fibres 
pass  upwards  and  outwards  to  their  insertion,  which  is  by  a  short  strong  tendon 
into  the  lowest  facet  on  the  tuberosity,  and  the  capsule  of  the  shoulder-joint;  below 
the  facet  it  is  inserted  by  fleshy  or  very  short  tendinous  filires. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
fifth  cervical  nerve)  by  the  lower  division  of  the  circumflex  nerve  which  enters  the 
muscle  upon  its  anterior  surface  near  its  insertion.  The  nerve  is  remarkable  on 
account  of  the  ganglion  upon  its  trunk  shortly  before  it  passes  into  the  muscle. 

Action. — The  same  as  that  of  the  preceding  muscle,  of  which  it  may  be  con- 
sidered to  form  a  part.  It  will  therefore  rotate  the  arm  outwards  and  at  the  same 
time  adduct. 

Relations. — Behind,  the  deltoid;  in  front,  the  long  head  of  the  triceps,  the 
teres  major,  and  subscapularis.  Above  and  internally,  the  dorsalis  scapula?  vessels 
run  between  it  and  the  axillary  border  of  the  scapula. 


5.  SUBSCAPULARIS 

The  subscapularis  muscle — named  from  its  position  beneath  the  scapula — is 
a  thick  triangular  and  somewhat  multipenniform  sheet. 

Origin. — (1)  The  whole  of  the  ventral  surface  of  the  scapula  with  the  exception 
of  the  part  near  the  neck,  and  the  spaces  at  the  upper  and  lower  angles  occupied  hy 
the  serratus  magnus;  (2)  the  lower  two-thirds  of  the  grooved  outer  border  of  the 
scapula;  and  (8)  the  internuiscular  sei)tum  between  it  and  the  teres  major. 


304 


THE  MUSCLES 


Insertion. — (1)  The  lesser  tul)erosity  of  the  humerus,  and  the  part  of  the  shaft 
inmu'diati^'ly  below  it;   (2)  the  front  of  the  capsular  ligament  of  the  shoulder-joint. 

Structure. — Its  origin  is  by  fleshy  fibres  from  the  surface  of  the  ))one,  and  also 
by  bi{)enniform  bundles  from  the  upper  and  lower  surfaces  of  three  or  four  septa 
which  are  attached  to  the  transverse  ridges  upon  the  venter  scai)ul8e,  so  that  the 
whole  muscle  has  a  multipenniform  arrangement.  The  fibres  converge  upwards 
and  outwards  upon  a  strong  tendon  which  is  hidden  by  fleshy  fibres  to  within  a 
short  distance  of  its  insertion,  the  lower  part  of  which  is  also  fleshy.  A  bursa 
intervenes  between  the  tendon  and  the  base  of  the  coracoid  process,  and  is  usually 
in  connection  with  the  shoulder-joint. 

Nerve-supply. — From  the  posterior  cord  of  the  bi'achial  plexus  (through  the 
fifth  and  sixth  cervical  nerves),  by  the  short  and  part  of  the  lower  subscapular 
nerves.  They  enter  the  front  surface  of  the  muscle,  the  former  near  its  upper,  the 
latter  near  its  outer  border. 

Action. — It  is  the  chief  internal  rotator  of  the  humerus;  at  the  same  time  it 
adducts  it   after  it   has   been   elevated.     It  also  has   an   important   influence  in 


Fig.  269. — Front  View  of  the  Scapular  Muscles. 


CLAVICLE  — 
CORACOID  PROCESS 
Supra-spinatus 


Subacapularis 


Teres  major 
Latissimus  dorsi 


Coraco-brachialiB  and  short 
head  of  biceps 

Peetoralis  major 


strengthening  the  shoulder-joint  by  drawing  the  head  of  the  humerus  towards  the 
glenoid  cavity. 

Relations. — Its  anterior  and  internal  face  forms  the  greater  part  of  the  posterior 
wall  of  the  axilla,  and  is  in  contact  with  the  serratus  magnus,  the  short  head  of  the 
biceps,  and  the  coraco-brachialis,  the  axillary  vessels  with  many  of  their  branches, 
the  brachial  plexus  and  its  branches,  the  lymphatic  glands  and  vessels;  its  outer 
border  lies  in  contact  with  the  teres  major,  the  posterior  circumflex  and  dorsalis 
scapula?  vessels,  and  the  circumflex  nerve;  behind  lie  the  long  head  of  the  triceps 
and  the  teres  minor  muscle,  and  the  bursa  which  intervenes  between  its  tendon  and 
the  capsule  of  the  shoulder-joint. 

Variations. — Occasionally  a  separate  slip  arises  from  the  axillary  border  of  the  scapula,  and  is 
inserted  into  the  capsule  of  the  shoulder-joint  or  into  the  humerus. 


6.  TERES  MAJOR 

The  teres  major — named  from  its  somewhat  cylindrical  shape  and  its  size — is 
a  thick  ril)l)on-sliaped  muscle. 

Origin. — (1)  The  oval  facet  which  occupies  the  lower  third  of  the  axillary 
border  of  the  infraspinous  fossa;  (2)  the  infrasi)inous  fascia  and  the  intermuscular 


CORACO-BRACH TALIS  305 

septa,  which  separate  the  muscle  from  the  subscapularis,  the  teres  minor,  and  infra- 
spinatus. 

Insertion. — The  inner  hp  of  the  bicipital  groove  from  the  lower  border  of  the 
lesser  tul)erosity  for  about  two  inches  (5  cm.)  down  the  humerus. 

Structure. — Its  origin  is  by  fleshy  fibres  which  pass  upwards,  outwards,  and 
somewhat  forwards,  to  be  inserted  by  a  strong  tendon,  which  is  first  visible  upon 
the  outer  Ijorder,  and  then  upon  the  anterior  surface  of  the  muscle,  and  which  is  in 
close  relation  with  the  l)ack  of  the  tendon  of  the  latissimus  dorsi.  A  small  bursa 
intervenes  b(4\veen  the  Iavo  tendons. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
sixth  and  seventh  cervical  nerves)  by  the  lower  subscapular  nerve,  which  enters  the 
muscle  upon  its  anterior  aspect  close  to  the  middle  of  its  inner  Ijorder. 

Action. — It  assists  the  latissimus  dorsi  as  a  strong  adductor,  and  in  some  posi- 
tions of  the  arm  as  an  internal  rotator  of  the  humerus. 

When  the  arm  is  fixed  it  will  act  with  the  latissimus  dorsi  in  drawing  the  body 
upwards,  as  in  climbing.  Its  influence,  however,  will  be  exerted  upon  the  lower 
angle  of  the  scapula,  while  that  of  the  latissimus  dorsi  is  chiefl}'  upon  the  trunk 
and  ]:)elvis. 

Relations. — In  front  lie  the  latissimus  dorsi,  both  heads  of  the  biceps,  the 
coraco-l)rachialis.  the  pectoralis  major,  the  axillary  vessels,  and  the  lower  branches 
of  the  brachial  plexus;  behind,  the  latissimus  dorsi,  teres  minor,  the  long  and  outer 
heads  of  the  triceps;  between  its  upper  border  and  the  subscapularis  muscle  are  the 
posterior  circumflex  and  dorsalis  scapulae  vessels,  and  the  circumflex  nerve;  below 
are  the  superior  profunda  vessels  and  the  musculo-spiral  nerve. 


7.  CORACO-BRACHIALIS 

The  coraco-brachialis — named  from  its  attachment  to  the  coracoid  process  and 
the  upper  arm  {brachuiui) — is  a  cylindrical  muscle,  but  somewhat  fusiform  at  the 
extremities. 

Origin. — (1)  The  tip  of  the  coracoid  process;  (2)  the  inner  side  of  the  tendon 
of  the  sliort  head  of  the  biceps. 

Insertion. — (1)  The  rough  impression  two  or  three  inches  long  upon  the  inner 
border  of  the  humerus  in  its  middle  third,  and  in  front  of  the  internal  interaiuscular 
septum  (see  page  306);  (2)  the  internal  intermuscular  septum  and  an  aponeurotic 
band  which  extends  upwards  from  the  septum  in  front  of  the  tendons  of  the  teres 
major  and  the  latissimus  dorsi  to  the  lesser  tuberosity  of  the  humerus. 

Structure. — It  arises  from  the  coracoid  process  l)y  a  short  tendon,  which  is 
blended  upon  its  inner  side  with  the  insertion  of  the  pectoralis  minor,  and  from 
the  short  head  of  the  biceps  by  fleshy  fibres  for  three  or  four  inches  (8-10  cm. ) 
Ix'low  the  coracoid  j^rocess.  From  this  origin  the  fil)res  run  parallel  to  one  another, 
and  are  inserted  by  a  short  tendon.  The  muscle  is  frequently  divided  into  two 
planes  between  which  the  external  cutaneous  nerve  passes. 

Nerve-supply. — From  the  outer  cord  of  the  brachial  plexus  (through  the 
seventh  cervical  nerve)  by  the  musculo- cutaneous  branch,  Avhich  either  pierces  it 
about  the  middle  upon  its  way  to  the  biceps  and  brachialis  anticus,  or  sends  a 
branch  to  it  in  this  position,  while  the  rest  of  the  ner\-e  passes  in  front  of  the 
muscle. 

Action. — To  adduct  and  flex  the  humerus.  As  it  lies  at  so  small  an  angle  with 
the  axis  of  that  l)one,  it  assists  materially  in  pressing  the  head  of  the  humerus 
against  the  glenoid  ca\'ity,  and  so  helps  to  prevent  dislocation. 

Relations. — Superficially,  the  deltoid  and  pectoralis  major;  deeply,  the  sub- 
scapularis, latissimus  dorsi,  teres  major,  and  triceps.  Upon  its  outer  side  lies  the 
short  head  of  the  biceps;  upon  its  inner  side  the  pectoralis  minor,  the  axillary  and 
brachial  vessels,  with  the  median  ner\'e  and  other  l)ranches  of  the  brachial  plexus. 

Variations. — The  coraco-brachialis  varies  chiefly  in  its  insertion,  which  may  extend  as  high 
as  the  cai)sule  of  the  shouMer  or  the  lesser  tu}>erosity.  occasionally  forming  in  this  position  a 
separate  muscle  (the  rotator  humeri);  or  it  may  descend  as  low  as  the  inner  condyle.     It  some- 
times sends  a  slip  to  the  triceps  or  brachialis  anticus. 
20 


306 


THE  MUSCLES 


GROUP  OF  MUSCLES  WHICH  :\rOYE  THE  ELBOW-JOIXT 

Fasci.e  of  the   Upper  Arm 

Tlie  deep  fascia  of  the  upper  arm  forms  a  strong  tube,  thicker  upon  the  pos- 
terior than  the  anterior  aspect,  enclosing  all  the  muscles  and  most  of  the  vessels  and 
nerves.  Aljove,  it  is  continuous  on  the  outer  side  and  front  with  tlie  fascia  covering 
the  deltoid  and  pectoralis  major,  and  internally  with  the  axillary  fascia.     In  the 


Fig.  270. — SuPEKFiciAL  View  of  the  Front  of  the  Upper  Arm. 


Pectoralis  minor 


Coraeo-brachialis 


Long  head  of  triceps 


Inner  head  of  triceps 


Brachialis  anticus 


Semilunar  fascia 


Tendons  of  insertion  of  pec- 
toralis major  and  deltoid 


—  Outer  head  of  triceps 


Brachialis  anticus 


Extensor  carpi  radialis 
longior 


Brachi,o-radialis 


lower  two-thirds  of.  the  upper  arm  it  is  joined  upon  its  deep  aspect  by  two  strong 
l)rocesses:  the  rxterivil  iitteriniisfiilur  s('j)(iim,  wliich  arises  from  the  external  condylar 
ridge  and  the  outer  border  of  the  humerus;  and  the  internal  intermvscular  septum, 
which  arises  from  the  internal  condylar  ridge  and  the  inner  border  of  the  humerus. 
The  tube  formed  by  the  deep  fasc-ia  is  thus  divided  by  the  bone  and  these  two  septa 
into  two  com})artments.  In  the  front  comj^artment  are  placed  the  Hexors  of  the 
elliow-joint,  and  in  the  back  comj)artment  tlie  great  extensor  muscle. 


BICEPS  307 


Flexdrs  of  the  Forearm 

The  flexor  muscles  are  three  in  number.  The  most  su])erfieial  is  the  biceps, 
which  arises  from  th(^  sca])ula;  while  more  clee])ly  lie  the  brachialis  anticus  and 
brachio-radialis  (supinator  longusj,  which  arise  from  the  humerus. 


1.  BICEPS 

The  biceps  flexor  cubiti — named  from  its  two  heads  and  its  action  upon  the 
cul)itus,  or  elbow — is  a  thick,  somewhat  flattened  fusiform  muscle  with  a  bifid  upper 
extremity. 

Origin. — (1)  The  short  head  from  the  outer  side  of  the  tip  of  the  coracoid 
])rocess,  in  close  connection  with  the  coraco-l^rachialis  muscle;  (2)  the  long 
head,  from  the  upper  border  of  the  glenoid  fossa  of  the  scapula  and  from  the 
glenoid  ligament. 

Insertion. — (1)  The  posterior  border  of  the  tubercle  of  the  radius;  (2)  the 
upi)er  i)art  of  the  deep  fascia  on  the  inner  side  of  the  front  of  the  forearm,  two 
inches  (  o  cm. )  below  the  inner  condyle  of  the  humerus. 

Structure. — The  short  head  arises  by  a  short  tendon  from  which  the  fleshy 
fibres  diverge  in  a  somewhat  conical  form  until  they  meet  and  Ijlend  with  the  outer 
and  longer  head  about  the  middle  of  the  ui)})er  arm. 

The  long  head  arises  by  a  thick  ribbon-like  tendon  three  to  four  inches  (about 
9  cm. )  long,  Avhich  at  its  origin  upon  the  upper  liorder  of  the  glenoid  fossa  bifur- 
cates and  blends  with  the  glenoid  ligament  of  the  shoulder-joint.  It  first  passes 
outwards  and  arches  over  the  rounded  head  of  the  humerus.  It  afterwards  enters 
the  canal  formed  by  the  bicipital  groove  internally,  and  externally  l^y  the  capsule 
of  the  joint,  together  with  the  aponeurotic  expansion  derived  from  the  tendon  of 
the  pectoralis  major.  Down  to  this  point  it  is  invested  by  synovial  membrane, 
which  is  reflected  upon  it  from  the  adjacent  bone  and  capsule.  After  emerging  at 
the  lower  end  of  the  bicipital  groove  it  gives  origin  to  a  conical  mass  of  fleshy  fibres, 
which  meet  with  the  fibres  derived  from  the  shorter  head  about  the  middle  of  the 
up])er  arm.  The  fleshy  l^undles  belonging  to  the  two  heads  may  be  separated  for 
a  considerable  distance  by  careful  dissection.  A  little  below  the  middle  of  the 
upper  arm,  the  tendon  of  insertion  commences  as  a  septum  between  the  two  bellies 
of  the  muscle.  It  rapidly  increases  in  thickness,  and  about  the  level  of  the  con- 
dyles it  becomes  free,  and  as  a  flattened  cord  passes  down  in  the  middle  of  the 
bend  of  the  elbow  and  turns  upon  itself  so  that  its  anterior  aspect  now  liecomes 
external;  before  its  insertion  into  the  posterior  liorder  of  the  tuliercle  of  the  radius 
it  is  sei)arated  from  that  process  l)y  a  small  synovial  bursa.  About  an  inch  and  a 
half  (4  cm. )  from  its  insertion  it  gives  off  from  its  inner  ];)order  a  strong  l)and  of 
fii)rous  tissue  three-quarters  of  an  inch  broad  and  one  inch  long  (the  semilunar 
fascia),  to  the  deep  fascia  covering  the  ulnar  surface  of  the  forearm. 

Nerve-supply. — From  the  outer  cord  of  the  brachial  plexus  (through  the  sixth 
and  seventh  cervical  nerves)  by  a  branch  of  the  musculo-cutaneous  nerve  which 
enters  the  muscle  on  its  posterior  aspect  near  its  inner  border. 

Action. — (1)  It  flexes  the  elbow-joint  by  means  of  its  radial  insertion,  and 
also  by  the  attachment  of  the  semilunar  fascia  to  the  inner  side  of  the  forearm. 
(2)  It  supinates  strongly  the  forearm  l)y  means  of  the  radial  tendon  which  wra]is 
round  the  tubercle  of  the  radius.  This  movement  will  be  most  ])Owerful  wlu'n  the 
ell)ow  is  l)ent  to  a  right  angle,  as  the  tendon  is  then  peri)endicular  to  the  l)one, 
which  it  causes  to  revolve.  To  increase  its  leverage,  the  tendon  is  lifted  away  from 
the  axis  of  the  bone  by  the  prominence  of  the  tubercle.  (3)  It  will  assist  some- 
what feebly  in  the  movements  of  the  shoulder-joint,  its  short  head  being,  like  the 
coraco-brachialis,  a  flexor  and  adductor  of  the  upper  arm.  By  its  long  head  it 
binds  down  the  upper  i)ortion  of  the  humerus,  and  prevents  the  tendency  to  dislo- 
cation u]iwards.  "\Mien  the  forearm  is  fixed,  the  Ijiceps  will  help  in  flexing  the 
elbow,  as  in  climbing  or  in  drawing  up  the  trunk  to  a  horizontal  bar. 

Relations. — Superficially,   the  deltoid  and  pectoralis  major,   the  deep  fascia. 


508 


THE  MUSCLES 


and  at  the  bend  of  the  elbow  the  median  cephalic  vein  and  brachio-radiahs; 
deeply  the  humerus,  the  brachiahs  anticus,  and  supinator  brevis;  upon  its  mner 
side  lie  the  coraco-braehialis,  the  brachial  vessels,  and  the  median  nerve.  The 
semilunar  fascia  separates  the  median  l)asilic  vein  from  the  ])rachial  vessels  and 
median  nerve. 


Fig.  271.— Deep  View  of  the  Froxt  of  the  Upper  Arm. 


Pectoralis  minor 


Short  head  of  biceps 


Coraeo-brachialis 


Long  head  of  triceps 


Inner  head  of  triceps 


Internal-intermuseular  septum 


Long  head  of  biceps 


Insertion  of  pectoralis  major 


Insertion  of  deltoid 


Brachialis  anticus 


Cuter  part  of  brachialis  anticus 


Insertion  of  biceps 


Variations.— The  origin  of  the  biceps  is  remarkably  variable.  Sometimes  one  of  the  heads 
is  deficient.  More  often  a  third  liead  is  derived  froni  the  middle  of  the  inner  border  of  the 
liumorus,  and  sometimes  as  many  as  three  additional  heads  have  been  found  arising  troni  the 
humerus.  Occasionally  it  sends  slips  to  the  inteinal  intermuscular  septum,  internal  condyle,  or 
coronoid  process. 


2.   BRACHIALIS  ANTICUS 

The  brachialis  anticus — named  from  its  intimate  relation  with  the  front  of 
the  humerus  {braclii>im) — is  a  thick,  somewhat  fusiform  sheet,  curved  from  side 
to  side  to  fit  on  to  the  front  of  the  humerus,  and  slightly  bifid  above. 


BRACHIO-RADIA  LIS— TRICEPS  309 

Origin. — The  whole  of  the  lower  three-fifths  of  the  front  of  the  humerus,  with 
the  exception  of  the  small  space  on  its  inner  aspect  occupied  l^y  the  coraco- 
hrachialis  and  the  impression  upon  the  outer  aspect  for  the  deltoid  muscle,  upon 
either  side  of  which  it  sends  up  two  small  pointed  processes;  (2)  the  front  of  the 
internal  intermuscuhir  septum;  (3)  a  small  i)ortion  of  the  ui:>per  part  of  the  front 
of  the  external  intermuscular  septum  above  the  point  where  it  is  i)ierced  Ijy  the 
musculo-spiral  nerve. 

Insertion. — The  inner  and  lower  part  of  the  rough  triangular  impression  upon 
the  front  of  the  coronoid  process  of  the  ulna. 

Structure. — The  greater  part  of  its  origin  is  by  fleshy  fil^res  which  converge 
upon  a  tendinous  sheet  which  makes  its  appearance  at  first  u2:)on  the  anterior 
surface  of  the  muscle,  just  above  the  level  of  the  elbow-joint.  This  tendinous  sheet 
receives  the  converging  fleshy  fibres  upon  its  posterior  aspect,  and  becomes  gradually 
thicker  until  it  forms  a  very  strong  tendon  of  insertion  which  is  closely  connected 
with  the  front  of  the  anterior  ligament  of  the  elbow-joint.  The  lower  and  outer 
portion  of  the  miiscle  is  deeply  grooved  by  the  brachio-radialis  (supinator  longus), 
so  that  it  often  looks  like  a  separate  muscle. 

Nerve-supply. — (1)  From  the  external  cord  of  the  brachial  plexus  (through 
the  sixtli  cer\'ical  nerve)  by  branches  of  the  musculo-cutaneous  nerve  which  enter 
the  anterior  surface  of  the  muscle  near  the  inner  border  of  its  upper  third;  (2) 
from  the  posterior  cord  of  the  brachial  plexus  (through  the  seventh  cervical  nerve) 
l)y  a  small  filament  from  the  musculo-spiral  nerve  Avhich  enters  the  front  of  that 
l)art  of  the  muscle  which  is  concealed  by  the  origin  of  the  brachio-radialis  (supin- 
ator longus). 

Action. — To  flex  the  ulna.  Like  the  biceps,  it  will  form  a  lever  of  the  third 
order,  but  with  much  mechanical  disadvantage  on  account  of  the  proximity  of  its 
insertion  to  the  axis  of  the  elbow-joint.  There  will  be,  however,  a  proportional 
gain  in  speed  and  range  of  movement. 

Relations. — In  front,  the  deep  fascia  on  the  outer  side  of  the  arm  which 
separates  it  from  the  cephalic  vein,  the  biceps,  coraco-brachialis,  deltoid,  brachio- 
radialis  (supinator  longus),  and  extensor  carpi  radialis  longior,  the  brachial  vessels, 
median  and  musculo-spiral  nerves;  behind,  the  triceps  and  elbow-joint. 

Variations. — The  brachialis  anticus  is  sometimes  divided  into  two  heads  by  a  continuation  of 
the  cleft  between  the  two  pointed  processes  above  mentioned,  or  by  a  separation  of  a  part  of  the 
outer  half  Occasionally  it  gives  oif  muscular  slips  t<i  the  radius  or  the  fascia  of  the  forearm, 
also  to  adjacent  muscles  such  as  the  pronator  teres,  the  brachio-radialis,  and  the  extensor  carpi 
radialis  longior. 

3.  BRACHIO-RADIALIS 

The  l)rachio-radialis  (supinator  longus)  is  described  with  the  radial  group  of 
muscles  (page  321). 


EXTENSORS  OF  THE  FOREARM 

The  extensor  muscles  are  two  in  number — the  triceps  and  the  anconeus. 

1.  TRICEPS 

The  triceps  extensor  cubiti — named  from  its  three  heads  and  its  action  upon 
the  elliow  or  cubitus — forms  a  thick  fusiform  sheet  wrapping  round  the  posterior 
surface  of  the  humerus  in  its  whole  length. 

Origin. — Tlie  long  head  arises  from  the  lower  edge  of  the  glenoid  cavity  and 
the  axillary  border  of  the  scapula  for  one  inch  (2'5  cm.)  below  it. 

The  external  head  arises  (1)  from  the  posterior  surface  of  the  humerus  above 
the  musculo-spiral  groove,  reaching  as  far  up  as  the  base  of  the  greater  tuberosity 
and  the  insertion  of  the  teres  minor;  (2)  from  the  back  of  the  external  inter- 
muscular septum  above  the  jioint  where  it  is  pierced  b}'  the  muscXdo-si)iral  nerve. 


310  THE  MUSCLES 

The  internal  head  arises  (1)  from  the  whole  of  the  posterior  surface  of  the 
humerus  between  the  musculo-spiral  groove  and  the  olecranon  fossa;  (2)  on  the 
inner  side,  from  the  back  of  the  whole  of  the  internal  internuiscular  septum;  (3)  on 
the  outer  side,  from  the  back  of  that  portion  of  the  external  intermuscular  septum 
which  lies  below  the  point  where  it  is  jjierced  by  the  nmsculo-spiral  nerve. 

Insertion, — (1)  The  jtosterior  \rdi't  of  the  upjjcr  svn-face  of  the  olecranon  pro- 
cess; and  (2)  on  either  side  by  aponeuroses  which  are  continuous  with  the  deep 
fascia  on  the  l)ack  of  the  forearm. 

Structure. — The  long  head  forms  a  strong  fusiform  muscular  band,  arising  by 
tendinous  filires  which  blend  with  the  lower  part  of  the  capsule  of  the  shoulder- 
joint.  The  surfaces  of  the  band  at  first  look  inwards  and  outwards.  The  tendon 
of  origin  extends  for  some  distance  further  on  the  inner  than  on  the  outer  surface. 
As  the  nniscular  band  passes  downwards,  it  twists  upon  itself  so  that  what  was  the 
internal  surface  now  becomes  posterior,  and  the  external  surface  becoming  the 
anterior  is  applied  to  the  back  of  the  rest  of  the  muscle.  Upon  this  anterior 
surface  the  common  tendon  of  insertion  begins  as  a  broad  aponeurosis  about  three 
inches  (8  era.)  from  the  scapula,  and  receives  the  fleshy  fibres  of  the  long  head  in 
penniform  fashion  chiefly  upon  its  upper  border  and  posterior  surface.  These 
fleshy  fibres  are  continued  as  a  thick  band  along  the  inner  border  of  this  common 
tendon,  and  terminate  in  a  blunt  point  a  little  below  the  junction  of  the  middle 
and  lower  thirds  of  the  arm. 

The  external  head  arises  by  fleshy  fibres  which  are  inserted  in  penniform 
fashion  into  the  outer  border  of  the  common  aponeurosis.  The  lowest  of  these 
fibres  arise  from  a  tendinous  arch  which  bridges  over  the  musculo-spiral  nerve. 

The  internal  head,  which  is  much  stronger  than  the  outer,  forms  a  thick 
triangular  sheet,  wrapping  round  the  back  of  the  bone,  and  arising  also  from  the 
l»ack  of  the  intermuscular  septa  on  either  side.  The  apex  of  this  triangle  extends 
upwards  along  the  lower  border  of  the  musculo-spiral  groove  to  a  point  just  below 
the  insertion  of  the  teres  major.  Its  fleshy  fibres  pass  downwards  and  somewhat 
backwards  to  the  broad  aponeurosis,  which,  after  receiving  the  fleshy  fibres  from 
the  outer  and  long  heads,  completely  covers  the  whole  of  the  posterior  surface  of 
the  muscle  in  the  lower  third  of  the  arm.  A  few  fleshy  fibres  of  this  head  are  in- 
serted directly  into  the  olecranon  and  the  adjacent  posterior  ligament;  the  slip 
attached  to  the  ligament  is  sometimes  called  the  subanconeus. 

The  insertion  of  the  tendon  into  the  Ijack  part  of  the  upper  surface  of  the  ole- 
cranon is  usually  separated  from  the  adjacent  part  of  the  olecranon  and  the  posterior 
ligament  of  the  elbow-joint  by  a  small  bursa.  That  part  of  the  aponeurotic  contin- 
uation of  the  tendon  which  lies  between  the  olecranon  process  and  the  back  of  the 
external  condyle  is  by  far  the  stronger. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventh  and  eighth  cervical  nerves)  by  means  of  the  musculo-sjnral,  which  supplies 
branches  to  the  long  and  inner  heads  in  the  first  part  of  its  course;  and  numerous 
other  branches  to  the  inner  and  outer  heads  while  passing  through  the  musculo- 
spiral  groove. 

Action. — To  extend  the  elbow-joint,  the  muscle  acting  as  a  lever  of  the  first 
order,  at  a  very  great  mechanical  disadvantage  on  account  of  the  short  distance 
which  intervenes  between  the  olecranon  process  and  the  axis  of  the  elbow-joint ; 
but  at  the  same  time  with  a  great  gain  in  speed  and  range  of  movement.  Hence 
this  muscle  is  the  chief  agent  in  movements  of  the  arm  in  which  great  speed  is 
attained,  such  as  in  throwing  a  stone  or  striking  a  blow.  The  long  head  has  some 
influence  as  an  adductor  of  the  shoulder-joint  ;  it  has  also  a  supplementary  liga- 
mentous aetion  upon  that  joint  similar  to  that  of  the  coraco-brachialis  by  holding 
tlie  head  of  the  humerus  in  close  contact  with  the  glenoid  cavity.  As  it  passes  over 
both  the  shoulder-  and  the  ell)ow-joints,  the  long  head  enables  the  powerful  abduc- 
tors of  the  shoulder  to  exert  a  peculiar  influence  upon  the  extension  of  the  elbow 
joint.  If  it  were  merely  a  passive  ligament,  the  long  head  would  extend  the  elbow 
whenever  the  humerus  was  abducted  by  the  deltoid  muscle.  As,  however,  the  long 
head  contracts  at  the  same  time  with  tlie  deltoid,  we  have  an  apparatus  by  which, 
so  to  speak,  a  double  rapidity  of  extension  is  secured  for  the  elbow-joint.  This 
attachment,  therefore,  of  tlie  long  head  of  the  triceps  to  the  scapula  is  the  chief 


ANCONEUS  311 

cause  of  the  rapid  movements  of  the  lower  end  of  the  forearm  which  are  made  use 
of  in  tin-owing  and  striking. 

Acting  from  below,  the  trice})s  will  extend  the  upper  arm  upon  the  forearm,  as 
in  the  use  of  the  parallel  l)ars,  and  in  many  other  gymnastic  exercises. 

Relations. — The  long  head  lies  behind  the  subscapularis,  teres  major,  and  latis- 
simus  dorsi,  in  front  of  the  teres  minor,  witli  the  dorsalis  scapula  vessels  upon  its 
posterior,  and  the  posterior  circumflex  vessels  and  the  circumflex  nerve  upon  its 
anterior  border.  Lower  down,  the  posterior  surface  of  the  muscle  is  only  separated 
from  the  integuments  by  the  deep  fascia;  in  front  lie  the  brachialis  anticus,  brachio- 
radialis  (supinator  longus),  extensor  carpi  radialis  longior,  and  coraco-brachialis, 
with  the  superior  and  inferior  profunda  vessels  and  the  ulnar  and  musculo-spiral 
nerves.  A  small  bursa  intervenes  between  the  tendon  and  part  of  the  olecranon 
process.     The  muscle  is  also  in  relation  with  the  shoulder-  and  elbow-joints. 

Variations. — The  internal  head  .somethues  arises  as  high  as  the  greater  tuberosity.  An  addi- 
tional slip  is  occasionally  received  from  the  capsule  of  the  shoulder-joint,  the  coracoid  process,  or 
the  tendon  of  the  latissimus  dorsi.  A  sli])  of  muscle  is  frequently  separated  from  the  lower 
border  of  the  internal  head,  and,  passing  from  the  inner  condyle  to  the  olecranon,  bridges  over 
the  ulnar  nerve. 

2.    ANCONEUS 

The  anconeus  is  described  with  the  Muscles  ox  the  Back  of  the  Foeearm 
(page  327). 


MUSCLES  OF  THE  FOREARM 

The  muscles  of  the  forearm  are  enveloped  by  a  strong  deep  fascia  which  is  con- 
tinuous with  that  of  the  upper  arm.  It  is  thickest  upon  the  posterior  aspect,  where 
it  is  attached  to  the  sides  of  the  triangular  posterior  surface  of  the  olecranon,  and  to 
the  Avliole  of  the  posterior  ridge  of  the  ulna.  Below  the  internal  condyle  it  receives 
the  broad  band  of  the  bicipital  fascia;  and  behind,  the  aponeurotic  insertion  of  the 
triceps.  In  the  bend  of  the  elbow  it  is  pierced  by  a  communicating  vein.  On  the 
outer  side  and  back  of  the  forearm  the  deep  fascia  has  numerous  connections  with 
the  longitudinal  ridges  on  the  lower  ends  of  the  radius  and  ulna.  It  also  becomes 
much  thickened  by  the  addition  of  transverse  bands,  so  as  to  form  the  posterior 
annular  ligament,  which  passes  from  the  outer  border  of  the  lower  end  of  the 
radius,  inwards  and  at  the  same  time  a  little  downwards,  to  the  ulnar  border  of  the 
ear})us,  where  it  is  attached  to  the  inner  sides  of  the  pisiform  and  cuneiform  bones. 
On  its  anterior  surface  this  ligament  is  attached  to  the  ridges  upon  the  back  of  the 
lower  extremity  of  the  radius,  and  so  forms  canals  through  which  pass  the  tendons 
of  the  long  muscles  upon  the  radial  border  and  posterior  surface  of  the  forearm. 
The  ligament  is  also  in  contact  with  the  lower  end  of  the  ulna,  which  it  binds  in  its 
place,  much  in  the  same  manner  as  the  head  of  the  radius  is  held  in  position  by 
means  of  the  orbicular  ligament,  but  it  has  no  insertion  into  this  bone. 

In  the  front  of  the  Avrist  the  deep  fascia  forms  a  thin  layer,  which  overlies  the 
anterior  annular  ligament.  The  latter  is  sometimes  described  as  a  thickening  of 
the  same  fascia,  but  really  it  is  continuous  with  a  thin  aponeurosis  which  separates 
the  first  and  second  layers  of  the  muscles  of  the  forearm  shortly  to  be  described. 
It  is  a  strong  band  of  fibrous  tissue,  which  stretches  transversely  from  the  pisiform 
l)one  and  unciform  process  on  the  ulnar  side  of  the  carpus  to  the  scaphoid  and  the 
trapezium  on  the  radial  side. 


MUSCLES  OF  THE  FRONT  OF  THE  FOREARM 

The  muscles  upon  the  front  of  the  forearm  form  four  planes  or  layers:  the  first 
two  layers  having  their  origins  from  the  front  of  the  internal  condyle;  the  last  two 
from  the  liones  of  the  forearm  alone. 


312 


THE  MUSCLES 


First  Layer 

The  first  layer  consists  of  four  muscles — the  pronator  radii  teres,  flexor  car})i 
radialis,  pahnaris  longus,  and  flexor  carpi  ulnaris — which  all  arise  by  a  common 


Fig.  272. — Fkoxt  of  the  Foreakm  :  First  Layer  of  Muscles. 


Triceps 


Brachialis  anticus 


Pronator  radii  teres 


Flexor  carpi  radialis 


Palmaris  longus 


Flexor  carpi  ulnaris 


Flexor  sublimis  digitorum 


Biceps 


Brachio-radialis 


-    Flexor  longus  pollicis 


tendon  froin  the  front  of  tlie  internal  condyle,  and  by  separate  attachments  from 
tlie  deep  fascia  of  tlie  forearm  and  the  intermuscular"  septa;  Avhile  the  innermost 
and  outermost  have  additional  ori<>ins  from  the  ulna. 


PRONATOR  RADII  TERES— FLEXOR   CARPI  RADIALIS  313 


1.  PRONATOR  RADII  TERES 

The  pronator  radii  teres — named  from  its  aetion  and  somewhat  cylindrical 
shape — is  a  thick  rihljon-shaped  muscle. 

Origin. — First  head  :  (1)  by  the  common  tendon  from  the  front  of  the  internal 
condyle;  and  (2j  from  the  lowest  part  of  the  internal  condylar  ridge;  (3)  from  tlie 
deep  fascia  covering  it,  and  the  internmscular  septum  which  separates  it  from  the 
flexor  carpi  radialis  and  the  flexor  sublimis  digitorum. 

Second  head :  from  the  inner  border  of  the  coronoid  process. 

Insertion, — The  rough  impression  on  the  middle  of  the  outer  surface  of  the 
radius. 

Structure. — The  higher  of  the  two  heads,  which  is  much  the  larger,  arises 
partly  l)y  a  short  tendon,  and  partly  by  muscular  filn-es,  and  is  separated  from  the 
lower  head  by  a  small  tendinous  arch  through  which  passes  the  median  nerve. 
The  lower  head,  which  lies  concealed  by  the  rest  of  the  muscle,  arises  by  a  small 
aponeurotic  band.  The  thick  fleshy  muscle  passes  obliquely  doAvnwards  and  out- 
wards across  the  front  of  the  forearm.  Below  the  middle  of  its  anterior  surface 
begins  the  tendon  of  insertion,  which  expands  and  covers  the  whole  of  the  muscle 
for  a  short  distance  before  it  is  inserted  by  a  strong  fibrous  band  into  the  special 
impression  for  it  upon  the  most  prominent  portion  of  the  outward  curve  of  the 
raclius. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus 
(through  the  sixth  cervical  nerve)  by  means  of  filaments  derived  from  the  median 
nerve  just  before  it  passes  through  the  arch  between  the  two  heads.  These  fila- 
ments enter  the  muscle  at  its  deep  surface  a  short  distance  above  the  middle  of  its 
outer  border. 

Action. — (1)  To  pronate  the  forearm.  In  supination,  the  tendon  is  to  some 
extent  wrapi)ed  round  the  radius,  as  the  tendon  of  the  biceps  is  in  pronation.  In 
contraction,  the  muscle  so  to  speak,  unwraps  itself  and  so  causes  the  radius  to 
revolve  around  the  axis,  which  passes  through  the  middle  of  its  head  and  the  lower 
end  of  the  ulna.  Its  insertion  into  the  convexity  of  the  curve  of  the  radius  places 
the  line  of  the  muscle  as  far  as  possible  from  this  axis,  and  so  gives  it  some 
mechanical  advantage.  On  the  other  hand,  the  obliquity  of  its  insertion  diminishes 
the  power  of  the  muscle,  and  is  one  of  the  causes  which  make  pronation  a  more 
feeble  movement  than  supination.  (2)  It  will  also  assist  in  the  flexion  of  the 
forearm. 

Relations. — Superficially,  the  bicipital  and  deep  fasciae  and  superficial  veins, 
the  radial  vessels  and  nerve,  and,  lower  down,  the  brachio-radialis  (supinator 
longus)  and  radial  extensors.  Deeply,  the  brachialis  anticus,  flexor  sublimis  digi- 
torum, supinator  brevis,  and  the  median  nerve.  By  its  outer  border,  it  forms  the 
inner  boundary  of  the  space  at  the  bend  of  the  elbow,  and  by  its  inner  border  it  is 
in  contact  with  the  flexor  carpi  radialis. 

Variations. — The  pronator  radii  teres  frequently  extends  at  its  origin  for  some  distance  further 
up  the  internal  condylar  ridge.  It  may  also  receive  a  separate  head  from  the  internal  inter- 
muscular septum,  the  inner  border  of  the  humerus,  or  an  abnormal  supracondylar  process  ;  some- 
times also  from  the  biceps  or  brachialis  anticus.  This  third  head  bridges  over  the  brachial  artery 
and  median  nerve. 

2.  FLEXOR  CARPI  RADIALIS 

The  flexor  carpi  radialis — named  from  its  action  as  a  flexor  of  the  wrist  and 
its  position  on  the  radial  side  of  the  joint — is  flat  and  fusiform. 

Origin. — (1)  The  common  tendon  from  the  front  of  the  internal  condyle;  (2) 
the  deep  fascia  and  the  intermuscular  sejita  whicli  lie  Ix'tween  the  muscle  and  the 
])ronator  radii  teres,  the  flexor  sublimis  digitorum,  and  the  palmaris  longus. 

Insertion. — The  front  of  the  Ijase  of  the  second  metacarpal  bone;  and  usually 
by  a  smaller  slip  into  that  of  the  third  as  well. 

Structure. — Its  fleshy  fibres  are  contained  in  an  ajioneurotic  case  which  forms 
an  elongated  four-sided  pyramid,  the  apex  lieing  at  the  internal  condyle,  and  the 


314  THE  MUSCLES 

sides  consisting  of  the  deep  fascia  and  the  intevninscular  septa  which  intervene 
between  it  and  the  adjacent  muscles.  The  fleshy  tilires  converge  downAvards  and 
somewliat  outwards  ujion  the  back  of  the  tendon  which  begins  at  the  junction  of 
the  upper  and  middle  thirds  of  the  forearm,  and  is  free  a  little  below  the  middle 
of  the  forearm. 

At  tlie  wrist  the  tendon  ixisses  througli  a  special  compartment  external  to  the 
tube  formed  l)y  the  anterior  annular  ligament.  This  compartment  is  bounded 
Itehind  l)y  the  scaphoid  bone  and  the  groove  upon  the  trapezium;  externally,  by 
the  tul)erosity  of  the  scaphoid  ])one  and  the  ridge  upon  the  trapezium;  and  in  front 
and  internally  by  a  thickening  of  the  deep  fascia  of  the  forearm.  It  is  lined  by  a 
special  synovial  membrane. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus 
(through  the  sixth  cervical  nerve)  by  filaments  from  the  median  nerve  which  pass 
to  its  posterior  surface  in  its  upper  third. 

Action. — (1)  To  flex  the  wrist.  By  its  insertion  into  the  metacarpus  it  bends 
not  only  the  radio-carpal  joint  (which  is  the  wrist-joint  proper),  but  also  the  inter- 
carpal and  the  carpo-metacarpal  joints,  which  really  take  part  in  all  the  movements 
of  what  may  be  called  the  irrist  as  distinguished  from  the  vrist-joint.  (2)  ^^"hen 
the  hand  is  fully  supinated,  it  helps  in  pronation.  (3)  It  is  also  a  feeble  flexor  of 
the  elbow. 

Relations. — Superficially,  the  deep  fascia  and  the  superficial  veins;  deeply,  the 
flexor  sublimis  digitorum,  the  flexor  longus  pollicis,  the  median  nerve,  the  wrist 
and  some  of  the  carpal  joints;  on  the  outer  side  of  it  lie  the  pronator  radii  teres  and 
the  radial  vessels;  on  the  inner  side  it  is  in  contact  above  with  the  palmaris  longus. 

Variations. — The  flexor  carpi  radialis  may  have  a  second  origin  fi'om  the  tendon  of  the  biceps 
or  the  radius,  and  its  insertion  may  be  extended  to  the  base  of  the  fourth  metacarpal  bone  or  to 
some  of  the  bones  of  the  carpus.     It  is  sometimes  absent. 


3.  PALMARIS  LOXGUS 

The  palmaris  longus — named  from  its  length  and  its  insertion  upon  the  palm 
of  the  hand — is  flat  and  fusiform. 

Origin. — (1)  The  common  tendon  from  the  front  of  the  internal  condyle;  (2) 
the  deep  fascia  of  the  forearm;  and  (3)  the  septa  which  lie  lietween  the  muscle  and 
the  flexor  carpi  radialis,  the  flexor  carpi  ulnaris,  and  the  flexor  sul)limis  digitorum. 

Insertion. — (1)  The  upper  end  of  the  strong  central  portion  of  the  palmar 
fascia;  (2)  the  lower  pai"t  of  the  front  of  the  anterior  annular  ligament;  and  (3) 
the  deep  fascia  covering  the  thenar  eminence. 

Structure. — Like  the  preceding  muscle  it  consists  of  flesh}^  fibres  which  rise  in 
a  long  four-sided  pyramid  from  the  aponeurotic  case  formed  by  the  deep  fascia  and 
the  intermuscular  septa.  Its  tendon  appears  first  upon  the  anterior  surface  of  the 
muscle  at  the  junction  of  the  middle  and  upper  thirds  of  the  forearm,  and  is  free 
about  the  middle  of  the  forearm.  It  passes  almost  directly  downwards  to  the 
middle  of  the  wrist,  where  it  descends  in  front  of  the  upper  part  of  the  anterior 
annular  ligament,  and  then  becomes  attached  to  its  lower  edge  as  well  as  the 
adjacent  fascite. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus 
(through  the  eighth  cervical  nerve)  by  filaments  from  the  median  nerve  which  enter 
the  deep  surface  of  the  muscle. 

Action. — (1)  To  flex  the  wrist;  (2)  to  a  slight  extent  to  flex  the  elbow  also; 
(3)  it  makes  tense  the  central  portion  of  the  palmar  fascia,  so  that  when  an  object 
is  grasped  finnly  by  the  fingers  no  injurious  pressure  is  exerted  upon  the  important 
vessels  and  nerves  which  lie  beneath  that  structure;  (4)  its  attachments  to  the  fascia 
of  the  thenar  eminence  gives  a  firm  origin  to  some  of  the  short  muscles  of  the 
thumi). 

Relations. — Superficially,  the  deep  fascia  and  sui)erficial  veins;  dee])ly.  the 
flexor  sublimis  digitorum  and  median  nerve,  and  the  upi)er  part  of  the  anterior 
annular  liirament. 


FLEXOR  SUBLIMIS  DIGITORUM  315 

Variations. — The  palmaris  longus  is  very  variable.  It  may  be  double,  and  it  is  often  absent. 
The  fleshy  belly  is  suiuetimes  below,  and  the  tendon  in  part  or  entirely  above.  It  may  take  an 
additional  head  fmrn  the  radius  or  the  onronoid  proces-s.  Its  insertion  may  be  into  the  fascia  of 
the  forearm,  the  flexor  carpi  ulnaris,  tlie  short  muscles  of  the  little  finger,  or  one  of  the  carpal 
bones. 

4.  FLEXOR  CARPI  ULXARIS 

The  flexor  carpi  ulnaris — named  from  its  influence  upon  the  wrist  and  its 
position — is  a  thick  sheet  of  muscular  fibre,  somewhat  fusiform  in  shape,  which 
wraps  round  the  convex  ulnar  border  of  the  forearm. 

Origin. — First  head:  (1)  by  the  common  tendon  from  the  lower  part  of  the 
front  of  the  internal  condyle;  (2)  the  deep  fascia  of  the  forearm;  and  (3)  the  septa 
which  intervene  between  the  muscle  and  the  palmaris  longus  and  flexor  sublimis 
digitorum. 

The  second  head :  from  the  inner  surface  of  the  olecranon  process,  and  the 
upper  two-thirds  of  the  posterior  border  of  the  ulna. 

Insertion. — The  upper  surface  of  the  pisiform  bone,  beyond  which  fibres  are 
continued  to  the  unciform  process  and  the  front  of  the  base  of  the  fifth  metacarpal 
l)one. 

Structure. — The  origin  of  the  upper  head  is  tendinous,  and  that  of  the  lower  is 
partly  fleshy,  partly  aponeurotic;  the  aponeurosis  from  the  posterior  ridge  of  the 
ulna  being  common  to  it  with  the  flexor  profundus  digitorum  and  the  extensor  carpi 
ulnaris,  and  being  closely  blended  with  the  deep  fascia  of  the  back  of  the  forearm. 
The  two  heads  are  united  by  a  fibrous  arch  under  which  passes  the  ulnar  ners'e. 
From  this  tendinous  and  bony  origin  the  fleshy  fibres  pass  doAvnwards  and  forwards 
in  a  penniform  manner  to  be  inserted  into  the  posterior  aspect  of  a  tendon  which 
appears  on  the  front  of  the  muscle  a  little  above  the  middle  of  the  foreann,  and 
becomes  free  just  above  the  wrist-joint,  where  it  lies  superficial  and  internal  to  the 
anterior  annular  ligament. 

Nerve-supply. — From  the  inner  cord  of  the  brachial  plexus  (through  the 
eighth  cervical  and  first  thoracic  nerves)  by  filaments  from  the  ulnar  nerve  which 
enter  the  deep  surface  of  the  muscle  above  the  middle  of  the  forearm. 

Action. — (1)  To  flex  the  wrist.  The  pisifonn  bone  assists  this  action  by  lifting 
the  line  of  the  tendon  a  little  from  the  metacarpal  bone,  much  as  the  patella  assists 
the  quadriceps  femoris.  (2)  It  assists  somewhat  feebly  in  adduction  of  the  wrist. 
(3)  It  helps  in  the  flexion  of  the  elbow. 

Relations. — Superficially,  the  deep  fascia  and  superficial  veins;  deeply,  the 
flexor  sublimis  and  profundus  digitorum,  the  ulnar  vessels  and  nerve.  At  the 
elbow  the  posterior  ulnar  recurrent  artery  with  the  ulnar  nerve  passes  between  the 
two  heads  of  this  muscle.  Near  the  wrist  the  ulnar  artery  lies  along  the  outer 
border  of  the  tendon. 

Variations. — Its  insertion  sometimes  extends  to  the  anterior  annular  ligament,  and  occasionally 
it  sends  a  sHp  to  the  base  of  the  fourth  metacarpal  bone. 


Second  Layer 
The  second  layer  consists  of  one  muscle — the  flexor  sublimis  digitorum. 

FLEXOR  SUBLIMLS  DIGITORUM 

The  flexor  sublimis  digitorum — named  from  its  action  as  a  flexor  of  the  fin- 
gers, and  from  its  position  in  relation  to  the  deep  flexor  {mhlin^ix  ^  superficial) — 
is  a  fusiform  sheet,  with  two  heads  above,  and  dividing  into  four  tendons  below. 

Origin. — The  first  head  arises  from  d)  the  front  of  the  intemal  condyle  by 
the  common  tendon;  (2)  the  intermuscular  septum  which  separates  it  from  the 
muscles  of  the  first  sheet;  (3)  the  internal  lateral  ligament;  and  (4)  a  tubercle  at 
the  upper  part  of  the  inner  border  of  the  coronoid  process  of  the  ulna. 


316 


THE  MUSCLES 


The  second  head  arises  from  the  ol)li(iiie  line  on  the  anterior  surface  of  the 
radius. 

Insertion. — By  four  tendons  into  the  middle  of  the  sides  of  the  second  pha- 
langes of  the  four  fingers. 

Structure. — The  first  head  arises  by  short  tendinous  fibres  from  the  humerus 

Fig.  273. — Front  of  thk  Foreakm  :  Second  Layer  of  Muscles. 


Biceps 
Trioepa 


Muscles  of  first  layer 
BracUialis  antieus 


Flexor  sublimls  digitorum 


Fiercer  carpi  ulnaris 


Flexor  carpi  radialia 
Falmaris  lougus 


B  rachio-radialis 


Extensor  carpi  radialis  longior 


Supinator  brevis 


Brachio-radialis 
Flexor  longus  poUicis 

Extensor  ossis  metacarpi  polUcis 
Extensor  brevis  pollicis 


and  ulna,  and  from  tlic  ligament  between  them.  The  second  head,  -which  is  much 
smaller,  by  fleshy  iibres  which  form  a  thin  sheet  covering  a  ]iart  of  the  flexor  longus 
pollicis.  ik'tween  these  two  heads  the  median  nerve  and  the  ulnar  artery  are  placed. 
Converging  from  tliese  two  heads,  the  flesliv  flbres  occu]\y  almost  the  whole  breadth 
of  the  forearm,  but  soon  divide  into  a  superflcial  and  deep  plane.    From  the  former, 


FLEXOR  SUBLIMIS  DIGITORUM 


317 


which  contains  the  radial  head  and  the  more  superficial  fihres  of  the  first  head, 
the  tendons  to  the  middle  and  xm\£.  fingers  are  derived.  The  tendon  to  the  middle 
finger  receives  the  greater  part  of  tlie  radial  head  in  penniform  fashion,  becoming 
free  close  to  the  anterior  annular  ligament.  That  to  the  ring  finger  separates  high 
up,  and  is  soon  free  from  lleshy  filjres.  The  deeper  plane  of  the  muscle  is  crossed 
by  a  strong  tendinous  intersection  soon  after  its  origin  from  the  first  head.  It  then 
gives  off  a  fleshy  band  to  join  that  part  of  the  superficial  plane  which  goes  to  the 
ring  finger,  and  afterwards  bifurcates  to  form  the  tendons  for  the  index  and  little 
fingers.  I  am  indebted  to  Professor  Thane  for  calling  my  attention  to  this  arrange- 
ment. Beneath  the  anterior  annular  ligament  the  tendons  of  the  superficial  plane, 
viz.  those  going  to  the  middle  and  ring  fingers,  lie  in  front  of  the  other  two  tendons. 
Here  they  are  invested  by  the  synovial  sheath  or  great  palmar  bursa.,  which  is  com- 
mon to  them  and  the  other  tendons  which  pass  through  this  space,  and  which 


Fig.  274. — Diagram  of  the  Great  Palmar  Bursa. 


Ulnar  portion  of  palmar  bursa 
Kadial  portion  of  palmar  bursa 


Anterior  annular  ligament 


liumbricalis 


Deep  transverse 
ligament 


Superficial  transverse  ligament 


extends  from  a  short  distance  above  the  wrist-joint  to  about  tlie  middle  of  the 
palm.  At  the  heads  of  the  metacarpal  Ijones  the  tendons  enter  the  vaginal  sheaths 
of  the  flexors  of  the  fingers,  and  each  tendon  becomes  concave  behind  to  correspond 
with  the  convexity  of  the  tendon  of  the  deep  flexor  upon  which  it  now  rests.  At 
the  middle  of  the  first  phalanx  the  tendon  splits,  and  the  halves  sej)arate  to  allow 
the  passage  of  the  tendon  of  the  flexor  profundus.  The  tAvo  halves  again  unite 
opposite  the  base  of  the  second  phalanx  in  such  a  way  that  the  i)arts  now  in  con- 
tact are  a  direct  continuation  of  what  were  before  the  borders  of  the  tendon;  while 
the  parts  of  the  tendon  which  correspond  to  its  mesial  line  above  are  now  most 
widely  separated  (see  fig.  2S0).  After  a  contact  of  about  a  quarter  of  an  inch  ('6 
cm. ),  the  halves  of  the  tendon  again  separate  in  order  to  be  attached  to  the  sides  of 
the  shaft  of  the  second  phalanx. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus  (through 


318  THE  MUSCLES 

the  seventh  and  eighth  cervical  and  first  thoracic  nerves)  bv  branches  from  the 
median  nerve  which  enter  the  deej)  surface  of  the  muscle  at  its  upper  part. 

Action. — To  fiex  the  second  })halanges  of  the  four  fingers.  Being  inserted  very 
oV)H(iuely,  it  acts  under  a  consideral^le  mechanical  disadvantage,  Init  at  the  same 
time  tlie  speed  and  range  of  movement  corresjionding  to  a  slight  contraction  of  the 
nuiscle  are  very  great.  The  size  of  the  angle  -which  it  makes  Avith  the  shaft  of  the 
phalanx  at  its  point  of  insertion  is  somewhat  increased  by  the  raising  of  its  tendon 
from  the  i)ahnar  aspect  of  the  first  i)halanx  l:)y  the  tendon  of  the  deep  flexor. 
After  Ijending  the  second  phahmx  of  the  finger,  it  will  bend  also  the  metacarpo- 
phalangeal joint;  then  the  three  joints  which  together  produce  flexion  of  the  wrist; 
itnd  finally  it  will  feebly  assist  in  the  flexion  of  the  elbow-joint. 

Relations. — Superficially,  the  four  muscles  of  the  first  sheet  and  the  radial 
vessels  and  nerves;  deeply,  the  flexor  longus  pollicis,  flexor  profundus  digitorum, 
and  pronator  quadratus,the  ulnar  artery  and  veins,  and  the  median  nerve.  In  the 
hand,  it  lies  beneath  the  anterior  annular  ligament,  the  palmar  fascia,  and  the 
superficial  palmar  arch,  and  ujion  the  tendons  of  the  flexor  profundus  digitorum 
with  the  lumbricales. 

Variations. — The  flexor  sublimis  digitorum  varies  very  little  in  its  origin.  It  has  been  seen 
to  arise  partly  from  the  pronator  radii  teres.  Occasiouall}'  its  tendon  to  the  little  finger  fails,  and 
the  place  of  this  tendon  may  be  taken  by  a  lumbriealis  or  a  special  slip  from  the  flexor  profundus. 
Sometimes  accessory  heads  join  the  tendons  in  the  hand  from  the  flexor  proi'undus  or  the  annular 
ligament. 

Third  Layer 

The  third  layer  consists  of  two  muscles — the  flexor  profundus  digitorum  and  the 
flexor  longus  pollicis — which  arise  from  the  ulna  and  radius  respectively. 


1.    FLEXOR  PROFUNDUS  DIGITORUM 

The  flexor  profundus  digitorum — named  from  its  action  upon  the  fingers  and 
Its  relation  to  their  superficial  flexor — is  a  strong  fusiform  sheet  of  muscular  fibres 
Avhich  Avraps  round  the  anterior  and  inner  surfaces  of  the  ulna,  and  divides  below 
into  four  tendons  for  the  fingers. 

Origin. — (1)  The  upper  three-fourths  of  the  anterior  surface  of  the  ulna;  and 
(2)  the  adjacent  part  of  the  interosseous  membrane;  (3)  the  upper  two-thirds  of 
the  inner  surface  of  the  ulna;  and  (4)  the  posterior  ridge  of  that  bone  by  the  apo- 
neurosis common  to  it,  the  flexor  car})i  ulnaris,  and  the  extensor  carpi  ulnaris. 

Insertion. — The  front  of  the  bases  of  the  third  phalanges  of  the  four  fingers. 

Structure. — Arising  directly  from  the  bones  and  fibrous  structures  which  form 
the  origin  of  the  muscle,  the  fleshy  fibres  converge  below  upon  the  back  of  four 
tendons,  w^hich,  appearing  about  the  middle  of  the  forearm,  become  free  at  the 
upper  border  of  the  anterior  annular  ligament.  That  part  of  the  muscle  which  is 
inserted  into  the  index  finger  is  separable  from  the  rest  of  the  muscle  in  nearly  the 
whole  of  its  extent;  the  part  to  the  little  finger  is  also  generally  more  separalde  than 
that  to  the  other  two  fingers.  As  they  pass  lieneath  the  anterior  annular  ligament, 
the  tendons  are  invested  l)v  the  common  synovial  sheath.  At  the  metacarpo- 
phalangeal joints  they  enter  the  vaginal  sheaths  belonging  to  their  respective 
fingers.  <  )iip<»site  the  first  phalangeal  joint  each  tendon  i)asscs  through  the  open- 
ing formed  by  the  si)litting  of  the  flexor  sublimis  tendon;  and  on  the  palmar  aspect 
of  the  second  i)halanx  it  passes  over  a  slight  elevation  formed  by  the  union  of  the 
two  halves  of  the  companion  tendon  before  they  are  inserted  into  the  sides  of  the 
second  phalanx.  The  deep  tendon  finally  ])asses  over  the  second  ])halangeal  joint, 
to  be  inserted  into  the  front  of  the  base  of  the  third  phalanx.  In  the  pahn  of  the 
hand  the  lumbricales  (which  will  afterwards  bi>  described)  arise  from  the  tendons 
of  the  flexor  ])rnfnndus. 

Nerve-supply. — By  two  sources  from  the  l)rachial  ])lexus  (through  the  eighth 
cervical  and  first  thoracic  nerves): — (1)  By  the  anterior  interosseous  branch  of 
the  median  nerve,  which  sends  a  filament  to"  the  portion  of  the  muscle  belonging 


FLEXOR  PROFUNDUS  DIG  I  TO  RUM 


319 


to  the  index  finger,  and  part  if  not  all  of  that  l)elonging  to  the  middle  finger  ui)on 
the  radial  border  of  its  anterior  surface,  about  the  middle  of  the  forearm.      (2)  By 
the  ulnar  nerve,  which  distriliutes  l)ranches  to  the  rest  of  the  muscle  near  the  inner 
border  of  tlie  sui)erficial  aspect  of  the  muscle  in  the  ui)per  part  of  the  forearm. 
Action. — It  is  a  powerful  fiexor  of  the  third  phalanges  of  the  fingers.     As  with 


Fig.  275. — Front  of  the  Fokkakm  :  Third  Layer  of  Mu.scles. 


Biceps 


Muscles  of  the  flrst  and  second 
layers 


Flexor  profundus  digltorum 


Pronator  quadratus 


Flexor  carpi  ulnaris 


Brachio-radialis 


Brachialis  anticus 


Extensor  carpi  radialis  lougior 
Supinator  brevis 


Flexor  longus  pollicis 


Brachio-radialis 


Extensor  ossia  metacarpi  pollicis 


Estensor  brevis  pollicis 


the  superficial  fiexor,  the  extreme  obliquity  of  the  insertion  of  the  tendons  gives 
great  speed  and  range  of  movement,  but  "increases  the  mechanical  disadvantage 
with  which  this  muscle  (being  a  representative  of  the  third  order  of  lever)  must 
act.  The  slight  elevation  formed  by  the  union  of  the  two  halves  of  each  tendon  of 
the  flexor  sublimis  upon  the  second   phalanx  diminishes  to  a  small  extent  the 


320  THE  MUSCLES 

extreme  obliquity  of  itj^  insertion.     Aftt-r  liending  the  third  phalanx,  the  muscle 
will  assist  in  the  Hexion  of  the  other  })halanf!;es  and  the  wrist. 

Relations. — Superticially,  the  flexor  sublimis  digitorum  and  flexor  carpi 
ulnaris,  the  ulnar  vessels,  the  median  and  ulnar  nerves;  deeply,  the  pronator  quad- 
ratus  and  wrist-joint.  In  the  hand,  it  lies  beneath  the  tendons  of  the  flexor  sub- 
limis digitorum  and  the  luml^ricales,  and  upon  the  adductor  of  the  thumb,  the 
interossei  muscles,  and  the  deep  palmar  arch. 

Variations. — The  flexor  profundus  digitorum  frequentlj'  receives,  like  the  flexor  longus 
pollie-is,  a  slip  from  the  superficial  muscles  of  the  forearm.  Sometimes  the  part  which  goes  to 
the  index  finger  may  take  part  of  its  origin  from  the  radius;  and  occasionallj' slips  may  pass  from 
the  flexor  profundus  to  the  flexor  longus  pollicis,  or  vice  versa.  A  slip  has  been  observed  to  end 
in  the  synovial  membrane  of  the  palmar  bursa. 


2.  FLEXOR  LONGUS  POLLICIS 

The  flexor  longus  pollicis — named  from  its  action  upon  the  thumb  and  its 
length  as  compared  with  the  short  muscles  of  the  ball  of  the  thumb — is  a  fusiform 
sheet. 

Origin. — (1)  The  anterior  surface  of  the  radius  below  the  oblique  line,  with  the 
exception  of  the  last  two  inches  (5  cm.)  of  the  surface;  and  the  adjacent  surface 
of  the  interosseous  membrane.  (2)  A  second  head  arises  from  the  inner  border 
of  the  coronoid  process  of  the  ulna,  but  occasionally  it  may  come  from  the  internal 
condyle  of  the  humerus. 

Insertion. — The  front  of  the  base  of  the  last  phalanx  of  the  thumb. 

Structure. — A  penniform  muscle  arising  fleshy  from  the  bone  and  the  inter- 
osseous membrane.  The  tendon  first  appears  upon  the  anterior  surface  near  its 
ulnar  border  about  the  middle  of  the  forearai.  It  receives  the  fleshy  fibres  upon 
its  outer  border  and  posterior  surface  and  becomes  free  at  the  level  of  the  wrist- 
joint,  where  it  enters  the  canal  formed  by  the  anterior  annular  ligament  and  the 
front  of  the  carpus.  It  is  here  invested  by  a  special  compartment  of  the  great 
synovial  bursa,  and  this  compartment  is  continuous  with  the  synovial  sheath  of 
the  tendon  as  it  lies  in  the  thumb.  After  entering  the  palm  of  the  hand,  the 
tendon  passes  beneath  the  outer  head  of  the  flexor  brevis  pollicis,  then  through  the 
groove  formed  by  the  two  sesamoid  bones  which  belong  to  the  tendons  of  this 
muscle,  and  after  lying  in  close  contact  with  the  concave  palmar  surface  of  the  first 
phalanx  of  the  thumb,  it  is  inserted  into  the  front  of  the  base  of  the  second 
phalanx. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus 
(through  the  eighth  cervical  and  first  thoracic  nerves)  by  means  of  the  anterior 
interosseous  Ijranch  of  the  median  nerve,  which  sends  filaments  to  it  upon  its 
anterior  surface  near  its  ulnar  border  about  the  middle  of  the  forearm. 

Action. — It  is  a  powerful  flexor  of  the  last  phalanx  of  the  thumb.  It  Avill  also 
flex  its  metacar})o-phalangeal  joint,  and  afterwards  it  will  assist  the  other  flexors  of 
the  wrist. 

As  the  bones  of  the  thumb  are  not  in  the  same  plane  with  those  of  the  fingers, 
but  rotated  so  that  their  palmar  surface  looks  towards  the  rest  of  the  hand,  their 
flexion  will  be  accompanied  by  adduction;  as  when  the  thumb  meets  the  other 
fingers  in  ])icking  up  any  small  object,  or  in  grasping  anything  between  the  fingers 
and  thunil). 

Relations. — Su]K'rficially,  the  flexor  sublimis  digitorum,  flexor  carpi  radialis, 
bracliio-radialis  (supinator  longus),  and  the  radial  vessels;  deeply  the  jironator 
(piadratus  and  wrist-joint.  In  the  hand,  after  passing  beneath  the  anterior  annular 
ligament,  it  is  covered  l>y  the  o])])onens  pollicis  and  the  outer  head  of  the  flexor 
brevis  pollicis,  and  it  lit-s  on  the  inner  head  of  the  flexor  brevis  pollicis. 

Variations.— Besides  the  communication  with  the  flexor  profundus  digitonim,  we  occasionally 
find  shps  passing  from  the  tendon  of  tlie  flexor  longus  i)olhcis  to  join  the  first  lumbricalis  muscle. 
The  second  head  may  be  absent,  as  in  fig.  275. 


PRONATOR   QUADRATUS—BRACHIO-RADIALIS  321 

Fourth  Layer 

The  fourth  layer  consists  of  one  muscle — the  pronator  quadratus. 

PRONATOR  QUADRATUS 

The  pronator  quadratus  (fig.  284)  is  a  thin  quadrilateral  sheet,  named  from 
its  action  and  its  nearly  square  shape. 

Origin. — The  inner  part  of  the  front  surface  of  the  lower  fourth  of  the  ulna. 

Insertion. — The  lower  two  inches  (5  cm.)  or  rather  less  of  the  outer  border 
and  the  anterior  surface  of  the  radius. 

Structure. — The  greater  part  of  the  muscle  consists  of  fleshy  fibres  Avhich  pass 
transversely  between  its  two  attachments.  Its  inner  third,  hoAvever,  is  covered  by 
a  strong  aponeurosis  which  arises  from  the  inner  Ijorder  of  the  ulna.  The  radial 
insertion  is  of  a  somewhat  triangular  shape,  the  outer  side  of  the  triangle  passing 
obliciuely  from  the  interosseous  line  downwards,  and  joining  the  outer  border  of  the 
radius  a  short  distance  from  the  base  of  the  styloid  process;  while  the  inner  side 
corresponds  to  the  interosseous  ridge,  and  the  base  crosses  the  front  of  the  radius 
above  the  attachment  of  the  anterior  radio-carpal  ligament. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus 
(through  the  eighth  cervical  and  first  thoracic  nerves)  by  means  of  the  anterior 
interosseous  Ijranch  of  the  median  nerve  which  terminates  by  filaments  which  enter 
the  front  of  the  muscle  near  its  upper  border. 

Action. — By  drawing  the  outer  border  of  the  anterior  surface  of  the  radius 
towards  the  inner  border  of  the  anterior  surface  of  the  ulna,  it  pronates  the  radius 
upon  the  ulna. 

Relations. — Superficially,  the  flexor  longus  pollicis,  the  flexor  carj^i  radialis, 
the  flexor  profundus  digitorum,  and  the  flexor  carpi  ulnaris,  the  radial  artery,  and 
the  ulnar  nerve;  deeply,  the  anterior  interosseous  arter}',  the  interosseous  mem- 
brane, and  the  inferior  radio-ulnar  joint. 

Variations. — The  pronator  quadratus  is  sometimes  absent.  It  sometimes  gives  off  slips  to  the 
scaplioid  or  trapezium,  the  base  of  the  first  metacarpal  bone,  or  to  the  origins  of  the  short  thumb 
muscles. 


EADIAL  GROUP  OF  :\IUSCLES 

Along  the  radial  border,  between  the  groups  which  clothe  the  front  and  back  of 
the  forearm,  lie  three  long  muscles,  one  upon  the  other — viz.  the  brachio-radialis 
(or  supinator  longus);  the  extensor  carpi  radialis  longior;  and  the  extensor  carpi 
radialis  brevior. 

1.  BRACHIO-RADIALIS 

• 

The  brachio-radialis,  or  supinator  radii  longus — named  from  its  attachment 
to  the  humerus  and  radius,  and  sometimes  called  the  supinator  longus  from  an 
erroneous  view  of  its  action — is  a  fusiform  sheet. 

Origin, — The  upper  two-thirds  of  the  external  condylar  ridge,  and  the  front  of 
the  external  intermuscular  septum  of  the  upper  arm. 

Insertion. — The  base  of  the  stylf)id  process  of  the  radius. 

Structure. — Arising  by  fleshy  fibres  from  the  septum,  and  by  short  tendinous 
filires  from  the  condylar  ridge,  the  muscle  passes  downwards  and  forwards  in  penni- 
form  fashion  to  its  tendon  which  lies  first  on  its  deep  surface.  Becoming  free  just 
below  the  middle  of  the  forearm,  the  tendon  runs  directly  downwards  and  expands 
before  its  insertion  upon  a  horizontal  line  at  the  base  of  the  styloid  process  of  the 
radius.  At  first  the  plane  of  the  muscle  is  directed  outwards  and  inwards;  but 
lower  down  the  outer  surface  becomes  anterior,  and  the  inner  posterior. 

Nerve-supply, — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
■Ji 


?500 


THE  MUSCLES 


sixth  cervical  nerve),  by  branches  from  the  musculo-spiral  nerve  which  enter  the 
wmn^v  part  of  the  muscle  upon  its  inner  surface. 

Action.— To  Hex  the  forearm.     Its  insertion  at  the  lower  end  of  the  long  arm 


FiCr.  276.— Muscles  of  the  Radial  Side  and  the  Back  of  the  Fokeaem. 


Biceps 

Brachialis  amicus 

Brachio-radialis 


Extensor  carpi  radialis  longior 


Extensor  communis  digltorum 


Extensor  carpi  radialis  brevior 


Extensor  ossis  metaoarpi  pollicis 


Extensor  brevis  pollicis 


Extensor  longus  pollicis 


t —  Triceps 


Flexor  carpi  ulnaris 


Extensor  carpi  ulnaris 


Extensor  minimi  digiti 


formed  l)y  the  radius  makes  it  one  of  the  few  examples  of  the  second  order  of  lever 
when  the  muscle  is  used  to  raise  only  the  weight  of  the  forearm;  but  whatever 
advantage  is  obtained   by  the  position  of   this   insertion   is  lost  by  the  extreme 


EXTENSOR  CARPI  RADIALIS  LOXGIOR—BREVIOR  323 

obliquity  of  the  tendon.  This  ol^hquity  (Introduction,  page  286)  will,  however, 
adfl  s])eed  and  range  of  movement,  and  at  the  same  time  it  will  assist  in  drawing 
the  articular  surfaces  of  the  ell)OAV  together,  and  so  give  strength  to  the  joint. 

If  the  forearm  be  fully  supinated,  the  contraction  of  the  brachio-radialis  will 
cause  some  pronation;  and  it  is  only  when  the  forearm  is  in  the  position  of  full 
pronation  that  it  will  produce  a  slight  supination.  It  is  therefore  incorrect  to 
describe  the  muscle  as  a  supinator. 

Relations. — In  the  up})er  arm,  it  has  at  its  inner  side  the  brachialis  antieus, 
in  which  it  forms  a  deep  groove,  and  the  musculo-spiral  nerve  and  superior  pro- 
funda vessels.  Outside  and  Ijehind  lies  the  inner  head  of  the  triceps.  Below,  it 
rests  on  the  upper  border  of  the  extensor  carpi  radialis  longior.  In  the  forearm  it 
is  covered,  above  by  the  deep  fascia  and  superficial  veins;  below,  by  the  extensor 
ossis  metacarpi  and  the  extensor  brevis  pollicis.  Beneath  it  lie  the  extensor 
carpi  radialis,  longior,  the  supinator  brevis,  the  pronator  radii  teres,  the  flexor 
sublimis  digitorum,  the  flexor  longus  pollicis,  and  the  radial  vessels  and  nerve. 

Variations. — The  bracliio-radialis  is  sometimes  absent.  It  may  receive  a  slip  from  the 
brachialis  antieus.  It  may  give  slips  to  various  parts  of  the  radius,  to  the  carpal  bones  on  the 
radial  side  of  the  hand,  to  the  tendons  of  the  extensor  carpi  radialis  longior,  the  extensor  ossis 
metacarpi  pollicis,  the  flexor  longus  pollicis,  or  to  the  supinator  brevis  muscle. 


2.  EXTEXSOR  CAEPI  RADIALIS  LOXGIOR 

The  extensor  carpi  radialis  longior — named  from  its  action,  position,  and 
length  in  comparison  with  its  fellow  extensor — is  a  narrow  fusiform  sheet. 

Origin. — (1)  The  lower  third  of  the  external  cond3dar  ridge;  (2)  the  front  of 
the  external  intermuscular  septum;  (3)  the  front  of  the  common  tendon  by  which 
the  extensors  at  the  back  of  the  forearm  arise  from  the  external  condyle. 

Insertion. — The  back  of  the  base  of  the  second  metacarpal  bone  near  its  radial 
border. 

Structure. — Arising  by  fleshy  fibres,  this  muscle  has  a  somewhat  penniform 
arrangement.  Its  tendon  is  first  seen"  near  the  outer  l)order  on  the  deep  surface  of 
the  muscle,  and  becomes  free  at  the  junction  of  the  middle  and  upper  thirds  of  the 
forearm.  It  lies  upon  and  in  close  association  with  the  tendon  of  the  short 
extensor,  and  passes  through  the  second  compartment  in  the  posterior  annular 
ligament  to  its  insertion  upon  the  metacarpal  bone.  Its  surfaces,  like  those  of  the 
preceding  muscle,  are  at  first  directed  outwards  and  inAvards,  and  afterwards  for- 
wards and  l)ackwards. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
sixth  cervical  nerve),  by  a  branch  from  the  mvisculo-spiral  nerve  which  enters  the 
muscle  at  the  upper  part  of  its  deep  surface. 

Action. — (1)  To  extend  the  wrist;  including  under  this  appellation  the  carpo- 
metacarpal, intercarpal,  and  radio-carpal  joints.  It  is  also  a  slight  abductor  of 
these  joints.  "When  the  fingers  have  to  be  bent  by  the  long  flexors,  it  steadies  the 
carpus  and  metacarpus  so  as  to  limit  the  action  of  the  flexors  to  the  phalanges. 
(2)  It  has  also  some  influence  in  flexion  of  the  elbow-joint. 

Relations. — In  the  arm,  it  lies  between  the  brachialis  antieus  and  the  triceps, 
and  it  is  covered  by  the  brachio-radialis.  In  the  forearm,  it  overlies  the  short 
radial  extensor  and  wrist-joint,  while  it  lies  beneath  the  brachio-radialis  and  the 
extensors  of  the  thumb. 

Variations. — The  extensor  carpi  radialis  longior  may  be  united  with  the  brevier.  It  may  give 
tendinous  slips  to  the  bases  of  the  first  or  third  metacariml  bones,  or  to  the  trapezium  ;  or  a  slip 
may  join  the  extensor  ossis  metacarpi  pollicis,  or  some  of  the  interossei. 


3.  EXTEXSOR  CARPI  RADIALIS  BREVIOR 

The  extensor  carpi  radialis  brevior — named  for  similar  reasons  to  those  which 
give  its  name  to  the  ])n'ceding  muscU — is  also  flat  and  fusiform. 

Origin. — (1)  The  cimnnon  tendon  attached  to  the  external  condyle;   (2)  the 


324  THE  MUSCLES 

intermuscular  septa  which  separate  it  from  the  origins  of  the  adjacent  muscles;  and 
(3)  the  external  lateral  ligament  of  the  elbow-joint. 

Insertion. — The  back  of  the  bases  of  the  second  and  third  metacarpal  bones 
near  the  Inwvr  part  of  their  line  of  contact. 

Structure. — This  nmscle  is  thicker  than  the  preceding,  and  its  fibres  have  a 
more  decitledly  penniform  arrangement,  as  they  ])ass  from  their  long  fibrous  origin 
ol)liiiuelv  downwards  and  forwards  to  the  tendon  which  appears  first  ui)on  the  inner 
border  of  the  anterior  aspect  of  the  muscle  about  the  middle,  and  is  free  at  the 
junction  of  the  lower  and  middle  thirds  of  the  forearm.  It  passes  through  the 
second  compartment  of  the  posterior  annular  ligament  with  the  tendon  of  the  pre- 
ceding muscle.  The  tendons  of  this  and  the  preceding  muscle  are '  invested  in  a 
synovial  sheath  as  they  pass  through  the  posterior  annular  ligament,  and  a  small 
bursa  lies  Ix^neath  each  of  them  close  to  its  insertion. 

Nerve-supply. — From  the  posterior  cord  of  the  lirachial  plexus  (through  the 
sixth  and  seventh  cervical  nerves)  by  filaments  from  the  posterior  interosseous 
branch  of  the  musculo-spiral  nerve  which  enter  the  upper  part  of  the  anterior 
surface  of  the  muscle. 

Action. — (1)  To  extend  the  wrist;  and  (2)  to  feebly  extend  the  elbow-joint. 

Relations. — It  is  covered  by  the  extensor  carpi  radialis  longiorand  the  tendons 
of  the  three  thumb  extensors.  It  lies  upon  the  supinator  brevis,  the  pronator  radii 
teres,  the  outer  surface  of  the  radius  and  the  wrist- joint. 

Variations. — Its  muscular  portion  may  be  blended  witli  that  of  the  preceding  muscle,  or  slijis 
may  pass  between  the  muscles.  The  tendon  is  often  divided,  and  may  send  separate  insertions 
to  the  second  and  third  metacarpal  bones. 


MUSCLES  OF  THE  BACK  OF  THE  FOREARM 

The  muscles  upon  the  back  of  the  forearm  form  two  lavers:  the  superficial, 
consisting  of  those  arising  from  the  back  of  *the  external  condyle  of  the  humerus; 
and  the  deep  layer,  of  those  which,  with  one  exception,  arise  from  the  bones  of  the 
forearm  only. 

The  superficial  layer  continues  upon  the  back  of  the  forearm  the  series  of  the 
radial  extensors.  It  consists  of  four  muscles:  the  extensor  communis  digitorum; 
the  extensor  minimi  digiti;  the  extensor  carpi  ulnaris;  and  the  anconeus. 


Superficial  Layer 

1.  EXTENSOR  COMMUNIS  DIGITORUM 

The  extensor  communis  digitorum — named  from  its  conmion  action  upon 
the  four  lingers — is  fusiform  and  somewhat  flattened,  and  divides  below  into  four 
tendons. 

Origin. — (l)  The  common  tendon  from  the  lower  part  of  the  external  condyle; 
(2)  the  deep  fascia  of  the  forearm;  and  (3)  the  intermuscular  se})ta  which  separate 
it  from  the  extensor  carpi  radialis  brevior,  the  extensor  minimi  digiti,  and  the 
supinator  brevis. 

Insertion. — (1)  The  lateral  ligaments  of  the  metacarpo-phalangeal  joints  of 
the  four  fingers;  the  back  of  the  bases  of  (2)  the  second,  and  (3)  the  third 
phalanges  of  the  four  fingers. 

Structure. — Arising  from  the  interior  of  tlie  aponeurotic  case  formed  liy  the 
deep  fascia  and  the  internuiscular  septa,  the  fleshy  fibres  soon  break  \\\)  into  se]ia- 
rate  masses,  and  converge  upon  the  four  tendons  which,  beginning  al)Out  the  middle 
of  the  forearm,  l)ecome  free  a  short  distance  above  the  wrist,  and  lie  side  by  side  in 
the  fourth  compartment  of  the  posterior  annular  ligament;  those  for  the  ring  and 
little  fingers  being  more  closely  connected  than  the  others.  After  their  emergence 
at  the  lower  border  of  the  ligament,  the  four  tendons,  which  still  retain  their  flat- 


EXTENSOR   COMMUNIS  DIGITORUM 


325 


tened  cylindrical  shape,  diverge  to  their  respective  fingers.  Opposite  the  heads  of 
tlie  metacarpal  l^ones,  each  tendon  gives  off  fil)rous  bands  to  the  lateral  ligaments 
of  the  corresponding  metacarpo-phalangeal  yAwi.  L'pon  the  first  i)halanx  the  tendon 
expands  into  a  broad  aponeurosis  which  fits  closely  by  its  concave  anterior  surface 


Fig.  277.— Tendons  upon  the  Dokslm  of  the  Hand. 


Extensor  oasis  metacarpi  pollieis 
Extensor  brevia  pollieis 


Posterior  annular  ligament 


Extensor  carpi  radialia  brevior 

Extensor  carpi  radialis  longior 

Extensor  longus  pollieis 

First  dorsal  interosseous 
Adductor  pollieis 


-    Extensor  carpi 
ulnaris 


Extensor  communis 
digitorum 


Extensor  minimi 
digiti 


Extensor  indicia 


Tendon  of  first  dorsal  interosseous 


Attachment  of  extensor  communis 
digitorum  to  second  phalanx 


Attachment  of  extensor  communis 
digitorum  to  third  phalanx 


upon  the  back  of  the  bone  and  affords  attachment  ])y  its  lateral  margins  to  other 
muscles.  After  passing  over  the  back  of  the  first  jdialangeal  j(  )int,  the  central  portion 
of  tliis  aponeurosis  is  inserted  into  the  base  of  the  second  i)halanx,  while  its  lateral 
portions  converge  and,  passing  over  the  second  })halangeal  joint,  are  attached  to  the 
back  of  the  base  of  the  ungual  phalanx.     A  transverse  band  usuallv  unites  the 


326  THE  MUSCLES 

tendons  of  the  index  and  middle  fingers  above  the  heads  of  the  metacarpal  bones. 
A  stronger  band  passes  tlownwards  and  outwards  from  the  ring  finger  tendon  to 
that  of  the  middle  finger  at  the  same  level.  The  fourth  tendon  divides  into  two 
parts.  The  one  joins  with  the  tendon  of  the  ring  finger,  which  immediately  after- 
wards gives  off  a  transverse  band  to  the  extensor  tendon  of  the  little  finger,  and  the 
other  part  joins  the  tendon  of  the  extensor  minimi  digiti  upon  the  metacarpal  bone 
of  the  little  finger. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventh  cervieal  nerve)  by  several  branches  from  the  posterior  interosseous  division  of 
the  musculo-spiral  nerve  which  enter  the  upper  part  of  the  deep  surface  of  the  muscle. 

Action. — (1)  Chiefly  to  extend  the  first  phalanges  of  the  fingers.  (2)  It  has 
some  power  of  extending  the  second  and  third  phalanges;  but  this  part  of  the 
tendon  of  the  muscle  is  chiefly  under  the  control  of  the  lumbricales  and  interossei, 
which  are  attached  to  the  sides  of  the  expansion  covering  the  first  phalanx.  After 
extending  the  fingers,  it  will  also  (3)  help  in  the  extension  of  the  wrist;  and  (4)  to 
a  slight  extent,  of  the  elliow-joint.  The  bands  by  which  the  tendons  are  attached 
to  one  another  upon  the  back  of  the  hand  hinder  independent  extension,  especially 
in  the  ring  finger.  The  little  and  index  fingers,  having  special  extensors,  do  not 
laliour  imder  this  disadvantage. 

Relations. — Superficially,  the  deep  fascia  and  posterior  annular  ligament; 
deeply,  the  supinator  brevis,  the  extensors  of  the  thumb,  the  extensor  indicis,  the 
dorsal  interossei,  the  posterior  and  anterior  interosseous  arteries,  the  posterior  inter- 
osseous nerve,  the  wrist  and  carpal  joints;  on  the  radial  side  is  the  extensor  carpi 
radialis  brevior;  and  on  the  ulnar,  the  extensor  minimi  digiti. 

Variations. — Some  of  the  tendons  may  be  deficient,  or  more  frequently  the  muscle  divides 
into  more  than  four  tendons,  two  or  even  three  of  which  may  be  attached  to  one  finger. 
Occasionally  a  tendon  joins  that  of  the  extensor  longus  poUicis. 


2.  EXTENSOR   MINIMI   DIGITI 

The  extensor  minimi  digiti — named  from  its  action  upon  the  little  finger — is 
small  and  fusiform. 

Origin. — (1)  The  common  tendon  from  the  back  of  the  external  condyle  by  a 
long  fibrous  process;  (2)  the  deep  fascia;  and  (3)  the  intermuscular  septa  which 
intervene  between  it  and  the  adjacent  muscles. 

Insertion. — With  the  corresponding  tendon  of  the  preceding  muscle. 

Structure. — Arising  from  the  interior  of  the  elongated  case  formed  by  the 
various  aponeuroses  which  diverge  from  the  back  of  the  external  condyle,  the 
fleshy  fibres,  which  do  not  begin  till  some  distance  below  that  ])oint,  are  inserted 
into  the  radial  border  of  a  tendon  which  begins  about  the  middle  of  the  forearm, 
and  becomes  free  a  short  distance  above  the  wrist-joint,  a  little  higher  than  that  of 
the  corresponding  part  of  the  preceding  muscle.  Passing  through  the  fifth  com- 
partment of  the  posterior  annular  ligament,  which  lies  upon  the  line  of  junction  of 
the  radius  and  ulna,  the  tendon  reaches  the  back  of  the  fifth  metacarpal  bone,  and 
there  blends  with  the  fourth  tendon  of  the  extensor  communis  digitorum  immedi- 
ately al)ov(;  the  mctacarpo-phalangeal  joint. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventh  cervical  nerve),  by  a  branch  from  the  ])Osterior  interosseous  division  of  the 
musculo-spiral  which  enters  the  deeji  surface  of  the  upper  part  of  the  muscle. 

Action. — (1)  To  extend  the  first  phalanx  of  the  little  finger;  (2)  to  extend  the 
second  and  third  phalanges;  (3)  to  extend  the  wrist;  and  (4)  very  slightly  the 
elbow  also. 

Relations. — Superficially,  the  deep  fascia  of  the  forearm  and  the  posterior 
annular  ligament;  deeply,  the  supinator  brevis,  the  extensors  of  the  thumb,  and 
the  extensor  indicis,  the  inferior  radio-ulnar  joint,  and  the  posterior  interosseous 
artery.  On  the  outer  side  lies  the  extensor  communis  digitorum;  and  on  the 
inner,  the  extensor  carpi  ulnaris. 

Variations. — Tlie  extensor  minimi  digiti  is  rarel}' absent,  but  it  is  sometimes  blended  with 
the  preceding  muscle.     Its  tendon  is  often  divided,  sometimes  into  as  many  as  three  slips. 


EXTENSOR   CARPI   ULNARIS— ANCONEUS  327 


3.    EXTENSOR    CARPI    ULNARIS 

The  extensor  carpi  ulnaris — named  from  its  action  upon  the  carpus  and  its 
position  on  the  uhiar  l)or(ler  of  the  forearm — is  a  fusiform  sheet. 

Origin. — By  two  heads.  The  first  head:  (1)  By  the  common  tendon  from 
the  back  of  the  external  condyle;  (2)  the  front  of  the  deep  fascia  of  the  forearm; 
and  (3_)  the  intermuscular  septa  which  separate  it  from  the  extensor  minimi  digiti, 
the  anconeus,  and  the  supinator  brevis. 

The  second  head  :  from  the  posterior  border  of  the  ulna,  by  the  aponeurosis 
common  to  it,  the  tiexor  carpi  ulnaris,  and  the  flexor  profundus  digitorum. 

Insertion. — The  back  of  the  base  of  the  fifth  metacarpal  bone,  close  to  its 
ulnar  l»onler. 

Structure. — The  fleshy  fibres  converge  below  upon  the  tendon  of  insertion, 
which,  beginning  in  the  interior  of  the  muscle  in  the  middle  of  the  forearm,  soon 
becomes  visible  upon  the  radial  border  of  the  back  of  the  muscle.  It  receives 
fleshy  fibres  in  penniform  fashion  upon  its  ulnar  border  and  deep  surface 
nearly  as  far  as  the  wrist,  where  it  enters  the  sixth  compartment  of  the  posterior 
annular  ligament,  and  lies  in  a  special  groove  to  the  outer  side  of  the  styloid 
process  of  the  ulna. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
eighth  cervical  nerve)  by  branches  from  the  posterior  interosseous  division  of  the 
musculo-spiral  nerve  which  enter  the  deep  surface  of  the  muscle  about  the  middle 
of  the  forearm. 

Action. — (1)  To  extend  the  wrist,  acting  upon  the  three  articulations  involved 
in  this  movement;  (2)  to  adduct  the  wrist,  especially  when  the  hand  is  pronated; 
(3)  it  will  also  help  in  the  extension  of  the  elbow- joint. 

Relations. — Sviperficially,  the  deep  fascia  of  the  forearm,  and  the  posterior 
annular  ligament;  deeply,  the  supinator  brevis,  the  extensors  of  the  thumb,  ex- 
tensor indicis,  posterior  interosseous  artery,  the  inner  half  of  the  posterior  sur- 
face of  the  ulna  below  the  middle  of  the  forearm,  the  wrist,  and  some  carpal 
joints.  On  the  outer  side  lies  the  extensor  minimi  digiti;  on  the  inner,  the 
anconeus  muscle. 

Variations. — Frequently  a  small  slip  of  tendon  passes  downwards  to  join  the  tendon  of  the 
preceding  muscle,  the  first  phalanx,  or  the  head  of  the  metacarpal  bone.  Occasionally  the 
fourth  or  even  the  third  metacarpal  bone  may  receive  a  slip. 


4.     ANCONEUS 

The  anconeus — named  from  its  intimate  relation  with  the  elbow  {ayxu)'^) — is  a 
triangular  fan-sliaped  sheet. 

Origin. — (1 )  The  lower  part  of  the  back  of  the  external  condyle;  and  (2)  the 
adjacent  part  of  the  posterior  ligament  of  the  elbow-joint. 

Insertion. — The  rough  triangular  impression  upon  the  outer  surface  (1)  of  the 
olecranon,  and  (2)  of  the  upper  third  of  the  back  of  the  ulna. 

Structure. — This  muscle  is  a  continuation  downwards  of  the  lower  part  of  the 
inner  liead  of  the  triceps.  Arising  by  a  short  tendon,  which  is  prolonged  upon  the 
deep  surface  of  the  muscle  and  along  its  outer  l)order,  the  fleshy  fibres  diverge  in 
a  fan  shape,  and  are  inserted  either  directly  or  by  short  tendinous  fibres  into  the 
large  special  impression  upon  the  ulna;  the  highest  fibres  being  nearly  horizontal, 
and  the  lowest  ajiproaching  more  nearly  to  a  vertical  direction. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventh  and  eighth  cervical  nerves)  by  a  long  branch  from  the  musculo-spiral 
nerve,  which,  after  passing  through  the  inner  head  of  the  triceps  muscle,  enters 
the  deep  aspect  of  the  anconeus  close  to  its  U})per  border. 

Action. — To  extend  the  elbow,  in  association  with  the  triceps,  of  which  some 
authors  consider  it  to  form  a  fourth  head. 

Relations. — Superficially,  the  deep  fascia  of  the  forearm;  deeply,  the  sujiinator 


328  THE  MUSCLES 

brevis,  the  interosseous  recurrent  artery  wliicli  runs  through  the  deeper  filires  of  the 
muscle,  the  elbow  and  upper  radio-ulnar  joints;  on  its  outer  border,  the  extensor 
carpi  uhxaris. 

Deep    I^ayer 

The  deep  layer  consists  of  five  muscles:  the  supinator  radii  Itrevis;  extensor 
ossis  metacarpi  pollicis;  extensor  l)revis  pollicis;  extensor  longus  pollicis;  and  the 
extensor  indicis.  Four  of  these  arise  from  the  bones  of  the  forearm,  and  one 
only  from  the  humerus  also. 


1.    SUPINATOR    RADII    BREVIS 

The  supinator  radii  brevis — named  from  its  action  and  size  in  comparison 
with  the  brachio-radialis  (=  supinator  longus) — is  a  rhomboidal  sheet  of  muscular 
fibre  curved  upon  itself  into  a  somewhat  cylindrical  shai)e  to  wrap  round  the 
up})er  third  of  the  radius. 

Origin. — (1)  Lower  and  back  part  of  external  condyle;  (2)  the  external 
lateral  ligament  of  the  elbow-joint;  (3)  the  orbicular  ligament;  (4)  the  triangular 
depression  below  the  lesser  sigmoid  cavity  of  the  ulna,  especially  along  its  posterior 
margin,  which  forms  the  upper  part  of  the  external  border  of  the  ulna. 

Insertion. — (1)  The  back  of  the  neck  of  the  radius;  (2)  the  anterior  and 
outer  surfaces  of  the  radius  above  and  at  the  upjjer  border  of  the  oblique 
line. 

Structure. — Its  origin  is  partly  fleshy  and  partly  by  a  strong  aponeurosis  which 
covers  the  upper  half  of  the  muscle  and  gives  attachment  to  some  of  the  muscles  in 
the  superficial  layer.  The  line  of  origin  runs  downwards  and  somewhat  inwards 
from  the  external  condyle  to  the  outer  border  of  the  ulna,  while  that  of  insertion 
runs  downwards  and  outwards  from  the  tul^ercle  of  the  radius  to  the  imjiression 
for  the  pronator  radii  teres. 

Between  these  lines  the  fleshy  fibres  run  in  parallel  curves  Avrapping  round  the 
upper  third  of  the  radius.  The  muscle  is  divided  into  a  small  superficial  and  more 
extensive  deep  plane  by  the  posterior  interosseous  nerve  Avhich  perforates  it  on  its 
way  to  supply  the  muscles  at  the  back  of  the  forearm.  The  line  of  insertion  is 
broken  at  the  tubercle  of  the  radius  l:)y  a  notch  in  which  lies  the  bursa  in  front  of 
the  attachment  of  the  biceps  tendon. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
sixth  cervical  nerve)  by  branches  derived  from  the  posterior  interosseous  division 
of  the  musculo-spiral  nerve,  which  are  given  of?  from  this  nerve  as  it  perforates  the 
muscle. 

Action. — To  supinate  the  radius  upon  the  ulna.  By  its  contraction  the 
muscle  unwraps  itself  from  the  radius;  the  tubercle  of  the  radius  is  drawn  for- 
wards, and  the  outer  border  of  the  bone  backwards;  and  if  the  radius  at  the 
commencement  of  action  be  in  the  position  of  complete  pronation,  it  Avill  be 
caused  by  this  muscle  to  revolve  about  the  axis  which  passes  through  the  centre  of 
its  head  and  the  middle  of  the  lower  extremity  of  the  ulna  through  nearly  1S0°. 

The  action  of  this  muscle  will,  unlike  that  of  the  biceps,  be  unaft'ected  In'  the 
position  of  the  elbow. 

This  completes  the  list  of  muscles  by  which  the  rotation  of  the  radius  upon  the 
ulna  is  effected.  The  biceps  and  supinator  brevis  are  the  su})inators;  the  pronator 
teres  and  (juadratus,  the  pronators.  It  should  be  remembered,  however,  that 
ordinary  pronation  and  supination  are  effected  by  a  more  complicated  movement 
than  simple  rotation  of  the  radius,  which  would  cause  the  hand  to  revolve  around 
the  axis  of  the  little  finger.  The  usual  rotation,  the  axis  of  which  movement 
passes  through  the  line  of  the  middle  finger,  involves  a  slight  flexion  and  extension 
of  the  elbow  with  some  movement  of  the  shoulder-joint. 

Relations. — Superficially,  tlie  l)iceps,  brachio-radialis,  pronator  radii  teres, 
extensor  car])i  radialis  brevior,  extensor  comnu^nis  digitorum,   extensor   minimi 


EXTENSOR  OSSIS  METACARPI  POLLICIS 


329 


digiti,  extensor  carpi  ulnaris,  anconeus,  the  radial  vessels  and  nerve,  the  interos- 
seous recurrent  artery;  deeply,  the  superior  radio-ulnar  joint. 

Variations. — A  second   head  has  been  seen  from  the  humerus  near  the  insertion  of  the 
deltoid,  and  it  may  receive  fibres  from  the  braehio-radialis. 


Fig.  278. — The  Deep  Layer  of  the  Back  of  the  Forearm. 


Supinator  brevis 


Extensor  ossis  metacarpi  poUicis 


Extensor  brevis  pollicis 
Extensor  longus  poUicis 


Hadial  extensors 


Flexor  carpi  ulnaris 


Flexor  profundus  digitoruro 


Extensor  indicis 


—  Extensor  carpi  ulnaris 


2.    EXTENSOR    OSSIS    METACARPI    POLLICIS 

The   extensor   ossis    metacarpi    pollicis,    or   abductor   longus    pollicis— 

named  from   its  action   upon  the   nictacari)al  bone  of  the  thumb — is  a  fusiform 
sheet. 

Origin. — (1)  Tlie  outer  division  of  the  i)osterior  surface  of  the  ulna  for  a  short 
distance  l)elow  the  junction  of  the  upper  and  middle  thirds  of  that  bone;  (2)  the 
adjacent  portion  of  the  interosseous  memlirane;   (3)  the  posterior  surface  of  the 


330  THE  MUSCLES 

radius  near  the  middle  of  that  bone  for  about  two  inches  (5  cm.)  below  the  inser- 
tion of  the  su})inat()r  brevis;  and  (4)  the  septa  which  separate  it  from  the  supinator 
brevis,  extensor  car})i  uhiaris,  and  extensor  longus  pollicis. 

Insertion. — (1 )  The  small  impression  upon  the  radial  side  of  the  base  of  the 
first  metacarpal  bone;  (2)  the  fascia  covering  the  ball  of  the  thumb;  and  frequently 
(3)  the  l^ack  of  the  trapezium. 

Structure. — A  somewhat  bipenniform  muscular  sheet  arising  by  an  origin 
which  stretches  obliquely  downwards  and  outwards  from  the  back  of  the  ulna,  at 
the  upi)er  part  of  its  middle  third,  to  the  middle  of  the  back  of  the  radius.  The 
tendon  ap})ears  first  as  an  aponeurosis  upon  the  anterior  aspect  of  the  muscle  just 
below  the  middle  of  the  forearm.  The  fleshy  fibres  pass  obliquely  downwards  and 
outwards  to  be  inserted  upon  the  posterior  face  of  this  aponeurosis.  This  as  it 
descends  thickens  into  a  rounded  tendon,  which,  becoming  free  from  its  muscular 
fibres  just  above  the  posterior  annular  ligament,  crosses  the  back  of  the  two  radial 
extensor  tendons,  and  enters  the  first  compartment  of  the  posterior  annular  liga- 
ment upon  the  outer  surface  of  the  lower  end  of  the  radius.  After  leaving  this 
compartment,  the  tendon  passes  vertically  downwards,  lying  upon  the  external 
lateral  ligament  of  the  wrist-joint  and  the  radial  artery,  to  be  inserted  into  the  first 
metacarpal  l)one.  From  its  anterior  border  a  strong  aponeurosis  is  given  off  to 
that  part  of  the  palmar  fascia  which  covers  the  ball  of  the  thumb,  and  which 
forms  a  part  of  the  origin  of  the  abductor  pollicis.  Frequently  this  division  of  the 
insertion  is  indicated  by  a  groove  running  up  the  tendon,  or  by  a  more  complete 
separation  which  may  extend  as  high  as  the  fleshy  fibres  of  the  muscle. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventh  cervical  nerve)  by  filaments  derived  from  the  posterior  interosseous 
division  of  the  musculo-spiral  nerve  which  enter  the  muscle  upon  the  upper  part 
of  its  superficial  aspect. 

Action. — (1)  It  abducts  and  extends  the  first  metacarpal  bone,  drawing  the 
thuml^  away  from  the  middle  line  of  the  hand,  and  slightly  forwards.  (2)  It 
abducts  the  wrist.  It  should  be  remembered  that  on  account  of  the  plane  of  the 
thumb  ))eing  different  to  that  of  the  palm  and  fingers,  its  abduction  involves  a 
considerable  forward  movement,  which  must  not  be  confounded  with  flexion. 

Relations. — Superficially,  the  extensor  communis  digitorum,  extensor  minimi 
digiti,  extensor  carj^i  ulnaris,  the  posterior  interosseous  artery,  and  posterior 
annular  ligament;  deeply,  the  extensor  brevis  and  the  extensor  longus  pollicis, 
the  two  radial  extensors,  the  radial  artery,  and  the  wrist-joint. 

Variations. — The  extensor  ossis  metacarpi  pollicis  may  receive  an  accessory  slip  from  the  radial 
group  of  extensors. 

3.  EXTENSOR  BREVIS  POLLICIS 

The  extensor  brevis  pollicis — sometimes  called  the  extensor  primi  inter- 
nodii  pollicis,  from  its  action  upon  the  first  phalanx  (internodius)  of  the  thumb — 
is  flat  and  fusiform. 

Origin. — (1)  The  middle  of  the  posterior  surface  of  the  interosseous  membrane 
just  below  the  preceding  muscle;  (2)  an  elongated  impression  upon  the  inner  part 
of  the  posterior  surface  of  the  radius  extending  from  the  middle  of  that  bone  for 
about  three  inches  (7 '5  cm.)  downwards  and  slightly  outwards;  (3)  an  aponeurosis 
which  s('])arates  it  from  the  preceding  muscle. 

Insertion. — The  back  of  the  base  of  the  first  phalanx  of  the  thumb. 

Structure. — A  pennifonn  muscle  arising  by  short  tendinous  fibres.  These  soon 
become  fleshy,  and  pass  downwards  and  outwards  to  a  tendon  which  begins  in  the 
lower  third  of  the  forearm  upon  the  radial  liorder  of  its  superficial  aspect.  Lying 
beneath  the  tendon  of  the  preceding  muscle  and  in  close  connection  with  it,  this 
tendon  passes  over  the  tendons  of  the  radial  extensors,  runs  through  the  first  com- 
partment of  the  posterior  annular  ligament,  crosses  the  first  metacarpo-phalangeal 
joint  on  the  ulnar  side  of  the  tendon  of  the  ]ireceding  muscle,  and  then  expands  into 
a  broad  aponeurosis  which  is  inserted  into  the  whole  of  the  posterior  surface  of  the 
base  of  the  first  phalanx. 


EXTENSOR  LONG  US  POLLICIS  331 

Nerve-supply. — From  the  posterior  cord  of  tlie  brachial  plexus  (through  the 
seventh  cervical  nerve)  l)y  a  branch  from  the  posterior  interosseous  division  of  the 
musculo-spiral  nerve,  which  enters  the  upper  part  of  the  muscle  on  the  ulnar  border 
of  its  superticial  aspect. 

Action. — It  is  a  feeble  muscle,  the  chief  function  of  which  is  (1 )  to  extend  the 
metacarpo-phalangeal  joint  of  the  thumb;  at  the  same  time  it  will  assist  the  extensor 
ossis  metacarpi  pollicis  in  (2)  abducting  and  extending  the  first  metacarpal  bone; 
and  afterwards  it  will  assist  in  (3)  the  abduction  of  the  wrist. 

Relations. — Superficially,  the  extensor  ossis  metacarpi  pollicis,  extensor  com- 
munis digitorum,  extensor  minimi  digiti,  and  posterior  annular  ligament;  deeply, 
the  radial  extensors,  the  radial  artery,  the  Avrist  and  first  metacarpo-phalangeal 
joints. 

Variations. — The  extensor  brevis  pollicis  may  be  absent,  or  it  may  be  blended  with  the  pre- 
ceding muscle.  It  may  have  insertions  upon  the  metacarpal  bones  or  the  last  phalanx.  An 
accessory  slip  has  been  observed  from  the  external  condylar  ridge  of  the  humeras. 


4.  EXTENSOR  LONGUS  POLLICIS 

The  extensor  longus   pollicis,   or  extensor  secundi  internodii  pollicis — 

named  from  its  action  and  length — is  Hat  and  fusiform. 

Origin. — (1)  An  elongated  impression  upon  the  outer  part  of  the  posterior  sur- 
face of  the  ulna,  extending  from  the  middle  of  that  l^one  for  three  or  four  inches  (7  "5 
to  10  cm.  )  downwards  and  slightly  outwards  close  to  its  external  border.  (2)  The 
adjacent  part  of  the  back  of  the  interosseous  membrane,  and  a  septum  between  it 
and  the  extensor  indicis. 

Insertion. — The  ])ack  of  the  base  of  the  last  phalanx  of  the  thumb. 

Structure. — This  muscle,  which  is  stronger  than  the  preceding,  has  also  a  pen- 
niform  arrangement.  Its  fibres  pass  downwards  and  outwards  from  their  fleshy 
origin  to  be  inserted  into  the  tendon  upon  the  back  of  the  muscle,  which,  appear- 
ing about  two  inches  (5  cm.)  from  its  upper  extremity  near  its  radial  border, 
gradually  thickens  as  it  passes  obliquely  downwards  and  outwards.  Becoming  free 
from  muscular  fibres  at  the  upper  border  of  the  posterior  annular  ligament,  it  enters 
the  deep  groove  which  forms  the  third  compartment  beneath  that  ligament.  At  the 
lower  extremity  of  this  canal  it  crosses  obliquely  the  two  radial  extensor  tendons 
at  the  back  of  the  wrist-joint,  and  upon  the  back  of  the  first  metacarpal  bone  it  lies 
in  close  contact  with  the  inner  border  of  the  tendon  of  the  preceding  muscle,  and 
expands  into  a  flat  and  broad  aponeurosis  which  covers  the  liack  of  the  first  phalanx 
before  its  insertion  into  the  last  phalanx.  Whilst  spread  over  the  convex  surface  of 
the  shaft  of  the  first  phalanx,  it  receives  small  tendinous  insertions  from  the 
abductor  and  adductor  muscles  of  the  ball  of  the  tluiml). 

The  three  tendons  of  the  extensor  muscles  of  the  thumb  enclose  a  triangular 
space  which  is  visible  upon  the  outer  side  of  the  wrist-joint,  and  is  bounded  by  the 
tendons  of  the  extensor  ossis  metacarpi  pollicis  and  the  extensor  brevis  pollicis 
upon  its  radial  side,  by  the  tendon  of  the  extensor  longus  pollicis  upon  its  ulnar 
side,  and  above  by  the  lower  end  of  the  radius.  Across  this  triangle  stretches  the 
radial  artery,  in  its  passage  beneath  the  tendons  from  the  anterior  surface  of  the 
wrist  to  the  upper  part  of  the  back  of  the  first  interosseous  space. 

Nerve -supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventli  cervical  nerve),  l)y  branches  from  the  posterior  interosseous  division  of  the 
musculo-spiral  nerve  which  enter  the  upper  part  of  the  muscle  upon  its  superficial 
aspect. 

Action. — It  is  (1)  a  strong  extensor  of  the  second  phalangeal  joint  of  the 
thumb;  and  afterwards  (2)  of  the  first  phalanx.  It  will  (3)  extend,  and  at  the 
same  time  adduct,  the  first  metacarpal  bone  so  as  to  draw  the  whole  thumb  in 
the  extended  position  backwards,  and  at  the  same  time  inwards.  It  will  also  (4) 
assist  in  the  extension  of  the  wri.st,  and  (5)  in  the  supination  of  the  forearm. 

Relations. — Superficially,  the  extensor  ossis  metacarpi  pollicis,  extensor  com- 
munis digitorum,  extensor  minimi  digiti,  extensor  carpi  ulnaris,  posterior  inter- 
osseous artery,  and  posterior  annular  ligament;  deejily,  the  radial  extensors,  the 


332  THE  MUSCLES 

anterior  interosseous  and  radial  arteries,  wrist,  metacarpo-phalangeal,  and  phalan- 
geal joints. 

Variations. — Tiiis  muscle  may  seiul  a  slip  to  the  base  of  the  first  phalanx  of  the  tliumb.     It 
may  also  receive  a  teudiuous  slip  from  the  following  muscle. 


5.  EXTENSOR  INDICIS 

The  extensor  indicis — named  from  its  action  upon  the  index  finger — is  flat 
and  fusiform. 

Origin. — (1)  An  elongated  impression  -which  stretches  downwards  and  slightly 
outwards  from  the  junction  of  the  middle  and  lower  thirds  of  the  outer  division  of 
the  posterior  surface  of  the  ulna,  inmiediately  internal  to  the  impression  for  the 
preceding  muscle,  but  at  the  same  time  rather  lower  down,  to  within  a  short  dis- 
tance of  the  lower  extremity  of  that  bone.  (2)  For  a  short  space  from  the  part  of 
the  interosseous  ligament  which  is  adjacent  to  the  lower  part  of  this  impression. 
(3)  The  septum  between  it  and  the  preceding  muscle. 

Insertion. — The  inner  side  of  the  aponeurosis  of  the  first  tendon  of  the  extensor 
connnunis  digitorum. 

Structure. — This  penniform  muscle  arises  by  fleshy  fibres  which  pass  oliliquely 
downwards  and  outwards  to  the  anterior  surface  of  a  tendon  which  is  first  seen 
upon  the  radial  border  of  its  posterior  surface  in  the  lower  third  of  the  forearm,  and, 
becoming  free  just  above  the  Avrist,  passes  beneath  the  tendon  of  the  extensor 
minimi  digiti,  and  enters  the  fourth  compartment  of  the  posterior  annular  ligament, 
where  it  lies  beneath  the  inner  tendons  of  the  extensor  communis  digitorum.  It 
is  then  inserted  into  the  inner  edge  of  the  aponeurosis  of  the  tendon  of  the  com- 
mon extensor  belonging  to  the  index  finger,  at  about  the  level  of  the  metacarpo- 
phalangeal joint. 

Nerve-supply. — From  the  posterior  cord  of  the  brachial  plexus  (through  the 
seventh  cervical  nerve),  by  a  branch  from  the  posterior  interosseous  division  of  the 
musculo-spiral  nerve  Avhich  enters  the  upper  part  of  the  muscle  near  the  radial 
border  of  its  superficial  aspect. 

Action. — It  assists  the  extensor  communis  digitorum  in  (1)  extending  the 
index  finger,  and  especially  its  first  phalanx.  At  the  same  time,  on  account  of  its 
direction,  it  Avill  (2)  adduct  the  index  finger,  while  the  action  of  the  extensor 
communis  digitorum  upon  this  finger  is  that  of  extension  combined  with  abduction. 
It  will  then  assist  feebly  in  (3)  the  extension  of  the  Avrist. 

Relations. — Superficially,  the  extensor  communis  digitorum,  the  extensor 
minimi  digiti,  extensor  carpi  ulnaris,  and  posterior  annular  ligament.  Deeply, 
the  dorsal  interosseous  muscle  of  the  second  space,  the  wrist,  and  some  carpal 
joints. 

Variations. — The  extensor  indicis  may  give  slips  to  the  extensor  longus  pollicis  and  to  the 
middle  finger.  It  may  receive  slips  from  the  posterior  carpal  ligaments  or  the  bases  of  the  meta- 
carpal bones,  and  these  slips  may  be  inserted  into  several  digits,  so  as  to  form  an  extensor  brevis 
digitorum  maniis. 


THE  FASCIA  OF  THE  HAND 

The  dorsal  fascia  is  a  thin  layer,  continuous  with  the  posterior  annular  liga- 
ment, and,  like  it,  composed  chiefly  of  transverse  fibres.  It  covers  the  extensor 
tendons,  and  connects  them  together  upon  the  back  of  the  hand;  and  upon  the  first 
phalanges  it  blends  with  the  aponeuroses  which  succeed  to  the  tendr)ns.  Between 
the  fingers  it  di])s  down  to  join  the  superficial  transverse  ligament  which  forms  the 
web  by  which  the  liases  of  the  fingers  are  connected. 

A  deeper  layer  of  the  dorsal  fascia  covers  the  back  of  the  dorsal  interossei,  and 
is  attached  to  the  l)ack  of  the  metacarpal  Ijones. 


THE  PALMAR   FASCIA  333 


THE  PALMAR  FASCIA 

The  palmar  fascia  takes  the  place  of  the  deep  fascia  in  the  palm  of  the  hand, 
and  is  for  tlie  most  part  formed  l^y  the  expansion  of  the  tendon  of  the  palmaris 
longus.  It  is  also  continuous  ■with  the  lower  margin  of  the  anterior  annular  liga- 
ment. It  may  be  divided  into  a  central  and  two  lateral  portions.  The  central 
division,  which  is  by  far  the  strongest,  is  of  a  triangular  shape,  the  apex  being  con- 
tinuous with  the  tendon  of  the  palmaris  longus,  and  also  attached  to  the  lower 
border  of  the  anterior  annular  ligament;  the  base  corresponding  to  the  heads  of  the 
four  inner  metacarpal  bones.  It  consists  in  front  of  longitudinally  arranged  bundles 
of  fibrous  tissue  derived  from  the  palmaris  longus  tendon,  and  behind  of  transverse 
fibres  which  continue  those  of  the  annular  ligament.  Below,  the  fascia  divides  into 
four  ])rocesses  which  join  the  ligamenta  vaginalia  of  the  finger  tendons.  Each  of 
these  four  jDrocesses  forms  a  bridge  across  the  tendons,  and  is  inserted,  at  the  sides 
of  the  metacarpo-phalangeal  joint,  into  the  lateral  and  the  deep  transverse  liga- 
ments. This  strong  central  portion  of  the  palmar  fascia  is  closely  connected  upon 
its  anterior  surface  with  the  skin  by  fibrous  septa,  which  form  small  compartments 
in  wliich  are  lodged  pellets  of  the  subcutaneous  fat.  Upon  its  posterior  surface  it 
is  smooth  and  in  contact  Avith  the  synovial  membrane  of  the  great  laalmar  bursa 
aljove.  and  of  the  thecse  below.  Between  its  four  processes  there  are  three  spaces 
left  tln-ough  which  the  digital  nerves  and  arteries  emerge.  These  are  bridged  over 
l)y  transverse  fibres  which  connect  the  processes,  and  which  form  the  superficial 
transver-se  lifjaments  lying  in  the  weljs  between  the  fingers. 

The  outer  division,  or  thenar  fascia,  is  that  portion  of  the  palmar  fascia  which 
covers  the  ball  of  the  thumb.  It  is  connected  above  with  the  anterior  annular 
ligament,  the  tendon  of  the  palmaris  longus,  and  an  aponeurosis  from  the  tendon 
of  the  extensor  ossis  metacarpi  pollicis.  After  covering  the  short  muscles  of  the 
thumb,  it  is  continuous  below  with  the  ligamentum  vaginale  of  the  flexor  longus 
pollicis  tendon.  The  inner  division,  or  hypothenar  fascia,  is  of  a  triangular 
shape,  the  base  being  above  and  the  apex  below.  Arising  from  the  anterior  annular 
ligament  and  the  deep  fascia  of  the  forearm  at  the  inner  side  of  the  wrist,  it  invests 
the  short  palmar  muscles  peculiar  to  the  little  finger,  and  terminates  upon  the  ulnar 
border  of  the  hand  close  to  the  fifth  metacarpo-phalangeal  joint.  It  is  covered 
above  by  the  palmaris  brevis. 

A  deep  layer  of  fascia  covers  the  front  of  the  interossei  muscles,  and  is  attached 
by  thin  longitudinal  septa  to  the  posterior  surface  of  the  central  part  of  the  palmar 
fascia. 

The  ligamenta  vaginalia  are  strong  bands  of  transverse  fibres  which  are 
attached  to  the  1)orders  of  the  first  and  second  phalanges,  and  serve  to  bind  in  their 
])laces  the  long  flexor  tendons.  Opposite  the  joints  the  ligaments  are  thin,  and 
composed  chiefly  of  obliijuely  decussating  fibres. 

The  sheaths  of  the  flexor  tendons,  or  thecae  as  they  are  called,  are  blind 
tubes  of  synovial  membrane  which  invest  the  back  of  the  ligamenta  vaginalia  and 
the  front  of  the  three  phalanges  and  the  interphalangeal  joints.  They  extend  from 
the  metacarpo-phalangeal  joint  to  the  middle  of  the  last  phalanx;  and  at  the 
extremities  of  the  tube,  the  synovial  membrane  is  reflected  upon  the  surface  of  the 
flexor  tendons.  Small  folds  and  cords  containing  connective  tissue  and  blood-vessels, 
and  invested  by  the  synovial  membrane,  .^tretch  across  the  intervening  space. 
These  are  called  vincula  accessoria  (fig.  279 ).  One  set  of  these,  the  ligamenta 
brevia,  are  of  triangular  shape,  and  pass  directly  forwards  from  the  front  of  the 
lower  })art  of  the  first  and  second  phalanges  to  the  back  of  the  overlying  tendons; 
while  the  other  set — which  are  called  the  ligamenta  longa — are  small  cords  run- 
ning downwards  and  somewhat  forwards  from  the  plialanges  to  the  tendons,  at  a 
higher  level  than  the  ligamenta  brevia.  The  compartment  of  the  palmar  Ijursa 
belonging  to  the  flexor  longus  pollicis  tendon  is  continuous  with  the  theca  of 
the  tliumb.  The  theca  also  of  the  little  finger  is  close  to,  and  frequently  in 
communication  with,  the  lower  part  of  the  great  palmar  bursa  upon  its  ulnar  side 
(fig.  274). 


334 


THE  MUSCLES 


MUSCLES   OF   THE   HAXD 

The  muscles  of  the  hand  proper  consist: — first,  of  a  superficial  one,  which  lies 
upon  the  ])ahnar  fascia;  and,  secondly,  of  a  deeper  set,  which  may  be  divided  into  a 
central  group  l)elonging  to  the  fingers  generally,  and  two  other  groujis.  which  are 
associated  with  the  thumb  on  the  radial,  and  the  little  finger  on  the  ulnar  side  of 
the  palm. 

Superficial  Muscle  of  the  Hand 

PALMARIS  BREVIS 

The  palmaris  brevis  (fig.  280) — named  from  its  position  in  the  palm  of  the 
hand,  and  its  small  size — is  a  small  quadrilateral  sheet. 


Fig.  279.— Diagram  of  a  Vertical  Section  through  the  Middle  of  the  Hand. 


Posterior  annular  ligament 


Deep  transverse  ligament 
Attachment  of  common  extensor 
to  first  phalanx 


Superficial  transverse  ligament 


Vincula  accessoria 


Attachment  of  common  extensor 
to  second  phalanx 


Attachment  of  common  extensor 
to  third  phalanx 


Great  palmar  bursa 


Anterior  annular  ligament 


Dorsal  interosseous 
Lumbriealis 
Palmar  fascia 

Flexor  profundus  digitorum 

Flexor  sublimis  digitorum 


Ligamentum  vaginale 
Vincula  accessoria 


Origin. — f  1)  The  front  of  the  lower  part  of  the  anterior  annular  ligament  about 
its  middle;  and  (2)  the  adjacent  part  of  the  palmar  fascia  at  the  inner  edge  of  its 
great  central  division. 


THE  LUMBRICALES  335 

Insertion. — The  deep  surface  of  the  skin  and  the  sulxaitaneous  fat,  along  the 
nhiar  border  of  the  ui)per  part  of  the  ])ahn. 

Structure. — Arising  l)y  tleshy  and  sliort  tendinous  fi1)res,  tliis  muscle  passes  in 
transverse  fasciculi  to  its  insertion,  which  is  of  a  similar  character  to  its  origin. 
It  belongs  to  that  t3'pe  of  muscle  of  which  the  i)anniculus  carnosus  in  the 
mammalia  is  the  best  example,  and  lies  in  the  subcutaneous  tissue  superficial  to 
the  deep  fascia  like  the  platysma  myoides  and  the  superficial  muscles  of  the  face. 

Nerve-supply. — From  the  inner  cord  of  the  brachial  plexus  (through  the  first 
thoracic  nerve),  by  filaments  from  the  superfi(;ial  division  of  the  ulnar  nerve  which 
enter  the  muscle  upon  its  deep  aspect  near  its  upper  border. 

Action. — It  draws  the  skin  and  the  superficial  fascia  of  the  ulnar  border  of  the 
hand  towards  the  middle  line  of  the  j)ahn,  forming  a  deep  dimple  or  groove  upon 
the  upper  part  of  the  ulnar  border  of  the  hand,  and  at  the  same  time  raising  the 
soft  parts  into  a  prominent  vertical  ridge,  the  object  of  which  appears  to  be  to  pre- 
vent the  ulnar  nerve  and  artery  from  l^eing  pressed  upon  when  a  hard  substance  is 
grasped  by  the  hand.  It  also  helps  to  deepen  the  cup-shaped  hollow  when  the 
palm  is  used  to  conve}^  fluid  to  the  mouth. 

Relations. — Superficially,  the  skin;  deeply,  the  hypothenar  fascia,  which 
separates  it  from  the  abductor  and  flexor  brevis  minimi  digiti,  and  from  the  ulnar 
vessels  and  nerve. 

Variations. — This  muscle  may  be  entirely  absent. 


Deep  Muscles  of  the  Palm  of  the  Hand 

Cexteal  Group 
Consisting  of  two  sets  of  muscles — the  lumbricales  and  the  interossei. 

1.  THE  LUMBRICALES 

The  lumbricales — named  from  their  resemblance  to  earth-worms  (  =Iumhru'i) 
— are  four  small  muscles  of  a  fusiform  shape. 

Origin. — The  two  outer  ones  from  the  outer  side  of  the  first  and  second  tendons 
of  the  flexor  profundus  digitorum;  the  two  inner  from  the  adjacent  sides  of  the 
second  and  third,  and  third  and  fourth  tendons  of  the  flexor  profundus  digitorum 
respectively.  All  four  are  attached  to  the  palmar  aspect  of  the  deep  flexor,  and  the 
origin  begins  at  the  lower  border  of  the  anterior  annular  ligament. 

Insertion. — The  aponeurosis  of  the  extensor  communis  digitorum  tendon  on  the 
radial  side  of  the  first  phalanx  of  each  of  the  four  fingers. 

Structure. — Arising  fleshy  from  the  tendons  of  the  deep  flexor,  the  fibres  con- 
verge upon  a  small  tendon  which  becomes  free  a  short  distance  aljove  the  metacarjjo- 
phalangeal  joint.  The  tendon  passes  in  front  of  the  deep  transverse  metacarpal 
ligament,  below  which  it  expands,  and  is  attached  to  the  border  of  the  extensor 
tendon. 

Nerve-supply. — From  the  outer  and  inner  cords  of  the  Itrachial  plexus;  the 
first  and  second  receiving  small  filaments  from  the  digital  branches  of  the  median 
nerve,  Avhich  enter  the  muscle  near  tlie  radial  Ijorder  in  the  middle  third  of  their 
palmar  aspect.  The  third  and  fourth  lumlnicales  are  supi)lied  by  filaments  of  the 
deep  l)ranch  of  the  ulnar  nerve,  which  enter  their  respective  muscles  in  the  middle 
third  of  their  deep  surfaces. 

Action. — Their  chief  action  Avill  be  (1)  to  flex  the  first  phalanges  upon  the  meta- 
carpal bones;  and  at  the  same  time  (2)  to  extend  the  second  and  third  phalanges 
by  their  traction  upon  the  sides  of  the  extensor  ai)oneurosis  which  covers  the  back 
of  each  of  the  first  phalanges.  In  this  action  they  assist  the  interosseous  muscles; 
but  the  lumbricales  have  this  advantage  over  them,  that  when  the  second  and  third 
phalanges  are  flexed  by  the  flexor  sultlimis  and  ]n-ofundus,  the  lumbricales  will  flex 
the  first  phalanges  with  increased  force,  inasmuch  as  the  tendons  from  which  they 


336 


THE  MUSCLES 


arit^e  have  been  retracterl,  whereas  the  origins  of  the  interossei  are  practically  fixed. 
The  first  and  second  lunii)ricales  will  act  feel)ly  as  abdiuttors  of  the  index  and  middle 
fingers;  the  third  and  fourth  as  adductors  of  the  ring  and  little  fingers.  They  will 
also  have  some  influence,  together  with  the  interossei,  upon  the  aponeuroses  of  the 
extensor  communis   digitorum   tendons   in   binding   them    down   upon   the   first 


Fig.  280. — The  Superficial  Muscles,  of  the  Falsi  of  the  Hand. 


Flexor  carpi  radialis 


carpi  ulnaris 


Deep  fascia  of 
forearm 


£xteusor  ossis  metacarpi  poUicis 


Opponeus  pollicis 


Abductor  pollicis 


Flexor  brevis  pollicis 


Adductor  pollicis 


First  lum- 


First  dorsal 
interos- 
seous 


Flexor  profundus  digitorum 


Flexor  profundus 
digitorum 


phalanges.  In  this  way  they  perform  for  the  dorsal  tendon  a  similar  func-tion 
to  that  which  is  exercised  by  the  ligamentum  vaginale  U}><)n  the  two  ])almar 
tendons. 

Relations. — Superficially,  the  tendons  of  the   flexor  sublimis  digitorum  and 
the  superficial  transverse  ligaments;  deeply,  the  interossei  muscles,  the  adductor 


THE  INTEROSSEI  337 

and  part  of  the  flexor  brevis  pollicis,  and  the  deep  transverse  ligaments;  on  the 
uhiar  ^ide  their  tendons  are  in  contact  with  the  metacarpo-phalangeal  joints. 

Variations. — The  fourth  himbricalis  is  st)metimes  absent.  They  may  vary  iu  their  origins, 
sometimes  arising  from  one,  and  sometimes  from  two  adjacent  tendons.  Occasionally  one  may 
arise  fnjm  the  flexor  longus  poUicis  tendon.  They  may  be  inserted  into  the  ulnar  side  of  a  finger, 
or  into  the  adjacent  sides  of  two  fingers. 


2.  THE  INTEROSSEI 

The  interossei — named  from  their  position  between  the  metacarpal  bones — are 
seven  in  numl)er,  three  being  palmar  and  four  dorsal.  They  are  small  muscles,  of 
penniform  or  bipenniform  structure.     Both  sets  are  easily  exposed  to  view  by  a 

Fig.  281. — The  Palmar  Intekossei. 


deep  dissection  in  the  palm,  but  the  dorsal  set  is  alone  visible  in  the  back  of  tlie 
hand. 

The  three  palmar  interossei  are  fusiform  in  shape. 

Origin. — They  arise  from  the  sides  of  the  metacarpal  bones:  the  first  occupy- 
ing the  whole  of  the  ulnar  side  of  the  second  metacarpal  bone;  the  second,  the 
radial  side  of  the  fourth  metacarpal  bone;  the  third,  the  radial  side  of  the  fifth 
metacar])al  bone. 

Insertion. — By  small  tendons  (1)  into  the  aponeuroses  of  the  extensor  tendons 
U[)(jn  the  back  of  the  first  phalanges  of  the  index,  ring,  and  little  fingers;  and  (2) 
the  adjacent  portion  of  the  side  of  each  first  phalanx  near  to  its  base;  the  first  being 
attached  to  the  ulnar  border,  and  the  second  and  third  to  the  radial  liorders  of  their 
fingers. 

Structure. — Fleshy  fibres  arising  along  the  whole  length  of  the  metacarpal 
bone  are  inserted  in  penniform  fashion  upon  tlie  tendon,  which,  beginning  on  the 
unattached  border  of  the  mu.scle  near  the  middle  of  the  interosseous  space,  becomes 
free  just  above  the  metacari)0-plialangeal  joint,  and  ])asses  beneath  the  deep 
transverse  ligament  which  separates  it  from  the  tendon  of  the  lumbricalis  muscle. 


338  THE  MUSCLES 

At  this  place  a  small  l)iirsa  separates  the  tendon  from  the  deep  transverse  ligament, 
and  the  lateral  ligament  of  the  metacarpo-phalangeal  joint. 

Nerve-supply. — From  the  inner  cord  of  the  brachial  plexus  (through  the 
eighth  cervical  nerve),  by  small  filaments  which,  coming  from  the  deep  branch  of 
the  ulnar  nerve,  pass  into  tiie  upper  part  of  the  muscles  upon  their  anterior  asjject. 

Action  and  relations. — 17(/('  infra. 

Uf  the  four  dorsal  interossei,  the  iirst  forms  a  thick  triangular  sheet,  while  the 
other  three  are  fusiform  and  prismatic. 

Origin. — From  the  five  metacarjKil  bones,  each  muscle  arising  from  the  adjacent 
surfaces  of  the  two  bones  bounding  an  interosseous  space. 

Insertion. — (1)  Into  the  sides  of  the  aponeuroses  of  the  extensor  communis 
digitorum  tendons;  and  (2)  the  adjacent  parts  of  the  first  phalanges. 

Structure. — The  fleshy  fibres  arise  from  the  adjacent  surfaces  of  the  metacarpal 
l)ones  in  liipenniform  fashion,  and  converge  upon  a  tendon  which,  lieginning  about 
the  middle  of   the  interosseous  space,   becomes  free   just  above  the  metacarpo- 

FiG.  282. — The  Dorsal  Interossei. 


l)halangeal  joint,  and  tlien  passes  upon  the  dorsal  aspect  of  the  deep  transverse 
ligament  to  its  insertion  into  the  side  of  the  aponeurosis,  and  into  the  upi)er  part  of 
the  border  of  the  first  i)halanx. 

The  /?r«^  muscle  is  thick  and  ]\v  far  the  strongest,  and  forms  with  the  adductor 
pollicis  the  fleshy  wel)  which  fills  the  interval  between  the  metacarjial  l)ones  of  the 
thumb  and  the  index  finger.  Its  origin  from  the  first  metacarpal  bone  occupies 
the  upper  half  of  that  bone,  while  that  from  the  second  is  more  extensive.  It  is 
inserted  into  the  radial  side  of  the  aponeurosis  upon  the  back  of  the  first  phalanx 
as  well  as  into  the  u})per  part  of  the  outer  border  of  that  bone.  The  second  is 
inserted  into  the  radial  side  of  the  ajxnieurosis  U])on  the  first  ])halanx  of  the  middle 
finger  and  into  the  adjacent  1)one.  The  tJiird  into  the  ulnar  side  of  the  ajxmeurosis 
u]ion  the  back  f)f  the  first  i>lialanx  of  the  middle  finger  and  into  the  adjacent  bone. 
The  fourth  into  the  ulnar  side  of  the  aponeurosis  upon  the  liack  of  the  ring  finger 
and  the  adjacent  l)one.  Of  the  two  heads  of  each  of  these  muscles,  the  one  arising 
from  the  nietacari)al  l)one  of  the  finger  into  which  the  nuiscle  is  inserted,  is  always 
the  larger. 


ABDUCTOR  POLLICrS  339 

Nerve-supply. — From  the  inner  cord  of  the  brachial  pk-xu.s  (through  the 
eighth  cervical  nerve),  by  In-anches  from  the  deep  division  of  the  ulnar  nerve  Avhich 
enter  the  muscles  at  the  ui)])er  part  <^f  their  anterior  aspect. 

Action  of  the  interossei  muscles. — First,  the  common  action  of  all  the  interossei 
is  (1)  to  tlex  the  tirst  })halanges;  and  (2)  to  extend  the  second  and  third.  Their 
power  of  flexion  depends  upon  their  insertion  into  the  sides  of  the  first  phalanges 
as  well  as  the  edges  of  the  aponeuroses  by  which  the  backs  of  these  phalanges  are 
covered.  The  extension  of  the  second  and  third  phalanges  depends  upon  th^  fact 
that  the  portion  of  the  aponeurosis  into  which  each  of  them  is  inserted  is  continued 
downwards  to  the  bases  of  these  phalanges.  A  good  example  of  the  action  of  these 
muscles  and  of  the  lumljricales  is  given  in  the  movements  of  the  fingers  which  hold 
the  pen  in  writing.  In  forming  the  light  upstroke  it  will  be  seen  that  flexion  of 
the  flrst,  accompanies  the  extension  of  the  second  and  third  phalanges.  This 
movement  is  due  to  the  contraction  of  the  lumbricales  and  interossei.  On  the 
other  hand,  the  thick  downstroke  is  formed  b}''  the  extension  of  the  first,  and 
the  flexion  of  the  second  and  third  phalanges;  this  strong  movement  being  due  to  the 
action  of  three  powerful  muscles,  the  extensor  communis,  the  flexor  sublimis,  and 
the  flexor  })rofundus  digitorum.  Secondly,  the  palmar  interossei  adduct  the  index, 
ring,  and  little  fingers  towards  the  middle  line  of  the  hand  which  passes  through  the 
middle  finger.  Thirdly,  the  dorsal  interossei  abduct  the  index,  middle,  and  ring 
fingers  from  the  middle  line  of  the  hand.  As  the  middle  finger  can  be  drawn  either 
to  the  radial  or  ulnar  side  from  the  middle  line  of  the  hand,  it  has  two  dorsal  inter- 
ossei to  abduct  it.  The  first  dorsal  interosseous  muscle  will  also  assist  in  adducting 
the  thumb. 

Relations. — On  the  palmar  surface  of  the  interossei,  separated  from  them  by 
the  deep  layer  of  fascia,  lie  the  flexor  profundus  digitorum  tendons  and  the  lumbri- 
cales, the  adductor  and  part  of  the  short  flexor  of  the  thumb,  the  deep  palmar  arch 
above,  and  the  deep  transverse  ligaments  beloAv;  behind,  lie  the  tendons  of  the 
extensor  communis  digitorum  and  extensor  indicis,  separated  from  the  dorsal  inter- 
ossei by  the  deep  dorsal  fascia. 

Variations. — Sometimes  the  dorsal  interossei  receive  small  accessory  heads  from  the  posterior 
carpal  ligaments,  the  lower  end  of  the  radius,  or  the  adjacent  deep  fascia.  A  jjart  of  the  first 
dorsal  interosseous  has  been  seen  running  separately  from  the  front  of  the  metacari)0-phalangeal 
joint  of  the  thumb  to  the  tendon  of  the  first  lumbricalis.  Occasionally  the  second  dorsal  inter- 
osseous is  inserted  upon  the  ulnar  side  of  the  index  finger,  so  as  to  resemble  the  same  muscle  in 
the  foot. 

Muscles  of  the  Thenar  Eminence 

These  are  four  in  number,  and  they  form  a  fleshy  mass  at  the  radial  border  of 
the  palm,  covered  by  the  thenar  portion  of  the  palmar  fascia,  and  called  the  thenar 
eminence  or  ball  of  the  thumb.  They  are  the  abductor  pollicis,  the  opponens 
pollicis,  the  flexor  brevis  pollicis,  and  the  adductor  i)ollicis. 


1.  ABDUCTOR  POLLICIS 

The  abductor  pollicis — named  from  its  action  upon  the  thuml) — is  a  small 
thick  triangular  sheet. 

Origin. — (1)  The  tuberosity  of  the  scaphoid  Ijone;  (2)  the  upper  ]iart  of  the 
ridge  on  the  trapezium;  (3)  the  outer  part  of  the  front  of  the  anterior  annular 
ligament;  (4)  the  outer  or  thenar  division  of  the  ]ialmar  fascia  by  which  the  ball 
of  the  thumb  is  covered;  and  (5)  the  slip  from  the  tendon  of  the  extensor  ossis 
metacarpi  pollicis  which  joins  this  part  of  the  palmar  fascia. 

Insertion. — (1)  With  the  outer  tendon  of  the  flexor  brevis  pollicis  into  the 
radial  side  of  the  base  of  the  first  ]ihalanx  of  the  thumb;  and  into  (2)  the  outer  edge 
of  the  aponeurosis  of  the  extensor  longus  pollicis  upon  the  back  of  the  first  phalanx. 

Structure. — Arising  1w  fleshy  or  short  tendinous  fibres  from  the  anterior 
annular  ligament  and  some  or  all  of  the  other  four  origins,  the  muscle  converges 
upon  a  short  tendon  which  l)lends  with  the  adjacent  tendon  of  the  fiexor  brevis. 


340 


THE  MUSCLES 


Nerve-supply. — From  the  outer  and  inner  cords  of  the  brachial  plexus  (through 
the  sixth  cervical  nerve),  by  a  branch  from  the  palmar  division  of  the  median 
nerve,  which,  after  passing  under  the  anterior  annular  ligament,  goes  upwards  and 
outwards  to  enter  the  upper  part  of  the  deep  aspect  of  the  muscle  near  its  ulnar 
border. 

Action, — (1)  To  al)duct,  and  (2)  to  flex  the  first  phalanx  of  the  thumb.  As 
the  bones  of  the  thumb  are  in  a  diflferent  plane  to  those  of  the  fingers,  this  move- 
ment will  draw  the  thumb  forwards  and  at  the  same  time  slightly  inwards.     By  its 


Fig.  283.— The  Deeper  Muscles  of  the  Palm  of  the  Haxd. 


Abductor  minim 
digiti 


Flexor  sublimis 
digitorum 


Flexor  brev 
luinirai  dig 


Flexor  profundus 
digitorum 


Extensor  ossis  metacarpi  pollicis 
Flexor  carpi  radialis 
Extensor  brevis  pollicis 

Abductor  pollicis 
Opponens  pollicis 


Abductor 
pollicis 
Flexor  brevis 
pollicis 


insertion  into  the  aponeurosis  of  the  extensor  longus  pollicis,  this  muscle  will  heli) 
(3)  to  extend  the  last  phalanx  of  the  thumb. 

Relations. — Superficially,  the  thenar  fascia,  and  the  superficialis  \o\ve  artery, 
which  usually  perforates  the  muscle;  deeply,  the  outer  head  of  the  flexor  brevis 
pollicis  and  the  oi)})onens  pollicis. 

Variations. — As  already  mentioned,  it  receives  occasional  slips  from  tlie  radial  extensors  of 
the  carpus  and  the  extensor  ossis  metacarpi  polUcis.  It  freriuently  receives  a  thin  muscular  sHp 
from  the  skin  (tvor  the  trapezium  ;  it  may  also  be  supplemented  by  the  opponens  pollicis  or  a  small 
slip  from  the  styloid  process  of  the  radius. 


OPPOXEXS  POLL/CIS  341 


2.  OPPONENS  POLLICIS 

The  opponens  pollicis,  or  flexor  ossis  metacarpi  pollicis,  is  named  from  its 
action,  as  it  lu'lj)s  in  opposing  the  thumb  to  the  other  lingers  and  at  the  same  time 
is  a  liexor  of  tlie  tirst  metacarpal  lione.      It  is  a  short,  thick,  triangular  sheet. 

Origin. — (1)  The  front  of  the  ridge  on  the  trapezium  below  the  preceding;  and 
(2)  the  lower  and  outer  i)art  of  the  front  of  the  anterior  annular  ligament. 

Insertion. — The  whole  of  the  outer  border  of  the  anterior  surface  of  the  shaft 
of  the  tirst  metacarpal  bone. 

Structure. — Arising  ])y  a  short  tendinous  or  fleshy  origin,  the  muscular  fibres 
diverge  fanwise  to  their  insertion.  The  lower  border  of  the  muscle  is  often  so 
blended  with  the  outer  head  of  the  next  muscle  that  the  separation  is  somewhat 
artificial. 

Nerve-supply. — From  the  same  source  as  the  preceding;  the  filaments  enter- 
ing the  anterior  surface  of  the  muscle  near  to  the  upper  part  of  its  ulnar  border. 

Action. — To  flex  the  first  metacarpal  bone,  which  it  draws  forwards  and 
inwards.  This  movement,  on  account  of  the  shape  of  the  carpo-metacari^al  joint, 
is  accompanied  by  a  certain  amount  of  rotation  inwards,  by  which  the  palmar 
asi)ect  of  the  thumb  is  made  to  look  backwards  and  inwards. 

Relations. — Superficially,  the  abductor  pollicis  and  the  thenar  fascia;  deeply, 
and  upon  its  ulnar  border,  the  flexor  brevis  pollicis.  It  also  lies  upon  the  joint 
between  the  metacarpal  bone  and  the  trapezium. 


3.  FLEXOR  BREVIS  POLLICIS 

The  flexor  brevis  pollicis — named  from  its  action  and  short  length  in  compari- 
son with  the  long  flexor — consists  of  two  heads:  each  forming  a  flat  triangular 
sheet. 

Origin. — The  outer  head  arises  from  (1)  the  outer  two-thirds  of  the  lower 
border  of  the  anterior  annular  ligament;  (2)  the  lower  part  of  the  ridge  of  the  trape- 
zium. The  inner  head,  from  (1)  the  front  of  the  os  magnum;  (2)  the  front  of  the 
bases  of  the  first,  second,  and  third  metacarpal  bones;  and  (3)  from  the  front  of  the 
sheath  of  the  flexor  carpi  radialis  tendon. 

Insertion. — The  outer  and  inner  sides  of  the  front  of  the  base  of  the  first 
phalanx  of  the  thumb. 

Structure. — Arising  by  short  tendinous  as  well  as  l)y  fleshy  filn'es,  the  two 
heads  become  tendinous  a  short  distance  above  the  first  metacarpo-phalangeal  joint, 
and  have  imbedded  in  their  suljstance  sesamoid  bones  of  a  somewhat  hemispherical 
shape,  and  about  one-sixth  of  an  inch  (nearly  1  cm. )  in  diameter,  which  rest  by 
small  articular  facets  covered  with  cartilage  upon  the  i)almar  aspect  of  the  condyles 
of  the  first  metacarpal  bone.  Close  to  their  insertion  the  tendinous  fil)res  are 
blended  with  those  of  the  abductor  pollicis  externally,  and  the  adductor  internally. 
In  the  inner  head,  three  distinct  divisions  may  generally  be  observed.  The  Jirst  or 
outermost  division  is  a  small  fusiform  slip  which  passes  beneath  the  tendon  of  the 
flexor  longus  pollicis  to  join  the  outer  head,  and  to  be  inserted  into  the  radial  sesa- 
moid bone.  The  second  divisionis  fan-shaped,  and  its  fibres,  which  form  the  greater 
part  of  the  inner  head,  converge  to  embrace  the  ulnar  sesamoid  bone.  The  third 
division  lies  under  cover  of  the  second.  It  is  a  small  flesliy  slip,  which  arises  from 
the  ulnar  side  of  the  l^ase  of  the  first  metacarpal  l^one,  and  passes  downwards  to  he 
inserted  with  the  adductor  pollicis  into  the  ulnar  side  of  the  base  of  tlie  first  ])ha- 
lanx.  Sonu^  authors  descril)e  this  third  division  as  the  inner  head  of  the  flexor 
brevis  pollicis,  and  the  first  and  second  divisions  as  the  adductor  pollicis 
obliquus. 

Nerve-supply. — The  outer  head  issupjdied  (through  the  sixth  cervical  nerve) 
l)y  the  palmar  Viranch  of  tlie  median,  which  enters  the  middle  of  its  anterior  surface 
near  its  ulnar  border.  The  inner  head  is  supplied  (through  the  eighth  cervical 
nerve)  by  the  deep  liranch  of  the  ulnar  nerve  which  enters  the  upper  part  of  its 
deep  surface  close  to  its  ulnar  border. 


U2 


THE  MUSCLES 


Action. — Both  heads  -will  flex  the  iiietacari)()-]>halanfroal  joint  of  the  thumb. 
The  outer  head  will  flex  also  the  earijo-metacarpal  joint,  while  the  inner  head  will 
be  an  adductor  as  well  as  flexor  of  this  joint.  The  former  will  act  in  association 
with  the  abductor  and  opponens,  and  will  draw  the  thumb  forwards  and  inwards, 
keepinp;  it  at  some  distance  from  the  palm  of  the  hand.  The  latter  will  act  wdth 
the  adductor,  and  draw  it  more  directly  inwards  in  close  proximity  to  the  palm  of 
the  hand. 

Relations. — The  outer  head  lies  beneath  the  abductor  pollicis,  and  in  contact 
by  its  radial  l)orderAvith  the  opponens  pollicis.  The  inner  head  is  partly  separated 
from  it  by  the  tendon  of  the  flexor  longus  pollicis;  upon  its  ulnar  border  it  is  in 


Fig.  284. — The  Pronator  Quadratus  and  Deep  View  of  the  Palm. 


>/" 


Pronator  quadratus 


Abductor  pollicis 


Outer  head  of  flexor 
brevis  pollicis 


Inner  head  of  flexor 

brevis  pollicis  i  flrst 

division) 
Opponens  pollicis 
Inner  head  of  flexor 

brevis  pollicis   third 

division  I 
Inner  head  of  flexor 
brevis  pollicis  (second 
division) 

Adductor  pollicis 


Dorsal  interosseous 


Third  palmar 
interosseous 


Fourth  dorsal 
interosseous 
Second  palmar  interosseo 


Third  dorsal  interosseous 


First  palmar  interosseous 


Second  dorsal  interosseous 


contact  with  the  adductor.  In  front  of  it  lie  the  tendons  of  the  flexor  ]n-ofundus 
with  the  outer  lumbricalcs;  behind,  are  the  third  part  of  the  radial  artery  and  the 
interossei  muscles  of  the  flrst  two  spaces. 


4.  ADDUCTOR  POLLICIS 

The  adductor  pollicis,  sometimes  called  tlie  adductor  pollicis  transversus — 
named  from  its  action — is  a  thick  trianjiular  sheet. 

Origin. — The  front  border  of  the  shaft  of  the  third  metacarpal  bone. 

Insertion. — (1 )  The  inner  side  of  the  base  of  the  first  phalanx  of  the  thumb: 
(2)  the  inner  side  of  the  aponeurosis  of  the  extensor  longus  pollicis  which  covers 
the  first  phalanx. 


FLEXOR  B RE  VIS  MIXIMI  DIGITI  343 

Structure. — Ari^^ing  by  short  tt-ndinous  or  fleshy  fibres,  the  muscle  converges 
upon  a  short  tendon,  ^vhich  blends  on  its  outer  side  with  the  inner  tendon  of  the 
flexor  lirevis  pollieis,  and  sends  a  iibrous  slip  to  the  inner  side  of  the  aponeurosis 
(jf  the  extensor  loiigus  pollieis. 

Nerve-supply. — From  the  lower  cord  of  the  brachial  ])lexus  (through  the 
eighth  cervical  nerve j,  by  the  deep  branch  of  the  ulnar  which  sends  filaments  to 
the  upper  border  and  deep  surface  near  the  origin. 

Action. — (1)  To  flex  the  first  phalanx  of  the  thumVj;  (2)  to  adduct  and  flex 
the  carpo-metacarpal  joint  of  the  thumb;  (oj  to  extend  the  second  phalanx  of  the 
thumb.  This  latter  action  of  the  adductor  and  abductor  pollieis  is  useful  in  many 
of  the  movements  of  the  thumb,  in  which  it  will  be  found  that  the  second  phalanx 
has  to  he  kept  extended,  while  its  palmar  aspect  is  being  opposed  to  the  tijjs  of  the 
other  digits. 

Relations. — Superficially,  some  of  the  tendons  of  the  flexor  profundus  digi- 
torum  and  the  two  outer  lumbricales;  deeply,  the  abductor  indicis  and  the  inter- 
ossei  of  the  space  l»etween  the  second  and  third  metacarpal  bones.  Part  of  the 
lower  border  is  subcutaneous. 

Variations. — The  adductor  pollieis  is  often  difficult  to  separate  from  the  inner  head  of  the 
flexor  brevis  pollieis. 


Muscles  of  the  Hypothexar  Eminence 

These  are  three  in  number — the  abductor  minimi  digiti,  the  opponens  minimi 
digiti,  and  the  flexor  brevis  minimi  digiti.  They  lie  under  cover  of  the  thin 
internal  division  of  the  palmar  fascia. 


1.  ABDUCTOR  MIXIMI  DIGITI 

The  abductor  minimi  digiti — named  from  its  action — is  fusiform  and  some- 
what flattened. 

Origin. — ( 1)  The  lower  half  of  the  pisiform  bone;  (2)  the  continuation  of  the 
tendon  of  the  flexor  carpi  ulnaris  below  this  bone. 

Insertion, — (1)  The  ulnar  side  of  the  base  of  the  first  phalanx  of  the  little 
finger;  and  (2)  the  adjacent  portion  of  the  aponeurosis  of  the  extensor  minimi 
digiti. 

Structure. — Arising  by  short  tendinous  fibres,  it  soon  forms  a  flat  flesh}'  mass 
which  contracts  slightly  below,  and  just  before  its  insertion  having  again  become 
tendinous,  it  is  for  the  most  part  attached  to  the  first  phalanx,  but  it  also  sends  a 
small  slip  backwards  to  the  extensor  aponeurosis. 

Nerve-supply. — From  the  ulnar  nerve  through  the  eighth  cervical  nerve.  It 
receives  small  filaments  at  the  outer  and  deep  aspect,  usually  from  the  deep  palmar 
division  of  the  ulnar  nerve. 

Action. — To  abduct,  and  at  the  same  time  flex,  the  metacarpo-phalangeal  joint 
of  the  little  finger;  it  will  also  assist,  like  an  interosseous  muscle,  in  the  extension 
of  the  second  and  third  phalanges. 

Relations. — Superficially,  the  hypothenar  part  of  the  jxalmar  fascia  and  the 
palmaris  brevis;  deeply,  the  flexor  brevis  and  opponens  minimi  digiti.  Upon  its 
radial  border  are  placed  the  deep  palmar  branches  of  the  ulnar  artery  and  nerve. 

2.  FLEXOR  BREVIS  MIXIMI  DIGITI 

Tlie  flexor  brevis  minimi  digiti — named  from  its  action — is  small  and  fusiform. 

Origin. — (  1)  The  ulnar  surface  of  the  hook  of  the  unciform  bone;  (2)  the 
adjacent  part  of  the  front  of  the  anterior  annular  ligament. 

Insertion. — The  ulnar  side  of  the  base  of  the  first  phalanx  of  the  little  finger. 

Structure. — Its  origin  and  insertion  are  by  short  tendinous  fibres,  and  the  rest 
of  tlie  nuiscle  is  fleshv. 


344  THE  MUSCLES 

Nerve-supply. — Through  the  eighth  cervical  nerve,  from  the  deep  branch  of 
the  uhiar  nerve  which  sends  filaments  to  the  ui)per  part  of  its  deep  and  ulnar 
surface. 

Action. — To  tlex  tlie  first  phalanx  of  the  Httk*  finger. 

Relations. — Superficially,  the  hypothenar  part  of  the  palmar  fascia,  the  lower 
part  of  the  abductor  minimi  digiti,  and  the  superficial  palmar  arch;  deeply,  the 
opponens  minimi  digit!  and  the  fifth  metacarpal  bone;  and  to  its  radial  side  lie 
the  flexor  tendons  of  the  little  finger.  This  muscle  is  closely  connected  with  the 
previous  one,  from  which  it  is  separated  above  by  the  deep  palmar  branches  of 
the  ulnar  artery  and  nerve. 

Variations. — It  may  foil,  or  be  bleuded  with  the  abductor  or  opponens  minimi  digiti.  An 
aecessorj'  slip  may  come  to  it  from  the  lower  third  of  the  ulna  at  its  inner  border,  from  the 
tendon  of  the  flexor  carpi  ulnaris,  or  the  deep  foscia  of  the  forearm. 


3.  OPPONEXS  MINIMI  DIGITI 

The  opponens  minimi  digiti  (=  flexor  ossis  metacarpi  minimi  digiti) — named 
from  its  action — is  a  triangular  fan-shaped  sheet. 

Origin. — (1)  From  the  hook  of  the  unciform  bone  deeper  than  the  preceding; 
(2)  from  the  adjacent  part  of  the  anterior  annular  ligament. 

Insertion. — The  wdiole  of  the  ulnar  border  and  part  of  the  head  of  the  fifth 
metacarpal  bone. 

Structure. — Arising  by  short  tendinous  fibres,  the  fleshy  liundles  diverge  down- 
wards and  outwards,  and  are  inserted  by  short  tendinous  fibres. 

Nerve-supply. — Through  the  eighth  cervical  nerve,  from  the  deep  branch  of 
the  ulnar  nerve  which  sends  filaments  to  the  upper  part  of  its  ulnar  aspect. 

Action. — To  flex  the  fifth  metacarpal  bone,  and  at  the  same  time  slightly  to 
adduct  it.  This  movement  is  observed  Avhen  the  palm  is  cupped,  as  when  the  hand 
is  used  to  lift  water  to  the  mouth. 

Relations. — Superficially,  the  abductor  and  the  flexor  brevis  minimi  digiti; 
and  deeply,  the  interossei  of  the  fourth  interspace,  and  the  deep  branches  of  the 
ulnar  artery  and  nerve. 

Variations. — It  may  receive  a  slip  from  the  deep  fascia  of  the  forearm. 


THE  3IUSCLES  AND  FASCIJE  OF  THE  THIGH 

Superficial  fascia. — The  greater  part  of  this  is  of  loose  adipose  tissue,  and, 
without  any  dee])  connections,  is  continuous  with  the  superficial  fascia  of  the 
al)domen  and  l)ack.  In  the  upper  and  front  part  of  the  thigh  a  deep  layer  of  a 
more  membranous  structure  may  be  distinguished,  and  this  has  deep  connections 
where  the  lower  liml)  joins  the  trunk,  Ijcing  attached  to  the  crest  of  the  ilium  and 
to  the  fascia  lata  just  below  its  insertion  into  Pou])art's  ligament  and  the  rami  of  the 
pubis  and  ischium.  Below  the  inner  half  of  Pou})art's  ligament  several  lymphatic 
glands  are  arranged  longitudinally  lietween  these  two  layers  of  the  superficial  fascia. 

The  deep  fascia  or  fascia  lata  is  a  very  strong  layer  of  fibrous  tissue,  the  fiV)res 
of  which  are  arranged  for  the  most  part  transversely  as  an  aponeurosis  of  invest- 
ment; but  many  of  them,  especially  upon  the  outer  side  where  it  is  much  thicker, 
are  longitudinal,  and  serve  for  the  insertion  of  important  muscles.  The  Avhole  of 
the  deep  fascia  forms  a  strong  cylindrical  tube  investing  all  the  muscles  of  the  thigh. 
It  is  attached  above,  in  the  groin,  to  Poupart's  ligament,  where  it  blends  with  the 


THE  MUSCLES  AXD   FASCIjE   OF  THE   THIGH 


345 


aponeurosis  of  tlie  oxtcvnal  ol)li(jue;  on  the  outer  side  and  Itehind,  to  the  outer  lip 
ot"  the  crest  of  tlie  iUuni,  and  to  the  lower  part  of  the  vertebral  a])oneurosis;  upon 
tiie  inner  side,  to  the  border  of  the  tuberosity  and  ascending  ramus  of  the  ischium, 
to  the  descending  ramus  of  the  pubes,  the  symphysis  pubis,  and  the  anterior  lip  of 
the  crest  of  the  pubes.  Below,  it  becomes  much  thinner,  and  is  continuous  with 
the  deep  fascia  of  the  leg;  it  has  also  a  deep  attachment  to  the  tuberosities  of  the 
tibia  and  the  outer  surface  of  the  head  of  the  fibula.  The  thickening  of  its  outer 
portion,  wliich  passes  down  like  a  tendon  to  the  external  tuberosity  of  the  tilna, 
and  is  also  attached  to  the  outer  side  of  the  ligamentum  patella^,  is  called  the  ilio- 
tibial  band.  From  the  deep  surface  of  this  great  cylindrical  tube  are  given  off 
various  processes  which  assist  in  the  formation  of  the  slieaths  of  some  of  the  more 
superficial  muscles.  There  are  also  three  strong  intermuscular  septa,  which  extend 
from  it  to  the  linea  aspera  in  the  lower  part  of  the  thigh  dividing  the  flexor,  exten- 
sor, and  adductor  groups  of  muscles  from  one  another.  At  the  u])])er  part  of  the 
thigh,  below  the  inner  third  of  Poupart's  ligament,  is  the  saphenous  opening,  for 

Fig.  285. — Obliquus  Exterxus  and  Fascia  Lata. 


Aponeurosis 
of  obliquua 
externus 


'  "i'l\.l.  'W]^ 


\    '  \\A\ 


Loops  of 
cremaster 


W     ! 


V  ,^j,\lMm^ 


External 
abdomiual 
ring 

Saphenous 
opening 


the  passage  of  the  internal  saphenous  vein,  w'hich,  after  running  up  the  thigh  in  the 
su})erficial  fascia,  enters  the  deep  femoral  vein  in  this  situation.  This  opening  is 
not,  as  might  have  been  expected  from  the  character  of  these  oi)enings  in  other 
])arts,  a  mere  circular  foramen.  It  is  formed  by  the  division  of  the  fascia  lata  into 
two  parts,  which  do  not  unite  together  again,  but  are  inserted  separately  along  the 
line  of  attachment  of  the  lower  limb  to  the  trunk.  It  l)egins  below  the  iimer  third 
of  Poupart's  ligament,  and  is  of  a  somewhat  oval  shape,  measuring  about  one  inch 
(2-5  cm.)  from  al)ove  downwards,  and  half  to  three-quarters  of  an  inch  (1'2  to 
2  cm. )  from  side  to  side.  The  lower  liorder  of  the  opening  forms  a  well-defined 
edge  which  occupies  the  angle  Iietween  the  saphenous  and  femoral  veins  close  to 
their  point  of  junction.  Externally,  the  fascia  lata  is  attached  above  along  the 
whole  length  of  Poupart's  ligament,  and  its  free  internal  edge  arches  inwards 
towards  the  spine  of  the  ])ubes  in  front  of  the"  femoral  vein.  This  external  and 
1)road  division  of  the  ui)])er  part  of  the  fascia  lata  is  called  its  iliac  portion,  and 
the  free  edge  which  lies  in  front  of  the  femoral  vessels  is  known  by  the  name  of  the 
falciform  border  nr  process.     Internally,  the  fascia  lata  is  in  close  contact  with 


346  THE  MUSCLES 

the  pectineus  muscle  which  lies  beneath  it,  and  with  that  muscle  it  flips  beneath  the 
femoral  vein  and  the  sheath  of  the  vessels  to  be  attached  to  the  ilio-jiectineal  line. 
This  internal  division  is  called  the  pubic  portion  of  the  fascia  lata.  The  deep 
layer  of  the  superficial  fascia  stretches  across  the  opening,  and  is  firmly  attached  to 
the  edge  of  the  falciform  process.  From  the  numerous  openings  which  give  passage 
to  the  vessels  and  lymphatics,  it  is  here  called  the  cribriform  fascia  {cribrumhemg 
the  Latin  for  a  sieve). 


MUSCLES  OF  THE  FRONT  OF  THE  THIGH 

In  front  of  the  thigh  there  is  a  group  of  four  muscles,  the  chief  function  of  which 
is  to  flex  the  hip-joint.  Two  of  these  muscles  arise  within  the  abdomen,  and  two 
from  the  margin  of  the  innominate  bone.  The  two  Avhich  come  from  within  the 
abdomen  are  the  psoas  and  iliacus,  and  they  act  together  as  one  muscle,  and  have 
been  described  as  such  under  the  name  of  the  ilio-psoas.  The  third  and  fourth  are 
the  sartorius  and  pectineus. 

1.   PSOAS 

The  psoas,  or  psoas  magnus — named  from  the  Greek  word  (}'""■,  meaning  the 
muscles  of  the  loins — is  thick,  rounded,  and  fusiform. 

Origin. — Inner  part,  by  five  processes  which  arise  from  (1)  the  sides  of  the 
intervertebral  cartilages  which  intervene  between  the  bodies  of  the  last  thoracic  and 
the  five  lumbar  vertebme;  and  (2)  the  adjacent  part  of  the  sides  of  the  bodies  of 
these  vertebrse;  and  between  these  processes  from  (3)  tendinous  arches  which  bridge 
over  the  sides  of  the  bodies  of  the  first  four  lumbar  vertebrae.  Outer  part,  from  the 
lower  border  and  the  front  of  the  transverse  processes  of  all  the  luml:»ar  vertebra?. 

Insertion, — The  lower  and  back  part  of  the  lesser  trochanter  of  the  femur. 

Structure. — With  the  exce}>tion  of  the  small  tendinous  arches  which  span  the 
sides  of  each  of  the  four  upper  luml^ar  vertebrae  from  its  upper  to  its  lower  border, 
and  which  give  passage  to  the  lumbar  vessels,  the  whole  origin  of  the  muscle  is 
fleshy.  The  fibres  pass  downwards  and  forwards  in  penniform  fashion,  but  with  a 
slight  convergence,  to  the  inner  side  of  the  tendon,  which,  beginning  in  the  interior 
of  the  muscle  about  the  level  of  the  crest  of  the  ilium,  becomes  free  upon  its  outer 
and  posterior  surface  a  short  distance  above  Poupart's  ligament,  while  upon  its 
inner  surface  it  receives  fibres  down  to  its  insertion.  The  muscle,  having  hitherto 
run  in  a  downward,  forward,  and  slightly  outward  direction,  changes  its  course  at 
Poupart's  ligament,  and  passes  downwards  and  backwards  to  be  attached  to  the 
lesser  trochanter  of  the  femur.  In  its  passage  along  the  brim  of  the  pelvis  and 
over  the  lower  part  of  the  iliac  fossa,  the  tendon  upon  its  outer  aspect  begins  to 
receive  the  insertion  of  the  iliacus  muscle.  Between  the  tendon  and  the  capsule  of 
the  hip-joint  which  is  in  close  connection  with  it,  is  placed  a  bursa  which  frequently 
communicates  through  an  opening  in  the  capsule  with  the  interior  of  the  hip-joint. 

Nerve-supply. — From  the  anterior  primary  branches  of  the  second  and  third 
lumbar  nerves  l)y  filaments  which  are  given  ofi"  from  the  lumliar  plexus  whilst  it  is 
passing  through  the  muscle. 

Action. — The  p.soas  is  a  powerful  flexor  of  the  thigh  upon  the  pelvis,  e.g.  in 
walking,  ruiming,  or  going  upstairs.  The  change  in  the  direction  of  the  tendon 
after  crossing  the  horizontal  ramus  of  the  pubes  makes  its  insertion  nearly  per])en- 
dicular  to  the  axis  of  the  femur.  The  psoas  therefore  acts  with  less  mechanical 
disadvantage  than  is  usual  with  the  muscles  of  the  limbs.  It  has  been  sometimes 
described  as  an  external  rotator  of  the  hip;  and  its  insertion  into  the  lesser 
trochanter  at  the  inner  side  of  the  femur  would  appear  to  favour  this  view.  In 
order  to  determine  whether  it  has  this  action,  it  is  necessary  to  ascertain  whether  the 
line  of  the  tendon  of  the  psoas  lies  internal  or  external  to  the  axis  of  rotation.  This 
axis  may  ])e  found  by  drawing  a  straight  line  fi-om  the  centre  of  the  head  of  the 
fenuir  to  the  centre  of  gravity  of  the  lower  limV),  which,  when. the  knee  is  extended, 
will  be  about  the  middh^  of  the  intercondylar  noteh.  By  reference  to  the  articulated 
skeleton  it  will  be  seen  tliat  on  account  of  the  position  of  the  lesser  trochanter  in 


PSOAS 


347 


the  an.ule  Avhich  exists  1)t't\vi'C'U  the  in'ck  and  shaft  of  the  femur,  the  hne  of  the 
tendon  of  the  psoas  passes  either  through  or  external  to  this  axis.  The  action, 
therefore  of  the  muscle  when  the  knee  is  extended  will  be  either  to  produce  no  rota- 
tion at  all,  or  to  rotate  inwards.  When  the  knee  is  flexed  or  when  the  thigh  is 
In'oken  the  axis  of  rotation  is  altered,  and  in  the  latter  case  the  psoas  may  become 
an  external  rotatf)r.  It  will  follow,  therefore,  that  any  power  of  rotation  exercised 
by  this  muscle  will  be  rather  internal  than  external. 

Acting  from  below,  the  psoas  will  flex  the  lower  thoracic  and  the  luml^ar  spine 
upon  the  pelvis  and  the  pelvis  upon  the  thigh,  as  when  the  body  is  raised  from  the 
reclining  to  the  sitting  position,  or  when  the  trunk  is  bent  forwards  in  rowing. 


Fig.  286. — Psoas,  Iliacus,  axd  Quadeatus  Lumbokum. 


Quadratus  lumborum 


Psoas  parvus 


Psoas  magnus 


—  Intertransversalis 
anterior 


Quadratus  lumborum 


Relations. — The  front  and  inner  surfaces  are  covered  by  the  iliac  fascia,  Avhich 
at  the  upper  part  of  the  muscle  is  thickened,  and  forms  the  ligamentum  arcuatum 
internum  of  tlie  diaphragm.  In  front  lie  also  the  peritoneum,  the  intestines,  the 
kidney,  ureter,  and  the  renal  vessels,  and  the  spermatic  or  ovarian  vessels.  On  the 
outer  side  is  the  iliacus  muscle.  In  the  interior  of  the  muscle  is  the  lumbar  i)lexus, 
the  nerves  from  which  run  for  some  distance  in  its  substance.  On  the  inner  side  lies 
the  external  iliac  artery;  and  behind  is  the  inner  border  of  the  quadratus  lumborum 
and  the  l)rim  of  the  pelvis.  In  the  thigh,  after  passing  beneath  Poupart's  ligament, 
it  is  covered  by  the  femoral  artery,  the  pectineus  lies  along  its  inner  border,  and 
the  capsule  of  the  hip-joint  lies  behind  it,  together  with  the  intervening  bursa. 

Variations.— Souietinies  the  part  of  the  psoas  wliich  arises  from  the  lower  lumbar  vertebrae 
loruis  a  distinct  muscle.     Occasionally  fibres  from  the  psoas  parvus  join  the  psoas  magnus. 


348  THE  MUSCLES 


2.   ILIACUS 

The  iliacus — named  from  its  attaclimeiit  to  the  iUum — is  a  thick,  triangular 
sheet. 

Origin. — (1)  The  ujiper  surface  of  the  ala  of  the  sacrum;  (2)  the  front  of  the 
ilio-lumbar,  lumbo-sacral,  and  anterior  sacro-iliac  hgaments;  (3)  the  upper  and 
outer  half  of  the  venter  of  the  ilium;  (4)  the  origin  of  the  upper  tendon  of  the 
rectus  femoris  and  tlie  ilio-femoral  ligament  near  the  anterior  inferior  spine  of  the 
ilium. 

Insertion. — (1)  The  outer  surface  of  the  tendon  of  the  psoas,  through  which 
it  is  attached  to  the  back  of  the  lesser  trochanter  of  the  femur;  (2)  the  upper  and 
back  part  of  the  shaft  of  the  femur  in  a  line  about  one  inch  (2-5  cm.)  long  leading 
downwards  from  the  lesser  trochanter. 

Structure. — Arising  by  fleshy  fibres,  the  muscle  converges  in  a  fan-shape  down- 
wards and  inwards,  and  its  fil)res  enter  the  outer  surface  of  the  tendon  of  the  psoas 
muscle  from  about  tAvo  inches  (5  cm.)  above  Poupart's  ligament  to  its  insertion. 
The  lowest  fibres  are  also  continued,  still  fleshy,  into  their  insertion  on  the  l)ack 
part  of  the  shaft  of  the  femur. 

Nerve-supply. — From  the  lumbar  plexus  (through  the  second  and  third 
lumbar  nerves)  Ijy  the  anterior  crural  nerve,  which  gives  branches  to  its  anterior 
surface  about  the  middle  of  its  inner  border. 

Action. — Similar  to  that  of  the  psoas,  as  a  flexor  of  the  thigh;  and  acting  from 
the  femur  as  a  fixed  point,  it  will  draw  forwards  and  flex  the  pelvis  upon  the  thigh. 

Relations. — The  iliac  fascia  in  front  separates  it  from  the  peritoneum  and 
intestines.  The  profunda  femoris  artery  and  several  nerves  from  the  luml^ar  plexus 
lie  upon  it.  On  its  inner  side  lies  the  psoas.  After  passing  under  Poupart's 
ligament,  it  is  crossed  by  the  sartorius,  and  behind  lie  the  rectus  femoris  and  the 
capsule  of  the  hip-joint. 

Variations. — A  small  detached  muscle  occasionally  arises  from  the  anterior  inferior  spine,  and 
is  inserted  into  the  lower  part  of  the  anterior  intertrochanteric  line,  or  the  ilio-femoral  ligament. 


Psoas  Parvus 

The  psoas  parvus — a  small  muscle,  only  occasionally  present,  named  from  its  position  in  the 
loins  and  its  small  size — is  fusiform  and  somewhat  flattened. 

Origin. — The  side  of  the  intervertebral  disc  between  the  last  thoracic  and  the  first  lumbar 
vertebra  and  the  adjacent  borders  of  the  bodies  of  these  vertebrae. 

Insertion. — The  ilio-pectineal  line. 

Structure. — Arising  fleshy,  the  fibres  converge  and  are  inserted  in  a  somewhat  jienniform 
manner  into  the  back  and  inner  surface  of  a  tendon  which  appears  about  two  inches  below  the 
origin  of  the  muscle  upon  its  outer  and  anterior  aspect,  and  becomes  free  about  the  level  of  the 
fifth  lumbar  vertebra.  The  tendon,  a  narrow  fibrous  band,  lies  ujwn  the  inner  aspect  of  the  psoas 
niagnus  on  the  brim  of  the  pelvis,  and  expands  at  its  lower  extremity  to  be  attached  along  the 
ilio-jH'ctineal  line  and  the  ilio-pubal  ridge. 

Nerve-supply. — By  small  filaments  from  the  first  nei-ve  of  the  lumbar  plexus. 

Action. — To  flex  the  pelvis  upon  the  thorax;  or,  taking  the  pelvis  as  a  fixed  point,  it  will 
flex  the  lower  i)art  of  the  thoracic  spine  as  well  as  the  lumbar  spine  upon  the  pelvis.  It  is  a 
muscle  which  is  well  developed  in  some  animals,  having  for  its  function  the  drawing  forwards  of 
the  lower  part  of  the  pelvis,  accompanied  by  the  arching  of  the  lumbar  spine  which  is  seen  when 
they  are  running  swiftly. 

Relations.— In  front,  the  iliac  fascia,  peritoneum,  ligamentum  arcuatum  internum,  intestines, 
renal  vessels,  ureter,  external  iliac  vessels,  etc.     Behind  and  externally,  the  psoas  magnus. 


Iliac  Fascia 

Investing  the  abdominal  portion  of  the  ilio-psoas  is  a  strong  membrane,  called 
the  iliac  fascia,  which  is  attached  to  the  crest  of  the  ilium  externally,  and  inter- 
nally to  the  posterior  part  of  the  ilio-pectineal  line  which  forms  the  brim  of  the 
pelvis. 


ILIACUS 


349 


Between  these  attachments  it  invests  the  front  of  the  ihacus  and  psoas  muscles. 
\hove,  it  is  continued  upwards  as  the  covering  of  the  latter  muse  e,  at  the  sides  of 
which  it  is  attached  to  the  transverse  processes  and  l^odies  of  the  lumbar  vertebra, 
as  well  as  to  the  inten-ertebral  discs  and  the  small,  tendinous  arches  which  bridge 
the  side  of  the  bodies  of  these  vertebrae.     At  the  diaphragm  it  is  thickened,  and 

Fig.  287.— Muscles  of  the  Feoxt  of  the  Thigh. 


Adductor  brevis 


Adductor  longus 


Adductor  magBus 


Vastus  internus 


Tendon  of  aartorius 


Gluteus  medius 


Gluteus  minimus 
Tensor  vaginae  femoris 


Kectus  femoris 


Ilio-tibial  band  of  fascia  lata 


Vastus  externus 


Ligamentum  patellae 


forms  the  ligamentum  arcuatum  internum;  near  the  tips  of  ^l^^^transA  er.e  proce..  . 
of  the  lumbar  vertebra^  it  is  attached  to  the  anterior  layer  of  the  lumbar  tasaa 
(pa.e  40S).  Below,  it  joins  beneath  the  outer  half  of  Poupart's  ligament  with  the 
transversalis  fascia,  but  internal  to  this  it  passes  downwards  into  the  ^^^^ 
ing  with  the  transversalis  fascia  the  sheath  of  the  femoral  ves.el..     Still  turtlicr 


350  THE  MUSCLES 

inwards,  it  is  continuous  with  the  })ul)ic  i)ortion  of  the  fascia  lata  which  invests  the 
pectineus  muscle,  and  it  also  sends  backwards  a  septum  between  the  psoas  and  the 
pectineus  which  is  attached  to  the  ilio-pubal  ridge. 


3.  SARTORIUS 

The  sartorius — named  somewhat  erroneously  from  sartor,  a  tailor,  Ijecause  it 
has  been  supposed  to  be  the  muscle  by  which  the  cross-legged  sitting  posture  is 
produced — is  a  long,  ribbon-shaped  muscle  slightly  fusiform  at  the  two  ends. 

Origin. — The  anterior  superior  spine  of  the  ilium  and  the  adjacent  part  of  the 
notch  lu'tween  this  process  and  the  anterior  inferior  spine. 

Insertion. — (1)  The  front  part  of  the  inner  surface  of  the  tibia,  just  internal  to 
the  tubercle;  (2)  the  upper  part  of  the  deep  fascia  covering  the  internal  surface  of 
the  leg. 

Structure. — Arising  by  short  tendinous  fi])res,  the  fleshy  fibres  which  are  the 
longest  in  the  whole  body,  run  parallel  to  one  another  inwards  and  downwards 
across  the  front  of  the  thigh,  and  after  reaching  the  inner  surface  of  the  thigh  a)  )OUt 
the  middle,  the  muscular  band  runs  almost  vertically  downwards  to  the  back  of  the 
internal  condyle  of  the  femur.  At  this  point  the  tendon  of  insertion  makes  its 
appearance  as  an  aponeurosis  which  covers  the  deep  asj^ect  of  the  muscle  and 
becomes  free  from  fleshy  fibres  just  below  the  knee-joint,  where  it  turns  forwards 
and  covers  the  inner  surface  of  the  inner  tuberosity  of  the  tibia,  being  separated 
from  it  as  well  as  from  the  tendons  of  the  gracilis  and  semi-tendinosus  by  a  large 
bursa.  The  upper  border  of  this  aponeurosis  is  thick  and  tendinous  and  is  inserted 
directly  into  the  bone.  The  lower  part  of  the  aponeurosis,  which  is  of  a  much 
more  membranous  character,  is  continued  downwards  and  forwards  and  blends  with 
the  deep  fascia  of  the  inner  side  of  the  leg,  of  which  it  is  one  of  the  chief  con- 
stituents. 

Nerve-supply. — From  the  second,  third,  and  fourth  iDranches  of  the  luml^ar 
plexus,'  by  filaments  which  are  usually  derived  from  the  middle  cutaneous  branch 
of  the  anterior  crural  nerve  as  it  pierces  the  muscle  at  the  junction  of  its  middle  and 
upper  thirds. 

Action. — (1)  To  flex  the  thigh,  and  at  the  same  time  rotate  it  slightly  outwards 
and  abduct  it.  (2)  To  flex  the  knee,  and  when  the  knee  is  in  the  ])ent  position  it 
will  also  help  in  rotating  the  leg  inwards.  (3)  Being  contained  in  the  close-fitting 
sheath  formed  l)v  the  fascia  lata  and  its  deep  processes,  it  will  tend  when  it  con- 
tracts to  draw  the  soft  parts  upon  the  inner  surface  of  the  thigh  forwards,  and  so 
make  tense  the  inner  portion  of  the  fascia  lata.  (4)  Acting  from  below,  it  will  flex 
the  pelvis  upon  the  thigh. 

Relations. — In  front  above  lies  the  fascia  lata;  internally  below  lie  the  fascia 
lata  and  intei-nal  saphenous  vein;  Ijeneath  lie  the  rectus  femoris,  iliacus,  pectineus, 
adductor  longus  and  magnus,  vastus  internus,  and  the  inner  hamstring  tendons,  the 
femoral  vessels,  the  anterior  crural  nerve  and  its  internal  saphenous  and  vastus 
internus  brandies. 

Variations. — The  sartorius  is  occasionally  absent ;  it  may  also  he  divided  longitudinally.  It 
may  have  insertions  into  the  fascia  lata,  or  the  ligamentum  patellae.  A  tendinous  intersection 
sometimes  crosses  the  muscle. 


4.  PECTINEUS 

The  pectineus — named  from  peden  (  =  pubes)  on  account  of  its  origin  from 
that  })on( — is  a  (luadrilateral  sheet. 

Origin. — (1)  The  ilio-pectineal  line  between  the  spine  of  the  pubes  and  the  ilio- 
pul)al  ridge;  (2)  the  surface  in  fn^it  of  the  inner  end  of  this  line;  and  (S)  the  deep 
surface  of  the  pubic  portion  of  the  fascia  lata  close  to  its  attachment  to  the  ilio- 
pectincnl  line. 

Insertion. — The  back  of  the  femur  in  a  vortical  line  about  two  inches  (5  cm.) 
long,  beginning  just  Ijehind  the  lesser  trochanter. 


GLUTEUS  MAXIMUS  351 

Structure. — The  ori<>;in  is  1)v  fleshy  and  tendinous  fil)res  intermingled.  The 
filjres  then  run  i);irallel  to  one  another  to  a  tendinous  insertion  Ijetween  the  iliaeus 
and  the  adductor  brevis.  The  direeti(jn  of  the  surfaces  changes  so  that  that  which 
looks  forwards  ahove  is  directed  outwards  below. 

Nerve-supply. — From  the  lumbar  plexus  (through  the  third  and  fourth 
lumbar  nerves),  by  a  branch  of  the  anterior  crural  nerve,  which,  after  passing 
behind  the  femoral  artery  and  vein,  enters  the  muscle  aljout  the  middle  of  its 
external  border.  \Mien  there  is  an  accessory  obturator  nerve,  it  passes  over  the 
brim  of  tlie  pelvis  to  supply  this  muscle  at  the  upper  part  of  its  anterior  surface. 
Occasionally  the  muscle  receives  a  branch  upon  its  deep  surface  from  the  anterior 
division  of  the  obturator  nerve. 

Action. — To  flex  and  at  the  same  time  adduct  the  thigh;  as,  for  example,  in 
crossing  the  legs,  when  one  thigh  is  brought  forwards  and  inwards  to  place  it  in 
front  of  the  other  thigh.  It  is  also  a  slight  external  rotator.  Its  predominant 
action  is  that  of  flexion,  as  is  indicated  by  the  fact  that  it  receives  the  same  nerve- 
supply  as  the  sartorius  and  ilio-psoas.  The  tendency  which  it  has  to  adduct  during 
flexion  is  counteracted  by  the  slight  abduction  produced  by  the  sartorius.  They 
will  together  produce  the  slight  external  rotation,  which  is  observed  during  the 
advance  of  the  leg  in  walking. 

Relations. — In  front,  the  puVjic  portion  of  the  fascia  lata,  the  femoral  and 
profunda  vessels,  and  at  its  insertion  the  psoas  and  iliaeus  muscles;  behind,  the 
adductor  brevis,  obturator  externus,  hip-joint,  and  obturator  nerve. 

Variations. — Sometimes  a  slight  blendiug  of  the  lower  fibres  of  the  pectiueus  with  the 
adductor  lousus  has  been  observed. 


THE  GLUTEAL  MUSCLES 

These  are  arranged  in  three  layers. 

First  Layer 

The  first  layer  consists  of  two  muscles — the  gluteus  maximus  and  the  tensor 
vaginae  femoris. 

1.  GLUTEUS  MAXI^IUS 

Tlie  gluteus  maximus  (figs.  291  and  303) — named  from  its  great  size  and  from 
the  region  which  it  occupies  {ykouTo^  =  the  buttock) — is  a  very  thick  and  strong 
rhomboidal  sheet. 

Origin. — (1)  The  posterior  fifth  of  the  outer  lip  of  the  crest  of  the  ilium,  and 
the  outer  surface  of  the  ilium  between  the  outer  lip  of  the  crest  and  the  superior 
gluteal  line;  (2)  the  lumbar  aponeurosis  betAveen  the  posterior  superior  spine  of  the 
ilium  and  the  side  of  the  sacrum;  (3)  the  lateral  portion  of  the  posterior  surface  of 
the  two  last  pieces  of  the  sacrum;  (4)  the  side  of  the  coccyx;  (5)  the  back  of  the 
great  sacro-sciatic  ligament;  (6)  in  front  of  its  attachment  to  the  ilium  a  few  of  its 
fibres  arise  from  the  strong  process  of  the  fascia  lata  which  invests  the  gluteus 
mcdius. 

Insertion. — (1)  The  upper  part  of  the  strong  aponeurosis  of  the  fascia  lata, 
called  the  ilio-tibial  band;  (2)  the  gluteal  ridge  of  the  fenuir  which  leads  from  tlie 
lower  l)order  of  the  greater  trochanter  to  the  linea  aspera;  (3)  the  adjacent  part  of 
the  tendinous  origin  of  the  vastus  externus. 

Structure. — Its  origin  is  almost  entirely  fleshy,  a  few  tendinous  fibres  only 
being  intermingled  between  the  coarse  bundles  which  rim  parallel  to  one  anotlier 
downwards  and  outwards  to  the  aponeurosis  of  insertion.  The  U])per  half  of  this 
aponeurosis  passes  over  the  outer  surface  of  the  great  trochanter  to  be  attached  to 
the  u})per  part  of  the  ilio-til)ial  band.     Lower  down  the  insertion  consists  of  short 


352  THE  MUSCLES 

tendinous  fibres,  wliicli  are  not  only  attached  to  tlie  roujrh  process  of  tlie  l)one  but 
to  the  adjacent  tendon  of  the  vastus  externus,  while  the  more  su])erticial  fibres  still 
pass  on  to  be  attached  to  the  fascia  lata.  The  whole  muscle  forms  a  parallelogram 
of  which  the  upper  and  lower  parallel  sides  are  formed  by  the  origin  and  insertion 
which  run  in  oljlique  lines  downwards  and  iuAvards,  w^hile  the  outer  and  inner 
borders  of  the  muscle  running  downwards  and  outwards  form  the  other  two  sides 
of  the  parallelogram.  This  nmscle  is  especially  remarkable  for  the  large  size  of  the 
fasciculi  in  which  its  fleshy  fibres  are  arranged,  and  which  give  the  muscle  its 
peculiarly  coarse  appearance. 

There  are  two  well-marked  bursffi  in  connection  with  the  deep  surface  of  this 
muscle:  the  one  over  the  tul)erosity  of  the  ischium,  which  is  jjartly  covered  by 
the  muscle  and  partly  projects  from  the  middle  of  its  knver  l)order  in  such  away  that 
Avhen  the  thigh  is  extencled  it  intervenes  between  the  muscle  and  the  prominence 
of  bone,  and  when  the  thigh  is  flexed  it  lies  between  the  tuberosity  of  the  ischium 
and  the  subcutaneous  fat.  The  second  is  a  large,  often  multilocular  cavity  which 
se]:)arates  the  outer  surface  of  the  greater  trochanter  from  the  aponeurosis  of  insertion 
of  the  upper  part  of  the  muscle.  A  small  bursa  is  also  occasionally  found  between 
the  lower  part  of  the  muscle  and  the  tendon  of  the  vastus  externus. 

Nerve-supply. — From  the  sacral  plexus  (through  the  fifth  lumbar  and  the  first 
and  second  sacral  nerves),  by  means  of  the  inferior  gluteal  branches  which  enter 
the  deep  surface  of  the  muscle  close  to  its  inferior  and  internal  border. 

Action. — To  extend  the  hip-joint.  The  upper  part  of  the  muscle,  passing  over 
the  greater  trochanter,  is  placed  at  a  consideral)le  distance  from  the  axis  of  movement 
which  passes  through  the  centre  of  the  hip-joint.  A  similar  object  is  obtained  by 
the  insertion  of  the  lower  fibres  of  the  muscle  at  some  distance  down  the  back  of 
the  femur.  The  whole  muscle  therefore  is  able  to  act  as  an  extensor  of  the  hip- 
joint  with  much  less  mechanical  disadvantage  than  is  usual  in  the  body.  The 
gluteus  maximus  is  not  used  in  the  movements  of  extension  which  recjuire  but 
little  muscular  power,  such  as  those  which  draw  the  thigh  backwards  in  walking; 
for  this  purpose  the  contraction  of  the  hamstring  muscles  at  the  back  of  the  thigh 
is  alone  employed.  AVhere,  however,  a  greater  effort  is  required,  as  in  ascending 
a  hill  or  in  running  and  leaping,  the  gluteus  maximus  acts  with  great  power. 

It  has  some  influence  as  an  external  rotator.  With  respect  to  abduction  and 
adduction,  the  action  of  the  muscle  is  neutral.  Acting  alone,  its  upper  fibres  will 
assist  in  the  former,  and  its  lower  fibres  in  the  latter  movement.  By  means  of  the 
ilio-tibial  band  it  makes  tense  the  outer  portion  of  the  fascia  lata  and  is  able  to 
exert  some  force  in  the  extension  of  the  knee,  especially  Avhen  that  movement  is 
nearly  completed.  Taking  its  fixed  point  from  below,  the  gluteus  maximus  is  a 
powerful  extensor  of  the  pelvis  and  in  some  degree  of  the  lower  part  of  the  s}>ine, 
e.g.  in  rising  from  the  stooping  position  or  Avhere  the  trunk  in  a  sitting  posture  is 
drawn  forcibly  l>ackwards  as  in  the  action  of  rowing.  The  influence  Avhich  it  has 
upon  the  back  by  means  of  its  attachment  to  the  lumbar  aponeurosis  is  shown  by 
the  great  pain  which  is  felt  in  rising  from  the  stooping  position  when  there  is  any 
inflammation  of  the  fascise  in  this  region,  as  in  lumbago. 

Relations. — Behind,  the  thick  adipose  tissue  of  the  buttock  and  numerous 
cutaneous  ncrA'os;  in  front,  the  gluteus  medius,  pyriformis,  gemelli  and  obturator 
internus,  ([uadratus  femoris,  adductor  magnus,  biceps,  semi-tendinosus  and  semi- 
menibranosus,  the  gluteal,  sciatic  and  pudic  vessels,  the  great  and  small  sciatic,  the 
pudic  and  internal  ol)turator  nerves,  the  two  sacro-sciatic  ligaments,  the  tuber 
isehii,  and  greater  trochanter. 

Variations. — These  are  rare.     Occasionally  a  bilaruinar  arrangement  has  been  observed. 


2.  TENSOR  VAGINA.  FEMORIS 

The  tensor  vaginae  femoris  Cfigs.  2S7  and  803) — named  from  its  function  of 
making  tight  the  fascia  lata,  or  sheath  of  tlie  thigh  (=  vagina  femoris)  is  an 
elongated,  four-sided  sheet. 

Origin. — (1)  Tim  front  of  the  outer  lip  of  the  crest  of  the  ilium;  (2)  the  upi)er 


GLUTEUS  MEDIUS  353 

part  of  the  notch  between  the  anterior  sujierior  and  the  anterior  inferior  spines  of 
the  ilium;   (o)  the  inner  surface  of  the  fascia  lata,  l)y  which  it  is  closely  invested. 

Insertion. — The  fascia  lata  ahout  one-fourth  of  the  way  down  the  outer  side  of 
the  thigh. 

Structure. — The  muscle  consists  of  ])arallel  Heshy  fibres  which  arise  by  a 
short  tendinous  sheet,  pass  obliquely  downwards,  outwards,  and  backwards,  and 
are  inserted  between  two  layers  of  the  upper  part  of  the  strong  aponeurosis  of  the 
fascia  lata  on  the  outside  of  the  thigh  called  the  ilio-tihial  band,  which  also  gives 
attachment  to  the  majority  of  the  fibres  of  the  gluteus  maximus.  The  two  muscles 
meet  by  their  adjacent  Ijorders  a  little  below  the  upper  part  of  the  greater  trochanter 
at  an  angle  of  about  60°.  As  they  pass  upwards,  the  two  divisions  of  the  fascia 
lata  form  a  strong  sheath  for  the  muscle. 

Nerve-supply. — Through  the  fourth  and  fifth  lumbar  nerves,  and  the  first 
sacral,  Ijy  the  terminal  branch  of  the  superior  gluteal  nerve  which  enters  the  muscle 
about  the  middle  of  its  deep  surface  near  its  posterior  border. 

Action. — To  abduct  and  rotate  inwards  the  thigh,  and,  taking  its  fixed  point 
from  below,  to  support  the  pelvis  and  to  rotate  the  other  side  of  it  forwards. 
Acting  with  the  gluteus  maximus,  it  will  draw  upwards  the  ilio-tibial  band,  the 
obliquity  of  its  fibres  enabling  it  to  counteract  the  tendency  of  that  muscle  to  draw 
the  l)and  backwards.  The  chief  consequence  of  this  traction  upon  the  ilio-tibial 
Itand  will  be  to  assist  in  the  latter  part  of  the  extension  of  the  leg,  by  the  drawing 
upwards  of  the  external  tuberosity  of  the  tibia. 

Relations. — Superficially,  the  fascia  lata  and  the  origin  of  the  sartorius; 
deeply,  the  deeper  layer  of  the  fascia  lata,  the  gluteus  medius,  the  upper  part  of 
the  rectus  femoris  and  the  vastus  externus,  with  some  of  the  branches  of  the 
external  circumflex  artery. 

Second  Layer 

The  second  layer  consists  of  one  muscle — 


GLUTEUS  MEDIUS 

The  gluteus  medius  (fig.  288) — named  from  its  size  and  position,  which  are 
intermediate  between  those  of  the  great  and  small  gluteal  muscles — is  a  strong 
triangular  sheet. 

Origin. — (1)  The  anterior  four-fifths  of  the  outer  lip  of  the  crest  of  the  ilium; 
(2)  the  outer  surface  of  the  ilium,  bordered  al)Ove  by  the  middle  portion  of  the 
outer  lip  of  the  crest  of  the  ilium,  and  in  the  posterior  fifth  by  the  superior  gluteal 
line,  below  by  the  middle  gluteal  line;  (3)  the  strong  process  of  the  fascia  lata 
which  invests  the  outer  surface  of  the  muscle  and  separates  it  behind  from  the 
gluteus  maximus;  (4)  the  intermuscular  septum  which  intervenes  between  it  and 
the  gluteus  minimus  just  Ijelow  the  anterior  superior  spine  of  the  ilium. 

Insertion. — The  well-marked  oblic{ue  impression  extending  from  the  posterior 
superior  to  the  anterior  inferior  angle  on  the  outer  surface  of  the  greater  trochanter. 

Structure. — Arising  by  fleshy  and  tendinous  fibres  intermingled,  the  muscle 
converges  fanwise  ujion  V)oth  surfaces  of  a  strong  flat  tendon  which  is  visible  rather 
higher  ui)on  the  deep  than  the  outer  surface  of  the  muscle.  The  front  part  of  the 
nuiscle  is  stronger,  and  it  gradually  decreases  in  thickness  towards  its  posterior 
edge.  A  Inirsa  is  contained  l)etween  the  deeji  i»ortion  of  the  tendon  and  the 
triangular  space  that  lies  in  front  of  the  impression  upon  the  outer  surface  of  tlie 
greater  trochanter. 

Nerve-supply. — From  the  fourth  and  fifth  lumbar  nerves,  and  the  first  sacral 
nerve  by  branches  of  the  superior  gluteal  nerve  which  enter  the  deep  surface  of  the 
muscle  near  the  middle  of  its  ])osterior  border. 

Action. — To  abduct  the  hip-joint.     It  will  also  by  its  thicker  and  stronger 

anterior  fibres  rotate  the  thigh  inwards.      Its  posterior  fil)res,  on  the  other  hand, 

which  are  not  so  strong  will  tend  slightly  to  rotate  the  thigh  outwards.      Acting 

from  below,  it  tends  to  support  the  pelvis  upon  the  fenuu*  and  to  approximate  the 

23 


354  THE  MUSCLES 

crest  of  the  ilium  to  the  greater  troeliantur.  This  is  ])y  far  the  most  imi)ortant  and 
frecjuent  of  its  actions.  In  walkinu",  if  it  were  not  for  the  powerful  contraction  of 
the  gluteus  medius  and  its  associated  muscles  the  gluteus  minimus  and  the  tensor 
vaginie  femoris,  the  pelvis  Avould  not  l:)e  held  firm  upon  the  upper  part  of  the  thigh 
when  one  leg  is  upon  the  ground  and  the  other  is  being  advanced  in  the  forward 
step.  In  fast  Avalking  the  rotatory  action  of  the  muscle  comes  into  play,  for  not 
only  does  the  gluteus  medius  of  the  limb  Avhich  is  resting  upon  the  ground  supi)ort 
the  pelvis  by  drawing  downwards  the  crest  of  the  ilium,  l:)ut,  l;)y  drawing  back- 
wards the  front  portion  of  that  crest,  it  throws  forwards  the  opposite  side  of  the 
pelvis  and  increases  the  length  of  the  stride. 

Relations. — Superficially,  the  fascia  lata,  gluteus  maximus,  and  tensor  vaginae 
femoris;  deeply,  the  gluteus  minimus,  sujierior  gluteal  vessels  and  nerve,  and  the 
greater  trochanter. 

Variations. — Sometimes  a  partially  distinct  bundle  of  fibres  is  inserted  into  the  front  of  the 
upper  border  of  the  greater  trochanter.  A  slip  may  be  giveu  from  the  lower  border  to  the 
pyriformis. 

Third  Layer 

The  third  layer  consists  of  one  muscle — the  gluteus  minimus — which  is  con- 
tinuous Avith  the  external  rotators  which  form  the  next  group. 


GLUTEUS  MINIMUS 

The  gluteus  minimus  (fig.  290) — named  from  its  position  and  smaller  size — is 
a  thick  triangular  sheet. 

Origin. — (1)  The  outer  surface  of  the  ilium  between  the  middle  and  inferior 
gluteal  lines;  (2)  a  fibrous  septum  which  intervenes  between  its  fibres  and  those  of 
the  gluteus  medius  below  the  anterior  superior  spine;  (3)  the  front  of  the  capsule 
of  the  hi]3- joint. 

Insertion. — The  well-marked  vertical  impression  which  forms  the  anterior 
border  of  the  greater  trochanter. 

Structure. — From  the  fleshy  origin  the  fibres  converge  fanwise  upon  the  deep 
surface  of  the  tendon  which  is  first  seen  about  the  middle  of  the  anterior  border, 
and  then  covers  the  lower  part  of  the  muscle.  By  its  anterior  border  this  muscle 
is  closely  blended  with  the  anterior  border  of  the  gluteus  medius  and  with  some  of 
the  ligaments  of  the  hip-Joint.  Like  the  preceding  muscle,  it  is  also  much  thicker 
and  stronger  in  front. 

Nerve-supply. — From  the  same  sources  as  the  preceding  by  the  superior 
gluteal  nerve  which  distributes  filaments  to  the  middle  of  its  outer  surface  near 
its  posterior  border. 

Action. — The  same  as  the  preceding:  viz.  to  abduct  and  rotate  inwards  the  hip- 
joint;  and  when  it  takes  its  fixed  point  from  below,  as  is  most  usually  the  case,  to 
flex  the  pelvis  laterally  and  at  the  same  time  to  rotate  the  other  side  forwards. 

Relations. — Sui)erficially,  the  gluteus  medius,  the  superior  gluteal  vessels  and 
nerve;  deeply,  the  capsule  of  the  hip- joint,  and  posterior  head  of  the  rectus 
femoris. 

Variations. — The  front  part  of  the  musele  may  be  separate  from  the  rest.  It  occasioually 
sends  slips  to  the  adjacent  muscles. 


THE  EXTERNAL  ROTATORS  OF  THE  THIGH 

This  group  consists  of  six  somewhat  short  muscles,  wliich  run  transversely  from 
the  pelvic  l)ones  to  the  femur,  and  which  follow  innnediately  after  the  lower  fibres 
of  the  gluteus  mininnis — viz.  the  pyriformis,  the  obturator  "internus  with  the  two 
gemelli,  the  quadratus  feiuoris,  and  the  obturator  cxteruus. 


THE  EXTERNAL  ROTATORS   OF  THE   THIGH 


355 


1.     PYRIFORMIS 

Tlie   pyriformis — named    from    its    pear    .shape    ( p^V??.?  =  pear) — is    a    thick 
trian^-ular  sheet. 

Origin.— (Ij  The  side  of  the  front  of  the  sacrum  between  and  to  the  outer  side 

Fig.  288.— The  External  Kotatous  and  the  Hamstring  Muscles. 


Gluteus  medius 

Pyriformia 
Gemellus  superior 

Gemellus  inferior 
Quadratus  femoris 


Gluteus  maiimus 


Vastus  externus 


Biceps  — 


Crureus 

Short  head  of  biceps 

Plantaris 


OaatrocnemiuE 


Obturator  internus 


Adductor  magnus 


Semi-tendinosus 


Semi -mem  bran  osus 

Sartorius 

Semi-tendinosus 


of  the  first,  second,  third,  and  fourth  foramina;  (1)  the  deep  surface  of  the  great 
sacro-seiatic  hgament;  (3)  the  posterior  border  of  the  hip  bone  at  the  ui.i)er^)art 
of  the  great  sacro-sciatie  notch. 

Insertion. — A  small  facet  upon  the  front  and  inner  aspect  of  the  upper  border 
of  the  greater  trochanter. 


356  THE  MUSCLES 

Structure. — The  greater  part  of  the  iiiusele  arises  by  three  fleshy  sHps  on  the 
ridges  of  bone  between,  and  external  to,  the  anterior  sacral  foramina.  From  this 
origin,  which  receives  accessory  slips  of  small  size  from  the  great  sacro-sciatic 
ligament  and  the  upper  portion  of  the  great  sacro-sciatic  notch,  the  fibres  converge 
as  they  pass  transversely  outwards  and  somewhat  backwards  through  the  great 
sacro-sciatic  foramen.  The  tendon  is  first  visil)le  upon  the  deep  as})ect  of  the 
muscle,  and  it  liecomes  free  near  the  posterior  border  of  the  greater  trochanter. 
Shortly  liefore  its  insertion  it  is  closely  l)lended  with  the  tendon  of  the  obturator 
internus  museU'. 

Nerve-supply. — From  the  sacral  plexus  by  small  l)ranches  which  pass  from 
the  second  sacral  nerve  into  the  anterior  surface  of  the  muscle  near  its  origin. 

Action. — To  rotate  the  thigh  outwards.  When  the  thigh  is  fixed,  it  will  rotate 
the  pelvis  so  that  the  face  is  turned  to  the  opposite  side;  if  the  thigh  be  flexed,  the 
pyriformis  will  alKluct  it. 

Relations. — In  front,  the  sacral  plexus  and  rectum,  the  back  of  the  hip-joint, 
and  some  of  the  branches  of  the  internal  iliac  artery;  behind,  the  gluteus  maximus; 
above,  the  gluteus  medius  and  minimus,  with  the  superior  gluteal  vessels  and  nerve; 
below,  the  coccygeus,  the  lesser  sacro-sciatic  ligament  and  gemellus  superior,  the 
sciatic  and  pudic  vessels,  and  most  of  the  branches  from  the  sacral  plexus. 

Variations. — The  pj'riforruismay  be  absent.  It  is  often  divided  by  a  part  of  the  great  sciatic 
nerve  into  two  muscles,  and  sometimes  into  three.  It  maj'  be  more  or  less  blended  with  the 
gluteus  medius  or  minimus  above,  and  the  superior  gemellus  below. 


2,  3,  AND  4.  OBTURATOR  INTERNUS  AND  GEMELLI 

The  obturator  internus  and  gemelli  form  really  a  single  muscle,  the  greater 
part  of  which  arises  inside  the  pelvis;  while  the  gemelli  form  two  accessory  slips 
W'hich  join  it  from  the  margin  of  that  cavity. 

The  obturator  internus — named  from  the  fact  that  it  arises  from  the  mem- 
brane which  closes  up  the  obturator  foramen,  and  from  its  position  within  the 
pelvis — is  a  somewhat  triangular  sheet,  or  rather,  perhaps,  it  should  be  described 
as  the  sector  of  a  circle,  for  its  origin  Avithin  the  pelvis  is  bounded  by  a  curved  line 
like  a  part  of  the  circumference  of  a  circle. 

Origin. — The  wdiole  of  the  interior  of  that  part  of  the  pelvis  which  is  formed  by 
the  innominate  bone :  viz.  ( 1 )  The  ])ack  of  the  body  and  descending  ramus  of  the 
OS  pubis,  and  of  the  ascending  ramus  of  the  ischium;  (2)  the  whole  of  the  inner 
surface  of  the  ol)turator  membrane;  (3)  the  broad  surface  of  bone  behind  the  fora- 
men, corresponding  to  the  acetabulum  on  the  exterior;  (4)  the  outer  surface  of  the 
pelvic  and  ol)turator  fascife.  These  extend  from  the  ilio-pectineal  line  above  to  the 
great  sacro-sciatic  foramen  behind,  and  to  the  spine  and  tulierosity  of  the  ischium 
below. 

Insertion. — The  inner  aspect  of  the  upper  l)order  of  the  greater  trochanter  at 
the  jxiint  where  it  unites  with  the  u})per  border  of  the  neck  of  the  femur. 

Structure. — The  muscle  arises  fleshy  from  the  Avhole  of  the  interior  of  the 
pouch-like  cavity  formed  by  the  pelvic  and  obturator  fascia?  internally  and  the  bony 
wall  of  the  ])elvis  externally,  and  o})ening  backwards  and  downwards  at  the  lesser 
sacro-sciatic  foramen.  From  this  extensive  origin  the  filirc^s  converge  downwards  and 
backwards  upon  a  broad  tendinous  expansion  which  begins  about  one  inch  (2 "5  cm.  ) 
al)ove  the  lesser  sacro-sciatic  foramen  upon  the  outer  surface  of  the  muscle.  This 
ex])ansion  is  corrugated  into  four  or  five  folds,  which  are  separated  from  the  cartila- 
ginous lining  of  the  lesser  sacro-sciatic  notch  by  a  bursal  cavity  Avhich  allows  of  the 
smooth  play  of  the  tendon  upon  the  bone.  This  cartilage  presents  corresponding 
grooves  for  the  folds  of  the  tendon.  After  passing  through  this  foramen  the  tendon 
changes  its  course,  and  is  directed  transversely  outwards  and  forwards  to  its  inser- 
tion. The  fleshy  fibres  extend  upon  the  inner,  which  has  now  become  its  posterior 
surface  for  about  half  the  distance  from  the  notch  to  the  facet  upon  the  greater 
trochanter.  For  a  short  distance  before  its  insertion  it  is  intimately  connected  with 
the  tendon  of  the  ]>yriformis. 

Nerve-supply. — From  the  first  and  second  sacral  nerves  of  the  sacral  jjIcxus 


OBTURATOR  IXTERXUS  AXD   GEMELLI  357 

by  a  special  nerve  which,  after  passing  through  the  lesser  sacro-sciatic  notch,  is 
distrilHited  to  the  niusclc,  entering  its  inner  surface  near  its  upper  border  and  close 
to  the  lesser  sacro-sciatic  foramen. 

The  gemellus  superior — named  from  gemellus  =  a  twin,  because  it  is  the  upper 
of  the  two  twin  muscles  wliich  nearly  surround  the  tendon  of  the  obturator  internus 
at  its  point  of  emergence  from  the  pelvis — is  a  somewhat  triangular  sheet  curved 
upon  itself  to  embrace  the  rounded  tendon  of  the  obturator  internus. 

Origin. — (1)  The  outer  surface  of  the  spine  of  the  ischium;  (2)  the  upper  half 
of  the  outer  edge  of  the  lesser  sacro-sciatic  notch. 

Insertion. — The  upper  boixler  and  the  anterior  surface  of  the  obturator  internus 
tendon,  a  sliort  distance  from  its  insertion. 

Structure. — Arising  fleshy  from  the  ])one  at  the  margin  of  the  lesser  sacro- 
sciatic  foramen,  the  muscular  filjres  converge  slightly  and  form  a  sheet  which  is 
curved  upon  itself  so  as  to  fit  round  the  upper  border  and  anterior  aspect  of  the 
ol)turator  internus  tendon,  with  which,  after  a  course  of  about  two  inches  (5  cm. ) 
in  length,  it  blends. 

Nerve-supply. — The  first  and  second  nerves  of  the  sacral  plexus  by  a  small 
special  In-anch  which  enters  the  muscle  at  the  upper  part  of  its  anterior  surface  near 
its  origin. 

The  gemellus  inferior — the  lower  of  these  twin  muscles — is  also  triangular  in 
sha]>e.  but  is  somewhat  broader  and  stouter  than  its  fellow. 

Origin. — ( 1)  The  upper  part  of  the  inner  border  of  the  tuber  ischii;  and  (2) 
the  lower  half  of  the  outer  edge  of  the  lesser  sacro-sciatic  notch. 

Insertion. — The  lower  border  and  anterior  surface  of  the  tendon  of  the 
oljturator  internus,  a  short  distance  from  its  attachment  to  the  greater  trochanter. 

Structure. — Its  fibres,  arising  fleshy  from  the  lower  half  of  the  outer  border  of 
the  lesser  sacro-sciatic  notch,  converge  and  form  a  sheet  which  wraps  round  the 
lower  part  of  the  anterior  surface  of  the  tendon  of  the  obturator  internus.  The  two 
gemelli  therefore  together  form  an  envelope  which  emljraces  the  whole  of  the  tendon 
of  the  ol)turator  internus  after  its  emergence  from  the  j^elvis,  Avith  the  exception  of 
a  part  of  its  posterior  surface. 

Nerve-supply. — From  the  sacral  plexus  (through  the  fifth  lumbar  and  first 
sacral  nerves),  by  filaments  from  the  special  nerve  to  this  muscle  and  the  quadratus 
femoris,  which  enter  the  upper  part  of  its  anterior  surface  near  its  origin. 

Action. — The  obturator  internus  with  its  two  satellites,  the  gemelli,  powerfully' 
rotates  the  femur  outwards.  It  should  be  observed  that,  although  the  fibres  are 
mostly  directed  backwards  and  downwards  within  the  pelvis,  the  action  of  the 
nniscle  is  really  determined  by  the  outward  and  slightly  forward  direction  of  the 
tendon  outside  tlie  pelvis;  and  the  notch  upon  the^  bone  plan's  the  part  of  a  pulley 
in  changing  the  direction  of  the  force. 

Besides  its  action  as  an  external  rotator,  the  muscle  will  l)e  al tie  to  assist  abduc- 
tion when  tlie  thigh  is  bent  through  a  right  angle. 

Relations. — The  obturator  internus  in  the  pelvis  is  in  contact  externally  with 
the  innominate  bone  and  obturator  membrane;  above,  with  the  obturator  artery 
and  nerve;  internally,  with  the  pelvic  and  obturator  fascia?,  the  levator  ani,  the 
pelvic  viscera,  and  the  pudic  vessels  and  nerve. 

Outside  the  pelvis,  the  tendon  of  the  obturator  internus.  with  the  gemelli,  is  in 
contact,  in  front  with  the  capsule  of  the  hip-joint  and  the  tendon  of  the  oV)turator 
externus;  behind,  with  the  gluteus  maximus,  great  sacro-sciatic  ligament,  the  sciatic 
vessels  and  nen'es;  above,  with  the  pyriformis  and  the  structures  Avhich  come  out 
of  tlie  pelvis  lielow  it;  below,  with  the  quadratus  femoris  and  a  branch  of  the 
internal  circumflex  artery. 

Variations. — One  or  other  of  the  gemelli  may  be  absent,  but  more  frequently  the  upper  one. 
An  accessory  slip  to  the  obturator  internus  has  been  obser\'ed  coming  from  the  third  jiiece  of  the 
sacmm. 


358  THE  MUSCLES 


5.  QUADRATUS  FEMORIS 

The  quadratus  femoris — named  from  its  square  sliape  and  its  insertion  into 
the  femur — is  a  four-sided  sheet. 

Origin. — The  upper  part  of  the  outer  border  of  the  tuber  ischii. 

Insertion. — The  vertical  ridge  -vvliich  begins  just  above  the  middle  of  the  pos- 
terior intertrochanteric  line  of  the  femur,  and  is  called  the  'linea  quadrati.' 

Structure. — Its  fibres  are  fleshy  and  run  parallel  to  one  another  almost  hori- 
zontally outwards  and  slightly  forwards. 

Nerve-supply. — From  the  sacral  plexus  (through  the  fifth  lumbar  and  first 
sacral  nerve)  by  a  special  branch  which,  after  furnishing  filaments  to  the  inferior 
gemellus,  enters  the  muscle  near  the  upper  part  of  its  anterior  surface  close  to  its 
origin. 

Action. — If  approximates  the  posterior  border  of  the  greater  trochanter  to  the 
tuber  iscliii,  and  so  assists  powerfully  in  the  external  rotation  of  the  femur. 

Relations. — Behind,  the  gluteus  maximus  and  the  two  sciatic  nerves;  in  front, 
the  obturator  externus  and  the  termination  of  the  internal  circumflex  artery. 
Above  is  the  inferior  gemellus,  and  below  tlie  adductor  magnus. 

Variations. — This  muscle  is  not  uufrequently  absent. 

G.  OBTURATOR  EXTERNUS 

The  obturator  externus  is  a  strong  external  rotator  of  the  thigh,  Init  it  is 
also  an  adductor,  and  on  account  of  its  nerve-supply  and  position  it  is  better 
described  in  that  group  of  muscles. 


THE  ADDUCTORS 

The  adductor  muscles  form  a  distinct  group  on  the  inner  side  of  the  thigh, 
and  are  all  supplied  by  the  obturator  nerve  with  the  exception  of  a  small  part  of 
the  adductor  magnus.  They  consist  of  the  adductor  longus,  adductor  brevis, 
adductor  magnus,  gracilis,  and  obturator  externus. 

1.  ADDUCTOR  LONGUS 

The  adductor  longus — so  named  from  its  action  and  its  length  compared  with 
that  of  its  immediate  neighbour — is  a  thick  triangular  sheet. 

Origin. — A  rounded  impression  on  the  front  of  the  body  of  the  os  pubis 
immediately  below  the  crest  and  angle. 

Insertion. — (1)  The  lower  two-thirds  of  the  inner  lip  of  the  linea  aspera  (in 
the  middle  third  of  the  thigh) ;  and  (2)  the  adjacent  internal  intermuscular  septum. 

Structure. — Arising  by  a  strong  rounded  tendon,  -which  extends  about  two 
inches  (5  cm.)  downwards  upon  the  inner  border  of  the  muscle,  the  fleshy  fil^res 
diverge  in  a  fan-shaped  expansion,  and  are  inserted  by  short  tendinous  fibres  Avhich 
blend  behind  with  those  of  the  adductor  brevis  and  adductor  magnus. 

Nerve-supply. — From  the  third  and  fourth  nerves  of  the  lumljar  plexus,  by 
])ranches  from  the  anterior  division  of  the  obturator  nerve  which  enter  the  muscle 
on  the  up})cr  part  of  its  posterior  surface  rather  below  its  middle. 

Action. — To  adduct  and  flex  the  femur,  and  at  the  same  time  to  rotate  it 
outwards. 

Relations. — In  front,  the  fascia  lata,  sartorius,  vastus  internus,  and  superficial 
femoral  vessels;  l)ehind,  the  adductor  brevis  and  magnus,  the  profunda  vessels,  and 
the  obturator  nerve;  its  upper  border  touches  the  i)ectineus. 

Variations. — The  adductor  loncfus  may  arise  by  two  heads,  the  outer  being  attached  to  the 
crest  uf  the  pubes,  and  separate  from  the  ordinary  head  which  arises  below  the  angle.  Occa- 
sionally the  muscle  is  divided  by  the  passage  of  vessels  into  an  upper  and  a  lower  portion. 


ADDUCTOR   BEE  VIS 


359 


2.  ADDUCTOR  BREVIS 

The  adductor  brevis — named  from  its  action  and  its  size  as  compared  with  the 
preceding  muscle — is  a  thick  quadrilateral  sheet. 


Fig.  289.— The  Deep  Muscles  of  the  Front  of  the  Thigh. 


Cbturator  externus 


Adductor  longus 


Adductor  maguus 


Adductor  longus 


Vastus  internuF 


Rectus  femoris 


Ligameutum  patellae 


Rectus  tendon 


Gluteus  mediUB 


'^\nS\unj      Gluteus  minimus 


Adductor  brevis 


Vastus  externuB 


Biceps 


Ilio-tibial  band 


some- 


Origin.— The  body  and  the  descendintr  ramus  of  theos  pubis,  below,  and  s 
Avhat  external  to,  the  origin  of  the  adductor  longus. 

Insertion. — The  inner  lip  of  the  linea  asperii  in  its  upper  half,  extendiuff  from 
just  below  the  lesser  trochanter  to  aliout  the  middle  of  the  back  of  the  femur. 

Structure. — Arising  by  short  tendinous  fibres,  tlie  muscle  diverges  into  a  fan- 


360 


THE  MUSCLES 


shaped  flesliy  exi)ansio)i,  Avhich  ends  in  sliort  tendinous  fibres  blending  with  those 
of  the  adductor  longus  and  adchictor  niagnus. 

Nerve-supply. — From  tlie  third  and  fourth  nerves  of  the  luml)ar  })lexus  by  the 
sujierficial  branch  of  the  obturator  nerve,  -which  sends  filaments  to  the  anterior 
surface  of  the  muscle  near  the  lower  part  of  its  upper  border.  Sometimes,  how- 
ever, it  derives  its  nerve-supply  from  the  deeper  division  of  the  obturator  nerve,  and 
in  tliat  case  the  nerves  enter  the  muscle  from  behind. 


Fig.  290. — The  Deep  Muscles  of  the  Back  of  the  Thigh. 


Gluteus  minimus 


Obturator  extemus 


Gluteus  mazimus  — -, — 


Vastus  extemus 


Short  head  of  biceps 


Tendon  of  biceps 


Obturator  internus 


Adductor  magnus 


Vastus  internus 


Action. — Like  the  preceding,  it  is  an  adductor  and  rotator  outwards  of  the 
femur,  ])ut  it  will  not  assist  so  powerfully  in  flexion. 

Relations. — In  front,  the  pectineus,  adductor  longus,  the  profunda  vessels,  and 
sujierficial  l>ranch  of  the  oljturator  nerve;  behind,  the  obturator  externusand 
adductor  magnus,  and  the  deep  brancli  of  tlie  ol>turator  nerve. 

Variations.— It  is  sometimes  divideil  intij  an  upper  and  a  lower  portion.  Occasiunully  it 
joins  above  with  tlie  oljturator  externus. 


ADDUCTOR  MAGNUS  361 


3.  ADDUCTOR  MAGNUS 

The  adductor  magnus — named  from  its  aetion  and  its  great  size — is  a  thick 
fan-sliaj)ed  sheet,  forming  a  riglit-angled  triangle,  the  right  angle  of  which  is 
contained  l^etween  the  side  corresponding  to  the  insertion  of  the  muscle  at  the  back 
of  the  fenuu-  and  the  side  formed  by  tiie  free  upper  border  of  the  muscle. 

Origin. — (1)  The  lower  part  of  the  outer  border  of  the  tuber  ischii;  (2)  the 
outer  surface  of  the  ascending  ramus  of  the  ischium  near  its  inner  border;  (3)  the 
front  of  the  outer  surface  of  the  descending  ramus  of  the  pul)es. 

Insertion. — (1)  The  back  of  the  femur,  in  a  line  beginning  at  the  lower 
extremity  of  the  linea  quadrati,  and  extending  along  the  inner  ])order  of  the  gluteal 
ridge  and  the  middle  of  the  linea  aspera  down  to  its  l)ifurcation;  (2)  the  adductor 
tubercle  on  the  upper  and  jjosterior  part  of  the  internal  condyle;  (3)  the  loAver  part 
of  the  internal  intermuscular  septum. 

Structure. — Its  origin  and  insertion  are  by  short  tendinous  fibres,  with  the 
exception  of  the  insertion  of  the  bundle  of  til^res  which  passes  from  the  tuber  ischii 
to  the  adductor  tubercle.  These  arise  by  a  long  tendon  above,  and  again  become 
tendinous  three  or  four  inches  (7  to  10  cm. )  above  the  knee-joint,  so  as  to  form  a 
long  and  conspicuous  tendon  on  the  lower  part  of  the  inner  border  of  the  muscle. 
Between  this  part  of  the  insertion  of  the  muscle  and  the  linea  aspera,  the  fibres  are 
attached  to  the  back  of  the  internal  intermuscular  septum  and  to  a  tendinous  arch 
which  allows  of  the  passage  of  the  superficial  femoral  artery  and  vein  from  Hunter's 
canal  into  the  upper  part  of  the  popliteal  space.  Between  the  origin  and  insertion 
the  fibres  diverge;  the  anterior  fibres  of  origin  passing  horizontally  outwards  to  their 
insertion  into  the  upper  part  of  the  back  of  the  femur,  Avhile  the  fibres  which  arise 
behind  pass  vertically  downwards  from  the  tuber  ischii  to  the  internal  condyle. 
Moreover,  the  muscle  is  twisted  upon  itself  so  that  the  surface  which  above  looks 
inwards  and  rather  Ijackwards  is  directed  forwards  below.  A  deep  longitudinal 
groove  is  thus  formed  upon  tlie  upper  part  of  the  back  of  the  muscle,  in  which  lie 
the  hamstring  muscles  and  the  great  sciatic  nerve.  The  ujjper  part  of  the  muscle, 
which  arises  in  front,  and  is  inserted  into  the  inner  border  of  the  gluteal  ridge, 
forms  a  triangular  sheet,  usually  separate  from  the  rest,  and  sometimes  descriljed 
as  a  distinct  muscle,  the  adductor  minimus. 

In  addition  to  the  opening  for  the  superficial  femoral  vessels,  the  muscle  is 
pierced  close  to  the  bone  by  the  perforating  arteries  and  the  terminal  branch  of  the 
profunda  femoris.  Upon  its  anterior  surface  it  receives  a  membranous  expansion 
from  the  vastus  internus,  which  passes  inwards  beneath  the  sartorius  to  the  adductor 
longus  and  magnus,  forming  the  anterior  wall  of  a  sort  of  tunnel  Avhich  contains 
the  superficial  femoral  vessels  in  the  middle  third  of  the  thigh,  and  is  called 
Hunter's  canal. 

Nerve-supply. — Chiefly  from  the  third  and  fourth  nerves  of  tiie  lumbar  plexus 
by  the  deep  division  of  the  ol:»turator  nerve  Avhich  supplies  the  nuiscle  upon  the 
outer  part  of  its  anterior  surface.  The  lower  fil>res  of  the  muscle,  however,  are 
supi)lied  upon  their  posterior  surface  by  the  great  sciatic  nerve,  a  branch  of  the 
sacral  ])lexus. 

Action. — This  muscle  is  the  most  powerful  of  the  adductors.  The  upper  three 
fourths  of  its  fibres  Avill  also  rotate  outwards  the  femur,  while  that  part  of  the 
nniscle  which  arises  from  the  tuber  ischii  and  is  inserted  into  the  inner  condyle 
will  tend  slightly  to  rotate  the  thigh  inwards,  and  will  at  the  same  time  extend  as 
well  as  adduct  the  thigh. 

Duchenne  suggests  that  this  is  the  part  (A  the  muscle  which  e(|Ucstnans  should 
especially  develop.  Otherwise  the  adduction  of  the  thighs  in  gripping  the  saddle 
is  apt  to  throw  out  the  toes,  which  is  ungainly,  and,  if  the  rider  have  spurs  on, 
may  lead  to  unpleasant  consequences. 

Relations. — In  front  lie  the  adductor  brcA'is  and  longus,  and  lower  down  the 
vastus  internus.  Behind  are  the  hamstring  muscles,  the  gluteus  maximus,  and  the 
great  sciatic  nerve.  At  its  ujiper  Itorder  are  the  quadratus  femoris  and  obturator 
externus.  Along  its  inner  border  lie  the  gracilis  and  ]inrt  of  the  sartorius.  It  is  also 
in  relation  with  the  superficial  and  deep  femoral  vessels,  and  the  obturator  nerve. 


3G2  THE  MUSCLES 

Variations. — The  posterior  part  of  the  imi.sele  may  ftirm  a  distinct  slip.  Accessory  bundles 
from  the  semi-membranosus  or  biceps  may  join  tlie  lower  tendon.  The  upper  border  of  the 
muscle  may  be  blended  with  the  quadratus  femoris. 


4.    GRACILIS 

The  gracilis — named  from  its  form  ((//•aciV/s  =  slender) — is  long  and  ribbon- 
shaped. 

Origin. — The  inner  edge  of  the  anterior  surface  of  the  body  and  descending 
ramus  of  the  os  pul;)is  from  about  the  middle  of  the  symphysis  to  the  junction  of 
the  rami  of  the  pubes  and  ischium. 

Insertion. — The  inner  surface  of  the  tibia  below  its  inner  tuberosity,  behind 
the  inscrtii)n  of  the  sartorius. 

Structure. — Arising  by  a  broad  and  thin  aponeurosis,  the  muscular  fibres  pass 
down  the  inner  surface  of  the  thigh  almost  parallel  to  one  another,  but  Avith  a 
slight  convergence,  so  that  the  muscle  in  descending  increases  in  thickness  as  it 
diminishes  in  breadth.  About  two  inches  (5  cm.)  above  the  inner  condyle  it 
becomes  a  rounded  flattened  tendon.  This  runs  behind  the  inner  condyle,  and, 
after  forming  one  of  the  two  hamstring  tendons  which  can  be  easily  felt  at  the  inner 
border  of  the  popliteal  space,  it  passes  forwards  to  be  inserted  in  a  slightly  ex- 
panded form  below  the  inner  tuberosity.  A  few  fibres  pass  from  its  lower  border 
to  the  deep  fascia  of  the  leg. 

Nerve-supply. — From  the  third  and  fourth  nerves  of  the  lumbar  plexus  by  a 
branch  from  the  superficial  division  of  the  obturator  nerve  which  enters  the  deep 
surface  of  the  muscle  above  its  middle. 

Action. — To  adduct  the  thigh  and  flex  the  knee.  "When  the  knee  is  flexed,  it 
will  hel})  in  rotating  the  leg  inwards. 

Relations. — It  lies  superficially  in  its  whole  course  under  cover  of  the  fascia 
lata.  Upon  its  deep  surface  lie  the  adductor  brevis  and  magnus,  and  lower  down 
the  semi-membranosus  muscle.  It  has  in  front  of  it  the  sartorius  muscle  which 
overlaps  it  slightly  at  the  lower  part  of  the  thigh,  and  l^ehind  it  is  the  tendon  of  the 
semi-tendinosus.  The  internal  lateral  ligament  of  the  knee  and  a  large  bursa  lie 
beneath  its  tendon. 

5.    OBTURATOR  EXTERNUS 

The  obturator  externus  (figs.  286,  289,  and  290) — named  from  its  attachment 
to  the  oi)turator  membrane  upon  its  outer  surface — is  a  triangular  sheet. 

Origin. — (1)  The  inner  half  of  the  anterior  surface  of  the  obturator  membrane; 
(2)  tlie  descending  ramus  of  the  os  pubis  immediately  internal  to  the  foramen;  (3) 
the  ascending  ramus  of  the  ischium  internal  to  the  foramen. 

Insertion. — The  digital  fossa  upon  the  inner  surface  of  the  great  trochanter. 

Structure. — It  is  a  fan-shaped  triangular  muscle  which  arises  fleshy  from  the 
adjacent  surfaces  of  bone  and  membrane,  in  a  curve  Avhich  is  convex  forwards  and 
inwards.  From  this  wide  origin  the  fibres  converge  outwards,  and  end  below  the 
acetabulum  in  a  rounded  tendon  which  passes  behind  and  in  close  contact  with  the 
capsule  of  the  joint  to  its  insertion  in  the  digital  fossa.  Not  unfrequently  a  small 
portion  of  the  muscle  is  scjiarated  at  its  up})er  1)order  from  the  rest  by  one  or  both 
of  the  divisions  of  the  oV)turator  nerve. 

Nerve-supply. — From  the  third  and  fourth  nerves  of  the  lumbar  plexus  by 
the  deep  division  of  the  obturator  nerve  which  distributes  filaments  to  the  deep 
surface  of  the  muscle  as  it  is  passing  through  it. 

Action. — To  adduct  and  rotate  outwards  the  thigh. 

Relations. — Behind,  the  obturator  vessels,  and  at  its  insertion  the  quadratus 
femoris;  in  front,  the  psoas  muscle,  the  pectineus,  and  adductor  Ijrevis;  above,  the 
obturator  nerve,  one  or  both  branches  of  which  perforate  it,  and  more  externally 
the  capsule  of  the  hip-joint. 


BICEPS  FEMORIS  3G3 


THE   HAMSTRING   MUSCLES 

The  hamstring  muscles  form  a  group  at  the  back  of  the  thigh,  separated  l)y 
inter^m^c•ular  septa  from  the  vastus  externus  on  the  outer,  and  the  adductor 
magnus  on  the  inner  side.  They  consist  of  the  biceps,  semi-tendinosus  and  semi- 
membranosus, and  are  supplied  by  the  great  sciatic  nerve.  Like  the  gluteus 
maximus  their  action  is  to  extend  the  hip. 


L  BICEPS  FEMORIS 

The  biceps  femoris  (figs.  288  and  290) — named  from  its  two  heads — consists 
of  two  parts;  the  longer  head  being  somewhat  fusiform,  and  the  shorter  a  triangular 
sheet. 

Origin. — The  long  head  from  (1)  the  lower  and  inner  facet  at  the  back 
of  the  tul)er  ischii  by  a  tendon  common  to  it  and  the  semi-tendinosus;  (2)  the 
lower  part  of  the  great  sacro-sciatic  ligament.  The  short  head  from  (1)  the  outer 
lip  of  the  linea  aspera  from  a  point  just  above  the  middle  of  the  bone  down  to  the 
bifurcation;  (2)  the  uj^per  two-thirds  of  the  outer  condylar  ridge;  (3j  the  external 
intermuscular  septum. 

Insertion. — (1)  A  fossa  below  and  in  front  of  the  styloid  process  of  the  head 
of  the  tiljula;  (2)  the  deep  fascia  covering  the  peronei  muscles;  (3)  the  outer 
tuberosity  of  the  til)ia. 

Structure. — The  origin  of  the  long  head  is  by  a  short  tendon  which  is  con- 
tinued down  to  the  middle  of  the  thigh  by  a  sej^tum  which  divides  this  muscle 
from  the  semi-tendinosus.  From  this  tendon  and  the  outer  surface  of  the  septum 
the  muscular  filjres  arise  in  penniform  fashion  and  form  a  fusiform  belly,  which 
receives  at  the  junction  of  the  middle  and  lower  thirds  of  the  thigh  the  thick  sheet 
of  muscular  fibres  derived  from  the  short  outer  head.  The  tendon  commences 
upon  the  posterior  surface  of  the  muscle  near  its  outer  border  about  the  middle 
of  the  thigh.  At  the  back  of  the  external  condyle  the  fleshy  fi])res  cease.  The 
roitnded  tendon  here  widens  into  a  thick  aponeurosis,  which  embraces  the  anterior 
portion  of  the  external  lateral  ligament  at  the  point  of  its  insertion  into  the  outer 
and  anterior  facet  of  the  head  of  the  fibula.  Between  this  tendon  and  the  external 
lateral  ligament  is  a  bursa.  From  the  borders  of  the  tendon  at  this  point  a  thinner 
aponeurosis  is  given  off  to  the  outer  tuberosity  of  the  tibia  in  front  and  the  deej) 
fascia  of  the  leg  liehind. 

Nerve-supply. — From  the  first,  second  and  third  nerves  of  the  sacral  j^lexus  by 
the  great  sciatic  nerve  which  sends  branches  to  the  anterior  and  inner  surfaces  of 
the  muscle  about  the  middle  of  the  thigh.  The  short  head  of  the  biceps  receives 
its  supply  from  the  external  popliteal  nerve. 

Action. — To  extend  the  hip  and  flex  the  knee.  Its  shorter  head  acts  U])on  the 
knee  only.  A\'hen  the  knee  is  flexed,  both  heads  will  unite  in  rotating  the  leg  out- 
wards. When  the  knee  is  extended,  the  long  head  will  have  a  slight  influence  in 
rotating  the  hip  outwards.  Acting  from  below,  the  long  head  Avill  assist  in  raising 
the  brxly  from  the  stooping  position. 

Relations. — Behind,  the  gluteus  maximus,  the  plantaris,  the  outer  head  of 
the  gastrocnemius,  gluteus  maximus,  fascia  lata,  and  the  small  sciatic  nerve.  In 
front,  the  tendon  of  the  semi-memVtranosus,  the  adductor  magnus,  and  the  great 
sciatic  nerve.  Upon  its  inner  Ijorder  lie  the  semi-tendinosus,  scmi-membranosus, 
and  the  external  popliteal  nerve.  Beneath  the  lower  tendon  is  a  bursa  which  sep- 
arates it  from  the  external  lateral  ligament  of  the  knee-joint. 

Variations. — The  short  head  of  the  biceps  may  be  absent.  Accessory  heads  may  be  derived 
from  tlie  tuber  ischii,  tlie  upper  part  of  the  linea  aspera,  the  fascia  lata,  or  the  iimer  surface  of 
the  tendou  of  insertion  of  the  gluteus  maximus.     It  may  send  a  sHp  to  the  gastrocnemius. 


364  THE  MUSCLES 


2.  SEMI-TENDINOSUS 

The  semi-tendinosus  (fig.  288) — named  from  the  long  tendon  Avhidi  forms 
the  lower  half  of  the  muscle — is  fusiform  and  somewhat  flattened. 

Origin. — By  a  tendon  which  is  common  to  it  and  the  preceding  muscle,  from 
the  lower  and  inner  of  the  facets  at  the  back  of  the  tuber  ischii. 

Insertion. — (1)  The  upper  part  of  the  inner  surface  of  the  tibia  Ijelow  and 
l)t"hind  the  insertion  of  the  gracilis;   (2)  the  deep  fascia  of  the  inner  side  of  the  leg. 

Structure. — The  rounded  and  somewhat  flattened  tendon  of  aliout  two  inches 
(.5  cm.)  in  length  is  succeeded  by  a  fusiform  mass  of  muscular  filtres,  wliich  end 
just  below  the  middle  of  the  thigh  in  a  flattened  cylindrical  tendon.  This  runs 
directly  downwards  along  the  inner  side  of  the  i)opliteal  space,  Avhere  it  can  easily 
be  felt  beneath  the  skin,  behind  and  external  to  the  tendon  of  the  gracilis,  in  com- 
pany with  which  it  passes  downwards  and  forwards  behind  the  internal  condyle  to 
its  insertion  below  the  inner  tuberosity.  From  the  lower  border  of  the  flattened 
tendon  an  aponeurosis  passes  downwards  to  the  deep  fascia  of  the  leg.  The  fleshy 
part  of  the  muscle  is  crossed  about  its  middle  by  a  thin  tendinous  intersection 
running  downwards  and  outwards. 

Nerve-supply. — From  the  first,  second,  and  third  nerves  of  the  sacral  plexus 
by  means  of  l)ranches  from  the  great  sciatic  nerve  which  enter  the  outer  i»art  of 
the  deep  surface  of  the  muscle  two  or  three  inches  (about  6  cm. )  l)elow  the  tulier 
ischii. 

Action. — To  extend  the  hip  and  flex  the  knee,  and  when  the  knee  is  flexed  to 
rotate  the  leg  inwards.  Acting  from  below,  it  lifts  up  the  body  from  the  stooping 
position. 

Relations. — Behind,  the  gluteus  maximus  and  fascia  lata;  on  its  outer  side  the 
biceps;  in  front,  the  semi-meml^ranosus,  adductor  magnus,  and  near  the  knee  the 
gracilis,  sartorius,  and  the  inner  head  of  the  gastrocnemius.  The  large  Inirsa 
beneath  the  sartorius  tendon  also  Avraps  round  the  lower  part  of  the  tendon  of  the 
semi-tendinosus,  and  separates  it  from  the  internal  lateral  ligament  of  the  knee- 
joint. 

3.  SEMI-MEMBRANOSUS 

The  semi-membranosus  (fig.  288) — named  from  the  broad  membrane-like 
aponeurosis  which  forms  the  upper  third  of  the  muscle — is  strong,  flattened,  and 
fusiform. 

Origin. — The  anterior  and  upper  of  the  facets  upon  the  back  of  the  tuljer  ischii. 

Insertion. — (1)  The  lower  part  of  the  jiosterior  extremity  of  the  groove  upon 
the  l)ack  and  inner  side  of  the  inner  tuberosity  of  the  til)ia;  (2)  by  a  band  of  filires 
which  pass  upwards  and  outwards  to  the  upper  and  back  part  of  the  external 
condyle  of  the  femur,  and  blend  with  the  posterior  ligament  of  the  knee-joint;  (3) 
by  a  broad  expansion  which,  passing  dowuAvards  and  outwards  from  its  insertion 
into  the  inner  tuberosity  to  the  oblique  line  at  the  back  of  the  tibia,  forms  the 
aponeurosis  which  invests  the  posterior  surface  of  the  popliteus;  (4)  a  few  fibres 
pass  downwards  and  forwards  from  the  lower  liorder  of  its  tiljial  insertion  to  lilend 
with  the  internal  lateral  ligament. 

Structure. — Tlie  upper  part  of  the  muscle  consists  of  a  strong  flat  tendon  about 
three-ijuarters  of  an  inch  (nearly  2  cm.)  Ijroad,  which  extends  along  the  outer 
})order  of  the  muscle  to  the  middle  of  the  thigh.  The  tendon  of  insertion  is  not 
quite  so  l)road  luit  nmch  thicker,  and  reaches  upon  the  inner  border  of  the  nniscle 
also  as  high  as  the  middle  of  the  thigh.  Between  these  two  tendons  the  nuiscular 
fibres  which  are  comparatively  short  pass  downwards  and  inwards,  Ix'ginning 
upon  the  upper  tendon  about  four  inches  (10  cm.)  below  the  tuber  ischii,  and 
ending  upon  the  lower  tendon  close  to  the  upper  part  of  the  inner  condyle.  The 
nuiscle  has  therefore  a  very  distinctly  penniform  arrangement,  but  it  is  peculiar  in 
this  respect  that  the  fleshy  filires  are  at  each  extremity  attached  to  a  tendon,  and 
are  not,  as  is  usually  tlie  case,  at  one  extremity  attaclied  to  the  bone.  It  is  also 
unusual  for  a  muscle  to  have  so  long  a  tendon  at  its  i)roximal  end.      One  effo'ct  of 


QUADRICEPS  EXTENSOR  3G5 

this  armngement  is  to  allow  of  the  free  action  of  the  long  head  of  the  l:)iceps 
which  crosses  over  this  part  of  the  senii-niemhranosiis.  Otherwise  the  swelling 
of  the  fibres  of  the  biceps  during  contraction  might  have  pressed  upon  and  inter- 
fered with  the  action  of  the  senii-menibranosus,  which  usually  contracts  at  the 
same  time. 

Nerve-supply. — From  the  first,  second,  and  third  nerves  which  enter  into  the 
formation  of  the  sacral  plexus  through  the  great  sciatic  nerve  which  sends  l^ranches 
to  the  deep  surface  of  the  muscle  al)out  the  middle  of  the  thigh. 

Action. — To  strongly  extend  the  hip  and  to  flex  the  knee.  When  the  knee  is 
flexed  it  will  also  assist  in  the  internal  rotation  of  the  leg,  but  with  less  mechanical 
advantage  than  the  semi-tendinosus  and  gracilis,  as  its  line  of  action  is  so  near  to 
the  axis  of  movement. 

Like  most  penniform  muscles,  the  semi-membranosus  is  very  powerful,  as  is 
shown  by  the  thickness  of  its  tendons.  This  strength  is  necessitated  by  the  fact 
that  its  line  of  action  is  so  much  nearer  to  the  axis  of  movement  both  in  flexion 
and  rotation  inwards  of  the  knee.  Like  the  other  muscles  which  arise  from  the 
tuber  ischii,  it  will  co-operate  powerfully  in  raising  the  body  from  the  stooping 
position,  this  prominence  of  bone  forming  the  short  arm  of  the  lever  by  which  the 
trunk  is  raised.  This  group  of  muscles  affords  a  good  example  of  the  peculiar 
action  obtained  by  long  muscles  passing  over  two  joints.  If  all  three  muscles  were 
to  remain  passive,  like  so  many  ligaments,  it  is  oljvious  that  on  flexion  of  the  hip- 
joint  l)y  means  of  the  ilio-psoas  and  other  muscles,  the  hamstrings  would  ensure 
the  simultaneous  flexion  of  the  knee;  or,  again,  on  extension  of  the  knee  by  the 
action  of  the  powerful  muscles  of  the  front  of  the  thigh,  the  hamstrings  would 
produce  a  corresponding  extension  of  the  hip-joint.  Seeing,  however,  that  these 
hamstrings  are  not  passive,  but  that  they  contract  powerfully  at  the  same  time  in 
man}'  of  these  movements,  it  follows  that  in  flexion  of  the  hip  in  such  movements 
as  those  of  running,  the  knee  is  at  the  same  time  flexed  with  increased  raj^idity; 
and  again,  when  the  knees  are  extended  by  the  powerful  contraction  of  the 
quadriceps  muscle,  the  simultaneous  action  of  the  hamstring  muscles  will  produce  a 
still  more  rajiid  elevation  of  the  trunk. 

Relations  of  the  semi-membranosus. — Behind,  the  gluteus  maximus,  biceps, 
and  semi-tendinosus;  in  front,  the  adductor  magnus,  posterior  ligament  of  knee, 
and  the  popliteus.  Along  its  outer  border  lies  the  great  sciatic  nerve,  and  just 
before  its  insertion  the  inner  head  of  the  gastrocnemius  hooks  round  this  border, 
being  separated  from  it  by  a  bursa  which  communicates  with  the  knee-joint.  There 
is  also  usually  a  small  bursa  l^etween  its  tendon  and  the  back  of  the  inner  tuberosity 
of  the  tibia. 

Variations. — The  semi-membranosus  has  occasionally  been  deficient,  or  only  represented  by  a 
tliiu  musfulo-tendinous  band.     It  has  also  been  found  double. 


AXTERIOR  MUSCLES  OF  THE  THIGH 

This  group  consists  of  the  sartorius  and  the  (quadriceps  extensor. 

1.  SARTORIUS 
This  musclf  has  already  Ijeen  described  (see  page  350). 

2.  QUADRICEPS  EXTENSOR 

The  quadriceps  extensor  ( tigs.  287  and  289),  as  its  name  implies,  consists 
of  four  heads.  Of  these,  one,  the  rectus,  arises  from  the  innominate  bone;  and 
the  three  others,  the  vastus  externus,  vastus  internus,  and  crureus.  from  the  femur; 
while  the  common  tendon  is  inserted  into  the  upper  border  and  sides  of  the  patella. 


3GG  THE  MUSCLES 

(a)  Rectus  Femoris 

The  rectus  femoris — named  from  its  long  straight  course — is  strong,  fusiform, 
and  flattfiK'd  from  Ijefore  backwards;  it  arises  l)y  an  anterior  and  a  posterior  head. 

Origin. — Anterior  head,  from  the  front  of  the  anterior  inferior  spine  of  the  iUum; 
posterior  head,  from  the  upper  surface  of  the  rim  of  the  acetabuhnn  just  external  to 
the  attachment  of  the  capsular  ligament. 

Insertion. — Tlie  front  of  the  upper  border  of  the  patella. 

Structure. — This  muscle  consists  of  two  strong  tendinous  expansions  joined  by 
fleshy  fibres.  The  upper  expansion  is  formed  aliove  by  the  union  of  the  two 
tendinous  heads  in  a  small  arch,  whicli  is  intimately  connected  with  the  capsule  of 
the  hip-joint.  From  this  arch  the  tendinous  expansion  descends  upon  the  front  of 
the  muscle  as  far  as  the  middle  of  the  thigh,  getting  thinner  and  narroAver  as  it 
descends.  The  tendon  of  insertion  begins  upon  the  back  of  the  muscle  also  al:)out 
the  middle  of  the  thigh,  and  soon  expands  into  a  broad  aponeurosis  which  covers 
the  back  of  the  muscle  at  its  lower  end;  about  three  inches  (T'o  cm.)  above  the 
patella,  it  becomes  free  of  muscular  fibres,  and  forms  a  strong  tendinous  band  which 
is  inserted  into  the  upper  border  of  the  patella.  The  fleshy  fil>res  pass  from  the 
back  and  sides  of  the  upper  expansion  to  the  front  and  sides  of  the  tendon  of  inser- 
tion. Seen  from  the  front,  these  fleshy  fil^res  appear  to  diverge  on  both  sides  from 
the  upper  expansion,  and,  after  passing  round  the  border  of  the  muscle,  they 
converge  upon  the  tendon  of  insertion  so  as  to  give  the  muscle  a  bipenniform 
appearance. 

Nerve-supply. — From  the  lumbar  plexus  (through  the  second,  third,  and 
fourtli  lumliar  nerves),  by  the  anterior  crural  nerve  Avhich  sends  filaments  to  the 
posterior  aspect  of  the  muscle  in  the  upper  half  of  its  course. 

Action. — To  assist  in  the  powerful  extension  of  the  knee  by  the  quadriceps.  It 
W'ill  also  help  in  flexion  of  the  hip;  and  it  Avill  be  a  powerful  agent  in  preventing 
dislocation  of  the  head  of  the  femur.  When  the  hip-joint  is  flexed,  the  muscle  will 
act  chiefly  from  its  posterior  head;  but  when  the  hip  is  extended,  the  anterior  head 
of  tlie  nniscle  will  act  with  more  power. 

Relations. — In  front  lie  the  sartorius,  tensor  vaginae  femoris,  and  the  fascia 
lata;  l)ehind.  it  lies  on  the  hip-joint  and  the  crureus  muscle;  upon  its  inner  border 
above  is  the  iliacus;  and  outside  it  lie  the  gluteus  medius  and  minimus. 

(b)  Vastus  Externus 

The  vastus  externus — named  from  its  great  size  and  its  position  upon  the 
outer  surface  of  the  thigh — is  a  thick  rhomljoidal  sheet. 

Origin. — (1)  The  upper  half  of  the  anterior  intertrochanteric  line  and  tlie  front 
of  the  upper  part  of  the  femur  along  the  anterior  Ijorder  of  the  greater  trochanter; 
(2)  a  horizontal  line  which  forms  the  loAver  border  of  the  greater  trochanter;  (3)  the 
outer  lip  of  the  gluteal  ridge;  (4)  the  upper  half  of  the  outer  lip  of  the  Hnea  aspera 
and  the  adjacent  portion  of  the  shaft  of  the  femur  for  about  one-sixth  of  an  inch 
(4  mm. ) ;  (5)  the  external  intermuscular  septum  in  the  neighl:)Ourhood  of  its  attach- 
ment to  tlie  linea  aspera. 

Insertion. — (1)  The  outer  half  of  the  upper  1,)order  of  the  patella.  ])ehind 
the  preceding  tendon,  Avith  which  it  also  blends;  (2)  the  u})i)er  third  of  the 
outer  l:)order  of  the  patella;  (3)  by  an  aponeurosis  Avhich  is  inserted  partly 
into  the  front  of  the  external  tuberosity  of  the  ti]>ia,  partly  into  the  deej)  fascia 
of  the  leg. 

Structure. — Arising  partly  directly  from  the  bone,  and  partly  by  a  strong  apo- 
neurosis Avhieh  covers  the  outer  surface  of  the  muscle  in  its  upper  "tAvo-thirds,  the 
fleshy  fibres  run  parallel  to  one  another  downAvards,  forAA'ards,  and  iuAvards,  at 
the  same  time  curving  slightly  as  they  pass  over  the  rounded  mass  formed  l>y  the 
crureus  muscle.  The  aponeurosis  of  insertion  lies  upon  the  inner  surface  of  the 
muscle  and  receives  fleshy  fibres  to  Avitliin  one  inch  (2-5  cm.)  of  its  insertion  into 
the  patella  and  its  l)lending  Avith  tlie  other  tendons  of  the  quadriceps  muscle.  Upon 
its  anterior  surface  it  unites  Avith  tlie  tendon  of  the  rectus  muscle,  and  ui)(>n  its 
posterior  surface  is  received  a  ]iart  of  the  insertion  of  the  crureus. 

Nerve-supply. — From   the  anterior  crural  (through  the  second,   tliinl.   and 


QUADRICEPS  EXTENSOR  307 

fourth  lumbar  nerves),  l)y  several  l)ranehes  which  enter  the  internal  surface  of  the 
muscle  in  the  upjxT  tliinl  of  the  thigh. 

Action  and  relations. — These  will  be  considered  with  those  of  the  two  follow- 
ing muscles. 

(c,  d)  Vastus  Ixternus  and  Crureus 

The  vastus  internus  and  crureus  are  so  closely  blended  that  it  is  better  to 
describe  their  origins  together  Itefore  mentioning  the  way  in  which  they  may  be 
separated.  They  have  received  their  names,  the  former  from  its  size  and  position; 
the  latter  from  its  intimate  connexion  with  the  whole  of  the  front  of  the  thigh  bone, 
the  term  '  cms  '  being  often  used  synonymously  with  the  femur.  The  blended 
nniscle  is  a  somewhat  fusiform  sheet  which  is  so  curved  laterally  as  to  form  a 
cylinder  embracing  the  Avhole  of  the  front  and  sides  of  the  shaft  of  the  femur. 

Origin. — (1)  The  outer  lip  of  the  lower  half  of  the  linea  asperaand  its  external 
bifurcation,  together  with  the  adjacent  external  intermuscular  septum;  (2)  the 
lower  part  of  the  anterior  intertrochanteric  line  and  the  spiral  line  of  the  femur; 
(3)  the  inner  lip  of  the  whole  length  of  the  linea  aspera  and  its  internal  bifurcation, 
together  Avith  the  adjacent  part  of  the  internal  intermuscular  septum,  and  the  front 
of  the  tendon  of  the  adductor  magnus;  (4)  the  greater  part  of  the  front  and  sides  of 
the  femur  within  the  limits  formed  l:)y  the  three  preceding  attachments  and  the 
origin  of  the  vastus  externus. 

Insertion. — (1)  The  front  aspect  of  the  upper  border  of  the  patella  immedi- 
ately Ijehind  the  insertion  of  the  rectus  femoris  tendon;  (2)  the  upper  half  of  the 
inner  border  of  the  patella;  (3)  by  a  strong  aponeurosis  into  the  front  of  the  inner 
tuberosity  of  the  tiVjia  and  into  the  adjacent  deep  fascia  of  the  leg. 

Structure. — The  fibres  of  this  large  muscle  arise  fleshy  from  the  surface  of  the 
femur  and  converge,  from  the  outer  side  downwards,  forwards,  and  inwards;  from 
the  front  directly  downwards;  from  the  inner  side  downwards,  forwards,  and  out- 
wards, upon  the  back  and  sides  of  a  strong  aponeurosis  which  covers  the  front  of 
the  muscle  from  about  the  middle  of  the  thigh  downwards.  The  filjres  which  arise 
from  the  tendon  of  the  adductor  magnus  and  the  adjacent  intermuscular  septum 
form  the  lowest  part  of  the  thick  muscular  belly  of  the  vastus  internus,  and  are 
directed  almost  transversely  outwards  to  get  to  their  insertion  upon  the  inner  border 
of  the  patella.  The  substance  of  the  muscle  is  arranged  in  layers  which  wrap  round 
the  front  and  sides  of  the  femur;  and  betw^een  the  attachment  of  these  layers  to 
the  bone,  longitudinal  strips  of  bone  may  be  found  upon  dissection  without  any 
muscular  attachment.  The  deepest  of  these  layers  in  the  lower  fourth  of  the  thigh 
forms  a  separate  sheet  of  muscular  fibre,  sometimes  called  the  subcrureus,  which 
is  inserted  into  the  upper  reflexion  of  the  synovial  membrane  of  the  knee-joint. 
Beneath  this  muscle  is  the  bursa  underneath  the  C}uadriceps,  Avhich  in  the  adult 
connnunicates  with  the  upper  part  of  the  knee-joint. 

A  somewhat  arbitrary  division  may  be  made  between  the  vastus  internus  and 
crureus  by  dissecting  at  the  lower  third  of  the  thigh  in  a  line  with  the  inner  border 
of  the  patella.  ^Vith  a  few  touches  of  the  scalpel  a  longitudinal  separation  may  be 
made  clear,  which  extends  upwards  to  the  lower  part  of  the  anterior  intertro- 
chanteric line.  The  part  of  the  muscle  external  to  this  line  is  the  crureus,  and  the 
part  internal  the  rnsfns  iufrrn'is. 

The  ligamentum  patellae  may  lie  looked  upon  as  the  common  tendon  of  the 
quadriceps.  It  is  a  Ijand  of  lil)rous  tissue  about  an  inch  (2"5  cm.)  broad  by  one- 
quarter  of  an  inch  (Gnmi.)  thick,  and  two  or  three  inches  (5  to  7 '5  cm.)  in 
length,  which  is  attached  above  to  the  apex  and  to  the  hiwer  part  of  the  jjosterior 
surface  of  the  patella;  and,  after  passing  downwards  and  very  slightly  outwards, 
it  is  inserted  into  the  anterior  surface  of  the  tubercle  of  the  tibia.  Attached  to 
its  sides  are  strong  aponeuroses  by  which  the  lower  fibres  of  the  vastus  externus 
and  vastus  internus  and  the  ilio-tibial  band  are  inserted  into  the  tuberosities  of  the 
tibia,  and  which  Ijlend  on  their  deep  surface  with  the  lower  part  of  the  capsule  of 
the  knee-joint. 

Nerve-supply. — Xumerous  branches  from  the  anterior  crural  are  distrilnited 
to  the  upper  half  of  the  front  of  the  crureus  muscle  and  to  the  inner  surface  of  tlie 
vastus  internus  at  the  junetiim  of  the  middle  and  lower  thirds  of  the  thigh,  the 


368  THE  MUSCLES 

nrrve  to  the  vastus  internus  beiiiir  a  large  and  conspicuous  branch  wliich  lies  close 
to  the  outer  side  of  the  superticial  femoral  artery  in  the  upper  part  of  Hunter's 
canal. 

Action. — The  vastiis  externus,  crureus,  and  vastus  internus,  together  with  the 
rectus  fenioris,  extend  powerfully  the  knee.  Their  intermediate  insertion  into 
the  sesamoid  bone  formed  by  the  patella  serves  to  lift  from  the  line  of  the  tibia  the 
ligamentum  patelhe,  which  may  be  looked  upon  as  the  lower  part  of  their  common 
tendon.  The  enormous  power  of  the  whole  of  this  combination  of  muscles  is 
necessitated  partly  by  the  fact  that  the  whole  of  the  weight  of  the  body  has  to  be 
raised  by  it,  and  partly  by  the  great  mechanical  disadvantage  which  results  from 
the  short  arm  of  the  lever  upon  which  the  tendon  acts,  and  the  obliquity  of  its 
insertion. 

On  account  of  the  direction  of  the  femur,  which  is  downwards  and  inwards,  the 
tendency  of  the  quadriceps  is  to  draw  the  patella  outwards  at  the  same  time  as  up- 
wards. This  is  in  some  degree  counteracted  by  the  position  and  direction  of  the 
vastus  internus.  The  great  mass  of  the  fibres  of  this  part  of  the  quadriceps  arises  in 
the  lower  part  of  the  thigh,  and  is  directed  so  transversely  outwards  towards  the 
inner  border  of  the  patella,  that  when  it  contracts  it  tends  to  draw  the  patella 
inwards  as  well  as  upwards,  and  so  the  resviltant  of  the  various  divisions  of  the 
(juadriceps  when  contracting  simultaneously  is  to  draw  the  patella  more  directly 
upwards.  If  it  were  not  for  this  arrangement,  the  contraction  of  the  quadriceps 
would  have  a  strong  tendency  to  produce  outward  dislocation  of  the  knee-cap. 

Relations  of  vastus  externus,  crureus,  and  vastus  internus. — In  front  lie 
the  fascia  lata,  tensor  vaginse  femoris,  rectus  femoris,  and  sartorius.  To  the  inner 
side  lie  the  femoral  vessels  and  anterior  crural  nerve.  On  the  outer  side  are  the 
gluteus  minimus  and  maximus.  Behind  are  the  biceps  on  the  outer  side  of  the 
femur,  and  the  adductor  longus  and  magnus  on  the  inner  side. 

Variations. — These  are  few  in  number.  An  accessory  head  to  the  rectus  from  the  anterior 
superior  ^yime  of  the  iUum  has  been  described,  and  occasionally  the  outer  head  is  absent. 


THE  DEEP  FASCIA  OF  THE  LEG  AND  ANNULAR  LIGAMENTS 

The  deep  fascia  of  the  leg  is  continuous  above  with  the  fascia  lata  of  the  thigh 
and  receives  imj^ortant  additions  from  the  tendons  of  the  quadriceps,  biceps, 
sartorius,  gracilis,  and  semi-tendinosus.  It  is  also  attached  to  the  lower  j)art  of  the 
outer  and  inner  tuberosities  of  the  tibia  and  to  the  head  of  the  fibula.  At  the  liack 
of  the  knee  it  is  strengthened  by  transverse  fibres  which  serve  to  bind  together  the 
muscles  which  form  the  boundaries  of  the  popliteal  space;  the  external  saphenous 
vein  also  perforates  it  about  the  centre  of  the  space.  It  is  very  thick  and  strong 
at  the  upper  and  outer  part  of  the  front  of  the  leg;  but  behind,  where  it  covers  the 
muscles  of  the  calf,  the  fascia  becomes  much  thinner.  The  internal  surface  of  the 
tibia  is  not  covered  by  this  fascia,  which  blends  with  the  periosteum  covering  its 
anterior  and  inner  borders  throughout  their  whole  length.  It  is  also  attached  to  the 
borders  of  the  fibula  by  two  strong  intermuscular  septa  which  form  the  anterior  and 
posterior  walls  of  a  compartment  containing  the  long  and  short  peronei.  In  the 
lower  third  of  the  leg  it  is  attached  to  the  borders  of  the  subcutaneous  surface  of 
the  fibula.  In  the  neiglibourhood  of  the  ankle  the  deep  fascia  is  thickened  by  the 
addition  of  numerous  transverse  fibres,  and  forms  the  annular  ligaments. 

The  anterior  annular  ligament  (fig.  298)  consists  of  two  parts,  an  upper  and 
a  loicer.  The  upjicr  purl  is  a  strong  band  of  transverse  fibres  just  above  the  ankle- 
joint,  which  extends  from  the  anterior  border  of  the  tibia  to  the  anterior  border  of 
the  subcutaneous  surface  of  the  fibula.  Behind  it  there  is  a  separate  synovial 
sheath  for  the  tendon  of  the  tibialis  anticus.  The  Inwer  part  of  the  anterior  annular 
ligament  arises  from  the  u])])er  surface  and  outer  border  of  the  great  process 
of  the  calcaneuni  in  two  bands,  a  su])erficial  and  a  deep,  which,  passing  trans- 
versely inwards,  unite  after  a  course  of  about  an  inch  (2-5  cm.),  and  thus  form 
a  loop  in  which  are  contained  the  tendons  of  the  extensor  longus  digitorum  and  the 
peroneus  tertius,  together  with  part  of  the  origin  of  the  extensor  brevis  digitorum. 


GASTROCNEMIUS  369 

From  the  inner  extremity  of  this  loop,  two  l)ands  of  fil)res  of  varying  distinctness 
proceed:  one  passes  upwards  and  inwards  to  join  the  front  border  of  the  internal 
malleolus;  the  other,  which  is  usually  the  weaker,  more  directly  inwards  over  the 
scaphoid  l)one  to  join  the  inner  border  of  the  plantar  fascia.  Beneath  this  inner  por- 
tion of  the  lower  part  of  the  anterior  annular  ligament  the  tendons  of  the  extensor 
proprius  hallucis  and  til)ialis  anticus  are  contained  in  sejjarate  synovial  sheaths. 

The  external  annular  ligament  passes  from  the  posterior  border  of  the  external 
malleolus  to  the  outer  border  of  the  tuberosity  of  the  calcaneum  and  to  the  posterior 
part  of  the  junction  of  the  lower  and  outer  surfaces  of  the  calcaneum.  It  is  con- 
tinuous aV)ove  with  the  deep  fascia  covering  the  calf  muscles  and  the  peronei;  and 
also  with  the  sheet  of  fascia  which  separates  the  two  superficial  from  the  two  deeper 
layers  of  nuiscles  at  the  back  of  the  leg.  Its  deep  surface  is  attached  to  the  pero- 
neal tubercle  on  the  outer  side  of  the  calcaneum. 

The  internal  annular  ligament  extends  from  the  posterior  border  of  the 
internal  malleolus  to  the  inner  border  of  the  tuberosity  of  the  calcaneum.  It  is 
also  continuous  above  with  the  deep  fascia  of  the  leg  and  with  the  sheet  of  fascia 
which  intervenes  between  the  soleus  and  the  deeper  layers  of  muscle  at  the  back  of 
the  leg. 


MUSCLES  OF  THE  BACK  OF  THE  LEG 

The  muscles  in  this  region  are  arranged  in  two  layers  above,  in  four  below, 
The  first  layer  consists  of  the  gastrocnemius  and  plantaris. 


First  Layer 

1.  GASTROCNEMIUS 

The  gastrocnemius — named  from  ya<jrr,p  =  the  belly,  and  x^rj/irj  =  the  calf, 
because  it  forms  the  enlargement  of  that  part  of  the  leg — is  dou)>le-headed,  each 
head  consisting  of  a  fusiform  mviscle,  the  lower  part  of  which  blends  with  its  fellow 
so  as  to  form  a  common  tendon  of  insertion.  These  two  heads  constitute  the 
femoral  origin  of  the  great  triceps  sura?  muscle. 

Origin. — Outer  head  :  a  Avell-markecl  impression  upon  the  upper  and  posterior 
part  of  the  outer  surface  of  the  external  condyle  and  the  adjacent  part  of  the 
})Osterior  surface  of  the  fenmr  just  above  the  external  condyle. 

Inner  head  :  an  oval  impression  placed  transversely  across  the  posterior  surface 
of  the  femur  above  the  internal  condyle,  and  reaching  inwards  to  the  back  of  the 
adductor  tul)ercle. 

Insertion. — By  the  tendo  Achillis  (so  named  from  the  legend  that  the  heel, 
into  which  this  tendon  is  inserted,  was  the  only  vulnerable  part  of  the  hero 
Achilles)  into  the  middle  area  on  the  posterior  surface  of  the  calcaneum. 

Structure. — The  two  heads  arise  by  short  strong  tendons;  that  of  the  inner 
is  the  stronger  and  thicker.  These  tendons  converge  downwards,  and  are  suc- 
cei'ded  l)y  large  fleshy  expansions  which  unite  at  the  ui)per  p)art  of  the  middle 
third  of  the  leg.  Near  this  })oint  the  tendon  of  insertion  begins  as  an  internuis- 
cular  septum  between  the  two  bellies  of  the  muscle.  This  becomes  thicker  and 
stronger,  and  expands  into  a  ]>road  aponeurosis  which  covers  the  anterior  surface  of 
the  united  muscle.  Just  below  the  middle  of  the  leg  the  fleshy  fibres  temiinate 
upon  the  back  of  this  aponeurosis  in  two  curves  the  convexity  of  which  is  down- 
wards, that  of  the  inner  portion  of  the  nuiscle  descending  about  half  an  inch 
(1"2  cm.)  lower  than  the  outer.  The  strong  aj)oneurosis  becomes  narrower  and  at 
the  same  time  thicker,  and  after  receiving  the  fibres  of  the  soleus  muscle  is  known 
by  the  name  of  the  tendo  Achillis. 
24 


370 


THE  MUSCLES 


Fig.  -291.— SuPKaFic'iAL  Muscles  of  the  Back  of  the  Thigh  and  Leg. 


Gluteus  mediue 


Aponeurosis  of  gluteus  maximus 


■  Gluteus  maximus 


-  Semi-membraiiosu3 


BicepE 


Vastus  eiternuB 


<   M 


-  Seini-tendinosus 


■Gracilis 

"Teudou  of  semi-tnembranosus 


Qastrocnemius  - 


Feroneua  longua  - 


Flexor  longus  digitorum 


—  Tendo  Achillis 


PLANTARIS—POPLITEUS  371 

Nerve-supply. — From  the  internal  j)()})liteal  l)ranch  of  the  ^reat  sciatic  nerve, 
which  sends  sural  branches  to  the  adjacent  portions  of  the  anterior  surfaces  of  the 
two  heads,  in  the  upper  third  of  the  leg. 

Action. — Its  action  will  l)e  described  with  that  of  the  soleus,  which  forms  a 
part  of  the  same  muscle. 

Relations. — Behind,  the  deep  fascia,  the  external  saphenous  vein  and  nerve, 
and  the  connnunicans  peronei  nerve.  Between  the  two  heads  above  is  the  plantaris 
muscle.  In  front  lie  the  knee-joint,  the  tendon  of  the  semi-nrembranosus,  the  pop- 
liteus,  the  i)lantaris  tendon,  the  soleus,  the  popliteal  vessels,  and  internal  jxtpliteal 
nerve.  On  the  outer  side,  aljove,  are  the  biceps  tendon,  and  external  po})lilcal 
nerve;  on  the  inner  side,  above,  are  the  tendons  of  the  semi-tendinosus,  gracilis, 
sartorius,  and  adductor  magnus.  A  bursa  lying  beneath  its  inner  head  separates 
it  from  the  tendon  of  the  semi-membranosus,  and  communicates  with  the  knee-joint. 

Variations. — The  most  comnion  variation  is  the  addition  of  a  third  head  from  the  posterior 
surface  of  the  lower  end  of  the  femur.  This  may  cross,  or  even  run  between,  the  popliteal 
vessels. 

2.   PLAXTARIS 

The  plantaris — named  from  its  occasional  attachment  to  the  fascia  covering  the 
sole  of  the  foot  (  ^plaitta) — is  a  fusiform,  sonjewhat  flattened  muscle  with  a  very 
long  ribbon-shaped  tendon. 

Origin. — (1)  The  lower  two  inches  (5  cm. )  of  the  outer  condylar  ridge  together 
with  the  posterior  surface  of  the  femur  immediately  below  that  ridge;  and  (2) 
the  adjacent  part  of  the  posterior  ligament  of  the  knee-joint. 

Insertion. — The  inner  side  of  the  lower  portion  of  the  posterior  surface  of  the 
calcaneum;  sometimes,  however,  it  Ijlends  with  the  inner  l)order  of  the  tendo 
Achiliis,  and  sometimes  it  is  continued  into  the  inner  division  of  the  plantar  fascia. 

Structure. — Arising  fleshy ,  the  fibres  of  this  small  muscle  have  a  somewhat 
penniform  arrangement  and  converge  upon  the  thin  tendon,  which  ap})ears  first  on 
the  inner  side  of  the  muscle,  and  soon  l^ecoming  free,  runs  downwards  and  slightly 
inwards  across  the  calf  between  the  gastrocnemius  and  the  soleus.  In  the  lower 
third  of  the  leg  it  lies  along  the  inner  jjorder  of  the  tendo  Achiliis,  with  which  it  is 
sometimes  l)lended. 

Nerve-supply. — From  the  internal  popliteal  Ijranch  of  the  great  sciatic  nerve 
by  a  small  filament  which  enters  the  deep  aspect  of  the  muscle  near  the  upper  part 
of  its  inner  border. 

Action. — This  vestigial  muscle  is  a  feeble  extensor  of  the  ankle  and  a  flexor  of 
the  knee-joint.  By  its  attachment  to  the  posterior  ligament  of  the  knee-joint  it  will 
tend  to  draw  liackwards  that  ligament  during  flexion  of  the  knee,  and  so  prevent  its 
being  caught  between  the  articular  surfaces. 

Relations. — Behind  lie  the  fascia  of  the  popliteal  space,  the  biceps,  the  gastroc- 
nemius, and  the  external  popliteal  nerve;  in  front  are  the  popliteal  vessels  and 
internal  popliteal  nerve,  the  popliteus  muscle  and  the  soleus. 

Variations. — In  addition  to  the  above-mentioned  variations  in  the  point  of  insertion,  this 
muscle  may  sometimes  be  double  at  its  origin,  and  it  is  not  unfrequeutlj'  absent. 


Second  Layer 

The  second  layer  is  formed  above  by  the  popliteus,  which  is  covered  behind  by 
the  aponeurosis  derived  from  the  semi-membranosus;  and  below  l)y  the  soleus, 
which  is  the  lower  head  of  the  great  triceps  sura3  muscle. 


1.   POPLITEUS 

The  popliteus  (fig.   202) — named  from  its  position  on  the  floor  of  the  ham 
(^:=: pnphs  ) — is  a  triangular  sheet. 

Origin. — The  bottom  of  the  anterior  portion  of  a  horizontal  groove  on  the  lower 


372  THE  MUSCLES 

part  of  the  outer  surface  of  the  external  condyle  of  the  femur;  also  by  a  small  slip 
from  the  posterior  ligament  of  the  knee-joint. 

Insertion. — (1)  The  back  of  the  tibia  from  below  the  attachment  of  the  pos- 
terior ligament  of  the  knee-joint  to  the  oblique  line;  (2)  the  fascia  derived  from 
the  tendon  of  the  semi-memljranosus,  which  covers  the  posterior  surface  of  the 
muscle. 

Structure. — Arising  by  a  somewhat  flattened  cylindrical  tendon  which  passes 
at  tirst  backwards  and  slightly  downwards  within  the  knee-joint,  grooving  the 
posterior  border  of  the  external  semilunar  cartilage;  it  then  escapes  from  tlie  capsule 
of  the  knee-joint,  receiving  a  small  slip  from  the  posterior  ligament,  and  innne- 
diately  expands  into  a  fan-shaped  muscle  which  forms  a  thick  sheet,  covering  the 
upper  fourth  of  the  back  of  the  tibia,  and  is  inserted  by  fleshy  fibres  into  the  pouch 
formed  by  the  bone  in  front  and  the  aponeurosis  derived  from  the  semi-membra- 
nosus  behind.  The  tendon  of  origin  is  surrounded  by  synovial  membrane,  which 
is  reflected  upon  it  aljout  half  an  inch  (1'2  cm.)  beyond  the  opening,  through 
which  it  emerges  from  the  posterior  ligament  of  the  knee-joint. 

Nerve-supply. — From  the  sacral  plexus  by  the  internal  popliteal  division  of  the 
great  sciatic  nerve,  which  sends  a  special  branch  round  the  lower  border  of  the 
muscle  to  distribute  itself  to  the  lower  part  of  its  deep  or  anterior  surface. 

Action. — To  flex  the  knee,  which  it  will  do  but  feebly  on  account  of  the 
obliquity  of  its  direction  and  its  proximity  to  the  axis  of  the  joint.  When  the  knee 
is  flexed  it  will  act  as  an  internal  rotator  of  the  leg.  In  this  position  the  tendon  of 
origin  lies  wholly  in  the  groove  for  its  reception  upon  the  outer  surface  of  the 
external  condyle.  It  is  possible  that  the  attachment  of  the  tendon  of  origin  to  the 
posterior  ligament  of  the  knee  may  enable  the  muscle  when  it  contracts  to  draw 
backwards  the  ligament,  and  so  prevent  the  synovial  membrane  upon  the  anterior 
aspect  of  the  ligament  from  being  nipped  lietween  the  articular  surfaces. 

Relations. — Behind,  the  aponeurosis  of  the  semi-meml)ranosus,  the  gastroc- 
nemius, plantaris,  and  the  popliteal  vessels,  the  internal  pojiliteal  nerve,  and 
the  lymphatic  glands.  In  front,  the  knee-joint.  Superficial  to  the  tendon  of  origin 
is  the  external  lateral  ligament  of  the  knee. 

Variations. — A  second  head  of  origin  has  been  seen  from  a  sesamoid  bone  in  the  outer  tendon 
of  the  gastrocnemius. 


2.  SOLEUS 

The  soleus — named  from  solea^  the  Latin  for  a  sole-fish,  because  of  the  resem- 
blance of  the  muscle  to  this  flat  fish — is  a  thick,  fusiform  sheet  which  forms  the 
lowest  head  of  the  triceps  surse  muscle. 

Origin. — (1)  The  oblicjue  line  of  the  tibia  and  the  inner  border  of  its  posterior 
surface,  from  the  lower  end  of  the  oblique  line  to  a  little  below  the  middle  of  the 
leg;  (2)  the  back  of  the  head  and  the  upper  third  of  the  outer  border  of  the 
posterior  or  flexor  surface  of  the  filjula  and  the  adjacent  external  intermuscular 
septum;  (3)  a  tendinous  arch  Avhich  stretches  across  the  interval  between  the 
upjH'r  part  of  the  back  of  the  tibia  and  fibula. 

Insertion. — By  a  strong  aponeurosis  which  l)lends  with  the  anterior  surface  of 
the  tendon  of  the  gastrocnemius,  and  forms  the  tendo  Achillis. 

Structure. — The  muscle  arises  partly  by  fleshy  fibres  and  partly  b}^  a  strong 
aponeurosis,  which  lies  in  front  of  the  fleshy  fibres,  and  is  especially  noticeable  in 
the  neighl)Ourhood  of  its  tibial  attachment.  From  the  til)ia  and  fibula  the  fibres 
pass  in  a  bipenniform  arrangement  downwards  and  towards  the  middle  line,  and 
after  a  very  short  course,  not  exceeding  two  inches  (5  cm. )  in  length,  they  l)lend 
with  the  tendon  of  insertion  which  begins  near  the  upper  part  of  the  origin  of  the 
muscle,  and  in  cross-sections  of  the  muscle  resembles  in  shape  the  letter  T;  one 
part  of  it  forming  a  broad  aponeurosis  upon  the  })osterior  surface  of  the  muscle, 
the  other  part  a  strong  tendinous  sejjtum  which  passes  forwards  from  the  middle  of 
the  broad  aponeurosis  a1)ove  mentioned,  so  as  to  separate  the  fleshy  fibres  into  two 
portions.  About  the  junction  of  the  middle  and  loAver  thirds  of  the  leg,  the  tendon 
of  insertion  joins  by  its  posterior  aspect  with  that  of  the  gastrocnemius  muscle.  l)ut 


SOLEUS  373 

upon  its  anterior  asi)oct  and  sides  it  receives  fleshy  fibres  nearly  as  far  down  as  the 
hack  of  the  ankle-joint.  The  tendo  Achillis  is  a  strong  rovnided  l)and  of  tendon 
about  three-quarters  of  an  inch  (2  cm.)  from  side  to  side,  and  about  half  as  much 
from  l)efore  backwards;  it  is  narrowest  at  the  level  of  the  ankle-joint,  and  expands 
slightly  before  it  is  inserted  into  the  lower  part  of  the  pcjsterior  surface  of  the  cal- 
caneum.  A  bursa  intervenes  between  the  tendon  and  the  smooth  upper  part  of  tlie 
])Osterior  surface  of  this  bone. 

Nerve-supply. — From  the  internal  popliteal  division  of  the  great  sciatic  nerve 
by  sural  l)ranches  which  enter  the  upper  half  of  the  muscle  upon  the  posterior 
surface;  and  lower  down  by  a  l:)ranch  from  the  posterior  tibial  nerve,  which  enters 
the  anterior  surface  of  the  muscle. 

Action. — The  chief  action  of  the  combined  gastrocnemius  and  soleus  is  to 
extend  the  ankle-joint.  It  is  an  extremel}'  powerful  muscle,  as  it  acts  with  con- 
sideral)le  mechanical  disadvantage.  The  lever  by  means  of  Avhich  it  acts  may  be 
best  descril)ed  as  one  of  the  first  order  (see  page  285);  the  lever  being  that  part  of 
the  foot  which  lies  between  the  heel  and  the  heads  of  the  metatarsal  bones,  the 
ankle  being  the  fulcrum;  a  pressure  ecjual  to  the  weight  of  the  body  being  exertt^d 
by  the  ground  at  the  anterior  extremity  of  the  lever;  and  the  arm,  at  the  end  of 
which  the  muscle  acts,  being  the  comparatively  short  distance  between  the  back  of 
the  heel  and  the  centre  of  the  ankle-joint.  When  the  ankle-j(jint  has  been  com- 
pletely extended,  this  muscle  wall  tend  to  adduct  slightly  the  foot,  and  to  invert 
the  sole,  this  movement  being  carried  out  in  the  joint  between  the  astragalus  and 
calcaneum.  Besides  extending  the  ankle,  the  gastrocnemius  will  assist  in  flexing 
the  knee-joint.  The  chief  oliject,  however,  which  aj^pears  to  be  gained  by  the 
femoral  attachment  of  this  muscle  is  the  addition  to  the  rapidity  of  extension  of 
the  foot.  Like  some  of  the  other  long  muscles  wdiich  pass  over  two  joints,  the 
gastrocnemius,  if  it  were  an  inextensible  ligament,  would  cause  extension  of  the 
ankle  as  soon  as  the  knee  was  straightened  by  means  of  the  great  quadriceps 
muscle.  Seeing,  however,  that  during  the  contraction  of  the  quadriceps  the  gas- 
trocnemius is  at  the  same  time  acting,  it  follows  that  the  ra])idity  and  amount  of 
the  extension  of  the  ankle-joint  is  almost  doubled.  By  these  means  we  obtain  that 
ra])id  and  powerful  contraction  Avhich  gives  the  spring  to  the  body  in  lea]^)ing  and 
running.  We  may  see  also  how  enormously  strong  the  tendo  Achillis  must  be, 
as  it  has  not  only  to  bear  the  contraction  of  the  gastrocnemius  and  soleus,  but  the 
additional  strain  thrown  upon  it  ])y  the  simultaneous  action  of  the  quadriceps 
extensor  of  the  knee.  The  soleus  will  assist  in  the  extension  of  the  ankle,  and  will 
even  be  able  to  perform  this  movement  somewhat  feebly  by  itself,  when  in  extreme 
flexion  of  the  knee-joint  the  gastrocnemius  is  so  relaxed  as  to  be  almost  powerless. 
It  is  much  stronger  than  the  gastrocnemius,  as  may  ])e  inferred  from  the  enormous 
nunil)er  of  short  fil)res  of  which  it  is  formed.  At  the  same  time,  however,  as  it 
only  passes  over  the  ankle  and  calcaneo-astragaloid  joints,  the  range  of  its  move- 
ments is  very  short. 

Relations. — The  soleus  is  in  relation  behind  with  the  gastrocnemius  and  plan- 
taris;  in  front,  with  the  flexor  longus  cligitorum,  flexor  longus  hallucis,  and  tibialis 
posticus,  and  with  the  posterior  til:)ial  vessels  and  nerve. 

Variations. — A  second  soleus  is  sometimes  found  beneath  the  normal  muscle,  and  more  or  less 
separate  from  it.     It  is  usually  inserted  into  the  calcaneum  or  internal  annular  ligament. 


Third  Layer 

The  third  layer  is  separated  from  the  superficial  layers  by  an  a]")oneurosis  called 
the  deep  tibial  fascia.  This  is  attached  to  the  inner  border  of  the  tibia  internally, 
and  externally  to  the  outer  l)order  of  the  flexor  surface  of  the  fibula,  and  the 
posterior  of  the  two  external  intermuscular  septa.  It  is  thin  above,  but  below  it  is 
strengthened  by  transverse  fibres,  and  becomes  much  thicker.  At  the  ankle  it 
blends  with  the  deep  fascia  of  the  leg  and  the  external  and  internal  annular 
ligaments.  The  third  layer  consists  of  two  muscles — the  flexor  longus  digitorum 
and  the  flexor  loncus  hallucis. 


374  THE  MUSCLES 


1.  FLEXOR  LONGUS  DIGITORUM  PEDIS 

The  flexor  longus  digitorum — nanu'd  from  its  being  the  longer  of  the  two 
flexors  of  the  toes — is  a  fusiform  slieet. 

Origin. — (1)  The  inner  part  of  the  posterior  surface  of  the  tibia,  beginning  with 
the  lower  lialf  of  the  oblique  line,  and  ending  about  three  inches  (7*5  cm. )  above  the 
inner  ankle;  (2)  the  front  of  the  deep  fascia  Avhich  covers  the  sheet;  (3)  a  thin  in- 
termusi'ular  septum  which  intervenes  between  this  muscle  and  the  tibialis  posticus. 

Insertion. — The  under  surface  of  the  base  of  the  ungual  phalanx  of  each  of  the 
four  outer  toes. 

Structure. — Arising  flesh v  from  the  tibia  and  adjacent  fascia?,  the  fibres  pass 
in  a  penniform  manner  into  the  front  and  outer  side  of  a  tendon  which,  beginning 
about  the  middle  of  the  leg,  gradually  becomes  thicker  and  stronger,  and  receives 
its  last  fleshy  fibres  about  two  inches  (5  cm. )  above  the  ankle-joint.  It  then 
passes  beneath  the  internal  annular  ligament  in  a  compartment  posterior  and 
external  to  that  for  the  tiV)ialis  posticus.  Thence  it  runs  downwards,  forwards,  and 
outwards  beneath  the  first  layer  of  the  sole  muscles,  and,  after  having  received 
fleshy  fibres  from  the  accessorius  pedis  and  a  small  tendinous  slip  from  the  tendon 
of  the  flexor  longus  hallucis,  divides,  aliout  half-way  between  the  tuberosity  of  the 
calcaneuin  and  the  heads  of  the  metatarsal  bones,  into  four  tendons.  These  enter 
the  theca?  of  the  four  outer  toes,  and  each  tendon  passes  through  the  splitting  of  the 
tendon  of  the  flexor  brevis  digitorum  to  its  insertion  upon  the  under  surface  of 
the  base  of  the  third  phalanx.  The  lumbricales  arise  from  its  tendons  in  the  sole 
of  tlie  foot. 

Nerve-supply. — From  the  posterior  tibial  nerve  by  liranches  which  enter  the 
superficial  aspect  of  the  muscle  near  its  outer  border  about  the  middle  of  the  leg. 

Action. — To  flex  the  last  phalanges  of  the  four  outer  toes;  it  will  then  help  to 
flex  the  second  and  first  phalanges  and  the  medio-tarsal  joint  of  the  foot.  It  will 
also  help  slightly  in  the  extension  of  the  ankle-joint.  In  flexing  the  medio-tarsal 
joint,  it  will  tend  to  preserve  the  arch  of  the  instep. 

Relations. — Superficially,  in  the  leg  the  soleus,  posterior  tibial  vessels  and 
nerve;  in  the  foot,  the  abductor  hallucis  and  flexor  brevis  digitorum.  Deeply,  the 
tibialis  posticus  in  the  leg,  and  in  the  foot  the  tendon  of  the  flexor  longus  hallucis, 
the  accessorius,  and  the  muscles  which  form  the  inner  part  of  the  third  layer  of  the 
sole  of  the  foot. 

Variations. — An  accessory  head  sometimes  arises  in  the  leg  from  the  fibula,  the  tibia,  or  the 
deep  taseia  ut'  the  leg  ;  it  may  join  the  rest  of  the  muscle  iu  the  leg,  or  in  the  sole.  Some  of  the 
tendons  to  the  toes  may  be  wanting  ;  more  often  they  are  increased  in  number  and  supply 
the  deficiencies  of  the  flexor  brevis  digitorum,  and  especially  by  sending  slips  to  the  little  toe. 


2.  FLEXOR  LONGUS  HALLUCIS 

The  flexor  longus  hallucis — named  from  its  action  ujion  the  great  toe  (hallux) 
and  its  length — is  a  strong  fusiform  sheet. 

Origin. — The  lower  two-thirds  of  the  posterior  (or  flexor)  surface  of  the 
fibula  external  to  the  oblicjue  line;  (2)  the  intermuscular  septa  between  it  and  the 
tibialis  posticus  in  front,  and  the  peronei  outside;  (3)  the  deep  fascia  covering  its 
jiosti'rior  surface;  and  sometimes  (4)  the  lowest  portion  of  the  interosseous  mem- 
l)rane. 

Insertion. — (1)  Tlie  under  surface  of  the  base  of  the  last  jdialanx  of  the  great 
toe;  (2)  by  a  small  slip  into  that  part  of  the  flexor  longus  digitorum  tendon  which 
is  distributed  to  the  second  and  third  toes. 

Structure. — The  nmscle  arises  by  fleshy  fibres  which  ]iass  with  a  l)i})enniform 
arrangement  into  the  tendon.  This  tendon  appears  first  just  below  tlie  middh:"  of 
the  leg  at  the  back  of  tlie  muscle  near  its  inner  border.  The  fleshy  fibres  are 
inserted  into  it  as  far  as  the  ankle-joint,  and  just  above  this  point  the  tendon  passes 
through  the  groove  at  the  outer  ])art  of  the  back  of  the  lower  end  of  the  tibia.  The 
tendon  then  grooves  tlie  l)ack  of  the  astragalus,  and  afterwards  the  under  sin-face  of 


FLEXOR   LONG  US  HALLUCIS 


375 


the_  sustentaculum  tali,  where  it  lies  external  to  the  tendon  of  the  flexor  longus 
difritorum.  From  this  ]ioint  it  |)asses  forwards  in  tlie  second  layer  of  the  muscles 
of  the  sole,  l^'ing  above  and  crossing  the  tendon  of  the  flexor  longus  digitorum,  to 


Fig.  292.— The  Deep  Musci.ks  of  the  Back  of  the  Leg. 


Plantaris 
Outer  head  of  gastrocnemius 


Peroueua  longua 


Flexor  longus  hailucis 


Peroneus  brevia 


Tibialis  posticus 


Tendo  Aohillia 


which  it  gives  a  small  slip.  It  then  crosses  1>eneath  the  inner  head  of  the  flexor 
hrevis  hailucis,  lies  in  the  groove  between  tlie  sesamoid  bones  of  that  muscle,  and 
is  finally  inserted  into  the  l)ase  of  the  last  phalanx. 


876  THE  MUSCLES 

Nerve-supply. — From  the  posterior  til)i:il  nerve  l\v  branches  which  enter  the 
muscle  in  tlie  upper  part  of  its  posterior  surface  near  its  inner  l)or(ler. 

Action. — This  muscle,  which  is  nmch  more  powerful  than  the  flexor  longus 
digitorum,  is  a  strong  liexor  of  the  last  phalanx  of  the  great  toe,  and  is  of  great 
importance  in  walking,  as  it  presses  the  great  toe  firmly  against  the  ground.  The 
ungual  i^halanx  of  the  great  toe  is  the  last  i)art  of  the  foot  to  leave  the  ground  when 
the  step  is  completed;  and  mitil  this  is  the  case  the  flexor  longus  hallucis  is  strongly 
contractetl.  It  Avill  also  help  to  flex  the  first  phalanx  of  the  great  toe  upon  its 
metatarsal  ])one  and  it  will  act  U])on  the  joints  which  intervene  between  the  first 
metatarsal  bone  and  the  astragalus  so  as  to  support,  the  arch  of  the  instep;  and, 
finally,  it  will  assist  in  the  extension  of  the  ankle-joint.  By  the  slip  which  it  gives 
to  the  flexor  longus  digitorum  it  will  help  that  muscle  in  flexing  the  adjacent  toes. 

Relations. — Superficially,  in  the  leg,  it  is  covered  by  the  soleus,  and  in  the  foot 
by  the  abductor  hallucis,  the  flexor  longus  digitorum,  the  external  plantar  vessels 
and  nerve;  on  its  outer  side  are  the  peronei;  on  its  deep  aspect  in  the  leg  lie  the 
tibialis  posticus  and  the  peroneal  vessels;  and,  after  passing  over  the  back  of  the 
ankle  and  other  joints,  it  lies  upon  the  inner  head  of  the  flexor  brevis  hallucis. 

Variations. — An  accessory  portion  of  the  muscle  may  be  inserted  into  the  sustentaculum  tali 
or  tlie  inner  surfiice  of  the  calcaneum.  The  slip  to  the  flexor  longus  digitorum  tendon  may  vary 
in  the  number  of  toes  to  which  it  is  distributed. 


Fourth  Layer 

The  fourth  layer  consists  of  one  muscle— the  til)ialis  posticus. 

TIBIALIS  POSTICUS 

The  tibialis  posticus — named  from  its  position  in  the  back  part  of  the  leg  and 
its  origin  from  the  tibia — is  a  thick  fusiform  sheet. 

Origin. — (1)  The  whole  of  the  back  of  the  interosseous  ligament  with  the 
exception  of  the  lowest  portion;  (2)  the  posterior  surface  of  the  tibia  close  to 
the  interosseous  line,  from  the  upper  end  of  the  oblique  line  to  the  junction  of  the 
middle  and  lower  thirds  of  the  shaft;  (3)  the  internal  (or  inner  part  of  the 
flexor)  surface  of  the  fibula  at  the  back  of  the  interosseous  ridge  to  within  a  short 
distance  of  the  ankle;  (4)  the  intermuscular  sei)ta  which  intervene  lietAveen  it  and 
the  muscles  of  the  third  layer,  viz.  the  flexor  longus  hallucis  and  the  flexor  longus 
digitorum;  and  (o)  a  small  portion  of  the  deep  tibial  fascia  which  separates  the 
second  from  the  third  layer. 

Insertion. — (1)  The  tuberosity  of  the  scaphoid  bone;  (2)  by  several  smaller 
offsets  into  the  front  of  the  lower  surface  of  the  sustentaculum  tali  and  the  under 
surface  of  all  the  other  tarsal  bones  with  the  exception  of  the  astragalus;  and  (3) 
the  under  surface  of  the  bases  of  the  second,  third,  and  fourth  metatarsal  bones. 

Structure. — A  strong  bipenniform  muscle,  the  central  tendon  of  which, -lying 
upon  the  middle  of  the  l)ack  of  the  muscle,  l)egins  about  the  middle  of  the  leg,  and 
passes  downwards  and  inwards  upon  the  liack  of  the  mviscle,  receiving  its'  last 
fleshy  fibres  aliout  an  inch  (2-5  cm.)  above  the  ankle.  Having  passed  inwards 
beneath  the  tendon  of  the  flexor  longus  digitorum,  it  enters  the  innermost  groove 
on  the  back  of  the  internal  malleolus,  and  is  contained  in  a  synovial  sheath  which 
accompanies  it  to  its  insertion  upon  the  scaphoid  bone.  From  this  insertion  strong 
fibrous  l)ands  radiate  backwards,  outwards,  and  forwards  to  the  tarsal  and  meta- 
tarsal bones,  being  intimately  blended  with  the  ligaments  by  which  these  bones  are 
held  together.  This  muscle,  which  is  very  strong,  is  contained,  so  to  s]>eak,  in  a 
h)ng  four-sided  case  formed  in  the  front  by  the  interosseous  membrane;  at  the 
sides,  by  the  op]>osing  surfaces  of  the  tibia  and  filjula;  and  behind,  at  a  distance  of 
nearly  half  an  inch  (1-2  cm.)  from  the  interosseous  membrane.  1)V  the  intermus- 
cular se])ta  which  sei)arate  the  muscle  from  tlie  flexor  longus  hallucis  and  the  flexor 
longus  digitorum. 

Just  above  its  insertion  into  the  tuberosity  of  the  scaphoid  bone,  the  tendon 
often  contains  a  sesamoid  bone. 


FASCIA   AND  MUSCLES   OF  THE  SOLE   OF  THE  FOOT         Zll 

Nerve-supply. — From  the  postcriin'  tilnal,  which  sends  hranches  forwards  to 
the  l)aek  of  the  muscle  in  the  U])i)er  third  of  the  leg. 

Action. — (I)  To  adduct  the  front  of  the  foot;  (2)  to  invert  the  sole;  (3)  to 
extend  the  ankle — the  last  of  these  movements  is  somewhat  limited;  (4)  to  siipijort 
the  longitudinal  arch  of  the  foot — first,  by  drawing  backwards  the  lower  part  of 
the  scaphoid,  and  so  preventing  the  descent  of  tlie  head  of  the  astragalus  between 
the  scaphoid  and  calcaneum,  and  secondly  by  its  traction  upon  the  other  tarsal 
bones  into  which  the  secondary  offsets  of  its  tendon  are  inserted. 

Relations. — Superficially,  the  soleus  and  third  layer  of  muscles  of  the  leg,  the 
l)osterior  tibial  and  peroneal  vessels  and  the  posterior  tibial  nerve  above;  in  the 
sole  the  tendon  of  the  flexor  longus  digitorum  and  the  abductor  hallucis;  deeply, 
the  ankle-joint  and  inferior  caleaneo-scaphoid  ligament.  The  anterior  tibial  vessels 
pass  through  a  notch  at  the  upper  extremity  of  the  muscle,  Ijetween  its  tiliial  and 
fibular  origins. 


THE  FASCIA  AND  MUSCLES  OF  THE  SOLE 
OF  THE  FOOT 

The  plantar  fascia  is,  like  the  corresponding  fascia  in  the  palm,  very  strong, 
and  is  divided  into  three  parts.  The  central  part,  which  is  the  strongest,  arises 
from  the  under  surface  of  the  calcaneum  at  the  back  of  the  tubercles.  It  is 
triangular,  the  apex  being  attached  behind,  and  the  expanded  base  dividing 
near  the  heads  of  the  metatarsal  bones  into  five  divisions,  one  for  each  of  the  toes. 
Each  division  forms  an  arch  over  the  tendons  entering  the  toe,  and  is  continuous 
with  the  ligamentum  vaginale  of  the  theca.  The  sides  of  the  arch  pass  upwards  to 
hit  attached  to  the  deep  transverse  ligament  which  connects  the  heads  of  the  meta- 
tarsal bones,  and  to  the  lateral  ligaments  of  the  metatarso-phalangeal  joints.  The 
under  surface  of  the  fascia  is  attached  to  the  deep  surface  of  the  skin  by  small 
fil)rous  bands  which  form  the  walls  of  compartments  containing  pellets  of  fat. 
These  fibrous  connections  give  firmness  to  the  skin  of  the  sole  and  prevent  it  from 
being  moved  about  upon  the  subjacent  fascia.  The  borders  of  the  central  portion 
of  the  plantar  fascia  are  continued  upwards  into  the  sole  by  the  internal  and  external 
inter  mil  scidar  septa,  which  are  attached  above  to  the  fibrous  structures  on  the  under 
surfaces  of  the  tarsal  bones.  The  inner  portion,  which  is  the  thinnest  division  of 
the  plantar  fascia,  is  attached  behind  to  the  inner  Itorder  of  the  great  tubercle  of  the 
calcaneum  and  to  the  lower  border  of  the  internal  annular  ligament.  It  is  inserted 
in  front  upon  the  inner  side  of  the  base  of  the  first  phalanx  of  the  great  toe,  and 
above  it  becomes  continuous  wdth  the  deep  fascia  covering  the  instep.  The  ex- 
ternal portion  is  very  thick,  and  arises  from  the  outer  border  of  the  lesser  tul)ercle 
of  tlie  calcaneum  and  the  lower  border  of  the  external  annular  ligament.  It  ter- 
minates in  front  in  the  base  of  the  first  phalanx  of  the  little  toe,  and  at  its  inner 
border  it  blends  with  the  central  portion  of  the  plantar  fascia,  Avhere  it  is  joined  by 
the  external  intermuscular  septum;  ujwn  its  outer  border  it  is  closely  connected 
with  the  l)ase  of  the  fifth  metatarsal  bone,  and  it  is  continuous  with  the  deep  fascia 
covering  the  instep. 

In  tlie  web  between  the  toes  some  thin  transverse  fibres  are  found,  the  super- 
ficial transverse  ligament  of  the  toes.  They  bridge  over  part  of  the  interval 
between  the  live  sli}>s  into  which  the  front  part  of  the  central  division  of  the 
l)lantar  fascia  breaks  up. 

The  muscles  and  tendons  in  the  sole  of  the  foot  are  divided  into  four  layers. 
The  first  layer  consists  of  three  muscles,  which  corresi)ond  in  their  position  to  the 
three  compartments  formed  l)y  the  ])lantar  fascia  and  the  two  intennuscular  septa, 
viz.  the  abductor  hallucis,  the  fiexor  brevis  digitorum,  the  abductor  minimi  digiti. 


;78 


THE  MUSCLES 


First  Layer 


1.  ABDUCTOR  HALLUCIS 

The  abductor  hallucis — nanu-(l  from  its  action  upon  the  great  toe — is  a  thick 
triantrular  sheet,  with  a  hroad  oriuin  Ix'hind,  Avhich  is  divided  into  two  heads. 

Origin. — Outer  head  :  (  1  )  Tlie  front  and  inner  surfaces  of  the  inner  or  greater 
tubercle  on  the  uncka-  surface  of  the  calcaneuni;   (2)  the  deep  surface  of  the  inner 


Fia.  293.— FiKST  Layer  of  the  Muscles  of  the  Sole. 


I 


Abductor  minimi  digiti 


Flexor  brevia  minimi  digiti 


Tendon  of  flexor  longus  digitorum 


Flexor  brevia  digitorum 


Abductor  hallucis 


Flexor  longus  hallucis 

Flexor  brevia  hallucis 
First  lumbricalis 


—  Tendon  of  adductor  hallucis 


j.ortion  of  tlie  ])lantar  fascia;  (3)  tlie  intern luscular  septum  Avhich  separates  it 
from  the  tiexor  hrevis  (hgitorum.  Inner  head  :  ( 1 )  The  deep  aspect  of  the  kiwer 
lionk^of  tlie  internal  amuilar  ligament;  (2)  the  under  surface  of  the  attachment 
of  the  tendon  of  the  tihialis  posticus  to  the  tuberosity  of  the  scaphoid  bone  and  the 
adjacent  prolongations  of  this  tendon. 

Insertion. — The  inner  part  of  the  lower  surface  of  the  base  of  the  first  ])halanx 
of  the  great  toe  and  the  inner  side  of  the  internal  sesamoid  bone.  Occasionally, 
also,  the  inner  l)order  of  the  expansion  of  the  extensor  proprius  hallucis  on  the 
back  of  the  first  ])halanx. 

Structure. — The  outer  head  arises  in  close  connection  with  the  flexor  hrevis 
digitorum  by  short  tendinous  fibres,  soon  succeeded  by  a  divergent  fleshy  bundle 
wiiich  is  joined  about  two  inches  (5  cm.)  from  its  origin  l)y  tlie  fleshy  sheet  formed 


FLEXOR  B  RE  VIS  DIG  ITORUM— ABDUCTOR  MINIMI  DIGITI      379 

by  the  inner  head.  The  tendon  to  which  these  llesliy  tibres  converge  appears  first 
upon  the  inner  and  lower  aspect  of  tlie  muscle,  and  receives  lleshy  fil)res  nearly  to 
its  insertion,  which  is  closely  blended  with  that  of  the  inner  portion  of  the  flexor 
brevis  hallucis.  The  deep  surface  of  the  muscle  arises  from  a  fil)rous  arch  attached 
on  the  one  side  to  the  septum  between  it  and  the  flexor  l)revis  digitorum;  on  the 
other  side  to  the  tibialis  i)osticus  tendon  and  the  fil)rous  tissue;  covering  the  under 
surface  of  the  tarsal  bones  along  the  inner  border  of  the  foot.  Through  this  arch 
pass  the  plantar  vessels  and  nerves. 

Nerve-supply. — The  internal  plantar  division  of  the  posterior  tiltial  nerve,  by 
filaments  wliicli  t'uter  the  deep  surface  of  the  middle  of  the  muscle. 

Action. — (1)  To  flex  the  first  phalanx  upon  the  metatarsal  bone;  (2)  to  abduct 
from  tlie  middle  line  of  the  foot  the  first  phalanx  of  the  great  toe. 

Relations. — Superficially,  the  internal  division  of  the  plantar  fascia;  upon  its 
outer  border,  tlie  flexor  Invvis  digitorum;  deeply,  the  tendons  of  the  tibialis  anti- 
cus,  tibialis  posticus,  flexor  longus  digitorum,  flexor  longus  hallucis,  the  plantar 
vessels  and  nerves. 

Variations. — A  tliirtl  liead  is  occasionallj'  tlerived  from  the  deep  surface  of  the  skin  upon 
the  inner  border  of  the  foot,  or  from  the  long  plantar  ligament.  The  muscle  may  give  a  slip  to 
the  second  toe. 

2.  FLEXOR   BREVIS    DIGITORUM   PEDIS 

The  flexor  brevis  digitorum  pedis,  or  flexor  perforatus — named  from  its 
being  the  shorter  of  the  flexors  of  the  four  outer  toes — is  a  triangular  sheet,  divided 
in  front  into  four  processes  corresponding  to  the  tendons  of  the  toes. 

Origin. — (1 )  The  outer  part  of  the  front  of  the  lower  surface  of  the  great  tubercle 
of  tlie  calcaneum;  (2)  the  deep  surface  of  the  back  part  of  the  central  portion  of 
the  plantar  fascia;   (3)  the  back  part  of  the  intermuscular  septa  on  either  side. 

Insertion. — The  sides  of  the  middle  phalanx  of  each  of  the  four  outer  toes 
ujjon  its  plantar  aspect. 

Structure. — Arising  tendinous  by  a  pointed  process  from  the  under  surface  of 
the  great  tubercle,  the  fleshy  filjres  extend  in  a  fan-shaped  sheet,  which,  about  half- 
way between  the  origin  and  the  heads  of  the  metatarsal  bones,  divides  into  four 
fleshy  processes  which  soon  become  tendinous.  The  tendons  are  arranged  in  a 
similar  manner  to  those  of  the  flexor  sublimis  digitorum  in  the  hand.  After  split- 
ting beneath  the  first  phalanx  of  the  toe,  the  two  halves  of  each  tendon  pass  round 
the  sides  of  the  flexor  longus  digitorum  tendon,  and  aliout  the  level  of  the  base  of 
the  second  phalanx  they  unite  l)y  their  adjacent  margins,  and  again  diverge  to  be 
attached  to  the  sides  of  the  plantar  surface  of  the  second  i)halanx. 

Nerve-supply. — From  the  internal  plantar  division  of  the  posterior  tibial,  by 
branches  which  enter  the  back  of  the  deep  aspect  of  the  muscle  near  its  inner 
border. 

Action. — This  muscle,  which  is  comparatively  feeble,  will  flex  the  second  pha- 
langes of  the  toes,  and  in  combination  with  the  flexor  longus  digitorum  it  will 
assist  in  walking,  by  pressing  the  under  surface  of  the  phalanges  of  the  toes  against 
the  ground.  After  it  has  flexed  the  second  phalanges,  it  will  act  in  a  similar  man- 
ner upon  the  metatarso-phalangeal  and  medio-tarsal  joints. 

Relations. — Superficially,  the  plantar  fascia;  on  either  side,  the  other  muscles 
of  the  first  layer  of  the  sole;  deeply,  the  tendons  of  the  flexor  longus  digitorum  and 
the  lumbricales,  the  accessorius  muscle,  and  the  external  plantar  vessels  and  nerve. 

Variations. — The  part  of  the  muscle  which  belongs  to  the  little  toe  is  often  absent  (see  fig. 
I2".t4),  and  its  place  may  be  supplied  by  a  small  perforated  slip  from  the  tendon  of  the  flexor 
longus  digitorum. 

3.    ABDUCTOR   MINIMI    DIGITI    PEDIS 

Tlie  abductor  mininii  digiti  (pedis) — named  from  its  action  upon  the  fifth  and 
smallest  toe — is  a  thick  triangular  slieet,  jiartly  muscular  and  partly  aponeurotic. 
Origin. — (1)   The  outer  side  and  tlie  under  surface  of  the  front  of  the  lesser 


380 


THE  MUSCLES 


tulxTcle  of  the  calcanciun  and  the  adjacent  i)()rti<)n  of  the  under  surface  of  that 
Ijone  in  front  of  the  <ire;it  tul)ercle;  (2)  the  upi)er  surface  of  the  l)ack  part  of  the 
outer  division  of  the  i)lantar  fascia;  (3)  the  outer  surface  of  the  back  ])art  of  the 
external  intermuscular  septum;  (4)  the  long  plantar  ligament  and  other  ligamen- 
tous structures  lying  upon  the  outer  border  of  the  sole,  and  more  especially  an 
aponeurotic  band  which  runs  from  the  outer  side  of  the  lesser  tubercle  of  the  cal- 
caneum  to  the  outer  side  of  the  base  of  the  fifth  metatarsal  bone,  and  of  the  base 
of  the  first  phalanx  of  the  fifth  toe. 

Insertion. — (1)  The  outer  part  of  the  under  surface  of  the  base  of  the  first 
])halanx  of  the  little  toe;  (2)  usually  also  the  outer  part  of  the  under  surface  of 
the  base  of  the  fifth   metatarsal  bone;   (3)   the  outer  edge  of  the  fourth  tendon 


( 


Fig.  294.— Secoxd  Layer  of  the  Muscles  of  the  Sole. 

Flexor  brevis  digitorum 

Origin  of  abductor  minimi  digiti  _         _    

"' '      '  '"  Abductor  hallucia 


Part  of  abductor  minimi  digiti 


Plexor  brevis  minimi  digiti 


Abductor  minimi  digi 


Lumbrieales 


Tendon  of  flexor  brevis 

digitorum 


Tendon  of  flexor  brevis  digitor 


Accessorius 


Flexor  longus  digitorum 


Flexor  longus  hallucis 
Flexor  brevis  hallucis 

Adductor  hallucis 
Abductor  hallucis 


\S-i^' 


of  the  extensor  longus  digitorum  upon  the  l)ack  of  the  first  phalanx  of  the  little 
toe. 

Structure. — Tlie  muscle,  which  is  at  first  encased  in  the  aponeuroses,  from 
which  as  well  as  from  the  bone  it  takes  origin,  converges  from  both  sides  upon  a 
tendon  which  is  first  visible  on  its  under  surface  at  the  front  of  the  calcaneum.  A 
small  portion  of  its  outer  part  is  now  inserted  into  the  tubercle  of  the  fifth  meta- 
tarsal bone,  internal  to  the  strong  aponeurotic  band  which  is  also  here  attached. 
From  this  point  the  tendon  of  insertion  is  free  on  its  inner  side,  but  receives  fieshy 
fibres  still  from  the  continuation  of  the  aponeurotic  liand  just  mentioned,  until  it 
is  inserted  into  the  base  of  the  first  ))halanx. 

Nerve-supply. — P^rom   the   external  i)lantar  division   of    the    posterior  tibial 


FLEXOR  ACCESSORIUS.   DIGITORUM  PEDIS  381 

nerve,  by  lilanients  which  enter  the  back  part  of  the  deep  surface  of  the  muscle 
near  its  inner  border. 

Action. — (1)  To  abduct  i\w  lirst  phahxnx  of  the  httle  toe  from  the  middle  Hne; 
(2)  to  Hex  tlie  metatarso-phalangeal  joint  of  the  httle  toe. 

The  usual  action  of  the  muscle  will  be  a  combination  of  tliese  two  movements. 

Relations. — Superficially,  the  plantar  fascia,  the  flexor  brevis  digitorum,  and 
even  a  sinall  portion  of  the  abductor  hallucis.  Deeply,  the  accessorius,  flexor 
brevis  minimi  digiti,  long  plantar  ligament,  and  peroneus  longus  tendon. 

Variations. — The  muscular  slip  attached  to  the  base  of  the  fifth  metatarsal  bone  is  often  so 
distinct  as  to  form  a  separate  muscle,  tlie  abductor  ossis  metatarsi  quinti. 


Second  Layer 

The  second  layer  consists  of  the  flexor  accessorius  muscle,  the  four  lumbricales, 
and  the  tendons  of  the  flexor  longus  hallucis  and  the  flexor  longus  digitorum. 


1.  FLEXOR  ACCESSORIUS  DIGITORUM  PEDIS 

The  flexor  accessorius  digitorum  pedis — named  from  its  accessory  or  supple- 
mentary action  in  assisting  the  flexion  of  the  toes  by  the  flexor  longus  digitorum — 
is  a  dou))le-headed  quadrilateral  sheet. 

Origin. — Inner  head  :  The  whole  of  the  concave  inner  surface  of  the  calcaneum 
below  the  groove  for  the  flexor  longus  hallucis. 

Outer  head  :  (1)  The  junction  of  the  lower  and  outer  surfaces  of  the  calcaneum 
in  front  of  the  lesser  tubercle;  (2)  the  under  surface  of  the  back  part  of  the  long 
plantar  ligament. 

Insertion. — The  upper  surface  and  outer  border  of  the  flexor  longus  digitorum 
tendon  about  midway  between  the  tubercles  of  the  calcaneum  and  the  heads  of  the 
metatarsal  bones. 

Structure. — Its  inner  head  consists  of  fleshy  fi})res  which  converge  from  their 
origin  in  a  somewhat  fan-shaped  sheet,  and  are  joined  shortly  before  their  insertion 
into  the  tendon  by  the  outer  head,  which  consists  of  a  pointed  tendinous  origin, 
from  which  the  fleshy  fibres  form  a  somewhat  smaller  fan-shaped  sheet  which 
blends  with  that  from  the  inner  head,  to  be  inserted  by  fleshy  fibres  upon  the 
upper  surface  and  outer  border  of  the  flexor  longus  digitorum,  at  its  point  of 
division  into  the  tendons  for  the  four  outer  toes. 

Nerve-supply. — From  the  external  plantar  division  of  the  posterior  tibial 
ncrvi',  by  l)ranches  which  enter  the  under  surface  of  the  muscle  near  its  origin. 

Action.— To  help  in  the  flexion  of  the  last  phalanges  of  the  four  outer  toes, 
and  at  the  same  time  to  draw  the  toes  somewhat  outwards.  On  accovmt  of  the 
oblicjue  direction  of  the  tendons  of  the  flexor  longus  digitorum  in  the  foot,  they 
would  tend  in  flexing  the  toes  to  draw  them  at  the  same  time  inwards.  This 
tendency  Avill  be  somewhat  neutralised  by  the  simultaneous  contraction  of  the 
accessorius.  The  accessorius  will  also  be  able  to  flex  the  toes  Avhcn,  on  account  of 
the  extensi(Mi  of  the  ankle-joint,  the  muscular  fibres  of  the  flexor  longus  digitorum 
are  so  relaxed  as  to  be  weakened  in  their  action. 

Relations. — Superficially,  the  flexor  brevis  digitorum,  the  aVxluctor  minimi 
digiti,  the  tendons  of  the  flexor  longus  digitorum  and  flexor  longus  hallucis,  with 
the  external  plantar  vessels  and  nerve;  deei)ly,  the  flexor  brevis  hallucis  and  long 
plantar  ligament. 

Variations. — An  additional  head  may  arise  above  the  ankle  from  the  flexor  longus  digitorum, 
Hfxiir  longus  liallucis,  or  soleus.  Sometimes  the  outer  head  is  wanting,  and  occasionally  the 
whole  muscle  is  absent.  The  (listril)Utinn  of  its  filires  to  the  tendons  of  the  long  flexor  is  very 
variable.  '  It  may  send  fibres  to  the  tenilon  of  the  flexor  longus  hallucis. 


382  THE  MUSCLES 


2.  THE  FOUR  LUMBRICALES 

The  four  lumbricales — named  from  their  shape  (lumbrirus  =  an  earthworm) — 
are,  like  those  in  the  pahn,  four  small  fusiform  muscles. 

Origin. — The  tirst,  from  the  inner  l)order  of  the  innermost  tendon  of  the  flexor 
lonj2;us  di^dtorum,  from  the  point  of  division  of  the  main  tendon  for  al)out  an  inch 
(•2-5em.  )  forwards;  the  other  three,  from  the  adjacent  surfaces  of  the  first  and 
second,  tlie  second  and  third,  and  the  third  and  fourth  tendons  of  the  flexor  longus 
digitorum  on  their  plantar  aspect. 

Insertion. — The  inner  Iwrder  of  the  expansion  of  the  extensor  longus  digitorum 
tendon  u}>on  the  hack  of  the  tirst  phalanx  of  each  of  the  four  outer  toes. 

Structure. — The  origin  of  the  muscle  is  entirely  fleshy.  It  ends  in  a  small 
rounded  tendon  a  short  distance  ahove  the  web  of  the  toes.  This  tendon  runs 
forwards  and  upwards  upon  the  inner  side  of  its  toe,  above  the  superficial  transverse 
ligament  of  the  toes  and  beneath  the  deep  transverse  ligament  of  the  metatarsus, 
to  the  side  of  the  expansion  of  the  extensor  tendon. 

Nerve-supply. — The  innermost  is  supplied  by  the  internal  jdantar  division 
of  the  posterior  tilnal  nerve,  by  filaments  which  enter  the  back  part  of  the  lower 
surface  of  the  muscle  near  its  inner  border;  the  three  outer,  by  the  external 
plantar  nerve,  by  filaments  which  enter  the  deep  part  of  each  muscle  near  its 
outer  border. 
"  Action. — (1)  To  flex  the  first  phalanx  of  the  toe;  (2)  to  straighten  the  second 
and  third  phalanges.  (3)  The  first  will  abduct  the  second  toe  from  the  axis 
passing  through  it,  which  is  looked  upon  as  the  middle  line  of  the  foot.  The  three 
others  will  adduct.  The  lumljricales  will  be  al)le  to  act  upon  the  first  ithalanges, 
even  Avhen  the  second  and  third  have  been  flexed  1)y  means  of  their  special  flexors. 
The  chief  advantage  derived  from  the  simultaneous  extension  of  the  two  terminal 
phalanges  and  the  flexion  of  tlie  first  phalanx  is  the  application  of  the  whole  length 
of  the  toe  to  the  ground  in  walking;  otherwise  there  would  be  a  strong  tendency 
to  the  flexion  of  the  phalanges  of  the  toes,  which  would  prevent  the  proper  appli- 
cation of  the  soft  plantar  aspect  of  the  ungual  phalanx  to  the  ground. 

Relations. — Superficially,  the  flexor  brevis  digitorum.  Deeply,  the  flexor 
longus  digitorum  tendons,  the  transversalis  pedis,  and  the  interossei. 


Third  Layer 

The  third  layer  consists  of  four  muscles — the  flexor  brevis  hallucis,  the  adductor 
hallucis,  the  transversus  pedis,  and  the  flexor  brevis  minimi  digiti. 


1.  FLEXOR  BREVIS  HALLUCIS 

The  flexor  brevis  hallucis,  or  flexor  brevis  pollicis  pedis — named  from  its 
action,  and  its  size  in  comparison  Avith  the  other  flexor  of  the  great  toe — is  a  thick 
triangular  sheet  with  a  forked  insertion. 

Origin. — { 1)  The  ])lantar  ligaments  and  the  continuations  of  the  tibialis 
posticus  tendon  in  the  middle  of  the  solo;  (2)  the  inner  part  of  the  under  surface 
of  the  cuboid  bone. 

Insertion. — The  inner  and  outer  borders  of  the  jdantar  aspect  of  the  base  of  the 
first  phalanx  of  the  great  toe. 

Structure. — Arising  fibrous  by  a  pointed  ])rocess  in  the  middle  of  the  sole,  the 
fibr(>s  diverge  as  they  pass  forwards  and  slightly  iuAvards,  and  form  two  fleshy 
bundles  of  eipial  size,  which  are  succeeded  liy  short  tendons.  In  each  tendon  is 
contained  a  sesamoid  l)one  of  ovoid  shape  about  three-eigliths  of  an  inch  (1  cm.)  in 
the  long  antero-])osterior  diameter,  and  a  quarter  of  an  inch  (7  nun.)  from  side  to 
side,  Avith  a  cartilaginous  articular  facet  U])on  tlie  ui)i)er  surface  Avhich  ))lays  U])on 
the  lower  surface  of  the  coiidvle    of  the  first  metatarsal  bone.      At  their  insertion 


ADD  UCTOR   II A  LL  UCIS 


383 


into  tlie  iiiiRT  and  outer  part  of  the  lower  Ijorder  of  the  l)ase  of  the  firt^t  ])lialanx, 
they  are  blended  with  the  tendons  of  the  alxluctor  and  the  adductor  hallueis. 

Nerve-supply. — From  the  internal  ])lantar  division  of  the  ]»osterior  tiliial 
nerve,  by  tilauients  which  enter  the  under  surface  of  the  nuiscle  near  the  middle  of 
its  inner  border. 

Action. — To  flex  and  sli,i;htly  adduct  the  first  i)halanx  of  the  great  toe.  The 
sesamoid  bones  give  a  slight  ol)liquity  to  its  insertion,  and  so  enable  it  to  act  with 
more  power;  at  the  same  time  they  form  a  groove  in  which  the  strong  tendon  of  the 
fl(^xor  longus  hallucis  plays.  They  also  form  a  somewhat  elastic  support  when  the 
weight  is  placed  upon  the  ball  of  the  foot. 

Relations. — Superficially,  the  abductor  hallucis,  the  tendon  of  the  flexor  longus 
hallucis,  and  the  inner  tendons  of  the  flexor  longus  digitorum  with  the  lumbricales; 
dee])ly,  the  interossei  and  the  termination  of  the  external  plantar  vessels  and  nerve. 

Variations. — A  small  slip  is  occasionally  given  to  the  first  phalanx  of  the  second  toe. 


Fig.  295. — Third  Layer  of  the  Muscles  of  the  Sole. 


Long  plantar  ilong  inferior 
caleaueo-cuboid)  ligaineat 


Part  of  abductor  minimi  digiti 


Flexor  brevis  minimi  digiti 


TrauBversus  pedis      — 


Divided  tendons  of  flexor  brevis 
digitorum 


Tendon  of  flexor  longus  digitorum 


Tendon  of  the  flexor  longus 
hallucis 


2.  ADDUCTOR  HALLUCIS 

The  adductor  hallucis — named  from  its  action  up(jn  the  great  toe — is  a  tri- 
angular sheet,  the  a]>ex  of  which  is  directed  forwards  and  inwards. 

Origin. — (1)  The  continuation  forwards  of  the  long  j)lantar  ligament  which 
forms  the  sheath  of  the  ])eroneus  longus  tendon;  (2)  the  under  surface  of  the  bases 
of  the  second,  third,  and  fourth  metatarsal  bones. 


384  THE  MUSCLES 

Insertion. — The  outer  jtart  of  the  under  surface  of  the  base  of  the  first  i)halanx 
of  the  <rreat  toe. 

Structure. — Arising  by  sliort  tendinous  fibres,  the  muscle  converges  iu  bipen- 
niforni  fasliion  upon  a  short  tendon,  which  blends  with  that  of  the  flexor  brevis 
hallucis  and  the  outer  sesamoid  Ijone  internally,  and  the  transversus  pedis  exter- 
nally. 

Nerve-supply. — From  the  external  plantar  division  of  the  posterior  tibial 
nerve  l)v  tilann-nts  which  enter  the  upper  surface  of  the  muscle  upon  its  outer 
border  near  its  origin. 

Action. — (1)  To  adduct  the  first  phalanx  of  the  great  toe  towards  the  middle 
line  of  the  foot;  (2)  to  Hex  the  first  phalanx.  Usually  it  will  act  during  walking 
in  combination  with  the  flexor  Ijrevis  hallucis  and  ah)ductor  hallucis,  and  the  three 
muscles  contracting  together  will  produce  direct  flexion  of  the  first  phalanx,  so 
that  when  the  weight  of  the  body  rests  upon  the  front  part  of  the  foot  the  second 
phalanx  is  pressed  firmly  against  the  ground  by  the  action  of  the  flexor  longus 
hallucis.  while  the  first  phalanx  is  acted  upon  in  the  same  manner  by  the  combi- 
nation of  these  three  short  muscles.  As  Duchenne  has  pointed  out,  the  abductor 
and  adductor  will  have  an  imijortant  function  in  adjusting  the  pressure  when  the 
step  has  to  be  made  upon  uneven  ground.  Thus,  in  walking  upon  a  slope  the 
adductor  hallucis  of  the  one  foot  will  direct  the  pressure  downwards  and  slightly 
outwards,  while  the  abductor  of  the  other  foot  will  direct  the  pressure  downwards 
and  slightly  inwards. 

Relations. — Superficially,  the  flexor  longus  digitorum  tendons  and  their  lum- 
bricales;  deeply,  the  interossei  with  the  external  plantar  vessels  and  nerve;  at  the 
sides,  the  flexor  brevis  hallucis  and  transversus  pedis. 

Variations. — The  adductor  hallucis  sometimes  sends  a  slip  to  the  first  phalanx  of  the  second 
toe. 

3.  TRAXSVERSUS  PEDIS 

The  transversus  pedis — named  from  the  direction  of  its  fibres — is  a  small 
muscle  consisting  of  three  or  four  fusiform  bundles  lying  side  by  side,  and  uniting 
in  a  single  tendon. 

Origin. — (1)  The  plantar  ligaments  of  the  three  outer  metatarso-phalangeal 
joints:   (  2  )  the  under  surface  of  the  adjacent  deep  transverse  metatarsal  ligaments. 

Insertion. — The  outer  side  of  the  base  of  the  first  phalanx  of  the  great  toe. 

Structure. — The  fleshy  fibres  form  a  series  of  small  bundles  which  converge 
slightly  as  they  pass  inwards  and  somewhat  forwards,  and  after  uniting  terminate 
in  a  short  tendinous  insertion  which  is  closely  blended  with  the  outer  surface  of 
the  tendon  of  the  adductor  hallucis. 

Nerve-supply. — Fnmi  the  external  plantar  division  of  the  posterior  tibial 
nerve  by  filaments  which  pass  to  the  upper  part  of  the  posterior  edge  of  the  muscle. 

Action. — (1)  To  adduet  the  first  phalanx  of  the  great  toe;  (2)  to  draw  together 
the  heads  of  the  metatarsal  bones  after  the}'  have  been  sej^arated  by  the  pressure 
of  the  weight  of  the  body  during  the  tread. 

Relations. — .Superficially,  the  flexor  longus  digitorum  tendons  and  lumbri- 
cales;  deeply,  the  interossei. 

Variations. — Some  or  all  of  the  bundles  may  be  absent ;  most  frequently  the  outermost  one. 
OLXiisionally  fibres  join  the  muscle  from  the  fascia  covering  the  int^erossei  below  the  lower  border 
of  the  adductor  hallucis,  so  that  the  two  muscles  are  more  or  less  blended. 


4.  FLEXOR  BREVIS  MINIMI  DIGITI  PEDIS 

The  flexor  brevis  minimi  digiti  pedis — named  from  its  action  u])on  the  little 
toe — is  small.  Unttcned.  and  fuHiforni. 

Origin. — (1)  The  under  surface  of  the  base  of  tlie  fifth  metatarsal  l)one;  (2) 
the  adjacent  part  of  the  sheath  of  the  ])eroneus  longus  tendon. 

Insertion. — (1)  The  outer  part  of  the  under  surface  of  the  base  of  the  first 


IXTEROSSEI  385 

phalanx  of  the  httle  toe;  (2)  the  outer  part  of  tlie  front  of  the  under  surface  of 
the  til'th  metatarsal  l)one. 

Structure. — Arising  tendinous,  the  fleshy  filjres  run  forwards  and  a  little  out- 
Avards  to  their  short  tendon  of  insertion,  which  is  closely  l)lended  with  that  of  the 
abductor  minimi  digiti.     A  few  of  the  deeper  fibres  end  in  the  metatarsal  bone. 

Nerve-supply. — From  the  external  plantar  nerve  by  a  branch  which  enters  the 
under  surface  of  the  muscle. 

Action. — To  flex  and  slightly  abduct  the  first  phalanx  of  the  little  toe. 

Relations. — Superficially,  the  flexor  longus  digitorum  and  abductor  minimi 
digiti;  deeply,  the  interossei  of  the  outermost  interspace. 

Variations. — The  in.sertion  upon  the  metatarsal  bone  may  form  a  sej^arate  muscle,  tlie 
opponeus  digiti  pedis  quiuti,  or  it  maj'  be  entirely  absent. 


Fourth  Layer 

The  fourth  layer  consists  of  the  seven  interosseous  muscles. 

IXTEROSSEI 

The  interossei — named  from  their  position  between  the  metatarsal  bones — are, 
like  those  of  the  hand,  seven  in  number,  three  being  plantar  and  four  dorsal. 
The  plantar  are  small  and  narrow  fusiform  bundles;  the  dorsal  are  bipenniform 
and  of  a  somewhat  Ijroader  fusifomi  shape  than  the  plantar.  The  interossei  of  the 
foot  differ  from  those  of  the  hand  in  the  fact  that  they  adduct  and  abduct  with  respect 
to  a  longitudinal  axis  through  the  line  of  the  second  toe;  whereas  in  the  hand  the 
median  line  passes  through  the  middle  finger. 

The  plantar  interossei. — Origin. — (1 )  The  inner  and  lower  surfaces  of  the  three 
outer  metatarsal  bones;  (2;  the  adjacent  part  of  the  sheath  of  the  peroneus  longus 
tendon. 

Insertion. — (1)  The  inner  side  of  the  bases  of  the  first  phalanges  of  the  three 
outer  toes;  (  2)  the  inner  ])order  of  the  expansions  of  the  long  extensor  tendons  on 
the  back  of  the  first  |)halanges  of  the  same  toes. 

The  dorsal  interossei  arise  from  the  adjacent  surfaces  of  the  metatarsal  bones 
bounding  each  interosseous  space.  The  first  dorsal  interosseous,  however,  differs 
somewhat  in  its  internal  head,  which  is  from  the  base  only  of  the  first  metatarsal 
bone  and  the  adjacent  outer  surface  of  the  internal  cuneiform  bone. 

Insertion. — The  first  dorsal  interosseous  is  inserted  into: — (1)  the  inner  side  of 
the  base  of  the  first  phalanx  of  the  second  toe;  (2)  the  inner  edge  of  the  aponeurosis 
of  the  extensor  tendon  upon  the  back  of  the  first  phalanx.  The  second,  third,  and 
fourth  are  inserted  respectively  into: — CI)  the  outer  sides  of  the  bases  of  the  first 
phalanges  of  the  second,  third,  and  fourth  toes;  (2)  the  outer  borders  of  the  extensor 
tendons  upon  the  backs  of  the  same  phalanges. 

Structure. — The  plantar  interossei  are  penniform  muscles  consisting  of  fleshy 
fil)res  which  run  forwards  to  the  outer  side  of  a  tendon  which  begins  about  the 
middle  of  the  space  and  becomes  free  opposite  the  heads  of  the  metatarsal  bones. 

The  dorsal  interossei  are  bipenniform,  and  consist  of  fleshy  fibres  which  con- 
verge from  both  sides  of  the  space  upon  a  central  tendon  Avhich  begins  about  the 
middle  of  the  interosseous  space  and  becomes  free  opposite  the  heads  of  the  meta- 
tarsal bones.  The  tendons  of  both  sets  of  muscles  before  their  insertion  lie  al)ove 
the  deep  transverse  metatarsal  ligament  which  separates  them  from  the  tendons 
of  the  luml)ricales.  On  the  dor.«um  of  the  foot  the  dorsal  interossei  are  alone 
visil)lo;  in  the  sole  of  the  foot  both  sets  are  seen. 

Nerve-supply. — From  the  external  plantar  nerve  by  filaments  which  enter  the 
}ilantar  aspect  of  the  muscles,  somewhat  behind  the  middle  of  the  interosseous 
space. 

Action. — The  common   action   of    all  the  interossei  is   (1)   to  flex   the   first 
phalanges  of  the  four  outer  toes;  (2)  to  extend  the  second  and  third  phalanges.    In 
25 


386 


THE  MUSCLES 


these  two  movoments  they  are  assisted  by  tlie  luinl 
ment  is  of  jiivut  importance,  as  it  keeps  the  toes 
body  rests  upon  tlie  front  part  of  the  foot.     When 
the  action  of  the  long  and  short  flexors  of  the  toes 
of  the  toes  are  subjected  to  consideralile  pressure, 
in  the  bkls  of  the  nails. 

The  special  action  of  the  plantar  interossei  is 
the  three  outer  toes;  and  of  the  dorsal  interossei 


)ricales.  In  walking,  this  move- 
straight  when  the  weight  of  the 
these  movements  are  paralysed, 
is  to  curl  them  up,  and  the  ends 
which  may  set  up  inflanmiation 

to  adduct  the  first  phalanges  of 
to  al)duct  the  second,  third,  and 


Fig.  296. — Foukth  Layer  of  the  Muscles  of  the  Sole. 


Peroneus  longus 


Plantar  interossei 


~!s-^  Dorsal  interossei 


fourth  toes  from  the  middle  line  of  the  second  toe.  As  the  second  toe  can  be 
abducted  from  its  own  middle  line  in  two  directions,  it  of  course  requires  two 
aljductors. 

Relations. — On  tlie  i)lantar  surfaces  l)oth  sets  of  interossei  are  in  contact  witli 
the  muscles  of  the  third  layer,  and  with  the  external  plantar  vessels  and  nerve;  on 
the  dorsal  surface  Ww  dorsal  interossei  are  covered  by  the  tendons  of  the  extensor 
longus  and  l)revis  digitorum.  The  dorsalis  pedis  and  other  ])erforating  arteries  pass 
tlirough  the  l)ack  of  the  interosseous  spaces  between  the  doul)le  origins  of  the  dorsal 
interossei. 


EXTENSOR  PROPRIUS  HALLUCIS  387 


3IUSCLES  OF  THE  FRONT  OF  THE  LEG 

Between  the  anterior  border  of  the  tibia  and  the  anterior  of  the  two  external 
intermuscular  septa,  are  placed  four  muscles:  the  tibialis  anticus,  the  extensor 
proprius  hallucis,  the  extensor  longus  digitorum,  and  the  peroneus  tertius. 


1.  TIBIALIS  ANTICUS 

The  tibialis  anticus — named  from  its  attachment  to  the  tibia  and  its  position 
in  the  front  of  the  leg — is  fusiform  and  somewhat  flattened,  Avith  a  long  terminal 
tendon. 

Origin. — (1)  Part  of  the  under  surface  of  the  outer  tuberosity  of  the  tibia;  (2) 
the  outer  surface  of  the  upper  two-thirds  of  the  til)ia;  (3)  the  adjacent  part  of  the 
anterior  surface  of  the  interosseous  membrane;  (4)  the  posterior  surface  of  the 
upper  part  of  the  deep  fascia  of  the  leg;  (5)  an  intermuscular  septum  which  sepa- 
rates it  from  the  extensor  longus  digitorum  in  the  upper  third  of  the  leg. 

Insertion. — The  lower  part  of  the  front  of  the  inner  surface  of  the  internal 
cuneiform  Ijone  and  the  adjacent  part  of  the  base  of  the  first  metatarsal  bone. 

Structure. — A  strong  penniform  muscle  the  fibres  of  Avhich,  arising  fleshy 
from  the  bone  and  the  fascia?,  pass  forwards  and  most  of  them  somewhat 
outwards  to  be  attached  to  the  deep  surface  and  outer  border  of  a  tendon,  which, 
beginning  below  the  middle  of  the  leg,  becomes  free  of  fleshy  fibres  two  or  three 
inches  (5  to  8  cm.)  above  the  ankle-joint;  and,  after  passing  first  Iseneath  the 
upper  portion  of  the  anterior  annular  ligament,  then  partly  under  and  partly  over 
the  lower  portion,  expands  slightly  to  be  inserted  upon  the  inner  margin  of  the 
foot.  In  passing  over  the  instep  it  turns  upon  itself  so  that  its  anterior  surface 
becomes  below  internal. 

Nerve- supply. — From  the  anterior  tibial  division  of  the  external  popliteal 
nerve  by  branches  which  enter  the  upper  third  of  the  muscle  upon  the  outer  part 
of  its  deep  aspect. 

Action. — (1)  To  flex  the  ankle-joint;  (2)  to  draw  upwards  the  inner  border  of 
the  foot  and  so  invert  the  sole;  (3)  to  adduct  the  front  portion  of  the  foot.  The 
first  of  these  movements  will  be  performed  chiefly  at  the  ankle-joint;  the  second 
and  third  at  the  medio-tarsal  and  calcaneo-astragaloid  joints.  This  muscle  is  of 
great  importance  in  walking,  as  it  raises  the  anterior  part  of  the  foot  and  so 
enables  the  toes  to  clear  the  ground  when  the  leg  is  swinging  forwards  to  begin 
anotlier  step. 

Relations.— Superficially,  the  deep  fascia;  on  the  outer  side,  the  extensor 
longus  digitorum  and  extensor  pr()i)rius  hallucis  with  the  anterior  tibial  vessels  and 
nerve;  deeply,  the  interosseous  mem])rane  and  the  tibia.  The  tendon  lies  in  a 
special  synovial  sheath  beneath  tlie  two  portions  of  the  anterior  annidar  ligament, 
and  upon  the  ankle-joint  and  inner  bones  of  the  tarsus.  A  small  l)ursa  separates 
the  tendon  from  the  upper  part  of  the  inner  surface  of  the  internal  cuneiform  bone. 

Variations. — A  small  tendon  is  sonietimos  sent  to  the  head  of  the  first  metatarsal  bone,  the 
base  of  the  first  phalanx  of  the  great  toe,  or  to  the  fascia  covering  the  instep. 


2.  EXTENSOR  PROPRIUS  HALLUCIS 

The  extensor  proprius  hallucis — named  from  its  being  the  special  extensor 
belonging  to  the  great  toe  { proprin-^  =  peculiar  to) — is  a  somewhat  triangular  sheet. 

Origin. — (1)  The  middle  two-fourths  of  the  anterior  (nr  extensor)  surface  of  the 
fibula  external  to  the  attachment  of  the  interosseous  membrane;  (2)  the  adjacent 
portion  of  the  anterior  surface  of  the  interosseous  membrane. 

Insertion. — (1)  The  ligamentous  structures  at  the  back  and  sides  of  the  first 


388 


THE  MUSCLES 


metatarso-phalancreal   joint  ;    (2)   tlie   dorsal    aspect    of   the   base   of   the   second 
phalanx  of  the  sreat  toe. 

Structure.— Arising  by  fleshy  fibres  from  the  bone  and  niterosseous  membrane, 


Fig.  297.— The  :\IrscLES  of  the  Fkoxt  of  the  Leg. 


Ligamentum  patellae 


Gaatrocnemius 


Extensor  proprius  hallueis 


Dorsal  interossei    r^^=^ 


Peroneu3 longus 


Tibialis  auticus 


Peroneus  tertius 


Extensor  longus  digitorum 


Peroneus  tertius 


Extensor  brevis  digitorum 


the  muscle  is  inserted  in  a  penniform  manner  into  a  tendon  Avhich  appears  about 
the  middle  of  the  leg  upon  its  inner  and  front  aspect,  and  becomes  clear  of  muscular 
lil)res  al)out  the  level  of  the  ankle-joint.     The  tendon  after  passing  beneath  the 


EXTENSOR   LOXGUS  DIGITORUM  389 

ui)})cr  })art  of  the  anterior  annular  li,iiament  is  included  in  a  special  sheath  beneath 
the  lower  part  of  the  same  lijranient.  Op})osite  the  first  rnetatarso-phalangeal 
joint,  it  gives  off  from  its  sides  and  under  surface  Ijands  of  connective  tissue  which 
unite  partly  with  the  two  lateral  ligaments,  especially  the  internal  one,  and  partly 
with  the  periosteum  upon  the  sides  of  the  first  phalanx.  The  rest  of  the  tendon 
is  tiattened  out  and  fits  closely  to  the  dorsal  aspect  of  the  first  phalanx;  it  is  finally 
attached  to  the  second  phalanx  in  a  transverse  line  which  crosses  the  upper  surface 
of  its  base. 

Nerve-supply. — From  the  anterior  tilnal  Ijy  filaments  which  enter  the  inner 
and  dee]icr  as])ect  of  the  muscle  about  the  middle  of  the  leg. 

Action. — (1)  To  extend  the  first  phalanx  of  the  great  toe;  (2)  slightly  to  extend 
the  second  phalanx,  but  this  movement  is  chiefly  performed  by  the  small  muscles 
of  the  sole  of  the  foot,  which  give  off  expansions  to  Ije  attached  to  the  borders  of 
the  tendon  at  the  sides  of  the  first  phalanx;  (3j  to  .flex  the  ankle,  and  at  the 
same  time  it  will  slightly  adduct  the  front  of  the  foot  and  invert  the  sole.  When 
the  muscle  contracts  strongly  it  will  hyper-extend  the  first  phalanx,  and  at  the 
same  time  flexion  of  the  second  phalanx  will  be  produced  by  the  resistance  of  the 
flexor  longus  hallucis  tendon. 

Relations. — Superficially,  the  deep  fascia,  the  tibialis  anticus,  and  the  extensor 
longus  digitorum;  internally,  the  tibialis  anticus;  externally,  the  extensor  longus 
digitorum;  deeply,  the  interosseous  membrane,  the  tibia,  and  the  anterior  tibial 
vessels  and  nerve.  The  tendon  lies  lieneath  the  two  portions  of  the  anterior  annular 
ligament,  and  after  crossing  the  anterior  tibial  artery  near  the  ankle-joint  it  runs  to 
its  insertion  with  the  dorsalis  pedis  artery  and  the  innermost  tendon  of  the  extensor 
brevis  digitorum  on  its  outer  side. 

Variations. — The  muscle  is  occasionallj'^  divided,  and  a  smaller  external  portion  joins  the 
first  tendon  of  the  extensor  brevis  digitorum,  or  is  inserted  separately  into  the  head  of  the  first 
metatarsal  bone  or  the  base  of  the  first  phalanx. 


8.    EXTENSOR   LOXGUS   DIGITORUM   PEDIS 

The  extensor  longus  digitorum — named  from  its  length  and  its  action  upon  the 
toes — is  fusiform  and  somewhat  flattened,  with  a  four-divided  tendon. 

Origin. — (1)  The  outer  part  of  the  under  surface  of  the  external  tuberosity  of 
the  tibia;  (2)  the  upper  three-fourths  of  the  anterior  or  extensor  surface  of  the 
fibula;  (3)  the  outer  border  of  the  anterior  surface  of  the  interosseous  membrane 
in  its  upper  third;  (4)  the  posterior  surface  of  the  deep  fascia  of  the  leg;  (5)  the 
intermuscular  septa  which  separate  it  from  the  upper  part  of  the  tibialis  anticus 
and  from  the  long  and  short  peronei. 

Insertion. — The  three  phalanges  and  the  metatarso-phalangeal  joints  of  each 
of  the  four  outer  toes. 

Structure. — This  is  a  penniform  muscle,  and  its  fibres  arise  fleshy  from  the 
bones  and  the  fascia,  and  pass  forwards  and  inwards  to  the  back  and  outer  side 
of  the  long  tendon  of  insertion.  This  begins  about  the  middle  of  the  leg,  and 
becomes  free  from  fleshy  fibres  about  the  level  of  the  ankle-joint;  it  passes  behind 
the  upper  part  of  the  anterior  annular  ligament,  but  not  in  a  special  synovial  sheath; 
then  beneath  the  lower  part  of  the  anterior  annular  ligament  in  a  special  synovial 
sheath  with  the  peroneus  tertius.  At  this  point  it  divides  into  four  tendons,  which 
diverge  upon  the  back  of  the  foot  to  the  bases  of  the  four  outer  toes.  Each  tendon 
first  gives  off  some  strong  fibres,  which  blend  with  the  lateral  ligaments  of  the 
metatarso-phalangeal  articulation,  and  with  the  periosteum  along  the  borders  of 
the  first  phalanx.  It  then  forms  a  Inroad  expansion  covering  the  back  of  the  first 
phalanx,  and  divides  into  three  parts:  the  central  part  is  inserted  into  the  dorsal 
aspect  of  the  base  of  the  second  phalanx;  and  the  two  lateral  jxirts  pass  forwiirds 
with  a  slight  convergence  upon  the  back  of  the  second  phalanx  to  be  inserted  into 
the  dorsal  aspect  of  the  base  of  the  third  phalanx. 

Nerve-supply. — From  tlie  anterior  tibial  by  filaments  which  enter  the  deep 
aspect  of  the  muscle  in  its  upper  third. 

Action, — (1)  To  extend  the  first  phalanges  of  the  four  outer  toes.     It  has  some 


390 


THE  MUSCLES 


iiitliu'iue  upon  the  second  and  third  phalanges, 
is  acted  upon  chietly  by  the  short  muscles  in 
attached  to  the  border  of  the  expansion  upon  the 
contracts  to  its  fullest  extent,  the  first  phalanges 
and  third  plialanges  are  sonievrhat  flexed  by  the 
flex  the  ankle-joint.  (3)  Slightly  to  abVluct  and 
Relations. — Superficially,  the  deep  fascia  of 


liut  the  distal  part  of  its  tendon 
the  sole  of  the  foot,  ■which  are 
first  phalanx.  "When  the  muscle 
i  are  extended,  while  the  second 
long  and  short  flexors.  (2)  To 
evert  the  front  part  of  the  foot, 
the  leg  and  the  anterior  annular 


Fig.  298.— The  Miscles  of  the  Doksum  of  the  Foot. 


Extensor  longus  digitorum 


Tibialis  anticus 


EstenBor  brevis  digitorum  — 


Extensor  proprius  hallueis      4  jr— 


Dorsal  interossei 


Peroneus  brevis 


Peroneus  tertius 


Flexor  brevis  minimi  digiti 


ligaments;  on  its  inner  side,  the  tibialis  anticus  and  extensor  proprius  lialluci&,  the 
anterior  tibial  vessels  and  nerve  with  their  continuations  in  the  foot.  Externally, 
the  peroneus  longus  and  brevis,  the  musculo-cutaneous  nerve,  and,  lower  down, 
the  peroneus  tertius.  Behind,  the  anterior  tibial  nerve  above,  and  the  ankle-joint, 
tarsal  and  metatarsal  bones,  and  the  extensor  brevis  digitorum  below. 

Variations. — The  muscle  may  be  divided  nearly  up  to  its  origin.  Tt  may  give  off  slips  to 
the  extensor  jiroprius  liallncis,  extensor  brevis  digitorum,  or  one  of  the  iuterossei.  Sometimes 
also  it  has  au  insertion  into  some  of  the  metatarsal  bones. 


EXTENSOR  B RE  VIS  DIGITORUM  391 


4.  PEROXEUS  TERTIUS 


The  peroneus  tertius — named  from  -e/ji'i>r,,  the  fibula,  and  caWed  tertius  because 
it  is  the  third  of  the  muscles  which  jjass  from  the  fibula  to  the  metatarsus — is  a 
small  triangular  sheet  which  is  closely  blended  with  the  preceding  muscle. 

Origin. — (1)  The  lower  fourth  of  the  anterior  (or  extensor)  surface  of  the 
fibula;  (2)  the  front  of  the  interosseous  membrane  for  a  short  distance  above  the 
ankle-joint;   (3)  the  external  intermuscular  septum  and  the  deep  fascia  of  the  leg. 

Insertion. — The  upper  part  of  the  base  of  the  fifth  metatarsal  bone. 

Structure. — Arising  fieshy,  the  muscular  fibres  pass  downwards  and  inwards 
in  penruform  fashion  to  a  tendon  which  appears  on  the  inner  border  of  its  anterior 
surface.  It  becomes  free  from  fleshy  fibres  at  the  level  of  the  ankle-joint,  and 
after  passing  beneath  the  upper  part  of  the  anterior  annular  ligament,  it  is  in- 
cluded with  the  extensor  longus  digitorum  in  a  special  synovial  sheath  beneath  the 
lower  part  of  the  ligament,  and  finally  diverges  from  it  to  be  inserted  into  the  inner 
part  of  the  upper  surface  of  the  base  of  the  fifth  metatarsal  bone. 

Nerve-supply. — Unlike  the  other  peronei,  which  are  supplied  by  the  musculo- 
cutaneous nerve,  it  receives  filaments  from  the  anterior  tibial  Avhich  enter  the 
inner  and  deep  aspect  of  the  muscle  in  the  upper  part  of  its  course. 

Action. — (1)  To  flex  the  ankle-joint;  (2_)  to  abduct  the  anterior  part  of  the 
foot;  (3)  slightly  to  elevate  the  outer  border  of  the  foot  and  so  to  produce  eversion 
of  the  sole. 

Relations. — Superficially,  the  anterior  annular  ligament  and  branches  of  the 
musculo-cutaneous  nerve;  on  the  inner  side,  the  extensor  longus  digitorum,  oi 
which  it  is  really  a  subdivision;  on  the  outer  side,  the  peroneus  brevis;  deeply, 
the  ankle  and  outer  tarsal  joints  with  the  extensor  brevis  digitorum. 

Variations. — The  peroneus  tertius  is  often  closely  blended  with  the  extensor  longus  digi- 
tomm.  It  is  sometimes  wanting,  and  replaced  by  a  slip  of  tendon  from  the  extensor  longus 
digitorum.  Occasionally  it  sends  slips  of  tendon  to  the  expansion  of  the  extensor  longus 
digitorum  on  the  first  phalanx  of  the  two  outer  toes,  or  to  the  fourth  dorsal  interosseous. 


MUSCLE  OX  THE  DORSUM  OF  THE  FOOT 

This  consists  of  the  four  bellies  of  one  muscle — the  extensor  brevis  digitorum, 

EXTEXSOR   BREVIS    DIGITORUM   PEDIS 

The  extensor  brevis  digitorum — named  from  its  being  the  shorter  of  the  two 
muscles  which  extend  the  toes — is  a  triangular  sheet  which  breaks  up  in  front  into 
four  small  divisions. 

Origin. — (1)  The  outer  part  of  the  upper  surface  of  the  great  process  of  the 
calcaneum;  (2)  the  interior  of  the  loop  of  fascia  Avhich  forms  the  outer  jiart  of  the 
lower  anterior  annular  ligament. 

Insertion. — By  four  tendons  into  the  four  inner  toes;  the  innermost  is  attached 
to  the  outer  border  of  the  upper  surface  of  the  first  ]ihalanx  of  the  great  toe  near 
its  base;  the  three  other  tendons  to  the  outer  l)order  of  the  tendons  of  the  extensor 
longus  digitorum  just  in  front  of  the  bases  of  the  first  phalanges. 

Structure. — Arising  superficially  by  fleshy,  and  on  the  deep  surface  by  short 
tendinous  iil)res,  the  muscle  diverges  inwards  and  forwards,  and  soon  divides  into 
four  fleshy  bellies,  of  which  that  to  the  great  toe  is  the  largest  and  most  separate. 
Each  portion  has  a  bipenniform  arrangement,  with  its  central  tendon  upon  the 
dorsal  surface,  and  becoming  free  opposite  the  middle  of  the  metatarsus. 


392  THE  MUSCLES 

Nerve-supply. — From  the  anterior  til)ial  nerve  l)y  small  filaments  wl)icli  enter 
the  deep  surface  of  the  muscle  near  its  inner  border  as  it  crosses  the  cuhoiil  and 
external  cuneiform  Ijones. 

Action. — (1)  To  extend  the  four  inner  toes.  In  the  case  of  the  outer  toes  the 
two  last  phalanges  will  be  chietl}'  extended,  and  the  obliquity  of  its  insertion,  by 
causing  it  to  draw  the  toes  somewhat  outwards  at  the  same  time  that  it  extends 
them,  will  enaljle  it  to  correct  the  opposite  tendency  of  the  long  extensor.  (2) 
The  innermost  tendon  will  act  as  an  adductor  of  the  first  jjludanx  of  the  great  toe. 

Relations. — Superficially,  the  tendons  of  the  extensor  longus  digitorum  and 
peroneus  tertius;  deeply,  the  tarsal  and  tarso-metatarsal  joints;  and,  in  the  case  of 
the  tendon  to  the  great  toe,  the  dorsalis  pedis  vessels  and  the  termination  of  the 
anterior  tibial  nerve. 

Variations. — The  number  of  tendons  may  be  diminished  or  increased.  Sometimes  a  tendon 
is  given  to  the  little  toe.  Accessory  bundles  maybe  derived  from  some  of  the  tarsal  or  mt_'t;i- 
tarsal  bones,  and  slii)S  have  been  found  running  to  the  dorsal  interossei ;  and  also  a  small  slip 
between  the  first  and  second  bellies,  going  to  the  inner  side  of  the  second  toe  or  its  metatarsal 
bone. 


MUSCLES  Oy  THE  OUTER  SIDE  OF  THE  LEG 

These  are  two  muscles — the  peroneus  longus  and  Ijrevis — situated  upon  the  outer 
side  of  the  fil^ula  in  a  compartment  of  quadrilateral  section,  bounded  internally 
by  the  fibula,  in  front  and  behind  by  intermuscular  septa,  and  externally  by  the 
deep  fascia  of  the  leg. 

1.  PERONEUS   LONGUS 

The  peroneus  longus  (figs.  292  and  296) — named  from  its  l^eing  the  longer  of 
the  two  filjular  muscles — is  long  and  fusiform. 

Origin. — (1)  The  outer  tuberosity  of  the  tibia  by  a  few  fibres;  (2)  the  front  of 
the  head  of  the  fibula;  (3)  the  upper  two-thirds  of  the  outer  (or  peroneal)  surface 
of  the  fibula,  occupying  the  whole  of  this  surface  above,  and  the  posterior  half  of 
it  below;  (4)  the  inner  surface  of  the  deep  fascia  of  the  leg,  and  the  opjoosed  sur- 
faces of  the  two  external  intermuscular  septa. 

Insertion. — (1)  The  low^er  part  of  the  outer  surface  of  the  base  of  the  first 
metatarsal  bone;  (2)  the  lower  part  of  the  outer  surface  of  the  internal  cuneiform 
bone  close  to  its  articulation  with  the  first  metatarsal  bone. 

Structure. — This  is  a  strong  penniform  muscle,  the  short  fleshy  fibres  of  which 
pass  downwards,  and  for  the  most  part  forwards,  to  be  inserted  into  the  tendon 
Avhieh,  beginning  al)out  three  inches  (7 "5  cm.)  below^  the  head  of  the  fii^ula,  runs 
along  the  front  of  the  outer  surface  of  the  muscle,  and  becomes  free  in  the  lower 
third  of  the  leg.  It  then  passes  behind  the  outer  ankle,  beneath  the  external 
annular  ligament,  in  a  special  sheath  with  the  tendon  of  the  i^eroneus  l)revis,  which 
lies  in  front  of  it.  On  the  outer  surface  of  the  calcaneum,  it  runs  forwards  and 
downwards  in  a  s])ecial  compartment  of  the  external  annular  ligament  below  the 
comi)anion  tendon.  At  the  outer  border  of  the  foot  it  again  changes  its  direction, 
and  i)asses  obliquely  inwards  and  forwards  across  the  sole  of  the  foot,  in  a  canal 
formed  by  the  long  plantar  ligament  beneath,  and  by  the  groove  in  the  cuboid  bone 
above,  to  its  insertion  near  the  inner  side  of  the  sole.  In  the  upper  two-thirds  of 
the  leg  the  peroneus  longus  almost  entirely  conceals  from  view  the  peroneus  l)revis, 
Avhieh  lies  beneath  and  slightly  anterior  to  it. 

The  synovial  tube  which  it  enters  at  the  outer  ankle  is  common  to  it  and  the 
peroneus  brevis,  and  bifurcates  to  accompany  the  two  tendons  Avhere  they  are 
separated  by  the  jx'roneal  tul)ercle  of  the  os  calcis.      A  second  sheath  envelopes  the 


PEROXEUS  BREVIS  393 

tendon  in  the  sole,  and  where  the  tendon  enters  this  canal  it  often  contains  a 
sesamoid  l>one  which  jtlays  upon  the  front  of  the  ridge  of  the  cnl)oid  bone. 

Nerve-supply. — From  the  musculo-cutaneous  branch  of  the  external  popliteal 
nerve  by  filaments  which  enter  the  deep  and  posterior  asjject  of  the  muscle  in  its 
upper  third. 

Action. — (1)  To  extend  the  ankle-joint;  (2)  to  al)duct  the  anterior  part  of  the 
foot;  (3)  to  depress  the  inner  l)order  of  the  foot,  and  so  to  evert  the  sole;  (4)  by 
drawing  backwards  and  outwards  the  base  of  the  first  metatarsal  bone,  it  tends  to 
render  more  concave  the  antero-posterior  and  transverse  arches  of  the  foot.  In  the 
former  action  it  assists  the  tibialis  i>osticus  and  flexor  longus  hallucis. 

In  walking,  it  will  act  with  the  gastrocnemius  and  soleus  in  lifting  the  heel  from 
the  ground,  and  its  tendency  to  evert  the  sole  and  abduct  the  foot  will  counteract 
the  opposite  tendency  of  the  muscles  attached  to  the  tendo  Achillis.  ^Moreover,  the 
tendenc}'  of  this  latter  set  of  muscles  is  to  press  the  outer  part  of  the  ball  of  the 
toes  firmly  upon  the  ground.  On  the  other  hand,  the  influence  of  the  peroneus 
longus  in  extending  the  foot  is  especially  exerted  upon  the  ball  of  the  great  toe. 
By  the  combined  action  of  all  these  extensors  of  the  ankle  the  whole  of  the  ball 
of  the  foot  is  pressed  evenly  upon  the  ground  and  firmness  of  tread  secured. 

Relations. — Superficially,  the  deep  fascia,  the  external  annular  ligament;  and 
in  the  sole,  the  abductor  minimi  digiti,  the  adductor  hallucis,  and  long  plantar 
ligament;  in  front,  the  peroneus  brevis,  the  extensor  longus  digitorum,  and  the 
musculo-cutaneous  nerve;  behind,  the  soleus  and  flexor  longus  hallucis;  deeply, 
the  external  popliteal  nerve  which  occupies  a  fibrous  canal  below  the  head  of  the 
filnila,  the  ankle-joint,  calcaneum,  cuboid,  and  the  bases  of  the  second  and  third 
metatarsal  bones. 

Variations. — Sometimes  a  second  peroneus  arises  between  the  peroneus  longus  and  brevis, 
and  sends  its  tendon  to  join  that  of  the  peroneus  longus.  A  slip  may  be  given  to  the  external 
annular  ligament.  The  insertion  of  the  muscle  may  extend  to  the  bases  of  the  adjacent  meta- 
tarsal bones. 

2.   PEROXEUS  BREVIS 

The  peroneus  brevis  (figs.  292  and  298) — named  from  its  being  the  shorter  of 
the  two  fibular  muscles — is  also  a  triangular  sheet. 

Origin. — (1)  The  lower  two-thirds  of  the  outer  (or  peroneal)  surface  of  the 
fiV)ula;  (2)  the  deep  fascia  of  the  leg  and  the  intermuscular  septa  in  front  and 
behind. 

Insertion. — (1)  The  outer  part  of  the  base  of  the  fifth  metatarsal  bone;  (2) 
the  outer  l)order  of  the  expansion  of  the  tendon  of  the  extensor  longus  digitorum 
upon  the  first  phalanx  of  the  little  toe. 

Structure. — This  is  also  a  penniform  muscle.  The  short  fibres  pass  obliquely 
downwards  to  the  tendon  which  lies  upon  the  outer  surface  of  the  muscle.  It 
becomes  free  from  fleshy  fibres  just  above  the  external  malleolus  where  it  passes 
beneath  the  external  annular  ligament  in  the  same  sheath  with  the  peroneus  longus 
tendon,  and  after  changing  its  direction,  runs  forwards  and  somewhat  downwards 
upon  the  outer  surface  of  the  calcaneum  and  above  the  peroneal  tubercle. 

Nerve-supply. — The  musculo-cutaneous  branch  of  the  popliteal  nerve  by  fila- 
ments which  enter  the  deej)  aspect  of  the  muscle  about  the  middle  of  the  leg. 

Action. — (1)  Slightly  to  extend  the  ankle;  (2)  to  abduct  the  anterior  part  of 
the  foot;   (3)  slightly  to  elevate  the  outer  border  of  the  foot,  and  so  evert  the  sole. 

Relations. — Superficially,  the  peroneus  longus,  deep  fascia  of  the  leg  and 
external  annular  ligament;  in  front,  the  extens(ir  longus  digitorum  and  peroneus 
tertius;  Ijehind,  the  peroneus  longus  and  flexor  longus  hallucis;  deeply,  the  ankle- 
joint,  calcaneum,  and  cuboid  bones. 

Variations. — The  small  slip  which  the  tendon  sends  on  to  the  expansion  upon  the  little  toe 
may  be  wanting,  or  it  may  be  inserted  into  tlie  first  or  even  the  second  phalanx.  This  slip  may 
be  entirely  separate,  so  as  to  form  a  fourth  peroneus. 


394 


THE  MUSCLES 


Fig.  '2!)S).— The  Extekxal  Ixtercostai.s  and  Levatores  Costarum. 

I'll--     <gS5 


Complexua 

Obliquus  superior 

Rectus  capitis  posticus  major 

Obliquus  inferior 

Multifldus  spinae 

Semispmalis  colli 
Cerviealis   ascendeus 

Longissimus  dorai 


Levator  coat  i 


Longissimus  dorsi 
Ilio-eostalis 

Obliquus  internus  

Lumbar  fascia '■ 

Ilio-costalis 


ectua  capitis  posticus 
minor 


SEVENTH  CERVICAL  VERTEBRA 


Semispinalis  dorsi 


Multifldus  spinae 


O 

*r      /  ^J—  TWELFTH  THORACIC  VERTEBRA 


Multifldus  spinae 


FIFTH  LUMBAR  VERTEBRA 


Multifldus  spinae 


EXTERNAL  AND  L\TER.\AL  IXTERCOSTALS  395 


THE  MUSCLES  OF  THE  THORAX 

These  consist  of  six  muscles,  or  sets  of  muscles,  which  are  attached  chiefly  to 
the  ribs,  their  cartilages,  and  the  sternum:  viz.  the  external  and  internal  inter- 
costals,  thelevatores  costarum,  the  triangularis  sterni,  infracostales  (or  subcostales), 
and  diaphragm. 

Intercostal   Muscles 

The  intercostal  muscles — named  from  their  position — are  long  narrow  sheets 
of  short  oblique  muscuhvr  filjres  Avhich  occupy  the  intercostal  spaces.  The  fibres 
of  the  outer  sheet  run  downwards  and  forwards,  and  those  of  the  inner  downwards 
and  backwards;  and  the  two  sheets  are  the  upper  continuations  of  the  obliquus 
extenius  and  internus  of  the  abdominal  Avail. 


1.  THE  EXTERNAL  INTERCOSTALS 

The  external  intercostals,  AA'hich  are  stronger  than  the  internal,  are  eleven  in 
number,  and  till  the  spaces  between  the  ribs  from  the  tubercle  to  the  tip.  In  the 
higher  spaces,  however,  they  do  not  come  quite  so  far  forwards  as  below.  Above, 
the  lower  attachment  barely  reaches  the  tij)  of  the  rib;  while  below,  the  upper 
attachment  reaches  the  tip,  and  the  lower  is  upon  the  cartilage. 

Origin. — The  lower  or  outer  border  of  all  the  ribs  except  the  last,  from  tubercle 
to  anterior  extremity. 

Insertion. — The  outer  aspect  of  the  upper  border  of  all  the  ribs  but  the  first 
from  a  little  in  front  of  the  tubercle  to  the  tip,  or  in  the  lower  ribs  for  a  short 
distance  upon  the  cartilage. 

Structure. — Composed  of  obliquely  directed  parallel  bundles  of  fleshy  fibre, 
with  a  short  tendinous  origin,  and  with  a  slight  admixture  of  fibrous  tissue.  The 
posterior  are  more  oblique  than  the  anterior  fibres.  The  sheet  formed  by  their 
fibres  is  thickest  behind,  and  becomes  gradually  thinner  forwards.  Between  the 
cartilages  it  is  succeeded  by  a  thin  memljrane,  the  external  intercostal  fascia, 
which  is  composed  of  fibres  running  with  the  same  slope  as  those  of  the  muscle. 

Nerve-supply. — The  intercostal  nerves  as  they  run  forwards  give  numerous 
filaments  to  the  inner  surfaces  of  the  muscles. 

Action. — See  later. 

Relations. — Superficially,  the  pectoralis  major  and  minor,  the  serratus  magnus, 
the  external  oblique,  the  latissimus  dorsi,  the  trapezius,  rhomboidei,  the  serrati 
postici,  the  continuation  upAvards  of  the  erector  spinae,  and  the  levatores  costarum ; 
deeply,  the  internal  intercostals  and  infracostales,  the  intercostal  A^essels  and  nerA'es. 


2.  THE  INTERNAL  INTERCOSTALS 

The  internal  intercostals  are  eleven  in  number,  and  fill  the  spaces  from  the 
angles  of  the  ribs  to  the  anterior  extremities  of  the  cartilages.  The  filn-es,  Avhich 
are  shorter  and  not  quite  so  oblique  as  those  of  the  outer  slieet,  are  directed  doAvn- 
Avards  and  backAvards. 

Origin. — The  upper  border  of  the  subcostal  groove  of  the  eleven  upper  ribs 
from  the  angle  forAvards,  and  the  continuation  of  this  border  upon  the  cartilages. 

Insertion. — The  inner  asjiect  of  the  upper  border  of  the  eleven  lower  rilts  and 
cartilages. 

Structure. — The  sheets  are  thicker  in  front.  There  is  less  fibrous  tissue  mixed 
Avith  the  flesliy  fibres  than  in  the  outer  sheet.  In  the  upper  and  loAver  spaces  the 
fleshy  fibres  are  continued  a  little  finther  Ijack  than  the  angles.     The  rest  of  the 


396 


THE  MUSCLES 


space  behind  the  thin  posterior  border  of  the  sheet  is  filled  by  a  thin  niemln'ane 
composed  of  fibres  running  in  the  same  direction,  and  is  called  the  internal 
intercostal  fascia. 

Nerve-supply. — Branches  from  the  intcnvostal  nerves,  which  are  sui)])]icd  to  its 
outer  surface  or  are  given  off  where  the  nerves  are  concealed  in  the  interior  of  the 
muscle. 

Action. — See  below. 

Relations. — Superficially,  the  external  intercostal  muscles,  and  the  intercostal 
arteries  and  nerves;  deeply,  the  triangularis  sterni,  infracostales,  dia})hragm,  and 
the  pleura. 

The  action  of  the  intercostal  muscles  generally  is  to  ai^proximate  the  ril)s  to  one 
another,  and  they  are  chiefly  used  in  inspiration.     The  obliquity  of  their  fibres  en- 


Exterual 
intercoatals 


Internal 
intercostals 


Fig.  300. — The  Intercostal  Mt^scles. 

A 


External 
intercostals 


Internal 
intercostals 


Infra -eostales 


al)les  them  with  a  small  contraction  to  i)roduce  a  greater  approximation  than  if  they 
ran  peri)en(licidarly  between  the  ribs  (page  287).  Moreover,  if  the  fibres  were  all 
directed,  like  those  of  the  outer  sheet,  downwards  and  forwards,  there  would  be  a 
tendency  for  the  lower  ribs  to  be  drawn  backwards  as  well  as  upwards  in  inspiration; 
and  if,  on  the  other  hand  all  the  fibres  were  directed  downwards  and  ])ackwards  like 
those  of  the  inner  sheet,  the  tendency  Avould  be  for  the  lower  ribs  to  be  drawn 
forwards  as  well  as  u])wards  in  inspiration.  The  combined  action  of  the  two  sets 
produces  the  direct  elevation  of  the  ril:»s,  the  forward  pull  of  the  iimer  sheet  being 
counteracted  by  tlie  l)ackward  ])ull  of  the  outer  sheet.  If  the  external  intercostals 
were  carried  forwards  as  far  as  the  sternum,  they  would  tend  to  take  the  sternum 
as  a  fixed  ])oint  and  to  de])ress  the  anterior  extremities  of  the  ril)s.  A  similar  result 
would  follow  the  continuation  ))ackwards  of  the  internal  intercostals  to  the  vertel)ral 


LEVATORES  COSTARUM  397 

eciluinn.  It  \vill  1)0  also  ni)ticed  that  the  front  })art  of  tlie  external,  and  the  hack  i)art 
of  the  internal  intercostal  sheets  are  thin  and  weak,  so  as  to  diniinisli  this  tendency 
towards  an  ex])iratorv  movement.  It  has  been  urged  that  both  sets  of  intercostals 
cannot  approximate  the  ril)s,  as  in  inspiration  some  of  the  intercostal  spaces  are  seen 
to  open  out  and  become  wider.  To  this  it  may  be  replied  that,  whatever  happens  in 
some  of  the  spaces,  it  is  certain  that  the  general  tendency  is  that  of  approximation 
of  the  ribs,  and  diminution  of  the  intervals  between  them,  as  after  a  full  inspiration 
the  last  rib  is  nearer  to  the  first  rib.  Moreover,  it  does  not  always  follow  that 
because  a  muscle  is  lengthening  it  is  not  acting  (cf.  such  cases  as  that  of  the  long 
head  of  the  triceps  when  it  is  used  in  extending  the  elbow  during  the  elevation 
of  the  arm)-  If  when  most  of  the  ribs  are  being  approximated  it  shovdd  happen 
that  some  of  tlie  spaces  are  found  to  be  widened,  the  action  of  the  muscle  in  these 
widened  spaces  will  probal^ly  be  to  prevent  a  greater  separation,  and  by  steadying 
the  lower  ribs  to  enable  the  muscles  which  descend  from  them  to  act.  When  the 
lowest  rib  is  fixed  by  the  quadratus  lumborum  and  other  muscles,  it  is  probal)le 
that  the  intercostals,  at  any  rate  those  of  the  lower  spaces,  by  approximating 
the  lower  ribs  to  the  last  rib,  may  act  as  muscles  of  expiration.  The  follow- 
ing are  some  of  the  arguments  which  may  be  adduced  in  support  of  the  view 
that  both  sets  of  intercostals  act  together,  and  also  that  their  action  is  usually 
inspiratory. 

1.  The  advantage  already  mentioned,  from  their  o1:)lique  decussation  enabling 
them  to  approximate  the  ribs  more  completely  and  at  the  same  time  to  elevate  them 
directly  when  they  act  in  combination  (cf.  the  action  of  the  external  and  internal 
ol)lique  in  approximating  the  last  rib  to  the  crest  of  the  ilium). 

2.  ^luscles  supplied  by  the  same  nerve  are  rarely  antagonistic. 

3.  In  long-standing  paralysis  of  the  intercostals  the  sternum  is  depressed,  the 
chest  flattened,  and  kept  in  a  permanent  condition  of  exaggerated  expiration. 

4.  Galvanism  of  the  intercostals  produces  expansion  of  the  chest.  In  Du- 
chenne's  experiment  he  found  that  when  he  galvanised  so  slightly  as  only  to  affect 
the  external  intercostals,  the  inspiratory  movement  was  small;  but  when  he  gal- 
vanised so  strongly  as  to  affect  the  nerve,  and  through  the  nerve  the  internal 
intercostals — as  was  known  by  the  contraction  of  muscular  fibre  being  felt  between 
the  cartilages  of  the  ribs,  in  which  situation  the  only  fleshy  fibres  are  those  of  the 
inner  set — a  strong  inspiratory  movement  was  produced. 

From  the  peculiar  shape  of  the  ribs  and  the  mode  of  their  articulation,  their 
elevation  is  accompanied  b}''  a  rotation  of  the  arcs  formed  by  them  upon  their 
chords  so  that  their  planes  from  a  slojjing  attain  an  almost  horizontal  position. 
Hence  the  widening  of  the  chest  during  inspiration,  in  addition  to  its  expansion 
from  before  backwards  due  to  the  forward  elevation  of  the  tips  of  the  ribs. 


3.  LEVATORES  COSTARUM 

The  levatores  costarum  (fig.  299) — named  from  their  action,  as  elevators 
of  the  ribs — are  twelve  triangular  sheets,  winch  cover  the  back  part  of  the  inter- 
costal spaces,  and  are  continuous  with  the  fibres  of  the  external  intercostal 
muscles. 

Origin. — The  tips  of  the  transverse  processes  of  the  last  cervical,  and  all  the 
thoracic  vcrteln'ic  except  the  last. 

Insertion. — The  outer  surface  of  the  ribs  from  the  tubercle  to  the  angle. 

Structure. — Arising  by  short  tendinous  fibres  the  nuiscle  expands  in  a  fan 
sha}K',  and  is  attached  to  the  next  i-il^  lielow.  Fre(iuently  fil)res  pass  over  one  rib 
and  are  inserted  upon  the  next  but  one. 

Nerve-supply. — The  intercostal  nerves  which  send  l)ranches  to  their  deep 
surfaces. 

Action. — To  elevate  the  ribs  in  inspiration. 

Relations. — Superficially,  the  outer  and  upward  continuations  of  the  erector 
spina-;  deeply,  the  external  intercostals,  which  are  continuous  with  the  outer  border 
of  the  muscles. 


398 


THE  MUSCLES 


4.  TRIANGULARIS  STERNI 

As  the  external  and  internal  ol)li(|ue  nuiscles  of  the  aljdonien  are  rej^resented 
1)y  the  external  and  internal  intercostals  in  the  thorax,  so  also  the  transversalis 
abdominis  has  its  counterpart  in  the  thin  stratum  of  muscular  fibre  at  the  sides  of 
the  sternum  called  the  triangularis  sterni,  and  the  still  thinner  expansion  behind 
of  the  infracostales. 

The  triangularis  sterni — named  from  its  shape  and  its  connection  with  the 
sternum — is  a  thin,  musculo-membranous,  triangular  sheet,  with  the  apex  below 
and  directed  internally,  Avhile  the  serrated  base  is  external. 

Origin. — (1)  The  side  of  the  lower  third  of  the  back  of  the  sternum;  (2)  the 
upi)er  and  lateral  part  of  the  back  of  the  ensiform  cartilage;  (3)  the  back  of  the 
inner  ends  of  the  fifth,  sixth,  and  seventh  costal  cartilages. 


Fig.  301. — The  Muscles  attached  to  the  Back  of  the  Steexum. 


Sterno-hyoid 


Sterno-thyroid 


Sternal  origin 
of  diaphragm 


Costal  origin 
of  diaphragm 


Triangularis 
Bterni 


Transversalis  abdominis 


Insertion. — The  outer  ends  of  the  posterior  surfaces  and  lower  borders  of  the 
cartilages  of  the  second  or  third  to  the  sixth  ribs,  and  occasionally  the  tips  of  the 
ribs  also. 

Structure. — The  muscle  is  membranous  at  its  origin  and  insertion,  and  it  con- 
tains maiiy  Ixuids  of  fibrous  tissue.  Its  fibres  diverge  fanwise,  the  lower  ones 
being  horizontal,  and  in  serial  continuation  with  the  ui)pcr  digitations  of  the  trans- 
versalis abdominis,  while  its  higher  fibres  run  ol:)li(iucly  ujiwards  and  outwards. 

Nerve-supply. — The  upper  intercostals,  which  send  filaments  to  its  anterior 
aspect. 

Action. — To  depress  the  anterior  extremities  of  the  ribs  to  Avhich  it  is  attached, 
and  so  to  help  in  ex])iration. 

Relations. — In  front,  the  internal  intercostals  and  internal  mammary  vessels; 
behind,  the  pleura  and  pericardium. 


INFRACOSTALES— DIAPHRAGM  399 


5.    INFRACOSTALES 

Theinfracostales,  orsubcostales — named  from  their  position  beneath  the  ri1)S 
— form  a  thin  n)usculo-meml)ranous  sheet  lining  the  back  of  the  thorax  external  to 
the  tnljercles  of  the  ribs;  l)roader  and  better  developed  below,  becoming  narrower 
and  thinner  above.  Frequently  it  consists  of  only  a  few  bundles  of  fibres  whicli 
can  be  distinguished  from  the  internal  intercostals  by  the  fact  that  they  are  not 
confined  to  one  intercostal  space. 

Origin. — The  lower  part  of  the  inner  surface  of  the  ribs  near  their  angles. 

Insertion. — The  upper  part  of  the  inner  surface  of  the  ribs,  each  bundle  of 
filires  usually  passing  over  one  rib  to  be  inserted  upon  the  next  higher. 

Structure. — The  filjres  arise  tendinous,  run  upwards  and  outwards,  and  have 
tendinous  insertions.  The  higher  fibres  riin  more  vertically.  The  lower  approach 
nearer  to  the  vertebral  column,  arising  from  the  ribs  just  external  to  their  tubercles. 

Nerve-supply. — The  intercostal  nerves,  which  enter  their  outer  surface. 

Action. — To  depress  the  ribs,  and  assist  in  expiration. 

Relations. — Externally,  the  external  and  internal  intercostal  muscles;  intern- 
ally, the  parietal  layer  of  the  pleura,  which  is  separated  from  them  by  a  thin 
aponeurosis  sometimes  called  the  endothoracic  fascia. 


6.  THE  DIAPHRAGM 

The  diaphragm — named  from  its  function  as  the  (^idcpayij-a^  or  partition  wall 
betw^een  the  thorax  and  abdomen — is  a  dome-shaped  musculo-membranous  sheet  of 
a  kidney-shaped  outline  when  seen  from  above,  and  consists  of  a  pair  of  muscles 
with  a  lateral  origin  and  a  central  aponeurotic  insertion,  resembling  the  two 
transversales  abdominis,  which  unite  in  the  linea  alba  so  as  also  to  form  a  single 
dome-shaped  biventral  muscle. 

Origin. — By  three  portions: — 

1.  Anterior  or  sternal  portion. — The  lower  border  and  back  of  the  ensiform 
cartilage,  and  the  adjacent  part  of  the  back  of  the  anterior  aponeurosis  of  the 
transversalis  abdominis. 

2.  Lateral  or  costal  portion. — The  lower  borders  and  inner  surfaces  of  the 
cartilages  of  the  six  lower  ribs,  and  sometimes  also  from  the  adjacent  part  of 
the  ribs. 

3.  Posterior  or  vertebral  portion. — (1)  The  ligamentum  arcuatum  exter- 
num, a  fi])rous  thickening  of  the  anterior  layer  of  the  lumbar  fascia,  uhieh  stretches 
from  the  tip  of  the  transverse  process  of  the  second  lumbar  vertel)ra  to  the  tip  of  the 
last  rib;  (2)  the  ligamentum  arcuatum  internum — a  fibrous  thickening  of  the 
iliac  fascia,  which  arches  over  the  upper  part  of  the  psoas  from  the  side  of  the  l)ody 
of  the  second  lumbar  vertebra  to  the  tip  of  its  transverse  process;  (3)  the  crus  of 
the  diaphragm — a  strong  vertical  band,  fleshy  externally,  tendinous  internally — 
arising  on  the  right  side  from  the  front  of  the  bodies  of  the  first  to  the  third  or 
fourth  lumbar  vertebrae,  from  the  intervening  vertebral  discs,  and  the  anterior 
common  ligament;  on  the  left  side,  from  the  bodies  of  the  first  to  the  second  or 
third  vertebrte  only,  as  well  as  the  discs  and  anterior  common  ligament. 

Insertion. — The  front,  sides,  and  back,  of  the  central  tendon. 

Structure. — The  fibres,  arising  fleshy  from  their  extensive  origin,  pass  at  first 
vertically  upwards,  and  then  arch  inwards  to  be  attached  to  the  borders  of  the 
central  tendon.  The  sternal  filires  are  the  shortest,  and  they  are  often  separated 
from  the  costal  portion  by  a  small  triangular  interval  filled  with  areolar  tissue,  and 
giving  passage  to  the  superior  epigastric  vessels.  The  costal  origin  forms  a  series 
of  teeth  Avhich  do  not  correspond  accurately  Avith  the  number  of  ribs,  some  rib 
cartilages  having  two  teeth  attached  to  them.  They  interdigitate  with  the  serrations 
of  the  transversalis  abdominis  (fig.  301).  The  aponeurotic  fibres  which  form  the 
inner  portion  of  the  two  crura,  after  arching  in  front  of  the  abdominal  aorta,  are 
continued  1>y  fleshy  fibres  which  decussate,  and  so  changing  sides  form  a  loop  round 
the  oesophagus  before  joining  the  central  aponeurosis. 


400 


THE  MUSCLES 


The  central  tendon,  or  a]-»oneurosis,  forms  the  suiiniiit  of  the  dome,  and  is  of  a 
similar  outhne  to  the  (haphragm,  hein<f  kidney-shaped,  -with  the  concavity  hehind. 
It  approaches  nearer  the  back  than  the  front  of  the  thorax.  There  is  a  sHght 
notching  of  its  outUne  in  front,  which  divides  it  into  three  parts,  so  that  it  has 
somewhat  of  a  trefoil  shape,  the  right  leaflet  being  the  largest,  and  the  left  the 
smallest.     Its  fibres  run  in  many  directions. 

The  diaphragm  contains  three  large  foramina,  for  the  passage  of  the  vena  cava 
inferior,  a?sophagus,  and  aorta. 

Foramina. — Close  to  the  posterior  border  of  the  central  tendon  at  the  junction 
of  the  right  and  middle  leaflet  is  a  quadrilateral  opening  Avith  rounded  angles,  the 
foramen  for  the  vena  cava  inferior,  the  outer  coat  of  which  vessel  is  blended  with  its 
fibrous  edges.  The  (esophageal  opening  is  oval,  with  the  long  diameter  directed 
forwards.  It  is  surrounded  by  fleshy  fil^res,  and  lies  to  the  left  of  the  middle  line, 
opposite  the  bod}'  of  the  tenth  thoracic  vertebra.  Through  it  passes  the  oesophagus, 
v,-ith  the  left  vagus  nerve  in  front,  and  the  right  behind;  also  a  few  small  oesophageal 
Vjranches  from  the  thoracic  aorta,  on  their  way  to  join   some  small  cesojihageal 


Fig.  302. — Diaphragm. 


Opening  for  vena 
cava  inferior 


Right  division  of 
tendon 


Psoas  parvus 


Psoas 
Transversalis 


Quadratus 
lumborum 


Sternal  origin 


Middle  division 
of  tendon 


CEsophagus 


Left  division  of 
tendon 


Costal  origin 


Ligamentum 

areuatum 

internum 
Left  erus 
Ligamentum 

areuatum 

externum 
Transverse 

process  of 

second  lumbar 

vertebra 
Fourth  lumbar 
vertebra 


branches  from  the  gastric  artery.  The  aortic  opening,  formed  by  the  union  of  the 
crura,  is  fibrous,  and  of  oval  shape.  It  is  situated  in  front  of  the  twelfth  thoracic 
vertebra,  and  is  completed  behind  by  the  anterior  common  ligament.  Through  it 
pass  the  aorta,  the  vena  azygos  major,  and  the  thoracic  duct.  In  the  crura  on 
either  side  are  small  openings  which  allow  of  the  passage  of  the  great  splanchnic 
nerves,  and  the  left  crus  is  usually  perforated  also  by  the  vena  azygos  minor. 

Nerve -supply. — The  two  phrenic  nerves,  chiefly  derived  from  the  cervical  plexus 
of  each  side  tlirough  the  fourth  cervical  nerves,  break  up  close  to  the  diajihragm 
into  many  filaments,  which  penetrate  the  muscular  structure  near  the  anterior 
border  of  the  central  tendon,  and  are  distriljuted  to  the  under  surface  of  the 
muscle.  Sympathetic  filaments  are  also  given  to  it  from  the  i)lexuses  which 
accompany  the  phrenic  arteries. 

Action. — To  deepen  the  chest  from  al)ove  downwards,  and  so  produce  a  move- 
ment of  inspiration.  The  central  tendon,  especially  the  middle  part  of  it,  which 
is  closely  connected  by  means  of  the  pericardium  with  the  deej)  fascia  of  the  neck, 
is  l;)ut  little  depressed;    but   the   arched    fleshy  fibres  all   around   flatten,  and   so 


ABDOMIXAL   PARIETKS  AXD   MUSCLES  401 

increase  greatly  the  capacity  of  the  sides  of  the  tlioracic  cavity.  At  the  same  time 
the  abdominal  viscera  are  driven  downwards,  and  as  the  front  part  of  the  parietes 
is  the  most  yielding,  they  are  also  displaced  forwards,  so  as  to  cause  a  greater 
jirominence  of  this  part  of  the  abdomen.  In  the  expulsive  efforts  of  defecation  and 
parturition,  after  the  diaphragm  has  first  contracted  in  a  deep  insjnration,  and 
the  glottis  has  been  closed  so  as  to  prevent  the  escape  of  air  from  the  chest,  the 
a])dominal  muscles  are  able  to  contract  with  full  effect  upon  the  viscera,  which 
have  been  pressed  down  by  the  previous  descent  of  the  diaphragm. 

The  lower  six  ribs  are  slightly  elevated  by  the  diaphragm,  and  the  hypc^chondria 
somewhat  dilated,  this  latter  movement  being  due  to  the  forward  and  outward 
pressure  of  the  depressed  viscera. 

Relations. — Above  lie  the  pleurse  and  pericardium,  the  heart  and  the  lungs. 
Below  are  the  peritoneum,  the  liver  with  its  ligaments,  the  stomach,  the  spleen, 
pancreas,  kidneys,  and  suprarenal  capsules.  The  dome-shaped  upper  convex  sur- 
face rises  higher  upon  the  right  than  the  left  side.  On  the  right  side,  being  raised 
by  the  liver,  it  reaches  to  the  level  of  the  junction  of  the  fifth  costal  cartilage  with 
the  sternum,  and  on  the  left  side  only  to  the  level  of  the  junction  of  the  sixth 
costal  cartilage. 

Variations. — Tlie  oesophageal  opening  has  been  found  in  the  right  eras,  instead  of  being 
surrounded  by  decussating  fibres  from  both  crura.  The  sternal  portion  of  the  muscle  is  not 
unfrequently  absent. 


THE  ABDOJIIXAL  PARIETES 

The  superficial  fascia  covering  the  walls  of  the  aljdomen  is  continuous  with  that 
of  the  thorax  and  lower  limbs,  and  is  usually  divided  into  two  layers. 

The  first  layer  is  w^ell  provided  with  fat,  which  in  many  individuals  attains  to 
a  considerable  thickness,  especially  in  the  lower  part  of  the  anterior  wall. 

The  second  or  deep  layer  (.Scarpa's  fascia)  is  of  a  more  membranous  character 
and  contains  a  quantity  of  elastic  fibres.  Xear  the  groin  it  is  sej^arated  from  the 
more  superficial  layer  by  blood-vessels  and  lymphatic  glands.  Upon  its  deeper 
surface  it  is  loosely  connected  with  the  deep  fascia  which  invests  the  external 
oblique  muscle;  but  it  is  closely  blended  with  the  linea  alba,  the  fibrous  structures 
in  front  of  the  pul)ic  bones,  the  fascia  lata  innnediately  below  Poupart's  ligament, 
and  the  crest  of  the  ilium. 

Both  layers  are  continued  downwards  upon  the  external  genital  organs.  In 
the  male  they  lose  their  fat  and  blend  w4th  the  suspensory  ligament  of  the  penis, 
the  fascia  covering  that  organ,  and  the  dartos  and  septum  of  the  scrotum.  In  the 
female  the}'  are  continuous  with  the  superficial  fascia  of  the  vulva. 


THE  ABDOMINAL  JIUSCLES 

The  muscular  portion  of  the  abdominal  wall  forms  a  lozenge-shaped  figure  of 
which  the  vertical  diagonal  extends  from  the  ensiform  process  to  the  symphysis 
pubis,  while  the  transverse  encircles  the  alxlomen  from  tij)  to  tip  of  the  transverse 
processes  of  the  third  luml)ar  vertebra. 

The  V)oundaries  of  this  muscular  wall  are  formed,  above  by  the  costal  cartilages 
of  the  six  lower  ribs;  behind,  by  the  tips  of  the  transverse  processes  of  the  lumbar 
vertebra' ;  below,  Ijv  the  crests  of  the  ilia  and  the  pubes.  More  accurately,  each 
26 


402  THE  MUSCLES 

lateral  half  may  be  looked  U])on  as  a  four-sided  figure  of  Avhich  the  upper  boundary 
slopes  backwards  and  downwards;  the  lower,  backwards  and  U]iwards;  Avhile  the 
long  anterior  boundary  and  short  posterior  l)oundary  are  vertical  and  parallel. 
The  muscles  contained  in  the  parietes  may  be  divided  into  vertical  and  transverse. 
The  former,  three  in  number,  are  situated  two  in  front,  and  one  behind;  while  the 
latter,  also  three  in  numl»er,  pass  transversely,  or  with  some  oljliquity,  l)etween 
the  anterior  and  jiosterior  1;)oundaries  of  the  space. 

The  two  lateral  halves  unite  in  front  in  a  strong  filirous  Ijand  called  the  linea 
alba,  which  stretches  from  the  tip  of  the  ensiform  cartilage  to  the  upper  part  of 
the  symphysis  pubis.  It  is  partly  formed  by  vertical  fibres  stretching  Ijetween 
these  two  points,  but  chiefly  by  the  interlacement  of  the  transverse  and  oblique 
bands  of  fibrous  tissue  which  pass  between  the  aponeuroses  of  the  muscles  upon 
either  side.  In  its  lower  two-fifths  it  is  not  more  than  one-eighth  of  an  inch 
(3  mm.)  broad;  in  its  upper  three-fifths  it  is  broader,  usually  not  less  than  a 
quarter  of  an  inch  (6  mm. )  in  width,  but  in  some  bodies  it  may  be  stretched  to  a 
much  greater  extent.  At  the  junction  <^f  tlie  loAver  twd-fiftlis  and  upper  three- 
fifths  is  the  small  fibrous  ring  of  the  umbilicus  through  which  pass  the  remnants 
of  the  fcetal  vessels. 

Anterior  Vertical  Muscles 

These  are  two  in  numl)er — the  ])vramidalis  and  rectus  abdominis. 


1.  PYRAMIDALIS 

The  pyramidalis  (fig.  266) — named  somewhat  fancifully  from  its  triangular 
shape — is  a  fan-shaped  sheet  of  muscular  fibre  forming  a  right-angled  triangle,  of 
which  the  shortest  side  corresponds  to  the  origin,  and  the  other  side  containing  the 
right  angle  to  the  linea  alba. 

Origin. — (1)  The  front  of  the  pubic  crest;  and  (2)  the  fil)rous  structures 
which  cover  the  front  of  the  body  of  the  os  pubis  and  its  symphysis. 

Insertion. — The  linea  alba  at  a  point  about  half-way  between  the  pubes  and 
the  umbilicus. 

Structure. — Arising  by  a  short  tendinous  sheet,  the  fleshy  fibres  converge  as 
they  pass  upwards.  Those  nearer  to  the  middle  line  ascend  vertically,  while  those 
which  arise  near  the  pubic  spine  pass  obliquely  U]iwards  and  inwards  to  the 
tendinous  insertion  of  the  muscle  into  the  linea  allia  three  or  four  inches  (8  to  10 
cm. )  above  the  symphysis  pubis. 

Nerve-supply. — From  the  eleventh  and  twelfth  thoracic  nerves  and  from  the 
ilio-hypogastric  branch  of  the  lumbar  plexus,  through  their  terminal  filaments 
which  enter  the  deep  surface  of  the  muscle. 

Action. — By  its  contraction,  it  pulls  upon  the  linea  alba  and  so  upon  the  lower 
end  of  the  ensiform  cartilage.  It  will  therefore  assist  the  rectus  in  flexion  of  the 
thorax  upon  the  pelvis,  or  of  the  pelvis  upon  the  thorax.  It  can  also  help  feel^ly 
to  compress  the  abdominal  viscera. 

Relations. — Su])erficially,  the  aponeuroses  of  the  ^ra».srer.sc' al)dominal  muscles; 
deejily,  the  rectus  abdominis,  from  Avhich  it  is  separated  by  a  thin  fibrous  lamella. 

Variations. — The  height  to  which  this  muscle  extends  is  variable.  It  is  often  absent  on  one 
or  both  sides  ;  or  it  may  be  double. 


2.  RECTUS  ABDOMINIS 

The  rectus  abdominis  (fig.  206) — named  from  its  straight  direction — is  a 
strong  ril>bon-shai)t'(l  muscle  running  vertically  on  either  side  of  the  linea  alba 
from  the  ])ubes  to  the  ensiform  and  adjacent  costal  cartilages. 

Origin. — By  two  tendons:  (1)  the  outer  head  from  the  whole  of  the  crest  of 
the  ])ub(_'s;  (  2)  the  inner  head  crosses  tlu'  niiihllc  lint'  of  the  l)ody,  and  arises  from 
the  filn'ous  structures  lying  in  front  of  the  symphysis. 


RECTUS  ABDOMIMS  403 

Insertion. — (1)  The  anterior  surface  of  the  tip  of  the  fifth  rib;  (2)  the  front 
of  the  costal  cartihiges  of  the  fifth,  sixth,  and  seventh  ril)s;  sometimes  also  (3)  the 
anterior  surface  of  the  base  of  the  ensiform  cartilage  near  its  outer  border. 

Structure. — The  inner  head  arises  tendinous  from  the  other  side  of  the  middle 
line,  decussating  with  its  fellow;  the  outer  and  stronger  head  arises  by  a  shorter 
tendon,  and  is  soon  joined  l)y  the  inner  head.  About  an  inch  (2"5  cm.)  above  the 
l")ubes,  a  fleshy  mass  is  formed,  which  expands  as  it  ascends  into  a  broad  sheet, 
which  l)elow  the  umbilicus  lies  close  to  its  fellow  of  the  opposite  side.  Above,  the 
two  muscles  arc  separated  by  an  interval  of  at  least  a  cparter  of  an  inch  (6  mm.). 
The  insertion,  Avhich  is  by  short  tendinous  fibres,  is  three  or  four  times  the  width 
of  the  origin.  The  muscle  is  also  curved  considerably  forwards  to  correspond  with 
the  convexity  of  the  front  wall  of  the  abdomen.  At  certain  intervals,  transverse 
bands  of  filjrous  tissue  extend  in  an  irregular  zigzag  manner  across  the  muscle, 
especially  upon  its  anterior  surface.  These  are  called  the  lineae  transversse,  and 
the  transverse  depressions  which  they  produce  are  usually  to  be  seen  and  felt 
through  the  skin.  They  are  generally  three  or  four  in  number  on  either  side. 
One  is  situated  opposite  the  umbilicus;  the  second  opposite  the  i\\)  of  the  ensiform 
cartilage;  the  third  half  way  Ijetween  these  points;  and  a  fourth  is  sometimes 
present  which  extends  incompletely  across  the  muscle  at  some  distance  below  the 
uml)ilicus.  They  are  firmly  connected  with  the  anterior  layer  of  the  strong  sheath 
of  the  muscle,  which  will  afterwards  be  described.  They  do  not  extend  through 
the  whole  thickness  of  the  muscle,  being  deficient  behind. 

Nerve-supply. — From  the  terminal  filaments  of  the  anterior  branches  of  the 
six  lower  thoracic  nerves  which  enter  the  muscle  on  its  posterior  surface  near  the 
outer  l)order;  and  from  the  ilio-hypogastric  branch  of  the  lumbar  plexus. 

Action. — (1)  By  the  tendency  of  the  curved  bands  of  the  muscle  to  become 
straight  during  contraction,  all  the  viscera  contained  in  its  concavity  are  compressed. 
It  will,  therefore,  help  in  defecation,  micturition,  and  parturition;  also  in  expira- 
tion, and  especially  in  strong  expiratory  efforts,  such  as  coughing  and  sneezing. 
(2)  By  drawing  down  the  ensiform  cartilage  and  the  anterior  extremities  of  the 
middle  ribs,  it  flexes  the  thorax  upon  the  pelvis,  and  at  the  same  time  acts  as  a 
flexor  of  the  thoracic  and  lumbar  portions  of  the  spine.  Acting  less  strongly,  it 
fixes  the  sternum,  so  that  the  sterno-mastoids  by  their  contraction  may  flex  the 
head,  e.g.  in  rising  from  the  recumbent  position.  (3)  Taking  its  fixed  point 
from  above,  it  will  draw  upwards  the  pul)ic  portion  of  the  pelvis,  and  so  flex  the 
pelvis  upon  the  thorax,  as  when  the  lower  part  of  the  Ijody  is  drawn  up  towards 
the  chest  in  climbing. 

The  linese  transversae,  Avhich  are  the  remnants  of  the  septa  which  divide  the 
muscular  structure  at  intervals  in  the  lower  vertebrates,  and  which  in  the  crocodile 
form  the  abdominal  riljs,  have  had  various  uses  assigned  to  them.  In  the  first 
place,  they  will  tend  to  keep  the  muscular  fibres  in  their  proper  place,  and  prevent 
them  from  being  separated  so  as  to  allow  of  ventral  hernia.  Secondly,  they  will 
enaljle  the  muscle  to  act  not  only  upon  the  points  of  bone  which  form  its  direct 
attachment,  but,  by  means  of  their  connection  with  the  sheath  of  the  muscle  and 
the  aponeuroses  of  which  it  is  formed,  they  will  in  some  measure  dift'use  the  action 
of  the  muscle  over  the  lower  ribs  and  the  crest  of  the  ilium.  Thirdly,  they  will 
ena]»le  one  part  of  the  muscle  to  act  independently,  as  for  example  when  the  lower 
part  exercises  some  pressure  upon  the  bladder  in  micturition.  Fourthly,  they 
prevent  extensive  separation  when  the  muscle  is  injured.  On  account  of  the  severe 
strain  to  which  the  muscle  is  exposed,  it  is  sometimes  ruptured.  If  the  muscular 
fibres  extended  without  interruption  from  the  pubes  to  the  ensiform  cartilage, 
such  a  rupture  would  occasion  a  much  wider  separation,  and  conso(|uently  much 
greater  disablement  than  is  now  found  to  be  the  case. 

Relations. — Superficially,  the  front  layer  of  its  sheath  above,  and  below  the 
pyramidahs;  deeply,  it  is  separated  from  the  transversalis  fascia  and  peritoneum  in 
the  greater  part  of  its  course  by  the  posterior  layer  of  its  sheath;  in  its  lower 
fourth  it  is  in  contact  with  the  transversalis  fascia;  and  above,  it  lies  on  the  carti- 
lages of  the  fifth  to  the  ninth  ribs,  and  covers  the  intercostal  nnisclcs  which  lie 
between  them.  The  deep  epigastric  artery  ascends  behind  tli<'  muscle  to  join  with 
the  superior  epigastric  branch  of  the  internal  mammary. 


404  THE  MUXCLES 

Variations. — Tlie  rectus  maybe  inserted  asliighas  the  i'uurtli  or  even  the  third  rilt.  Ahiteral 
rectus  is  sometimes  found  between  the  t-xternal  and  internal  oblique  muscles,  extending  from  the 
tenth  rib  to  the  iliac  crest. 


Transverse  and  Oblique  Muscles 

This  group  consists  of  three  niiiscles — the  ohliquus  externus,  the  obliquiis  inter- 
niis,  and  the  transversalis — which  lie  iu  successive  strata  in  the  abdominal  wall. 


1.  OBLIQUUS  EXTERNUS 

The  obliquus  externus  abdominis — named  from  its  position  and  direction — 
is  a  broad  curved  sheet,  partly  muscle  and  partly  aponeurosis,  of  an  irregularly 
Cjuadrilateral  shape.  • 

Origin. — The  outer  surface  of  the  eight  lower  ribs  about  their  middle  by  a  series 
of  nearly  horizontal  lines  which,  after  crossing  each  rib  obliquely  downwards  and 
backwards,  extend  for  a  short  distance  along  their  lower  borders. 

Insertion. — (1)  By  a  strong  aponeurosis  along  the  whole  of  the  linea  alba;  (2) 
the  front  of  the  os  pubis  close  to  the  symphysis;  (3)  the  spine  of  the  pubes  and 
the  adjacent  part  of  the  ilio-pectineal  line;  (4)  the  deej?  fascia  of  the  thigh  in  a 
thickened  band  which  stretches  from  the  spine  of  the  pubes  to  the  anterior  superior 
spine  of  the  ilium:  (5)  the  anterior  half  of  the  outer  lip  of  the  crest  of  the  ilium. 

Structure. — At  their  origin  the  muscular  fibres  form  a  series  of  teeth  which 
interdigitate  in  the  upper  part  of  the  muscle  with  the  serratus  magnus,  and  in  the 
lower  with  the  latissimus  dorsi.  The  general  direction  of  the  origin  is  an  oblique 
line  somewhat  curved  upon  itself  so  as  be  convex  upwards  and  backwards.  Above 
and  below,  the  origin  is  nearer  to  the  anterior  extremities  of  the  ribs.  From  this 
origin  the  fleshy  fibres  pass  downwards  and  forwards,  and  at  the  same  time  diverge 
fanwise,  at  first  lying  upon  the  ribs  and  their  cartilages,  and  then  without  any  bony 
support  as  part  of  the  muscular  wall  of  the  abdomen.  The  change  from  fleshy  to 
tendinous  iibres  takes  place  at  some  distance  from  the  outer  border  of  the  rectus 
muscle,  in  such  a  w^ay  that  the  fleshy  mass  terminates  rather  al)ruptly  in  a  right 
angle  situated  in  the  iliac  region  of  the  abdomen.  This  angle  is  fcjrmed  in  front 
by  a  vertical  line,  which  passes  downwards  from  the  tip  of  the  ninth  costal  carti- 
lage; and  below  by  a  horizontal  line  passing  forwards  from  a  point  upon  the  crest 
of  the  ilium  an  inch  or  two  (2 '5  to  5  cm.)  behind  the  anterior  superior  spine. 
This  abrupt  limitation  of  the  muscular  fibres  gives  rise  to  a  projection  wdiich  is 
distinctly  visible  through  the  skin  in  a  muscular  sul)ject.  The  aponeurosis  thus 
formed  blends  in  nearly  the  whole  of  its  extent  with  that  of  the  subjacent  muscle, 
the  obliquus  internus,  and  in  the  middle  line  it  unites  at  the  linea  alba  with  that  of 
the  opposite  side.  Above,  it  extends  U])wards  as  high  as  the  insertion  of  the  rectus 
muscle,  of  which  it  forms  part  of  the  sheath,  and  in  this  locality  it  gives  origin  to 
a  part  of  the  pectoralis  major. 

The  insertion  into  the  pubic  bone  of  the  same  side  is  interrupted  l)y  an  interval 
corresponding  to  the  crest  of  the  pubes,  and  forms  the  external  abdominal  ring. 
From  the  spine  of  the  pubes  to  the  anterior  superior  spine  of  the  ilium,  the 
aponeurosis  forms  a  thickened  band  slightly  convex  downwards,  Avhich  blends  with 
the  fascia  lata,  and  is  called  Poupart's  ligament.  The  rest  of  the  insertion  into 
the  outer  lip  of  tlie  crest  of  the  ilium  is  l)y  short  tendinous  fi])res. 

The  insertion  of  the  lower  edge  of  the  aponeurosis  is  also  carried  backw'ards  and 
outwards  from  the  spine  of  the  pulses  along  the  inner  jiart  of  the  ilio-pectineal  line 
by  a  horizontal  triangle  of  fascia  called  Gimbernat's  ligament.  This  ligament  is 
attached  to  the  lower  end  of  Poupart's  ligament  in  front,  and  it  i)resents  a  concave 
surface  upwards,  U]ion  which  lie  the  structures  Avhich  emerge  through  the  external 
al)dominal  ring.  The  fibres  of  Gimbernat's  ligament  are  continued  upwards  and 
inwards  beyond  the  ilio-pectineal  line  to  the  front  of  the  rectus  and  the  linea  all)a 
by  a  layer  called  the  triangular  fascia,  which  lies  behind  the  inguinal  canal  and 
the  external  abdominal  ring. 


OBLIQ  UCS  EXTERXUS 


40i 


The  external  abdominal  ring  (fig.  285)  is  an  obliquely  directed  plit  or  narrow- 
triangular  aperture  in  the  aponeurosis  of  theobliquus  externus,  which  transmits  the 


Fig.  303. — Extkknal  Oblique  and  Ilio-tibiai.  Baxd. 


Pectoralis  major 


Origin  of  pectoralis 

Major  from  aponeurosis 

of  obliquus  externuB 


Obliquus  externuB 


Linea  semilunaris 


Tensor  vaginae  femoris 


Ilio-tibial  band 


Trapezius 
Serratus  magnus 


Latissimus  dorsi 


Gluteus  maximus 


Tendon  of  biceps 


Spermatic  cord  in  the  male,  and  the  nnnid  ligament  of  the  uterus  in  the  female.     The 
slit  is  formed  Ijv  the  divergence  of  the  obliquely  directed  fibres  of  the  apont'urosis. 


406  THE  MrSCLES 

Those  above,  which  form  the  inner  pillar,  as  it  is  called,  of  the  ring,  run  clown- 
wards  and  inwards  to  be  attached  to  the  front  of  the  symphysis  pubis;  those 
below,  which  form  the  external  pillar  of  the  ring,  form  a  thin  edge  at  first,  but 
thicken  just  before  their  altachnicut  to  the  spine  of  the  pubes  and  the  inner  ex- 
tremity of  the  ilio-pectineal  line,  for  at  this  point  the  external  i)illar  is  identical 
with  Pou})art's  ligament.  Upon  the  surface  of  the  oblicjuus  externus,  close  to  the 
external  al)dominal  ring,  the  obliiiue  lilires  of  tlie  ajtoneurosis  are  fastened  together 
by  some  transversely  directed  fibres,  the  intercolumnar  fibres,  which  run  upwards 
and  inwards  from  Poupart's  ligament,  limiting  and  rounding  off  the  upper  and 
outer  end  of  the  external  abdominal  ring.  A  thin  membrane,  the  intercolumnar 
fascia,  is  prolonged  from  the  edges  of  this  opening  over  the  spermatic  cord  and 
round  ligament,  of  which  it  forms  the  external  envelope. 

Nerve-supply. — From  the  anterior  branches  of  the  lower  thoracic  nerves,  by 
means  of  numerous  filaments  which,  passing  through  the  internal  oblique,  enter 
the  muscle  on  its  deep  surface. 

Action. — (1)  The  curved  muscular  fibres  in  their  contraction  tend  to  become 
straiglit  and  so  compress  the  viscera  which  lie  in  their  concavity;  they  act  in 
defecation,  micturition,  parturition,  and  all  expiratory  efforts;  (2)  the  two  obli(jui 
externi  acting  together  will  draw  upwards  the  front  part  of  the  pelvis,  and  so  fiex 
it  upon  the  thorax;  (3)  the  muscle  of  one  side,  acting  alone  or  in  conjunction  with 
the  internal  oblique  of  the  opposite  side,  Avill  rotate  the  pelvis  and  the  lower  part 
of  the  body  to  the  same  side;  (4)  it  will  tend  by  its  posterior  fibres  to  draw  the 
crest  of  the  ilium  upwards  towards  the  low^er  ribs,  and  will  thus  act  as  a  lateral 
flexor  of  the  pelvis  upon  the  thorax;  (5)  acting  from  below,  the  muscles  of  the  two 
sides  will  draw  the  thorax  downwards  and  forwards  and  flex  the  lumbar  and  lower 
part  of  the  thoracic  spine;  (6)  it  wall  rotate  the  tliorax  upon  the  pelvis  so  as  to 
turn  the  thorax  and  the  upper  part  of  the  body  to  the  ojjposite  side;  (7)  the 
posterior  fibres  wall  flex  the  thorax  laterally. 

Relations. — Superficially,  the  integuments,  and  for  a  short  space  behind  the 
latissimus  dorsi;  deeply,  the  lower  ribs,  tlieir  cartilages,  the  intercostal  muscles 
between  them,  and  the  internal  oblique;  and  below,  the  spermatic  cord  or  round 
ligament  in  the  inguinal  canal. 

Variations. — The  oblique  externus  may  rise  from  more  or  fewer  ribs.  Occasionally  a  deeper 
plane  is  separated  from  the  vest  of  the  muscle.  In  one  case,  the  anterior  part  of  the  aponeurosis 
was  observed  to  be  wanting. 


2.  OBLIQUUS  INTERNUS  ABDOMINIS 

The  obliquus  internus  abdominis  (fig.  266) — named  from  its  relation  to  the 
preceding  muscle  and  the  direction  of  its  fibres — is  an  irregular  cpiadrilateral  curved 
sheet,  partly  fleshy  and  partly  aponeurotic. 

Origin. — (1)  The  outer  half  of  Poupart's  ligament;  (2)  the  anterior  two-thirds 
of  the  space  intervening  between  the  inner  and  outer  li})s  of  the  crest  of  the  ilium; 
(3)  the  outer  and  posterior  aspect  of  the  aponeurosis  of  the  transversalis  abdominis 
(which  aponeurosis  is  also  called  the  lumbar  fascia). 

Insertion. — (1)  For  about  one  inch  (2 "5  cm.)  into  the  inner  extremity  of 
the  ilio-pectineal  line;  (2)  the  anterior  border  of  the  crest  of  the  pubes;  (3)  the 
whole  length  of  the  linea  all>a;  (4)  the  lower  borders  of  the  cartilages  of  the 
last  three  ribs. 

Structure. — Arising  by  fleshy  and  short  tendinous  fibres  intermingled,  a  fleshy 
sheet  is  soon  formed,  the  fibres  of  which  diverge;  the  anterior  passing  forwards 
and  doAvnwards,  the  middle  forwards  and  upwards,  and  the  posterior  directly 
upwards  to  their  insertion,  which  is  by  means  of  a  broad  aponeurosis.  At  the  front 
of  the  lower  intercostal  spaces  the  fibres  run  parallel  to,  and  in  the  same  plane 
with,  the  internal  intercostals.  The  position  of  the  change  from  fleshy  to  apo- 
neurotic fibres  may  be  indicated  by  two  lines  at  right  angles  to  each  other;  one 
passing  upwards  and  a  little  outwards  from  the  middle  of  Poupart's  ligament,  the 
other  horizontally  forwards  below  the  tip  of  the  last  rib,  and  near  the  edges  of  the 
lower  rib  cartilages.     The  aponeurosis  is  blended  with  that  of  the  external  oblique, 


OBLIQUUS  LXTERXCS— ('REMASTER  401 

and  ill  its  upper  three-fourths  it  divides  into  an  anterior  and  a  posterior  Y>lane  wliieh 
together  form  the  sheath  of  the  rectus  muscle.  In  the  lower  fourth  of  the  al)dt)men 
the  wliole  of  the  aponeurosis  passes  in  front  of  this  muscle.  The  line  of  division  of 
the  a])oneurosis  of  the  internal  ol)li(|ue  is  indicated  on  the  surface  of  the  abdomen 
l)y  a  furrow  called  the  linea  semilunaris,  which  lies  between  the  fleshy  part  of  the 
muscle  and  the  outer  border  of  the  rectus  muscle,  and  forms  a  curve,  concave 
inwards,  which  extends  from  the  cartilage  of  the  ninth  rib  alcove  to  the  vicinity  of 
the  i)ubes  below. 

The  plica  semilunaris,  or  fold  of  Douglas,  on  the  other  hand,  is  the  name 
given  to  the  lower  edge  of  the  posterior  sheath  of  the  rectus,  when  that  muscle 
pierces  the  aponeuroses  so  as  to  lie  behind  all  of  them  in  the  lower  fourth  of  its 
course.  The  lowest  portion  of  the  aponeurosis  of  insertion  of  the  ol:)lifjuus  internus 
is  closely  blended  with  that  of  the  transversalis  abdominis,  and  is  called  the  con- 
joined tendon. 

Nerve-supply. — From  the  anterior  primary  branches  of  the  lower  thoracic 
nerves,  and  from  the  first  nerve  of  the  lumbar  plexus  by  means  of  the  ilio-inguinal 
and  ilio-hypogastric  nerves.  The  main  branches  of  these  nerves  run  forwards 
between  this  muscle  and  the  transversalis  abdominis,  and  give  off  their  filaments 
to  the  internal  surface  of  the  muscle;  some  also  are  distributed  to  the  muscle  by 
the  branches  which  perforate  it  in  order  to  supply  the  external  oblique. 

Action. — (1)  The  fil^res  of  the  muscle  being  curved  tend  to  flatten  upon  their 
(Contraction  and  so  to  compress  the  viscera  contained  within  their  concavit}-;  they 
will  therefore  help  in  defecation,  micturition,  parturition,  and  all  expiratory  efforts. 
(2)  It  will  also  assist  expiration  by  drawing  the  lower  ril)s  downwards.  (3)  AMren 
Ijoth  muscles  act  together,  they  flex  the  thorax  upon  the  pelvis.  They  will  also 
flex  the  lumbar  and  lower  thoracic  spine.  (4)  When  the  muscle  of  one  side  acts 
alone,  or  in  conjunction  with  the  obliquus  externus  of  the  other  side,  it  will  rotate 
the  thorax  to  its  own  side.  (5)  The  posterior  fibres  of  the  muscle  will  draw  down 
the  side  of  the  thorax;  it  will  therefore  he  a  lateral  flexor  of  the  thorax  and  of  the 
lumbar  and  lower  dorsal  spine.  (6)  Acting  from  the  thorax,  this  muscle  will  flex 
the  pelvis,  rotate  it  to  the  opposite  side,  and  by  means  of  its  posterior  fibres  it  will 
act  as  a  lateral  flexor  of  the  pelvis. 

Relations. — Superficially,  the  external  oljlique  and  latissimus  dorsi;  deeply, 
the  transversalis  abdominis.  Its  lower  margin  lies  for  a  short  distance  in  front  of 
the  inguinal  canal,  containing  the  spermatic  cord  in  the  male,  and  the  round  liga- 
ment in  the  female.  The  conjoined  tendon  lies  internally  beneath  these  structures. 
The  aponeurosis  of  the  internal  oblique  is  also  in  relation  with  the  rectus  muscle, 
of  which  it  forms  the  sheath  in  the  upper  three-fourths  of  its  extent. 

Variations. — Sometimes  the  muscle  is  crossed  close  to  its  insertion  into  the  ribs  by  teudiuous 
intersections,  which  probably  represent  ribs. 

Cremaster 

The  cremaster  (fig.  285) — named  from  its  action  as  a  suspender  of  the  testicle 
(xpzijLair-yjp  a  suspender,  from  ■/.peij.d-^vuij.i  to  hang) — is  really  a  detached  part  of  the 
obliquus  internus,  forming  M'itli  the  fascia  Avhich  connects  its  fibres  a  thin  loop- 
shaped  band,  which  in  the  male  envelopes  the  lower  part  and  front  of  the  testicle 
and  spermatic  cord.  In  the  female  it  is  either  entirely  al)sent,  or  a  few  filtres  upon 
the  front  of  the  round  ligament  take  its  place. 

Origin. — The  iq)per  and  deep  surface  of  Poupart's  ligament  about  its  middle 
point. 

Insertion. — (1)  Tlie  s]»ino.  and  crest  of  the  ]nibic  bone;  (2)  the  front  of  the 
fascia  propria  or  infundibuliform  fascia,  which  envelopes  the  testicle  ami  sper- 
matic cord. 

Structure. — The  fibres,  which  differ  from  all  other  muscles  in  their  scattered 
and  separate  character,  spring  fleshy  from  the  concavity  of  Poupart's  ligament  on 
the  deep  aspect  of  the  aponeurosis  of  the  obli({uus  externus,  in  continuation  of  the 
origin  of  the  obli(|Uus  internus.  Three  main  divisions  may  be  noted: — (1)  A 
series  of  loops  which  pass  from  this  origin  at  dift'erent  heights  in  front  of  the  cord 


408  THE  MUSCLES 

and  testicle,  with  their  convexities  directed  downwards  and  closely  connected  with 
the  fascia  propria  of  the  testicle;  finally,  they  collect  into  a  narrow  tendinous  band, 
which  is  attached  to  the  spine  and  crest  of  the  pubes.  (2)  A  <,m)up  of  diverirent 
lleshy  fibres,  which  pass  from  the  origin  downwards  and  inwards  to  l)e  lost  ui)on 
the  fascia  propria.  (3)  A  smaller  group,  which  descend  from  the  tendinous  inser- 
tion to  be  lost  in  a  similar  manner  upon  the  front  of  the  fascia  propria. 

Between  these  fleshy  fibres,  Avhich  are  often  thin  and  difiicult  to  recognise, 
there  is  a  layer  of  connective  tissue,  called  the  cremasteric  fascia,  Avhich  unites 
them  and  forms  one  of  the  coverings  of  the  testicle  and  cord. 

Nerve-supply. — The  genital  branch  of  the  genito-ci-ural,  from  the  first  and 
second  lumbar  nerves,  gives  ofif  numerous  filaments  which  enter  the  muscle  upon 
its  deep  and  posterior  aspect. 

Action. — To  raise  the  testicle,  and  draw  it  upwards  towards  the  external 
abdominal  ring.  This  action  is  involuntary,  and  is  usually  of  a  reflex  character, 
being  readily  excited  by  any  irritation  of  the  adjacent  skin  either  of  the  scrotum 
or  thigh. 

Relations. — Superficially,  the  external  oblique  aponeurosis  above,  the  inter- 
colunmar  fascia,  dartos,  and  integuments  below;  deeply,  the  spermatic  cord  and 
testicle  with  its  fascia  propria. 


3.  TRANSVERSALIS  ABDOMINIS 

The  transversalis  abdominis — named  from  the  general  direction  of  its  fibres — 
is  an  irregularly  quadrilateral  curved  sheet,  partly  muscular,  partly  aponeurotic. 

Origin. — (1)  The  inner  surface  of  the  cartilages  of  the  last  six  ribs,  close  to  their 
junction  Avith  the  ribs,  by  teeth  which  interdigitate  with  the  attachments  of  the 
diajthragm;  (2)  the  strong  aponeurosis  called  the  lumbar  fascia,  which  arises  (a) 
Ijv  its  anterior  layer  from  the  front  of  the  transverse  processes  of  the  five  lumljar 
vertebrte,  (b)  by  its  middle  layer  from  the  tips  of  the  transverse  processes  of  the  five 
lumbar  vertebne,  (c)  by  its  posterior  layer  from  the  general  vertebral  aponeurosis 
which  is  attached  to  the  spines  of  the  thoracic,  lumbar,  and  sacral  vertebras  (3)  the 
anterior  two-thirds  of  the  inner  lip  of  the  crest  of  the  ilium;  (4)  the  outer  third 
of  Poupart's  ligament. 

Insertion. — (1)  The  whole  length  of  the  linea  alba;  (2)  the  anterior  border  of 
the  crest  of  the  pubes;  (3)  the  inner  end  of  the  ilio-pectineal  line  for  about  one 
inch  and  a  half  (4  cm.). 

Structure. — Arising  by  short  tendinous  intermixed  with  fleshy  fil)res,  the  muscle 
passes  transversely  forwards,  diverging  slightly  to  its  insertion.  The  change  from 
fleshy  to  aponeurotic  fibres  is  in  a  curved  line,  the  upper  and  lower  extremities  of 
which  approach  the  linea  alba  more  closely  than  in  the  central  part  of  the  muscle. 
In  the  upper  part  the  fleshy  fibres  are  overlapped  in  front  ])v  tlie  rectus  muscle; 
and  at  the  lower  ])order  of  the  muscle  Avhere  it  terminates  in  a  small  arch,  passing 
over  the  spermatic  cord  or  round  ligament,  the  fleshy  fibres  cease  just  above  the 
middle  of  Poupart's  ligament.  The  muscles  of  the  two  sides,  joined  as  they  are  by 
the  central  aponeurosis,  may  be  looked  upon  as  a  single  muscle  with  a  central 
aponeurosis,  like  the  dia]>hragm. 

Inits  upi)erthree-fourtlis  the  anterior  aponeurosis  is  closely  l)lended  with  the 
posterior  division  of  the  a])oneurosis  of  the  internal  ol^lique  muscle,  and  forms  the 
hinder  part  of  the  sheath  of  the  rectus  in  tliis  region.  In  the  lower  fourth,  tlie 
anterior  aponeurosis  is  blended  with  the  undivided  aponeurosis  of  the  internal 
oblique,  and  passes  in  front  of  the  rectus  muscle  and  the  pyramidalis. 

The  posterior  aponeurosis,  or  lumbar  fascia,  consists  of  strong  transverse 
fibres.  The  middle  layer  is  the  strongest,  and  has  in  its  substance  fibrous  bands 
passing  outwards  from  the  tips  of  the  transverse  processes  of  the  lumbar  vertebrae, 
and  continuing  the  series  of  the  ribs  connected  with  the  dorsal  transverse  ])rocesses. 
Between  this  middle  layer  and  the  anterior  layer  Avhich  sjirings  from  the  front  of 
the  tips  of  the  transverse  processes  is  placed  the  (]uadratus  luml)orum;  and  a 
thickening  of  this  anterior  layer  passing  from  the  tips  of  the  transverse  processes 
of  tlie  first  and  second  luml)ar  vertehne  to  the  lowt'st  rib,  called  the  li(f(niu'ii(um 


TRANSVERSALIS  ABDOMINIS 


409 


arcnatum  externum,  gives  origin  to  a  i)ai-t  of  the  (Iia})liragui.  Between  the  middle 
and  posterior  layers  is  placed  the  erector  spinte  muscle.  This  posterior  layer 
hlends  with  the  vertebral  aponeurosis,  and  gives  origin  to  the  latissimus  dorsi,  the 
serratus  posticus  inferior,  and  otlier  muscles. 

Nerve-supply. — The  anterior  primary  branches  of  the  lower  thoracic  nerves 
and  the  ilio-hypogastric  and  ilio-inguinal  branches  of  tlie  first  nerve  of  the  lumbar 
plexus.  The  nerves  as  they  run  forward  between  this  muscle  and  the  obliquus 
internus  distribute  filaments  to  its  outer  surface. 

Action. — The  muscles  of  the  two  sides  with  their  intervening  aponeurosis  form 
a  strong  girth  round  the  a])dominal  viscera,  and  by  their  contraction  compress  most 
powerfully  the  contents  of  the  abdomen. 


Fig.  304. — Tkaxsveksalis  Ahdohixis  and  Sheath  of  Rectus. 


External  intercostal 


Internal  intercostal 


Posterior  portion  of 
sheath  of  rectus 


Transversalis        ^° 
abdominis 


Fold  of  Douglas 


Transversalis  fascia  and 
internal  abdominal  ring 

Conjoined  tendon 

Poupart's  ligament 

Gimberuat's  ligament 


—   Serratus  magnus 


Lumbar  fascia 


It  will  thus  be  seen  that  tlie  three  layers  of  the  transverse  muscle  in  the 
abdominal  wall  cross  one  another  at  various  angles,  one  pair  passing  transversely 
forwards,  a  second  forwards  and  U])wards,  and  a  third  forwards  and  downwards. 
The  following  objects  are  gained  l)y  this  arrangement:  (1)  the  wall  is  rendered 
much  stronger,  and  the  proliability  of  a  hernial  protrusion  of  any  portion  of  the 
viscera  between  the  separated  fibres  of  the  muscles  is  diminished;  (2)  contraction 
of  the  wall  is  permitted  in  every  direction;  (o)  greater  approximation  of  the  mova- 
l)le  boundaries  of  the  abdominal  wall  is*  obtained  by  means  of  the  obliquity  of  the 
muscles  which  effect  this  movement.  For  example,  two  parallel  bones  can  have 
the  distance  between  them  diminished  only  by  one  half,  supposing  that  the  mus- 
cular fibres  producing  this  movement  run  ])er]>endicularly  from  one  lione  to  the  other; 
but  if  the  fibres  cross  one  another  obliquely,  like  those  of  the  external  and  internal 


410  THE  MUSCLES 

ol)li(iue  imiscles,  in  passing  from  the  crest  of  the  ilium  to  the  lower  ribs,  a  much 
more  e(^nii>lete  approximation  of  the  bones  is  effected. 

Relations. — Superiicially,  the  ol)li(|Uus  internus.  the  cartilages  of  the  lower 
ribs,  some  small  vessels,  and  the  lower  intercostal  nerves;  above,  it  is  continuous 
with  the  lower  border  of  the  triangularis  sterni;  below,  it  lies  above  the  spermatic 
cord  or  round  ligament,  and  its  conjoined  tendon  lies  for  a  short  distance  beneath 
these  structures;  deeply,  the  transversalis  fascia  which  separates  it  from  the  peri- 
toneum. 

The  sheath  of  the  rectus  is  formed  by  the  aponeuroses  of  the  three  preceding 
muscles.  That  of  the  obliquus  internus  divides  into  an  anterior  and  posterior 
layer.  The  anterior  layer  l>lcnded  with  the  aponeurosis  of  the  obliquus  externus 
forms  the  front  portion  of  the  sheath.  Above,  it  is  attached  to  the  cartilages  of 
the  fifth,  sixth,  and  seventh  ribs;  and  internally  it  l)lends  with  the  posterior  por- 
tion of  the  sheath  along  the  linea  alba.  The  posterior  portion  of  the  sheath  is 
formed  by  the  posterior  layer  of  the  aponeurosis  of  the  ol^liquus  internus,  which 
is  blended  with  the  aponeurosis  of  the  transversalis.  Above,  it  is  attached  to  the 
lower  edge  of  the  cartilages  of  the  seventh  and  eighth  ribs,  and  to  the  ensiform 
cartilage.  Internally  it  blends  with  the  front  portion  of  the  sheath  along  the 
linea  alba.  Rather  nearer  the  umbilicus  than  the  pubes,  the  posterior  portion  of 
the  sheath  becomes  suddenly  much  thinner  and  weaker  at  the  fold  of  Douglas, 
Avhich  is  a  transverse  line  indicating  that  the  filn'es  of  the  abdominal  aponeuroses 
which  have  down  to  this  level  formed  the  posterior  portion  of  the  sheath,  now  pass 
to  its  front  wall.  Below  this  level  the  posterior  portion  of  the  sheath  is  formed 
by  a  thickening  of  the  transversalis  fascia  (page  411). 


POSTERIOR  VERTICAL  MUSCLE— QUADRATUS  LUMBORUM 

The  quadratus  lumborum  (fig.  286) — named  from  its  approximately  square 
shape  and  its  position  in  the  region  of  the  loins — is  a  thick  quadrilateral  sheet. 

Origin. — (1)  About  two  inches  (5  cm.)  of  the  inner  lip  of  the  crest  of  the 
ilium  at  the  junction  of  its  middle  and  posterior  thirds;  (2)  the  ilio-lumbar  liga- 
ment; (3)  the  tips  of  the  transverse  processes  of  the  three  or  four  lower  lumbar 
vertebra?. 

Insertion. — (1)  The  inner  half  of  the  lower  border  of  the  last  rib;  (2)  the 
tips  of  the  transverse  processes  of  the  upper  three  or  four  lumbar  verteljrse;  and 
(3)  the  fibrous  continuations  which  pass  out  from  these  transverse  processes  in  the 
substance  of  the  middle  portion  of  the  lumbar  fascia,  and  which  represent  the 
abdominal  ribs. 

Structure. — This  muscle  varies  considerably  in  its  structure  and  arrangement, 
the  origins  from,  and  insertions  into  the  transverse  processes  differing  much  in 
different  subjects.  Its  origin  is  usually  by  short  tendinous  intermixed  with  fleshy 
fibres,  and  extends  at  its  lower  part  all  along  the  ilio-lumbar  ligament,  and  behind 
the  attachment  of  this  ligament  from  the  inner  lip  of  the  crest  of  the  ilium.  The 
fibres  converge  somewhat  as  they  ascend;  the  outermost,  passing  upwards  and 
inwards  to  the  middle  point  of  the  lower  border  of  the  last  rib,  while  the  inner 
fibres  pass  vertically  upwards  along  the  tips  of  the  transverse  processes  of  the 
lumbar  vertebrae,  from  which  they  receive  short  tendons,  and  they  sometimes  give 
tendinous  slips  to  these  processes.  On  the  anterior  and  posterior  surfaces  of  the 
muscle  are  often  seen  ascending  fibres  from  the  transverse  processes,  which  diverge 
slightly  l)efoi-e  they  are  inserted  into  the  lower  border  of  the  last  rib. 

Nerve-supply. — From  the  twelfth  thoracic  and  upper  lumbar  nerves,  by  fila- 
ments which  enter  the  muscle  upon  its  anterior  surface  near  its  inner  border. 

Action. — (1)  It  will  draw  downwards  the  last  rib,  and  will  therefore  act  as  a 
lateral  flexor  of  the  thorax  as  well  as  of  the  loAver  thoracic  and  the  lumbar  spine; 
(2)  it  will  assist  in  expiration  by  drawing* down  the  last  rib;  (3)  taking  its  fixed 
point  from  the  last  ril),  it  will  draAv  upwards  the  crest  of  the  ilium,  and  so  act  as 
a  lateral  flexor  of  the  pelvis  upon  the  thorax. 

Relations. — In  front  lie  the  kidney,  the  colon,  the  psoas,  the  lumbar  arteries 
and  nerves,  separated  from  it  by  the  anterior  layer  of  the  luml)ar  fascia.     Behind, 


SERRATUS  POSTICUS  SUPERIOR  411 

the  middle  layer  of  the  lumljar  fascia  separates  it  from  the  erector  spinse,  and  along 
its  inner  border  are  placed  the  intertransversales. 

The  transversalis  fascia,  -which  lines  the  interior  of  the  muscular  portion  of  the 
abdominal  parietes,  is  a  thin  layer  of  connective  tissue.  It  is  best  marked  in  the 
lower  jDart  of  the  front  of  the  aV^domen,  where  some  of  the  muscular  and  aponeurotic 
layers  are  deficient.  Below,  it  is  attached  to  the  inner  border  of  the  whole  length 
of  the  crest  of  the  ilium,  and  to  the  outer  half  of  Poupart's  ligament,  where  it 
blends  with  the  iliac  fascia  covering  the  iliacus  muscle.  Beneath  the  inner  half  of 
Poupart's  ligament  it  is  somewhat  thickened,  and  called  the  deep  crural  arch. 
This  is  but  loosely  attached  to  Poupart's  ligament,  and  the  fascia  is  continued  into 
the  thigh,  where  it  forms  the  front  of  the  sheath  of  the  femoral  vessels.  Internally 
to  this,  it  is  attached  to  the  free  margin  of  Gimbernat's  ligament,  and  the  inner  end  of 
the  ilio-pectineal  line.  Further  inwards  it  is  inserted  along  the  ])osterior  border  of  the 
crest  of  the  pubes.  At  the  back  of  the  linea  alba  it  is  continuous  with  the  fascia 
of  the  opposite  side.  Behind  the  lower  part  of  the  rectus  muscle  it  is  thickened, 
and  takes  the  place  of  the  posterior  portion  of  the  sheath  from  the  pubes  to  the 
fold  of  Douglas.  Above,  it  becomes  thin  and  blends  with  the  fascia  covering  the 
under  surface  of  the  diaphragm;  and  behind,  it  is  lost  in  the  loose  fat  which  covers 
the  posterior  surface  of  the  kidneys,  together  with  the  back  of  the  ascending  and 
descending  colon. 

About  half  an  inch  (1"2  cm.)  above  Poupart's  ligament,  half  way  between  the 
anterior  superior  spine  and  the  symphysis  pubis,  it  is  perforated  by  the  spermatic 
cord  in  the  male,  and  the  round  ligament  in  the  female.  To  the  margins  of  the 
opening,  which  is  called  the  internal  abdominal  ring,  is  attached  a  tubular  pro- 
longation, the  infundibuliform  fascia,  which  invests  the  cord  or  round  ligament. 
The  connection  of  this  tube  to  the  rest  of  the  fascia  may  be  compared  to  the  attach- 
ment of  the  sleeve  to  a  coat.  No  opening  is  therefore  visible  from  the  exterior 
until  the  sleeve-like  tube  has  been  divided. 


MUSCLES  OF  THE  BACK 


The  first  and  second  layers  have  already  been  described,  as  they  belong  to  the 
groups  of  muscles  which  pass  from  the  thorax  to  the  bones  of  the  upper  extremity. 
The  third  layer  consists  of  muscles  which  stretch  in  a  nearly  transverse  direction 
from  the  spinous  processes  of  the  vertebrae  to  the  back  of  the  ribs,  viz.  the  serratus 
posticus  superior  and  the  serratus  posticus  inferior. 


Third   Layer 

1.  SEPvRATUS   POSTICUS  SUPEPvIOR 

The  serratus  posticus  superior — named  from  its  saw-like  edge  and  its  relation 
to  the  other  serrati — is  a  cpiadrilateral  sheet  with  a  toothed  outer  margin. 

Origin. —  (1)  The  outer  surface  of  the  lower  part  of  the  ligamentum  nuchfe 
near  its  posterior  edge;  (2)  the  spines  of  the  last  cervical  and  first  two  thoracic 
vertebne.  and  the  supraspinous  ligament  connecting  them. 

Insertion. — The  upper  borders  and  outer  surfaces  of  the  second  to  the  fifth  ribs, 
external  to  their  angles. 

Structure. — The  inner  half  is  a  tendinous  sheet,  the  fibres  of  which  run  down- 
wards and  outwards,  and  when  they  have  passed  beyond  the  line  of  the  transverse 
processes  they  become  fleshy  and  are  inserted  into  the  ribs  by  the  lower  borders  of 
the  four  teeth  into  which  the  muscle  divides. 


412 


THE  MUSCLES 


Nerve-supply. — From   the  second    and   third    intercostals   by  fine  filaments 
which  enter  the  outer  part  of  its  deep  surface. 


Fig.  305.— The  Third  and  Foueth  Layers  of  the  Mi'scles  of  the  Back. 


Complexus 


Splenius  capitis 


Splemus  colli 


Ssrratus  post'Cus  superior 


Vertebral  aponeurosis 


Serratus  posticus 
inferior 


Obliquus  internus 


Origin  of  latissimus 
dorsi 


SEVENTH  CERVICAL  VERTEBRA 


TWELFTH  THORACIC  VERTEBRA 


FIFTH  LUMBAR  VERTEBRA 


Action. — To  raise  the  ribs  into  Avhich  it  is  inserted;  and  tlierefore  to  assist  in 
inspiration. 


SERRATUS  POSTICUS  IXFERIOR— VERTEBRAL  APONEUROSIS  413. 

Relations. — Superficially,  the  tra])ezius,  levator  aiiiruli  scapulte,  rhoiiiljoideus 
minor  and  major;  deeply,  the  vertel)ral  aponeurosis  which  separates  it  from  the 
splenius  and  the  more  superficial  spinal  muscles;  farther  outwards  the  muscle 
covers  part  of  the  external  intercostals. 

Variations. — The  .'^lips  vary  in  number.  Sometimes  it  gives  oflF  a  slip  from  its  upper  border 
or  posterior  surface  which  goes  to  the  levator  anguli  scapulae,  the  mastoid  process,  or  the  superior 
nuchal  line. 

2.  SERRATUS   POSTICUS   IXFERIOR 

The  serratus  posticus  inferior — named  also  from  its  outer  saw-like  margin, 
and  its  position — is  a  quadrilateral  sheet. 

Origin. — The  spines  of  the  two  lower  thoracic  and  two  upper  lumbar  vertebrae. 

Insertion. — The  lower  borders  of  the  last  four  or  five  ribs  external  to  their 
anirlfs,  except  in  the  case  of  the  last  rib  which  has  no  angle;  and  as  far  forwards 
as  tliL'  costal  origins  of  the  latissimus  dorsi. 

Structure. — More  than  half  of  the  muscle  is  aponeurosis,  which  is  blended  with 
that  of  the  latissimus  dorsi  on  its  superficial,  and  of  the  erector  spinse  on  its  deep 
aspect,  and  forms  a  part  of  the  vertebral  aponeurosis,  Avhich  blends  with  the  pos- 
terior layer  of  the  lumbar  fascia.  The  fleshy  fibres  are  directed  upwards  and  out- 
wards from  this  ajDoneurosis,  arising  in  an  oblic|ue  line  which  is  nearer  the  spine 
above  than  below,  and  inserted  directly,  or  with  small  tendinous  attachments  into 
the  ribs.  Each  succeeding  tooth  slightly  overlaps,  and  extends  farther  forwards 
than  the  one  below.     The  middle  teeth  are  the  largest. 

Nerve-supply. — Filaments  from  the  tenth  and  eleventh  intercostals  which 
enter  the  deep  surface  of  the  outer  part  of  the  muscle. 

Action. — (1)  To  depress  the  lower  ribs;  (2)  to  fix  them,  so  as  to  enable  the 
diaphragm  to  contract.      It  is  therefore  in  this  respect  a  muscle  of  inspiration. 

Relations. — Superficially,  the  latissimus  dorsi;  deeply,  the  erector  spinse  with 
its  upward  continuations,  also  the  levatores  costarum,  and  the  external  intercostal 
muscles. 


GENERAL   ARRANGEMENT   OF   THE   MUSCLES 
ACTING   UPON   THE   SPINAL   COLU:\IN 

THE  VERTEBRAL  APONEUROSIS 

Beneath  the  serrati  postici  are  arranged  what  may  be  called  the  muscles  of  the 
back  projjer,  viz.  those  which  move  the  vertebral  column  and  act  chiefly  upon  the 
spines  and  transverse  processes  of  the  vertebrae  and  the  parts  of  the  skull  which 
are  serially  continuous  with  them.  The}'  lie  for  the  most  part  in  the  groove  on 
either  side  of  the  spines  of  the  vertebrae,  and  they  are  bovuid  down  and  protected 
by  the  strong  vertebral  aponeurosis  which  is  blended  below  with  the  tendinous 
origin  of  the  latissimus  dorsi,  the  serratus  posticus  inferior,  and  the  erector  spinae. 
Laterally,  it  is  attached  to  the  angles  of  the  ribs;  and  internally,  to  the  spines  of  the 
vertebrae  and  the  supra-spinous  ligament.  Above,  it  passes  beneath  the  tendon  of 
the  serratus  posticus  superior,  and  is  then  lost  in  the  thin  fascia  covering  the  splenii. 

The  back  muscles  proper  may  l)e  arranged  according  to  their  direction  into 
two  great  divisions,  each  of  Avhich  contains  two  classes.  The  vertical  division 
consists  of  muscles  which  run  between  similar  points  of  bone,  and  its  two  classes 
will  contain  the  spinales,  which  connect  the  spines  of  the  verteliraj  with  one  another 
and  with  the  mesial  portion  of  the  occipital  bone;  the  transrcrsales,  which  connect 
the  transverse  processes  of  the  sacral  and  lumbar  regions  with  the  transverse  pro- 
cesses and  the  adjacent  portions  of  the  ribs  in  the  thoracic  region,  the  articular  and 
transverse  processes  in  the  cervical  region,  and  the  mastoid  process  at  the  upi>er 
end  of  the  spinal  column.  The  oblique  division  consists  of  muscles  which  run 
obliquely,  and  contains  two  classes:  the  ■•<pino-tran.-<rersnIes,  which  run  upwards  and 
outwards  from  spine  to  transverse  process,  or  to  a  point  of  bone  which  corresponds 


414  THE  MUSCLES 

to  a  transverse  process,  e.g.  the  mastoid  process;  and  the  transverso-spi nales.  wliich 
run  upwards  and  inwards  from  transverse  process  to  spine. 

The  action  of  these  muscles  will  be  easily  ascertained  by  observing  to  which  class 
they  belong.  The  spinales  will  simply  extend,  while  the  transrerscdes  will  produce 
lateral  flexion  as  well  as  extension.  The  oblique,  in  addition  to  extension  and 
lateral  flexion,  will  also  produce  rotation  wherever  the  ligaments  and  processes  of 
the  vertebrae  permit  of  this  movement. 


Fourth  Layer 

The  fourth  layer  of  the  muscles  of  the  back  consists  of  two  muscles,  Avhich  are 
closely  connected  with  each  other,  and  belong  to  the  spino-transversalis  class  of  the 
oblique  division. 

1  AND  2.   SPLENIUS 

The  splenius  (fig.  305) — named  from  a-Ay^tov  a  bandage  or  compress,  probably 
on  account  of  the  way  in  which  it  crosses  over  and  l)inds  down  the  complexus  and 
other  muscles — is  a  broad  four-sided  sheet,  divided  into  two  parts  at  its  insertion: 
the  one  part  being  the  splenius  capitis,  and  the  other  the  splenius  colli. 

(1)  Splenius  Capitis 

Origin. — (1)  The  lower  two-thirds  of  the  ligamentum  nuchae;  (2)  the  spines  of 
the  seventh  cervical  and  upper  two  thoracic  vertebra?,  and  the  interspinous  liga- 
ments between  them. 

Insertion. — The  outer  third  of  the  middle  nuchal  line  of  the  occipital  bone, 
and  the  back  part  of  the  outer  surface  of  the  mastoid  process  of  the  temjjoral 
bone. 

Structure. — Arising  Ijy  a  short  tendinous  aponeurosis,  the  fleshy  fibres  pass 
upAvards  and  outwards  parallel  to  each  other,  and  are  inserted  by  short  tendinous 
fibres,  except  along  the  anterior  border,  where  the  tendon  of  insertion  extends  more 
than  an  inch  (2-5  cm.)  downwards. 

Nerve-supply. — The  external  branches  of  the  posterior  primary  divisions  of 
the  middle  cervical  nerves  which  enter  the  outer  part  of  the  deep  surface  of  the 
muscle. 

Action. — (1)  To  extend  the  head  and  neck;  (2)  to  flex  them  laterally;  (3)  to 
rotate  the  face  to  the  same  side. 

(2)  Splenius  Colli 

Origin. — The  spines  of  the  third  to  the  sixth  thoracic  vertebrae,  and  the  inter- 
spinous ligaments  between  them. 

Insertion. — The  back  of  the  posterior  tul^ercles  of  the  transverse  processes  of 
three  or  four  upper  cervical  vertebrae. 

Structure. — Of  parallel  fleshy  fibres  witli  a  short  aponeurotic  origin,  and 
inserted  liy  small  tendons,  the  highest  of  which  is  the  largest. 

Nerve-supply. — The  external  branches  of  the  i)osterior  divisions  of  the  loAvcr 
cervical  nerves. 

Action. —  ( 1)  To  extend  the  upper  ])art  of  the  neck;  (2)  to  flex  it  laterally; 
(3)  to  rotate  it  to  llic  same  side. 

Relations  of  the  splenius. — Superficially,  the  sterno-mastoid,  trajiezius.  ser- 
ratus  posticus  superior,  and  the  levator  anguli  scapula?  which  conceals  the  splenius 
colli  in  the  posterior  triangle  of  the  neck.  Beneath  lie  the  complexus,  trachelo- 
mastoid,  cervicalis  ascendens,  and  transversalis  colli. 

Variations. — The  number  of  the  thoracic  vertebrre  from  which  the  splenii  arise  varies.  The 
splenius  colli  may  be  absent.  The  slip  mentioned  in  the  variations  of  the  serratus  posticus 
superior  may  be  considered  to  be  a  variation  of  the  splenii. 


ERECTOR  SPIX.E—ILIO-COSTALIS  415 


FiFrii  Layer 

The  fifth  layer  consists  of  vertical  muscles,  and  contains  both  spinales  and 
transversalns.  To  the  hitter  ckiss  Ijelong  the  greater  part  of  the  erector  spina^  and 
the  seven  muscles  which  either  spring  from  it  or  are  serially  continuous  with  it: 
viz.  the  ilio-costalis,  accessorius  ad  ilio-costalem,  cervicalis  ascendens,  longissimus 
dorsi,  transversalis  colli,  trachelo-mastoid,  and  the  spinalis  dorsi. 


1.  ERECTOR  SPIN.E 

The  erector  spinae — named  from  its  function — is  a  broad  and  very  strong 
membranous  sheet  of  a  triangular  shape,  with  a  layer  of  fleshy  fibres  upon  its 
deep  surface,  and  it  divides  in  the  lumbar  region  into  three  longitudinal  series  of 
muscles  which  fill  the  greater  part  of  the  vertel:)ral  groove. 

Origin. —  (1)  The  spines  of  the  two  last  thoracic,  all  the  lumbar,  and  the  four 
upper  sacral  vertebrae;  (2)  the  back  of  the  side  portion  of  the  fourth  sacral  ver- 
teljra;  (3)  the  posterior  sacro-iliac  ligament,  a  few  of  these  fibres  being  continuous 
with  the  origin  of  the  gluteus  maximus;  (4)'  the  upper  part  of  the  posterior  supe- 
rior spine  of  the  ilium,  and  the  posterior  fifth  of  the  iliac  crest. 

Insertion. — It  is  continuous  with  the  spinalis  dorsi.  longissimus  dorsi,  and 
ilio-CDstalis. 

Structure. — A  strong  membranous  sheet,  everywhere  continuous  except  at  the 
origin  from  the  lower  thoracic  and  upper  lumbar  spines,  where  it  is  partly  divided 
into  separate  tendons. 

It  breaks  up  into  fleshy  fibres  in  a  line  which  stretches  obliquely  upwards  and 
inwards  from  the  front  of  the  iliac  origin  to  the  last  thoracic  spines.  Fleshy  fibres 
also  arise  upon  its  deeper  surface  at  a  lower  level,  and  some  arise  directly  from 
the  posterior  superior  iliac  spine  and  the  crest  under  cover  of  the  tendinous 
origin. 

Nerve-supply. — The  external  l)ranches  of  the  posterior  divisions  of  the  lumbar 
nerves  which  enter  its  deep  surface. 

Action. — Generally,  that  of  extension  of  the  lumbar  spine  on  the  pelvis;  but  a 
full  account  will  be  given  with  the  description  of  the  succeeding  muscles. 

Relations. — Superficially,  the  vertebral  aponeurosis,  Avith  which  it  is  blended 
at  its  origin  and  for  the  first  two  inches  (5  cm.)  of  its  course.  By  this  aponeurosis 
it  therefore  enters  into  a  close  relation  with  the  lower  part  of  the  tendons  of  the 
latissimus  dorsi  and  serratus  posticus  inferior.  Deeply,  the  nmltifidus  spinae, 
some  of  the  fibres  of  which  arise  from  it. 

The  outer  division  extends  upwards  along  the  angles  of  the  ribs  and  the  trans- 
verse processes  of  the  lower  cervical  vertebrae,  and  consists  of  the  ilio-costalis. 
accessorius  ad  ilio-costalem,  and  the  cervicalis  ascendens.  It  is  separated  from 
the  middle  division  by  the  external  branches  of  the  posterior  divisions  of  the  sj^innl 
nerves. 

Outer  Division 

2.  ILIO-COSTALIS 

The  ilio-costalis,  or  sacro-lumbalis — named  from  its  attachment  to  the  ilium 
and  ribs — is  an  elongated  muscular  sheet,  with  a  serrated  outer  border  formed  Ijy 
the  insertion  of  its  tendons  into  the  lower  rilxs. 

Origin. — The  outer  portion  of  the  erector  spinse. 

Insertion. — (1)  The  angles  of  all  the  ribs  from  the  sixth  to  the  eleventh; 
(2)  the  lower  border  of  the  last  rib;  (3)  the  tips  of  the  transverse  processes  of 
the  lumbar  vertebrae,  and  the  fibrous  processes  which  extend  outwards  from 
the  tips  of  the  transverse  processes  of  the  upper  lumbar  vertebrae  into  the 
lumbar  fascia. 


416 


THE  MUSCLES 


Fig.  306.— The  Fifth  Layer  of  the  Muscles  of  the  Back. 


Complexus 
Trachelo-mastoid 


TrauBversalis  colli 


Cervicalis  aseendens 


Longissimus  dorsi 


Aceessorius  ad  ilio- 
costalem 


Spinalis  dorsi 


Ilio-costalis 


Obliquus  internus 


Ei-eetor  spinas 


SEVENTH  CERVICAL  VERTEBRA 


_   TWELFTH  THORACIC  VERTEBRA 


FIFTH  LUMBAR  VERTEBRA 


3.  ACCESSORIUS  AD  ILIO-COSTALEM 

The  aceessorius  ad  ilio-eostalem  or  ad  saero-lumbalem — named  from  its 
beinp;  an  acccssorv  or  addition  to  tlie  ilio-costalis — is  a  narrow  niiisculo-tendinous 
l)aiid  with  a  serrated  niaruin  on  either  side. 


CERVICALIS  ASCENDENS—LOXGISSLMUS  DORSI  417 

Origin. — The  ui)per  borders  of  the  angles  of  the  seventh  to  the  eleventh  ribs 
and  tlie  l)ack  of  the  last  rib. 

Insertion. — The  back  of  the  transverse  process  of  the  seventh  cervical  vertel^ra, 
the  lirst  rib  just  external  to  its  tubercle,  and  the  angles  of  the  second  to  the  fifth 
ribs. 

4.  CERVICALIS  ASCENDENS 

The  cervicalis  ascendens — named  from  its  position  in  the  neck  and  its 
direction — is  a  still  thinner  musculo-tendinous  band  with  serrated  margins. 

Origin. — The  back  of  the  four  or  five  ujiper  ril:)s  just  internal  to  the  insertion 
of  the  preceding  muscle. 

Insertion. — The  back  of  the  transverse  processes  of  the  fourth,  fifth,  and  sixth 
cervical  vertel)rie. 

Structure. — These  three  sections  form  a  compound  muscle,  composed  for  the 
most  jjart  of  fusiform  bellies  with  tendinous  origins  and  insertions,  placed  in  series 
so  that  the  origins  of  the  higher  slips  are  on  a  level  with  the  insertions  of  those  that 
arise  six  or  seven  vertebras  or  ribs  lower  down.  The  lowest  of  the  series  arise 
directly  from  the  muscular  mass  of  the  erector  spinse;  and  the  insertions  of  these 
lower  slips,  especially  those  into  the  lumbar  fascia  and  last  rib,  are  fleshy.  A  part 
of  the  tendinous  origin  of  the  slips  of  muscle  is  so  closely  blended  that  a  complete 
separation  of  the  muscle  into  its  component  parts  is  impossible.  There  is  a 
gradual  diminution  of  the  size  of  each  component  muscle  and  its  tendons  as  we 
trace  the  compound  mass  upwards. 

Nerve-supply. — The  external  branches  of  the  posterior  divisions  of  the  spinal 
nerves  from  the  lower  cervical  nerves  to  the  last  thoracic. 

Action. — (1)  To  extend  the  vertebral  column,  in  the  lower  cervical,  thoracic, 
and  upper  lumbar  regions;  (2)  to  flex  it  laterally  in  these  regions;  (3)  to  depress 
the  ril)s,  and  so  help  in  expiration. 

Relations. — Superficially,  the  trapezius,  rhomboidei,  latissimus  dorsi,  the  ser- 
ratus  posticus  superior  and  inferior,  and  the  two  splenii;  deeph^,  the  intercostal 
muscles  and  the  levatores  costarum;  internally,  the  muscles  of  the  middle  division, 
and  the  external  divisions  of  the  posterior  spinal  nerves. 


Middle   Division 

The  middle  division  extends  along  the  liack  of  the  transverse  processes  of 
the  lumbar  and  thoracic  vertebrae,  the  articular  processes,  and  adjacent  i)art  of 
the  transverse  processes  of  the  cervical  vertebrae,  and  ends  at  the  mastoid  pro- 
cess of  the  temporal  bone.  It  consists  of  the  longissimus  dorsi,  transver- 
salis  colli,  and  trachclo-mastoid. 


5.  LONGISSIMUS  DORSI 

The  longissimus  dorsi — named  from  its  great  length  and  its  position  in  the 
dorsal  regi(jn — is  a  compound  muscle  forming  a  long  band,  with  its  surfaces  directed 
outwards  and  inwards,  and  an  anterior  margin  provided  with  an  outer  and  inner 
row  of  teeth  by  which  it  is  inserted. 

Origin. — (1)  The  middle  part  of  the  erector  spina*;  and  (2)  tlie  transverse 
processes  of  some  of  the  lower  thoracic  verteljrje. 

Insertion. — Externally:  (1)  the  lower  l)order  of  the  back  of  the  transverse 
processes  of  the  upper  lumbar  vertebrte;  (2)  the  lower  border  of  the  ribs  just  exter- 
nal to  their  tubercles.  Internally:  (1)  The  accessory  tubercles  of  the  ui)i)er 
lumbar  and  lower  thoracic  vertel)rie;  and  (2)  the  back  of  the  transverse  processes 
of  the  rest  of  the  thoracic  vertebrae. 
27 


418  THE  MUSCLES 

Fig    307  -The  Fifth  Layer  of  the  Muscles  of  the  Back,  after  sepakatixg  the 
Outer  and  Middle  Divisions. 


ObliquuB  superior 

Rectus  capitis  posticus  major 

Obliquus  inferior 

Trachelo-mastoid 

Transversalis  colli 
Cerviealis  aseendens 


Accessorius  ad  ilio- 
eostalem 


Ilio-coBtalis 


Insertion  of  ilio-costalis 
upon  lumbar  transverse 
processes 


Rectus  capitis  posticus  minor 


SEVENTH  CERVICAL  VERTEBRA 


Longissimus  dorsi 


TWELFTH  THORACIC  VERTEBRA 


FIFTH  LUMBAR  VERTEBRA 


Erector  spinas 


6.  TRANSVERSALIS  COLLI 
The  transversalis   colli— named  from  its  attachment  to  the  transverse^  pro- 


cesses and  its  hisertion  m 
band. 


the  neck— is  a  similar  but  narroAver  musculo-tendinous 


TRACHELO-MASTOID— SPINALIS  DORSI  419 

Origin. — The  back  of  the  transverse  processes  of  tlie  five  or  six  upper  thoracic 
vertehra'.  internal  to  the  insertion  of  tlie  jjreceding  nuiscle. 

Insertion. — The  posterior  tubercles  of  the  transverse  processes  of  the  second 
to  the  sixth  cervical  vertebrtX3. 


7.  TRACHELO-MASTOID 

The  trachelo-mastoid — named  from  its  origin,  part  of  which  is  in  the  neck 
(zpd/rjAoq)^  and  its  insertion  ujjon  the  mastoid  process — is  a  similar  but  smaller 
inusculo-tendinous  band. 

Origin, — (1)  The  back  of  the  articular  processes  of  the  lower  three  or  four 
cervical  verte])ra3;  (2)  the  back  of  the  transverse  jsrocesses  of  the  four  or  five  upper 
thoracic  vertelira?. 

Insertion. — The  posterior  l)order  of  the  mastoid  process. 

Structure  of  the  middle  division. — The  three  parts  of  this  division  have  a 
close  connection  with  one  another,  and  a  long  tendinous  expansion  wliich  covers 
the  inner  and  back  part  of  the  longissimus  clorsi,  is  common  to  it  and  the  spinalis 
dorsi. 

The  association  of  the  two  upper  portions  of  the  division  is  so  close  that  they 
are  sometimes  described  together  under  the  name  transversalis,  the  trachelo-mastoid 
being  called  the  transversalis  capitis  to  distinguish  it  from  that  part  of  the  muscle 
which  is  inserted  into  the  neck.  All  the  upper  Elements  of  this  long  compound 
muscle  have  tendinous  origins  and  insertions. 

The  trachelo-mastoid  portion  is  often  found  to  have  a  tendinous  intersection 
crossing  its  fleshy  fibres. 

Nerve-supply. — The  external  division  of  the  jiosterior  branches  of  the  lower 
cervical,  all  the  thoracic,  and  the  upper  lumbar  ner\'es. 

Action. — (1)  To  extend  the  cervical,  thoracic,  and  lumbar  spine;  (2)  to  flex  it 
laterally;  (3)  to  extend  and  laterally  flex  the  head,  rotating  the  face  to  the  same 
side. 

Relations. — Superficially,  it  is  covered  by  the  latissimus  dorsi,  trapezius,  rhom- 
boidei,  serratus  posticus  inferior  and  superior,  and  the  two  splenii;  upon  its  inner 
border  lie  the  spinalis  dorsi  and  complexus.  Upon  its  outer  lie  the  muscles  of  the 
outer  division  and  the  external  divisions  of  the  posterior  branches  of  the  spinal 
nerves.     Beneath  lie  the  multifidus  spinas  and  the  semispinales  dorsi  et  colli. 


Inner   Division 

The  inner  division  consists  usually  of  a  single  muscle,  the  spinalis  dorsi;  but 
sometimes  a  small  muscle,  the  spinalis  colli,  continues  the  series  into  the  neck. 


8.  SPINALIS  DOPxSI 

The  spinalis  dorsi — named  from  its  attachment  to  the  spines  in  the  dorsal 
region — is  a  musculo-tendinous  band  closely  connected  below  with  the  aponeurosis 
on  the  back  of  the  longissimus  dorsi. 

Origin. — The  erector  spinse,  and  esjiecially  that  ])art  which  is  attached  to  the 
two  or  three  lower  thoracic  and  the  upper  lumbar  spines. 

Insertion. — The  spines  of  the  upper  thoracic  vertebra^. 

Structure. — L"i)on  its  i)osterior  surface  it  is  covered  l)y  a  thick  ai)oneurosis, 
from  the  upper  edge  and  anterior  surface  of  which  fleshy  fil:)res  i)ass  almost  directly 
upwards,  and  are  then  inserted  by  means  of  four  to  eight  tendons  into  as  many  of 
the  upper  thoracic  spines.  They  are  closely  blended  with  the  tendons  of  the  semi- 
spinalis  dorsi  at  their  insertion. 

Nerve-supply. — The  posterior  branches  of  the  thoracic  nerves. 

Action.— To  extend  the  thoracic  spine. 


420  THE  MUSCLES 

Relations. — Supcrticially,  the  two  serrati  postici,  the  latissimus  dorsi,  the 
rhoniboicU'i  and  splenii;  externally,  the  longissimus  dort^i;  deei)ly  the  semisj)inalis 
dorsi  and  complexus. 

Variations  of  the  erector  spinse  and  its  divisions. — The  number  of  ribs  or  vertebrse  from 
which  the  various  parts  of  these  divisions  arise,  or  into  whicli  thej'  arc  inserted,  varies  much. 
The  insertions  upon  tlie  lumbar  vertchnc  are  often  less  numerous  than  those  described.  Occa- 
sionally the  loiii.Mssimus  dorsi  receives  accessory  fibres  from  the  lower  ribs.  Sometimes  the 
portion  of  the  lonizissimus  dorsi,  which  arises  from  the  transverse  i)roces.ses  of  the  lower  thoracic 
vertebrse,  is  separate  from  the  rest  of  the  muscle,  and  is  inserted  into  the  transverse  processes  of 
some  of  the  upper  thoracic  vertebrse. 

Sixth  Layer 

The  sixth  layer,  or  rather  group,  consists  of  four  strata  of  oblique  muscles 
belonging  to  the  class  of  transverso-spinales;  the  deepest  stratum  being  formed  by 
a  series  of  small  muscles  which  run  upwards  and  inwards  from  the  back  of  one 
vertebra  to  that  of  the  next  above  it;  while  the  other  strata  run  in  the  same  direc- 
tion but  less  obliquely,  so  as  to  cross  over  the  backs  of  several  vertebra?  before 
reaching  their  insertion. 

1.  COMPLEXUS 

The  complexus,  or  semispinalis  capitis  (fig.  306) — named  from  the  complex 
or  complicated  arrangement  of  the  muscular  bundles  which  were  formerly  included 
under  this  designation,  viz.  the  complexus,  trachelo-mastoid,  &c. — is  a  musculo- 
tendinous band  somewhat  constricted  about  its  middle. 

Origin. — (1)  The  back  of  the  articular  processes  of  the  cervical  vertebrge  from 
the  third  to  the  sixth;  (2)  the  back  of  the  transverse  processes  of  the  seventh  cer- 
vical and  the  six  upper  thoracic  vertebrse;  (3)  generally  also  by  an  inner  head  from 
the  spine  of  the  seventh  cervical  vertebra. 

Insertion. — The  under  surface  of  the  occipital  bone  between  the  middle  and 
inferior  nuchal  lines  from  the  middle  line  for  nearly  two  inches  (5  cm.)  outwards. 

Structure. — Arising  by  tendinous  slips,  the  fleshy  fibres  pass  upwards  and 
slightly  inwards,  and  are  inserted  either  directly  into  the  occiput  or  by  a  short 
aponeurosis  which  covers  the  thick  part  of  the  muscle  near  its  outer  border.  On 
their  way,  the  innermost  fibres  are  intersected  by  a  transverse  tendinous  band 
opposite  the  sixth  cervical  spine,  and  this  part  of  the  muscle,  being  thus  divided, 
is  often  called  the  biventer  cervicis.  There  is  usually  also  a  smaller  tendinous 
intersection  across  the  posterior  surface  of  the  muscle  at  a  higher  level. 

Nerve-supply. — From  the  suboccipital  and  great  occipital  nerves,  and  from 
the  internal  divisions  of  the  posterior  branches  of  the  three  or  four  following 
cervical  nerves  which  enter  the  deep  surface  of  the  muscle. 

Action. — To  extend  the  head,  to  flex  it  laterally,  and  to  rotate  the  face  slightly 
to  the  opj)osite  side. 

Relations. — It  is  covered  by  the  trapezius  and  the  two  splenii,  and  it  lies  upon 
the  muscles  of  the  suboccipital  triangle  and  the  semispinalis  colli,  the  vertebral 
artery  and  the  anastomosis  between  the  arteria  princeps  cervicis  and  the  arteria 
profunda  cervicis.  It  is  pierced  by  the  great  occipital  nerve.  Internally  it  lies 
close  to  the  ligamentum  nuchse;  and  externally,  to  the  trachelo-mastoid  and 
transversalis  colli. 

Variations. — The  inner  head  may  arise  from  several  of  the  thoracic  sjiines  as  well  as  that  of 
the  seventh  cervical  vertebra.  Sometimes  a  second  and  smaller  complexus  runs  beneath  the 
normal  muscle  from  the  upper  thoracic  vertebrae  to  the  head. 

2.  SEMISPINALIS  DORSI 

The  semispinalis  dorsi — named  from  the  fact  that  the  inner  half  only  of  the 
muscle,  i.e.  its  insertion,  is  attached  to  the  spines  of  the  vertebrse,  and  from  its 
situation  in  the  dorsal  region — is  a  rather  feeble  compound  muscle,  consisting  of  a 
series  of  small  muscles  with  tendinous  extremities. 


SEMISPIXALIS  DO  RSI 


421 


Origin. — The  back  of  the  transverse  processes  of  the  sixth  to  the  tenth  tho- 
racic vertebra3. 


Kectua  capitis  posticus 
luiaor 


Fig.  308. — The  Sixth  Layee  of  the  Mlscles  of  the  Back. 

Complexus    ^-^ 

Obliquus  superior 

Rectus  capitis  posticus  major 

Obliquus  inferior 

Multifldus  spinas 

Semispinalis  colli 
Cervicalis  ascendens 

liOngissimus  dorsi 

Semispinalis  dorsi 


Levator  costae 


Longissimus  dorsi 
Ilio-costalis 

Obliquus  internus 
Lumbar  fascia 

Ilio-costalis 


SEVENTH  CERVICAL  VERT:3:iA 


Multifldus  spinas 


TWELFTH  THORACIC  VERTEBRA 


Multifldus  spinae 


FIFTH  LUMBAR  VERTEBRA 


Multifldus  spinae 


Insertion. — The  spines  of  the  last  two  cervical,  and  first  four  thoracic  verteltrai. 
Structure. — Arising  by  long  slender  tendons,  the  fleshy  fibres  f<jrm  a  thin  sheet 


422  THE  MUSCLES 

Avliich  runs  upwards  and  inwards,  and  tlien  breaks  up  again  into  sliort  tendons  of 
insertion.      Each  muscle  bridges  over  six  or  seven  vertel)ne. 

Nerve-supply. — The  internal  divisions  of  the  posterior  l)ranches  of  the  thoracic 
spinal  nerves. 

Action. — To  extend  and  laterally  Hex  the  lower  cervical  and  upper  thoracic 
portions  of  the  spinal  cohnnn.  The  upjjerniost  tendons  will  also  assist  in  rotating 
the  lower  ])art  of  the  neck  to  the  opposite  side. 

Relations. — .Superficially,  the  spinalis  and  longissinms  dorsi;  deeply,  the 
multitidus  spinse. 

3.  SEMISPINALS  COLLI 

The  semispinalis  colli — named  from  the  attachment  of  one-half  the  muscle, 
i.e.  the  insertion,  to  the  spines  of  the  cervical  vertebrae — is  a  somewhat  triangular 
sheet,  with  a  serrated  base  placed  vertically  along  the  transverse  processes,  and  the 
apex  at  the  spine  of  the  second  cervical  vertebra. 

Origin. — The  back  of  the  transverse  processes  of  the  five  or  six  upper  thoracic 
vertebne. 

Insertion. — The  spines  of  the  second  to  the  fifth  cervical  vertebrae. 

Structure. — Arising  by  short  tendons,  the  fleshy  fibres  pass  upwards  and 
inwards,  l>ridging  over  in  their  course  five  or  six  vertebrae,  and  are  inserted  by  still 
shorter  tendons  into  the  spines  of  the  cervical  vertebrae.  The  highest  is  by  far  the 
largest. 

Nerve-supply. — The  internal  divisions  of  the  posterior  branches  of  the  lower 
cervical  nerves,  the  upper  ones  entering  the  muscle  on  its  superficial,  and  the  lower 
on  its  deep  aspect. 

Action. — (1)  To  extend;  (2)  to  flex  laterally;  (3)  to  rotate  to  the  opi^osite 
side,  the  second  and  following  cervical  vertebrae. 

Relations. — Superficially,  the  complexus,  from  which  it  is  separated  by 
branches  of  the  posterior  cervical  nerves  and  the  anastomosis  of  the  arteria  jiro- 
funda  cervicis  with  the  arteria  princeps  cervicis;  deeply,  the  multifidus  spinae. 


4.  MULTIFIDUS   SPIN^ 

The  multifidus  spinae — named  from  its  many  divisions  (mtdhis,  many;  findo, 
to  cleave) — is  a  compound  muscle,  fleshy  and  thick  in  the  sacral  and  lumbar 
regions,  but  becoming  thin  and  more  aponeurotic  in  the  thoracic  and  cervical 
regions. 

Origin. — (1)  The  groove  in  the  back  of  the  sacrum,  between  the  spines  and  the 
elevations  which  represent  articular  j^rocesses,  the  posterior  sacro-iliac  ligaments, 
and  the  deep  surface  of  the  tendon  of  the  erector  spinae;  (2)  the  manmiillary 
processes  of  the  lumbar  vertebrae;  (3)  the  liack  of  the  transverse  processes  of 
all  the  thoracic  vertebrae;  (4)  the  articular  processes  of  the  fourth  to  the  sixth 
cervical  vertebrae,  and  the  back  of  the  transverse  process  of  the  seventh  cervical 
vertebra. 

Insertion. — The  lower  borders  of  the  spines  of  the  vertebrae  from  the  last 
lumltar  to  the  second  cervical. 

Structure. — Arising  by  tendinous  fibres  superficially,  but  by  fleshy  fil)res 
deeply,  the  bundles  of  each  element  of  the  muscle  diverge,  the  more  superficial 
ones  running  obliquely  upwards  and  inwards  so  as  to  In-idge  three  vertebne,  while 
the  deeper  ones  pass  more  transversely  to  the  third,  second,  and  in  the  neck,  the 
next  vertel)ra  above.  Consequently,  the  more  superficial  fil)res  from  one  vertebra 
overlap  the  (lee])er  ones  from  some  of  the  vertebrae  above. 

Nerve-supply. — The  internal  divisions  of  the  posterior  branches  of  tlie  spinal 
nerves  from  the  second  cervical  to  the  third  sacral. 

Action. — To  extend,  laterally  flex,  and  to  rotate  to  the  opposite  side,  the 
various  ]iarts  of  the  spinal  column. 

Relations. — Superficially,  the  erector  spinae,  longissimus  and  spmalis  dorsi, 
the  semispinalis  dorsi  and  colli;  deeply,  the  rotatores  spina-. 


ROTATORES  SPINJE—IXTERTRANSVERSALES  423 


5.   ROTATORES  SPINiE 

The  rotatores  spinae — named  from  the  rotatory  action  which  they  impress 
upon  the  spine — are  small  rhomboidal  sheets,  chiefly  found  in  the  thoracic  region, 
where  they  form  a  series  of  eleven  pairs,  but  occasionally  found  also  in  the  upper 
lumbar  and  the  lower  cervical  regions. 

Origin. — The  back  and  upper  border  of  the  transverse  process. 

Insertion. — The  lower  b(jrder  of  the  lamina  of  the  next  vertebra  above. 

Structure. — Sheets  of  parallel  fibres,  almost  entirely  fleshy,  which  run  upwards 
and  inwards. 

Nerve-supply. — The  internal  divisions  of  the  posterior  primary  branches. 

Action. — To  rotate  to  the  opposite  side,  and  also  to  extend  and  laterally  flex, 
the  vertebra  which  receiA'es  its  insertion. 

Relations. — Superficially,  themultifidusspinse;  deeply,  the  ligamenta  subflava. 


SEVE^'TH    Layer 

The  seventh  group  consists  of  short  vertical  muscles,  the  interspinales  and 
intertransversales,  Avhieh  lie  on  a  deep  plane  internal  and  external  to  the  transverso- 
spinales,  and  under  cover  of  the  longer  vertical  muscles  which  form  the  fifth  layer 
of  the  back. 

1.    IXTERSPIXALES 

The  interspinales — named  from  their  position — are  small  ribbon-like  muscles 
which  run  vertically  between  the  spines,  especially  in  the  cervical  and  lumbar 
regions. 

Origin. — The  upper  surface  of  the  spine  of  the  vertebra,  near  its  tip. 

Insertion. — The  posterior  part  of  the  lower  surface  of  the  spine  of  the  vertebra 
above. 

Structure. — In  the  neck  the  bundles  are  attached  to  the  two  parts  of  the  bifid 
extremities  of  the  spines  from  the  axis  downwards.  In  the  lumbar  region  they 
form  broader  bands  attached  to  the  whole  length  of  the  spines,  and  separated  by 
the  interspinous  ligaments. 

Nerve-supply. — The  internal  divisions  of  the  posterior  branches  of  the  spinal 
nerves. 

Action. — To  extend  the  vertebra  next  above. 

Relations. — Behind,  the  spinales  and  complexus;  internally,  the  interspinous 
ligaments;  externally,  the  multifidus  si^ina'. 

Variations. — Occasionally  they  pass  over  one  spine  to  be  inserted  upon  the  next  but  one. 
The  spinuhs  colli,  when  present,  may  be  looked  upon  as  a  still  greater  extension  of  this  variation. 


2.  INTERTRANSVERSALES 

The  intertransversales — named  from  their  position  between  the  transverse 
processes — are  small  vertical  l)ands,  also  found  chiefly  in  the  cervical  and  lumbar 
regions. 

In  the  neck  (fig.  316)  they  are  double,  the  anterior  band  connecting  the  anterior 
tubercles  of  the  transverse  processes  of  the  cervical  vertebrae,  and  the  posterior  the 
posterior  tubercles. 

In  the  lumbar  region  they  are  also  douVtle.  an  outer  set  connecting  the  adjacent 
surfaces  of  the  ends  of  the  transverse  processes,  and  an  inner  connecting  the 
accessory  tubercle  of  one  vertebra  to  the  mannnillary  tubercle  of  the  next  vertebra 
below.  A  few  similar  pairs  of  muscles  may  also  be  found  in  the  lower  part  of  the 
thoracic  region. 

Structure. — -Fleshy,  with  parallel  fibres. 


424  THE  MUSCLES 

Nerve-supply. — The  spinal  nerves  as  they  emerge  from  the  mtervertebral  for- 
amina. 

Action. — To  Hex  laterally  the  spinal  column. 

Relations. — In  the  neck,  the  anterior  primary  branches  of  the  nerves  come 
out  l)et\veen  the  anterior  and  })osterior  intertransversales,  and  the  posterior  primary 
branches  emerge  at  the  inner  borders  of  the  posterior  intertransversales.  They  are 
hidden  from  view  l\v  the  mass  of  muscles  attached  to  the  transverse  processes.  In 
the  lumbar  region  they  lie  under  cover  of  the  erector  spinse  and  its  divisions,  and 
they  are  covered  in  front  by  the  psoas  (fig.  286). 


THE  SUBOCCIPITAL  MUSCLES 

The  suboccipital  group  consists  of  short  muscles,  situated  in  the  same  plane  as 
the  preceding,  but  somewhat  altered  in  their  arrangement  on  account  of  the  })eculiar 
movements  of  the  region.  They  are  the  rectus  capitis  posticus  major  and  minor, 
the  obliquus  capitis  inferior  and  superior,  the  rectus  capitis  lateralis. 


1.  RECTUS  CAPITIS  POSTICUS  MAJOR 

The  rectus  capitis  posticus  major  (fig.  308) — somewhat  incorrectly  named 
from  the  direction  of  its  fil)res,  its  position,  and  size — is  a  triangular  sheet. 

Origin. — The  upper  surface  of  the  spine  of  the  axis  along  its  side  and  one-half 
of  its  bitid  tip. 

Insertion. — The  middle  third  of  the  inferior  nuchal  line  of  the  occipital  bone. 

Structure. — From  a  narrow  tendinous  origin  the  fleshy  fi1)res  diverge  as  they 
run  upwards  and  outwards  to  a  broad  insertion. 

Nerve-supply. — A  branch  of  the  suboccipital  which  enters  the  middle  of  its 
superficial  surface. 

Action. — To  extend  the  head  upon  the  neck;  and  to  rotate  the  head  to  the 
same  side. 

Relations. — Behind,  the  complexus  and  obliquus  superior;  in  front,  the 
succeeding  muscle. 

2.  RECTUS  CAPITIS  POSTICUS  MINOR 

The  rectus  capitis  posticus  minor  (fig.  308) — named  from  its  direction,  size, 
and  position — is  also  flat  and  triangular. 

Origin. — The  upper  part  of  one-half  of  the  posterior  tubercle  of  the  atlas. 

Insertion. — The  inner  third  of  the  inferior  nuchal  line  of  the  occipital  bone, 
and  the  s})ace  immediately  in  front  of  it. 

Structure. — Fleshy,  and  consisting  of  fibres  which  diverge  in  fan  shape  as  they 
pass  upwards  and  outwards. 

Nerve-supply. — Branches  of  the  suboccipital  nerve  which  enter  the  outer  part 
of  its  su}K'rficial  surface. 

Action. — To  extend  the  head  on  the  neck. 

Relations. — Behind,  the  preceding  muscle  and  complexus;  in  front,  the  pos- 
terior occipito-atlantal  ligament. 


3.  OBLIQUUS  CAPITIS  INFERIOR 

The  obliquus  capitis  inferior  (fig.  308)— uanud  from  its  direction  and 
position — is  a  fusiform  sheet. 

Origin. — The  up])er  })art  of  the  side  of  tb(^  spine  of  the  axis. 

Insertion. — The  lower  part  of  the  ti])  of  the  transverse  process  of  the  atlas. _ 

Structure. — Strong  and  fleshy,  with  pointed  extremities,  and  a  general  direc- 
tion upwards  and  outwards. 


MUSCLES  OF  THE  HEAD   AXD   NECK  425 

Nerve-supply. — The  suboccipital,  Avhicli  sends  branches  to  its  upper  lx)rder. 

Action. — Chietly  to  rotate  the  atlas,  and  with  it  the  head,  to  the  same  side.  It 
will  also  help  in  extension  and  lateral  flexion  of  the  atlas  upon  the  axis. 

Relations. — Behind,  the  coniplexus  and  the  great  occipital  nerve,  which  winds 
round  its  lower  border;  in  front,  the  posterior  atlanto-axial  ligament  and  vertebral 
artery. 

4.  OBLIQUUS  CAPITIS  SUPERIOR 

The  obliquus  capitis  superior  (fig.  308) — named  from  its  direction  and  position 
— is  flat  and  triangular. 

Origin. — The  back  of  the  upper  surface  of  the  transverse  process  of  the  atlas. 

Insertion. — The  impression  immediately  behind  the  outer  half  of  the  inferior 
nuchal  line  of  the  occipital  bone. 

Structure. — Of  fleshy  fibres  which  diverge  fauAvise  upwards  and  inwards. 

Nerve-supply. — The  suboccipital,  which  supplies  it  at  the  inner  part  of  its 
deep  surface. 

Action. — To  extend  and  slightly  to  flex  laterally  the  head. 

Relations. — Behind,  the  complexus  and  splenius  capitis;  in  front,  the  rectus 
capitis  posticus  major,  vertebral  artery,  and  posterior  occipito-atlantal  ligament. 


5.  RECTUS  CAPITIS  LATERALIS 

The  rectus  capitis  lateralis  (fig.  316) — named  from  its  direction  and  position 
— is  a  quadrilateral  sheet,  and  corresponds  to  the  intertransversales  posteriores  of 
the  vertebrae  below. 

Origin. — The  front  of  the  upper  surface  of  the  lateral  mass  of  the  atlas. 

Insertion. — The  under  surface  of  the  jugular  process  of  the  occipital  bone. 

Structure, — Fleshy,  with  parallel  vertical  fibres. 

Nerve-supply. — The  anterior  branch  of  the  first  cervical  nerve  which  passes 
out  internal  to  it,  and  supplies  it  from  the  front. 

Action. — To  flex  the  head  laterally. 

Relations. — In  front,  the  anterior  primary  branch  of  the  first  cervical  nerve, 
and  the  internal  jugular  vein;  behind,  the  obliquus  superior  and  the  trachelo- 
mastoid. 

Variations. — Occasionally  the  short  muscles  of  this  group  are  double.  Small  slips  of  muscle 
have  been  observed,  ininning  from  the  spines  of  the  lower  cen'ical  vertebrae,  or  the  ligamentum 
nuchae  to  the  occipital  bone. 


MUSCLES  OF  THE  HEAD  AND  NECK 

The  superficial  layer  in  this  region  is  peculiar  in  that  it  consists  of  numerous 
muscles  containecl  in  the  connective  tissue  outside  the  deep  fascia.  This  connective 
tissue,  the  superficial  fascia,  is  moderately  provided  Avith  fat,  and  extends  without 
any  deep  connection  to  the  adjacent  regions  of  the  thorax,  arm,  and  back.  In  the 
scalp  it  is  firm  and  difficult  to  dissect  on  account  of  numerous  septa  Avhich  pass 
through  it  to  unite  the  skin  to  the  subjacent  muscular  aponeurosis.  In  this  situa- 
tion the  superficial  fascia  is  richly  provided  Avith  blood  l)y  vessels  Avhich  run  Avithin 
it  instead  of  beneath  the  deep  fascia,  Avhich  is  their  usual  i)ositi()n  in  other  parts  of 
the  body. 

Besides  the  peculiarity  of  their  position  outside  tlie  deep  fascia,  these  muscles 
are  all  associated  in  their  function,  A'iz.  to  produce  the  various  movements  of  the 
features    by  Avhich  the  expression  of   the  emotions  is   effected.      They    are  also 


426  THE  MUSCLES 

peculiar  in  the  fact  that  many  of  them  decussate  with  one  another  on  the  Avay  to 
their  insertion  in  the  skin;  and  they  are  all  supplied  by  the  seventh  pair  of 
cranial  nerves. 


SUPERFICIAL  MUSCLES  OF  NECK  AND  SCALP 

1.  PLATY8MA  MYOIDES 

The  platysma  myoides — named  from  its  flat  expanse  {platysma,  a  plate)  and 
its  similarity  to  muscle  {ini/oides,  like  muscle,  for  the  older  anatomists  considered 
it  to  be  only  a  membrane) — is  a  quadrilateral  sheet  with  a  somewhat  toothed 
posteri(^r  1>order. 

Origin. — (1)  The  deep  fascia  of  the  upper  part  of  the  front  of  the  chest  and 
the  shoulder,  and  the  deep  cervical  fascia  covering  the  sterno-mastoid. 

Insertion. — (1)  The  outer  surface  of  the  lower  border  of  the  body  of  the 
mandible,  bt)th  on  the  same  and  the  opposite  side;  (2)  the  deep  surface  of  the  skin 
from  the  corner  of  the  mouth  to  the  anterior  border  of  the  masseter  muscle. 

Structure. — Arising  by  slender  bundles  from  the  fascia  covering  the  pectoralis 
major  and  deltoid,  in  a  line  from  the  second  costal  cartilage  to  the  tip  of  the 
acromial  process,  the  pale  muscular  fibres  at  first  converge  slightly  until  they  have 
crossed  the  clavicle.  They  then  run  parallel  to  one  another  upwards  and  forwards, 
receiving  at  the  posterior  border  of  the  muscle  small  teeth  from  the  deep  fascia 
forming  the  sheath  of  the  sterno-mastoid.  The  anterior  fibres  cross  the  middle  line 
half-way  between  the  hyoid  bone  and  the  symphysis,  and  are  inserted  into  the 
lower  border  of  the  body  of  the  mandil:)le  upon  the  opposite  side  of  the  neck.  The 
greater  part  of  the  rest  are  inserted  into  the  outer  surface  of  the  lower  border  of 
the  mandible  on  the  same  side,  but  some  are  continued  upwards  and  join  Avith  the 
depressor  labii  inferioris.  Still  fvirther  back,  a  few  fibres  pass  upwards  over  the 
lower  part  of  the  masseter,  and  are  inserted  into  the  deep  surface  of  the  skin  just 
outside  the  angle  of  the  mouth.  A  strong  bundle  of  these  fibres  which  runs  nearly 
transversely  forwards  to  the  corner  of  the  mouth  will  be  described  later  as  the 
risorius  muscle.  In  its  whole  extent,  the  muscle  is  closely  connected  with  the  deep 
surface  of  the  skin. 

Nerve-supply. — The  seventh  cranial  nerve,  by  means  of  the  inframandil)ular 
branch  of  the  cervico-facial  division,  which  supplies  it  from  beneath  at  a  point  a 
little  below  the  angle  of  the  mandible. 

Action. — (1)  To  draw  downwards  and  outwards  the  lower  lip,  by  means  of  the 
fibres  which  are  continued  upwards  into  the  depressor  labii  inferioris.  In  trans- 
verse wounds  below  the  mandible,  the  division  of  this  muscle  often  impairs  this 
movement.  Duchenne  has  shown  how  important  a  part  this  depression  of  the 
lower  lip  discbarges  in  the  expression  of  horror  or  extreme  surprise.  (2)  To  draw 
outwards  the  soft  parts  of  the  side  of  the  neck,  so  as  to  diminish  pressure  upon  the 
veins  during  strong  inspiratory  efforts.  As  the  muscle  is  arched  in  its  ])assage 
from  the  clavicle  to  the  mandible,  with  the  concavity  directed  outwards,  it  is  plain 
that  its  contraction  will  flatten  the  arch  and  tend  to  lift  the  skin  and  fascia'  off  the 
vessels,  in  exactly  the  opposite  manner  to  that  by  which  pressure  is  exerted  when 
the  concavity  is  upon  the  deep  surface  of  a  muscle.  (3)  It  may  assist  feebly  in 
depression  of  the  mandible;  and,  if  that  be  fixed,  in  flexion  of  the  head  and  rotation 
towards  the  same  side.  This  muscle  covers  all  the  front  of  the  neck  with  the 
exception  of  a  narrow  triangular  interval,  the  base  of  which  is  formed  by  the  upjun* 
Vjorder  of  the  sternum  and  the  adjacent  sterno-clavicular  joints. 

Relations. — It  lies  inmiediately  bcneatli  the  skin  and  superficial  fascia,  and  in 
a  lean  neck  the  bundles  are  often  distinctly  visible  through  tlie  skin,  esi^ecially 
when  an  effort  is  made  to  depress  the  lower  li])  while  the  teeth  are  clenched. 
A  thin  band  derived  from  the  anterior  part  of  tlie  dei)ressor  anguli  oris  usually 
crosses  it  superficially  beneath  the  chin  (page  48<S).  Upon  its  deep  surface  lie 
the  deep  cervical  fascia,  the  external  jugular  vein,  the  glanduUc  concatenatfe  of  the 
neck,  the   parotid   and  submaxillary  glands,  and  the  superficial  branches  of  the 


OCCIPITO-FROXTALIS 


427 


cervical  plexus,  too;ether  with  tlic  masscter,  and  buccinator,  the  muscles  of  the 
front  and  side  of  the  neck,  and  the  pectoralis  major  and  deltoid.  'Its  anterior 
border  lies  externally  to  the  sterno-clavicular  Joint,  and  is  often  conspicuous  in 
the  aged,  in  whom  the  two  muscles  may  be  seen  to  hang,  like  a  dewlap,  beneath 
the  chin,  and  then  to  divide  into  the  two  separate  folds  formed  by  their  internal 
borders,  which  run  outwards  and  downwards  towards  the  clavicles. 

Variations. — The  anterior  bonier  of"  tlie  mu.scle  may  be  placed  as  fiir  backwards  as  the  middle 
of  the  clavicle,  and  in  some  cases  the  muscle  has  been  entirely  absent.  Slips  have  been  seen 
going  to  the  side  of  the  thyroid  cartilage,  the  auricle  or  the  mastoid  process. 


Fig.  309. — The  Supekficiai.  jMuscles  of  the  Head  axd  Neck. 


Epicranial 
aponeurosis 


Orbicularis  palpebrarum 


Pyramidalis 

Levator  labii  superioris 
aleeque  nasi 
Compressor  narium 

Dilatator  naris  anterior 
Dilatator  naris  posterior 

Levator  labii  superioris 

Zygomaticus  minor 

Levator  anguli  oris 
Orbicularis  oris 


Depressor  labii  inferioris 
Depressor  anguli  oris 


Attollens 
aurem 

[|,  I        Attrahens 
^  aurem 

Occipitalis 

^    Retrahens 

aurem 


Trapezius 


2.  OCCIPITO-FROXTALIS 

The  occipito-frontalis — named  from  its  two  muscular  bellies.  Avhich  cover 
])arts  of  the  occipital  and  frontal  bones — consists  of  two  curved  muscular  sheets 
united  by  a  strong  a])oncurosis.  and  is  best  described  in  three  parts — viz.  the 
occipitalis  and  frontalis  muscles  and  the  epicranial  aponeurosis. 

( 1 )   The  occipitalis  is  a  small  (luadrilateral  sheet. 

Origin. — (  1  j  The  outer  two-thirds  of  the  superior  nuchal  line  of  the  occipital 
bone,  and  (2)  a  ridge  upon  the  mastoid  process. 


428  THE  MUSCLES 

Insertion. — The  posterior  border  of  the  epicranial  aponeurosis,  about  one  inch 
and  a  half  (3 '7  cm.)  above  the  su})erior  nuchal  line  of  the  occipital  bone. 

(2)  The  frontalis — a  curved  sheet  of  somewhat  quadrilateral  shape,  Avith  a 
convex  upper,  and  a  concave  lower  border. 

Origin. — The  ei)irranial  aponeurosis,  aljout  half-way  between  the  coronal 
suture  and  the  orbital  arch. 

Insertion. — The  deep  surface  of  the  skin  of  the  eyebrow  and  of  that  which 
occupies  the  space  at  the  r(^ot  of  the  nose  between  the  eyebrow  and  the  middle 
line. 

(3)  The  epicranial  aponeurosis  forms  the  central  tendon  of  the  occipito- 
frontalis,  and  its  attachments  will  be  described  with  the  structure  of  the  muscle. 

Structure. — The  occipitalis  is  thin  and  pale,  and  arises  by  sliort  tendinous  inter- 
mingled with  muscular  fibres,  and,  after  passing  in  parallel  lines  for  about  one  inch 
and  a  half  (3' 7  cm. )  upwards,  it  is  inserted  into  the  epicranial  aponeurosis,  a  strong 
curved  sheet,  which  occupies  the  whole  of  the  surface  of  the  skull  from  the  superior 
nuchal  lines  l^ehind  to  the  eyebrows  in  front,  and  is  continued  laterally  over  the 
temporal  fascia  of  either  side  to  about  the  level  of  the  external  auditory  meatus. 
Al)ove,  it  is  tendinous,  and  composed  of  fibres  which  run  from  behind  forwards. 
It  is  thin  in  front  and  behind,  where  it  forms  a  sort  of  sheath  to  the  occipitalis  and 
frontalis  muscles;  but  near  the  median  line  behind,  it  is  thick  where  it  fills  up  the 
interval  between  the  occipitales.  Laterally,  it  becomes  very  thin,  and  is  lost  in 
the  loose  connective  tissue  superficial  to  the  temporal  fascia  after  having  given 
origin  to  the  attrahens  and  attollens  aurem  muscles.  In  front,  a  narrow  triangular 
slip,  with  the  base  upwards  and  the  apex  between  the  eyebrows,  is  left  betAveen  the 
frontales,  which  are  larger  and  somewhat  thicker  than  the  occipitales.  The  fibres 
of  the  frontales  run  in  parallel  Inmdles  downwards  and  slightly  inwards,  and  are 
lost  in  the  subcutaneous  fat  of  the  eyebrows;  while  near  the  middle  line  a  small 
slip  is  continued  upon  the  bridge  of  the  nose  as  the  pyramidalis,  after  entering 
into  close  relation  with  the  deep  surface  of  the  skin  at  the  junction  of  the  forehead 
and  nose. 

Nerve-supply. — The  occipitalis  receives  one  of  the  divisions  of  the  posterioi 
auricular  branch  from  the  facial  or  seventh  cranial  nerve.  Its  filaments  enter  the 
deep  surface  of  the  muscle  close  to  the  outer  border. 

The  frontalis  is  supplied  by  the  temporal  branch  of  the  temporo-facial  divi- 
sion of  the  facial  nerve  which  is  distriljuted  to  the  deep  surface  near  its  outer 
border. 

Action. — The  occipitales  draw  back  the  epicranial  aponeurosis,  and  with  it  the 
scalp,  which  is  intimately  attached  to  its  superficial  aspect.  Acting  from  behind, 
the  frontales  raise  the  eyebrows.  If  these  are  fixed  by  the  contraction  of  the 
orbicularis  palpebrarum,  the  frontalis  will  draw  forwards  the  epicranial  aponeu- 
rosis and  scalp.  When  both  occipitales  and  frontales  contract,  they  raise  the 
eyebrows  to  the  utmost  extent,  and  throw  the  skin  of  the  forehead  into  transverse 
"wrinkles,  as  in  the  expression  of  surj^rise  or  horror.  At  the  same  time,  on  account 
of  the  direction  of  the  hair-bulbs,  which  lie  with  a  forward  slant  behind  and  a 
backward  slant  in  front,  there  will  be  a  tendency  to  lift  the  hair  shafts,  and  to 
make  them  '  stand  on  end,  like  quills  upon  the  fretful  porcupine.' 

When  the  frontalis  alone  contracts,  taking  its  fixed  point  from  above,  a  slight 
elevation  of  the  eyebrow  is  produced,  as  in  the  expression  of  attention.  This  is 
also  accompanied  by  a  transverse  wrinkling  of  the  forehead. 

Relations. — Superficially,  the  epicranial  aponeurosis  and  its  muscles  are  in 
very  close  connection  with  the  skin  of  the  scalp  and  forehead,  being  only  separated 
from  it  by  granular  fat  which  is  contained  in  small  com]iartments  formed  b}'  fibrous 
septa  extending  from  the  aponeurosis  to  the  deep  surface  of  the  skin.  In  tlie  fat 
lie  the  hair-bulbs  and  blood-vessels  of  the  scalp.  Beneath,  it  is  separated  from  the 
pericranium  and  temporal  fascia  by  very  loose  connective  tissue. 

Variations.-— The  occipitalis  may  be  continuous  with  the  retrahetis  aurem.  The  frontalis  may 
have  insertions  into  the  external  or  internal  angle  of  the  frontal  bone,  the  nasal  process  of  the 
maxilla,  or  the  uasal  bone. 


ORBICULARIS  PALPEBRARUM  429 


THE   MUSCLES   OF   THE   EYELIDS   AND    EYEBROWS 

These  are  four  in  number — viz.  the  orbicularis  palpel^rarum,  the  tensor  tarsi, 
the  corrugator  supercilii,  and  the  levator  palpeljne  superioris.  To  these  may  be 
added  a  fifth,  the  frontalis,  which  has  been  described.  The  levator  palpebrae 
superioris  will  be  descril)ed  with  the  or1)ital  muscles.  The  only  part  of  it  which  is 
visible  in  a  dissection  of  the  face  is  its  l)road  expansion,  which  is  intimately  blend(^d 
with  the  front  of  the  crescentic  plate  of  condensed  fibrous  tissue  called  the  upper 
tarsal  cartilage. 

1.  ORBICULARIS  PALPEBRARUM 

The  orbicularis  palpebrarum — named  from  the  rounded  shape  of  the  majority 
of  its  filn'es  (orbiculas,  a  little  circle)  and  its  relation  to  the  eyelids — is  an  oval 
sheet  with  a  long  transverse  diameter  and  so  curved  as  to  fit  the  prominences  and 
depressions  of  the  eyelids  and  the  margin  of  the  orbit. 

It  consists  of  a  marginal  and  a  central  division:  the  former  stronger  and  called 
the  orbital  portion;  the  latter  thin  and  pale,  and  called  the  palpebral  portion.  Both 
have  attachments  to  the  tarsal  ligaments,  by  which  the  so-called  tarsal  cartilages 
are  fastened  to  the  margins  of  the  orbit.  The  internal  tarsal  ligament,  or  tendo 
oculi,  is  a  strong  flat  band  of  fil^rous  tissue  al)OUt  a  sixth  of  an  inch  (4  mm.)  long 
with  surfaces  which  look  upwards  and  downwards.  It  arises  from  a  projection  upon 
the  crest  of  the  nasal  process  of  the  maxilla,  and  passes  transversely  outwards  and 
somewhat  upwards  in  front  of  the  lachrymal  sac,  to  which  it  gives  off  an  aponeu- 
rotic covering.  It  then  bifurcates  into  an  upper  and  a  lower  division,  which  diverge 
to  be  attached  to  the  inner  extremities  of  the  tarsi,  here  separated  by  the  caruncula 
lachripnalis.  The  external  tarsal  ligament  is  undivided;  it  passes  from  the 
margin  of  the  frontal  process  of  the  malar  bone  transversely  inwards  to  the  ex- 
tremities of  the  tarsi,  which  at  the  outer  commissure  of  the  eyelids  are  in  close 
contact. 

The  orbital  portion  of  the  orljicularis  palpebrarum  consists  of  a  series  of  con- 
centric oval  1(  )0ps  which  are  attached  only  at  the  inner  side  of  the  orbit. 

Origin  and  insertion. — ( 1)  The  lower  part  of  the  internal  angular  process  of 
the  frontal  l)one;  (2)  the  posterior  half  of  the  outer  surface  of  the  nasal  process  of 
the  maxilla;  (3)  the  upper  and  lower  surfaces  of  the  inner  half  of  the  internal 
tarsal  ligament. 

The  palpebral  portion  consists  of  paler  and  shorter  semielliptical  fibres. 

Origin. — The  upper  and  lower  surfaces  of  the  outer  half  of  the  internal  tarsal 
ligament,  together  with  the  adjacent  part  of  the  aponeurosis  covering  the  lachrymal 
sac. 

Insertion. — The  upper  and  lower  surfaces  of  the  external  tarsal  ligament. 

Structure. — Both  portions  of  the  muscle  are  entirely  composed  of  fieshy  fibres. 
In  addition  to  the  origin  of  the  orliital  portion  at  the  inner  part  of  the  orV)it,  it  gives 
off  processes  from  its  circumference  which  1  :)lend  with  the  adjacent  muscles,  such  as 
the  frontalis  and  the  elevator  of  the  upper  lip.  Moreover,  some  of  the  deeper  fil)rcs 
of  the  muscle  decussate  with  the  fibres  of  those  adjacent  muscles  which  lie  under 
cover  of  the  outer  loops. 

The  innermost  fibres  of  the  palpebral  portion  are  shorter  than  the  rest  and, 
instead  of  extending  across  the  whole  length  of  the  tarsi,  they  terminate  upon  their 
free  margins,  l)etween  the  attachment  of  the  eyelashes  and  the  orifices  of  certain 
glands  which  line  the  inner  surface  of  the  tarsi. 

Nerve-supply. — The  temporal  and  malar  branches  of  the  temporo-facial  divi- 
sion of  the  facial  nerve,  which  enter  the  outer  part  of  the  muscle  upon  its  deep 
surface. 

Action. — (1)  The  orldtal  portion  l)y  its  contraction  draws  the  soft  parts  around 
the  opening  of  the  orbit  inwards  and  towards  the  palpebral  aperture,  raising  a 
ridge  which  deepens  the  socket  of  the  eye  so  as  to  protect  the  eyeball  from  injury, 
e.g.  from  the  blow  of  a  fist;  (2)  Its  upper  part  will  lower  the  eyebrow,  as  when 
the  face  is  exposed  to  a  strong  light,  or  when  the  mind  is  wrapt  in  thought.      (3) 


430 


THE  MUSCLES 


The  palpebral  portion  will  lower  the  vipper  and  raise  the  lower  eyelid,  in  elosiire  of 
the  eye.  (4)  The  hrni  eontraction  of  the  Avhole  nmsele  presses  upon  the  eyeball, 
and  supports  it  from  the  evil  elfeet  of  a  strong  expiratory  effort,  which  by  the  rush 
of  blood  int(5  the  interior  of  the  eyeliall  might  burst  its  thin-walled  vessels,  and  do 
serious  harm  to  the  delicate  structures  within.  Thus  it  will  l)e  noticed  that  in 
shouting,  sneezing,  or  violent  coughing  the  eyes  are  tightly  closed.  (5)  By  pressure 
upon  the  lachrymal  gland  it  is  probable  that  the  nmsele  influences  the  secretion  of 
tears:  hence  their  flow  during  violent  coughing  or  laughter.  It  wull  also  draAv  out- 
wards and  forwards  the  covering  of  the  lachrymal  sac,  and  so  produce  a  suction  of 
the  tears  through  the  canaliculi  into  the  sac. 

Relations. — Superficially,  the  skin;  upon  its  deep  surface  the  tarsal  cartilages 
and  thfir  ligaments,  the  palpe])ral  ligaments  and  the  expansion  of  the  tendon  of 
the  levator  palpebrse  superioris;  the  liones  which  bound  the  opening  of  the  orbit, 
the  frontalis  and  corrugator  supercilii  muscles  aljove;  the  temporal  fascia  exter- 
nally; tlie  zygomaticus  minor,  levator  labii  superioris,  and  levator  labii  superioris 
alaeque  nasi,  below;  also  the  supraorbital  vessels  and  nerve,  the  supratrochlear 
nerve,  the  terminal  portion  of  the  facial  artery,  and  the  palpebral  branches  of  the 
infraorbital  vessels  and  nerve. 

2.  TENSOR  TARSI 

The  tensor  tarsi — named  from  its  supposed  action  upon  the  tarsus — is  a  small 
muscle  com}»osed  of  two  flat  slips,  which  are  closely  connected  with  the  preceding 
muscle. 

Fig.  310. — The  Texsor  Tarsi  and  Corrugator  Supercilii. 


Orbicularis 
palpebrarum 


Tensor  tarsi 


Corrugator  supercilii 
Obliquus  superior 


Obllquus  inferior 


Origin. — The  crest  of  the  lachrymal  bone. 

Insertion. — The  posterior  aspect  of  the  inner  end  of  the  tarsi. 

Structure. — Arising  as  a  thin  muscular  sheet,  at  the  back  of,  and  in  close  con- 
tact with,  the  outer  surface  of  the  lachrymal  sac,  the  muscle  divides  into  tAvo  slips 
which  run  behind  the  canaliculi,  and  are  inserted  into  the  edge  of  the  eyelids  near 
the  puncta  lachrymalia. 

Nerve-supply. — From  the  infraorbital  branch  of  the  upper  division  of  the 
facial  nerve,  by  small  slips  which  enter  the  muscle  near  its  lower  Ijorder. 

Action. — To  compress  the  lachrymal  sac  l:)y  drawing  inwards  and  l^ackwardstho 
outer  ])ai-t  of  the  tendo  oculi  and  the  inner  ends  of  the  tarsi. 

Relations. — Internally  and  in  front,  the  lachrymal  sac;  externally  and  lu'hind, 
the  orbital  fat  from  which  it  is  separated  by  the  capsule  of  Tenon. 


3.  CORRUGATOR  SUPERCILII 

The  corrugator  supercilii — named  from  its  action,  the  Avrinkling  of  the  brow — 
is  a  short  ribbon-:-ha])cd  muscle. 

Origin. — The  inner  extremity  of  the  superciliary  ridge  of  the  frontal  bone. 


A  TTOLLENS  A  UREM—A  TTRA HENS  A  UREM  431 

Insertion. — The  deep  surface  of  the  skin  at  the  middle  of  the  e3'ebrow. 

Structure. — A  small  wisp  of  fleshy  fibres,  closely  connected  with  the  or])ital 
portion  of  the  orljicularis  pal])ebrarum.  It  passes  outwards,  and  at  the  same  time 
sli<jhtly  U))wards  and  forwards,  to  the  under  surface  of  this  muscle,  and,  diverging 
slightly,  its  fibres  pass  between  the  interlacing  fi])res  of  the  orl)icularis  and  frontalis 
to  their  insertion  into  the  skin. 

Nerve-supply. — The  temporal  branch  of  the  upper  division  of  the  facial  nerve, 
whicli  tenters  its  deep  surface  from  the  outer  side. 

Action. — To  draw  the  middle  of  the  eyel)row  inwards  and  slightly  downwards. 
In  the  adult  this  causes  vertical  wrinkles  to  form  between  the  evebrows,  and  gives 
a  frowning  aspect  to  the  face,  as  when  a  difficulty  occurs  either  in  thought  or  action. 
In  the  crying  infant,  the  effect  of  its  contraction  is  to  cause  dimples  about  the 
centre  of  the  eyebrows,  which  may  usually  be  observed  just  before  the  orbiculares 
pal})ebrarum  close  the  eyes. 

Relations. — Superficially,  the  orbicularis  palpebrarum ;  deeply,  the  frontal  bone. 

For  The  Muscles  of  the  Eye,  see  pages  854-7. 


THE  EXTRINSIC  MUSCLES  OF  THE  AURICLE 

The  extrinsic  muscles  of  the  auricle  (fig.  309) — viz.  the  attollens  aurem, 
the  attrahens  aurem,  and  the  retrahens  aurem — are  feeble,  and  almost  vestigial 
in  man.  They  are  closely  connected  Avith  the  occipito-frontalis.  The  largest  of 
the  three  is  the  attollens  aurem. 


1.  ATTOLLENS  AUREM 

The  attollens  aurem — named  from  its  action  as  an  elevator  of  the  avuicle — is 
a  thin  triangular  sheet. 

Origin. — The  epicranial  aponeurosis,  a  short  distance  Ijelow  the  top  of  the 
temj)oral  ridge. 

Insertion. — The  inner  surface  of  the  pinna  of  the  auricle,  over  a  space  which 
corresi)onds  to  the  fossa  of  the  antihelix  upon  its  outer  surface. 

Structure. — A  thin,  fan-shaped  sheet,  consisting  of  muscular  fibres  and  bands 
of  connective  tissue,  which  all  converge  from  above  upon  a  flat  tendon  just  above 
the  point  of  insertion. 

Nerve-supply. — The  temporal  branch  of  the  upper  division  of  the  facial  nerve, 
by  filaments  which  enter  the  front  of  the  deep  surface. 

Action. — To  draw  upwards  the  auricle. 

Relations. — Superficially,  the  skin;  deeply,  the  temporal  fascia  and  auriculo- 
temptn-al  nerve. 

2.  ATTRAHENS  AUREM 

Tlie  attrahens  aurena — named  from  its  action  in  drawing  forwards  the  auricl» — 
is  a  smaller  and  very  thin  triangular  sheet. 

Origin. — The  lateral  border  of  the  epicranial  aponeurosis  in  front  of  and  below 
the  level  of  the  preceding,  with  which  it  is  usually  continuous. 

Insertion. — The  front  of  the  inner  surface  of  the  helix. 

Structure. — It  consists  of  a  thin  stratum  of  muscular  fibres,  intermingled  with 
comiective  tiss'ue,  lying  upon  the  temporal  fascia,  and  converging  backwards  and 
downwards  upon  a  feei)le  flat  tendon. 

Nerve-supply. — The  same  as  the  preceding. 

Action. — To  draw  forwards  and  upwards  the  auricle. 

Relations. — Superficially,  the  skin;  deeply,  the  temporal  fascia,  temporal 
artery,  and  auriculo-temporal  nerve. 


432  THE  MUSCLES 


3.   RETRAHENS  AUREM 

The  retrahens  aurem — named  from  its  aetion  of  drawing  back  the  auricle — 
consists  of  two  nuiscular  l)ands,  wliich  narrow  shghtly  as  they  pass  forwards  to  the 
ear. 

Origin. — Tlie  upper  part  of  the  outer  surface  of  the  mastoid  process  of  the 
temporal  bone. 

Insertion. — The  inner  surface  of  the  concha. 

Structure. — It  consists  usually  of  darker  and  more  distinctly  fleshy  bands 
than  the  two  preceding  muscles.  They  arise,  one  alcove  the  other,  by  short  tendi- 
nous fibres  from  the  mastoid  process,  and  pass  transversely  forwards  to  their  tendi- 
nous insertion. 

Nerve -supply. — The  posterior  auricular  Ijranch  of  the  facial,  which  sends 
filaments  to  the  lower  part  of  its  deep  surface. 

Action. — To  draw  l^ack  the  auricle. 

Relations. — Superficially,  the  skin;  deeply,  the  posterior  auricular  artery,  part 
of  the  great  auricular  and  the  posterior  auricular  nerves. 


THE  MUSCLES  OF   THE  NOSE 

The  chief  muscles  of  the  nose  are  three  in  number:  viz.  the  pyramidalis  nasi 
and  compressor  narium,  which  consist  of  muscular  fibres  which  pass  up^vards  and 
outwards  from  an  aponeurosis,  covering  the  cartilaginous  part  of  the  ridge  of  the 
nose,  and  intimately  connected  with  the  under  surface  of  the  skin;  and  the  depressor 
alse  nasi.  A  small  slij)  from  the  levator  labii  superioris  alseque  nasi  is  also  attached 
to  the  ala  nasi;  and  two  little  muscles  may  sometimes  be  found  in  the  subcutaneous 
tissue  upon  the  outer  surface  of  the  nostril:  viz.  the  dilatator  naris  anterior  and 
posterior. 

1.  PYRAMIDALIS 

The  pyramidalis  (figs.  309  and  311) — named  from  its  triangular  shape,  Avhich  is 
like  the  side  of  a  pyramid — is  a  thin  sheet. 

Origin, — The  upper  border  of  the  nasal  aponeurosis  over  the  junction  of  the 
cartilage  with  the  lower  border  of  the  nasal  bone. 

Insertion. — The  deep  surface  of  the  skin  lietween  the  eyebrows,  being  at  this 
point  cuntiiuious  with  the  inner  fibres  of  the  frontalis. 

Structure. — The  muscular  fibres  form  a  slightly  curved  sheet,  Avhich  wraps 
round  the  anterior  surface  of  the  nasal  bone,  and  is  continuous  with  the  correspond- 
ing muscle  of  the  other  side.  They  converge  as  they  pass  upwards,  and  the  outer 
ones  run  slightly  inwards  as  well  as  upwards,  to  their  insertion. 

Nerve-supply. — The  infraorbital  branch  of  the  uppc^r  division  of  the  facial, 
which  enters  the  outer  part  of  its  deep  surface. 

Action. — To  draw  downwards  the  skin  between  the  eyebrows,  so  as  to  throw  it 
forwards  into  a  fold,  and  at  the  same  time  to  produce  a  transverse  groove  above 
the  bridge  of  the  nose.  This  gives  to  the  face  a  stern,  aggressive,  or  fierce 
expression. 

Relations. — Sujicrticially,  the  skin;  and  deeply,  the  nasal  bone. 

Variation. — Tills  muscle  is  sometimes  absent. 


2.  COMPRESSOR  NARIUM 

The  compressor  narium  (figs.  309  and  311) — named  from  its  supposed  action 
as  a  compressor  of  the  nostrils — is  a  triangular  sheet,  the  base  of  which  is  attached 
to  the  nasal  aponeurosis  above  mentioned. 


DEPRESSOR  ALjE  NASI— DILATATOR  ^ARIS  POSTERIOR      433 

Origin. — The  sides  of  the  nasal  aponeurosis. 

Insertion. — (1)  The  lower  and  front  part  of  the  canine  fossa  of  the  maxilla; 

(2)  part  of  its  fibres  are  continued  into  those  of  adjacent  muscles,  especially  the 
levator  lahii  superioris  alseque  nasi,  and  the  levator  anguli  oris. 

Structure. — Arising  from  the  side  of  the  aponeurosis  in  a  vertical  line  ahout 
half  an  inch  (1-2  cm.)  from  the  ridge  of  the  nose,  the  fibres  of  the  muscular  sheet 
converge  as  they  pass  ]»ackwards,  outwards  and  downAvards  to  a  narrow  band  just 
aljove  and  behind  the  ala  nasi.  Here  they  are  partly  attached  to  the  maxilla,  and 
partly  they  ])ass  into  the  adjacent  muscles. 

Nerve-supply, — The  infraorbital  l)ranch  of  the  upper  division  of  the  facial 
nerve,  which  sends  filaments  to  the  deep  surface  of  the  muscle  near  its  upper  border. 

Action. — (1)  To  depress  slightly  the  cartilaginous  ridge  of  the  nose;  (2)  to 
throw'  into  vertical  wrinkles  the  side  of  the  nose,  as  when  a  bad  smell  is  perceived; 

(3)  to  assist  the  adjacent  muscles  in  dilating  the  nostril  and  drawing  up  parts  of 
the  ui»))er  lip. 

Relations. — Superficially,  the  skin  and  levator  labii  superioris  alaque  nasi; 
deeply,  the  cartilages  of  the  nose. 


3.   DEPRESSOR  AL.E  NASI 

The  depressor  alae  nasi  (fig.  311) — named  from  its  action  uiwn  the  cartilage 
of  the  nostril — is  a  small  triangular  sheet. 

Origin. — The  incisive  fossa  of  the  maxilla. 

Insertion. — (1)  The  lower  and  back  part  of  the  cartilage  of  the  ala  nasi;  (2) 
the  adjacent  part  of  the  lower  border  of  the  cartilaginous  septum  nasi. 

Structure. — Its  muscular  fibres  diverge  upwards  and  outwards  from  their  origin. 

Nerve-supply. — Small  filaments  from  the  buccal  branch  of  the  lower  division 
of  the  facial  nerve,  which  enter  the  muscle  near  its  outer  border. 

Action. — To  draw  downwards  and  inwards  the  alar  cartilage. 

Relations. — Superficially,  the  orbicularis  oris;  deeply,  the  maxilla.  It  is  also 
closely  connected  with  the  fibres  of  the  previous  muscle  and  the  elevators  of  the 
upper  lip. 

4.   LEVATOR  LABII  SUPERIORIS  AL^QUE  NASI 
This  muscle  will  be  described  with  the  Muscles  of  the  Mouth. 


5.  DILATATOR  NARIS  ANTERIOR 

The  dilatator  naris  anterior  (fig.  309) — named  from  its  action  and  position — 
is  a  small  quadrilateral  sheet. 

Origin. — The  lower  edge  of  the  lateral  cartilage  of  the  nose. 

Insertion. — The  deep  surface  of  the  skin  covering  the  ala  nasi. 

Structure. — A  thin  stratum  of  muscle,  which  may  occasionally  be  found  pass- 
ing downwards  upon  the  U]:)])er  part  of  the  alar  cartilage. 

Nerve-supply. — The  infraorbital  ])ranch  of  the  upper  division  of  the  facial 
nerve. 

Action. — To  dilate  the  nostril,  e.g.  in  the  expression  of  anger,  or  in  hard 
breathing. 

Relations. — Superficially,  the  skin  below  and  the  compressor  narium  above; 
deeply,  the  cartilages  of  the  ala. 


6.  DILATATOR  XARIS  POSTERIOR 

The  dilatator  naris  posterior  (fig.  309) — named  from  its  action  and  position 
— is  a  similar  sliect  of  soniewliat  quadrilateral  sha]»e. 

Origin, — (1)  The  edge  of  the  nasal  aperture  of  the  maxilla;  and  (2)  the  outer 
surface  of  the  sesamoid  cartilages  of  the  nose. 
•28 


434  THE  MUSCLES 

Insertion. — Tlie  skin  over  the  posterior  and  lower  part  of  the  alar  cartilage. 

Structure. — A  thin  stratum  of  parallel  muscular  iilircs  running  forwards  and 
downwards. 

Nerve-supply. — The  infraorl)ital  l)ranch  of  the  upper  division  of  the  facial 
nerve. 

Action. — To  dilate  the  nostril. 

Relations. — Superficially,  the  skin  and  levator  labii  superioris  akeque  nasi; 
deeply,  the  sesamoid  cartilages. 


MUSCLES  OF  THE  MOUTH 

The  muscles  of  the  mouth  consist,  first,  of  the  orl)icularis  oris,  which  is  the 
sphincter  surrounding  the  aperture;  and  secondly,  of  the  l)ands  which  radiate  from 
this,  as  a  centre,  to  their  origin  upon  the  adjacent  facial  bones.  These  may  be 
grouped  into  three  sets:  viz.  (1)  the  transverse  series,  Avhich  radiate  transversely. 
This  consists  of  only  one  pair  of  muscles,  tlie  buccinators.  (2)  The  angular  series, 
which  pass  from  above  or  below  to  the  corner  of  the  mouth.  (3)  The  labial  series, 
which  pass  nearly  vertically  either  downwards  or  upwards  to  the  lips,  and  chiefly 
to  their  inner  half. 

A  fourth  series  may  be  added,  Avhich  have  no  special  connection  with  the  mouth, 
viz.  two  nearly  vertical  muscles  close  to  the  middle  line,  which  radiate  from  an 
origin  close  to  the  mouth.  Of  tliese,  one  has  already  been  descrilied,  the  depressor 
alse  nasi;  the  other  arises  from  the  loAver  Jaw,  the  levator  menti. 

The  muscles  miglit  also  be  arranged  according  to  their  stratification,  for  they 
form  two,  and,  in  some  parts,  three  layers  over  the  greater  part  of  this  region. 


1.  ORBICULARIS  ORIS 

The  orbicularis  oris — an  unpaired  muscle,  named  from  its  shape  and  situation 
— is  an  oval  sheet  with  the  long  axis  placed  transversely,  and  its  fibres  arranged 
round  a  transverse  central  aperture.  Like  the  orbicularis  oculi,  the  mviscle  may 
be  divided  into  an  internal  or  labial  portion,  and  an  external  ov  facial.  The  first  part, 
Avhich  is  superficial,  has  no  bony  connection,  except  through  the  medium  of  the 
adjacent  muscles  with  which  it  is  closely  blended.  The  second,  which  is  deep  and 
which  forms  part  of  the  third  layer  of  the  facial  muscles,  has  the  following  small 
attachments  to  bone  and  cartilage. 

Attachments  to  bone  and  cartilage. — (1)  Naso-labial  slips  from  the  back  of 
the  lower  })art  of  the  cartilage  of  the  septum  of  the  nose;  (2)  the  incisive  fossa 
of  the  maxilla  just  above  the  socket  of  the  lateral  incisor  tooth ;  (3)  the  incisive 
fossa  of  the  mandible,  below  the  sockets  of  the  lateral  incisor  and  canine  teeth. 

Structure. — The  orbicularis  oris  consists  of  three  sets  of  fibres,  which  are 
in  their  direction  approximately  transverse,  vertical,  and  sagittal  or  antero- 
posterior. The  transverse  set  form  the  most  conspicuous  part  of  the  muscle; 
they  are  continuous  on  either  side  with  the  fibres  of  the  l)Viccinator,  and  they  con- 
stitute the  greater  part  of  the  fine  smooth  bundles  which  lie  beneath  the  red  skin  of 
the  prolal)ium,  and  are  called  the  labial  portion  of  the  muscle.  The  vertical 
fibres  are  derived  from  the  elevators  and  depressors  of  the  lips,  including  the  zygo- 
matici;  they  form  the  superficial  part  of  the  facial  portion,  and  they  interlace  with 
the  transverse  fil)res.  ]\lany  of  them  pass  round  tlie  corners  of  the  mouth  and 
become  transverse;  those  arising  from  the  maxilla  and  its  vicinity  ]iassing  to  the 
lower  li]),  Avhile  those  from  the  mandil)le  go  to  the  upper.  The  sagittal  or  antero- 
posterior fibres  ])ass  directly  or  somewhat  oldiquely  from  ])efore  backwards 
betwc'i'ii  the  transverse  fil)r('s.  and  unite  the  skin  to  the  mucous  membrane.  They 
are  found  chiefly  in  the  labial  portion  of  the  muscle.  The  two  naso-labinl  slips 
pass  side  by  side  vertically  downwards  to  the  upper  part  of  the  muscle,  their  ])osi- 
tion  being  indicated  upon  the  surface  l)y  two  small  vertical  ridges  which  descend 
from  the  columna  nasi  on  either  side  of  the  median  groove  of  the  upj^er  lip.     The 


ORBICULARIS   ORIS 


435 


flesliy  slips  from  the  maxilla  and  mandible — the  musculi  incisivi,  as  they  are 
called — pass  outwards  and  forwards  to  join  the  deep  surface  of  the  transverse  fibres 
near  the  corners  of  the  mouth. 

Nerve-supply. — The  buccal  and  supramaxillary  branches  of  the  lower  division 
of  tlie  facial,  which  enter  the  facial  part  of  the  muscle  near  its  outer  border. 

Action. — (1)  To  bring  together  tlie  lips  and  to  oppose  all  the  other  mu.scles 
which  converge  upon  the  mouth,  and  tend  to  draw  it  open  in  various  directions. 
It  thus  acts  negatively,  and  prevents  the  expression  of  any  emotion,  as  when  the 
lips  are  pursed  up.     If  the  upper  fibres  alone  act,  the  upper  lip  will  be  drawn 


Fig.  311. — The  Deeper  Layer  of  the  Muscles  of  the  Face  axd  Neck. 


Corrugator 
Bupercilii 


Fyramidalia 

Levator  labii 
superioris 
alaeque  nasi 
Levator  labii 
superioris 
Compressor 
narium 
Levator  anguli 
oris 
Naso-labialis 
Depressor  alae 
nasi 
Orbicularis  oris 

Buccinator 

Depressor 

angull  oris 

Depressor  labii 

inferioris 
Levator  menti 
Mylo-hyoid 

Anterior  belly  of 
digastric 


Temporal 


ZygomaticuB 
major 


Splenius  capitis 

Stylo-hyoid 

Sterno-mastoid 


Scalenus  anticus 


downwards;  if  the  lower,  the  lower  lip  will  be  drawn  upwards.  If  the  fibres  of 
the  labial  portion  contract  strongly,  the  corners  of  the  mouth  are  approximated. 
(2)  To  shoot  out  the  lips:  this  will  chiefly  depend  upon  the  contraction  of  the 
facial  portion  and  the  musculi  incisivi.  (3)'To  press  the  lips  against  the  teeth:  the 
plane  of  the  muscle  being  curved,  with  the  concavity  against  the  arches  formed  by 
the  front  tectli,  its  contraction  will  carry  the  food  backwards  into  the  oral  cavity. 

Relations. — In  front  of  the  lal)ial  portion  is  the  bright  red  skin  of  the  ])rola- 
bium;  and  in  front  of  the  facial  ]iortion  lie  the  angular  and  labial  series  of  muscles, 
together  with  some  suljcutaneous  fat. 


436  THE  MUSCLES 

Upon  the  deep  surface  lies  the  mucous  membrane  of  the  mouth,  separated  from 
the  muscular  fil)res  by  the  mucous  and  small  salivary  glands,  together  -with  the 
superior  and  inferior  coronary  arteries. 


Transverse   ^Muscles   of   the   Mouth 
This  group  comprises  only  the  buccinator, 

BUCCINATOR 

The  buccinator — named  from  its  action,  as  it  is  the  muscle  used  by  the 
trumpeter'  {buccinator) — is  a  somewhat  oval  sheet  of  muscular  fibre,  distinct  in  its 
origin,  but  blending  in  front  with  the  orbicularis  oris.  It  forms  a  part  of  the  third 
stratum  of  the  facial  muscles. 

Origin. — (1)  The  outer  surface  of  the  alveolar  process  of  the  maxilla  above 
the  molar  teeth;  (2)  the  anterior  border  of  the  pterygo-maxillary  ligament,  a 
fil:)rous  band  or  raphe  extending  from  the  hamular  process  of  the  internal  pterygoid 
plate  of  the  sphenoid  bone  to  the  back  of  the  mylo-hyoid  ridge  of  the  mandil)le; 
(3)  the  outer  surface  of  the  alveolar  process  of  the  mandible  below  the  molar 
teeth. 

Insertion. — The  outer  part  of  the  orbicularis  oris. 

Structure. — It  rises  by  fleshy  fibres  which  run  forwards  in  four  sets.  The 
upper  set  pass  directly  into  the  facial  portion  of  the  orbicularis  oris  which  belongs 
to  the  upper  lip;  the  next  pass  downwards  and  forwards  to  that  which  belongs  to 
the  lower  lip;  the  third  upwards  and  forwards,  decussating  with  the  second  set  to 
join  the  lower  part  of  the  orl)icularis  in  the  up])er  lip.  Finally,  a  fourth  set  which 
pass  from  the  mandil^le  to  the  lower  part  of  the  facial  portion  of  the  orl)icularis 
oris  belonging  to  the  lower  Hp. 

Nerve-supply. — The  buccal  branch  of  the  lower  division  of  the  facial,  which 
sends  filaments  into  the  back  part  of  its  outer  surface;  it  is  also  pierced  by  the 
buccal  branch  of  the  inferior  maxillary  division  of  the  fifth  nerve  on  its  way  to 
supply  the  mucous  membrane  lining  the  cheek. 

Action. — (1)  To  draw  outwards  the  corner  of  the  mouth,  widening  it  and 
pressing  the  lips  against  the  teeth;  (2)  to  diminish  the  concavity  of  the  cheek, 
compressing  the  air  contained  in  it,  as  in  using  the  blowpipe  or  playing  the 
cornet;  or  forcing  inwards  the  food  when,  in  mastication,  any  portion  of  it 
has  escaped  into  that  part  of  the  mouth  which  is  external  to  the  bicuspids  and 
molar  teeth. 

Relations. — Superficially,  the  skin,  suljcutaneous  fat,  Stenson's  duct,  the  zygo- 
maticus  major,  risorius,  a  large  mass  of  fat  (the  buccal  fat-pad)  Avhich  separates 
the  buccinator  from  the  masseter,  and  a  layer  of  deejj  fascia  continuous  with  that 
which  covers  the  upper  part  of  the  pharynx;  deeply,  the  mucous  membrane  of  the 
mouth.  The  upper  part  of  the  muscle  is  perforated  by  Stenson's  duct.  The 
buccinator  is  almost  continuous  behind  with  the  superior  constrictor,  from  which 
it  is  only  separated  by  the  tendinous  intersection  of  the  pterygo-maxillary  ligament. 


Angular  Muscles  of  the  ISIouth 

The  angular  series  are  four  in  numl)er:  viz.  the  zygomaticus  major,  levator 
anguli  oris,  risorius,  and  depressor  anguli  oris.  Two  descend  to  the  corner  of  the 
mouth  obli(]uely  from  al)ove,  one  runs  almost  horizontally  forwards,  and  one 
ascends  from  below.  They  })lend  at  the  corner  of  tlie  mouth,  and  form  there  a 
thick  muscular  mass,  l)ehind  which  is  a  depression  filled  up  witli  tlie  fat  covering 
the  buccinator.  In  a  lean  face  tins  depression  is  often  very  conspicuous,  and  in 
some  faces  its  position  is  indicated  by  a  dimple  when  the  zygomaticus  major 
contracts. 


•ZYGOMATICUS  MAJOR— RISORIUS  437 


1.  ZYGOMATICUS  MAJOR 

The  zygomaticus  major — iianictl  from  its  origin  from  the  zygoma  and  its  size 
— is  rihl)on-shaped,  and  belongs  to  the  first  layer  of  the  museles. 

Origin. — The  outer  surface  of  the  malar  bone  near  the  zygomatic  suture. 

Insertion. — The  deep  surface  of  the  skin,  and  the  sul)cutaneous  tissue  at  the 
outer  extremity  of  the  upper  lip,  and  just  external  to  the  commissure  of  the  lips. 

Structure. — Arising  liy  short  tendinous  fibres,  the  muscle  forms  a  fleshy  band 
which  passes  downwards  and  forwards  to  the  meeting-point  of  the  angular  muscles 
at  and  external  to  the  angle  of  the  mouth,  where  it  blends  with  the  orbicularis  oris 
and  the  other  angular  muscles,  its  outermost  fibres  passing  into  the  outer  fibres  of 
the  depressor  anguli  oris. 

Nerve-supply. — The  infraorbital  branch  of  the  upper  division  of  the  facial 
ner\-e,  wliich  enters  the  middle  of  its  deep  surface. 

Action. — To  draw  upwards  and  outwards  the  corners  of  the  mouth,  as  in 
smiling  or  laughter.  When  it  is  strongly  contracted,  it  throws  into  prominence 
the  soft  parts  of  the  cheek  in  front  of  the  malar  l^one,  raises  the  lower  eyelid,  and 
produces  'crow's  feet,'  as  the  wrinkles  are  called  which  radiate  outwards  from 
the  outer  canthus.  "When  both  muscles  act  together,  the  mouth  is  Avidened,  and 
the  upper  lip  raised  so  as  to  shoAV  the  upper  teeth,  in  what  is  called  a  '  broad 
grin.' 

Relations. — Superficially,  the  skin;  deeply,  the  buccinator  and  facial  part  of 
the  orbicularis  oris,  the  facial  and  transverse  facial  arteries,  the  facial  vein,  and 
some  branches  of  the  facial  nerve. 


2.  LEVATOR  ANGULI  ORIS 

The  levator  anguli  oris — named  from  its  action  upon  the  corner  of  the  mouth 
— is  a  triangular  sheet  and  belongs  to  the  second  stratum  of  the  facial  muscles. 

Origin. — The  canine  fossa  of  the  maxilla. 

Insertion. — The  deep  surface  of  the  skin,  and  the  subcutaneous  tissue,  close  to 
the  corner  of  the  mouth. 

Structure. — Arising  muscular  from  its  broad  origin  al)ove  the  canine  and 
bicuspid  teeth,  the  fibres  converge  in  a  downward  and  outward  direction,  and  blend 
with  the  other  angular  muscles  outside  the  corner  of  the  mouth. 

Nerve-supply. — The  infraorbital  branch  of  the  upper  division  of  the  facial  at 
the  outer  i)art  of  the  anterior  surface. 

Action. — To  raise  the  corner  of  the  mouth,  Ijut  at  the  same  time  to  draw  it 
inwards. 

Relations. — Superficially,  the  zygomaticus  minor  and  levator  laliii  superioris, 
the  infraorljital  vessels  and  nerves;  deeply,  the  facial  portion  of  the  orbicularis  oris. 


3.  RISORIUS 

The  risorius — named  from  its  supposed  action  in  laughter — is  flat  and  ribbon- 
shaped,  and  belongs  to  the  superficial  layer  of  muscles,  being  a  part  of  the  platysma 
myoides,  and  often  very  small  and  ill-developed. 

Origin. — The  subcutaneous  tissue  overlying  the  deep  fascia  which  covers  the 
masscter  and  parotid  gland. 

Insertion. — The  sul)cutaneous  and  muscular  tissue  external  to  the  angle  of  the 
mouth. 

Structure. — It.  is  a  band  of  ])arallcl  filnvs  which  runs  transversely  forwards 
from  tlx'  upper  and  posterior  part  of  the  ])latysma  to  the  corner  of  the  mouth. 

Nerve-supply. — The  buccal  1>ranch  of  tlie  lower  division  of  the  facial  nerve 
which  enters  it  from  lieneath. 

Action. — To  widen  the  mouth  by  drawing  its  corner  directly  outwards.  It  is 
not  used  in  the  expression  of  pleasure  like  the  zygomaticus  major.  Init  it  gives  a 


438  THE  MUSCLES 

strained  painful  expression  to  the  features,  sueh  as  is  seen  in  tetanus,  and  ealled 
the  '  risus  sardonicus. ' 

Relations. — Su]>erficially,  the  skin  and  sul)eutaneous  fat;  deeply,  the  masseter 
and  bueeinator,  the  faeial  artery  and  vein,  and  branehes  of  the  facial  nerve. 


4.  DEPRESSOR  ANGULI  ORIS 

The  depressor  anguli  oris — named  from  its  action  upon  the  corner  of  the 

mouth — is  a  triangular  sheet,  and  belongs  to  the  superficial  layer  of  facial  muscles. 

Origin. — The  outer  aspect  of  the  loAver  border  of  the  body  of  the  mandil)le  and 
the  external  oblique  line  below  the  canine,  bicuspid,  and  first  molar  teeth. 

Insertion. — The  subcutaneous  connective  tissue,  and  the  muscular  mass  ex- 
ternal to  the  corner  of  the  mouth. 

Structure. — Its  fibres,  arising  fleshy,  converge  upwards  and  inwards,  and, 
having  diminished  to  a  narrow  band,  join  the  general  muscular  mass  at  the  corner 
of  the  mouth,  some  of  them  being  continued  upwards  into  the  levator  anguli  oris, 
and  the  most  external  into  the  zygomaticus  major. 

The  fibres  which  form  the  inner  border  of  the  muscle  are  often  continued 
downwards  below  the  mandible,  and  form  wdth  those  of  the  other  side  a  l^and, 
partly  muscular  and  partly  fibrous,  which,  lying  beneath  the  platysma  myoides, 
supports  and  compresses  the  sulicutaneous  fat  below  and  behind  the  prominence  of 
the  chin.  When  there  is  much  subcutaneous  fat,  the  absence  of  this  support  gives 
rise  to  a  consideral^le  prominence  behind  this  band,  producing  the  so-called 
'  double  chin. ' 

Nerve-supply. — The  supramandibular  Ijranch  of  the  lower  division  of  the 
facial  nerve,  which  sends  filaments  to  the  back  part  of  its  deep  surface. 

Action. — To  draw  downwards  and  somewhat  outwards  the  angle  of  the  mouth, 
giving  an  expression  of  sorrow  to  the  face,  and  making  the  individual  look  '  down 
in  the  mouth.' 

Relations. — The  skin  superficially;  and  deeply,  the  depressor  labii  inferioris 
and  inferior  coronary  artery. 


Labial  Group  of  Muscles 

The  labial  group  consists  of  three  muscles  which  pass  downwards  from  the 
maxilla,  and  form  a  continuous  sheet  which  might  fairly  be  included  under  one 
name;  and  a  fourth  muscle  which  passes  upwards  from  the  mandible.  All  the 
muscles  are  inserted  into  the  lips,  and  especially  into  that  part  of  them  which  inter- 
venes between  the  middle  line  and  a  point  half  way  between  this  and  the  corner  of 
the  mouth. 

The  upper  set  is  formed  by  the  levator  labii  superioris  ahieque  nasi,  the  levator 
labii  superioris,  and  the  zygomaticus  minor;  the  lower  muscle  is  the  depressor 
labii  inferioris. 


1.   LEVATOR  LABII  SUPERIORIS  AL.EQUE  NASI 

The  levator  labii  superioris  alaeque  nasi — named  from  its  action  as  an 
elevator  of  the  U])i)er  li])  and  the  nostril — is  a  somewliat  triangular  sheet,  bifur- 
cating below  at  the  base  which  corresponds  to  the  insertion  of  the  muscle.  It 
belongs  to  the  superficial  layer  of  facial  muscles. 

Origin.— The  anterior  half  of  the  outer  surface  of  tlie  nasal  process  of  the 
maxilla. 

Insertion. — (1)  The  deep  surface  of  the  skin  Avhich  covers  the  lower  part  of  the 
ala  nasi;  (2)  the  deep  surface  of  the  skin  and  the  general  muscular  mass,  of  the 
inner  half  of  the  u]iper  lip. 

Structure. — Arising  lleshy,  its  fibres  diverge  somewhat  as  they  pass  down- 
wards; they  tlien  decussate  with  those  of  the  orbicularis  oris  close  to  the  prolabium. 


ZYGOMATICUS  MINOR— DEPRESSOR  LAB  11  INFERIORIS        439 

Nerve-supply. — The  iiifraorl)ital  branch  of  the  upper  division  of  the  facial 
nerve,  which  sends  filaments  to  the  outer  part  of  the  deep  surface  of  the  muscle. 

Action. — (1)  To  raise  and  dilate  the  nostril;  (2)  to  raise  the  inner  half  of  the 
u])i>cr  lip. 

Relations. — Superficially,  the  skin  and  orbicularis  palpebrarum;  deeply,  the 
compressor  narium  and  levator  anguli  oris. 


2.  LEVATOR  LABII  SUPERIORIS 

The  levator  labii  superioris — named  from  its  action — is  a  nearly  scjuare  slieet, 
and  it  belongs  to  the  superficial  layer  of  muscles. 

Origin.— The  front  of  the  maxilla  just  below  the  margin  of  the  orbit,  and  from 
the  adjacent  part  of  the  malar  bone. 

Insertion. — The  deep  surface  of  the  skin  and  the  subjacent  muscular  tissue 
near  the  upper  edge  of  the  inner  half  of  the  upper  prolaljium. 

Structure. — Its  fibres,  arising  fleshy,  descend  parallel  to  one  another  and 
almost  vertically  to  their  insertion,  where  they  interlace  with  the  fibres  of  the 
orbicularis  oris.  It  freci[uently  receives  at  its  outer  border  some  bundles  of  fibres 
from  the  orbicularis  palpeln'arum. 

Nerve-supply. — The  infraorbital  branch  of  the  upper  division  of  the  facial 
nerve,  which  sends  filaments  to  the  outer  part  of  its  deep  surface. 

Action. — To  raise  the  inner  half  of  the  upper  lip.  This  muscle,  with  its  two 
fellows,  the  preceding  and  following,  is  especially  used  in  the  expression  of  grief, 
and  to  some  extent  of  anger  also,  as  when  the  lip  is  raised  and  somewhat  everted 
so  as  to  show  the  canine  tooth.  In  crying,  the  action  of  these  muscles  is  strongly 
displayed,  for  when  the  eyes  are  closed  by  the  orbiculares  palpebrarum,  at  the  same 
time  the  mouth  is  made  square  by  the  elevation  of  the  inner  half  of  the  lip,  while 
the  outer  half  is  drawn  down  by  the  depressor  anguli  oris. 

Relations. — Superficially,  the  skin  and  orbicularis  palpebrarum;  deeply,  the 
levator  anguli  oris,  the  infraorbital  vessels  and  nerve. 


3.  ZYGOMATICUS  MINOR 

The  zygomaticus  minor — named  from  its  association  with  the  zygomaticus 
major  and  its  smaller  size — is  a  small  riljbon-shaped  band,  often  absent,  and 
belonging  to  the  superficial  layer  of  facial  muscles. 

Origin. — The  lower  part  of  the  front  of  the  malar  bone  close  to  its  junction 
with  the  maxilla. 

Insertion. — The  deep  surface  of  the  skin  and  the  subjacent  muscular  tissue  at 
a  point  upon  the  upper  border  of  the  prolabium  of  the  upper  lip  about  midway 
between  tlie  middle  line  and  the  outer  corner  of  the  mouth. 

Structure. — Arising  fleshy,  the  small  band  of  parallel  filu-es  which  is  upon  its 
inner  margin  closely  connected  Avith  the  preceding  muscle,  passes  downwards  and 
inwards  to  its  insertion,  which  interlaces  with  the  fil:)res  of  the  orbicularis  oris. 

Nerve-supply. — The  infraorbital  branch  of  the  upper  division  of  the  facial 
nerve,  which  sends  fih\ments  to  the  deep  surface  of  the  muscle. 

Action. — To  raise  and  somewhat  evert  the  part  of  the  upper  lip  to  which  it  is 
attached. 

Relations. — Superficially,  the  skin  and  orbicularis  palpebrarum;  deeply,  the 
levator  anguli  oris,  facial  portion  of  the  orbicularis  oris,  and  the  infraorljital  branch 
of  the  facial  nerve. 

4.    DEPRESSOR  LABII  INFERIORIS 

The  depressor  labii  inferioris,  or  quadratus  menti — named  from  its  action, 
or  shape,  and  its  connection  with  the  lower  lip  and  chin  (rnentum) — is  a  nearly 
square  sheet,  and  belongs  to  the  second  layer  of  the  facial  muscles. 

Origin.— The  outer  aspect  of  the  lower  border  of  the  body  of  the  mandible 
below  the  canine  and  bicuspid  teeth. 


440  THE  MUSCLES 

Insertion. — The  deep  surface  of  the  skin  and  the  subjacent  muscular  mass 
along  the  lower  i.^d^e  of  the  prolabium  of  the  lower  lij). 

Structure. — It  consists  of  parallel  muscular  fibres,  many  of  them  continuous 
with  tliose  of  the  platysma  myoides,  which  pass  u])wardsand  inwards  to  interlace 
with  the  fibres  of  the  orbicularis  oris  along  the  line  aljove  mentioned.  The  inner 
margins  of  the  muscles  of  the  two  sides  meet  above  in  the  middle  line. 

Nerve-supply. — The  supramandilnilar  branch  of  the  lower  division  of  the 
facial  nerve,  which  sends  filaments  to  its  deep  surface  near  its  outer  Ijorder. 

Action. — To  draw  down  and  somewhat  evert  the  lower  lip. 

Relations. — Superficially,  the  skin  and  the  depressor  anguli  oris;  deeply,  the 
facial  portion  of  the  orbicularis  oris,  the  mental  vessels,  and  nerve. 


Muscles   eadiating    from   the   ISIouth 

The  two  muscles  which  radiate  from  the  mouth  are  the  depressor  alse  nasi  and 
the  levator  menti. 

1.    DEPRESSOR  AL^  NASI 

The  depressor  alee  nasi  has  lieen  described  with  the  muscles  of  the  nose. 


2.    LEVATOR   MEXTI 

The  levator  menti,  or  levator  labii  inferioris — named  from  its  action — is  a 
short,  thick,  and  somewhat  fan-shaped  muscle,  belonging  to  the  second  layer. 

Origin. — The  incisive  fossa  of  the  mandible,  below  and  a  little  internal  to  the 
attachment  of  the  incisivus  inferior  of  the  orbicularis  oris. 

Insertion. — The  subcutaneous  tissue  just  above  the  point  of  the  chin. 

Structure. — Arising  fleshy,  its  fibres  diverge  slightly  as  they  pass  downwards 
and  inwards  to  meet  in  the  middle  line  Avith  those  of  the  opposite  side  just  below 
a  pellet  of  fat  which  lies  beneath  the  skin  at  a  short  distance  above  the  point  of 
the  chin. 

Nerve-supply. — The  supramandibular  l^raneh  of  the  lower  division  of  the 
facial  nerve,  which  terminates  in  this  muscle. 

Action. — To  draw  upwards  the  skin  covering  the  prominence  of  the  chin,  and 
to  elevate  and  shoot  out  the  lower  lip.  It  has  been  sometimes  called  the  mnsculus 
superbus,  from  the  haughty  and  contemptuous  expression  which  it  produces  when 
it  acts  at  the  same  time  with  the  depressor  anguli  oris.  A  slighter  contraction, 
however,  gives  the  mouth  an  expression  of  firmness  and  decision. 

Relations. — Superficially,  the  mucous  membrane  of  the  mouth  and  the  facial 
portion  of  the  orl)icularis  oris  al)ove,  the  subcutaneous  fat  below;  deeply,  the 
mandible. 


MUSCLES  OF  MASTICATION 

The  muscles  of  mastication  form  an  independent  group,  four  in  number, 
occupying  the  l)ack  part  of  the  side  of  the  face,  and  the  temporal  and  zygomatic 
fossae,  and  consisting  of  the  masseter,  the  temporal,  with  the  external  and  internal 
pterygoid  muscles.  The  temporal  muscle  is  covered  by  a  strong  membrane,  the 
temporal  fascia,  which,  arising  from  the  temporal  ridge,  is  attached  below  to  the 
upper  border  of  tlie  zygoma,  after  first  dividing  into  two  laminte  which  go  to  the 
outer  and  inner  aspects  of  this  border,  and  contain  between  them  a  small  (luantity 
of  fat.  From  the  zygoma  downwards,  the  masseteric  fascia  is  continued  to  the 
])osterior  and  inferior  borders  of  the  ramus  of  the  inandi])lc.  enveloping  the  mas- 
seter muscle.  Closely  connected  with  this  is  the  parotid  fascia  which  envelops 
the  parotid  gland,  extending  l)ackwards  from  the  masseteric  fascia  to  that  part  of 
the  deep  cervical  fascia  which  covers  the   upper  portion  of   the   sterno-mastoid 


MASSETER—THE   TEMPORAL   MUSCLE  441 

muscle;  covering  also  the  deep  surface  of  the  gland,  and  giving  off  a  process  called 
the  stylo-maxillari/  ligament,  which,  running  from  the  styloid  process  to  the  angle 
of  the  mandible,  separates  the  parotid  and  submaxillary  glands. 


1.  MASSETER 

The  masseter  (fig.  311) — named  from  the  Greek  word  /j.a(jd()tj.m,  to  chew — is  a 
strong  quadrate  sheet,  consisting  of  two  layers. 

Origin. — The  superficial  layer,  from  the  lower  border  of  the  malar  bone,  and  the 
lower  border  of  the  anterior  two-thirds  of  the  zygomatic  arch;  the  deep  layer,  from 
the  lower  border  of  the  posterior  third  of  the  zygomatic  arch,  and  the  whole  of  its 
inner  surface. 

Insertion. — The  superficial  layer,  into  the  lower  lialf  of  the  outer  surface  of  the 
ranuis  of  the  mandible;  the  deep  layer,  partly  with  the  superficial  layer,  and  jwirtly 
into  the  upi)er  half  of  the  outer  surface  of  the  ramus  of  the  mandible. 

Structure. — The  origin  and  insertion  are  by  tendinous  bands  intermingled  in 
multipenniform  fashion  with  fleshy  fibres.  The  fibres  of  the  superficial  sheet  are 
directed  obliquely  downwards  and  backwards;  those  of  the  deep  sheet  almost 
vertically  downwards,  and  they  are  much  shorter  than  the  superficial  fibres.  The 
two  sheets  blend  closely  in  front,  but  are  separate  behind,  where  the  muscle  forms 
a  sort  of  pocket  closed  above  at  the  origin  and  below  at  the  insertion,  as  Avell  as  in 
front,  but  ojien  behind. 

Nerve-supply. — The  masseteric  branch  of  the  motor  portion  of  the  mandilmlar 
division  of  the  fifth  nerve,  which  enters  the  deep  surface  of  the  muscle  just  l^elow 
the  zygoma. 

Action. — To  close  the  jaw,  and  by  its  superficial  layer  to  draw  it  slightly 
forwards.  In  closing  the  jaw  it  acts  with  less  mechanical  disadvantage  than  is 
usual  witb  muscles.  When  the  pressure  to  be  overcome  is  exerted  upon  the  ))ack 
teeth,  the  arm  of  the  lever  upon  Avhich  the  power  acts  is  almost  as  long  as  that 
which  intervenes  between  these  teeth  and  the  fulcrum.  This  fulcrum  is  not  at  the 
temporo-mandilmlar  joint,  but  at  a  j^oint  below  the  neck  of  the  mandible,  cor- 
responding very  nearly  to  the  lower  attachment  of  the  internal  lateral  ligament. 
Moreover,  the  resultant  force  of  the  muscle,  acting  as  it  does  upwards  and  forwards, 
is  perpendicular  to  the  lever,  which  may  be  roughly  described  as  a  bar  extending 
downwards  and  forwards  from  the  neck  of  the  mandible  to  the  point  of  the  chin. 

Relations. — Superficially,  the  parotid  gland  and  its  duct,  the  platysma 
myoides,  the  risorius  and  the  masseteric  fascia,  the  transverse  facial  vessels,  the 
facial  vein,  the  upper  and  lower  divisions  of  the  facial  nerve;  deeply,  the  buccal 
fat-pad  which  separates  it  from  the  buccinator  and  a  small  part  of  the  temporal 
muscle. 

2.  THE  TEMPORAL  MUSCLE 

The  temporal  muscle — named  from  its  attachment  to  the  temple  (  =  (empus) 
— is  a  thick,  somewhat  triangular  sheet;  more  correctly  it  may  be  described  as 
forming  the  quadrant  of  a  circle. 

Origin. — (1)  The  whole  of  the  temporal  fossa,  from  the  temporal  to  the  ptery- 
g<Md  ridge,  with  the  exception  of  a  small  part  close  to  the  outer  wall  of  the  orljit. 
which  is  occu])ied  by  fat;  (2)  the  inner  surface  of  the  temporal  fascia  down  to  its 
lower  attachment  to  the  zygomatic  process,  from  the  inner  surface  of  which  some 
of  its  fibres  also  sometimes  arise. 

Insertion. — The  point,  posterior  border,  and  the  whole  of  the  inner  surface  of 
the  coronoid  process  of  the  mandible,  down  to  the  last  molar  tooth. 

Structure. — The  bones  of  the  temjioral  fossa  and  tlie  temporal  fascia  form  a 
pouch,  open  downwards,  from  which  the  fleshy  fibres  of  the  muscle  converge, 
the  middle  fibres  running  downwards,  the  anterior  downwards  and  backwards,  the 
l)osterior  almost  transversely  forwards,  to  be  inserted  beloAV  upon  both  faces  of  a 
flat  tendon  which,  becoming  free  of  flesh  on  the  outer  surface  first,  embraces  the 
point  and  borders  of  the  coronoid  process. 


442 


THE  MUSCLES 


Nerve-supply. — The  two  or  three  deep  temporal  branches  of  the  motor  portion 
of  the  niandibular  division  of  the  fifth  nerve,  -which  enter  the  lower  part  of  its  deep 
surface. 

Action. — To  close  tlie  jaw:  its  posterior  tilnvs  will  also  draw  it  backwards  after 
the  other  muscles  have  protruded  it.  This  muscle,  like  the  masseter,  has  to  con- 
tend with  very  little  mechanical  disadvantage,  power  being  of  more  importance  in 
mastication  than  speed. 

Fig.  312.— The  Temporal  Muscle. 


Temporal 


Relations. — Superficially,  the  temporal  fascia  which  separates  it  from  some  of 
the  auricular  muscles,  the  sides  of  the  epicranial  aponeurosis,  the  auriculo-temporal 
nerve,  and  the  upper  branches  of  the  facial  nerve;  the  zygoma  and  a  small  part  of 
the  masseter.     Deeply,  the  temporal  fossa,  and  the  external  pterygoid  muscle. 

At  its  posterior  border  it  is  crossed  by  the  masseteric  nerve  and  vessels. 


3.  PTERYGOIDEUS  EXTERXUS 

The  pterygoideus  externus — named  from  its  attachment  to  the  pterygoid 
process  of  tlie  sphenoid  bone,  and  its  relation  to  the  companion  muscle — consists  of 
two  thick  triangular  sheets,  the  one  lying  in  a  horizontal,  and  the  other  in  a  vertical 
plane. 

Origin. — Upper  head  :  the  under  surface  of  the  great  wing  of  the  sphenoid 
bone,  internal  to  the  jitcrvgoid  ridge,  and  external  to  the  foramen  ovale  and 
foramen  spinosum.  Lower  head  :  All  the  outer  surface  of  the  external  i:)tervgoid 
plate. 

Insertion. — Upper  head  :  (1)  The  front  of  the  interarticular  fibro-cartilage  of 
the  temporo-mandibular  joint;  (2)  the  adjacent  portion  of  the  capsular  ligament; 
(8 )  the  upper  part  of  the  front  of  the  neck  of  the  condyle  of  the  mandible.  Lower 
head :  The  pit  in  the  front  of  the  neck  of  the  condyle. 

Structure. — Arising  by  fleshy  fibres,  which  are  closely  connected  at  the  ptery- 
goid ridge  with  part  of  the  temporal  muscle,  the  upper  head  forms  a  fan-shaped 
sheet  and  passes  backwards  and  slightly  outwards  to  its  insertion,  which  is  by 
short  tendinous  fibres  blending  below  with  those  of  the  lower  head.     The  lower 


PTERYG OIDEUS  EXTERXUS 


443 


and  much  stronger  head  is  at  first  separated  from  the  upper  by  a  small  chink, 
which  may  give  passage  to  the  internal  maxillary  vessels.  It  arises  fleshy,  con- 
verges backwards,  outwards,  and  somewhat  upwards,  and  is  inserted  by  short 
tendinous  fibres. 

Nerve-supply. — Th{»  external  pterygoid  branch  of  the  motor  portion  of  the 
mandibular  division  of  the  fifth  nerve,  which  divides  into  filaments  entering  its 
deep  surface. 

Action. — (1)  To  draw  forwards  the  ramus  of  the  mandible,  and  the  inter- 
articular  fibro-cartilage;  (2)  to  draw  them  inwards.  The  combination  of  these 
two  movements  produces  the  oblique  movement  of  the  lower  molar  teeth  of  one 
side  forwards  and  inwards  with  respect  to  the  upper  molars  which  are  their 
opponents.  It  should  be  observed  also  that  this  inward  movement  of  one  side  is 
the  action  by  which  the  ramus  of  the  opposite  side  is  moved  outwards.  (3)  To 
assist  in  opening  the  mouth  by  depression  of  the  lower  jaw.  As  the  transverse 
axis  of  this  movement  passes  through  the  mandible  at  two  points  situated  below 


Fig.  313. — The  Pterygoid  Muscles. 


|'4    'j  '       Interartioular  fibro-cartilage 


External  pterygoid 


Internal  pterygoid 


the  necks  of  the  rami,  it  follows  that  a  forward  movement  of  the  condyles  and 
necks  will  assist  in  the  backward  movement  of  the  angles  and  body  which  accom- 
panies the  depression  of  the  mandible. 

Relations. — Superficially,  the  anterior  fibres  of  the  internal  pterygoid,  the 
temporal  muscle,  and,  at  a  little  distance,  a  small  part  of  the  masseter;  deeply,  the 
internal  pterygoid  muscle,  the  internal  maxillary  vessels  (unless,  as  sometimes, 
they  pass  across  the  outer  surface  of  the  lower  head),  the  middle  meningeal  and 
inferior  dental  vessels,  with  the  masseteric  and  posterior  deep  temporal  nerves 
passing  behind  or  through  the  attachment  of  the  upper  head;  the  buccal  and  ante- 
rior deep  temporal  ners'es  running  V)etweeii  the  two  heads;  the  lingual  gustatory 
and  inferior  dental  nerves  beneath  the  lower  head. 

Variations. — Muscular  fibres  are  froqueiitlj'  found  upon  the  deep  surface  of  the  external 
pterygoid,  running  from  the  back  of  the  external  pterj'goid  plate  to  the  spine  of  the  sphenoid, 
or  the  vaginal  process  of  the  temporal  bone. 


444  THE  MUSCLES 


4.  PTERYGOIDEUS  INTER NUS 

The  pterygoideus  internus — named  from  its  origin  and  relative  position — is  a 
thick  ([iiadrilateral  sheet. 

Origin. — ( 1)  The  whole  of  the  inner  surface  of  the  external  pterygoid  plate  and 
the  adjacent  part  of  the  tuberosity  of  the  palate  bone.  (2)  A  small  triangular  area, 
consisting  of  the  outer  surface  of  the  tuberosity  of  the  palate  Ijone,  and  a  small 
strip  in  front  belonging  to  the  maxilla. 

Insertion. — The  lower  half  of  the  internal  surface  of  the  ramus  of  the  man- 
dible, including  the  adjacent  parts  of  its  lower  and  posterior  borders,  and  extending 
as  high  as  the  mylo-hyoid  ridge  and  inferior  dental  canal. 

Structure. — Arising  fleshy,  the  fibres  run  |)arallel  to  one  another,  downwards, 
backwards,  and  outwards,  to  be  inserted  partly  into  the  mandible,  and  partly  in 
multipenniform  fashion,  like  those  of  the  masseter,  into  the  tips  and  sides  of 
fibrous  septa,  which,  passing  ui)Avards  from  the  periosteum  of  the  mandible, 
separate  the  muscular  bundles  from  one  another. 

Nerve-supply. — The  internal  jDlerygoid  branch  of  the  motor  portion  of  the 
mandil)ular  division  of  the  fifth  nerve,  which  enters  the  deep  surface  near  its  poste- 
rior border. 

Action. —  (1)  To  close  the  jaw.  The  same  remarks  which  were  made  with 
respect  to  the  very  small  loss  of  mechanical  advantage  in  the  masseter  muscle 
apply  to  this  muscle.  (2)  When  closed  it  will  draw  the  jaw  forwards;  and  also 
(3)  it  will  help  the  external  pterygoid  in  drawing  the  ramus  of  its  own  side  towards 
the  middle  line. 

Relations. — Superficially,  the  external  pterygoid  muscle,  the  internal  lateral 
ligament,  the  internal  maxillary  vessels,  the  inferior  dental  and  lingual  nerves; 
deeply,  the  tensor  palati  and  superior  constrictor  of  the  pharynx,  the  stylo-hyoid 
muscle  and  the  posterior  belly  of  the  digastric,  the  submaxillary  gland. 


THE  MUSCLES  AXD  FASCI.E  OF  THE  FRONT 
OF  THE  NECK 

The  platysma  myoides  has  been  already  described  (page  426)  with  the  muscles 
of  expression. 

The  muscles  of  the  neck  Avhich  lie  beneath  it  are  surrounded  by  a  layer  of  deep 
fascia,  called  the  cervical  fascia.  This  is  a  strong  tubular  membrane,  attached 
above  to  the  lower  l)order  of  the  mandible,  the  parotid  fascia,  the  upper  part  of 
the  mastoid  process,  and  the  superior  nuchal  line.  At  the  back  of  the  neck  it  is 
continuous  with  the  deep  fascia  which  gives  a  thin  investment  to  the  trapezius 
muscle.  In  front,  it  is  attached  to  the  lower  l:)order  of  the  body  and  great  cornu  of 
the  hyoid  bone.  Below,  it  ends  upon  the  front  surface  of  the  presternum  and  the 
clavicle.  The  deep  layer  of  the  cervical  fascia  separates  from  it  just  below  the 
hyoid  bone,  and  runs  downwards  in  close  proximity  to  the  sterno-hyoid  muscles 
and  the  other  depressors  of  the  hyoid  bone,  to  the  upper  part  of  the  posterior  sur- 
face of  the  sternum,  and  the  posterior  surface  of  the  clavicle.  Laterally,  it  blends 
Avith  and  completes  the  sheath  of  the  sterno-mastoid  muscle,  which  is  ]iartly  formed 
by  the  superficial  layer  of  the  cervical  fascia;  it  also  binds  down  the  })osterior  belly 
of  the  omo-hyoid  to  the  clavicle  and  first  rib.  Below  its  attachment  to  the  sternum 
and  clavicle  it  is  continued  downwards  in  front  of  the  trachea  and  great  vessels  at 
the  root  of  the  neck  into  the  superior  mediastinum,  and  it  finally  joins  the  peri- 
cardium. Behind,  it  gives  an  investment  to  the  depressors  of  the  hyoid  bone. 
Between  this  deep  layer  of  the  cervical  fascia  and  the  superficial  layer  is  a  small 
space  containing  a  part  of  the  course  of  the  anterior  jugular  vein,  a  lymphatic 
gland,  some  fat  and  loose  connective  tissue. 

A  still  deeper  fibrous  layer,  the  prevertebral  fascia,  stretches  across  the  neck 
and  divides  the  cvlindrical  tub(>  formed  l)y  the  cervical  fascia  into  a  posterior  and 
anterior  compartment.     Its  surfaces  are  directed  forwards  and  liackwards.      Behind, 


STERXO-CLEIDO-MASTOID  445 

it  rests  in  the  middle  line  \\\^(n^.  the  ligaments  covering  the  front  of  the  bodies  of 
the  cervical  vertebrse.  Laterally,  it  covers  in  the  prevertebral  muscles,  and  is 
attached  to  the  deep  surface  of  the  superjicial  layer  of  the  cervical  fascia  between  the 
sterno-mastoid  and  trapezius  muscles.   • 

In  the  c()m])artment  formed  l)etween  the  deep  layer  of  the  cervical  fascia  as  it 
invests  the  depressors  of  the  hyoid  ])one,  and  the  preverteljral  fascia,  processes  are 
given  off  which  form  the  sheath  of  the  great  vessels  of  the  neck,  and  invest  the 
thyroid  gland,  the  trachea,  and  pharynx. 

"^  The  muscles  of  the  front  of  the  neck  may  be  divided  into  three  groups:  the 
first  group  consisting  of  one  muscle  which  ascends  from  the  sternum  and  clavicle 
to  the  head,  the  sterno-cleido-mastoideus;  the  second,  of  those  which  ascend  from 
the  sternum,  clavicle,  and  shoulder-blade  to  the  hyoid  bone  and  thyroid  cartilage; 
the  third,  of  those  which  are  attached  to  the  hyoid  bone  below,  and  the  skull  and 
lower  jaw  above. 


First  Group 

STERXO-CLEIDO-MASTOID 

The  sterno-cleido-mastoid,  or  sterno-mastoid  muscle — named  from  its 
attachments  {y.ht^=:a  key,  being  the  equivalent  of  clavicle) — is  a  strong  ribbon- 
shaped  band,  l)ifurcated  below,  and  somewhat  constricted  in  its  middle  third. 

Origin. — Sternal  head :  the  front  of  the  manubrium  (or  presternum)  Ix'tAveen 
the  notches,  th(^  middle  line,  and  for  the  clavicle  and  first  rilx  Clavicular  head : 
The  upper  part  of  the  anterior  surface  of  the  inner  third  of  the  clavicle. 

Insertion. — (1)  Along  the  anterior  border  and  the  outer  surface  of  the  mastoid 
process  of  the  temporal  bone;  (2)  the  outer  half  of  the  superior  nuchal  line  of  the 
occipital  bone. 

Structure. — The  sternal  head  is  a  rounded  but  flat  tendon;  the  clavicular  is 
partly  fleshy  and  partly  tendinous.  After  a  course  of  about  an  inch  (2-5  cm.),  the 
sternal  head  expands  into  a  flat  muscle,  which  conceals  the  greater  part  of  the 
clavicular  portion,  and,  passing  upwards,  outwards,  and  backwards,  is  spread  over 
the  whole  line  of  the  upper  attachment.  Frequently  it  is  so  separate  from  the 
clavicular  head,  that  they  might  very  fairly  l)e  considered  to  form  two  muscles. 
The  clavicular  head  soon  becomes  entirely  fleshy  and  ascends  more  directly.  At 
first  it  is  separated  by  a  small  interval  from  the  sternal  head,  corresponding  to  a 
part  of  the  sterno-cla\dcular  joint,  from  which  it  sometimes  receives  a  few  fibres  of 
origin;  when  they  have  joined,  it  passes  beneath  the  sternal  head  to  its  insertion, 
which  is  chiefly  the  lower  part  of  the  outer  surface  of  the  mastoid  process.  The 
whole  insertion  in  front  is  composed  of  short  tendinous  fil)res,  and  behind  of 
a  thin  aponeurosis.  As  the  w'hole  muscle  has  a  ver}-  wide  range  of  action, 
nearly  the  whole  length  of  its  fibres  is  fleshy.  The  sternal  head  is  a  little 
longer  than  the  other,  but  has  little  if  any  more  range  of  movement.  Hence  it 
is  tendinous. 

Nerve-supply. — (1)  The  spinal  accessory  nerve,  which,  while  traversing  the 
deep  surface  of  the  muscle  at  the  junction  of  its  upper  and  middle  thirds,  sends 
filaments  to  it;  (2)  the  cervical  plexus  through  the  anterior  primary  branches 
of  the  second  and  third  cervical  nerves,  which  enter  the  upper  part  of  its  deep 
surface. 

Action. — (1)  To  flex  laterally  the  head  and  neck,  so  as  to  draw  the  side  of  the 
head  towards  the  shoulder.  (2)  To  rotate  the  face  towards  the  oi)posite  side.  Of 
the  two  parts  of  the  muscle,  the  cleido-mastoid  portion  is  more  concerned  in  lateral 
flexion,  the  sterno-mastoid  in  rotation.  The  combination  of  all  these  movements 
may  be  very  well  seen  in  a  case  of  wry-neck,  which  results  from  the  permanent 
contraction  of  this  muscle.  (3)  "When  both  muscles  act,  to  flex  the  head  and  neck 
upon  the  thorax,  at  the  same  time  raising  slightly  the  chin,  which  is  therefore 
carried  horizontally  forwards.  (4)  To  raise  the  sternum  and  inner  end  of  the 
clavicle.  This  action  may  sometimes  be  seen  in  patients  with  paralysis  of  all  the 
parts  beneath  the  cervical  region,   when  the  only  nerves  available  for  respiratory 


446 


THE  MUSCLES 


movements  are  tlie  phrenic  and  those  which  sn})])ly  certain  of  the  muscles  of  the 
neck.  (5)  If  the  head  be  much  thrown  ])ack,  the  two  sterno-mastoids  may  be 
used  to  increase  the  extension. 

Relations. — Superficially,  the  deep  cervical  fascia  and  integuments,  the  pla- 
tysma  myoides,  external  jugular  vein,  and  many  of  the  superficial  branches  of 
the  een'ical  plexus,  and  the  glandula?  concatenatae;  deeply,  the  rectus  capitis  anticus 
major,  omo-hyoid,  sterno-hyoid  and  sterno-thyroid,  the  posterior  belly  of  the 
digastric,  the  splenius  capitis,  levator  anguli  scapulae,  and  three  scalene  muscles; 
the  common,  external,  and  internal  carotid  and  subclavian  arteries,  with  several 


Fig.  314. — Axtekior  and  Lateral  Cervical  Muscles. 


Raphe  of  mylo 
hyoid 


Stylo-hyoid 

Posterior  belly  of  digastric 

Splenius  capitis 

Sterno-mastoid 

Levator  anguli  scapulas 


Scalenus  mediua 

Trapezius 


Scalenus  posticus 


I'/V 

//'     Posterior  belly  of 
omo-hyoid 


\^^^^^^VX^\^^>U\^:^^^'^ 


branches  of  the  external  carotid,  the  internal  jugular,  facial,  thyroid,  anterior 
jugular,  and  other  veins;  the  spinal  accessory  and  hypoglossal  nerves,  the  cervical 
and  upper  part  of  the  l^rachial  plexuses  with  many  of  their  branches,  the  parotid 
gland,  the  lateral  lobe  of  the  thyroid  gland,  and  numerous  deep  cervical  lymijhatic 
glands. 

Variations. — The  clavicular  origin  may  extend  farther  outwards  ujxm  the  colhir  bone.  Be- 
sides its  insertion  into  the  mastoid  process,  this  head  may  have  an  attachment  to  the  superior 
nuchal  line,  called  the  cleldo-occipital.  An  extension  of  the  sternal  head  has  been  observed 
arising  from  the  co.stal  cartilages  as  low  as  that  of  the  fifth  rib.  Slips  sometimes  pass  from  the 
upper  j)art  of  the  muscle  to  the  angle  of  the  jaw,  the  pharynx,  the  auricle,  or  the  ui)per  attach- 
ment of  the  trapezius. 


STERNO-HYOJD—OMO-HYOID  447 


THE  IXFRA-HYOID  MUSCLES 

The  infra-hyoid  muscles  form  a  sroup  of  four  long  flat  muscles,  arranged  in  two 
layers,  and  enveloped  h\  the  deep  layer  of  the  cervical  fascia. 


Superficial  Layer 

This  consists  of  two  muscles — the  sterno-hyoid  and  omo-hyoid. 

1.  STERXO-HYOID 

The  sterno-hyoid  (figs.  301  and  ol4j — named  from  its  two  attachments — is 
long  and  ribbon-sliaped. 

Origin, — (I)  The  back  of  the  manubrium  (presternum)  just  internal  to  the 
notches  for  the  clavicle  and  first  rib;  (2)  the  l)ack  of  the  posterior  sterno-clavicular 
ligament;  (8)  the  back  of  the  inner  end  of  the  clavicle  external  to  the  facet  for  the 
first  costal  cartilage. 

Insertion. — The  lower  border  of  the  body  of  the  hyoid  bone,  close  to  the 
middle  line. 

Structure. — It  arises  fleshy,  and  forms  a  band  of  parallel  fibres,  which 
approach  the  middle  line  as  they  ascend,  and  are  inserted  by  a  short  tendon. 

Nerve-supply. — From  the  first  three  cervical  nerves  through  the  descendens 
and  communicantes  hypoglossi,  which  send  filaments  to  its  deep  surface  near  its 
upper  end. 

Action. — To  draw  down  the  body  of  the  hyoid  lione,  e.g.  after  it  has  been 
raised  in  swallowing;  also  to  fix  it  when  the  muscles  which  pass  upwards  from  it 
are  depressing  the  tongue,  as  in  suction. 

Relations. — Superficially,  the  deep  cerv'ical  fascia,  sterno-mastoicl,  sterno- 
clavicular joint,  anterior  jugular  vein;  deeply,  the  sterno-thyroid,  crico-thyroid, 
thyroid  and  cricoid  cartilages,  the  trachea,  thyroid  isthmus,  and  the  inferior  thyroid 
vein. 

Variations. — The  sterno-hyoid  may  arise  from  the  clavicle  alone,  and  occasionally  even  from 
the  middle  of  that  bone.  It  may  be  absent  or  double.  A  tendinous  intersection  sometimes 
crosses  it. 

2.  OMO-HYOID 

The  omo-hyoid  (a»,ao?  =z  shoulder) — named  from  its  attachment  to  the  shoulder- 
blade  and  the  hyoid  bone — is  ribbon-shaped  with  a  tendinous  constriction  in  the 
middle  which  di\4des  it  into  two  fleshy  bellies. 

Origin. — (1)  The  upper  border  of  the  scapula  for  about  an  inch  (2"5  cm.) 
behind  the  suprascapular  notch;  (2)  occasionally,  the  upper  l)order  of  the  trans- 
verse ligament  which  crosses  the  notch. 

Insertion. — The  lower  border  of  the  body  of  the  hyoid  bone  just  external  to 
the  preceding  muscle,  which  it  also  slightly  overlaps. 

Structure. — Arising  fleshy  and  broad,  the  muscle  contracts  slightly  as  it  passes 
forwards,  and  a  little  upwards,  across  the  posterior  triangle  of  the  neck  above  the 
clavicle.  Beneath  the  sterno-mastoid,  and  over  the  great  vessels  of  the  neck,  it 
becomes  tendinous  for  a  short  distance;  and  then,  changing  its  direction,  it  again 
expands  to  a  fleshy  band  which  runs  ujjwards  and  slightly  forwards  and  inwards 
to  its  insertion,  which  is  by  short  tendinous,  intermingled  with  fleshy,  fibres.  An 
ol)tuse  angle  is  formed  between  the  two  bellies,  the  lower  ])ortion  of  the  muscle 
and  its  tendon  being  held  down  by  a  strong  process  of  the  deeji  layer  of  the 
cervical  fascia,  which,  forming  a  loop  around  them,  jjasses  downwards  to  be  attached 
to  the  posterior  surface  of  the  clavicle  and  to  the  first  rib. 

Nerve-supply. — The  anterior  belly  is  supplied  by  a  l)ranch  froin  the  descendens 
hypoglossi,  which  enters  the  l)ack  of  its  deep  surface,  while  the  posterior  receives 


448  THE  MUSCLES 

a  l)ranch  from  the  loop  of  comnumication  between  this  nerve  and  the  coniniuni- 
cantes  liypoglost^i  which  enters  the  deej)  surface  of  the  muscle  close  to  its  junction 
with  the  tendon. 

Action. — (1)  To  draw  down  the  hyoid  bone;  (2)  very  sliiihtly  to  help  in  raising 
the  scapula;  (3)  to  make  tense  the  lower  part  of  the  cervical  fascia.  In  this  way 
it  assists  the  platysma  myoides  in  diminishing  the  inward  suction  of  the  soft 
parts,  which  tends  to  compress  the  great  vessels  and  the  apices  of  the  lungs  during 
prolonged  inspiratory  efforts.  The  part  of  the  muscle  between  the  sterno-mastoid 
and  the  carotid  sheath,  being  tendinous,  Avill  not  vary  in  thickness,  otherwise 
during  contraction  it  might  tend  to  obstruct  the  vessels  beneath. 

Relations. — Superhcially,  the  deep  cervical  fascia,  sterno-mastoid,  clavicle, 
sul^clavius  and  trapezius,  the  external  jugular  vein,  and  the  descending  branches 
of  the  superficial  cervical  plexus;  deeply,  the  thyro-hyoid,  sterno-thyroid,  scaleni, 
and  the  hrst  digitation  of  the  serratus  magnus,  the  sheath  of  the  common  carotid 
artery  and  internal  jugular  vein,  the  upper  part  of  the  brachial  plexus,  often  the 
third  part  of  the  subclavian  artery  with  the  trans versalis  colli  and  suprascapular 
vessels  and  the  suprascapular  nerve. 

Variations. — These  are  very  frequent.  It  may  be  absent  or  double.  The  posterior  belly 
may  be  attached  to  the  clavicle  and  scapula,  or  to  the  clavicle  alone.  It  may  receive  a  slip  from 
the  manubrium.  The  anterior  belly  may  blend  with  the  sterno-hyoid,  and  it  may  send  a  slip  to 
the  thyroid  cartilage  or  the  mandible. 


Second  Layer  of  Infea-hyoid  Muscles 

This  consists  of  two  muscles — the  sterno-thyroid  and  thyro-hyoid. 

1.  STERNO-THYROID 

The  sterno-thyroid  (figs.  301  and  314) — named  from  its  attachment  to  the 
sternum  and  thyroid  cartilages — is  fiat  and  ribbon-shaped. 

Origin. — (1)  The  lower  part  and  side  of  the  back  of  the  manubrium  (prester- 
num), from  the  middle  line  to  the  notch  for  the  first  rib  cartilage;  (2)  the  back  of 
the  first  rib  cartilage,  and  occasionally  that  of  the  second;  and  (3)  occasionally 
from  the  back  of  the  clavicle  near  the  facet  for  the  first  costal  cartilage. 

Insertion. — The  oblique  line  on  the  outer  surface  of  the  ala  of  the  thyroid 
cartilage. 

Structure. — Arising  fleshy,  the  two  muscles  form  broad  bands  of  parallel  fibres, 
which  at  first  lie  close  to  one  another,  and  afterwards  diverge  slightly  as  they 
ascend.  Finally,  they  are  inserted  by  short  tendinous  fibres  into  the  thyroid 
cartilage.     Occasionally,  the  muscle  is  crossed  by  a  tendinous  intersection. 

Nerve-supply. — Branches  from  the  loop  between  the  descendens  and  the  com- 
municantes  hypoglossi  which  enter  the  outer  part  of  the  deep  surface  of  the  muscle. 

Action. — (1)  To  draw  down  the  thyroid  cartilage,  e.g.  after  swallowing;  (2)  in 
conjunction  with  the  thyro-hyoid  it  will  depress  the  hyoid  l)one. 

Relations. — Superficially,  the  cervical  fascia,  the  anterior  jugular  vein,  the 
sterno-mastoid  and  sterno-hyoid  and  omo-hyoid  muscles;  deeph',  the  inferior  con- 
strictor, the  cricoid  cartilage,  crico-thyroid  muscle,  thyroid  gland,  inferior  thyroid 
veins  and  trachea,  the  common  carotid  artery  and  left  innominate  vein. 

Variations. — This  muscle  may  be  absent  or  double  ;  the  muscles  of  the  two  sides  may  be 
united.     It  may  send  a  slip  to  the  carotid  sheath. 

2.  THYRO-HYOID 

The  thyro-hyoid — named  from  its  attachment  to  the  thyroid  cartilage  and 
hyoid  bone — is  a  (piadrilateral  sheet. 

Origin. — The  oblique  line  on  the  outer  surface  of  the  ala  of  the  thyroid 
cartilage. 


THYRO-HYOID— DIGASTRIC  449 

Insertion. — The  lower  border  of  (l)  the  outer  tliird  of  the  body  of  the  hyoid 
bone;  and  of  (2)  tlie  inner  half  of  the  greater  eornu. 

Structure. — This  muscle  is  a  continuation  ujiwards  of  the  preceding  muscle, 
many  of  its  fibres  being  derived  from  those  of  the  sterno-thyroid  without  any 
attachment  to  the  cartilage.  It  consists  of  parallel  fleshy  fibres  which  run  nearly 
vertically  upwards  to  their  insertion  into  the  hyoid  bone. 

Nerve-supply. — A  special  branch  of  the  hypoglossal  nerve  which  enters  the 
deep  surface  of  the  muscle  near  its  posterior  border. 

Action. — (1)  To  draw  up  the  thyroid  cartilage,  as  in  swallowing,  or  in  the  pro- 
duction of  a  high  note  in  singing;  (2)  in  association  with  the  sterno-thyroid  to  draw 
down  the  hyoid  bone. 

Relations. — Superficially,  the  sterno-hyoid,  omo-hyoid,  and  sterno-mastoid; 
deeply,  the  thyro-hyoid  membrane,  the  thyro-hyoid  bursa,  the  sviperior  laryngeal 
vessels  and  nerve. 

Variations. — Slips  are  occasionally  seen  passing  from  the  cricoid  cartilage  to  the  hyoid  bone, 
or  between  the  upper  border  of  the  thyroid  cartilage  in  front  and  the  body  of  the  hyoid  bone. 


THE  SUPRA-HYOID  MUSCLES 

These  consist  of  four  muscles  arranged  in  three  layers:  the  first  containing  the 
digastric  and  stylo-hyoid,  the  second  the  mylo-hyoid,  and  the  third  the  genio-hyoid. 


1.    DIGASTRIC 

The  digastric — named  from  its  two  bellies  (yaffrrj/j,  the  belly) — is  composed  of 
two  flattened  and  somewhat  s[)indle-shaped  bellies  united  by  a  tendon. 

Origin. — (1)  Of  posterior  belly,  the  digastric  fossa  of  the  temporal  bone;  (2) 
of  (interior  belly,  the  lower  border  of  the  body  of  the  mandible  just  external  to  the 
symphysis. 

Insertion. — By  its  central  tendon,  which  is  attached  to  the  outer  part  of  the 
lower  l)order  of  the  body  of  the  hyoid  bone  and  the  adjacent  part  of  the  great  cornu. 

Structure. — The  posterior  belly  at  its  origin  consists  of  short  tendinous  fibres, 
which  soon  form  a  laterally  compressed  muscle.  This  passes  downwards,  forwards 
and  inwards,  and  converges  upon  a  laterally  flattened  rounded  tendon  about  half 
an  inch  (1"2  cm.)  above  the  tip  of  the  great  cornu  of  the  hyoid  bone. 

The  anterior  belly  arises  by  short  tendinous  fibres,  and  forms  a  muscle  flattened 
fron^  before  backwards  and  from  above  downwards,  which  is  shorter  and  smaller 
than  the  posterior  belly.  Its  fibres  converge  as  they  pass  backwards  and  slightly 
downwards  and  outwards,  to  end  in  the  flattened  tendon  a  (piarter  of  an  inch  (6 
nun.)  above  the  junction  of  the  body  and  great  cornu  of  the  hyoid  bone.  The 
central  tendon  is  bound  down  to  its  insertion  upon  the  h3'oid  bone,  chiefly  by  a 
fibrous  expansion  given  off  from  its  lower  border,  and  to  a  very  small  degree  also 
by  the  oblicjue  arch  over  it  formed  by  the  division  of  the  stylo-hyoid  muscle.  Often, 
a  part  of  this  expansion  passes  inwards  across  the  middle  line  and,  uniting  with  its 
felloAV,  forms  a  membranous  covering  to  the  deeper  structures,  and  unites  the  inner 
borders  of  the  two  anterior  bellies. 

Nerve-supply. — The  posterior  belly,  which  is  really  a  distinct  muscle,  be- 
longing to  a  deeper  stratum  of  the  muscular  planes,  receives  a  special  Ijranch  from 
the  facial  nerve  which  enters  the  upper  part  of  its  deej)  surface.  Perhaps  this  may 
be  due  to  the  fact  that  this  part  of  the  muscle  assists  in  swallowing;  for  the  facial 
nerve,  by  means  of  the  Vidian  and  the  relations  which  through  the  lesser  super- 
ficial petrosal  nerve  it  has  with  the  otic  ganglion,  may  l)e  considered  to  take  part 
in  this  function,  as  well  as  in  the  expression  of  emotions. 

The  anterior  lielly  receives  at  the  outer  part  of  its  deep  surface  the  terminal 
filaments  of  the  mylo-hyoid  twig  from  the  inferior  dental  (or  mandibular)  branch 
of  the  mandibular  division  of  the  fifth  nerve. 
29 


450  THE  MUSCLES 

Action. — (1)  The  posterior  belly  draws  upwards  and  l)ackwards  the  hyoid 
bone,  as  in  the  elevation  of  the  larynx  in  the  second  part  of  deglutition;  (2)  the 
anterior  belly,  acting  from  above,  draws  upwards  and  forwards  the  hyoid  bone; 
and,  acting  in  the  opposite  direction,  (o)  it  assists  in  the  depression  of  the  lower 
jaw  and  in  opening  the  mouth.  Although  a  comparatively  weak  muscle,  it  acts 
with  considerable  power  in  this  movement,  for  it  is  inserted  at  the  end  of  the  lever 
of  the  second  order  formed  by  the  mandible,  while  the  resistance  which  it  has  to 
overcome  is  exerted  by  muscles  acting  much  nearer  to  the  fulcrum.  Moreover,  its 
direction  downwards  and  backwards  is  at  a  considerable  angle  with  the  line  of  the 
lever,  viz.  that  which  joins  the  i)rominence  of  the  chin  to  a  point  a  little  above 
the  inferior  dental  foramen.  (4)  If  the  mandible  be  fixed  and  both  bellies  act,  the 
hyoid  bone  will  be  drawn  directly  upwards.  By  this  action  the  muscle  is  of  great 
importance  in  the  elevation  of  the  tongue,  which  rests  upon  the  ui)per  surface  of 
the  hyoid  bone.  It  Avill  therefore  help  in  the  first  part  of  deglutition,  in  which  the 
back  of  the  tongue  is  pressed  against  the  hard  palate. 

Relations. — The  posterior  belly  lies  beneath  the  mastoid  process,  the  sterno- 
mastoid,  splenius,  and  trachelo-mastoid  muscles,  the  facial  vein,  and  the  parotid 
gland;  in  front  lies  the  stylo-hyoid  muscle;  deeply,  the  middle  constrictor  of  the 
pharynx,  the  hyo-glossus,  the  external  and  internal  carotid  arteries,  and  some  of 
the  branches  of  the  external  carotid,  the  internal  jugular  vein,  the  hypoglossal  and 
superior  laryngeal  nerves. 

The  tendon  lies  beneath  the  deep  cervical  fascia,  platysma  myoides,  and  part  of 
the  stylo-hyoid  muscle.  Above  is  the  submaxillar}-  gland.  On  its  deep  surface  is 
the  rest  of  the  stylo-hyoid  muscle,  the  mylo-hyoid,  the  hyo-glossus,  and  the  hypo- 
glossal nerve. 

The  anterior  belly  is  covered  by  the  deep  cervical  fascia  and  platysma  myoides, 
and  it  lies  upon  the  mylo-hyoid  muscle. 

Variations. — A  second  posterior  belly  may  arise  in  front  of  the  angle  of  the  mandible;  slips 
may  also  arise  from  the  styloid  process,  or  the  pharynx.  The  anterior  belly  may  be  absent ;  it 
may  be  partly  or  entirely  united  with  that  of  the  opposite  side,  or  may  send  a  slip  to  the  median 
raphe  of  the  mylo-hyoid. 

2.  STYLO-HYOID 

The  stylo-hyoid — named  from  its  attachments — is  a  slender  fusiform  muscle 
with  a  bifurcated  lower  extremity. 

Origin. — The  back  and  outer  surface  of  the  styloid  process  of  the  temporal  bone 
near  its  base. 

Insertion. — The  lower  border  of  the  body  of  the  hyoid  bone  at  the  point  of 
union  with  the  great  cornu. 

Structure. — Arising  by  a  short  tendon,  its  fibres  soon  become  fleshy  and  pass 
downwards  and  forwards.  Just  before  its  insertion  they  divide  into  two  bundles, 
which  form  an  obliquely  directed  arch  bridging  over  the  tendon  of  the  digastric 
muscle. 

Nerve -supply. — A  special  branch  of  the  facial  nerve,  Avhich  enters  its  deep 
surface  fr(nn  Ijchind. 

Action. — The  same  as  that  of  the  posterior  belly  of  the  digastric,  viz.  to  draw 
the  liyoid  l)one  backwards  and  upwards. 

Relations. — Superficially,  the  parotid  gland  and  deep  cervical  fascia;  in  front, 
the  submaxillary  gland;  behind,  the  posterior  belly  of  the  digastric;  deeply,  the 
middle  constrictor  and  hyo-glossus  and  the  external  carotid  artery. 

Variations, — The  stylo-hyoid  may  arise  in  part  from  the  cartilage  of  the  external  auditory 
meatus.  It  may  be  absent,  or  its  insertion  may  be  undivided,  in  which  case  it  may  pass  to  the 
inner  or  outer  side  of  the  digastric  tendon.  A  second  stylo-hyoid  may  run  beneath  the  hyo-glossus 
to  the  lesser  cornu  of  the  hyoid  bone. 

3.  MYLO-HYOID 

The  mylo-hyoid — named  from  its  attachment  to  the  lower  jaw  (jj-uXtj  =  a  mill 
and  the  jaw)  and  to  the  hyoid  bone — is  a  triangular  and  somewhat  curved  sheet. 


MYL  0-H }  OW—GENIO-HYOID  451 

Origin. — The  whole  lengtli  of  the  mylo-liyoid  ridge  on  the  inner  surface  of  the 
body  of  the  mandible. 

Insertion. — (1)  The  lower  edge  of  the  anterior  surface  of  the  body  of  the  hyoid 
bone;  (2)  a  median  raphe  extending  from  the  middle  of  the  loAver  border  of  the 
body  of  the  hyoid  bone  to  the  back  of  the  symphysis  of  the  mandible  innnediately 
below  the  genial  tubercles. 

Structure. — Arising  l)y  fleshy  and  short  tendinous  fibres  intermingled,  the 
muscle  passes  inwards  and  slightly  downwards  to  its  insertion  by  short  tendinous 
fibres  into  the  median  ra])he  and  hyoid  bone.  Sometimes  the  fleshy  fibres  are  here 
and  there  continuous  with  those  of  the  other  side.  Each  of  them  is  somewhat 
arched,  so  that  the  whole  sheet  has  a  slight  downward  convexity.  The  muscles  of 
the  two  sides  together  form  a  curved  diaphragm  which  stretches  across  the  angle 
containofl  Ix^tween  the  two  portions  of  the  mandil)le. 

Nerve-supply. — From  the  third  (or  mandibular)  division  of  the  fifth  cranial 
nerve,  by  the  mylo-hyoid  branch  of  the  inferior  dental  which  enters  the  nnder 
surface  of  the  muscle  by  several  filaments. 

Action. — (1)  To  raise  the  tongue,  the  floor  of  the  mouth,  and  the  hyoid  bone,  as 
in  mastication  and  the  first  part  of  swallowing.  By  its  elevation  of  the  hyoid  bone 
it  will  also  exert  some  influence  on  the  larynx  and  lower  part  of  the  pharynx. 
These  actions  will  be  most  efficiently  carried  out  when  the  jaw  is  closed.  (2) 
Acting  from  below,  it  will  help  in  the  depression  of  the  lower  jaw  and  in  opening 
the  mouth. 

Relations. — Upon  its  under  surface  lie  the  superficial  portion  of  the  submax- 
illary gland,  the  submental  artery,  and  the  anterior  belly  of  the  digastric  muscle. 
Above,  it  is  in  contact  with  the  genio-hyoid  and  hyo-glossus,  the  sublingual 
gland,  the  deep  portion  of  the  submaxillary  gland,  and  the  hypoglossal  nerve. 

Variations. — The  mylo-hyoid  may  be  closely  connected  with  the  anterior  belly  of  the  diga.«tric. 
Openings  are  sometimes  found  in  the  muscular  sheet,  containing  lobules  of  the  submaxillary 
gland. 

4.  GENIO-HYOID 

The  genio-hyoid — named  from  its  attachment  to  the  chin  (yi'^sur/)  and  the 
hyoid  bone — is  somewhat  fusiform,  but  flattened  from  above  downwards  behind, 
and  from  side  to  side  in  front. 

Origin. — The  lower  genial  tubercle. 

Insertion. — The  anterior  surface  of  the  body  of  the  hyoid  bone. 

Structure. — Arising  by  a  short  tendon,  its  fibres  pass  backwards  and  slightly 
downwards,  close  to  those  of  the  corresponding  muscle  of  the  other  side.  Near 
the  hyoid  bone  they  spread  out  laterally,  and  occupy  nearly  the  whole  of  the 
upper  and  anterior  surface  of  the  body,  sometimes  even  a  small  ])ortion  of  the 
greater  cornu. 

Nerve-supply. — The  hypoglossal  nerve,  which  sends  filaments  to  the  deep 
surface. 

Action. — (1)  To  raise  and  draw  forwards  the  hyoid  bone;  (2)  to  draw  down  the 
mandible.  In  its  direction  and  action  it  is  closely  related  to  the  anterior  belly  of 
the  digastric. 

Relations. — Superficially,  the  mylo-hyoid  muscle;  deeply,  the  genio-hyo- 
glossus;  on  its  median  surface,  the  corresponding  muscle  of  the  other  side. 

Variations.— The  genio-hyoid  may  be  double,  or  it  may  form  one  muscle  witli  its  fellow  of 
the  opposite  side. 


THE  EXTRINSIC  MUSCLES  OF  THE  TONGUE 

The  tongue  consists  chiefly  of  muscular  tissue,  part  of  which  arises  from  the 
adjacent  bones,  Avhile  the  rest  is  made  up  of  bands  of  fibre  which  pass  in  various 
directions  in  its  substance,  and  have  no  external  attachment.    The  latter  or  intrinsic 


452  THE  MUSCLES 

imiscles  will  he  described  later;  the  former  or  extrinsic  muscles  constitute  a  grou}> 
which  is  nearly  related  to  those  which  have  been  just  described.  It  consists  of 
four  muscles — viz.  the  genio-hyo-glossus,  the  hyo-glossus,  the  stylo-glossus,  and 
the  palato-glossus. 

1.  GENIO-HYO-GLOSSUS 

The  genio-hyo-glossus — named  from  its  attachment  to  the  chin  (ji^s'.ov),  hyoid 
bone,  and  tongue  (yXdxTffa),  is  a  flat  sheet  forming  the  quadrant  or,  more  correctly, 
the  sector  of  a  circle,  and  separated  from  its  fellow  by  a  thin  stratum  of  connective 
tissue,  the  septum  of  the  tongue. 

Origin. — The  upper  genial  tubercle. 

Insertion. — (1 )  The  whole  length  of  the  tongue  in  the  submucous  tissue  just 
external  to  the  median  plane,  from  the  tip  along  the  dorsum  to  the  root;  (2)  the 
upper  part  of  the  anterior  surface  of  the  body  of  the  hyoid  bone;  (3)  by  a  few 
fibres  into  the  side  of  the  pharynx. 

Structure. — Its  origin  is  by  a  short  tendon,  froai  which  its  fleshy  fi):)res  diverge 
in  a  fan-shaped  sheet  to  their  extensive  insertion. 

Nerve-supply. — The  hypoglossal,  by  filaments  which  enter  its  outer  surface. 

Action. — (1)  To  draw  downwards  and  forwards  the  mesial  portion  of  the 
tongue  so  as  to  make  its  dorsum  concave  upwards  in  a  transverse  direction;  (2)  by 
its  anterior  fibres  to  drawback  the  tip  of  the  protruded  tongue;  (3)  by  fibres  which 
pass  to  the  back  part  of  the  dorsum  of  the  tongue  to  draw  it  forwards,  and  protrude 
the  tongue;  (4)  by  its  lowest  fibres  to  draw  upwards  and  forwards  the  hyoid  bone, 
and  so  help  the  genio-hyoid  and  anterior  belly  of  the  digastric  in  raising  the 
tongue;   (5)  acting  from  below,  its  hyoid  portion  will  help  in  depressing  the  lower 

Relations. — Externally,  the  inferior  lingualis,  hyo-glossus,  and  stylo-glossus 
muscles,  the  ranine  artery,  the  terminal  branches  of  the  hypoglossal  and  lingual 
gustatory  nerves,  the  mucous  membrane  of  the  floor  of  the  mouth,  the  sublingual 
gland,  and  Wharton's  duct;  internally,  the  fellow  muscle  and  septum  linguae; 
along  its  lower  border,  the  genio-hyoid  muscle. 


2.  HYO-GLOSSUS 

The  hyo-glossus — named  from  its  attachments  to  the  hyoid  bone  and  tongue 
(y/.uxrtja) — is  a  thin  square  sheet. 

Origin. — (1)  From  the  front  of  the  hyoid  bone  near  the  upper  border  of  the 
outer  third  of  its  body;  (2)  from  the  upper  border  of  all  its  great  cornu;  (3)  by  a 
small  slip  from  the  lesser  cornu. 

Insertion. — The  submucous  tissue  and  adjacent  muscular  mass  of  the  posterior 
half  of  the  tongue  external  to  the  preceding  muscle. 

Structure. — The  fleshy  fibres  arise  directly  from  the  bone  in  a  thin  sheet,  and 
ascend  nearly  parallel  to  one  another.  The  anterior  fibres,  however,  diverge 
slightly  forwards,  and  they  all,  having  reached  the  upper  surface  of  the  sides  of  the 
tongue,  course  inwards,  interlacing  with  the  fibres  of  the  palato-glossus  and  super- 
ficial lingualis  to  form  a  submucous  cover  to  the  tongue. 

Those  which  arise  from  the  lesser  cornu  are  often  described  as  a  distinct  muscle, 
the  cJwn(Jro-filofif<iif<,  which  is  separated  from  the  rest  of  the  muscle  by  some  bundles 
whicVi  ])ass  from  the  lower  part  of  the  genio-hyo-glossus  to  the  superior  constrictor. 

Nerve-supply. — The  hypoglossal  nerve,  which  sends  filaments  into  its  outer 
surface. 

Action. — (1)  To  draw  downwards  the  sides  of  the  tongue,  increasing  its  trans- 
verse convexity;   (2)  to  draw  backwards  the  protruded  tongue. 

Relations. — Externally,  the  mylo-hyoid,  digastric,  stylo-hyoid,  and  stylo- 
glossus muscles,  the  lingual  vein,  lingual  gustatory  and  hypoglossal  nerves,  the 
submaxillary  gland  and  Wharton's  duct;  deeply,  the  inferior  lingualis,  genio-hyo- 
glossus,  middle  constrictor,  and  part  of  the  origin  of  the  superior  constrictor,  the 
lingual  artery,  and  glosso-pharyngeal  nerve. 


STYLO-GLOSSUS 


453 


3.  STYLO-GLOSSUS 

The  stylo-glossus — named  from  its  attachments  to  the  styloid  process  and 
tongue  (y/.u)(jiTa) — is  a  long,  triangular  sheet. 

Origin. — (1)  The  front  of  the  lower  part  and  tip  of  the  styloid  i)rocess  of  the 
temi)oral  i)one;  (2)  the  upper  part  of  the  stylo-mandibular  ligament. 

Insertion. — The  submucous  tissue  and  subjacent  muscular  strata  of  the  side  of 
the  t(jngue  and  the  adjacent  parts  of  its  under  surface. 

Structure. — Arising  by  short  tendinous  fibres,  the  muscle  soon  develops  into  a 
long,  fan-shaped,  laterally-compressed  sheet,  which  passes  in  a  long  curve,  with  an 
upward  concavity,  forwards  and  slightly  downwards  and  inwards  to  the  side  of  the 
tongue,  where  it  partly  overlaps  and  partly  interlaces  with  the  hyo-glossus  muscle, 
forming  with  this  nuiscle  and  some  of  the  fibres  of  the  palato-glossus  a  thin  super- 
ficial stratum  which  is  continued  forwards  to  the  tip  of  the  tongue. 

Nerve-supply. — From  the  hypoglossal  nerve,  by  filaments  which  enter  its  ex- 
ternal surface. 

Fig.  315. — Su)E  View  of  the  Muscles  of  the  Tongue. 


Lingualis  inferior 


Qenio-hyo-glossus    — 


Genio-hyoid 
Anterior  belly  of 
digastric 


Hyo-glossus 


Mylo-hyoid 


Action. — (1)  To  draw  back  the  tongue — for  this  purpose  it  arises  from  the 
styloid  process  as  low  as  possible  and  below  the  level  at  which  the  two  other  styloid 
muscles  arise;  (2)  to  draw  upwards  the  sides  of  the  tongue,  so  as  to  help  the  genio- 
hyo-glossi  and  some  of  the  intrinsic  muscles  in  making  its  upper  surface  concave 
from  side  to  side. 

Relations. — Superficially,  the  internal  pterygoid,  tlie  parotid  gland,  lingual 
gustatory  nerve,  and  the  mucous  membrane  of  the  side  of  the  tongue;  deei)ly,  the 
stylo-pharyngeus,  hyo-glossus,  inferior  lingualis  and  genio-hyo-glossus,  with  tlie 
glosso-pharyngeal  nerve. 


4.  PALATO-GLOSSUS 

The  palato-glossus — named  from  its  attachment  to  the  soft  palate  and  tongue 
(y?.u)(T(Ta) — is  a  somewhat  cylindrical  muscle  which  expands  at  either  end  into  a 
thin  sheet. 

Origin. — The  under  surface  of  the  aponeurosis  of  the  soft  palate;  and  at  the 
middle  line  its  fibres  are  continuous  with  those  of  its  fellow  of  the  opposite  side. 


454  THE  MUSCLES 

Insertion. — (1)  The  superficial  muscular  stratum  which  covers  the  side  and 
adjacent  part  of  the  under  surface  of  the  tongue;  (2)  it  is  partly  continuous  with 
the  deep  transverse  lingualis  muscle. 

Structure. — Arising  in  a  thin  muscular  sheet,  its  fibres  form  as  they  pass  out- 
wards a  small  cylindrical  bundle  which,  lying  in  front  of  the  tonsil  and  against 
the  w^all  of  the  pharynx,  constitutes  the  anterior  pillar  of  the  fauces.  This  bundle 
runs  downwards  and  forwards  till  it  reaches  the  side  of  the  tongue  at  the  junction 
of  its  middle  and  posterior  thirds.  Here  some  of  the  fibres  pass  forwards  and 
downwards  to  join  the  superficial  stratum  formed  by  the  stylo-glossus  and  hyo- 
glossus.  The  rest  pass  inwards  towards  the  midtlle  line,  being  continued  into  the 
deep  transverse  lingualis  muscle.  This  part  of  the  two  muscles,  together  Avith 
the  associated  portion  of  the  lingualis  transversus,  forms  a  sphincter  muscle  round 
the  front  part  of  the  faucial  opening. 

Nerve-supply. — Filaments  from  the  pharyngeal  plexus. 

Action. — (1)  To  draw  dowaiwards  the  sides  of  the  soft  palate;  (2)  to  draw 
upwards  and  backwards  the  sides  of  the  tongue.  The  combination  of  these  two 
actions  closes  the  front  part  of  the  faucial  opening,  as  in  the  second  part  of 
swallowing,  when  the  back  of  the  tongue  comes  into  contact  with  the  soft  palate, 
and  prevents  the  return  of  the  food  which  is  being  grasped  by  the  constrictors.  It 
should  be  remembered,  however,  that  the  elevation  of  the  tongue  is  chiefly  due  to 
the  muscles  Avhich  raise  the  hyoid  bone. 

Relations. — Superficially,  it  is  covered  by  the  mucous  membrane  of  the  soft 
palate  and  the  side  of  the  tongue;  deeply,  it  is  in  contact  with  the  aponeurosis  of 
the  soft  palate,  the  superior  constrictor  of  the  pharynx,  and  the  hyo-glossus; 
behind  it  lies  the  tonsil. 

For  ^luscles  of  the  Palate  see  page  944.  For  Muscles  of  the  Pharynx  see 
pages  950-952. 


THE  DEEP  MUSCLES  OF  THE  FRONT  OF  THE  NECK 

The  deep  muscles  of  the  front  of  the  neck  consist  of  an  inner  and  an  outer 
group,  separated  from  one  another  by  the  line  of  the  anterior  tubercles  of  the 
cervical  vertebrae.     Both  groups  are  covered  in  front  b}'  the  prevertebral  fascia. 


Outer  Geoup 

The  outer  group  is  formed  by  the  three  scaleni,  which  pass  from  the  first  two 
ribs  upwards  and  inwards  to  the  transverse  processes. 


1.  SCALENUS  ANTICUS 

The  scalenus  anticus — named  from  its  shape  (scalenus  =  of  unequal  sides, 
being  a  term  a]>pli('d  to  certain  triangles  in  geometry)  and  its  relation  to  its  fellows 
— is  a  thick  triangular  sheet. 

Origin. — The  scalene  tubercle  near  the  inner  liorder  of  the  upper  surface  of  the 
first  rib. 

Insertion. — Tlie  anterior  tul)ercles  of  the  third,  fourth,  fifth,  and  sixth  cervical 
vertebne. 

Structure. — Arising  by  a  short,  somewhat  flattened  tendon,  which  is  continued 
upwards  for  a  short  distance  upon  the  front  and  outer  surface  of  the  muscle,  the 
fleshy  fibres  diverge  as  they  pass  upwards  and  slightly  backwards  and  inwards  to 
be  inserted  by  four  short  tendons  into  the  transverse  processes. 

Nerve-supply. — From  the  anterior  jirimarv  branches  of  the  fourth,  fifth,  and 
sixth  cervical  nerves  close  to  their  points  of  emergence. 

Action. — (1)  The  rib  being  fixed,  it  will  help  to  flex  the  neck  botli  forwards 


SCALENUS  MEDI US— SCALENUS  POSTICUS  455 

and  laterally,  and  to  rotate  it  so  as  to  turn  the  face  to  tlie  opposite  side;   (2)  it  will 
raise  the  first  rib,  especially  in  forced  inspiration. 

Relations. — In  front  lie  the  sterno-niastoid,  omo-hyoid,  and  subclavius,  the 
internal  jugulai  vein,  the  subclavian  vein  and  phrenic  nerve;  on  the  inner  side  are 
the  rectus  cai)itis  anticus  major,  longus  colli,  the  vertebral  vessels,  and  the  sympa- 
thetic cord;  on  the  outer  side  and  behind  emerge  the  anterior  primary  branches  of 
the  cervical  nerves  separating  it  from  the  scalenus  medius;  and  loVer  down  it 
crosses  in  front  of  the  second  part  of  the  subclavian  artery  and  the  pleura. 


2.  SCALENUS  MEDIUS 

The  scalenus  medius — named  from  its  shape  and  position — is  an  elongated 
triangular  sheet. 

Origin. — The  upper  surface  of  the  first  rib  between  the  tuberosity  and  the  groove 
for  the  subclavian  artery. 

Insertion. — The  front  of  the  posterior  tubercles  of  the  six  lower  cervical 
vertebne,  and  frequently  also  the  lower  part  of  the  lateral  mass  of  the  atlas. 

Structure. — Arising  by  a  broad  band,  tendinous  in  front  and  muscular  behind, 
the  fleshy  fibres  form  a  thick  sheet  of  slightly  divergent  fibres,  whicli  run  upwards 
and  inwards  to  end  upon  the  vertebrae  in  six  short  tendons. 

Nerve-supply. — The  anterior  primary  branches  of  the  cervical  nerves  as 
soon  as  they  emerge  supply  numerous  filaments  to  the  inner  part  of  its  anterior 
surface. 

Action. — Acting  from  below,  to  flex  the  neck  laterally;  acting  from  above,  to 
raise  the  first  rib  as  in  forced  inspiration,  or  to  fix  it  in  ordinary  inspiration. 

Relations. — In  front  lie  the  sterno-mastoid,  omo-hyoid,  and  trapezius,  the 
subclavian  artery,  cervical  and  brachial  plexuses;  behind,  it  is  in  contact  with  the 
levator  anguli  scapulae  and  scalenus  posticus. 


3.  SCALENUS  POSTICUS 

The  scalenus  posticus — named  from  its  form  and  position — is  a  triangular 
sheet. 

Origin. — The  upper  part  of  the  outer  surface  of  the  second  rib  l)ehind  the 
rough  prominence  for  the  serratus  magnus. 

Insertion. — The  lower  surface  of  the  posterior  tubercles  of  the  two  or  three 
lowest  cervical  vertebrae. 

Structure. — Arising  partly  directly  from  the  bone,  and  partly  by  a  short  apo- 
neurosis which  covers  the  outer  and  posterior  part  of  the  origin,  its  fleshy  fibres 
converge  and  are  inserted  by  three  short  tendons. 

Nerve-supply. — Small  filaments  which  come  from  the  lower  three  cervical 
nerves  at  their  points  of  emergence,  and,  after  passing  through  the  scalenus  medius, 
enter  the  front  service  of  the  muscle. 

Action. — When  the  rib  is  fixed,  to  flex  the  lower  part  of  the  neck  laterally, 
and  acting  from  aliove,  to  raise  the  second  rib,  especially  in  forced  inspiration. 

Relations. — In  front  lies  the  scalenus  medius;  behind,  the  levator  anguli 
scapulae. 

Variations  of  the  scaleni. — The  scalenus  posticus  maybe  absent.  The  scalenus  medius  may 
arise  as  low  as  the  third  rib.  A  portion  of  the  scalenus  anticus  may  be  separate  from  the  rest, 
and  pass  behind  the  subclavian  artery. 


45G 


THE  MUSCLES 


Inner  Group 

The  inner  or  prevertebral  group  consists  of  the  greater  and  lesser  rectus  capitis 
anticus  and  the  longus  colli. 


1.  RECTUS  CAPITIS  ANTICUS  MAJOR 

The  rectus  capitis  anticus  major — named  from  its  direction,  position,  and 
size — is  a  thick,  irregular,  quadrilateral  sheet. 

Origin. — The  front  of  the  anterior  tubercles  of  the  third,  fourth,  fifth,  and 
sixth  cervical  vertebrae. 


Fig.  316.— The  Muscles  of  the  Front  of  the  Neck. 


Rectus  eapitia  lateralis 


Rectus  capitis  auticus 
major 


Origin  of  rectus  capitis 
anticus  major 


Scalenus  medius 


Scalenus  auticus 


Scalenus  posticus  ""• 


Rectus  capitis  later- 
alis 
Rectus  capitis  anti- 
cus minor 


Intertransversalia 
anterior 


Intertransversalia 
posterior 


Longus  colli 


nsertion  of  scalenus 
anticus 


Scalenus  medius 


Scalenus,  posticus 


Insertion. — A  transverse  impression  upon  the  under  surface  of  the  basilar 
process  of  the  occipital  l)one,  extending  from  just  l)ehind  the  pharyngeal  tubercle 
outwards  and  somewhat  forwards. 

Structure. — Arising  by  four  tendinous  teeth,  tlie  jiarallel  fleshy  fibres  run 
upwards  and  inwards  to  be  inserted  directly  upon  the  occii)ital  bone.  An  incom- 
plete tendinous  intersection  crosses  its  anterior  surface. 

Nerve-supply. — Internal  branches  from  tlie  first  and  second  cervical  nerves 
enter  the  upper  part  of  its  front  surface. 


RECTUS  CAPITIS  ANTICUS  MINOR— LONG  US  COLLI  457 

Action. — To  flex  the  head,  and  sHghtly  to  rotate  it  to  the  same  side. 

Relations. — In  front,  the  internal  and  common  carotid  artery,  the  internal 
jugular  vein,  the  pneumogastric  and  sympathetic  nerves,  and  the  upper  part  of  tlie 
pharynx;  behind,  the  rectus  capitis  anticus  minor,  and  part  of  the  longus  colli. 


2.  RECTUS  CAPITIS  ANTICUS  MINOR 

The  rectus  capitis  anticus  minor — named  from  its  direction,  position,  and 
size — is  thick  luul  rihbon-shaped,  and  continues  the  series  of  the  anterior  intertrans- 
versalcs. 

Origin. — The  upper  surface  of  the  lateral  mass  of  the  atlas  in  front  of  the 
articular  jn'ocess. 

Insertion. — The  under  surface  of  the  basilar  portion  of  the  occipital  l)one  in 
front  of  the  foramen  magnum,  but  not  as  far  inwards  as  the  preceding  muscle. 

Structure. — Parallel  or  slightly  divergent  fleshy  fibres  which  run  upwards  and 
inwards. 

Nerve-supply. — The  first  cervical  nerve,  which  sends  a  filament  to  its  front 
surface. 

Action. — To  flex  the  head. 

Relations. — In  front,  the  rectus  capitis  anticus  major;  behind,  the  anterior 
occipito-axial  ligament. 

3.  LONGUS  COLLI 

The  longus  colli — named  from  its  length  and  the  region  in  which  it  lies — is  a 
compound  muscle,  and  forms  an  elongated  triangular  sheet  with  the  Ijase  running 
vertically  along  the  outer  Ijorcler  of  the  anterior  common  ligament,  and  the  obtuse 
apex  directed  outwards.  It  consists  of  three  portions:  one  mesial,  the  vertical; 
and  two  lateral,  the  upper  and  lower  ohllque  portions. 

Vertical  portion  : — 

Origin. — Lateral  part  of  front  of  bodies  of  last  two  cervical  and  first  three 
thoracic  vertebrae,  external  to  the  anterior  common  ligament. 

Insertion. — Lateral  part  of  front  of  bodies  of  second,  third,  and  fourth  cervical 
vertebne. 

Lower  oblique  portion  : — 

Origin. — Lateral  ])art  of  front  of  bodies  of  the  first  three  thoracic  vertel)rce. 

Insertion. — The  front  of  the  anterior  tubercles  of  the  transverse  processes  of 
thf  fifth  and  sixth  cervical  vertebne. 

Upper  oblique  portion  : — 

Origin. — The  front  of  the  anterior  tubercles  of  the  transverse  processes  of  the 
third,  fourth  and  fifth  cervical  vertebrae. 

Insertion. — The  under  surface  and  side  of  the  anterior  tubercle  of  the  atlas. 

Structure. — All  three  portions  arise  by  short  tendons,  then  Ijccome  fleshy,  and 
are  inserted  l)y  short  tendons,  with  the  exception  of  the  superior  ol)lique  portion, 
which  has  a  fleshy  attachment  to  the  tubercle  of  the  atlas. 

Nerve-supply. — The  anterior  branches  from  the  cervical  nerves  soon  after  their 
emergence. 

Action. — To  flex  the  neck;  and  also  by  its  olilique  portions  slightly  to  rotate 
and  laterally  flex  it. 

Relations. — In  front,  the  pharynx,  oesophagus,  great  vessels  of  the  neck,  the 
inferior  tln'roid  artery,  the  sympathetic  cord,  the  pneumogastric  ner\'e,  and  the 
recurrent  laryngeal  nerve;  behind,  the  vertebral  cohnnn,  and,  under  cover  of 
the  lower  oblique  }>ortion,  the  vertebral  artery. 


ABNORMAL   MUSCLES 

By  J.  BLAND  SUTTON,  F.R.C.S. 

ASSISTANT  SURGEON   TO  THE  MIDDLESEX  HOSPITAL,  AND  SURGEON   TO  THE  CHELSEA   HOSPITAL  FOR   WOMEN 

Revised  and  Added  to  by  ARTHUR  ROBINSON,  M.D.,  Lectueer  ox  Anatomy  at  the 

Middlesex  Hospital 


The  abductor  ossis  metatarsi  quinti  art'ses  from  the  outer  tubercle  of  the  calcaneum. 

It  is  inserted  into  the  tuberosity  at  the  base  of  the  fifth  metatarsal  bone.  The  origin  and 
insertion  are  marked  in  fig.  167.  It  is  present  in  two  out  of  every  three  subjects,  and  when  not 
represented  by  muscle  fibres  its  place  is  occupied  by  a  band  of  fibrous  tissue. 

Agitator  caudae  is  a  small  slip  of  muscles  which  arises  from  the  last  piece  of  the  sacrum  or 
from  the  side  of  the  coccyx.     It  is  inserted  into  the  femur  below  the  gluteus  maximus. 

Amygdalo-glossus. — A  small  muscle  which  arises  from  the  side  of  the  tongue  and  is  inserted 
into  the  outer  surface  of  the  tonsil. 

The  anomalus  arises  from  the  nasal  process  of  the  maxilla,  beneath  the  levator  lahii  superior  is 
akeqne  nasi.'    It  is  inserted  into  the  maxilla  close  to  the  origin  of  the  compressor  nan's. 

The  atlanto-mastoid  arises  from  the  transverse  process  of  the  atlas,  between  the  superior 
oblique  and  the  rectus  capitis  lateralis.  It  is  inserted  into  the  posterior  part  of  the  mastoid 
process. 

Azygos  pharyngis. — This  muscle  arises  from  the  pharyngeal  tubercle  on  the  under  surface 
of  the  body  of  the  occipital  bone. 

It  is  inserted  into  the  raphe  of  the  pharynx  supei^ficial  to  the  insertion  of  the  superior  and 
middle  constrictor  muscles.  It  may  blend  with  the  ascending  fibres  of  the  middle  constrictor.  It 
is  often  represented  by  a  fibrous  band.  [For  figure,  see  Macalister,  Proc.  Royal  Irish  Academy, 
vol.  ix.  ] 

The  chondro-epitrochlearis  arises  from  the  cartilages  of  one  or  two  ribs  (usually  the  seventh), 
or  from  the  aponeurosis  of  the  external  oblique  muscle. 

It  is  inserted  into  the  fascia  on  the  inner  side  of  the  aiiu,  or  into  the  intermuscular  septum, 
and  sometimes  into  the  internal  condyle  of  the  humerus.  [For  figure,  see  Perrin,  Journ.  of 
Anat.  and  Pliys.  vol.  v.  plate  ix.] 

The  cleido-hyoid  arises  from  the  clavicle  near  the  outer  border  of  the  sterno-hj'oid. 

It  is  inserted  into  the  body  of  the  hyoid  superficial  to  the  sterno-hyoid. 

The  cleido-occipitalis  arises  from  the  clavicle  posterior  to  the  sterno-mastoid  and  anterior 
or  external  to  the  cleido-mastoid.  It  runs  upwards  parallel  with  the  posterior  border  of  the 
sterno-mastoid  to  be  inserted  into  the  su]ierior  nuchal  line  of  the  occipital  bone  anterior  to  the 
origin  of  the  trapezius.      [Perrin  ;  a  good  figure  in  Journ.  of  Anat.  and  Pliys.  vol.  v.  p.  253.] 

The  costo-coracoideus  arises  from  one  or  more  ribs,  between  the  pectoralis  major  and  the 
latissimus  dorsi,  and  is  inserted  into  the  coracoid  ]irocess. 

The  costo-fascialis  is  a  muscular  slip  given  off  from  the  outer  border  of  the  sterno-thyroid 
near  its  origin. 

It  is  in.<serted  into  the  sheath  of  the  carotid  vessels,  and  sometimes  reaches  as  high  as  the  level 
of  the  thyroid  curtilage. 

The  curvator  coccygis  arises  from  the  anterior  surface  of  the  fifth  piece  of  the  sacrum. 

It  is  inserted  into  tlie  anterior  surface  of  the  coccyx.  [For  figure,  see  M.  Watson,  Journ. 
of  Anat.  and  PJiys.  vol.  xiv.  p.  407.] 

The  depressor  thyroideae  arises  from  the  lower  border  of  the  first  ring  of  the  trachea  quite 
clo.se  to  the  middle  lini'. 

It  passes  vertically  upwards  to  be  inserted  into  the  lower  border  of  the  thyroid  cartilage  inter- 
nal to  the  crico-thyroid.  [The  muscle  is  figured  by  Messeneer  Bradlov  in  Joirrn.  of  Anat.  and 
P/iys.  vol.  vi.  p.  420.] 

The  dorso-epitrochlearis  is  a  muscular  slip  given  off  by  the  tendon  of  the  latissimus  dorsi  at 
the  axilla.     Sometimes  it  is  directly  continuous  with  a  chondro-epitroeldearis  muscle. 

It  is  inserted  into  the  long  head  of  the  triceps,  or  into  the  fascia  of  the  arm,  and  sometimes 
into  the  internal  interuuiscular  sei)tum.  [For  figure,  see  Perrin,  Journ.  of  Anat.  and  Phys. 
vol.  V.  plate  X.] 

The  epitrochleo-anconeus  is  a  small  muscle  arising  from  the  back  of  the  internal  condyle  of 
the  humerus,  and  passing  over  the  ulnar  nerve  is  inserted  into  the  inner  side  of  the  olecranon. 

458 


ABNORMAL  MUSCLES  459 

This  is  the  most  frequent  of  all  the  muscles  to  which  the  term  '  abnormal '  is  applied.  [For 
figure,  see  \\'()0(l,  Pj-oc  Roy.  Soc.  vol.  xv.  p.  521.] 

The  extensor  annularis  arises  from  the  posterior  surface  of  the  ulnar  shaft  below  the  ex- 
tensor indicis.  Wheu  an  extensor  medius  is  also  present,  it  will  arise  in  common  with  the 
annularis. 

The  teudon  pa.sses  under  the  annular  ligament  with  the  common  extensor,  and  is  inserted 
into  the  tendun  of  the  ring  (fourth)  linger. 

The  extensor  brevis  digitorum  manus  arises  from  the  ligamentous  tissues  on  the  back  of  the 
carpus,  or  from  one  of  the  bones  of  the  forearm,  or  from  the  posterior  annular  ligament.  It 
pa.sses  under  the  posterior  annular  ligament,  and  gives  off  three  slips  which  blend  with  the 
tendons  of  the  third,  fourth,  and  fifth  iligits. 

The  extensor  carpi  radialis  accessorius  arises  from  the  humerus  below  the  extensor  carpi 
radialis  longior. 

It  is  inserted  into  the  metacarpal  bone  of  the  thumb,  or  into  the  abductor  pollicis,  or  into  the 
first  dorsal  interosso(jus  muscle. 

Extensor  carpi  radialis  intermedius. — This  muscle  usually  arises  from  one  or  both  the 
radial  exten.sois  of  the  carpus,  and  more  rarely  from  the  humerus.  It  is  inserted  into  the  second 
or  third  metacarpal  bone. 

The  extensor  coccygis  arises  from  the  posterior  surface  of  the  last  piece  of  the  sacrum. 

It  is  inserted  into  the  posterior  .surface  of  the  coccyx. 

The  extensor  medii  digiti  arises  from  the  ulna  below  the  extensor  indicis,  or  from  the  pos- 
terior annular  ligament.     It  is  inserted  into  the  extensor  exi)ansion  of  the  middle  finger. 

The  extensor  ossis  metatarsi  hallucis  arises  as  a  slip  from  the  extensor  proprius  hallucis  or 
from  the  extensor  ce/inmiinis  diyitorum,  or  from  the  tibialis  anticus.  It  may  arise  as  a  separate 
muscle  close  to  the  extensor  proprius. 

It  is  inserted  into  the  metatarsal  bone  of  the  hallux. 

The  extensor  primi  internodii  hallucis  longus  is  usually  an  oifset  from  the  extensor  jwopriiis, 
but  it  may  arise  separately  from  the  fibula  and  intero-sseous  membrane  or  from  the  tibialis  anticus. 

It  is  inserted  into  the  inner  part  of  the  base  of  the  first  phalanx  of  the  hallux.  [See  Wood, 
Proc.  Rfj}/.  Soc.  vol.  XV.  p.  .535.] 

The  flexor  accessorius  longus  arises  from  the  fascia  over  the  flexor  longus  hallucis,  or  fi'om 
the  fibula  or  tibia  ;  it  pa.sses  with  the  tendon  of  this  muscle  beneath  the  internal  annular 
ligament ;  and  ends  in  a  tendon  which  crosses  the  long  plantar  ligament  obliquely,  to  be 
inserted  into  the  sesamoid  bone  in  the  tendon  of  the  pjeroneus  longus,  or  it  joins  tlie  long  flexor 
or  the  accessorius. 

When  this  muscle  is  present,  the  acces.sorius  is  sometimes  absent.  [For  figure,  see  Thane, 
Proc.  Ann t.  Soc.  of  Gt.  Britain  and  Ireland,  May  IS'Jl.'] 

The  flexor  carpi  radialis  brevis  vel  profundus  arises  from  the  front  surface  of  the  radius 
near  the  anterior  border,  above  the  pronator  quadratus,  but  below  the  flexor  longus  pollicis. 

The  insertio/i  is  veiy  variable  :  in  some  cases  it  onlj'  reaches  the  annular  ligament,  whilst  in 
others  itija.sses  under  this  structure  to  be  inserted  into  the  trapezium,  magnum,  or  the  base  of  the 
second  or  third  metacarpal  bones.  [For  figure,  see  Wood,  Journ.  of  Anat.  and  P/ii/s.  vol.  i.  p. 
57.] 

The  gluteo-perinealis  arises  from  the  fascia  at  the  lower  border  of  the  gluteus  maximus.  It 
joins  the  transversu.s  {lerinei  or  is  inserted  into  the  triangular  ligament. 

The  gluteus  quartus  arises  from  the  anterior  part  of  the  inferior  gluteal  ridge  of  the  ilium  ; 
it  lies  in  close  contact  with  the  capsular  ligament  of  the  hip-joint. 

It  is  inserted  into  the  top  of  the  great  trochanter  of  the  femur  anterior  to  the  insertion  of  the 
gluteus  minimus.     [For  good  figure,  see  Graber,  Virchoiv  Arch.  bd.  cvii.  s.  480.] 

Hyo-epiglottideus. — This  muscle  arises  from  the  middle  of  the  ridge  on  the  lingual  aspect  of 
the  epiglottis. 

It  is  inserted  into  the  median  tubercle  on  the  body  of  the  hyoid  bone.  It  is  often  represented 
by  n  fibrous  Vjand.     [See  Journ.  of  Anat.  and  PInjs.  vol.  xxiii.  p.  256.] 

The  iliacus  minor,  or  ilio-capsularis,  arises  from  the  anterior  inferior  spine  of  the  ilium. 

It  is  inserted  itito  the  lower  part  of  the  anterior  intertrochanteric  line,  or  into  the  ilio-femoral 
portion  of  the  capsule. 

The  interclavicular  muscle  usually  consists  of  two  fleshy  bellies  with  a  stout  intermediate 
tendon.  It  arise^s  from  the  clavicle,  anteiior  to  the  attachment  of  the  rhomboid  ligament  and 
from  the  ligament  itself 

It  is  inserted  into  a  corresponding  position  on  the  opposite  clavicle,  and  fllls  up  the  gap  be- 
tween the  .sternal  ends  of  the  clavicles.     [Lane,  Journ.  of  Anat.  and  Pht/s.  vol.  xx.  j).  544.] 

The  interosseus  primus  volaris  is  a  slender  muscle  arising  from  the  ulnar  side  of  the  base  of 
the  first  metacarpal  bone. 

It  is  inserted  into  the  side  of  the  base  of  the  first  phalanx  of  the  thumb  in  common  with  the 
adductor  pollicis. 

Its  origin  and  insertion  are  marked  in  fig.  1,35,  p.  130. 

The  ischio-aponeuroticus,  or  tensor  fasciae  cruralis,  arises  from  one  of  the  hamstring  muscles, 
and  is  inserted  into  the  fascia  on  the  back  of  the  leg. 

Kerato-thyroid. — A  short,  slender  muscle  arising  from  the  lower  border  of  the  cricoid  carti- 
lage behind  the  articular  facet. 

It  is  inserted  into  the  inferior  cornu  of  the  thyroid  cartilage. 


460  THE  MUSCLES 

Tile  levator  claviculae  arises  iVoiii  tlie  transver.se  jtrocesses  of  the  first  and  second  cen'ical 
vertebrae  ;  it  appears  as  a  disLuemberment  of  the  levator  avgtiJi  scaj-)ula'. 

It  is  inserted  into  the  outer  half  of  the  daviele. 

Levator  glandulae  thyroideae. — This  muscle  arises  from  the  isthmus,  but  more  frequently 
from  the  i\yraiuidal  process  uf  the  thyroid  body. 

It  is  inserted  into  the  anterior  .surface  of  the  body  of  the  hyoid  bone.  Frequently  it  is  con- 
nected with  the  thyro-hyoid  muscle,  and  occasionallj^  with  the  sterno-thyroid. 

The  mento-hyoideus  is  a  slip  of  muscle  which  arises  from  the  body  of  the  hyoid  bone. 
Sometimes  it  consists  of  two  parallel  slips. 

It  is  inserted  into  the  symphysis  superficial  to  the  mj'lo-hyoid  muscle. 

The  mylo-glossus,  a  small  accessory  .slip  of  the  stj'lo-glossus,  arises  from  the  angle  of  the 
mandible,  or  from  the  stylo-maxillarj'  ligament. 

It  is  inserted  into  the  side  of  the  tongue  between  the  stylo-  and  h3'o-glossus  muscles.  [For 
figure,  see  Wood,  Proc.  Roy.  Soc.  vol.  xv.  p.  52-3.] 

Obliquus  inferior  accessorius. — A  small  muscular  slip  which  passes  from  the  inferior  rectus 
to  the  inferior  oblique  muscle. 

The  occipitalis  minor  arises  from  the  fascia  over  the  occipital  origin  of  the  trapezius  and 
terminates  in  the  fascia  over  the  insertion  of  the  sterno-mastoid. 

The  occipito-hyoid  arises  from  the  ma.stoid  process  of  the  temporal  bone  and  adjacent 
portion  of  the  superior  nuchal  line.  It  passes  superficially  across  the  sterno-mastoid  near  its 
origin,  to  be  inserted  into  the  hyoid  bone  near  the  junction  of  the  cornua  with  the  basi-hyoid, 
and  in  close  a.ssoeiation  with  the  posterior  bellj'  of  the  digai?tric.  [Perrin  :  good  figures  in  Journ. 
of  Anat.  and  Phtjs.  vol.  v.  pp.  251-3.] 

The  occipito-scapular,  or  rhomboideus  occipitalis,  arises  from  the  occipital  bone  on  a  level 
with  the  si)lenius  capitis  under  cover  of  the  trapezius.  It  passes  downwards  to  be  inserted  into 
the  posterior  border  of  the  scapula  at  the  base  of  the  spine.  [For  figure,  see  Wood,  Proc. 
Roil.  Soc.  vol.  XV.  p.  521.] 

The  opponens  hallucis  arisen  from  the  oblique  adductor  of  the  great  toe,  and  is  inserted  into 
the  first  metatarsal  bone. 

The  opponens  minimi  digiti  pedis  arises  from  the  flexor  brevis  minimi  digiti  and  is  inserted 
into  the  fifth  metatarsal  bone. 

Pectoralis  minimus. — A  rare  muscle  which  arises  fi'om  the  cartilage  of  the  first  rib,  and  is 
inserted  into  the  coracoid  process. 

The  peroneo-calcaneus  internus  arises  from  the  lower  part  of  the  flexor  (posterior)  surface 
of  the  fil:)ula,  external  to  the  origin  of  the  flexor  longus  hallucis.  Its  tendon  passes  beneath 
the  internal  annular  ligament  with  the  tendon  of  the  flexor  longus  hallucis,  to  be  inserted  into  the 
fore  part  of  the  inner  .surface  of  the  calcaneum.  [For  figure  and  reference,  see  Thane,  Proc. 
An'at.  Soc.  of  Gt.  Britain  and  Ireland,  May  1891.] 

The  peroneo-tibialis  arises  from  the  inner  side  of  the  head  of  the  fibula. 

It  is  in.serted  into  the  upper  extremity  of  the  oblique  line  of  the  tibia  beneath  the  pop- 
liteus. 

The  peroneus  accessorius  arisen  from  the  fibula,  between  the  peroneus  longus  and  the  pero- 
neus  brevis.  and  joins  the  tendon  of  the  longus  in  the  sole  of  the  foot. 

The  peroneus  quartus  arises  from  the  flexor  surface  of  the  fibula  between  the  peroneus  brevis 
and  flexor  longus  hallucis. 

It  is  inserted  into  the  ridge  of  the  cuboid,  peroneo-cuboideus,  or  into  the  peroneal  tubercle 
of  the  calcaneum,  peroneo-calcaneus  externus. 

The  peroneus  quinti  digiti  arises  from  the  lower  fourth  of  the  fibula  under  cover  of  the 
peroneus  brevis. 

It  is  inserted  into  the  aponeurosis  on  the  extensor  surface  of  the  little  toe.  [Wenzel  Gruber 
has  devoted  a  monograph  to  this  muscle,  entitled  Musculus  Peronei  Digiti  Y.     Berlin,  1886.] 

The  petro-pharyngeus  arises  from  the  vaginal  process  of  the  temporal  bone  and  is  inserted 
into  the  pharynx. 

The  pharyngo-mastoideus  arises  from  the  mastoid  process  and  is  inserted  into  the  pharynx. 

The  pisi-annularis  arises  from  the  pisiform  bone  and  is  inserted  into  the  annular  ligament. 

The  pisi-metacarpeus  arises  from  the  ]iisiform  bone  and  is  inserted  into  the  filth  metacarjial. 
It  fref|uently  forms  part  of  the  abductor  minimi  digiti. 

The  pisi-uncinatus  arises  from  the  pisiform  bone  and  is  inserted  into  the  hook  of  the  unci- 
form. 

The  popliteus  minor  arises  from  the  femur  to  the  inner  side  of  the  ]>lantaris. 

It  is  inserted  into  the  posterior  ligament  of  the  knee-joint. 

The  psoas  parvus  arises  from  the  bodies  of  the  last  thoracic  and  finst  lumbar  vertebrae  and 
from  the  ilisc  between  them. 

It  is  inserted  by  means  of  a  thin  flat  tendon  into  the  ilio-]iectineal  line.  This  muscle  is  fre- 
quently present. 

The  pterygoideus  proprius  ari.'<es  fiom  the  crest  on  the  greater  wing  of  the  sphenoid. 

It  is  inserted  into  the  posterior  border  of  the  external  pterj'goid  plate,  and  occasionally  into 
the  tuberosity  of  the  maxilla.  [For  figure,  see  Wagstaffe,  Jnurn.  of  Anat.  and  Phys.  vol.  v.  p. 
282.] 

The  pterygo-pharyngeus  externus  arises  from  the  hamular  process  of  the  sphenoid  bone  and 
is  inserted  into  the  pharynx. 


ABNORMAL   MUSCLES  461 

The  pterygo-spinous  arises  from  the  ahir  spine  of  the  sphenoid. 

It  is  inserted  into  the  posterior  margin  of  the  external  pterygoid  plate.  This  muscle  is  some- 
times replaced  bj'  linrament. 

The  pubo-transversalis  arises  from  the  ilio-pectineal  line  behind  the  conjoined  tendon,  and 
is  inserted  into  the  traiisversalis  lascia,  the  aponeurosis  of  the  transversalis  muscle  or  the  outer 
end  of  the  st'niilutiar  fold  of  Douglas. 

Rectus  abdominis  lateralis. — This  muscle  consists  of  vertical  fibres  passing  from  the  lower 
ribs  to  the  upper  ])art  <jf  tlie  ilium  between  the  oblique  abdominal  muscles. 

The  rectus  capitis  amicus  medius  arises  from  the  middle  of  the  anterior  surface  of  the  body 
of  the  axis  near  its  lower  border  by  means  oi'a  tendon.  As  it  passes  vertically  upwards,  it  bifur- 
cates, each  flesh}'  belly  being  inserteil  into  the  basilar  jiroce.ss  of  the  occipital  bone  immediately  in 
front  of  the  foramen  magnum,  posterior  to  the  insertion  of  the  rectus  capitis  anticus  major,  and 
internal  to  that  of  the  rectus  capitis  anticus  minor.  [Walsham,  Journ.  of  Anat.  and  Phys.  vol. 
xviii.  p.  461.] 

The  rhombo-atloideus  arises  fi'om  the  lower  cervical  or  upi)er  dorsal  spines,  superficial  to  the 
serratus  p(.)sticus  superior,  and  is  inserted  into  the  transverse  process  of  the  atlas. 

The  rotator  humeri  arises  from  the  under  surface  and  outer  border  of  the  coracoid  process  of 
the  sca}iula. 

It  pa.sses  across  the  tendon  of  the  subscapularis,  to  be  inserted  into  the  neck  of  the  humerus, 
below  the  lesser  tuberosity,  and  between  the  in.sertions  of  the  subscapularis  and  the  conjoined 
tendons  of  the  latissimus  dorsi  and  teres  major  muscles. 

The  rotator  humeri  is  a  part  of  the  coraco-brachialis  muscle,  and  is  often  referred  to  as  the 
coraco-brachialis  superior  vel  brevis.  [For  figure,  see  Wood,  Journ.  of  Anat.  and  Phys.  vol. 
i.  p.  47.]     The  insertion  of  this  mu.scle  is  indicated  in  fig.  125. 

The  spheno-pharyngeus  arises  from  the  spine  of  the  sphenoid  and  is  inserted  into  the  wall 
of  the  pharynx. 

The  spinalis  cervicis  arises  from  the  ligamentum  nuchae  and  the  first  dorsal  spine.  It  is 
inserted  into  the  spine  of  the  axis,  and  occasionally  into  the  spines  of  the  third  and  fourth  cervical 
vertebrae. 

The  sternalis  muscle  (rectus  sternalis)  arises  from  the  sheath  of  the  rectus  abdominis,  or 
from  the  tissues  covering  tlie  fifth  and  sixth  costal  cartilages. 

The  direction  of  the  fibres  is  very  variable.  In  some  cases  they  are  directed  oblifiuely  out- 
wards ;  in  others,  they  pass  vertically  upwards  to  be  inserted  into  the  fascia  covering  the  origin 
of  the  sterno-mastoid,  or  into  the  aponeurosis  of  the  pectoralis  major,  or  into  the  upper  part  of 
the  manubrium  of  the  sternum.  A  sternalis  may  be  present  on  each  side.  In  some  instances 
they  are  entirely  muscular  ;  in  others,  furnished  with  terminal  tendons.  [See  Jouvii.  of  Anat. 
and  Phys.  vols.  i.  240.  xviii.  p.  208,  xix.  p.  311.] 

The  sterno-clavicularis  ai-ises  from  the  front  of  the  manubrium  sterni,  and  is  inserted  into 
the  clavicle,  between  the  pectoralis  major  and  the  costo-coracoid  membrane. 

The  stylo-auricularis  arises  from  the  cartilage  of  the  external  auditory  meatus  and  is 
inserted  into  the  styloid  process  of  the  stylo-glossus  mu.scle. 

The  subscapularis  minor  arises  from  the  axillary  border  of  the  scapula  and  is  inserted  into 
the  cap.sular  ligament  or  the  adjacent  part  of  the  inner  margin  of  the  bicipital  groove. 

The  supraclavicularis  anses  by  a  .slender  tendon  from  the  upper  border  of  the  manubrium 
of  the  sternum.  It  passes  outwards,  above  the  .sterno-clavicular  joint,  behind  the  sterno-mastoid 
muscle,  to  be  inserted  into  the  clavicle.  When  present  in  both  sides,  the  muscle  .sometimes  fuses 
in  the  middle  line. 

Supracostalis. — When  this  muscle  is  present  it  extends  from  the  anterior  end  of  the  first 
to  the  anterior  ends  of  the  third  or  fourth  ribs.  It  may  be  connected  also  with  the  deep  fascia 
of  the  neck  or  the  scalene  muscles. 

The  syndesmo-pharyngeus  ai-ises  from  the  lateral  thyro-hyoid  ligament  and  is  inserted  into 
the  mid<lle  constrietor. 

The  tibialis  secundus  arises  from  the  back  of  the  tibia  below  the  flexor  longus  digitorum 
and  is  inserted  into  the  back  of  the  capsule  of  the  ankle-joint  or  into  the  annular  ligament. 

The  tibio-fascialis  anticus  arises  from  the  lower  third  of  the  anterior  border  of  the  tibia. 

It  is  inserted  into  the  aniuilar  ligament  and  deep  fa.scia. 

Transversus  menti. — A  muscular  band  extending  between  the  adjacent  borders  of  the 
depressor  muscles  of  the  lower  li]i. 

The  transversus  nuchae  arises  from  the  external  occipital  protuberance  and  is  inserted  into 
the  fascia  of  the  sterno-mastoid. 

The  triticeo-glossus  arises  from  the  cartilago  triticea  in  the  thyro-hyoid  ligament. 

It  is  inserted  into  the  side  of  the  tongue,  blending  with  the  posterior  fibres  of  the  hyo- 
glossus. 

The  ulnaris  quinti  digiti  arises  from  the  lower  part  of  the  ulna  or  from  the  extensor  carpi 
ulnaris.  It  is  inserted  into  the  metacarpal  bone  of  the  little  finger  or  it  may  joiu  the  tendon  of 
the  extensor  minimi  disiti. 


SECTION    lY 

ARTERIES,  VEINS,  AND  LYMPHATICS 


By  W.  J.  WALSH  AM,  F.KC.S. 


SURGEON   TO  ST.    BARTHOLOMEW'S   HOSPITAL;   LECTURER   ON  SURGERY;    LATE    LECTURER    ON    ADVANCED    ANATOMY    IN 
ST.    BARTHOLOMEW'S    HOSPITAL   MEDICAL   SCHOOL,    ETC.,    ETC. 


THE    ARTERIES 

THE  arteries  are  divided  into  the  pulmonary  and  the  systemic.  The  pul- 
monary convey  the  blood  from  the  right  ventricle  of  the  heart  to  the  lungs, 
whence  it  is  returned,  when  aerated,  by  the  pulmonary  veins  to  the  left 
auricle,  and  through  that  cavity  into  the  left  ventricle.  The  systemic  arteries 
carry  the  blood  from  the  left  ventricle  all  over  the  body,  whence  it  is  returned  by 
the  vense  cavse  to  the  right  auricle,  and  through  it  to  the  right  ventricle.  The  lungs 
also  receive  blood  from  the  systemic  arteries — the  lironchial.  This  Idood  which 
serves  for  the  nourishment  of  the  larger  and  smaller  branches  of  the  bronchial 
tubes  and  the  lung  substance  is  returned,  in  part  by  the  bronchial  veins  to  the 
general  venous  circulation,  and  thence  to  the  right  side  of  the  heart;  and  in  part  by 
the  pulmonary  veins,  along  with  the  aerated  blood,  to  the  left  side  of  the  heart. 


THE  PUMIONARY  ARTERY 


The  pulmonary  artery  (fig.  317)  passes  from  the  right  ventricle  to  the  lungs. 
It  differs  from  all  other  arteries  in  the  body  in  that  it  contains  venous  blood.  It 
arises  as  a  short,  thick  trunk  from  the  upper  and  front  part  of  the  right  ventricle 
kn^wn  as  the  conus  arteriosus,  and,  after  a  course  of  about  two  inches  within  the 
pericardium — the  serous  layer  of  which  memlirane  forms  a  common  sheath  for  it 
and  the  aorta — divides  into  a  right  and  a  left  liranch.  These  branches  pierce  the 
pericardium,  and  pass  to  the  riglit  and  loft  lung  respectively. 

The  trunk  of  the  pulmonary  artery  at  its  origin  (fig.  319)  is  on  a  plane 
anterior  to  the  first  j^ortion  of  the  an;h  of  the  aorta,  and  slightly  overlaps  that 
vessel.  Tlionce  it  passes  upwards,  backwards,  and  to  the  left,  forming  a  sliglit 
curve  round  the  front  and  left  side  of  the  ascending  portion  of  the  aorta  (fig.  321); 
and,  having  reached  tlie  concavity  of  the  transverse  j)()rtion  of  the  aortic  arch,  on  a 
level  with  the  fifth  thoracic  vertebra,  and  on  a  ])lane  ]>osterior  to  the  ascending 
aorta,  it  divides  into  its  right  and  left  branches,  which  diverge  from  each  other  at 
an  angle  of  about  130°. 

462 


THE  PULMONARY 


463 


In  the  f(»tus,  the  puhiionarv  artery  (fig.  818)  continues  its  course  ui)\var(ls, 
hackwards,  and  to  the  left,  under  the  name  of  the  ductus  arteriosus,  or  ductus 
Botalli,  and  opens  into  the  descending  aorta  just  l)elo\v  tht-  origin  of  the  k-ft 
suhclavian  artery.  After  birth,  that  i)ortion  of  the  puhiionary  artery  whicli 
extends  to  the  aorta  becomes  obliterated,  and  remains  merely  as  a  fibrous  cord. 

The  trunk  of  the  artery  with  the  ductus  Botalli  was  originally  the  left  fifth 
aortic  arch,  and  the  recurrent  laryngeal  nerve  in  early  foetal  life  passed  below  it 
direct  to  the  larynx.  As  in  the  process  of  develo])ment  the  heart  descends  into  the 
tliorax,  and  the  fifth  arch  assumes  a  more  vertical  direction,  it  comes  to  pass  that 
the  nerve  winds  round  the  transverse  portion  of  the  aorta,  the  fourth  aortic  arch. 


Fig.  '317. — .\xterior  View  of  the  Heart  with  the  Large  Arteries  axd  Veins. 

(By  pennissiou.     Royal  College  of  Surgeons  Mn.seuni.) 

X^//  commnn 

carotid  artery    Internal  jugular  vein 
Right  superior  thyroid  vein    Left  superior 
Right  common  carotid  artery  i  thyroid  vein 

Internal  jugular  vein      |  |        THYROID 

Booy 
Vertebral  lein 


Left  vertebral  vein 


Sitbclavian  x-ein 
Inferior  thyroid  veins 

Vena  azygos  major 

Vena  cava  superioi 

Aorta 

Right  pulmonary  artery 

PERICARDIUM 
RIGHT  AURICLE L 

RIGHT  VENTRICLE 
Vena  cava  inferior 


External  jugular  vein 


Left  subclavian  vein 
Left  innominate  vein 


Left  superior  intercostal  vein 


DUCTUS  ARTERIOSUS 

Left  pulmonary  artery  and 

vein 
LEFT  AURICULAR  APPENDIX 

Pulmonary  artery 


LEFT  VENTRICLE 


and  consequently  external  to  the  ductus  arteriosus  (fig.  321).  In  adult  life  the  cord 
tormed  by  the  obliterated  ductus  arteriosus  arises  a  little  to  the  left  of  the  Vjifurca- 
tion  of  the  pulmonary  artery,  and  receives  a  slight  reflexion  from  the  pericardium 
as  it  pierces  that  membrane.      It  occasionally  remains  }iartially  unobliterated. 

Relations. — In  front,  the  trunk  of  the  pulmonary  artery  is  covered  by  the 
second  bone  of  the  sternum,  the  remains  of  the  thymus  gland,  and  the  jiericardium 
(fig.  319),  and  at  its  commencement  lies  immediately  l^ehind  the  anterior  extremity 
of  the  second  intercostal  space,  the  left  lung  and  ])leura  intervening. 

Behind,  it  lies  successively  upon  the  ascending  {)art  of  the  arch  of  the  aorta 
and  the  left  auricle. 


464 


THE  ARTERIES 


To  the  right  are  the  ascen«lin,tr  aorta,  the  riglit  aurieular  appendix,  the  right 
coronary  artery,  and  tlie  cardiac  nerves. 

To  the  left  are  the  pericardium,  the  left  pleura  and  lung,  the  left  auricular 
appendix,  the  left  coronary  artery,  and  the  cardiac  nerves. 


Fig.  318. — The  Heart,  with  the  Arch  of  the  Aorta,  the  Pulmonary  Artery,  the 
Ductus  Arteriosus,  and  the  Vessels  concerned  in  the  Fcetal  Circulation. 

(From  a  preparation  of  a  fcetus  in  the  Museum  of  St.  Bartholomew's  Hospitiil.) 


Right  innominate  vein 

I'fJia  cava  superior 
Xif/lit  pulmonary  artery 


Vena  cava  inferior 


Leji  branch  of  portal  vein 


Umbilical  vein 

Portal  rein 

Right  branch  of 
portal  vein 


Umbilical  vein 
Umbilical  arteries 

Ifypogastric  artery 


Left  innominate 
vein 


A  rch  of  aorta 

DUCTUS  ARTERIOSUS 

Left  pulmonary 
artery 


Descending  aorta 


y^  Superior 

mesenteric  artery 


Splenic  vein 

Superior 
mesenteric  vein 


Inferior 
mesenteric  artery 


Left  common  iliac 
artery 


Internal  iliac  artery 
External  iliac  arte.ru 


THE  PvIGHT  PULMONARY  ARTERY 

The  right  pulmonary  artery  (figs.  319  and  320),  longer  than  the  left,  passes 
almost  horizontally  outwards  under  the  arch  of  the  aorta  to  the  root  of  the  right 


THE  PULMONARY 


465 


Fig.  319. — Diagram  of  the  Kelations  of  the  Pllmoxary  Akteky  and  it.s  Right 
ANi>  Left  Bkaxches.     iWalsham.) 


RIGHT  PSEVMOQASTRIC 
NER  VE 

Vena  azygos  major 

RIGHT  BRONCHUS 

Riijht  pulmonary  artery 

RIGHT  PHRENIC  NERVE 

Vena  cava  superior 

PERICARDIUM 

RIGHT  AURICULAR  APPENDIX 

RhjIU  cwonary  artery 

RIGHT  PLEURA  AND  LUNG 


Aorta 

THORACIC  DUCT 

(ESOPHAGUS 

L  EFT  PNE  UMO  GA  S  TRIC 

LEFT  BRONCHUS  [NERVE 

Left  pulmonary  artery 


LEFT  PHRENIC  NERVE 

Pulmonary  artery 

PERICARDIUM 

LEFT  PLEURA  AND  LUNG 

SECOND  BONE  OF  STERNUM 


Fig.  320. — Posterior  View  of  Heart  and  Greater  Vessels. 

(By  permission.     Royal  College  of  Surgeons  Museum.) 

Left  common  carotid  artery 
Left  vertebral  rein 


Superior  thyroid      „.  , . 

i,/j.„  Right  common  carottd  artery 


THYROID  BODY 


External  jugular  vein 

Ascending  cervical 
artery 
Thyroid  axis 

Vertebral  artery 

Left  subclavian  vein 

Left  subclavian  artery 

Internal  mammary 

artery 

Lfft  common  carotid 

artery 


Aorta 

Left  superior  intercostal 

rein 

Ductus  arteriosus 

Pulmonary  arteriei 

Upper  left  pulmonary 
veins 

LEFT  AURICULAR 
APPENDIX 


Lower  left  ptdmonary 
vein 


Right  internal  jugular  vein 

!      External  jugular  vein 

'Inferior  thyroid  veins 


Right  subclavian 
artery 

Right  subclavian  vein 

Right  innominate 
vein 

Innominate  artery 
Vena  azygos  major 


Vena  cava  superior 

PERICARDIUM 
Pulmonary  arteries 


Pulmonary  arteries 


Z^ncer  right  pulmonary 
vein 


Vena  cava  inferior 


30 


466  THE  ARTERIES 

lung,  where  it  divides  into  a  larger  upper  braneh,  which  sujjplies  the  ui)i)er  lobe 
and  gives  off  a  descending  branch  to  the  middle  or  third  lobe,  and  into  a  smaller 
inferior  branch  for  the  supply  of  the  inferior  lol^e.  These  branches  follow  the 
course  of  the  bronchi,  dividing  and  subdividing  for  the  supply  of  the  lobules  of  the 
lung.     The  terminal  branches  do  not  anastomose  with  each  other. 

Relations. — In  its  course  to  the  lung  it  has  in  front  of  it  (fig.  319)  the 
ascending  aorta,  the  vena  cava  superior,  the  ])hrenic  nerve,  the  anterior  pulmonary 
plexus,  and  the  reflexion  of  the  pleura.  Behind  are  the  right  bronchus  and 
the  termination  of  the  vena  azygos  major.  Above  is  the  transverse  portion 
of  the  arch  of  the  aorta,  and  below  are  the  left  auricle  and  the  uj)per  right 
pulmonary  vein. 

At  the  root  of  the  lung  it  lias  the  right  bronchus  above  and  behind  it;  the 
l)ulmonary  veins  below  and  in  front.  Crossing  in  front  of  it  and  the  other  struc- 
ture forming  the  root  of  the  lung  are  the  phrenic  nerve  and  the  anterior  ])ulmonary 
plexus;  behind  are  the  vena  azygos  major,  the  pneumogastric  nerve,  and  the 
posterior  pulmonary  plexus  (fig.  324). 


THE  LEFT  PULMONARY  ARTERY 

The  left  pulmonary  artery,  shorter  and  slightly  smaller  than  the  right,  passes 
in  front  of  the  descending  aorta  to  the  root  of  the  left  lung,  where  it  divides  into 
two  branches  for  the  supply  of  the  upper  and  lower  lobes  respectively.  These 
divide  and  subdivide  as  on  the  right  side  (fig.  319). 

Relations. — At  the  root  of  the  lung  it  has  the  left  bronchus  behind  and  also 
below  it  in  consequence  of  the  more  vertical  direction  taken  by  the  left  l)ronchus 
than  l)y  the  right.  Below  and  in  front  are  the  pulmonary  veins,  while  between 
the  artery  and  the  ui)per  left  pulmonary  vein  the  vestigial  fold  of  Marshall  is  to  be 
seen.  Crossing  in  front  of  it  and  the  other  structures  forming  the  root  of  the  lung 
are  the  phrenic  nerve,  the  anterior  pulmonary  plexus,  and  the  reflexion  of  the  left 
pleura;  crossing  behind,  are  the  descending  aorta,  the  left  pneumogastric  nerve, 
and  the  posterior  pulmonary  plexus  (fig.  324). 


THE   SYSTEMIC   ARTERIES 


THE  AOBTA 

The  aorta  is  the  main  systemic  arterial  trunk,  and  from  it  all  the  systemic 
arteries  are  derived.  It  begins  at  the  left  ventricle  of  the  heart,  and,  after  running 
a  short  distance  upwards  and  to  the  right,  turns  backwards  and  to  the  left,  and 
then  downwards,  forming  the  arch  of  the  aorta.  It  is  thence  continued  through 
the  thorax  as  the  thoracic  aorta,  and  finally  enters  the  abdomen  at  the  aortic 
opening  in  the  dia])lirngm,  and.  passing  through  the  abdominal  cavity  under  the 
name  of  the  abdominal  aorta,  terminates  opposite  the  foiu'th  lum])ar  verte1)ra  in 
the  right  and  left  coiumon  iliac  arteries.  From  the  point  of  l)ifurcation  a  small 
vessel  is  continued  down  the  middle  line  in  front  of  the  sacrum  and  co(>cyx,  and 
ends  in  the  coccygeal  glomerulus.  This  vessel  (known  as  the  middle  sacral)  is 
iisually  regarded,  mor])hologically,  as  the  sacral  and  coccygeal  aorta;  while  the 
coccygeal  glomerulus  is  believed  to  represent  the  rudiments  of  the  caudal  aorta, 
with  probably  a  persistent  part  of  the  post-anal  gut. 


THE  ARCH  OF  THE  AORTA 


467 


THE  ARCH  OF  THE  AORTA 

The  arch  of  the  aorta  (fig.  321)  begins  at  the  upper  and  back  part  of  the  left 
ventricle  of  the  heart,  Ijehind  the  sternum,  on  a  level  with  the  lower  border  of  the 
third  left  costal  cartilage.  Thence  it  passes  upwards  and  slightly  forwards  and  to 
the  right,  as  high  as  the  level  of  the  upper  l)order  of  the  second  costal  cartilage  of 


Fig.  321. — Tjie  Akch  of  the  Aorta,  with  the  Pulmonaky  Aktkry  and  Chief 

Branches  of  the  Aorta. 


(From  a  dissectiou  in  St.  Bartholomew's  Hospital  Mnseniii.1 
RTGHT  RECUR- 

j;i:xT  LA  It  y.y- 

OEAL  SERVE 

Transvise  c.rcical 

ailenj 

Right  common  can  I  id     _- 

ttrtery 
Suprascapular  art  i  >/  — 


Internal  jugular  k  in  — 

PXEUMOOASTPIf    - 
SER  VE 
Subclavian  ttin 

Inferior  thyroid  ifin 

PIIREXIC  NER  I  E 

Left  innominate  rein  — 

Ascending  ac>  1 1 

Superior  renn  cita 

RIGHT  BRONCHUS 


Branch  to  superior  I  tb 
of  luug 
Upper  branch  of  ri /hi 

Ijulinonarji  arterii 
Branch  to  middle  lobe 

of  lung 
Right  pulmonary  vein 

RIGHT  AURICLE 

Right  coronary  arti  >  1/ 
Lower  branch  nf  right 
pulmonary  artery 
THORACIC  VERTEBRA 

Litercostal  vein 

Intercostal  arleiy 

Vena  uzygos  major 

Intercostal  vein 
Intercostal  artei  y 

Intercostal  vein 
Intercostal  artery 


THYROID  BODY 
L EFT  RECUR Rh X T 
LARYXGEAL 
XKRVE 
I-XEUMOGASTRIC 

XER  VE 
Left  internal  jugular 

vein 
Left  common  carotid 
urlery 
~    Left  subclavian  artery 

~   Left  subclavian  vein 

TRACHEA 

~    Inferior  thyroid  i-ein 

_    PHREXIC  XERVE 

( hooked  aside) 
REriRREXT 
LARYXGEAL 
XERVE 
PXEUMOGASTRIC 

XERVE 
DUCTUS  ARTERIOSUS 

Left puhnoiiary  artery 

!':ilrnonary  artery 

Right  pulmonary 
artery 

LEFT  BRONCHUS 

Left  coronary  artery 

Ujiper  left  pulmonary 

vein 
'.  GHT  VENTRICLE 

'  'onus  arteriosvs) 
I.  II  er  left  pulmonary 

artery 
Loner  left  pulmonary 

vein 
ISaPHAGUS 
(/looked  aside) 


THORACIC  DUCT 
Thoracic  aorta 


the  right  side;  and  then,  curvdng  backwards,  upwards,  and  to  the  left,  crosses 
behind  the  sternum  at  the  level  of  the  middle  of  the  manubrium;  and,  reaching  the 
left  side  of  the  l)ody  of  the  fourth  thoracic  vertel^ra,  runs  downwards  on  the  side  of 
the  body  of  that  and  the  fifth  thoracic  vertebra,  at  the  lower  border  of  which  it  ter- 
minates in  the  thoracic  aorta.  The  arch  thus  formed  has  its  convexity  upwards 
and  to  the  right;  in  its  concavity  are  situated  the  left  bronchus  and  the  riglit  pul- 
monary artery.  According  to  its  direction,  it  is  somewhat  arlntrarily  divided  into 
an  ascending,  transverse,  and   descending  part.     jNIorphologically,   the  ascending 


468 


THE  ARTERIES 


portion  is  the  ventral  aorta;  the  descending  portion,  part  of  the  left  dorsal  aorta; 
and  the  transverse  portion,  the  fourth  left  aortic  arch.  Each  portion  requires  a 
separate  description. 

The  Ascending  Portion  of  the  Arch  of  the  Aorta 

The  ascending  portion  or  ventral  aorta  ascends  behind  the  sternum  from  the 
upper  part  of  the  left  ventricle  of  the  heart,  on  a  level  with  the  lower  border  of 
the  third  left  costal  cartilage,  to  the  upper  border  of  the  second  right  costal  carti- 
lage at  the  junction  of  these  cartilages  Avith  the  sternum.  It  measures  from  two 
to  two  and  a  quarter  inches  (5 '5  cm.),  forming,  as  it  ascends,  a  gentle  curve,  the 
most  prominent  part  of  which,  when  the  aorta  is  distended,  is  situated  about 
a  cpiarter  of  an  inch  (6  mm.)  from  the  sternum.     It  is  enclosed  for  the  greater 


Fig.  322. — Scheme  of  the  Relations  of  the  First  Portion  of  the  Arch  of  the  Aorta. 

(Walsham.) 

I,  at  origin  :  II,  a  little  higher  up. 
1 


RIGHT  AURICLE 


RIGHT  AURICULAR  APPENDIX 


Pulmonary  artery 


II 


RIGHT  BRONCHUS 
Right  pulmonary  artery 


Vena  cava  superior 


PERICARDIUM 

RIGHT  PLEURA 

RIGHT  LUNG 


Ltfl  pulmonary  artery 


Pulmonary  artery 
PERICARDIUM 

LEFT  LUNG 

LEFT  PLEURA 

REMAINS  OF  THYMUS   GLAND 


-   MANUBRIUM 


part  of  its  length  in  the  pericardium,  being  invested,  together  with  the  pulmonary 
artery,  in  a  connnon  sheath  formed'  by  the  serous  layer  of  that  membrane.  A 
dilatation  known  as  the  great  sinus  of  the  arch  of  the  aorta  is  often  present 
along  the  right  side.  Immediately  above  the  heart  the  aorta  presents  three  bulg- 
ings,  known  as  the  sinuses  of  Valsalva;  they  are  placed,  two  anteriorly,  and  one 
posteriorly.  From  the  anterior  are  derived  the  coronarv  arteries  of  the  heart. 
(SeeHEAUT. ) 

Relations. — In  front  (fig.  o22),  it  is  over]ap])cd  at  its  commencement  by  the 
right  auricular  ap])en(lix  and  the  pulmonary  artery.  Higlierup,  as  the  pulmonary 
artery  and  auricular  ai)pen(lix  diverge,  it  is  separated  from  the  manul)rium  l)y  the 
pericardium,  the  remains  of  the  thymus  gland,  and  by  the  loose  tissue  and  fat  in 
the  superior  mediastinum,  and  is  here  slightly  overlap})ed  by  the  right  pleura  and 
by  the  edge  of  the  right  lung  in  full  inspiration.  The  commencement  of  the  coro- 
nary arteries  is  also  in  front. 


THE  ARCH  OF  THE  AORTA 


400 


Behind  are  the  left  auricle  of  the  heart,  the  right  pulmonary  artery,  the  right 
bronchus,  and  the  anterior  right  deep  cardiac  nervc;^. 

On  the  right  side  it  is  in  contact,  below  with  the  right  auricle,  and  aV)Ove  with 
the  su})eritn-  vena  cava. 

On  the  left  side  are  the  pulmonary  artery  and  the  branches  of  the  right  super- 
ficial cardiac  nerves. 

The  Transverse  Portion  of  the  Arch  of  the  Aorta 

The  transverse  portion  of  the  arch  of  the  aorta  extends  in  a  gentle  curve 
upwards,  backwards,  and  to  the  left,  from  the  level  of  the  ujtper  l;>order  of  the 
second  right  costal  cartilage  to  the  left  side  of  the  body  of  the  fourth  thoracic 
vertebra.  Passing  under  the  arch  are  the  left  bronchus,  the  right  pulmonary 
artery,  and  the  left  recurrent  laryngeal  nen'e.  It  measures  about  one  inch  au'l 
four-rifths  (4-0  cm.). 

Relations. — In  front  (fig.  323),  it  is  slightly  overlapped  by  the  right  pleura 


Fig.  3-23. — Scheme  of  the  Relations  of  the  Transverse  Portion  of  the 
Arch  of  the  Aorta.     (Walsham.) 


(ESOPHAGUS 

TRACHEA 
Left  carotid  artery 
Innominate  artery 


RIGHT  PLEURA 
RIGHT  LUNG 


THORACIC  DUCT 

LEFT  RECL'EREXT  LARYSGEAL  SERVE 

Left  subclavian  artery 

Lfft  superior  intenostal  vein 

P'SELMOGASTRIC  SERVE 

rARDHC  BRASCHES  OF  SYMPATHETir 

CARDIAC  BRAXCHES  OF  PXEUMOGA-^TRIC 

PHREXIC  XER  VE 

left  lung 

Right  pleura 


and  lung,  and  to  a  greater  extent  by  the  left  pleura  and  lung.  It  is  crossed  in  the 
following  order  from  right  to  left,  by  the  phrenic  ner\-e,  by  the  cardiac  branches  of 
the  pneumogastric  nerve,  the  cardiac  branches  of  the  sympathetic  nerve,  by  the 
pneumogastric  ners'e,  and  by  the  left  superior  intercostal  vein  as  it  passes  up  to  the 
left  innominate  vein. 

Behind  it  (fig.  323)  are  the  trachea,  the  cesophagus.  the  thoracic  duct,  the 
deep  canliac  plexus  which  is  situated  on  the  trachea  just  above  its  bifurcation,  and 
the  left  recurrent  laryngeal  nen'e. 

Above  it  (fig.  321)  are  the  three  chief  branches  for  the  head,  neck,  and  upper 
extremities,  namely,  the  innominate,  the  left  carotid  and  the  left  subclavian  arte- 
ries, and  the  left  innominate  vein. 

Below  it — that  is.  in  its  concavity — are  the  bifurcation  of  the  pulmonary 
artery,  the  left  bronchus,  the  left  recurrent  laryngeal  nerve,  the  remains  of  the 
ductus  arteriosus,  the  superficial  cardiac  plexus,  two  or  more  bronchial  lymphatic 
glands  (fig.  321),  and  the  reflexion  of  the  pericardium. 


470 


THE  ARTERIES 


The  Descending  Portion  of  the  Arch  of  the  Aorta 

The  descending  portion  of  the  arch  of  the  aorta,  morphologically  a  ])art  of  the 
])rimitive  dorsal  aorta,  descends  by  the  left  side  of  the  body  of  the  fourth  and  fifth 
thoracic  vertebrae,  and  ends  at  the  lower  border  of  the  latter  in  the  thoracic  aorta. 

Just  below  the  sj^ot  where  the  ductus  arteriosus  (the  fifth  left  arch)  joins  the 
aorta,  a  constriction  (the  aortic  isthmus  )  is  at  times  met  with,  and  below  this  again 
a  dilatation  of  a  fusiform  ^^hape  (the  aortic  spindle ). 

Relations. — In  front,  it  is  in  contact  with  the  reflexion  of  the  left  pleura  and 
the  root  of  the  left  lung  (rig.  325). 


Fig.  324. —The  Heart  and  Great  Vessels,  with  the  Eoot  of  the  Lungs, 
SEEN  FROM  BEHIND.     (St.  Bartholomew's  Hospital  jMuseuni.) 


dSOPHAGUS 
TRACHEA 

Innoviinale  artery 

RIGHT 
PXE I  \M(t  G  A  S  TRIC 

XER  VE 
Vena  catu  stiperior 

Intercostal  artery 

RIGHT  BRONCHUS 

Intercostal  artery 

Bronchial  artery 

POSTERIOR  PUL- 
MONARY PLEXUS 

Rir/ht  pidmoniiry  artery 
Rhjltt  pulmonary  vein 

Vena  azygos  major 
RIGHT  PLEURA 
Left  auricle 


THORACIC  DUCT 

Left  subclavian  artery 

LEFT  PNEUMO- 

GASTRIC  NERVE 

LEFT  RECURRENT 

LARYNGEAL  NERVE 

Intercostal  artery 

Pulmonary  artery 

BRONCHIAL  GLANDS 
Intercostal  urterh  — 
LEFT  BRONCHUS 

r    .         ,                      ■           \h% 
Lei t  pulmonary  rein  L  J   ^^ 

Descending  aorta 

LEFT  PLEURA 

Oblique  vein 

Left  coronary  artery 

Coronary  sinus 


Left  marginal  braiich  of 
left  coronary  artery 


Ventricular  branches  of 
coronary  artery 

Left  ventricle 


Posterior  cardiac  rein 


Posterior  interventricular 
branch  of  right  coronary 
artery 


Behind,  it  is  in  relation  with  the  left  side  of  the  bodies  of  the  fourth  and  fifth 
thoracic  vertel)i\ne  and  the  ])leura. 

To  the  right  side  are  the  o^-sophagus  and  thoracic  duct,  and  the  fourth  and  fifth 
thoracic  vertebnr. 

To  the  left  side  are  the  left  pleura  and  lung. 


Variations  in  the  Arch  of  the  Aorta 

The  variations  that  have  boon  met  with  in  the  aortic  arch  are  very  niunorous.  Only  the 
chief  can  bo  hero  montioneil.  They  may  lie  divideil  into: — 1.  Variations  in  the  arch  itself; 
and  2.  Variations  in  the  number  and  arrangement  of  the  three  chief  branches.  The  variations 
in  the  coronary  arteries  are  describeil  under  Coronary  Arteries,  page  473. 


VARIATIOyS  IN  ARCH  OF  AORTA 


All 


(1)    Variations  i)i  the  Aortic  Arch  itself 

The  variations  in  the  aortic  arch  itself  may  for  the  most  part  be  traced  to  abnormahties  in 
development  of  the  embryunic  stnictures  from  which  the  three  portions  of  the  arch  and  the  pul- 
HKinary  arteries  and  ductus  arteriosus  are  derived,  i.e.  («)  the  jirimitive  ventral  aortic  stem  ; 
{b)  the  i'uurth  and  fifth  branchial  arches  ;  and  (c)  the  dorsal  aortic  stems. 

(«)  Variations  depending   on  Ahnormah'tits  in   Development   of  the  Ventral 

Aortic  Stem 

The.^e  variations  are  closely  associated  with  abnormalities  of  the  pulmonary  artery  and  heart. 
They  depend  upon  deficient  development  of  the  septum  which  normally  divides  the  anterior 
stem  into  the  first  portion  of  the  aorta  and  the  pulmonary  arterj'.  The  following  are  some  of 
the  chief  variations  : — 

(1)  The  aorta  and  ]uilmonary  artery  may  ari.se  as  a  single  stem  fi-om  a  simple  heart.  The 
septum  here  is  completely  absent.     The  condition  resembles  the  normal  state  in  fishes. 

(2)  The  aorta  and  pulmonary  artery  may  be  more  or  less  conjoined,  and  the  septum  of  the 
heart  incomplete.     This  is  analo.trous  to  the  normal  condition  in  reptiles. 

(3)  The  aorta  and  pulmonary  artery  may  be  transposed. 

(4)  The  aorta  or  pulmonary  artery  may  be  in  part  obliterated,  and  the  blood  earned  into  the 
remainder  of  the  affected  vessel  through  an  abnormal  opening  beyond  the  obliterated  part. 


Fig.  325. — Scheme  of  the  Relations  of  the  Third  Poetiox  of  the 
Akch  of  the  Aorta.     (Walsbam.) 


THORACIC  DUCT 


LEFT  BRONCHUS 


LEFT  LUNG  AND  PLEURA 


Descending  pail  of  arch  of 
aorta 


Left  pulmonary  artery 


{h)    Variations  dependinf/  on  Abnormalities  in  Development  of  the  Fonrth  and 
Fifth  Aortic  or  Branchial  Arches 

(1)  The  aorta  may  be  double,  the  normal  condition  in  amphibians,  each  arch  giving  ofi"  a 
corresponding  carotid  and  sulx-lavian  artery.  This  abnormality  is  explained  by  the  persistence  of 
the  right  fourth  aortic  arch  and  right  descending  aortic  stem,  as  well  as  the  con-esponding  parts 
on  the  left  side.     The  trachea  and  oesophagus  pass  through  the  arterial  circle  thus  formed. 

(2)  The  aortic  arch  may  turn  over  the  right  bronchus  instead  of  over  the  left.  This  is  the 
normal  condition  in  birds,  and  is  exi)lained  by  the  jiersistence  of  the  right  fourth  aortic  arch  and 
right  descending  aortic  stem  and  the  obliteration  of  the  corresponding  parts  on  the  left  side. 

(3)  The  puimonaiy  artery  may  be  given  off  froTn  the  aorta.  This  condition  is  due  to  the 
obliteration  of  the  anterior  part  of  the  fifth  branchial  arch  and  the  persistence  of  the  posterior 
part  which  normally  constitutes  the  ductus  arteriosus. 


(c)    Variations  depending  on  Abnormalities  in  Development  of  the  Dorsal  Aortic  Stems 

The  right  subclavian  may  arise  from  the  third  part  of  the  arch  of  the  aorta.  It  then  j.asses  be- 
hind the  trachea  and  oesophagus,  and  in  front  of  the  vertebral  column,  to  gain  the  interval  between 
the  right  scalene  muscle.*.  The  explanation  of  this  abnormality  is  that  the  right  fourth  arch, 
from  which  the  right  subclavian  is  normally  developed,  is  obliterated,  whilst  the  right  jfosterior 
aortic  stem  remains  pervious  as  far  as  the  spot  where  it  normally  joins  the  right  fourth  arch,  the 
blood  thus  passing  through  the  aortic  stem  instead  of  the  arch.  The  recurrent  laryngeal  nerAe  in 
these  cases  runs  .straight  to  the  larynx,  since,  the  fourth  arch  being  obliterated,  the  nerve  is  no 
longer  hooked  down  by  it.  Rudiments  of  the  right  aortic  stem  fretiuently  persist  as  the  aberrans 
branch  of  the  superior  intercostal  artery  and  thoracic  aorta. 


472  THE  ARTERIES 

In  addition  to  the  above  variations,  the  arch  of  the  aorta  may  be  higher  or  lower  ia  the 
thorax  than  normal.  In  the  former  ease  it  may  cross  the  first  bone  of  the  sternum,  just  below, 
or  even  a  little  above,  the  sternal  notch,  and  reach  the  side  of  the  second  or  third  thoracic  vertebra 
instead  of  the  fourth.  In  the  latter  case,  that  is,  when  it  is  situated  lower  in  the  thorax  than 
normal,  it  may  cross  the  sternum  below  the  level  of  the  manubrium,  and  come  into  contact  with 
the  spine  on  a  level  with  the  fifth  or  sixth  thoracic  vertebra. 

2.    The  Chief  Variations  in  the  Three  Primary  Branches  of  the  Transverse  Portions  of 

the  Aortic  Arch 

(1)  All  may  arise  from  a  common  stem  :  a  condition  explained  on  the  supposition  that  the 
anterior  aortic  roots  have  become  fused,  and  have  so  collected  all  the  branches  together.  A 
similar  condition  is  normal  in  the  horse.     This  variation  is  rare. 

(2)  They  may  arise  as  two  stems  :  (a)  One  stem  may  be  common  to  the  right  subclavian, 
right  carotid,  and  left  carotid,  the  other  stem  being  the  left  subclavian.  This  is  one  of  the  com- 
monest variations  in  the  arrangement  of  the  primary  branches.  It  is  the  normal  condition  in 
many  mammals,  and  was  formerly  described  as  the  normal  condition  in  man.  It  is  of  some 
surgical  interest,  in  that  the  left  carotid  when  thus  given  off  may  cross  in  front  of  the  trachea. 
{b)One  stem  may  be  common  to  the  left  subclavian,  left  carotid,  and  right  carotid,  the  other 
stem  being  the  right  subclavian.  In  this  variety  the  right  carotid  passes  in  front  of  the  trachea. 
(t)  There  may  be  two  innominate  arteries,  one  stem  forming  the  right,  the  other  a  left  innominate 
artery  as  in  birds,  (c?)  One  stem  may  be  common  to  the  right  and  left  carotid  arteries,  the  other 
stem  being  the  left  subclavian— the  right  subclavian  in  this  case  coming  from  the  thoracic  aorta. 

(3)  They  may  arise  as  three  stems :  but,  in  place  of  being  given  oif  in  the  normal  way,  (a) 
the  right  and  left  subclavian  may  come  off  separately,  and  the  carotids  arise  by  a  common  stem 
between  the  subclavians.  This  is  the  normal  condition  in  some  cetaceans,  (h)  The  right  sub- 
clavian and  right  carotid  may  arise  separately,  the  left  carotid  and  left  subclavian  forming  a  left 
innominate  stem,  (c)  The  innominate  may  give  off  the  left  carotid,  the  left  vertebral,  and  left 
subclavian,  the  other  two  vessels  arising  from  the  arch. 

(4)  They  may  arise  as  four  stems,  which  may  be  given  off  in  the  following  order  :  (a) 
innominate,  left  carotid,  left  vertebral,  left  subclavian  (the  commonest  condition)  ;_  (b)  right  caro- 
tid, left  carotid,  left  subclavian,  right  subclavian  ;  (c)  right  subclavian,  right  carotid,  left  carotid, 
left  subclavian — the  normal  condition  in  the  walnis  and  wombat. 

(5)  They  may  arise  as  five  stems,  the  five  branches  being  given  off  in  the  following  order  : 
(a)  right  subclavian,  right  carotid,  left  carotid,  left  vertebral,  left  subclavian;  (h)  right  carotid, 
left  carotid,  left  vertebral,  left  subclavian,  right  subclavian;  (c)  right  carotid,  left  carotid,  left 
subclavian,  left  vertebral,  right  subclavian  ;  {d)  right  subcla%Han,  right  external  carotid,  right 
internal  carotid,  left  common  carotid,  left  subclavian ;  (e)  innominate,  right  vertebral,  left  caro- 
tid, left  vertebral,  left  subclavian. 

(6)  They  may  arise  as  six  stems,  given  off  as  follows  :  right  subclavian,  right  vertebral,  right 
carotid,  left  carotid,  left  vertebral,  left  subclavian. 

Branches  of  the  Arch  of  the  Aorta 

1.  The  ascending  portion    gives  off — fl)  Right  coronary;   (2)  left  coronary. 

2.  The  transverse  portion  gives  off — (1)  Innominate;  (2)  left  common  caro- 
tid;  (3)  left  sulK'lavian. 

3.  The  descending  portion  gives  oft'  no  l)ranch. 

I.  Tlie  l)ranchi-s  of  the  first,  or  ascending,  ]»ortion  of  the  arch  of  the  aorta  are 
the  right  and  left  coronary  for  the  supply  of  the  tissues  of  the  heart.  They  come 
off  from  the  aorta,  immediately  above  the  aortic  valves,  from  two  of  the  dilatations 
known  as  the  sinuses  of  \^alsalva. 


THE  RIGHT  CORONARY  ARTERY 

The  right  coronary  artery  (figs.  321  and  326)  arises  from  the  right  anterior 
sinus  of  Valsalva,  and,  ])assing  forwards  and  t<>  the  right  l)etween  the  right  auricular 
appendix  and  the  pulmonary  artery,  turns  to  the  right,  and  courses  in  the  right 
auriculo-ventricular  groove  to  the  back  of  the  heart,  where  it  follows  the  posterior 
interventricular  groove  to  the  apex  of  the  ventricles,  giving  off,  however,  a  small 
transverse  branch,  which  continues  in  the  groove  between  the  left  auricle  and  ven- 
tricle to  anastomose  with  the  terminal  branch  of  the  left  cor<^nary  artery.  In  this 
course  it  gives  off  the  following  branches:  (a)  A  right  auricular  branch  (fig. 
326),  wliich  turns  backwards  and  upwards  between  the  right  auricle  and  the  aorta, 


RIGHT  AND   LEFT  CORONARY 


473 


su]>plyinff  the  structures  between  which  it  runs  and  the  auricular  sc])tuni;  (6)  a 
preventricular  branch  (tiu;.  o2()),  which  runs  down  the  front  of  the  right  ventricle, 
sup})lyhig  its  walls;  [c)  a  right  marginal  branch  (fig.  o"26),  Avhich  courses  down 
the  right  margin  of  the  right  ventricle;  (d)  a  posterior  interventricular  branch, 
or  the  continuation  of  the  coronary  trunk,  which  passes  down  the  posterior  inter- 
ventricular groove,  giving  twdgs  to  each  ventricle  and  the  interventricular  septum, 
and  anastomosing  at  the  apex  of  the  heart  with  the  anterior  interventricular  branch 
of  the  left  coronary  artery;  and  (e)  the  transverse  branch,  which  runs  in  the  left 
auriculo-ventricular  groove  to  anastomose  with  the  terminal  branch  of  the  left 
coronary  (fig.  32G). 

THE  LEFT  CORONARY  ARTERY 

The  left  coronary  artery  (figs.  321  and  326),  a  little  larger  than  the  right,  arises 
from  the  left  anterior  sinus  of  Valsalva,  and,  passing  forwards  and  to  the  left 
between  the  pulmonary  artery  and  left  auricular  appendix,  courses  round  the  heart 


Fig.  326. — Scheme  of  the  Coroxary  Arteries.     (Walsham.) 


Posterior  intervenlricular 
branch  of  right  coronary 
artery 

AURICULAR  APPENDAGE 

Right  aiirifiilar  hraiir/t 

Right  coronary  artery -J 


Preventricular  branch 
Right  marginal  branch 


Posterior  interventricular 
branch  of  right  coronary 
artery 


Transverse  branch  of  right 
coronary  artery 

Terminal  branch  of  left 
coronary  artery 


Left  coronary  artery 


A  nterior  interventricular 
branch  of  left  coronary 
artery 


Left  marginal  branch 


in  the  left  auriculo-ventricular  groove  to  anastomose  with  the  transverse  bran(>h  of 
the  right  coronary  artery.  It  gives  ofif  the  following  branches:  (a)  A  left  auricular 
branch,  which  supplies  the  left  auricle,  the  pulmonary  artery,  and  the  commence- 
ment of  the  aorta,  (h)  A  large  anterior  interventricular  branch,  Avhich  is  larger 
than  the  continuation  of  the  vessel  between  the  auricle  and  ventricle,  and  is 
regarded  by  some  as  the  main  trunk  of  the  left  coronary  artery.  It  courses  down- 
wards in  the  anterior  interventricular  groove  to  the  apex  of  the  heart,  where  it 
forms  a  slight  anastomosis  with  the  posterior  interventricular  branch  of  the  right 
vessel  (fig.  324).  It  supplies  both  ventricles  and  the  interventricular  septum,  (c) 
A  left  marginal  branch,  which  runs  down  the  left  margin  of  the  heart,  supplying 
branches  to  the  walls  of  the  ventricle,  {d)  The  terminal  branch,  the  continuation 
of  the  vessel,  anastomoses  with  the  transverse  branch  of  the  right  coronary  artery. 


Variations  in  the  Coronary  Arteries 

(a)  They  may  arise  as  a  common  trunk,  (b)  They  may  both  arise  from  the  same  sinus  of 
Valsalva,  '(c)  Tlie  interventricular  and  terminal  Ijranchos  of  tlie  left  coronary  may  arise 
separately  from  the  sinus  of  Valsalva.      (d)  One  coronary  artery  may  be  larger  than  usual; 


474 


THE  ARTERIES 


the  otlier  vessel  is  tlien  correspondingly  small,     (e)  An  extra  coronary  artery  may  arise  from  the 
pulmonary  artery. 

II.  From  tlie  transverse  part  of  the  aortic  arch  are  given  off  the  innominate, 
the  left  common  carotid,  and  the  left  subclavian  arteries.  The  innominate  and 
left  carotid  arise  close  together — indeed,  so  close  that,  when  seen  fr(^m  the  interior 
of  the  aorta,  the  orifices"  appear  merely  separated  by  a  thin  septum.  The  left 
subclavian  arises  a  little  less  close  to  the  left  carotid. 


THE  INNOMINATE  ARTERY 

The  innominate  or  brachio-cephalic  artery  (fig.  321),  the  largest  branch  of 
the  arch  of  the  aorta,  extends  from  near  the  commencement  of  the  transverse  por- 


FiG.  327. — Scheme  of  the  Relations  of  the  Innominate  Artery.     ("Walsham.) 

I,  a  little  above  origin  ;  II,  a  little  below  bifurcation. 

I 


CARDIAC  NERVE 

RIGHT  PyEVMO- 

GASTRIC  SERVE 

Innominate  artery 

RIGHT  LUNG  AND  PLEURA 


Rir/ht  innominate  vein, 
divided  transversely 
at  its  junctio7i  with 
the  left  innominate 
vein 


Left  common  carotid  artery 


Inferior  thyroid  vein 
Inferior  thyroid  vein 
Left  innominate  vein 


n 


RIGHT  LUNG  AND  PLEURA 

RIGHT    PNEUMO- 

GASTRIC  NERVE 

Right  innominate  vein 

Innominate  artery 


CARDIAC  NERVES 


Left  common  carotid  artery 
Inferior  thyroid  vein 


Right  sterno-hyoid  and 
Right  sterno-thyroid  muscles 


tion,  upwards  and  a  little  forwards  and  to  the  right,  as  high  as  the  upper  limit  of 
the  right  sterno-clavicular  joint  where  it  bifurcates  into  the  right  common  carotid 
and  right  subclavian  arteries.  It  lies  obliquely  in  front  of  the  trachea,  and 
measures  from  an  inch  and  a  half  to  two  inches  in  length  (about  4  cm.). 

Relations. — In  front  of  the  artery  (fig.  327)  are  the  manultrium,  the  origins 
of  the  sterno-hyoid  and  sterno-thyroid  muscles,  the  right  sterno-clavicular  joint 
and  the  remains  of  the  thymus  gland.  The  left  innominate  vein  crosses  the  root 
of  the  vessel,  and  the  inferior  thyroid  veins  descend  obliquely  over  it  to  end  in  the 
left  innominate  vein.  The  inferior  cervical  cardiac  branches  of  the  right  pneumo- 
gastric  pass  in  front  of  it  on  their  way  to  the  deep  cardiac  plexus. 

Behind,  it  lies  on  the  trachea,  cx'ossing  that  tube  obliquely  from  left  to  riglit, 
and  coming  into  contact  al)Ove  with  the  right  pleura. 

To  the  right  side  are  the  right  innominate  vein,  the  right  pneumogastric  nerve, 
and  the  pleura. 


THE  COMMON  CAROTID  475 

To  the  left  side  are  the  left  common  carotid,  the  remains  of  the  thymus  gland, 
the  inferior  thyroid  veins;  and  higher,  the  trachea. 

Variations  in  the  Innominate  Artery 

The  variations  in  the  innominate  artery  are  of  surgical  interest,  (a)  It  may  divide  lower 
than  normal,  thus  decreasing  the  available  space  for  the  application  of  a  ligature  to  it,  but  at  the 
same  time  increasing  the  length  of  the  first  portion  of  the  right  subclavian  artery,  {b)  It  may 
divide  higher  than  usual,  and  may  then  incline  abnormally  to  the  left,  mounting  in  front  of  the 
trachea  above  the  sternum.  Under  these  circumstances  it  is  in  danger  in  the  low  operation  of 
tracheotomy,  (c)  When  abnormally  long  and  inclining  to  the  left,  it  may  pass  behind  the  trachea 
or  the  oesophagus  to  gain  the  right  side.  ((/)  It  may  give  off  the  thyroidea  ima  artery,  and,  more 
rarely  the  vertebral,  the  internal  mammary  or  a  smaller  twig,  as  a  bronchial,  thymic,  pericardiac, 
or  tracheal  branch. 

The  branches  of  the  innominate  artery  are:  (1)  The  right  common  carotid; 
and  (2)  the  right  subclavian.  These  nw  terminal  branches.  There  are  usually  no 
collateral  branches  from  this  vessel,  but  at  times  the  thyroidea  ima  may  arise 
from  it. 

THE  COMMON  CAROTID  ARTERIES 

The  common  carotid  arteries  pass  up  deeply  from  the  thorax  on  either  side 
of  the  neck  to  about  the  level  of  the  upper  border  of  the  thyroid  cartilage,  where 
they  divide  into  the  external  and  internal  carotid  arteries.  The  external  carotid 
supplies  the  structures  at  the  upper  part  of  the  front  and  side  of  the  neck,  tlie 
larynx,  pharynx,  tongue,  face,  the  upper  part  of  the  back  of  the  neck,  the  structures 
in  the  pterygoid  region,  the  scalp,  and  in  chief  part  the  membranes  of  the  brain. 
Tlie  internal  carotid  gives  off  no  branch  in  the  neck,  but  enters  the  cranium  and 
supplies  the  greater  part  of  the  brain,  the  structures  contained  in  the  orbit,  and 
portions  of  the  membranes  of  the  brain. 

The  common  carotid  artery  on  the  right  side  arises  from  the  liifurcation  of 
the  innominate  behind  the  sterno-clavicular  joint;  on  the  left  side  from  the 
arcli  of  the  aorta  a  little  to  the  left  of  the  innominate  artery,  and  on  a  some- 
what posterior  plane  to  that  vessel  (fig.  321).  The  portion  of  the  left  common 
carotid  artery  which  extends  from  the  arch  of  the  aorta  to  the  level  of  the  sterno- 
clavicular articulation  lies  deeply  in  the  chest,  and  requires  a  separate  descrip- 
tion; but  above  the  level  of  the  sterno-clavicular  joint  the  relations  of  the  right 
and  left  carotids  are  practically  the  same,  and  are  given  under  the  account  of 
the  right  common  carotid. 


THORACIC  PORTION  OF  THE  LEFT  COMMON  CAROTID  ARTERY 

Within  the  thorax  the  left  common  carotid  is  deeply  placed  behind  the  first  bone 
of  the  sternum,  and  is  overlapped  by  the  left  lung  and  pleura.  It  arises  from  the 
middle  of  the  transverse  portion  of  the  aortic  arch,  close  to  the  left  side  of  the 
innominate  artery,  and  a  little  posterior  to  that  vessel,  and  ascends  obliquely  in 
front  of  the  trachea  to  the  left  sterno-clavicular  articulation,  above  which  its  rela- 
tions are  similar  to  those  of  the  right  common  carotid. 

Relations. — In  front,  but  at  some  little  distance,  are  the  manubrium  and 
the  origins  of  the  left  sterno-hyoid  and  sterno-thyroid  nmscles;  whilst  in  con- 
tact with  it  are  the  remains  of  the  thymus  gland,  and  the  loose  connective 
tissue  and  fat  of  the  superior  mediastinum.  Crossing  its  root  is  the  left  innom- 
inate vein. 

Behind,  it  lies  successively  upon  the  trachea,  the  cpsophagus  (which  here 
inclines  a  little  to  the  left),  the  thoracic  duct,  and  the  left  recurrent  laryngeal 
nerve. 

To  its  right  side  is  the  root  of  the  innominate  artery,  and  higher  up  are  the 
trachea  and  the  inferior  thyroid  veins. 

To  its  left  side,  but  on  a  posterior  plane,  are  the  left  subclavian  artery  and  the 


476 


THE  ARTERIES 


left  pneumogastric  nerve;  and,  slightly  overlapping  it,  the  edge  of  the  left  pleura 
and  lung  (fig.  328). 

The  variations  in  the  origin  of  the  left  common  carotid  are  given  under  VARIATIONS  OP  THK 
Arch  of  the  Aorta  (page  471). 


THE  COMMON  CAROTID  ARTERY  IN  THE  NECK 

Tlie  common  carotid  artery  in  the  neck  extends  from  the  sterno-clavicular 
articulation  to  the  upper  border  of  the  thyroid  cartilage  on  a  level  with  the  fourth 
cervical  vertebra  where  it  divides  into  the  external  and  internal  carotid  arteries. 
A  line  drawn  from  the  sterno-clavicular  joint  to  the  interval  between  the  mastoid 
process  and  the  angle  of  the  jaw  would  indicate  its  course.     The  artery  is  at  first 


Fig.  328. — Scheme  of  the  Relations  of  the  Left  Common  Caeotid  and  Left 
Subclavian  Arteries  within  the  Thorax.     (Walsham.) 

I,  just  above  origin  ;  II,  just  below  level  of  steruo-clavicular  joint. 

I 


LEFT  RECURRENT 
LARYSGEAL  NERVE 

Left  common  carotid  artery 
Innominate  artery 

CARDIAC  NERVES 
Right  innominate  vein 


Left  subclavian  artery 


LEFT  PNEUMOGASTRIC 
NER  VE 


—  Left  innominate  vein 
Inferior  thyroid  veins 

REMAINS  OF  THYMUS  GLAND 


5TEJ^NUT?1- 


II 


LEFT  RECURRENT 
LARYNGEAL  NERVE 


Inferior  thyroid  veins  \ 
Innominate  artery 

REMAINS  OF  THYMUS  GLAND 


THORACIC  DUCT 


Left  subclavian  artery 


LUNG  AND  PLEURA 

LEFT  PNEUMOGASTRIC 

NER  VE 
Left  common  carotid  artery 


-  Left  innominate  vein 


Left  Bterno-hyoid  and 
Left  sterno-thyroid  muscles 


deeply  placed  beneath  the  sterno-mastoid,  sterno-hyoid,  and  sterno-thyroid 
muscles,  and  at  the  level  of  the  top  of  the  sternum  is  only  three-quarters  of  an  inch 
(2  cm.)  distant  from  its  fellow  of  the  opposite  side,  and  merely  separated  from  it 
by  the  trachea.  As  the  carotid  arteries  run  up  the  neck,  however,  tliey  diverge  in 
the  form  of  a  V  and  become  more  superficial,  though  on  a  plane  posterior  to  that 
in  which  they  lie  at  the  root  of  the  neck,  and  are  separated  from  each  other  by  the 
larynx  and  pharynx.  At  their  bifurcation  they  are  about  two  inches  and  a  quarter 
(6  cm. )  apart.  The  common  carotid  is  contained  in  a  sheath  of  fascia  common 
to  it  and  the  internal  jugular  vein  and  pneumogastric  nerve.  The  artery,  vein, 
and  nerve,  hoAvever,  are  not  in  contact,  but  separated  from  one  another  by  fibrous 
septa,  which  divide  the  common  sheath  into  three  conqiartments:  one  for  the 
artery,  one  for  the  vein,  and  one  for  the  nerve.  The  vein,  wliich  is  larger  than 
the  artery,  lies  to  the  outer  side,  and  somewhat  overlaps  the  artery.     The  pneumo- 


THE  COMMON  CAROTID 


477 


gastric  nerve  lies  behind  and  between  the  two  vessels.  The  artery  on  the  right 
side  measures  about  three  and  three-quarter  inches  (9-5  cm.);  on  the  left  side 
about  four  and  three-quarter  inclies  (12  cm.). 


Fig.  32[).~The  Common  Caeotid,  the  External  and  Internal  Carotid  and  the 
Subclavian  Arteries  of  the  Right  Side  and  their  Branches. 

(From  a  dissection  by  Dr.  Alder  Smith  in  the  Museum  of  St.  Bartholomew's  Hospital.) 

Stylo-glossus 

SiibniKutal  artery 
Facial  artery 

MYLO-IIYOID  NERVE 

LOWER  JAW,  TURNED  UP 


lyPERIOR  DENTAL  NERVE 
CHORDA  TYMPANT 
FACIAL  NERVE 
Internal  maxillary  artery 
Stylo-hyoid,  turned  up 
Digastricus,  turned  up 
Temporal  artery 


Posterior  auricular  artery 
Internal  jugular  rein    \ 

SECOND  CERVICAL 

NER  VE 

SPINA  L  A  CCESSOR  Y 

NERVE  V 

Rectus  capitis  anticus  major  \V: 

Stylo-pharyngeua  muscle 

SUP.  CER.   GANGL.  OF  SVMPATHET'C 

GLOSSO-PUAR.  NER  VE 

Sterno-mastoid,  reflected 

Occijjital  artery 

Internal  carotiit 

Levator  anguli  scapulae 

THIRD  (ERVIC  NERVE 

DESCENDENS  H  YPO- 

GLOSSI  NER  VE 

External  carntiil 
Inferior  constrictor 

COMMUN.  HYPOGLOSSI 

FOURTH  CERV.  NERVE 

Ascending  cervical  artery 

SPINAL  ACCESSORY 

PHRENIC  NERVE 

Scalenus  anticus 

Levator  anguli  scapulae 

FIFTH  CERV.  NER  VE 

Scalenus  mediua 

CERVICAL  PLEXrS 

DESCENDEXS  BRANCH 

PNEUMOGASTRIC 

NER  VE 

BRACHIAL  PLEXUS 

(SIXTH  CERVICAL) 

Internal  jugular  vein 

Superficial  cervical  artery 

Suprascapular  artery 

Serratus  maguus 

Coraco-braehialis 


^Kjirascapular  artfry  given  off  from  tliinl 
part  iij  subclavian 

Posterior  scapular  artery 
SUPRASCAPULAR  NERVE 

Humeral  thoracic  artery 
Posterior  belly  of  omo-hyoid,  drawn  down 


SUBMAXILLARY  GANGLION 
G  USTA  TOR  Y  NER  VE 

SUBMAXILLARY   DUCT 
SUBMAXILLARY  GLAND 
TONGUE 

HYPOGLOS.  NERVE 
Ranine  artery 

6enio-hyo-glo8sus 
Sublingual  artery 

Lingual  artery 

'  *^^^ — ■  Artery  of/rcenum 
'     "^ LOWER  JAW 


Genio-hyoid 


Hyo-gloBBUs 
Lingual  artery 
~  Hyoid  hraiirk 

Mylo-hyoid  muscle 
Thyro-hyoid  membrane 
.S  UPERIOR  LARl  N- 

GEAL  NERVE 
Superior  laryngeal  artery 
Thyro-hyoid 
Superior  tliyroid  artery 
Omo-hyoid 
EXTERNA L  LAR YN- 

GEAL  NERVE 
THYROID  GLAND 

Sterno-hyoid 
Common  carotid 
Sterno-thyroid 
Vertebral  artery 
Inferior  thyroid  artery 
Anterior  jugular  vein 
Common  carotid 
CLAVICLE 
Vertebral  vein 

BRA  CHIA  L  PLEXUS 
(SEVENTH  CER  VIC.) 

Subclavia?)  artery 

Peef oralis  major, 
reflected 


Ti-an.\verse  cervical  artery 
Subclavius,  reflected 
BRACHIAL  PLEXUS  (EIGHTH  CERVICAL) 
Pectoral  branch  of  acromial  thoracic  artery 
Subclavian  vein 
Pectoralis  minor 


Relations. — In  front  the  artery  is  covered  by  the  skin,  superficial  fascia,  ])la- 
tysma,  and  deep  fascia,  and  is  more  or  less  overlapped  by  the  sterno-mastoid  muscle. 
At  the  loAver  part  of  the  neck  it  is  covered  in  addition  by  the  sterno-hyoid  and 


478 


THE  ARTERIES 


sterno-thyroid  muscles,  and  is  crossed  by  the  anterior  jugular  vein,  and  is  often 
overlapi)ed  l)y  the  thyroid  body.  Opposite  the  cricoid  cartilage  it  is  crossed  obliquely 
l)y  the  onio-hyoid  muscle;  and  ai)0ve  this  spot  by  the  middle  and  superior  thyroid, 


Fig.  3:50.— The  Collateral  CiEcrLAXiox  after  Ligature  of  the  Common  Carotid  and 

Subclavian  Arteries. 

(A  ligature  is  placed  on  the  common  carotid  and  on  the  third  portion  of  the  subclavian  arter}'.) 


Right  anterior  cerebral 

Internal  carotid 
Right  posterior  cerebral 


Occipital 
Princeps  cervicis 

External  carotid 

Superficial  branch  of  princeps  cervicis 

Deep  branch 

Ascending  cervical 


Transverse  cervical 

Posterior  scapular 

Acromial  branch 

Subscapular  branch 

Sujirasjiinoiis  branch 

Anterior  circumflex  ■  \i 
Infraspinous  branch  — * 
Posterior  circumflex 
Long  thoracic 
Subscapular 

Dorsal  scapular 
Jn/rascnpular 

Subscapular 


Superior  thijroiii 


Left  anterior  cerebral 
Anterior  communicating 


Posterior  communicating 
Left  posterior  cerebral 


Anterior  spinal 


Inferior  thyroid 
Cfinimon  carotid 


Thyroid  axis 
Superior  intercostal 


Innominate 
Sujierior  inter  costal 
Left  common  carotid 
Left  sub cl avian 
Short  thoracic 
Internal  mammary 


Anterior  intercostal 

First  aortic  inter- 
costal 

Second  aortic  inter- 
costal 


Anterior  intercostal 


Third  aortic  inter- 
costal 


the  lingual,  and  generally  the  facial  veins  in  their  course  to  the  internal  jugular, 
and  by  the  middle  sterno-mastoid  artery  as  it  passes  from  the  superior  thyroid  artery, 
its  usual  source,  on  its  way  down  to  the  sterno-mastoid  muscle.    Along  the  anterior 


THE  COMMON  CAROTID  479 

border  of  the  sterno-mastoid  there  is  a  communicating  vein  l)et\veen  the  facial  and 
anterior  jugular  veins,  which,  as  it  crosses  the  line  of  the  carotid  artery,  is  in  danger 
of  being  wounded  in  the  operation  of  tying  the  carotid.  The  descendens  hypoglossi 
nerve  generally  descends  in  front  of  the  carotid  sheath,  being  there  joined  by  the 
communicantes  hypoglossi,  one  or  two  small  l)ranches  of  the  second  and  third 
cervical  nerves.  At  times  this  nerve  runs  within  the  sheath.  There  are  usually 
two  lymphatic  glands  about  the  bifurcation  of  the  artery.  These  are  often  found 
enlarged  and  infiltrated  in  cancer  of  the  lip  and  tongue. 

Behind,  the  common  carotid  lies  on  the  longus  colli  and  scalenus  anticus  below, 
and  rectus  capitis  anticus  major  above.  Posterior  to  the  artery,  l;)ut  in  the  same 
sheath,  is  the  pneumogastric  nerve;  and  posterior  to  the  sheath,  the  chain  of  the 
sympathetic  and  the  cervical  cardiac  branches  of  the  sympathetic  and  pneumo- 
gastric nerves.  At  the  lower  part  of  the  neck  the  inferior  thyroid  arter}'  courses 
olili([Uely  lieliind  the  carotid,  as  does  likewise  the  recurrent  laryngeal  nerve. 

Internally,  from  below  upwards,  are  the  trachea  and  oesophagus,  with  the 
recurrent  laryngeal  nerve  in  the  groove  between  them,  and  the  terminal  branches 
of  the  inferior  thyroid  artery,  the  lateral  lobe  of  the  thyroid  l)ody,  the  cricoid  car- 
tilage, the  thyroid  cartilage,  and  the  lower  part  of  the  pliarynx.  At  tlie  angle  of 
bifurcation  is  a  vascular  structure  known  as  the  ganglion  intercaroticum  or  the 
carotid  gland. 

Externally  are  the  internal  jugular  vein  and  the  pneumogastric  nerve.  On  the 
right  side,  at  the  root  of  the  neck,  the  vein  diverges  somewhat  from  the  artery, 
leaving  a  space  in  which  the  pneumogastric  nerve  and  vertebral  artery  are  exposed. 
On  the  left  side  the  vein  approaches  and  somewhat  overlaps  the  artery,  thus  leaving 
no  interval  corresponding  to  that  on  the  right  side. 

The  cricoid  cartilage  is  as  a  rule  taken  as  the  centre  of  the  incision  in  the  opera- 
tion f<jr  ligature  of  the  common  carotid  artery.  The  incision  is  made  in  the  line  of 
the  vessel  jnirallel  to  the  anterior  margin  of  the  sterno-mastoid  muscle.  The  omo- 
hyoid forms  one  of  the  chief  ralhdng  points  in  the  course  of  the  operation  for 
ligature  of  the  artery  above  that  muscle,  the  usual  situation.  The  artery  is  found 
beating  at  the  angle  formed  by  the  omo-hyoid  with  the  sterno-mastoid. 

Branches. — (1)  External  and  (2)  internal  carotid  arteries.  The  common  carotid 
gives  off  no  lateral  branch,  and  consequently  does  not  diminish  in  size  as  it  runs  up 
the  neck.  It  is  often  a  little  swollen  just  below  its  bifurcation,  a  condition  that 
should  not  be  mistaken  for  an  aneurismal  dilatation. 

Variations  of  the  Common  Carotid  Arteries 

The  variations  in  the  origin  of  the  common  carotid  have  been  already  mentioned  under 
Y.A.RrATio\s  OF  THE  Chief  Braxches  OF  THE  AoRTic  Arch  (page  472). 
The  fulluwing  vuriatiun.s  are  of  surgical  interest : — 

(A)  The  artery  may  cross  obliquely  the  lower  part  of  the  trachea  above  the  level  of  the 
sternum.  This  may  occur  on  the  right  side  :  (a)  when  the  innominate  is  situatt-d  abnormally  to 
the  left  of  the  middle  line  ;  (i)  when  the  right  common  carotid  ari.ses  as  the  second  branch  of  the 
aortic  arch  ;  and  (c)  when  the  right  and  lel't  common  carotids  aiise  as  a  common  stem  from 
the  aorta.     On  the  left  side  :  when  the  left  common  carotid  arises  from  tlie  innominate. 

(B)  The  ri^ht  common  carotid  maj',  when  arising  I'rom  the  aorta,  run  behind  the  trachea  and 
oesophagus  to  the  right  side  of  the  neck. 

(C)  The  commencement  of  the  right  common  carotid  may  be  above  or  below  the  usual  sjiot, 
according  as  the  innominate  bifurcates  higher  or  lower  than  usual.  A  low  bifurcation  of  the 
innominate  is  .somewhat  the  more  conunon  abnormality. 

(D)  The  common  carotid  maj'  run  in  a  very  tortuous  manner,  forming  one  or  more  distinct 
loojts  in  its  course  uij  the  neck. 

(E)  The  artery  may  bifurcate  higher  or  lower  than  normal.  A  high  bifurcation  is  the  more 
common.  The  bifurcation  may  occur  as  high  as  the  hj'oid  bone,  or  even  stj'loid  process ;  or  as 
low  as  the  cricoid  cartilage,  or  within  an  inch  ami  a  half  of  its  on'frin. 

(F)  The  artery  may  not  bifurcate,  but  give  off  the  branches  usually  derived  from  the  external 
division  as  it  ascends  in  the  neck. 

(G)  The  CMjmmon  carotid  may  be  absent,  the  external  and  internal  carotids  arising  directly 
from  the  aorta. 

(H)  It  may  give  off  one  or  more  of  the  branches  usually  derived  from  the  external  carotid. 

(I)  It  may  give  off  a  thyroidea  ima. 

(J)  The  pneumogastric  nerve  may  run  in  front  of  the  artery  instead  of  behind  it. 

The  collateral  circulation  (fig.  330),  after  ligature  of  the  common  caroti<l,  is  carried  on  chiefly 


480  THE  ARTERIES 

by  the  anastomosis  of  the  uitenial  carotid  with  the  internal  carotid  of  the  opposite  side  throufrh 
tlie  circle  of  Willis  ;  by  the  vertebral  with  the  ojjposite  vertebral  ;  by  the  inferior  thyroid  with 
the  superior  thyroid  ;  by  the  deep  cervical  branch  of  the  superior  intercostal  with  the  princeps 
cervicis  of  the  occipital ;  by  the  superior  thyroid,  lingual,  facial,  occipital  and  temporal,  with  the 
corresponding  arteries  of  the  opposite  side,  and  by  the  ophthalmic  with  the  angular.  The  anas- 
tomosis between  the  deep  cervical  branch  of  the  superior  intercostal  with  the  princeps  cervicis  of 
the  occipital  is  an  important  one  and  is  situated  deeply  at  the  back  of  the  ueck,  aud  is  to  be  found 
lying  between  the  complexus  and  semi-spinalis  colli  muscles. 


THE  EXTERNAL  CAROTID  ARTERY 

The  external  carotid  artery,  the  smaller  of  the  two  branches  mto  which  the 
common  carotid  divides  at  the  upper  border  of  the  thyroid  cartilage,  is  distributed 
to  the  anterior  part  of  the  neck,  the  face,  and  the  side  of  the  skull  both  soft  parts 
and  bones,  the  integuments  externally,  and  dura  mater  internally.  It  is  develop- 
mentally  derived  from  the  third  aortic  arch,  and  supplies  the  oral  and  post-oral 
visceral  branches.  It  is  at  first  situated  internal  to  the  internal  carotid ;  1  )Ut  as  it 
ascends  in  the  neck  it  forms  a  gentle  curve,  with  its  convexit}'  forwards,  and, 
running  slightly  backwards  as  well  as  upwards,  terminates  opposite  the  neck  of  the 
lower  jaw  just  below  the  condyle,  by  dividing  into  the  internal  maxillary  and 
superficial  temporal  arteries.  It  here  lies  superficial  to  the  internal  carotid,  from 
which  it  is  separated  by  a  portion  of  the  parotid  gland.  At  its  origin  it  is 
overlapped  by  the  anterior  margin  of  the  sterno-mastoid,  and  is  covered  by  the 
superficial  fascia,  platysma,  and  deep  fascia.  Higher  up  the  neck  it  passes  beneath 
the  stylo-hyoid  muscle,  the  posterior  belly  of  the  digastric  muscle,  and  the  hypo- 
glossal nerve;  and,  entering  the  parotid  gland,  is  situated  deeply  in  that  structure 
at  its  division  into  its  terminal  branches.  It  is  separated  from  the  internal  carotid 
artery  posteriorly  by  the  stylo-jiharyngeus  and  stylo-glossus  muscles,  the  glosso- 
pharyngeal nerve,  the  pharyngeal  branch  of  the  pneumogastric  nerve,  a  portion  of 
the  parotid  gland,  and  the  stylo-hyoid  ligament;  or,  if  the  styloid  process  is  alnior- 
mally  long,  by  that  process  itself.  It  measures  about  two  and  a  half  inches 
(6"5  cm.). 

Relations  (fig.  329). — In  front,  in  addition  to  the  skin,  superficial  fascia, 
platysma,  and  deep  fascia,  it  has  the  hypoglossal  nerve,  the  lingual  and  facial 
veins,  the  posterior  belly  of  the  digastricus  and  stylo-hyoid  muscles,  the  temporo- 
maxillary  vein,  the  superior  cervical  lymphatic  glands,  branches  of  the  facial  nerve, 
and  the  parotid  gland.  The  sterno-mastoid  also  overlaps  it  in  the  natural  state  of 
the  parts. 

Behind,  it  is  in  relation  with  the  internal  carotid,  from  Avhich  it  is  separated 
by  the  stylo-glossus  and  stylo-pharyngeus  muscles,  the  glosso-pharvngeal  nerve,  the 
pharyngeal  branch  of  the  pneumogastric  nerve,  the  stylo-hyoid  ligament,  and  the 
parotid  gland.  The  superior  laryngeal  nerve  crosses  behind  both  the  external  and 
internal  carotid  arteries. 

Internally,  it  is  in  relation  with  the  hyoid  bone,  the  pharyngeal  wall,  the  ramus 
of  the  jaw,  the  stylo-maxillary  ligament  Avhich  sejiarates  it  from  the  submaxillary 
gland,  and  the  parotid  gland. 

Externally,  in  the  first  part  of  its  course,  it  is  in  contact  with  the  internal 
carotid  artery. 

Chief  Variations  of  the  External  Carotid  Artery 

The  variations  of  the  external  carotid  artery  are  not  of  much  surgical  im]iortance.  The 
variations  in  its  origin  have  been  discussed  under  A'ariations  of  the  Common  Carotid. 

(A)  It  may  be  absent,  the  branches  usually  derived  from  it  coming  off  from  the  upward 
continuation  of  the  common  trunk. 

( B)  It  may  run  superficial  to  the  stylo-hyoid  muscle. 

(C)  Its  branches  may  come  oflF  irregularly;  or  maybe  diminished  or  increased  in  number 
either  by  two  or  more  arising  as  a  common  stem,  or  by  its  giving  origin  to  branches  not  usually 
derived  from  it,  as  the  sterno-mastoid  branch  of  either  the  superior  thyroid  or  occipital  artery. 

(D)  At  times  all  its  branches  come  off  close  together  just  above  its  origin. 

The  branches  of  the  external  carotid  are  usuallv  given  off  in  the  following 
order,  from  below  upwards: — 


THE  ASCEXDIXir  PHARYXGEAL 

1.  Ascending  pharyngeal Ascending  set. 

2.  Superior  thyroid '\ 

3.  Lingual       -  Anterior  set. 

4.  Facial S 

5.  Occipital Id*-         * 

6.  Posterior  auricular \   P^-'^tenor  set. 

7.  Temporal I   rp        .     ,      , 

8.  Internal  maxillary J  Termmal  set. 


481 


1.   THE  ASCENDING  PHARYNGEAL  ARTERY 

The  ascending  pharyngeal  artery  is  usually  the  first  or  second  branch  of  tlie 
external  carotid.       (Jccasionallv  it  comes  off   at    the    bifvircation  of  the  common 


Fig.  331.— Scheme  of  Right  Ascending  Pharyngeal  Aktery.     (Walsham. 
The  internal  carotid  artery  is  hooked  aside. 


Meningeal  hranchpassiiig i/irotif/h 
niUldle  lacerated  foramen 

I)/mpanic  branch 

Meningeal  branch  passing  throvgh 

jugular  foramen 

Meninge'il  branch  passing  through 

anterior  condyloid  foratuen 


Stylo-pharyngeus 


GLOSSO-PHARYXGEAL 
SER  VE 

Orrijiilal  artery 
Reetua  capitis  antieus 
major 
A.<cend i II g  pharyngeal 

iirtery 

Middle  constrictor  of 

pharynx 

SYMPA  THETTC  SERVE 
Internal  carotid  artery 
External  carotid  artery 


Intracranial  part  of  internal 
carotid 


Intraosseous  part  of  internal 
carotid 

Levator  palati 
Palatine  branch 


Buccinator  muscle 

Superior  constrictor 
of  pharynx 

Pterygo-maxillary 
ligament 

Stylo-glossus 


Ascending  palatine  branch 
of  facial  artery 

Tonsillar  branch  of  facial  artery 


Lingual  artery 
Superior  thyroid  artery 


Common  carotid  artery 


carotid  from  the  common  carotid  itself.  It  is  a  long  slender  vessel,  the  smallest 
named  braneli  of  the  external  carotid,  and  runs  deeply  seated  up  the  neck  to  the 
base  of  the  skull,  having  the  walls  of  the  pharynx  and  the  tonsil  internally,  the 
internal  carotid  artery  externally,  and  the  vertebral  column,  the  rectus  ca]»itis 
antieus  major,  and  the  sympathetic  nerve  posteriorly.  In  front  it  is  crossed  by 
the  stylo-glossus  (see  fig.  331 J  and  stylo-pharyngeus  muscks  and  the  glosso-pharyn- 
geal  nerve. 

Beaxches  of  the  Ascending  Pharyngeal  Artery 

The  ascending  pharyngeal  artery  gives  oflP  the  folL^wing  branches: — H)  Pre- 
vertebral;  (2  )  pharyngeal;   (3)  palatine;   (4)  tympanic;   (5)  meningeal. 

(1)  The  prevertebral  are  distributed  to  the  recti  muscles,  the  fascia  in  front  of 
31 


482  THE  ARTERIES 

the  vertebral  column,  and  to  the  symi)athetic  nerve  and  lymphatic  glands.  These 
branches  anastomose  with  branches  of  the  ascending  cervical.  (2)  Tlie  pharyngeal 
supply  the  superior  and  middle  constrictor  muscles  and  the  mucous  niemlirane 
lining  them.  These  vessels  anastomose  with  branches  of  the  sui)erior  thyroid. 
(3)  The  palatine  passes  over  the  upj^er  edge  of  the  superior  constrictor  to  the  soft 
palate  and  its  muscles.  This  branch  follows  a  course  similar  to  that  taken  by 
the  ascending  palatine  artery,  and  when  the  latter  is  small  may  take  its  place. 
It  generally  gives  off  small  twigs  to  the  Eustachian  tube  and  tonsil.  (4)  The 
tympanic  accompanies  the  tympanic  In-ancli  of  the  glosso-pharyngeal  nerve 
through  the  tympanic  canaliculus  into  the  tympanum,  and  anastomoses  with  the 
other  tympanic  arteries.  (5)  The  meningeal  are  distributed  to  the  memljranes 
of  the  brain.  Some  of  these  pass  with  the  jugular  vein  through  the  jugular 
foramen  into  the  cranium,  and  supply  the  dura  mater  in  the  posterior  fossa  of 
the  skull.  Others  occasionally  reach  the  same  fossa  through  the  anterior  condy- 
loid foramen  in  company  with  the  hypoglossal  nerve;  while  others  pass  through 
the  cartilage  of  the  middle  lacerated  foramen  and  supplv  the  middle  fossa  of  the 
skull. 

2.  THE  SUPERIOR  THYROID  ARTERY 

The  superior  thyroid  artery  arises  from  the  front  of  the  external  carotid  a 
little  above  the  origin  of  that  vessel,  and,  coursing  forwards,  inwards,  and  then 
downwards,  in  a  tortuous  manner,  supplies  the  depressor  muscles  of  the  hyoid  bone, 
the  larynx,  the  thyroid  body,  and  the  lower  part  of  the  pharynx.  The  artery  at 
first  runs  forwards  and  a  little  upwards,  just  beneath  the  greater  cornu  of  the 
hyoid  bone.  In  this  part  of  its  course  it  lies  in  the  sui^erior  carotid  triangle,  and  is 
quite  superficial,  being  covered  only  with  the  integument,  fascia,  and  platysma. 
It  next  turns  downwards,  and  passes  beneath  the  omo-hyoid,  sterno-hyoid.  and 
sterno-thyroid  muscles,  and  ends  at  the  upper  i)art  of  the  thyroid  body  by  breaking 
up  into  liranches,  some  of  which  pass  downwards  in  front,  and  others  behind  the 
lateral  lobe  of  that  structure  to  anastomose  with  ascending  branches  from  the 
inferior  thyroid;  Avhilst  others,  again,  but  much  smaller  in  size,  pass  in  the  substance 
of  the  isthmus  across  the  front  of  the  trachea  to  anastomose  with  the  superior 
thyroid  artery  of  the  opposite  side.  These  vessels,  however,  are  so  small,  that  if  the 
isthmus  is  divided  accurate^  in  the  middle  line,  there  is  practically  no  arterial 
hiemorrhage.  From  the  branch  to  the  thyroid  body  twigs  are  given  off  to  the 
inferior  constrictor  and  the  upper  part  of  the  oesophagus.  These  anastomose  with 
branches  from  the  inferior  thyroid.  The  superior  thyroid  vein  passes  beneath  the 
artery  on  its  way  to  the  internal  jugular  vein.  The  superior  thyroid  is  the  artery 
most  commonly  divided  in  cases  of  suicidal  wounds  of  the  throat. 

Branches  of  the  Superior  Thyroid  Artery 

The  named  branches  of  the  superior  thyroid  artery  are: — (1)  The  hyoid; 

(2)  the  sterno-mastoid;   (3)  the  superior  laryngeal;  and  (4)  the  crico-thyroid. 

(1)  The  hyoid — or  infra-hyoid  branch  as  it  is  sometimes  called,  usually  a 
small  twig — passes  along  the  lower  border  of  the  hyoid  bone,  lying  on  the  thyro- 
hyoid membrane  under  cover  of  the  thyro-hyoid  and  sterno-hyoid  muscles.  It 
sup})lies  the  infra-hyoid  l)ursa,  and  the  tliyro-hyoid  muscle,  and  anastomoses  with 
its  fellow  of  the  opposite  side,  an.d  with  the  supra-hyoid  liranch  of  the  lingual. 
When  the  latter  artery  is  small,  the  infra-hyoid  is  usually  comparntivfly  large,  and 
vice  versa. 

(2)  The  sterno-mastoid  (fig.  332) — or  middle  mastoid  artery  as  it  is  occa- 
sionally called — courses  downwards  and  backwards  across  the  carotid  sheath,  and 
entering  the  sterno-mastoid  supi)lies  the  middle  portion  of  that  muscle.  It  gives 
off  slender  twigs  to  the  thyro-hyoid,  sterno-hyoid,  and  omo-hy<^id  muscles,  and  the 
platysma  and  integuments  covering  it.  At  times  the  vessel  arises  directly  from  the 
external  carotid.  It  lies  usually  somewhere  in  the  upper  ]iart  of  the  incision  for 
tying  the  common  carotid  al)ove  the  omo-hyoid  muscle. 

(3)  The  superior  laryngeal  (tig.  329)  passes  inwards  and  forwards  beneath 


SUPERIOR   THYROID— LINGUAL 


483 


the  thyro-hyoid  muscle,  and,  perforating  the  thyro-hyoid  membrane  along  with  tlie 
superior  laryngeal  nerve,  supplies  the  intrinsic  muscles  and  mucous  lining  of  tlie 
larynx.  Its  further  distribution  within  the  larynx  is  given  with  the  description  of 
that  organ.  This  branch  sometimes  arises  from  the  external  carotid  direct.  It 
may  enter  the  larynx  by  ](assing  througli  a  foramen  in  the  thyroid  cartilage. 

(4)  The  crico-thyroid — or  inferior  laryngeal  branch  as  it  is  sometimes 
called,  usually  insigniticant  in  size — passes  across  the  crico-thyroid  membrane 
immediately  beneath  the  lower  border  of  the  thyroid  cartilage.  It  anastomoses 
Avith  its  fellow  of  the  opposite  side,  and  usually  sends  a  small  branch  through  the 
membrane  into  the  interior  of  the  larynx.  Occasionally  a  considerable  twig 
descends  over  the  cricoid  cartilage  to  enter  the  isthmus  of  the  thyroid  gland. 
The  crico-thyroid  has,  however,  frequently  been  seen  of  comparatively  large  size — 
once  as  large  as  the  radial,  and  crossing  the  membrane  obliquely.     In  order  to 


Fig.  332.— Scheme  of  Left  Superiok  Thyroid  Artery.     (Walsham.) 

Facial  artery 


Lingual  artery 


Supra-hyoid  branch 
Infra-hyoid  branch 

Superior  laryngeal  branch 


Crico-thyroid  branch 


External  carotid  artery 
Ascending  pharyngeal  artery 

Internal  carotid  artery 


Sterno-mastoid  branch 


Superior  thyroid  artery 


Common  carotid  artery 


nfcrior  thyroid  artery 


avoid  injuring  the  crico-thyroid  artery  in  tlie  operation  of  larvngotomy,  it  is 
usual,  if  the  operation  has  to  be  done  in  a  hurry,  to  make  the  incision  through 
the  crico-thyroid  membrane  in  a  transverse  direction,  and  as  near  to  the  cricoid 
cartilage  as  possible. 


3.  THE  LINGUAL  ARTERY 

The  lingual  artery  Tfig.  333)  arises  from  the  front  of  the  external  carotid, 
between  the  su])erior  thyroid  and  facial  arteries,  often,  as  a  common  trunk  with 
the  latter  vessel,  and  nearly  o])posite  or  a  little  below  the  greater  cornu  of  the  hyoid 
bone.  It  may,  for  })urposes  of  description,  be  divided  into  three  ])ortions:  the  first, 
or  oblique,  extends  from  its  origin  \o  the  outer  edge  of  the  hyo-glossus  muscle;  the 
second,  <>r  horizontal,  lies  l)eneath  the  liyo-glossus;  the  third,  or  ascending, 
beneath  the  tongue.  The  first  or  oblique  portion  is  situated  "in  the  su]>erior 
carotid   triangle,   and  is  superficial,   being  covered   merely   by  the   integuments, 


484 


THE  ARTERIES 


platysnia,  and  deep  fascia.  Here  it  lies  on  the  middle  constrictor  muscle  and 
superior  laryngeal  nerve.  After  ascending  a  short  distance,  it  curves  downwards 
and  forwards  beneath  the  hypoglossal  nerve,  and,  in  the  second  part  of  its 
course,  runs  horizontally  along  the  upper  border  of  the  hyoid  bone,  beneath  the 
hyo-glossus,  l)y  which  it  is  separated  from  the  hypoglossal  nerve,  the  posterior 
belly  of  the  digastricus  and  the  stylo-hyoid  muscles,  and  the  lingual  vein.  In  this 
part  of  its  course  it  lies  successively  on  the  middle  constrictor  of  the  pharynx  and 
the  genio-hyo-glossus  muscle,  and  crosses  a  small  triangular  space  known  as 
'  Lesser' s  triangle,'  the  sides  of  which  are  formed  by  the  tendons  of  the  digastric, 
the  base  by  the  hypoglossal  nerve,  and  the  floor  by  the  hyo-glossus  muscle,  in 
which  situation  it  is  usually  tied.  In  the  third  part  of  its  course  it  ascends 
tortuously,  usually  beneath  the  anterior  margin  of  the  hyo-glossus,  to  the  under 
surface  of  the  tongue,  and  is  thence  continued  to  the  tip  of  that  structure  h'ing 
between  the  lingualis  and  the  genio-hyo-glossus  muscles.  From  the  anterior  edge 
of  the  hyo-glossus  to  its  termination,  it  is  only  covered  by  the  mucous  memlirane 
of  the  under  surface  of  the  tongue.  This  part  of  the  vessel  is  sometimes  called 
the  ranine  artery. 


Fig.  333. — Scheme  of  the  Right  Lingual  Arteey.     (Walsham.) 

Palato-glossus 


Descending  palatine  arleri, 
Palato-pharyngeus 

TONSIL 

Ascending  palatine  branch 

of  facial 

Tonsillar  branch  of  dorsalis 

lingiue 

Tonsillar  branch  of  facial 

Stylo-glosBus 

Bursalis  lingua;  artery 

Middle  constrictor 

HYPOGLOSSAL  JHERVE 

Facial  artery 

Posterior  belly  of  digastric 
and  stylo-hyoid 
Snpru-hi/'jid  branch 

SUP.  LARYNGEAL  X. 

Infra-hyoid  branch 
Internal  carotid  artery 


Ranine  artery 


Genio-hyo- 
glossus 

Artery  of 
1'roenUNt 

Hyo-glossus 

Snblingiial 

arter;/ 

Genio-hyoid 
Anterior  belly 

of  digastric 
Subiiienlal 

artery 
I  artery 


Common  carotid  artery 


Branches  of  the  Lingial  Artery 

The  named  branches  of  the  lingual  artery  are: — (1)  The  hyoid:  (2)  the 
dorsalis  linguae;  (o)  tlie  sulilingual:  and  (4)  the  ranine. 

(1)  The  hyoid,  or  supra-hyoid  (fig.  333),  is  a  small  vessel  Avhich  arises  from 
the  first  part  of  the  lingual,  and  courses  along  the  upper  border  of  the  hyoid  bone, 
superficial  to  the  hyo-glossus,  but  beneath  the  insertion  of  the  posterior  belly  of  the 
digastricus  and  stylo-hyoid.  It  anastomoses  with  its  fellow  of  the  opposite  side, 
and  with  the  infra-hyoid,  a  branch  of  the  superior  thyroid  artery,  and  supplies  the 
contiguous  muscles. 

(2)  The  dorsalis  linguae  (fig.  333)  arises  from  the  second  portion  of  the  lingual 
artery,  usually  under  cover  of  the  posterior  edge  of  the  hyo-glossus  muscle.  It 
ascends  to  the  back  of  the  dorsum  of  the  tongue,  and,  dividing  into  branches, 
supplies  the  mucous  membrane  on  each  side  of  the  V  formed  l)y  the  circumvallate 
papillae.  It  also  supi:)lies  the  pillars  of  the  fauces  and  the  tonsil,  where  it  anasto- 
moses with  the  other  faucial  and  tonsillar  arteries.  Instead  of  a  single  artery,  as 
above  described,  there  may  be  several  small  vessels  running  directly  to  the  parts 
mentioned.     The  artery  anastomoses  in  the   mucous   membrane   by  very  small 


LING  UA  I.— FA  CIA  L  485 

branches  with  the  vessel  of  the  opi)()site  side;  l)ut  the  anastomosis  is  so  minute  tliat 
when  one  lingual  artery  is  injected,  the  injection  merely  passes  across  to  the  opi)0- 
site  side  at  the  tip  of  the  tongue;  and  wlicn  the  tongue  is  divided  accurately  in  the 
middle  line,  as  in  the  removal  of  one-half  of  that  organ,  practically  no  luemorrhage 
occurs. 

(3)  The  sublingual  artery  (fig.  333)  usually  comes  off  from  the  lingual  at  the 
anterior  margin  of  the  hyo-glossus.  It  passes  beneath  the  mylo-hyoid  to  the 
sublingual  gland,  which  it  supplies,  and,  perforating  the  muscle,  anastomoses  with 
the  submental  artery,  a  branch  of  the  facial.  It  also  supplies  branches  to  the  side 
of  the  tongue,  and  gives  off  a  terminal  twig,  which  anastomoses  l)eneath  the  mucous 
membrane  of  the  floor  of  the  mouth  (to  which  it  also  gives  twigs)  with  the  artery 
of  the  opposite  side.  The  artery  of  the  fraenum  is  usually  derived  from  this 
vessel  (tig.  3.')o). 

(4)  The  ranine  artery,  the  termination  of  the  lingual,  courses  forwards  beneath 
the  mucous  membrane,  on  the  under  surface  of  the  tongue,  to  the  tip.  It  lies 
external  to  the  genio-hyo-glossus,  between  that  muscle  and  the  inferior  lingualis, 
and  is  accompanied  by  the  ranine  vein  and  terminal  branch  of  the  gustatory  nerve. 
It  follows  a  very  tortuous  course,  so  that  it  is  not  stretched  Avhen  the  tongue  is 
protruded.  Branches  are  given  off  from  it  to  the  contiguous  muscles  and  mucous 
membrane.  Near  the  tip  of  the  tongue  it  communicates  with  its  fellow  of  the  oppo- 
site side,  as  shown  by  the  fact  that  when  the  lingual  artery  of  one  side  is  injected 
the  injection  fluid  passes  into  the  branches  of  the  artery  of  the  other  side. 


4.  THE  FACIAL  ARTERY 

The  facial  artery  (fig.  334) — also  called  the  external  maxillary — arises  imme- 
diately al)Ove  the  lingual  from  the  fore  part  of  the  external  carotid,  at  times  as  a 
common  trunk  with  the  lingual.  It  courses  forwards  and  upwards  in  a  tortuous 
manner  to  the  lower  jaw,  and,  passing  over  the  body  of  this  Ijone  at  the  anterior 
edge  of  the  masseter  muscle,  winds  ol)liquely  upwards  and  forwards  over  the  face 
to  the  inner  canthus  of  the  eye,  where  it  inosculates,  under  the  name  of  the  angular 
artery,  with  the  nasal  liranch  of  the  ophthalmic.  It  is  usually  divided  into  two 
portions — the  cervical  and  the  facial. 

The  cervical  portion  (fig.  334)  ascends  tortuously  from  its  origin  from  the 
external  carotid  u})Avards  and  forwards  beneath  the  posterior  belly  of  the  digastric 
and  stylo-hyoid  muscles,  and  usually  also  beneath  the  hypoglossal  nerve,  and  then 
making  a  turn  runs  horizontally  forwards  for  a  short  way  lieneath  the  jaw,  either 
imbedded  in  or  lying  under  the  sul)maxillary  gland.  It  has  here  the  mylo-hyoid 
and  stylo-glossus  beneath  it.  On  leaving  the  cover  of  the  gland  it  forms  a  l(Jop 
passing  first  downwards  and  then  upwards  over  the  lower  liorder  of  the  jaw  imme- 
diately in  front  of  the  masseter  muscle,  where  it  is  superficial,  being  merely  covered 
by  the  integument  and  platysma.  Here  it  can  be  felt  beating,  and  can  be  readily 
compressed.  In  the  above  course  it  lies  in  the  posterior  part  of  the  submaxillary 
triangle,  and,  in  addition  to  the  structures  already  mentioned  as  crossing  it,  is 
covered  by  the  skin,  superficial  fascia,  and  platysma,  and  by  one  or  two  submaxil- 
lary lymphatic  glands.  The  vein  is  separated  from  the  artery  liy  the  submaxillary 
gland,  the  posterior  l)elly  of  the  digastric  muscle,  the  stylo-hyoid  muscle,  and  the 
hypoglossal  nerve. 

The  facial  portion  (fig.  334)  of  the  facial  artery  ascends  tortuously  forwards 
towards  the  angle  of  the  mouth,  i)assing  under  the  })latysma  (risorius)  and  zygomatic 
muscles  and  the  supramaxillary  and  buccal  ])ranches  of  the  facial  nerve.  It  here 
lies  upon  the  jaAV  and  the  l^uceinator  muscle.  Thence  it  courses  upwards  by 
the  side  of  the  nose  towards  the  inner  canthus  of  the  eye,  being  covered  by  the 
levator  labii  superioris,  levator  labii  superioris  akvque  nasi,  and  infraorlntal  branches 
of  the  facial  nerve,  and  lying  on  the  levator  anguli  oris  (sometimes  on  the  levator 
labii  superioris,  instead  of  beloAV  it)  and  the  infraorbital  branches  of  the  fifth  nerve. 
The  facial  vein  takes  a  much  straighter  course  than  the  artery,  is  separated  from  it 
by  the  zygomatic  muscles,  and  lies  to  its  outer  side. 


486 


THE  ARTERIES 


Branches  of  the  Facial  Aktery  in  the  Xeck 

The  branches  of  the  facial  artery  in  the  neck  are: — (1 )  The  asecndin.ir,  or 
inferior  palatine;  (2)  the  tonsillar;  (3)  the  glandular;  (4)  the  muscular;  (5)  the 
submental. 

(1)  The  ascending,  or  inferior  palatine  (figs.  333,  334) — the  first  branch  of 
the  facial,  but  often  a  distinct  branch  of  the  external  carotid — ascends  between  the 

Fig.  334. — Scheme  of  the  Right  Facial  Aktery.    (WulsLam.) 


Orbicularis  palpebrarum 
muscle 


Trans lerxe  facial  arterii 


Zygomaticus  major 
muscle 


Buccinator  muscle 
Masseteric  branch 
Masseter  muscle 


Stylo-pharyngeus 

muscle 

Stylo-glossus  muscle 

Ascending  palatini 

hrnnch 

Timsiltar  branch 


Facial  artery  r 
External  carotid 
nrlery 
Posterior  belly  of 
digastric  muscle 

Lingual  artery 


rontal  branch  of  ophthalmic 

artery 
'asal  branch  of  ophthalmic 

artery 


Anyitlar  nrltry 
Levator  labii  super- 
ioris   et   alee    uai>i 
muscle 
—  Infraurbitat  artfry 

Levator  labii  super- 

ioris  proprius 
Lateralis  nasi  ar. 
Levator  anguli  oris 
muscle 

Artery  of  Sfpttnn 

Superior  coronary 

artery 

Risorius  muscle 


Inferior  coronary  artery 

Mental  branch  of  inferior 

dental  artery 
Depressor  labii  inferioris 

muscle 
Inferior  labial  artery 
Depressor  anguli  oris 
muscle 

Submental  artery 
Branches  to  submaxillary 
gland 

Anterior  belly  of  digastric  muscle 
Mylo-hyoid  muscle 

usele 


HYPOGLOSSAL  NERVE 


internal  and  external  carotids,  and  then  lietween  the  stylo-glossus  and  stylo- 
])haryngeus  muscles,  and  on  reaching  the  wall  of  tlie  pharynx  is  euntinued  upwards 
between  the  su])erior  constrictor  and  internal  i^tcrygoid  muscles  towards  the  bas(>  of 
the  skull  as  high  as  the  levator  palati,  Avlicreit  divides  into  two  branches,  a  palatine 
and  a  tonsillar.     One  of  these  branches,  the  palatine,  passes  with  the  levator  ])alati 


FACIAL  487 

over  the  curved  upper  margin  of  the  superior  constrictor  to  the  goft  palate,  wliere 
it  is  (listril)Uted  to  tlie  tissues  constituting  that  structure,  and  anastomoses  with  its 
fellow  of  the  op})Osite  side  and  with  the  descending  palatine  branch  of  the  internal 
maxillary,  and  the  ascending  jtharyngeal,  Avhich  vessel  often  to  a  great  extent 
sup])lies  the  place  of  this  artery.  The  other  branch,  the  tonsillar,  su})plies  the 
tonsil  and  the  Eustachian  tube,  anastomosing  with  the  tonsillar  branch  of  the  facial 
and  ascending  pharyngeal  arteries.  The  ascending  pjalatine  arter}'  supplies  the 
muscles  between  which  it  nms  on  its  way  to  the  palate. 

(2)  The  tonsillar  branch  (fig.  334)  ascends  between  the  stylo-glossus  and 
internal  pterygoid  muscles  to  the  level  of  the  tonsil,  where  it  perforates  the  superior 
constrictor  muscle  of  the  pharynx,  and  ends  in  the  tonsil,  anastomosing  with  the 
tonsillar  branch  of  the  ascending  palatine  and  with  the  other  tonsillar  arteries  (fig. 
833).      It  gives  liranches  also  to  the  root  of  the  tongue. 

(3)  The  glandular  or  submaxillary  branches  are  distributed  to  the  submax- 
illary gland  as  the  artery  is  passing  through  or  beneath  that  structure.  A  small 
twig  from  one  of  these  branches  usually  supplies  Wharton's  duct. 

(4)  The  muscular  branches  are  small  twigs  given  off  irregularly  to  the  con- 
tiguous muscles,  viz.  the  posterior  belly  of  the  digastric,  the  stylo-hyoid,  the  stylo- 
glossus, and  the  mylo-hyoid  muscles. 

(5)  The  submental  branch  (fig.  334)  comes  ofT  from  the  facial  as  the  latter 
vessel  lies  under  cover  of  the  submaxillary  gland,  and,  passing  forwards  on  the 
mylo-hyoid  muscle  l>etween  the  base  of  the  jaw  and  the  anterior  belly  of  the  digas- 
tricus,  supplies  these  structures  and  the  overlying  platysma  and  integuments.  It 
gives  off  the  following  small  branches: — (a)  muscular,  to  the  muscles  between 
which  it  runs;  (b)  perforating,  whicli  passes  through  the  mylo-hyoid  to  anasto- 
mose with  the  sublingual;  (c)  cutaneous,  to  the  integuments  covering  it;  ((/) 
mental,  which  turns  over  the  border  of  the  lower  jaw  near  the  symphysis,  and, 
after  supplying  a  branch  to  the  depressor  labii  inferioris,  the  levator  menti,  and  the 
other  adjacent  soft  tissues  forming  the  chin  and  lip,  anastomoses  with  the  mental 
branch  of  the  inferior  dental,  the  inferior  labial,  and  the  artery  of  the  opposite  side. 

Branches  of  the  Facial  Artery  on  the  Face 

From  the  outer  or  concave  side  of  the  artery  are  given  off: — (1)  masseteric 
branches  which  ascend  over  the  masseter  to  anastomose  with  the  masseteric  branch 
of  the  internal  maxillary  artery  and  the  transverse  facial  artery;  and  (2)  buccal, 
which  pass  upwards  over  the  buccinator  and  anastomose  with  the  buccal  branch  of 
the  internal  maxillary,  the  transverse  facial,  and  the  infraorbital  arteries. 

From  the  inner  or  convex  side  the  following  larger  and  named  vessels  are  given 
off: — (1)  The  inferior  labial;  (2)  the  inferior  coronary;  (3)  the  superior  coronary; 
(4j  the  lateralis  na.si;  and  (5)  the  angular. 

(1)  The  inferior  labial  artery  arises  either  separately  from  the  facial  artery,  or 
in  common  with  the  next  branch — the  inferior  coronary.  It  courses  forwards 
beneath  the  depressor  anguli  oris,  and  over  the  depressor  labii  inferioris,  and,  after 
supplying  the  contiguous  muscles  and  integuments,  anastomoses  below  Avith  the 
submental,  above  with  the  inferior  coronary,  and  between  the  two  with  the  mental 
branch  of  the  inferior  dental  which  escapes  from  the  mental  foramen. 

(2)  The  inferior  coronary  artery  arising  from  the  facial  a  little  above  the 
inferior  lal)ial,  or  in  connnon  with  it,  passes  forwards  beneath  the  depressor  anguli 
oris  towards  the  angle  of  the  mouth,  thence  skirts  along  the  lower  lip,  between 
the  mucous  membrane  and  orbicularis  oris,  about  a  quarter  to  half  an  inch  from 
the  junction  of  the  skin  and  mucous  membrane,  and  anastomoses  with  its  fellow 
of  the  opposite  side.  It  can  readily  be  felt  beating  during  life  by  pressing  the  lip 
between  finger  and  thumb.  It  giv-^s  off  descending  branches  which  anastomose 
with  the  inferior  labial  and  the  mental  branch  of  the  inferior  dental  (or  mandi- 
bular) artery. 

(3)  The  superior  coronary  artery,  arising  from  the  facial  a  little  higher  than 
the  inferior  coronary,  passes  forwards  beneath  the  zygomaticus  major,  and  then, 
like  the  inferior  coronary,  courses  tortuously  along  the  lower  margin  of  the  upper 
lip  between  the  orbicularis  oris  and  the  mucous  membrane  about  half  an  inch 


488  THE  ARTERIES 

from  the  junction  of  the  mucous  meml)rane  and  the  skin.  It  is  usually  larger 
than  the  inferior  coronary.  The  superior  coronary  anastomoses  Avith  its  fellow 
of  the  opposite  side,  and  gives  off  a  small  artery  to  the  septum — arteria 
septi  nasi.  Compression  of  this  vessel  will  sometimes  control  luemorrhage  from 
the  nose. 

In  the  operation  for  hare  lip,  the  pin  or  suture  should  l^e  passed  sufficiently  deep 
to  transfix  the  divided  coronary  artery,  or  haemorrhage  may  continue  into  the  mouth. 
Bleeding  from  either  coronary  vessel  can  be  readily  controlled  by  the  thumb  and 
forefinger  grasping  tlie  lip. 

(4)  The  lateral  nasal  artery  (fig.  334)  is  a  small  twig  or  twigs  given  oft'  from 
the  facial  opposite  the  ala  of  the  nose.  It  passes  forwards  over  the  ala  and  lower 
\>axi  of  the  nose,  supplying  the  integuments,  muscles,  and  cartilages,  and  anasto- 
moses with  the  artery  of  the  septum,  the  vessel  of  the  opposite  side,  and  the  nasal 
branches  of  the  ophthalmic. 

(5)  The  angular  artery  (fig.  334)  is  the  name  given  to  the  termination  of  the 
facial  arter}'.  It  anastomoses  at  the  inner  canthus  of  the  eve  Avith  the  nasal 
branch  of  the  ophthalmic.  It  is  accompanied  by  the  anterior  descending  vein 
from  the  scalp.  It  lies  to  the  inner  side  of  the  lachrymal  sac,  and  supplies  that 
structure  and  the  lower  part  of  the  orbicularis  oculi,  beneath  which  a  l^ranch  anas- 
tomoses with  the  infraorbital  artery.  The  situation  of  the  artery  to  the  inner  side 
of  the  lachrymal  sac  should  be  borne  in  mind  in  opening  a  lachrymal  abscess. 


5.  THE  OCCIPITAL  ARTERY 

The  occipital  artery  (fig.  335)  is  usually  a  vessel  of  considerable  size.  It 
comes  off  from  the  posterior  part  of  the  external  carotid  opposite  the  facial,  or  else 
a  little  higher  than  that  vessel.  It  then  winds  upwards  and  l)ackwards  to  the 
interval  between  the  mastoid  process  of  the  temporal  lione  and  transverse  process 
of  the  atlas,  and,  after  running  horizontally  liackwards  in  the  occipital  groove 
on  the  mastoid  j^ortion  of  the  temporal  bone,  again  turns  upwards,  and  ends  liy 
ramifying  in  the  scalj)  over  the  Ixick  of  the  skull,  extending  as  far  forwards  as  the 
vertex. 

The  vessel  may  be  divided  into  three  parts — viz.  that  internal  to  the  sterno- 
mastoid  muscle;  that  beneath  the  sterno-mastoicl;  and  that  external  to  the  sterno- 
mastoid. 

In  the  first  part  of  its  course  the  occipital  artery  is  covered  l)y  the  integu- 
ments and  fascia,  and  is  more  or  less  overlapped  by  the  posterior  Ijelly  of  the 
digastric  muscle,  the  parotid  gland,  and  temporo-maxillary  vein.  It  is  crossed  by 
the  hj'po-glossal  nerve  as  the  latter  winds  forwards  over  the  carotid  vessels  to  reach 
the  tongue.  It  successively  crosses  in  front  of  the  internal  carotid  arter}-,  the  hypo- 
glossal nerve,  the  pneumogastric  nerve,  the  internal  jugular  vein,  and  the  spinal 
accessory  nerve. 

In  the  second  part  of  its  course  it  sinks  deeply  beneath  the  digastric  muscle 
into  the  interval  between  the  mastoid  process  of  the  temporal  l)one  and  the  trans- 
verse process  of  tlie  atlas.  It  is  here  covered  by  the  sterno-mastoid,  si)lenius  capitis, 
and  trachelo-mastoid  muscles  and  by  the  origin  of  the  digastricus;  and  lies,  first 
on  the  rectus  capitis  lateralis,  which  separates  it  from  the  vertebral  artery,  then  in 
the  occipital  groove  on  the  mastoid  portion  of  the  temporal  lione,  and  then  on  the 
insertion  of  the  supcricn-  oblicpie  muscle. 

In  the  third  part  of  its  course  it  enters  the  triangular  interval  formed  by  the 
diverging  borders  of  the  s})lenii  capitis  and  the  sujierior  curved  line  of  the  occipital 
bone.  Here  it  lies  beneath  the  integuments  and  the  aponeurosis  uniting  the  occi- 
pital attachments  of  the  sterno-mastoid  and  trapezius,  and  rests  upon  thecomplexus 
just  before  the  insertion  of  that  muscle  into  the  occipital  l)one.  In  company  with 
the  great  occipital  nerve,  it  perforates  either  this  aponeurosis,  or  less  often  the 
posterior  belly  of  the  occipito-frontalis,  and  folhjws  roughly,  l>ut  in  a  tortuous 
course,  the  line  of  the  lambdoid  suture  lying  between  the  integument  and  the 
cranial  aponeurosis.  In  the  scal]>  it  divides  into  several  large  l)ranches,  Avhich 
ramify  over  the  ])ack  of  the  skull  and  reach  as  far  forwards  as  the  vertex.     They 


OCCIPITAL 


489 


anastoinoso  with  tlie  corresponding  l)ranches  of  the  opposite  side,  and  with  the 
posterior  auricular,  and  the  superficial  temporal  arteries. 

Branches  of  the  Occipital  Artery 

The  branches  of  the  occipital  artery  are: — (1)  The  sterno-mastoid;  (2)  the 
posterior  meningeal;  (8)  the  auricular;  (4)  the  mastoid;  (5)  the  princeps  cervicis; 
(B)  the  communicating;  (7)  the  muscular;  and  (8)  the  terminal.  The  sterno- 
mastoid,  ]K)sterior  meningeal,  auricular,  and  princeps  cervicis  are  the  four  vessels 
usually  named  amongst  the  above  branches. 


Fig.  335. — Scheme  of  Right  Occipital  and  Posterior  Auricular  Arteries.     (Walsham. 


Anterior  branch  of  pos- 
terior auricular 

Posterior  branch  of  pos- 
terior auricular 


PAROTID  GLANO 
Sterno-mastoid,  cut 

Auricular  branch  of 
occipital 

Rectus  capitis  lateralis 

SPIXA  L  A  CCESSOR  Y 
NERVE 
Posterior  auricular 

Internal  jugular  vein 
Facial  artery 

HYPOGLOSSAL  X. 

Linf/iiiil  artery 
PXE I  'MOG  A  S  TRI'C 
NER  VE 

Superior  thyroid 

Common  carotid 


External  branch  of 
occipital 


Internal  branch  of 
occipital 


Complexus 

Priceps  cervicis 

Superior  oblique 

Traehelo-mastoid,  cut 
Splenius  capitis,  cut 
Meningeal  branches 

Sterno^nastoid  branch  of 
occipital 

Internal  carotid 
Sterno-mastoid 

External  carotid 
Trapezius 


(1)  The  Sterno-mastoid  branch  (fig.  335)  usually  comes  off  from  the  occipital 
just  after  its  origin  from  the  carotid,  and,  passing  downwards  and  backwards  oyer 
the  loop  of  the  hypoglossal  nerve,  enters  the  sterno-mastoid  muscle  in  company  with 
the  spinal  accessory  nerve.  At  times  this  artery  is  a  distinct  branch  of  the  external 
carotid.  The  hypoglossal  nerve  then  as  a  rule  loops  round  it  instead  of  round  the 
occiytital. 

(2)  The  posterior  meningeal  branches  (fig.  335),  one  or  more  in  number, 
are  long  slender  vessels  whirh  leave  the  occipital  artery  as  it  crosses  the  internal 
jugular  vein,  and,  ascending  along  that  vessel,  ])ass  with  it  through  the  jugular 
foramen,  and  are  distributed  to  the  dura  mater  lining  the  posterior  fossa  of  the 
skull. 


490  THE  ARTERIES 

(3)  Tlie  auricular  branch  ascends  over  the  mastoid  process  to  the  back  of  the 
ear,  and  suppHes  the  pinna  and  concha.  It  sometimes  takes  the  pkiee  of  the 
posterior  auricular  artery  (f^,L^  335). 

(4)  The  mastoid  branch  is  a  small  tAvig  that  passes  into  the  skull  through  the 
mastoid  foramen,  sui)})lying  the  dura  mater,  the  diploe,  the  walls  of  the  lateral 
sinus  and  the  mastoid  cells. 

(5)  The  princeps  cervicis  (fig.  335),  the  largest  of  the  branches  of  the  occipital, 
arises  from  tliat  artery  just  before  it  emerges  from  beneath  the  sjtlenius,  and, 
descending  for  a  short  distance  between  the  splenius  and  complexus,  divides  into  a 
supertieial  and  a  deep  branch.  The  superficial  branch  perforates  the  splenius, 
supplies  branches  to  the  trapezius,  and  anastomoses  Avith  the  superficial  cervical,  a 
l)ranch  of  the  transverse  cervical  artery.  The  deep  branch  passes  downwards 
between  the  complexus  and  semispinalis  colli,  and  anastomoses  with  the  deeji 
cervical  branch  of  the  suj^erior  intercostal  and  with  branches  of  the  vertebral 
(fig.  338).  The  anastomoses  between  the  above-mentioned  arteries  form  important 
collateral  channels  after  ligature  of  the  common  carotid  and  sul^clavian  arteries 
(fig.  330). 

(6)  The  communicating  branches  run  deeph'  into  the  triangle  formed  Ity  the 
superior  oblique,  inferior  obli(|ue,  and  rectus  capitis  posticus  major  muscles,  and 
there  anastomose  with  brandies  of  the  vertelu'al. 

(7)  Muscular  branches  throughout  the  course  of  the  occipital  artery  are  dis- 
tributed to  the  contiguous  muscles — viz.  in  addition  to  the  sterno-mastoid  which 
receives  a  named  branch,  to  the  digastricus,  stylo-hyoid,  splenius,  trachelo-mastoid, 
trapezius,  the  small  muscles  forming  the  suboccipital  triangle,  and  the  posterior 
belly  of  the  occipito-frontalis. 

(8)  The  terminal  or  superficial  branches  (fig.  335),  usually  two  in  number, 
named  from  their  position  internal  and  external,  ramify  over  the  scalp,  and  have 
already  been  described.  The  internal  branch  generally  gives  off  a  twig  which  enters 
the  parietal  foramen  (parietal  artery)  and  is  distri1)uted  to  the  dura  mater.  The 
occipital  artery  may  also  give  off  the  stylo-mastoid,  the  posterior  auricular,  or  the 
ascending  pharyngeal  arteries. 


6.  THE  POSTERIOR  AURICULAR  ARTERY 

The  posterior  auricular  artery  (fig.  335)  arises  from  the  posterior  part  of  the 
external  carotid  artery,  usually  immediately  above  the  posterior  belly  of  the 
digastric,  about  the  level  of  the  tip  of  the  styloid  process.  Occasionally  it  arises 
under  cover  of  the  digastric,  quite  close  to,  or  as  a  common  trunk  with,  or  as  a 
l)ranch  of,  the  occipital.  It  courses  upwards  and  backwards  in  the  parotid  gland 
to  the  notch  between  the  margin  of  the  external  auditory  meatus  and  the  mastoid 
process,  where  it  divides  into  two  branches,  an  anterior  or  auricular,  and  a  posterior 
or  mastoid.  In  this  course  it  rests  on  the  styloid  process,  crosses  the  spinal 
accessory  nerve,  and  is  crossed  itself  by  the  facial  nerve. 

Branches  of  the  Posterior  Auricular  Artery 

The  branches  of  the  posterior  auricular  artery  are: — (1)  The  parotid;  (2) 
the  muscular;  (3)  the  stylo-mastoid;  (4)  the  anterior  terminal,  or  auricular;  (5) 
the  posterior  terminal,  or  mastoid  (fig.  335). 

(1)  The  parotid  branches  are  distributed  to  the  lower  portion  of  the  parotid 
gland,  and  anastomnse  with  tlie  other  parotid  arteries. 

(2)  The  muscular  branches  sup})ly  the  posterior  belly  of  the  digastricus,  the 
stylo-hyoid,  and  retraliens  auvem  muscles. 

(3)  The  stylo-mastoid  branch  comes  off  from  the  posterior  auricular  artery 
just  before  it  reaches  the  notch  between  the  margin  of  the  external  auditory  meatus 
and  the  mastoid  process,  and,  following  the  facial  nerve  upwards,  enters  tlie  stylo- 
mastoid foramen  in  the  temporal  bone.  In  the  aqueduct  of  Fallopius  it  gives  off 
the  following  named  twigs: — (a)  meatal,  to  the  external  auditory  meatus;  (}>) 
mastoid,  to  the  mastoid  cells  and  mastoid  antrum;   (r)  stapedic,  wliieh  runs  for- 


POSTERIOR  AURICULAR— TEMPORAL  491 

wards  to  the  stapedius  muscle;  (d)  tympanic,  wliich  anastomoses  Avith  the  tympanic 
branch  of  the  internal  maxillary,  formiui:-  witli  it  in  the  ffftus  a  vascular  circle 
around  the  membrana  tympani;  (c)  vestibular,  to  the  vestibule  and  semicircular 
canals;  and  (/)  terminal,  a  small  twig  which  enters  the  hiatus  Fallopii  with  the 
great  superficial  })etrusal  nerve,  and  anastomoses  with  the  petrosal  l»ranch  of  the 
large  middle  meningeal  artery. 

(4)  The  anterior  terminal  or  auricular  branch  passes  upwards  liehind  the  ear 
and  beneath  the  rctrahens  aurem,  sujtplying  the  l)ack  of  the  pinna  and  neighbour- 
ing integuments.  It  anastomoses  with  the  posterior  branch  of  the  superficial  tem- 
poral artery.  The  branches  to  the  pinna  not  only  supply  the  back  of  that  structure. 
l»ut  some  perforate  the  cartilage,  and  others  turn  over  its  free  margin  to  supply  the 
front  surface;  there  they  anastomose  with  the  anterior  auricular  branches  from  the 
temporal. 

(5)  The  posterior  terminal,  or  mastoid  or  occipital  branch,  passes  upwards 
and  backwards,  crossing  the  aponeurotic  insertion  of  the  sterno-mastoid  muscle.  It 
gives  a  branch  to  the  posterior  belly  of  the  occipito-frontalis,  and  anastomoses  Avith 
the  occipital  artery. 

7.  THE  TEMPORAL  ARTERY 

The  temporal  artery,  or  superficial  temporal  artery — the  smaller  of  the  two 
terminal  divisions  of  the  external  carotid,  thougli  apparently  the  direct  continuation 
of  that  vessel — arises  opposite  the  neck  of  the  lower  jaw  and,  under  cover  of  the 
parotid  gland,  passes  upwards  in  the  interval  between  the  condyle  and  the  external 
auditory  meatus  to  the  zygoma,  lying  on  the  capsule  of  the  joint.  Thence  it  ascends 
over  the  posterior  root  of  that  process  and  the  temporal  aponeurosis  for  about  an 
inch  and  a  half  to  two  inches  (4  cm.),  and  there  divides  into  an  anterior  and  a  pos- 
terior branch.  It  is  surrounded  by  a  dense  plexus  of  sympathetic  nerves,  and  is 
accompanied  by  the  auriculo-temporal  nerve,  which  lies  beneath  and  generally  a 
little  Ijehind  it.  It  is  crossed  by  the  temporo-facial  division  of  the  facial  nerve, 
and  by  the  attrahens  aurem  muscle.  As  it  crosses  the  zygoma  it  can  be  readily  felt 
pulsating  immediately  in  front  of  the  ear,  and  in  this  situation  can  be  compressed 
against  the  bone.  It  is  here  quite  superficial,  being  merely  covered  by  the  integu- 
ments and  a  delicate  prolongation  from  the  cervical  fascia. 

Branches  of  the  Temporal  Artery 

The  branches  of  the  temporal  artery  are: — (1)  The  parotid;  (2)  the 
articular;  (3)  the  masseteric;  (4)  the  auricular,  or  anterior  auricular;  (5)  the 
transverse  facial;  (6)  the  middle  temporal;  (7)  the  orbital;  (8)  the  anterior 
terminal;    (9)  the  posterior  terminal. 

(1)  The  parotid  branches  are  small  twigs  given  off  in  the  substance  of  the 
parotid  gland  to  that  structure. 

(2)  The  articular  branches  supply  the  temporo-maxillarv  joint. 

(3)  The  masseteric  are  one  or  two  small  branches  to  the  masseter  muscle. 

(4)  The  auricular  or  anterior  auricular  branches  su})ply  the  tragus,  the 
pinna,  and  the  lolmle  of  the  ear,  and  to  some  extent  the  external  auditory  meatus. 

(5)  The  transverse  facial  is  the  largest  branch  of  the  temporal.  It  sometimes 
arises  from  the  external  carotid  as  a  common  trunk  with  the  temjioral.  It  is  at 
first  deeply  seated  in  the  substance  of  the  jiarotid  gland.  l)ut,  soon  emerging  from 
under  that  part  of  the  gland  known  as  the  socia  parotidis,  courses  transversely 
across  the  masseter  muscle  about  a  finger's  breadtli  below  the  zygoma.  Steno's 
duct  runs  below  it,  and  the  infraorbital  branches  of  the  facial  nerve  above  it.  It 
supplies  the  parotid  gland,  the  masseter  muscle,  and  the  skin  of  the  face,  and 
anastomoses  with  the  infraorbital,  the  buccal,  and  the  facial  arteries. 

(6)  The  middle  temporal  branch,  or  middle  deep  temporal  artery  (fig.  336), 
arises  just  aV»ove  the  zygoma,  and,  perforating  the  temporal  aponeurosis  and 
temporal  muscle,  ascends  on  the  squamous  portion  of  the  temporal  bone,  and 
anastomoses  with  the  posterior  deep  temporal  artery. 

(7)  The  orbital  or  zygomatico-orbital  branch  (fig.  336),  as  it  is  sometimes 


492  THE  ARTERIES 

called — at  times  a  branch  of  the  deep  temporal — passes  forwards  along  the  upper 
border  of  the  zygoma  in  the  fat  lietween  tlie  superficial  and  deep  layers  of  the  tem- 
poral aponeurosis,  and,  after  giving  branches  to  the  orbicularis  oculi,  sends  one  or 
more  twigs  into  the  orbit  through  the  orljital  foramina  in  the  malar  bone  to  anas- 
tomose with  the  lachrymal  and  })al})el_>ral  branches  of  the  ophthalmic. 

(8)  The  anterior  terminal  branch  ramifies  tortuously  in  an  upward  and 
forward  direction  over  the  front  part  of  the  skull.  It  lies,  first  between  the  skin 
and  temporal  fascia,  and  then  between  the  skin  and  occij^ito-frontalis  aponeurosis. 
It  supplies  the  anterior  belly  of  the  occipito-frontalis  and  the  orl)icularis  oculi 
nuiscles,  and  anastomoses  with  the  supraorljital,  supratrochlear,  and  frontal 
branches  of  the  ophthalmic,  and  with  the  corresponding  artery  of  the  opposite 
side.  The  secondary  branches  given  off'  from  this  vessel  to  the  scalp  run  from 
before  backwards. 

(9)  The  posterior  terminal  branch  ramifies  on  the  side  of  the  head  between 
the  skin  and  temporal  fascia.  Its  branches  anastomose,  in  front  with  the  anterior 
terminal  branch;  behind,  with  the  posterior  auricular  and  occipital  arteries;  and 
al)ove,  across  the  vertex  of  the  skull,  with  the  corresponding  artery  of  the  opposite 
side. 

8.  THE  INTERNAL  MAXILLARY  ARTERY 

The  internal  maxillary  artery  (fig.  336)  is  the  larger  of  the  tAvo  terminal 
divisions  of  the  external  carotid.  It  arises  opposite  the  neck  of  the  jaw  in  the 
substance  of  the  parotid  gland,  and,  passing  first  between  the  neck  of  the  jaw  and 
the  spheno-mandibular  ligament — the  so-called  internal  lateral  ligament  of  the  lower 
jaw — and  then  between  the  external  and  internal  pterygoid  muscles,  sinks  deeply 
into  the  spheno-maxillary  fossa,  and  there  breaks  up  into  its  terminal  branches. 
It  is  divided  into  three  portions:  a  maxillary,  a  pterygoid,  and  a  spheno- 
maxillar3\ 

(1)  In  the  first  part  of  its  course  (the  maxillary  portion)  the  artery  lies 
between  the  neck  of  the  jaw  and  the  spheno-mandibular  ligament,  taking  a  hori- 
zontal course  forwards  and  inwards  parallel  to  and  a  little  below  the  auriculo- 
temporal nerve  and  the  external  pterygoid  muscle.  It  is  here  embedded  in  the 
deep  portion  of  the  parotid  gland,  and  usuall}^  crosses  in  front  of  the  mandibular 
(inferior  dental)  nerve. 

(2)  In  the  second  part  of  its  course  (the  pterygoid  portion)  the  artery  lies 
either  between  the  two  pterygoid  muscles  and  the  ramus  of  the  jaw,  and  then  turns 
upwards  over  the  outer  surface  of  the  external  pterygoid,  beneath  tlie  temporal 
muscle  to  gain  the  two  heads  of  the  external  pterygoid,  between  which  it  sinks  into 
the  spheno-maxillary  fossa;  or  it  passes  behind  and  internal  to  the  external  ptery- 
goid, and  is  covered  l)y  that  muscle  till  it  reaches  the  interval  between  its  two 
heads,  where  it  then  often  forms  a  projecting  loop  as  it  turns  into  the  spheno- 
maxillary fossa. 

(3)  In  the  third  part  of  its  course  (the  spheno-maxillary  portion)  the 
artery  lies  in  the  spheno-maxillary  fossa  beneath  tlie  maxillary  division  of  the  fifth 
nerve,  and  in  close  relationship  with  Meckel's  ganglion,  and  there  breaks  uj)  into  its 
terminal  branches. 

Branches  of  the  Internal  Maxillary  Artery 

The  branches  of  the  internal  maxillary  artery  are: — 

(A)  From  the  first  part : — (1)  The  deep  auricular;  (2)  the  tympanic;  (3)  the 
large  middle  meningeal;  (4)  the  mandibular  (inferior  dental);  (5)  the  small 
middle  meningeal  (sometimes).  All  these  vessels  pass  through  bony  or  cartilagi- 
nous canals. 

(B)  From  the  second  part: — (1)  The  masseteric;  (2j  the  ])osterior  deep 
temporal;  (3)  the  internal  pterygoid;  (4)  the  external  ]iterygoid;  (o)  the  l)uccal; 
and  (6)  the  anterior  dee))  tem])<)ral.      All  these  branches  supply  muscles. 

(C)  From  the  third  part: — (1)  The  posterior  dental,  or  alveolar;  (2)  the 
infra-orbital;   (3)  the  posterior,   or  descending  i)alatinc;   (4)  the  Vidian;  (5)  the 


INTERXA L   MA XILLA R  Y 


493 


pterygo-])alatine;  and  (6)  the  naso-  or  sphono-palatine.  All  tliese  branches  pass 
through  l)ony  canals. 

Braiirhes  of  the  First  Part  of  the  Liter  ml  Maxilla  ri/  Arteri/. — (1)  TIr-  deep 
auricular  (fig.  83(i)  passes  upwards  in  the  substance  of  the  parotid  gland  behind 
the  capsule  of  the  temj)oro-maxillary  joint,  and,  perforating  the  bony  or  cartilagi- 
nous wall  of  the  external  auditory  meatus,  supplies  the  skin  of  that  passage  and 
the  nienibrana  tynipani.  It  at  times  gives  a  branch  to  the  joint  as  it  passes  behind 
the  temporo-maxillary  capsule. 

(2)  The  tympanic  branch,  or  Glaserian  artery,  is  a  long  slender  vessel,  which 
runs  upwards  bcliind  the  condyle  of  llic  jaw  to  the  Glaserian  fissure,  through  which 
it  passes  to  the  interior  of  the  tympanum.  Here  it  supi)lies  the  lining  membrane 
of  that  cavity  and  the  laxator  tympani  muscle,  and  anastomoses  with  the  other 
tym})anic  arteries,  forming  with  the  tympanic  branch  of  the  stvlo-mastoid  arterv  a 


Fig.  336.— Scheme  of  Left  Ixterxal  Maxillaey  Artery.     (Walsliam.) 

Infraorhital  artery  and  nerve  Sjjfieno-pataline  branch 

Posterior  or  descending  palatine  branch 
ine  branch 

anch 

ior  deep  teiiijjoral  artery 

ternul plerygoid  branch 


Orbital  branch 


yaxal  branch 
Anterior 
dental  hr 

Labial  branch 

Posterior  dental 

branch 


Incisive  branch 
Mental  branch 


Submental  branch 


Posterior  deep  temporal  artery 
j     I,     I  y  Small  meningeal 

"/  /'.'  /  /    ,  /  artery 

Middle  meningeal 
artery 


Temporal  artery 
Ti/ni/ianic  brajtch 

Ii'ep  auricular 

branch 
I  IRICi'LO-TEM- 
fORAL  XERVK 

Masseteric  branch 


External  carotid 
artery 


Internal  lateral  or 
spheno-mandibu- 
lar  ligament 

Mandibular  or 
inferior  dental 
artery  and  nerre 


Buccal  branch  with         Internal  pterygoid  branch 
~     piyrtioH  of  buccal  nerve 
Mylo-liyoidean  branch 


vascular  circle  around  the  membrana  tympani.  This  circle  is  more  distinct  in  the 
f(jetus  than  in  the  adult. 

(3)  The  large  middle  meningeal  is  the  largest  branch  of  the  internal  maxillary 
artery.  It  comes  off  from  that  vessel  as  it  lies  between  the  spheno-niandibular  liga- 
ment and  the  ramus  of  the  jaw,  and  under  cover  of  the  external  ]iteryg(iid  passes 
directly  upwards  to  the  foramen  spinosum,  through  which  it  enters  the  interior  of 
the  cranium.  In  this  part  of  its  course  it  is  crossed  by  the  chorda  tympani  nerve; 
and  just  before  it  enters  the  foramen  is  embraced  by  the  two  heads  of  origin  of  the 
auriculo-temporal  nerve  (fig.  336). 

The  trunk  of  the  mandibular  division  of  the  fifth  nerve,  as  the  latter  emerges 
through  the  foramen  ovale,  lies  in  front  of  the  artery.  As  the  artery  passes  upwards 
it  is  surrounded  by  filaments  of  the  symjtathetic  nerve,  and  is  accompanied  by  two 
veins  which  open  into  the  internal  maxillary  vein.      On  entering  the  skull  it  ramifies 


41)4 


THE  ARTERIES 


between  the  bone  and  dura  mater,  supplying  both  structures.  It  at  first  ascends  for 
a  short  distance  in  a  groove  on  the  greater  wing  of  the  sphenoid,  and  then  divides 
into  two  l)ranches.  an  anterior  and  a  posterior. 

The  anterior  branch  i)asses  upwards,  in  the  groove  on  the  greater  wing  of  the 
sphenoid,  on  to  the  parietal  bone  at  its  anterior  and  inferior  angle;  at  this  spot  the 
groove  becomes  deepened  and  often  bridged  over  by  a  thin  plate  of  bone,  being 
converted  for  a  quarter  to  half  an  inch  or  more  into  a  distinct  canal.  The  situation 
of  the  artery  is  here  indicated  on  the  exterior  of  the  skull  by  a  spot  an  inch  and  a 
half  l:)ehind,  and  al)out  an  inch  above,  the  external  angular  process  of  the  orbit. 
The  anterior  liranch  is  continued  along  the  anterior  border  of  the  parietal  bone 
nearl}^  as  far  as  the  superior  longitudinal  sinus,  and  gives  off  in  its  course,  1)ut 
especially  posteriorly,  large  l)ranches  which  raniif}^  in  an  upward  and  backward 
direction  in  grooves  on  the  parietal  l)one  (fig.  337). 

The  posterior  branch  passes  backwards  over  the  squamous  portion  of  the 
temporal  bone;  and  thence  on  to  the  parietal  bone,  behind  the  anterior  branch. 

Fig.  337. — The  Middle  Meningeal  Artery  within  the  Skill. 

BREGMA 


This  l)ranch  and  its  collaterals  extend  upwards  as  far  as  the  longitudinal  sinus,  and 
l)ackwards  as  far  as  the  lateral  sinus. 

In  addition  to  its  terminal  anterior,  and  terminal  posterior  In'anches,  the  middle 
meningeal  gives  off: — (a)  Gasserian  branches  to  the  Gasserian  ganglion  and 
Meckel's  space,  (b)  A  petrosal  branch,  which  enters  the  hiatus  Fallo}ui  in  com- 
l)anv  with  the  large  superficial  i)etrosal  ncn-ve  and  anastomoses  with  the  terminal 
]»ranch  of  the  stylo-mastoid  artery,  (c)  A  tympanic  branch,  Avhich  enters  the 
canal  for  the  tensor  tympani,  and  supplies  that  muscle,  {d)  An  orbital  or 
lachrymal  branch,  ^vhicll  enters  the  orbit  at  the  outermost  part  of  the  sphenoidal 
fissure,  or  sometimes  through  a  minute  foramen,  just  external  to  that  fissure,  and 
anastomoses  with  the  lachrymal  branch  of  the  ophthalmic.  {<')  Anastomotic  or 
perforating  branches  which  pierce  the  greater  wing  of  the  s])henoid  bone,  and 
anastomose  with  the  deep  temjioral  arteries. 

(4)  The  mandibular  (inferior  dental)  artery  (fig.  330).  arising  from  the 
internal  maxillary  as  it  lies  brtweeii  the  sjilieno-mandibular  ligament  and  neck  of 
the  jaw,  courses  downwards  to  the  mandibular  foramen,  which  it  enters  in  company 


INTERNAL   MAXILLARY  495 

with,  and  a  little  In-liind  and  external  to,  the  niandihular  nerve  It  tlien  passes 
along  the  canal  in  the  interior  of  the  hone,  giving  oil:"  l)ranelies  to  the  molar,  l)ieus])id, 
and  canine  teeth.  On  reaching  the  mental  foramen  it  divides  into  two  hranclies, 
the  incisive  and  the  mental.  Tlie  incisive  continues  its  course  in  the  l)one,  and 
sui)plies  l)ranclies  to  the  incisor  teeth,  and  anastomoses  Avith  the  artery  of  the 
opposite  side.  The  mental  i)asses  through  the  mental  foramen  in  comi)any  with 
the  mental  hranch  of  the  mandibular  (inferior  dental)  nerve,  and  emerges  on  the 
chin  under  cover  of  the  depressor  labii  inferioris.  It  anastomoses  above  with 
tlie  inferior  coronary,  and  below  with  the  submental,  and  also  with  the  inferior 
labial.  Near  its  origin  the  artery  gives  off  (a)  a  lingual  or  gustatory  branch, 
whicli  accompanies  and  supjdies  the  lingual  nerve,  and  ends  in  the  mucous 
membrane  of  the  mouth;  and,  just  before  it  enters  the  dental  foramen  in  the  lower 
jaw,  (//)  a  mylo-hyoidean  branch,  Avhich  accomi^anies  the  nerve  of  that  name 
along  the  groove  in  tlie  lower  jaw,  and,  after  supplying  the  mylo-hyoid  muscle, 
anastomoses  with  the  sublingual  and  submental  arteries. 

(5)  The  small  meningeal  arises  either  from  the  internal  maxillary  a  little  in 
front  of  the  large  middle  meningeal,  or  as  a  branch  of  that  vessel.  It  passes 
upwards  along  the  course  of  the  mandibular  division  of  the  fifth  nerve,  and,  enter- 
ing the  skull  through  the  foramen  ovale,  is  distributed  to  the  Gasserian  ganglion, 
and  to  the  walls  of  the  cavernous  sinus  and  the  dura  mater  in  the  neighbourhood. 

Branches  oft/ie  tSecond  Part  of  the  Internal  Maxillary  Artery. — The  branches  of  the 
second  portion  of  the  internal  maxillary  all  supply  muscles.  They  are: — (1)  The 
masseteric;  (2)  the  posterior  deep  temi)oral;  (3)  the  internal  pterygoid  ;  (4)  the 
external  pterygoid;   (5)  the  buccal;  and  (6)  the  anterior  deep  temporal. 

(1)  The  masseteric  branch  comes  oft"  from  the  internal  maxillary  as  the  latter 
is  passing  from  Ijetween  the  neck  of  the  jaw  and  the  spheno-mandilralar  ligament. 
It  is  directed  outwards  along  with  the  masseteric  nerve,  and,  passing  through  the 
sigmoid  notch  in  the  lower  jaw,  supplies  the  masseter  muscle.  Some  filaments 
perforate  the  muscle  and  anastomose  Avith  the  transverse  facial  and  Avith  the  mas- 
seteric branches  of  the  facial  itself. 

(2)  The  posterior  deep  temporal  arises,  as  a  rule,  from  the  internal  maxillary 
in  common  Avith  the  masseteric  or  a  little  beyond  that  branch.  It  passes  u})wards 
])eneath  the  temporal  muscle  in  a  slight  groove  on  the  anterior  margin  of  the 
squamous  portion  of  the  temporal  bone,  supplying  the  temporal  muscle,  the  peri- 
cranium, and  the  external  layer  of  the  bone.  It  anastomoses  Avith  the  anterior 
deep  temporal  and  the  other  temporal  arteries. 

(3)  The  internal  pterygoid  branches  are  short  trunks  Avhich  pass  into  and 
supply  the  internal  ])terygoid  muscle. 

(4)  The  external  pterygoid  branches  supply  the  external  pterygoid  muscle, 
and,  like  the  internal  pterygoid  Ijranches,  are  short  trunks,  and  very  irregular  in 
their  number,  origin,  and  distribution. 

(5)  The  buccal  branch  (fig.  330)  courses  forAvards  and  doAvinvards  Avith  the 
buccal  nerve  to  the  Iniccinator  muscle,  lying  in  close  contact  with  the  inner  side 
and  anterior  margin  of  the  tendon  of  the  temporal  muscle  and  coronoid  i)rocess  of 
the  loAver  jaAV.  It  supplies  the  ])Uccinator  muscle  and  mucous  membrane  of  the 
mouth,  and  anastomoses  Avith  the  facial,  transverse  facial,  and  infraorbital  arteries. 

(6)  The  anterior  deep  temporal  branch  ascends  Ixnieath  the  temporal  mu-scle 
in  a  slight  groove  on  the  greater  Aving  of  the  sphenoid  l)one.  It  sup])lies  the 
nuiscle,  pericranium,  and  subjacent  l)one,  and  gives  off  small  branches  Avhich  pass 
through  minute  foramina  in  the  malar  bone.  Some  of  these  last  l^ranches  enter 
the  orl)it  and  anastomose  Avith  the  lachrymal  artery;  others  emerge  on  the  face  and 
anastomose  Avith  tlie  transverse  facial  artery. 

Branches  of  the  Third  I^art  of  the  Litermd  Maxillary  Artery. — The  branches  of  the 
third  part  of  the  internal  maxillary  artery,  like  those  of  the  first  ])art,  all  ]»ass  through 
bony  canals.  They  are  the  folloAving: — (1)  The  jjosterior  dental,  or  alveolar  ;  (2) 
the  infraorbital;  (3)  the  posterior,  or  descending  palatine;  (4)  the  Vidian;  (5)  the 
ptery go-palatine;  and  (6)  the  naso-palatine,  or  spheno-]>alatine. 

(1 )  The  posterior  dental  or  alveolar  branch  arises  from  the  internal  maxillary 
as  the  latter  is  passing  into  the  splicno-niaxillary  fossa,  and  descends  in  a  tortuous 
manner  in  a  groove  on  the  back  of  the  l)odv  of  the  maxilla.      It  gives  oft"  the  fol- 


496  THE  ARTERIES 

lowintj  l»ranches: — ((OAntral,  which  }iass  through  small  foramina  into  the  antrum; 
(//)  dental,  whic-li  ])a<s  into  hony  canals  to  sui)])ly  the  molar  and  l)icusi)id  teeth; 
{c)  alveolar,  uv  gingival,  which  supi)ly  the  gums;  and  ((/)  buccal,  which  are  tlis- 
tributecl  to  the  buccinator  muscle. 

(2)  The  infraorbital  branch  arises  from  the  internal  maxillary,  generally  as  a 
common  trunk  with  the  posterior  dental.  It  passes  forwards  and  a  little  upwards 
through  the  spheno-maxillary  fossa;  then  forwards  in  company  Avith  the  maxillary 
division  of  the  fifth  nerve,  first  along  the  groove,  and  then  through  the  canal  in  the 
orbital  plate  of  the  maxilla;  and  finally,  emerging  on  the  face  at  the  infraorl)ital 
foramen,  under  cover  of  the  levator  labii  superioris  proprius,  is  distriljuted  to  the 
structures  forming  the  upper  lip,  the  lower  eyelid,  the  lachrymal  sac,  and  the  side 
of  the  nose.  It  anastomoses  with  the  superior  coronary  and  angular  l^ranches  of 
the  facial,  Avith  the  nasal  and  lachrymal  branches  of  the  ophthalmic,  and  with  the 
transverse  facial.  It  gives  off  the  following  small  branches: — (a)  Orbital,  to  the 
fat  of  the  orbit  and  to  the  inferior  rectus  and  inferior  obliciue  muscles;  (6)  an 
anterior  dental  branch,  which  passes  downwards  through  a  groove  in  the  anterior 
Avail  of  the  superior  maxilla,  together  Avith  the  anterior  dental  branch  of  the  infra- 
orbital nerve,  and, supplies  branches  to  the  incisor  and  canine  teeth  and  the  mucous 
membrane  of  the  antrum;  and  (c)  nasal  branches,  Avhich  pass  through  the 
foramina  in  the  nasal  process  of  the  superior  maxilla  (sutura  notha). 

(3)  The  posterior  or  descending  palatine  branch  descends  in  the  posterior 
palatine  canal  Avith  the  great  or  anterior  palatine  branch  of  Meckel's  ganglion.  On 
emerging  on  the  palate  at  the  posterior  palatine  foramen,  it  divides  into  the  folloAV- 
ing  branches: — (a)  An  anterior  branch,  Avhich  courses  forwards  in  the  muco- 
periosteum  at  the  junction  of  the  hard  palate  Avith  the  alveolar  process  as  far  as  the 
anterior  palatine  foramen,  Avhere  it  anastomoses  Avith  the  naso-palatine  artery;  and 
(l) )  posterior  branches,  Avhich  pass  backAvards  and  doAvnAvards  into  the  soft  palate, 
contriljuting  to  the  supply  of  that  structure,  and  anastomosing  Avith  the  ascending 
palatine  artery.  After  the  operation  for  cleft  palate,  serious  hnemorrhage  occasion- 
ally occurs  from  the  descending  palatine  artery.  It  may  be  stopped  by  compressing 
the  artery  by  means  of  a  plug  inserted  in  the  posterior  palatine  foramen.  The 
foramen  is  situated  a  little  behind,  and  internal  to,  the  last  molar  tooth,  and  almost 
inmiediately  in  front  of  the  hamular  process. 

(4)  The  Vidian  artery  is  a  long  slender  branch  Avhich  passes  backAvards 
through  the  Vidian  canal  in  company  Avith  the  Vidian  nerve  into  the  cartilage  of 
tlie  middle  lacerated  foramen.  It  gives  off  the  folloAving  branches: — (a)  Pharyn- 
geal, which  contributes  to  the  supply  of  the  roof  of  the  pharynx,  and  anastomoses 
Avith  the  ascending  pharyngeal  and  pterygo-palatine  arteries;  (/>)  Eustachian, 
Avhich  is  distributed  to  the  Eustachian  tube;  and  (c)  tympanic,  Avhicli  enters  tlu- 
tyniipanum,  and  anastomoses  Avith  the  other  tympanic  arteries. 

(5)  The  pterygo-palatine  artery,  or  pterygo-pharyngeal  as  it  is  sometimes 
called,  a  still  more  slender  branch  than  the  Vidian,  passes  backAvards  througli  the 
pterygo-palatine  foramen  Avith  the  pharA'ngeal  nerve,  a  branch  of  Meckel's  ganglion. 
It  divides  into  three  branches: — (o)  Pharyngeal,  to  the  roof  of  the  pharynx;  (6) 
Eustachian,  to  the  Eustachian  tube;  and  (c)  sphenoidal,  to  the  sphenoidal  cells. 
The  ]iterygo-palatine  sometimes  arises  from  the  spheno-palatine. 

(6)  The  spheno-palatine  or  naso-palatine  artery,  the  terminal  branch  of  the 
internal  maxillary,  ])asses  Avith  the  spheuo-i)alatine  l)ranch  of  Meckel's  ganglion 
from  the  spheno-maxillary  fossa  into  the  nose  through  the  spheno-palatine  foramen. 
Crossing  the  roof  of  the  nose  in  the  nuico-periosteum,  it  passes  on  to  the  septum, 
and  then  runs  forwards  and  downwards  in  a  groove  on  the  vomer  (under  the  name 
of  the  naso-palatine,  or  artery  of  the  septum)  toAvards  the  anterior  palatine 
foramen,  Avhere  it  anastomoses  Avith  the  anterior  palatine  artery,  Avhich  enters  the 
nose  through  the  lateral  compartment  of  that  foramen  (the  canal  of  !-^tenson).  In 
this  course  it  gives  off  the  folloAving  branches: — (a)  A  pharyngeal  branch  (or 
descending  pharyngeal  branch,  as  it  is  sometimes  called),  which  is  distributed 
to  the  roof  and  contiguous  ]iortions  of  the  phar^'ux.  (h)  A  sphenoidal  branch, 
which  sup})lies  the  sjthenoidal  cells,  (r )  Nasal  branches,  Avliich  ramify  over  the 
turl)inal  l»ones  and  lateral  Avails  of  the  nose,  and  give  twigs  to  the  ethmoidal  and 
frontal  sinuses  and    lining   membrane  of   the  antrum.       (//)   Ascending  septal 


INTERNAL  CAROTID 


497 


branches,  which  run  upwards  and  forwards,  <rivin^  small  twigs  to  the  mucous 
mcmlirane  covering  the  upi^er  part  of  the  sejttum,  and  which  pass  through  the 
criliriform  plate  of  the  etlnnoid,  and  anastomose  with  the  ethmoidal  arteries 
(perforating  or  meningeal  branches). 


THE  INTERNAL  CAROTID  ARTERY 

The  internal  carotid  (fig.  338)  arises  with  the  external  carotid  at  the  bifurca- 
tion of  the  common  rarotid,  opposite  the  upper  border  of  the  thyroi<l  cartilage,  on  a 
level  with  the  fourth  cervical  vertebra.     It  is  at  first  placed  a  little  external  to  the 


Fici.  338.  — The  Ixterxal  Carotid  Artery,  axp  Deep  Braxches  of  the  Extekxal 

Carotid  Arterv,  Left  Side. 

(From  a  dissection  in  the  Hunterian  Museum.) 

External  carotid  artei-tj,  cut 
Temporal  artery 


Internal  maxillary  artery 
Transverse  facial  artery 
STENSON'S  DUCT,  TURNED  FORWARDS 


Superior  oblique 

Splenius  capitis,  cut 

T/iinl  part  of  occipital  artery 
I 


Superior  constrictor 

AacfniUng  palatine  ar. 

Ascemlinfj  pharyngeal 

arler\i 

External  carotid 

artfirt/,  cut  short 

Stylo-pharyilgeus 


Digastrieus 
f'oslerior  auricular 
First  part  of      [ar. 

occipital  artery 
Princeps  cervicis  ar. 
Occipital  part  of 
vertebral  artiry 
Inferior  oblique, 

cut 
Complexus,  cut 


SemispinaliB  colli 


Complexus.  cut 

Ascending  cervical 
artery 


Vertebral  artery 


N—  Deep  cervical 
>.         artery 


Sterno-mastoid,  cut 


SUBMAXILLARY  GLAND 
Superior  thyroid  artery 

Rectus  capitis  amicus  major 


external  carotid,  l:)ut  as  it  ascends  in  the  neck  the  external  carotid  becomes  more 
superficial  and  in  front  of  the  internal.  The  internal  carotid  passes  up  the  neck, 
in  front  of  the  transverse  processes  of  the  upper  cervical  vertebrie  lying  upon 
the  rectus  capitis  anticus  major  to  the  carotid  foramen,  thence  through  the  carotid 
canal  in  the  petrous  portion  of  the  temporal  bone,  making  at  fir.^t  a  turn  forwards 
and  inwards  and  then  a  second  turn  upwards,  and  enters  the  cranium  through 
the  foramen  lacerum  medium.  It  then  makes  a  sigmoid  curve  on  the  side  of  the 
bodv  of  the  sjtlienoid  bone,  and  terminates,  after  jierforating  the  dura  mater,  by 
32 


498  THE  ARTERIES 

dividing  oi)posite  the  anterior  clinoid  processes  in  the  fissure  of  Sylvius,  into  the 
anterior  and  middle  cerebral  arteries. 

In  its  course  up  the  neck  it  often  forms  one  or  more  curves,  especially  in  old 
people.  Between  the  internal  and  the  external  carotids,  at  their  angle  of  diverg- 
ence, is  situated  the  intercarotid  body,  or  ganglion  intercarotioum. 

The  internal  carotid  is  the  continuation  ui)wards  of  the  ])rimitive  dorsal  aorta, 
and  supplies  the  greater  part  of  the  brain,  the  contents  of  tlie  orl^it,  and  parts  of 
the  internal  ear,  forehead,  and  nose.  It  is  divided  into  three  portions: — 1.  a 
cervical;  2.  an  intraosseous,  or  petrosal;  and  3.  an  intracranial. 

1.  The  Cervical  Portion 

Relations. — In  the  neck  the  artery  is  at  first  comparative!}'  superficial,  having 
in  front  of  it,  as  it  lies  in  the  superior  carotid  triangle,  the  skin,  superficial  fascia, 
platysma  and  deep  fascia,  and  the  overlapping  edge  of  the  sterno-mastoid  muscle. 
Higher  up,  as  it  sinks  beneath  the  parotid  gland  (fig.  829),  it  becomes  deeply 
placed,  and  is  crossed  by  the  posterior  belly  of  the  digastric  and  stylo-hyoid 
muscles,  the  hypoglossal  nerve,  and  the  occipital  and  posterior  auricular  arteries; 
whilst  still  higher  it  is  separated  from  the  external  carotid  artery,  which  here  gets 
in  front  of  it,  by  the  stylo-glossus  and  stylo-pharyngeus  muscles,  the  glosso- 
pharvngeal  nerve,  the  pharyngeal  branch  of  the  pneumogastric  nerve,  and  by  the 
stylo-hyoid  ligament. 

Behind,  it  lies  upon  the  rectus  capitis  anticus  major,  which  separates  it  from  the 
transverse  processes  of  the  three  upper  cervical  vertebrae,  on  the  superior  cervical 
ganglion  of  the  sympathetic  nerve,  and  on  the  pneumogastric  nerve.  Xear  the 
base  of  the  skull,  the  hypoglossal,  pneumogastric,  glosso-pharyngeal,  and  spinal 
accessory  nerves  cross  obliquely  behind  it,  separating  it  at  this  spot  from  the 
internal  jugular  vein,  which,  as  the  artery  is  about  to  enter  the  carotid  canal,  also 
forms  one  of  its  posterior  relations. 

On  its  outer  side  are  the  internal  jugular  vein  and  pneumogastric  nerve. 

On  its  inner  side  it  is  in  relation  with  the  pharynx,  the  superior  constrictor 
muscle  separating  it  from  the  tonsil.  The  ascending  pharyngeal  and  ascending 
palatine  arteries,  and  at  the  base  of  the  skull  the  Eustachian  tube  and  levator 
palati  muscle  are  also  internal  to  it. 

2.  The  Intraosseous  or  Petrosal  Portion 

The  intraosseous  portion  (fig.  331)  is  situated  in  the  carotid  canal  in  the 
petrous  portion  of  the  temporal  bone.  It  is  here  separated  from  the  walls  of  the 
canal  V>y  a  prolongation  downwards  of  the  dura  mater.  In  this  part  of  its  course 
it  first  ascends  in  front  of  the  tympanum  and  cochlea  of  the  internal  ear;  it  then 
turns  forwards  and  inwards,  lying  a  little  internal  to  and  behind  the  Eustachian 
tube,  and  enters  the  cranial  cavity  by  turning  upwards  through  the  foramen 
lacerum  medium,  lying  upon  the  lingula  of  the  si)henoid  l)one.  In  this  part  of  its 
course  it  is  accompanied  by  the  ascending  liranches  from  the  superior  cervical 
ganglion  of  the  sympathetic.  These  form  a  ])lexus  about  the  artery,  liut  are  situated 
chiefly  on  its  outer  side.  It  is  also  surrounded  by  a  number  of  small  veins,  Avhich 
receive  tributaries  from  the  tympanum,  and  open  into  the  cavernous  sinus  and 
internal  jugular  vein. 

3.  The  Intracranial  Portion 

On  entering  the  cranium  through  the  foramen  lacerum  medium,  the  internal 
carotid  first  ascends  towards  the  ])Osterior  clinoid  process,  but  soon  changing  its 
direction,  it  curves  forwards  and  slightly  doAvnwards  by  the  side  of  the  l)ody  of  the 
sphenoid  bone  on  the  inner  wall  of  the  cavernous  sinus.  Here  it  has  the  sixth  nerve 
innuediately  external  to  it,  and  is  covered  by  the  lining  membrane  of  the  sinus. 
Again  turning  upwards,  it  pierces  the  dura  mater  on  the  inner  side  of  the  anterior 
clinoid  process,  and,  passing  l^etween  the  second  and  third  nerves  to  the  anterior 
perforated  spot  at  the  inner  end  of  the  Sylvian  fissure,  divides  into  its  two  terminal 
branches,  the  anterior  and  middle  cerebral.     After  it  has  perforated  the  dura  mater, 


BRA.XCHES  OF  OPHTHALMIC  499 

it  is  described  by  some  aiuituiuists  as  a  fourth  portion — the  intracereln'al  (fig.  387). 
As  it  Ucs  in  the  foramen  lacerum  mediinn  the  artery  is  erossed  on  its  outer  side  by 
the  great  superficial  j)etrosal  nerve  as  the  latter  goes  to  join  the  great  deep  petrosal 
from  the  carotid  plexus  to  form  the  Mdian  nerve. 

Branches  of  the  Internal  Carotid  Artery 

The  cervical  portion  gives  off  no  branch.  The  intraosseous  portion  gives 
off: — (1)  Tympanic;  (2)  Vidian.  The  intracranial  portion  gives  off: — (1) 
Arteria  receptaculi;  (2)  pituitary;  (3)  Gasserian;  (4j  meningeal;  (5)  ophthalmic; 
(6)  posterior  communicating;  (7)  anterior  choroid;  (8)  anterior  cerebral;  (9) 
middle  cerebral. 

Branches  of  the  Intraosseous  Portion. — (1)  The  tympanic  enters  the  tympanum 
through  a  small  foramen  in  the  posterior  "wall  of  the  carotid  canal,  and  contributes 
its  quota  to  the  Ijloocl-supply  of  that  cavity.  It  anastomoses  Avith  the  tympanic 
branches  of  the  stylo-mastoid  and  internal  maxillary  arteries.  (2)  A  Vidian 
branch  is  also  descriljed,  and  is  said  to  anastomose  Avith  the  Vidian  artery. 

Branches  of  the  Intracranial  Portion. — As  the  internal  carotid  artery  lies  on  tlie 
inner  side  of  the  cavernous  sinus,  it  gives  off  the  following  branches  : — (1)  Arteria 
receptaculi,  small  branches  to  the  walls  of  tlie  cavernous  sinus;  (2)  pituitary 
branches  to  the  pituitary  body;  (3)  Gasserian  or  ganglionic  branches  to  the 
Gasserian  ganglion;  (4)  meningeal  or  anterior  meningeal  branches  to  the  dura 
mater;  these  anastomose  with  anterior  liranches  of  the  middle  meningeal. 


(o)  THE  OPHTHALMIC  ARTERY 

The  ophthalmic  artery  (fig.  339)  comes  off  from  the  internal  carotid  imme- 
diately bel(JW  the  anterior  clinoid  ])rocess  just  as  the  latter  vessel  is  passing  through 
the  dura  mater.  Entering  the  orljit  through  the  optic  foramen  l^elow  and  external 
to  the  optic  nerve,  it  at  once  perforates  the  sheath  of  dura  mater  which  is  prolonged 
through  the  optic  foramen  on  both  artery  and  nen'e.  It  then  runs  in  a  gentle  curve 
with  its  convexity  outwards  below  the  optic  nerve  and  external  rectus,  being  here 
crossed  by  the  nasal  nen'e,  and  turning  forwards,  inwards,  and  upAvards,  passes 
over  the  optic  nerve,  round  which  it  thus  forms  a  loop  (fig,  339)  to  the  inner  side 
of  the  orbit.  Thence  it  runs  obliquely  beneath  the  superior  rectus  in  front  of  the 
nasal  nerve  under  the  lower  border  of  the  superior  oVilique,  but  above  the  internal 
rectus,  and  continues  its  course  under  the  pulley  for  the  superior  oblique  and 
reflected  tendon  of  that  muscle  to  the  internal  angular  process  of  the  orbit,  where 
it  divides  into  the  frontal  and  nasal  branches. 


Branches  of  the  Ophthalmic  Artery 

The  branches  of  the  ophthalmic  artery  are: — (a)  the  lachrymal;  (h)  the 
supra-orl)ital;  {c)  the  central  artery  of  the  retina;  (d)  the  muscular;  (f)  the  ciliary; 
(/)  the  posterior  ethmoidal;  ((/)  the  anterior  ethmoidal;  (A)  the  palpebral;  (?) 
the  frontal;  and  (/.)  the  nasal. 

(a)  The  Lachrymal  Artery 

Tiie  lachrymal  artery  is  usually  the  first  and  at  times  the  largest  l)ranch  of  the 
0])lithalmic.  It  arises  l)etween  the  superior  and  external  rectus  on  the  outer  side 
of  the  optic  nerve  from  the  ophthalmic  soon  after  that  vessel  has  entered  the  orbit. 
At  times  it  is  given  off  from  the  ophthalmic  outside  the  orbit,  and  then  usually 
passes  into  that  cavity  through  the  si)lienr)idal  fissure.  It  runs  forwards  along  the 
outer  wall  of  the  orbit  with  the  lachrymal  nerve  above  the  upper  border  of  the 
external  rectus  to  the  lachrymal  gland,  which  it  supplies.  In  tliis  course  it  fur- 
nishes the  following  branches: — (i)  Recurrent  lachrymal,  one  or  more  branches 
Avhich  pass  backwards  through  tiie  splienoidal  fissure,  and  anastomoses  with  the 
lachrymal  branch  of  tlie  large  middle  meningeal  artery.     The  anastomosis  is  some- 


500 


THE  ARTERIES 


times  of  lavfre  sizo,  and  takes  the  chief  share  in  the  formation  of  the  lachrymal 
artery,  (ii )  Muscular  branches,  distributed  chiell}'  to  the  external  rectus,  (iii) 
Malar  branches — small  twiiis,  which  ])ass  through  the  malar  canals,  and  anasto- 
mose with  the  orltital  Itranch  (tf  the  middle  tem})oral,  and  with  the  transverse  facial 
on  the  cheek,  (iv;  Palpebral  branches,  whidi  arc  distributed  to  the  U])per  and 
lower  eyelids  and  to  the  conjmutiva.  {v)  Ciliary.  See  Ciliary  Akteeies, 
page  501. 

(h)  The  Supraorbital  Artery 

The  supraorbital  artery  usually  arises  from  the  ophthalmic  as  the  latter  vessel 
is  about  to  cross  over  the  optic  nerve.  Passing  upwards  to  the  inner  side  of  the 
superior  rectus  and  levator  palpebra?,  it  runs  along  the  upper  surface  of  the  latter 
muscle  with  the  frontal  nerve  in  the  orbital  fat,  but  beneath  the  periosteum  to  the 
supraorbital  notch.     On  emerging  on  the  forehead  beneath  the  orlncularis  palpe- 


FiG.  339.— The  Left  Ophthalmic  Aeteey  and  Vein. 


Supraorbital  artery 

LACHRVMAL  GLAND 

Superior  rectus,  cut 

EYEBALL 


External  rectus 

Lachrymal  artu  y 

Superior  rectus,  cut 

Inferior  ophthalmic  it.  in 
Superior  ophthalmic  ^ein 


OPTIC  NER  VE  - 
Common  ophthalmic  vei 


'"''"''SS       Commencement  of  sii/ie/iiir 
ojihthalinic  icin 

Reflected  tendon  of  superior 
oblique 

S —  ophthalmic  artery 


Anterior  ethmoidal  artery 

Posterior  ethmoidal  artery 
Ciliary  arteries 

Levator  palpebrae,  cut 
Ligament  of  Zinn 

Ojdithalmic  artery 

OPTIC  COMMISSURE 


Internal  carotid  artery 


])rarmii,  it  divides  into  a  superficial  and  deep  branch;  the  former  ramifies  between 
the  skin  and  occipito-frontalis,  the  latter  between  the  occii>ito-frontalis  and  the 
pericranium.  Both  l)ranches  anastomose  with  the  anterior  l)ranches  of  the  superficial 
temporal,  the  angular  branch  of  the  facial,  and  the  transverse  facial  artery.  The 
branches  of  the  supraorbital  are: — (i)  Periosteal,  to  the  periosteum  of  the  roof  of 
theorV)it;  (ii)  muscular,  to  the  levator  palpebnc  and  superior  rectus;  (iii)  diploic, 
given  off  as  the  artery  is  passing  through  the  supraorbital  notch  and  entering  a 
minute  foramen  at  the  bottom  of  the  notch  is  distributed  to  the  diploe  and  frontal 
sinuses;  (iv)  trochlear,  to  the  pulley  of  the  sui)eri(>r  olilique;  (v)  palpebral,  to 
the  upper  eyelid. 

(c)  The  Central  Artery  of  the  Retina 

The  arteria  centralis  retinae,  a  small  but  constant  branch,  comes  oflf  from 
the  ophthalmic  close  to  the  optic  foramen,  and,  perforating  the  optic  nei've  about  a 
(piarter  of  an  inch  behind  the  globe,  runs  forwards  in  the  substance  of  the  nerve  to 
the  eyeball,  supplying  the  retina.  The  fact  that  this  artery  penetrates  the  substance 
of  the  optic  nerve  is  of  developmental  interest,  as  it  indicates  the  spot  where  the 


BRANCHES  OF  OPHTHALMIC  501 

meseiichynia  invaginated  the  i)riinaiT  optic  vesicle  on  its  ventral  aspect  to  form  the 
vitreous.      Its  further  description  is  given  in  the  Anatomy  of  thk  Eye. 

{(1)  The  Muscular  Branxhes 

The  muscular  branches  are  very  variable  in  their  origin  and  distril)ution. 
Tiiey  may  l)e  roughly  divided  into  superior  and  inferior  sets.  Tlie  superior  or 
smaller  set  sui)})ly  the  superior  oblique,  the  levator  palpel>ni?,  and  superior  rectus. 
The  interior  ])ass  forward  between  the  optic  nerve  and  the  inferior  rectus,  supply- 
ing that  nmscle,  the  internal  rectus,  and  the  inferior  oblique.  From  the  muscular 
branches  are  given  ofi'  the  anterior  ciliary  arteries.     (See  Ciliary  Arteries.) 

(e)  The  Ciliary  Arteries 

The  ciliary  arteries  are  divided  into  three  sets: — The  short  posterior,  the 
long  posterior,  and  the  anterior,  (i)  The  short  posterior,  five  to  six  in  number, 
come  off  ehietiy  from  the  ophtlialmic  as  it  is  crossing  the  optic  nerve.  They  run 
forwards  al)out  the  nerve,  dividing  into  twelve  or  fifteen  small  vessels,  which  per- 
forate the  sclerotic  around  the  entrance  of  the  optic  nerve,  and  are  distributed  to  the 
choroid  coat,  (ii)  The  long  posterior  ciliary  arteries,  usually  two  in  number, 
come  off  from  the  ophthalmic  on  either  side  of  the  optic  nerve,  and  run  forwards 
with  the  short  ciliary,  to  the  sclerotic.  On  piercing  the  sclerotic,  they  course  for- 
wards, one  on  either  side  in  the  equatorial  line,  between  that  coat  and  the  choroid 
to  the  ciliary  processes  and  iris.  Their  further  distril)ution  is  given  under  the 
Anatomy  of  the  Eye.  (iii)  The  anterior  ciliary  are  derived  from  the  muscular 
branches  and  from  the  lachrymal.  They  run  to  the  globe  along  the  tendons  of  the 
recti,  forming  a  zone  of  radiating  vessels  beneath  the  conjunctiva.  They  perforate 
the  sclerotic  about  a  quarter  of  an  inch  (6  mm. )  behind  the  cornea,  and  supply 
the  iris  and  ciliary  processes.  It  is  these  vessels  that  are  enlarged  and  congested  in 
iritis,  forming  the  circumcorneal  zone  of  redness  so  characteristic  of  that  disease. 
Tliev  thtni  (lifter  from  the  tortuous  vessels  of  the  conjunctiva  in  that  they  are 
straight  and  }iarallel. 

(/)  The  Posterior  Ethmoidal  Artery 

Ine  posterior  ethmoidal  runs  inwards  between  the  su])erior  oUique  and 
internal  rectus,  and,  leaving  the  orbit  by  the  posterior  ethmoidal  canal,  together 
with  the  s]>heno-ethmoidal  branch  of  the  nasal  nerve,  enters  the  })Osterior  ethmoidal 
cells,  whence  it  passes  through  a  transverse  slit-like  aperture  Ix'tween  the  s}»]ienoid 
bone  and  cribriform  plate  of  the  ethmoid  bone  into  the  cranium.  It  gives  oft"  <  i ) 
ethmoidal  branches  to  the  posterior  ethmoidal  cells;  (ii)  meningeal  branches 
to  the  dura  mater  lining  the  crilniform  plate;  and  (iii)  nasal  branches,  which 
l)ass  through  the  cribriform  plate  to  the  superior  meatus  and  ui>i»er  si)ongy  ])ones 
of  the  nose,  and  anastomose  Avith  the  nasal  branches  of  the  si)heno-palatine  artery. 

(//)  The  Anterior  Ethmoidal  Artery 

The  anterior  ethmoidal  (figs.  339,  387),  a  larger  branch  than  the  posterior 
ethmoidal,  arises  in  front  of  the  latter,  ])asses  inwards  lietwcen  the  su])erior  o])lique 
and  internal  rectus,  and,  leaving  the  orl)it  through  the  anterit)r  ethmoidal  canal,  in 
company  with  the  nasal  nerve,  enters  the  cranial  cavity.  After  running  a  short 
distance  l^eneath  the  dura  mater  on  the  cribriform  jilate  of  the  ethmoid  bone,  it 
passes  into  the  nose  through  the  horizontal  slit-like  aperture  by  the  side  of  the 
crista  galli.  Its  terminal  branch  ]>asses  along  the  groove  on  the  under  surface  of 
the  nasal  l)one,  and  emerges  on  the  nose  between  the  bone  and  lateral  cartilage, 
terminating  in  the  skin  of  that  organ.  It  gives  off  the  following  branches  in  its 
course: — (i)  Ethmoidal,  to  the  anterior  ethmoidal  cells;  (ii)  meningeal,  to  the 
dura  mater  of  the  anterior  fossa;  (iii)  nasal,  to  the  middle  meatus  and  anterior 
part  of  the  nose;  (iv)  frontal,  to  the  frontal  sinuses;  (v;  cutaneous,  or  terminal, 
to  the  skin  of  the  nose. 


502  THE  ARTERIES 

(h)  The  Palpebral  Branches 

The  palpebral  branches  arise  either  separately  or  by  a  common  trunk  from 
the  ophthahnir  artery  djiposite  the  pulley  fur  the  superior  oblicjue,  just  as  the  latter 
vessel  is  about  to  divide  into  its  terminal  l)ranches.  They  pass,  one  above  and 
one  below  the  internal  tarsal  ligament  or  tendo  oculi,  and  then  skirt  along  the 
upper  and  lower  eyelids  respectively,  near  the  free  margin  between  the  tarsal 
cartilages  and  the  orbicularis  muscle,  and  form  a  superior  and  inferior  palpebral 
arch  by  anastomosing  with  the  palpebral  branches  of  the  lachrymal.  The  up})er 
also  anastomoses  with  the  supraorbital  artery  and  orbital  branch  of  the  temporal 
artery;  the  lower  Avith  the  infraorbital,  the  angular  branch  of  the  facial,  and  the 
transverse  facial  arteries.  A  branch  from  the  lower  palpebral  passes  with  the  nasal 
duct  as  far  as  the  inferior  meatus.  Small  twigs  are  also  given  to  the  caruncle  and 
conjunctiva. 

(i)  The  Frontal  Branch 

The  frontal  branch,  the  upper  of  the  terminal  branches  of  the  ophthalmic, 
pierces  the  tarsal  membrane  at  the  inner  angle  of  the  orbit,  passes  upAvards  over 
the  frontal  bone,  beneath  the  orbicularis  palpebrarum  and  corrugator  supercilii, 
supplies  the  structures  in  its  neighbourhood,  and  anastomoses  with  its  fellow  of 
the  opposite  side,  with  the  supraorbital,  and  Avith  the  anterior  division  of  the  super- 
ficial temporal  artery. 

(k)  The  Xasal  Branch 

The  nasal,  the  loAver  of  the  terminal  branches  of  the  ophthalmic,  leaves  the 
orbit  at  the  inner  canthus  by  perforating  the  tarsal  meml)rane  above  the  tendo 
oculi.  It  then  descends  along  the  dorsum  of  the  nose,  beneath  the  integuments; 
and  anastomoses  Avith  the  angular  and  lateral  nasal  branches  of  the  facial.  It  gives 
off  a  lachrymal  branch  as  it  crosses  the  lachrymal  sac,  and  a  transverse  nasal 
branch  as  it  crosses  the  root  of  the  nose;  the  latter  vessel  anastomoses  Avith  its 
felloAv  of  the  opposite  side. 


(6)    THE  POSTERIOR  COMMUXICATIXG  ARTERY 

The  posterior  communicating  artery  (iig.  340)  is  giA-en  off  from  the  internal 
carotid  just  before  the  division  of  that  vessel  into  the  anterior  and  middle  cerebral 
arteries;  occasionally  it  arises  from  the  middle  cerebral  itself.  It  is  as  a  rule  a 
slender  vessel  which  runs  backwards  over  the  optic  tract  and  crus  cerebri  along  the 
side  of  the  uncinate  convolution  to  join  the  posterior  cerebral.  At  times,  however, 
it  is  of  considerable  size,  and  contributes  chiefly  to  form  the  posterior  cerebral,  the 
jiortion  of  the  latter  A^essel  between  the  basilar  and  posterior  communicating  being 
then  as  a  rule  reduced  to  a  mere  rudiment.  It  giA-es  off  the  folloAving  branches: — 
(a)  the  uncinate,  to  the  convolution  of  that  name;  and  (6)  the  middle  thalamic, 
to  the  optic  thalannis. 


(7)    THE  ANTERIOR  CHOROID  ARTERY 

The  anterior  choroid  is  a  small  but  constant  A'essel,  which  arises  as  a  rule 
from  the  back  part  of  the  internal  carotid  just  external  to  the  origin  of  the 
posterior  communicating.  It  passes  backwarcls  on  the  o])tic  tract  and  the  crus 
cerebri,  at  first  lying  parallel  and  a  little  external  to  the  posterior  connnunicating 
artery,  and  then,  turning  slightly  outwards,  dips  under  tlie  edge  of  the  uncinate 
couA'oiution,  and,  entering  the  transverse  fissure  at  the  loAver  end  of  the  descending 
cornu  of  the  lateral  ventricle,  ends  in  the  choroid  plexus  and  su]ip]ies  tlie  hi])i)0- 
campus  major  and  corpus  limbriatum. 


AMERIOR   CEREBRAL— MIDDLE  CEREBRAL  50c 


(8)  THE  ANTERIOR  CEREBRAL  ARTERY 

The  anterior  cerebral  artery  (fig.  340) — one  of  the  terminal  branches  into 
which  the  internal  carotid  divides  in  the  fissure  of  Sylvius — passes  at  first  forwards 
and  inwards  across  the  anterior  perforated  space  bet^veen  the  olfactory  and  optic 
nerves  to  the  longitudinal  fissure  where  it  approaches  its  fellow  of  the  o])i)Osite  side, 
and  communicates  with  it  by  a  short  transverse  trimk,  about  two  lines  long,  known 
as  the  anterior  communicating  artery.  Onwards  from  this  spot  it  runs  side  l)y 
side  Avith  its  fellow  in  the  longitudinal  fissure  round  the  genu  of  the  corpus 
callosum;  then,  turning  backwards,  it  continues  along  the  upper  surface  of  that 
commissure,  and,  after  giving  off  large  branches  to  the  frontal  and  parietal  lobules, 
anastomoses  with  the  posterior  cerebral  artery. 

The  branches  of  the  anterior  cerebral  are: — (a)  Communicating;  (6)  gan- 
glionic, or  central;   (c)  commissural;   (f/)  hemispheral,  or  cortical. 

(rt)  Communicating. — The  anterior  communicating  is  a  transverse  trunk 
about  two  lines  in  length,  connecting  the  right  and  left  anterior  cerebral  arteries. 
It  lies  immediately  in  front  of  the  oi)tic  commissure  across  the  lamina  cinerea.  It 
gives  off  some  of  the  antero-median  branches  which  pass  from  the  anterior 
cerebral  to  the  fore  end  of  the  caudate  nucleus.  Sometimes  the  anterior  cerebral 
arteries,  instead  of  communicating  by  a  transverse  trunk,  coalesce  for  a  short 
distance  and  then  again  diyide.  Upon  this  short  trunk  the  terminal  filaments  of 
the  carotid  plexus  of  the  sympathetic  of  either  side  meet  in  a  small  gangliform 
enlargement  known  as  the  '  ganglion  of  Ribes. ' 

(h)  Ganglionic,  or  central. — The  antero-median  group,  together  with  the 
antero-median  branches  of  the  anterior  communicating,  pass  through  the  lamina 
cinerea  and  supply  the  fore  end  of  the  caudate  nucleus. 

(c)  Commissural. — These  supply  the  corpus  callosum. 

((/)  The  hemispheral  or  cortical  branches. — (i )  The  orbital,  three  or  four 
in  numl)t'r,  supply  the  inferior  surface  of  the  first  frontal  convolution,  and  give  off 
small  twigs  to  the  olfactory  bulb,  (ii)  The  margino-frontal  arise  from  the  artery 
as  it  lies  on  the  corpus  callosum,  and,  after  supplying  the  marginal  convolution, 
pass  on  to  the  convex  surface  of  the  hemisphere  and  further  supply  the  first  and 
second  frontal  convolutions  and  the  upper  part  of  the  ascending  frontal  convolution, 
(iii)  The  calloso-marginal  supplies  the  callosal  convolution  and  the  upper  part 
of  the  marginal  convolution,  (iv)  The  quadrate  is  a  1)ranch  to  the  convolution  of 
that  name. 

(9)  THE  MIDDLE  CEREBRAL  ARTERY 

The  middle  cerebral  artery  (fig.  340) — the  larger  of  the  two  terminal  divisions 
of  the  internal  carotid — passes  obliquely  upwards  and  outwards  into  the  fissure  of 
Sylvius,  and  opposite  the  insula  or  island  of  Reil  divides  into  its  hemispheral  or 
cortical  branches. 

The  branches  of  the  middle  cerebral  are: — (a)  Ganglionic,  or  central;  and 
(Jj)  hemispheral,  or  cortical. 

(a)  Ganglionic,  or  central. — (i)  The  caudate  are  two  or  three  small 
branches,  which  arise  from  the  inner  aspect  of  the  artery  and  pass  through  the 
inner  part  of  the  lloor  of  the  fissure  of  Sylvius  to  the  head  of  the  caudate  nucleus, 
(ii)  The  antero-lateral  are  numerous  small  arteries,  which  pass  througli  tlie 
anterior  perforated  space  and  supply  the  caudate  nucleus  (except  its  hea<l ).  the 
internal  capsule,  and  part  of  the  optic  thalamus,  (iii)  The  lenticulo-striate, 
a  larger  branch  of  the  antero-lateral  set,  passes  through  a  separate  hole  in  tlie 
outer  part  of  the  anterior  perforated  space,  runs  upwards  between  the  lenticular 
nucleus  (which  it  supplies)  and  the  external  capsule,  perforates  the  internal 
capsule,  and  terminates  in  the  caudate  nucleus.  It  has  been  so  frequently  found 
ruptured  in  apoplexy,  that  it  is  called  by  Charcot  the  'artery  of  cerebral  ha'inor- 
rhage. '  (iv)  Sometimes  a  more  or  less  distinct  branch,  called  lenticulo-optic,  is 
distributed  to  the  outer  and  hinder  portion  of  the  lenticular  inicleus  and  the 
external  portion  of  the  thalamus  opticus. 


504 


THE  ARTERIES 


(h)  The  hemispheral  or  cortical  branches  come  off  from  the  middle  cerel)ral 
opposite  the  insula.  They  are  four  in  number: — (i)  The  inferior,  or  orbito- 
frontal,  to  the  inferior  frontal  convolutions,  (ii)  The  ascending  frontal,  to  the 
lower  part  of  the  ascending  frontal  convolution,  the  upper  part  being  sui^plied  by 
the  margino-frontal,  a  branch  of  the  anterior  cere})ral.  (iii)  The  parietal,  to  the 
•whole  of  the  ascending  parietal  and  the  adjacent  part  of  the  inferior  ])arietal  convo- 
lution, (iv)  The  parieto-temporal,  to  the  convolutions  around  the  posterior 
limb  of  the  fissure  of  Sylvius — viz.  the  supra-marginal,  the  angular,  and  the 
posterior  part  of  the  inferior  i»arietal  above,  and  the  first  and  the  greater  part  of  the 
second  and  third  temporal  Ijelow. 

The  Circle  of  "Willis 

The  anastomosis  of  the  l)ranches  of  the  internal  carotid  and  vertebral  arteries 
at  the  base  of  the  brain  is  known  as  the  circle  of  Willis  (fig.  340).     This  so-called 


Fig.  340.— The  Arteries  of  the  Brain. 

(The  posterior  part  of  the  cerebrum  on  the  left  side  has  been  cut  away  to  show  the  cerebellum. 
From  a  preparation  in  the  Museum  of  St.  Bartholomew's  Hospital.) 


Anterior  cerebral 
artery 


Middle  cerebral 

artery 
Internal  carotid 

artery 
Postero-median 
per/oratitig 
Posterior  cerebral 
artery 
Superior  cerebellar 
artery 

Anterior  inferior 
cerebellar  artery 


Vertebral  artery 


Posterior  inferior 
cerebellar  artery 


A  n te.rior  com- 
municating 
artery 

Antero-lateral 
jierforalinrj 

Anterior  choroid 

Po.iterior 
commimicaling 
artery 

I'osterior  choroid 

Basilar  artery 
Cms  cerebelli,  cut 


Anterior  sj)inal 
artery 


circle,  which  has  really  the  form  of  a  heptagon,  is  formed,  in  front,  by  the  anterior 
communicating  artery  uniting  the  anterior  cerebral  arteries  of  opposite  sides; 
laterally,  Ijy  the  trunk  of  the  internal  carotid  and  the  posterior  communicating 
arteries  stretching  between  it  and  the  posterior  cerebral;  behind,  by  the  two 
posterior  cerebrals  diverging  from  the  bifurcation  of  the  basilar  artery  (page  543). 
Tliis  free  anastomosis  l>etween  the  two  internal  carotid  and  the  two  vertebral 
arteries  serves  to  equalise  the  flow  of  blood  to  the  various  ] tortious  of  the  brain; 
and,  should  one  or  more  of  the  arteries  entering  into  the  formation  of  the  circle  l)e 
temi)orarily  or  permanently  obstructed,  it  ensures  a  flow  of  blood  to  the  otherwise 
deprived  part  through  some  of  the  collateral  arteries.  Thus,  if  one  carotid  or  one 
vertebral  is  ol)structed,  the  i)arts  supplied  by  that  vessel  receive  their  l)lood  through 
the  circle  from  the  remaining  pervious  vessels.  Indeed,  one  vertebral  artery  alone 
has  been  found  equal  to  the  task  of  carrying  sufficient  blood  for  the  supply  of  the 


THE  SUBCLAVIAN  505 

l)rain  afte-r  Ik^ature  of  both  the  carotids  and  the  other  vertebral  artery.  Further, 
the  circle  of  Willis  is  the  only  medium  of  connnunication  l)et\veen  the  ganglionic 
or  central  and  the  hemispheral  or  cortical  branches  of  the  cerebral  arteries,  and 
between  the  various  ganglionic  Ijranches  themselves.  The  ganglionic  and  the  cor- 
tical branches  form  separate  and  distinct  systems,  and  do  not  anastomose  •with  each 
other;  and  the  ganglionic,  moreover,  are  so-called  end-vessels,  and  do  not  anasto- 
mose with  the  neighlMjuring  ganglionic  Ijranches. 


THE  SUBCLA  VIAN  ARTERY 

The  subclavian  artery  on  the  right  side  arises  at  the  1  )ifurcation  of  the  innomi- 
nate behind  the  right  sterno-clavicular  articulation.  On  the  left  side  it  arises  from 
the  arch  of  the  aorta,  and  as  far  as  the  inner  ])order  of  the  scalenus  anticus  is  situ- 
ated deeply  in  the  chest.  The  first  portion  of  the  left  subclavian  artery  is  described 
separately. 

Beyond  the  inner  l^order  of  the  scalenus  anticus  the  artery  has  the  same  rela- 
tions on  both  sides.  It  courses  from  this  point  Ijeneath  the  clavicle  in  a  slight 
curve  across  the  root  of  the  neck  to  the  outer  ])order  of  the  first  rib.  there  to  end 
in  the  axillary  artery.  Thus  the  course  of  the  artery  in  the  neck  will  l)e  indicated 
Vjy  a  line  drawn  from  the  sterno-clavicular  joint  in  a  curve  with  its  convexity  upwards 
to  the  middle  of  the  clavicle.  The  height  the  artery  rises  in  the  neck  varies.  It  is 
perhajts  most  commonly  about  half  an  inch  above  the  clavicle.  If  the  curved  line 
above  mentioned  is  drawn  to  represent  part  of  the  circumference  of  a  circle  having 
its  centre  at  a  point  on  the  lower  margin  of  the  clavicle  an  inch  and  a  half  from 
the  sternal  end  of  that  bone,  the  line  of  the  artery  will  be  sufficiently  well  indicated 
for  all  practical  purposes.  In  its  course  the  artery  arches  over  the  dome  of  the 
pleura  and  gains  the  groove  on  the  upper  surface  of  the  first  ril)  by  passing  between 
the  scalenus  anticus  and  medius  muscles.  The  artery  is  accompanied  by  the 
subclavian  vein,  the  latter  vessel  lying  in  front  of  the  scalenus  anticus,  anterior  to 
the  artery,  and  on  a  slightly  lower  plane. 

The  subclavian  artery  is  divided  into  three  portions — as  it  lies  internal  to, 
behind,  or  external  to,  the  scalenus  anticus  muscle. 


THE  FIRST  OR  THORACIC  PORTION  OF  THE  LEFT 
SUBCLAVIAX  ARTERY 

The  left  subclavian  artery  Tfig.  328)  arises  from  the  termination  of  the  trans- 
verse portion  of  the  arch  of  the  aorta.  The  first  part  of  the  left  subclavian  is  con- 
sequently longer  than  the  first  jjart  of  the  right,  which  arises  at  the  liifureation  of 
the  innominate  opposite  the  right  sterno-clavicular  joint.  The  artery  at  its  origin 
is  situated  deeply  in  the  thorax,  and  as  it  arises  from  the  aorta  is  on  a  plane  ]m»s- 
terior  to  and  a  little  to  the  left  of  the  thoracic  portion  of  the  left  common  carotid. 
It  first  ascends  almost  vertically  out  of  the  chest,  and  at  the  root  of  the  neck 
curs'es  outwards  over  the  apex  of  the  left  pleura  and  lung  to  the  interval  between 
the  anterior  and  middle  scalene  muscles.  Beyond  the  inner  l)order  of  the  scalenus 
anticus — that  is,  in  the  second  and  third  portions  of  its  course — its  relations  are 
similar  to  those  of  the  right  suVjclavian  artery. 

Relations. — In  front  it  is  covered  by  the  left  pleura  and  lung,  wliilst  more 
superficial  are  the  sterno-thyroid.  sterno-hyoid.  and  sterno-mastoid  muscles.  It  is 
crossed  a  little  above  its  origin  h\  the  left  innominate  vein,  and  higher  in  the  neck 
near  the  iicalenus  anticus  by  the  internal  jugular,  vertebral,  and  sulxlavian  veins. 
The  ]>hrenic  nerve  crosses  the  artery  innnediately  internal  to  the  scalenus  anticus, 
and  then  descends  parallel  to  it  Init  on  an  anterior  plane  to  cross  the  arch  of  the 


506  THE  ARTERIES 

aorta.  The  pneumogastric  nerve  descends  parallel  to  the  artery  between  it  and  the 
left  common  carotid,  coming  into  contact  with  its  anterior  surface  just  before  cross- 
ing the  arch  of  the  aorta.  The  left  cervical  cardiac  nerves  of  the  sympathetic  also 
descend  in  front  of  it  on  their  way  to  the  cardiac  plexus.  The  left  common  carotid 
is  situated  anteriorly  and  to  its  right.  The  thoracic  duct  arches  over  the  artery 
just  internal  to  the  scalenus  anticus,  to  empty  its  contents  into  the  confluence  of 
the  internal  jugular  and  subclavian  veins  (fig.  360). 

Behind  and  somewhat  internal  to  it  are  the  ("esophagus,  thoracic  duct,  inferior 
cervical  ganglion  of  the  sympathetic,  longus  colli  muscle,  and  vertebral  column. 
To  some  extent  it  is  overlapped  posteriorly  by  the  left  pleura  and  lung  (fig.  328). 

On  its  right  side  are  the  trachea  and  the  recurrent  laryngeal  nerve,  and,  higher 
up,  the  oesophagus  and  thoracic  duct. 

On  its  left  side  are  the  left  pleura  and  lung. 

The  chief  variations  in  the  origin  of  the  left  subclavian  artery  are  given  under  Variations 
OF  THE  Arch  of  the  Aorta  (page  472). 


THE  FIRST  PORTION  OF  THE  RIGHT  SUBCLAVIAN  ARTERY 

The  first  portion  of  the  right  subclavian  artery  extends  from  its  origin  at 
the  bifurcation  of  the  innominate,  behind  the  upper  margin  of  the  right  sterno- 
clavicular joint,  upwards  and  outwards  in  a  gentle  curve  over  the  apex  of  the  right 
lung  and  pleura  to  the  inner  border  of  the  scalenus  anticus.  It  measures  about 
one  inch  and  a  quarter  in  length  (3  cm.).  In  this  course  it  ascends  in  the  neck  a 
variable  distance  above  the  clavicle,  but  is  so  deeply  placed,  so  surrounded  by 
important  structures,  and  gives  off  so  many  large  branches,  that  it  is  now  seldom 
or  never  selected  for  the  application  of  a  ligature. 

Relations. — In  front  it  is  covered  by  the  integuments,  the  superficial  fascia, 
the  platysma,  the  anterior  layer  of  the  deep  fascia,  the  clavicular  origin  of  tlie 
sterno-mastoid,  the  sterno-hyoid  and  sterno-thyroid  muscles,  and  the  deep  cervical 
fascia.  It  is  crossed  by  the  commencement  of  the  innominate,  by  the  internal 
jugular,  and  by  the  vertebral  veins;  and  from  within  outwards  by  the  pneumo- 
gastric and  phrenic  nerves,  and  the  superior  cardiac  branches  of  the  sympathetic 
nerve.  A  loop  of  the  sympathetic  nerve  itself  also  crosses  the  arter}^  and  forms 
with  the  trunk  of  the  sympathetic  a  ring  around  the  vessel  known  as  the  annulus 
of  Vieussens. 

Behind,  but  separated  from  the  artery  by  a  cellular  interval,  are  the  longus 
colli  muscle,  the  transverse  process  of  the  seventh  cervical  or  first  thoracic  vertebra, 
the  main  chain  of  the  sympathetic  nerve,  the  inferior  cardiac  nerves,  the  recurrent 
laryngeal  nerve,  and  the  apex  of  the  right  lung  and  pleura. 

Below,  it  is  in  contact  with  the  pleura  and  lung  and  the  loop  of  the  recurrent 
laryngeal  nerve,  wdiich  winds  round  the  artery  from  the  pneumogastric  and  ascends 
behind  it  to  the  larynx.  The  subclavian  vein  is  below^  the  artery  and  on  an  anterior 
plane. 

Branches. — The  vertebral,  internal  mammary,  and  thyroid  axis  arise  from  this 
part  of  the  vessel.  Not  uncommonly  a  small  al)errant  artery  also  takes  origin  from 
this  portion  of  the  artery  and  descends  to  the  left  1:)ehind  the  oesophagus  to  join  a 
branch  of  the  aorta  opposite  the  third  or  fourth  thoracic  vertebra.  This  vessel  is 
probably  the  remains  of  the  right  aortic  root. 


THE  SECOND  PORTION  OF  THE  SUBCLAVIAN  ARTERY 

The  second  portion  of  the  subclavian  artery  lies  behind  the  scalenus  anticus 
muscle.  It  measures  about  three-quarters  of  an  inch  in  length  (2  cm.),  and  here 
reaches  liighest  in  the  neck.  The  subclavian  vein  is  separated  from  tlie  artery  by 
the  scalenus  anticus,  and  lies  on  a  lower  and  anterior  plane. 

Relations. — In  front  it  is  covered  by  the  skin,  superficial  fascia,  platysma, 
anterior  layer  of  deep  fascia,  the  clavicular  origin  of  the  sterno-mastoid,  posterior 


SUBCLAVIAN 


507 


layer  of  deep  fascia,  and  by  the  scalenus  anticus.  The  phrenic  nerve — which,  in 
consequence  of  its  oblique  course  downwards  and  inwards,  crosses  a  i)ortion  of 
both  the  first  and  second  part  of  the  subclavian — is  separated  from  the  second 
portion  by  the  scalenus  anticus  muscle  as  is  also  the  subclavian  vein  which  courses 
on  a  someAvhat  lower  plane. 

Behind  the  artery  are  the  apex  of  the  pleura  and  lung,  and  a  i)ortion  of  the 
scalenus  medius;  also  the  structure  known  as  Sibson's  fascia. 

Above  is  the  brachial  plexus. 

Below  are  the  pleura  and  lung. 

One  branch  only — the  superior  intercostal — is,  as  a  rule,  given  off  from  this 
portion  of  the  subclavian;  occasionally  the  posterior  scapular  artery  arises  from  it. 


THE  THIRD  PORTION  OF  THE  SUBCLAVIAN  ARTERY 

The  third  portion  of  the  subclavian  artery  extends  from  the  outer  margin  of 
the  scalenus  anticus  muscle,  downwards  and  outwards  to  the  outer  border  of  the 


Fig.  341. — The  RmHT  Subclavian  Artery. 


Scalenus  medius 

Scalenus  anticus  and 

ou  it  phrenic  nei-ve 

Traiisrerxt'  ri nicul 

artery 


Suprascapular  artery 


Siihclavian  artery 

CORD  OF  BRA  CHIA  L 
I'LEXVS,  GfViyO 
OFF  .VrsCVLO- 
CUTAXEOUS  AXn 
OUTER  HEAD  OF 
MEDIAN  NER  VES 


Axillary  artery 


MrSCVLO-SPIRAL 
XER  VE 


Thyroid  axis 
Internal  jugular  vein 


Right  common  carotid 

artery 
rXEFMOGASTRIC 

XERVE 
Coiionericement  of 

iiiiioniinate  vein 


.'Subscapular  and  two  circumflex  arteries 


first  rib.  It  is  more  superficial  than  either  the  first  or  second  portions;  it  is  in  rela- 
tion with  less  important  structures,  and  as  a  rule  gives  off  no  l)ranch,  and  for  these 
reasons  is  the  part  selected  when  practicable  for  the  ap})lication  of  a  ligature.  It  is 
the  longest  of  the  three  i)ortions  of  the  sul  tclavian  artery,  and  lies  in  a  triangle — the 
subclavian  triangle — lioundcd  by  the  sterno-mastoid,  the  omo-hyoid.  and  the 
clavicle. 

Relations. —  In  front  it  is  covered  by  the  skin,  superficial  fascia,  platysma,  cla- 
vicular branches  of  the  descending  portion  of  the  superficial  cervical  plexus  of  nerves; 
anterior  layer  of  deep  fascia  which  descends  from  the  omo-hyoid  to  the  clavicle; 
and  the  posterior  layer  of  deep  fascia  which  descends  from  the  omo-hyoid  to  the 
first  rib  and  is  prolonged  inwards  over  the  scalenus  anticus  and  phrenic  nerve. 
Between  the  two  lavers  of  fascia  is  a  variable  amount  of  cellular  tissue  and  f:it,  and 


508  THE  ARTERIES 

running  in  this  is  the  siipraseai)ular  artery.  The  sul^clavian  is  crossed  by  this 
artery  unless  the  arm  is  drawn  -well  downwards.  Hence  one  of  the  reasons  for 
depressing  the  shoulder,  and  thus  avoiding  the  suprascapular  artery,  in  the  opera- 
tion of  ligaturing  the  subclavian.  Close  to  the  outer  margin  of  the  sterno-mastoid, 
the  external  jugular  vein  pierces  the  fascia,  and  crosses  the  subclavian  artery  to 
open  into  the  subclavian  vein.  As  this  vein  lies  between  the  two  layers  of  fascia,  it 
receives  on  its  external  side  the  suprascapular,  transverse  cervical,  and  other  veins 
of  the  neck,  which  together  form  a  plexus  of  large  veins  in  front  of  the  artery.  The 
nerve  to  the  subclavius,  and  when  present  the  accessory  l)ranch  from  this  nerve  to 
the  phrenic,  also  here  cross  in  front  of  the  artery.  In  very  muscular  subjects  the 
sterno-mastoid  may  extend  further  outwards  along  the  clavicle  than  usual,  and  in 
such  a  case  will  form  one  of  the  coverings  of  the  artery. 

Behind,  the  artery  is  in  contact  with  the  scalenus  medius,  and  with  the  cord  of 
the  brachial  plexus  formed  by  the  union  of  the  eighth  cervical  and  first  dorsal 
nerve. 

Below,  the  artery  rests  in  the  posterior  of  the  two  grooves  on  the  upper  surface 
of  the  first  rib. 

Above  is  the  ]:»rachial  plexus  of  nerves  and  the  posterior  ])elly  of  the  omo-hyoid 
nuiscle.  The  cord  formed  l)y  the  fifth  and  sixth  cervical  nerves  is  also  alwve  the 
artery,  but  on  a  somewhat  anterior  plane.  It  is  close  to  the  vessel,  and  has  been 
mistaken  for  the  artery  in  the  application  of  a  ligature. 

As  a  rule  there  is  no  branch  given  off  from  the  third  portion  of  the  subclavian. 
At  times,  however,  the  suprascapular  (fig.  329)  or  the  posterior  scapular  artery  may 
arise  from  the  third  portion  of  the  sul^clavian,  instead  of  from  the  thyroid  axis  and 
from  the  transverse  cervical  respectively  as  here  descril:)ed. 


Chief  Variations  in  the  Subclavian  Artery 


(A)  The  right  subclavian  artery  may  arise  directly  from  the  arch  of  the  aorta,  and  then  come 
off  as  the  first,  second,  tliird  or  fourth  branch  of  that  vessel.  When  it  arises  as  the  first  branch, 
it  takes  the  place  usually  occupied  by  the  innominate  ;  wlien  it  arises  as  the  last  branch,  it 
courses  behind  the  trachea  and  oesophagus  to  gain  the  groove  on  the  first  rib.  As  the  second  or 
third  branch  of  the  aortic  arch  it  is  very  rare  ;  in  both  instances  it  then  runs  behind  the  right 
common  carotid.  The  explanation  of  the  right  subclavian  arising  as  the  last  branch  of  the  arch 
of  the  aorta,  is  that  the  right  aortic  arch  has  remained  pervious,  whilst  the  normal  root  of  the 
subclavian  artery  has  become  obliterated.  An  arteria  aberrans,  given  off  from  the  right  subclavian 
or  from  the  superior  intercostal,  can  generally  be  traced  to  the  third  thoracic  vertebra  behind  the 
oesophagus,  and  in  a  number  of  such  cases  can  be  followed  across  the  s]iine  to  anastomose  with  a 
branch  of  the  thoracic  aorta  given  off  below  the  ductus  arteriosus.  It  is  the  enlargement  of  this 
anastomosis — which  is  itself  the  remains  of  what  was  the  primitive  right  dorsal  aorta  in  the 
embryo — that  gives  rise  to  the  abnormality  in  question.  The  inferior  laryngeal  nerve  in  such 
cases,  in  consequence  of  the  right  fourth  arch  which  firms  the  first  portion  of  the  subclavian  being 
obliterated,  follows  a  direct  course  to  the  larynx  instead  of  winding  recurrently  round  the  sub- 
clavian artery. 

(B)  The  righ{  subclavian  may  arise  higher  or  lower  in  the  neck  than  usual,  according  as  the 
innominate  divides  above  or  below  the  normal  situation. 

(C)  It  may  perforate  the  scalenus  anticus  or  pass  in  front  of  that  muscle. 

(D)  It  may  ascend  as  high  as  an  inch  and  a  half  above  the  clavicle,  or  remain  below  the  level 
of  that  bone. 

(E)  The  third^  iiart  of  the  artery  may  be  covered  by  the  trapezius  or  sterno-mastoid,  or  by  a 
clavicular  origin  of  the  omo-hyoid. 

(F)  The  subclavian  vein  may  accompany  the  artery  behind  the  scalenus  anticus. 

Branches  of  the  Si'bcl avian  Artery 

From  the  first  portion  of  the  subclavian  artery  are  given  off:  from  the  upper 
and  back  ])art  and  al)out  three-quarters  of  an  inch  (2  cm. )  from  its  origin,  the  ver- 
tebral ;  a  little  further  outwards,  from  the  front  })art,  the  thyroid  axis  ;  and  from 
the  lower  part — usually  o)>])()sit('  the  thyroid  axis,  or  else  ])etween  the  thyroid  axis 
and  the  verteljral — the  internal  mammary. 

From  the  second  portion  arises,  from  the  back  of  the  vessel,  the  superior 
intercostal. 

The  third  portion  as  a  rule,  gives  off  no  branch. 


VERTEBRAL 


509 


Branches  of  the  First  Part  of  the  Subclavian  Artery 

THE  VERTEBRAL  ARTERY 

The  vertebral  artery,  tlie  first  and  largest  branch,  arises  from  the  upper  and 
posterior  })art  of  the  first  i)ortion  of  the  subclavian,  on  the  right  side  about 
three-quarters  of  an  inch  (2  cm.)  from  the  origin  of  the  latter  vessel  from  the 
innominate,  on  the  left  side,  from  the  most  prominent  part  of  the  arch  of  the  sub- 
clavian, close  to  the  inner  edge  of  the  scalenus  anticus  muscle.  It  first  ascends  to 
the  foramen  in  the  costo-transverse  process  of  the  sixth  cervical  vertebra,  and,  having 
passed  through  that  foramen  and  those  of  the  next  succeeding  cervical  vertel)rse  as 
high  as  the  axis,  it  turns  outwards    and  tlien  upwards  to  reach  the  foramen  in  the 


Fig.  342.— Scheme  of  the  Left  Veetebrae  Akterv.     (Walsham.) 
The  internal  jugular  and  verteliral  veins  are  Looked  aside  to  exi^ose  the  artery. 


Right  posterior  cerebral  artery 

Left  posterior  cerebral  artery 

Basilar  artery 

BASILAR  PROCESS,  OCCIPITAL  BONE 

Intracranial  portion  of  vertebral 

Rectus  capitis  lateralis  muscle 

FIRST  CERVICAL  XERVE 

Commencement  of  vertebral  vein 

SECOND  CERVICAL  NERVE 

Vertebral  plexus  of  reins 

THIRD  CERVICAL  NERVE 

Vertebral  /lorlion  of  vertebral  artery 
FOURTH  CERVICAL  NERVE 

Vertebral  plexus  of  veins 
FIFTH  CERVICAL  NERVE 

SIXTH  CERVICAL  NERVE 

Inferior  thyroid  artery 

Longus  colli  mutele 

Cervical  portion  of  vertebral  artery 

Internal  jugular  rein,  liooked  a  little 
aside 

Vertebral  vein,  cut 

Subclavian  artery 


Right  and   left  supe- 
rior cerebellar 
arteries 

OCCIPITAL  BONE 


Keetus  capitis  pos- 
ticus minor  mus- 
cle 


/iifal  ]  0)  ti07i  of  rertebral  artery 


A 1  teria  princeps  cervicis 


Semispinalis  colli  muscle 

Deep  cervical  artery 

Scalenus  anticus  muscle,  cut 
Thyroid  axis,  hooked  a  little  aside 
Subclavia/i  rein 


transverse  process  of  the  atlas;  after  passing  through  that  forann^n  it  turns  back- 
wards behind  the  articular  ])rocess  lying  in  the  groove  on  the  jjosterior  arch  of  the 
atlas.  It  next  ]»ierces  the  jiosterior  occipito-atloid  ligament  and  the  dura  mater,  and 
enters  the  cranium  through  the  foramen  magnum.  Here  it  passes  ui)wards,  at  first 
lying  by  the  side  of  tlie  medulla,  then  in  front  of  that  structure,  and  terminates  at 
the  lower  portion  of  tlie  pons  Viy  inosculating  witli  the  vertebral  of  the  opposite  side 
to  form  the  basilar. 

The  vertel)ral  artery  may  be  divided  for  purposes  of  description  into  four  parts: 
the  first,  or  cervical,  extending  from  its  oriirin  to  the  transverse  jtrocess  of  the  sixth 
cervical  vertebra:  the  second,  or  vertebral,  situated  in  the  intt'rvrrtebral  foramina: 
the  third,  or  occipital,  contained  in  the  suboccipital  triangle:  and  the  fourth,  or 
intracranial,  witliin  tlie  cranium. 

The  first  or  cervical  portion. — Tlie  artery   liere  lies    l)etween   the   scalenus 


510  THE  ARTERIES 

aiiticiis  and  longus  colli  muscles.  In  front  it  is  covered  by  the  vertel)ral  and 
internal  jii<iular  veins,  and  is  crossed  by  the  inferior  thyroid  artery;  and  on  the  left 
side,  in  addition,  by  the  thoracic  duct,  Avhich  runs  over  it  from  within  outwards. 
Behind,  the  arterv  lies  on  the  transverse  process  of  the  seventh  cervical  vertebra 
and  the  sympathetic  nerve.  To  its  inner  side  is  the  longus  colli.  To  its  outer 
side  is  the  scalenus  anticus.  It  gives  off  as  a  rule  no  branch  in  this  ])art  of  its 
course.  Occasionally,  however,  a  small  branch  passes  into  the  foramen  of  the 
transverse  process  of  the  seventh  cervical  vertebra. 

The  second  or  vertebral  portion. — As  the  artery  passes  through  the  inter- 
vertebral foramina,  it  is  surrounded  by  a  plexus  of  veins  and  by  liranches  of  the 
sympathetic  nerve.  The  cervical  nerves  lie  behind  it.  Between  the  transverse 
processes  it  is  in  contact  with  the  intertransverse  muscles. 

The  third  or  occipital  portion. — The  artery  here  lies  in  the  suboccipital 
triangle,  bounded  by  the  superior  oblique,  inferior  oblique,  and  rectus  capitis  pos- 
ticus major  muscles.  As  it  Avinds  round  the  groove  on  the  atlas,  it  has  the  rectus 
capitis  lateralis,  the  articular  process,  and  the  occipito-atloid  ligament  in  front  of 
it;  the  superior  ol)lique,  the  rectus  capitis  posticus  major  and  the  complexus 
behind  it.  Separating  it  from  the  arch  of  the  atlas,  is  the  first  cervical  or  sub- 
occi[)ital  nerve. 

The  fourth  or  intracranial  portion  extends  from  the  aperture  in  the  dura 
mater  to  the  lower  border  of  the  pons,  where  it  unites  with  its  fellow  to  form  the 
basilar  artery.  It  here  winds  round  from  the  side  to  the  front  of  the  medulla, 
lying  in  the  vertebral  groove  on  the  basilar  process  of  the  occipital  bone.  In  this 
course  it  passes  beneath  the  first  process  of  the  ligamentum  dentatum,  and  between 
the  hypoglossal  nerve  in  front,  and  the  anterior  roots  of  the  sul)0cci])ital  nerve 
behind. 

Chief  Variations  of  the   Vertebral  Artery 

(A)  The  right  vertebral  artery  may  arise  from  the  first  part  of  the  subclavian,  either  nearer 
to  the  innominate,  or  nearer  to  the  anterior  scalene  muscle  than  normal. 

(B)  It  may  come  off  from  the  arch  of  the  aorta  direct.  (See  Variations  in  the  Chief 
Branches  op  the  Arch  of  the  Aorta.) 

(C)  It  may  arise  from  the  right  common  carotid  when  the  right  subclavian  is  given  off  from 
the  aorta  beyond  the  left  subclavian. 

(D)  It  may  pass  behind  the  oesophagus. 

(E)  The  left  vertebral  artery  may  also  arise  from  the  arch  of  the  aorta  direct,  or  from  the 
left  common  carotid.     (See  Variations  in  the  Chief  Branches  of  the  Aorta.) 

(F)  Either  vertebral  may  enter  the  foramen  in  the  seventh  cervical  vertebra,  or  in  that  of  the 
fifth,  fourth,  third,  or  second.  When  entering  one  of  the  higher  vertebral  foramina,  it  maj'  lie 
behind  the  common  carotid  and  cause  some  embarrassment  in  the  ligature  of  the  latter  vessel. 

(G)  Either  vertebral  may  give  ofiP  the  inferior  thyroid,  superior  intercostal,  deep  cervical, 
or  occipital  arteiy. 

(H)  One  or  other  artery  may  be  much  increased  or  diminished  in  size. 

Branches  of  the  Vertebral  Artery 

A.  Cervical  portion. — No  branch. 

B.  Vertebral  portion. — 1.   Lateral  spinal;  2.   muscular. 

C.  Occipital  portion. — 1.   Muscular;  2.   anastomotic. 

D.  Cranial  portion. — 1.  Posterior  meningeal;  2.  posterior  sjiinal;  8.  anterior 
spinal;  4.   posterior  cerebellar. 

Branches  of  the  Second  or  Vertebral  Portion 

1.  The  lateral  spinal  branches  run  through  the  intervertel>ral  foramina  into 
the  vertebral  canal,  and  there  divide  into  two  branches:  (a)  The  spinal,  which 
ramifies  on  the  backs  of  the  bodies  of  the  cervical  vertebra';  and  (h)  the  medullary, 
Avhicli  runs  along  the  spinal  nerves,  supplies  the  cord  and  its  meml)ranes,  and  anas- 
tomoses with  the  arteries  above  and  below.  2.  The  muscular  branches  sui)ply 
the  deep  muscles  of  the  neck,  and  anastomose  with  the  ascending  cervical,  occi2)i- 
tal,  and  deep  cervical  arteries. 


BASILAR  511 

Branches  of  the  Third  or  Occipital  Portion 

1.  Muscular,  to  the  muscles  forming  the  suboccipital  triangle;  2.  anasto- 
motic, U)  the  branches  of  the  occipital  artery. 

Branches  of  the  Fourth  or  Cranial  Portion 

1.  The  posterior  meningeal  is  a  small  bnuich  given  oft"  as  the  vertebral  artery 
pierces  tlie  dura  mater  to  enter  the  cranium.  It  sui)plies  the  bone  and  dura  mater 
of  the  posterior  fossa  of  the  skull,  and  anastomoses  with  the  jjosterior  meningi'al 
branches  derived  from  the  occipital  and  ascending  pharyngeal  arteries.  It  gives 
branches  to  the  falx  cerel»elli  (lig.  387). 

2.  The  posterior  spinal  artery  runs  downwards  oljliquely  along  the  side  of  the 
medulla  to  the  back  of  the  cord,  dcnvn  wliich  it  passes  behind  the  roots  of  the 
spinal  nerves,  l)eing  reinforced  by  lateral  branches  running  iiiAvards  along  these 
nerves,  in  the  neck  from  the  vertebral,  in  the  dorsal  region  from  the  intercostals, 
and  in  the  lumbar  region  from  the  lumbar  arteries.  It  can  be  traced  as  Ioav  as  the 
end  of  the  spinal  cord. 

3.  The  anterior  spinal  artery  comes  off  from  the  vertebral  a  little  ])elow  its 
termination  in  the  basilar  artery.  Descending  ol)liquely  inwards  in  front  of  the 
medulla,  it  unites  on  a  level  with  the  foramen  magnum  with  its  fellow  of  the  op- 
posite side.  The  single  vessel  thus  formed  runs  downwards  in  fi'ont  of  the  spinal 
cord  beneath  the  pia  mater  as  far  as  the  termination  of  the  cord,  being  reinf<irccd 
by  the  lateral  spinal  l)ranches  the  whole  way  down  (fig.  387).  The  spinal  arteries 
are  descril^ed  in  detail  with  the  anatomy  of  the  spinal  cord. 

4.  The  posterior  inferior  cerebellar  (fig.  340) — the  largest  branch  of  the 
vertebral — arises  from  that  vessel  just  before  it  joins  its  fellow  to  form  the  basilar 
artery.  At  times  it  may  come  off  from  the  basilar  itself.  It  runs,  at  first  outwards 
across  the  restiform  body  between  the  origin  of  the  pneumogastric  and  hypoglossal 
iierves,  and,  descending  towards  the  vallecula,  there  divides  intc)  two  ])ranches,  an 
internal  and  external,  (a)  The  internal  or  inferior  vermiform  branch  runs 
backwards  Ijetween  the  vermiform  i)rocess  and  the  lateral  hcniisi»hcrc  of  the  cere- 
belkim.  It  supplies  the  vermiform  process,  and  anastomoses  Avith  the  artery  of 
the  o]:)posite  side,  and  with  tlie  su])erior  vermifoiin  Ijranch  of  the  superior  cere- 
bellar, {b)  The  external  or  hemispheral  branch  runs  outwards,  and,  ramifying 
over  the  under  surface  of  the  cereV)cllar  hemisphere,  supplies  its  cortex  and  anas- 
tomoses along  its  outer  margin  with  the  superior  cerebellar  arteries. 

From  the  undivided  trunk  of  the  posterior  inferior  cerebellar  artery  branches  are 
given  to  the  choroidal  plexus  and  the  fourth  ventricle. 


THE  BASILAR  ARTERY 

The  basilar  artery  is  formed  by  the  confluence  of  the  right  and  left  vertel)ral 
arteries,  which  meet  at  an  acute  angle  at  the  lower  liorder  of  the  pons  Varolii.  It 
runs  forwards  and  upwards  in  a  slight  groove  in  the  middle  line  of  the  pons,  and 
divides  at  the  upper  l)order  of  that  structure  at  the  level  of  the  i)retentorial  oj>ening 
into  the  two  posterior  cerebral  arteries. 

Branches  of  the  Basilar  Artery 

The  branches  of  the  basilar  artery  are: — 1.  Transverse  or  pontal;  2.  internal 
auditory;  3.   anterior  cerebellar:  4.   stqierior  cerel)ellar;  5.    ])osterior  cerel)ral. 

1.  The  transverse  or  pontal  arteries  are  numerous  small  vessels  which  come 
off  at  right  angles  on  either  side  of  the  basilar  artery,  and,  passing  outwards  over 
the  ])ons.  supply  that  structure  and  adjacent  parts  of  the  brain. 

2.  The  internal  auditory  artery,  a  long  slender  vessel,  accompanies  tlie  audi- 
tory nerve  into  the  internal  auditory  meatus  (fig.  387).  It  here  lies  Itetween  the 
facial  and  auditory  nerves,  and  at  the  l)ottom  of  the  meatus  passes  into  the  internal 
ear,  and  anastomoses  with  the  other  auditory  arteries.      (See  Internal  Ear.) 


512  THE  ARTERIES 

3.  The  anterior  cerebellar — or  anterior  inferior  cerebellar  artery,  as  it  is  some- 
times called — arises  from  the  basilar  soon  after  its  origin,  passes  outwards  and 
l)ackwards  across  the  pons,  and  then  over  the  crus  cerebelli  to  the  front  part  of  the 
imder  surface  of  the  cerebellum.  It  anastomoses  with  the  posterior  inferior  cere- 
bellar artery  (fig.  340). 

4.  The  superior  cerebellar  comes  off  from  the  basilar  immediately  behind  its 
bifurcation  into  the  posterior  cerebral  arteries.  It  courses  outwards  and  backwards 
over  the  pons,  in  a  curve  roughly  corresponding  to  that  of  the  posterior  cerebral 
artery,  from  which  it  is  separatecl  by  the  third  cranial  nerve;  but,  soon  sinking 
into  the  groove  between  the  pons  and  the  crus  cerebri,  it  curves  round  the  latter 
structure  on  to  the  upper  surface  of  the  cerebellum,  lying  nearly  parallel  to  the 
fourth  nerve.  Here  it  divides  into  two  branches,  an  internal  and  external,  (a)  The 
internal  or  superior  vermiform  branch  courses  backwards  along  the  superior 
vermiform  process,  anastomosing  with  its  fellow  of  the  opposite  side,  and  at  the 
posterior  notch  of  the  cerebellum  with  the  inferior  vermiform  branch  of  the  poste- 
rior inferior  cerebellar  artery.  (6)  The  external  or  hemispheral  branch  runs 
outwards  to  the  circumference  of  the  cerebellum,  anastomosing  with  the  external 
branch  of  the  inferior  posterior  cerebellar  artery. 

Branches  are  given  off  from  the  main  trunk  of  the  superior  cerebellar  artery,  or 
from  its  internal  branch  to  the  valve  of  Vieussens,  the  optic  lobes,  the  pineal 
gland,  and  the  choroid  plexus. 

o.  The  posterior  cerebral  arteries  are  the  two  terminal  branches  into  which 
the  basilar  bifurcates  at  tlie  upper  border  of  the  pons  immediately  behind  the  pos- 
terior perforated  space.  Each  artery  runs  at  first  outwards  and  a  little  forwards 
across  the  crus  cerebri  immediately  in  front  of  the  third  nerve,  Avhich  separates  it 
frc^m  the  superior  cerebellar  artery.  After  receiving  the  posterior  communicating 
artery,  Avhich  runs  backwards  from  the  internal  carotid,  the  posterior  cerebral 
turns  backwards  on  to  the  under  surface  of  the  cerebral  hemisphere,  where 
it  breaks  up  into  branches  for  the  supply  of  the  temporo-sphenoidal  and  occipital 
lobes. 

The  branches  of  the  posterior  cerebral  artery  ma}'  be  divided  into  the  gan- 
glionic or  central,  and  tlie  cortical  or  hemispheral. 

(a)  The  ganglionic  or  central  branches,  are  divided  into  the  postero-median ; 
the  posterior  choroid;  and  the  posterq-lateral.  (i)  The  postero-median 
branches  come  off  from  the  posterior  cerebral  near  its  origin,  and,  passing 
through  the  cerel)ral  substance  forming  the  posterior  perforated  spot,  supply  the 
inner  part  of  the  optic  thalamus  and  the  walls  of  the  third  ventricle;  (ii)  the 
posterior  choroid  branch  passes  through  the  transverse  fissure  to  the  velum  inter- 
l)ositum  and  choroid  ]ilexus;  (iii)  the  postero-lateral  branches  arise  external  to 
the  spot  where  the  posterior  cerebral  artery  is  joined  by  the  posterior  communicat- 
ing. They  run  to  the  posterior  part  of  the  optic  thalamus  and  give  branches  to 
the  crus  cerebri  and  optic  lobes  or  corpora  quaclrigemina. 

(b)  The  cortical  or  hemispheral  branches  are  distributed  as  follows: — (i)  the 
uncinate,  a  branch  to  the  anterior  part  of  the  uncinate  convolution;  (ii)  the 
temporal,  a  l)ranch  to  the  inferior  part  of  the  temporal  lobe;  and  (iii)  the  tem- 
poro-occipital,  a  branch  to  the  cuneus,  lingual  convolution,  and  outer  surface  of 
the  occipital  lobe. 

Here  it  may  be  stated,  not  only  in  reference  to  the  branches  of  the  jiosterior 
cerebral  artery,  l:)ut  also  with  respect  to  the  branches  of  the  anterior  and  middle 
cerebral  arteries,  Avhich  are  described  with  the  internal  carotid  (page  503),  that 
there  is  no  anastomosis  between  the  cortical  and  central  branches.  The  cortical  and 
the  central  form  two  distinct  and  separate  systems.  The  cortical  may  or  may  not 
anastomose  with  each  other,  but  the  comnumication  between  the  neighl>ouring 
cortical  branches  is  seldom  sufficient  to  maintain  the  nutrition  of  an  area  when  the 
vessel  that  normally  supjJies  it  is  obstructed.  The  central  l)ranches  are  so-called 
•  ■nd-vessels  and  do  not  anastomose  with  each  other.  Hence  obstruction  of  the 
middle  cerebral  or  Sylvian  artery  leads  to  softening  of  the  area  su])plied  by  its 
central  l)ranches,  l)utnot  always  to  softening  of  the  region  supplied  by  its  cortical 
l)ranches.  Indeed  the  cortical  region  may  escape  completely,  although  the  central 
area  is  irreparably  disorganised.     The  gross  anastomosis  of  the  posterior  cerel)ral 


THYROID  AXIS  513 

with    the    anterior   and   middle   cerebral  arteries    through    the  eirele  of  M'illis  is 
described  with  the  l»ranches  of  tlie  internal  carotid  (page  504j. 


SUMMARY    OF    THE    DISTRIBUTION    OF    THE   CEREBRAL  ARTERIES 

Here  it  may  be  of  advantage  to  give  a  brief  sunnnary  of  tlie  distriljution  of  the 
anterior,  middle,  and  posterior  cerebral  arteries,  the  branches  of  wliich  have  already 
been  described  in  detail.  The  branches  of  each  are  divided  into  the  central  or 
ganglionic,  and  the  cortical  or  hemisi^heral.  The  central  branches  arise  at  the 
commencement  of  the  cerebral  arteries  about  the  circle  of  ^Mllis,  whilst  the  cortical 
are  derived  chiefly  fi'om  the  termination  of  these  vessels. 

(A)  The  central  branches  are  divided  into  six  sets — two  median  and  four 
lateral.  1.  The  two  median  are — (1)  The  antero-median,  which  arise  from  the 
anterior  cerebral  and  the  anterior  communicating,  and  sujijtly  the  fore  end  of  the 
caudate  nucleus,  and  (2)  tlie  postero-median,  which  arise  from  the  jjosterior 
cerebral,  and  supply  the  inner  part  of  the  optic  thalannis  and  neighbouring  wall  of 
the  third  ventricle.  2.  The  four  lateral,  two  on  each  side,  are  also  divided  into 
antero-lateral,  and  postero-lateral.  (1)  The  antero-lateral  arise  from  the  middle 
cerebral,  and,  passing  through  the  anterior  perforated  spot,  supply  the  lenticular 
nucleus,  the  posterior  part  of  the  caudate  nucleus,  the  internal  and  external 
capsules,  and  the  outer  part  of  the  optic  thalamus.  (2)  The  postero-lateral  arise 
from  the  posterior  cereljral,  and  supply  the  hinder  part  of  the  optic  thalamus,  the 
crus.  and  the  optic  lobes  or  corpora  cpiadrigemina. 

(  B)  Tlie  cortical  branches  ramify  in  the  pia  mater,  giving  off  brandies  to  the 
cortical  suVjstance,  some  ol  wliich  extend  through  it  to  the  underlying  white  sub- 
stance. The  cortical  branches  of  the  anterior  cerebral,  roughly  speaking,  supply 
the  median  surface  of  the  frontal  lobe  as  far  as  the  precuneus,  the  inner  part  of  its 
orbital  surface,  and  part  of  its  convex  surface,  viz.  the  highest  part  of  the  ascend- 
ing frontal  and  the  first  and  most  of  the  second  frontal  convolutions.  The  cortical 
branches  of  the  middle  cerebral — or  Sylvian  artery  as  it  is  often  called,  because 
of  its  relation  to  the  Sylvian  fissure — supply  the  most  important  area,  namely,  the 
motor  convolutions;  and  also  the  largest,  namely,  the  inferior  frontal,  the  ascending 
parietal,  part  of  tlie  inferior  parietal,  the  supramarginal  and  angular,  the  posterior 
part  of  the  superior  parietal,  the  first  temporal,  and  the  anterior  yjart  of  the  second 
and  third  temporal  convolutions.  The  cortical  branches  of  the  posterior  cerebral 
supply  the  occipital  lobe,  and  the  inferior  aspect  of  the  temporal  lobe. 

It  will  be  seen,  therefore,  that  the  middle  cerebral  supplies  the  motor  region, 
both  central  and  cortical,  except  a  part  of  the  leg  centre.  It  also  supplies  the 
region  of  the  cortex  that  subserves  cutaneous  sensibility,  the  cortical  auditory 
centre,  and  in  part  the  higher  visual  centre.  It  likewise  supplies  all  the  cortical 
regions  concerned  in  speech  processes  in  the  left  hemisphere.  The  anterior  cerebral 
supplies  only  a  small  part  of  the  motor  region — namely,  the  part  of  the  leg  centre 
that  occupies  the  paracentral  loljule  and  the  highest  part  of  the  ascending  frontal 
convolution.  The  posterior  cerebral  supplies  the  visual  path  from  the  middle  of 
the  tract  backwards,  and  the  half  vision  centre  in  the  occipital  lo)>e.  It  supplies 
also  the  corpora  quadrigemina  and  the  sensory  part  of  the  internal  capsule. 


THE  THYROID  AXIS 

The  thyroid  axis  arises  from  the  upper  and  front  part  of  the  subclavian  artery, 
usually  opposite  the  internal  mammary,  and  a  little  internal  to  the  inner  border  of 
the  scalenus  anticus.  It  is  a  short  thick  trunk,  and  divides  almost  immediately 
into  three  radiating  branches — namely,  the  inferior  thyroid,  the  suprascapular, 
and  the  transverse  cervical  (  fig.  '-530  ). 

r)ccasionally  the  pt)sterior  scajtular  branch  of  the  transverse  cervical  arises  from 
the  third  portion  of  the  subclavian;  the  superficial  cervical,  the  other  branch  into 
which  the  transver.se  cervical  divides,  then  conimonlv  comes  oft'  from  tlie  axis. 
33 


514  THE  ARTERIES 


THE  INFERIOR  THYROID  ARTERY 

The  inferior  thyroid,  the  largest  of  the  three  branches  into  which  the  thyroid 
axis  divides,  ascends  tortuously  upwards  and  inwards  in  front  of  the  verteliral 
artery,  the  recurrent  laryngeal  nerve,  and  the  longus  colli  muscle,  and  l:)eliind  the 
common  carotid,  and  the  symj)athetic  nerve  or  its  middle  cervical  ganglion,  to  the 
thyroid  l>ody,  where  it  anastomoses  with  the  superior  thyroid  artery  and  the  artery 
of  the  opposite  side.  It  gives  off  the  following  branches: — (1)  Muscular;  (2) 
ascending  cervical;   (3)  oesophageal;   (4)  tracheal;  and  (5)  inferior  laryngeal. 

(1)  The  muscular  branches  supply  the  scalenus  anticus,  longus  colli,  sterno- 
hyoid, sterno-thyroid,  and  omo-hyoid  muscles,  and  the  inferior  constrictor  muscle 
of  the  pharynx. 

(2)  The  ascending  cervical  (fig.  329)  is  given  off  from  the  inferior  thyroid  as 
that  vessel  is  passing  l)cneath  the  carotid  sheath.  It  ascends  lietween  the  scalenus 
anticus  and  the  rectus  cai»itis  anticus  major,  lying  parallel  and  a  little  internal  to 
the  phrenic  nerve  and  l)t4iind  the  internal  jugular  vein.  It  anastomoses  with  the 
vertebral,  ascending  pharyngeal,  and  occipital  arteries,  and  su])]4ies  the  following 
])ranches: — (a)  Muscular,  to  the  deej)  muscles  of  the  neck;  {h)  spinal,  which  enter 
the  spinal  canal  Avith  spinal  liranches  of  the  vertel^ral  artery;  and  (c)  phrenic,  to 
the  phrenic  nerve.  Two  veins  accompany  the  ascending  cervical  artery,  and  end 
in  the  innominate  vein. 

(3)  The  oesophageal  branches  of  the  inferior  thyroid  artery  supj^ly  the 
oesophagus,  and  anastomose  with  the  other  arteries  supplying  that  tube. 

(4)  The  tracheal  branches  ramify  on  the  trachea,  where  they  anastomose  with 
the  tracheal  branches  of  the  superior  thyroid  and  bronchial  arteries. 

(5)  The  inferior  laryngeal  branch  passes  along  the  trachea  to  the  back  of  the 
cricoid  cartilage  in  company  with  the  recurrent  laryngeal  nerve.  It  enters  the 
lar\aix  beneath  the  inferior  constrictor.  Its  further  distribution  in  that  organ  is 
described  under  Larynx. 


THE  SUPRASCAPULAR  ARTERY 

The  suprascapular,  or  transversalis  humeri,  passes  more  or  less  transversely 
outwards  across  the  root  of  the  neck,  lying  first  beneath  the  sterno-mastoid,  and 
then  in  the  sul)clavian  triangle  behind  the  clavicle  and  subclavius  muscle.  At  the 
external  angle  of  this  space  it  is  joined  Ijy  the  suprascapular  nerve,  sinks  beneath 
the  posterior  belly  of  the  omo-hyoid,  and  passes  over  the  ligament  bridging  the 
scapular  notch,  the  nerve  passing  through  the  notch  (fig.  343).  It  then  ramifies 
in  the  supraspinous  fossa  of  the  scapula,  and,  winding  downwards  round  the  base 
of  the  s])ine  over  the  neck  of  the  scapula,  enters  the  infraspinous  fossa,  and  ter- 
minates by  anastomosing  with  the  dorsal  scapular  and  posterior  scapular  arteries. 
As  it  lies  under  cover  of  the  sterno-mastoid  muscle,  it  crosses  the  ]ihrenic  nerve  and 
the  scalenus  anticus;  and  as  it  courses  through  the  sul)clavian  triangle,  it  is  se]"»a- 
rated  by  the  (>ervical  fascia  which  descends  from  the  omo-hyoid  to  the  first  rib, 
from  the  subclavian  artery  and  brachial  plexus  of  nerves.  If  this  artery  is  seen  in 
tying  the  subclavian  it  should  not  be  injured,  as-  it  is  one  of  the  chief  vessels  by 
\\'hi(4i  the  collateral  circulation  is  carried  on  after  ligature  of  the  subclavian  in  the 
third  part  of  its  course.  At  the  outer  part  of  the  subclavian  triangle  it  is  covered 
by  the  trapezius,  and  after  passing  over  the  scapular  ligament  it  pierces  the  supra- 
spinous fascia  and  ]iasses  beneath  the  supra-spinatus  muscle,  and  ramifies  between 
it  and  the  bone.  In  the  infraspinous  fossa  it  lies  l)etween  the  infra-spinatus  and 
the  bone.      The  artery  is  ace(un])anie(l  bv  two  veins. 

The  branches  of  the  suprascapular  are: — (1)  Tlie  inferior  sterno-mastoid, 
given  off  to  that  nuiscle  as  the  vessel  crosses  behin<l  it;  (2)  the  subelaviculai' to 
the  subclavius  nmscle;  (3)  the  nutrient,  to  the  clavicle;  (4)  the  sui)rasternal, 
which  passes  over  the  sternal  end  of  the  clavicle  to  the  skin  of  the  upper  part  of 
the  chest;  (5)  the  acromial,  to  the  arterial  rete  or  plexus  on  the  acromial  process, 
to  reach  which  it  pierces  the  trapezius;  (6)  the  articular,  to  the  aciomio-clavicular 


TRA  NS  VERSE  CER  VIC  A  L 


515 


joint  and  shonklcr-joint;  (7)  llit^  subscapular,  given  off  as  the  artery  is  passing 
over  the  suprascapuhir  ligament,  de,seends  to  the  subscapular  fossa  between  the 
subscapularis  and  the  bone,  and  anastomoses  with  the  infrascapular  In'anch  of  the 
dorsal  sca])ular  artery,  and  Avith  the  subscapular  and  posterior  scapular  arteries; 
(8)  the  suprasjoinous  branches,  which  ramify  in  the  supraspinous  fossa,  and 
supply  the  supra-spinatus  muscle  and  the  i)eriosteum  and  the  nutrient  artery  to  the 
bone;  (D)  the  infnisi)in()us  branches,  which  ramify  in  a  similar  way  in  the  infra- 
spinous  fossa,  giving  off'  like  twigs  to  the  infra-spinatus  nuiscle,  the  periosteum,  and 
tiic  l)one. 

THE  TUANSVERSE  CERVICAL  ARTERY 

Tiie  transverse  cervical  or  transversalis  colli  artery — somewhat  larger  than 
the  suprascapular  artery — runs  like  the  latter  vessel  tr;nisversely  outwards  across 
the  root  of  the  neck,  but  on  a  slightl}^  higher  j)lane,  and  a  little  above  the  clavicle. 


Fig.  343. — Scheme  of  Axa.sto.moses  of  the  Right  Scapular  Arteries.     (Walsham.) 

Subscapular  branch  of  sitprascajmlar  artery 
Supraspinous  branch  of  suprascapular  artery 


I'iist'-rior  scafiular  artery 


Supraspinous  branch 
of  posterior  scapular 
artery 

Sub^capu/ar  branch 
of  posterior  scapular 
artery 


Branch  of  intercostal 
artery 


Branch  of  intercostal 
artery 
Continuation  of  posterior 
scapular  artery 


fi'prascapular  artery 


Acromial  brunch 
of  acromio- 
thmacic 

Acromial  refe 


ubscapular  branch 

of  stiprascapuliir 

artery 
Infraspinous  branch 

of  suprasci'jiular 

artery 
Subscapular  brunch 

of  axillary  artery 


I'orsal  sctijiiilar  lirnnch  of 
subscapular  artery 


Infrascapular   branch   of 
<l07-sal  scapular  artery 


Continuation  ofsnb- 
stapular  artery 


At  its  origin  from  the  thyroid  axis  it  lies  under  the  sterno-mastoid;  on  leaving  the 
cover  of  this  muscle,  it  crosses  the  upper  part  of  the  subclavian  triangle,  lying  here 
only  beneath  the  platysma  and  cervical  fascia;  further  outwards,  it  passes  beneath 
the  anterior  margin  of  the  trapezius  and  omo-hyoid  muscle,  and  at  the  outer 
margin  of  the  levator  anguli  scapuke  divides  into  the  ]>o.sterior  sca])ular  and  super- 
ficial cervical  arteries.  In  this  course  it  crosses  the  j)hrenic  nerve,  the  scalenus 
anticus,  the  brachial  ])lexus,  and  the  scalenus  medius.  At  times  it  passes  between 
the  cords  of  the  brachial  plexus. 

The  terminal  branches  of  the  transverse  cervical  artery  are: — (1)  The 
posterior  sca})ular;  and  (  2  )  the  suiK-ilicial  cervical.  The  ])()steri( a- scapular  occa- 
sionally arises  from  the  thinl  jiortion  of  the  subclavian  artery. 


51 G  THE  ARTERIES 

(1)  The  posterior  scapular — the  a})paveiit  continuation  of  the  transverse 
cervical  artery — begins  at  the  outer  border  of  the  levator  anguU  scapuUe,  and, 
continuing  its  course  beneath  this  muscle  to  the  U])per  and  posterior  angle  of  the 
scapula,  turns  downwards  and  skirts  along  the  ])osterior  border  of  the  scapula, 
between  the  serratus  niagnus  in  front  and  the  levator  anguli  scapula;  and  rhom- 
boideus  minor  and  major  behind,  to  the  inferior  angle,  where  it  anastomoses  ^yith 
the  subscapular  artery.  It  gives  off  the  folloAving  branches: — (a)  Supraspinous, 
which  ramifies  lietween  the  supraspinous  muscle  and  the  trapezius,  and  sends 
branches  through  the  muscle  into  the  fossa,  to  anastomose  Avith  the  suprascapular 
arter}'.  (6)  Infraspinous  branches,  one  or  more  of  which  enter  the  infraspinous 
fossa,  and  anastomose  with  the  dorsal  scapular,  {c)  Subscapular  branches, 
which  enter  the  subscapular  fossa,  and  anastomose  Avith  the  suprascapular,  infra- 
scapular,  and  subscapular  arteries,  {d)  Muscular  branches,  to  the  muscles 
between  Avhich  it  runs  and  to  the  latissimus  dorsi.  These  branches  anastomose  with 
the  posterior  divisions  of  the  intercostal  arteries. 

(2)  The  superficial  cervical  artery,  smaller  than  the  posterior  scapular, 
ascends  under  cover  of  the  anterior  margin  of  the  trajjezius,  lying  upon  the  levator 
anguli  scapulae  and  splenius  muscles.  It  supplies  branches  to  the  trapezius,  levator 
anguli  scapulffi,  and  splenius  muscles,  and  the  posterior  chain  of  lymphatic  glands. 
It  anastomoses  with  the  superficial  branch  of  the  princeps  cervicis  Avhich  descends 
from  the  occipital  betAveen  the  splenius  and  complexus.  It  is  accompanied  by  two 
veins.  This  artery  may  arise  directly  from  the  thyroid  axis,  or  from  the  third 
l)art  of  the  subclavian  artery. 


THE  INTERNAL  MAMMARY  ARTERY 

The  internal  mammary  artery  (fig.  344)  comes  off  from  the  loAver  part  of  the 
first  2)ortion  of  the  subclavian,  usually  opposite  the  thyroid  axis,  close  to  the  inner 
edge  of  the  scalenus  anticus,  occasionally  opposite  the  vertebral,  or  at  a  spot 
l)etAveen  these  tAVO  vessels.  It  descends  Avith  a  slight  inclination  forwards  and 
iuAvards,  under  cover  of  the  clavicle,  and  enters  the  thorax  behind  the  cartilage  of 
the  first  rib,  and  thence  passes  doAvn  behind  the  cartilages  of  the  next  succeeding 
ribs,  about  half  an  inch  from  the  external  margin  of  the  sternum,  to  the  sixth 
interspace,  Avhere  it  divides  into  the  superior  epigastric  and  musculo-phrenic. 
It  is  accompanied  by  two  veins,  Avhich  unite  into  one  trunk  behind  the  first 
intercostal  muscle,  and  pass  to  the  inner  side  of  the  artery  into  the  corresponding 
vena  innominata;  occasionally  on  the  right  side  into  the  vena  cava  superior  direct. 
The  artery  may  l;)e  divided  into  tAvo  portions,  the  cervical  and  the  thoracic. 

The  cervical  portion  is  covered  by  the  sterno-mastoid  muscle,  subclavian  vein, 
and  internal  jugular  vein,  and  is  crossed  obliquely,  from  Avithout  iuAvards,  by  the 
phrenic  nerve.  It  rests  upon  the  pleura  and  courses  round  the  upper  part  of  the 
innominate  vein.      There  is  no  branch  from  this  part  of  the  artery. 

The  thoracic  portion  lies  behind  the  cartilages  of  the  six  upper  ribs,  and  in 
the  interspace  betAveen  the  ribs  has  in  front  of  it  the  pectoralis  major  and  the 
internal  intercostal  muscles  and  the  external  intercostal  membrane.  Behind,  it  is- 
in  contact  above  Avith  the  pleura,  but  it  is  separated  from  it  loAver  doAvn  by  slips 
of  the  triangularis  sterni.  On  the  left  side  the  artery  Ix'tAveen  the  fourth  and  sixth 
ribs  maybe  said  to  be  in  the  anterior  mediastinum,  the  pleura  here  forming  a  notch 
for  the  heart,  '[w  the  first,  second,  and  third  spaces  the  artery,  if  Avounded,  can 
be  easily  tied;  but  in  the  fourth  space  the  operation  is  attended  Avith  more  difficulty. 
The  remaining  spaces  are  so  narroAV  that  a  portion  of  the  cartilage  Avould  have  to 
be  removed  to  ex])Ose  the  A'cssel. 

The  branches  of  the  internal  mammary  artery  are: — (1)  The  superior 
phrenic;  (^2  j  the  mediastinal,  or  thymic;  (o)  the  ])ericardiac;  (4)  the  sternal;  (5) 
the  anterior  intercostals;  (6)  the  perforating;  (7)  the  lateral  infracostal;  (8)  tlie 
superior  epigastric;  and  (9)  the  nuisculo-phrenic. 

(1)  The  superior  phrenic,  or  comes  nervi  phrenici,  is  a  long  slender  vessel 
Avhich  comes  off  from  the  internal  mammary  just  after  it  has  entered  tlie  chest,  and 
descends  Avith  the  phrenic  nerve,  at  first  betAveen  the  i)leura  and  innominate  vein; 


INTERNA L  MAMMAR  Y 


517 


then  between  the  pleura  and  the  vena  cava  superior;  and  lastl}',  between  the  pleura 
and  the  pericardium  to  the  diaphragm,  where  it  anastomoses  with  the  other  dia- 
phragmatic arteries.      It  gives  brandies  both  to  the  pleura  and  i)ericardium. 

(2)  The  mediastinal  or  thymic  branches  come  off  irregularly  from  the  internal 
mannnary.  They  arc  of  small  size,  and  supply  the  connective  tissue,  fat,  and 
lym})hatics  in  the  superior  and  anterior  mediastina  and  the  rt^-mains  of  the  thymus 
gland. 

(3)  The  pericardiac  branches  are  distriV)uted  to  the  anterior  surface  of  the 
pericardium. 

(4)  The  sternal  branches  enter  the  nutrient  foramina  in  the  sternum,  and  also 
supply  the  triangularis  sterni. 


Fig.  344. — Scheme  of  the  Kioht  Interxal  Mammary  Artery.     (Walshani. 

Common  carotid  artery 


PHRENIC  ySR  VE 

Subclavian  artery 
Subc/ariaH  rein,  cut 


A  nterior  intercostal  brancli 


Anterior  intercostal  branch 


Mnscnlo-phrenic  artery 


Deep  circumflex  iiiae  artery 


Internal  jugular  vein 
Siihrlavian  vein,  cut 
Scalenus  anticus  muscle 


Triangularis  sterni  muscle 


Perforating  branch 


Superior  epigastric  artery 


Deep  epigastric  artery 


(5)  The  anterior  intercostal  arteries  (fig.  344) — two  in  each  of  the  live  or 
six  ui)per  intercostal  s}nices — run  outwards  from  the  internal  mammary  artery, 
along  the  lower  border  of  the  ril)  ahovc  and  the  up])cr  l)order  of  the  rib  below,  and 
anastomose  with  the  corresponding  uj)))er  and  lower  liranches  of  the  aortic  intcr- 
costals.  Each  pair  of  branches  sometimes  arises  by  a  common  trunk  from  the  in- 
ternal mammary,  which  in  this  case  soon  divides  into  an  upper  and  a  lower  branch, 
as  above  described.  They  lie  at  first  between  the  internal  intercostal  muscles  and 
the  pleura;  afterwards  between  the  external  and  internal  intercostal  muscles.  They 
supply  the  contiguous  muscles,  the  ]-)ector:ilis  major,  and  the  ribs. 

(6)  The  perforating  or  anterior  perforating  branches — five  or  six  in  number, 
one  corresponding  to  each  of  the  five  or  six  upper  spaces — come  off  from  the  front 


518  THE  ARTERIES 

of  the  internal  nianiniary,  between  the;  su])eriur  and  inferior  anterior  intercostals, 
and,  })erforating  the  internal  intereostal  nmscles,  pass  forwards  between  the  costal 
cartilages  to  the  pectoralis  major,  which  they  supply.  The  terminal  twigs  perforate 
that  nuisele  close  to  the  sternum,  and  are  distributed  to  the  integument.  The 
second,  third,  and  fourth  perforating  supply  the  inner  and  deep  surface  of  the 
mammary  gland,  and  become  greatly  enlarged  during  lactation.  They  frequently 
require  ligation  in  excision  of  the  l)reast. 

(7)  The  lateral  infracostal  artery  (Macalister)  is  given  ofif  close  to  the  first 
rib,  and  descends  behind  the  ril)s  just  external  to  the  costal  cartilages.  It  anasto- 
m(.)ses  with  the  upper  intercostal  arteries.  This  vessel  is  often  of  insignificant  size, 
or  absent. 

(8)  The  superior  epigastric  artery  (fig.  o44),  or  internal  terminal  branch  of 
the  internal  mammary  artery,  leaves  the  thorax  behind  the  seventh  costal  cartilage 
by  passing  through  the  costo-xiphoid  space  in  the  diaphragm.  It  is  the  direct 
prolongation  of  the  internal  mammary  downwards.  In  the  abdomen  it  descends 
behind  the  rectus  muscle,  between  its  posterior  surface  and  its  sheath,  and,  lower, 
entering  the  substance  of  the  muscle,  anastomoses  with  the  deep  e})igastric,  a 
branch  of  the  external  iliac.  It  gives  off  the  following  small  branches: — (ft)  The 
phrenic,  to  the  diaphragm;  (h)  the  xiphoid,  which  crosses  in  front  of  the  ensi- 
form  cartilage,  and  anastomoses  with  the  artery  of  the  opposite  side;  (c)  the  cuta- 
neous, which  perforate  the  anterior  layer  of  the  sheath  of  the  rectus  and  sui>i)ly 
the  integuments;  {d)  the  muscular,  to  the  rectus  muscle,  some  of  Avhich  perforate 
the  rectus  sheath  laterally,  and  are  distributed- to  the  oblique  muscles;  (e)  the 
hepatic  (on  the  right  side  only),  which  pass  along  the  falciform  ligament  to  the 
liver,  and  anastomose  with  the  hepatic  artery;  (/)  the  peritoneal  which  perforate 
the  posterior  layer  of  the  sheath  of  the  rectus,  and  ramify  on  the  peritoneum. 

(9)  The  musculo-phrenic,  or  external  terminal  branch  of  tlie  internal  mam- 
mary artery,  skirts  outwards  and  downwards  behind  the  costal  cartilages  of  the  false 
ribs  along  the  costal  attachments  of  the  diaphragm,  which  it  perforates  opposite  the 
ninth  rib.  It  terminates,  much  reduced  in  size,  at  the  tenth  or  eleventh  intercostal 
space  by  anastomosing  with  the  ascending  branch  of  the  deep  circumflex  iliac  artery. 
It  gives  off  in  its  course  the  following  small  branches: — (a)  The  phrenic  for  the 
supply  of  the  diaphragm;  (h)  the  anterior  intercostals,  two  in  number  for  each 
of  the  lower  five  or  six  intercostal  spaces,  are  distril)Uted  like  those  to  the  upper 
spaces,  already  described,  and  anastomose  like  them  with  the  corresponding  branches 
of  the  lower  aortic  intercostals;  (c)  the  muscular  for  the  supply  of  the  obliciue 
muscles  of  the  abdomen. 


Braxches  of  the  Second  Paet  of  the  Subceavian  Autery 

THE  SUPERIOR  INTERCOSTAL  ARTERY 

1.  The  superior  intercostal  artery  (fig.  845)  usually  arises  from  the  back  part 
(»f  the  second  portion  of  the  subclavian  artery,  behind  the  scalenus  anticus  on  the 
right  side,  but  sometimes  just  internal  to  that  muscle  on  the  left  side.  It  at  first 
runs  backwards  and  a  little  upwards  above  the  apex  of  the  pleura,  and  then  turns 
downwards  and  enters  the  thorax  in  front  of  the  neck  of  the  first  rib.  It  termi- 
nates in  a  l)ranch  which  runs  forwards  in  the  first  intercostal  space.  Frequently, 
and  especially  on  the  right  side,  it  is  continued  in  front  of  the  neck  of  the  second 
rib,  and  sup])lies  a  branch  to  the  second  intercostal  space.  This  branch  may  then 
be  reinforced  by  an  intercostal  from  the  aorta,  wdiich  supplies  the  space  when  the 
branch  is  not  present.  As  the  superior  intercostal  crosses  the  neck  of  the  first  rib, 
it  lies  internal  to  the  anterior  branch  of  the  first  dorsal  nerve,  and  external  to  the 
superior  thoracic  ganglion  of  the  sympathetic.  That  part  of  the  superior  intercostal 
which  intervenes  lietwei'u  its  origin  from  the  subclavian  and  its  first  branch,  is 
sometimes  called  the  costo-cervical  artery. 

Branches. — The  sujx'rior  intercostal  gives  off: — (1)  The  deep  cervical;  (2) 
the  first  intercostal;  and  (3)  the  arteria  aV)errans. 

(1)  The  deep  cervical  branch  is  given  off  from  the  sujierior  intercostal  just 


SUPERIOR  INTERCOSTAL 


519 


before  the  latter  enters  the  thorax.  It  passes  directly  hac'kwartls,  first  between  the 
seventh  and  eighth  cervical  nerves,  and  then  V»etween  the  transverse  i)rocess  of  the 
seventh  cervical  vertebra  and  the  neck  of  the  first  rib,  having  the  body  of  the  seventh 
cervical  vertebra  to  its  inner  side,  and  the  intertransverse  muscle  to  its  outer  side. 
It  then  turns  upwards  in  the  groove  between  the  transverse  and  spinous  i)rocesses 
of  the  cervical  vertebne  lying  upon  the  semispinalis  colli.  It  is  covered  by  the 
complexus.  Between  these  muscles,  near  the  axis,  it  anastomoses  with  the  deep 
branch  of  the  princeps  cervicis  of  the  occipital  artery.  The  deep  cervical  is  homol- 
ogous in  its  course  to  the  posterior  Itranch  of  an  aortic  intercostal,  being  morpho- 
logically the  posterior  branch  of  tlie  intercostal  artery  for  the  seventh  cervical  space. 
It  gives  oflf  the  following  small  branches: — (a)  Muscular,  to  the  semispinalis  colli 
and  complexus;  (h)  anastomotic,  which  anastomose  with  branches  of  the  verte- 
bral, ascending  cervical  and  princeps  cervicis  arteries;  and  (/)  vertebral  or  spinal, 

Fig.  345. — Scheme  of  the  Right  Superior  Intercostal  Artery.     (Walsham.) 


Scalenus  amicus  muscle 

Deep  cervical  branch 

FIRST  DORSAL  SERl E 

FIRS T  IXTERCOS T4L 
yERVE 

Siibc/acian  atlei  >j 


SECOND  INTERCOSTAL 
NER  VE 


Aiilerior  intercostal 
arterii 
THIRD  INTER- 
COSTAL NERVE 


Anterior  intercostal 
artery 

Internal  mammary 
artery 

Intercostal  ressels  of 
th  ird  space 


SYMPATHETIC 
NER  VE 

INFERIOR  CERVI- 
CAL GANGLION 

I  Superior  intercostal 
J  artery 


Arteria  aberrans 


Branch  from  first  aortic 
intercostal 


Arteria  aberratis 


First  aortic  intercostal 
artery 


Second  aortic  intercostal 

artery 


Intercostal  vessels  ojjourth  space 


which  enters  the  spinal  canal  through  the  intervertebral  foramen  with  the  eighth 
cervical  nerve. 

(2)  The  first  intercostal  branch  runs  forwards  in  the  first  intercostal  space, 
and,  like  the  second  intercostal  branch,  which,  Avhen  present,  runs  to  the  second 
space  on  the  right  side,  resembles  in  its  course  and  distribution  the  succeeding 
intercostals  derived  from  the  aorta.      (See  Branches  of  Thoracic  Aorta.) 

(3)  The  arteria  aberrans,  when  jtresent,  comes  oft"  from  the  inner  side  of  the 
right  superior  intercostal,  and  occasionally  from  the  right  subclavian  itself.  (See 
jiageoOB. )  It  descends  as  a  delicate  vessel  into  the  thorax,  passing  liackwards 
and  inwards  behind  the  oesophagus  as  far  as  the  third  or  fourth  thoracic  vertebni, 
where  in  some  cases  it  is  found  to  anastomose  with  a  similar  delicate  branch  com- 
ing off  from  the  aorta  below  the  ductus  arteriosus.  This  anastomosis,  which  repre- 
sents the  remains  of  the  right  dorsal  aortic  stem,  may  become  enlarged,  and  the 
suliclavian  artery  on  the  right  side  be  derived  from  the  arch  of  the  aorta.  This 
accounts  for  the  subclavian  in  such  circumstances  passing  behind  the  oesophagus. 
(See  Variations  of  the  Arch  of  the  Aorta.  ) 


520  THE  ARTERIES 


THE  AXILLARY  ARTERY 

The  term  axillary  is  applied  to  that  portiuu  of  the  main  arterial  stem  of  the 
upper  limb  that  passes  through  the  axilla.  The  axillary  artery  therefore  is  con- 
tinuous with  the  subclavian  above  and  with  the  brachial  below.  It  extends  from 
the  outer  border  of  the  lirst  rib  to  the  lower  edge  of  the  teres  major  nmscle,  and  has 
the  shoulder-joint  and  the  neck  of  the  humerus  to  its  outer  side.  "\Mien  the  arm 
is  placed  close  to  the  side  of  the  body,  the  artery  forms  a  gentle  curve  with  its 
convexity  upwards;  but  when  the  arm  is  carried  out  from  the  side  at  right  angles 
to  the  trunk  in  the  ordinary  dissecting  position,  the  vessel  takes  a  nearly  straight 
course,  which  will  then  be  indicated  by  a  line  drawn  from  the  middle  of  the 
clavicle  to  a  spot  midway  between  the  condyles  of  the  humerus.  The  axillary 
artery  is  at  first  deeply  placed  beneath  the  pectoral  muscles,  but  in  its  lower  third 
is  superficial,  being  covered  onl}^  by  the  skin  and  the  superficial  fascia  and  deep 
fascia.  It  is  divided  into  three  parts — first,  second,  and  third,  according  as  it  lies 
respectively  above,  beneath,  or  below  the  pectoralis  minor. 

The  Pirst  Part  of  the  Axillary  Artery 

The  first  part  of  the  axillary  artery  extends  from  the  outer  border  of  the  first 
rib  to  the  upper  border  of  the  pectoralis  minor.  It  measures  about  an  inch  in 
length  (2 '5  cm.). 

Relations. — In  front  it  is  covered  by  the  skin,  superficial  fascia,  the  origin  of 
the  platysma,  the  deep  fascia,  the  pectoralis  major,  the  costo-coracoid  membrane, 
the  subclavius  muscle  and  the  clavicle  when  the  arm  hangs  down  by  the  side.  The 
cephalic  and  acromio-thoracic  veins,  the  external  anterior  thoracic  nerve,  and  the 
axillary  lymphatic  trunk,  cross  over  it.  A  layer  of  the  deep  cervical  fascia  which 
has  ])assed  under  the  clavicle  also  descends  in  front  of  it. 

Behind,  it  rests  upon  the  first  intercostal  space  and  first  intercostal  mus- 
cle, the  first  digitation  and  sometimes  a  portion  of  the  second  digitation  of 
the  serratus  magnus  muscle,  and  a  part  of  the  second  rib.  The  posterior  or 
external  respiratory  nerve  of  Bell,  on  its  way  to  the  serratus  magnus  muscle, 
passes  behind  it. 

To  its  outer  side,  and  somewhat  on  a  higher  plane,  are  the  cords  of  the 
brachial  plexus. 

To  its  inner  side,  and  on  a  slightly  anterior  plane,  is  the  axillary  vein.  The 
anterior  internal  thoracic  nerve  courses  between  the  vein  and  the  arterv. 


The  Second  Part  of  the  Axillary  Artery 

The  second  part  of  the  axillary  artery  (fig.  346)  lies  lieneath  the  pectoralis 
minor  deep  in  the  axilla.  It  measures  a  little  more  than  an  inch  in  length 
(3  cm.). 

Relations. — In  front,  in  addition  to  the  pectoralis  minor,  it  is  covered  by  the 
pectoralis  major  and  tlie  integuments. 

Behind,  it  is  separated  by  a  considera1)le  interval  containing  loose  connective 
tissue  and  fat  from  the  subscapularis  muscle;  whilst  behind,  and  in  contact  with 
it,  is  the  posterior  cord  of  the  brachial  plexus. 

To  the  inner  side,  but  separated  from  the  arterv  by  the  inner  cord  of  the 
brachial  plexus,  is  the  axillary  vein. 

To  the  outer  side  is  the  outer  cord  of  the  l)rachial  })lexus,  and  at  some  little 
distance  the  coracoid  process. 

It  is  thus  seen  that  the  second  portion  of  the  axillary  artery  is  surrounded  on 
three  sides  by  the  cords  of  the  brachial  plexus — one  behind,  one  internal,  and  one 
external. 


AXILLARY  521 

The  Third  Part  of  the  Axillary  Artery 

The  third  part  of  the  axillary  artery  (tig.  346)  extends  from  the  lower  l)order 
of  the  pectoralis  minor  to  the  lower  border  of  the  teres  major.  Its  upper  half  lies 
deeply  placed  within  the  axilla,  beneath  the  lower  edge  of  the  pectoralis  major 
muscle,  l)ut  its  lower  half  is  in  the  arm  external  to  the  axilla,  and  is  uncovered  by 
muscle.      It  measures  about  three  inches  in  length  (7 '5  cm.). 

Relations. — In  front  it  has,  in  addition  to  the  skin  and  superficial  fascia,  the 
I)ectoralis  major  above,  and  lower  down  the  deep  fascia  of  the  arm.  It  is  crossed 
obliquely  b}^  the  inner  root  of  the  median  nerve  and  Ijy  the  outer  brachial  vena 
comes. 

Behind,  it  lies  successively  ujion  the  subscapularis,  the  latissimus  dorsi,  and 
tores  major  muscles.  From  the  first-named  muscle  it  is  separated  at  first  by  a  con- 
siderable mass  of  fat  and  cellular  tissue.  The  musculo-spiral  and  circumfiex 
nerves  intervene  V^etween  the  arter}^  and  the  muscles. 

On  its  outer  side  it  is  separated  from  the  bone  by  the  coraco-brachialis,  by 
which  it  is  jjartly  overlapped,  this  muscle  and  the  short  head  of  the  biceps  serving 
as  a  guide  to  the  artery  in  ligature.  For  a  part  of  its  course  it  has  also  the  musculo- 
cutaneous nerve  and  the  outer  root  of  the  median  nerve  to  its  outer  side. 

To  its  inner  side  it  has  the  axillary  vein,  the  ulnar  nerve,  the  internal  cutaneous 
nerve,  the  lesser  internal  cutaneous  nerve,  and  the  inner  root  of  the  median  nerve. 
The  ulnar  nerve  is  between  the  artery  and  the  vein.  The  internal  cutaneous  nerve 
is  a  little  in  front  of  the  artery  as  well  as  internal  to  it. 

]^ariations  in  the  Axillary  Artery 

The  chief  variations  in  the  axillary  artery  are  : — (a)  It  may  give  off  the  radial  artery; 
[h)  more  rarely,  the  ulnar  artery  ;  (c)  still  mure  rarely,  the  interosseous  arteiy,  or  a  vas  aberrans  ; 
[d)  it  may  give  off  a  common  trunk,  from  which  may  arise  the  sub.scapulai',  the  anterior  and 
posterior  circumflex,  and  the  superior  and  inferior  profunda  arteries.  The  branches  of  tlie 
brachial  plexus  usually  surround  this  common  tiTink,  and  not  what  is  apparently  the  main  brachial 
artery.  The  latter  vessel  indeed  would  seem  in  many  of  these  instances  to  be  reallj'  an  enlarged 
vas  aberrans,  and  the  common  trunk  the  main  brachial  artery,  the  lower  portion  of  which  has 
been  obliterated,  i.e.  obliterated  from  the  last  branch  given  off  from  the  common  trunk  to  the 
si)Ot  where  it  is  again  joined  by  the  vas  aberrans.  {e)  The  axillarj'  artery  may  be  covered  in 
the  third  part  of  its  course  by  a  muscular  sli])  (the  dorsi  axillaris),  derived  from  the  ujjper  i»art 
of  the  tendon  of  the  latissimus  dorsi,  and  alwaj^s  present  in  early  foetal  life,  though  as  a  rule 
atrophied  later. 

Branches  of  the  Axillary  Artery 

The  first  part  gives  off: — (1)  The  superior  thoracic;  and  (2)  the  acromio- 
thoracic. 

The  second  part  gives  oft': — (1)  The  long  thoracic;  and  (2)  the  alar  thoracic. 

The  third  part  gives  off: — (1)  The  subscajtular;  (2)  the  anterior  circumfiex; 
and  (8)  the  posterior  circumflex. 

Branches  of  the  First  Part  of  the  Axillary  Artery 

1.  The  superior  or  short  thoracic  is  variously  given  oft"  from  tlit-  axiUary 
artery,  usually  either  as  a  conniion  trunk  with  the  next  l)ranch,  the  acromial 
thoracic,  or  a  little  above.  It  passes  behind  the  axillary  vein  across  the  first  inter- 
costal space,  supplying  the  intercostal  muscles  and  the  upper  ])ortion  of  the  ser- 
ratus  magnus,  and  anastomoses  with  the  intercostal  arteries.  At  times  it  sends  a 
branch  between  the  pectoralis  major  and  minor,  which  then,  as  a  rule,  more  or 
less  takes  the  place  of  the  pectoral  branch  of  the  acromial  thoracic. 

2.  The  acromio-thoracic,  or  thoracic  axis,  arises  from  the  front  part  of  the 
axillary  just  above  the  U])per  border  of  the  pectoralis  minor.  It  is  a  short  trunk, 
and  coming  off  from  the  front  of  the  artery  pierces  the  costo-coracoid  membrane, 
and  then  divides  into  three  or  four  small  l>ranches,  named  from  their  direction: — 
{<!)  the  acromial,  or  thoracica  acromialis;  (//)  the  humeral,  or  thoracica  humeralis; 
(c)  the  pectoral,  or  short  thoracic  of  some  autliors;  and  (c/)  the  clavicular. 


522 


THE  ARTERIES 


Fig.  346.  — The  Lower  Part  of  the  Axillary,  the  Brachial,  and  the  Radial  and 

Ulnar  Arteries,  Right  Side. 

;^From  a  dissection  iu  the  Museum  of  the  Royal  College  of  Surgeons  of  England.) 

BRACHIAL  PLEXUS 


Subscapularis 
Acroiiiio-lhoracic  artery 
Axillary  artery 
MEDIA  X  XER  VE 
Subscapular  artery 


HEAD  OF  HUMERUS 
Peetoralis  minor,  turned  back 

MUSCUL  O-CCTAXEO  I'S  XER  VE 

BRAXCH   OF  Ml\S('VLi>-CVTA- 

XEOUS  TO    ME  DUX   XERVE 

Coraco-brachialiB 


Brachial  artery 


Superior  profunda  artery 


Biceps 


MUSCULO-CUTANEO  US  XER  VE 

BRAXCH  OF  MUSCULO-CUTA- 
XEOUS  XERVE  TO  BRACHI- 
AL IS  AX  TIC  US 

Srachialis  anticus 
MEDIAX  XER  VE 

Inner  brachial  vena  comes 

MUSCULO-SPIRAL  XERVE 

Radial  recurrent  artery 
Supinator  longus 

Superficial  median  vein,  cut  short 


Pronator  radii  teres,  superficial 
head,  cut 


RADIAL  XERVE  . 


Radial  artery 

Cut  edge  of  flexor  subliinia 
digit  orum 

MEDIAX  XERVE 


Flexor  longus  poUicis 


Teres  major 
Latissimus  dorsi 

Long  head  of  triceps 
MUSCULO-SPIRAL  XERVE 

)  MUSCULAR  BRAXCH  OF 
y     MUSCULO-SPIRAL 
I      XER  VE 


* Inferior  prof  unda  artery 

Inner  head  of  triceps 
ULXAR  XER  VE 

Anastomolica  magna  artery 
Internal  intermuscular  septurr 


MUSCULAR  BRANCHES  OF 
MEDIAX  XERVE 

Pronator  teres  and  superficial 
flexor  muscles,  turned  back 

Anterior  ulnar  recurrent  artery 

Deep  head  of  pronator  radii 
teres 


Posterior  itlnar  recurrent  artery 


Superficial  flexor  muscles, 
turned  back 


Anterior  interosseous  artery  and  nerve 
Plexor  profundus  digitorum 
ULXAR  XERVE 

llnar  artery 


Interosseous  membrane  with  cut  edge 
of  pronator  quadratus 


AXILLARY 


523 


(a)  The  acromial  branch  or  branches  pass  outwards  across  the  coracoid  process, 
frequently  through  the  deltoid  muscle,  which  they  in  part  supply,  to  the  acromion, 
where  they  form,  by  anastomosing  with  the  anterior  and  posterior  circumflex  and 
suprascapular  arteries,  the  so-called  acromial  rete,  or  plexus  of  vessels  on  the  sur- 
face of  that  process. 

(6)  The  humeral  branch  —  the  descending  branch  of  some  authors  —  runs 
downwards  with  the  cephalic  vein  in  the  interval  between  the  pectoralis  major  and 
the  deltoid,  and,  supplying  lateral  offsets  to  these  muscles  and  the  adjacent  integu- 
ments, anastomoses  witli  the  anterior  and  posterior  circumflex  arteries. 

(c)  The  pectoral  branch  j^asses  between  the  pectoralis  major  and  minor  mus- 


Fio.  347. — The  Dorsal  Scapular  Artk:ry,  Right  Side. 
(From  a  ilissectiou  in  the  Museum  of  the  Koyal  College  of  Surgeons.) 

Supra-spinatus     Siiprascnjitilar  artery 
Posterior  scajnilar  artery  |       |  Infra-spinatus 


Rhomboideus  minor 
Levator  anguli  scapula 


Triceps,  cut 

Deltoid,  insertion 
Deltoid 


Trapezius 
Rhomboideus  major 

Teres  major  muscles 


Teres  major,  insertion 
Dorsalis  scapulce  artery   Posterior  circumjiez  artery 


cles,  both  of  which  it  supplies,  and  the  superimposed  mammary  gland.  In  the 
female,  one  or  more  of  these  branches  which  perforate  the  pectoralis  major  are  often 
of  large  size. 

(d)  The  clavicular  branch  passes  upwards  V)eneath  the  clavicle  and  supplies 
the  subclavius  muscle,  and  anastomoses  with  the  suprascapular  artery. 


Branches  of  the  Second  Part  of  the  Axillary  Artery 

1.  The  long  thoracic  artery — also  called  the  external  mammary — descends 
along  the  lower  l)order  nf  the  pectoralis  minor,  under  cover  of  tlie  ])ect<iralis  major, 
to  the   walls  of   the  chest.     It  supplies   both  pectoral  muscles  and  the  serratus 


524 


THE  ARTERIES 


magnus,  sends  branches  round  the  lower  border  of  the  pectoralis  major  to  the 
mammary  gland,  and  terminates  in  the  intercostal  muscles  by  anastomosing  with 
the  aortic  intercostals  and  the  internal  mamnmry.  It  als.j  furnishes  branches  to 
the  glands  of  the  axilla.  The  branches  to  the  mammary  gland  in  the  female  are 
often  of  large  size. 

2.  The  alar  thoracic  are  small  branches  given  off  either  directly  from  the  axil- 
lary artery  to  the  lympliatic  glands  in  the  axiJla,  or  from  some  of  the  other 
branches  of  the  first  or  second  part  of  the  axillary  arter}-. 

Branches  of  the  Third  Part  of  the  Axillary  Artery 

1.  The  subscapular  artery  is  the  largest  branch  of  the  axillary.  It  arises 
opposite  the  lower  border  of  the  subscapularis,  and  runs  downwards  and  inwards 


Fig.  348. — The  Right  Posteeiok  Circumflex  Aeterv. 
(From  a  dissection  by  Mr.  Homer  in  the  Museum  of  St.  Bartholomew's  HospitiU. 


Suprascapular  artery 
SPINE  OF  SCAPULA 


Infra-spinatus,  out 
ACROMIAL  PROCESS         |  Teres  minor 

Superior  profunda  artery 

Posterior  circnmffer  artery 
Deltoid,  reflected 


ML  SCI  LO-SPIRA  L  NER  \'E 

Outer  head  of  triceps 

V      EXTERNA  L  CUTA  NEO  US 
BRANCH  OF 
MUSCULO- 
SPIRAL  NERVE 


Infra-spinatus,  cut 

Teres  major 

Dorsal  scapular  artery 

Branch  of  dorsal  scapular  artery 

NER  VE  TO  TERES  MINOR 


I 


Long  head  of  triceps 
CVTANEorS  BRANCH  OF  CIRCVMFLEX  NERVE,  Cl'T 


along  the  anterior  border  of  that  muscle  under  cover  of  the  latissimus  dorsi  as  far 
as  the  angle  of  the  scapvila,  where  it  anastomoses  with  the  dorsal  scapular,  pos- 
terior scapular,  long  thoracic,  infrascapular,  and  the  intercostal  arteries.  The  lonir 
subscapular  nerve  accompanies  it.  It  supplies  tlie  subscapularis,  teres  major, 
latissimus  dorsi,  and  serratus  magnus  muscles,  and  gives  branches  to  the  glands 
in  the  axillary  space.  The  course  of  this  large  vessel  along  the  posterior  border  of 
the  axilla  sliould  be  remembered  in  opening  abscesses  in  the  axilla,  and  in  remov- 
ing enlarged  glands  from  this  space.  It  is  accompanied  by  two  veins,  which 
usually  unite  and  then  receive  the  dorsal  scapular  vein,  and  open  as  a  single  vein 
of  large  size  either  into  the  axillary  or  at  the  confluence  of  the  inner  ])rachial  vena 
comes  with  the  basilic  vein. 

About  an  inch  to  an  inch  and  a  half  from  its  origin,  the  subscapular  artery  gives 
off  the  following  large  branch : — 


AXILLARY 


525 


The  dorsal  scapular,  arisiiiu;  from  the  siil)seapular,  usually  at  the  ahove- 
mentioned  spot,  passes  hackwards  throu^di  the  triangular  spaee  bounded  by  the  sub- 
scapularis  above,  the  teres  major  l)elo\v,  and  the  long  head  of  the  triceps  externally, 
and  then  between  the  teres  minor  and  the  axillary  border  of  the  scapula,  which  "it 
connnonly  grooves.  It  thus  reaches  the  infraspinous  fossa,  Avhere,  under  cover  of 
the  infraspinatus,  it  anastomoses  with  the  suprascapular  and  posterior  scapular 
arteries  (tig.  347).  As  it  passes  througli  the  triangular  s})ace,  it  gives  off  a  ventral 
branch,  sometimes  called  the  infrascapular,  which  ramifies  between  the  subscapu- 
laris  and  the  bone,  supplying  branches  to  the  subscapularis,  to  the  scapula,  and 
to  the  shoulder-joint.  A  second  branch  is  often  given  off  near  the  triangular  space 
and  passes  downwards  between  the  teres  major  and  teres  minor,  supplying  both 
muscles  (fig.  348). 

The  chief  variations  in  the  subscapular  artery  are: — (a)  It  niaj-  come  off  witli  the  posterior 
circuiuflex;   (Z>)  it  iiiaj'  arise  from  a  trunk  commou  to  several  other  of  the  branches  of  the  third 


Fig.  349. — The  Anastomoses  about  the  Scapula. 

Subscapiilar  branch  of  snpraseiijiular  artery 
Siipraspinovs  hrnnch  of  suprascapular  artery 


Posterior  scapular  arlr 


Supraspinous  hranrli 
uf  posterior  scapulur 
artery 

Suhscapti/ar  branch 
of  posterior  scapulur 
artery 


Branch  of  intercostal 
artery 


Branch  of  intercostal 
artery 
<  'ontimtalion  of  posterior 
scapulur  artery 


Suprascapular  artery 


Acromial  branch 
of  ucromio- 
tlioracic 

Acromial  rete 


Subscapular  branch 

of  suprascapular 

artery 
Infraspinous  branch 

of  suprascapular 

artery 
Subsiiipiilar  branch 

<f  axillary  artery 


Dorsal  scapular  branch  of 
subscapular  artery 


Iiifrasciijiulur   branch   if 
dorsal  scapular  artery 


Continuation  of  sub- 
senpular  artery 


part  of  the  axillary  artery  and  upjier  pavt  of  the  brachial  artery  ;  and  (c)  its  dorsal  scapular 
hranch  may  arise  from  the  axillary  direct. 

2.  The  anterior  circumflex,  usually  quite  a  small  vessel,  comes  ofif  from  the 
outer  .side  of  the  axillary  artery,  generally  opposite  the  posterior  circumflex.  It 
passes  beneath  the  coraco-brachialis  and  short  and  long  heads  of  the  biceps,  wind- 
ing transversely  round  the  front  of  the  surgical  neck  of  the  linmerus,  across  the 
bicipital  groove,  and  anastomoses  with  the  posterior  circumflex  and  acromial 
thoracic  arteries.  It  gives  off  the  following  small  branches:  (n)  the  bicipital  or 
ascending,  which  runs  up  the  bici|)ital  groove  to  sup])ly  the  long  tendon  of  the 
biceps  and  the  shouhler-joint;  and  (h)  a  pectoral  or  descending  branch,  which 
runs  downwards  along  the  insertion  of  the  pectoralis  major,  and  supplies  the  tendon 
of  that  muscle.      The  anterior  circumflex  artery,  in  conse(|Uence  of  its  being  close 


526  THE  ARTERIES 

to  the  bone,  is  sometimes  difficult  to  secure  in  the  operation  for  excision  of  the 
shoulder-joint. 

Chief  variations. — (a)  The  anterior  circumflex  may  be  given  off  from  the  jiu^terior  circum- 
flex ;  or  {b)  I'rom  a  stem  common  to  it  and  several  other  vessels.  (See  Variations  in  the 
Axillary  Artery,  page  521.) 

3.  The  posterior  circumflex  artery  (fig.  348)  arises  from  the  hinder  part  of 
the  axillary,  just  lielow  thi-  lower  Itorder  of  the  subscapularis  muscle.  It  passes 
through  the  quadrilateral  space,  bounded  by  the  teres  minor  above,  the  latissimus 
dorsi  and  teres  major  below,  the  humerus  externally,  and  the  long  head  of  the 
triceps  internally,  and,  Avinding  round  the  back  of  the  humerus  beneath  the  deltoid. 
l)reaks  up  under  cover  of  that  muscle  into  a  leash  of  branches,  which  for  the  most 
part  enter  its  substance.  The  circumflex  nerve  and  two  vena^  comites  run  with  it. 
It  anastomoses  with  the  anterior  circumflex,  the  arteries  on  the  acromion,  and  the 
suj^erior  profunda  artery. 

In  addition  to  the  leash  of  vessels  to  the  deltoid,  it  gives  off  the  following  small 
branches: — (a)  nutrient,  to  the  greater  tuberosity  of  the  humerus;  (6)  articular, 
to  the  back  of  the  shoulder-joint;  (c)  acromial,  to  the  plexus  on  the  acromion;  and 
((/)  muscular,  to  the  teres  minor  and  long  and  short  heads  of  the  triceps.  One  or 
more  of  these  branches  to  the  triceps  (the  tricipital)  descend  either  between  the 
outer  and  long  head,  or  in  the  substance  of  that  muscle  to  anastomose  with  an 
ascending  branch  from  the  superior  profunda  artery.  It  is  by  means  of  this 
anastomosis  that  the  collateral  circulation  is  chiefly  carried  on  when  the  axillary 
or  the  brachial  artery  is  tied  between  the  origins  of  the  posterior  circumflex  and 
superior  profunda  arteries  (fig  330). 

The  chief  variations  in  the  posterior  circumflex  are: — {a)  It  may  arise  with  the  subscapular 
artery  as  a  cunimou  trunk.  (6)  It  may  come  ofi"  from  the  brachial,  and  run  up  behind  tlie  teres 
major  to  the  quadrilateral  space,  (c)  It  may  give  off  the  inferior  jirofunda,  the  anterior  circum- 
flex, or  the  dorsal  scapular,  {d)  It  may  be  double,  (e)  It  may  form  one  of  the  vessels  arising 
from  a  trunk  common  to  several  branches  of  the  axillary  and  brachial  arteries.  (See  VARIATIONS 
in  the  Axillary  Artery,  page  521. 


THE  BRACHIAL   ARTERY 


The  brachial  artery,  the  continuation  of  the  axillary,  extends  from  the  lower 
border  of  the  teres  major  \o  a  little  below  the  centre  of  the  crease  at  the  bend  of 
the  elbow,  where  it  divides,  opp(^site  the  junction  of  the  head  with  the  neck  of 
the  radius,  into  the  radial  and  ulnar  arteries.  The  artery  is  situated  at  first  inter- 
nal to  the  humerus;  but  as  it  passes  down  the  arm  it  gradually  gets  in  front  of  tlie 
bone,  and  at  the  bend  of  the  elbow  lies  midway  between  the  two  condyles  (fig. 
350).  Hence,  in  controlling  haemorrhage,  the  artery  should  be  comj)resse(l  out- 
wards against  the  bone  in  its  upper  third,  outwards  and  backwards  in  its  middle 
third,  and  directly  backwards  in  its  lower  third.  Throughout  the  greater  part  of 
its  course  the  artery  is  superficial,  being  merely  overlapped  slightly  on  its  outer  side 
by  the  coraco-brachialis  and  bice]>s  muscles;  but  at  the  bend  of  the  elbow  it  sinks 
deeply  beneath  the  semilunar  fascia  of  the  biceps  into  the  triangular  interval 
(antecubital  s])ace),  bounded  on  either  side  by  the  supinator  longus  and  })ronator 
radii  teres,  and  at  its  bifurcation  is  more  or  less  under  cover  of  these  muscles  (fig. 
351).  The  sheath  of  the  brachial  artery  is  closely  incorp(n"ated  with  the  fascia 
covering  the  l)ice])s  muscle,  and  it  is  for  this  reason  that  in  the  operation  for  liga- 
turing, the  vessel  is  a])t  to  be  retracted  with  the  muscle.  A  line  drawn  from  midway 
between  the  folds  of  the  axilla  at  the  outer  side  of  that  space  to  midway  between 
the  condyles  of  the  humerus,  will  indicate  its  course.  It  is  accompanied  by  two 
veins  which  frequently  communicate  across  the  artery. 


BRACHIAL 


if21 


Relations.— In  front,  tlie  artery  is  covered  by  the  integuments  and  suijerficial 
and  deep  faseite,  and  at  the  Ijend  of  the  ell)ow  by  the  semikniar  fascia  of  the  biceps, 
and  ni  muscular  suljjects  l)y  the  overlapping  margins  of  the  supinator  longus  and 


Yiii.  350.— Thk  PJkachial  Autkrv,  Left  Sn)E. 
(From  a  dissection  in  the  Museum  of  the  Royal  College  of  Surgeons.) 

^iijinuicuputar  artery  and  nerve 


Subscapular  lesiels 


CIRCUMFLEX 1 

SERVE 


SUBSCAPULAR 
SERVE 


TrioepB 
Basilic  vein 


ULXAR  SERVE 

Triceps 

Inferior  profunda  artery 


I  STERNA  L  CUT  A  SEO I  .s 
SER  VE 

Brachial  arleni 
MEDIAS  SERVI 


Ulnar  artery 


Axillary  artery  and 

vein 
MUSCULO-CUTA- 
NEOUS  and  in- 
lernalhi  outer 
head  of  MEDIAS 
SERVE 
One  of  the  brachial 
veins 

Coraco-brachialia 


Cephalic  vein 
AnastomoHca  maffna  artery 


Mi  SCULO-CUTASEO  US 
SER  VE 


Supinator  longus 
Radial  lein 


Median  vein 


Radial  artery 


pronator  radii  teres.  In  the  middle  third  of  the  arm  it  is  crossed  obli.,uelv  from 
without  mwards  l>y  the  median  nrrve,  and  at  the  liend  of  the  elbow  bv  the  inedian 
basilic  vein,  the  bicipital  fascia  interveninsr  ( ti-r.  357). 


528 


THE  ARTERIES 


Behind,  it  lies  successively  on  the  long  head  of  the  triceps  (from  which  it  is 
separated  by  the  musculo-spiral  nerv^e  and  superior  profunda  artery),  on  the  inner 
head  of  the  triceps,  on  the  insertion  of  the  coraco-brachialis,  and  thence  to  its 
bifurcation  on  the  brachialis  anticus  muscle. 

External  to  the  artery  is  the  coraco-brachialis  above,  and  the  muscular  belly  of 
the  bice[)s  bflow,  V)oth  of  which  slightly  overlap  the  vessel,  and  at  the  bend  of  the 
ell)o\v  the  tendon  of  the  biceps.  The  external  vena  comes  is  also  to  its  outer  side. 
The  median  nerve  is  in  close  contact  with  the  outer  side  of  the  artery  in  the  upper 
third  of  its  course,  but  in  the  middle  tliird  crosses  the  artery  obliquely  to  gain  the 
inner  side. 

Internal  to  the  artery  in  the  upper  part  of  its  course  are  the  internal  cutaneous 
and  the  ulnar  nerves;  the  latter  nerve,  however,  leaves  the  artery  about  the  origin 


Fig.  351. — The  Brachial  Artery  at  the  Bend  of  the  Elbow,  Left  Side,  Front  View, 


POSTERIOR  BRANCH 

OF  INTERNAL 

CUTANEOUS  NERVE 
ANTERIOR    BRANCH 

OF  INTERNAL 

CUTANEOUS  NERVE 


Biceps  muscle 


BRANCH  OF  MUSCULO- 
SPIRAL  NERVE  TO 
SUPINA  TOR  L ON(t US 

RADIAL  NERVE 

Riulir,]  recurrent  artery 
<nnl  POSTERIOR  ' 
INTEROSSEOUS 
NERVE 

Tendon  of  biceps 

MUSCULO-CUTANEO  US 
NER  VE 


Supinator  longus  muscle 


■f-         Radial  artery 


of  the  inferior  profunda  branch,  to  make,  with  that  vessel,  for  the  internal  con- 
dyle. Lower  down,  the  internal  cutaneous  nerve  also  leaves  the  artery,  by  piercing 
the  deep  fascia.  The  median  nerve  is  in  close  contact  with  the  inner  side  of  the 
artery  in  its  lower  third  and  at  the  bend  of  the  elbow.  The  basilic  vein  is  super- 
ficial to  it,  and  a  little  to  its  inner  side  in  the  greater  part  of  its  course,  but 
separated  from  it  l)y  the  deep  fascia.  The  internal  vena  comes  runs  along  its  inner 
side. 


The  Variations  in  the  Brachial  Artery 

The  chief  variations  in  the  brachial  artery  are: — (1)  A  high  division  into  its  terminal 
branches.  The  high  division  inny  occur  at  any  spot  in  the  iionnal  course  ot"  the  vessel,  but  is 
most  common  in  the  upper  third  of  the  arm,  and  least  common  in  the  middle  third.  The  two 
vessels  into  which  the  brachial  then  divides  as  a  rule  run  parallel  tu  eacli  other  to  the  bend  of"  the 


BRACHIAL  529 

elliiiw  ill  tlie  usual  situatitm  of  the  brat-liial,  whence  one  follows  the  normal  course  of  the  radial 
artery  through  tlie  iorearni,  and  tlie  other  takes  the  noruial  course  of  the  ulnar  artery,  givini^  off 
as  usual  tiie  coniiuon  interosseous  artery.  This  aiTangeiuent  may  be  consideied  a  simple  high 
division  of  the  brachial.  At  other  times  the  disposition  of  the  two  vessels  is  different :  thus  (i) 
tlu'  two  arteries  may  communicate  at  the  elbow  by  a  cross  branch,  or  reunite,  and  then  again 
divide  in  the  usual  manner,  (ii)  One  ve.«sel  may  follow  the  course  of  the  ulnar  artery  in  the 
forearm,  and  the  other  divide  into  the  radial  and  common  interosseous.  This  condition  is  spoken 
of  as  a  high  origin  of  the  ulnar,  (iii)  One  artery  may  divide  into  tlie  radial  and  ulnar  as  usual, 
and  the  other  take  the  course  of  the  common  interosseous  and  divide  into  the  anterior  and  jios- 
terior  interosseous  arteries  ;  or,  much  more  rarely,  take  the  course  of  the  posterior  interosseous 
artery,  the  anterior  intero-sseous  coming  from  the  ulnar,  (iv)  The  vessels  may  follow  a  course  in 
the  upper  arm  different  from  that  of  the  normal  brachial.  Thus  (A)  the  branch  rei)re.senting 
the  radial  may  (a)  cross  over  or  under  the  other  branch  ;  (b)  perforate  the  deep  fascia  above  the 
elbow,  and  run  beneath  the  skin  to  its  place  in  the  forearm  ;  or(c)  pass  behind  the  tendon  of  the 
biceps.  (B)  The  branch  representing  the  ulnar  may  (a)  run  to  the  front  of  the  inner  condyle 
with  the  meilian  nerve,  and  thence  reach  its  u.sual  situation  by  descending  from  within  outwards 
beneath  the  fascia  and  jironator  teres,  or,  more  rarely,  beneath  some  of  the  flexor  mu.scles,  or 
merely  beneath  the  skin  ;  or  (b)  it  may  run  with  the  ulnar  nerve  behind  the  inner  condyle,  and 
thence  beneath  the  muscles  to  its  u.sual  place  in  the  forearm.  (2)  An  enlarged  vas  aberrans  may 
be  present.  This  is  a  long  slender  A'essel,  which  arises  from  the  brachial  usually  near  the  origin 
of  the  superior  profunda,  and  joins  most  commonly  the  radial  artery,  or,  more  rarely,  one  of  its 
branches,  or  the  ulnar.  It  is  said  to  be  usually  present,  though  not  admitting  of  complete  injec- 
tion, and  to  descend  over  the  median  nerve  to  the  biceps  muscle.  At  times  this  vessel  takes  the 
jilace  of  the  bracliial  ;  the  median  nerve  will  then  be  found  behind  the  artery.  (3)  The  brachial 
may  run  with  the  median  nerve  towards  the  inner  condyle,  where  it  then  usually  turns  round  a 
supracondyloid  process  after  the  course  normally  taken  by  the  artery  in  the  Felidfe,  in  which 
it  runs  through  a  supracondyloid  foramen.  Thence  it  descends  to  its  normal  situation  beneath 
the  pronator  teres,  which  then  usually  arises  from  a  fibrous  expansion  from  the  process. 
(4)  The  brachial  may  be  covered  'by  various  nni.scular  slips  derived  from  the  adjacent  muscles. 
(.5)  Certain  abnormalities  in  the  giving  off  of  its  collateral  branches.  These  are  referred  to 
under  each  branch. 

Branches  of  the  Brachi.\l  Artery 

The  branches  of  the  brachial  artery  are: — (1)  The  superior  profunda;  (2) 
tlie  inferior  profunda;  Co)  the  anastornotica  magna;  (4)  the  nutrient;  (5)  the 
muscular;  and  (G;  tlie  terminal  branches — the  radial  and  ulnar  arteries. 

d)  The  Superior  Profunda  Artery 

Tlic  superior  profunda  is  the  largest  of  the  branches  of  the  brachial.  It  arises 
from  the  inner  and  hinder  aspect  of  that  artery,  a  little  below  the  inferior  liorderof 
the  tendon  of  the  teres  major.  It  at  first  lies  to  the  inner  side  of  the  lirachial,  but 
soon  passes  behind  that  vessel,  and,  sinking  between  the  inner  and  long  heads  of  tlie 
triceps  with  the  musculo-spiral  nerve,  curves  round  the  humerus  in  the  musculo- 
spiral  groove,  lying  in  contact  with  the  bone  between  the  inner  and  outer  heads 
of  the  triceps.  On  reaching  the  external  supracondyloid  ridge  of  the  humerus,  it 
perforates  the  external  intermuscular  septum,  and.  continuing  forward  between  the 
supinator  longus  and  brachialis  anticus  to  the  front  of  the  external  condyle,  ends 
by  anastomosing  with  the  radial  recurrent  artery. 

It  gives  off  the  following  Itranches: — 

(a)  The  ascending  branch,  which  runs  upwards  behind  the  tendon  of  the 
teres  major  in  the  sul)Stance  of  the  triceps,  or  between  the  outer  and  inner  heads  of 
that  muscle,  to  anastomose  with  the  tricipital  brancli  of  the  posterior  circumflex 
artery.  The  importance  of  this  anastomosis  in  carrying  on  the  collateral  circula- 
tion after  ligature  of  the  third  part  of  the  axillary  artery  below  the  circumHex.  or 
the  brachial  above  the  profunda,  has  already  been  mentioned  (page  526). 

(6)  The  cutaneous  branch,  which  runs  with  the  external  cutanef)us  branch  of 
the  musculo-s])iral  nerve  to  supjily  the  skin  of  the  outer  side  of  the  arm. 

(c)  Tlie  articular  branch,  which  is  often  larger  than  the  continued  trunk  of  the 
superior  profunda  itself,  is  given  off  from  the  artery  just  before  it  ])erforates  the 
intermuscular  sei)tum.  runs  downwards  in  the  sub.stance  of  the  triceps  to  the  l)ack 
of  the  external  condyle,  Avhere  it  anastomoses  with  the  interosseous  recvuTent,  and 
forms  an  arterial  arch  bv  anastomosing  with  the  anastornotica  magna  across  tlie 
34  ■  " 


530  THE  ARTERIES 

back  of  the  lower  end  of  the  humerus  immediately  above  the  olecranon  fossa.    From 
this  arch  or  rete  small  twigs  enter  and  supply  the  elbow-joint. 

(d)  A  nutrient  artery  is  sometimes  given  to  the  upper  end  of  the  humerus. 

(e)  Muscular  branches  to  the  triceps. 

Chief  variations. — The  superior  profunda  may  arise  (a)  from  the  axillary  artery  iu  common 
with  one  or  more  branches  of  that  vessel  ;  or  (6)  as  a  common  trunk  with  the  inferior  profunda. 
(c)  It  may  give  off  the  posterior  circumflex,  which  then  runs  upwards  behind  the  teres  major  to 
reach  the  back  of  the  shoulder. 

(2)  The  Inferior  Profunda  Artery 

The  inferior  profunda  arises  from  the  inner  side  of  the  brachial,  usually  about 
the  level  of  the  insertion  of  the  coraco-brachialis,  at  times  as  a  common  trunk 
with  the  superior  profunda.  It  passes  with  the  ulnar  nerve  obliquely  downwards 
and  inwards  through  the  internal  intermuscular  septum,  and  then  along  the  inner 
head  of  the  triceps  to  the  back  of  the  internal  condyle  where,  under  cover  of  the 
deep  fascia  and  the  origin  of  the  flexor  carpi  ulnaris  from  the  olecranon  and  internal 
condyle,  it  anastomoses  with  the  posterior  ulnar  recurrent  and  anastomotica  magna 
arteries.  It  frequently  supplies  the  nutrient  artery  to  the  humerus.  It  gives 
branches  to  the  triceps,  to  the  elbow- joint,  and  a  branch  which  passes  in  front  of 
the  internal  condyle  to  anastomose  with  the  anterior  ulnar  recurrent. 

Chief  variations. — (1)  The  inferior  profunda  may  arise  (a)  with  the  superior  profunda  ;  (b) 
from  a  trunk  common  to  several  other  branches  of  the  axillary  and  brachial  arteries.  (2)  It  may 
be  absent,  its  place  being  taken  by  the  anastomotica  magna. 

(3)    The  Anastomotica  Magna  Artery 

The  anastomotica  magna  arises  from  the  inner  side  of  the  brachial,  about  two 
inches  above  its  bifurcation  into  the  radial  and  ulnar  arteries,  and,  running  down- 
wards and  inwards  across  the  brachialis  anticus,  divides  into  two  branches,  a  posterior 
and  an  anterior.  The  posterior  })ierces  the  internal  intermuscular  septum,  winds 
round  the  internal  condyloid  ridge  of  the  humerus,  and  pierces  the  triceps,  between 
which  and  the  bone  it  anastomoses  with  the  articular  branch  of  the  superior 
jH'ofunda  artery,  and  to  a  lesser  extent  with  the  interosseous  recurrent,  forming 
an  arterial  arch  or  rete  round  the  upper  l)order  of  the  olecranon  fossa.  The  anterior 
branch  passes  downwards  and  inwards  lietween  the  brachialis  anticus  and  pronator 
teres,  and  anastomoses  in  front  of  the  internal  condyle,  but  beneath  the  pronator 
teres,  with  the  anterior  ulnar  recurrent.  From  this  branch  a  small  vessel  passes 
down  behind  the  internal  condyle  to  anastomose  with  the  posterior  ulnar  recurrent 
and  inferior  profunda  arteries. 

Chief  variations. — (a)  The  anastomotica  magna  may  take  the  place  of  the  inferior  profunda. 
(b)  It  may  be  very  small,  the  inferior  profunda  taking  its  place. 

(4)  The  Nutrient  Artery  of  the  Humerus 

The  nutrient  artery  of  the  humerus  comes  off  from  the  brachial  about  the 
level  of  the  insertion  of  the  coraco-brachialis,  or  from  the  inferior  profunda,  or 
from  one  of  the  muscular  branches.  It  j^asses  obliquely  downwards  through  the 
nutrient  foramen,  and  on  entering  the  medullary  canal  of  the  humerus  divides  into 
an  ascending  and  a  descending  branch,  of  which  the  latter  is  the  larger. 

(5)  The  Muscular  Branches  of  the  Brachiai. 

The  muscular  branches  are  irregidar  in  their  number,  origin,  and  distribution. 
They  vary  from  about  live  to  eight,  usually  come  oft"  from  the  outer  ))ai't  of  the 
artery,  and  an^  distributed  to  the  coraco-brachialis,  bice])s,  and  brachialis  anticus 
muscles.  The  nutrient  artery  of  the  humerus  frequently  arises  from  the  upper- 
most muscular  branch. 


ULNAR  531 


THF   ULNAE  ARTERY 

The  ulnar  artery,  the  larger  of  the  two  ternimal  })ranches  of  the  brachial, 
begins  opposite  the  lower  border  of  the  head  of  the  radius  in  the  middle  line  of  the 
forearm.  Tlienee  through  the  upper  half  of  the  forearm  it  runs  in  a  slight  curve, 
with  its  convexity  inwards,  deeply  beneath  the  pronator  teres  and  superficial 
flexor  muscles,  and,  having  reached  the  ulnar  side  of  the  limb  about  midway 
l)etween  the  elbow  and  the  wrist,  it  passes  directly  doAvnwards,  being  merely  over- 
lapped by  the  flexor  carpi  ulnaris.  Crossing  the  annular  ligament  immediately  to 
the  radial  side  of  the  pisiform  bone,  it  enters  the  palm,  where  it  divides  into  two 
branches,  which  enter  respectively  into  the  formation  of  the  superficial  and  deep 
palmar  arches.  The  artery  is  accompanied  by  two  veins,  which  anastomose  with 
each  other  by  frequent  cross  l^ranches,  and  usually  terminate  in  the  l>rachial  vense 
comites;  or  sometimes  the  inner  vena  comes  ends  in  the  inner  brachial  vein,  the 
outer  vena  comes  in  the  median  profunda  vein.  The  ulnar  nerve  is  at  first  some 
distance  from  the  artery,  but  approaches  the  vessel  at  the  junction  (^f  its  upj^er  and 
middle  thirds,  and  then  lies  close  to  its  inner  or  ulnar  side.  The  course  of  the 
artery  in  the  lower  two-thirds  of  the  forearm  is  indicated  by  a  line  drawn  from  the 
front  of  the  internal  condyle  to  the  radial  side  of  the  pisiform  bone;  and  in  the 
upper  third  of  the  forearm  by  a  line  drawn  in  a  gentle  curve  with  its  convexity 
inwards  from  an  inch  below  the  centre  of  the  bend  of  the  elbow  to  a  point  in  the 
former  line  at  the  junction  of  its  upper  with  its  middle  third.  The  artery  through- 
out its  course  is  best  reached  through  the  innermost  intermuscular  septum,  i.e.  the 
interval  between  the  flexor  carpi  ulnaris  and  the  flexor  sublimis  digitorum. 

The  relations  of  the  artery  will  be  given  in  detail — as  it  lies  in  the  forearm,  at 
the  wrist,  and  in  the  palm  of  the  hand. 


I.   Relations  of  the  Ulnar  Artery  in  the  Forearm 

In  front. — In  the  upper  half  of  the  forearm  the  ulnar  artery  is  deei)ly  i)Iaced 
beneath  the  pronator  teres,  the  flexor  carpi  radialis,  the  palmaris  longus,  and  the 
flexor  sublimis  digitorum.  In  the  lower  half  it  is  comparatively  superficial,  Ijeing 
merely  overla])})ed  above  by  the  tendon  of  the  flexor  carjji  ulnaris,  whilst  the  last 
inch  or  so  of  the  vessel  is  only  covered  as  a  rule  by  the  skin  and  superficial  and 
deep  fasciae.  As  the  artery  lies  beneath  the  pronator  teres,  it  is  crossed  from 
within  outwards  by  the  mediari  nerve,  the  deep  head  of  origin  of  the  muscle 
usually  separating  the  nerve  from  the  artery.  The  lower  part  of  the  artery  is 
crossed  by  the  ])almar  cutaneous  branch  of  the  ulnar  nerve. 

Behind. — For  about  an  inch  of  its  course  the  artery  lies  upon  the  liracliialis 
antirus;  l)ut  thence,  as  far  as  the  anterior  annular  ligament  of  the  wrist,  u})on  the 
flexor  profundus  digitorum,  which  separates  it  above  from  the  interosseous  mem- 
brane and  bone,  and  at  the  wrist  from  the  pronator  quadra tus.  The  artery  is 
bound  down  to  the  flexor  profundus  digitorum  by  bands  of  fasciae. 

To  the  outer  side  in  the  lower  two-thirds  of  its  course  is  the  flexor  sublimis 
digitorum. 

To  the  inner  side  in  the  lower  two-thirds  is  the  flexor  carj»i  uhiaris.  the  guiile 
to  the  vessel.  The  ulnar  nerve,  as  it  enters  the  forearm  from  behind  the  inner 
condyle,  is  at  first  some  distance  from  the  artery,  being  sejiarated  from  it  in  its 
upper  third  l)y  the  flexor  sul)limis  digitorum,  but  in  its  lower  two-thirds  is  in  close 
contact  with  the  vessel  and  on  its  ulnar  side. 

Variations  of  the   llnar  Artcrj/  in  the  Forearm 

Tlio  principal  variations  of  the  ulnar  artery  in  the  forearm  are  :  (A)  It  may  arise  from  the 
brachial  alxivc  the  usual  ]i(iiiit  of  division  or  from  the  axillary,  in  wliicli  casi-  it  usually  lains  over 
the  flexor  muscles,  but  beneath  the  fascia,  to  reach  its  usual  situation  in  the  forearm.  Tlie  recur- 
rent arteries  and  the  common  iuterosseou.s  are  then  usually  derived  fnnu  the  trunk  ves.sel  from 


532 


THE  ARTERIES 


Fig.  35'2.— The  Arteries  of  the  Forearm  with  the  Superficial  Pai.^mak  Arch. 


Biceps 


Brachialis  antieuB 

Tendon  of  biceps 
Semilunar  fascia  of  bleeps 

R(u1l<il  rfcvrrenl  artery 
Supinator  longus 

RADIAL  SERVE 

Radial  artery 


Flexor  longus  pollicis 


Pronator  quadratus 

Radial  artery  winding  to  back  of 
vrisf  under  extensors  uf  thumb 


iiuperfieiales  vole 
Superficial  palmar  arch 


Brachial  artery 
Basilic  vein 

ULXAR  yERVE 

MEDIAX  yERVE 

Anasloniotica  magna 
Brachial  artery 

INTERNAL  CONDYLE 


Ulnar  artery 
-ii Pronator  radii  teres 

Flexor  sublimis  digitorum 
Flesor  carpi  radialis 
Palmaris  longus 

MED Uy  yERVE 
—   Flexor  sublimis  digitorum 
I'liiar  artery 

PISIFORM  BONE 

Anterior  annular  ligament 
Palmaris  brevis 


ULXAR  533 

which  the  uhiar  is  given  off.  At  times  it  runs  beneath  tlie  muscles,  or  merely  beneath  the  skin. 
(B)  It  may  in  some  cases  of  high  division  of  the  brachial  run  beneath  the  fascia  throughout  its 
whole  extent  in  the  forearm.  (C)  In  some  cases  of  normal  origin  from  the  brachial  it  takes  a 
.superficial  course  in  the  forearm,  being  merely  covered  by  the  fa.scia,  the  recurrent  branches  and 
the  common  interosseous  then  arising  from  the  radial. 

The  branches  of  the  ulnar  artery  in  the  forearm  are: — 1.  The  anterior 
uhiar  recurrent.  2.  The  posterior  uhiar  recurrent.  3.  The  interosseous,  or  com- 
mon interosseous:  (a)  anterior  interosseous — (i)  arteria  conies  nervi  mediani,  (ii) 
muscular,  (iii)  medullary,  (iv)  anterior  communicating;  (6)  posterior  interosse- 
ous— (i)  interosseous  recurrent,  (ii)  muscular,  (iii)  articular.  4.  Muscular.  5. 
Nutrient.     6.    Posterior  ulnar  carjnil.      7.   Anterior  ulnar  carpal. 

1 .  The  anterior  ulnar  recurrent  is  a  small  branch  which  leaves  the  inner  side 
of  the  ulnar  artery  soon  alter  its  origin,  and,  running  upwards  and  inwards  between 
the  outer  edge  of  the  pronator  teres  and  the  brachialis  anticus,  anastomoses  in 
front  of  the  internal  condyle  with  the  anastomotica  magna  and  a  branch  of  the 
inferior  ])rofunda  artery.  It  supplies  branches  to  the  muscles  between  which  it 
runs. 

2.  The  posterior  ulnar  recurrent,  larger  than  the  anterior  ulnar  recurrent, 
comes  off  from  the  inner  side  of  the  ulnar  artery,  either  a  little  below  the  latter 
branch,  or  else  as  a  common  trunk  with  it,  and,  passing  inwards  between  the  flexor 
sublimis  and  flexor  profundus  digitorum,  turns  upwards  to  the  back  of  the  internal 
condyle,  where  it  lies  with  the  ulnar  nerve  l)etween  the  two  heads  of  origin  of  the 
flexor  carpi  ulnaris.  It  supplies  the  contiguous  muscles — the  flexor  carpi  ulnaris. 
the  palmaris  longus,  and  the  flexor  sublimis  and  profundus  digitorum — the  elbow- 
joint  and  the  ulnar  nerve,  and  anastomoses  with  the  inferior  profunda,  Avith  the 
anastomotica  magna,  and  Avith  the  interosseous  recurrent,  forming  the  so-called  rete 
olecrani. 

3.  The  interosseous  or  common  interosseous  artery,  is  a  short  thick  trunk 
half  an  inch  or  so  in  length.  Avhich  comes  oft"  from  the  outer  and  back  part  of  the 
ulnar  artery  aljout  an  inch  from  its  origin,  and  just  before  that  artery  is  crossed  by 
the  median  nerve.  It  passes  backwards  and  downwards  between  the  flexor  longus 
pollicis  and  the  flexor  profundus  digitorum,  tOAvards  the  triangular  interval 
bounded  by  the  upper  border  of  the  interosseous  membrane,  the  oblique  ligament, 
and  the  outer  border  of  the  ulna.  Avhere  it  divides  into  the  anterior  and  posterior 
interosseous  arteries. 

(a)  The  anterior  interosseous  artery,  smaller  than  the  posterior,  but  appar- 
ently the  direct  continuation  of  the  c(jmmon  trunk,  courses  cloAvnAvards  in  front  of  the 
interosseous  membrane,  upon  Avhich  it  lies  under  cover  of  the  overlapping  edges  of 
the  flexor  profundus  digitorum  and  flexor  longus  pollicis,  to  the  upper  border  of  the 
pronator  (juadratus,  Avhere  it  terminates  in  two  branches,  an  anterior  terminal  and 
a  posterior  terminal. 

The  anterior  interosseous  artery  is  accompanied  by  two  veins  and  by  the  deep 
branch  of  the  median  nerve  Avhich  lies  to  its  radial  side.  The  artery  is  bound  down 
to  the  inter(.)sseous  membrane  l)y  ajioneurotic  fibres. 

The  branches  of  the  anterior  interosseous  artery  are: — (1)  The  arteria 
comes  nervi  mediani — or  the  median  artery  as  it  is  sometimes  shortly  called — is 
a  long  slender  vessel,  Avhich  arises  from  the  anterior  interosseous  immediately  after 
the  latter  is  given  oft'  from  the  common  trunk.  It  ]iasses  forAvards  betAveen  the 
flexor  profundus  digitorum  and  the  flexor  longus  pollicis  to  the  median  nerA'e,  Avith 
AA'hich  it  descends  beneath  the  amiular  ligament  into  the  palm,  and  Avhen  of  large 
size  sometimes  enters  into  the  formation  of  the  superficial  palmar  arch.  At  times 
the  artery  arises  from  the  connnon  interosseous  before  its  division,  (h)  Muscular 
branches  supply  the  flexor  longus  pollicis,  flexor  profundus  digitorum,  and  pro- 
nator quadratus,  and  the  extensor  muscles  of  the  thumb,  which  they  reach  by 
passing  baclcAvards  through  the  interosseous  membrane,  (iii)  The  nutrient 
arteries  of  the  radius  and  ulna  are  usualh'  deriA-ed  from  this  vessel,  (iv)  The 
anterior  terminal  and  smaller  division  of  the  anterior  interosseous  artery,  some- 
times called  tlie  anterior  coimnunicating,  passes  either  in  front  of  or  behind  the 
pronator  quadratus,  but  in  either  case  in  front  of  the  interosseous  membrane,  and 
anastomoses  with  the  anterior  carpal  branches  of  the  radial  and  ulnar  arteries,  and 


534 


thp:  arteries 


with  the  recurront  hranches  from  the  deep  pahnar  arch,  forming  the  so-called 
anterior  carpal  rete.  (  v)  The  posterior  terminal  and  larger  division  pierces 
the  interosseous  membrane,  and  continues  its  course  downwards  behind  the  inter- 
osseous membrane,  under  cover  of  the  extensor  muscles,  to  the  back  of  the  wrist, 
where  it  ends  by  anastomosing  with  the  posterior  carpal  branches  of  the  radial  and 

Fig.  353.— The  Back  of  the  Left  Forearm,  with  the   Posterior   Ixterosseovs  Artery 
AXD  Branches  of  the  Kadial  at  the  Back  of  the  Wrist. 

(From  a  dissection  in  the  Hunterian  Museum.) 


Articular  branch  of  superior 
profunda 

Brachialis  antieus 
Supinator  longus,  cut 


Common  extensor  tendon 


Extensor  earpi  radialis  longior 
and  brevior 


Supinator  brevis 


Poslerior  interosseous  artery 


Extensor  ossis  metaearpi  pollieis 
Supinator  longus,  cut 

Extensor  primi  internodii  pollieis 


Posterior  annular  ligament 

Extensor  earpi  radialis  longior 

Radial  artery 

Ddrsalis  pollieis  artery 

Extensor  secundi  internodii 

pollieis 

First  dorsal  interosseous  muscle 

Dorsalis  indicts  artery 

Princeps  pollieis  artery 


Dorsal  digital  artery 


Triceps 


Rete  over  olecranon 
Interosseous  recurrent  artery 

Anconeus,  cut 


Extensor  carpi  uluaris 
Flexor  carpi  ulnaris 


Origin  of  extensor  secundi  and 
indicator 


Posterior  brancfi  of  anterior  interosseous 

artery 
Interosseous  membrane 


Posterior  ulnar  carpal  artery 
Extensor  carpi  radialis  brevier 

Posterior  radial  carpal  artery 

Third  dorsal  interosseous  artery 
Second  dorsal  interosseous  artery 
Metacarpal  or  first  dorsal  interosseous 
artery 


ulnar  arteries,  forming  the  so-called  posterior  carpal  rete.  This  branch  anas- 
tomoses, as  soon  as  it  pierces  the  interosseous  niemljrane,  with  the  posterior 
interosseous  artery. 

(h)  The  posterior  interosseous  artery,  the  larger  division  of  the  common 
interosseous,   turns    backwards  through    the  triangular   interval   bounded    b}-  the 


ULNAR  535 

interosseous  niemltrane  below,  the  i)l)li(|iK'  liganu'iit  above,  and  tlie  ubia  internally, 
and,  emerging  at  the  back  of  the  forearm  between  the  extensor  ossis  metacarpi 
})oIlicis  and  the  supinator  l»revis,  under  cover  of  the  superficial  extensors  of  the 
forearm,  descends  between  the  superficial  and  the  deej)  muscles,  crossing  in  this 
course  the  extensor  ossis  metacarpi  pollicis,  the  extensor  primi  internodii  pollicis, 
the  extensor  secundi  internodii  pollicis,  and  the  indicator  (fig.  353).  It  anasto- 
moses at  the  lower  border  of  this  muscle  with  the  anterior  interosseous,  or  with  the 
l>osterior  Ijranch  of  the  anterior  interosseous  which  here,  as  above  described,  has 
l)erforated  the  interosseous  membrane.  It  is  separated  from  the  nerve  of  the  same 
name  at  first  V)y  the  radius  and  supinator  brevis  and  on  the  back  of  the  forearm  by 
the  extensores  secundi  internodii  pollicis  and  indicis. 

It  gives  off  the  following  l)ranches: — (i)  The  interosseous  recurrent,  or  pos- 
terior interosseous  recurrent  (fig.  353),  arises  from  the  posterior  interosseous  as 
tlie  latter  emerges  from  l)eneath  the  supinator  brevis.  It  runs  upwards  between 
the  anconeus  and  supinator  brevis,  usually  under  cover  of  the  former,  to  the  inter- 
val l)etween  the  external  condyle  and  the  olecranon,  where  it  anastomoses  Avith  the 
superior  profunda,  anastomotica  magna,  radial  recurrent,  and  posterior  ulnar 
recurrent  arteries,  and  gives  i>ranches  to  the  retiform  plexus  over  the  olecra- 
non— the  rete  olecrani.  (ii)  Muscular  branches  are  given  off  to  the  superficial 
and  deep  extensor  muscles,  (iii;  Articular  branches  enter  the  back  of  the 
wrist-joint. 

4.  The  muscular  branches  of  the  ulnar  artery  supply  the  contiguous 
nuiscles,  and  are  varial»le  in  numl)er,  origin,  and  distribution. 

5.  The  nutrient  artery  of  the  ulna  may  be  given  of?  from  the  main  trunk  of 
the  ulnar  artery,  or  from  one  of  its  muscular  branches,  or  from  the  anterior  inter- 
osseous artery. 

6.  The  posterior  ulnar  carpal  comes  of?  from  the  ulnar  artery  a  little  above 
the  anterior  annular  ligament,  and,  winding  inwards  round  the  end  of  the  vilna 
(»r  the  internal  lateral  ligament  of  the  wrist,  beneath  the  flexor  carpi  ulnaris, 
ramifies  on  the  l)ack  of  the  carpus  beneath  the  extensor  tendons.  It  forms  by 
its  anastomosis  with  the  posterior  radial  carpal  and  with  the  pjosterior  branch  of 
the  anterior  interosseous  and  with  the  posterior  interosseous  arteries,  a  plexus  or 
rete,  the  so-called  posterior  carpal  arch.  The  branches  given  off  from  this  plexus 
or  arch  are  described  with  the  posterior  carpal  branch  of  the  radial  arterv  (page 
541). 

7.  The  anterior  ulnar  carpal  is  a  small  branch  given  off  from  the  ulnar  arterv 
opposite  the  car})us.  It  passes  lieneath  the  flexor  profundus  digitorum  to  anasto- 
mose with  the  anterior  radial  carjjal,  with  terminal  twigs  of  the  anterior  branch  of 
the  anterior  interosseous,  and  with  recurrent  branches  from  the  deep  palmar  arch, 
forming  an  anastomotic  arch  across  the  front  of  the  carpus — the  so-called  anterior 
carpal  arch  or  rete. 

II.   Relations  of  the  Ulnar  Artery  at  the  Wrist 

The  ulnar  artery  at  the  wrist  may  be  said  to  extend  from  the  upper  to  the 
lower  border  of  the  anterior  aimular  ligament.  It  here  lies  immediately  to  the 
radial  side  of  the  pisiform  bone,  and  to  the  ulnar  side  of  the  hook  of  the  unciform, 
the  two  bones  forming  for  the  vessel  a  protecting  channel,  which  is  further  converted 
into  a  short  canal  by  the  expansion  of  the  flexor  carjn  ulnaris  passing  from  the 
])isiform  to  the  hook  of  the  unciform.  The  ulnar  nerve  in  this  situation  is  imme- 
diately to  the  ulnar  side  of  the  arterv. 

Relations. — In  front  it  has.  in  addition  to  the  expansion  aliove  menticnied. 
the  skin  and  superficial  fascia;  below,  it  rests  on  the  annular  ligament;  inter- 
nally are  the  ulnar  nerve  and  })isitorm  bone:  externally,  the  hook  of  the  unci- 
form. 

The  ulnar  artery  gives  off  no  named  branch  in  this  part  of  its  course. 


536 


THE  AUTKRIES 


III.     IvELATK)NS    f)F    THE    UlNAR    ArtERY    IX    THE    PaLM 

(Superficial  Palmar  Arch) 

Tlie  ulnar  artery,  on  entering  the  palm,  divides  into  t\vol)ranches,  the  superficial 
and  deep. 

The  superficial  branch  (fig.  354),  the  direct  continuation  of  the  vessel,  anast<v 
moses  with  the  superficial  volar,  a  hranch  of  the  radial,  forming  what  is  then  known 


Fig.  354.— Anastomoses  and  Distributiux  of  the  Arteries  of  the  Hand.     (WaLsham.) 

7 


Anterior  interosseous 

Radial  artery 

Anterior  radial  carpal 


Superfciat  rolar 
Posterior  radial  carjial 
Radial  artery  at  urisl 


Dorsalis  pollicis 

Metacarpal  or 

first  dorsal 

interosseous 

Princeps  pollicis 

Dorsalis  indicis 
Radialis  indicis 


First  dorsal  branrh  of  collalpral 
digital 


Second  dorsal  branch  of  collateral 
digital 


Anastomosti  of  collateral  digital 
arteries  about  matrix  of  nail 
and  pulp  of  finger 


Ulnar  artery 

Anterior  ulnar 
carpal 

Posterior  ulnar 
carpal 


Deep  ulnar 
Superficial  arch 

Carpal  recurrent 

Posterior  communi- 
cating or  perforat- 
ing 

Palmar  interosseous 

Second,  third,  and 
fourth  jialniar 
digital 

Second  and  third 
dorsal  interosseous 

First  jialmar  digital 


Anterior  commuiii- 
cating  or  perforat- 
ing 


as  the  superficial  palmar  arch.  After  descending  a  short  distance  towards  the 
cleft  between  the  fourth  and  lifth  fingers,  it  turns  outwards  towards  the  thumh, 
forming  a  curve  witii  its  convexity  towards  the  fingers  and  its  concavity  towards 
the  muscles  of  the  thuml),  and  anastomoses  o])])()site  the  cleft  hetween  the  index 
and  middle  fingers,  at  tlie  junction  of  the  upjier  with  the  middle  third  of  the  palm, 
with  the  sup(Tficial  volar  hranch  of  the  radial  artery  to  complete  th(>  arch.  A  line 
drawn  across  the  ])alm  on  a  level  with  the  thumb  at  a  right  angle  to  the  hand  will 
roughly  indicate  the  situation  of  the  arch. 


ULNAR 


537 


Relations. — In  front :  in  addition  to  the  skin  and  superficial  fascia,  the  vessel 
is  crossed  successively,  from  witliin  outwards,  by  the  palmaris  breyis,  the  palmar 
branch  of  the  ulnar  nerye,  the  i)a]mar  fascia,  and  the  palmar  branch  of  the  median 
nerve. 

Behind,  it  rests  u))on,  from  within  outwards,  the  short  muscles  of  the  little 
finger,  the  digital  branches  of  the  ulnar  nerve,  the  flexor  tendons,  and  the  digital 
branches  of  the  median  nerve. 

Fig.  0.55.— The  Akteriks  of  the  Kight  Fore.\rm  and  the  Deep  Palmar  Arch. 


Inferior  profunda  artery 
Aiiastoiiiolico  magna  artery 


Brachial  artery 
Radial  recurrent  artery  . 


Supinator  longus 


Radial  artery. 


Flexor  longus  pollicis  muBcle 


b 


■Braehialis  autieus  muscle 
Anterior  ulnar  recurrent 
I'otiterior  ulnar  recurrent 


-l-'lnar  artery 

.\  liter  lor  interosseous  artery 
Flexor  carpi  ulnaris 

Flexor  profundus  digitorum  muscle 
.  Anterior  interosseous  artery 


Anterior  annular  ligament,  cut - 


Anterior  branch  of  ulnar  artery,  cut 
Deep  palmar  arch 


Collateral  branch  of  palmar  digital  artery 


^ps 


^.-^. 


w 


w 


Palmar  iiiterosseotis  arteries 
Palmar  digital  artery,  cut  short 


Variatioii.i  in  the  Superjicial   Palmar  Anli 

The  superficial  palmar  arch  is  very  .subject  tn  variations.  (A)  It  may  be  formed  by  the 
superficial  branch  of  the  ulnar  ana.«;toni()siiiir  witli  the  radialis  indicis.  or  witli  the  radial  in  the 
palm  instead  of  with  the  supei-ficial  volar  branch  of  the  radial.  (B)  The  superficial  volar  may  be 
larger  than  usual,  and  take  a  s^reater  share  than  the  ulnar  in  the  formaticm  of  the  arch.  (C)  The, 
arch  may  be  reinforced  by  a  large  median  artery,  or  by  an  enlarged  intero.sseous  artery.  (D)  The 
arch  may  be  double,  both  the  superficial  branch  of  the  ulnar  and  the  superficial  volar  dividing 


538  THE  ARTERIES 

into  two  branches  which  anastomose  across  the  palm.  (E)  The  arteries  of  the  thumb  and  radial 
side  of  the  index  linger  may  be  jriven  oflF  from  the  arch.  (F)  The  arch  may  be  incomplete,  the 
inner  digital  branches  coming  off  from  the  ulnar,  and  tlie  outer  from  the  superficial  volar,  the 
radial  in  the  palm  or  an  enlarged  median  artery.  (G)  The  arch  may  be  absent,  the  lateral  digital 
arteries  being  then  given  off  from  enlarged  interosseous  arteries  from  the  deep  arch,  or  fiom 
enlarged  dorsal  interosseous  arteries. 

The  branches  of  the  superficial  palmar  arch  are: — (1)  The  four  digital 
arteries;  (2j  the  inu.<(ul;ir:  and  (3)  the  cutaneous. 

(1)  The  digital  arteries,  usually  four  in  number,  are  given  off  from  the  con- 
vexity of  the  superticial  arch  and,  running  downwards  through  the  palm,  supply 
both  sides  of  the  little,  ring,  and  middle  lingers,  and  the  ulnar  side  of  the  index 
finger.  The  radial  side  of  the  index  finger  and  the  thumb  are  supplied  respectively 
by  the  radialis  indicis  and  princeps  pollicis,  branches  of  the  radial  artery.  The 
digital  arteries  are  named,  from  within  outwards — first,  second,  third,  and  fourtli. 
The  first  digital  artery  runs  downwards  and  iuAvards  over  the  muscles  on  the  inner 
side  of  the  palm,  and  thence  along  the  ulnar  side  of  the  little  finger.  It  gives 
branches  to  the  abductor,  flexor  brevis,  and  opponens  minimi  digiti  muscles.  This 
branch  sometimes  comes  from  the  deep  Ijranch  of  the  ulnar  artery.  The  second, 
third,  and  fourth  digital  arteries  run  downwards  in  the  interspace  between  the 
little  and  ring,  the  ring  and  middle,  and  the  middle  and  index  fingers  respectively, 
to  within  about  a  quarter  of  an  inch  of  the  clefts  Ijetween  the  fingers,  where  they 
divide  into  two  branches  (collateral  digital)  for  the  supply  of  the  sides  of  the 
contiguous  fingers.  As  the  digital  arteries  pass  through  the  palm,  they  lie  between 
the  flexor  tendons,  on  the  digital  nerves  and  lumbrical  muscles,  and  beneath  the 
palmar  fascia.  Just  before  bifurcating  they  pass  under  the  superficial  transverse 
ligament,  and  are  joined  by  the  palmar  interosseous  branches  from  the  deep  palmar 
arch  (fig.  354).  At  this  spot  they  also  receive  the  anterior  perforating  branches 
from  the  dorsal  interosseous  vessels.  On  the  sides  of  the  fingers  the  collateral 
digital  arteries  lie  between  the  palmar  and  dorsal  digital  nerves.  They  anastomose 
by  small  branches,  forming  an  arch  across  the  front  of  the  bones  on  the  proximal 
side  of  each  interphalangeal  joint.  They  supply  the  flexor  tendons  and  the  integu- 
ments, and  terminate  in  a  plexiform  manner  beneath  the  pulp  of  the  finger  and 
around  the  matrix  of  the  nail.  A  dorsal  digital  branch  is  given  off  to  the  back  of 
the  fingers  about  the  level  of  the  middle  of  the  first  phalanx,  and  a  second  but 
smaller  dorsal  digital  branch  about  the  level  of  the  middle  of  the  second  phalanx. 

(2)  The  muscular  branches  from  the  superficial  arch  are  very  small  and 
supply  the  superficial  muscles. 

(3)  The  cutaneous  branches  supply  the  integuments  of  the  palm. 

The  deep  branch  of  the  ulnar  arter}',  also  called  the  communicating  artery, 
sinks  deeply  into  the  palm  between  the  abductor  and  flexor  brevis  minimi  digiti, 
and  joins  the  radial  to  form  the  deep  palmar  arch.  (See  The  Radial  ARTf:RV. 
page  543. ) 

THE  RADIAL  ARTERY 

The  radial  artery — the  smaller  of  the  two  arteries  into  which  the  brachial 
divides  at  the  bend  of  the  elbow — appears  as  the  direct  continuation  of  the  brachial. 
It  runs  downwards  and  outwards  along  the  radial  side  of  the  forearm  as  far  as  the 
styloid  process,  then,  coiling  over  the  external  lateral  ligament  and  outer  and  back 
part  of  the  wrist,  enters  the  palm  of  the  hand  from  behind  between  the  first  and 
second  metacarpal  bones,  and  ends  by  anastomosing  with  the  dee})  l)ranch  of  the 
ulnar  to  form  the  deep  palmar  arch.  Hence  the  artery  is  divisible  into  three  parts: 
that  in  the  forearm,  that  at  the  wrist,  and  that  in  the  palm  of  the  hand.  The 
course  of  the  artery  is  indicated  by  a  line  drawn  from  a  point  one  inch  below  the 
centre  of  the  elbow  to  a  ])()int  situated  half  an  inch  internal  to  the  styloid  process 
of  the  radius. 

I.  The  Radial  Artery  in  the  Forearm 

In  its  course  through  the  forearm  (fig.  351)  the  radial  artery  is  found  in  the 
outermost  intermuscular  space,  and  it  is  only  necessary  to  divide  the  skin,  super- 


RADIAL 


539 


ficial  and  deep  fascia,  to  expose  the  vessel,  and  in  addition  in  the  upper  third  to 
S('i»arate  the  supinator  longus  (huniero-radialis)  from  the  pronator  radii  teres. 

In  front,  tlie  artery  is  at  first  overlapped  by  the  supinator  longus,  but  for  the 
rest  of  its  course  it  is  niereh'  covered  by  the  skin,  superficial  and  deep  fasciae,  by 
some  cutaneous  veins,  and  by  cutaneous  branches  of  the  musculo-cutaneous  nerve. 

Behind,  it  lies  successively  from  above  downwards  on  the  tendon  of  the  l)iceps, 
the  supinator  brevis,  from  which  it  is  separated  by  a  layer  of  fat,  the  insertion  of 
the  pronator  radii  teres,  the  radial  origin  of  the  flexor  sublimis  digitorum,  the  flexor 

Fig.  :io6. — Diagram  of  the  Relation  of  the  Arteries  of  the  Left  Forearm  to 

THE  Boxes.     (Walsham.) 


Inferior  profunda  artery 
Brachial  artery 


Anastomotica  mufftia  artery 

Anterior  ulnar  recurrent 
Posterior  ulnar  recurrent 

Ulnar  artery 

Common  interosseoi^ artery 


A  nterior  interosseous  arteru 


Anterior  ulnar  carpal 

Superficial  branch  of  ulnar  artery 
(superficial palmar  arch) 

First  palmar  digital  artery 


Superior  profunda  artery 


EXTERNAL  CONDYLE 


-i. Articular 


branch  of  superior 
profunda  artery 

Radial  recurrent  artery 
Interosseous  recurrent  artery 

Radial  artery 
Oblique  ligament 

Interosseous  membrane 
Posterior  interosseous  artery 


Anterior  radial  carpal 

Radial  artery  at  wrist 

Superficial  volar  branch  of 
radial  artery 


Deep  palniur  arch 


longus  pollicis,  the  pronator  quadratus,  and  the  front  surface  of  the  lower  end  of 
the  radius.  It  is  in  this  last  situation,  where  the  artery  lies  upon  the  bone  and  can 
therefore  be  easily  pressed  against  it,  that  the  pulse  is  usually  felt. 

On  its  outer  side  it  has,  throughout  the  whole  of  its  course,  the  supinator 
longus  or  humero-radialis  muscle,  the  guide  to  the  artery  in  ligature,  and  the 
external  vena  comes;  in  its  middle  third,  the  radial  nerve  as  well.  In  its  lower 
third  the  radial  nerve  is  to  its  outer  side,  but  separated  from  it  by  the  supinator 
longus  and  fascia. 

On  its  inner  side,  in  the  upper  third  is  the  pronator  radii  teres,  in  the  lower 


540 


THE  AUTKRTES 


third  the  tendon  of  the  flexor  carpi  radialis,  and  throughout  the  -whole  of  its  course 
the  internal  vena  comes. 

Variations  in  the  Radial  Artery  in  the  Forearm 

(A)  The  radial  artery  may  be  given  off  from  the  brachial  higher  than  usual,  or  from  the 
axillary  artery.  (B)  It  may  arise  from  the  brachial  lower  than  the  bend  of  the  elbow,  but  a  low 
division  of  the  brachial  is  rare.  (C)  It  may  run  superficial  to  the  fascia  of  the  forearm.  (I))  It 
may  cross  over,  instead  of  under,  the  extensors  of  the  thumb.  (E)  It  may  terminate  in  the 
forearm  or  be  absent,  its  place  in  tlie  forearm  and  hand  being  then  supplied  by  the  ulnar, 
the  anterior  interosseous,  or  an  enlarged  median  artery.  (F)  It  may  be  joined  by  a  vas  aberrans 
liom  the  brachial  or  axillary  artery. 


Fig.  357. — The  Bend  of  the  Ei-bow,  Left  Side. 
(From  a  dissection  l>y  Dr.  Alder  Smith  in  the  Museum  of  St.  Bartholomew's  Hospital.) 


MEDIAN  NERVE 

Posti-.rior  branch  0/ 

anastomotica  magna 

BRANCHES  OF      ( 

INTERNAL  CUTA-J 

NEOUS  NERVE      ( 

Posterior  ulnar  vein 

BrachialiB  antieus 

Anteriiir  hrtinch  of 
anastomotica  magna 
Anterior  ulnar  vein 

Median  basilic  vein 

MUSCULAR  BRANCH 
OF  MEDIAN  NERVE 

Tendon  of  biceps 
Bicipital  fascia 


BrachialiB  antieus 

Deep  median  vein 

Ulnar  artery 


Pronator  teres 


Radial  arterii 


Biceps 

Internal  vena 
comes  of 
brachial  artery 
Basilic  vein 

Brachialis 
antieus 

Cephalic  vein 

Brachial  artery 
EXTERNAL 
CUTANEOUS 

NER  VE 
Miisciilo-spiral 
n.  and  ascending 
branch  of  radial 
recurrent  artery 
Radial  vein 
Median  cephalic 

vein 
Ascending  br.  of 
radial  recurrent 
RADIAL 

NERVE 

Radial  recurrent 

artery 
Supinator 

longus 
Drxcnuling  hr. 

of  nidial 

recurrent 
Median  vein 


RADIAL 
NERVE 


The  branches  of  the  radial  artery  in  the  forearm  are  : — (1)  The  radial  re- 
current; ('2)  the  muscular;  (o)  the  anterior  radial  car])al;  (4)  the  BU})erficial 
volar. 

(1)  The  radial  recurrent  usually  arises  from  the  outer  side  of  the  radial  just 
helow  its  origin  from  the  brachial.  It  at  first  runs  outwards  on  the  su])inator 
brevis,  and  then  divides  into  three  chief  branches  (fig.  357).  One  of  these  runs 
transversely  outwards  through  the  fibres  of  the  musculo-spiral  nerve,  or  between 
the  radial  and  posterior  interosseous  nerves  when  the  musculo-si)iral  divides  higher 


RADIAL   AT  THE   WRIST  541 

than  usual,  into  the  supinator  lonjjjus  and  pxtcnsor  carpi  radialis  longior  and 
brevior,  and  anastomoses  with  tlie  interosseous  recurrent.  A  second  ascends  he- 
tAveen  the  l)rachiahs  anticus  and  supinator  longus,  with  the  nnisculo-spiral  nerve, 
and  anastomoses  with  the  superior  profunda  artery.  A  third  descencls  with  the 
radial  nerve  under  cover  of  the  sujnnator  longus  su])plying  that  muscle.  The  radial 
recurrent  also  gives  off  brandies  to  the  elbow-joint. 

(2)  The  muscular  branches  of  the  radial  artery  come  off  irregularly  to 
sui)ply  the  contiguous  muscles  on  the  outer  side  of  the  forearm. 

(3)  The  anterior  radial  carpal  arises  from  the  inner  side  of  the  radial  artery 
about  the  level  of  the  lower  l)order  of  the  pronator  quadratus.  It  crosses  the  front 
of  the  radius  beneath  the  flexor  muscles,  and  anastomoses  with  the  anterior  carpal 
branch  of  the  ulnar,  forming  what  is  sometimes  called  the  anterior  carpal  arch;  or 
Avhat  is,  more  properly  speaking,  an  arterial  plexus  or  rete — the  anterior  carpal 
rete.  This  plexus  is  joined  aljove  by  small  twigs  from  the  anterior  interosseous 
artery,  and  below  by  recurrent  branches  from  the  deep  palmar  arch.  It  supplies 
branches  to  the  lower  end  of  the  radius,  and  to  the  Avrist  and  carpal  joints. 

(4)  The  superficial  volar  leaves  the  radial  artery  as  the  latter  vessel  is  about 
to  turn  over  the  external  lateral  ligament  to  the  back  of  the  wrist.  It  courses 
forwards  over  the  short  muscles  of  the  ball  of  the  thumb,  and  anastomoses  with 
the  superficial  branch  of  the  ulnar  artery  to  com})lete  the  superficial  palmar  arch. 
It  su))plies  small  branches  to  the  muscles  of  the  ball  of  the  thumb,  and  at  times 
terminates  in  these  muscles  without  joining  the  arch.  Occasionally  it  passes  beneath 
the  abductor  pollicis.  This  brancli  is  often  small  and  ends  in  the  muscles  of  the 
thumb. 

II.  The  Radial  Artery  at  the  Wrist 

The  radial  artery  at  the  wrist  winds  over  the  outer  side  of  the  carpjus,  under  the 
extensor  tendons  of  the  thumb,  from  a  spot  a  little  below  and  internal  to  the  styloid 
]jrocess  of  the  radius  to  the  base  of  the  first  interosseous  space,  where  it  sinks 
ijetween  the  two  heads  of  the  abductor  indicis  into  the  palm,  to  form,  by  anasto- 
mosing with  the  deep  branch  of  the  ulnar  artery,  the  deep  palmar  arch.  A  line 
drawn  from  half  an  inch  internal  to  the  styloid  process  to  the  base  of  the  first  inter- 
(jsseous  space,  which  can  be  distincth'  felt  on  the  back  of  the  hand,  will  roughly 
indicate  the  course  of  the  artery. 

Relations. — The  artery  is  covered  successively  by  the  extensor  ossis  metacarpi 
pollicis  and  extensor  jirimi  internodii  pollicis,  by  branches  of  the  radial  nerve  and 
su])erficial  radial  veins,  and,  just  before  it  sinks  between  the  two  heads  of  the 
abductor  indicis,  by  the  tendon  of  the  extensor  secundi  internodii  pjollicis.  The 
branches  of  the  radial  nerve  to  the  thumb  and  index  finger  cross  it.  It  is  at  first 
somewhat  deeply  placed  beneath  the  first-mentioned  extensor  muscles  of  the  thumb; 
but  sul)se(]uently  it  lies  quite  superficial,  and  can  be  felt  pulsating  in  a  little  trian- 
gular depression  bounded  on  either  side  by  the  extensor  ynimi  and  extensor  secundi 
internodii  p>ollicis,  and  above  by  the  lower  end  of  the  radius.  The  artery  lies  suc- 
cessively on  the  external  lateral  ligament  of  the  Avrist,  on  the  scai)hoid,  the  trape- 
zium, the  base  of  the  fii'st  metacarpal  bone,  and  on  the  dorsal  ligaments  uniting 
these  bones.  It  has  usually  with  it  two  comj)anion  veins,  and  a  few  ])ranches  of 
the  musculo-cutaneous  nerve. 

The  branches  of  the  radial  artery  at  the  wrist  arc: — (1)  The  posterior  radial 
car})al;  (2)  the  metacarpal,  or  the  first  dorsal  interosseous;  (3)  thedorsalis  pollici.':. 
or  dorsal  artery  of  the  thumb;  and  (4)  the  dorsalis  indicis,  or  dorsal  digital  artery 
of  the  first  finger. 

(1)  The  posterior  radial  carpal  arises  from  the  radial  as  the  latter  vessel 
passes  under  the  extensor  ossis  metacarpi  pollicis,  and  runs  inwards  l)eneath  the 
extensor  carpi  radialis  longior  and  brevior,  and  the  extensor  secundi  internodii 
pollicis,  across  the  back  of  the  carpus,  to  anastomose  with  the  posterior  ulnar  car] >al 
and  with  the  terminal  twigs  of  the  posterior  branch  of  the  anterior  interosseous 
artery.  This  anastomosis  is  called  the  ]iosterior  carpal  arch,  or  jiosterior  carpal 
rete.  The  two  following  named  branches  are  given  off  from  this  an^h  or  rete: — 
(a)  The  second  and  (b)  the  third  dorsal  interosseous  arteries  to  the  third 
and  fourth  spaces  respectively.      These  vessels  run  downwards  on   the  dorsal  inter- 


542 


THE  ARTERIES 


osseous  muscles  as  far  as  the  flexure  of  the  fingers,  and  there  divide  into  two 
hranches  (dorsal  digital),  which  run  along  the  sides  of  the  contiguous  fingers  on 
their  dorsal  aspect.  Near  their  proximal  ends  they  anastomose  with  the  posterior 
perforating  branches  of  the  deep  palmar  arch.  Distally  they  are  connected  by 
anterior  perforating  branches  with  the  digital  arteries  of  the  corresponding  spaces. 


Fig.  358. — The  Radial  Arteky  at  the  Wrist,  Left  Forear.m. 
^Fiom  a  dissectiou  in  the  Hunterian  Mu.seum.) 


Articular  branch  of  super wr 
prnfunda 

Brachialis  auticus 
Supinator  lougus,  cut 


Common  extensor  tendon 


Extensor  carpi  radialis  longior 
and  brevior 


Supinator  brevis 


Posterior  interosseous  artery 


Extensor  ossis  metacarpi  poUiois 
Supinator  longus,  cut 

Extensor  primi  interuodii  poUicis 


Posterior  annular  ligament 

Extensor  carpi  radialis  longior 

Badial  artery 

Boj-salis  poinds  artery 

Extensor  seeundi  internodii 

poUicis 

First  dorsal  interosseous  muscle 

Dorsalis  indicia  artery 

Princeps  poUicis  artery 


Dorsal  digital  artery 


Triceps 


Rete  over  olecranon 
Interosseous  recurrent  artery 

Anconeus,  cut 


Extensor  carpi  ulnaris 
Flexor  carpi  ulnaris 


Posterior  liranch  of  anterior  interosseous 

Wl  artery 


Interosseous  membrane 


Posterior  ulnar  carpal  artery 
Extensor  carpi  radialis  brevior 
Posterior  radial  carpal  artery 

Third  dorsal  interosseous  artery 
Second  dorsal  interosseous  artery 
Metacaipal  or  first  dorsal  interosseous 
artery 


The  branches  which  run  along  the  backs  of  tin-  fingers  anastomose  witli  tlie  dorsal 
branches  of  the  collateral  diirital  arteries  derived  from  the  palmar  digital  vessels 
(%  359). 

(2)  The  metacarpal  or  first  dorsal  interosseous  artery  (figs.  358,  859) 
arises  from  the  radial  artery  beneath  the  extensor  seeundi  internodii  ])ollicis,  and, 
crossing   the   second    metacarpal    ])one,    i)asses   downwards  on  the  seetnid    dorsal 


DEEP  PALMAR   ARfH  543 

interosseous  muscle  between  the  extensor  tendons  to  the  level  of  the  metacarpo- 
phalangeal joint,  Avhere  it  divides  into  two  small  branches,  like  the  other  dorsal 
interosseous  arteries,  for  the  sui)ply  of  the  sides  of  the  contiguous  fingers  on  their 
dorsal  aspect.  At  the  base  of  the  second  interosseous  space  it  communicates  with 
the  posterior  perforating  branch  of  the  deep  arch,  which  here  runs  ))ackwards 
between  the  heads  of  the  second  dorsal  interosseous  muscle,  and  at  the  fore  part  of 
the  space  it  anastomoses  through  the  anterior  perforating  brancli  with  the  fourth 
digital  artery. 

The  dorsal  digital  arteries,  the  terminations  of  the  metacarpal  artery  and 
dorsal  interosseous  arteries,  extend  along  the  sides  of  the  fingers  as  far  as  the  first 
inter})halangeal  joint,  where  they  anastomose  with  the  dorsal  l^ranches  of  the  col- 
lateral digital  arteries. 

(8)  The  dorsalis  pollicis  arises  from  the  radial  just  before  it  sinks  between 
the  two  heads  of  the  first  dorsal  interosseous  muscle.  It  runs  downwards  on  the 
ulnar  side  of  the  extensor  secundi  internodii  pollicis,  along  the  metacarpal  l:)one, 
and  divides  into  two  branches  for  the  supply  of  the  radial  and  ulnar  side  of  the 
thumb  on  its  dorsal  aspect.  These  branches  sometimes  come  off  separately  from 
the  radial  artery. 

(4;  The  dorsalis  indicis  arises  from  the  radial  just  as  that  artery  sinks  Ix'- 
tween  the  two  heads  of  the  first  dorsal  interosseous  muscle,  usually  below  the  origin 
of  the  dorsalis  pollicis,  but  sometimes  as  a  common  trunk  with  the  latter  vessel. 
It  runs  downwards  along  the  radial  side  of  the  metacarpal  bone  of  the  index 
finger,  and  can  be  traced  along  the  radial  side  of  that  finger  as  far  as  the  first  inter- 
phalangeal  joint,  where  it  anastomoses  with  the  dorsal  branch  of  the  radialis 
indicis. 


III.  The  Radial  Artery  in  the  Palm  (the  Deep  Palmar  Arch) 

The  radial  artery  enters  the  palm  between  the  first  and  second  metacarpal  bones 
at  the  base  of  the  first  interosseous  space,  by  passing  between  the  two  heads  of  the 
first  dorsal  interosseous  muscle.  It  then  runs  inwards  between  the  adductor 
pollicis  and  inner  head  of  the  flexor  brevis  pollicis,  and  continuing  its  course,  in  a 
slight  curve  with  the  convexity  forwards,  across  the  base  of  the  metacarpal  l^ones 
and  interosseous  muscles,  it  anastomoses  with  the  deep  branch  of  the  ulnar, 
forming  the  deep  palmar  arch.  The  arch  thus  formed  may  be  said  to  extend  from 
the  first  interosseous  space  to  the  base  of  the  metacarpal  lione  of  the  little  finger, 
and  is  a  finger's  breadth  nearer  the  wrist  than  the  superficial  arch.  It  is  covered 
by  the  superficial  and  deep  flexor  tendons,  by  the  inner  head  of  the  flexor  brevis 
pollicis,  and  by  part  of  the  flexor  brevis  minimi  digiti.  It  is  accompanied  by  the 
deep  l)ranch  of  the  ulnar  nerve,  and  two  small  venae  comites. 

Variations  in  the  Deep  Palmar  Arch 

(A)  The  deep  palmar  arch  may  be  larger  than  u.sual,  and  its  interosseous  branches  supply 
the  })lace  of  one  or  more  of  the  digital  arteries  by  dividing  at  the  cleft  of  the  fingers  into  collat- 
eral digital  branches.  (B)  It  may  be  reinforced  by  enlarged  jidsterior  perforating  branches  fium 
the  radial  and  its  branches  on  the  back  of  the  hand,  or  by  a  large  anterior  intero.sseou.s.  (C)  The 
radial  may  join  the  deep  arch  by  passing  through  the  second  instead  of  the  first  intero.sseous  space. 
(D)  The  princeps  pollicis  and  radialis  indicis  may  come  nff  from  the  supei-ficial  arch  or  from  the 
superficial  volar,  or  from  a  separate  branch  of  the  radial  wliich  passes  through  the  first  intero.sseous 
space. 

The  branches  of  the  deep  palmar  arch  are: — O)  The  princeps  pollicis;  (2) 
the  radialis  indicis;  (3)  the  palmar  interosseous  (three  in  number);  (4)  the  recur- 
rent carpal;  (5)  the  posterior  perforating.  The  first  two  are  usually  spoken  of  as 
coming  off  from  the  radial  artery  in  the  palm;  the  last  three  from  the  deep  palmar 
arch. 

(1)  The  princeps  pollicis  arises  from  the  radial  artery  as  it  enters  the  palm, 
between  the  two  heads  of  the  abductor  indicis.  It  passes  downwards  between  the 
adductor  transversus  pollicis  and  abductor  indicis,  parallel  to  the  metacarpal  bone, 
and  between  the  tAvo  ])ortions  of  the  flexor  brevis  pollicis  under  cover  of  the  flexor 


544 


THE  ARTERIES 


longus  pollicis.  Opposite  the  metacarpo-i)halan(ieal  joint  it  usually  divides  into 
two  branches,  one  of  wliich  is  distributed  to  each  side  of  the  thumb  on  its  palmar 
aspect.  These  vessels  anastomose  with  each  other  at  the  end  of  the  thumb,  like 
the  other  collateral  digital  arteries. 

(2 )  The  radialis  indicis  comes  off  from  the  radial  artery  a  little  lower  than 
the  former  vessel,  or  as  a  connnon  trunk  with  it,  and  passes  forwards  between  the 
abductor  indicis  and  adductor  transversus  pollicis,  parallel  to  the  radial  side  of  the 


Fig.  359. — Axastomosep  and  Distribution  of  the  Arteries  of  the  Hand. 


Aiiltiior  hilerosseotii' 

Radial  nrturij 

Anterior  radial  carpal 


Stiper/icial  lolar 
Posterior  radial  carpjal 
Radial  artery  at  irrisl 


Dorsalis  pollicis 

Metacaipal  or 

first  dorsal 

interosseous 

Princeps  pollicis 

Dorsalis  indicis 
Radialis  indicis 


First  dorsal  branch  of  collateral 
digital 


Second  dorsal  branch  of  collateral 
digital 


Anastomosis  of  collateral  digital 
arteries  about  matrix  of  nail 
and  pulp  uf  finger 


Ulnar  artery 

Anterior  ulnar 
carpal 

Posterior  ulnar 
carpal 


Deep  ulnar 
Superficial  arch 

Carpal  recurrent 

Posterior  communi- 
cating or  perforat- 
ing 

Palmar  interosseous 


Second,  third,  and 
fourth  palmar 
digital 

Second  and  third 
dorsal  interosseous 

First  palmar  digital 


Anterior  communi- 
cating or  perforat- 
ing 


second  metacarpal  bone.  After  emerging  from  beneath  the  adductor  transversus 
j^ollicis,  it  continues  its  course  along  the  radial  side  of  the  index  finger,  on  its 
palmar  aspect,  as  far  as  the  tip,  anastomosing  in  this  course  with  the  collateral 
digital  artery  on  the  opposite  side  of  the  finger  in  a  way  similar  to  that  of  the  other 
collateral  digital  arto^ries.  It  freiiuently  communicates,  at  the  lower  l)order  of  the 
adductor  })ollicis,  with  the  superficial  palmar  arch  and  ]>rinceps  pollicis.  It  gives 
off  a  dorsal  branch,  which  anastomoses  with  the  dorsalis  indicis. 

(3)  The  palmar  interosseous  arteries,  three  in  number,  come  off  from  the 


THORACIC  AORTA  545 

convexity  of  the  deep  arch,  and,  coursing  downwards  in  the  centre  of  the  second, 
third,  and  fourth  interosseous  spaces  on  the  interosseous  muscles,  terminate  near 
the  clefts  of  the  fingers  liy  anastomosing  with  the  digital  arteries  from  the  superficial 
arch.  These  vessels  suitply  the  interosseous  muscles  and  the  bones,  and  the  second, 
third,  and  fourtli  hitiihrirales. 

(4)  The  recurrent  branches  come  off  from  the  concavity  of  the  arch,  and 
consist  of  two  or  three  small  vessels  which  run  upAvards  towards  the  wrist,  and 
anastomose  above  with  the  anterior  liranch  of  the  anterior  interosseous,  and  later- 
ally with  the  anterior  radial  and  ulnar  carpal  arteries,  forming  the  so-called  anterior 
carpal  rete  (fig.  859). 

(5)  The  posterior,  communicating,  or  perforating,  also  usually  three  in 
number,  pass  from  the  arch  directly  through  the  second,  third,  and  fourth  inter- 
osseous spaces  between  the.  two  heads  of  the  corresponding  dorsal  interosseous 
muscle,  and  join  the  proximal  ends  of  the  metacarpal  artery  (first  dorsal  inter- 
osseous), and  the  second  and  third  dorsal  interosseous  arteries  respectively. 


THE  DESCEXDIXG,  OR  THORACIC  AORTA 

The  thoracic  aorta  (fig.  360)  extends  from  the  termination  of  the  aortic  arch 
at  the  lower  liorder  of  the  body  of  the  fifth  thoracic  vertebra  to  the  lower  border  of 
the  body  of  the  twelfth  thoracic  vertebra,  where  it  passes  through  the  aortic  open- 
ing in  the  diaphragm,  and  is  thence  continued  under  the  name  of  the  abdominal 
aorta.  It  is  at  first  situated  a  little  to  the  left  of  the  vertebral  column,  but  as  it 
descends  approaches  the  front  of  the  column,  at  the  same  time  following  the  back- 
ward curve  of  the  spine,  and  at  its  passage  through  the  diaphragm  is  almost  in  the 
middle  line.  It  Hes  in  the  posterior  mediastinum,  having  the  oesophagus  at  first 
a  little  to  the  right  of  it,  then  in  front  of  it,  and  just  above  the  tenth  thoracic 
vertebra,  where  this  tube  pierces  the  diaphragm,  a  little  to  its  left  side. 

Relations. — In  front  it  is  crossed  from  above  downwards  by  the  root  of  the 
left  lung,  by  the  oesophagus,  which  separates  it  from  the  pericardium  and  heart, 
and  by  the  diaphragm. 

Behind,  it  lies  upon  the  lower  seven  thoracic  vertebrae,  and  is  crossed  obliquely 
opposite  the  seventh  or  eighth  thoracic  vertebra  by  the  vena  azygos  minor,  and 
opposite  the  tifth  or  sixth  vertebra  by  the  third  azygos  vein,  or  by  one  or  more 
of  the  left  intercostal  veins. 

On  the  right  side  it  has,  above,  the  oesophagus,  and  lower  down  the  right 
pleura  and  lung.  The  vena  azygos  major  and  thoracic  duct  also  lie  to  the  right, 
but  on  a  somewhat  posterior  plane. 

On  the  left  side  it  has  the  left  lung  and  pleura  above,  and  the  oesophagus  below. 
The  vena  azygos  minor  and  the  third  azygos  vein  are  also  to  the  left,  but  on  a  pos- 
terior plane. 

Branches  of  the  Thoracic  Aorta 

Thp  branches  of  the  thoracic  aorta  may  be  divided  into  the  visceral  and  the 
parietal.  The  visceral  are: — (1)  The  pericardiac;  (2)  the  l)ronchial;  and  (3)  the 
(esophageal.  The  parietal  are: — (1)  The  intercostal;  (2)  the  subcostal;  (3) 
the  diaphragmatic;  and  (4)  the  arteria  aberrans. 

A.    Viiccral  Branchrs 

(1)  The  pericardiac — two  or  three  small  branches,  irregular  in  their  origin, 
course,  and  (li.^tribution — jniss  to  the  po.sterior  surface  of  the  pericardium  to  supply 
that  structure,  and  anastomose  with  the  otlier  pericardiac  l)ranches.  They  give 
small  twigs  to  tlio  jiosti-rior  m«_'diastinal  glands. 

(2)  The  bronchial  arteries  ( Hg.  324)  supply  the  bronchi  and  the  lung  sub- 
stance. They  vary  considerably  in  their  origin,  course,  and  distribution;  they  are 
usually  three  in  number — one  on  the  right  side,  and  two  on  the  left. 

(a)  The  right  bronchial  generallv  arises  either  from  the  first  right  aortic  inter- 
35 


546 


THE  ARTERIES 


costal,  or  else  as  a  common  trunk  witli  the  left  upper  1)ronehial  from  the  front  of 
the  thoracic  aorta  just  l)elow  the  level  of  the  bifurcation  of  the  trachea.  It  passes 
outwards  on  the  back  of  the  right  bronchus,  and  is  distributed  to  the  bronchi  and 
lung  substance.  (6)  The  left  upper  bronchial  arises  from  the  front  of  the 
thoracic  aorta  just  below  the  bifurcation  of  the  trachea,  or  as  a  common  trunk  with 


Fig.  360. — The  Arch  of  the  Aokta.  the  Thoracic  Aorta,  and  the  Abdominal  Aorta, 
WITH  THE  Superior  and  Inferior  Vena  Cava  and  the  Innominate  and  Azygos 
Veins. 


Right  coiiimon  carotid 

artery 
Might  internal  jugular 


RIGHT  LYMPHATIC  DUCT 

Innoniinole  artery 

RIGHT  PXEUMO- 

GASTRIC  XERVE 

Right  innominate  vein 

Internal  mammary  vein 

Ti'tivk  of  the  pericardiac 
and  thymic  veins 
Vena  cava  superior 


Vena  azygos  major 


Vena  azygos  minor,  cross- 
ing spine  to  enter  vena 
azygos  major 


Hepatic  veins   .__^ 


Vena  cava  inferior 

Right  phrenic  artery 

Cceliac  axis 

Right  middle  suprarenal 
artery 


Right  spermatic  artery 
Right  spermatic  vein 


Lejt  common  carotid 

artery 
LEFT  PXEUMOGAS- 
TRIC  NERVE 

THORACIC  DUCT 

Ly't  innominate  vein 

Left  subclavian  artery 

Left  superior  intercostal 
vein 

RECURREXT 
LARYNGEAL 
NER  VE 

Vena  azygos  tertius 

OESOPHAGUS 

Left  upper  azygos  vein 

(Esophageal  branches 
from  aorta 

Vena  azygos  minor 


THORACIC  DUCT 


Left  phrenic  artery 

Left  middle  suprarenal 

artery 
REGEPTACULUM  CHYLI 

Superior  mesenteric 
artery 

Left  ascending  luynbar 

vein 
Left  spermatic  vessels 


Inferior  mesenteric 
artery 


the  right  bronchial,  (c)  The  left  lower  bronchial  arises  from  the  front  of  the 
thoracic  aorta  just  below  the  level  of  the  left  l^ronchus.  Like  the  corresponding 
artery  on  the  right  side,  the  left  broncliial  arteries  run  outwards  on  the  left 
bronchus,  and,  after  dividing  and  subdividing  on  the  back  of  the  bronclii,  supply 
the  bronchi  themselves  and  the  lung  substance.  Small  twigs  are  given  off  from  the 
bronchial  arteries  to  the  bronchial  glands  and  to  the  oesophagus. 


THORACIC  AORTA 
Fig.  361.— Schp:me  of  the  Thoracic  Aorta.     (Walsliara.) 


547 


1.   At  level  of  fifth 
thoracic  vertebra 


Intercostal  artery 
Intercostal  vein 

Vena  azygos  major 

THORACIC  DUCT 

(ESOPHAGEAL  PLEXUS  OF 
RIGHT  PXEUMOGASTRIC 
y£R  VE 

(ESOPHAGUS 
(ESOPHAGEAL  PLEXUS  OF 
L  EFT  PXE  UMO  GA  STRIC 
XER  VE 


2.  At  level  of  seventh 
thoracic  vertebra. 


Intercostal  artery 
Intercostal  vein 

Vena  azygos  major 

THORACIC  DUCT 

PLEURA 

LUNG 

RIGHT  (ESOPHAGEAL 

PLEXUS 

LEFT  (ESOPHAGEAL 

PLEXUS 


3.  At  level  of  ninth 
thoracic  vertebra. 


Intercostal  artery 
Intercostal  vein 

Vena  azygos  major 

THORACIC  DUCT 


Intercostal  vein 
Intercostal  artery 

Left  upper  azygos  vein 


Intercostal  vein 
Intercostal  artery 

PLEURA 

LUNG 

Vena  azygos  minor 


RIGHT  PXEUMOGASTRIC 
XER  VE 
-    ISDPHAGUS 

LEFT  PXEU.VOGASTRIC 
XER  VE 


548  THE  ARTERIES 

(3)  The  CESophageal  arteries,  four  or  sometimes  five  in  number,  arise  at 
intervals  from  the  front  of  the  thoracic  aorta,  the  first  coming  off  just  below  the  left 
lower  bronchial.  They  usually  increase  in  size  from  above  downwards,  the  upper 
coming  olt"  nn)re  towards  the  right  side  of  the  aorta,  the  lower  more  towards  the  left 
side.  They  i)ass  forwards  to  the  oesophagus,  supplying  that  tu])e  and  anastomosing 
with  each  other  and  with  the  descending  oesophageal  branches  of  the  inferior 
thvroid  above,  and  Avith  the  ascending  oesophageal  branches  of  the  phrenic  and 
gastric  arteries  below,  thus  forming  a  chain  of  anastomoses  along  the  whole  length 
of  the  tube. 

B.   Parietal  Branches 

(1)  The  aortic  intercostal  arteries,  usually  ten  in  number  on  each  side, 
supply  the  lower  intercostal  spaces,  the  two  upper  spaces  being  supplied  by  the 
superior  intercostal  branch  of  the  subclavian  artery.  The  tenth  artery  runs  along 
the  lower  l)order  of  the  last  rib,  and  would  be  better  called  the  subcostal  artery; 
it  is  similar  in  its  distribution  to  the  other  intercostals,  but  is  described  separately. 

The  aortic  intercostals  arise  in  pairs  from  the  back  part  of  the  thoracic  aorta, 
and  at  once  turning,  the  one  to  the  right,  the  other  to  the  left,  wind  backwards 
over  the  front  and  sides  of  the  vertebral  bodies  to  reach  the  intercostal  spaces, 
which  they  follow,  and  anastomose  in  front  with  the  anterior  intercostals  given  oflf 
from  the  internal  mammary  and  musculo-ijhrenic  arteries  respectively.  In  foetal 
life  these  arteries  run  almost  transversely  backwards,  or  even  with  a  slight  inclina- 
tion downwards,  to  the  intercostal  spaces;  but  after  the  first  year,  in  conseciuence 
of  the  disproportionate  growth  of  the  aorta  and  vertebral  colunm,  the  upper  inter- 
costals have  to  ascend  to  reach  their  respective  spaces.  For  convenience  of  descrip- 
tion the  intercostal  arteries  may  be  divided  into  two  portions — the  vertebral,  which 
lies  upon  the  bodies  of  the  vertebrae;  and  the  intercostal,  which  lies  in  the  inter- 
costal spaces. 

The  vertebral  portion. — The  arteries  in  their  course  round  the  vertebrse  differ 
on  the  two  sides  of  the  body.  On  the  right  side  the  arteries — and  especially  the 
upper,  in  consequence  of  the  aorta  lying  a  little  to  the  left  side  of  the  spine  in  the 
upper  part  of  its  course — are  longer  than  the  left.  They  wind  over  the  front  and 
right  side  of  the  vertebrse,  being  crossed  by  the  thoracic  duct  and  vena  azygos 
major,  and  covered  by  the  right  pleura  and  lung.  The  upper  are  also  crossed  by 
the  oesophagus.  They  give  oflf  small  l:)ranches  to  the  bodies  of  the  vertel)ra^  and 
anterior  common  ligament.  On  the  left  side,  as  the  intercostals  wind  round  the 
sides  of  the  bodies  of  the  vertebrse,  the  lower  are  crossed  by  the  vena  azygos  minor, 
the  two  upper  by  the  left  superior  intercostal  vein,  and  the  two  next  by  the  third 
azygos  vein  when  this  is  present.  They  are  all  covered  by  the  left  pleura  and 
lung. 

The  intercostal  portion. — In  their  course  through  the  intercostal  spaces  the 
arteries  are  alike  on  both  sides.  They  at  first  cross  the  intercostal  spaces  ol;)liquely, 
in  consequence  of  the  downward  direction  of  the  riljs,  towards  the  angle  of  the  rib 
above,  and  thence  are  continued  forward  in  the  subcostal  groove,  and  anastomose 
with  the  superior  branches  of  the  anterior  intercostals  from  the  internal  mammary 
in  the  upper  spaces,  and  from  the  musculo-phrenic  in  the  loAver  spaces.  They  lie 
at  first  on  the  external  intercostal  muscles,  being  covered  in  front  by  the  pleura  and 
lung,  the  endothoracic  fascia  and  the  infra-costales  muscles.  Opposite  the  heads  of 
the  ribs  they  are  crossed  by  the  sympathetic  nerve.  At  the  angle  of  the  ribs  they 
pass  under  cover  of  the  internal  intercostal  muscles,  and  thence  to  their  termination 
lie  between  the  two  intercostal  muscles.  Their  situation  in  the  midspace  as  far  as 
the  angle  of  the  ril)  should  be  remembered  in  performing  paracentesis  thoracis.  To 
avoid  the  risk  of  injuring  the  vessels,  the  puncture  should  not  be  made  further 
back  than  the  angle  of  the  ril;)S.  They  are  accompanied  by  an  intercostal  nerve 
and  vein,  the  vein  lying  above  and  the  nerve  below,  except  in  the  upper  si)aces 
where  the  artery,  having  to  ascend  to  reach  the  space,  at  first  lies  below  the  nerve 
which  passes  transversely  outwards.  The  uppermost  aortic  intercostal  artery 
anastomoses  with  the  superior  intercostal  from  the  subclavian,  and  at  times  sup- 
plies almost  entirely  the  second  intercostal  space.  The  arteries  to  the  tenth  and 
eleventh   spaces  on   reaching  the  end   of  their  respective  ribs  pass  between  the 


THORACIC  AORTA 


549 


abdominal  muscles,  and  anastomose  with  the  deej)  epigastric  artery  from  the 
external  iliac,  and  with  the  luml)ar  arteries  from  the  al^dominal  aorta. 

The  intercostal  arteries  give  oft"  the  following  branches: — 

(a)  The  dorsal  branch. — This  large  branch  is  given  off  from  the  intercostals 
opposite  the  quadrilateral  space  l^ounded  by  the  transverse  process  of  the  vertebra 
above,  the  neck  of  the  rib  below,  the  body  of  the  vertebra  internally,  and  the 
superior  eosto-trans verse  ligament  externally.  Passing  backwards  towards  this  space 
with  the  dorsal  branch  of  tlie  corresponding  intercostal  nerve,  the  dorsal  branch 
divides  oi)p()site  the  intervertebral  foramen  into  a  spinal  and  a  nmscular  Itranch. 
(i)  The  spinal  branch  enters  the  intervertebral  foramen  along  with  the  undivided 
trunk  of  the  intercostal  nerve,  and  subdivides  into  three  branches: — («)  an  anterior, 
or  preneural,  which  ramifies  on  the  back  of  the  body  of  the  vertebra  and  anas- 
tomoses wdth  the  corresponding  vessels  above  and  below;  (/5)  a  posterior,  or  retro- 


FiG.  362. — Scheme  of  Intercostal  Artery.     (Walsbam.) 

liongissimus  dorsi 

External  division  oj  muscular  branch 
I        lUo-costalis 


Internal  dirision  of  muscular  branch 
Semispinalis  dorai  and  multifldua  spinae 


Posterior  spinal  arteries 


Retroneural  branch  - 

Medullary  branch 

Preneural  branch 

SPISAL  CORD 

Anterior  spinal  artery 

Intercostal  artery 

Vena  azygos  minor 

Vena  azygos  major 

THORACIC  DUCT 

(ESOPHAGUS 


Spinal  branch 


Dorsal  branch 


Anterior  intercostal 


Internal  mammary  artery 


Anterior  per/orating  branch  of 
internal  mammary  artery 


SYMPATHETIC 


Lower  branch  of 
aortic  intercostal 

Upper  or  main 
branch  of  aortic 
intercostal 

Lateral  cutaneous 
branch 


Lower  branch  of 
anterior  intercostal 

Mammary  glandular 

branch 
I'j'per  or  main 

branch  of  anterior 

intercostal 


neural,  which  ramifies  over  the  ])ack  of  the  spinal  canal  and  also  anastomoses  with 
the  like  artery  above  and  below;  and  (y)  a  middle  or  medullary,  which,  passing 
inwards  in  the  sheath  of  dura  mater  to  the  spinal  cord,  anastomoses  with  the 
anterior  s})inal  artery  in  front,  and  with  the  posterior  s])inal  artery  behind.  ( ii)  The 
muscular  branch  passes  backwards  through  the  quadrilateral  space,  and  soon 
sultdivides  into  an  external  and  internal  branch.  The  former  passes  between  the 
longissimus  dorsi  and  ilio-costalis,  and,  after  supplying  these  muscles,  gives  cuta- 
neous offsets  to  the  integuments.  The  latter  or  internal  branch  pierces  the  multi- 
fidus  spinse,  and,  emerging  between  the  longissimus  dorsi  and  semispinalis  dorsi 
near  the  spinous  processes,  gives  cutaneous  offsets  to  the  skin.  It  supplies  the 
nmscles  in  its  course 

(h)  The  collateral  intercostal  branch  comes  off  from  the  intercostal  artery 
near  the  angle  of  the  rib  above,  and  descends  to  the  upper  border  of  the  rib  l)elijw, 


550  THE  ARTERIES 

along  which  it  runs  between  the  intercostal  muscles  to  anastomose  with  the  inferior 
division  of  the  anterior  intercostal  branch  of  the  internal  mammary  artery.  It  is 
much  smaller  than  the  main  intercostal  artery,  and  heli)s  to  supply  the  structures 
in  the  intercostal  space  and  neighbouring  parts. 

(c)  The  pleural  branches  ramify  beneath  the  pleura,  forming  a  plexus  by 
anastomosing  with  like  branches  above  and  below. 

(ri)  The  muscular  branches  supply  the  intercostals,  serratus  magnus,  and 
pectoralis  major  and  minor,  and  anastomose  Avith  the  long  and  short  thoracic 
branches  of  the  axillary  artery. 

(e)  The  lateral  cutaneous  branches  run  with  the  lateral  cutaneous  branches 
of  the  intercostal  nerves  to  tlic  skin. 

(/)  The  mammary  glandular  branches  are  given  off  from  the  intercostal 
arteries  in  the  third,  fourth,  and  fifth  intercostal  spaces,  and  supply  the  mannnary 
gland.  They  are  of  large  size  during  lactation,  and  generally  require  a  ligature  in 
the  removal  of  the  breast. 

(2)  The  subcostal  artery,  or  the  tAvelfth  dorsal  as  it  is  sometimes  called, 
follows  the  same  course  as  the  intercostals  as  far  as  the  head  of  the  twelfth  rib.  It 
then  passes  in  compan}^  with  the  twelfth  dorsal  nerve  along  the  lower  border  of  the 
twelfth  rib,  lying  in  front  of  the  quadratus  lumborum  muscle,  behind  the  fascia 
transversalis.  Crossing  in  front  of  it  is  the  thickened  upper  bridge-like  margin  of 
this  fascia,  which  stretches  across  the  quadratus  and  gives  origin  to  some  of  the 
fibres  of  the  diaphragm,  and  is  known  as  the  ligamentum  arcuatum  externum. 
The  subcostal  artery  anastomoses  with  the  lumliar  arteries  and  external  circumflex 
iliac  artery.  At  the  outer  edge  of  the  quadratus  lumliorum  it  passes  between  the 
abdominal  muscles,  and  is  distributed  in  a  manner  similar  to  that  of  the  lumlmr 
arteries. 

(3)  The  diaphragmatic  branches  are  small  twigs  coming  off  from  the  thoracic 
aorta  immediately  above  the  diaphragm.  They  are  distributed  to  the  vertebral 
portion  of  the  diaphragm  on  its  upper  surface. 

(4)  The  aberrans  artery  is  a  small  twig  which,  arising  from  the  thoracic  aorta 
near  the  right  bronchial  artery,  passes  upwards  and  to  the  right  behind  the 
oesophagus  and  trachea,  and  is  occasionally  found  to  anastomose  on  the  a?sophagus 
with  the  arteria  aberrans  of  the  superior  intercostal  artery.  It  is  regarded  as  the 
remains  of  the  right  aortic  dorsal  stem  (fig.  345). 


THE  ABDOMINAL  AORTA 

The  abdominal  aorta  (fig.  363),  the  continuation  of  the  descending  or  thoracic 
aorta,  begins  at  the  aortic  opening  in  the  diaphragm  opposite  the  lower  border  of 
the  twelfth  thoracic  vertebra,  and  ends  opposite  the  middle  of  the  body  of  the 
fourth  lumbar  vertebra  on  its  left  side,  by  dividing  into  the  right  and  left  common 
iliac  arteries.  It  is  at  first  centrally  placed  between  the  pillars  of  the  diaphragm, 
but  as  it  descends  in  front  of  the  lumbar  vertebrae  it  leaves  the  middle  line,  and,  at 
its  bifurcation,  lies  a  little  to  the  left  side  of  the  spine.  The  spot  at  which  the 
aorta  bifurcates  is,  for  all  practical  purposes,  roughly  indicated  on  the  surface  of 
the  abdomen  by  a  point  about  half  an  inch  below  and  a  little  to  the  left  of  the  um- 
bilicus. But  the  level  of  its  bifurcation  may  be  more  accurately  determined  by  a 
line  drawn  across  the  front  of  the  abdomen  from  the  highest  point  of  one  iliac  crest 
to  the  highest  point  of  the  other. 

The  vena  cava  inferior,  which  accompanies  the  abdominal  aorta,  lies  to  its  right 
side.  Below,  the  vein  is  in  contact  with  the  artery  and  on  a  somewhat  posterior 
plane;  but  above,  it  is  separated  from  the  aorta  by  the  right  crus  of  the  dia])hragm, 
and  in  consequence  of  the  caval  opening  in  the  diaphragm  being  placed  further 
forward  than  the  opening  for  the  aorta,  is  on  an  anterior  plane. 

Relations. — In  front  (fig.  364),  the  aorta  is  successively  crossed  from  above 
downwards  by  the  right  lobe  of  the  liver,  the  solar  plexus,  the  lesser  omentum, 
the  termination  of  the  oesophagus  in  the  stomach,  the  ascending  layer  of  the  trans- 
verse meso-colon,  the  splenic  vein  or  commencement  of  the  vena  porta,  the  pan- 
creas, the  left  renal  vein,  the  third   portion  of  the  duodenum,  the  mesentery,  the 


ABDOMINAL  AORTA 


551 


aortic  plexus  of  the  sympathetic  nerve,  the  spermatic  or  ovarian  arteries,  the  infe- 
rior mesenteric  artery,  the  median  lumbar  lymphatic  glands  and  lymphatic  vessels, 
and  the  small  intestines. 

Of  these  structures  the  solar  plexus,  the  aortic  plexus,  the  splenic  vein  or  the 
commencement  of  the  vena  porta,  the  j)ancreas,  the  left  renal  vein,  the  duodenum, 
the  lymphatics,  the  spermatic  or  ovarian  arteries,  and  the  peritoneal  reflexions  are 
in  contact  with  the  aorta. 

Behind,  the  aorta  lies  upon  the  bodies  of  the  lumbar  vertebrae  and  intervening 


Fig.  363. 


-The  Abdominwl  Aorta  and  its  Branches,  with  the  Inferior 
Vena  Cava  and  its  Tributaries. 


Ci/stic  artery 

HEPATIC  DUCT 

CYSTIC  DUCT 

COMMON  DUCT 

Portal  vein 

G astro-duodenal  br. 

Superior  pyloric  br. 

Hepatic  artery 

Iliglit  suprarenal  vein 
Inferior  suprarenal 
artery 
Renal  artery 

Renal  vein 

Inferior  vena  cava ^ 

KIDNEY 


Right  spermatic  vein  — 


Riyht  spermatic  artery 

Quadratus  lumborum 

muscle 

Right  lumbar  artery  and 

left  lumbar  vein 

Ureteric  branch  of 

spermatic  artery 


Middle  sacral  vessels 


LEFT  LOBE  OF  LIVER 

(ESOPHAGUS 

Left  phrenic  artery 

Right  phrenic  artery 
Superior  suprarenal 
Gastric  artery 
Inferior  suprarenal 
Splenic  artery 

Left  phrenic  vein 
Left  suprareiial  vein 
Superior  mesenteric 
artery 

KIDNEY 

Ureteric  branch  of  renal 
Left  spermatic  vein 

URETER 

Left  spermatic  artery 


Inferior  mesenteric  artery 

Ureteric  branch  of 
spermatic 


Ureteric  branch  of 

common  iliac 
Common  iliac  artery 


External  iliac  artery 
Internal  iliac  artery 


intervertebral  cartilages,  the  anterior  common  ligament,  the  origin  of  the  left  crus 
of  the  diai)hragm,  and  the  left  luml)ar  veins. 

On  the  right  side  from  above  downwards  are  the  right  crus  of  the  diiiphragm, 
the  great  splanelmic  nerve,  the  Si)igelian  lobe  of  the  liver,  the  receptaculum  cliyli 
and  beginning  of  the  thoracic  duct  (the  two  latter  structures  are  on  a  posterior 
plane),  the  right  semilunar  ganglion,  and  the  vena  cava  inferior. 

On  tlie  left  side  are  the  left  crus  of  the  dia])hragm,  the  left  splanchnic  nerve, 
and  the  left  semilunar  ganglion.  The  pancreas  is  also  in  contact  with  the  aorta 
on  the  left  side,  as  are,  too,  the  small  intestines,  but  separated  from  it  by 
peritoneum. 


552 


THE  ARTERIES 


Variations  in  the  Abdominal  Aorta 

Variations  in  the  abdominal  aorta,  except  as  regards  its  place  of  division  and  some  irregu- 
larity ill  the  origin  and  number  of"  its  branches,  are  not  common.  According  to  Quain,  in  ten  out 
of  every  thirteen  subjects  examined,  the  bifurcation  took  place  within  half  an  inch  above  or  below 
the  level  of  the  highest  part  of  the  crest  of  the  ilium.  The  commonest  situation  for  its  bifurca- 
tion with  reference  to  the  vertebrse  is  perhaps  opposite  the  lower  border  of  the  bodj'of  the  fourtli 
lumbar,  but  it  maj'  divide  oi)posite  the  disc  between  the  fourth  and  fifth  lumbar,  or  rarely  oi)j»o- 
site  the  fifth  lumbar.  A  higher  division  than  at  the  usual  spot  is  less  common.  The  arteiy, 
however,  has  been  found  in  exceptional  instances  dividing  as  high  as  the  origin  of  the  renal 
arteries,  or  even  as  high  as  the  second  lumbar  vertebra. 

The  following  rare  variations  have  been  met  Avith  : — (A)  The  aorta  passing  through  tlie 
oesophageal  opening  in  the  diaphragm.  (B)  The  aorta  lying  on  the  right  side  of  the  vena  cava; 
the  vein  then  passes  over  the  upper  part  of  the  aorta  to  gain  the  caval  opening.  (C)  The  aorta 
with  a  vena  cava  on  each  side,  the  left  vein  passing  across  the  upper  part  of  the  artery  to  open 


Fig.  364. — Scheme  of  the  Abdominal  Aorta.     ("NValsham.) 


LESSER  OMENTUM 


Splenic  vein 


PANCREAS 

Left  renal  vein 
Superior  mesenteric 
artery 
TRANSVERSE  MESO-COLON 

THIRD  PART  OF  DUODENUM 


TRANSVERSE  COLON 
MESENTERY 


SMALL  INTESTINES 

GREAT  OMENTUM 

Inferior  mesenteric 
artery 


THORACIC  DUCT 
Cceliac  axis 


First  lumbar  vein 

RECEPTACULUM   CHYLI 


Second  lumbar  vein 


PERITONEUM 

Third  lumbar  vin 


Fourth  lumbar  vein 


into  the  right  vein  just  below  the  caval  opening.  (D)  The  aorta  giving  off  a  imbnonary  branch 
close  to  the  origin  of  the  cceliac  axis,  the  abnormal  vessel  then  passing  through  the  oesophageal 
opening,  and  supplying  a  branch  to  the  lower  lobe  of  each  lung. 

The  variations  in  the  branches  of  the  aorta  are  described  under  each  branch. 


Branches  of  the  Abdominal  Aorta 

The  branches  of  the  abdominal  aorta  are  given  off  in  the  following  order 
from  ahove  downwards  (fig.  863): — 

(1)  Right  and  left  phrenic;  (2)  coeliac  axis;  (3)  right  and  left  suprarenal  or 
capsular;  (4)  right  and  left  first  lumbar;  (5)  su])erior  mesenteric;  (6)  right  and 
left  renal;  (7)  right  and  left  si>ermatic;  (8)  right  and  left  second  lumbar;  (9) 
inferior  mesenteric;  (10)  right  and  left  third  lumbar;  (11)  right  and  left  fourth 
lumbar;   (12)  right  and  left  common  iliac;   (13)  middle  sacral. 

The  above  branches  may  be  divided  into  the  parietal,  the  visceral,  and  the 
terminal. 


PHRENIC  AND    LUMBAR  553 

The  parietal  branches  are  distributed  to  the  abdominal  walls.  They  are  the 
right  and  left  })lnvnics.  and  the  four  right  and  left  lumbars. 

Tiie  visceral  branches  supply  the  viscera.  Three  of  these  are  given  oft" 
singly  from  the  front  of  the  aorta,  namely,  the  ea4iac  axis,  the  sujierior  mesenteric 
and  the  inferior  mesenteric;  and  three  are  given  oft'  in  pairs,  namely,  the  two 
suprarenals.  the  two  rciials,  ami  the  two  spermatics. 

The  terminal  branches  are  the  middle  sacral  and  the  right  and  left  common 
iliac  arteries. 


A.     The    Parietal  BRANCHFi?  of  the  Abdominal  Aorta 

1.     THE  PHRENIC  ARTERIES 

The  right  and  left  phrenic  arteries — sometimes  called  the  inferior  phrenic  to 
distinguish  them  from  the  diaphragmatic  branches  of  the  internal  manmiary  and 
thoracic  aorta — usually  arise  from  the  aorta  as  it  passes  between  the  crura  of  the 
diaphragm  either  as  a  common  trunk  or  as  separate  vessels.  At  times  they  come 
off  as  a  common  trunk  from  the  coeliac  axis;  or  either  the  right  or  left  vessel  may 
come  from  this  artery,  or  from  other  of  the  upper  branches  of  the  abdominal 
aorta. 

The  right  phrenic  passes  (fig.  363)  over  the  right  crus  of  the  diaphragm  behind 
the  vena  cava,  and  then  upwards  and  to  the  right  Ijetween  the  central  and  right 
leaflets  of  the  central  tendon  of  the  muscle,  where  it  divides  into  an  anterior  and 
a  posterior  branch.  The  former  courses  forwards  and  inwards,  and  anastomoses 
with  the  anterior  branch  of  the  left  phrenic,  Avith  the  musculo-phrenic  branches  of 
the  internal  mammary,  and  with  the  superior  phrenic  arteries;  the  latter  passes 
outwards  and  liackwards  towards  the  ribs,  and  anastomoses  with  the  intercostal 
arteries.  Besides  the  two  terminal  branches  and  branches  for  the  supply  <»f  tln' 
diaphragm  itself,  the  right  phrenic  gives  off  the  following: — (1 )  Right  superior 
suprarenal,  to  the  right  suprarenal  capsule;  (2)  caval,  to  the  vena  cava;  (3) 
hepatic,  to  the  liver;  and  (4)  pericardiac,  to  the  pericardium. 

The  left  phrenic  crosses  the  left  crus  of  the  diaphragm  behind  the  cesophagus, 
and  then  runs  l)etween  the  left  and  central  leaflets  of  the  tendon,  dividing  like  the 
right  into  an  anterior  and  a  posterior  branch.  The  former  runs  forwards  and 
inwards,  and  anastomoses  with  the  anterior  branch  of  the  right  phrenic,  the  left 
musculo-phrenic  from  the  internal  mammary,  and  the  suj^erior  ^jhrenic  artery.  The 
latter  courses  outwards  and  Ijackwards  towards  the  ribs,  and  anastomoses  with  the 
intercostal  arteries.  In  addition  to  the  terminal  branches,  and  branches  to 
the  diajjhragm  itself,  the  left  phrenic  gives  off: — (1)  CEsophageal  branches  ti»  the 
ceso])hagus.  where  they  anastomose  with  the  other  (es(»]ihagcal  branclu-s;  {'!)  left 
superior  suprarenal,  to  the  left  suprarenal  l)ody;  (3)  splenic,  to  the  spleen;  and 
(4)  pericardiac,  which  perforate  the  diaphragm  and  anastomose  with  the  other 
pericardiac  arteries. 

The  variations  in  the  origin  of  the  phrenic  arteries  are  very  nuiiierou?>.  The  chief  have  been 
alluded  to  in  the  general  description  of  the  vessels. 


2.  THE  LPMBAR   ARTERIES 

The  lumbar  arteries  (figs.  360,  363),  usually  eight  in  number,  four  on  each 
side,  con)e  oft"  in  pairs  from  the  ])0.sterior  aspect  of  the  abdominal  aorta,  opposite 
the  bodies  of  the  four  ui)i)er  luml)ar  vertebrae  A  fifth  ])air  of  lumbar  arteries, 
generally  of  small  size,  are  frequently  given  off  from  the  middle  sacral  opposite  the 
fifth  lumbar  vertel)ra.  The  lumbar  arteries,  whicli  are  rathi-r  longer  on  tlie  right 
than  on  the  left  side,  in  consequence  of  the  aorta  lying  a  little  to  the  left  of  the 
median  line,  wind  more  or  less  transversely  outwards  round  the  bodies  of  the  ver- 
tel^rse  to  the  interval  between  the  transverse  processes,  where  they  give  off  a  dorsal 
branch,  and  then,  coursing  forwards  between  the  alxlominal  nuiscles,  terminate  liy 


554  THE  ARTERIES 

anastomosing  with  the  other  arteries  of  the  aV)dominal  wall.  As  they  wind  round 
the  l)odies  of  the  vertehrie  they  pass  beneath  the  chain  of  the  sympathetic  nerve, 
and  the  upper  two  beneath  the  right  crus  of  the  diaphragm  on  the  right  side,  and 
the  left  crus  on  the  left  side.  The  right  arteries  also  pass  beneath  the  vena  cava 
inferior,  and  the  two  upper  on  that  side  beneath  the  receptaculuni  chyli.  The 
arteries  on  both  sides  then  dip  beneath  the  tendinous  arch  thrown  across  the  sides 
of  the  bodies  of  the  vertebrae  by  the  psoas,  and  continue  beneath  this  muscle  until 
they  arrive  at  the  interval  between  the  transverse  processes  of  the  vertebrae  and  the 
inner  edge  of  the  quadratus  lumborum.  "Whilst  under  cover  of  the  psoas  they  are 
accompanied  l)y  two  slender  filaments  of  the  sympathetic  nerve  and  by  the  lumbar 
veins.  A  little  anterior  to  the  transverse  processes  they  are  crossed  by  branches  of 
the  luml)ar  plexus,  and  here  usually  cross  in  front  of  the  ascending  lumliar  vein. 
They  now  ^Jass  behind  the  quadratus  lumborum,  with  the  exception  usually  of  the 
first,  and  sometimes  of  the  last,  which  may  pass  in  front  of  the  muscle.  At  the 
outer  edge  of  the  quadratus  they  run  between  the  transversalis  and  the  internal 
obli(jue,  and  then,  perforating  the  internal  oblique,  between  the  internal  and 
external  oblique.  Finally,  much  diminished  in  size,  they  enter  the  rectus,  and  give 
off  one  or  more  anterior  cutaneous  branches,  which  accompany  the  last  dorsal  and 
the  ilio-hypogastric  nerves  to  the  skin.  They  anastomose  with  the  lower  intercos- 
tals,  ilio-lumbar,  deep  circumflex  iliac,  and  deep  epigastric  arteries. 

The  lumbar  arteries  give  off  the  following  branches: — 

(^(1)  Vertebral  branches  which  supply  the  bodies  of  the  vertebrae  and  their 
connecting  ligaments. 

(l))  Muscular  branches  to  the  psoas,  quadratus  lumborum,  and  oblique 
muscles  of  the  abdomen. 

(c)  The  dorsal  branch.  This  is  of  large  size,  and  passes  baclcAvards  in  com- 
pany with  the  dorsal  nerve  between  the  transverse  processes  above  and  below,  the 
intertransversalis  internally,  and  the  quadratus  lumborum  externally,  to  the 
muscles  of  the  Ijack.  On  reaching  the  interval  Ijetween  the  longissimus  dorsi  and 
multifidus  spinte,  it  divides  into  an  external  and  internal  branch.  The  former 
ends  in  the  multifidus,  the  latter  and  larger  supplies  the  erector  spina^,  and  gives 
l)ranches  which  accompany  the  termination  of  the  dorsal  nerves  to  the  skin.  Just 
Ijefore  the  artery  passes  betw^een  the  transverse  processes  it  gives  off  a  spinal  branch, 
which  accompanies  the  lumbar  nerve  through  the  intervertebral  foramen  into  the 
spinal  canal.  Here  the  spinal  branch  divides  into  three  twigs,  one  of  which  passes 
through  the  sheath  of  the  dura  mater  to  the  termination  of  the  spinal  cord  and 
Cauda  equina;  the  other  two  are  distrilmted  to  the  walls  of  the  spinal  canal  after 
the  way  descril^ed  in  the  case  of  the  intercostals. 

((/)  Renal  branches  of  small  size  pass  forwards  in  front  of  the  quadratus  lum- 
borum to  the  ca})sule  of  the  kidney.  The}^  anastomose  with  the  renal  artery.  A 
conmnmication  is  thus  established  between  the  renal  arteries  and  the  arteries 
su])plying  the  lumljar  region. 

The  fifth  pair  of  lumbar  arteries,  when  present,  usually  come  off  from  the 
middle  sacral  artery.  Each  courses  outwards,  l^eneath  the  common  iliac  artery 
and  vein;  and,  after  giving  off  a  dorsal  branch,  ramifies  over  the  lateral  mass  of  the 
sacrum,  and  ends  in  the  iliacus  muscle  l)y  anastomosing  with  the  circumflex  iliac 
artery.  The  dorsal  branch  passes  to  the  back  l)etween  the  last  lumbar  vertebra 
and  the  sacrum  and  ramifies  in  the  gluteus  maximus,  anastomosing  with  the 
luml)ar  arteries  above,  and  with  the  gluteal  artery  below. 

The  variations  in  the  lumbar  arteries  are  not  of  erreat  importance.  (A)  One  or  more  pairs 
may  arise  as  a  common  stem  from  the  back  of  tlie  aorta.  (B)  The  first  lumbar  may  be  joined  at 
its  oriiiin  with  the  sul)oostal  artery  ;  or  the  third  and  fourtli  luud)ar,  or  less  often  the  second  and 
third  lumbar,  may  arise  from  the  aorta  as  a  common  stem.  (C)  The  fii'th  pair  may  sometimes 
be  absent.  _(D)  The  first  lumbar  may  give  off  the  phrenic  or  the  suprarenal.  (E)  One  of  the 
lumbar  arteries  may  give  off  the  spermatic.  (F)  The  fourth  lumbar  on  either  side  may  give  off' 
the  middle  sacral,  or  both  arteries  may  arise  as  a  common  stem  with  the  middle  sacral. 


CCELIAC 


ooo 


B.  The  Visceral  Branches  of  the  Abdominal  Aorta 

THE  CCELIAC  ARTERY 

The  ccEliac  artery — or  cceliac  axis  as  it  is  commonly  called,  because  it  breaks 
up  simultaneously  into  three  branches  which  radiate  from  it  like  the  spokes  of  a 
wheel  from  the  axle — is  a  short  thick  trunk  given  off  from  the  front  of  the  aorta 
l)etween  the  crura  of  the  diaphragm  a  little  below  the  aortic  opening.  It  passes 
horizontally  forwards  above  the  upper  margin  of  the  pancreas  for  about  half  an 
inch,  and  then  breaks  up  into  three  branches  for  the  supply  of  the  stomach, 
duodenum,  spleen,  pancreas,  liver,  and  gall-bladder  (fig.  365). 

Relations. — In  front  is  tlie  lesser  omentum;  behind,  the  aorta;  above,  the 
right  lobe  of  the  liver;  belo^v,  the  pancreas;  to  the  right,  the  right  semilunar 


Fig.  365. — The  Cceliac  Artery  axd  its  Branches. 

Abdominal  aorta  LEFT  CRUS  OF  DIAPHRAGM 

ISOPHAGEAL  BRANCH 


RIGHT  CRUS  OF  DIAPHRAGM 


Celiac  nxis 

Gastric  Vasa 

artery  brevia 


Cystic  artery 

Right  phrenic  artery 

HEPATIC  DUCT 

CYSTIC  DUCT 

Splenic  artery 

COMMON  BILE  DUCT 

Pyloric  artery 

Gustro-duodenal  artery 


Superior  pancreaticfi- 
(luodenal  artery 
HEAD  OF  PANCREAS 

Inferior  pancreatico- 
duodenal artery 
Right  gastro-epiploic 
artery 


Left  gastro-epiploic  artery 


ganglion  and  lobulus  Spigelii  of  the  liver;  to  the  left,  the  left  semilunar  ganglion 
and  the  cardiac  end  of  the  stomach.  It  is  closely  surrounded  by  the  dense  solar 
plexus  of  sympathetic  nerves. 

Variations. — (A)  The  ((leliac  axis  may  be  absent ;  the  branches  usually  arisinsr  fmrn  it  then 
cominir  off  separately  from  the  aorta.  (B)  It  may  be  shorter  or  longer  than  usual.  Ftuler  the 
latter  circumstaiice  the  branches  are  commonly  given  off  separately  from  the  tnink  of  the  vessel 
instead  of  radiating  frf)m  one  spot.  (C)  It  may  give  off  two  branches  only  :  these  are  usually  the 
splenic  and  hepatic,  more  rarely  the  gastric  and  the  splenic.  (D)  It  may  give  off  more  than  three 
branches,  the  additional  branch  being  one  of  the  jdircnies  ;  a  trunk  common  to  the  two  phrenics; 
a  gastro-duodenal ;  a  second  gastric  or  splenic  artery,  or  the  superior  mesenteric;  the  median 
colic  or  the  pancreatica  magna.  (E)  One  or  other  of  the  branehes  normal  to  the  coeliac  axis  may 
be  absent,  or  replaced  by  a  stem  common  to  the  idirenies,  or  by  the  right  suprarenal  and  the  nght 
gastro-epiploic,  or  more  rarely  by  some  other  branch. 

Branches  of  the  coeliac  artery.— The  coeliac  axis  gives  off  the  gastric,  hepatic, 
and  splenic  arteries. 


556  THE  ARTERIES 


1.     The  Gastric  Artery 


The  gastric  or  coronary  artery  (fig.  365),  the  smallest  of  the  three  branches 
into  which  the  ccjeliac  axis  di\i(les,  courses  at  first  upwards  and  to  the  left  towards 
the  cardiac  end  of  the  stomach,  where  it  turns  sharply  round,  and  then,  coasting 
along  the  lesser  curvature  of  the  stomach,  descends  from  left  to  right  towards  the 
pylorus.  It  anastomoses  with  the  superior  jiyloric  l^ranch  of  the  hepatic  artery, 
which  has  proceeded  from  the  opposite  direction,  the  two  branches  thus  forming  a 
continuous  arterial  arch  corresponding  to  the  lesser  curvature  of  tlie  stomach. 
The  artery  at  first  lies  behind  the  posterior  layer  of  the  lesser  omental  sac  of  peri- 
toneum (fig.  364),  but  on  reaching  the  cardiac  end  of  the  stomach  it  passes  through 
the  so-called  pancreatico-gastric  fold  of  peritoneum  into  the  lesser  omentum,  between 
which  it  then  runs  to  its  terminal  anastomosis  Avith  the  pyloric.  It  is  surrounded 
1)V  the  coronary  plexus  of  sympathetic  nerves. 

The  branches  of  the  gastric  artery  are: — (1)  The  oesophageal;  (2)  the  car- 
diac;  (3)  the  gastric;  and  (4)  the  hepatic. 

(1)  The  oesophageal  branches,  given  ofif  where  the  artery  makes  its  bend  on 
to  the  stomach,  ascend  on  the  ipsophagus,  and,  i-'assing  through  the  oesophageal 
opening  of  the  diaphragm,  anastomose  witli.  the  thoracic  oesophageal  branches  and 
the  branches  from  the  left  phrenic. 

(2)  The  cardiac  branches,  two  or  more  in  number,  are  given  off  for  the  supply 
of  the  cardiac  end  of  the  stomach,  around  which  they  form  an  anastomotic  circle. 

(3)  The  gastric  branches  come  off  from  the  artery  as  it  lies  between  the  layers 
of  the  lesser  omentum,  and  are  distributed  to  the  front  and  back  of  the  stomach 
(the  lesser  anterior  and  posterior  gastric  branches),  over  which  they  ramify, 
anastomosing  with  branches  ascending  from  the  right  and  left  gastro-epiploic  on 
the  greater  curvature.  One  of  these  branches  of  larger  size  ramifies  over  the  front 
of  the  great  cul-de-sac,  the  greater  anterior  gastric  (Macalister),  and  anastomoses 
with  the  vasa  brevia  and  left  gastro-epiploic  from  the  splenic. 

(4)  The  hepatic  branch  is  a  constant  small  tAvig  passing  to  the  left  lobe  of  the 
liver,  where  it  anastomoses  with  the  left  hepatic  artery. 

Chief  variations. — (A)  The  gastric  may  arise  directly  from  the  aorta,  and  may  then  give  off 
one  of  the  phi'enics,  or  both,  or  a  trunk  common  to  tlie  two.  (B)  There  may  he  two  gastric 
arteries  instead  of  one.  (C)  The  gastric  may  give  off  the  leit  branch  of  the  hepatic  arterj'.  This 
api^ears  to  be  due  to  the  enlargement  of  the  constantly  present  small  hepatic  branch,  and  the 
oblit'^ration  of  part  of  the  normal  left  branch  of  the  hepatic  artery. 

2.  The  Hepatic   Artery 

The  hepatic  artery,  the  largest  branch  of  the  coeliac  axis  in  the  foetus,  but  in- 
termediate in  the  adult  between  the  gastric  and  the  splenic,  comes  off  on  the  right 
side  of  the  coeliac  axis,  and,  winding  upwards  and  to  the  right  to  the  transverse  or 
portal  fissure  of  the  liver,  there  breaks  up  into  two  chief  branches  for  the  supply  of 
the  riglit  and  left  lobe  of  that  organ.  It  at  first  courses  forwards  and  to  the  right 
along  the  upper  border  of  the  head  of  the  pancreas,  behind  the  posterior  layer  of 
the  lesser  omental  sac  of  peritoneum,  to  the  upper  margin  of  the  duodenum,  where, 
at  the  base  of  the  so-called  right  pancreatico-gastric  fold,  it  jiasses  l)etween  the  tAvo 
layers  of  the  lesser  omentum,  and  thus  ascends  along  with  the  hepatic  duct  which 
lies  to  its  right,  and  with  the  portal  vein  which  lies  behind  it,  to  the  transverse  or 
portal  fissure  of  the  liver.  As  it  lies  with  the  hepatic  duct  and  portal  vein  between 
the  layers  of  the  lesser  omentum,  it  is  in  front  of  the  so-called  foramen  of  AMnslow. 

The  branches  of  the  hepatic  artery  are: — (1)  The  pancreatic;  (2)  the  supe- 
rior pyloric;  (3)  the  gastro-duodenal;  (4)  the  right  tej-minal;  and  (5)  the  left 
terminal. 

(1)  The  pancreatic,  or  lesser  pancreatic  branches  as  they  are  often  called, 
come  off  from  the  hepatic  as  it  runs  along  tin-  upjier  margin  of  the  jxancreas,  and 
su})ply  tliat  organ. 

(2)  The  superior  pyloric  comes  oft'  from  the  hepatic  just  as  the  latter  vessel 
enters  the  lesser  omentum,  and,  descending  between  the  two  layers  of  that  fold  of 
peritoneum  to  the  pylorus,  there  turns  leftwards,  and,  ascending  horn  riglit  to  left. 


HEPATIC— SPLENIC  bbl 

anastomoses  along  tlie  lesser  curvature  of  the  stomach,  as  already  mentioned,  ^vith 
the  gastric  artery,  which  descends  from  the  opi)osite  direction. 

(3)  The  gastro-duodenal  arises  from  the  hej)atic  a  little  heyond  the  pyloric. 
It  descends  behind  the  ascending  jjortion  of  the  duodemmi  to  the  lower  Ixn-der  of 
the  ])yloriis,  where  it  divides  into  the  right  gastro-epiploic  and  the  superior 
pancreatico-duodenal.  It  varies  from  half  an  inch  to  an  inch  in  length.  In 
addition  to  the  above  branches,  it  may  give  off  the  inferior  pyloric  artery. 

(a)  The  right  gastro-epiploic,  entering  the  anterior  fold  of  the  great  omentmn, 
coasts  from  riglit  to  left  along  the  greater  curvature  of  the  stomach,  and  anastomoses 
with  the  left  gastro-epiploic  branch  of  the  splenic,  which  descends  from  left  to 
right  also  along  the  greater  curvature  to  meet  it.  From  this  anastomotic  arch  are 
given  off: — (i)  Ascending  or  gastric  branches,  Avhich  supply  the  anterior  and 
])Osterior  surfaces  of  the  stomach,  and  anastomose  with  the  descending  gastric 
branches  of  the  arteries  along  the  lesser  curvature,  (ii)  Epiploic  or  omental 
branches — long  slender  vessels,  which  descend  between  the  two  anterior  layers  of 
the  great  omentum,  and  then,  looping  upwards,  anastomose  with  similar  slender 
branches  given  off  from  the  middle  and  left  colic,  and  passing  down  in  like  manner 
between  the  two  i)osterior  layers  of  the  great  omentum. 

{h)  The  superior  pancreatico-duodenal — the  smaller  division  of  the  gastro- 
duodenal — arises  from  that  vessel  as  it  passes  behind  the  first  portion  of  the 
duodenum,  and  courses  downwards  behind  the  peritoneum,  in  the  anterior  groove 
between  the  second  portion  of  the  duodenum  and  the  pancreas,  to  anastomose  with 
the  inferior  pancreatico-duodenal,  a  V)ranch  of  the  supjerior  mesenteric,  which  runs 
upwards  between  the  contiguous  borders  of  the  pancreas  and  duodenum.  Both  the 
inferior  and  superior  pancreatico-duodenal  give  off  branches  to  the  duodenum 
and  the  pancreas. 

(c)  The  inferior  pyloric  arises  either  from  the  gastro-duodenal  or  from  the 
right  gastro-epiploic;  it  supplies  the  pyloric  end  of  the  stomach,  and  anastomoses 
with  the  other  arteries  in  that  situation. 

(4)  The  right  terminal  branch  of  the  hepatic  artery  is  given  off  at  the  portal 
fissure  of  the  liver,  and  runs  to  the  right  towards  the  end  of  that  fissure,  either 
behind  the  hepatic  and  cystic  ducts,  or  between  these  structures.  At  the  right  end 
of  the  portal  fissure  it  divides  into  two  or  more  branches,  which  again  subdivide  as 
they  enter  the  liver  substance  for  the  supply  of  the  right  lobe.  As  it  crosses  the 
cystic  duct  it  gives  off  the  cystic  artery. 

(a)  The  cystic  artery  courses  forwards  and  downwards  through  the  angle 
formed  by  the  union  of  the  hepatic  and  cystic  ducts,  and  just  before  it  reaches  the 
gall-bladder  divides  into  a  superficial  and  deep  branch.  The  former  breaks  up  into 
a  number  of  small  vessels,  Avhich  ramify  over  the  free  surface  of  the  gall-bladder 
beneath  the  peritoneal  covering,  and  furnish  branches  to  the  musc-ular  and  mucous 
coats.  The  deep  branch  ramifies  between  the  gall-bladder  and  the  liver-substance, 
sujiplying  each,  and  anastomosing  with  the  sujierficial  branch. 

(5)  The  left  terminal  branch,  the  smaller  division  of  the  hepatic  artery,  runs 
inwards  towards  the  left  end  of  the  portal  fissure,  and,  after  giving  oft'  a  distinct 
branch  to  the  Spigelian  lobe,  enters  the  left  lobe  of  the  liver. 

Chief  variations. — (A)  The  hepatic  artery  may  arise  directly  from  tlie  aorta,  or  from  the 
gastric,  the  superior  mesenteric,  or  the  risrht  renal  artery.  (B)  Totrether  with  a  normal  artery 
there  may  be  an  accessory  hepatic  from  one  or  other  of  the  above-named  or  neighbouring 
branches.  (C)  The  hepatic  artery  may  be  altogether  wanting,  and  its  jilace  suj^plied  by  one  or 
more  accessory  arteries  derived  from  one  or  other  of  the  above-named  sources.  This  vtuiation  is 
explained  by  Hyrtl  on  the  supposition  that  there  has  been  oliliteration  of  the  normal  hepatic, 
with  enlargement  of  one  or  more  of  the  minute  branches  which  normally  proceed  from  the  aortii 
and  the  above-named  branches  to  the  capsule  of  the  liver. 

3.  The  Splenic  Artery 

The  splenic  artery — the  largest  branch  of  the  coeliac  axis — arises  from  the  left 
side  of  the  termination  of  that  vessel  below  the  gastric,  and  passes  along  the  upper 
border  of  the  pancreas  in  a  tortuous  manner  to  the  spleen.  It  at  first  lies  behind 
the  ascending  layer  of  the  transverse  meso-colon,  but  on  nearing  the  spleen  enters 


558  THE  ARTERIES 

the  lieno-renal  ligament,  and  there  l^reaks  iiji  into  numerous  branches,  which 
enter  the  hilum  and  supjily  the  organ.  In  this  course  it  crosses  in  front  of  the  left 
crus  of  the  diaphragm  and  the  upper  end  of  the  left  kidney  and  is  placed  above  the 
splenic  vein.' 

The  branches  of  the  splenic  artery  are: — (1)  The  smaller  pancreatic;  (2)  the 
larger  pancreatic;  (3)  the  left  gastro-epiploica;  (4)  the  vasa  Ijrevia;  and  (5)  the 
terminal. 

(1)  The  smaller  pancreatic  branches  come  off  from  the  sjilenic  at  varying 
intervals,  as  that  vessel  courses  along  the  upper  margin  of  the  pancreas.  They 
enter  and  supply  the  organ. 

(2)  The  larger  pancreatic  branch  usually  arises  from  the  splenic  about  the 
junction  of  its  middle  with  its  left  third.  p]ntering  the  ])ancreas  oblitpiely,  it  runs 
from  left  to  right,  commonly  above,  and  a  little  l)ehind,  the  pancreatic  duct,  winch 
it  supplies  together  with  the  substance  of  the  organ. 

(3)  The  left  gastro-epiploic  arises  from  the  splenic  behind  the  great  cul-de-sac 
of  the  stomach,  and,  ])assing  between  the  anterior  layers  of  the  great  omentum, 
descends  along  the  greater  curvature  of  the  stomach  from  left  to  right,  and  anasto- 
moses with  the  right  gastro-epiploic.  Like  that  vessel,  it  gives  off  ascending  or 
gastric  branches  to  the  anterior  and  posterior  surfaces  of  the  stomach  respectively, 
and  long  slender  descending  epiploic  or  omental  branches  to  the  great  omen- 
tum which  anastomose  with  like  liranches  from  the  right  and  left  colic  arteries. 

(4)  The  vasa  brevia  come  off  from  the  splenic  just  before  it  divides  into  its 
terminal  branches,  oftentimes  from  some  of  these  terminal  liranches  themselves. 
Passing  from  between  the  folds  of  the  lieno-renal  ligament  into  those  of  the  gastro- 
splenic,  they  thus  reach  the  greater  cid-dc-sac  of  the  stomach,  where,  ramifying 
over  both  its  anterior  and  posterior  surfaces,  they  anastomose  with  the  gastric  and 
left  gastro-epiploica  arteries. 

(5)  The  terminal  branches,  five  to  eight  or  more  in  number,  are  given  off 
from  the  splenic  as  it  lies  in  the  lieno-renal  ligament,  and,  entering  the  spleen 
at  the  hilum,  are  distributed  in  the  way  mentioned  in  the  description  of  that 
organ. 

The  variations  of  the  splenic  artery  are  neither  numerous  nor  important.  (A)  It  may  divide 
into  two  branches  which  reunite,  the  splenic  vein  running  through  the  loop  thus  formed.  (B)  It 
may  sometimes  give  oiF  branches  nornially  derived  from  other  vessels,  such  as  the  gastric,  the 
middle  colic,  and  the  left  hepatic.  (C)  The  variations  in  its  origin  are  mentioned  under  A'aria- 
TIONS  OF  THE  Cgeliac  Axis  (page  555). 


THE  SUPERIOR  MESENTERIC  ARTERY 

The  superior  mesenteric  artery  is  given  off  from  the  front  of  the  aorta  a  little 
below  the  coeliac  axis,  which  it  nearly  equals  in  size;  sometimes  as  a  common  trunk 
with  the  axis.  Lying  at  first  behind  the  pancreas  and  splenic  vein,  it  soon  passes 
forwards  between  the  lower  border  of  that  gland  and  the  upper  1:)order  of  the  third 
portion  of  the  duodenum,  and,  crossing  in  front  of  the  duodenum,  enters  the 
mesentery,  in  which  it  runs  from  left  to  right,  in  the  form  of  a  curve  with  its  con- 
vexity to  the  left,  to  the  caecum,  Avhere  it  anastomoses  with  its  ileo-colic  branch. 
Its  vein  lies  to  its  right  side  above,  having  previously  crossed  obliquely  in  front  of 
the  artery  from  left  to  right.  It  is  surrounded  liy  the  mesenteric  plexus  of  nerves. 
The  accessory  portion  of  the  head  of  the  pancreas  dips  in  l)ehind  the  vessel. 

From  the  concave  side  of  the  artery  brandies  are  given  oft'  to  the  duodenum  and 
the  colon,  viz. : — 

(1)  The  inferior  pancreatico-duodcnal;  (2)  the  middle  colic;  (3)  the  right  colic; 
and  (4)  the  ileo-colic. 

From  the  convex  side  branches  are  given  off  to  the  small  intestines,  viz. : — 

(5)  The  vasa  intestini  tenuis. 

It  will  thus  be  seen  that  the  superior  mesenteric  artery  supplies,  witli  the  excej)- 
tion  of  the  upper  third  of  tlie  duodenum,  the  whole  of  the  small  intestine  and  lialf 
the  large. 

(1  j  The  inferior  pancreatico-duodenal  arises  either  from  the  superior  mesen- 


SUPERIOR  MESENTERIC 


559 


teric  as  that  vessel  emerges  from  tlie  contiguous  margins  of  the  i)ancreas  and 
transverse  duodenum  or  from  its  first  intestinal  Ijranch,  and,  crossing  ])ehind  the 
superior  mesenteric  vein,  courses  upwards  and  to  the  right  l)etween  the  head  of 
the  pancreas  and  the  duodenum,  beneath  the  ascending  layer  of  the  transverse 
meso-colon,  to  anastomose  with  the  superior  pancreatico-duodenal,  which  is  given 
off  from  the  gastro-duodenal,  and  descends  in  a  like  situation  beneath  the  ascend- 
ing layer  of  the  transverse  meso-colon. 

(2)  The  middle  colic,  arising  from  the  concavity  of  tlie  superior  mesenteric  a 
little  below  the  pancreas,  enters  the  transverse  meso-colon,  and  divides  into  two 
branches — one  of  which  passes  to  the  left  and  anastomoses  with  the  ascending 


Fig.  366. — The  Superior  Mesenteric  Artery  and  Vein. 
(The  colon  is  turned  up,  and  the  small  iutestines  are  drawn  over  to  the  left  side.) 


Left  colic  artery 

Superior  nifseii- 
teric  artery  and 
vein 


Ileo-colic  artery 


VERMIFORM 
APPENDIX 


]'asa  intestini 
tenuis 


SMALL  INTEST'NES 


branch    of    the    left    colic;    the   other,    winding    downwards   and    to   the   right, 
anastomoses  with  the  ascending  branch  of  the  right  colic. 

(3)  The  right  colic — sometimes  given  off  as  a  common  trunk  either  witli  the 
former  branch  or  with  the  ileo-colic — passes  to  the  right  behind  the  peritoneum  to 
the  back  of  the  ascending  colon,  Avhere  it  divides  into  an  ascending  branch,  Avhich 
anastomoses  with  the  descending  branch  of  the  middle  colic,  and  a  descending 
branch  which  anastomoses  with  the  ascending  or  colic  branch  of  the  ileo-colic. 

(4)  The  ileo-colic  descends  behind  the  peritoneum  towards  the  caecum,  where 
it  divides  into  a  colic  branch  which  tracks  ui)wards  beneath  the  peritoneum  to 
anastomose  with  the  descending  branch  of  the  right  colic;  and  into  an  ileac  branch 
which  passes  between  the  layers  of  the  mesentery  and  anastomoses  with  the 
termination  of  the  superior  mesenteric  artery. 


560  THE  ARTERIES 

From  the  anastomotic  loops  formed  between  the  termination  of  the  superior 
mesenteric,  the  ileo-coHc,  the  right  colic,  and  the  middle  cohc  arteries,  secondary 
loops  are  derived  whence  branches  pass  to  the  termination  of  the  ileum,  theca'cum, 
the  vermiform  appendix,  the  ascending  colon,  and  half  the  transverse  colon.  These 
branches  on  reaching  the  intestine  divide  into  two,  one  of  which  i)asses  in  front, 
and  the  other  behind  the  intestine,  and,  after  encircling  it,  anastomose  with  each 
other  and  with  the  neighl)ouring  circlets  above  and  below. 

(5)  The  intestinal  branches,  or  vasa  intestini  tenuis,  arise  from  the  convex 
side  of  the  superior  mesenteric,  and,  varying  from  twelve  to  sixteen  in  numl)er, 
radiate  in  the  mesentery,  where  each  divides  into  two  branches,  which  inosculate 
with  similar  branches  given  off  from  the  branch  above  and  below.  From  the 
primar}^  loops  thus  formed,  secondary  loops  are  derived  in  like  manner,  and  from 
these  tertiary,  and  at  times  quaternary,  or  even  quinary  loops.  From  the  ultimate 
loops  terminal  Ijranches  pass  on  to  the  intestine  through  the  triangular  interval  left 
at  the  spot  where  the  mesentery  is  reflected  on  to  tlie  nuiscular  coat  of  the  gut.  On 
reaching  the  Avail  of  the  gut  these  terminal  vessels  bifurcate,  the  two  branches 
encircling  the  intestine,  and  thus  forming  with  those  above  and  below  a  series  of 
vascular  rings  surrounding  the  small  intestine  throughout  its  whole  length.  These 
branches  of  the  superior  mesenteric  in  their  course  to  the  intestine  also  supply  the 
mesentery  and  the  mesenteric  glands. 

The  variations  in  the  superior  mesenteric  artery  are  numerous.  (A)  It  may  be  double.  (B) 
It  may  give  oif  accessory  brunches  to  the  liver,  stomach,  pancreas,  spleen,  and  gall-bladder.  (C) 
It  may  give  oif  branches  normally  derived  fiom  other  sources,  namely,  the  hepatic  or  its  right  or 
left  branch,  the  cystic,  the  gastro-duodenal  or  its  right  gastro-epiploic  branch,  the  gastric  or  the 
pancreatica  magna.  (D)  It  may  give  off  the  left  colic  and  su])erior  liEemorrhoidal,  thus  taking 
the  place  in  whole  or  in  ])art  of  the  inferior  mesenteric.  (E)  Its  colic  and  intestinal  branches 
may  vary  considerably  in  their  origin  and  course,  and  in  the  number  of  primary  and  secondary 
loops  that  they  form.  (F)  A  rare  abnormality  described  by  Hyrtl  is  the  persistence  of  an 
omphalo-mesenteric  artery  running  to  the  neighbourhood  of  the  umbilicus  and  giving  off  a  branch 
to  the  urachus,  or  a  branch  to  the  liver  through  the  falciform  ligament,  or  a  branch  to  the  rectus 
anastomosing  with  the  epigastrtc. 


THE  RENAL  ARTERIES 

The  renal  arteries  come  off  one  on  each  side  of  the  abdominal  aorta,  a  little 
below  the  superior  mesenteric  and  first  lumbar  arteries,  on  a  level  Avith  the  first 
lumbar  vertebra.  They  pass  transversely  outwards  across  the  crura  of  the  dia- 
phragm to  the  kidneys,  the  riglit  being  on  a  slightly  lower  plane  and  somewhat  longer 
than  the  left,  and  passing  bebind  the  inferior  vena  cava.  In  front  of  each  is  the 
corresponding  renal  vein.  Behind  each  at  the  hilum  of  the  kidney  is  the  com- 
mencement of  the  ureter.  Before  entering  the  kidney  the}-  lireak  up  into  three  or 
four  terminal  branches.  The  distribution  of  the  arteries  in  the  kidney  is  descrilied 
under  the  anatomy  of  that  organ. 

Each  renal  artery  gives  off  the  following  branches: — 

(a)  The  inferior  suprarenal,  Avhich  ascends  to  the  suprarenal  body. 

(/>)  The  capsular  or  peri-renal  branches  to  the  capsule  of  the  kidney  and 
peri- renal  fat. 

(c)  The  ureteral  branch  to  the  U})per  end  of  tlie  ureter. 

Variations  in  the  renal  arteries  are  common.  (A)  The  right  and  left  renal  may  arise  from 
the  aorta  by  a  common  stem.  (B)  They  may  arise  from  the  aorta  lower  than  usual ;  the  kidneys 
then  being  also  below  their  usual  situation.  (C)  There  may  be  several  renal  arteries  on  each  side, 
or  the  renal  artery  may  divide  close  to  its  origin  into  several  branches.  (I))  The  renal  artery  on 
one  or  both  sides  may  arise  from  the  bifurcation  of  the  aorta,  from  the  ctmimon  iliac,  the  internal 
iliac,  the  inferior  mesenteric,  or  the  middle  sacral  artery.  (K)  The  right  artery  may  cross  in  front 
of,  instead  of  l)eliin(],  the  vena  cava.  (F)  The  branches  of  the  renal  artery  may  perforate  the 
substance  of  the  kidney  instead  of  entering  at  the  hilum.  ((li )  The  renal  artery  may  give  origin 
to  branches  normally  derived  from  other  vessels,  as  tlie  phrenic,  the  hepatic  or  its  right  branch 
from  the  right  renal,  the  middle  sui)rarenal,  some  of  the  colic  arteries,  the  s])erniatic,  one  or  more 
of  the  lumbar  arteries,  or  the  greater  pancreatic  artery.  (H)  Accessory  renal  arteries,  varying  in 
size  and  generally  derived  from  the  aorta,  are  common.  Tliey  may  enter  the  kidney  at  almost 
any  ])art  of  the  organ. 


SUPRARENAL— SPERMATIC  561 


THE  SUPRARENAL  ARTERIES 

The  capsular  or  suprarenal  arteries  are  derived  from  three  sources,  and 
are  named  as  follows: — (1)  Superior  suprarenal;  (2)  middle  suprarenal;  and 
(3)  inferior  suprarenal. 

(1)  The  superior  suprarenals,  one  on  each  side,  are  usually  derived  from  tlie 
phrenics,  and  clescend  to  the  su})rarenal  bodies. 

(2)  The  middle  suprarenals,  or  suprarenals  proper,  come  off  one  on  each  side 
from  the  aorta,  just  above  the  first  lumbar  artery,  and  pass  transversely  outwards 
to  the  suprarenal  bodies,  across  the  crura  of  the  diaphragm  a  little  above  the  renal 
arteries.  In  the  fcjetus  they  equal  the  renals  in  size.  In  the  adult  they  are  mucli 
smaller. 

(3)  The  inferior  suprarenals  are  branches  of  the  renals.  They  ascend,  one  on 
each  side,  to  the  suprarenal  bodies. 

The  suprarenal  veins,  usually  one  on  each  side,  terminate  as  a  rule  on  the  left 
side  in  the  left  renal;  on  the  right  side,  in  the  inferior  vena  cava. 

For  the  distribution  of  the  suprarenal  vessels  within  the  suprarenal  capsules,  see 
page  1014. 

THE  SPERMATIC  ARTERIES 

The  spermatic  arteries  come  off  from  the  front  of  the  abdominal  aorta. 
They  diverge  from  each  other  as  they  descend  over  the  aorta  and  psoas  muscle  to 
the  deep  or  internal  abdominal  ring,  where  they  are  joined  by  the  vas  deferens, 
and,  passing  with  it  through  the  inguinal  canal  and  out  of  the  external  or 
superficial  abdominal  ring,  run  downwards  into  the  scrotum  in  a  tortuous  course 
to  the  testicle.  They  terminate  in  branches  to  the  epididymis  and  bocl}-  of  that 
organ.  Within  the  abdomen  they  lie  beneath  the  peritoneum,  and  cross  in  their 
descent  over  the  ureter  and  distal  end  of  the  external  iliac  artery;  the  right  being 
superficial  to  the  vena  cava,  and  behind  the  termination  of  the  ileum;  and  the 
left  beneath  the  sigmoid  flexure  of  the  colon.  In  the  inguinal  canal  and  in 
the  scrotum  the  spermatic  veins  lie  in  front  of  the  artery,  and  the  vas  deferens  lies 
behind  it. 

In  the  foetus  these  vessels  pass  transversely  outw^ards  to  the  testicle,  which  in 
early  foetal  life  lies  in  the  loin  in  front  of  the  kidney;  but  as  the  testicles  descend  to 
the  scrotum,  the  vessels  become  elongated,  and  are  drawn  with  the  testicle  into  the 
scrotum. 

The  spermatic  arteries  give  off  the  following  branches: — (1)  Ureteral;  (2)  cre- 
masteric;  (3)  epididymal;  and  (4)  testicular. 

(1)  The  ureteral  are  small  branches  given  off  to  the  ureter  as  the  si")ermatic 
artery  crosses  it.  They  anastomose  with  the  other  ureteral  branches  derived  from 
the  renal,  common  iliac,  and  vesical  arteries. 

(2)  The  cremasteric  are  small  branches  given  off  to  the  cremaster  muscle; 
they  anastomose  with  the  cremasteric  branch  of  the  deep  epigastric. 

(3)  The  epididymal  are  distributed  to  the  epididymis,  and  anastomose  Mith 
the  artery  of  the  vas. 

(4)  The  testicular  are  the  terminal  branches  of  the  spermatic;  they  perforate 
the  tunica  albuginea  posteriorly,  and  are  distributed  to  the  body  of  the  organ  in 
the  way  mentioned  in  the  section  on  the  Testicle. 

Chief  variations  in  the  spermatic  arteries. — (A)  One  or  both  may  be  wanting,  the  testide 
being  then  supplied  by  branches  from  the  vesical  or  prostatic  arteries  jiassing  under  the  arch  of 
the  pubis.  (B)  One  or  both  may  arise  from  the  renal,  more  rarely  from  the  suprarenal.  (C) 
One  may  come  off  higher  tliaii  the  other.  (D)  They  may  come  off  from  a  common  stem.  (E) 
One  or  both  may  be  double  in  the  whole  or  part  of  "their  course.  (F)  The  right  spermatic  may 
run  behind  instead  of  in  front  of  the  inferior  vena  cava. 


36 


562  THE  ARTERIES 


THE  OVARIAN  ARTERIES 

The  ovarian  arteries  are  the  honiologues  of  the  spermatic  arteries  in  the  male, 
and  correspond  in  their  relations  in  the  ui)per  part  of  their  course.  Tliey  diverge 
somewhat  less  however,  and  on  reaching  the  level  of  the  connnon  iliac  artery  turn 
inwards  over  that  vessel  and  descend  tortuously  into  the  pelvis  hetween  the  folds 
of  the  Inroad  ligament  to  the  ovaries.  In  the  broad  ligament  the  ovarian  artery  lies 
below  the  Fallopian  tube,  and  on  reaching  the  ovary  turns  backwards  and  sujjplies 
that  organ  (fig.  370). 

They  give  off  the  following  branches: — (1)  Ureteral;  (2)  Fallopian;  (3)  uterine; 
and  (4)  ligamentous. 

(1)  The  ureteral  is  distributed,  as  in  tlie  male,  to  the  ureter. 

(2)  The  Fallopian  supplies  the  istlnnus  and  ampulla  of  the  Falloi)ian  tu])e  and 
its  fimbriated  extremity. 

(3)  The  uterine  runs  along  the  Fallopian  tulje  to  the  superior  cornu  of  the 
uterus,  which  it  supplies,  together  -with  the  upper  jtart  of  the  fundus  uteri,  and 
anastomoses  with  the  uterine  arteries  from  the  internal  iliac. 

(4)  The  ligamentous  is  distributed  to  the  round  ligament,  passing  with  that 
structure  through  the  inguinal  canal,  and  anastomosing  with  the  cremasteric  and 
superficial  external  pudic  arteries. 

Like  the  spermatic,  the  ovarian  arteries  in  the  foetus  come  off  at  right  angles  to 
the  aorta,  and  pass  transversely  outwards  to  the  ovaries,  which  are  formed,  as  are 
the  testicles,  in  the  right  and  left  loin  in  front  of  the  kidneys.  They  elongate  as 
the  ovaries  descend  into  the  pelvis.  During  pregnancy  these  arteries  undergo  great 
enlargement. 

THE  INFERIOR  MESENTERIC  ARTERY 

The  inferior  mesenteric  artery,  smaller  than  the  superior,  arises  from  the 
front  of  the  al)dominal  a(jrta  about  an  inch  and  a  half  above  the  bifurcation  of  that 
vessel.  It  runs  oblicpiely  downwards  and  to  the  left,  across  the  lower  part  of  the 
abdominal  aorta  and  then  over  the  left  psoas  muscle  and  left  common  iliac  artery, 
descends  into  the  pelvis  l:)etween  the  layers  of  the  meso-rcctum,  and  terminates  on 
the  rectum  in  the  superior  hemorrhoidal  or  superior  rectal  artery.  It  at  first  lies 
behind  the  peritoneum,  or  in  the  left  lumbar  meso-colon  Avhen  that  structure  is 
})resent.  It  supplies  the  lower  half  of  the  large  intestine.  Its  vein  lies  at  first  close 
to  the  left  side,  but  soon  passes  upwards  on  the  psoas,  away  from  the  artery,  to 
end  in  the  splenic  vein  (fig.  367). 

The  branches  of  the  inferior  mesenteric  are: — (1)  The  left  colic;  (2)  the 
sigmoid;  and  (3)  the  superior  hemorrhoidal. 

(1)  The  left  colic  runs  transversely  outwards  and  to  the  left,  1)eneath  the  peri- 
toneum, and  divides  into  two  Ijranches,  one  of  which,  entering  the  transverse  meso- 
colon, ascends  upwards  and  to  the  right,  to  anastomose  with  the  middle  colic.  The 
other  descends,  and,  entering  the  sigmoid  meso-colon,  anastomoses  with  the 
ascending  branch  of  the  sigmoid  artery. 

The  distribution  of  this  artery  and  the  next  to  the  colon  is  similar  to  that  of 
the  colic  branches  of  the  superior  mesenteric,  and  does  not  require  a  separate 
description.     (See  Superior  Mesenteric  Artery,  pages  559,  560.) 

(2)  The  sigmoid  artery  runs  downwards  and  to  the  left  over  the  psoas  muscle, 
and,  entering  the  sigmoid  meso-colon,  divides  into  two  liranches;  the  ui)per  anasto- 
mosing with  the  left  colic,  the  lower  with  the  superior  luemorrhoidal. 

(3)  The  superior  haemorrhoidal  is  the  continued  trunk  of  the  inferior  mesen- 
teric. It  descends  into  the  pelvis,  behind  the  rectum,  between  the  layers  of  the 
meso-rectum.  On  reacliing  the  wall  of  the  bowel  it  l)ifurcates,  one  branch  proceed- 
ing on  either  side  of  the  gut,  to  within  four  or  five  inches  of  the  anus.  Here  each 
again  divides,  and  the  branches,  piercing  the  muscular  coat,  descend  between  that 
coat  and  the  mucous  membrane,  forming  with  each  other,  and  with  the  middle 
hcDmorrhoidal  arteries — derived  from  the  internal  iliac — a  series  of  small  vessels, 
running  longitudinally  to  the  rectum,  and  ])arallel  to  each  other  as  far  as  the  level 


INFERIOR  MESENTERIC— MIDDLE  SACRAL 


563 


of  till'  internal  spliineter,  wIktc,  l)y  their  anastomosis,  they  form  a  series  of  loops 
an^und  the  lower  }tart  of  the  reetum. 

The  chief  variations  in  the  inferior  mesenteric  arc  : — (A)  Its  place  may  be  supplied  by  the 
superior  meseutcric.     (1>)   It  may  give  branches  tu  the  liver  or  kiduey.     (C)  It  may  give  off  the 


Fig.  367. — Thk  Inferior  Mesknteric  Artery  and  Veix. 
(The  colon  is  turned  up,  aud  the  small  iutestines  are  drawn  to  the  right  side.) 


Middle  colic  arlerti  — 


Inferior  pancreatico- 
duodenal artery 
Superior  mesenteric 
artery 
Riijht  colic  artery 


Abdominal  aorta 
Vena  cava  inferior 


Right  common  iliac 

artery 

Middle  sacral  artery 

and  vein 


Left  colic  artery 

Inferior  mesenteric 
vein 

Inferior  nn'senleric 

uriery 
Left  colic  artery 

Inferior  vifsenteric 

artery 


Left  common  iliac 
rem 

■'iiymoid  artery 


Superior  htemor- 
r/ioidai  artery 


middle  colic.  (D)  It  may  give  off  a  stem  to  both  umbilical  arteries.  (E)  The  anastomosis  between 
the  middle  aud  left  colic  arteries  maybe  wanting — the  normal  condition  in  the  rumiiianls  and  the 
porcupines. 


C.  The  Terminat.  Branches  of  the  Aedomixae  Aorta 


THE  MIDDLE  SACRAL  ARTERY 

The  middle  sacral  artery  is,  anatomically,  the  continuation  of  the  aorta,  and 
is  generally  l)nt  not  universally  held  to  be  the  homologue  of  the  sacral  and  coccygeal 
aorta  of  some  animals.  The  so-called  coccygeal  glomerulus,  or  Luschka's  gland,  in 
Avhich  it  terminates,  is  l:)elieved  to  contain  the  rudiments  of  the  caudal  aorta,  or 
artery  of  the  tail.  The  artery  is  mesially  j)laced,  and  extends  from  the  bifurcation 
of  the  aorta  to  the  tip  of  the  coccyx.  As  itj^asses  downwards  into  the  pelvis,  it  runs 
behind  the  left  common  iliac  vein,  the  hypogastric  plexus  of  the  syinjiathetic  nerve, 
and  the  layer  of  peritoneum  that  descends  from  the  mesentery  into  the  pelvis  to 
become  the  meso-rectum.  It  lies  successively  upon  the  intervertebral  disc  between 
the  fourth  and  fifth  lumbar  vertebrae,  the  fifth  lumbar  vertel)ra,  the  intervertebral 
disc  between  that  vertel)ra  and  the  sacrum,  and  lower  down  upon  the  middle  of 
the  anterior  surface  of  the  sa(,-rum  and  coccvx. 


564  THE  ARTERIES 

Branches. — The  middle  sacral  gives  off: — 

(1)  The  fifth  pair  of  lumbar  arteries  ( soiiietimes).  These  are  described  with 
the  lumbar  arteries. 

(2)  Lateral  sacral  branches,  usually  four  in  number.  These  are  serially 
homologous  with  the  intercostal  and  lumbar  arteries  given  off  l)y  the  aorta.  They 
run  more  or  less  transversely  outwards,  and  anastomose  with  the  lateral  sacral 
branches  of  the  internal  iliac  artery.  They  give  off  small  spinal  branches,  which 
pass  through  the  sacral  foramina,  and  supply  the  sacral  canal  and  back  of  the 
sacrum. 

(3)  Rectal  or  haemorrhoidal  branches  pass  forwards  in  the  la3'ers  of  the  meso- 
rectum,  to  the  rectum  which  they  help  to  supply,  and  anastomose  with  the  other 
haemorrhoidal  or  rectal  arteries. 

On  the  lower  part  of  the  middle  sacral  artery — the  coccygeal  part — there  are 
often  found  small  pouches  or  A^aricosities,  Avhich  are  believed  by  some  to  represent 
the  rudiments  of  lateral  coccygeal  arteries,  homologous  to  the  intercostal,  lumbar, 
and  sacral  arteries,  given  off  from  the  aorta  in  these  regions. 

The  variations  of  this  vessel  are  uniixiportaut.  (A)  The  most  frequent  perhaps  is  for  it  to 
come  off  from  the  back  of  the  aorta  a  little  above  tlie  bifurcation  ;  or  (B)  froui  one  or  other  of 
the  common  iliacs  ;  or  (C)  as  a  common  trunk  with  what  are  usually  its  blanches,  the  fifth 
pair  of  lumbar  arteries.  (D)  It  sometimes  gives  off  an  accessory  renal  arter.v — a  fact  of  inter- 
est, in  that  the  kidneys  occujiy  a  lower  position  in  the  abdomen  in  some  animals  than  in  man. 


THE  COMMON  ILIAC  ARTERIES 

The  common  iliac  arteries  must  be  regarded  as  the  terminal  branches  of  the 
abdominal  aorta,  unless  the  middle  sacral  and  the  artery  of  the  tail  in  the  loAver 
animals  are  regarded  as  the  continuation  of  the  al)dominal  aorta.  The  common  iliacs 
arise  opposite  the  left  side  of  the  middle  of  the  body  of  the  fourth  lumbar  vertebra, 
at  the  bifurcation  of  the  abdominal  aorta,  and,  diverging  from  each  other  in  the 
male  at  about  an  angle  of  60°,  and  in  the  female  at  an  angle  of  68°,  terminate 
opposite  the  lumbo-sacral  articulation  by  bifurcating  into  the  external  iliac,  which 
is  continued  along  the  brim  of  the  pelvis  to  the  lower  limb,  and  into  the  internal 
iliac,  which  passes  over  the  brim  of  the  pelvis  and  descends  into  that  cavity. 
Both  arteries  lie  on  the  fifth  luml:)ar  vertebra,  are  covered  l_iy  the  peritoneum,  and 
are  crossed  by  the  ureter,  and  in  the  female,  in  addition,  by  the  ovarian  arteries. 

The  relations  of  the  arteries  differ  slightly  on  the  two  sides,  and  may  be  con- 
sidered separately. 

The  Right  Common  Iliac  Artery 

The  right  common  iliac  measures  about  tAvo  inches  in  length  (5  cm.),  and  is 
rather  longer  than  the  left,  in  consequence  of  the  aorta  bifurcating  a  little  to  the 
left  of  the  median  line. 

Relations. — In  front  it  is  covered  by  the  peritoneum,  and  is  crossed  by  the 
right  ureter  a  little  before  its  l)ifurcation,  by  the  ovarian  artery  in  the  female,  l)y 
the  termination  of  the  ileum,  by  the  terminal  branches  of  the  superior  mesenteric 
artery,  and  by  branches  of  the  SAnnpathetic  nerve  descending  to  the  hypogastric 
plexus. 

Behind,  it  lies  on  the  right  common  iliac  A'cin,  the  end  of  the  left  common  iliac 
A'ein,  and  the  commencement  of  the  inferior  A'ena  caA'a,  Avhich  se]>arate  it  from  the 
fourth  and  fifth  lumljar  vertebrae  and  their  intervening  disc,  the  psoas  nniscle,  and 
the  sympathetic  nerA'e;  Avhilst  still  deeper  in  the  groove  betAveen  the  fifth  lumliar 
A'ertebra  and  the  psoas  are  the  lumbo-sacral  cord,  the  obturator  nerve,  and  the  ilio- 
lumbar artery. 

To  the  right  side  are  the  beginning  of  the  inferior  vena  cava,  the  end  of  the 
right  common  iliac  vein,  and  the  psoas  muscle,  Avhich,  hoAvever,  is  separated  from 
the  artery  by  the  inferior  vena  cava  at  its  upper  part. 

To  the  left  side  are  the  right  common  iliac  A^ein,  the  termination  of  the  left 
common  iliac  vein,  and  the  hypogastric  plexus. 


COMMOX  ILIAC  565 

It  \\  ill  be  thus  seen  that  the  right  common  iliac  artery  crosses  both  common 
iliac  veins,  and  that  its  own  vein,  the  right,  is  at  first  a  little  to  the  left  side,  l)ut, 
as  it  ascends,  i»asses  beneath  it,  and  gets  a  little  to  the  right  side.  Since  the  bifur- 
cation of  the  vena  cava  is  a  little  lx4o\v  and  to  the  right  side  of  the  l)ifurcation  of 
the  aorta,  it  follows  that  the  right  common  iliac  artery  lies  on  the  conmiencement 
of  the  vena  cava. 

The  Left  Coimmon  Iliac  Artery 

The  left  common  iliac  artery,  one  inch  and  three-quarters  in  length  (4  cm.), 
is  a  little  shorter  and  thicker  than  the  right. 

Relations. — In  front  it  is  covered  by  the  peritoneum,  which  separates  it  from 
the  intestines,  and  is  crossed  by  the  ureter,  the  ovarian  artery  in  the  female, 
branches  of  the  sympathetic  nerve  descending  to  the  hypogastric  plexus,  the  termi- 
nation of  the  inferior  mesenteric  artery,  the  sigmoid  flexure,  and  the  sigmoid 
meso-colon. 

Behind  are  the  lower  border  of  the  body  of  the  fourth  lumbar  vertebra,  the  disc 
betwcL-n  the  fourth  and  fifth  lumbar  vertebrae,  the  body  of  the  fifth  lumbar 
vertebra,  and  the  disc  between  it  and  the  sacrum.  Crossing  deeply  behind  the 
artery  between  the  fifth  lumbar  vertebra  and  the  psoas,  is  the  obturator  nerve,  the 
luml)0-sacral  cord,  and  the  ilio-lumbar  artery. 

To  the  left  side  is  the  psoas  muscle. 

To  tlie  right  side  are  the  left  common  iliac  vein,  the  hypogastric  plexus,  and 
the  middle  sacral  arterv. 


Variations  in  the  Common  Iliac  Arteries 

(A)  The  cotumon  iliac  arteries  may  be  longer  or  shorter  than  here  described.  Thej-  liave 
been  found  as  short  as  half  an  inch,  or  as  long  as  four  and  a  half  inches,  but  the  usual  limit  is 
something  between  one  and  a  half  to  three  inches.  This  variation  in  the  length  of  the  vessels 
may  depend  upon  the  aorta  bifurcating  above  or  below  tlie  usual  spot,  or  upon  the  common  iliac 
arteries  dividing  higher  or  lower  than  usual.  A  low  bifurcation  of  the  aorta  is  somewhat  more 
comuion  than  a  high  bifurcation,  as  is  also  the  case  with  the  common  iliacs.  (B)  The  common 
iliacs  may  be  absent,  the  external  and  internal  iliacs  then  arising  together  from  the  end  of  the 
aorta.  (C)  Either  artery  may  give  off  a  large  branch,  such  as  tlie  ilio-lumbar,  the  lateral  or  the 
middle  sacral,  .sometimes  a  lumbar,  or  occasionally  an  accessory  renal  arterj'. 

Collateral  Circulation 

The  collateral  circulation  after  obstruction  or  ligature  of  the  common  iliac  artery  is  carried 
on  chiefly  (fig.  374)  by  the  anastomosis  of  the  middle  sacral  with  the  lateral  sacral;  the  internal 
mammary  with  the  epigastric  ;  the  lumbar  arteries  of  the  aorta  with  the  ilio-lumbar  and  deep 
circumflex  iliac  ;  the  pubic  branch  of  the  epigastric  with  the  jaibic  branch  of  tlie  obturator  ; 
the  posterior  branches  of  the  sacral  arteries  with  the  gluteal  ;  the  superior  hajmorrhoidal  from 
the  superior  mesenteric,  with  the  hjemorrhoidal  branches  of  the  internal  iliac  and  jmdic  ;  the 
ovarian  arteries  from  the  aorta  with  the  uterine  branches  of  the  internal  iliac  ;  and  by  the 
anastomosis  across  the  middle  line  of  the  jmbic  branch  of  the  obturator  with  the  like  vessel  of 
the  opjwsite  side  ;  the  lateral  sacral  with  the  opposite  lateral  sacral ;  and  the  vesical,  hsemor- 
rhoidal,  uterine,  and  vaginal  branches  of  the  internal  iliac  with  the  corresponding  branches  of 
the  opposite  internal  iliac. 


Branches  of  the  Common  Iliac  Artery 

The  branches  of  the  common  iliac  artery  are: — (1)  Peritoneal  and  sub- 
peritoneal;  (2)  ureteral:   ^-'5)   iiitti-n;il  iliac;  and  (4)  external  iliac. 

(1)  The  peritoneal  and  subperitoneal  are  distriiiuted  to  the  peritoneum  and 
subperitoneal  fat.  They  anastomose  with  like  vessels  given  off  from  the  lumbar, 
phrenic,  and  renal  arteries,  forming  a  suljperitoneal  arterial  anastomosis.  They 
are  very  small  and  unimportant. 

(2)  The  ureteral  are  .small  insignificant  twigs  given  off  to  the  ureter  as  that 
duct  crosses  the  artery.  They  anastomose  with  the  ureteral  arteries  given  off  from 
the  si3ermatic  above,  and  with  those  derivcil  from  the  vesical  arteries  below. 


566 


THE  ARTERIES 


(3)  THE  IXTERXAL  ILIAC  ARTERY 

The  internal  iliac  artery  arises  at  the  bifurcation  of  the  coniiiion  ihae  opposite 
the  hmibo-sacral  articulation.  It  descends  into  the  pelvis  for  al>out  an  incli  and  a 
quarter  (3  cm.),  and  then  divides,  opposite  the  upper  margin  of  the  great  sacro- 
•  sciatic  foramen,  into  an  anterior  and  a  posterior  brancli. 


Fig.  .368. — Side  View  of  Pelvis  axd  Upper  Third  of  Thigh,  with  the  External 
Iliac,  Ixterxal  Iliac,  axd  Femoral  Arteries  axd  their  Branches,  Left  Side. 

(From  a  dissection  by  W.  J.  Walsliani  iu  tlie  Museum  of  St.  Bartholomew's  Hospital.) 

The  bladder  is  hooked  over  to  expose  back  of  pelvis. 

Common  iliac  arlcry 
SYMPATHETIC  yERVE 
Middle  sacral  artery 


Common  iliac  lein 

URETER 

Internal  itiac  aitery 

External  iliac  i  em 

Exttrnal  iliac  ai  t>  i v 
Posterior  branch  of  internnl  lUac  diudiiic/  into 
gluteal  and  ilio-himlar  arteries 

Latnal  iucial  mlf 
SACRAL  PLEXUS 
OBTURATOR  XER^  E 
Ohttiratoi  ailuy 
Obliterated  hypogastric 
Superior  vesical  artery 
£!dge  of  levator  ani 

Pudic  artery 

BLADDER 

Middle  vesical  artery 

Deep  epigastric  artery 
Pubic  branclt  of  epi- 
gastric artery 
Common  femoral  artery  — 

Long  snphenovs  rein  — 
PeetineuB  ruusele 

ObtHialni  lilt 

Adductor  magnua 

Internal  cii  c  iimfli  r  ai  I  i  u 

Adductor  brevia 

OBTURATOR  XERVE  (ant.  hrnnch) 

Profunda  artery 

Adductor  longus,  hooked  aside 

Superficial  femoral  artery  and  rein 


Gracilis  muscle 
Lower  part  of  sartorius 


Psoaa  muscle 

Ilio-lumbar  artery 

EA'TERXAL  CUTA- 
XEOUS  XERVE 

Iliacus  muscle 

GEXITO-CRURAL 
XERVE 

AXTERIOR  CRU- 
RAL XERVE 


Deep  circiinifiex  iliac 

artery 
Superficial  circumflex 

iliac  artery 
AXTERIOR  CRVRAL  X. 
Gluteal  artery  and 

stiperior  gluteal  iteri'e 
Tensor  faciae  temoris 

t hooked  asidei 
Gluteus  raedius  and 

minimus 
Sartorius  muscle 
MIDDLE  <UTA- 
XEO  US  XERVE 

XERVE  TO  RECTUS 

XERVE  TO  VASTVS 

E-YTERXl'S 
Eilernal  circuiiifiex  nr. 
XERVE  TO  CRfREfS 
Rectus,  hooked  aside 

Profuiiit.i   cti,, 

LOXti  SAPHEXOUS 
XERVE  AXD 
NERVE  TO  VAS- 
TUS IXTERXUS 


Relations. — Behind,  it  rests  on  the  termination  of  the  external  iliac  vein,  the 
internal  iliac  vein,  the  inner  margin  of  the  psoas  muscle,  the  luml)0-sacral  cord,  the 
obturator  nerve,  and  the  sacrum. 

In  front  it  is  covered  by  the  peritoneum,  and  is  crossed  by  tbc  ureter. 

In  the  adult  the  internal  iliac  is  smaller  than  the  external  iliac;  but  in  the  foetus 
the  internal  is  much  larger  than  the  external,  and  is,  together  with  its  anterior 
branch,  the  vessel  by  which  the  Idood  is  returned  to  the  placenta.      In  early  fa^tal 


LXTERXA  L   ILIA  C—ILIO- L  UMBA R  567 

life  it  (Iocs  not  descend  into  the  ju'lvis,  Imt  courses  al)Ove  the  i)elvic  hrim  by  the  side 
of  the  allantois,  and  later  by  the  side  of  the  l)ladder  and  urachiis,  to  the  umbilicus, 
under  the  name  of  the  hypogastric  artery.  At  the  umbilicus  it  is  joined  by  the 
umbilical  vein,  and  by  the  hypogastric  artery  of  the  oi)}iosite  side.  The  two  arteries, 
now  known  as  the  umbilical,  coil  spirally  round  the  vein  on  their  way  to  the 
placenta,  forming  the  umbilical  cord  (tig.  3(58).  After  birth  the  hypogastric  artery 
ceases  to  be  pervious  beyond  the  superior  vesical  branch,  and  is  converted  into  a 
fibrous  cord,  the  obliterated  hypogastric  artery. 

Variations. — (A)  The  internal  iliac  may  be  lunger  or  shorter  than  usual.  It  is  seldom  less 
than  an  inch  in  length,  but  has  been  met  with  as  short  as  half  an  inch,  and  as  long  as  three 
inches.  The  variation  in  length  generally  depends  upon  the  length  of  the  common  iliac  ;  when 
this  bifurcates  higher  than  usual,  the  internal  iliac  is  then  longer,  and  maj'  lie  at  first  above  the 
brim  of  the  pelvis ;  but  the  length  may  also  depend  ujKjn  the  artery  itself  dividing  higher  or 
lower  than  usual  into  its  branches.  This  division  may  occur  anywhere  between  the  brim  of  the 
pelvis  and  the  upper  border  of  the  sacro-sciatic  foramen.  (B)  Its  branches  may  be  given  off 
without  the  arteiy  dividing  into  an  anterior  and  a  posterior  division,  or  one  or  more  branches  may 
arise  above  the  division. 

The  branches  of  the  posterior  division  of  the  internal  iliac  are: — (1)  The 
ilio-luml)ar;   (2)  the  lateral  sacral:  and  ('■-))  the  gluteal. 

The  branches  of  the  anterior  division  are: — (l)The  hypogastric;  (2)  the 
sui)erior,  middle,  and  inferior  vesical:  ( o j  the  middle  hemorrhoidal;  (4)  the 
uterine;  (5)  the  vaginal;  (6)  the  obturator;  (7)  the  sciatic;  and  (8)  the  internal 
pudic. 


Branches  of  the  Posterior   Division  of   the    Internal   Iliac  Aetery 

1.    THE   ILIO-LUMBAR  ARTERY 

The  ilio-lumbar  artery — a  short  vessel  coming  off  from  the  posterior  part  of 
the  internal  iliac  artery — runs  upwards  and  outAvards  beneath  the  common  iliac 
artery,  fir.st  between  the  lumbo-sacral  cord  and  obturator  nerve,  and  then  between 
the  psoas  muscle  and  the  vertebral  column.  On  reaching  the  brim  of  the  pelvis  it 
divides  into  two  branches,  an  iliac  and  a  lumbar.  The  iliac  branch  passes  out- 
wards beneath  the  psoas  and  anterior  crural  nen-e  and,  perforating  the  iliacus, 
ramifies  in  the  iliac  fossa  between  that  muscle  and  the  bone.  It  supplies  a  nutrient 
artery  to  the  bone,  and  then  breaks  up  into  several  branches  which  radiate  from 
the  parent  trunk,  upwards  towards  the  sacro-iliac  synchondrosis,  outwards  towards 
the  crest  of  the  ilium,  downwards  towards  the  anterior  superior  spine,  and  inwards 
towards  the  pelvic  cavity.  The  first  anastomoses  with  the  last  lumbar;  the  second 
with  the  external  circumflex  and  gluteal;  the  third  with  the  deep  circumflex  iliac 
from  the  external  iliac;  the  fourth  with  the  iliac  branch  of  the  obturator.  The 
lumbar  branch  ascends  beneath  the  psoas,  and.  sui>plying  that  muscle  and  the 
(luailratus  lumborum,  anastomoses  with  the  last  lumbar  artery.  It  sends  a  branch 
into  the  spinal  canal  through  the  intervertebral  foramen  between  the  last  lundiar 
vertebra  and  the  sacrum,  which  anastomoses  with  the  other  spinal  arteries.  The 
ilio-lumbar  artery  is  serially  homologous  with  the  lumbar  arteries.  Hence  the 
similaritv  in  its  course  and  distriV)Ution. 


2.  THE  LATERAL  SACRAL  ARTEIHES 

The  lateral  sacral  arteries,  usually  two  in  number,  arise  from  the  posterior 
division  of  the  internal  iliac.  The  superior  artery,  when  two  are  present,  runs 
downwards  and  inwards  to  the  first  anterior  sacral  foramen,  through  which  it 
passes;  and,  after  supplying  the  spinal  membranes  and  anastomosingwith  the  other 
spinal  arteries,  passes  through  the  first  posterior  sacral  foramen,  and  is  distributed 
to  the  skin  over  the  back  of  the  sacrum,  there  anastomosing  with  branches  of  the 
gluteal  and  sciatic  arteries.     The  inferior  lateral  sacral  descends  on  the  side  of 


568 


THE  ARTERIES 


the  sacrum,  external  to  the  sacral  chain  of  the  sympathetic,  and  internal  to  the 
anterior  sacral  foramina,  crossing  in  its  course  the  slij^s  of  origin  of  the  pyriformis 
muscle  and  the  first  anterior  sacral  nerve.  On  reaching  the  coccyx  it  anastomoses 
in  front  of  that  bone  with  the  middle  sacral  arter}',  and  with  the  inferior  lateral 
sacral  of  the  opposite  side.  In  this  course  it  gives  off: — Posterior  or  spinal 
branches,  which  enter  the  second,  third,  and  fourth  anterior  sacral  foramina,  and, 
after  supplying  the  spinal  memliranes  and  anastomosing  with  each  other,  leave  the 
spinal  canal  l:)y  the  corresponding  posterior  sacral  foramina,  and  are  distributed  to 


Fig.  369. — The  Gluteal  Region,  with  the  Glvteal,  Sciatic,  and  Prmc  Arteries. 

(From  a  dissection  by  W.  J.  Walsham  in  St.  Bartholomew's  Hospital  ^Museum.) 

The  inferior  gluteal  branch  of  the  sciatic  artery  has  been  drawn  inwards  over  the  tuber  ischii  with  the 
reflected  origin  of  the  gluteus  maximus  muscle. 

Gluteus  medius,  turned  up 
INFERIOR  GLUTEAL  NERVE       ,   Gluteus  minimus 


Gluteus  maximus,  cut 
Internal  circurnjlex  artery 
Obturator  externus 


Insertion  of  gluteus  medius 
External  circurnjlex  aiteii/ 


}Iiiscii!ar  branches  of  sciatic  artery 
Deep  branch  of  gluteal  artery 

.SUPERIOR  GLUTEAL  NERVE 


Pyriformis  perforated  by  peroneal 
portion  of  sciatic  nerve 


Cut  edge  of  gluteus  maximus 


Puilii  nitpjyand  nerve  and  nerve 
to  obturatoi  internus 
Sciatic  artery 


Insertion  of 

gluteus  maximus 

First  perforating  arferi/ 

Quadratus  femoris 


Branch  of  internal  cirrumjleT  artery 
Obturator  internus  with 'the  two  gemelli 


I    Semi-tendinosus 
Semi-membranosus 


LESTER  SCIATIC  NERVE 
Arteria  nerri  comes  ischiatici 
POPLITEAL  PORTION  OF  GREA  TSCIA  TIC  NER  VE 
I    LONG  PUDENDAL  NERVE 
PERONEAL  PORTION  OF  GREAT  SCIA  TIC  NERVE 


the  muscles  and  skin  over  the  back  of  the  sacrum:  anterior  or  rectal  branches 
which  run  forward  to  the  rectum;  external  branches  which  are  distri))uted  to  the 
pyriformis,  coccygeus,  and  the  sacral  nerves;  and  internal  branches  wliich  pass 
inwards  across  the  sacrum  to  anastomose  with  l)ranches  of  the  middle  sacral  artery. 
At  times  the  lateral  sacral  arteries  are  exceedingly  small,  the  spinal  branches 
then  coming  chiefly  from  the  middle  sacral.  The  anastomosing  branches  between 
the  lateral  sacral  and  middle  sacral  are  usually  regarded  as  sacral  arteries  dimin- 
ished in  size,  and  serially  homologous  with  the  lumbar  and  intercostal  arteries. 


GL  UTEA  L— HYPOGASTRIC—  VESICAL  569 


3.  THE  GLUTEAL  ARTERY 

The  gluteal  artery,  the  largest  Ijranch  of  the  posterior  division  of  the  internal 
iliac,  e<jni(-s  off  as  a  short,  thick  trunk  from  the  outer  and  back  part  of  that  vessel 
of  which  indeed  it  may  be  regarded  as  the  continuati(jn.  Passing  backwards 
Ijetween  the  first  sacral  nerve  and  the  lumbo-sacral  cord  through  an  osseo-tendinous 
arch  formed  hy  the  margin  of  the  bone  and  the  upper  edge  of  the  pelvic  fascia,  it 
leaves  the  pelvis  through  the  great  sacro-sciatic  foramen  above  the  pyriformis  muscle 
in  company  with  its  vein  and  the  superior  gluteal  nerve.  At  its  exit  posteriorly 
from  the  great  sciatic  foramen  it  lies  under  cover  of  the  gluteus  maximus  and 
beneath  the  gluteal  vein,  and  in  front  of  the  superior  gluteal  nerve.  It  here  breaks 
up  into  two  chief  branches,  a  superficial  and  a  deep.  Its  emergence  from  the 
l»elvis  is  indicated  on  the  surface  l)y  a  point  situated  at  the  junction  of  the  })Osterior 
with  the  middle  third  of  a  line  drawn  from  the  anterior  superior  to  the  posterior 
superior  spine  of  the  ilium. 

Branches  of  the  gluteal  artery: — 

(a)  ^A^ithin  the  pelvis,  branches  are  distributed  to  the  obturator  internus,  the 
pyriformis,  the  levator  ani,  the  coccygeus,  and  the  pelvic  bones. 

(b)  External  to  the  pelvis,  the  artery  divides  into  a  superficial  and  deep 
branch. 

(i)  The  superficial  branch  breaks  up  into  a  number  of  large  vessels  for  the 
supply  of  the  upper  i)orti<jn  of  the  gluteus  maximus,  some  of  them  piercing  the 
muscle  and  supplying  the  skin  over  it,  and  anastomosing  Avith  the  posterior 
branches  of  the  lateral  sacral  arteries;  whilst  one  of  larger  size,  emerging  from  the 
muscle  near  the  iliac  crest,  anastomoses  with  the  deep  circumflex  iliac  artery.  The 
lower  branches  to  tlie  muscle  anastomose  with  l^ranches  of  the  sciatic. 

(ii)  The  deep  branch  subdivides  into  a  superior  and  an  inferior  branch.  («)  The 
superior  skirts  along  the  line  of  origin  of  the  gluteus  minimus,  Ijetween  the  gluteus 
medius  and  the  l)one,  and,  emerging  in  front  from  l^eneath  these  muscles  umhn* 
cover  of  the  tensor  fasciae  femoris  (fig.  368),  anastomoses  with  the  ascending  branch 
of  the  external  circumflex  and  deep  circumflex  iliac  arteries,  (fi)  The  inferior 
branch  passes  forwards  between  tlie  gluteus  medius  and  minimus,  accompanied  by 
the  l)ranch  to  the  tensor  fascite  femoris  of  the  inferior  division  of  the  superior 
gluteal  nerve  towards  the  great  trochanter,  where  it  anastomoses  with  the  ascen<ling 
branch  of  the  external  circumflex.  It  supplies  branches  to  the  contiguous  muscles 
and  to  the  hip-joint. 

The  deep  branch  before  its  division  gives  off  the  external  nutrient  artery  of  the 
ilium. 


BiJAxrHES  OF  thp:  Anterior  Division  of  the  Internal  Iliac  Artery 

1.  THE  HYPOGASTRIC  ARTERY 

The  hypogastric  artery,  the  main  trunk  of  the  internal  iliac  in  the  foetus,  is 
the  apparent  continuation  of  the  anterior  Ijranch  of  the  internal  iliac.  Passing 
forwards  along  the  side  of  the  pelvis,  it  enters  the  lateral  false  ligament  of  the 
bladder,  where,  after  giving  oflf  one  or  more  vesical  branches,  it  ceases  to  be  ]iervious 
as  it  passes  on  to  the  side  and  upper  part  of  the  l)ladder.  Thence  it  ascends,  under 
cover  of  the  anterior  false  ligament,  as  a  fibrous  cord,  to  the  umbilicus,  where  it  is 
joined  by  its  fellow  of  the  opposite  side.  As  it  lies  in  the  lateral  false  ligament  it 
is  crossed  bv  the  vas  deferens. 


2.  THE  VESICAL  ARTERIES 

The  vesical  arteries  are  divided  into  the  superior,  middle,  and  inferior. 
(1)  The  superior  vesical  artery — though  usually  described  as  a  branch  of  the 
internal  iliac,  inasmuch  as  it  is  api)arently  given  ofl:'  from  the  anterior  division  of 


570  THE  ARTERIES 

that  vessel — is  really  a  branch  of  the  iinobliterated  portion  of  what,  in  the  foetus, 
■was  the  hypogastric  artery.  It  ramifies  over  the  upper  fundus  of  the  l)ladder, 
anastomosing  with  the  artery  of  the  opposite  side  and  with  the  middle  and  inferior 
vesical  lielow.  It  gives  off  the  following  branches: — (a)  The  deferential,  or  artery 
of  the  vas  deferens,  arises  from  the  superior  vesical  near  the  spot  where  the  vas 
crosses  the  oljliterated  hy[)Ogastric  artery,  and,  having  readied  the  vas,  divides  into 
an  ascending  and  a  descending  branch.  Tlie  ascending  branch  follows  the  vas 
through  the  inguinal  canal  to  the  testicle,  Avhere  it  anastomoses  with  the  spermatic 
arterv.  The  descending  l)ranch  passes  downwards  to  the  dilated  portion  of  the  vas 
and  Vesiculse  seminales.  {h)  Tlio  uracheric  branch  passes  upwards  along  the 
urachus.  (c)  The  ureteric  branches  pass  to  the  lower  end  of  the  ureter,  which 
they  supply,  and  anastomose  with  the  other  ureteric  arteries,  (rf)  The  middle 
vesical  (sometimes). 

(2)  The  middle  vesical  is  a  branch  either  of  the  superior  vesical,  or  of  the 
unobliterated  portion  of  the  hypogastric  artery.  In  the  latter  case  it  is  given  off 
])efore  the  superior  vesical.  It  is  distributed  to  the  sides  and  base  of  the  Ijladder, 
and  anastomoses  with  the  other  vesical  arteries. 

(3)  The  inferior  vesical  arises  from  the  anterior  division  of  the  internal  iliac, 
frequently  in  common  with  the  middle  htemorrhoidal.  and  passes  downwards  and 
inwards  to  the  base  of  the  bladder,  where  it  breaks  up  into  branches  which  ramify 
over  the  lower  part  of  the  viscus.  It  gives  off: — (a)  Branches  to  the  prostate. 
Avhich  supply  that  organ  and  anastomose  with  the  arteries  of  the  opposite  side  by 
means  of  descending  arteries  which  pass  through  the  prostatic  plexus  of  veins,  but 
outside  the  capsule  of  the  prostate,  and  with  the  inferior  hsemorrhoidal  branches  of 
the  internal  pudic.  At  times  one  of  these  prostatic  branches  is  of  large  size,  and 
supplies  certain  of  the  parts  normally  supplied  by  the  internal  pudic.  It  is  then 
known  as  the  accessory  pudic,  and  then  most  commonly  terminates  as  the  dorsal 
artery  of  the  penis,  {h)  Branches  to  the  vesicuke  seminales;  and  (r)  branches  (in 
the  female)  to  the  vagina.  (See  Vagixal  Artery.  )  The  artery  of  the  vas  deferens 
sometimes  arises  from  the  inferior  vesical,  instead  of  from  the  superior  vesical. 


3.    THE  MIDDLE  H^EMORRHOIDAL  ARTERY 

The  middle  haemorrhoidal  or  the  middle  rectal  artery,  variable  in  its  origin, 
perhaps  most  commonly  arises  from  the  anterior  division  of  the  internal  iliac  along 
with  the  inferior  vesical.  It  runs  inwards  to  the  sides  of  the  middle  portion  of  the 
rectum,  dividing  into  branches  which  anastomose  above  with  the  superior  ha?mor- 
rhoidal  derived  from  the  inferior  mesenteric,  and  below  with  the  inferior  hsemor- 
rhoidal  derived  from  branches  of  the  pudic.  Its  corresponding  vein  terminates  in 
the  inferior  mesenteric  vein. 


4.     THE  UTERINE  ARTERY 

The  uterine  artery  arises  from  the  anterior  liranch  of  the  internal  iliac  close  to 
or  in  conjunction  with  tlie  middle  hiemorrhoidal  or  inferior  vesical.  It  runs  down- 
wards and  in  wards,  through  the  pelvic  connective  tissue  in  the  so-called  infundibulo- 
pelvic  ligament,  crossing  the  ureter  about  half  an  inch  from  the  cervix  uteri.  It  then 
turns  upwards  and  ascends  between  the  layers  of  the  broad  ligament  on  the  side 
of  the  uterus  in  a  coiled  and  tortuous  manner,  and,  after  giving  off  a  number  of 
tortuous  branches  Avhich  ramify  in  a  horizontal  manner  over  the  front  and  back 
of  the  uterus,  supplying  its  substance,  anastomoses  with  the  uterine  branch  of 
the  ovarian  artery.  The  distribution  of  the  vessel  in  the  uterus  Avill  be  described 
with  that  organ.  The  branches  of  the  uterine  artery  are: — (1)  Cervical. — This 
branch  comes  oft'  from  the  iiU'rine  as  the  latter  artery  crosses  the  ureter  to  turn  up- 
wards on  to  the  uterus.  It  runs  directly  inwards,  and  divides  into  three  or  four 
branches  Avhich  pass  on  to  the  cervix  at  right  angles  to  it;  one  branch  anastomosing 
with  its  fellow  of  the  opposite  side  in  front  and  beliind  the  neck,  forming  the  so-called 
coronary  artery  of  the  cervix.      (2)  Vaginal  azygos. — A  second  branch  descends 


UTERINE—  VA GINAL—OBTURA  TOR 


571 


both  in  front  and  behind  in  the  middle  Hne  of  tlie  cervix  on  to  tlie  vagina,  and 
forms,  with  liranehes  of  the  vaginal  arteries,  the  so-called  azygos  artery  of  the 
vagina. 

5.  THE  VAGINAL  ARTERIES 

The  vaginal  arteries  come  ofif  separately  from  the  anterior  division  of  the 
internal  iliac,  or  one  or  more  of  them  may  arise  in  common  with  the  inferior 
vesical,  uterine,  or  middle  hsemorrhoidal  arteries.  They  are  usually  two  or  three  in 
number.  They  pass  through  the  pelvic  connective  tissue  to  the  side  of  the  vagina, 
supplying  its  Avails,  and  anastomosing  with  the  corresponding  arteries  of  the  oppo- 
site side,  with  each  other,  and  witli  tortuous  branches  from  the  artery  of  the  cervix, 
a  branch  of  the  uterine.  "With  this  vessel  they  form  a  more  or  less  vertical  trunk 
in  the  median  line  of  the  vagina,  both  back  and  front.     This  vessel  is  known  as  the 


Fig.  370.— Scheme  of  the  Ovaeiax  axd  Uteeixe  and  Vagixal  Arteries. 

Branch 


Cervical  branch 


Coronal  artery 


FIMBRIATED 


Branch     Branches 
Uterine    to  round  to  to  EXTREMITY  OF 

branch    ligament       isthmus       ampulla    FALLOPIAN  TUBE 


Ovarian  branches 

Uterine  artery 
Internal  iliac  artery 

Vaginal  arteries 


azygos  artery  of  the  vagina.  The  lower  vaginal  arteries  extend  to  the  bulb  of 
the  vestibule,  where  they  conununicate  with  the  bulbar  branch  of  the  internal 
pudic.     Small  branches  extend  also  on  to  the  rectum. 


6.  THE  OBTURATOR  ARTERY 

The  obturator  artery  comes  off  from  the  anterior  division  of  the  internal  iliac 
at  about  the  same  sjiot  as  the  hypogastric.  Occasionally  it  arises  from  the  posterior 
division.  It  runs  forward  and  downwards  a  little  below  the  brim  of  the  pelvis, 
having  the  obturator  nerve  al)Ove,  and  the  obturator  vein  below.  It  here  lies 
between  the  peritoneum  and  the  pelvic  fascia,  but  pierces  the  fascia  to  gain  the 
obturator  canal,  the  aperture  in  the  upper  and  outer  part  of  the  ol>turator  mem- 
brane. In  this  course  it  is  crossed  by  the  vas  deferens.  On  emerging  from  the 
obturator  canal,  the  artery  divides  into  two  branches,  an  external  and  an  internal, 
which  wind  round  the  margin  of  the  thyroid  foramen  beneath  the  obturator 
externus  muscle. 


572  THE  ARTERIES 

Within  the  pelvis  the  artery  gives  off: — (1)  An  ihac  or  nutrient  branch;  (2) 
a  vesical  branch;  and  (3)  a  pubic  branch.  "Without  the  pelvis,  it  divides  into: — 
(1)  An  external  branch;  and  (2)  an  internal  branch. 

A.  Intra-peliHc  branches. — (1)  The  iliac  or  nutrient  branch  ascends  to  the  iliac 
fossa,  passing  between  the  iliacus  muscle  and  the  l)one.  It  svipi)lies  a  nutrient 
vessel  to  the  ilium,  and  anastomoses  with  the  internal  In'anch  of  the  iliac  division 
of  the  ilio-lumbar  artery. 

(2)  The  vesical  branch  or  branches  are  small  vessels  which  run  in  the  lateral 
false  ligament  of  the  ])ladder  to  that  organ,  where  they  anastomose  with  the  other 
vesical  arteries. 

(3)  The  pubic  branch  comes  off  from  the  obturator  as  that  vessel  is  leaving  the 
pelvis  by  the  oliturator  canal.  It  runs  upwards  and  inwards  behind  the  pubes, 
anastomosing  with  its  fellow  of  the  opposite  side  of  the  body,  and  with  the  pubic 
l)ranch  of  the  deep  epigastric  artery.  One  of  the  anastomosing  channels  between 
the  pubic  branch  of  the  obturator  and  pubic  branch  of  the  deep  epigastric  arteries 
is  sometimes  of  large  size,  a  fact  of  surgical  interest  in  that  the  enlarged  vessel  may 
then  run  round  the  inner  side  of  the  femoral  ring  (])age  579). 

B.  Extra-pelvic  branches. — (1)  The  external  branch  skirts  the  external  margin 
of  the  thyroid  foramen,  h^ing  between  the  ol^turator  externus  and  the  obturator 
meml^rane.  At  the  lower  margin  of  the  foramen  it  divides  into  two  branches.  One 
branch  continues  its  course  round  the  lower  margin  of  the  foramen,  and  anasto- 
moses with  the  internal  branch  of  the  obturator  and  with  the  internal  circumflex. 
The  other  branch  turns  outwards  below  the  acetabulum,  and  ends  in  the  muscles 
arising  from  the  tuberosity  of  the  ischium.  It  anastomoses  with  the  sciatic  artery. 
This  l)ranch  gives  off  a  small  twig  which  passes  under  the  transverse  ligament  into 
the  hip-joint,  Avhere  it  supplies  the  synovial  membrane,  the  ligamentum  teres,  and 
the  fat  in  the  fossa  at  the  bottom  of  the  acetabulum. 

(2)  The  internal  branch  runs  round  the  inner  margin  of  the  thyroid  foramen, 
and  anastomoses  with  the  inner  division  of  the  external  branch  and  with  the 
internal  circumflex  artery.  It  supplies  branches  to  the  ol)turator  and  adductor 
muscles. 

7.  THE   SCIATIC  ARTERY 

The  sciatic  artery — the  larger  of  the  terminal  l:)ranches  of  the  anterior  division 
of  the  internal  ihac — passes  over  the  sacral  plexus  and  pyriformis  muscle  to  the 
lower  part  of  the  great  sciatic  foramen,  where  it  leaves  the  pelvis  with  the  pudic 
artery,  behind  and  external  to  which  it  lies,  by  passing  between  the  pyriformis  and 
coccygeus  muscles.  On  emerging  from  the  great  sciatic  foramen  in  the  gluteal 
region  under  cover  of  the  gluteus  maximus,  it  descends  to  the  inner  side  of  the  great 
sciatic  nerve,  lying  midway  between  the  tuberosity  of  the  ischium  and  the  great 
trochanter  on  the  gemellus  superior,  obturator  internus,  gemellus  inferior,  quadratus 
fcmoris,  and  upper  part  of  the  adductor  magnus  muscles.  It  anastomoses  with  the 
internal  circumflex  artery,  and  superior  perforating  branch  of  the  profunda.  The 
branches  of  the  sciatic  artery  are  divided  into  the  intra-  and  extra-pelvic. 

The  intra-pelvic  branches  are  small  and  unimportant,  and  irregular  in  their 
origin  and  (Hstribution.  Thc}^  are  given  oft'  to  the  levator  ani,  coccygeus,  and 
pyriformis  muscles,  the  rectum,  bladder,  prostate  gland,  and  vesiculse  seminales. 

The  extra-pelvic  branches  are:  (1)  The  coccygeal;  (2)  inferior  gluteal;  (3) 
muscular;  (4)  anastomotic;  (5)  articular;  ((3)  cutaneous;  and  (7)  comes  nervi 
ischiatici. 

(1)  The  coccygeal  is  a  small  l)ranch  Avliich  glasses  inwards,  and,  jjiercing  the 
great  sacro-sciatic  ligament  and  the  gluteus  maximus,  is  lost  in  the  integument 
over  the  lower  part  of  the  sacrum  and  coccyx.  It  gives  several  l)ranches  to  the 
lower  and  internal  ])art  of  tlie  gluteus  maxinuis  as  it  passes  through  it. 

(2)  The  inferior  gluteal  is  a  fairly  large  branch  which  arises  from  the  sciatic 
just  l)elow  the  coccygeal,  and,  turning  upwards  and  inwards  into  the  deep  surface 
of  the  gluteus  maximus  along  with  the  inferior  gluteal  nerve,  su])plies  that  muscle, 
and  anastomoses  with  the  gluteal  artery. 

(3)  The  muscular  branches,  varial)le  in  their  numlier  and  origin,  pass  to  the 


INTERNAL   PTDIC  573 

pyrifonuis,  ()l)tur:it()r  intrvnus,  and  gcniclli  iimscles,  anastomosing  with  the  piulic, 
the  internal  (•ircunill<'.\,  and  the  oljturator  arteries. 

(4)  The  anastomotic  branch  crosses  the  external  rotator  muscles  either  over 
or  under  the  great  sciatic  nerve,  and  contributes  to  the  formation  of  the  so-called 
crucial  anastomosis  by  anastomosing  -with  the  first  perforating  below,  the  termi- 
nation of  the  internal  circumiiex  internally,  and  the  transverse  branch  of  the 
external  circumflex  externally  (fig.  369). 

(5)  The  articular  branches  pass  beneath  the  external  rotator  muscles  with  the 
nerve  to  the  quadratus  femoris,  and  send  several  filaments  into  the  posterior  part 
of  the  capsule  of  the  hip-joint. 

(6)  The  cutaneous  branches  turn  round  the  lower  border  of  the  gluteus  maxi- 
mus,  along  with  l)ranchcs  of  the  small  sciatic  nerve,  and  supj^ly  the  integument  of 
that  region. 

(7)  The  comes  nervi  ischiatici  is  a  long  slender  vessel  which  passes  down 
the  back  of  the  thigh  with  the  great  sciatic  nerve,  to  Avhich  it  sends  numerous 
branches.  It  anastomoses  Avith  the  internal  circumflex,  and  with  the  first,  second, 
and  third  perforating  arteries,  and  with  the  termination  of  the  profunda,  or  fourth 
perforating.  After  ligature  of  the  femoral  in  Scarpa's  triangle,  this  artery  becomes 
greatly  enlarged,  and  contributes  through  its  anastomosis  with  the  above-mentioned 
arteries  to  the  supply  of  the  parts  below  the  ligature. 


8.     THE  INTERNAL  PUDIC  ARTERY 

The  internal  pudic  artery — the  smaller  of  the  two  terminal  branches  of  the 
anterior  division  of  the  internal  iliac  artery — comes  off  wdth  the  sciatic,  the  other 
terminal  branch,  either  separately  or  as  a  common  trunk,  opposite  the  pyriformis 
muscle.  It  descends  with  the  sciatic  over  the  pyriformis  and  sacral  plexus  of 
nerves,  lying  anterior  and  internal  to  the  latter  artery  as  far  as  the  lower  liorder  of 
the  great  sciatic  foramen,  where  it  passes  out  of  the  pelvis  l^etween  the  pyriformis 
and  coccygeus  muscles.  It  then  winds  over  the  outer  surface  of  the  spine  of  the 
ischium  under  cover  of  the  gluteus  maximus,  and  re-enters  the  pelvis  through  the 
lesser  sciatic  notch.  Running  forwards  over  the  obturator  internus  muscle,  it 
passes  through  the  base  of  the  triangular  ligament,  and,  continuing  its  course 
along  the  ramus  of  the  pubes,  gives  off  between  the  two  layers  of  the  triangular 
ligament  the  artery  of  the  crus  and  the  artery  of  the  bulb,  and  is  continued  through 
the  anterior  layer  of  the  ligament  as  the  dorsal  artery  of  the  penis. 

The  relations  of  the  artery  may  be  considered: — (1)  As  it  lies  within  the 
pelvis;  (2)  as  it  crosses  the  spine  of  the  ischium;  (3)  as  it  lies  on  the  obturator 
internus  muscle,  in  the  outer  Avall  of  the  ischio-rectal  fossa;  and  (4)  as  it  lies 
between  the  two  layers  of  the  triangular  ligament. 

(1)  ^A(^ithin  the  pelvis  the  artery  crosses  the  pyriformis  muscle  and  sacral 
plexus  of  nerves,  lying  somewhat  anterior  and  internal  to  the  sciatic  artery,  which 
is  usually  given  off  from  the  internal  iliac  along  with  it.  At  the  lower  border  of 
the  sciatic  foramen  it  leaves  the  pelvis  by  passing  between  the  pyriformis  and 
coccygeus  muscles  along  with  the  sciatic  artery,  the  pudic  nerve,  the  greater  and 
lesser  sciatic  nerves,  and  the  nerve  to  the  obturator  internus. 

(•2)  As  it  crosses  the  spine  of  the  ischium  it  has  a  companion  vein  on  either 
side,  the  pudic  nerve  on  its  inner  side,  and  the  nerve  to  the  obturator  interims  (»n 
its  outer  side.  It  is  covered  by  the  gluteus  maximus  muscle,  and  more  or  less  by 
the  overlapping  edge  of  the  great  sacro-sciatic  ligament.  In  a  thin  sul)ject  it  can 
be  felt  pulsating  as  it  crosses  the  ischial  spine.  A  s])ot  taken  at  the  junction  of 
the  inner  with  the  outer  two-thirds  of  a  line  drawn  from  the  top  of  the  great 
trochanter  with  the  femur  rotated  inwards  to  the  base  of  the  coccyx,  indicates 
externally  the  situation  of  the  artery  as  it  crosses  the  ischial  spin(\  In  this  situa- 
tion it  may,  in  a  thin  subject,  be  compressed.  The  branches  of  the  artery  in  tliis 
part  of  its  course  are:  (a)  Small  twigs  to  the  gluteus  maxinuis;  (^)  a  small  branch 
to  the  ol)turator  internus  which  accompanies  the  nerve  to  that  muscle;  (r)  a  sacral 
branch  which  i)ierces  the  great  sciatic  ligament  and  anastomoses  with  the  sciatic 
artery. 


574 


THE  ARTERIES 


(3)  In  the  third  part  of  its  course,  as  it  lies  on  the  obturator  internus  muscle, 
in  the  outer  wall  of  the  ischio-rectal  fossa,  it  is  placed  about  an  inch  and  a  half 
(3"5cm. )  above  the  lower  margin  of  the  tuberosity  of  the  ischium.  It  is  here 
bound  down  to  the  muscle  by  a  strong  sheath  of  the  obturator  layer  of  the  pelvic 
fascia  (Alcock's  canal).  In  this  part  of  its  course  the  dorsal  nerve  of  the  penis 
and  the  superficial  perineal  nerve,  into  which  the  pudic  nerve  divides  about  tliis 
situation,  lie  respectively  above  and  l)elow  the  artery. 

The  branches  of  the  pudic  artery  in  the  third  part  of  its  course  are: — (a)  The 
external  or  inferior  hajmorrhoidal;  and  (h)  the  superficial  j^erinseal. 

(a)  The  external  or  inferior  haemorrhoidal  branches  (inferior  or  posterior 
anal)  are  given  off  from  the  pudic  at  the  posterior  jiart  of  the  ischio-rectal  fossa, 
just  after  it  enters  the  outer  wall  of  that  cavity  through  the  lesser  sciatic  foramen. 
They  perforate  the  sheath  of   obturator  fascia  binding  the  pudic  artery  to  the 


Fig.  370a. — The  Arteries  of  the  Perineum. 

On  the  right  side  Colles's  fascia  has  been  turned  back  to  show  the  superficial  vessels.  On  the 
left  side  the  superficial  vessels  have  been  cut  away  with  the  anterior  layer  of  the  triangular  ligament 
to  show  the  deep  vessels. 


Superficial  perinaeal  vessels 


Accelerator  uriuae 


Colles's  fascia,  turned  back 


Erector  penis 

Transverse  peri)iiml  vessels 

Cut  edge  of  triangular 

ligament 

SUPERFICIAL  PERIX^AL 

NER  VE  GIVING  OFF 

TRANSVERSE  BRANCH 

Pudic  vessels 

Inferior  hcemorrhoidal  vessels 
and  nerves 


Gluteus  raaximus, 
hooked  back 


Crus  penis 

Dorsal  artery  of  penis 
Artery  of  cms 


■A        — Artery  of  bulb 

COWPER'S  6LAN0 

..  ,j-  — .  Pudic  artery 

\\ 
=y-],i Great  sciatic  ligament 

*—ji Levator  ani 

External  sphincter 


Gluteus  maximus 


obturator  internus,  and  course  transversely  through  the  fat  of  the  ischio-rectal 
fossa,  inwards  to  the  anus,  where  they  supply  the  sphincter  muscle  and  levatc^r  ani, 
and  anastomose  with  the  superior  and  middle  ha?morrhoidal  arteries.  Twigs  are 
given  off  from  them  to  the  skin  covering  the  anal  triangle  of  the  ])erina3um;  otlier 
branches  supply  the  gluteus  maximus  and  wind  over  the  posterior  fold  of  tliat 
muscle  to  the  integuments;  whilst  others  again  run  forwards  and  anastomose  with 
the  transverse  and  sujierficial  perinatal  arteries  (fig.  370a). 

(h)  Th(!  superficial  perinaeal  branch  arises  from  the  pudic  at  the  front  of  the 
ischio-rectal  fossa,  just  l)ef ore  that  vessel  ])ierces  the  posterior  layer  of  the  triangular 
ligament.  It  passes  through  the  deep  layer  of  the  superficial  fascia  of  the  peri- 
naeum  (Colles's  fascia),  Avhere  that  structure  is  continued  into  the  anterior  layer  of 
the  triangular  ligament  round  the  transverse  perinatal  muscle.  It  then  crosses  in 
front  of  (occasionally  l^'hind)  that  muscle,  and  enters  the  periiia'al  triangle,  the 


IMERXAL   PUDIC 


bib 


space  between  Colles's  fascia  and  the  anterior  layer  of  the  triangular  ligament, 
bounded  by  the  erector  penis  externally,  the  accelerator  urinie  internally,  and  the 
transverse  perinscal  muscle  below.  On  nearing  the  ajjcx  of  this  triangle  it  divides 
into  long  slender  branches,  which  are  continued  along  the  back  of  the  scrotum, 
anastomosing  with  the  superficial  external  pudic  branch  of  the  connnon  femoral. 
In  this  course  it  is  accompanied  by  the  superficial  perinaeal  nerve.  It  supplies  the 
contiguous  muscles  and  the  integuments  of  the  scrotum.  As  a  rule  it  gives  off  the 
following  branch : — 

The  transverse  perinaeal  artery  usually  arises  from  the  before-mentioned 
artery.  Occasionally  it  is  a  direct  branch  from  the  jnidic  trunk.  It  courses  trans- 
versely inwards,  on  the  transverse  perinaeal  muscle,  towards  the  central  tendon  of 
the  perinteum.  su})plying  the  muscles  and  integuments  of  the  perinteum,  and 
anastomosing  with  its  fellow  of  the  ojjposite  side. 

(4)  In  the  fourth  part  of  its  course  the  pudic  artery  lies  between  the  two 
layers  of  the  triangular  ligament,  close  to  the  ramus  of  the  pubes,  in  the  substance 
of  the  compressor  urethrse  muscle,  having  the  anterior  layer  of  the  triangular  liga- 
ment in  front  and  the  posterior  layer  behind.  In  this  situation  it  gives  off  the 
artery  of  the  bulb  and  the  artery  of  the  crus  penis,  and  then  continues  its  course 


Fig.  371. — .Scheme  of  the  Pudic  Artery  and  its  Br.\nche.s. 


Subpubic  ligament  with  aperture  for 
dorsal  vein  of  the  penis 

Apei  hires  for  dorsal  artery  and  ( 
nerve  of  the  penis  \ 


Crus  penis 
Aperture  for  artery  of  t<jr/>us 
cnvernosiiin 
Superficial  triangular  ligament 
Ischio-eavernosus,  or  erector  peuis 
Aperture  for  artery 
to  bulb 
Urethral  aperture 
Aperture  for  Cow- 
per's  duct 
Position  of  bulb 


Apertures  for  super- 
jicial  perhiceal 
vessels  and  tier  re 


Fascia  of  Colles, 
turned  backwards 


DORSAL  NERVE 
Anterior  layer  of  triangular 
ligament 
■n—  Dorsal  artery  of  penis 

vy  Deep  triangu- 

lar ligament 
.1  rtery  of  corpus 
carfniosiiiu 

Artery  to  bulb 

/'•i<lic  reins 
DORSAL  NERVE 

POSITION  OF  COWPER'S 

GLAND 
Internal  pudic  artery 


Posterior  border  of 
perinaeal  ledge 
I  junction  of  trian- 
gular ligaments 
■with  fascia  of 
CoUes) 


forwards  through  the  anterior  layer  of  the  triangular  ligament  under  the  name  of 
the  dorsal  artery  of  the  penis. 

Tlie  branches  of  the  pudic  artery  in  the  fourth  part  of  its  course  are: — (a) 
The  artery  of  the  bullj;  {b )  the  artery  of  the  crus;  and  (c)  the  dorsal  artery  of  the 
penis. 

(«)  The  artery  of  the  bulb,  often  of  large  size,  comes  off  from  the  ]»udic  soon 
after  that  vessel  has  ))assed  between  the  two  layers  of  the  triangular  ligament.  It 
runs  inwards  and  slightly  upwards  behind  tlie  anterior  layer  of  the  triangular  liga- 
ment, embedded  more  or  less  in  the  sul:)Stance  of  the  compressor  urethra 
muscle.  On  nearing  the  urethra,  it  passes  forwards  through  a  hole  in  the 
anterior  layer  of  the  triangular  ligament  (fig.  371).  by  the  side  of  the  ojiening  for 
the  urethra,  and,  entering  the  bulb,  sui)plies  the  erectile  tissue  of  the  bulb  and 
corpus  spongiosum  in  the  way  descrilied  under  the  anatomy  of  the  urethra.  It 
gives  off  a  branch,  just  before  piercing  the  anterior  layer  of  the  triangular  ligament, 
to  Cowper's  glands  (fig.  370a). 

The  situation  of  the  artery  of  the  bulb  should  l»e  remembered  in  jierforming  the 
operation  of  lateral  lithotomy.  As  a  rule,  the  artery  is  well  above  the  central  tendon 
of  the  perinseum.  If  the  point  of  the  knife  is  entered  V)elow  this  spot,  and  care  is 
taken  not  to  direct  its  point  subsequently  too  much  ujiwardsso  that  the  deei>er  part 


576  THE  ARTERIES 

of  the  incision  is  not  made  higher  than  the  superficial,  the  artery  will  not  be  endan- 
gered. At  times,  however,  the  artery  is  given  off  from  the  })udic  lower  than 
normal.     Its  division  may  then  be  unavoidable. 

When  the  artery  is  given  off,  as  it  occasionally  is,  from  the  accessory  pudic,  it 
pierces  the  anterior  layer  of  the  triangular  ligament  higher  up,  and  is  out  of  danger 
in  the  ordinary  low  operation  of  lateral  lithotomy.  Further,  the  artery  of  the 
bulb  may  be  absent  on  one  side,  smaller  than  usual,  or  double. 

In  the  female,  the  artery  of  the  bulb,  smaller  than  in  the  male,  ends  in  the 
bulb  of  the  vestibule. 

{I))  The  artery  of  the  crus  is  usually  given  off  from  the  pudic  a  little  higher 
than  the  artery  of  the  bulb.  It  makes  at  once  for  the  ramus  of  the  pubes,  per- 
forates the  anterior  layer  of  the  triangular  ligament  close  to  the  bone,  and  enters 
the  crus  penis  (figs.  370a,  371).  This  artery  has  to  be  divided  in  the  operation  for 
the  removal  of  the  wdiole  of  the  penis  by  dissecting  off  the  crura  from  the  rami  of 
the  pubis  and  ischium.  Its  situation  close  to  the  bone  at  times  gives  rise  to  some 
little  trouble  in  securing  it.  A  small  additional  artery  to  the  corpus  spongiosum  is 
occasionally  given  off  from  this  branch  and  then  contributes  to  the  supply  of  that 
structure  and  inosculates  with  branches  from  the  artery  to  the  bulb. 

In  the  female,  the  artery  ends  in  the  crus  clitoridis. 

(c)  The  dorsal  artery  of  the  penis  (fig.  371),  the  termination  of  the  pudic, 
passes  upwards  between  the  two  layers  of  the  triangular  ligament  in  the  substance 
of  the  compressor  urethrse  muscle;  then,  turning  forwards,  perforates  the  anterior 
layer  of  the  triangular  ligament,  near  its  apex,  a  little  to  one  side  of  the  central 
apical  opening  for  the  dorsal  vein.  It  then  passes  between  the  two  layers  of  the 
suspensory  ligament  of  the  penis,  and  descends  along  the  dorsum  of  that  organ, 
the  single  centrally  placed  dorsal  vein  separating  it  from  the  artery  of  the  opposite 
side.  The  dorsal  nerve  lies  to  the  outer  side  of  the  artery,  and,  still  more  external, 
the  deep  external  pudic  branch  of  the  common  femoral  artery.  At  the  glans  the 
dorsal  artery  forms  an  anastomotic  chain  around  the  corona  with  the  vessel  of  the 
opposite  side.  The  superficial  external  pudic  branch  of  the  femoral  at  times  may 
take  the  place  of  the  dorsal  artery.  Occasionally  the  dorsal  artery  is  found  to 
arise  from  the  inferior  vaginal;  that  is,  from  an  enlarged  branch  of  the  vessel  known 
as  the  accessory  pudic  (see  page  570). 

In  the  female,  the  termination  of  the  pudic  is  called  the  dorsal  artery  of  the 
clitoris. 

The  dorsal  artery  gives  branches  to — (a)  The  corpus  cavernosum;  (6)  the  skin 
of  the  penis;  (c)  the  glans  penis;  and  in  the  female,  (d)  the  glans  and  prepuce 
of  the  clitoris. 

THE  EXTERNAL  ILIAC  ARTERY 

The  external  iliac  artery — the  larger  in  the  adult  of  the  two  vessels  into  which 
the  common  iliac  divides  opposite  the  lumbo-sacral  articulation — extends  from  this 
spot  along  the  brim  of  the  pelvis,  lying  upon  the  inner  border  of  the  psoas  muscle, 
to  the  lower  margin  of  Poupart's  ligament,  where,  midway  between  the  anterior 
superior  spine  of  the  ilium  and  the  symphysis  pubis,  it  passes  into  the  thigh,  and 
takes  the  name  of  the  femoral. 

It  measures  three  and  a  half  to  four  inches  (10  cm.)  in  length.  The  course  of 
the  vessel  is  indicated  by  a  line  drawn  from  half  an  inch  below  and  a  little  to  the 
left  of  the  umbilicus,  to  a  point  a  little  internal  to  the  centre  of  Poupart's  liga- 
ment, that  is,  to  a  spot  midway  between  the  symphysis  pubis  and  the  anterior 
superior  spine  of  the  ilium.  If  this  line  is  divided  into  thirds,  the  lower  two 
thirds  indicate  the  situation  of  the  external  iliac,  the  upper  third  the  common 
iliac.  The  external  iliac  vein,  the  continuation  upwards  of  the  femoral  vein 
from  the  thigh,  lies  to  the  inner  side  of  the  artery,  but  on  a  slightly  lower  plane, 
and  just  before  its  termination  gets  a  little  behind  the  artery  on  the  right  side. 

Relations. — In  front,  the  artery  together  with  the  vein  is  covered  by  the 
parietal  peritoneum  descending  from  the  abdomen  into  the  pelvis,  and  by  a  layer 
of  condensed  subperitoneal  tissue,  known  as  Abernethy's  fascia.  It  is  crossed  by 
the  termination  of  the  ileum  on  the  right  side,  and  by  the  sigmoid  flexure  on  the 


EXTERNAL   ILIAC  bll 

\A{.  The  genital  brancli  of  the  itrcnito-crural  nerve  runs  obliquely  over  its  lower 
third,  and  just  before  its  termination  it  is  crossed  transversely  by  the  deep  circuni- 
ilex  iliac  vein.  The  si)erniatic  vessels  lie  for  a  short  distance  on  the  lower  part  of 
the  artery,  and  the  vas  deferens  in  the  male  and  the  ovarian  vessels  in  the  female 
curve  over  it  to  descend  to  the  pelvis.  It  is  sometimes  crossed  at  its  origin  by  the 
ureter.  The  external  iliac  lymphatic  glands  lie  along  the  course  of  the  artery. 
The  eonmiencement  of  its  deep  epigastric  branch  is  also  in  front. 

Behind. — At  first  the  artery  lies  partly  upon  it^  OAvn  vein;  lower  doAvn  upon 
the  inner  border  of  the  psoas;  and  just  before  it  passes  through  the  lacuna  vascu- 
losa,  beneath  Pou})art's  ligament,  uj^on  the  tendon  of  the  psoas.  The  continuation 
of  the  iliac  into  the  pelvic  fascia  is  also  below  it. 

To  its  inner  side  is  the  external  iliac  vein,  the  peritoneum,  the  descending 
layer  of  fascia,  and  the  vas  deferens  in  the  male,  and  ovarian  vessels  in  the  female. 

To  its  outer  side  is  the  psoas  muscle  and  the  iliac  fascia. 

Variations. — (A)  Tlic  external  iliac  may  be  lunger  or  shorter  than  usual,  according  as  the 
coimuon  iliac  bifurcates  above  or  below  the  usual  spot.  Wlien  longer  it  often  takes  a  very  tor- 
tuous course,  making  a  partial  loop  or  bend  which  may  dip  down  below  the  brim  of  the  pelvis. 
(B)  It  may  be  much  smaller  in  size  than  usual ;  this  is  especially  the  case  in  those  instances  in 
which  the  femoral  or  main  vessel  of  the  lower  limb  arises  from  the  sciatic  or  other  branch  of  the 
internal  ihac.  It  then  often  ends  in  the  profunda.  (C)  It  may  give  oiF  a  large  branch,  as  the 
deep  circumflex  iliac  or  deep  epigastric,  higher  than  usual. 

The  collateral  circulation  is  carried  on  (fig.  372),  when  the  external  iliac  is  tied,  by  the  anas- 
tomosis of  the  ilio-lumbar  and  lumbar  arteries  with  the  circumflex  iliac  ;  the  internal  mammary 
witli  the  dee))  epigastric  ;  the  obturator  with  the  internal  circumflex  ;  the  sciatic  with  the  internal 
circumflex  and  superior  ])erforating  ;  the  gluteal  with  the  external  circumflex  ;  the  arteria  comes 
neryi  isehiatici  from  tlie  sciatic,  with  the  perforating  branches  of  tlie  profunda ;  tlie  external 
pudic  with  tlie  internal  jiudic  ;  tlie  pubic  branch  of  the  obturator  with  the  pubic  branch  of  the 
epigastric. 

The  branches  of  the  external  iliac  artery  are: — (1)  The  deep  epigastric;  (2) 
the  deei)  circumiiex  iliac;  and  (3)  several  small  and  insignificant  tw'igs  to  the 
neighbouring  psoas  muscle  and  lymphatic  glands. 

(1)  The  Deep  Epigasteic  Artery 

The  deep  epigastric  artery  usually  comes  oflp  from  the  external  iliac  just 
above  Poupart's  ligament.  Immediately  after  its  origin,  the  vas  deferens  in  the 
male,  and  the  round  ligament  in  the  female,  loop  round  it  on  their  way  to  the 
pelvis,  drawing,  as  it  were,  the  artery  slightly  inwards  and  downwards.  It  here 
lies  internal  to  the  inner  margin  of  the  deep  or  internal  alidominal  ring  behind  the 
inguinal  canal,  and  a  little  to  the  upper  and  outer  side  of  the  femoral  ring.  Thence 
it  passes  U])wards  and  inwards,  above  and  to  the  outer  side  of  the  superficial  or 
external  abdominal  ring,  lying  between  the  fascia  transversalis  and  the  peritoneum 
to  the  lower  margin  of  the  posterior  layer  of  the  sheath  of  the  rectus  (fold  of  Doug- 
las). Having  pierced  the  fascia  transversalis  at  this  point,  it  passes  in  front  of 
Douglas'  fold  and  turns  upwards  between  the  rectus  and  its  sheath,  lying  here 
about  midway  betw^een  the  outer  and  inner  edge  of  the  muscle.  Higher,  it  enters 
the  sul)stance  of  the  muscle,  and  anastomoses  with  the  superior  epigastric,  descend- 
ing in  the  rectus  from  the  internal  mannnary. 

The  situation  of  the  artery  between  the  two  abdominal  rings  should  be  borne  in 
mind  in  the  operation  for  strangulated  inguinal  hernia,  and  its  near  proximity  to 
the  upper  and  outer  side  of  the  femoral  ring  should  not  be  forgotten  in  the  operation 
for  femoral  hernia.  The  artery  is  accom])anie(l  l)y  two  veins,  of  which  the  inner  is 
the  larger.  They  end  in  a  single  trunk  before  opening  into  the  external  iliac 
vein. 

The  deep  epigastric  gives  off  the  following  small  branches: — (a)  The  cremas- 
teric, which  runs  with  the  vas  through  the  inguinal  canal,  supplies  the  eremaster 
muscle,  and  anastomoses  Avith  the  spermatic,  inferior  external  pudic,  and  sujierfieial 
]terinfeal  arteries,  (b)  The  pubic,  which  ])asses  below,  or  sometimes  above,  the 
femoral  xmn  to  the  l)ack  of  the  pul)es,  where  it  anastomoses  with  the  pubic  branch 


578  THE  ARTERIES 

of  the  obturator  and  the  corresponding  vessel  of  the  opposite  side.  This  branch, 
though  usually  small,  is  occasionally  considerably  enlarged,  when  its  exact  course  be- 
comes of  great  interest  to  the  surgeon.  Thus  it  may  descend  immediately  internal  to 
the  vein,  and  therefore  external  to  the  femoral  ring,  or  it  may  pass  inwards  in  front 
of  the  femoral  ring  and  turn  downwards  either  l)ehind  the  os  ]Hibis  or  immediately 
behind  the  free  edge  of  Gimbernat's  ligament,  in  wliich  situation  it  would  be 
exposed  to  injury  in  the  operation  for  the  relief  of  a  strangulated  femoral  hernia, 
(c)  The  muscular,  which  'supply  the  rectus  and  the  oblique  and  transverse 
muscles  of  tlie  abdomen,  and  anastomose  with  the  lower  intercostal  and  the  lumbar 
arteries,  (rf)  The  cutaneous,  which  pierce  the  rectus,  and  supply  the  skin,  anas- 
tomosing with  branches  of  the  superficial  epigastric.  And  (e)  the  terminal, 
Avhich  anastomose  above  the  umbilicus  with  the  superior  epigastric  branch  of  the 
internal  mammary. 

Variations. — (A)  Tlie  epigastric  may  come  off  from  the  external  iliac  higher  than  usual  ; 
it  has  been  met  with  arising  as  much  as  two  inches  and  a  half  above  Poupart's  ligament.  (B) 
It  may  arise  from  the  femoral  below  Poupart's  ligament,  or  even  from  the  profunda.  (C)  It 
may  arise  as  a  common  trunk  with  the  circumflex  iliac.  (D)  It  is  sometimes  double.  (E)  It  may 
arise  from  the  obturator,  or  conver.selj'  it  may  give  oif  the  obturator  artery.  This  variation  is 
due  to  the  enlargement  of  the  normal  anastomosis  of  the  epigastric  and  obturator  through  their 
pubic  branches.  It  is  of  considerable  importance  to  the  surgeon,  since  the  obturator  artery, 
when  given  off  from  the  epigastric,  may  run  either  external  or  internal  to  the  femoral  ring  to 
reach  the  obturator  foramen.  This  abnormal  origin  of  the  obturator  is  said  to  occur  once  in  eveiy 
three  subjects  and  a  half;  but  the  abnormal  artery  only  courses  round  the  inner  side  of  the  ring — 
in  which  situation  it  is  liable  to  injury  in  the  operation  for  femoral  hernia — in  exceptional  cases. 
According  to  Langton  (Holden's  'Anatomy  '),  the  chances  are  about  seventy  to  one  against  this 
occurring.  But  even  when  it  takes  the  abnormal  course,  it  lies  a  line  and  a  half  or  so  from  the 
margin  of  the  ring,  and  will  probably  escape  injury  in  the  division  of  the  stricture  if  several  short 
notches  are  made  in  jjlace  of  a  single  and  longer  incision. 


(2)  The  Deep  Circimflex  Iliac  Artery 

The  deep  circumflex  iliac  arises  from  the  outer  side  of  the  external  iliac 
artery,  either  opposite  the  epigastric  or  a  little  below  the  origin  of  that  vessel.  It 
courses  upwards  and  outwards  just  above  the  lower  margin  of  Poupart's  ligament, 
lying  between  the  fascia  transversalis  and  the  peritoneum,  or  at  times  in  a  fibrous 
canal  formed  by  the  union  of  the  fascia  transversalis  with  the  iliac  fascia.  Near  the 
anterior  superior  spine  of  the  ilium,  it  perforates  the  transversalis,  and  then  courses 
between  that  muscle  and  the  internal  oblique,  along  and  a  little  above  the  crest  of 
the  ilium.  It  finally  divides  into  an  ascending  branch,  which  anastomoses  with  the 
lumbar  and  lower  intercostal  arteries,  and  a  marginal  branch  which  runs  backwards 
to  anastonrose  with  the  ilio-lumbar  artery.  It  is  accompanied  by  two  veins.  These 
unite  into  one  trunk,  which  then  crosses  the  external  iliac  artery  to  join  the  external 
iliac  vein. 

The  deep  circumflex  iliac  artery  gives  off  the  following  branches:  —  (a) 
Muscular  branches,  which  supply  the  psoas,  iliacus,  sartorius,  tensor  fasciae  fem- 
oris,  and  the  oblique  and  transverse  muscles  of  the  abdomen.  One  of  these  branches, 
larger  than  the  rest,  usually  arises  about  an  inch  behind  the  anterior  superior  spine 
of  the  ilium  and  ascends  perpendicularly  between  the  transversalis  muscle  and  the 
internal  oblique.  It  has  received  no  name  but  is  important  to  the  surgeon,  as  it 
indicates  the  intermuscular  plane  between  the  two  muscles,  {h)  Cutaneous 
branches,  which  supply  the  skin  over  the  course  of  the  vessel,  and  anastomose 
with  the  superficial  cireumfiex  iliac,  the  gluteal,  and  the  ascending  branch  of  the 
external  circumflex. 

Variations. — (A)  The  circumflex  iliac,  like  the  epigastric,  may  be  given  oiT  from  the  external 
iliac  higher  than  normal,  th(.»ugh  seldom  if  ever  as  high  as  the  latter.  (B)  More  rarely  it  may 
come  oft"  from  the  femoral  below  Poupart's  ligament.  (C)  It  may  arise  as  a  common  trunk  with 
the  epigastric.     (D)  It  may  be  doubb. 


FEMORAL  579 


T?TE  FEMORAL  ARTERY 

The  femoral  artery  (fig.  o72)  is  the  continuation  of  the  external  ihac,  and 
extends  from  the  lower  l)order  of  Poupart's  ligament,  down  the  front  and  inner  part 
of  the  thigh,  to  the  tendinovis  opening  in  the  adductor  magnus,  through  which  it 
passes  into  the  popliteal  space,  and  is  then  known  as  the  popliteal.  The  femoral 
artery  is  at  first  quite  su})erficial,  being  merely  covered  by  the  skin,  and  superficial 
and  deep  fascia;  but,  after  thus  passing  about  five  inches  (13  cm.)  in  a  direction 
downwards  and  inwards  through  the  space  known  as  Scarpa's  triangle,  it  sinks  at 
the  apex  of  that  triangle  beneath  the  sartorius  muscle,  and  thence  to  its  termina- 
tion continues  beneath  the  sartorius,  coursing  deeply  between  the  vastus  internus 
and  adductor  muscles  in  the  si)ace  known  as  Hunter's  canal.  It  at  first  rests  upon 
the  brim  of  the  pelvis  and  head  of  the  thigh  Ijone,  from  which  it  is  merely  sepa- 
rated by  the  capsule  of  the  hip-joint  and  the  tendon  of  the  psoas.  Here  it  can  be 
readily  compressed.  Owing  to  the  obliquity  of  the  neck  of  the  femur  and  the 
direct  course  taken  by  the  artery,  it  lies  lower  down  only  on  muscles,  at  some  little 
distance  from  the  bone  (fig.  373).  At  its  termination,  in  consequence  of  the  shaft  of 
the  femur  inclining  towartls  the  middle  line  of  the  body,  the  artery  lies  close  to  the 
bone,  but  to  the  inner  side.  The  course  of  the  vessel  when  the  thigh  is  slightly 
fiexed  and  abducted — the  position  in  which  the  limb  is  placed  when  the  vessel  is 
ligatured — is  indicated  by  a  line  drawn  from  a  spot  midway  betw^een  the  anterior 
su|)erior  spine  of  the  ilium  and  the  symphysis  pubis  to  the  adductor  tubercle. 
When  the  thigh  is  in  the  extended  position  and  parallel  to  its  fellow,  the  course  of 
the  artery  will  correspond  to  a  line  drawn  from  the  spot  above-mentioned  to  the 
inner  border  of  the  patella. 

The  artery  for  about  the  first  inch  and  a  half  to  two  inches  (4  to  5  cm. )  is  known 
as  the  common  femoral,  but  at  this  distance  from  Poupart's  ligament  it  gives  off  a 
large  branch  called  the  profunda,  or  deep  femoral.  For  the  rest  of  its  course  it  is 
known  as  the  superficial  femoral.  The  superficial  femoral  is  only  superficial  where 
it  lies  in  Scarpa's  triangle — that  is,  for  about  three  and  a  half  inches  (9  cm.)  of  its 
course;  the  remainder  of  the  artery  being  deeply  placed  in  Hunter's  canal,  though 
less  deeply  than  the  profunda,  or  deep  femoral.  The  details  of  the  anatomy  of  the 
femoral  will  perhaps  best  be  studied  by  considering  the  relations  of  (1)  the  common 
femoral;  (2)  the  superficial  femoral  as  it  lies  in  Scarpa's  triangle;  and  (3)  the 
superficial  femoral  as  it  lies  in  Hunter's  canal. 

(1)  The  relations  of  the  common  femoral  artery. — In  front,  the  common 
femoral  (fig.  372)  is  covered  by  the  skin,  the  superficial  fascia,  the  iliac  portion  of 
the  fascia  lata,  the  crural  branch  of  the  genito-crural  nerve,  the  superficial  circumflex 
iliac  vein,  and  sometimes  the  superficial  epigastric  vein.  The  fascia  transversalis, 
which  is  continued  downwards  into  the  thigh  beneath  Poupart's  ligament,  is  also 
one  of  its  anterior  relations,  but  soon  becomes  indistinguishable  from  the  sheath  of 
the  vessel. 

Behind,  the  artery  rests  upon  the  tendon  of  the  psoas  muscle,  Avhich  separates 
it  from  the  brim  of  the  pelvis  and  capsule  of  the  hip-joint,  and,  a  little  lower,  on 
the  pectineus,  more  or  less  loose  fat  and  cellular  tissue  intervening.  The  branches 
of  the  anterior  crural  nerve  to  the  pectineus  muscle  also  pass  behind  it. 

A  similar  prolongation  to  that  derived  from  the  fascia  transversalis  in  front 
descends  behind  the  vessel  from  the  iliac  fascia;  but,  like  the  anterior  prolongation 
of  fascia,  soon  blends  with  the  sheath  of  the  vessels. 

To  the  inner  side  is  the  femoral  vein,  but  separated  from  the  artery  in  the 
upper  part  of  its  course  by  a  thin  layer  of  fascia  ])assing  from  the  continuation  of 
the  iliac  fascia  behind  the  vessels,  to  the  continuation  of  the  f:is(>ia  transversalis  in 
|ront  of  the  vessels. 

To  the  outer  side  is  the  leash  of  nerves  known  as  the  anterior  crural.  These 
are,  howev(>r,  separated  from  the  artery  by  a  few  fibres  of  the  ])soas  muscle. 

(2)  The  relations  of  the  superficial  femoral  artery  in  Scarpa's  triangle 
(fig.  372). — In  front,  the  artery  is  covere<l  by  the  .-^kin  and  by  the  superficial 
and  deep  fascia,  and  is  crossed'at  the  lower  part  of  Scarpa's  triangle  by  a  branch 
of  the  internal  cutaneous  nerve.     The  crural   branch  of  the  genito-crural  nerve 


580 


THE  ARTERIES 


is  superficial  to  it,  InU  is  se])arated  from  this  part  of  the  femoral  artery  by 
the  (lee|)  fasria. 

Behind,  the  artery  lies  on  the  peetincus,  from  wliicli  it  is  separated  by  the 
femoral  vein  and  the  profunda  vein  and  artery.  Lower  down,  it  lies  on  the  upper 
portion  of  the  adductor  longus  muscle. 

To  its  outer  side  is  tlie  long  saphenous  nerve  and  the  nerve  to  the  vastus  internus, 
the  anterior  crural  nerve  having  in  this  situation  more  or  less  broken  up  into  its 
components. 

Fig.  372. — The  Femoral  Aktery  ix  Scarpa's  Triangle. 
(From  a  dissection  by  W.  J.  Walsham  iu  St.  Bartholomew's  Hospital  Museum.) 

Common  iliac  artery 
S  YMPA  THETIC  NEE  VE 
Middle  sacral  artery 


Common  iliac  vein 

URETER 

Internal  iliac  artery 

External  iliac  vein 

External  iliac  artery 
Posterior  branch  of  internal  iliac  dividing  into 
gluteal  and  ilio-lumbar  arteries 

Lateral  sacral  ar 
SAGRAL  PLEXUS 
OB  TL'RA  TOR  NER  VE 
Obturator  artery 
Obliterated  hypogastric 
Superior  vesical  artery 
Edge  of  levator  ani 

Pudic  artery 

BLADDER 

Middle  vesical  artery 

JJeep  epigastric  artery 
Pubic  branch  of  epi- 
gastric artery 
Common  femoral  artery 

Lona  saphenous  vein 
Pectineus  muscle 


Internal  circumflex  artery  . — "jf**y|ijj , 

Adductor  brevis 

OBTCRA  TOR  NERVE  (ant.  branch) 

Profunda  artery 

Adductor  longus,  hooked  aside 

Superficial  femoral  artery  and  vein 

Graeilia  muscle 
Lower  part  of  sartorius 


Psoas  muscle 

Ilio-lumbar  artery 

EXTERNAL  CUTA- 
NEOUS NERVE 

Iliacus  muscle 

GENI  TO-CRURAL 
NERVE 

ANTERIOR  CRU- 
RAL NERVE 

Peep  circnnifiex  iliac 

artery 
Superficial  circumflex 

iliac  artery 
ASTER  10 R  CRfRAL  X. 
Gluteal  artery  and 


supe 


gluteal  i 


Tensor  fasciae  femoris 

hooked  aside) 
Gluteus  medius  and 

minimus 
Sartorius  muscle 
Ml  PULE  CUTA- 
NEOUS NERVE 

NERVE  TO  RECTUS 

NERVE  TO  VASTCS 

EXTERNUS 
External  circumflex  ar. 

XERVE  TO  fRTRErS 

Hectus,  hooked  aside 

Profunda  vein 

LONG  SAPHENOUS 
NERVE  ANI) 
NERVE  TO  VAS- 
1  US  INTERNUS 


Vastus  internus 
muscle 


To  its  inner  side  is  the  femoral  vein,  which,  however,  at  the  apex  of  Scarpa's 
triangle,  is  getting  somewhat  behind  the  artery. 

The  superficial  femoral  varies  in  length  according  to  the  distance  that  the  pro- 
funda is  given  off  from  the  common  femoral  below  Poupart's  ligament.  As  a  rule, 
it  measures  three  inches  and  a  half  (9  cm. ),  the  commim  an  inch  and  a  half  (4  cm. ). 
Hut  the  profunda  may  come  off  two  or  more  inches  below  Poupart's  ligament,  in 
which  case  the  superficial  femoral  will  be  shorter  to  this  extent;  or  it  may  come  off 
less  than  an  inch  and  a  half  below  Pcnipart's  ligament,  or  even  from  the  external 
iliac  a1)0ve  Poupart's  ligament,  wlicn  the  superficial  will  be  longer  tlian  normal.    The 


FEMORAL  581 

practical  jjoint  to  rcniciul)or  is  that  it  is  more  usual  to  luoct  with  a  short  than  with 
a  long  connnon  femoral,  and  that,  if  the  superficial  femoral  is  tied  at  the  apex  of 
Scarpa's  triangle — i.e.  the  spot  where  the  inner  edge  of  the  sartorius  comes  into 
contact  with  the  adductor  longus — there  is  nearly  always  a  sufficient  length  of  that 
vessel  ahove  tlie  ligature  to  ensure  a  firm  internal  clot,  and  consequently,  as  far  as 
this  point  is  concerned,  a  successful  result. 

(3)  The  relations  of  the  superficial  femoral  artery  in  Hunter's  canal. — 
Hunter's  canal  is  the  somewhat  triangularl}^  shaped  space  bounded  by  the  vastus 
internus  on  the  outer  side,  the  adductors  longus  and  magnus  on  the  inner  side,  and 
by  an  aponeurosis  thrown  across  from  the  adductors  to  the  vastus  in  front. 
Below,  the  canal  terminates  at  the  opening  in  the  adductor  magnus;  above,  its 
limit  is  less  well  defined,  as  here  the  aponeurosis  between  the  muscles  becomes  less 
tendinous,  and  gradually  fades  away  into  the  perimuscular  fascia.  The  transverse 
direction  of  the  fibres  of  the  aponeurotic  covering  at  the  lower  two-thirds  of  the 
canal  is  characteristic,  and  serves  as  a  rallying  point  in  tying  the  artery  in 
this  part  of  its  course.  Lying  superficial  to  the  aponeurosis  is  the  sartorius 
muscle.  The  superficial  femoral  artery  as  it  lies  in  this  canal  has  the  following 
relations: — 

In  front,  in  addition  to  the  skin,  superficial  and  deep  fascia,  are  the  sartorius 
muscle  and  the  aponeurotic  fibres  of  the  canal.  The  internal  saphenous  nerve 
crosses  the  artery  from  without  inwards,  lying  in  the  wall  of  the  canal. 

Behind  is  the  angle  of  meeting  of  the  vastus  internus  and  the  adductors. 

The  femoral  vein  lies  behind  the  artery,  but  gets  a  little  external  to  it  at  the 
lower  part  of  the  canal.  It  is  here  very  firmly  and  closely  attached  to  the  artery, 
embracing  it  as  it  were  on  its  po.sterior  and  external  aspect.  Hence  it  is  very  liable 
to  be  punctured  on  ligaturing  the  artery  in  this  part  of  its  course.  Such  an  acci- 
dent is  best  avoided  by  opening  the  sheath  of  the  vessels  well  to  the  inner  side  of 
the  front  of  the  artery,  and  by  keeping  the  point  of  the  aneurysm  needle  closely 
applied  to  the  vessel  in  passing  it  from  without  inwards  between  the  vein  and  the 
artery.  There  are  sometimes  two  veins,  which  then  more  or  less  surround  the 
artery. 

To  its  inner  side  is  the  adductor  longus  above  and  the  adductor  magnus 
below. 

To  its  outer  side  is  the  vastus  internus,  the  nerve  to  the  vastus  internus,  and 
at  the  lower  part  of  the  canal  the  femoral  vein. 

Vdrldtions  in   the  Femoral  Artery 

The  most  important  variations  in  the  femoral  artery  are  : — (A)  The  femoral  arising  from 
the  sciatic  or  internal  iliac,  and  pa.ssing  out  of  the  pelvis  and  down  the  back  of  the  thiirh  with 
the  great  sciatic  nerve  to  the  popliteal  space  ;  the  external  iliac  under  these  circumstances  ending 
in  the  profunda  or  external  circumflex,  or  some  other  branch  of  the  femoral.  (B)  A  dduble 
condition  of  the  femoral  artery  below  tlie  origin  of  the  profunda  ;  the  vessel  re-uniting  lower 
down  the  thigh.  (C)  A  vas  aberrans  given  off  from  the  iimer  side  of  the  common  femoral  or 
external  iliac,  and  joining  the  femoral  lower  down.  (D)  The  vein  may  remain  to  the  inner  side 
of  the  arteiy  its  whole  distance  through  the  thigh,  or  it  may  be  double,  especially  in  Hunter's 
canal.  There  is  often  a  plexiform  arrangement  of  the  vein  around  the  artery  in  this  situation. 
(E)  The  variations  in  the  origin  of  the  profunda  have  been  already  mentioned. 

Branches  of  the  Femoral  Artery 

The  femoral  artery  gives  off  the  following  branches: — 

A.  From  the  com'mon  femoral : — (1)  The  superficial  epigastric;  (2)  the  super- 
ficial circumflex  iliac;  (3)  the  superficial  external  i)udic;  (4)  the  deep  external 
pudic;  and  (5)  the  profunda. 

B.  From  the  superficial  femoral  in  Scarpa's  triangle:— (1)  Muscular  l>ranchcs; 
and  (2)  the  saphenous  branch. 

C.  From  the  superficial  femoral  in  Hunter's  canal: — O)  Muscular  branches; 
and  (2)  the  anastomotica  magna. 


582 


THE  ARTERIES 


Fig.  373. — To  show  the  Anastomoses  of  the  Akteries  of  the  Lower  Extkemity. 

(After  Siiiitli  and  Walsham.) 


Deep  epigastric  artery  -r- 

llio-lumbar  artery  


Deep  circumflex  iliac  artery  ■ 
Gluteal  artery . 

Common  femoral  artery  ■ 

Profunda  artery  ■ 

External  circumflex  artery 

Crucial  anastomosis 


Abdominal  aorta 
Common  iliac  artery 
Middle  sacral  artery 
Internal  iliac  artery 
External  iliac  artery 
Obturator  artery 
Sciatic  artery 
P.idic  artery 

Internal  circumflex  artery 
Superficial  femoral  artery 


Perforating  branc/ies  ofprofunda 


Popliteal  artery 


Anastomotica  magna 

Terminal  branch  ofprofunda  anastomosing 
with  popliteal 


Superior  external  articular 


Superior  internal  articular 


Inferior  external  articular 
External  lateral  ligament 

Tibial  recurrent  ■ 


Anterior  tibial  artery 


Peroneal  artery  . 


External  malleolar  branch 
Anterior  peroneal  artery 
Posterior  peroneal  artery 

External  plantar  artery 


Internal  lateral  ligament 
Inferior  internal  articular 
Posterior  tibial  artery 


■  Internal  malleolar  branch 


Tarsal  branch 
Dorsalis  pedis  artery 
Metatarsal  branch 


BRANCHES  OF  COMMON  FEMORAL  583 

A.    Brunches  of  tlic  Common  Femoral 

(1)  The  superficial  epigastric  artery  t-oiiR's  off  from  the  femonil  about  half 
an  inch  below  Poupart's  lit^anient.  At  its  ori.uin  it  is  l)eneath  the  fascia  lata,  but 
almost  at  once  passes  throutfh  this  fascia,  or  else  through  the  saphenous  opening, 
and  courses  upwards  and  inwards  in  front  of  the  external  oblique  nuiscle  almost  as 
far  as  the  umbilicus.  It  ends  in  numerous  small  twigs,  which  anastouKjse  with 
the  cutaneous  branches  from  the  deep  epigastric  and  internal  mammary.  In  its 
course  it  gives  off'  small  Ijranches  to  the  inguinal  glands  and  to  the  skin  and  super- 
ficial fasciae.  Running  Avith  it  is  the  superficial  epigastric  vein,  which  ends  in  the 
long  saphenous  just  before  the  latter  passes  through  the  saphenous  opening. 

(2)  The  superficial  circumflex  iliac  artery  (fig.  372),  usually  smaller  than 
the  superficial  epigastric,  arises  either  in  common  with  that  vessel,  or  else  as  a 
separate  l)ranch  from  the  femoral.  It  passes  upwards  and  outwards  over  the 
iliacus,  and,  soon  perforating  the  fascia  lata  a  little  to  the  outer  side  of  the  sa})he- 
nous  opening,  runs  more  or  less  parallel  to  Poupart's  ligament  about  as  far  as  the 
crest  of  the  ilium,  where  it  ends  in  branches  which  anastomose  with  the  deep  cir- 
cumflex iliac  artery.  In  its  course  it  gives  off"  branches  to  the  iliacus  and  sartorius 
muscles,  to  the  inguinal  glands,  and  to  the  fascia  and  skin.  Its  companion  vein, 
the  superficial  circumflex  iliac,  ends  in  the  long  saphenous  vein  just  before  the 
Litter  passes  through  the  saphenous  opening. 

(3 )  The  superficial  or  superior  external  pudic  artery  arises  from  the  inner 
side  of  the  femoral,  either  a  little  above  or  else  in  connnon  with  the  deep  or  inferior 
external  pudic.  It  passes  either  through  the  fascia  lata,  or  else  through  the  criliri- 
form  fascia  covering  the  saphenous  opening,  ascends  upwards  and  inwards  over  the 
s|)ermatic  cord  in  the  male,  or  round  ligament  in  the  female,  and  divides  into 
l)ranches,  one  of  which  supplies  the  integuments  above  the  pubes,  while  another 
descends  along  the  penis  external  to  the  dorsal  arter}^  with  Avhich,  and  with  the 
corresj)onding  artery  of  the  opposite  side,  it  anastomoses  at  the  corona.  In  the 
female,  this  branch  terminates  in  the  preputium  clitoridis,  anastomosing  with 
the  dorsal  artery  of  that  organ.  Small  branches  also  descend  to  the  scrotum  and 
labium  respectively.  As  it  crosses  the  cord  it  anastomoses  with  the  cremasteric 
branch  of  the  deep  epigastric.  It  is  accompanied  by  tAvo  small  veins,  which 
usually  join  to  form  a  single  vein  opening  into  the  upper  end  of  the  long 
saphenous. 

(4)  The  deep  or  inferior  external  pudic  artery  arises  from  the  inner  side  of 
tlie  femoral  artery,  either  in  common  with  the  preceding  branch  or  a  little  lower 
down.  It  runs  inwards  beneath  the  deep  fascia,  across  the  pectineus  and  adductor 
longus  muscles,  and,  perforating  the  fascia  close  to  the  ramus  of  the  pubes,  supplies 
the  skin  of  the  scrotum  or  the  corresponding  part,  the  labium  majus,  in  the  female, 
anastomosing  with  the  superficial  perinseal  branch  of  the  internal  pudic.  It  sup- 
]>lies  small  twigs  to  the  pectineus  and  adductor  muscles  as  it  crosses  them.  Its 
companion  veins  terminate  as  a  single  trunk  in  the  long  saphenous. 

(5)  The  profunda  or  deep  femoral  artery  (figs.  372,  373)  is  the  chief  nutrient 
vessel  of  the  thigh.  It  is  usually  given  off  from  the  back  and  outer  part  of  the 
common  femoral,  about  an  inch  and  a  half  (4  cm.)  below  Poupart's  ligament.  At 
tirst  it  is  a  little  external  to  the  femoral,  but  as  it  runs  downwards  and  backwards 
it  gets  behind  that  artery  and  closer  to  the  bone.  On  reaching  the  uj^per  border  of 
the  adductor  iongus  nuiscle,  it  leaves  the  femoral,  and,  passing  beneath  the  muscle, 
1  tierces  the  adductor  magnus,  and  finally,  much  reduced  in  size,  ends  in  the  ham- 
string muscles. 

Relations. — Behind,  the  artery  lies  successively  upon  the  iliacus,  the  pectineus, 
the  adductor  Itrevis,  antl  adductor  magnus  muscles.  In  front,  at  tirst  it  is  super- 
ficial, being  merely  covered  l)y  the  skin,  superficial  and  deep  fascia\  and  branches 
of  the  anterior  crural  nerve;  Init  as  it  sinks  behind  the  femoral  artery,  it  has  in 
front  of  it  both  the  femoral  and  the  profunda  veins,  and  lower  down  the  adductor 
longus  muscle.  Externally  is  the  fenun-  at  the  angle  of  union  of  the  adductors 
longus  and  brevis.      Internally  is  the  pectineus  at  the  upper  part  of  its  course. 

Branches  of  the  profunda. — The  jtrofunda  gives  oft"  the  following  branches: 
— (a)  The  external  circumflex;   {b)  the  internal  circumflex:  and  (c)  the  three  per- 


584  THE  ARTERIES 

forating.  The  termination  of  tlie  artery  is  sometimes  called  the  fourth  perforating 
Ijranch. 

(a)  The  external  circumflex,  a  short  trunk,  Init  the  largest  in  diameter  of  the 
hranches  of  the  artery,  arises  from  the  outer  side  of  the  profunda  as  it  lies  on  the 
iliacus  muscle,  about  three-quarters  of  an  inch  (2  cm.)  below  the  origin  of  that 
vessel  from  the  femoral.  It  passes  transversely  outwards  over  the  iliacus,  under 
the  sartorius  and  rectus,  and  between  the  branches  of  the  anterior  crural  nerve. 
In  this  course  it  gives  off  branches  to  the  rectus  and  crureus,  and  then  divides  into 
three  chief  sets  of  branches — an  ascending,  transverse,  and  descending. 

(i)  The  ascending  branch,  consisting  of  one  or  more  separate  vessels,  runs 
upwards  beneath  the  sartorius;  then,  sinking  deeply  beneath  the  tensor  fasciiu 
femoris  on  the  outer  side,  and  the  gluteus  medius  and  minimus  on  the  inner  side, 
anastomoses  with  the  superior  gluteal  and  the  deep  circumflex  iliac  arteries.  This 
branch  also  supplies  a  twig  which  runs  upwards  under  the  rectus  to  the  hip-Joint. 

(ii)  The  transverse  branch,  or  branches,  run  transversely  outwards,  and, 
winding  over  the  crureus  and  piercing  the  vastus  externus,  anastomose  towards  the 
back  of  the  thigh  with  the  superior  perforating  liranch  of  the  profunda,  the  sciatic, 
and  internal  circuintlex  arteries.  These  branches  will  usually  be  found  a  little 
below  the  great  trochanter. 

(iii)  The  descending  branches  run  directly  downwards  along  with  the  nerve 
to  the  vastus  externus  muscle.  They  lie  beneath  the  rectus  muscle  and  on  the 
crureus  or  vastus  externus,  some  of  them  being  just  under  cover  of  the  anterior 
edge  of  the  latter  muscle.  The}'^  are  distributed  to  the  vastus  externus,  crureus, 
and  rectus,  one  branch  usually  running  along  the  anterior  border  of  the  vastus 
externus  as  far  as  the  knee-Jomt,  where  it  anastomoses  with  the  superior  external 
articular  liranch  of  the  popliteal  (fig.  376);  another,  entering  the  crureus,  anasto- 
moses with  the  lower  perforating  branch  of  the  profunda  and  Avith  the  anastomotica 
magna. 

Variations  of  the  external  circumflex. — (A)  It  may  come  off  from  the  femoral  above  tlie 
profunda.  (B)  It  may  be  double,  one  branch  coiuinsr  off  from  the  femoral,  and  one  from  the 
profunda,  or  botli  from  the  profunda,  or  both  from  the  femoral  above  the  profunda. 

(h)  The  internal  circumflex  artery  comes  off  from  the  back  and  inner  part  of 
the  profunda  artery  on  al)()Ut  tlie  same  level  as  the  external  circumflex;  sometimes 
as  a  common  trunk  with  that  vessel.  As  it  winds  round  the  inner  side  of  the 
femur  to  reach  the  region  of  the  trochanters,  it  lies  successively,  first,  Ijetween  the 
psoas  and  pectineus,  then  between  the  obturator  externus  and  adductor  brevis; 
finally,  between  the  adductor  magnus  and  quadratus  femoris,  where  it  anastomoses 
Avith  the  external  circumflex  externally,  with  the  sciatic  above,  and  with  the 
superior  perforating  below,  forming  the  so-called  crucial  anastomosis.  As  it  passes 
between  the  obturator  externus  and  adductor  l)revis,  it  gives  oft'  two  or  more 
branches  to  the  adductor  longus,  the  adductor  ])revis,  the  gracilis,  and  the  ol)turator 
externus,  and  anastomoses  with  the  oltturator  artery.  Another  small  liranch 
usually  courses  upwards  and  outwards  beneath  the  tendon  of  the  psoas,  and  enters 
the  hip-joint  beneath  the  transverse  ligament,  and,  together  Avith  the  articular  In-anch 
of  the  obturator,  supplies  the  fatty  tissue  in  the  acetal)ulum,  and  sends  branches  to 
the  synovial  membrane.  As  it  lies  beneath  the  adductor  brevis,  it  gives  off*  a 
descending  branch  to  the  adductor  magnus  and  brevis.  This  branch  is  generally 
accompanied  by  the  posterior  division  of  the  ol)turator  nerve.  Before  passing 
betAveen  the  quadratus  femoris  and  adductor  magnus,  a  small  l)ranch  runs 
upAvards  Ijcneath  the  (juadratus  femoris  to  sui)i)ly  the  back  of  the  hip-joint,  and 
anastomoses  Avith  the  gluteal  and  sciatic  arti-ries.  Its  comi)anion  veins  join  the 
profunda  vein. 

Variations  of  the  internal  circumflex. — (A)  It  may  come  off  from  the  profunda  artery  before 
tlie  external  eircumflex.  (Bj  It  may  arise  from  the  femoral  artery;  or  (C)  from  the  external 
iliac  or  one  of  its  branches. 

(c)  The  perforating  arteries  of  the  profunda  are  so  called  because  they  per- 
forate, in  a   more  or  less  regular   manner  I'niiu  above  doAViiAvards.  certain  of  the 


BRANCHES   OF  SUPERFICIAL   FEMORAL  585 

adductor  muscles.  Tliey  form  a  series  of  loop.-;  by  anastomosinsr  with  one  another 
(fig.  373),  and  with  the  gluteal,  internal  eircumtlex,  and  sciatic  arteries  above, 
and  with  the  muscular  and  articular  branches  of  the  ])opliteal  below.  They  are 
distributed  chiefly  to  the  liamstring  nuiscles,  but  send  twigs  along  the  external 
intermuscular  septum  to  supply  the  integuments  at  the  back  and  outer  parts  of 
the  tliigh.  Other  branches  perforate  the  external  intermuscular  septum  and  the 
short  head  of  the  biceps,  and,  entering  the  crureus  and  vastus  externus,  anasto- 
mose with  the  descending  branch  of  the  external  circumflex.  All  the  perforating 
arteries,  moreover,  contribute  to  reinforce  the  artery  of  the  sciatic  nerve,  a  branch 
of  the  sciatic  artery.  They  are  each  accompanied  by  two  veins  which  terminate  in 
the  profunda. 

(i)  The  superior  or  first  perforating  is  given  off  from  the  profunda  as  that 
vessel  sinks  beneath  the  adductor  longus.  It  either  pierces  the  adductor  brevis, 
or  else  runs  l)etween  the  pectineus  and  adductor  brevis,  and  then  passes  through  a 
small  aponeurotic  opening  in  the  adductor  magnus  close  to  the  inner  lip  of  the 
linea  aspera.  In  this  course  it  supplies  branches  to  the  adductors,  and,  after 
perforating  the  adductor  magnus,  is  distributed  to  the  lower  part  of  the  gluteus 
maximus  and  the  hamstring  muscles,  one  branch  commonly  running  upwards 
beneath  the  gluteus  maximus  to  anastomose  with  the  external  circumflex,  internal 
circumflex,  and  sciatic  arteries,  forming  the  crucial  anastomosis  at  the  junction 
of  the  neck  of  the  femur  with  the  great  trochanter  (fig.  373).  A  second  branch 
descends  to  anastomose  with  the  asctMiding  branch  of  the  middle  perforating. 

(ii)  The  middle  or  second  perforating,  Avhich  is  given  oflf  from  the  profunda 
as  it  lies  behind  the  adductor  longus,  pierces  the  adductor  brevis,  and  then  passes 
through  a  second  aponeurotic  opening  in  the  adductor  magnus  a  little  below  that 
for  the  first  perforating  artery,  and  also  close  to  the  linea  aspera.  It  supplies  the 
hamstring  muscles,  sends  a  branch  upwards  to  anastomose  with  the  descending 
branch  of  the  superior  perforating,  and  another  downwards  to  anastomose  in  like 
manner  with  the  ascending  branch  of  the  third  perforating.  It  usually  supplies 
the  chief  nutrient  branch  to  the  femur.  At  times,  however,  this  comes  from  the 
third  ))erforating. 

(iii)  Tlie  inferior  or  third  perforating  also  arises  from  the  profunda  as  it  lies 
under  the  adductor  longus,  usually  about  the  level  of  the  lower  liorder  of  the 
adductor  brevis.  It  turns  beneath  this  border,  and  then,  like  the  first  and  second 
perforating,  passes  through  an  aponeurotic  opening  in  the  adductor  magnus  close 
to  the  linea  aspera.  It  also  supplies  the  hamstring  muscles,  and  divides  into  two 
branches,  which  anastomose  above  with  the  second  perforating,  and  bi^low  witli  the 
termination  of  the  profunda  or  the  fourth  perforating. 

(iv)  The  fourth  perforating  is  the  continuation  of  the  profunda.  It  passes 
through  an  aponeurotic  o])ening  in  the  adductor  magnus  just  above  the  opening 
for  tlie  femoral  artery.  It  anastomoses,  above  with  the  third  perforating,  and  below 
with  the  superior  muscidar  and  articular  branches  of  the  popliteal.  It  supplies 
chiefly  the  short  head  of  the  biceps. 

B.   Branches  of  the  Superficial  Femoral  in  Scarpa^ s  Triangle 

The  branches  given  off  by  the  superficial  finnoral  in  Scarpa's  triangle  are  usually 
small  and  insignificant.  They  are: — ( 1  )  Muscular,  to  the  sartorius  and  rectus;  and 
(2)  saphenous,  to  the  region  of  the  long  sajihenous  vi'in  and  femoral  lymphatics 
in  the  neighbourhood  of  the  vein. 

C.   Branches  of  the  Superficial  Femoral  in  Hunter'' s  Canal 

The  branches  in  Hunter's  canal  are:— (1)  Muscular:  and  (2)  the  anastomotica 
magna. 

(1 )  The  muscular  branches  sujiply  the  sartorius.  the  rectus,  the  vastus  internus, 
the  crureus,  and  the  adiluctor  muscles.'  They  are  usually  larger  than  the  mu.scular 
branches  given  off  in  Scarpa's  triangle. 

(2)  The  anastomotica  magna  arises  from   tlie   front  an<l   inner  side  of  the 


586  THE  ARTERIES 

femoral  just  before  the  latter  perforates  the  adductor  magnus  muscle,  and  almost 
immediately  divides  into  two  branches,  (a)  a  superficial  and  {h)  a  deep.  These 
branches  may  sometimes  come  off  separately  from  the  femoral. 

(a)  The  superficial  branch  pierces  the  aponeurotic  covering  of  Hunter's  canal, 
passes  between  tlic  sarturius  and  gracilis  muscles  along  with  the  internal  sa})henous 
nerve,  and,  perforating  the  deep  fascia,  supplies  the  skin  of  the  upper  and  inner 
side  of  the  leg  and  anastomoses  with  the  inferior  internal  articular  branch  of  the 
popliteal  and  the  other  vessels  forming  the  plexus  or  rete  at  the  inner  side  of  the 
knee.  In  its  course  it  gives  twigs  to  the  lower  part  of  the  sartorius  and  gracilis 
muscles. 

{h)  The  deep  branch  runs  downwards  in  front  of  the  adductor  magnus  tendon, 
burrowing  amongst  the  fibres  of  the  vastus  internus  as  far  as  the  internal  condyle, 
where  it  passes  into  the  plexus  or  rete  on  the  inner  side  of  the  knee-joint, 
anastomosing  with  the  internal  inferior  articular  branch  of  the  popliteal,  the 
anterior  tibial  recurrent,  and  the  external  superior  articular  branch  of  the  ])opliteal 
across  the  front  of  the  femur  just  above  the  articular  surface  of  the  knee-joint.  In 
common  with  the  rest  of  the  rete  it  sends  branches  into  the  knee-joint.  It  also 
supplies  branches  to  the  vastus  internus  and  crureus  muscles. 


THE  POPLITEAL  ARTERY 

The  popliteal  artery  (fig.  375)  runs  through  the  popliteal  space  or  ham.  It  is 
a  continuation  of  the  femoral,  and  extends  from  the  aponeurotic  opening  in  the 
adductor  magnus  at  the  junction  of  the  middle  with  the  lower  third  of  the  thigh  to 
the  lower  border  of  the  popliteus  muscle,  Avhere  it  terminates  by  dividing  into  the 
posterior  and  anterior  tibial  arteries.  This  division  is  on  a  level  with  the  lower 
border  of  the  tubercle  of  the  tibia.  As  the  artery  passes  through  the  opening  in 
the  adductor  magnus,  it  is  accompanied  by  the  popliteal  vein,  and  at  times  by  the 
branch  of  the  obturator  nerve  to  the  knee-joint.  The  vein  throughout  is  behind 
the  artery,  at  first  lying  a  little  external  to  it,  but  as  the  vessels  pass  through  the 
popliteal  space  the  vein  crosses  obliquely  over  the  artery,  and  at  the  termination 
of  the  artery  lies  a  little  to  its  inner  side.  The  internal  popliteal  nerve  is 
superficial  to  both  artery  and  vein.  As  it  enters  the  space  it  is  well  to  the  outer 
side  of  the  vessels,  but  as  it  descends  it  gradually  approaches  them,  crosses  behind 
them,  and  at  the  lower  part  of  the  space  lies  to  their  inner  side.  The  artery 
in  the  whole  of  its  course  is  deeply  placed  and  covered  by  a  considerable  amount 
of  fat  and  cellular  tissue. 

Relations  (fig.  374). — In  front,  the  artery  lies  successively  on  the  popliteal 
surface  of  the  femur  (from  which  it  is  separated  l^y  a  little  fat  and  sometimes  one 
or  two  small  glands) ;  on  the  posterior  ligament  of  the  knee;  on  the  hinder  edge  of 
the  articular  surface  of  the  head  of  the  tibia;  and  on  the  popliteus  muscle.  From 
the  latter  muscle  it  is  separated  by  the  expansion  from  the  semi-membranosus  which 
covers  the  muscle,  and  is  attached  to  the  oblique  line  on  the  tibia. 

Behind,  the  artery  is  covered,  above  by  the  semi-membranosus;  in  the  centre  of 
the  space  by  the  skin,  superficial  and  deep  fascia;  and  below  by  the  inner  head  of 
the  gastrocnemius.  The  popliteal  vein  is  behind  it  in  the  whole  of  its  course.  The 
internal  popliteal  nerve  crosses  behind  it  ol)li(|uely  from  without  inwards,  about  the 
centre  of  the  space.  As  the  artery  divides  into  the  anterior  and  posterior  tibial, 
it  is  crossed  by  the  aponeurotic  arch  of  the  soleus  which  stretches  between  the 
tibial  and  fi))ular  origins  of  that  muscle. 

To  the  inner  side  are  the  semi-membranosus  above,  and  the  inner  head  of  the 
gastrocnemius  and  the  internal  popliteal  nerve  below. 

To  the  outer  side  are  the  biceps  and  the  internal  popliteal  nerve  above,  and 
the  outer  head  of  the  gastrocnemius  and  the  plantaris  below. 

Principal  variations  in  the  popliteal. — (A)  It  luaj'  divide  higher,  or  more  rarely  lower  than 
usual.  (B)  It  may  divide  into  the  anterior  tibial  and  peroneal.  (C)  The  vein  may  he  deeper 
than  the  artery,  or  separated  irom  it  by  a  .slip  of  the  gastrocnemius. 


BRANCHES  OF  POPLITEAL 


587 


Branches  of  tiik  Popliteal  Artery 

The  branches  of  the  pophteal  may  he  divided  into — (1)  The  cutaneous;  (2)  the 
muscular  or  sural;   (8)  the  articular;  aii(l(4j    tlic  terminal. 


P^iG.  374. — Kelatioxs  of  the  Popliteal  Artery  to  Boxes  and  Muscles,  Left  Side. 


Superior  external  articular  artery  . 

POPLITEAL  NERVE - 

External  lateral  ligament 

Inferior  external  articular  artery  - 

FopliteuB  ' 

Muscular  branch  to  soleus  - 
Soleus  - 
Anterior  tibial  artery 

Peroneus  longus  . 
Peroneal  artery  . 


BRANCH  OF  POSTERIOR  TIBIAL 
NERVE  TO  FLEXOR  LONGUS 
HALLL'CIS 

Flexor  longus  hallucis 


rS'-^ 


SS^        -  Superior  internal  articular  artery 
^rt pr — ^^ —  popliteal  artery 


X 


Posterior  ligament  of  knee 

■  Azygos  articular  artery 
SEMI-MEMBRANOSUS 


ZJ-- Inferior  internal  articular  artery 


Muscular  branch 


■  Tibialis  posticus 
POSTERIOR  TIBIAL  NERVE 


MUSCULAR  BRANCH  OF  POS- 
TERIOR TIBIAL  NERVE  TO 
FLEXOR  LONGUS  DIGITORUM 


Flexor  longus  digitorum 


Cutaneous  branch  of  peroneal  artery 


.  Posterior  tibial  artery 


Tibialis  posticus 


Peroneus  brevis  . 
Continuation  of  peroneal  artery 


Comuiiiiiicatinfj  branch 
Internal  annular  ligament 


Ititprnal  cnlrnn'-ol  cirlfri/ 


(1)  The  cutaneous  branches — very  irrej^ular  in  tlieir  origin,  number,  and  dis- 
tribution— arise  either  from  the  main  trunk  or  from  one  of  the  inferior  muscular 
branches,  pass  downwards  betAveen  the  two  heads  of  tlie  gastrocnemius,  and,  ])er- 


588 


THE  ARTERIES 


forating  the  deep  fascia,  supply  the  skin  and  fascia  of  the  calf.  A  branch,  usually 
of  moderate  size,  accompanies  the  short  or  external  saphenous  vein,  and  is 
sometimes  called  the  posterior  saphenous  artery. 

(2)  The  muscular  or  sural  branches  are  conmionly  divided  into  the  superior 
and  inferior.  They  arise  from  \\w  upper  and  lower  portions  of  the  popliteal 
respectively;  the  former  sup])ly  the  muscles  forming  the  boundaries  of  the  upper 
half  of  the  popliteal  space;  the  latter,  the  muscles  of  the  calf. 

(a)  The  upper  muscular  branches — or  superior  sural,  as  they  are  sometimes 
called — are  distributed  to  the  hamstring  muscles  and  lower  part  of  the  adductor 

Fig.  375. — Side  View  of  the  Right  Popliteal  Artery. 
(From  a  dissection  in  the  Hunteiian  Museum.) 


x#''?^. 


Ffimoral  artery  and  vein 

BRANCHES  OF  THE 
ly'TERSAL  CUTA- 
NEOUS NERVE 


Aponeurotic  covering 
of  Hunter's  canal 


Anaslomotica  magna 
artery 


LONG  SAPHENOUS 
NEE  VE 


Vertical  fibers  of  the 
adductor  magnus      — 

Popliteal  artery — ^-^\ 


Vastus  internus 
Cut  edge  of  fascia  lata 


BRANCH  OF  SAPHE- 
NOUS NERVE  TO 
PATELLAR  PLEX- 
US 


SMALL  SCIATIC 
NERVE 


Adductor  magnus 


Internal  saphenous  vein 


Part  of  semi- 
tendinoBus 


magnus.  They  anastomose  with  the  superior  articular  arteries,  and  with  the  ter- 
mination of  the  i)rofunda.  (6)  The  inferior  muscular  or  sural  branches,  usually 
two  in  numljer  and  of  large  size,  come  oil  from  the  pojditual  just  as  it  jKisses  under 
cover  of  the  inner  head  of  the  gastrocnemius.  They  at  iirst  descend  between  the 
two  heads  of  the  latter  muscle,  one  branch  then  entering  the  outer,  and  one  the 
inner  head.     They  also  supply  branches  to  the  soleus  and  plantaris  muscles. 

(3)  The  articular,  five  in  number,  are  divided  into  two  superior  (internal  and 
external),  two  inferior  (internal  and  external),  and  the  azygos,  or  anterior.  The 
superior  and  inferior  come  off  transversely  in  pairs  from  either  side  of  the  ])opliteal. 


BRANCHES  OF  POPLITEAL 


589 


the  superior  al)ove,  the  inferior  below  tlie  joint,  and,  windinfr  round  the  Irenes  to 
the  front  of  the  knee,  form — hy  anastomosing  witli  eaeli  other  and  with  tlie  anasto- 
motiea  magna,  the  termination  of  the  profunda,  tlic  descending  branch  of  the 
external  circumflex,  and  the  anterior  tibial  recurrent — a  superficial  and  deep 
arterial  rete  (tig.  376).  The  superficial  anastomosis  or  rete  lies  between  the  skin 
and  fascia  round  about  the  patella  (patellar  rete),  which  it  supplies,  the  larger 
branches  entering  it  from  above.  The  deep  anastomosis  or  rete  lies  on  the  surface 
of  the  bones  around  the  articular  surfaces  of  the  femur  and  tibia,  supplying  branches 
to  the  contiguous  bones  and  to  the  joints.  The  azygos  articular  is  a  single  short 
trunk  coming  off  from  the  deep  surface  of  the  popliteal  artery.  It  at  once  passes 
through  the  jiosterior  ligament  into  the  joint. 

(a)  The  superior  external  articular,  the  larger  of  the  two  superior  articular 


Fig.  376. — The  Anastomosis  about  the  Left  Knee-joint.     (Walsham.) 
(Senii-diagraniniatic. ) 


Deep  branch  of  anastomolica  magna 

Superficial  branch  of  anastoniotica 
magna 


Adductor  magnus 


Siipt-rficial  internal  articular  artery 
piercing  tendon  of  adductor 
magnus 


Internal  lateral  ligament 


Inferior  internal  articular  artery 
passing  under  internal  lateral 
ligament 


Posterior  tibial  artery 


Descending  branch  ofezternal 
circumflex  artery 


Superior  external  articular  artery 
passing  through  external  inter- 
muscular septum 


EXTERNAL  CONDYLE 


rj Long  external  lateral  ligament 


Inferior  external  articular  artery 
passing  under  external  lateral 
ligament 


Anterior  tibial  recurrent  artery 


.1  nterior  tibial  artery 


branches,  runs  transversely  outwards  above  the  external  head  of  the  gastrocnemius, 
and,  passing  beneath  the  biceps  and  through  the  external  intermuscular  se])tum  and 
vastus  externus,  enters  the  substance  of  the  crureus,  and  anastomoses,  above  with 
the  descending  l)ranch  of  the  external  circumflex,  l)elow  with  the  inferior  external 
articular,  and  across  the  front  of  the  femur  with  tlie  superior  internal  articular, 
the  anastoniotica  magna,  and  termination  of  the  ])rofunda,  forming  with  them,  as 
already  described,  the  deep  periarticular  rete.  Ikanches  are  given  off  to  the 
patella,  to  the  upper  and  outer  part  of  the  joint,  to  the  bone,  and  to  the  contiguous 
muscles. 

(b)  The  superior  internal  articular  (tig.  874)  runs  transversely  inwards  just 
above  the  inner  head  of  the  gastrocnemius,  beneath  the  semi-membrano'sus.  and, 
after  perforating  the  tendon  of  the  adductor  magnus,  enters  the  substance  of  the 


590  THE  ARTERIES 

vastus  internus,  wliore  it  anastomoses  (fig.  376)  with  the  deep  branch  of  tlie  anas- 
tomotica  magna  and  termination  of  tlie  profunda  alcove,  with  the  inferior  internal 
articular  below,  and  with  the  superior  external  articular  across  the  front  of  the 
femur.  It  supjilies  small  branches  to  the  contiguous  muscles,  to  the  femur,  to  the 
patella,  and  to  the  joint. 

(c)  The  inferior  internal  articular,  the  larger  of  the  two  inferior  articular 
arteries,  passes  o])liquely  downwards  and  inwards  across  the  popliteus,  below  the 
internal  tuberosity  of  the  tibia,  and  beneath  the  internal  lateral  ligament  to  the 
front  and  inner  side  of  the  knee-joint,  where  it  anastomoses  (fig.  376),  above  with 
the  superior  internal  articular  and  the  superficial  l)ranch  of  the  anastomotica  magna, 
and  across  the  front  of  the  tibia  with  the  inferior  external  articular.  It  supplies 
branches  to  the  loAver  and  inner  part  of  the  joint. 

(d)  The  inferior  external  articular  (fig.  376)  passes  outwards  above  the  head 
of  the  fibula,  along  the  tendon  of  the  })0})liteus  muscle,  beneath  the  external  head 
of  the  gastrocnemius,  and  then  under  the  tendon  of  the  biceps,  and  between  the 
long  and  short  external  lateral  ligaments.  Then  winding  to  the  front  of  the  joint, 
it  anastomoses  above  with  the  superior  external  articular,  below  with  the  anterior 
tibial  recurrent,  and  across  the  front  of  the  tibia  with  the  internal  inferior  articular. 
It  also  supplies  branches  to  the  outer  and  lower  part  of  the  joint. 

(e)  The  azygos  articular  arises  from  the  deep  surface  of  the  popliteal  artery, 
and  passes,  with  the  articular  branch  of  the  obturator  nerve,  through  the  posterior 
ligament,  directly  into  the  knee-joint,  where  it  supplies  the  crucial  ligaments,  and 
the  ligamenta  mucosa  and  alaria.  It  anastomoses  Avith  the  intrinsic  branches  of 
the  other  articular  arteries. 

(4)  The  terminal  branches  of  the  popliteal  are  the  posterior  and  anterior  tibial 
arteries.  The  former  appears  to  be  a  direct  continuation  of  the  vessel,  and  passes 
down  the  back  of  the  leg  to  the  inner  ankle,  where,  on  entering  the  sole  of  the  foot, 
it  divides  into  the  internal  and  external  plantar.  The  anterior  tibial  turns  forwards, 
and,  passing  through  the  interosseous  membrane,  descends  along  the  front  of  the 
leg,  and  ends,  under  the  name  of  the  dorsal  artery  of  the  foot,  l:)y  anastomosing, 
through  the  first  interosseous  space,  with  the  external  plantar  artery  in  the  sole. 


THE  POSTERIOR  TIBIAL  ARTERY 

The  posterior  tibial  artery  (fig.  377),  the  larger  of  the  two  branches  into  which 
the  popliteal  divides  at  the  lower  border  of  the  popliteus  muscle,  runs  dow'nwards 
on  the  flexor  aspect  of  the  leg  between  the  superficial  and  deep  muscles  to  the  back 
of  the  inner  ankle,  where,  midway  between  the  tip  of  the  internal  malleolus  and 
OS  calcis,  and  under  cover  of  the  origin  of  the  abductor  hallucis  as  it  arises  from 
the  internal  annular  ligament,  it  divides  into  the  internal  and  external  plantar 
arteries. 

The  artery  is  first  situated  midway  between  the  tibia  and  fibula,  and  is  deeply 
placed  ])encath  the  muscles  of  the  calf.  As  it  passes  downwards  it  inclines  inwards, 
and  at  the  lower  third  of  the  leg  is  superficial,  being  only  covered  by  the  skin  and 
fascias.  At  the  ankle  it  lies  beneath  the  internal  annular  ligament,  and  at  its  bifur- 
cation also  beneath  the  abductor  hallucis.  A  line  drawn  from  the  centre  of  the 
popliteal  space  to  a  spot  midway  between  the  internal  malleolus  and  point  of  the  heel 
will  indicate  its  course. 

Relations. — Anteriorly,  from  above  downwards,  it  lies  successively  on  the 
tibialis  posticus,  the  flexor  longus  digitorum,  tlie  posterior  surface  of  the  til)ia,  and 
the  internal  lateral  ligament  of  tlie  ankle-joint. 

Posteriorly,  it  is  covered  by  the  skin  and  fascia,  the  gastrocnemius  and  soleus, 
and  th(^  deep  or  intermuscular  fascia  of  the  leg,  by  which  it  is  tightly  bound  down 
to  the  underlying  nmscles.  It  is  crossed  by  the  posterior  tibial  nerve  about  an  inch 
and  a  half  below  its  origin  and  after  it  has  given  off  its  peroneal  branch,  the  nerve 
first  being  on  the  inner,  and  for  the  rest  of  its  course  on  the  outer  side  of  the  vessel 
(fig.  374).  It  is  accompanied  by  two  veins,  which  send  numerous  anastomosing 
branches  across  it.  In  the  lower  third  of  the  leg  the  artery  is  superficial,  ])eing 
only  covered  by  the  skin  and  hy  the  sujx'rficial  and  dee])  fascine. 


POSTERIOR    TIBIAL 


591 


At  the  inner  ankle  it  lies  beneath  the  internal  annular  h<:,aiment  and  alxluctor 
halhicis  upcni  the  internal  lateral  lifjament  of  tlie  ankle-joint.  Here  it  has  the 
tibialis  posticus  and  flexor  longus  dijijitoruni  in  front  of  it,  and  the  j)osterior  til)ial 
nerve  and  the  Hexor  longiis  lialliicis  Ix-hind  and  to  its  outer  side. 

At  times  the  posterior  tibial  nerve  divides  higher  than  usual,  when  one  branch 
lies  on  the  inner  side  of  the  artery,  and  the  other  branch  on  the  outer  side. 

The  branches  of  the  posterior  tibial  artery  are: — (1)  The  peroneal;   (2;  the 


Fig.  377.— The  Popliteal,  the 


Posterior  Tibial,  and  the  Peroneal  Artery, 
Right  Side. 


Semi-tendinosuB 
Semi-membranoBus 

Sartorius 

Inferior  internal  articular  artery LiJ 

Gracilis  ___! 

Inner  head  of  gastrocnemius, 
hooked  aside 

Injfriur  sural  artery 


Superior  external  articular  artery 

Biceps 

Superiur  sural  artery 

Popliteal  artery 

Flantaris  muscle 


Inferior  external  articular  artery 

Spot  at  which  anterior  tibial  artery 
passes  to  front  of  leg 


Tibialis  posticus 


Soleus,  turned  back 


Posterior  tibial  artery 


Flexor  longus  digitorum 


Tibialis  posticus 
Flexor  longus  digitorum 

Communicating  artery 


A  nierior  peroneal  arteri/  passing  to  the 
front  between  the  bones 


Feroneus  longus 
Comnninicating  artery 


muscular;  (3)  the  medullary;  (4)  the  cutaneous;  (5j  the  communicating;  (6)  the 
malleolar;  (7)  the  calcanean,  or  internal  calcanean;  and  (8)  the  terminal,  i.e.  the 
external  and  internal  plantar  arteries. 

(1)  The  peroneal  artery  (tigs.  374,  377)  arises  from  the  posterior  tibial  about 
one  inch  below  the  lower  l)order  of  the  popliteus  muscle.  At  first  forming  a  gentle 
curve  with  the  convexity  outwards,  it  ajijn-oaches  the  fibula,  and  continues  its  course 
downwards  close  to  that  bone  as  far  as  the  lower  end  of  the  interosseous  membrane, 


592  THE  ARTERIES 

where  it  gives  off  a  large  branch,  the  anterior  peroneal,  and  then,  passing  over  the 
back  of  the  inferior  tibio-fil)ular  joint,  terminates  by  breaking  up  into  a  network, 
Avhich  is  distributed  over  the  back  of  the  external  malleolus  and  outer  surface  of 
the  calcaneum  (tig.  381).      It  is  accompanied  by  two  vena?  comites. 

Relations. — At  its  upper  part  it  is  deeply  placed  between  the  tibialis  posticus 
and  soleus  muscles,  and  beneath  the  deep  or  intermuscular  fascia.  For  the  rest  of 
its  course  to  the  ankle  it  lies  beneath,  or  sometimes  in  the  substance  of  the  flexor 
longus  hallucis  in  the  angle  between  the  fibula  and  interosseous  membrane.  After 
giving  off  the  anterior  peroneal,  it  is  only  covered,  as  it  lies  behind  the  tibio-fibular 
articulation,  by  the  integuments  and  deep  fascia,  and  in  this  part  of  its  course  is 
sometimes  called  the  posterior  peroneal. 

The  branches  of  the  peroneal  artery  are: — (a)  The  anterior  peroneal;  (6)  the 
muscular;  (c)  the  medullary;  i^d)  the  communicating;  (e)  the  cutaneous;  (/)  the 
external  calcanean;  and  (g)  the  terminal. 

(a)  The  anterior  peroneal  artery  arises  from  the  front  of  the  peroneal  artery 
at  the  lower  part  of  the  interosseous  space,  and,  passing  through  the  interosseous 
membrane,  runs  downwards  over  the  front  of  the  inferior  tibio-fibular  joint,  beneath 
the  peroneus  tertius,  and  supplies  this  muscle  and  the  inferior  tibio-fibular  joint.  It 
anastomoses  with  the  tarsal,  metatarsal,  and  external  malleolar  branches  of  the 
anterior  tibial  artery,  and  with  the  external  plantar  artery  on  the  outer  side  of  the 
foot,  forming  a  plexus  over  the  outer  ankle  (fig.  380). 

(6)  The  muscular  branches  of  the  peroneal  artery  are  distril)uted  to  the  con- 
tiguous muscles,  namely:  the  flexor  longus  hallucis,  the  tibialis  posticus,  the 
peronei,  and  the  soleus. 

(c)  The  medullary  enters  the  nutrient  foramen  of  the  fibula. 

(cZ)  The  communicating  branches  pass  transversely  inwards  in  front  of  the 
tendo  Achillis  to  anastomose  with  the  communicating  branch  of  the  posterior 
tibial.  The  usual  situation  of  this  communication  is  from  one  to  two  inches  above 
the  ankle-joint. 

(e)  The  cutaneous  branches  run  outwards  between  the  flexor  longus  hallucis 
and  soleus  to  supply  the  integuments  on  the  outer  side  of  the  leg. 

(/)  The  external  calcanean  comes  off  from  the  peroneal  below  the  point  at 
which  the  anterior  peroneal  is  given  off,  and  is  distributed  over  the  outer  surface  of 
the  OS  calcis. 

(gr)  The  terminal  branch  or  posterior  peroneal,  the  continuation  of  the 
peroneal  artery,  anastomoses  with  the  other  arteries  distributed  to  the  external 
malleolus  and  heel. 

(2)  The  muscular  branches  of  the  posterior  tibial  artery  are  distributed  to  the 
contiguous  muscles,  namely:  the  tibialis  posticus,  flexor  longus  digitorum,  and 
soleus. 

(3)  The  medullary  artery,  a  vessel  of  large  size,  leaves  the  posterior  tibial  at 
its  upper  part,  pierces  the  tilnalis  posticus,  and  enters  the  medullary  foramen  in 
the  upper  third  of  the  posterior  surface  of  the  tibia.  In  the  interior  of  the  bone 
it  divides  into  two  branches:  an  ascending  or  smaller,  which  runs  upwards  towards 
the  head  of  the  bone;  and  a  descending  or  larger,  Avhich  courses  downwards 
towards  the  lower  end.  It  gives  off  two  or  three  muscular  twigs  to  the  tibialis 
posticus  before  it  enters  the' foramen.  The  medullary  artery  of  the  tibia  is  the 
largest  nutrient  artery  of  bone  in  the  body,  and  is  accompanied  by  a  nerve  given 
off  liy  the  nerve  to  the  popliteus. 

(4)  The  cutaneous  branches  ]»ass  inwards  to  the  integuments  on  the  inner 
side  of  the  leg.  They  run  in  the  cellular  planes  between  the  deep  and  superficial 
muscles,  and  serve  as  useful  guides  to  tlie  vessel  Avhen  ligaturing  the  posterior 
tibial  through  the  lateral  incision. 

(5)  The  communicating  branch  arises  from  the  posterior  tibial  aliout  two 
indies  above  tlie  inner  malleolus,  and,  ])assing  transversely  outwards  across  the 
tibia  beneath  the  flexor  longus  hallucis  and  tendo  Achillis,  anastomoses  with  the 
communicating  branch  of  the  peroneal. 

Frequently  an  inferior  communicating  branch  between  the  posterior  tibial  and 
peroneal  arteries  is  likewise  present  in  the  loose  connective  tissue  beneath  or  behind 
the  tendo  Achillis  (fig.  374). 


EXTERXAL    PLAXTAR  593 

(Gj  The  malleolar  or  internal  malleolar  branches  aro  distributed,  as  the 
name  implietJ,  over  the  internal  nialleolu!?,  anastoniosinj;  witli  tlie  other  arteries 
entering  into  the  retiforni  plexus  of  vessels  over  that  j)ortion  of  bone.  In  their 
eourse  to  tlie  malleolus,  they  run  l)eneath  the  flexor  loiigus  digitorum  and  tibialis 
posticus  muscles. 

(7)  The  calcanean  or  internal  calcanean  branch  is  distributed  to  the  soft 
parts  over  the  inner  side  of  the  calcaneum.  This  branch — or,  as  is  frequently  the 
case,  branches — comes  off  from  the  posterior  tibial  just  before  its  bifurcation,  and 
anastomoses  with  the  internal  malleolar  and  peroneal  arteries  (fig.  379j. 

(8)  The  terminal  branches  are  the  external  and  internal  plantar  arteries. 


THE  EXTERNAL  PLANTAR  ARTERY 

The  external  plantar  artery — the  larger  of  the  two  branches  into  which  the 
posterior  tit>ial  divides  beneath  the  internal  annular  ligament — passes  at  first 
obliquely  forwards  and  outwards  across  the  sole  of  the  foot  to  the  base  of  the  fifth 
metatarsal  bone,  where  it  makes  a  bend  forwards  and  inwards,  and,  sinking  deeply 
into  the  foot,  terminates  at  the  proximal  end  of  the  first  interosseous  space  by 
anastomosing  Avith  the  communicating  branch  of  the  dorsal  artery  of  the  foot.  In 
its  course  to  the  fifth  metatarsal  bone  the  artery  runs  in  a  more  or  less  straight  line 
oblicjuely  across  the  foot;  whilst  its  deep  portion,  extending  from  the  fiftli  metatarsal 
bone  to  the  proximal  end  of  the  first  interosseous  space,  forms  a  slight  curve  with 
tlie  convexity  forwards,  and  is  know^n  as  the  plantar  arch.  The  plantar  arch  is 
comparable  to  the  deep  palmar  arch  formed  by  the  deep  branch  of  the  ulnar 
anastomosing  with  the  radial  through  the  first  interosseous  space.  This  homology 
is  at  times  more  complete  in  that  the  communicating  branch  of  the  dorsalis  pedis, 
the  homologue  of  tlie  radial  in  the  upper  limb,  takes  the  chief  share  in  forming 
the  arch.  The  external  plantar  artery  is  accompanied  by  two  veins.  The  course 
of  the  artery  is  indicated  by  a  line  drawn  across  the  sole  of  the  foot  from  a  point 
midway  between  the  tip  of  the  internal  malleolus  and  the  greater  tuliercle  of  the 
calcaneum  to  the  base  of  the  fifth  metatarsal  bone,  and  thence  forwards  and 
inwards  to  the  posterior  part  of  the  ball  of  the  great  toe. 

Relations. — In  the  first  part  of  its  course  from  the  inner  ankle  to  the  base 
of  the  fifth  metatarsal  bone,  the  artery  is  covered  successively  by  the  abductor 
hallucis  and  the  flexor  brevis  digitorum,  by  which  it  is  separated  from  the  plantar 
fascia,  and  may  be  slightly  overlapped  in  muscular  subjects  by  the  abductor  minimi 
digit!.  As  it  approaches  the  base  of  the  fifth  metatarsal  bone,  it  lies,  as  it  turns 
forwards  and  inwards  before  sinking  into  the  foot,  in  the  interspace  between  the 
riexor  brevis  digitorum  and  the  abductor  minimi  digiti.  and  is  here  only  covered 
by  the  skin  and  superficial  fascia,  and  the  plantar  fascia.  It  lies  upon  the  cal- 
caneum, the  flexor  aceessorius.  and  the  flexor  brevis  minimi  digiti.  It  is  accom- 
jianied  by  the  external  plantar  nerve,  the  smaller  of  the  two  divisions  into  which 
the  posterior  tibial  nerve  divides.  In  this  part  c»f  its  course  it  gives  off  small 
branches  to  the  contiguous  muscles  and  to  the  heel. 

In  the  second  part  of  its  course  the  artery,  which  is  here  known  as  the 
])lantar  arch,  sinks  into  the  sole,  and  is  covered,  in  addition  to  the  skin,  superficial 
fascia,  plantar  fascia,  and  flexor  lirevis  digitorum,  by  the  tendon  of  the  flexor 
longus  digitorum,  the  lumbricales,  branches  of  tlie  internal  plantar  nerve,  and  tin- 
adductor  hallucis.  It  lies  upon  the  proximal  ends  of  the  second,  tliird,  and  fourth 
metatarsal  bones  and  the  cnrresiionding  interosseous  muscles. 

The  branches  of  the  external  plantar  artery  are: — ( 1 )  Mu.scular;  (2)  cal- 
caneal; (3)  cutaneous;  (4 j  anastomotic;  (5)  articular;  (0)  posterior  perforating; 
and  (7)  digital. 

(1)  The  muscular  branches  of  the  external  plantar  are  distributed  to  the 
contiguous  muscles;  in  the  first  part  of  its  course  to  the  flexor  brevis  digitorum, 
and  the  aceessorius;  as  it  makes  its  bend  into  the  sole,  Xo  the  muscles  of  the  little 
toe;  and.  as  it  forms  the  plantar  anh.  to  the  interossei.  flexor  brevis  hallucis,  and 
adductor  hallucis. 

(2)  The  calcanean  are  two  or  three  small  branches  which  are  distrilnited  over 
38 


594 


THE  ARTERIES 


the  inner  surface  of  the  calcaneum,  and  anastomose  with  the  internal   calcanean 
branch  of  the  ])osterior  tibial  artery  (fig.  379). 

(3)  The  cutaneous  pass  between  the  abductor  minimi  digiti  and  tiexor  brevis 
digitorum,  and  through  the  interval  between  the  middle  and  outer  portions  of  the 
plantar  fascia,  to  the  skin. 

(4)  The  anastomotic  turn  over  the  outer  border  of  the  foot,  and  anastomose 
with  the  tarsal  and  metatarsal  l^ranches  of  the  dorsalis  pedis  (fig.  381). 

(5)  The  articular  come  off  from  the  concavity  of  the  arch,  and,  running  back- 
wards and  upwards,  are  distributed  to  the  articulations  of  the  tarsus.     They  are 


Fig.  378. — The  Plaxtae  Arteries,  Left  Foot. 
(From  a  dissection  iu  the  Museum  of  St.  Bartholomew's  Hospital.) 


Eiternal  calcanean  artery 
Cutaneous  branch  of  external  plantar 

Abductor  minimi  digiti 

Anastomotic  branch 
External  plantar  artery 


First  digital  to  outer  side  of 
little  foe 
Ijumbrical  muscle 

Second  digital 

Third  digital 

Fourth  digital 


Anastomosis  about  inter- 
phalangeal  joint 
Dorsal  branch  of  collateral 
digital 


Anastomosis  of  collateral  digital 
arteries  around  matrix  of  nail 
and  pulp  of  toe 


Internal  calcanean  artery 

Cutaneous  branch  of  internal 
plantar 

Plantar  fascia,  out 


Abductor  hallucis 


Internal  plan  la  r  artery 


Flexor  brevis  digitorum 


Branch  of  internal  plantar  to 
digital  arteries  (superjicial 
digital) 

Flexor  brevis  hallucis 


Princeps  hallucis,  or  fifth  plantar 
digital  artery 


Collateral  digital  branch  of  princeps 

hallucis  to  second  toe 
Collateral  di(jitnl  branch  of  princeps 

hallucis  to  inner  side  of  great  toe 
Collateral  digital  branch  of  princeps 
hallucis  to  outer  side  of  great  toe 


homologous  to  the  recurrent  branches  of  the  deep  palmar  arch  in  the  hand,  and, 
like  the  latter,  are  usually  three  in  number. 

(6)  The  posterior  perforating,  also  three  in  number,  ascend  through  the 
proximal  end  of  the  second,  third,  and  fourth  spaces,  between  the  two  heads  of 
the  correspondingly  named  dorsal  interosseous  muscles,  and  communicate  with  the 
proximal  ends  of  the  first,  second,  and  third  interosseous  arteries  (fig.  381). 

(7)  The  digital  or  plantar  digital  arteries  are  usually  four  in  numl)er,  and 
are  distributed  to  the  inner  and  outer  sides  of  the  third,  fourth,  and  fifth  toes, 
and  to  the  outer  side  of  the  second  toe.  They  are  named  first,  second,  third,  and 
fourth  as  they  come  off  from  the  arch  from  without  inwards,  and  not  according  to 


EXTERNA  L   PL  A  XT  A  R 


595 


the  interosseous  space  in  wliich  they  run.  The  first  comes  off  from  the  outermost 
part  of  the  ))lantar  arch,  and  courses  forwards  along  the  outer  side  of  the  little  toe 
(figs.  378,  379,  381),  over  the  fifth  metatarsal  l)one  and  the  abductor  and  flexor 
brevis  minimi  digiti  muscles.  The  second,  third,  and  fourth  digitals  run  forwards 
in  the  centre  of  the  interosseous  spaces  on  the  therein  contained  interosseous 
muscles,  under  cover  of  the  contiguous  lumbrical,  the  short  and  long  flexor 
tendons,  and  the  transversalis  pedis  muscle.  Near  the  cleft  of  the  toes  they 
become  su{)erficial,  and  bif ungate  for  the  supply  of  the  contiguous  sides  of  the  toes: 
the  second  sup{)lying  the  inner  side  of  the  fifth  and  the  outer  side  of  the  fourth  toe; 
the  third  the  inner  side  of  the  fourth  and  the  outer  side  of  the  third  toe;  and  the 
fourth  tlie  inner  side  of  the  third  and  the  outer  side  of  the  second  toe.     The  supply 


Fig.  379. — Right  Plantar  Aktekies  (Deep). 
(From  a  dissection  in  tlie  Hunterian  Museum.) 


Internal  calcanean  br(inclt 
of  posterior  tibial 


Posterior  tibial  arteri/ 


Abductor  hallucis,  cut 


Internal  plantar  arteri/ 


Inner  head  of  flexor 
accesBoriua 


Flexor  longus  haUueis 

External  plantar  artery 

Adductor  hallucis 

Flexor  brevis  hallucis 

Princeps  hallucis  artery 

Plexor  tendons, 
cut  short 

Collateral  dir/ital  branch  of 
princeps  hallucis  to  inner 
side  of  great  toe 


Cutaneous  and  anastomotic 
branches  of  external 

plantar 

Outer  head  of  flexor 
aocessorius 


Abnormal  muscular  slip 

Muscular  branch 

Cutaneous  branch 

Collateral  digital  artery  to 
outer  side  of  little  toe 

Second  digital  artery 
Third  digital  artery 
Fourth  digital  artery 


of  the  inner  side  of  the  second  and  both  sides  of  the  great  toe  is  dtrived  from  the 
dorsalis  pedis  through  its  communicating  branch  to  the  plantar  arch.  The  digital 
arteries,  immediately  before  they  bifurcate,  send  ujnvards  on  to  tlie  dorsum  of  the 
foot  a  communicating  branch  (the  anterior  perforating  artery)  to  the  corresi)onding 
dorsal  interosseous  arteries.  On  tlie  side  of  the  toes  the  digital  arteries — here  some- 
times called  the  collateral  digital  arteries — furnish  numerous  small  branches  to 
the  integuments  and  the  flexor  tendons  and  their  sheaths.  They  anastomose  by 
manv  small  twigs  witli  the  dorsal  interosseous  arteries,  which  also  run  along  the 
sides  of  the  toes,  but  more  towards  the  dorsal  aspect.  Immediately  above  each 
phalangeal  joint  the  collateral  digital  vessels  communicate  by  cross  branches, 
forming  a  rete  for  the  supply  of  the  articular  end  of  the   phalanges  and  the  con- 


596  THE  ARTERIES 

tiguous  joints.  At  the  distal  end  of  the  toes  they  also  freel}'  anastomose  with  each 
other,  forming  a  rete  heneatli  the  pulp  and  around  the  matrix  of  the  nail.  The 
digital  arteries  are  each  accompanied  hy  two  small  veins. 


THE  INTERNAL  PLANTAR  ARTERY 

The  internal  plantar  artery  (figs.  378,  379) — the  smaller  of  the  two  divisions 
into  which  the  posterior  tibial  divides  at  the  inner  ankle — passes  forwards  along  the 
inner  side  of  the  sole  of  the  foot  usually  to  the  first  interosseous  space,  where  it  ends 
by  anastomosing  either  with  the  fifth  plantar  digital  artery  (princeps  hallucis) 
derived  from  the  communicating  branch  of  the  dorsalis  pedis,  or  with  the  branch 
given  off  by  the  fifth  plantar  digital  to  the  inner  side  of  the  great  toe  (figs.  378,  379). 

Relations. — The  artery  is  at  first  under  cover  of  the  abductor  hallucis,  but 
afterwards  lies  in  the  interval  between  that  muscle  and  the  flexor  brevis  digitorum. 
It  is  covered  by  the  skin  and  superficial  fascia,  but  not  by  the  plantar  fascia,  since 
it  lies  between  the  middle  and  inner  portions  of  that  structure. 

The  branches  of  the  internal  plantar  are  small  and  irregular  in  their  origin, 
course,  and  distrilmtion.     The  following  are  described: — 

(1)  The  muscular  branches  supply  the  abductor  hallucis,  and  flexor  brevis 
digitorum. 

(2)  The  cutaneous  branches  supply  the  skin  over  the  course  of  the  vessel. 

(3)  The  articular  sink  deeply  into  the  sole,  and  supply  the  articulations  on 
the  inner  side  of  the  foot,  and  anastomose  with  branches  of  the  external  plantar 
artery. 

(4)  The  anastomotic  run  beneath  the  abductor  hallucis  and  round  the  inner 
side  of  the  foot,  to  anastomose  with  the  internal  tarsal  branch  of  the  dorsalis 
pedis. 

(5)  The  superficial  digital  are  very  small  twigs  which  accompany  the  digital 
branches  of  the  internal  i)lantar  nerves,  and  anastomose  with  the  plantar  digital 
arteries  in  the  first,  second,  and  third  spaces.  At  times  a  twig  from  one  of  these 
branches  joins  the  external  plantar  artery  to  form  a  superficial  plantar  arch. 


THE  ANTERIOR  TIBIAL  ARTERY 

The  anterior  tibial  artery  (fig.  380) — the  smaller  of  the  two  branches  into  which 
the  popliteal  artery  divides  at  the  lower  border  of  the  popliteus  muscle — at  first 
courses  forwards  between  the  two  heads  of  origin  of  the  tibialis  posticus,  and,  after 
passing  between  the  tibia  and  filnila  above  the  upper  part  of  the  interosseous 
membrane,  runs  downwards  on  the  front  and  outer  aspect  of  the  leg,  between  the 
anterior  muscles,  as  far  as  the  front  of  the  ankle-joint  (fig.  380).  Below  this  spot 
it  is  known  as  the  dorsalis  pedis.  The  course  of  the  vessel  is  indicated  by  a  line 
drawn  from  the  front  of  the  head  of  the  fibula  to  a  point  midway  between  the  two 
malleoli. 

The  artery  is  accompanied  by  two  veins  which  conmiunicate  with  each  other  at 
frequent  intervals  across  it.  It  is  also  accompanied  in  the  lower  three-fourths  of  its 
course  by  the  anterior  tibial  nerve.  The  nerve,  which  winds  round  the  head  of  the 
fi])ula,  and  pierces  the  extensor  longus  digitorum,  first  comes  into  contact  with  the 
outer  side  of  the  artery  somewhere  about  the  upper  .third  of  the  leg;  then,  in 
the  middle  third  of  the  leg,  it  gets  a  little  in  front  of  the  artery,  and  in  the  lower 
third  again  lies  to  its  outer  side. 

Relations. — The  artery  at  first  lies  in  the  triangle  formed  by  the  two  heads  of 
the  tibialis  posticus  and  the  popliteus  muscle;  and,  as  it  passes  through  the  hole 
in  the  interosseous  membrane,  it  has  the  tibia  on  one  side  and  the  fibula  on  the 
other.  It  is  separated  from  the  anterior  tibial  nerve  at  its  conmiencement  by  the 
neck  of  the  fibula  and  the  extensor  longus  digitorum.  This  arrangement  is 
homologous  with  that  met  with  in  the  forearm  in  the  case  of  the  posterior  inter- 
osseous artery  and  nerve. 

Posteriorly  in  its  course  down  the  leg  it  lies  in  its  up]>er  two-thirds  upon  the 


ANTERIOR   TIllIAL 


597 


interosseous  membrane,  to  which  it  is  closely  bound  l^y  fi})rous  bands;  and  in  its 
lower  third  upon  the  front  of  the  tibia  and  the  ankle-joint. 


Fig.  380.— The  Anterior  Tibial  Artery,  Dorsal  Artery  of  the   Foot,  axd  Anterior 
Peroneal  Artery,  and  their  Branches,  Left  Side. 


Superior  internal  articular  artery 


Inferior  internal  articular  artery 


Anterior  tibial  recurrent  artery 


Anterior  tibial  artery 


Tibialis  antious  muscle 


AyTERIOR  TIBIAL  NERVE 


Extensor  longus  hallueis 


Internal  malleolar  artery 


Anterior  annular  ligament 

Dorsalis  pedis  artery 

Innermost  tendon  of  extensor 
brevis  digitorum 

Communicating  branch 

Dorsalis  hallueis  artery 


Superior  external  articular  artery 


Inferior  external  articular  artery 


£.zteasor  longus  digitorum 


Extensor  longua  digitorum, 
turned  back 


Feroneus  tertius 


■« Anterior  peroneal  artery 

External  malleolar  artery 

Peroneus  brevis  muscle 

Extensor  brevis  digitorum,  cut 
External  tarsal  branch 
Metatarsal  branch 
-     Dorsal  interosseous  artery 


To  its  inner  side  along  its  upper  two-thirds  is  the  tibialis  anticus  muscle;  Itiit 
at  the  lowtn-  third  it  is  crossed  by  the  tendon  of  the  extensor  jiroprius  hallueis,  and 
then  for  the  rest  of  its  course  has  this  tendon  overlapping  it  or  to  its  inner  side. 


598  THE  ARTERIES 

On  its  outer  side  it  is  in  contact  in  its  upper  third  with  the  extensor  longus 
digitorum  muscle;  in  its  middle  third  with  the  extensor  proprius  hallucis;  but,  as 
this  nmscle  crosses  to  the  inner  side  of  the  artery,  the  vessel  usually  for  a  very  short 
part  of  its  course  comes  again  into  contact  with  the  extensor  longus  digitorum.  At 
the  upper  and  lower  thirds  of  its  course  on  the  front  of  the  leg  the  artery  has  the 
anterior  tibial  nerve  to  its  outer  side. 

In  front  the  artery  is  covered  by  the  skin,  superficial  and  deep  fascia.  In  its 
upper  two-thirds  it  is  deeply  placed  in  the  cellular  interval  between  the  tibialis 
anticus  on  the  inner  side,  and  the  extensor  longus  digitorum  and  extensor  proprius 
hallucis  on  its  outer  side;  and  in  its  lower  third  it  is  crossed  from  without  inwards 
by  the  tendon  of  the  extensor  proprius  hallucis,  and  lies  beneath  the  anterior 
annular  ligament  of  the  ankle-joint.  The  anterior  tibial  nerve  is  usually  in  front 
of  the  artery  in  the  middle  third  of  the  leg. 

The  branches  of  the  anterior  tibial  artery  are: — (1)  The  posterior  tibial 
recurrent;  (2)  the  superior  fibular;  (3 )  the  anterior  tibial  recurrent;  (4)  the  mus- 
cular;  (5)  the  internal  malleolar;  and  (6)  the  external  malleolar. 

(1)  The  posterior  tibial  recurrent  is  occasionally  absent.  It  ascends  between 
the  popliteus  muscle  and  the  posterior  ligament  of  the  knee-joint  supplying  these 
structures  and  the  superior  tibio-fibular  joint.  It  anastomoses  with  the  inferior 
external  articular  branch  of  the  popliteal,  and,  to  a  less  extent  with  the  inferior 
internal  articular  branch. 

(2)  The  superior  fibular  is  a  branch  of  small  size  which  arises  from  the  main 
trunk  just  before  it  passes  through  the  interosseous  space.  It  winds  round  the 
neck  of  the  fibula,  pierces  the  attachment  of  the  soleus  and  is  distributed  to  that 
muscle  and  to  the  skin. 

(3)  The  anterior  tibial  recurrent  is  given  off  from  the  anterior  tibial  artery 
immediately  after  that  vessel  has  passed  through  the  interosseous  membrane.  It 
winds  tortuously  through  the  substance  of  the  tibialis  anticus  muscle,  over  the 
outer  tuberosity  of  the  tibia  close  to  the  bone;  and,  perforating  the  deep  fascia, 
ramifies  on  the  lower  and  outer  part  of  the  capsule  of  the  knee-joint.  It  anas- 
tomoses with  the  inferior  and  superior  external  articular  branches  of  the  popliteal, 
with  the  descending  branch  of  the  external  circumflex,  and  somewhat  less  freely 
with  the  internal  articular  branches  of  the  popliteal  and  with  the  anastomotica 
magna.  It  gives  off  small  branches  to  the  tibialis  anticus,  the  extensor  longus 
digitorum,  the  knee-joint,  and  the  contiguous  fascia  and  skin.  It  forms  one  of  the 
collateral  channels  by  which  the  blood  is  carried  to  the  limb  below  in  obstruc- 
tion of  the  popliteal  artery  (tig.  376). 

(4)  The  muscular  branches,  some  ten  or  twelve  in  number,  arise  irregularly 
from  either  side  of  the  artery  as  it  courses  down  the  limb,  and  supply  the  con- 
tiguous muscles. 

(5)  The  internal  malleolar,  the  smaller  of  the  two  malleolar  branches,  arises 
from  the  loAver  part  of  the  anterior  tibial  artery  a  little  higher  than  the  external, 
usually  about  the  spot  where  the  tendon  of  the  extensor  longus  hallucis  crosses  the 
anterior  tibial  artery.  It  winds  inwards  over  the  internal  malleolus,  passing 
beneath  the  tibialis  anticus,  and  forms  an  internal  malleolar  plexus  or  rete  about 
the  inner  ankle  over  the  loAver  end  of  the  tibia  by  anastomosing  with  branches  from 
the  posterior  tibial,  internal  plantar,  and  internal  calcanean  arteries. 

(6)  The  external  malleolar,  larger  than  the  internal,  arises  from  the  outer 
side  of  the  anterior  tibial  artery,  usually  on  a  lower  level  than  the  internal 
malleolar.  It  winds  in  an  outward  and  downward  direction  round  the  external 
malleolus,  passing  beneath  the  extensor  longus  digitorum  and  peroneus  tertius.  and 
forms  the  external  malleolar  plexus  or  rete  l>v  anastomosing  with  the  anterior 
peroneal,  the  termination  of  the  peroneal,  the  external  plantar,  and  the  external 
tarsal  branch  of  the  dorsalis  pedis  (fig.  381). 

The  anastomosis  between  the  external  malleolar  and  anterior  peroneal  is  some- 
times of  considerable  size,  supplying  the  blood  to  the  dorsal  artery  of  the  foot:  the 
anterior  tibial,  then  much  reduced  in  size,  usually  ends  at  the  spot  where  the 
external  malleolar  is  usually  given  off. 


ARTERIES   OF  RIGHT  FOOT 


599 


Fifi.    381.— SCHEMK   OF   THE   DlSTKIBl  TIO.V    AND   ANASTOMOSES   OF   THE   AKTEKIES   OF   THE 

Ki(iHT  Foot.     (Walsham.) 
(The  plantar  arteries  are  shown  in  dotted  outline  ;  the  dorsal  in  solid  red.) 


Peroneal  artery 


A  nierior  peroneal  branch 
External  malleolar  branch ' ''  ' ' 


Posterior  peroneal  artery 

Dorsalis  pedis  artery 
Kxlernal  plantar  artery 


External  tarsal  branch 


External  plantar  artery 
forming  plantar  arch 
I'osterior perforating  branches 

First  digital  artery  to  outer 
side  of  little  toe 


Second,  third,  and  fourth 
dorsal  interosseous  arteries 
given   off  from   metatarsal 
artery 

Srrond,  third,  and  fourth 
digital  arteries 


A  nierior  perforating  branches 


Branch  of  third  dorsal 
interosseous  artery  to 
outer  side  of  little  toe 


Anterior  tibial  artery 


Internal  malleolar 
branch 


Malleolar  branch  of 
jiuslerior  tibial  artery 

(  ommunicating  branch 
he lueen posterior  tibial 
and  peroneal  arteries 


Internal  plantar  artery 


Internal  tarsal  branch 


Metatarsal  branch 


—  Communicating  artery 


Dorsalis  hallucis  or 
first  dorsal  inter- 
osseous 

Princeps  hallucis  or 
fifth  plantar  digital 
artery 


Dorsal  digital  branch 
of  dorsalis  hallucis 
to  inner  side  of 
great  toe 


600  THE  ARTERIES 


THE  DORSALIS   PEDIS  ARTERY 

The  dorsalis  pedis  artery  is  a  continuation  of  the  anterior  tihiah  It  extends 
from  the  front  of  the  ankh^-joint  to  the  })roximal  end  of  the  first  interosseous 
space  where  it  dips  into  the  sole  to  join  the  external  ]jlantar  artery  and  comj^lete 
the  plantar  arch.  The  course  of  the  artery  is  indicated  hy  a  line  drawn  from  a 
point  midway  between  the  two  malleoli  to  the  proximal  end  of  tlie  first  metatarsal 
space. 

Relations.— Behind,  the  artery  from  above  downwards  lies  successively  on 
the  astragalus,  scaphoid,  middle  cuneiform,  and  the  base  of  the  second  metatarsal 
l)ones,  and  the  ligaments  uniting  these  bones.  As  it  sinks  into  the  sole,  under  the 
name  of  the  connnunicating  artery,  it  lies  between  the  two  heads  of  origin  of  the 
first  dorsal  interosseous  muscle.  At  times  it  takes  a  course  a  little  more  outwards, 
then  lying  either  partly  on  the  middle  cuneiform  bone,  or  on  the  dorsal  ligaments 
uniting  the  middle  cuneiform  to  the  internal  cuneiform.  It  is  more  or  less  bound 
down  to  the  l:)ones  by  aponeurotic  fibres  derived  from  the  deep  fascia. 

In  front,  the  artery  is  covered  by  the  anterior  annular  ligament,  sometimes  by 
the  extensor  longus  hallucis,  by  the  skin,  the  superficial  and  deep  fascia,  and,  just 
before  it  sinks  into  the  sole,  by  the  innermost  tendon  of  the  extensor  brevis  digi- 
torum.  The  angle  formed  by  this  tendon  with  the  extensor  longus  hallucis  is  the 
best  guide  to  finding  the  artery  in. the  process  of  ligature  (fig.  380). 

To  its  outer  side  is  the  innermost  tendon  of  the  extensor  longus  digitorum,  and 
lower  down  the  innermost  tendon  of  the  extensor  brevis  digitorum.  The  anterior 
til)ial  nerve  is  also  to  its  outer  side,  as  is  also  the  outermost  of  its  vena?  comites. 

To  its  inner  side  is  the  extensor  longus  hallucis,  except  at  times  for  al)out  half 
an  inch  below,  where  the  innermost  tendon  of  the  extensor  brevis  digitorum,  having 
crossed  the  artery,  may  lie  between  it  and  this  tendon.  The  innermost  of  the  vena* 
comites  is  also  to  the  inner  side.  Branches  lietween  the  venae  comites  at  intervals 
cross  the  vessel. 

The  branches  of  the  dorsalis  pedis  artery  are: — (1)  The  tarsal;  (2)  the  meta- 
tarsal; (3)  the  dorsalis  hallucis;  and  (4)  the  communicating,  or  plantar  digital. 

(1)  The  tarsal  branches  may  l)e  divided  into  (a)  the  external,  and  {h)  the 
internal,  (a)  The  external  tarsal  runs  outwards  over  the  scaphoid  and  cu))oid 
bones,  beneath  the  extensor  brevis  digitorum.  It  supplies  branches  to  that  muscl(\ 
and  to  the  bones  and  the  articulations  between  them,  and  anastomoses  above  with 
the  external  malleolar  and  anterior  peroneal,  below  with  the  metatarsal,  and  extern- 
ally over  the  outer  border  of  the  foot  with  the  anastomotic  branches  of  the  external 
plantar  artery.  (6)  The  internal  tarsal  consists  of  a  few  small  branches  which 
run  over  the  inner  side  of  the  foot,  supplying  the  skin  and  articulations,  and  anas- 
tomose with  the  internal  malleolar. 

(2)  The  metatarsal  artery  ffigs.  380,  381)  runs  outwards  across  the  foot,  in  a 
slight  curve  with  the  convexity  forwards,  over  the  bases  of  the  metatarsal  bones, 
and  beneath  the  extensor  tendons  and  the  extensor  brevis  digitorum.  At  the  out(»r 
border  of  the  foot  it  anastomoses,  above  with  the  external  tarsal,  and  externally 
with  the  anastomotic  l^ranches  of  the  external  ])lantar.  From  the  convexity  of  the 
arch  it  gives  off  three  dorsal  interosseous  arteries,  which  run  forwards  on  the 
dorsal  interosseous  muscles  in  the  centre  of  the  second,  third,  and  fourth  inter- 
osseous spaces  to  the  cleft  of  the  toes,  where  they  bifurcate  for  the  supply  of  the  con- 
tiguous sides  of  the  second  and  third  toes,  the  third  and  fourth  toes,  and  the  fourth 
and  fifth  toes.  The  outermost  of  the  interosseous  branches  gives  off  a  small  vessel 
for  the  supply  of  the  outer  side  of  the  little  toe.  At  the  proximal  end  of  the  second, 
third,  and  fourth  interosseous  spaces  each  artery  receives  a  branch  of  comnnmica- 
tion  from  the  external  plantar  artery  (posterior  perforating),  and  immediately 
before  they  bifurcate  a  second  commvmicating  artery  through  the  distal  end  of  the 
interosseous  space  from  the  corresponding  digital  vessel  (anterior  perforating 
artery). 

The  little  dorsal  digital  vessels,  into  which  the  dorsal  interosseous  arteries 
divide  at  the  cleft  of  the  toes,  run  along  the  side  of  each  toe  towards  the  dorsal 
aspect,  anastomosing  with  each  other  across  the  dorsum  of  the  toes  and  by  frequent 


DORSALIS   PEDIS  601 

branches  with  the  coHateral  (lif!;ital  hranclies  of  the  digital  arteries,  which  also  run 
along  the  sides  of  the  toes,  but  nearer  the  j)lantar  surface.  At  the  end  of  the  toes 
they  anastomose  with  each  other  around  the  (juick  of  the  nail. 

(3)  The  dorsalis  hallucis — or  first  dorsal  interosseous  artery,  as  it  is  some- 
times called — is  the  aiii)ar(iit  continuation  of  the  dorsalis  ])edis.  Like  the  other 
dorsal  interosseous  arteries,  it  passes  forwards,  in  the  centre  of  the  first  interosseous 
space,  on  the  first  dorsal  interosseous  muscle.  At  the  cleft  of  the  toes  it  divides 
into  two  dorsal  digital  branches — the  one  for  the  supply  of  the  outer  side  of  the 
great  toe,  the  other  for  the  inner  side  of  the  second  toe.  Before  its  bifurcation 
the  dorsalis  hallucis  gives  off  a  small  branch,  which  runs  inwards,  under  the 
extensor  longus  hallucis,  for  the  sujiply  of  the  inner  side  of  the  great  toe;  but  this 
branch  is  sometimes  absent.  At  the  front  of  the  s})ace,  immediately  before  its 
bifurcation,  the  dorsalis  hallucis  communicates  with  the  fifth  plantar  digital  artery, 
or  i)rinceps  hallucis,  through  an  anterior  perforating  artery  (fig.  381). 

(4)  The  communicating — first  interosseous  perforating,  or  plantar  digital 
artery,  as  it  is  variously  called — comes  ofif  from  the  dorsalis  pedis  with  the  dorsalis 
hallucis  (into  which  arteries  indeed  the  dorsalis  pedis  may  be  said  to  divide).  At 
the  back  of  the  first  interosseous  space  it  dips  into  the  sole  between  the  two  heads 
of  the  first  dorsal  interosseous  muscle,  and  communicates  with  the  termination  of 
the  external  plantar  artery,  completing  the  plantar  arch,  in  a  manner  similar  to 
that  in  which  the  radial  artery,  passing  through  the  first  dorsal  interosseous  muscle 
in  the  hand,  completes  by  inosculating  with  the  ulnar  the  deep  palmar  arch.  At 
the  spot  wliere  it  joins  the  external  plantar  it  gives  off  the  fifth  plantar  digital 
artery,  or  princeps  hallucis,  which  runs  forAvards  in  the  centre  of  the  first  inter- 
osseous space  to  the  cleft  between  the  first  and  second  toe,  where  it  divides  into 
collateral  Ijranches  for  the  adjacent  side  of  each.  Before  bifurcating,  it  supplies  a 
branch  to  the  inner  side  of  the  great  toe,  and  receives  the  anterior  connnunicating 
arterv  from  the  dorsalis  hallucis. 


THE   VEINS 


nriHE  veins,  like  the  arteries,  are  divided  into  the  pulmonary  and  the  systemic. 
I  The  pulmonary  return  the  aerated  blood  from  the  lungs  to  the  left  side 

of  the  heart,  and  are  the  only  veins  that  contain  arterial  blood.  The  sys- 
temic veins  bring  back  to  the  right  side  of  the  heart  the  impure  venous  blood  from 
the  rest  of  the  body.  All  the  systemic  veins  terminate  ultimately  either  in  the 
superior  or  inferior  vena  cava,  except  the  cardiac  veins,  which  return  the  blood 
from  the  heart's  substance,  and  open  directly  into  the  right  auricle. 

The  veins  from  the  stomach  and  intestines,  the  spleen,  and  the  pancreas, 
before  opening  into  the  inferior  vena  cava,  are  collected  into  a  large  trunk  vein 
called  the  portal  vein,  which  breaks  up,  like  an  artery,  into  capillaries  in  the 
substance  of  the  liver.  From  these  capillaries  the  blood  is  again  collected  by 
the  hepatic  veins,  which  finally  open,  as  two  or  more  large-sized  vessels,  into  the 
inferior  vena  cava. 

The  veins  are  described  under  the  heads  of: — 1.  The  veins  of  the  thorax; 
2.  the  veins  of  the  head  and  neck;  3.  the  veins  of  the  spine;  4.  the  veins  of  the 
abdomen;  5.  the  veins  of  the  upper  extremity;  and  6.  the  veins  of  the  lower 
extremity. 


1.   THE    VEINS   OF  THE   THORAX 

The  veins  of  the  thorax  are:  the  pulmonary,  which  carry  the  blood  from  the 
lung  to  the  left  side  of  the  heart;  and  the  superior  vena  cava  and  its  tributaries, 
which  return  the  venous  blood  from  the  head  and  neck,  the  upper  extremities,  and 
the  walls  of  the  thorax,  to  the  right  side  of  the  heart.  The  inferior  vena  cava, 
which  brings  back  the  blood  from  the  abdomen  and  pelvis  and  lower  extremities, 
is  described  with  the  veins  of  the  abdomen,  in  Avhich  cavity  it  lies  throughout  by 
far  the  greater  part  of  its  course,  somewhat  less  than  half  an  inch  of  its  upper  end 
only  being  situated  in  the  thorax. 

The  pulmonary  veins  are  contained  in  the  middle  mediastinum.  The  superior 
vena  cava  and  the  right  and  k'ft  innominate  veins  course  through  the  superior 
mediastinum.  The  azygos  veins,  the  larger  of  which  opens  into  the  superior  vena 
cava,  lie  on  either  side  of  the  thoracic  vertebra  in  the  posterior  mediastinum.  Tliey 
receive  the  intercostal,  the  bronchial,  and  the  oesophageal  veins. 


THE  PULMONARY  VEINS 

The  pulmonary  veins  (fig.  320)  return  the  aerated  blood  from  the  kmgs  to  the 
heart.  They  are  usually  four  in  number,  two  right  and  two  left.  Occasionally, 
however,  there  are  three  pulmonary  veins  on  the  right  side,  the  result  of  the  vein 

G02 


PULMOXARV—VEXA    CAVA   SUPERIOR— TXXOMIXATE  603 

from  the  middle  lobe  of  the  right  lung  opening  separately  into  the  left  auricle 
instead  of  joining  as  usual  the  upper  of  the  two  right  pulmonary  veins.  The 
relations  of  the  pulmonary  veins  to  the  pulmonary  arteries  and  V^ronchi  in  the 
lungs  are  given  with  the  Anatomy  of  the  Ll'ngs.  At  the  root  of  the  lung  the 
pulmonary  veins  on  both  sides  are  arranged  as  an  upper  and  a  lower  branch,  an 
anterior  descending  branch  of  the  bronchus  passing  between  them.  The  upper 
vein  on  the  right  side  is  larger  than  the  lower,  and  usually  receives  the  vein  from 
the  middle  lobe  of  the  right  lung.  The  lower  vein  on  the  left  side  is  larger  than 
the  upper.  Both  the  upper  and  lower  veins  lie  in  front  of  the  pulmonary  artery 
and  on  a  lower  jjlane,  and  run  almost  horizontally  inwards  and  forwards  to  the 
left  auricle.  As  they  pierce  the  pericardium  they  receive  a  reflexion  from  the 
serous  layer  of  that  membrane.  Their  relations  within  the  pericardium  are  given 
with  the  Anatomy  of  the  Heart.  At  the  root  of  the  lung  their  relations  to  the 
surrounding  structures  are  similar  to  those  of  the  pulmonary  artery  (page  466). 
A  separate  description  is  not  required. 


THE  VENA  CAVA  SUPERIOR 

The  superior  or  descending  vena  cava  (fig.  381a)  carries  to  the  heart  the 
l)lood  returned  from  the  head  and  neck  and  upper  extremities  through  the  right  and 
left  innominate  veins,  and  from  the  walls  of  the  thorax,  either  directly  through  the 
greater  az3'gos  vein,  or  indirectly  through  the  innominate  veins.  It  is  formed 
(fig.  381a)  by  the  confluence  of  the  right  and  left  innominate  veins  at  the  lower 
border  of  the  first  right  costal  cartilage  close  to  the  sternum,  and,  descending 
from  this  spot  in  a  gentle  curve  with  its  convexity  to  the  right  and  in  a  direction 
slightly  backwards  and  outwards  behind  the  sternal  end  of  the  first  and  second 
intercostal  spaces  and  second  costal  cartilage,  terminates  in  the  right  auricle  of  the 
heart  on  a  level  with  the  third  right  costal  cartilage  in  front  and  the  seventh 
thoracic  vertebra  behind.  It  measures  about  three  inches  in  length  (7-8  cm.). 
A  little  more  than  its  lower  half  (4  cm.)  is  contained  within  the  pericardium,  the 
serous  layer  of  that  membrane  being  reflected  obliquely  over  it  immediately  below 
the  spot  where  it  is  joined  by  the  vena  azygos  major,  and  on  a  lower  level  than 
the  reflexion  of  the  pericardium  on  the  aorta.  The  vena  cava  superior  contains 
no  valve. 

Relations. — In  front  (fig.  322),  in  addition  to  the  first  and  second  intercostal 
spaces  and  the  second  costal  cartilage,  it  is  covered  by  the  remains  (jf  the  thymus 
gland,  the  interthoracic  fascia,  and  the  pericardium,  and  is  overlapped  by  the  right 
pleura  and  lung. 

Behind  (fig.  324)  are  the  vena  azygos  major,  the  right  bronchus,  the  right 
pulmonary  artery,  and  the  superior  right  pulmonary  vein;  and  below,  the  fibrous 
layer  of  the  pericardium.  The  serous  layer  is  reflected  over  the  front  and  sides  of 
the  vessel,  but  not  over  its  posterior  part. 

To  the  right  side  are  the  right  lung  and  pleura,  and  the  phrenic  nerve. 

To  the  left  side  are  the  innominate  artery  and  the  first  or  ascending  portion  of 
the  arch  of  the  aorta. 

Tributaries. — In  addition  to  the  right  and  left  innominate  veins  and  the  vena 
azygos  major,  it  receives  small  veins  from  the  mediastinum  and  pericardium. 


THE  INNOMINATE  OR  BRACHIO-CEPHALIC  VEINS 

The  innominate  veins  return  the  blood  from  the  head  and  neck  and  upper 
extremity.  They  are  formed  on  each  side  by  the  confluence  of  the  internal  jugu- 
lar and  subclavian  veins  l^ehind  the  sternal  end  of  the  clavicle.  They  terminate 
at  the  lower  l)order  of  the  first  costal  cartilage  on  the  right  side  by  uniting  to  form 
the  superior  vena  cava.     The  innominate  veins  have  no  valves. 

The  right  innominate  vein  (fig.  382)  measures  about  one  to  one  and  a  half 
inches  in  length  (2-3  cm. ),  and  descends  from  its  origin  behind  the  sternal  end  of  tlie 
clavicle,  very  slightly  forwards  and  inwards,  superficial  to,  and  to  the  right  of,  the 


604 


THE  VEINS 


subclavian  and  innominate  arteries,  t<»  its  junetioii  with  tlie  left  vein   l)fliind  the 
first  costal  cartilas^e  close  to  the  sternum. 

Relations. — In  front  (fig.  327)  are  the  origins  of  the  sterno-hyoid  and  sterno- 
thvroid  muscles,  the  clavicle,  the  first  costal  cartilage,  and  the  remains  of  the 
thymus  gland. 

'  Behind  are  the  pleura  and  lung. 

To  the  right  are  the  right  pleura  and  lung,  and  the  phrenic  nerve. 


Fig.  381a. — The  Vexa  Cava  Superior  and 
;Froni  a  dissectiou  iu  St.  Bartholomew's 


RIGHT  RECrit- 
REXT  LARV.V- 
GEAL  XERVI-: 

Transverse  cervical 
artery 
Right  common  carotid 

artery 
Suprascapular  artery 

Internal  jugular  vein 

PNEUMOGASTRIC 
NERVE 

Subclavian  vein 

Inferior  thyroid  vein 

PHREyiC  NER  VE 

Left  innominate  vein 

Ascending  aorta 

Superior  vena  cava 
RIGHT  BRONCHUS 

Branch  to  superior  lobi 
of  lung 
Upper  branch  of  right 
pulmonary  artery 
Brunch  lo  middle  lobe 

of  lung 
Right  pulmonary  vein 

RIGHT  AURICLE 

Right  coronary  arter 
Lower  branch  of  rig  hi 
pulmonary  artery 
THORACIC  VERTEBRA 

Intercostal  vein 
Intercostal  artery 
Vena  azygos  majot 

Intercostal  vein 
Intercostal  artery 

Intercostal  vein 
Intercostal  arti'ry 


THE   InXOMIXATE   VEIXS. 
Hospital  Museum. ) 


THYROID  BODY 
LEFT  liE(  VRREST 
LARYNGEAL 
NERVE 
PNE I  M  O  G  A  STRIC 

NER  VE 
Left  internal  jugular 

vein 
Lfft  common  carotid 

artery 
Left  subclavian  artery 

Left  subclavian  vein 

TRACHEA 


~   Inferior  thyroid  rein 


PHRENIC  NER  VE 

(hooked  aside) 
RECURRENT 
LARYNGEAL 
NERVE 
PNE  I MOGA  S  TRIC 

NERVE 
DUCTUS  ARTERIOSUS 

Left  pulmonary  artery 


Pulmonary  artery 

Right  pulmonary 
artery 

LEFT  BRONCHUS 

Left  coronary  artery 

Upper  left  pvlmonury 

vein 
RIGHT  VENTRICLE 

( ( 'on U.I  arteriosus ) 
Liiuer  left  pulmonary 

artery 
Lower  left  pulmonary 

vein 
ISOPHAGUS 
(hooked  aside) 


THORACIC  DUCT 
Thoriicic  aiirtn 


To  the  left  (fig.  381a)  are  tlie  riglit  subclavian  artery,  the  innominate  artery, 
the  right  pneuiuogastric  nerve,  and  the  trachea. 

The  left  innominate  vein  {\\\f.  381a)  measures  two  and  a  half  to  three  inches 
in  length  (G-7  cm.),  and  extends  from  its  origin  behind  the  sternal  end  of  the  left 
clavicle  obliquely  across  the  three  main  branches  of  the  arch  of  the  aorta  to  unite 
Avith  the  right  innominate  vein  at  the  lower  border  of  the  cartilage  of  the  first  rib 
close  to  the  sternum  to  form  the  vena  cava  superior.  In  this  course  it  runs  from 
left  to  right  with  an  inclination  downwai'ds  and  slightly  backwards.  A  line  drawn 
obliquely  across  the  upi)erhalf  of  the  manubrium  of  the  sternum,  from  the  sterno- 


IXyOMLXA  TIC  H05 

clavicular  articulation  on  the  left  side  to  the  lower  liorder  of  the  first  costal  carti- 
lage at  its  junction  with  the  sternum  on  the  right  side,  will  indicate  its  course. 
The  left  innominate  vein  is  on  a  level  with  the  top  of  the  sternum  at  hirth. 

Relations. — In  front,  in  addition  to  the  manubrium  of  the  sternum,  it  has  the 
origins  of  the  sterno-liyoid  and  sterno-thyroid  muscles,  and  the  remains  of  the 
thymus  gland,  the  sternal  end  of  the  left  clavicle,  and  the  sterno-clavicular  articu- 
lation (figs.  828,  381a). 

Behind,  are  the  three  chief  arteries  arising  from  the  arch  of  the  aorta,  the 
trachea,  and  the  left  phrenic  and  left  pneumogastric  nerves. 

Below  it  is  the  transverse  portion  of  the  arch  of  tlie  aorta. 

Above  it  are  the  cervical  fascia  and  inferior  thyroid  veins. 

Tributaries. — In  addition  to  the  internal  jugular  and  subclavian  veins,  by  the 
contiuence  of  which  the  innominate  veins  are  formed,  each  vein  receives  on  it^ 
uj)per  aspect  the  vertebral,  the  deep  cervical  and  inferior  thyroid  veins;  and  on  its 
lower  aspect  the  internal  mammary  vein.  The  left  vein,  moreover,  is  joined  by 
the  left  superior  intercostiil,  and  by  the  thymic,  mediastinal,  and  jjericardiac  veins. 
At  the  confluence  of  the  internal  jugular  and  subclavian  veins  on  the  right  side, 
the  right  lymphatic  duct  opens;  on  the  left  side  the  thoracic  duct.  The  vertebral, 
the  deep  cervical,  and  the  inferior  thyroid  veins  are  described  with  the  deep  veins 
of  the  head  and  nock  (])age  628). 

The  internal  mammary  veins  (fig.  344)  are  formed  l)y  the  union  of  the 
vente  comites  of  the  superior  epigastric  and  musculo-phrenic  Itranches  of  the  inter- 
nal mammary  artery.  They  receive  in  their  course  through  the  chest  collateral 
trilnitaries  corresponding  to  the  l>ranches  of  the  internal  manunary  artery.  Just 
l>efore  reaching  the  innominate  vein  they  unite  behind  the  first  interct)Stal  space 
to  form  a  single  trunk  which  opens  into  the  innominate  vein  on  the  inner  side  of 
the  internal  mammary  artery.     They  contain  many  valves. 

The  left  superior  intercostal  vein — or,  more  correctly  speaking,  the  lower  left 
su)ierior  intercostal  vein — longer  than  the  right,  which  is  described  as  a  tributary 
of  the  vena  azygos  major,  receives  the  intercostal  veins  from  the  three  or  four  upper 
left  intercostal  spaces  except  from  the  first  space,  and,  ascending  over  the  arch 
of  the  aorta,  opens  into  the  left  innominate  vein.  It  usually  receives  the  left 
bronchial  vein,  and  communicates  with  the  upper  left  azygos  vein.  (See  Inter- 
costal ^'EIXS.  page  (308. ) 

Thi-  mediastinal,  pericardiac,  and  thymic  veins  are  small  vessels,  correspond- 
ing to  the  arteries  of  those  names  given  off  by  the  internal  mammarv.  They  do 
not,  however,  as  a  rule,  join  the  internal  mammary  vein,  but  unite  into  a  single 
trunk  (figs.  317,  382), which  passes  over  the  transverse  part  of  the  arch  of  the  aorta, 
and  opens  into  the  lower  and  anterior  part  of  the  left  innominate  vein. 

Chief  Variations  in  the  Superior  Vena  Cava  and  Innominate  Veins 

Tlie  variations  in  the  vena  cava  and  innominate  veins  depend  upon  certain  abnormalities  in 
the  development  of  the  frreat  veins  from  the  ducts  of  Cuvier  and  the  primitive  jugular  veins, 
and  can  here  receive  only  a  brief  mention.     They  may  be  classified  as  follows  : — 

(1)  Variations  due  to  the  Persistence  of  the  Left  Duct  <f  Cuvier 

(a)  The  left  subclavian  may  join  the  left  internal  jugular  vein  to  form  a  trunk  which  is  con- 
tinued almost  vertically  downwards  over  the  arch  of  the  aorta  in  front  of  the  root  of  the  left  lung, 
to  open  into  the  coronary  sinus  of  the  heart.  Tliis  variety  is  known  as  the  persi.^tent  left  superior 
vena  cava,  and  is  the  normal  arranL'einerit  of  tlie  great  anterior  veins  in  some  animals.  The  rudi- 
ments of  this  vein  are  found  in  Man  in  the  so-called  ohli(|ue  vein  of  Marshall,  which  stretches 
from  the  cijronary  sinus  through  the  vestigial  fuld  of  the  peric.ndium,  and  is  often  continued  as 
a  fine  fibmus  cord  to  the  su|ierior  intercostal  vein. 

When  the  so-called  left  superior  vena  cava  is  present,  the  upper  left  azygos  vein  (the  remains 
of  the  left  primitive  cardinal  vein)  may  open  into  it  hy  archiiiL'  over  the  rout  of  the  left  luiiir  in 
a  way  similar  to  that  in  which  the  greater  azj'gos  (the  right  primitive  cardinal  vein)  opens  into 
the  superior  vena  cava  over  the  root  of  the  right  lung.  The  normal  left  innominate  vein  may 
be  absent,  or  may  be  quite  small  or  rudimentary,  the  resvilt  of  the  non-development,  or  oidy 
partial  development,  of  a  transverse  l)ranch  (which  becomes  the  left  intii'minate)  when  the  left 
part  of  the  sinus  venosus  and  the  left  duct  of  Cuvier  are  transformed  into  the  coronarj"  .sinus, 
the  oblique  vein  of  Marshall,  and  the  upper  jiortion  of  the  left  suj)erior  intercostal  vein. 


606  THE  VEINS 

(b)  A  vein  may  run  from  the  left  innominate,  or  left  superior  intercostal  vein,  throu^^h  the 
vestigial  fold  of  the  pericardium  to  the  coronary  sinus,  the  left  innominate  vein  being  itself  nor- 
mal. This  abnormality  is  similar  in  kind,  but  minor  in  degree,  to  the  former,  described  under 
(a). 

(2)    Variations  due  to  Persistence  of  the  Left  and  Suppression  of  the  Right  Dad  of  Cuvier 

{a)  The  right  innominate  vein  may  cross  the  arch  of  the  aorta  to  join  a  vertical  left  innom- 
inate vein,  and  thus  form  a  left  superior  vena  cava,  the  normal  right  superior  cava  being 
absent.  The  arrangement  of  the  azj'gos  veins  under  this  condition  n)ay  be  reversed,  there  being 
a  left  vena  azj'gos  major  opening  over  the  root  of  the  left  lung  into  the  left  superior  cava,  and  an 
upper  and  lower  right  azygos  vein  arranged  after  the  manner  of  the  normal  lei't  azygos  veins. 
This  arrangement  of  the  veins  may  occur  independently  of  any  general  transposition  of  the 
viscera. 

(Jb)  There  are  many  other  varieties,  depending  upon  abnormalities  in  the  normal  development 
of  the  great  veins  from  the  Cuvierian  ducts  and  from  the  primitive  jugular  and  cardinal  veins  ; 
but  these  cannot  be  discussed  here. 


THE  AZYGOS  VEINS 

The  azygos  veins  (fig.  382)  are  three  in  number.  They  collect  the  blood 
returned  from  the  eleven  intercostal  spaces  on  the  right  side,  and  from  the  seven 
or  eight  loAver  intercostal  spaces  on  the  left  side.  They  lie  on  each  side  of  the 
front  of  the  bodies  of  the  thoracic  vertebrae,  and  establish  a  communication  between 
the  superior  and  inferior  venae  cavae  through  the  ascending  lumbar  veins. 

The  vena  azygos  major  l^egins  in  the  abdomen,  where  it  may  be  looked  upon 
as  a  continuation  upwards  of  the  ascending  lumbar  vein  (page  633).  It  passes 
through  the  aortic  opening  of  the  diaphragm,  runs  up  through  the  posterior 
mediastinum  on  the  right  side  of  the  front  of  the  bodies  of  the  thoracic  vertebrae  as 
high  as  the  fourth  thoracic  vertebra;  then  curves  forwards  over  the  root  of  the  right 
lung,  and  opens  into  the  superior  vena  cava  immediately  before  the  latter  pierces 
the  pericardium. 

Relations. — (1)  In  the  abdomen,  the  vena  azygos  major  lies  to  the  right  of 
the  aorta  and  thoracic  duct,  under  cover  of  the  right  crus  of  the  diaphragm,  upon 
the  first,  sometimes  upon  the  second,  lumbar  vertebra.  At  this  spot  it  receives 
the  right  subcostal  vein,  and  is  continued  below  into  the  ascending  lumbar  vein; 
or,  if  the  lower  part  of  this  vein  is  small,  it  ma}^  appear  to  begin  in  one  of  the 
lumbar  veins,  or  in  the  vena  cava,  or  Avhere  the  portion  of  the  ascending  lumbar 
vein  which  communicates  with  the  renal  is  enlarged,  in  the  renal  vein.  Tlu'ough 
this  intermediation  of  the  ascending  lumbar  vein,  a  communication  is  established 
between  the  iliac  veins  and  the  vena  azygos.  In  obstruction  of  the  inferior  vena 
cava  much  of  the  blood  from  the  lower  extremities  and  abdominal  wall  is 
returned  by  the  vena  azygos  major  and  its  continuation,  the  ascending  lumbar 
vein,  in  the  abdomen,  to  the  vena  cava  superior.  (See  Ascending  Lumbar 
Vein,  page  633. ) 

(2)  At  the  aortic  opening  the  vena  azygos  major  lies  to  the  right  of  the  aorta 
and  thoracic  duct,  between  the  crura  of  the  diaphragm. 

(3)  In  the  posterior  mediastinum,  as  it  courses  upwards  on  the  right  side  of 
the  bodies  of  the  thoracic  vertebrae,  the  vena  azygos  major  crosses  in  front  of  the 
lower  right  intercostal  arteries,  having  on  its  left  side  the  descending  aorta  and 
thoracic  duct,  in  front  the  root  of  the  right  lung  and  lower  down  the  pleura,  and 
on  its  right  side  the  right  ])leura  and  lung. 

(4)  As  it  curls  over  the  root  of  the  right  lung,  the  veua  azygos  major  is  in 
contact  with  the  right  broiiclius,  the  pneumogastric  nerve  passing  obliquely  be- 
tween them  (fig.  324). 

It  usually  contains  an  imperfect  pair  of  valves  at  the  spot  where  it  turns  for- 
wards from  the  fourth  thoracic  vertebra  to  arch  over  the  root  of  the  lung;  and  still 
more  imperfect  valves  are  found  at  varying  intervals  lower  down  the  vein. 

Tributaries. — (1)  The  vena  azygos  minor;  (2)  the  vena  hemiazygos  accessoria, 
or  one  or  more  of  the  left  intercostal  veins;  (3)  the  lower  end  of  the  lower  superior 
intercostal  vein  of  the  left  side  (sometimes);  (4)  the  lower  right  tcsophageal  veins; 
(a)  a  few  right  mediastinal  veins;  (6)  the  right  broncliial  vein;  (7)  the  lower  right 


AZYGOS 


mi 


superior  intercostal  vein;   (8)  the  nine  lower  right  intercostal  veins;   and  (9;  the 
right  subcostal  vein. 

The  vena  azygos  minor — also  called  the  lower  left  azygos  and  vena  hemi- 
azygos— begins  in  the  abdomen  by  communicating,  like  the  vena  azygos  major, 
with  the  ascending  lumbar  vein  of  the  left  side.     Through  this  vein  it  communi- 

FiG.  ;?82. — The  Superior  and  Ixferior  Ven^  Cavje,  the  Innominate  Veins, 
AND  THE  Azygos  Veins. 


Right  common  carotid 

artery 

Right  internal  jugular 

vein 


RIGHT  LYMPHATIC  DUCT 

Innominiite  artery 

RIGHT  PNEUMO- 

GASTRIC  NER\E 

Right  inncminate  vtin 

Inlernal  mammary  vein 

Trutik  of  the  pericardiac 
a7id  thymic  veins 
Vena  cava  superior 


Vena  azygos  major 


Vena  azygos  minor,  cross- 
ing  spine  to  enter  vena 
azygos  major 


Hepatic  veins 


Vena  cava  inferior 

Right  phrenic  artery 

Cieliac  axis 

Right  middle  suprarenal 
artery 


Right  spermatic  artery   . 
Right  spermatic  vein 


Left  common  carotid 

artery 
LEFT  PNEUMOGAS- 
TRIC  NER  VE 

THORACX  DUCT 

Left  innominate  vein 

Left  subclavian  artery 

Left  superior  intercostal 
vein 

RECCRREXT 
LARYNGEAL 
NER  VE 

Vena  azygos  tertivs 
(ESOPHAGUS 


_  Left  upper  azygos  vein 


(Esophageal  branches 
from  aorta 

Vena  azygos  minor 


THORACIC  DUCT 


Left  phrenic  artery 

Left  middle  suprarenal 
arfery 

RECEPTACULUM  CHYLI 

Superior  mesenteric 
artery 

Left  ascending  lumbar 

vein 
Left  spermatic  vessels 


Inferior  mesenteric 
artery 


cates  with  the  lumbar  veins,  the  renal,  and  the  iliac  veins,  and,  according  as  one  or 
other  portion  of  the  ascending  lumbar  is  enlarged  and  other  portions  are  diminished 
in  size  or  obliterated,  so  may  the  vena  azygf)S  minor  appear  to  begin  in  the  vena 
cava  inferior  or  in  a  lumbar,  the  renal,  or  f)ne  of  the  iliac  veins.  The  vena  azygos 
minor,  after  receiving  the  left  subcostal  vein,  passes  through  the  left  crus  of  the 
diaphragm,  and  courses  up  the  posterior  mediastinum  to  the  left  of  the  bodies  of 


608  THE  VEINS 

the  lower  thoracic  vertebrae  as  high  as  the  eighth,  where  it  turns  obU(}uely  to  the 
right,  and,  crossing  in  front  of  the  spinal  column  behind  the  aorta  and  the  a'sopha- 
gus,  opens  into  the  vena  azygos  major.  In  its  course  it  crosses  over  three  or  four 
of  the  lower  left  intercostal  arteries,  and  is  covered  by  the  pleura. 

Tributaries. — (1)  The  lower  four  left  intercostal  veins;  (2)  the  left  subcostal 
vein;  (o)  the  lower  end  of  the  third  azygos  vein  (sometimes);  (4)  small  left  medi- 
astinal veins;  and  (5)  the  lower  left  oesophageal  veins. 

The  vena  azygos  tertia  (also  called  the  upper  left  azygos  and  vena  hemi- 
azygos accessoriaj  varies  considerably  in  size,  position,  and  arrangement,  and  is 
often  absent.  It  lies  in  the  posterior  mediastinum  by  the  left  side  of  the  bodies  of 
the  fifth,  sixth,  and  seventh  thoracic  vertebrae,  and  is  more  or  less  vertical  in 
direction.  It  is  continued  above  into  the  lower  left  superior  intercostal  vein,  an<l 
below  either  joins  the  vena  azygos  minor,  or  passes  obliquely  across  the  sixth  or 
seventh  thoracic  vertebra  to  join  the  vena  azygos  major.  ^  The  intercostal  veins 
intervening  between  it  and  the  vena  azygos  minor  then  open  directly  across  the 
spine  into  the  vena  azygos  major.  It  crosses  the  corresponding  left  intercostal 
arteries,  and  is  covered  by  the  pleura. 

Tributaries. — (1)  The  fifth,  sixth,  and  sometimes  the  seventh  intercostal 
veins;  (2)  the  lower  end  of  the  lower  left  superior  intercostal  vein;  (3)  the  upper 
end  of  the  vena  azygos  minor  (sometimes);  and  (4)  the  left  bronchial  vein. 

The  intercostal  veins. — The  intercostal  veins  are  eleven  in  number  on  each 
side,  and  correspond  with  the  intercostal  artei'ies.  The  last  thoracic  vein  is  here 
called  the  subcostal,  and  is  described  separately  (page  609).  There  is  one  vein 
to  each  intercostal  artery,  the  vein  lying  above  the  artery  whilst  in  the  intercostal 
space.  Each  vein  is  joined  by  a  dorsal  tributary  which  runs  with  the  dorsal  l)ranch 
of  the  intercostal  artery  between  the  transverse  process  of  the  vertebrae  and  the  neck 
of  the  rib.  The  dorsal  tributaries  return  the  blood  from  the  muscles  of  the  back, 
and  receive  communicating  branches  from  the  dorsal  spinal  plexus  and  from  the 
spinal  veins  through  the  intervertebral  foramina.  The  intercostal  veins  also  receive 
small  tributaries  from  the  bodies  of  the  vertebrae.  The  termination  of  the  inter- 
(;ostal  veins  is  different  on  the  two  sides,  and  is  seldom  alike  in  any  two  consecu- 
tive subjects. 

On  the  right  side. — The  first  intercostal  vein  (the  upper  right  superior 
intercostal  vein)  ascends  with  the  superior  intercostal  artery,  a  branch  of  tlic 
sul)clavian,  to  end  either  in  the  vertebral  vein  just  before  the  latter  joins  the  right 
innominate  vein,  or  in  the  right  innominate  direct.  The  second  intercostal  vein 
either  joins  with  the  first,  and  opens  with  it  as  a  common  trunk  into  the  vertebral 
or  innominate  vein,  or  it  joins  with  the  third  or  with  the  third  and  fourth  to  open 
into  the  vena  azygos  major  as  the  latter  is  arching  over  the  root  of  the  right  lung. 
This  vein  is  known  as  the  lower  right  superior  intercostal  vein.  The  fifth, 
sixth,  seventh,  eighth,  ninth,  tenth,  and  eleventh  right  intercostal  veins  join  the 
vena  azygos  major.  The  vipper  of  these  have  well-marked  valves  Avhere  they  join 
the  azygos  vein.  In  the  lower  veins  these  valves  are  imperfect.  All  the  intercostal 
veins  are  provided  with  valves  in  their  course  between  the  muscles. 

On  the  left  side  the  first  intercostal  vein  also  follows  the  superior  intercostal 
artery  from  the  subclavian,  and  ascends  to  join  the  left  vertebral  or  left  innominate 
vein,  and  is  known  as  the  upper  left  superior  intercostal  vein.  The  second 
intercostal  vein  either  joins  the  first,  and  opens  with  it  as  a  common  trunk  into  the 
left  vertebral  or  left  innominate  vein,  or  joins  the  third  and  fourth,  as  described 
below,  to  form  the  lower  left  superior  intercostal  vein.  The  third  and  fourth, 
and  sometimes  the  second,  intercostal  veins  unite  to  form  a  single  trunk,  the  lower 
left  superior  intercostal  vein,  which  passes  iipwards  across  the  arch  of  the  aorta, 
and  opens  into  the  left  innominate  vein.  This  vein  usually  communicates  at  its 
lower  end  with  the  third  azygos  vein,  but  at  times  crosses  the  spine,  and  enters 
directly  the  vena  azygos  major.  A  fibrous  cord  can  fretjuently  be  traced  from 
it  through  the  vestigial  fold  of  the  pericardium  to  the  oblicjue  vein  of  ISIarshall 
(page  605).  The  fifth  and  sixth,  and  sometimes  tlie  seventh,  intercostal  veins 
cither  end  in  the  third  azygos  vein,  or,  if  this  is  absent,  cross  the  spine,  and  open 
directly  into  the  vena  azygos  major.  The  eighth,  ninth,  tenth,  and  eleventh,  and 
sometimes  the  seventh,  intercostal  veins  join  the  vena  azygos  minor. 


CARDIAC 


609 


Tlie  subcostal  vein,  or  twelfth  thoracic  vein,  lies  beneath  tlie  last  rib,  and 
accompanies  the  twelfth  dorsal  or  subcostal  artery.  It  receives  tributaries  corre- 
sponding to  the  branches  of  the  subcostal  artery,  and  opens  on  the;  right  side  into 
the  vena  azygos  major,  and  on  the  left  side  into  the  vena  azygos  minor. 

The  bronchial  veins  correspond  to  the  bronchial  arteries,  but  do  not  return  the 
wliolc  of 'the  blood  carried  to  the  lungs  l)y  those  vessels — that  part  which  is  distri- 
buted to  the  smaller  bronchial  tubes  and  the  alveolae  being  brought  back  by  thi' 
pulmonary  veins.  The  bronchial  veins  issue  from  the  lung  substance  behind  the 
structures  forming  the  root  of  the  lung.  The  right  vein  generally  joins  the  vena 
azygos  major  just  before  the  latter  vein  enters  the  superior  vena  cava.  The  left 
vein  opens  into  the  lower  left  superior  intercostal  vein,  or  into  the  upper  left  azygos 
vein.  The  bronchial  veins  at  the  root  of  the  lung  receive  small  trilnitaries  from  the 
bronchial  glands,  from  the  trachea,  and  from  the  posterior  mediastinum. 

The  oesophageal  veins  from  the  thoracic  portion  of  the  oesophagus  end  in  part 
in  the  vena  azygos  major,  and  in  part  in  the  vena  azygos  minor. 


THE  VEINS  OF  THE  HEART 

The  cardiac  or  coronary  veins  return  the  blood  from  the  substance  of  the 
heart.  They  accompany  the  corresponding  coronary  arteries, and  terminate  for  the 
most  part  in  a  dilated  vein  known  as  the  coronary  sinus.     This  opens  directly  into 


Fig.  383. — The  Coronaky  Sintts. 


Left  carotid  artery 
Left  subclavian  artery 

Aorta 
Ductus  arteriosus 

Pulmonary  artery 

Left  pulmonary  veins 

LEFT  AURICLE 

Left  coronary  artery 

Left  marginal  artery 

Oblique  vein  of  Marshall 

Left  marginal  vein 

PERICARDIUM 

Coronary  sinus 

Posterior  cardiac  vein 


A  nterior  interventricular 
branch  of  left  coronary 


Hight  carotid  artery 


Innominate  artery 


Vena  cava  superior 
Right  pulmonary  veins 

KIGHT  AURICLE 


—     Vena  cava  inferior 


Hight  coronary  artery 
Posterior  interventricular  vein 


Posterior  interventricular  branch 
of  right  coronary 


the  right  auricle  of  the  heart,  V)etween  the  tricuspid  opening  and  the  opening  of  the 
inferior  vena  cava.     Some  smaller  veins  from  the  heart's  substance  (vena?  minima^ 
cordis)  open  separately  and  directly  into  the  right  auricle  at  the  bottom  of  some  of 
the  small  depressions  "known  as  the  foramina  Thebesii. 
39 


610 


THE  VEIXS 


The  coronary  sinus  is  situated  at  the  hack  of  the  heart,  in  tlie  groove  lietween 
the  left  auricle  and  left  ventricle.  It  measures  about  an  inch  in  length.  Its 
opening  into  the  auricle  is  guarded  by  the  so-called  Thebesian  or  coronary  valve. 
It  receives  the  following  tributaries:  (1)  The  great  coronary  or  cardiac  vein,  of 
which  it  appears  to  be  the  large  and  dilated  end;  (2)  the  posterior  cardiac  or  pos- 
terior interventricular  vein;  (3)  the  right  auricular  vein;  and  (4)  the  oblique  vein. 

(1)  The  great  coronary  or  cardiac  vein  is  formed  by  the  union  of  (a)  the 
anterior  interventricular  vein,  which  runs  upwards  from  the  apex  of  the  heart, 
in  the  groove  between  the  right  and  left  ventricles,  in  comi)any  with  the  artery  of 
that  name;  with  (h)  the  left  auricular  vein,  which  returns  the  blood  from  the  left 
auricle.  The  vein  thus  formed  then  runs  round  the  left  side  of  the  heart,  in  the 
groove  between  the  left  auricle  and  left  ventricle,  and  terminates  in  the  coronary 
sinus  at  the  spot  where  the  latter  is  joined  by  the  oblique  vein.  Its  entrance  into 
the  sinus  is  guarded  by  a  double  valve.  It  receives  (c)  the  left  marginal  vein  or 
veins,  and  branches  from  both  ventricles,  especially  the  left. 

The  left  marginal  vein  runs  with  the  artery  of  that  name  over  the  surface  of 


Fig.  384. — Scheme  of  the  Coronary  Veins.     (Walsham.) 

Right  pulmonary  veins ! I        >        /         1 Superior  vena  cava 


Left  pulmonary  veins 
Inferior  vena  cava 

Oblique  vein 

Great  coronary  or 
cardiac  vein 

Left  marginal  vein 


Anterior  inlerien- 
Iricular  vein 

Preventricvlnr  or 
anterior  cardiac 
vein 

night  auricular  vein 

Coronary  ^inus 


Posterior  or  middle 
cardiac  or  posterior 
interventricular  vein 

Right  marginal  vein 


the  left  ventricle,  along  the  left  margin  of  the  heart.      It  receives  tributaries  from 
the  left  ventricle,  and  terminates  in  the  great  coronary  vein. 

(2)  The  posterior  cardiac,  middle  cardiac,  or  posterior  interventricular 
vein  accompanies  the  posterior  interventricular  artery  upwards,  from  the  apex  of 
the  heart  in  the  posterior  interventricular  groove.  It  ends  in  the  coronary  sinus, 
just  before  the  termination  of  the  latter  in  the  right  auricle.  It  receives  tributaries 
from  the  posterior  surface  of  both  ventricles,  and  is  guarded  by  a  valve  where  it 
joins  the  coronary  sinus.  Two  or  three  small  veins  (posterior "cardiac,  or  smaller 
posterior  cardiac)  run  upwards  from  the  back  of  the  left  ventricle,  and  open  into 
the  coronary  sinus  by  sejiarate  orifices  guarded  by  valves. 

(3)  The  right  auricular,  right  coronary,  or  small  coronary  vein,  runs  in  the 
right  auriculo-ventricular  groove,  and  terminates  in  the  coronary  sinus  just  before 
the  entrance  of  that  sinus  into  the  auricle.  It  is  joined  by  "the  riglit  marginal 
vein  and  by  the  preventricular  or  smaller  anterior  cardiac  vein  or  veins. 

(4)  The  oblique  vein — the  greater  ])art  of  which  is  often  represented  merely  by 
a  delicate  til)r(nis  cord — runs  across  the  l)ack  2)art  of  the  left  auricle,  in  the  vestigial 
fold  of  the  pericardium  to  tlie  coronary  sinus.      This  vein,  with  the  coronary  sinus, 


VEINS   OF   THE  HEAD   AND   NECK  611 

its  dilated  portion,  re})reseiits  what  was  the  left  duct  of  Cuvicr  and  part  of  the 
sinus  venosus  in  thctVetus.  As  stated  at  pat^c  GOo,  it  is  occasionally  found  jjcrvious, 
and  may  be  greatly  enlarged,  and  help  to  form  the  so-called  left  superior  vena  cava. 
There  is,  as  might  l)e  gathered  from  the  consideration  of  its  morphology,  no  valve 
"where  the  ol>li(iue  vein  is  continued  into  the  coronary  sinus. 

The  right  marginal  vein— sometimes  called  the  anterior  cardiac  vein,  or  vein 
of  Galen — runs  over  the  right  ventricle,  along  the  right  margin  of  the  heart,  and 
opens  either  into  the  right  auricular  vein  or  separately  into  the  lower  part  of  the 
right  auricle,  its  orifice,  known  as  the  foramen  of  Galen,  being  situated  immediately 
below  the  opening  of  the  superior  vena  cava.  Other  small  veins — the  smaller 
anterior  cardiac  veins  (venae  cordis  parvae,  or  preventricular  veins; — also 
track  U})  from  the  anterior  surface  (if  the  right  ventricle,  and  o})en  either  into  the 
riglit  marginal  vein  or  separately  into  tlie  right  auricle. 


2.  THE  VEINS  OF  THE  HEAD  AND  NECK 

The  veins  of  the  head  and  neck  may  be  divided  for  purposes  of  description 
into  the  superficial,  which  return  th*e  blood  from  the  external  parts  of  the  head 
and  neck;  and  into  the  deep,  which  return  the  blood  from  the  deeper  structures. 
The  superficial  may  be  again  subdivided,  according  to  the  region  from  which  they 
carry  the  blood,  into  (1)  The  veins  of  the  scalp  and  face;  and  (2)  the  veins  of  the 
neck.  The  deep  veins — into  which,  moreover,  some  of  the  superficial  open — may 
be  subdivided  into; — (1)  The  veins  of  the  diploe;  (2)  the  venous  sinuses;  (3)  the 
veins  of  the  brain;  (4)  the  veins  of  the  nasal  cavities;  (5)  the  veins  of  the  ear; 
(6)  the  veins  of  the  orbit;  (7)  the  veins  of  the  pharynx  and  larynx;  and  (8)  the 
deep  veins  of  the  neck.  All  the  veins,  whether  superficial  or  deep,  sooner  or  later 
termiriate  in  the  internal  jugular,  the  external  jugular,  the  vertebral,  or  the  deep 
cervical  vein — chiefly  the  two  former;  and  these  veins  open  directly  or  indirectly 
into  the  innominate  veins  at  the  root  of  the  neck,  through  which  all  the  blood  from 
the  head  and  neck  ultimately  passes  on  its  way  to  the  heart.  The  external  jugular 
vein  is  quite  superficial;  it  is  formed  by  the  confluence  of  the  veins  corresponding 
to  the  upper  branches  of  the  external  carotid  artery,  and,  after  receiving  tributaries 
from  the  superficial  parts  of  the  neck  and  from  the  shoulder,  terminates  just  above 
the  clavicle  in  the  subclavian  vein.  The  internal  jugular  vein  is  deeply  placed  liy 
the  side  of  the  common  and  internal  carotid  arteries.  It  begins  in  the  jugular 
fossa,  where  it  is  continuous  wdth  the  lateral  sinus,  and,  after  receiving  tributaries 
corresponding  to  the  low'er  })ranches  of  the  external  carotid  artery,  terminates  at 
the  root  of  the  neck  in  the  innominate  vein.  The  vertebral  vein  accomi)anies  the 
vertelrral  artery  through  the  foramina  in  the  transverse  processes  of  the  cervical 
vertebrie.  It  begins  in  the  suboccipital  triangle  by  the  confluence  of  small  veins 
from  the  deep  muscles  at  the  ])ack  of  the  occiput,  and,  after  receiving  tributaries 
from  the  cervical  spine  and  deep  muscles  of  the  neck,  ends  in  the  innominate 
vein.  The  deep  cervical  receives  the  occii)ital  vein,  courses  downwards  amongst  the 
deep  muscles  at  the  Imck  of  the  neck,  and  ends   in  the   iminminate  vein. 


THE  SUPERFICIAL   VEINS  OF  THE  HEAD  AND  NECK 

1.  THE  SUPERFICIAL  VEINS  OF  THE  SCALP  AND  FACE 

The  blood  from  the  scalp  is  returne(l  by  three  main  channels — viz.  an  anterior, 
which  passes  over  the  forehead  and  face;  a  posterior,  which  descends  over  the 
occipital  l)one;  and  a  lateral,  formed  ])y  the  confluence  of  two  smaller  veins  which 
descend  over  the  parietal  and  temporal  bones  respectively — one  in  front,  and  one 
behind  the  ear. 


612 


THE  VEINS 


The  Anterior  Superficial  Vein  of  the  Scalp  and  Face 

The  anterior  vein  descends  near  the  middle  line,  over  the  frontal  bone,  to 
the  inner  angle  of  the  orbit;  continues  its  course  by  the  side  of  the  nose  to  the 
cheek,  which  it  crosses  obliquely,  to  the  anterior  edge  of  the  masseter  muscle,  and 
thence  passes  through  the  digastric  triangle  to  the  upper  border  of  the  hyoid  bone, 
where  it  terminates  in  the  internal  jugular  vein.  In  this  course  it  is  reinforced 
by  numerous  collateral  veins,  and  gradually  increases  in  size.  It  has,  moreover, 
numerous  connnunications  with  the  deep  veins. 


Fig.  385.- 


-The  Superficial  Veins  and  Lymphatics  of  the  Scalp,  Face,  and  Neck. 

(Walshaiu.) 


Frontal  vein 


SiipraorhilaJ  vein 
Coinmunicatiiin  uil/i 
ophthalmic  rein 
Transverse  nasal  vein 


Angular  vein 
Lateral  nasal  veinx 

Transverse  facial 

vein 
Superior  labial  or 

coronary  vein 

A  n  terior  pterygoid 

or  deep  facial  vein 

Inferior  coronary 

vein 

Facial  vein 

Inferior  labial  vein 

Submental  vein 
lAngual  vein 

Superior  thyroid 

vein 

Middle  thyroid 
vein 

Sterno-mastoid 

Anterior  jtigular 
vein 
Communication 
between  anterior 
jugular  veins 

Platysma 


Anterior  temporal  vein 

Posterior  temporal  vein 

Deep  temporal  vein 
Parotid  lymphatic  glands 
Common  temporal  vein 
Internal  maxillary  vein 
Occipital  vein 
-  Temporo-maxillary  vein 
Posterior  auricular  vein 

,     Occipital  lymphatic  glands 

y     'Sterno-mastoid  lymphatic 

glands 

Conimnnication  betireen 

facial    and    external 

jugular  veins 

Submaxillary  lymphatic 

glands 
Internal  jugular  vein 
Posterior  external  Jtigular 

vein 
External  jugular  vein 


Superficial  cervical  chain 
of  glands 


-   Transverse 

cervical  vein 

Suprascapular 


Jugulo-cephalic 
vein 


This  long  continuous  trunk  vein  is  variously  named  according  to  the  region  in 
which  it  lies.  Thus,  as  it  descends  over  the  frontal  bone  it  is  known  as  the  frontal 
vein  ;  as  it  lies  by  the  side  of  the  nose  it  is  called  the  angular  vein  ;  whilst  in  the 
remainder  of  its  course  over  the  face  and  neck  it  is  spoken  of  as  the  facial  vein. 

CI)  The  frontal  vein  begins  about  the  level  of  the  coronal  suture  in  a  venous 
plexus  which  communicates  with  the  anterior  division  of  the  tem})oral  vein.  Soon 
forming  a  single  trunk,  it  passes  vertically  downwards  over  the  frontal  l)one,  a  short 
distance  from  the  middle  line  and  parallel  to  its  fellow  of  the  op])Osite  side,  to  the 
inner  can  thus  of  the  eyelids,  where  it  takes  the  name  of  the  angular  vein  (fig.  385). 

Tributaries. — In  its  course  it  receives  numerous  tributaries  from  the  forehead, 


VELXS  OF  THP:  scalp  AXD   face  613 

and  coiumunicates  freely  with  the  vein  of  the  opposite  side,  across  the  o;lal)ella  or 
root  of  the  nose,  by  a  transverse  branch  sometimes  called  the  transverse  nasal 
vein.  Just  V)efore  its  termination  it  receives  tlie  supraorl)ital  vein.  'J'hc  ti-ansverst^ 
nasal  vein  usually  receives  the  dorsal  veins  of  the  nose. 

The  supraorbital  vein  l^egins  over  the  frontal  eminences  l)y  intercommunica- 
tions with  the  anterior  l)ranch  of  the  superficial  temporal  vein.  It  receives  tribu- 
taries from  the  forehead  and  eyebrow,  and,  running  oliliquely  downwards  and 
inwards,  oi)ens  into  the  termination  of  the  frontal  vein.  It  conmiunicates  with 
the  ophthalmic  vein,  and  receives  the  frontal  vein  of  the  diploe  as  the  latter  vein 
issues  from  the  bone  at  the  liottom  of  the  supraorbital  notch. 

(2)  The  angular  vein,  the  continuation  of  the  frontal  vein  downwards,  extends 
from  the  juncti(jn  of  the  frontal  and  supraorl)ital  veins  a  little  below  the  level  of 
the  eyebrow,  to  the  level  of  the  lower  margin  of  the  orV)it,  where  it  becomes  the 
facial  vein.  In  this  short  course  it  skirts  round  theinner  margin  of  the  orbit,  lying 
with  the  angular  artery  on  the  nasal  process  of  the  superior  maxillary  bone  a  little 
internal  to  the  lachrymal  sac.  Branches  pass  from  the  posterior  part  of  the  angular 
vein  into  the  orbit  to  join  the  ophthalmic. 

The  angular,  the  facial,  and  the  ophthalmic  veins  contain  no  valves.  The 
blood,  therefore,  can  pass  either  forward  from  the  ophthalmic  into  the  angular,  or 
backwards  through  the  facial  and  angular  into  the  ophthalmic,  and  so  on  to  the 
cavernous  and  other  venous  sinuses  of  the  cranium.  Hence  in  certain  tumours  in 
the  orbit  and  ci'anium,  the  congestion  of  the  angular  and  facial  veins;  and  the 
danger  in  facial  car]:)uncle  and  anthrax  of  septic  thrombi  spreading  Imckwards 
through  tlic  angular  and  o})hthalmic  veins  to  the  cranial  sinuses. 

Tributaries. — (a)  The  superior  lateral  nasal;  and  (6)  the  palpebral  veins. 

(a)  The  superior  lateral  nasal  veins  ascend  from  the  ala  and  the  side  of  the 
nose  to  join  the  inner  side  of  the  angular  vein  (fig.  885). 

(b)  The  palpebral  veins  proceed  from  the  upper  and  lower  eyelids,  and  open 
into  the  outer  side  of  the  angular  vein,  either  separatel}'  or  by  a  common 
trunk.  Several  branches  of  the  inferior  palpel^ral  vein  oj^cn  into  the  facial 
vein  (fig.  385). 

(3)  The  facial  vein,  the  continuation  of  the  angular,  begins  at  the  lower  margin 
of  the  orbit,  and,  crossing  the  face  oblicjuely  downwards  and  outwards,  passes  at 
the  anterior  edge  of  the  niasseter  muscle  over  the  l)ody  of  the  lower  jaw,  and  thence 
downwards  and  backwards  across  the  digastric  and  superior  carotid  triangles  to  join 
the  internal  jugular  vein  about  the  level  of  the  hyoid  bone.  It  runs  in  a  more  or 
less  direct  line  behind  its  corresponding  artery,  the  facial,  which  itself  pursues  a 
tortuous  course.  It  usually  passes  beneath  the  zygomatic  muscles  and  beneath  the 
])latysma,  but  above  the  other  muscles.  At  the  anterior  edge  of  the  niasseter  it 
meets  the  facial  artery,  lying  immediately  posterior  to  it.  In  the  neck  it  lies 
l)eneath  the  platysma  and  cervical  fascia,  and  is  usually  separated  from  the  facial 
artery  by  the  submaxillary  gland  and  the  stylo-hyoid,  and  the  posterior  l)elly  of 
the  digastricus  muscles,  below  which  it  frequently  receives  a  communicating  branch 
from  the  external  jugular  vein.  That  petition  of  the  vein  from  the  spot  when-  it 
receives  the  communicating  branch  to  its  termination  in  the  internal  jugular  is 
sometimes  called  the  common  facial  vein ;  and  the  communicating  branch,  tin- 
anterior  division  of  the  temporo-maxillary  vein.  (See  Tkmporo-maxili.arv 
N'kin,  page  61(3. ) 

Tributaries. — It  receives  on  its  inner  side,  from  above  downwards: — (a)  The 
inferior  lati  ral  nasal  veins;  (b)  the  superior  labial  vein;  (c)  the  inferior  labial  veins; 
(d)  the  sul)mcntal  vein;  (e)  the  suV)maxillary  veins.  On  its  outer  side  : — (a)  the 
inferior  pali)el»ral  veins;  (/^)  the  anterior  internal  maxillary  vein;  {<■)  the  buccal 
vein;  (d)  the  anterior  parotid  vein;  (e)  the  masseteri(^  vein;  and  (/)  the  inferior 
palatine  vein. 

Communications. — It  communicates  with  the  infraorbital  vein,  the  pterygoid 
plexus  of  veins,  the  anterior  jugular  vein,  and  the  external  jugular  vein. 

Tributaries  on  the  Inner  Side. — (a)  The  inferior  lateral  nasal  vein  is  a  small 
branch  which  corresponds  with  the  lateralis  nasi  artery.  It  joins  the  facial  on  a 
level  with  the  ala  of  the  nose. 

(6)  The  superior  labial  or  coronary  vein  begins  as  a  plexus  in  the  orbicularis 


614  THE  VEINS 

oris  muscle  of  the  upper  lip,  and  passes  with  the  superior  coronary  artery  outwards, 
and  joins  the  facial  vein  a  little  l)elow  the  level  of  the  ala  of  the  nose. 

(c)  The  inferior  labial  veins. — A  small  branch  (inferior  coronary)  usually 
opens  into  the  facial  a  little  helow  the  superior  labial  vein;  but  the  chief  ])ranch 
from  the  lower  lip  descends  as  a  rule  over  the  chin  to  the  submental  vein,  and  thus 
only  opens  indirectly  into  the  facial  vein.  It  may  open  into  the  anterior  jugular 
vein. 

(fZ)  The  submental  vein  lies  on  the  mylo-hyoid  muscle  superficial  to  the  sub- 
mental artery.  It  begins  below  the  chin,  and,  running  backwards  in  the  digastric 
triangle,  joins  the  facial  vein  just  after  the  latter  has  passed  over  the  body  of  the 
lower  jaw.  It  receives  branches  from  the  inferior  labial  plexus  and  the  neighbour- 
ing muscles,  and  communicates  with  the  anterior  jugular  vein. 

(e)  The  submaxillary  or  glandular  veins  open  into  the  facial  as  it  crosses  the 
submaxillary  gland.  But  some  branches  from  the  gland  often  open  into  the 
submental  vein. 

Tributaries  on  the  Outer  Side. — (a)  The  inferior  palpebral  veins. — Several 
branches  pass  downwards  to  the  facial  vein;  others,  as  before  stated,  pass  inwards 
to  the  angular  vein  (page  613).  Through  one  or  more  of  these  branches  a 
communication  is  formed  with  the  infraorbital  vein. 

(6)  The  anterior  internal  maxillary  vein,  sometimes  known  as  the  deep 
facial,  passes  downwards  and  forwards  from  the  pterygoid  plexus  of  veins  between 
the  buccinator  and  masseter  muscles,  and  opens  into  the  outer  side  of  the  facial  vein 
under  cover  of  the  zygomaticus  major  muscle. 

(c)  The  buccal  vein  is  a  small  branch  from  the  buccinator  muscle. 

(d)  The  anterior  parotid  branch  descends  from  the  giandula  socia  parotidis 
forwards  to  the  facial. 

(e)  The  masseteric  is  a  small  branch  from  the  masseter  muscle. 

(/)  The  inferior  or  descending  palatine  vein  accompanies  the  ascending 
palatine  or  tonsillar  artery  from  the  venous  plexus  about  the  tonsil  and  soft  palate, 
and  joins  the  facial  vein  just  below  the  body  of  the  lower  jaw. 

The  communicating  branch  between  the  external  jugular  and  facial  veins — 
sometimes  known  as  the  anterior  division  of  the  temporo-maxillary  vein — runs 
obliquely  downwards  and  inwards  from  the  external  jugular  vein  from  near  the 
spot  where  the  latter  is  continuous  with  the  temporo-maxillary  trunk.  It  joins  the 
facial  vein  deeply  just  behind  the  angle  of  the  jaw. 

The  chief  variations  in  the  facial  vein  are  : — (1)  It  may  ran  over  the  sterno-inastoid  and 
open  into  the  external  jugular  vein  ;  (2)  it  may  open  into  the  anterior  jugular  vein  ;  (3)  it  may 
run  beneath  the  posterior  belly  of  the  digastricus  and  stylo-hyoid  muscles ;  (4)  it  may  receive  the 
lingual  vein,  the  pharyngeal  vein,  or  both  of  these  veins. 

The  Posterior  Superficial  Vein  of  the  Scalp 

The  posterior  vein  descends  over  the  occipital  bone,  and  then  deeply  amongst 
the  muscles  at  the  back  of  the  neck.  It  ends  in  the  innominate  vein.  The  first  or 
superficial  portion  of  this  trunk  is  known  as  the  occipital  vein  ;  the  second  or 
deeper  portion  as  the  deep  cervical  vein   (fig.  385). 

The  occipital  vein  l)egins  at  the  back  of  the  skull  in  a  venous  plexus  which 
anastomoses  with  the  posterior  auricular  and  posterior  branch  of  the  .'^u])erficial 
temporal  veins.  It  passes  dowmwards  over  the  occipital  bone,  and,  perforating  tiie 
trapezius  with  the  occipital  artery,  sinks  deeply  into  the  suboccipital  triangle, 
where  it  terminates  in  the  deep  cervical  vein.  At  times  it  takes  a  more  su})erficial 
course,  and,  joining  the  posterior  auricular,  passes  with  this  into  the  external 
jugular  vein.  One  of  its  branches — usually  the  outermost — receives  an  emissary 
vein  issuing  through  the  mastoid  foramen  of  the  temporal  bone,  and  in  tliis  way 
forms  a  comnmnication  with  the  lateral  sinus. 

The  deep  cervical  vein  begins  as  a  plexus  of  small  veins  in  the  suboccipital 
triangle.  After  receiving,  as  a  rule,  the  occipital  vein,  it  passes  downAvards  betAveen 
the  complexus  and  the  semispinalis  colli,  in  company,  first  Avith  the  princeps  cervicis 
branch  of  the  occipital  artery,  and  afterAvards  Avith  the  deep  cervical  branch  of  the 


VELXS   OF  THE  SCALP  Glo 

sii])t'nor  intercostal  artery.  On  reacliing  tlie  transverse  process  of  the  seventh 
cervical  vertehra,  it  turns  forwards  between  that  process  and  the  neck  of  the  first 
ril),  and  opens  either  directly  into  the  innominate  vein  or  into  the  vertebral  imme- 
diately liefure  that  vein  joins  the  innominate. 

Tributaries. — It  receives  branches  from  the  muscles  amongst  which  it  runs. 

The  Lateral  Superficial  Veins  of  the  Scalp 

The  lateral  veins  descend,  one  in  front  and  one  ])eliind  the  ear,  and  unite 
about  the  level  of  the  angle  of  tlie  jaw  to  form  a  single  trunk — the  external  jugular 
vein. 

The  anterior  vein,  the  larger  of  the  two.  is  known  as  far  as  the  zygoma  as  the 
superficial  temporal  vein.  There  it  is  joined  by  a  deep  vein  from  the  temporal 
fossa — the  middle  temporal  vein  ;  and  the  united  trunk,  now  called  the  common 
temporal  vein,  passes  over  the  zygoma  into  the  parotid  gland.  Opposite  the  neck 
of  the  lower  jaw  it  receives  the  large  internal  maxillary  vein,  and  takes  the  name 
of  the  temporo-maxillary  vein.  This  emerges  from  the  lower  border  of  the 
parotid  gland,  and  joins  the  posterior  lateral  vein,  which  is  known  as  the  posterior 
auricular,  to  form  the  external  jugular  vein. 

The  Anterior  Lateral  Veins. — The  superficial  temporal  vein  returns  the  blood 
from  the  parietal  region  of  the  scalp.  It  is  formed  l)y  the  uni(jn  of  an  anterior  and  a 
posterior  branch:  the  former  communicates  with  the  supraorbital  and  frontal  veins; 
the  latter  with  the  posterior  auricular  and  occipital  veins  and  the  temporal  vein  of 
the  opposite  side.  These  branches  lie  superficial  to  the  corresponding  branches  of 
the  superficial  temporal  artery,  which  they  roughly  though  not  accurately  follow. 
Like  the  artery,  they  lie  between  the  skin  and  the  cranial  aponeurosis,  and  descend 
over  the  temporal  fascia  to  unite  a  little  above  the  zygoma,  and  just  in  front  of  the 
pinna  of  the  ear,  to  form  the  superficial  temporal  trunk.  The  vein  thus  formed 
continues  its  course  downwards  with  the  trunk  of  the  temporal  artery,  and 
opi)osite  the  zygoma  is  joined  by  the  middle  tem|toral  vein  to  form  the  common 
temporal  vein. 

The  middle  temporal  vein  corresponds  with  the  middle  temporal  artery.  It 
begins  in  a  plexus  in  the  temporal  fossa,  and  then  runs  backwards  l)etween  the 
layers  of  the  temporal  fascia,  the  outer  layer  of  which  it  perforates  near  the 
zygoma,  to  join  the  superficial  temporal  vein.  It  receives  an  orbital  branch,  which 
corresponds  with  the  orbital  branch  of  the  temporal  artery,  and  communicates  in 
front  with  the  ophthalmic  vein,  the  external  palpel)ral  veins,  and  the  infraorbital 
veins,  and  then  runs  backwards  l)etween  the  layers  of  the  temporal  fascia  to  join 
the  middle  temporal  trunk  or  plexus.  The  middle  temporal  vein  communicates 
with  the  dee]i  temporal  veins,  and  through  them  with  the  pterygoid  venous  plexus. 

The  common  temporal  vein,  formed  1)V  the  confluence  of  the  superficial  and 
middle  temporal  veins,  descends  over  the  zygoma  just  in  front  of  the  pinna  of  the 
ear,  lying  a  little  superficial  to  the  temporal  artery.  Then,  passing  deeply  into 
the  parotid  gland,  between  the  external  auditory  meatus  and  the  angle  of  the  jaw, 
it  is  joined  almost  at  a  right  angle  by  the  internal  maxillary  vein,  and  becomes  the 
temporo-maxillary  vein. 

Tributaries. — It  receives  (a)  the  transverse  facial  vein,  which  corresponds 
to  the  transverse  facial  artery;  {b)  articular  veins  from  the  {)lexus  around  the 
temporo-mandibular  joint — this  plexus  receives  the  tympanic  vein,  Avhich,  together 
with  its  corresponding  artery,  jjasses  through  tlie  tissm-e  of  (Uaser;  (r;  parotid 
veins,  from  the  substance  of  the  parotid  gland;  (d)  masseteric  veins,  from  the 
masseter  muscle;  and  (e)  anterior  auricular  veins,  from  the  pinna  of  the  ear. 

The  internal  maxillary  vein  accompanies  the  first  ])art  of  the  internal  max- 
illary artery  between  the  internal  lateral  or  spheno-mandiliular  ligament  and  the  neck 
of  the  lower  jaw.  It  begins  at  the  i)osterior  confluence  of  the  veins  forming  the 
pterygoid  plexus,  and  ends  by  uniting  with  the  common  tem|)oral  vein  to  form  the 
temporo-maxillary  trunk. 

The  pterygoid  plexus  is  formed  by  the  veins  which  correspond  to  the  branches 
of  the  internal  maxillary  artery.  It  is  situated,  partly  on  the  inner  surface  of  the 
internal  pterygoid  muscle,  and  partly  around  the  external  pterygoid  muscle.     The 


616  THE  VETXS 

veins  entering  into  this  plexus  are: — the  two  middle  meningeal,  which  accom- 
pany the  artery  of  that  name;  the  posterior  dental  vein  ;  the  mandibular  (inferior 
dental) ;  the  masseteric ;  tlie  buccal ;  the  pterygoid  veins  from  the  pterygoid 
muscles;  the  deep  temporal,  l»y  which  the  plexus  connnunicates  with  the  tem- 
poral plexus;  the  spheno-palatine  vein;  the  infraorbital;  the  superior  pala- 
tine ;  the  lower  brancli  of  the  ophthalmic  vein,  which  courses  through  the  spheno- 
maxillary fissure  from  the  orbit;  and  the  Vesalian  vein,  through  which  the  plexus 
comunicates  with  the  cavernous  sinus.  The  plexus  ends  posteriorly  in  the  internal 
maxillary  vein  which  joins  the  common  temporal  vein,  and  anteriorly  in  the  ante- 
rior internal  maxillary  or  deep  facial  vein,  which  passes  forwards  and  downwards 
between  the  buccinator  and  masseter  muscles  to  join  the  facial  vein. 

The  above-mentioned  veins,  forming  by  their  confluence  the  pterygoid  plexus, 
correspond  in  their  course  so  nearly  with  that  of  their  companion  arteries,  that  a 
detailed  description  is  not  necessary.  Although  deeply  placed,  they  are  for 
convenience  described  with  the  superficial  veins. 

The  temporo-maxillary  vein  is  formed  by  the  union  of  the  common  temporal 
vein  and  internal  maxillary  vein  in  the  substance  of  the  parotid  gland.  It  usually 
joins  about  the  angle  of  the  jaw  the  posterior  auricular  vein  to  form  the  external 
jugular.  At  other  times  it  divides  into  two  branches,  an  anterior  and  a  posterior. 
The  anterior  division  runs  forwards  and  downwards,  and  joins  the  facial  vein  (see 
Facial  Vein).  The  posterior  division  runs  backwards  over  the  sterno-mastoid 
and  joins  the  posterior  auricular  to  form  the  external  jugular.  When  the  temporo- 
maxillary  trunk  without  dividing  joins  the  posterior  auricular  to  form  the  external 
jugular  vein,  the  anterior  branch  is  represented  by  the  communicating  branch 
between  the  external  jugular  and  facial  veins. 

The  Posterior  Lateral  Veins. — The  posterior  auricular  vein  begins  in  a  venous 
})lexus  on  the  posterior  part  of  the  parietal  bone.  This  plexus  communicates  with 
the  vein  of  the  opposite  side,  across  the  sagittal  suture,  and  with  the  posterior 
branch  of  the  superficial  temporal  vein  in  front,  and  with  the  occipital  vein  behind. 
It  descends  over  the  back  part  of  the  parietal  bone  and  the  mastoid  process  of  the 
temporal  bone,  lying  wdth  its  artery  behind  the  ear.  It  then  leaves  the  artery, 
and  passing  over  the  upper  part  of  the  sterno-mastoid  muscle  obliquely  forwards  and 
downwards,  joins  the  temporo-mandibular  vein  al^out  the  level  of  the  angle  of  the 
lower  jaw,  forming  the  external  jugular  vein  (fig.  385). 

Tributaries. — (a)  Auricular  veins  from  the  back  of  the  pinna;  and  (b)  the 
stylo-mastoid  vein,  corresponding  to  the  little  stylo-mastoid  artery.  The  latter  vein 
opens  into  the  posterior  auricular  vein,  as  a  rule,  as  the  latter  leaves  the  mastoid 
process. 

2.  THE  SUPERFICIAL  VEINS  OF  THE  XECK 

The  external  jugular  vein  is  formed  by  the  confluence  of  the  posterior  auricular 
and  temporo-maxillary  veins  near  the  angle  of  the  lower  jaw.  It  runs  obliquely 
downwards  and  backwards  across  the  sterno-mastoid  muscle  to  a  spot  opposite  the 
middle  of  the  clavicle,  where  it  terminates  as  a  rule  in  the  subclavian  vein.  A 
line  drawn  from  a  point  midway  between  the  mastoid  process  and  angle  of  the  jaw 
to  the  middle  of  the  clavicle  will  indicate  its  course.  It  is  covered  by  the  skin, 
superficial  fascia,  and  platysma,  and  is  crossed  by  a  few  branches  of  the  cervical 
plexus,  the  great  auricular  nerve  running  parallel  to  it  at  the  upper  part  of  the 
neck.  It  at  first  crosses  the  sterno-mastoid  obliquely,  then  runs  nearly  parallel  to 
the  posterior  border  of  that  muscle,  from  which  it  is  separated  tln-oughout  its 
course  by  the  anterior  layer  of  the  deep  cervical  fascia. 

-Just  above  the  clavicle  it  perforates  the  cervical  fascia,  by  Avhich  it  is  prevented 
from  readily  collapsing,  the  fascia  being  attached  to  its  walls.  It  then  opens  into 
the  subclavian  vein;  occasionally  into  the  internal  jugular,  or  into  the  confluence 
of  the  subclavian  and  internal  jugular  veins.  It  contains  a  pair  of  valves  about  one 
inch  to  two  inches  above  the  clavicle,  and  a  second  pair  where  it  enters  the  sub- 
clavian vein.  Both  of  these  valves  were  shown  by  Sir  James  Struthers  not  to 
prevent  the  blood  regurgitating,  or  injections  passing  from  the  larger  vein  into  the 
external  jugular. 


VEjys  OF  THE  HEAD  A.\I>   XECK  (317 

Some  anatomists  describe  the  external  jugular  vein  as  being  formed  by  the 
junction  of  the  ]>osterior  auricular  and  occipital  veins.  The  vein  here  regarded  as 
the  upper  part  of  the  trunk  of  the  external  jugular  is  looked  upon  by  them  merely 
as  a  brancli  of  communication  between  the  external  jugular  and  tem])oro-maxillary 
vein. 

The  chief  variations  of  the  external  jugular  vein  are: — (1)  It  maj'  be  very  small,  or  much 
smaller  or  much  larger  tliau  tlic  opposite  veiu  ;  (2)  it  may  be  wantiii.tr  on  one  or  both  sides,  the 
veins  whie-li  nurmallj'  form  it  tlieii  opening  into  the  internal  jugular  ;  (3)  it  may  be  turnied  merely 
\)y  the  posterior  auricular  vein  ;  (4)  it  may  be  perforated  by  the  supei-ficialis  colli  neiTe  ;  (5)  it 
may  receive  the  facial,  the  lingual,  and  the  cephalic  veins  ;  (0)  it  may  pass  over  the  clavicle  and 
open  into  the  cephalic  or  subehivian  vein. 

Tributaries  and  communications. — From  al)Ove  downwards,  the  external 
jugular  receives  a  branch  from  the  internal  jugular  vein;  the  posterior  external 
jugular,  which  in  the  ffjetus  was  part  of  the  primitive  jugular  vein;  a  large 
Itranch  connecting  it  with  the  facial  vein;  one  or  two  small  branches  of  communi- 
cation from  the  anterior  jugular  vein;  near  its  termination,  the  transverse  cervi- 
cal and  suprascapular  veins  ;  and  sometimes  the  anterior  jugular  vein  at  the 
po.sterior  l)order  and  hinder  surface  of  the  sterno-mastoid.  At  times  the  occipital 
vein  opens  into  the  external  jugular,  and  is  by  some  anatomists  regarded  as  the 
normal  termination  of  the  former  vein. 

The  posterior  external  jugular  vein  descends  from  the  upper  and  back  part 
of  the  neck,  receiving  small  tributaries  from  the  superficial  structures  and  muscles. 
At  times  it  communicates  with  the  oi/cipital,  or  may  appear  as  a  continuation  of 
tliat  vein.  It  opens  into  the  external  jugular  as  the  latter  vein  is  leaving  the 
sterno-mastoid  muscle.  In  the  foetus  this  vein  returns  the  blood  from  the  interior 
of  the  cranium  through  the  post-glenoid  foramen.  Vestiges  of  the  foetal  trunk  are 
said  to  remain  in  the  mastoid  vein. 

The  suprascapular  veins,  two  in  number,  correspond  to  the  suprascapular 
artery.  They  usually  form  one  trunk  before  they  "open  into  the  external  jugular 
vein.      They  contain  well-marked  valves. 

The  transverse  cervical  veins — or  venae  comites  of  the  transverse  cervical 
artery — accompany  that  vessel  and  open  Avith  the  suprascapular  vein  into  the 
external  jugular  close  to  the  spot  where  the  latter  vein  joins  the  sul)clavian. 

The  anterior  jugular  vein  begins  below  the  chin  by  communicating  with  the 
mental,  submental,  inferior  labial,  and  inferior  hyoid  veins.  It  descends  a  little 
external  to  the  middle  line,  receiving  branches  from  the  superficial  structures  at 
the  frcjut  and  side  of  the  neck,  and  occasionally  a  branch  from  the  larynx  and  thyroid 
l)ody.  .Just  above  the  clavicle  it  turns  outwards,  and,  piercing  the  fascia,  passes 
beneath  the  sterno-mastoid  muscle  and  opens  into  the  external  jugular  vein  just 
before  the  latter  joins  the  subclavian;  at  times  it  opens  into  the  subclavian  vein 
it.self.  In  its  course  down  the  neck  it  communicates  with  the  external  jugular;  and, 
as  it  turns  outwards  beneath  the  sterno-mastoid,  sends  a  branch  across  the  trachea, 
between  the  layers  of  cervical  fascia,  to  join  the  anterior  jugular  of  the  ojtijosite 
side.  This  communicating  vein  may  be  divided  in  the  operation  of  tracheotomy,  and 
is  then  often  found  greatly  engorged  with  blood.  Another  branch,  often  of  consider- 
able size,  courses  along  the  anterior  margin  of  the  sterno-mastoid  and  joins  the 
facial  vein.  When  the  anterior  jugular  vein  is  large,  the  external  jugular  is  small, 
and  rice  rersd.  It  is  usually  also  of  large  size  when  the  corresponding  vein  on  the 
opposite  side  is  absent,  as  is  fre(iuently  the  case.     It  contains  no  valves. 

The  p(jsition  of  the  anterior  jugular  vein  beneath  the  t<'ndon  of  the  sterno-mastoid 
should  be  borne  in  mind  in  tenotomy  of  that  muscle  for  wry-neck. 


THE  DEEP  VETXS  OF  THE  HE  AD  AXD  XEOR' 

The  deep  veins  of  the  head  and  neck  may  be  divided  into — 1.  the  veins  rjf 
the  diploi';  L'.  the  venous  sinuses  of  the  cranium;  o.  the  veins  of  the  brain;  4.  the 
veins  of  the  nasal  cavities;  5.  the  veins  of  the  ear;  6.  the  veins  of  the  orbit;  7.  the 
veins  of  the  pharynx  and  larynx;  and  8.  the  deep  veins  <»f  the  neck.     The  veins  of 


618 


THE  VELXS 


the  diploe  terminate  partly  in  the  siipertieial  veins  already  described,  partly  in  the 
venous  sinuses  of  the  eranium,  and  partly  in  the  deep  veins  of  the  neck.  The 
vinous  sinuses  open  into  the  deep  veins  of  the  neck.  The  veins  of  the  brain  ter- 
minate in  the  venous  sinuses.  The  veins  of  the  nasal  cavities  terminate  partly  in 
the  deep,  and  to  some  extent  m  the  superficial  veins.  The  veins  of  the  ear  ynn  both 
the  superficial  and  deep  veins  and  the  venous  sinuses.  The  veins  of  the  orbit  ter- 
minate partly  in  the  superficial  veins,  but  chiefly  in  the  venous  sinuses.  The  veins 
of  the  pharynx  and  larynx  enter  the  deep  veins  of  the  neck. 


1.  THE  VEINS  OF  THE  DIPLOE 

The  veins  of  the  diploe  are  contained  in  bony  channels  in  the  cancellous  tissue 
between  the  external  and  internal  tables  of  the  skull.  They  are  of  comparatively 
large  size,  Avith  very  thin  and  imperfect  Avails,  and  form  irregular  communicating 
channels.     They  have  no  valves.     They  can  only  be  seen  on  removing  the  external 


Fig.  386. — The  Veins  of  the  Diploe. 
(From  a  specimen  iu  St.  Bartholomew's  Hospital  Museum.) 


THE  LAMBOOID 
SUTURE 

The  occipital  or 
pa  r  ieto-oecip  Hal 
diploic  vein 

The  external  pari- 
etal or  posterior 
temporal  diploic 
■vein 

THE  MASTOID 
FORAMEN 


THE  CORONAL  SUTURE 


The     frontal    di- 
ploic vein 

The     frontosphe- 
noidal  diploic 
vein 

The  /ronio-pari- 
elal  or  anterior 
temporal  diploic 
vein 


table  of  the  skull  with  a  file  or  chisel.  They  terminate  in  four  or  five  main  and 
descending  channels,  Avhich  open,  some  outwards  through  the  external  table  of  the 
skull  into  some  of  the  superficial  and  deep  veins  of  the  head  and  face,  and  some 
inwards  through  the  internal  table  into  the  venous  sinuses.  They- are  divided  into 
the  frontal.  fronto-s])henoidal.  fronto-parietal  or  anterior  tem])oral,  external  i)arietal 
or  posterior  temporal,  and  occipital  or  parieto-occipital. 

The  frontal  are  contained  in  the  anterior  part  of  the  frontal  bone.  They  con- 
verge anteriorly  to  a  single  vein  which  passes  downwards,  ])erforates  the  external 
table  through  a  small  aperture  in  the  roof  of  the  supraorbital  notch,  and  terminates 
in  the  supraorV)ital  vein. 

The  fronto-sphenoidal  are  contained  in  the  lateral  parts  of  the  frontal  bone, 
and.  running'  into  the  s]ihenoid  Ixnie,  terminate  in  the  sinus  ahe  parva\ 

Tlic  fronto-parietal,  or  anterior  temporal,  are  contained  in  the  posterior  part 
of  the  frontal  and  in  the  anterior  part  of  the  parietal  bone.  They  pass  downwards, 
and  end,  ])artly  in  the  deep  tem](oral  veins  by  perforating  the  greater  wing  of  the 
sphenoid  bone,  and  ])avtly  in  the  superior  ]ietvosal  sinus. 

The  external  parietal,  or  posterior  temporal,  ramifies  in  the  parietal  bone. 


VENOUS  SINUSES  OF  THE  CRAXIVM  619 

and,  coursing  doAvnwards  to  the  posterior  inferior  angle  of  that  bone,  passes  either 
through  a  foramen  in  its  inner  table,  or  through  the  mastoid  foramen  into  the  lateral 
sinus. 

The  occipital,  or  parieto-occipital,  ramifies  chiefly  in  the  occipital  l)one,  and 
opens  into  the  (lecijiital  vein  or  into  the  lateral  sinus. 

The  diploic  veins  freely  anastomose  with  one  another  in  the  adult;  l)Ut  in  the 
foetus,  before  the  bones  have  united,  each  svstem  of  veins  is  distinct. 


2.  THE  VEXOUS  SINUSES  OF  THE  CRANIUM 

The  venous  sinuses  of  the  cranium  are  endothelially  lined  blood-sjoaces,  situ- 
ated between  the  periosteal  and  meningeal  layers  of  the  dura  mater.  They  are  the 
channels  by  which  the  l)lood  is  conveyed  from  the  cerel>ral  veins,  and  from  some  of 
the  veins  of  the  meninges  and  diploe,  into  the  veins  of  the  neck.  The  sinuses  of  the 
base  of  the  skull  also  carry  the  chief  part  of  the  blood  from  the  orbit  and  eyeball  to 
the  jugular  veins.  At  certain  spots  the  sinuses  communicate  with  the  superficial 
veins  by  small  vessels  known  as  the  emissary  veins,  which  run  through  foramina 
in  the  cranial  bones. 

The  venous  sinuses  are  eighteen  in  number:  six  being  disposed  medianly 
and  singly;  six  laterally  and  in  pairs.  The  median  and  single  sinuses  are: — (1;  the 
superior  longitudinal;  (2)  the  inferior  longitudinal;  (3)  the  straight;  (4)  the 
occipital;  (o)  the  circular;  and  (6)  the  transverse  or  basilar.  The  lateral  and 
])aired  sinuses  are: — (7)  the  two  lateral;  (8)  the  two  superior  petrosal;  (9)  the  two 
inferior  petrosal;  (10)  the  two  cavernous;  (11)  the  tAvo  spheno-parietal  (sinus  ahe 
l)arvse),  and  (12)  the  two  sigmoid — which  latter,  however,  are  usually  described  as 
part  of  the  lateral.  Occasionally  there  are  two  additional  sinuses  (the  two  petro- 
squamous), due  to  the  persistence  in  the  adult  of  what  in  the  fcetus  was  the  con- 
tinuati(jn  of  the  lateral  sinus. 

(1)  The  superior  longitudinal  sinus,  or  superior  sagittal  sinus  (fig.  388), 
lies  in  the  median  groove  on  tlie  inner  surface  of  the  calvarium  along  the  attached 
margin  of  the  falx  cerebri.  It  extends  from  the  foramen  caecum  to  the  internal 
occii)ital  i)rotuberance.  It  grooves  from  before  backwards  the  frontal  l)one,  the 
contiguous  sagittal  margin  of  the  parietal  bones,  and  the  squamous  j^ortion  of  the 
occipital  bone.  In  the  ftx^tus  it  communicates,  tln-ough  the  foramen  caecum,  with 
tlie  nasal  veins,  and  generally  throughout  life  with  the  superficial  temporal  vein 
througli  the  parietal  foramen.  It  is  triangular  on  section,  the  base  of  the  triangle 
corresponding  to  the  bone.  Crossing  it  are  a  number  of  fibrous  bands  known  as 
the  chorda?  ^\'illisii,  and  projecting  into  it  in  places  are  the  Pacchionian  bodies. 
In  front  the  sinus  is  quite  small,  but  it  increases  greatly  in  calibre  as  it  runs  back- 
wards. It  receives  at  intervals  the  superior  cortical  cereliral  veins  and  the  veins 
from  the  falx.  The  former,  for  the  most  part,  open  into  it  in  the  direction  opposite 
to  that  in  which  the  blood  is  flowing  in  the  sinus.  They  pass  for  some  distance  in 
the  walls  of  the  sinus  befcn-e  opening  into  it.  Posteriorly,  at  the  internal  nceii)ital 
protuberance,  the  superior  longitudinal  sinus  usually  turns  sharply  to  the  right, 
and  ends  in  the  right  lateral  sinus;  the  straight  sinus  then  usually  terminates  in 
the  left  lateral  sinus,  and  the  right  and  left  lateral  sinuses  conmiunicate  with  each 
other  across  the  occipital  protuberance.  Occasionally,  however,  the  superior 
longitudinal  sinus  ends  in  the  left  lateral  sinus,  the  straight  then  passing  into  the 
right.  At  other  times  the  posterior  end  of  the  superior  longitudinal  sinus  at  the 
internal  occipital  ])rotuberance  becomes  slightly  dilated,  forming  what  is  called 
the  torcular  Herophili,  or  confluence  of  the  sinuses.  When  this  dilatation  exists, 
the  straight  sinus  usually  opens  into  it  in  front,  the  two  lateral  sinuses  on  either 
side,  the  superior  longitudinal  above,  the  occijtital  sinus  or  sinuses,  when  two  are 
present,  ])elow.  The  torcular  may  conmiunicate  with  the  occipital  vein  through 
the  occipital  emissary  vein,  which,  when  present.  ])asses  through  a  minute  foramen 
in  the  occipital  protuberance. 

(2)  The  inferior  longitudinal  or  inferior  sagittal  sinus  (fig.  388)  is  situated 
at  the  free  margin  of  the  falx  cerebri.     Beginning  about  the  junction  of  the  anterior, 
with  the  middle  third  of  the  falx,  it  is  continued  l)ackwards  along  the  concave  or 


620 


THE  VEINS 


lower  margin  of  that  process  to  the  junction  of  the  falx  with  tlie  tentorium,  where 
it  ends  in  the  straight  sinus.  The  sinus  is  cylinch-ical  in  shape  and  of  small  size, 
and  receives  some  of  the  inferior  frontal  veins  of  the  brain,  some  of  the  veins  from 
the  median  surface  of  the  l)rain,  and  some  of  the  veins  of  the  falx. 

(3)  The  straight  sinus,  or  sinus  rectus  (fig.  388) — also  variously  called  the 
sinus  tentorii,  perpendicularis,  and  obliquus — lies  along  the  junction  of  the  falx 
cerebri  with  the  tentorium  cerebelli.  It  is  formed  by  the  union  of  the  great  vein  of 
CJalen,  from  tlie  velum  interpositum,  and  the  inferior  longitudinal  sinus.  It  receives 
in  its  course  brandies  from  the  tentorium  cerebelli  and  from  the  upper  surface  of 
the  cerebellimi.  It  runs  downwards  and  backwards  to  the  internal  occipital  pro- 
tuberance, where  it  ends  in  the  left  lateral  sinus,  at  times  in  the  right  lateral  sinus, 
or  in  the  torcular  Herophili  when  that  blood-space  is  present.  On  section  it  is 
triangular  in  shape,  Avith  its  apex  upwards. 


Fig.  387. — The  Venous  Sinuses. 
(From  a  dissection  by  "W.  J.  Walsliam  iu  St.  Bartholomew's  Hospital  IMuseum.) 


Meningeal  branch  of 
anleiior  tlhmoidal  artery 


Meninf/eul  branch  nf  pos- 
terior ethmoidal  artery 

Middle  meningeal 

arteni 

OPHTHALMIC 

DIVISIOX  OF 

FIFTH  NERVE 

THIRD  NERVE 
Cavernous  sinus 
FOURTH  NERVE 
AVniTORY  AND 
FAdAL  NERVES 
Sitpt'rior  petrosal  sin  us 
Inferior  petrosal  sintis  _ 
Pelro-sqnamous  sinus 
HPINAL  ACCES- 
SOR Y NER VE 
Sigmoid  portion  0/ 
lateral  sinus 
Posterior  meningeal 
branch  of  vertebral 
artery 
Left  marginal  sinus 


Left  lateral  sinus 
Superior  longitudinal  sinus 


Circular  sinus 
Carotid  artery 
SIXTH  NERVE 
Basilar  artery 
Rastlar  plexus  of  reins 
A  udi/ory  artery 

Terttliral  arteri/ 
GLOSSO-PHARYNOEAL 
ASD   PXEfMOGASTRIC 

Antfrinr  spimil  arteri/     [X. 

HYPOCLUSSAL 

NERVE 
SPINAL  ACCES- 
SORY NERVE 

Right  marginal  sinus 
Occipital  sinus 
Right  lateral  sinus 


(4)  The  occipital  sinus  (fig.  387)  ascends  mesially  at  the  attached  margin  of 
the  falx  cerel>elli,  along  tlie  lower  half  of  the  squamous  portion  of  the  occipital 
bone  from  near  the  posterior  margin  of  the  foramen  magnum  to  the  internal 
occipital  ]~>rotuberance.  It  usually  begins  in  a  right  and  a  left  branch,  known  as  the 
marginal  sinuses.  These  proceed  from  the  termination  of  each  lateral  sinus,  run 
round  the  foramen  magnum,  where  they  communicate  with  the  posterior  spinal 
veins,  and  unite  at  a  variable  distance  from  the  internal  occii)ital  protul)erance  to 
form  the  single  occipital  sinus.  Sometimes  they  remain  separate  as  far  as  the 
occipital  protuberance,  then  forming  two  occipital  sinuses.  One  or  other  of  the 
marginal  sinuses  may  be  much  smaller  than  the  other,  or  be  entirely  absent. 
At  the  point  where  the  marginal  sinuses  unite  to  form  the  single  occiiiital  sinus, 
there  is  a  communication  with  the  posterior  spinal  veins.  The  occijiital  sinus 
ends  either  in  one  of  the  lateral  sinuses,   in  the  straight  sinus,  or  in  the  torcular 


VEX 0  us  SINUSES  OF  THE  CBAMUM 


621 


Herophili  when  tliis  is  present.  It  receives  in  its  course  veins  from  the  ten- 
torium cerebelli,  and  from  the  inferior  surface  of  the  cerebelkun.  It  communi- 
cates through  the  plexus  of  veins  which  surrounds  the  hypoglossal  nerve  in  the 
anterior  condyloid  foramen  with  the  vertehral  vein  and  veins  of  the  anterior  spinal 
plexus. 

(5)  The  circular  sinus,  so  called  (fig.  387),  is  a  venous  plexus  encircling  the 
hypophysis  cerebri,  and  connecting  the  right  and  left  cavernous  sinuses.  The  more 
distinct  channels  are  found,  one  in  front  of  the  sella  turcica,  one  behind,  and  one 
on  its  floor,  and  are  sometimes  called  the  anterior,  posterior,  and  inferior  inter- 
cavernous sinus,  the  last  being  also  known  as  the  inferior  circular  sinus  of 
W^inslow. 

(t) )  The  transverse  or  basilar  sinus  (fig.  387)  is  a  venous  plexus  in  the  sub- 
stance of  the  dura  mater  over  the  basilar  process  of  the  occipital  bone.  It  extends 
from  the   cavernous  sinus  to   the  margin  of    the    foramen    magnum  below.       It 


Fig.  388. — The  Venous  Sinuses.     (Longitudinal  section.) 

rO  UR  TH  XER  VE  THIRD  NER  VE 


Fall  cerebri 


SECOND  NERVE 


Superior  loni/i- 
tudinal  xiiiu.i 
Inferior  lonr/i- 
tudinal  sinus 


Veins  of  Galen 


S!raight  sinus 

Tentorium 
cerebelli 


Lateral  sinus  — 


Superior 
petrosal  sinus 

Falx  cerebelli 

SEVENTH  AM) 
KKiUTII 
NERVES 

NINTH.  TENTH.  AND 
ELEVENTH  NERVES 

TWELFTH  NERVE 

SECOND  CERVICAL  NERVE 

Ligamentum  deutieulatum 


in-i  II 

NERVE 


FTRST 
CERVICAL 

NER  I  '£■    Inferior  petrosal  sin  !m 


Vertebral 
artery 


communicates  laterally  with  the  inferior  petrosal  sinus,  and  inferiorly  with  the 
anterior  spinal  veins.  Through  this  sinus  passes  the  sixth  nerve.  One  of  the 
larger  of  the  irregular  venous  channels  forming  the  sinus  passes  transversely 
from  one  inferior  petrosal  sinus  to  the  other.  It  is  this  portion  to  which  tlie 
description  of  the  transverse  sinus  given  by  some  authors  ajtpears  to  apply.  This 
venous  plexus  on  the  basilar  process  is  serially  homologous  with  the  anterior  sj)inal 
plexus  of  veins  on  the  ])osterior  surface  of  the  bodies  of  the  vertebra^. 

(7)  The  lateral  sinus  (fig.  387)  extends  from  the  internal  occijntal  protuber- 
ance to  the  jugular  foramen.  In  this  course  it  lies  in  the  groove  (which  has  been 
named  after  it)  along  the  squamous  portion  of  the  occipital  bone,  the  posterior 
inferior  angle  of  the  parietal  bone,  the  mastoid  portion  of  the  temporal  bone,  and 
the  jugular  process  of  the  occipital  bone.  It  at  first  runs  horizontally  outwards 
and  forwards  between  the  two  layers  of  the  tentorium  cerebelli.  following  the  curve 
of  the  groove  on  the  occipital  and  the  posterior  inferior  angle  of  tlie  parietal  bones. 
In  this  part  of  its  course  it  is  sometimes  known  as  the  transverse  sinus,  or 
lateral  sinus  proper,  but  on  reaching  the  groove  in  the  mastoid  portion  of  the  tern- 


622  THE  VEINS 

poral  bone  it  leaves  the  tentorium  and  curves  downwards  and  inwards  and  then 
forwards  over  the  jugular  process  of  the  occi])ital  lione,  and  ends  in  the  posterior 
compartment  of  tlie  jugular  fossa  in  the  sinus  jugularis  or  bulb  of  the  internal 
jugular  vein.  The  S-shaped  })art  of  the  sinus  Avhich  lies  on  the  mastoid  portion 
of  the  temporal  and  jugular  ])ortion  of  the  occipital  l^one  is  sometimes  known 
as  the  sigmoid  sinus.  The  lateral  sinus  receives  the  veins  from  the  temporo- 
sphenoidal  lobe  of  the  cerebrum,  some  of  the  superior  and  inferior  cerebellar 
veins,  some  of  the  veins  of  the  medulla  and  pons,  the  occipital  and  the  external 
parietal  veins  of  the  diploe,  and  at  the  spot  where  it  leaves  the  tentorium  the  supe- 
rior petrosal  sinus  and,  Avhen  present,  the  petro-squamous  sinus.  It  communi- 
cates with  the  occipital  and  vertebral  veins  through  the  mastoid  and  posterior 
condyloid  foramina  by  means  of  emissary  veins.  As  the  lateral  sinus  lies  betAveen 
the  layers  of  the  tentorium  it  is  on  section  prismatic  in  shape.  The  sigmoid 
portion  is  semicylindrical. 

The  right  lateral  sinus  is  usually  the  larger  and  the  direct  continuation  of  the 
superior  longitudinal  sinus,  and  hence  conveys  the  chief  part  of  the  blood  from 
the  cortical  surface  of  the  brain  and  vault  of  the  skull.  The  left  lateral  sinus  is 
usually  the  smaller  and  the  direct  continuation  of  the  straight  sinus,  and  hence 
returns  the  chief  part  of  the  blood  from  the  central  ganglia  of  the  brain. 

The  relation  of  the  lateral  sinus  to  the  outside  of  the  skull,  especially  to  the 
mastoid  process  of  the  temporal  bone,  is  of  importance  with  reference  to  the  opera- 
tions of  trephining  the  mastoid  cells,  opening  the  tympanum,  and  exposing  the 
sinus  itself,  in  septic  thrombosis,  &c.  The  course  of  the  sinus  corresponds  to  a 
line  drawn  from  the  external  occipital  protuberance  to  the  base  of  the  mastoid  pro- 
cess, or  to  the  asterion,  and  thence  over  the  back  of  the  mastoid  process  in  a 
curved  line  towards  its  apex. 

(8)  The  superior  petrosal  sinus  (figs.  387,  388)  runs  at  the  attached  margin 
of  the  tentorium  cerebelli,  along  the  upper  border  of  the  petrous  portion  of  the 
temporal  bone.  It  connects  the  cavernous  with  the  lateral  sinus.  Leaving  the 
outer  and  back  part  of  the  cavernous  sinus  just  below  the  fourth  nerve,  it  crosses 
the  fifth  nerve,  and,  after  grooving  the  petrous  bone,  ends  in  the  lateral  sinus  as 
the  latter  turns  downwards  on  the  mastoid  portion  of  the  temporal  bone.  It 
receives  veins  from  the  temporo-sphenoidal  lol^e  of  the  cerebrum,  veins  from  the 
cerebellum,  veins  from  the  tympanum  through  the  squamo-petrosal  fissure,  and 
sometimes  the  fronto-parietal  veins  of  the  diploe. 

(9)  The  inferior  petrosal  sinus  (figs.  387,  388)  runs  along  the  line  of  the 
petro-occipital  suture,  and  connects  the  cavernous  sinus  with  the  commencement 
of  the  internal  jugular  vein.  It  is  shorter  than  the  superior  petrosal,  but  con- 
siderably wider.  As  it  crosses  the  anterior  compartment  of  the  jugular  foramen,  it 
separates  the  glosso-pharyngeal  from  the  pneumogastric  and  spinal  accessory 
nerves.  It  receives  veins  from  the  inferior  surface  of  the  cerebellum,  from  the 
medulla  and  pons,  and  from  the  internal  ear.  The  last  issue  through  the  aqueduc- 
tus  vestilmli  and  aqueductus  cochleae. 

(10)  The  cavernous  sinus  (fig.  387)  is  an  irregular  shaped  venous  space 
situated  Ijetween  the  meningeal  and  periosteal  layers  of  the  dura  mater  on  the  side 
of  the  body  of  the  sphenoid  bone.  It  extends  from  the  central  end  of  the  sphe- 
noidal fissure  in  front  to  the  apex  of  the  petrous  bone  behind.  Its  outer  wall  is  the 
more  distinct,  and  contains  in  it,  but  separated  from  the  blood  by  the  lining  mem- 
l)rane  of  the  sinus,  the  third  and  fourth  nerves,  and  the  ophthalmic  division  of 
the  fifth  nerve,  the  nerves  lying  in  the  above-mentioned  order  frcim  above  down- 
wards, and  from  witliin  outAvards.  The  internal  carotid  artery  and  the  sixth 
nerve  also  pass  through  the  sinus,  being  separated  from  the  blood  by  the  endothel- 
ial lining.  The  inner  wall  is  practically  absent,  the  blood-space  communicating 
across  the  middle  line  with  the  opposite  sinus  in  front,  behind,  and  below  the 
pituitary  body  or  hypophysis  cerebri.  (See  Circul.\r  Sixus.  )  The  cavernous 
sinus  is  traversed  by  numerous  trabecular  or  fibrous  bands,  so  that  there  is  no 
central  space,  but  rather  a  number  of  endothelially-lined  irregular  lacunar  cavities 
communicating  with  each  other.  Hence  its  name  cavernous,  from  its  resem- 
blance to  cavernous  tissue.  In  front  it  receives  the  ophthalmic  vein,  witli  which 
it  is  practically  continuous,  and  just  above  the  third  nerve  the  sinus  ala3  parvse. 


i 


CEREBRAL   AND   CEREBELLAR  623 

Internally  it  communicates  with  the  opposite  (iinus,  ami  posteriorly  it  ends  in  the 
sui)erior  and  inferior  petrosal  sinuses.  It  also  receives  veins  from  the  inferior  sur- 
face of  the  frontal  lobe  of  the  brain,  and  some  of  the  middle  cerebral  veins. 
Through  the  Vesalian  vein,  which  runs  in  a  minute  foramen  in  the  spinous  pro- 
cess of  the  sphenoid  bone,  the  sinus  communicates  with  the  pterygoid  plexus 
of  veins;  through  the  venous  plexus  around  the  intraosseous  portion  of  the 
internal  carotid,  with  the  internal  jugular  vein;  and  through  small  veins  which 
leave  the  cranium  l>y  the  foramen  ovale  and  foramen  lacerum  medium,  with 
tlie  pterygoid  and  |)haryng(>al  |)l<'xuses. 

(11)  The  spheno-parietal  sinus,  or  sinus  alae  parvse,  runs  in  a  slight  groove 
on  the  under  surface  of  the  lesser  wing  of  the  sphenoid  bone.  It  originates  in  one 
oi  the  meningeal  veins  near  the  apex  of  the  lesser  wing,  and,  running  inwards, 
passes  through  the  sphenoidal  fold  of  dura  mater  above  the  third  nerve  into  the 
front  part  of  the  cavernous  sinus.  It  generally  receives  the  fronto-sphenoidal  veins 
from  the  diploe. 

The  petro-squamous  sinus  is  occasionally  present.  It  lies  in  a  groove  along 
the  junction  of  tlie  petrous  and  S(iuamous  portions  of  the  temporal  bone.  It  opens 
posteriorly  into  the  lateral  sinus  at  the  spot  where  the  latter  enters  on  its  sigmoid 
course.  In  front  it  sometimes,  though  very  rarely,  passes  through  a  foramen  in  the 
S({uamous  portion  of  the  temporal  bone  between  the  glenoid  cavity  and  the  external 
auditory  meatus  into  the  temporal  vein.  This  sinus  is  the  rudiment  of  what  in 
early  foetal  life,  before  the  development  of  the  internal  jugvilar  vein,  was  the  con- 
tinuation of  the  lateral  sinus,  the  blood  from  the  interior  of  the  skull  at  this  i^eriod 
passing  through  the  above-mentioned  foramen  into  the  primitive  jugular  vein. 


3.  THE  VEIXS  OF  THE  BPxAIX 

The  veins  of  the  brain  present  the  following  peculiarities: — (a)  They  do  not 
accompany  the  cerebral  arteries.  (6)  Ascending  veins  do  not  as  in  other  situations 
run  with  descending  arteries,  but  with  ascending  arteries,  and  vice  versa,  (c)  The 
deep  veins  do  not  freely  communicate,  (d)  The  veins  have  very  thin  Avails,  no 
muscular  coat,  and  no  valves,  (e)  The  veins  opening  into  the  longitudinal,  and 
some  of  those  opening  into  the  lateral  sinus  pour  in  their  blood  in  a  direction 
opposite  to  the  current  in  the  sinuses,  so  impeding  the  flow  in  both  vein  and  sinus. 
(/)  The  flow  of  blood  in  the  sinuses  is  further  retarded  by  the  trabecular  stretching 
across  their  lumen,  and  in  the  longitudinal  sinus  b}'  the  blood  having  to  ascend, 
when  the  body  is  erect,  through  the  anterior  half  of  its  course. 

The  veins  of  the  brain  may  be  divided  into  the  cerebral  and  the  cerebellar. 

The  Cerebral  Veins 

The  cerebral  veins,  like  the  cerebral  arteries,  may  be  divided  into  the  cortical 
or  hemispheral,  and  the  central  or  ganglionic. 

The  cortical,  hemispheral  or  superficial  veins  ramify  on  the  surface  of  tlie 
Itrain  and  return  the  blood  from  tlic  cortical  substance  into  the  venous  sinuses. 
They  lie  for  the  most  part  in  the  sulci  jjetween  the  convolutions,  Init  some  pass 
over  the  convolutions  from  one  sulcus  to  another.  They  consist  of  two  sets:  a 
superior  and  an  inferior. 

(1)  The  superior  cortical  veins,  some  eight  to  twelve  in  number  on  each  side, 
are  formed  by  the  union  of  branches  from  the  convex  and  median  surfaces  of  the 
cerebrum.  Those  from  the  convex  surface  pass  forwards  and  inwards  towards  the 
longitudinal  fissure,  where  they  are  joined  by  the  branches  coming  from  the  median 
surface.  After  receiving  a  sheath  from  the  arachnoid,  they  enter  oldiquely  into 
the  superior  longitudinal  sinus,  ruiming  for  some  distance  in  its  walls.  These  veins 
freely  eonmiunicate  with  each  other,  thus  difi"ering  from  the  cortical  arteries.  They 
also  connnunicate  with  the  inferior  cortical  veins.  They  may  lie  roughly  divided 
into  (a)  frontal:   (7;)  paracentral:   (r)  central;  and  (d  )  occi|)ital. 

(2)  The  inferior  cortical  veins  ramify  on  the  base  of  the  hemisphere  and  the 
lower  part  of  its  outer  surface.     Those  on  the  infi'rior  surface  of  the  frontal  lobe 


624  THE  VEINS 

pass,  in  part  into  the  inferior  longitudinal  sinus,  and  in  part  into  the  cavernous 
sinus.  Those  on  the  temporo-sphenoidal  lobe  enter  in  part  into  the  superior 
petrosal  sinus,  and  in  part  into  the  lateral  sinus,  passing  into  the  latter  from  before 
backwards.  A  large  vein  from  the  occipital  lobe  winds  over  the  crus  cerebri  and 
joins  the  great  vein  of  Galen  just  before  the  latter  enters  the  straight  sinus.  One 
of  the  inferior  cortical  veins  is  sometimes  called  the  middle  cerebral  vein;  another 
the  great  anastomosing  vein  of  Trolard;  another  the  posterior  anastomosing  vein  of 
Labbe.  The  first  ramifies  over  the  under  surface  of  the  frontal  and  temporo- 
sphenoidal  lobes,  and  at  the  anterior  and  lower  part  of  the  fissure  of  Sylvius  opens 
into  the  cavernous  sinus.  The  second  establishes  a  communication  between  the 
superior  longitudinal  and  cavernous  sinuses  by  anastomosing  with  the  middle 
cerebral  and  one  of  the  superior  cortical  veins.  The  third  passes  from  the  middle 
cerebral  vein  over  the  temporo-sphenoidal  lobe  to  the  lateral  sinus. 

The  central,  ganglionic,  or  deep  cerebral  veins  are  collected  into  two  large 
venous  trunks,  the  vense  Galeni,  which  leave  the  brain  at  the  great  transverse 
fissure,  that  is,  between  the  splenium  of  the  corpus  callosum  and  the  optic  lobes. 
At  this  spot  they  unite  to  form  a  single  vein,  the  vena  magna  Galeni,  which 
opens  into  the  anterior  end  of  the  straight  sinus.  The  vense  Galeni  are  formed  by 
the  union  of  the  choroid  vein  with  the  vena  corporis  striati  near  the  foramen  of 
Monro.  From  this  spot  they  run  backwards  parallel  to  each  other  between  the 
layers  of  the  velum  interpositum,  and  terminate  in  the  way  above  mentioned. 

Tributaries  of  the  veins  of  Galen. — The  choroid  vein,  the  vein  of  the  corpus 
striatum,  the  basilar  vein,  the  veins  of  the  optic  thalamus,  the  vein  of  the  choroid 
plexus  of  the  third  ventricle,  and  veins  from  the  corpus  callosum,  the  pineal  body, 
the  optic  lobes,  and  posterior  horn  of  the  lateral  ventricle.  The  united  trunk,  or 
great  vein  of  Galen,  receives  veins  from  the  upper  surface  of  the  cerebellum,  and 
one  of  the  posterior  inferior  cerebral  veins. 

The  choroid  vein  runs  with  the  choroid  plexus.  It  begins  in  the  inferior  cornu 
of  the  lateral  ventricle,  and  ascends  on  the  outer  side  of  the  choroid  plexus  along 
the  margin  of  the  velum  interpositum  to  the  foramen  of  Monro,  where  it  unites 
with  the  vein  of  the  corpus  striatum  to  form  the  vein  of  Galen.  It  receives  tribu- 
taries from  the  hippocampus  major,  corpus  callosum,  and  fornix. 

The  vena  corporis  striati,  formed  by  veins  from  the  corpus  striatum  and  optic 
thalamus,  runs  forwards  in  the  groove  between  those  structures,  passing  in  its  course 
beneath  the  taenia  semicircularis,  and  joins  the  vein  of  Galen  at  the  foramen  of 
Monro.  Tributaries. — It  receives,  in  addition  to  the  veins  from  the  corpus  stria- 
tum and  optic  thalamus,  small  veins  from  the  fornix,  septum  lucidum,  and 
anterior  cornu  of  the  lateral  ventricle. 

The  basilar  vein,  formed  by  the  confluence  of  the  deep  Sylvian  vein,  the 
inferior  striate  veins,  and  some  small  anterior  cerebral  veins,  runs  backwards  over 
the  crus  cerebri,  and  enters  the  vein  of  Galen  near  the  union  of  that  vessel  Avith 
the  vein  of  the  opposite  side.  Tributaries. — The  deep  Sylvian  vein  from  the  insula 
and  surrounding  convolutions;  the  inferior  striate  veins  from  the  corpus  striatum, 
which  they  leave  through  the  anterior  perforated  space;  anterior  cerebral  veins 
from  the  front  of  the  corpus  callosum;  interpeduncular  veins  from  the  structures 
in  the  interpeduncular  space;  ventricular  veins  from  the  middle  cornu  of  the  lateral 
ventricle;  and  mesencephalic  veins  from  the  mid-l»rain. 

The  Cerebellar  Veins 

The  cerebellar  veins  are  divided  into  the  superior  and  inferior. 

The  superior  ramify  on  the  upper  surface  of  the  cerebellum;  some  of  them 
run  inwards  over  the  superior  vermiform  process  to  join  the  straight  sinus  and 
great  vein  of  Galen;  others  run  outwards  to  the  lateral  and  superior  petrosal 
sinuses. 

The  inferior,  larger  than  the  superior,  run,  some  forwards  and  outwards  to  the 
inferior  petrosal  and  lateral  sinuses,  and  others  directly  backwards  to  the  occipital 
sinuses. 


XASAL—A  URICULAR—OPHTHA  LMIC  625 

The  Veins  of  the  Medulla  and  Pons 

The  veins  from  the  medulla  oblongata  and  the  pons  terminate  in  the  inferior 
petrosal  and  lateral  sinuses. 


4.  THE  VEINS  OF  THE  NASAL  CAVITIES 

The  venous  plexuses  on  the  inferior  turbinated  bone  and  back  of  the  septum 
are  described  with  the  Nose.  The  veins  leaving  the  nasal  cavities  follow  roughly 
the  course  of  their  corresponding  arteries.  Thus  the  spheno-palatine  veins  pass 
tlirough  the  spheno-palatine  foramen  into  the  pterygoid  plexus;  the  anterior  and 
l^osterior  ethmoidal  veins  join  the  ophthalmic.  Small  veins  accompany  branches  of 
the  facial  artery  through  the  nasal  bones  and  nasal  processes  of  the  superior 
maxillary  bones,  and  end  in  the  angular  and  facial  veins;  and  other  small  veins  pass 
from  the  nose  anteriorly  into  the  superior  labial,  and  thence  to  the  facial. 


5.  THE  VEINS  OF  THE  EAR 

The  veins  from  the  external  ear  and  external  auditory  meatus  join  the  temporal 
and  posterior  auricular  veins.  The  veins  from  the  tympanum  open  into  the 
suijcrior  petrosal  sinus  and  temporo-maxillary  vein.  The  blood  from  the  labyrinth 
flows  chiefly  through  the  internal  auditory  veins  which  lie  with  the  internal 
auditory  artery  in  the  internal  auditory  meatus,  and  enters  the  inferior  petrosal  or 
lateral  sinus.  Some  of  the  blood  from  the  labyrinth,  however,  passes  through  the 
vestibular  vein  which  lies  in  the  aqueductus  vestibuli,  into  the  inferior  petrosal 
-inus,  and  some  through  the  aqueductus  cochlese,  into  the  commencement  of 
the  internal  jugular  vein. 


6.  THE  VEINS  OF  THE  ORBIT 

The  blood  from  the  eyeball  and  orbit  is  returned  by  the  ophthalmic  vein  into 
tlie  cavernous  sinus.  This  vein  and  its  tributaries  have  no  valves,  and  communi- 
cate in  front  with  the  frontal,  supraorbital,  and  other  veins.  Hence  under  certain 
conditions,  as  from  pressure  on  the  cavernous  sinus,  the  blood  may  flow  in  the 
contrary  direction  to  the  normal — i.  e.  from  behind  forwards  into  the  frontal  and 
supraorbital,  and  thence  through  the  angular  vein  into  the  facial.  In  this  way 
I)ressure  on  the  retinal  veins  is  quickly  relieved,  and  little  or  no  distension  occurs 
in  cases  of  obstruction  in  the  cavernous  sinus. 

The  ophthalmic  vein,  or  common  ophthalmic  vein,  is  formed  by  the 
confluence  at  the  back  of  the  orl)it  of  the  superior  and  inferior  ophthalmic  veins. 
It  is  a  short  thick  trunk,  and  passes  backwards  between  the  two  heads  of  the 
external  rectus  muscle  below  the  sixth  nerve,  and  at  the  inner  part  of  the 
sphenoidal  fissure  leaves  the  orbit  and  enters  the  front  part  of  the  cavernous  sinus. 

A.  The  superior  ophthalmic  vein,  larger  than  the  inferior,  begins  at  the 
inner  canthus  of  the  eyelid  by  a  free  communication  with  the  frontal,  supra- 
orbital, and  angular  veins,  and  thence  runs  backwards  and  outwards  with  the 
ophthalmic  artery  across  the  optic  ner\'e  to  the  inner  end  of  the  sphenoidal 
fissure,  Avhere  it  joins  the  inferior  ophthalmic  vein  to  form  the  common  ophthalmic 
trunk.     In  this  course  it  lies  anterior  and  superficial  to  the  ophthalmic  artery. 

Tributaries. — (1)  The  superior  muscular  veins;  (2)  the  ciliary  veins;  (3)  the 
anterior  and  posterior  ethmoidal  veins;  (4)  the  lachrymal  vein;  and  (5)  the  central 
vein  of  the  retina. 

(1)  The  superior  muscular  branches  are  derived  from  the  levator  palpel)rse, 
superior  rectus,  superior  oblique  and  internal  rectus. 

(2)  The  ciliary  veins  are  divided  into  two  sets:  an  anterior,  which  emerge 
from  the  evel)all  with  the  anterior  ciliary  arteries,  and  open  into  the  muscular  veins 
returning  the  blood  from  the  four  recti;  and  a  posterior  set,  known  as  the  venae  vor- 

40 


62G 


THE  VEINS 


ticosae,  which  leave  the  gloVje  midway  between  the  cornea  and  entrance  of  the  optic 
nerve.  The  latter  veins  are  four  or  five  in  number,  the  upper  ending  in  the  sujje- 
rior,  the  lower  in  the  inferior  ophtlialmic  vein  (page  852). 

(3)  The  anterior  and  posterior  ethmoidal  veins  corresijond  in  their  course 
with  the  arteries  of  the  same  namr.  They  enter  the  orbit  through  the  anterior  and 
posterior  etlnuoidal  foramina,  and  join  either  the  ophthalmic  direct,  or  one  or  other 
of  the  superior  muscuhir  l)ranches. 

(4)  The  lachrymal  vein  returns  the  l)lood  from  the  lachrymal  gland,  and  corre- 
sponds in  its  course  to  the  lachrymal  artery. 

(5)  The  central  vein  of  the  retina  runs  with  the  central  artery  in  the  optic 
nerve.     It  joins  the  superior  ophthalmic  at  the  back  of  the  orbit. 


Fiu.  389. — The  Veins  of  the  Orbit. 


Supraorbital  arlerij 

LACHRYMAL  GLAND 
Superior  rectus,  cut 

EYEBALL 


External  rectus       A. 


Lachrymal  artery 

Superior  rectus,  cut 
Inferior  ophthalmic  vein 
Siiperior  ophthalmic  vein 


OPTIC  NERVE 

Common  ophthalmic  vein 


Commencement  of  superior 
ojihthaimic  vein 

Reflected  tendon  of  superior 

oblique 
Ophthalmic  artery 


Anterior  ethmoidal  artery 

Posterior  ethmoidal  artery 
Cilian/  arteries 

Levator  palpebrae,  cut 
Ligament  of  Zinn 
Ophthalmic  artery 

OPTIC  COMMISSURE 


Internal  carotid  artery 


B.  The  inferior  ophthalmic  vein,  smaller  than  the  superior,  is  formed  near  the 
front  of  the  orbit  l)y  the  confluence  of  the  inferior  muscular  with  the  lower  posterior 
ciliary  veins.  It  runs  backwards  below  the  optic  nerve,  along  the  floor  of  the  orbit, 
and  either  joins  the  superior  ophthalmic  vein  to  form  the  common  ophthalmic  trunk, 
or  else  opens  separately  into  the  cavernous  sinus.  A  large  communicating  branch 
passes  downwards  through  the  spheno-maxillarv  fissure  to  join  the  pterygoid  plexus 
of  veins. 

Tributaries. — (1)  Tlie  inferior  muscular,  wliich  are  derived  from  tlie 
inferior  ol>li<iue,  inferior  rectus,  and  external  rectus;  and  (2)  the  lower  posterior 
ciliary  veins. 


7.  THE  VEINS  OF  THE  PHARYNX  AND  LARYNX 

The  veins  of  the  pharynx  are  arranged  in  the  form  of  a  plexus,  between  the 
constrictor  muscles  and  the  pharyngeal  or  prevertebral  fascia.  The  plexus  receives 
branches  from  the  mucous  membrane,  from  the  soft  palate,  the  Eustachian  tube, 
and  the  ante^rior  recti  and  lons;us  colli  muscles.     Above,  it  comnumicates  with  the 


IXTERXAL   JUGULAR  627 

pterygoid  plexus  of  veins;  below,  either  with  the  lower  end  of  the  facial  vein,  or 
with  the  intrnial  jutrular  vein. 

The  veins  of  the  larynx  end  partly  in  the  superior,  and  partly  in  the  inferior 
thyroid  veins. 

8.  THE  DEEP  VEINS  OF  THE  NECK 

The  deep  veins  of  the  neck  are  the  internal  jugular  vein,  the  vertebral  vein, 
and  the  deep  cervical  vein  and  their  respective  tributaries. 

The  Internal  Jugular  Vein 

The  internal  jugular  vein  begins  at  the  jugular  fossa,  and  is  the  continuation 
of  the  lateral  sinus.  It  passes  down  the  neck  in  company  first  Avith  the  internal 
carotid  artery,  and  then  with  the  common  carotid  artery  to  a  spot  a  little  external 
to  the  sterno-claAdcular  articulation,  where  it  joins  the  subclavian  to  form  the 
innominate  vein.  At  its  commencement  in  the  larger,  and  posterior  and  external 
part  of  the  jugular  foramen,  it  is  somewhat  dilated,  forming  the  so-called  bulb  or 
sinus  of  the  internal  jugular  vein.  This  dilated  part  of  the  internal  jugular  vein 
lies  in  the  jugular  fossa  of  the  temporal  bone  and  is  therefore  in  immediate 
relation  to  the  floor  of  the  tympanum.  At  first  the  internal  jugular  lies  in  front 
of  the  rectus  capitis  lateralis,  and  behind  the  internal  carotid  artery,  from  which  it 
is  separated  by  the  hypoglossal,  glosso-pharyngeal,  and  pneumogastric  nerves,  and 
by  the  carotid  plexus  of  the  sympathetic.  But  as  it  descends  it  passes  gradually 
to  the  outer  side  of  that  vessel,  and  retains  this  relation  as  far  as  the  upper  border 
of  the  thyroid  cartilage.  Thence  it  runs  to  its  termination  along  the  outer  side  of 
the  common  carotid  artery,  being  contained  in  the  same  sheath  with  it  and  the 
pneumogastric  nerve,  but  separated  from  these  structures  by  a  distinct  septum.  The 
vein  generally  overlaps  the  artery  in  front;  hence  the  importance  in  tying  the  carotid 
of  opening  the  sheath  well  to  the  inner  side  of  that  vessel,  in  order  to  avoid  the 
vein.     About  an  inch  above  its  termination  it  contains  a  pair  of  imperfect  valves. 

Tributaries. — At  the  bulb  or  sinus  the  internal  jugular  vein  receives  the 
inferior  jjetrosal  sinus;  opposite  the  angle  of  the  jaw  veins  from  the  pharyngeal 
plexus,  and  often  a  communicating  branch  from  the  external  jugular  vein;  opposite 
the  bifurcation  of  the  carotid  it  is  joined  by  the  facial,  and  a  little  lower  down  by 
the  lingual  and  the  superior  thyroid  vein,  and  at  the  level  of  the  cricoid  cartilage 
by  the  middle  thyroid  vein. 

The  inferior  petrosal  sinus  is  described  with  the  other  sinuses  of  the  brain 
(page  622);  the  pharyngeal  plexus  with  the  veins  of  the  ])harynx  (see  above);  and 
the  facial  vein  with  the  superficial  veins  of  the  scalp  and  face  (page  613). 

The  lingual  vein  begins  near  the  tip  of  the  tongue,  under  the  name  of  the 
ranine.  It  lies  at  first  close  to  the  hypoglossal  nerve  and  beneath  the  nmcous 
membrane  covering  the  under  .surface  of  the  tongue.  It  then  passes  backwards 
across  the  hyo-glossus  where  this  muscle  forms  the  floor  of  Lesser' s  triangle,  the 
latter  muscle  intervening  between  it  and  the  lingual  artery.  After  receiving  the 
sublingual  vein  and  the  dorsalis  lingufe  veins  which  roughly  correspond  to  their 
respective  arteries,  and  the  two  small  veins  (ven*  comites)  which  fre(juently 
accompany  the  lingual  artery  beneath  the  hyo-glossus,  the  united  trunk  crosses  the 
common  carotid  artery  and  opens  into  the  internal  jugular  vein.  At  times  these 
tributaries  open  separately  into  the  internal  jugular  vein  or  into  the  facial  vein. 

The  superior  thyroid  vein  emerges  from  the  upper  part  of  the  thyroid  body, 
in  Avhich  it  freely  anastomoses  with  the  other  thyroid  veins,  both  in  the  substance 
of  the  organ,  and  on  its  surface  beneath  the  capsule.  Thence  it  passes  upwards 
and  outwards  into  the  internal  jugular  vein,  crossing  the  common  carotid  artery  in 
its  course.  At  times  it  forms  a  common  trunk  with  the  facial  vein.  Its  tribu- 
taries are  the  sterno-hyoid,  sterno-thyroid,  and  thyro-hyoid  veins  from  the  muscles 
bearing  those  names;  and  the  crico-thyroid  and  superior  laryngeal  vein,  which 
correspond  with  the  crico-thyroid  and  superior  laryngeal  arteries  respectively. 
These  require  no  special  description. 

The  middle  thyroid  vein  passes  out  from  the  capsule  of  the  thyroid  gland 


628  THE  VEINS 

near  the  lower  part  of  the  lateral  lol)e  of  that  body,  crosses  the  common  carotid 
ohliquelv  downwards  and  outwards,  and  opens  into  the  internal  jugular  vein  a 
little  below  the  cricoid  cartilagi\ 

The  Inferior  Thyroid  Veins 

The  inferior  thyroid  veins  descend  from  the  lower  part  of  the  thyroid  body 
obliquely  outwards  to  the  innominate  veins.  The  right  vein  crosses  the  innom- 
inate artery  just  before  its  bifurcation,  and  ends  in  the  right  innominate  vein 
a  little  above  the  superior  vena  cava.  It  receives  inferior  laryngeal  veins  and 
veins  from  the  trachea,  and  has  valves  at  its  termination  in  the  innominate. 
The  left  vein  passes  obliquely  over  the  trachea  behind  the  sterno-thyroid  muscle, 
and  opens  into  the  left  innominate  vein.  It  also  receives  laryngeal  and  tracheal 
veins,  and  is  guarded  l:)y  valves  where  it  opens  into  the  innominate  trunk. 
The  inferior  thyroid  veins  communicate  across  the  trachea  by  transverse  branches. 
Not  unfrequently  the  inferior  thyroid  veins  (right  and  left)  unite  to  form  a  single 
trunk  which  joins  the  left  innominate  vein. 

The  Vertebral  Veins 

The  vertebral  vein  (fig.  342)  does  not  accompany  the  vertebral  artery  in  its 
fourth  stage,  that  is,  within  the  skull,  but  begins  as  a  plexus  of  small  veins  in  the 
suboccipital  triangle.  It  then  enters  the  foramen  in  the  transverse  process  of  the 
atlas,  and  passes  with  the  vertel^ral  artery  through  the  foramina  in  the  transverse 
processes  of  the  cervical  vertebrEe,  forming  a  plexus  around  the  artery.  On  leav- 
ing the  transverse  process  of  the  sixth  cervical  vertebra  it  crosses  in  front  of  the 
subclavian  artery  and  opens  into  the  innominate  vein.  It  has  one  or  two  semi- 
lunar valves  at  its  entrance  into  the  innominate  vein.  In  the  suboccipital  triangle 
it  communicates  with  the  intraspinal,  deep  cervical,  and  occipital  veins,  and  is 
joined  by  veins  from  the  recti  and  oljlique  muscles  and  the  pericranium.  Tribu- 
taries.— As  it  passes  down  the  neck  it  receives  (1)  lateral  spinal  veins,  which 
issue  along  with  the  cervical  nerves  and  lateral  spinal  arteries  from  the  spinal 
canal;  (2)  branches  from  the  venous  plexus  about  the  bodies  of  the  cervical  verte- 
brae and  their  transverse  processes;  (3)  branches  from  the  deep  cervical  muscles: 
and  (4)  branches  from  the  cervical  dorsal  spinal  veins.  Just  before  it  terminates 
in  the  innominate  it  is  joined  by  (5)  the  deep  cervical  vein  (sometimes);  (6)  the 
anterior  vertebral  vein;  and  (7)  the  upper  superior  intercostal  vein  (sometimes). 

The  anterior  vertebral  vein  begins  in  a  plexus  in  front  of  the  bodies  of  the 
cervical  vertebri:e,  and,  running  downwards  with  the  ascending  cervical  artery 
between  the  scalenus  anticus  and  longus  colli  muscles,  opens  into  the  vertebral  vein 
just  before  the  latter  ends  in  the  innominate.  It  receives  tributaries  from  the 
scaleni,  longus  colli,  and  rectus  capitis  anticus  muscles. 

The  deep  cervical  vein,  which  is  really  a  part  of  the  posterior  superficial  vein 
of  the  scalp,  is  described  with  that  vein  (page  614). 


3.    THE  SPINAL   VEINS 


The  spinal  veins,  which  form  plexuses  around  and  within  the  spinal  canal  from 
the  cranium  to  the  sacrum,  may  be  divided  into  the  extra-  and  intraspinal  veins. 
The  extraspinal  form  a  plexus  both  in  front  of  the  bodies  of  the  vertebrae  (the 
anterior  spinal  plexus),  and  in  tlie  sidnal  groove  between  the  transverse  and 
s]»inous  ))rocesscs — the  dorsal  plexus,  or  dorsal  spinal  plexus  as  it  is  often 
called.     The  intraspinal  veins,  or  those  within  the  spinal  canal,  may  be  divided 


4 


SPINAL 


629 


into  the  meningeal  and  the  medullary.  The  meningeal  form  an  anterior  and  a 
])(>sterior  spinal  plexus  between  tlic  (hira  mater  and  the  walls  of  the  s])inal  canal, 
and  are  generally  known  as  the  meningo-rachidean  veins.  They  receive  the  veins 
from  the  bodies  of  the  vertebrse.  The  medullary  set  are  situated  within  the  dura 
mater;  they  return  the  l)lood  from  the  S])inal  cord,  and  are  kncjwn  as  the  mcdulli- 
spinal  veins. 

1.  The  extraspinal  veins. — (a)  The  veins  of  the  anterior  spinal  plexus 
ramify  in  front  of  the  bodies  of  the  vertebra?.  They  are  of  small  size  and  most 
distinct  in  the  cervical  region  (fig.  890).      They  open  into  the  neigh})ourmg  veins. 

(h)  The  veins  of  the  posterior  spinal  or  dorsal  spinal  plexus  are  situated 
around  the  spinous  processes,  the  laminse,  and  the  articular  and  transverse  ])r()- 
cesses  of  the  verteljroe,  the  larger  veins  of  the  plexus  running  horizontally  forwards 
along  the  interspinous  ligaments.  The  plexus  is  formed  chiefly  by  the  union  of 
tributaries  proceeding  from  the  integuments  of  the  back  and  the  spinal  muscles. 

Fig.  390.— The  Spixal  Veins. 


ACCESSORY  PRO- 
CESS  OR  TIP 
OF  THE  TRUE 
TRANSVERSE 
PROCESS 

COSTAL  ELEM 

Posterwr  traiisrerse 

branch 


Vein  from  cord 
Transverse  branch 


A  iilerior  transverse 
rein 


Lumbar  vein 


Dorsal  spinal  pleitis 


Branch 
jiKrJoraling 
ligamenla 
subjiara 
Posterior  longitudinal 

spinal  vein 
Lateral  transverse 

branch 
A  nterior    longitudin  al 
spinal   vein   seen  in 
section 
Vdn.i  from  body  of 
vertebra 


Anli-rior  spinal  plexus 


C'onnnunications  take  place  between  the  veins  of  each  vertebral  segment  by  vertical 
t)ranches  running  upwards  and  downwards  to  the  })lexus  above  and  below  respec- 
tively near  tlie  base  of  the  transverse  ])roces.ses.  Branches  are  also  sent  through 
the  ligamenta  suV)flava  between  the  laminie  of  the  several  vertebra*  to  the  posterior 
plexus  of  the  intrasjdnal  veins,  and  also  forwards  l)etween  tlie  transverse  processes 
of  the  vertebrie  to  join  the  vertebral  vein  in  the  neck,  the  dorsal  branch  of  the 
intercostal  veins  in  the  thorax,  the  lumV)ar  veins  in  the  lumbar  region,  and  the 
lateral  sacral  veins  in  the  sacral  region. 

2.  The  intraspinal  veins  are  divided  into  (a)  the  meningeal;  and  (h)  the 
medullary,  or  meduUi-spinal. 

{'I)  The  meningeal  extra-medullary  or  meningo-rachidian  veins  lie  in 
the  fatty  tissue  between  the  walls  of  tlie  verteliral  canal  and  the  dura  mater  or 
theca  vertebralis.  They  are  arranged  in  four  longitudinal  channels,  two  of  which 
are  anterior  and  two  posterior,  united  by  transverse  branches  corresponding  in 
numlier  to  the  vertebral  segments  (fig.  390). 


630  THE  VK/XS 

The  anterior  longitudinal  spinal  veins  extend  from  the  foramen  magnum  to 
the  coccyx  as  two  tortuous  })lcxiform  vest^els,  one  being  placed  on  each  side  of  the 
liack  of  the  boches  of  the  vertelirte  behind  the  posterior  common  hgament.  Oppo- 
site the  body  of  each  vertebra  they  connnunicate  V)y  a  transverse  Ijranch,  which 
passes  between  the  body  of  the  vertebra  and  posterior  eonnnon  Hgaiiient,  an 
arrangement  which  is  sometimes  spoken  of  as  the  spinal  venous  ladder.  Each 
transverse  branch  as  it  lies  under  cover  of  the  posterior  common  ligament  receives 
the  veins  from  the  bodies  of  the  vertebrae  (the  venae  basis  vertebrae).  At  the 
spot  where  each  longitudinal  vein  is  joined  by  the  transverse  l>ranch,  the  vessel 
becomes  considerably  dilated.  From  the  longitudinal  vein  branches  run  backwards 
to  join  the  posterior  longitudinal  veins,  and  op})osite  the  intervertebral  foramina  a 
transverse  branch  runs  outwards  to  join  the  vertebral  vein,  the  intercostal  veins,  the 
lumbar  veins,  and  the  sacral  veins,  according  to  the  region  of  the  si)ine  in  ^\•llich 
the  vertebra  is  situated.  Above,  the  anterior  spinal  veins  communicate  with  the 
l)asilar  plexus  at  the  front  of  tlie  foraim-n  magnum. 

The  posterior  longitudinal  spinal  veins,  smaller  tlian  the  anterior  longitudinal 
veins,  likewise  extend  from  the  cranium  to  the  coccyx.  They  lie  between  the  pos- 
terior wall  of  the  spinal  canal  and  the  dura  mater.  Like  the  anterior,  they  commu- 
nicate by  transverse  branches,  which  receive  veins  through  the  ligamenta  subflava 
from  the  dorsal  spinal  plexus.  They  also  communicate  with  the  anterior  longi- 
tudinal veins  by  lateral  transverse  branches. 

It  will  be  thus  seen  (fig.  390)  that  in  the  interior  of  the  vertebral  canal,  opposite 
each  vertebral  segment,  there  is  a  venous  ring  between  the  bony  wall  of  the  canal 
and  the  sheath  of  the  dura  mater,  the  ring  being  formed  in  front  by  the  anterior 
transverse  vein;  on  each  side  by  the  dilated  portion  of  the  trunk  of  the  anterior 
longitudinal  spinal  vein,  and  the  lateral  transverse  lu-anch;  and  behind,  by  the 
trunk  of  the  posterior  longitudinal  vein  and  the  posterior  transverse  branch.  This 
venous  ring  receives  veins  from  the  body  of  the  vertebra,  from  the  spinal  cord,  and 
from  the  meninges,  and  pours  its  blood,  in  part  through  the  lateral  veins  lying  in 
the  intervertebral  foramina  into  the  vertebral,  intercostal,  lumliar,  or  sacral  veins; 
and  in  part  through  the  branch  which  perforates  the  ligamenta  subflava  into  the 
dorsal  spinal  plexus.  Above,  the  posterior  longitudinal  veins  connnunicate  at  the 
back  of  the  foramen  magnum  with  the  occipital  sinuses.  Around  the  foramen 
magnum  a  distinct  venous  ring  or  plexus  is  formed  l)y  the  connnunication 
between  the  occipital  and  marginal  sinuses  and  the  posterior  and  anterior  spinal 
veins. 

(6)  The  medullary  or  medulli-spinal  veins,  or  veins  of  the  spinal  cord,  are 
of  small  size,  and  run  in  the  pia  mater  in  a  tortuous  course  along  the  spinal  cord. 
They  join  the  venous  ring  corresponding  to  each  vertebral  segment  by  passing  along 
the  sheath  of  dura  mater  reflected  round  the  spinal  nerves. 


4.  THE  VEIXS  OF  THE  ABDOMEN  AND  PELVIS 

All  the  veins  of  the  al)domen  and  pelvis — Avith  the  exception  of  the  superior 
epigastric  vein  and  ascending  lum])ar  vein,  which  open  ultimately  into  the  su})erior 
vena  cava — enter  directly  or  indirectly  into  the  inferior  vena  cava.  The  veins 
corres])onding  to  the  parietal  branches  of  the  abdominal  aorta,  except  the  middle 
sacral  vein,  open  directly  into  the  inferior  vena  cava;  the  middle  sacral  vein  only 
indirectly  through  the  left  common  iliac  vein.  Of  the  visceral  veins  corres]ionding 
to  the  visceral  branches  of  the  abdominal  aorta,  those  which  return  the  blood  from 
the  stomach,  intestines,  and  pancreas  (the  chylopoetic  viscera),  and  from  the 
spleen,  end  in  a  common  trunk  (the  portal  vein).  The  portal  vein  enters  tlie 
liver,  and  breaks  up  in  the  liver  substance  into  cai)illaries  like  an  artery,  and  from 


IXFERIOR   VEXA   CAVA  631 

these  capillaries  arise  the  licpatic  veins  Avliicli  open  into  the  inferior  vena  cava  as 
that  vessel  grooves  the  under  surface  of  the  liver. 

Of  the  other  visceral  veins,  both  renals,  the  right  capsular,  and  the  right 
spermatic  or  ovarian  open  directly  into  the  inferior  vena  cava;  whilst  the  left 
capsular  and  left  spermatic  or  ovarian  only  join  that  vessel  indirectly  through  the 
left  renal. 

Two  of  the  superficial  veins  of  the  lower  })art  of  the  anterior  abdominal  wall, 
the  superficial  epigastric  and  superficial  circumflex  iliac,  enter  the  long  saphenous 
vein;  and  two  of  the  deep  veins  from  the  like  situation,  the  deep  epigastric  and 
deep  circumflex  iliac,  enter  the  external  iliac  vein.  The  blood  in  these  vessels, 
however,  can  flow  upwards  as  well  as  in  the  normally  downward  direction.  In 
obstruction  of  the  inferior  vena  cava  they  become  greatly  enlarged,  and  form,  with 
tlie  superior  epigastric  vein  and  witli  other  superficial  veins  of  the  thorax  with  which 
they  anastomose,  one  of  the  chief  (channels  for  the  return  of  the  ])lood  from  the 
lower  limbs. 

The  veins  of  the  pelvis,  which  receive  the  veins  from  tiie  perin;eum  and  gluteal 
regit)n,  join  the  internal  iliac  vein. 


THE  IXFERIOR  VEXA  CAVA 

The  inferior  or  ascending  vena  cava  (fig.  391  )  is  the  large  vessel  which 
returns  the  blood  from  the  lower  extremities  and  the  abdomen  and  pelvis.  It  is 
formed  by  the  confluence  of  the  right  and  left  connuon  iliac  veins  oj)})osite  the  body 
of  the  fifth  lumbar  vertebra,  ascends  in  front  of  the  lumbar  verteln'ie  to  the  right 
of  the  abdominal  aorta,  passes  through  the  caval  opening  in  the  diaphragm,  and 
ends  in  the  lower  and  back  part  of  the  right  auricle  of  the  heart  on  a  level  with 
the  lower  border  of  the  ninth  thoracic  verteljra.  At  its  origin  it  lies  behind  the 
right  common  iliac  arter}''  on  a  plane  posterior  to  the  aorta,  but  as  it  ascends  it 
])asses  slightly  forward  and  to  the  right,  getting  on  a  plane  anterior  to  the  aorta, 
and  Ijecoming  separated  from  that  artery  by  the  right  crus  of  the  diaphragm  and 
the  lobulus  Spigelii  of  the  liver.  Whilst  in  contact  with  the  liver  it  lies  in  a  deep 
groove  on  the  hinder  surface  of  that  organ,  the  groove  being  often  converted  into  a 
distinct  canal  by  a  thin  portion  of  the  hepatic  substance  bridging  across  the  groove. 
-Vs  it  passes  through  the  diaphragm  its  Avails  are  attached  to  the  tendinous  margins 
of  the  caval  opening,  and  are  thus  held  apart  when  the  muscle  contracts.  On  the 
thoracic  side  of  the  diaphragm  it  lies  for  about  half  an  inch  within  the  pericar- 
dium, the  serous  layer  of  that  membrane  l)eing  reflected  over  it. 

Relations. — In  front  it  is  covered  by  the  peritoneum,  and  crossed  l)y  the  right 
spermatic  artery,  branches  of  the  aortic  plexus  of  the  sympathetic,  the  transverse 
colon,  the  root  of  the  mesentery,  the  duodenum,  the  head  of  the  pancreas,  the 
portal  vein,  and  the  liver.  The  median  group  of  the  luml)ar  lymphatic  glands  are 
also  in  front  of  it  below,  and  at  its  connnencement  the  right  connuon  iliac  artery 
rests  U])on  it. 

Behind,  it  lies  on  the  luml)ar  verteljrie,  the  right  lumbar  arteries,  the  right 
renal  artery,  the  right  semilunar  ganglion,  and  the  right  crus  of  the  diaphragm. 

To  the  right  are  the  peritoneum,  liver,  and  psoas  muscle. 

To  the  left  is  the  aorta,  and  higher  up  the  right  crus  of  tlie  diaphragm. 

Tributaries. — The  inferior  vena  cava  receives  the  following  veins: — (1)  the 
renal  veins:  (2)  the  right  suprarenal  vein;  (3)  the  right  s])ermatic  or  (4)  the  right 
ovarian  vein;  (5)  the  lumbar  veins;  (6)  the  inferior  i)hrenic  veins;  (7)  the 
he])atic  veins;  and  (S)  the  right  and  left  common  iliac  veins. 

(1)  The  renal  or  emulgent  veins  r(>turn  the  blood  from  the  kidneys.  They 
are  short  but  thick  trunks,  and  oiien  into  the  vena  cava  nearly  at  right  angles  to 
that  vessel.  The  vein  on  the  left  side,  like  the  kidney,  is  a  little  higher  than  on 
the  right,  and  is  also  longer,  in  consequence  of  its  having  to  cross  tlie  aorta.  The 
comparative  shortness  of  the  right  renal  vein  should  be  borne  in  mind  in  the 
operation  of  nephrectomy,  since,  if  too  much  traction  is  made  on  the  ])edicle,  not 
only  the  vein,  but  a  portion  of  the  vena  cava  may  be  drawii  into  the  ligature,  as 
shown  in  a  specimen  in  J>t.  Bartholomew's  Hospital  Museum.      Each  vein  lies  in 


632 


THE  VELXS 


front  of  its  corresponding  artery.  The  left  vein  crosses  in  front  of  the  aorta,  just 
below  the  origin  of  the  superior  mesenteric  artery.  It  is  covered  by  the  third 
portion  of  the  duodenum,  and  receives  the  left  spermatic,  or  the  left  ovarian  in  the 
female,  and  usually  the  left  suprarenal,  and  sometimes  the  left  phrenic.  There  are 
rudiments  of  valves  in  each  vein  where  it  joins  the  vena  cava.  Those  on  the  right 
side,  however,  are  less  well  marked. 

(2)  The  suprarenal  veins. — There  is  usually  only  one  suprarenal  vein  on  each 
side  to  return  the  l»lood  In-ought  to  the  su2)rarenal  body  by  the  three  suprarenal 
arteries.  On  the  right  side  tlie  vein  opens  into  the  vena  cava  direct  a])ove  the 
opening  of  the  right  renal  vein.     On  the  left  side,  it  opens  into  the  left  renal. 

Fig.  391. — The  Abdominal  Aorta  and  Ixfekiok  Vexa  Cava. 


Cystic  artery 

HEPATIC  DUCT 

CYSTIC  DUCT 

COMMON  DUCT 

Portal  vein 

Gastro-dumlenal  In:  — 

Superior  pyloric  lir.  — 

Hepatic  art'  / ;/  — 

Right  xuprarenat  r 
Inferior  suprun 
artery 
lienal  art: 

Benal  r 
Inferior  vena 


Right  spermatic  rein 


Right  spermatic  artery 

Quadratus  lumborum 

muscle 

Right  !u7nbar  artery  and 

left  lumbar  vein 

Ureteric  branch  of 

spermatic  artei~y 


yiidille  sacral  vessels 


LEFT  LOBE  OF  LIVER 

(ESOPHAGUS 

Left  phrenic  artery 

Right  phrenic  artery 
Superior  suprarenal 
Gastric  artery 
Inferior  suprarenal 
Splenic  artery 

Left  phrenic  vein 
-5=7-r —    Left  suprarenal  vein 
Superior  mesenteric 
artery 

KIDNEY 

Ureteric  branch  of  renal 
Left  spermatic  vein 


Left  spermatic  artery 


Inferior  mesenteric  artery 

i)n|iiii..,'i  n Ureteric  branch  of 

'Inill'lll'  I  I  I  spermatic 


Ureteric  branch  of 

common  iliac 
Common  iliac  artery 


External  iliac  artery 
Internal  iliac  artery 


(3)  The  spermatic  veins  return  the  blood  from  the  testicle.  They  begin  by 
the  confluence  of  small  branches  from  the  body  of  the  testicle  and  epididymis,  and 
as  they  proceed  uj)  the  s})ermatic  cord,  in  front  of  the  spermatic  artiuy  and  ^'as 
deferens,  become  dilated  and  plexiform,  constituting  tbe  so-called  pampiniform 
plexus.  After  passing  through  the  external  alxlominal  ring,  the  inguinal  canal, 
and  the  internal  alxlominal  ring,  the  plexus  merges  into  two  veins,  Avbich  lie  one 
on  each  side  of  the  s})ermatic  artery.  Along  with  the  artery  the  veins  pass  uj) 
beneath  the  peritoneum,  and  on  the  left  side  also  beneath  the  sigmoid  flexure  of 
the  colon,  across  the  psoas  muscle  and  ureter,  to  end  as  a  single  trunk,  on  the 
right  side  in  the  inferior  vena  cava,  and  on  the  left  side  in  the  left  renal  vein. 
There  are  commonly  a  numl)er  of  imperfect  valves  in  the  spermatic  plexus  and  a 


TRIBUTARIES  OF  THE  INFERIOR   VEXA   CAVA  633 

perfect  pair  at  the  termination  of  each  spermatic  vein.      On  the  left  ^ide.  hov/ever, 
the  terminal  valve  may  l»e  wanting. 

(4)  The  ovarian  veins  hegin  as  the  panii»inif<)rm  ])lexus  near  tlie  (tvarv, 
between  the  layers  of  the  broad  ligament.  This  i)lexiis  communicates  freely  Avith 
the  uterine  plexus  of  veins,  and  with  the  plexus  of  veins  which  extends  from  the 
hilum  of  the  ovary  into  the  ovarian  ligament  (the  ovarian  bulb).  After  passing 
from  between  the  layers  of  the  broad  ligament,  the  plexus  unites  to  form  at  first 
two  and  then  a  single  vessel,  which  accompanies  the  ovarian  artery,  following  a 
similar  course  to  the  spermatic  veins  in  the  male.  The  right  ovarian  vein  opens 
into  the  inferior  vena  cava;  the  left  into  the  left  renal.  They  usually  contain 
imperfect  valves  in  their  i)lexiform  part,  and  a  perfect  valve  where  they  join  the 
vena  cava  and  renal  vein  respectively. 

(5)  The  lumbar  veins. — There  are  usually  fovn-  lumbar  veins  on  each  side 
corresponding  to  the  lumbar  arteries.  The  main  trunks  of  these  veins,  which  lie 
beside  the  bodies  of  the  lumbar  vertebrae,  are  formed  by  the  union  beneath  the 
psoas  of  anterior  and  posterior  branches.  The  anterior  branches  collect  the 
blood  from  the  front  and  lateral  walls  of  the  abdomen.  They  conmnmicate  in 
front  with  the  internal  manmiary  and  epigastric  veins,  and  then  run  backwards 
Ijetween  the  alxlominal  muscles  in  company  with  the  anterior  branches  of  the  luml)ar 
arteries  to  their  confluence  with  the  posterior  branches.  The  posterior  branches 
collect  the  blood  from  the  loins  and  muscles  of  the  back,  and  correspond  to  the 
]>osterior  or  dorsal  division  of  the  lumbar  arteries.  They  receive  connnuni- 
cating  branches  from  the  dorsal  spinal  plexus  and  from  the  verteVjral  canal,  and 
pass  forwards  between  the  transverse  processes  to  join  the  anterior  branches.  The 
trunk  lumbar  veins  are  connected  beneath  the  psoas  muscle  by  vertical  l)ranches, 
which  cross  in  front  of  the  transverse  processes.  The  last  lumbar  vein  is  variously 
joined  below  b}^  a  vertical  branch  to  the  common  iliac,  internal  iliac,  lateral  sacral 
or  ilio-lumbar  vein,  and  the  first  lumbar  vein  is  similarly  connected  al)Ove  with  the 
connnencement  of  the  vena  azygos  major  on  the  right,  and  the  vena  azygos  minor 
on  the  left  side.  The  vertical  vein  thus  formed  is  known  as  the  ascending  lumbar 
vein,  and  is  regarded  by  some  morphologists  as  the  remains  of  the  primitive  or 
cardinal  vein  of  the  emI)rvo.  The  trunk  lum])ar  veins  run  uj)  ])eneath  the  tendin- 
ous arches  of  the  })soas  on  the  sides  of  the  bodies  of  tlie  vertebra?  in  company  with 
the  lumbar  arteries  and  branches  of  the  sympathetic  nerve,  and  end  in  the  inferior 
vena  cava  on  its  posterior  aspect.  The  left  veins  are  longer  than  the  right,  and 
pass  behind  the  aorta. 

(G)  The  phrenic  veins,  or  inferior  phrenic  veins  as  they  are  sometimes 
called,  follow  the  course  of  the  phrenic  arteries:  the  right  opens  into  the  vena  cava 
direct;  the  left  into  the  suprarenal,  the  left  renal,  or  tlie  vena  cava. 

(7)  The  hepatic  veins,  the  largest  tributaries  of  the  vena  cava,  return  the 
Itlood  from  the  liver.  C'onnneneing  in  the  substance  of  the  liver  (see  Liver),  they 
converge  as  they  approach  its  posterior  surface,  and  unite  to  form  two  or  three 
large  branches,  which  open  into  the  vena  cava  as  it  lies  in  the  groove  or  canal  in 
that  organ.  Some  smaller  vessels  from  the  lobulus  8i)igelii,  and  other  parts  of  the 
liver  in  the  neighbourhood  of  the  caval  groove,  open  directly  into  the  vena  cava. 
The  hepatic  veins  contain  no  valves,  but,  in  consequence  of  those  from  the  riglit 
and  left  lobe  of  the  liver  opening  obli(iuely  into  the  vena  cava,  ])resent  a  .semilunar 
fold  at  the  lower  margins  of  their  orifices. 

Chief    V(iri(it'n>ti^   in    tJie  Inferior    ]'eii(i    Ctira 

(1)  The  inferior  vena  cava,  in  oases  of  transpo-sition  of  tlu'  viscera,  may  lie  on  the  left  siile 
of  the  aorta.  (2)  Without  tninsi>osition  it  may  also  lie  to  the  left  of  the  aorta,  emssinir  to  the 
riirht  to  .irain  the  eaval  oi)eniiiir  immediately  below  the  (]iaiihra,i:in,  or  after  receivin.ir  the  leit  renal 
vein.  (H)  It  may  he  doulile.  the  left  cava  tlien  usually  passinir  across  tlie  aorta  into  the  riuht 
after  receivinii  the  left  renal  vein.  A  commuiiieation  lictweeii  the  right  and  left  veins  in  the  ])osi- 
tion  of  the  normal  left  eominoii  iliac  vein  may  or  may  not  then  exist.  (4)  The  inferior  vena  cava 
may  be  absent,  the  blood  from  the  lower  extremities  passing  by  a  large  vein  in  the  position  of  the 
ascending  lumbar  and  azygos  veins  throuah  the  diai>hrai:m  to  open  into  the  suiierior  vena  cava. 
The  hepatic  veins  then  "open  directly  into  the  right  auricle  thmugli  the  normal  eaval  opening 
in  the  diajihragm.  (.'))  The  inferior  vena  cava  may  receive  the  left  si.ermatie  vein,  (t.)  Tt  may 
receive  a  left  accessory  renal  vein  i)assing  behind  the  aorta,  and  into  this  the  usual  tributaries 


634  THE  VEINS 

ut'  the  left  renal  vein  may  ojien.  (7)  It  may  receive  .several  accessory  renal  veins ;  as  many  as 
seven  on  each  side  have  been  met  with.  (8)  The  lumbar  veins  may  enter  it  on  one  or  both  sides 
as  a  common  trunk. 

(8)  THE  COMMON  ILIAC  VEINS 

The  common  iliac  veins  :ire  formed  opposite  the  sacro-iliac  synehondrosis  by 
tlie  eontluenee  oi  the  external  iliac  and  internal  iliac  vein.<.  They  converge  as  they 
ascend,  and  unite  opposite  the  upper  border  of  the  tilth  lumbar  verteljra  to  form 
the  vena  cava  inferior  a  little  to  the  right  of  the  median  line. 

The  right  vein,  shorter  and  more  vertical  in  direction  than  the  left,  passes 
obliquely  liehind  the  right  common  iliac  artery  to  its  outer  side,  where  it  is  joined 
by  the  left  common  iliac  vein. 

The  left  vein  lies  to  the  inner  side  of  the  left  common  iliac  artery,  and,  after 
crossing  in  front  of  the  promontory  of  the  sacrum  and  fifth  lumlxir  vertebra  below 
the  bifurcation  of  the  aorta,  passes  beneath  the  right  comnKju  iliac  artery  to  join 
the  right  vein  and  form  the  inferior  vena  cava.  The  left  vein  may  contain  an 
imperfect  valve. 

Tributaries, — Tlie  ilio-lumbar  veins  may  enter  the  lower  })art  of  the  common 
iliac,  or  open  into  the  internal  iliac  vein.  The  left  vein  receives  the  middle  sacral 
veins. 

(a)  The  ilio-lumbar  veins  follow  the  course  of  the  ilio-lumbar  artery,  and  end 
either  in  the  connnon  iliac  or  in  the  internal  iliac  vein. 

(h)  The  middle  sacral  veins  ascend  on  either  side  of  the  middle  sacral  artery 
in  front  of  the  sacrum,  to  o})cn  usually  by  a  single  trunk  into  the  left  common  iliac 
vein.  They  connnunicate  with  the  lateral  sacral  veins,  forming  the  so-called  pre- 
sacral plexus.  Below,  the  middle  sacral  veins  communicate  with  the  ha?morrhoidal 
veins. 

CJdef  Variations  in  the  Common  Iliac   Veins 

(1)  Either  common  iliac  vein  maybe  double,  or  double  only  for  a  portion  of  its  extent. 
(2)  One  may  be  absent, — the  external  and  internal  iliac  veins  joining  the  opposite  common  iliac  to 
form  the  vena  cava.  (3)  The  right  and  left  internal  iliac  veins  may  unite  and  open  as  a  common 
trunk  at  the  confluence  of  tlie  right  and  left  external  iliac  veins  to  form  the  vena  cava.  (4)  The 
middle  sacral  ti-unk  vein  may  divide,  and  one  branch  open  into  the  right,  and  the  other  into  the 
left  common  iliac  vein. 


THE  PORTAL  VEIN  AND  ITS  TRIBUTARIES 

The  veins  corresponding  to  the  inferior  mesenteric,  the  superior  mesenteric,  and 
the  branches  of  the  cn^liac  artery,  with  the  exception  of  'the  terminal  branches  of 
the  hepatic  artery,  do  not  join  the  inferior  vena  cava  direct,  but  unite  to  form  a 
common  trunk — the  portal  vein. 

This  vein  enters  the  liver,  and  breaks  up  in  its  substance  into  cajjillaries  like  an 
artery,  from  which  the  lilood  is  again  ultimately  collected  by  the  hepatic  veins, 
and  carried  by  them  into  the  inferior  vena  cava.  The  terminal  branches  of  the 
hepatic  artery  also  break  up  in  the  liver  into  capillaries,  and  from  them  the  blood 
likewise  finds  its  way  finally  into  the  hepatic  veins,  and  thence  into  the  inferior 
vena  cava.  Thus  the  arterial  blood,  leaving  the  aorta  for  the  su]>ply  of  the  stom- 
ach, the  intestines,  the  pancreas  (the  so-called  chylopoetic  viscera),  and  the  spleen, 
passes,  before  it  reaches  the  vena  cava,  through  two  sets  of  ca])illaries:  viz.  the 
cajjillaries  of  the  viscera  and  the  capillaries  of  the  liver.  Hence  the  portal  system 
of  veins  may  be  said  to  terminate  in  capillaries  at  each  end;  to  begin,  like  other 
veins,  in  capillaries  in  the  viscera;  but,  unlike  other  veins,  to  end  in  ca})illarieslike 
an  artery,  instead  of  in  a  larger  and  larger  vein  till  the  auricle  is  reached.  The 
portal  vein  and  its  tributaries  have  no  valves. 

The  portal  vein  is  a  thick  trunk  about  three  inches  in  length  (7-8  cm.).  It 
is  formed  Iwhind  the  pancreas,  opposite  the  right  side  of  the  body  of  the  second 
lumbar  vertebra,  by  the  union  of  the  superior  mesenteric  with  the  splenic  vein. 
After  passing  behind  the  first  part  of  the  duodenum,  and  then  between  the  layers 


PORTAL 


635 


of  the  lesser  omentum  in  company  with  tlie  liepatic  artery  and  the  hepatic  duct,  it 
enters  the  transverse  or  i)ortal  Hssure  of  the  Hver,  and  there  divides  into  a  right  and 
a  left  l)ranch.  In  this  course  it  passes  upwards  and  to  the  right,  having  hoth  the 
he{)atic  artery  and  the  common  bile  duct  in  front,  the  former  to  the  left,  the  latter 
to  the  right.  It  is  surrounded  by  branches  of  the  hepatic  plexus  of  the  sym- 
l)athetic  nerve,  and  by  numerous  lymphatic  vessels  and  some  glands.  The  con- 
nective tissue  sheath  enclosing  these  structures  is  called  the  capsule  of  Glisson. 
Just  before  it  divides  it  is  somewhat  dilated,  the  dilated  portion  being  called  the 
sinus  of  the  portal  vein.  The  division  into  right  and  left  branches  taki-s  place 
towards  the  riizlit  end  of  the  transverse  fissure  of  the  liver.  The  right  branch  is 
shorter  and  thicker  than  the  left,  and  supplies  the  right  lobe  of   the  liver  and    a 


Fig.  392. — The  Veins  of  the  Stomach  and  the  Portal  Veix. 
(From  a  dissection  by  W.  J.  W;ilsham.) 


Cystic  vfhi 

Right  branch  of 
portal  IV in 

Portal  vein 

Hepatic  artery 

Continuation  of 

hepatic  artery 

Gnstro-iiiiodennl 

branch  of  hepatic 

artery 

Pyloric  win 


Right  gastro- 
epiploic vein 


Omental  reins 


Left  branch  of 
portal  rein 


Left  f/astro- 
'jii/jloic  rein 


branch  to  the  quadrate  lobe.  The  left  branch  is  longer  and  smaller  than  the  right, 
and  supplies  the  left  lobe,  and  gives  a  Itranch  to  the  Spigelian  and  (piadrate  lolies. 
It  is  joined,  as  it  crosses  the  longitudinal  fissure,  by  a  fil)rous  cord,  known  as  the 
round  ligament  of  the  liver  or  the  oliliterated  umbilical  vein,  and  ]>osteriorly  by  a 
second  fibrous  cord,  the  remains  of  the  ductus  venosus.  In  the  feetus  the  blood 
passes  through  the  umbilical  vein  and  ductus  venosus  directly  into  the  vena  cava, 
a  very  small  ([uantity  only  turning  to  the  right  and  left  into  the  brandies  of  the 
portal  vein.  Before  l)irth,  the  blood  in  that  part  of  the  left  branch  of  the  ])ortal 
vein  which  lies  between  the  trunk  of  the  vena  porta  and  the  umbilical  vein  travels 
from  left  to  right;  but  after  l)irth,  as  the  portal  circulation  l)ecomes  freely  esta- 
blislied  and  the  umbilical  vein  and  ductus  venosus  are  obhterated,  in  the  opposite 
direction,  i.e.  from  right  to  left. 


636 


THE  VEINS 


Tributaries. — The  pyloric,  the  gastric,  the  cystic  (which  latter  usually  enters 
the  right  Ijrancli),  the  superior  mesenteric,  and  the  splenic. 

The  pyloric  vein  hegins  near  the  pylorus  in  the  lesser  curve  of  the  stomach, 
and,  running  from  left  to  right  with  the  superior  pyloric  artery,  opens  directly  into 
the  lower  part  of  the  portal  vein.  It  receives  hranches  from  the  pancreas  and 
duodenum. 

Tlie  gastric  or  coronary  vein  runs  with  the  gastric  artery  at  first  from  right  to 
left,  along  the  lesser  curve  of  the  stomach,  towards  the  cardiac  end,  and  then,  turning 
to  the  right,  passes  across  the  spine  from  left  to  right  to  end  in  the  portal  trunk  a 
little  higher  than  tlie  pyloric  vein  (fig.  392).  At  the  cardiac  end  of  the  stomach  it 
receives  small  branches  from  the  oesophagus. 


Fig.  393. — The  Superior  Mesenteric  Veix. 
(The  colon  is  turned  up,  and  the  small  intestines  are  drawn  over  to  the  left  side.) 


Ileo-colic  artery 


VERMIFORM 
APPENDIX 


Lcjl  colic  artery 

Superior  mesen- 
teric artery  and 
rein 


Vasa  inlestini 
tenuis 


SMALL  INTESTINES 


The  cystic  vein  returns  the  blood  from  the  gall-l)ladder.  It  usually  opens  into 
the  right  l^ranch  of  the  j^ortal  vein. 

The  superior  mesenteric  vein  begins  in  trilnitaries  which  correspond  with  the 
branches  of  the  superior  mesenteric  artery.  It  courses  upwards  a  little,  in  front  and 
to  the  right  of  the  artery,  passing  wdth  that  vessel  from  between  the  layers  of  the 
mesentery  in  front  of  the  duodenum,  and  behind  the  pancreas,  where  it  joins  the 
splenic  vein  to  form  the  portal  trunk. 

Tributaries. — In  addition  to  the  tributaries  corresponding  to  the  branches  of 
the  superior  mesenteric  artery — viz.  the  ileo-colic.  right  colic,  middle  colic,  and 
small  intestinal  veins  (fig.  3*93) — it  receives  the  right  gastro-epiploic  and  the 
pancreatico-duodenal  veins  just  before  its  termination  in  the  portal  vein. 


PORTAL 


6.'}; 


The  right  gastro-epiploic  vein  accf»m))anies  the  artery  of  that  name.  It  runs 
from  left  to  right  along  the  greater  curvature  of  the  stoniach,  receiving  l>ranches 
from  the  anterior  and  posterior  surfaces  of  that  viscus,  and  from  the  great  omentum, 
and,  passing  hehind  the  first  portion  of  the  duodenum,  ends  in  the  superior  mesen- 
teric vein  just  Ijefore  that  vessel  joins  the  portal  trunk. 

The  pancreatico-duodenal  vein  runs  with  the  corresponding  arteries  hetween 
the  head  of  the  pancreas  and  the  second  portion  of  the  duodenum,  and  ends  in  the 
superior  mesenteric  vein  a  little  below  the  spot  where  that  vessel  is  joined  by  the 
right  gastr(  (-epiploic  vein. 

The  splenic  vein  issues  as  several  large  branches  from  the  hilum  of  the  spleen. 
These  soon  unite  to  foi-m  a  large  trunk,  which  passes  across  the  aorta  and  spine  in 
company  with  the  splenic  artery,  below  which  it  lies,  to  join  at  nearly  a  right  angle 


Fig.  394.— The  Inferior  Mesenteric  Vein. 
(The  colon  is  turned  up,  and  the  small  intestines  are  drawn  to  the  right  side. ) 


Miitille  colic  arleri/ 


Iiife.riof  pancreatico- 
duodenal arlery 
Huperior  mesenteric 
artery 
Riyht  colic  artery 


Abdominal  aor/n 
Vena  cava  infer !■ 


Right  common  iliac  . 

artery 

Middle  sacral  artery 

anil  rein 


Left  colic  artery 

Inferior  mesenteric 
vein 

Inferior  mesenteric 

artery 
Left  colic  artery 
Inferior  mesenteric 

artery 


Left  common  iliac 
rein 

Sigmoid  artery 


Superior  h(Fmor- 
rkoidal  artery 


the  superior  mesenteric  vein.  In  this  course  it  lies  behind  the  pancreas;  and  at  its 
union  with  the  superior  mesenteric  to  form  the  vena  porta,  in  front  of  the  inferior 
vena  cava. 

Tributaries. — It  receives  veins  corresponding  to  tlic  vasa  brevia  arteries  from 
the  cardiac  end  of  the  stomach,  the  left  gastro-epiploic  vein,  veins  from  tlie 
pancreas,  and  the  inferior  mesenteric  vein. 

The  left  gastro-epiploic  vein  accompanies  the  left  gastro-epiploic  artery.  It 
runs  from  riglit  to  left  along  the  greater  curvature  of  the  stomach,  receives  branches 
from  the  stomach  and  omentum,  and  o])ens  into  the  commencement  of  the  splenic 
vein. 

The  inferior  mesenteric  vein  begins  at  the  rectum  in  the  superior  and  middle 
hsemorrhoidal  veins.  It  passes  out  of  the  pelvis  with  the  inferior  mesenteric  artery; 
but,  after  receiving  the  veins  corresponding  with  the  sigmoid  and  left  colic  branches 


638  THE  VEINS 

of  that  vessel,  it  leaves  the  artery  and  runs  upwards  on  the  psoas  to  the  left  of  the 
aorta  and  behind  the  })eritoneuni.  On  ap})roaching  the  })anereas  it  turns  slightly 
inwards,  and  passes  obliquely  behind  that  gland  to  join  the  splenic  vein  just  before 
tlie  latter  unites  with  the  superior  mesenteric  to  form  the  vena  i)orta. 


THE  VEINS  OF  THE  PELVIS 

The  veins  of  the  pelvis,  with  the  exception  of  the  middle  sacral  vein,  which 
terminates  in  the  left  cunimon  iliac  vein,  open  into  the  internal  iliac  vein.  Under 
the  head  of  i)elvic  veins  are  included  all  of  those  corresponding  to  the  branches  of 
the  internal  iliac  artery  except  the  hypogastric  branch,  although  some  of  these  veins 
do  not  retin-n  the  lilood  from  the  pelvic  walls  or  viscera. 

The  internal  iliac  vein  is  formed  by  the  confluence  of  the  veins  (except  the 
uml)ilical)  corresponding  to  the  branches  of  the  internal  iliac  artery.  It  varies 
considerably  in  length,  but  is  usually  quite  a  short  trunk,  extending  from  the  upper 
part  of  the  great  sacro-sciatic  foramen  to  the  sacro-iliac  synchondrosis,  Avhere  it 
joins  the  external  iliac  to  form  the  common  iliac  vein.  It  lies  behind  and  a  little 
internal  to  the  internal  iliac  artery.      It  contains  no  valve. 

Tributaries. — The  internal  iliac  vein  receives  directly  or  indirectly  the  following 
brandies:  the  gluteal,  ilio-lumbar,  lateral  sacral,  obturator,  sciatic,  pudic,  dorsal 
penile.  }trustatic,  vesical,  and  ha?morrhoidal  veins.  The  single  umbilical  vein — the 
vein  corresponding  to  the  right  and  left  hypogastric  arteries  and  their  continuation, 
the  umbilical  arteries — does  not  enter  the  pelvis,  but,  leaving  the  umbilical  arteries 
at  the  navel,  passes  along  the  falciform  ligament  to  the  liver.  After  birth  it  is 
converted  into  a  fibrous  cord.      (See  Portal  Vein,  page  634. ) 

The  gluteal  veins  accompany  the  gluteal  artery,  and,  passing  through  the 
upper  part  of  the  great  sciatic  foramen,  open  into  the  internal  iliac  vein  near  its 
termination,  either  separately  or  as  a  single  trunk. 

The  ilio-lumbar  veins  open  into  the  internal  iliac  a  little  higher  than  the 
gluteal.     At  times  they  join  the  common  iliac  vein. 

The  lateral  sacral  veins  join  the  gluteal  or  the  internal  iliac  at  or  about  the 
same  situation  as  the  gluteal.  They  form  with  the  middle  sacral  veins  a  plexus  in 
front  (»f  the  sacrum,  and  receive  l:»ranches  from  the  sacral  canal. 

The  obturator  vein,  which  lies  below  the  obturator  artery  as  it  crosses  the  side 
of  the  pelvis,  opens  into  the  front  of  the  internal  iliac  vein  a  little  beloAV  the  gluteal. 
Its  branches  correspond  to  those  of  the  artery. 

The  sciatic  veins  accompany  the  sciatic  artery,  and,  as  a  rule,  unite  to  form  a 
single  trunk  liefore  joining  the  internal  iliac  a  little  below  tlie  ol)turator  vein. 

All  the  al)ove  veins  so  closely  follow  the  ramifications  of  their  respective 
arteries,  that  no  further  special  descri})tion  of  them  is  required.  They  all  contain 
valves. 

The  pudic  vein  doi's  not  begin  as  the  dorsal  vein  of  the  penis,  but  issues  from 
the  corjius  cavernosum  with  the  artery  of  that  body.  It  communicates,  however, 
with  tlie  dorsal  vein  before  the  latter  pierces  the  triangular  ligament.  In  the  rest 
of  its  course  it  runs  with  the  pudic  artery,  receiving  tributaries  corresi)onding 
to  the  branches  of  that  vessel.  It  terminates  in  the  lower  part  of  the  internal 
iliac  vein. 

The  dorsal  vein  of  the  penis  begins  in  a  ])lexus  around  the  corona  glandis, 
then  runs  along  the  centre  of  the  dorsum  of  the  penis  between  the  two  ]»udic 
arteries.  In  this  course  it  receives  large  trilmtaries  from  the  interior  of  the  organ, 
which,  emerging  for  the  most  part  between  the  cori)US  spongiosum  and  cor]nis 
cavernosinn.  wind  obliquely  over  the  outer  surface  of  the  latter  structure  to  the 
dorsiun  of  the  penis  to  end  in  the  dorsal  vein.  At  the  root  of  the  penis  the  dorsal 
vein  leaves  the  dorsal  arteries,  and,  passing  straight  backwards  between  the  two  layers 
of  the  suspensory  ligament,  and  then  through  either  the  sub])ubic  ligament  or  the 
upper  part  of  the  triangular  ligament  of  the  pelvis  (fig.  371)  bifurcates,  each 
branch  passing  backwards  and  downwards  to  the  prostatico-vesical  jilexus  of  veins. 
At  times  the  dorsal  vein  begins  as  two  branches,  which  nm  l)etween  the  dorsal 
arteries  and  onlv  unite  to  form  a  simple  tnnik  aliout  an  inch  and  a  half  from  the 


SUPERFICIAL  VEINS  OF  UPPER   EXTREMITY  639 

triangular  ligament.  Before  passing  through  the  trianguhir  ligament,  it  connnuiii- 
cates  on  each  side  witli  the  ]>rimarv  radicals  of  the  pudic  vein.  After  dividing  ii;t<i 
a  right  and  a  left  hrancli  within  the  pelvis,  each  vessel  generally  communicates  witli 
the  ol^turator  vein  by  a  branch  passing  over  the  ))ack  of  the  pubes  to  the  ol»turati>f 
foramen. 

The  prostatico-vesical  plexus  surrounds  the  prostate  and  the  neck  and  lowir 
fundus  of  the  bladder.  It  receives  in  front  the  right  and  left  divisions  of  the 
dorsal  vein  of  the  penis,  and  communicates  i)Osteriorly  with  the  ha-morrhoidal 
])lexus.  The  prostatic  veins  and  the  vesical  plexus  open  into  it.  The  veins 
forming  the  plexus  are  of  large  size,  especially  in  old  men,  in  whom  they  oftt  n 
become  varicose,  and  contain  phlel)oliths,  or  vein-stones.  The  jdexus  is  surroundeil 
by  a  kind  of  ca])sule  formed  by  the  i-ecto-vesical  process  of  the  pelvic  fascia.  It 
terminates  in  a  single  stem  on  each  side  which  opens  into  the  internal  iliac  vein. 

The  vesical  plexus  surrounds  the  upper  fundus,  the  sides,  and  the  anterior  and 
posterior  surfaces  of  the  Idadder.  It  is  situated  between  the  muscular  coat  and  the 
peritoneum,  and  where  the  bladder  is  uncovered  by  peritoneum  external  to  the 
nuiscular  coat  in  the  pelvic  cellular  tissue.  It  opens  into  the  jirostatico-vesical 
plexus. 

The  haemorrhoidal  plexus  of  veins  surrounds  the  rectum,  and  is  situated  at 
the  lower  part  of  that  tul)e  between  the  muscular  and  mucous  coats.  The  veins  of 
this  ])lexus  terminate  in  the  inferior,  middle,  and  superior  haemorrhoidal  veins. 
The  inferior  join  the  pudic;  the  middle  accompany  tlie  middle  hannorrhoidal 
arteries,  and  open  into  tlie  internal  iliac  and  su])erior  ha?morrhoidal  veins;  the 
superior  form  the  commencement  of  the  inferior  mesenteric  vein,  and  through  this 
the  l)lood  gains  the  portal  vein.  None  of  these  veins  have  any  valves,  hence  the 
enlargement  of  the  inferior  haemorrhoidal  veins,  a  condition  known  as  piles,  when 
the  i)ortal  vein  is  obstructed,  as  from  compression  of  its  ca}nllaries  in  cirrhosis  of 
the  liver.  Through  the  ha?morrhoidal  veins  a  free  communication  is  established 
between  the  systemic  and  portal  system  of  veins. 


5.   TFFE  VEINS  OF  THE  UPPER  EXTREmTY 

The  veins  of  the  upper  limb  consist  of  two  sets — a  superficial  and  a  deep. 
The  sui)erficial  veins  ramify  in  the  subcutaneous  tissue  al)ove  the  dee])  fascia;  the 
deep  accompany  the  arteries,  and  have  practically  the  same  relations  as  those 
vessels.  The  superficial  and  deep  veins  commimicate  at  frequent  intervals  tln-oi;gh 
the  internuiscular  veins  which  run  l)etween  the  muscles  and  perforate  the  deep 
fascia.  Both  sets  of  veins  are  provided  ^vith  valves,  Init  the  valves  are  more 
numerous  in  the  deep  than  in  the  superficial.  Tliere  is  usually  a  valve  where  the 
deep  veins  join  the  su])erficial.  The  superficial  veins  are  larger  than  the  deej^.  and 
take  the  greater  sliarc  in  retin-ninif  the  blood. 


I.    THE  SUPER  Fir  lAL   VEIXS  OF  THE  UPPER  EXTREMITY 

The  superficial  veins  begin  in  two  irreguhir  venous  plexuses:  one  situated  on 
the  back  oi  the  hand,  and  the  other  on  the  front  of  the  wrist.  From  the  radial 
side  of  the  dorsal  plexus,  a  single  vein,  the  superficial  radial,  runs  u])  the  forearm 
as  far  as  the  ell)ow.  From  the  ulnar  side  of  the  plexus,  two  veins  course  up  the 
inner  side  of  the  forearm — the  anterior  and  posterior  superficial  ulnar  veins — 
and,  joining  together  a  little  l)elow  the  ))end  of  tiie  elbow,  form  a  single  superficial 
ulnar  vein.  From  tlie  anterior  ]»lexns  a  vein  runs  up  the  middle  of  the  tront  of 
the  forearm — the  superficial  median  vein — and.  after  receiving  a  branch  from  the 
deep  veins  at  the  bend  of   the  elbow  (tlic  deep  median),  divides  into  an  outer 


640 


THE  VEINS 


1  (ranch  (the  median  cephahc)  and  an  mner  branch  (tlie  median  basilic).  The 
median  cephalic  runs  upwards  and  outwards  to  join  the  superficial  radial  vein. 
The  united  trunk,  then  known  as  the  cephalic,  continues  u])  the  outer  side  of  the 
arm,  and  opens  into  the  axillary  vein.  The  median  basilic  runs  upwards  and 
inwards  to  join  the  superficial  ulnar  vein.  The  trunk  thus  formed  (the  basilic) 
courses  up  the  inner  side  of  the  arm  to  join  the  inner  brachial  vena  comes  and 
form  the  axillary  vein. 

The  dorsal  venous  plexus,  which  is  situated  on  the  back  of  the  hand,  some- 
times takes  the  form  of  an  irregular  arch,  stretching  across  from  the  radial  to  the 


Fig.  395.— The  Bend  of  the  Elbow  with  the  Siperficial  Veins,  Left  Side. 
(From  a  dissection  by  Dr.  Alder  Smith  in  the  Museum  of  St.  Bartholomew's  Hospital.) 


MEDIAN  NERVE 
Posterior  branch  of 
anastomotica  magna 
BRANCHES  OF      1 
INTERNAL  CUTA- 
NEOUS NERVE      I 


Posterior  ulnar  rein 

BrachialiB  amicus 

Anterior  branch  of 
anastoraotica  magna 
Anterior  ulnar  vein 

Median  basilic  rein 

MUSCULAR  BRANCH 
OF  MEDIAN  NER  VE 


Tendon  of  biceps 
Bicipital  fascia 

Sraciiialis  anticus 

Deep  median  vein 

Ulnar  arlerv 


Pronator  teres 


Biceps 

Internal  vena 
come*  of 
brachial  artery 
Basilic  vein 

Brachialis 
anticus 

Cephalic  rein 

Brachial  artery 
EXTERNAL 

CUTANEOUS 

NER  VE 
Mnsculo-spiral 
n.  and  ascending 
branch  of  radial 
reairrent  artery 
Radial  rein 
Median  cephalic 

rein 
Ascending  hr.  of 
radial  recurrent 
RADIAL 
NERVE 

Radial  recurrent 

artery 
Supinator 

longus 
Descending  br. 

of  radial 

recurren  t 
Median  vein 


RADIAL 
NERVE 


I 


ulnar  side;  at  other  times,  the  form  of  two  more  or  less  distinct  plexuses,  a  radial 
dorsal  and  an  ulnar  dorsal;  but  an  exactly  similar  arrangement  is  seldom  met  with 
in  any  two  consecutive  bodies. 

Th(^  distal  part  of  the  arch  or  ]>lexus  receives  the  digital  veins  from  the  fingers. 
These  digital  veins,  two  to  each  finger,  start  from  a  minute  plexus  about  the  nail, 
run  along  the  finger,  one  on  either  side,  to  the  cleft,  where  each  unites  with  the 
vein  from  the  contiguous  side  of  the  neighljouring  finger,  and  so  form  single  trunks 
Avhich  {)roceed  upwards  to  the  arch.  The  veins  of  the  iingers  communicate  at 
fre(|Uent  intervals  by  cross  branches  above  and  below  the  interi)halangeal  joints. 

Here  it  may  be  noted,  that  whilst  the  veins  wliich  return  the  chief  part  of  the 


SUPERFICIAL   VELXS  OF  UPPER   EXTREMITY  041 

blood  from  the  fingers  are  superficial  and  dorsally  placed,  the  arteries  are  deep  and 
situated  towards  the  palmar  surface.  Minute  venie  comites,  however,  lie  on  each 
Bide  of  the  digital  arteries. 

The  anterior  median  plexus  is  situated  on  the  fore  part  of  the  wrist.  It  is 
very  irregular  in  its  arraugeinent.  and  receives  a  few  small  l)ranches  from  the  palm 
and  from  the  nuter  ami  fiont  i»art  of  the  thumb. 

The  superficial  radial  vein  begins  at  the  radial  end  of  the  dorsal  venous 
])lexus  or  arch,  and,  after  receiving  veins  from  the  thumb  and  communicating  with 
the  deep  veins  accompanying  the  radial  artery,  courses  up  the  radial  side  of  the 
forearm  along  with  the  musculo-cutaneous  nerve.  It  receives  numerous  branches 
from  the  front  and  outer  surface  of  the  forearm,  and  a  little  above  the  bend  of  the 
ell>ow,  in  the  slight  sulcus  at  the  outer  side  of  the  bicipital  prominence,  unites  with 
tlie  median  ce})halie  vein  to  form  the  cephalic  vein  (figs.  395,  396).  It  contains 
from  four  to  six  valves. 

The  anterior  superficial  ulnar  vein  begins  on  the  inner  and  front  surface  of 
tlie  wrist,  runs  u])  the  inner  side  of  the  foreann,  and  joins  the  posterior  ulnar  vein 
just  below  the  bend  of  the  elbow;  or  it  may  unite  directly  with  the  median  basilic 
to  form  the  basilic  vein.  In  the  latter  case  the  posterior  superficial  ulnar  vein  joins 
the  basilic  (fig.  395).  The  anterior  ulnar  vein  is  accompanied  by  the  anterior 
branch  of  the  internal  cutaneous  ner^-e.      It  contains  about  four  valves. 

The  posterior  superficial  ulnar  vein,  larger  than  the  anterior,  begins  at  the 
'  ulnar  side  of  the  dorsal  plexus.  It  receives  the  vena  salvatella,  or  vein  of  the 
little  finger,  and  communicates  with  the  deep  ulnar  veins  by  means  of  an  inter- 
muscular branch  which  passes  beneath  the  abductor  minimi  digiti.  As  it  courses 
upwards  on  the  posterior  aspect  of  the  forearm  it  receives  numerous  cutaneous 
l)ranches,  and  near  the  bend  of  the  elbow  joins  the  anterior  superficial  ulnar  vein. 
Just  below  the  internal  condyle  the  united  trunk  turns  forwards  to  unite  with  the 
median  basilic  to  form  the  basilic  vein.  When  the  basilic  is  formed  by  the  union 
of  the  anterior  ulnar  and  median  basilic  (fig.  395),  the  posterior  ulnar  vein  may 
end  in  the  Viasilic  vein  direct.     It  contains  about  four  valves. 

The  superficial  median  vein  begins  in  the  anterior  plexus  in  front  of  the 
wrist,  and  losses  up  tlie  centre  of  the  front  of  the  forearm,  receiving  numerous 
cutaneous  branches,  and  communicating  on  each  side  with  the  superfii'ial  ulnar  and 
radial  veins.  At  the  bend  of  the  elbow  it  receives  the  deep  median  vein,  which 
is  formed  V»y  tlie  union  of  the  outer  vena  comes  of  the  ulnar  artery  with  the  mus- 
cular and  radial  recurrent  veins.  The  short  trunk  pierces  the  deep  fascia  to  join 
the  median  vein,  which  immediately  afterwards  bifurcates  into  the  median  basilic 
and  median  cejthalic. 

The  median  cephalic  vein,  the  smaller  branch  of  the  median,  runs  upwards 
and  outwards  in  the  sulcus  between  the  biceps  and  supinatus  longus,  and,  joining 
the  superficial  radial  vein  immediately  above  the  bend  of  the  elbow,  forms  the 
ce]ihalie  vein.  The  musculo-cutaneous  nerve  passes  beneath  it,  a  few  fibres  of  the 
nerve  lying  superficial  to  it. 

The  median  basilic  vein,  tlie  larger  of  the  two  divisions  of  the  median  vein, 
runs  upwards  and  inwards  across  the  semilunar  fascia  of  the  Inceps,  by  which  it  is 
separated  from  the  brachial  artery,  to  the  internal  bicipital  sulcus,  where  it  joins 
one  of  the  superficial  ulnar  veins  or  their  united  trunk  to  form  the  Ijasilic.  Fibres 
of  the  internal  cutaneous  nerve  pass  both  in  front  and  behind  it.  This  vein  is 
especially  prominent  at  the  bend  of  the  elbow;  and,  on  account  of  its  larger  size 
and  superficial  jiosition,  was  usually  chosen  in  venesection  when  this  operation  was 
in  vogue.  The  lancet,  if  care  was  not  taken,  was  liaVdeto  i)ass  through  the  bicipital 
fascia  and  injure  the  artery,  when  varicose  aneurysm  f)r  aneurysmal  varix  was 
a  common  re-^ult. 

The  cephalic  vein,  formed  by  the  union  of  the  median  cephalic  with  the  super- 
ficial radial  vein,  courses  upwards  first  in  the  external  bicijiital  sulcus,  and  then 
in  the  interval  between  the  pect oralis  major  and  the  deltoid,  jierforates  the  costo- 
coracoid  membrane,  and,  crossing  the  first  part  of  the  axillary  artery,  opens  into 
the  axillarv  vein.     It  contains  a  pair  of  valves  where  it  joins  the  axillary  vein. 

The  basilic  vein — formed  by  the  union  of  the  median  basilic  and  one  of  the 
superficial  ulnar  veins  or  their  united  trunk — jiasses  u\>  the  inner  side  of  the  arm 
41 


642 


THE  VEIXS 


a  little  internal  to  the  biceps,  and  nearly  over  the  course  of  the  brachial  artery. 
At    the  junction  of  the  middle  with  the  lower  third  of  the  arm  it  ]>ierces   the 


Fig.  39(>. — Supekficial  Veins  axd  Lymphatics  of  the  Left  Foreakm  and  Akm. 

(Walsham.j 


Pectora-is  major,  booked  up 


External  jugular  vein 


Posterior  superficial  ulnar    ' 
rein 
Median  basilic  vein 
Inner  set  of  superficial  lym- 
phatics of  forearm 

Deep  median  vein 

INTERXAL  CCTAXEOrS 
SERVE 

Anterior  superficial  ulnar  

vein 


Median  set  of  superficial  lym- 
phatics of  forearm 


Supraclavicular  glawl 
Jugulo-cephnlic  rein 

Deltoid  muscle 


Lymphatics  accompanying 
cephalic  vein 

Axillary  glanils 


Cephalic  rein 


Lymphatic  vessels  nf  inner 
side  of  arm 


Biceps,  exposed 

MUsCULrt-CUTASEtJlS 
SER  VE 

Brachi'il  artery 
Bicipital  fascia 
Median  cephalic  vein 

Superficial  radial  vein 
Superficial  median  vein 


Outer  set  of  superficial  lym- 
phatic vessels  of  forearm 


deep  fascia,   and  ends  by  uniting  with  the  inner  1»rachial  vena   comes   to   form 
the  axillarv  vein. 


DEEP  VEINS  OF  UPPER  EXTREMITY  643 


II.    THE  DEEP  VEINS  OF  THE  UPPER  EXTREMITY 

The  deep  veins  of  the  upper  extremity  accompany  their  corresponding 
arteries  and  consequently  require  no  detailed  description.  There  are  two  veins  to 
each  artery  l^elow  the  level  of  the  axilla,  known  as  the  companion  veins  or  vena? 
comites.  In  the  leg,  as  will  be  afterwards  noticed,  the  vena3  comites  of  the  main 
arteries  extend  as  far  as  the  knee  only.  The  deep  veins  all  contain  numerous 
valves,  and  connnunicate  at  frequent  intervals  througli  intermuscular  veins  with  the 
superficial. 

Beginning  at  the  fingers,  two  minute  veins  accompany  each  digital  artery 
along  the  sides  of  the  fingers,  and,  uniting  at  the  cleft,  form  interdigital  veins 
which  join  the  venae  comites  of  the  arteries,  forming  the  superficial  palmar  arch. 
In  like  manner  the  veins  accompanying  the  arteries  forming  the  deep  arch  receive 
tributaries  corresponding  to  the  branches  of  that  arch.  The  venae  comites  from 
the  ulnar  side  of  the  superficial  and  deep  arches  unite  at  the  spot  where  the  ulnar 
artery  divides  into  the  superficial  and  deep  branch  to  form  two  ulnar  venae  comites; 
whilst  those  on  the  radial  side  of  the  superficial  and  deep  arch  accompany  the  su]ier- 
ficial  volar  artery  and  the  termination  of  the  radial  artery  respectively,  and  unite 
at  the  spot  where  the  superficial  volar  is  given  off  from  the  radial  artery,  to  form  the 
radial  yenas  comites.  The  ulnar  and  radial  venae  comites  thus  formed  course  up 
the  forearm  with  their  respective  arteries,  receiving  numerous  tributaries  from  the 
muscles  amongst  which  they  run,  and  giving  frequent  communications  to  the  super- 
ficial veins.  They  finally  unite  at  the  bend  of  the  elbow  to  form  the  brachial  venae 
comites.  The  ulnar  venae  comites  receive,  before  joining  the  radial,  the  companion 
veins  of  the  interosseous  arteries.  At  the  bend  of  the  ell)ow  the  deep  veins  are 
connected  with  the  superficial  median  vein  by  a  short,  thick  trunk,  the  deep  median 
vein. 

The  brachial  venae  comites  accompany  the  brachial  artery,  the  inner  vein 
receiving  at  the  lower  border  of  either  the  teres  major  or  su1;)sca})ularis  muscle  the 
outer  vein  and  the  basilic  vein,  to  form  a  single  axillary  vein. 

The  venae  comites  of  the  arteries  of  the  arm  anastomose  with  one  another  by 
frequent  cross  branches. 

The  axillary  vein  is  formed  by  the  junction  of  the  inner  brachial  vena  comes 
with  the  ])asilic  vein  at  the  lower  border  of  either  the  teres  major  or  sul)scapularis 
muscle.  It  is  a  vessel  of  large  size,  conveying  as  it  does  nearly  the  whole  of  the 
returned  blood  from  the  upper  extremity.  It  accompanies  the  axillary  artery 
through  the  axilla,  lying  to  its  inner  side  and  at  the  upper  part  of  the  space  on  a 
sliglitly  lower  i)lane.  At  the  outer  l)order  of  the  first  ril)  it  changes  its  name  to  the 
subclavian.  It  has  one  or  two  axillary  glands  in  close  connection  with  it,  and  is 
lial)le,  if  care  is  not  taken,  to  be  wounded  in  removing  these  glands  when  infiltrated 
with  cancer  secondary  to  cancer  of  the  breast.  The  vein  contains  a  pair  of  valves, 
usually  placed  near  the  lower  border  of  the  subscapularis  muscle.  It  receives  in  its 
course  through  the  axilla: — (1)  The  subscapular  veins  which  accompany  the  sub- 
scapular artery;  (2)  the  circumflex  veins  accompan3''ing  the  circumflex  arteries; 
(3)  the  long  thoracic  veins  accompanying  the  long  thoracic  artery;  (4)  numerous 
small  veins  returning  the  l)lood  from  the  axillary  glands;  (5)  the_ veins  correspond- 
ing to  the  branches  of  the  thoracic  axis;  and  (B)  the  cei^halic  vein. 

The  subclavian  vein  (fig.  329)  is  the  continuation  of  the  axillary.  It  begins 
at  the  outer  l)order  of  the  first  rib,  and  terminates  by  joining  the  internal  jugular  to 
form  the  innominate  vein  opposite  the  outer  part  of  the  sterno-clavicular  articula- 
tion. It  lies  anterior  to  the  subclavian  artery  and  on  a  lower  plane,  and  is  se})arated 
from  the  artery  in  the  second  part  of  its  course  by  the  scalenus  anticus  muscle.  The 
subclavian  vein,  just  before  the  spot  where  it  is  joined  l\v  the  external  jugular, 
contahis  a  pair  of  valves. 

Tributaries. — Near  the  outer  border  of  the  sterno-mastoid  nmsele  it  receives 
the  external  jugular  vein.  Occasionally  the  cephalic  vein,  (^r  a  branch  from  the 
cephaHc  (the  jugulo-cei)halic),  passes  over  the  clavicle  to  the  subclavian  (fig.  390). 

Chief  variations.— (1)  Tlie  subclavian  vein   may  niii  on  a  higher  plane  than  usual,  lying 


644  THE  VELXS 

even  above  the  artery.  (2)  It  luaj'  pass  with  the  artery  behiud  the  scalenus  anticus.  (3)  It  may 
ruu  behind  the  scalenus  anticus  and  the  arterj'  in  front  of  that  muscle.  (4)  It  may  split  and 
enclose  the  scalenus  anticus.  (5)  It  may  pass  between  the  clavicle  and  the  sulx'lavius.  (6)  It 
may  receive  directly  the  transverse  cervical,  the  suprascapular,  the  anterior  jugular,  or  the 
cephalic  vein,  or  the  veua3  comites  of  the  brachial  artery. 


6.   TIIF  VEINS  OF  THE  LOWER  EXTREMITY 

The  veins  of  the  lower  extremity  are  divided  into  the  superficial  and  the 
deep.  The  superficial  veins  lie  in  the  subcutaneous  tissue  superficial  to  the  deep 
fascia,  through  which  they  receive  numerous  communicating  branches  from  the 
deep  veins.  They  are  collected  chiefly  into  two  main  trunks,  which,  beginning 
on  the  foot,  extend  upwards,  one  lying  antero-internally,  and  the  other  |)ostero- 
externally.  The  former  finally  joins  the  femoral  vein  by  passing  through  the  deep 
fascia  at  the  groin;  the  latter  the  popliteal  by  perforating  the  fascia  at  the  ham. 
The  deep  veins,  on  the  other  hand,  accompany  their  corresponding  arteries. 
Below  the  knee  there  are  two  veins  to  each  artery;  above  it,  excepting  at  the  back 
of  the  thigh,  there  is  only  one  vein  to  each  artery.  All  the  veins  of  the  lower  limb 
have  valves  which  are  more  numerous  than  in  the  veins  of  the  upper  extremity, 
and  in  the  deep  than  in  the  superficial  veins. 


I.    THE  SUPERFICIAL  VEINS  OF  THE  LOWER  EXTREMITY 

The  superficial  veins  of  the  lower  limb  are  collected  into  two  main  trunks. 
One,  the  long  or  internal  saphenous,  which  is  placed  antero-internally;  the  other, 
the  short  or  external  saphenous,  which  is  placed  postero-externally.  These  veins 
commence  on  the  dorsum  of  the  foot  in  an  irregular  arch,  which  stretches  across 
the  instep  Avith  its  convexity  towards  the  toes.  The  arch  receives  branches  from 
the  four  outer  toes  and  dorsum  of  the  foot,  and  one  branch  of  somewhat  larger  size 
than  the  rest  from  the  inner  side  of  the  great  toe.  It  also  communicates  with  the 
venae  comites  accompanying  the  dorsal  artery  of  the  foot  (fig.  397). 

The  long  or  internal  saphenous  vein  commences  on  the  inner  side  of  the  foot 
at  the  inner  end  of  the  above  described  venous  arch,  and,  after  receiving  branches 
from  the  sole  which  join  it  by  turning  over  the  inner  border  of  the  foot,  passes 
upwards  in  front  of  the  inner  ankle,  and  then  obliquely  upwards  and  backwards 
about  a  finger's  breadth  from  the  posterior  border  of  the  tibia  in  company  with  the 
internal  saphenous  nerve,  which  becomes  sujierficial  just  beloAv  the  knee.  Con- 
tinuing its  course  upwards,  it  passes  behind  the  internal  condyle,  and  then  runs 
upwards  and  somewhat  outwards  on  the  inner  side  of  the  front  of  the  thigh  to 
about  an  inch  and  a  half  beloAv  Poupart's  ligament,  Avhere,  after  receiving  the  superfi- 
cial circumflex  iliac,  superficial  epigastric,  and  superficial  external  ])udic  veins,  it  dips 
through  the  saphenous  opening  in  the  fascia  lata,  and  ends  in  the  femoral  vein.  In 
its  course  up  the  leg  and  thigh  it  receives  numerous  unnamed  cutaneous  branches, 
and  at  varial^le  intervals  communicates  Avith  the  deep  veins.  Just  before  it  ])asses 
through  the  saphenous  opening,  it  often  receives  a  large  vein  (external  femoral 
cutaneous)  formed  by  the  union  of  scA'eral  of  the  cutaneous  veins  on  the  uj)per 
and  outer  part  of  the  thigh,  and  a  second  vein  (the  internal  femoral  cutaneous) 
formed  by  the  union  of  the  cutaneous  veins  from  the  inner  and  back  part  of  the 
thigh.      The  long  saphenous  vein  contains  from  ten  to  tAventy  valves. 

The  short  or  external  saphenous  vein  begins  at  the  outer  end  of  the  venous 
arch,  or  plexus,  on  the  dorsum  of  the  foot.  After  receiving  branches  from  the  sole, 
Avhich  turn  over  the  outer  border  of  the  foot,  it  passes  behind  the  outer  ankle,  and 
then  upAA-ards  and  iuAvards,  lying  at  first  along  the  outer  side  of  tlie  tendo  Achillis, 


SUPERFICIAL   VEINS   OF  LOWER   EXTREMFFY 


645 


Fig.  397.— The  Slpekkicial  Vein.s  a.nd  Ly.mphatics  of  the  Left  Lowek  Limb. 

(Walshani.) 


Superficial  epigastric  rein 


Lymphatics  from  penU  and 
scrotum 
Common  femoral  vein 

Superfieia I  fe moral  tympka t ic 

1]  lands 
Superficial  external pudic  vein 


Internal  femoral  cutaneous  vein 


Long  snpltenous  vein 


INTERNAL  MALLEOLUS 
Dorsal  venous  arch 


Superficial  lymp/mticsfrom 
lateral  wall  of  abdomen 

Superficial  lymphatics  from 
lower  and  anterior  walls 
of  abdomen 


Superfiiial  inguinal 

lymphatic  glands 

Superficial  circnmflez 

iliac  vein 


External  femoral 
cutaneous  vein 


646  THE  VEINS 

afterwards  along  the  back  of  the  calf,  in  company  with  the  external  or  short 
saphenous  nerve,  to  about  the  lower  part  of  the  centre  of  the  popliteal  space, 
where  it  perforates  the  deep  fascia,  and,  sinking  between  the  two  lieads  of  the 
gastrocnemius,  opens  into  the  popliteal  vein.  As  it  passes  uj)  the  calf  Ix-tween  the 
superficial  and  deep  fascia,  it  receives  numerous  cutaneous  veins  from  the  heel,  and 
the  outer  side  and  Ixick  part  of  the  leg,  and  communicates  at  intervals,  through 
transverse  or  internuiscular  branches,  with  the  deep  veins  (venas  comites)  accom- 
})anying  the  peroneal  artery.  Just  before  perforating  the  deep  fascia,  it  receives  a 
large  descending  branch  from  the  lower  and  back  part  of  the  thigh,  and  sends 
upwards  and  inwards  a  communicating  vein  to  the  long  saphenous.  A  small 
offshoot  from  the  inferior  sural  branch  of  the  popliteal  artery  accompanies  the  vein 
for  a  short  distance  down  the  back  of  the  calf.  The  short  saphenous  vein  contains 
from  nine  to  twelve  valves. 


II.    THE  DEEP  VEINS  OF  THE  LOWER  EXTREMITY 

The  deep  veins  of  the  lower  extremity  accompany  the  arteries,  and  have 
received  corresponding  names.  From  the  foot  to  the  knee  there  are  two  veins 
to  each  artery.  These  veins  run  on  either  side  of  the  corresponding  artery,  and 
communicate  at  frequent  intervals  with  each  other  across  it.  They  are  known  as 
the  vense  comites.  From  the  knee  upwards  there  is  a  single  vein  to  each  artery, 
except  at  the  back  of  the  thigh  and  in  the  gluteal  region,  where  there  are  com- 
monly two. 

The  veins  of  the  foot  and  leg. — The  vena?  comites  of  the  internal  and  ex- 
ternal plantar  arteries,  after  receiving  small  veins  corresponding  to  the  brandies 
of  these  vessels,  unite  beneath  the  abductor  hallucis  muscle  to  form  the  vena? 
comites  of  the  posterior  tibial  artery.  These,  again,  receive,  at  the  spot  where 
the  peroneal  artery  is  given  off  from  the  posterior  tibial,  the  vense  comites  of  the 
peroneal  artery,  which  are  formed  in  like  manner  by  the  confluence  of  the  various 
veins  corresponding  to  the  branches  of  that  vessel.  Opposite  the  lower  border  of 
the  popliteus  muscle,  the  posterior  tibial  veins  unite  with  the  anterior  tibial  veins, 
which  pass  through  the  upper  part  of  the  interosseous  meml^rane  with  the  anterior 
til:)ial  artery,  to  form  the  popliteal.  The  anterior  tibial  veins  are  the  continuation 
of  the  venae  comites  of  the  dorsal  artery  of  the  foot,  Avhich,  in  their  turn,  are 
formed  by  the  confluence  of  the  veins  accompanying  its  various  branches.  The 
anterior  tibial  venae  comites  thus  formed  run  with  the  anterior  tibial  artery  up  the 
front  of  the  leg,  and,  after  passing  through  the  interosseous  membrane  along  with 
the  artery,  join  the  posterior  tibial  veins  to  form  a  single  popliteal. 

All  these  veins  contain  numerous  valves,  and  communicate,  by  means  of  inter- 
muscular branches,  with  the  superficial  veins. 

The  popliteal  vein  is  formed  by  the  confluence  of  the  venae  comites  of  the 
anterior  and  posterior  til)ial  arteries  at  the  lower  border  of  the  popliteus,  and  extends 
upwards  to  the  opening  in  the  adductor  magnus  at  the  junction  of  the  middle  and 
lower  third  of  the  thigh,  where  it  changes  its  name  to  femoral.  It  accompanies  the 
])opliteal  artery,  lying  superficial  to  it  in  the  whole  of  its  course,  and  tightly  bound 
down  to  it  by  its  fascial  sheath.  At  the  lower  part  of  the  space  it  is  a  little  internal 
to  the  artery,  but,  crossing  the  vessel  obliciuely  as  it  ascends,  lies  a  little  external 
to  it  at  the  upper  part  of  the  space.  The  internal  popliteal  nerve  lies  su}>erficial 
to  the  vein,  being  external  to  it  above,  then  on  it,  and  then  a  little  to  its  inner  side. 
The  popliteal  vein  contains  two  or  three  valves. 

The  chief  variations  of  the  popHteal  are  : — (1)  It  may  lie  between  the  artery  and  the  bone. 
(2)  It  may  be  ilnuhle  thnmuli  a  [lait  or  the  whole  of  the  popliteal  space.  (3)  Two  veins  by  fre- 
quently unitin<?  in  front  and  behind  the  artery  may  form  a  kind  of  plexus  around  the  vessel. 
(4)  It  may  be  shorter  than  usual  in  consequence  of  a  high  union  of  the  tibial  venfe  comites. 

The  femoral  vein,  the  continuation  of  the  popliteal  upwards,  extends  from  the 
tendinous  opening  in  the  adductor  magnus  to  an  inch  and  a  half  below  Poupart's 
ligament  where  it  joins  the  profunda  vein  to  form  the  conuiion  femoral  vein.  In 
this  course  its  relations  are  similar  to  those  of  the  superficial  femoral  artery.     As 


EXTERNAL  ILIAC  647 

tlie  vein  j)ays('S  throut^li  Hunter's  canal,  it  lies  luiiind  ami  a  little  external  to  the 
artery.  At  the  apex  of  Scarpa's  triangle  it  is  still  jjosterior  to  the  artery,  but 
gradually  passes  to  the  inner  side  as  it  ascends  through  tliat  space.  It  contains 
three  pairs  of  valves.  The  close  connection  of  the  vein  to  the  artery  should 
be  renieinljered  in  tlie  operation  of  ligature.  The  sheath  should  be  ojjened  on  its 
inner  side,  that  is,  well  over  the  artery,  and  the  point  <»f  the  aneurysm  needle  kept 
closely  a])plied  to  the  artery  lest  it  perforate  the  overlai>ping  vein. 

Tributaries. — (1)  The  venae  comites  of  the  anastoniotica  magna  artery;  (2) 
the  venfe  coniit(^s  corn'S])onding  to  the  muscular  branches  of  the  femoral. 

The  profunda  or  deep  femoral  vein  accompanies  the  profunda  or  deep  femoral 
artery,  and  receives  the  venic  comites  corresponding  to  its  various  branches. 
Unlike  the  other  veins  of  the  lower  extremity,  it  lies  in  front  of  its  companion 
artery,  and  is  at  first  a  little  internal  to  it.  It  terminates  by  joining  the  super- 
ficial femoral  vein  about  an  inch  and  a  half  below  Poupart's  ligament  in  the  angle 
between  the  femoral  and  profunda  arteries.      It  contains  five  valves. 

The  common  femoral  vein  is  a  short  thick  trunk  corresponding  to  the  common 
femoral  artery.  It  is  formed  by  the  confluence  of  the  su])erficial  femoral  and 
jirofunda  veins  about  an  inch  and  a  half  below  Poupart's  ligament,  and  is  con- 
tinued upwards  to  the  lower  border  of  that  structure,  where  it  takes  the  name 
of  external  iliac.  It  lies  on  the  same  plane  as  the  common  femoral  artery,  but 
internal  to  that  vessel,  from  which  it  is  separated  by  a  delicate  prolongation 
of  fascia  stretching  between  the  front  and  back  layers  of  the  femoral  sheath. 
Internally,  it  is  separated  by  a  similar  septum  of  fascia  from  the  crural  canal. 
It  usually  contains  two  valves:  one  just  above  the  junction  with  the  profunda  vein, 
the  otlier  just  below  Poupart's  ligament  (fig.  372). 

Tributary. — The  long  saphenous  vein  which  reaches  it  by  passing  through  the 
sai)hcuous  opening  in  the  deep  fascia. 

Chief  variations. — (1)  The  femoral  vein  luay  be  double  in  part  or  in  the  whole  of  its  length. 
(2)  It  may  sjilit  into  two  and  embrace  the  femoral  artery.  (3)  It  may  pass  through  the 
adductor  magiius  above  the  femoral  artery  and  run  separate  from  the  artery  until  it  joins  the 
])rofunda  vein  to  form  the  common  femoral  vein.  (4)  It  may  run  with  the  sciatic  neiTe  and 
pierce  the  adductor  magnus  at  tlie  level  of  the  lesser  trochanter.  When  this  occurs  the  femoral 
artery  is  usually  very  small,  and  the  sciatic  artery  is  the  chief  nutrient  vessel  of  the  thigh. 

The  external  iliac  vein  is  the  continuation  upwards  of  the  common  femoral. 
Beginning  at  the  lower  border  of  Poupart's  ligament  it  accompanies  the  external 
iliac  artery  upwards  and  inwards  along  the  brim  of  the  pelvis,  lying  at  first  on  tlie 
horizontal  ramus  of  the  pubes,  and  then  on  the  psoas  muscle.  It  terminates  in  the 
common  iliac  vein  by  joining  the  internal  iliac  vein  behind  the  internal  iliac  artery 
opposite  the  lower  border  of  the  sacro-iliac  synchondrosis.  It  lies  at  first  internal 
to  the  external  iliac  artery,  and  on  the  left  side  remains  internal  to  the  artery 
throughout  its  course.  On  the  right  side,  however,  as  it  ascends,  it  gradually  gets 
a  little  behind  the  artery.     It  contains  one  or  two  valves. 

Tributaries. — (1)  The  deep  epigastric  vein,  formed  by  the  union  of  the  veiue 
comites  of  the  deep  epigastric  artery,  joins  the  external  iliac  just  above  Poupart's 
ligament.  (2)  The  deep  circumflex  iliac  vein,  which  is  formed  in  the  same  way 
by  the  confluence  of  the  vente  comites  of  the  deep  circumflex  iliac  artery,  joins  the 
external  iliac  vein  a  little  higher. 


THE    LYMPHATICS 


THE  lymphatics  consist  of  lymphatic  vessels  and  lymphatic  glands.  The 
lymphatic  vessels  carry  lymph,  and  the  lymphatics  of  the  intestine  chyle  as 
well  whilst  digestion  is  going  on.  The  chyle-carrying  lymphatics  are 
generally  known  as  lacteals.  The  lymphatic  glands  are  situated  at  certain  spots  in 
the  course  of  the  lymphatic  vessels.'  The  lymphatic  vessels  ultimately  terminate 
either  in  the  left  or  right  lymphatic  duct.  The  former,  some  eighteen  inches  in 
length,  known  as  the  thoracic  duct,  Ijegins  at  the  continence  of  certain  lymphatics 
in  the  ahdomen,  passes  through  the  thorax,  and  terminates  in  the  left  innominate 
vein  at  the  confluence  of  the  left  internal  jugular  and  subclavian  veins.  It  receives 
the  lymphatics  of  both  lower  extremities,  the  lymphatics  of  the  abdomen,  excej^t 
those  from  the  convex  surface  of  the  liver,  the  lymphatics  from  the  left  half  of  the 
thorax,  the  left  half  of  the  head  and  neck,  and  the  left  upper  extremity.  The  right 
lymphatic  duct  is  a  short  vessel  a  little  less  than  an  inch  in  length.  It  receives  the 
lymphatics  from  the  convex  surface  of  the  liver,  the  right  half  of  the  thorax,  the 
right  side  of  the  head  and  neck,  and  the  right  upper  extremity.  It  ends  in  the 
right  innominate  vein  at  the  confluence  of  the  right  internal  jugular  and  subclavian 
veins. 

The  thoracic  duct,  or  left  lymphatic  duct,  is  described  with  the  Lvivi- 
PHATics  OF  THE  Thorax;  the  right  lymphatic  duct  with  the  Lymphatics 
OF  THE  Head  and  Neck. 


THE  LYMPHATICS  OF  THE  HEAD  AND  NECK 

The  lymphatics  of  the  head  and  neck  are  divided  into  the  superficial  and 
the  deep.  The  superficial  roughly  follow  the  course  of  the  superficial  veins. 
Streaming  down  the  scalp  and  face,  they  enter  the  neck  through  corresponding 
groups  of  superficial  glands,  and  then  converge  to  join  the  superficial  cervical 
chain  and  in  part  the  deep  cervical  chain  of  glands  which  are  situated  along  the 
course  of  the  external  and  internal  jugular  veins  respectively.  The  deep  lymphatics 
of  the  head  and  neck  follow  roughly  the  course  of  the  deep  arteries.  They  include 
the  lymphatics  from  the  interior  of  the  cranium;  from  the  orl)it;  from  the  interior 
of  the  nose  and  mouth;  from  the  tongue;  from  the  i)l)arynx,  larynx,  and  upi»er 
part  of  the  trachea  and  oesophagus,  and  from  the  thyroid  gland.  After  passing 
through  certain  glands  in  their  course,  they  terminate  chiefly  in  the  deep  cervieal 
chain  of  glands.  The  deep  cervical  chain  of  glands,  after  receiving  the  lymjihatics 
from  the  superficial  chain,  ends  in  the  thoracic  duct  on  the  left  side,  and  in  the 
right  Ivmphatic  duct  on  the  right  side. 
^        '  648 


SUPERFICIAL  LYMPHATICS   OF  HEAD  AXD   NECK  649 


I.    THE  SUPERFICIAL  LYMPHATIC  VESSELS  AND  GLANDS  OF 
THE  HEAD  AND  NECK 

A.  The  Superficial  Lymphatic  Vessels 

The  superficial  lymphatic  vessels  may  be  su])divided  into  the  superficial 
lymphatics  of  the  scalp,  the  face,  and  the  neck  (i\<i.  398). 

1.  The  superficial  lymphatic  vessels  of  the  scalp  follow  roughly  the  course 
of  the  superficial  veins.  Thus  there  is  (1)  a  posterior  or  occipital  set,  which  course 
downwards  over  the  occipital  bone  to  the  occipital,  or  suboccipital  glands  as  they 
are  sometimes  called;  (2)  a  postero-lateral  or  posterior  auricular  set,  which  course 
downwards  behind  the  ear,  and  end  in  the  posterior  auricular  or  sterno-mastoid 
glands;  (3)  an  antero-lateral  or  temporal  set,  which  accompany  the  superficial 
temi)oral  vein  in  front  of  the  ear,  and  end  in  the  parotid  lymphatic  glands;  and 
(4)  an  anterior  or  frontal  set,  which  course  downwards  over  the  frontal  bone  and 
end  in  the  facial  lymphatics. 

2.  The  superficial  lymphatic  vessels  of  the  face — continuous  at  the  root  of 
the  nose  with  tlie  frontal  set  of  lymphatics  descending  from  the  scalp — course  down- 
wards and  backwards  with  the  facial  vein,  receiving  tributaries  from  the  inner  half 
of  the  eyelids,  the  side  of  the  nose,  the  contiguous  portions  of  the  cheek,  and  the 
upper  and  lower  lips.  They  end  in  the  submaxillary  lymphatic  glands  beneath 
the  lower  jaw.  The  lymphatics  from  the  outer  part  of  the  eyelids  and  the  outer 
part  of  the  cheek  run  backwards  and  slightly  dowuAvards  to  the  parotid  lymphatic 
glands. 

3.  The  superficial  lymphatic  vessels  of  the  neck  form  a  plexus  in  the  sub- 
cutaneous tissues  of  the  neck.  They  communicate  with  the  superficial  lymphatics 
of  the  scalp  and  face,  and  with  some  of  the  superficial  lymphatics  of  the  upper 
part  of  the  thorax.     They  end  in  the  superficial  cervical  chain  of  lymphatic  glands. 


B.  The  Superficial  Lymphatic  Glands 

The  superficial  lymphatic  glands  of  the  head  and  neck  may  be  divided  into 
two  sets,  a  transverse  and  a  vertical  (fig.  398). 

1.  The  transverse  occur  in  groups  in  the  course  of  a  line  draAAii  from  the 
occiput  to  the  mast<jid  process,  and  thence  along  the  zygoma  and  beneath  the  body 
of  the  lower  jaw  to  the  symphysis.  They  receive  as  afferent  vessels  the  lymj^hatics 
of  the  scalp  and  face.  Their  efferent  vessels  pass  into  the  superficial  and  deep 
cervical  chains. 

Tiiey  are  named: — (1)  The  occipital,  or  suboccipital;  (2)  the  posterior  auri- 
cular, or  sterno-mastoid;  (3)  the  parotid;  (4)  the  buccal;  and  (5)  the  sub- 
maxillary. 

(1 )  The  occipital  or  suboccipital  glands  are  situated  at  the  back  of  the  head, 
beneath  the  skin,  just  below  the  superior  curved  line  of  the  occipital  bone  and  over 
the  insertion  of  the  complexus  muscle.  They  receive  the  lymphatic  vessels  from 
the  Imck  of  the  head.  Their  efferent  vessels  discharge  into  the  superficial  lymphatic 
glands  of  the  neck.  It  is  these  glands  which  i)erha])S  more  esj)ecially  are  foimd 
enlarged  in  secondary  sy})liilis. 

(2)  The  posterior  auricular  or  sterno-mastoid  glands,  situated  over  the 
insertion  of  the  sterno-mastoid  nuiscle  behind  the  ear,  receive  the  ])osterior  auri- 
cular lymphatics.  Their  eft'erent  vessels  discharge  into  tlie  superficial  cervical 
lympliatics. 

(S)  The  parotid  lymphatic  glands  are  situated  Justin  front  of  the  ear  over 
the  parotid  salivary  gland,  in  the  sul)stance  of  which  one  or  more  are  embedded. 
They  receive  the  temporal  set  of  lymjthatic  vessels,  and  the  lymphatics  from  the 
external  parts  of  the  eyelid  and  posterior  and  greater  part  of  the  cheek.  They 
discharge,  partly  into  the  sul)maxillary  glands,  and  partly  into  the  superficial 
cervical  chain. 

(4)  The  buccal  lymphatic  glands  are  situated  on  the  surface  of  the  buccinator. 


650 


THE   LYMPHATICS 


Some  of  the  facial  lymphatics  pass  through  these  on  their  way  to  the  submaxillary 
glands. 

(5)  The  submaxillary  lymphatic  glands  are  situated  in  the  digastrir  triangle, 
beneath  the  body  of  the  lower  jaw.  They  vary  from  eight  to  twelve  in  number. 
They  receive  some  of  the  lymphatics  from  the  face,  i.e.  from  the  upper  and  lower 
lips  and  side  of  the  nose;  the  lymphatics  from  the  iioor  of  the  mouth,  from  the 
front  part  of  the  tongue,  and  from  the  sublingual  and  submaxillary  salivary  glands, 
and  the  anterior  efferent  vessels  from  the  parotid  lymphatic  glands.  Their  efferent 
vessels  terminate  partly  in  the  deep,  and  partly  in  the  superficial  cervical  lymphatic 
glands.     Two  or  three  glands  situated  in  the  middle  line  between  the  anterior  bellies 


Fig.  398. — The  Superficial  Ly.mphatics  of  the  Scalp,  Face,  axd  Neck.     (Walshani.) 


Frontal  vein 


Supraorbital  vein 
Cumiiiunicalion  with 

ophthalmic  vein 
Transverse  nasal  vein 

Angular  vein 
Lateral  nasal  veins 

Transverse  facial 

vein  r  v      ; 

Superior  labial  or         jS^^^i 

coronary  veiii 

Anterior  pterygoid 

or  deep  facial  vein 

Inferior  coronary 

vein 

Facial  vein 

Inferior  labial  vei7i 

Submental  vein 

Lingual  vein 

Superior  thyroid 
rein 

Miildle  thyroid 
vein 

Sterno-mastoid 

Anterior  jngnlar 
rein 

Ciiiiiiniiiiicdfioii 

hrlirrri,   ilil/erinr 
j,nnil„r  reins 
Platysma,  cut 


Anterior  temporal  vein 

Posterior  temporal  reiii 

Deep  temporal  vein 
Parotid  lymphatic  glands 
Common  temporal  vein 
Internal  maxillary  vein 

j'^rj'  Occipital  vein 

Temporo-maxillary  vein 

Posterior  auricular  i-ein 

Occipital  lymphatic  glands 
>^lerno-mastnid  lymphatic 

glands 
(uminiinica/ion  he/ween 
fiicial    and    external 
jugular  veins 
— •  Submaxillary  lymphatic 
glandx 
Internal  jugular  rein 
Posterior  extern  a  I  jugu  lar 

vein 
External  jugular  vein 


Superficial  cervical  chain 
of  glands 


Transverse 
cervical  vein 

^  Suprascapular 
vein 


Jugu  lo-cep  h  a  lie 
vein 


of  the  digastric  muscles  are  sometimes  distinguished  as   the    suprahyoid    lym- 
pbatic  glands. 

2.  The  vertical  set  of  superficial  glands  of  the  neck — four  to  six  in  number, 
known  as  the  superficial  cervical  chain — are  situated  chiefly  in  the  posterior 
triangle  of  the  neck,  along  the  course  of  the  external  jugular  vein,  lietween  the 
platysma  and  the  deep  fascia.  Small  superficial  glands  are  also  found  in  the  front 
of  the  neck  between  the  hyoid  Ixrne  and  the  sternum,  and  posteriorly  over  the 
trapezius  muscle.  The  superficial  cervical  glands  receive  the  vessels  from  the 
occipital  glands,  and  from  the  posterior  auricular  glands,  and  part  of  tliose  from 
the  parotid  and  submaxillary  glands.      They  also  receive  the  lymj)hatics  from  the 


DEEP  LYMPHATICS   OF  HEAD   AXD   NECK 


651 


integuments  of  the  neck  and  from  tlie  external  ear.     Their  efferent  vessels  open 
into  the  deep  chain  of  cervical  glands. 


II.    THE  DEEP  LYMPHATIC  VESSELS  AND  GLANDS 
OF  THE  HEAD  AND  NECK 

A.    The  Deep  Lymphatic  Vessels  of  the  Head  and  Neck 

The  deep  lymphatic  vessels  of  the  head  and  neck  may  he  divided  into 
the  lymphatics  of  the  cranium,  the  orbit,  the  temporal  and  zygomatic  fossa?,  the 
nose,  the  mouth  and  tongue,  the  pharynx,  the  larynx,  the  up])er  part  of  the 
oesophagus  and  trachea,  and  the  thyroid  body.  They  roughly  follow  the  course  of 
the  deep  arteries,  and  terminate  in  the  deep  cervical  chain  of  lymphatic  glands 
which  accompany  the  common  carotid  artery  and  internal  jugular  vein. 

1.   The  lymphatics  from  the  interior  of  the  cranium  are  divided  into  the 


Fig.  398a. — Diagram  of  the  Superficial  Lymphatic  Vessels  and  Glands  of  the  Head 
AND  Neck.     (After  Drawing  by  Dr.  Francis  li.  Sherwood.) 

Ext.  part  of  eyelid/ 
Outer  part  of  cheek 
Part  of  face 


Face  and  Lips  superficial 
Nose  and  floor  of  mouth. 


Ant.  part  of  tongue 


Sublingual 
Submaxillary  '•' 
Part  of  parotid  ) 


Submaxillary  glands  8  to  I 


Deep  cervical  glands 

Superficial  cervical  glands 


Suboccipital  glands 


Post.  Auric,  or 
Sterno-mastoid  glands 


Efferent  vessels  to  deep  cervical 


meningeal  and  the  cerebral.  The  meningeal  accompany  the  meningeal  arteries 
through  the  various  foramina  in  the  I)as(!  of  the  skull,  and  terminate  in  the  deep 
cervical  chain.  The  cerebral  lymphatics  pass  in  like  manner  with  the  cerebral 
vessels  (the  internal  carotid  and  verteln-al  arteries,  and  the  internal  jugular  vein), 
through  the  corresponding  foramina  in  the  base  of  the  skull,  and  join  the  deep 
lymphatic  chain.  The  origin  of  the  cerebral  lym])hatics  and  the  lymphatics  from 
the  clioroid  plexus  are  described  in  the  Anatomy  of  the  Brain  (page  678). 

2.  The  lymphatics  of  the  orbit  j)ass  witli  tlic  infraorbital  vein  into  the  s])heno- 
maxillary  fossa,  and  thence  with  the  internal  maxillary  vein  into  the  internal 
maxillary  and  deep  parotid  glands.  (For  description  of  the  lymphatics  of  the  eye- 
ball, see  page  852. ) 

3.  The  lymphatics  from  the  temporal  and  zygomatic  fossae  run  with 
the  arteries  in  these  situations,  and,  after  passing  througli  the  internal  maxillary 
glands,  join  the  deep  cervical  chain. 

4.  The  lymphatics  from  the  interior  of  the  nose  accompany  the  arteries 
supplying  that  cavity,  and  terminate,  in  jiart  in  the  lyiii])liatics  of  the  pharynx,  but 
chiefly  in  the  deep  cervical  chain.      They   communicate,  through  tlie   lymphatic 


652  THE  LYMPHATICS 

spaces  which  surround  the  olfactory  nerves,  witli  the  subdural  and  subarachnoid 
lympli-spaci^s  of  the  cranimu. 

5.  The  lymphatics  of  the  mouth  and  tongue. — The  lymphatics  from  the 
floor  of  the  mouth  i)ass  through  the  niylo-hyoid  muscle  into  the  submaxillary 
lymphatic  glands.  The  lymphatics  of  the  lips  i)ass  with  the  superficial  lymphatics, 
partly  into  the  submaxillary  glands,  and  partly  into  the  deep  cervical  chain.  The 
lym])hatics  of  the  deep  surface  of  the  cheek  and  of  the  roof  of  the  mouth  join  the 
internal  maxillary  Ij'mphatic  glands.  The  lymphatics  of  the  tongue  run  back- 
wards with  the  ranine  vein,  and,  after  passing  through  several  small  lingual  glands 
on  the  hyo-glossus  muscle,  join  the  deep  cervical  chain.  The  lymphatics  of  the 
front  part  of  the  tongue  pass  with  the  lymphatics  of  the  floor  of  the  mouth, 
through  the  mylo-hyoidean  muscles  into  the  submaxillary  glands. 

6.  The  lymphatics  of  the  pharynx  run  along  the  course  of  the  pharyngeal 
arteries  and  enter  the  upper  set  of  deep  cervical  glands.  Those  from  the  upper 
part  of  the  pharynx  pass  through  the  i)Ost-pharyngeal  gland.  The  lymphatics  of 
the  tonsil  open  into  the  submaxillary  glands  near  the  angle  of  the  jaw. 

Fig.  398b. — Diagram  of  the  Beep  Lymphatic  Vessels  and  Glands  of  the  Head  and 
Neck.     (After  Drawing  ))y  Dr.  Francis  R.  Sherwoofl.) 

(Upper  and  post,  part  of  Tongue 

_    ,  .,,         c ,  It   »  interior  of  Cranium 

Spheno-maxillary  Fossa  ill  t  t 

Inner  and  posterior  part  of  Nose 
Temporal  Fossa 

Orbit >^^        ^y  f  2  to  4 — 0«i  9        //  y  y  Upper  part  of  pharynx 

Nose.^  \      \       i  jyj         //  /  / 

Deep  muscles  of  neck 
(prevertebral) 


Upper  pari  of  pharynx  and  palat 

Internal  maxillary  glands  3  to  6 


Posterior  pharyngeal  glands 


Efferent  vessels  from  ^  \  XV  \l  \    ATrt/  ^.^^f  cervical  glands 

submaxillary  glands 

■  Deep  muscles 


OEs 
Lower  part  of  Thyroid  body 

Efferent  vessels'to  R,  and'L'  Lymphatic  ducts 

7.  The  lymphatics  of  the  larynx  join  the  deep  cervical  glands.  Those  above 
tlie  glottis  })ierce  the  thyro-hyoid  membrane,  and  end  in  the  upper  set  of  the  deep 
cervical  glands;  those  below  the  glottis  perforate  the  crico-thyroid  membrane,  and, 
after  passing  through  one  or  more  small  laryngeal  glands  at  the  lower  part  of 
the  larynx  on  its  anterior  or  lateral  asj^ect,  enter  the  lower  set  of  the  deep  cervical 
glands. 

8.  The  lymphatics  of  the  upper  part  of  the  oesophagus  and  trachea  join 
the  lower  glands  of  the  deep  cervical  cliain. 

9.  The  lymphatics  of  the  thyroid  body  accompany  the  thyroid  arteries, 
and  end  in  part  in  the  up2:»er  and  in  part  in  the  lower  glands  of  the  deep 
cervical  chain. 

B,  The  Deep  Lymphatic  Glands  of  the  Head  and  Neck 

1.  The  deep  lymphatic  glands  of  the  head  are  few  in  numl)t'r.  They  are 
the  lingual,  the  internal  maxillary,  and  the  post-))haryngeal. 

(1)  The  lingual,  two  to  four  in  iiuml)er,  are  situated  on  the  outer  surface  of 


LYMPHATICS   OF   I'PPKR   EXTREMPPV  653 

the  hyo-gl()Ssiis  and  genio-hyo-glosi^us  muscles.  They  receive  lymi^hatics  from  the 
upper  surface  and  i)osterior  part  of  the  substance  of  the  tongue.  Their  efferent 
vessels  terminate  in  tlie  superior  glands  of  tlie  deep  cervical  chain. 

(2)  The  internal  maxillary  or  deep  facial  glands,  three  to  six  innumlier,  are 
situated  by  the  side  of  the  jiharynx  innnediately  bcliind  the  buccinator  muscle. 
They  receive  the  lym})hatics  from  the  orltit,  the  nose,  the  temporal  and  spheno- 
maxillary fossiB,  the  upper  jaw,  the  })alate,  and  the  pharynx.  Their  efferent 
vessels  join  the  superior  glands  of  the  deep  cervical  chain. 

(8)  The  post-pharyngeal  gland  is  situated  behind  the  pharynx  on  the  rectus 
capitis  anticus  major  near  the  base  of  the  skull.  It  receives  lymphatics  from 
the  upper  part  of  the  pharynx,  from  the  nose,  and  from  the  deej)  })revertebral 
nuiscles. 

2.  The  deep  lymphatic  glands  of  the  neck  are  divided  into  the  upper  and 
the  lower. 

The  upper  set  extend  along  the  course  of  the  internal  jugular  vein  from  the 
base  of  the  skull  to  about  the  level  of  tlie  thyroid  cartilage.  They  receive  the 
lymi)hatics  from  the  interior  of  the  cranium  above;  the  lymphatics  from  the  deep 
muscles  of  the  upper  part  of  the  neck  behind;  and  the  lymphatics  from  the  internal 
maxillary  glands,  the  posterior  half  of  the  tongue,  the  middle  portion  of  the 
pharynx,  the  upper  part  of  the  larynx,  the  upper  part  of  the  thyroid  body,  aiid 
some  of  the  efferent  vessels  from  the  submaxillary  lymphatic  glands  in  front  and 
internally.  Their  efferent  vessels  pass  downwards  to  the  lower  deep  cervical 
glands. 

The  lower  deep  cervical  glands  follow  the  course  of  the  internal  jugular  vein 
from  the  thyroid  cartilage  to  near  the  clavicle.  They  receive  the  lymphatics  from 
the  lower  part  of  the  neck,  the  efferent  vessels  from  the  superior  set  of  deep 
cervical  glands,  the  lymphatics  from  the  lower  part  of  the  larynx,  the  lower  part 
of  the  thyroid  body,  the  upper  part  of  the  trachea  and  oesophagus,  and  the  efferent 
vessels  from  the  superficial  cervical  glands.  Their  efferent  vessels  end  in  the  jugular 
lymphatic  trunk,  which  unites  with  the  subclavian  lymphatic  trunk,  on  the  right 
side  to  form  the  right  lymphatic  duct,  and  on  the  left  side  to  end  in  the  thoracic 
duct.  The  right  jugular  trunk  may  also  receive  the  lymphatics  coming  from  the 
right  half  of  the  supei'ior  and  anterior  mediastina. 

The  right  lymphatic  duct. — The  right  lymphatic  duct  is  a  short  vessel 
from  half  to  three-quarters  of  an  inch  long.  It  receives  the  lymphatics  from 
the  right  side  of  the  head  and  neck,  from  the  right  upper  extremity,  most 
of  the  lymphatics  from  the  right  side  of  the  thorax,  the  right  lung  and  pleura 
and  from  the  right  side  of  the  heart  and  part  of  the  lymphatics  from  the  convex 
surface  of  the  liver.  It  passes  downwards  and  inwards  from  its  formation  at 
the  union  of  the  subclavian  and  jugular  lymphatic  trunks,  and  ends  at  the 
confluence  of  the  right  internal  juguhir  and  subclavian  veins.  Its  entrance  is 
guarded  Ijy  a  double  valve. 


THE  LYMPHATICS  OF  THE  UPPER  EXTP EMPTY 

The  lymphatics  of  the  upper  extremity — consisting  of  ])oth  lymjihatic  ves- 
sels and  lymphatic  glands — are  arranged  in  two  sets,  a  suj^erflcial  and  a  deep.  The 
former  are  situated  in  the  subcutaneous  tissue  l)etween  the  skin  and  the  deep  or 
muscular  fascia,  the  latter  along  the  course  of  the  arteries  of  the  limb.  Both  sets 
converge  as  they  approach  the  axilla,  and  unite  in  the  axillary  glands.  The 
efferent  vessels  of  these  glands  form  one  or  more  trunks,  which  oi^en,  on  the  left 
side,  into  the  thoracic  duct,  and,  on  the  right  side,  into  tlie  right  lymphatic 
duct. 


654 


THE  LYMPHATICS 


Fig.  399. — The  Superficial  Lymphatics  of  the  Left  Upper  Limb  and  Axillary 

Glands.     (Walshain.) 


Peetoralis  major,  hooked  ur 


External  jugular  vein 


Peetoralis  major 


Lymphatics  from  side  of  chest 


Pectoral  glands  — J^-y^-^     '  P  ' 


Epitrochlcar  gland 

Posterior  superficial  ulnar     ' 
rein 
Median  basilic  vein 
Inner  set  of  superficial  lym- 
phatics of  forearm 

Deep  median  vein 

INTERNAL  CUTANEOUS 
NER  VE 

Anterior  superficial  ulnar 
vein 


Median  set  of  superficial  lym- 
phatics of  forearm 


Suprackiviciilar  gland 
Jugulo-cephalic  vein 


Deltoid  muscle 


Lymphatics  accompanying 
cephalic  vein   . 


Axillary  glands 


Cephalic  vein 


Lymjihatic  vessels  of  inner 
side  of  arm, 


Biceps,  exposed 

MUSCULO-CUTA  NEO  US 
NERVE 

Brachial  artery 
Bicipital  fascia 
Mi'dian  cephalic  vein 

-  Sujierjicial  radial  vein 
Superficial  median  vein 


(later  set  of  superficial  lym- 
phatic vessels  of  forearm 


LYMPHATICS   OF   CPPER   EXTREMITY  655 


I.    THE  SUPERFICIAL   LYMPHATIC   VESSELS  AND   GLANDS   OF 
THE    UPPER   EXTREMITY 

1.  The  superficial  lymphatic  vessels  hcuin  around  the  nialrix  of  the  nail 
and  in  tlie  pulp  of  tlie  lintier.  Thence  thev  run  ujjwards,  in  tlie  form  of  fourmain 
channels,  along  the  side  of  the  linger — two  on  the  dorsal  and  two  on  the  palmar 
aspect. 

The  palmar  set  end  on  the  convexity  of  a  lymphatic  palmar  arch.  From  the 
arch,  lymphatic  vessels  run  up  the  forearm,  more  or  less  in  two  sets — an  outer  and 
an  inner — roughly  following  the  course  of  the  superti(;ial  veins;  a  third  or  median 
set,  starting  as  a  plexiform  arrangement  in  front  of  the  wrist,  runs  up  ])etwcen  the 
other  two.  The  communication,  however,  between  tlie  three  main  sets  of  vessels 
is  so  free  that,  when  they  are  minutely  injected,  the  front  of  the  forearm  appears 
covered  with  a  dense  plexus  of  lymphatics  (fig.  399). 

The  dorsal  set  of  digital  lymi)hati('S  ends  in  a  plexus  on  the  l)ack  of  the  hand. 
From  this  plexus  numerous  lymphatic  vessels  stream  up  the  back  of  the  forearm, 
and,  winding  round  the  inner  and  outer  borders  respectively  of  the  limb,  join  the 
lymphatics  on  the  anterior  aspect. 

From  the  bend  of  the  elbow  the  lymphatics  run  up  the  arm,  the  greater  numlier 
following  the  course  of  the  basilic  vein,  and,  dipping  lieneath  the  pectoralis  major, 
converge  to  end  in  the  axillary  glands.  The  lymphatics  from  the  outer  side  of  the 
arm  run  in  chief  part  obliquely  across  the  bice])S,  toAvards  the  axilla;  but  a  few 
accompany  the  cephalic  vein  to  the  infraclavicular  lymi)hatic  glands.  The  lym- 
phatics over  the  deltoid  also  mainly  end  in  these  glands. 

2.  The  superficial  lymphatic  glands  are  feAv  in  number.  There  are  none, 
as  a  rule,  below  the  bend  of  the  elbow.  Occasionally  there  is  one  at  the  bend 
of  the  elbow,  and  constantly  two  or  three  are  found  above  the  internal  condyle 
(epitrochlear  glands),  in  the  course  of  the  lymphatic  vessels  running  Avith  the 
basili<'  vein. 


II.    THE  DEEP  LYMPHATIC    VESSELS  AND    GLANDS   OF   THE 

UPPER    EXTREMITY 

1.  Tlie  deep  lymphatic  vessels  accompany  the  arteries  of  the  upjier  extremity. 
Hence  in  the  forearm  they  are  found  along  the  course  of  the  radial,  the  ulnar,  the 
anterior  interosseous,  and  the  posterior  interosseous  arteries.  At  the  bend  of  the 
elbow  they  converge,  and  follow  the  course  of  the  brachial  and  axillary  arteries  to 
the  axilla,  and  there  end,  together  with  the  superficial  lymphatics  of  the  u]t])er 
extremity  and  the  superficial  lym])liatics  from  the  side  of  the  chest  and  liack  of 
the  shoulder,  in  the  axillary  lymphatic  glands.  They  comniunicate  Avitli  the 
superficial  lymphatics  at  the  Avrist. 

2.  The  deep  lymphatic  glands. — A  few  small  glands  are  occasionally  found 
in  the  course  of  tlie  lymi)hatic  vessels  accom])anving  the  arteries  of  the  forearm, 
and.  more  often,  a  few  in  the  course  of  those  accom])anying  the  lirachial  artery. 
But  the  first  imjmrtant  set  of  deep  glands  is  met  with  in  the  axilla. 

The  axillary  glands  are  numerous  and  of  large  size.  They  are  about  twelve 
in  number.  They  are  arranged  in  four  chief  sets — a  median  set,  three  or  more  in 
number,  situated  along  the  course  of  the  axillary  artery  and  vein  (  axillary  glands 
proper);  an  inner  or  anterior  set,  four  or  five  in  number,  situated  l)elow  the  greater 
p<'ctoral  muscles  in  the  course  of  the  long  thoracic  artery,  on  the  outer  surface  of 
the  scrratus  magnus  (pectoral  glands);  a  )»ostcrior  or  external  set,  usually  two  in 
number,  situated  along  the  coui-se  of  the  subscapular  artery,  under  cover  of  the 
latissimus  dorsi  (subscapular  glands);  and  a  sui)crior  set,  usually  two  in  number, 
situated  just  below  the  clavicle  close  to  the  cephalic  vein.  U])on  the  cost(^-coracoid 
meml)rane  in  the  fossa  beneath  the  pectoralis  major  and  deltoid  (subclavian  or 
infraclavicular  glands). 

The  axillary  glands  proper,  or  the  glands  along  the  course  of  the  axillary  artery 
and  vein,  receive  the  larger  number  of  lyin]»hatics  from  the  arm.     The  pectoral 


656  THE  LYMPHATICS 

glands  receive  the  lymphatics  from  the  mammary  gland,  the  side  of  the  chest,  and 
the  integument  of  the  upper  portion  of  the  abdominal  wall.  The  subscapular 
glands  receive  the  lymphatics  from  the  integuments  of  the  back.  The  infra- 
clavicular glands  receive  the  lymphatics  from  the  outer  part  of  the  arm  and  integu- 
ments covering  the  deltoid.  They  communicate,  above  with  the  cervical  lymphatics, 
and  l)clo\v  with  the  other  glands  in  the  axilla.  The  efferent  vessels  from  all  these 
glands  run  upwards  along  the  subclavian  vein,  and  enter  the  neck  either  as  four 
distinct  trunks,  or  as  a  single  trunk  (the  axillary  lymphatic  trunk),  and  ter- 
minate on  the  left  side  in  the  thoracic  duct,  and  ou  the  right  side  in  the  right  lym- 
phatic duct. 

The  communication  between  the  glands  in  the  axilla  is  very  free.  Thus,  in 
secondary  infiltration  following  carcinoma  of  the  breast,  although  the  pectoral 
glands  may  at  first  be  alone  affected,  the  remaining  sets  generally  become  also 
involved. 


THE  LYMPHATICS  OF  THE  THORAX 

The  lymphatics  of  the  thorax  may  be  divided  into  the  parietal,  which  ramify 
in  the  thoracic  walls;  and  the  visceral,  which  receive  the  lym})h  from  the  thoracic 
viscera.  The  thoracic  duct,  which  conveys  the  lymph  from  the  lower  extremities 
and  from  the  greater  part  of  the  abdomen,  passes  through  the  posterior  mediastinum 
on  its  way  to  the  confluence  of  the  left  internal  jugular  and  subclavian  veins  at  the 
root  of  the  neck,  and  is  described  here  with  the  h-mphatics  of  the  thorax. 


I.    THE   PARIETAL   LYMPHATIC    VESSELS  AXD    GLANDS   OF 

THE  Til  OP  AX 

1.  The  parietal  lymphatic  vessels  are  divided  into  the  superficial  and  the 
deep. 

The  superficial  parietal  lymphatics  ramify  beneath  the  integuments,  over 
the  pectoralis  major  in  front,  the  serratus  magnus  laterally,  and  the  trapezius  and 
latissimus  dorsi  behind.  They  all  converge  toAvards  the  axilla,  and  end  in  the 
axillary  glands.  The  lymphatics  of  the  mammary  gland  end  for  the  most  part 
in  the  pectoral  set  of  the  axillary  glands,  but  those  from  the  inner  portion  of  the 
gland  pass  through  the  second,  third,  and  fourth  intercostal  spaces  into  the  internal 
mammary  lymphatic  chain  of  glands,  and  thus  o]ien  into  the  thoracic  duct  on  the 
left,  and  the  right  lymphatic  duct  on  the  right  side.  According  to  ^Nlacalister,  the 
lymphatics  from  the  nipple  and  areola  pass  more  deeply  into  the  axilla,  and  end  in 
one  of  the  axillary  glands,  placed  nearer  to  the  clavicle  than  the  pectoral  set. 

The  deep  parietal  lymphatics  are  subdivided  into  (1)  the  intercostal  and  (2) 
the  diaphragiiiatie. 

(1)  The  intercostal  lymphatics  accompany  the  intercostal  arteries  and  receive 
the  lymph  from  the  intercostal  muscles  and  the  parietal  pleura.  Those  in  the 
anterior  part  of  the  intercostal  space  run  forwards  and  end  in  the  internal 
mammary  or  anterior  intercostal  lymphatic  glands.  Those  in  the  posterior  part  of 
the  space  run  backwards,  and — after  receiving  the  dorsal  lymphatic  vessels  which 
accompany  the  dorsal  branches  of  the  intercostal  arteries  between  the  transverse 
processes  of  the  vertebrae,  and  return  the  lym})h  from  the  muscles  of  the  back  and 
from  the  spinal  canal — end  in  tlie  intercostal  or  jtosterior  intercostal  lymphatic 
glands. 

(2)  The  diaphragmatic  lymphatics  follow  the  vessels  of  the  diaphragm. 
They  terminate,  anteriorly  in  tlie  internal  mammary  and  anterior  mediastinal 
lymphatic  glands;  postero-laterally  in  the  lower  intercostal  lymphatics  and  in  the 
lymphatics   accompanying  the  musculo-piirenic  arter}-;  and  posteriorly  in  the  pos- 


PARIETAL   LYMPHATICS   OF   THORAX 


657 


terior  mediastinal  glands.  The  lymphatics  from  the  vertebral  jjortion  of  the  dia- 
phragm end  in  the  lumhar  glands  (see  Lymphatics  of  Abdomen,  page  661).  Some 
of  tlie  lymphatics  from  the  right  side  join  the  hepatic  lymphatics. 

2.  The  parietal  lymphatic  glands  are  also  divided  into  the  superficial  and  the 
dee) ». 

The  superficial  parietal  glands. — The  three  or  four  glands  along  the  lower 
border  of  the  ptctoralis  major,  described  here  as  the  pectoral  set  of  the  axillary 
glands,  are  by  some  authors  classed  as  superficial  thoracic  glands.  They  receive 
the  lymphatics  from  the  front  of  the  chest,  and  some  of  the  lymphatics  of  the 
mammary  gland.  There  is  also  occasionally  a  superficial  gland  a  little  ])elo\v  the 
ensiform  cartilage  called  the  epigastric  gland.  It  receives,  ■when  present,  some  of 
tlie  lymjihatics  from  the  lower  anterior  ciu-st  walls  and  upper  part  of  the  abdomen. 

The  deep  parietal  glands  are: — (1)  The  internal  mammary,  sternal,  or  anterior 
intercostal;  and  (  2  i  tlie  intercostal  or  posterior  intercostal. 

(1)  The  internal  mammary,  sternal,  or  anterior  intercostal  glands  lie  along 
the  course  of  the  internal  mammary  artery  behind  the  costal  cartilages  of  the  true 


Fig.  399a. — Diagram  of  the  Superficial  and  Deep  Lymphatic  Vessels  and  Glands  of 
THE  Upper  Extremity  including  the  Superficial  Lymphatic  Vessels  of  the  Back 
AND  Chest.      (After  Drawing  by  Dr.  Francis  R.  Sherwood.) 

Communication  with  deep  cervical  Lymphatics 


Efferent  vessels  to  R.  or  L.  Lymphatic  Dutt 


>  Lymphatics  of  front  of  Chest  and  Mamma 


Superficial  Lymphatics  of  back  as  low  as  Ilium 


Superficial  Lymphatics 


rilts.  There  is  usually  one  gland  corresponding  to  each  intercostal  space.  These 
glands  receive  the  lymjthatics  from  the  anterior  ])art  of  the  intercostal  spaces,  the 
lymphatics  ascending  with  the  superior  epigastric  artery  from  the  abdominal  walls, 
the  lymphatics  accompanying  the  musculo-phrenic  artery  from  the  diaphragm  and 
lower  intercostal  spaces,  and  the  lymphatics  from  the  inner  portion  of  the  mammary 
gland.  The  efferent  vessels  from  the  uppermost  glands  join  the  thoracic  and  right 
lym])hatic  ducts  respectively,  Init  some  of  the  efferent  vessels  of  the  lower  glands 
join  the  anterior  media.stinal  glands. 

(2  )  The  intercostal  or  posterior  intercostal  lymphatic  glands  lie  in  the  pos- 
terior end  of  each  intercostal  s])ace  alxiut  the  level  of  tiie  beads  of  tlie  ribs.  They 
receive  the  lymphatics  accompanying  the  intercostal  vessels  from  the  posterior  juirts 
of  the  intercostal  spaces,  and  the  lymphatics  from  tlie  deep  muscles  of  the  back,  and 
from  the  spinal  canal.  The  lowermost  also  receive  some  of  the  lymphatics  from 
the  diaphragm.  On  the  left  side  their  efferent  vessels  open  into  the  thoracic  duct. 
On  the  right  side  the  efferent  vessels  from  the  lower  glands  also  join  the  thoracic 
duct,  but  the  vessels  from  the  upper  glands  may  join  the  efferent  vessels  from  the 
bronchial  glands  (the  bronchio-mediastinal  trunk  •  and  open  into  the  right  lym- 
phatic duct. 
42 


658  THE  LYMPHATICS 


II.    THE    VISCERAL    LYMPHATIC    VESSELS    AND     GLANDS     OF     . 

THE   THORAX 

1.  The  visceral  lymphatics  of  the  thorax  include  those  from  the  heart  and 
pericardium,  the  lungs  and  visceral  pleura,  the  (psophagus  and  the  thymus  gland, 
with  the  glands  into  which  these  lymjihatics  respectively  open — namely,  the  ante- 
rior mediastinal,  the  superior  mediastinal,  the  posterior  mediastinal,  and  the 
bronchial. 

The  lymphatics  of  the  pericardium  end  in  front  in  the  anterior  mediastinal 
and  superior  mediastinal  glands,  and  behind  in  the  posterior  mediastinal  glands. 

The  lymphatics  of  the  heart  l)egin  at  the  apex,  and  follow  the  coronary  ves- 
sels to  the  base,  where  they  leave  the  pericardium,  and  imite  to  form  a  right  and 
a  left  trunk.  The  former  passes  over  the  arch  of  the  aorta,  then  through  one  of  the 
superior  mediastinal  or  cardiac  glands,  and  thence  backwards  to  the  trachea,  on 
which  it  runs  to  join  the  right  lymphatic  duct  at  the  root  of  the  neck.  The  left 
trunk  courses  along  the  pulmonary  artery,  and,  at  the  bifurcation  of  that  vessel, 
passes  through  one  of  the  posterior  mediastinal  glands  behind  the  arch  of  the 
aorta,  and  thence  runs  up  the  left  side  of  the  trachea  to  end  in  the  thoracic  duct. 

The  lymphatics  of  the  visceral  pleura  and  lung  form  a  st^perficial  set 
beneath  the  pleura,  and  a  deep  set  which  accompanies  the  pulmonary  vessels  and 
bronchial  tubes.  At  the  root  of  the  lung  the  superficial  join  the  deep,  which  then 
enter  the  bronchial  glands. 

The  lymphatics  of  the  thoracic  portion  of  the  oesophagus  l^egin  as  a 
plexus  ])etween  the  mucous  membrane  and  the  muscular  coat,  perforate  the  latter, 
and  terminate  in  the  i)()sterior  mediastinal  glands. 

The  lymphatics  of  the  thymus  terminate  in  the  superior  mediastinal  glands. 

2.  The  visceral  lymphatic  glands  are  the  anterior  mediastinal,  the  superior 
mediastinal,  the  {Hjsterior  mediastinal,  and  the  l:)ronchial. 

The  anterior  mediastinal  or  sternal  glands  lie  in  front  of  the  pericardium 
behind  the  sternum  in  the  loose  tissue  of  the  anterior  mediastinum.  They  receive 
the  lymphatics  from  the  antero-median  portion  of  the  diaphragm,  the  front  of  the 
pericardium  and  heart,  some  of  the  efferent  vessels  from  the  lower  internal  mammary 
lymphatic  glands,  and  the  lymphatics  from  the  convex  surface  of  the  right  lol)e  of 
the  liver.     Their  efferent  vessels  pass  u])wards  to  the  superior  mediastinal  glands. 

The  superior  mediastinal  or  cardiac  glands  lie  in  front  of  the  upper  part  of 
the  pericardium,  the  arch  of  the  aorta,  and  left  innominate  vein.  They  receive 
the  lymphatics  from  the  anterior  mediastinal  glands,  from  the  upper  and  front  ]iart 
of  the  pericardium  and  right  side  of  the  heart,  and  from  the  thymus  gland. 
Their  efferent  vessels  run  up  the  sides  of  the  trachea  to  join  the  thoracic  duct 
and  right  lymphatic  duct  respectively. 

The  posterior  mediastinal  glands  are  situated  in  the  posterior  mediastinum 
along  tlie  course  of  the  aorta  and  crsophagus.  They  receive  lymphatics  from  the 
back  of  the  pericardium  and  left  side  of  the  heart,  from  the  oesophagus,  from  the 
])osterior  part  of  the  diaphragm,  and  a  few  from  the  right  border  of  the  livtM". 
Their  efferent  vessels  pass  chieffy  into  the  thoracic  duct;  a  few  into  the  broneliial 
glands. 

The  bronchial  glands  are  placed  between  the  divisions  of  the  ])ronchi  at  the 
root  of  the  lung  (pulmonary  glands),  and  al)out  the  Infurcation  of  the  trachea 
(tracheal  glands).  The  larger  glands,  situated  at  the  bifurcation  of  the  trachea, 
are  twenty  or  thirty  in  number.  They  receive  the  ]ym})hatics  from  the  lung  and 
visceral  ])leura;  also  some  of  the  lym])hatics  from  the  trachea  and  from  the  back 
of  the  lieart  and  ])ericar(lium,  and  a  few  of  the  efferent  vessels  of  the  posterior 
mediastinal  glands.  Their  efferent  vessels,  with  the  efferent  vessels  of  the  sujjerior 
mediastinal  or  cardiac  glands,  pass  up  the  sides  of  the  trachea,  and  on  the  riglit 
side  either  terminate  directly  in  the  right  lymphatic  duct,  or  join  with  tlie  efferent 
vessels  of  the  intercostal  glands  to  form  a  common  trunk,  the  broncho-mediasti- 
nal  trunk,  and  thus  open  into  the  right  lymphatic  duct.  On  the  left  side  they 
open  directly  into  the  thoracic  duct,  or  first  form,  as  on  the  right  side,  a  broncho- 
mediastinal trunk. 


THORACIC  DUCT  659 

In  early  life  they  are  of  a  ])iiikish  coLmr,  but  as  life  advaiiees  tlit-v  heconie 
bluish,  and  later  aluKtst  hlaek,  from  the  deposit  of  })ignient  arrt'st<'d  in  thciu  in  its 
passage  from  the  lungs. 

THE  THORACIC  DUCT 

The  thoracic  duct  l)egins  in  the  abdomen  at  the  rcceptaciilum  chyli  opposite 
the  first  or  second  lunil»ar  vertebra,  enters  the  thorax  through  the  aortic  o}>ening 
of  the  diaphragm,  runs  up  the  posterior  mediastinum  to  the  right  of  the  aorta, 
crosses  behind  the  aortic  arch,  and,  leaving  the  thorax  at  the  su}»erior  opening, 
ascends  on  the  left  side  of  the  neck  as  high  as  the  seventh  cervical  vertel)ra,  and, 
finally  curving  over  the  a})ex  of  the  left  pleura  and  suljclavian  artery,  ends  in  the 
confluence  of  the  left  internal  jugular  and  subclavian  veins. 

The  duct  is  about  eigliteen  inches  long,  and  i)ursues  a  tortuous  course.  It  de- 
tains many  double  valves  which,  when  the  duct  is  dilated,  cause  it  to  be  constricted 
at  intervals,  and  give  it  somewhat  the  appearance  of  a  string  of  beads.  The  valves 
are  more  numerous  in  the  upper  than  in  the  lower  part  of  the  duct.  At  its  entrance 
into  the  innominate  vein  there  are  two  perfect  valves,  which  effectually  prevent  any 
regurgitation  of  lymph  or  entrance  (;f  blood.  The  calibre  of  the  duct  usually 
decreases  as  it  ascends  through  the  thorax,  l)ut  increases  again  at  its  upper  part. 
It  is  least  at  or  al)Out  the  fifth  thoracic  vertebra.  The  thoracic  duct  conveys  the 
lymph  iroxw  the  lower  extremities,  the  lymph  and  chyle  from  the  abdomen  (except 
some  of  the  lymph  from  the  convex  surface  of  the  liver),  the  lyn)})h  from  the  left 
side  of  the  thorax,  and  some  of  that  from  the  right  side,  and  the  lymph  from  the 
left  upper  extremity  and  the  left  side  of  the  head  and  neck. 

The  relations  of  the  thoracic  duct  in  the  abdomen,  thetliorax,  and  at  the 
root  of  the  neck,  may  be  considered  separately. 

1.  The  abdominal  portion  of  the  thoracic  duct  lies  deeply  placed  behind 
and  between  the  aorta  and  the  right  crus  of  the  diaphragm  on  tlie  front  of  the  body 
of  the  second  lumbar  vertel)ra.  This  part  of  the  duct  is  dilated  into  an  irregular, 
sacculated,  and  fusiform  sac,  known  as  the  receptaculum  chyli,  or  cistern  of 
Pecquet.  It  receives  the  efferent  vessels  of  the  lumbar  glands,  the  intestinal 
lymi)hatic  trunk,  and  sometimes  some  of  the  hepatic  and  gastric  lymphatics.  It  is 
thin- walled  and  contains  no  valves,  and  is  about  an  inch  and  a  half  long  (38  mm.) 
and  about  a  quarter  of  an  inch  in  diameter  at  its  widest  part  (7  mm.).  As  the  duct 
passes  through  the  aortic  opening  of  the  diaphragm,  it  still  lies  to  the  right  of  the 
aorta,  and  has  the  vena  azygos  major  to  its  right  side. 

2.  The  thoracic  portion  of  the  thoracic  duct  lies  at  first  in  the  posterior 
mediastinum  between  the  aorta  and  the  vena  azygos  major,  in  front  of  the  seven 
lower  thoracic  vertebra';  Init  at  the  level  of  the  fifth  thoracic  vertebra  it  ])asses  to  the 
left  behind  the  cesophagus  and  aortic  arch,  and  enters  the  superior  mediastinum, 
whence  it  escapes  through  the  upper  a])erture  of  the  thorax  into  the  root  of  the 
neck.  This  portion  of  the  duct  is  not  of  equal  calibre  throughout;  as  a  rule,  it  is 
contracted  in  some  places  and  dilated  at  others.  The  constrictions  indicate  the 
situation  of  the  valves. 

In  the  posterior  mediastinum  it  has  in  front  of  it,  from  below  upwards,  the 
jtericardium,  the  u'sophagus,  and  the  arch  of  the  aorta;  behind  it,  the  seven  lower 
thoracic  vertebra?,  the  anterior  connnon  ligament,  the  lower  right  intercostal  arteries, 
the  vena  azygos  minor,  and  at  times  one  or  moi'e  of  the  mid  left  intercostal  veins, 
and  the  vena  azygos  tertia.  To  its  left  is  the  thoracic  aorta,  and  to  its  right  the 
vena  azygos  major  and  the  right  ])U'Ura.  In  the  superior  mediastinum  it  a.^cends, 
between  the  O'sophagus  and  left  pleura,  to  the  posterior  and  left  side  of  the  superior 
tlioracic  opening.  It  here  has  in  front  of  it  the  first  jwrtion  of  the  left  subclavian 
artery,  behind  it  the  upper  thoracic  vertel)ra\  to  its  left  the  i)leura.  and  to  its  right 
the  cesophagus. 

Opening  into  the  thoracic  portion  of  the  duct  are: — tlie  lymjihatics  from  the 
left  half  of  the  thoracic  walls;  the  efferent  vessels  from  the  left  anterior  mediastinal 
and  intercostal  glands;  the  lymphatics  of  the  left  lung  and  the  left  side  of  the 
heart;  the  lymphatics  of  the  trachea  and  a^sophagus,  and  the  right  lower  internal 
mannnary  lymphatics. 


660  THE  LYMPHATICS 

o.  The  cervical  portion  of  the  thoracic  duct  as^eends  as  higli  as  the  level  of 
the  seventh  cervical  vertebra,  and  then  curves,  downwards  and  forwards,  over  the 
apex  of  the  pleura  in  front  of  the  sul)clavian  artery,  scalenus  anticus  muscle,  and 
vertebral  vein,  behind  the  left  internal  jugular  vein,  and  behind  and  suljsequently 
external  to  the  left  common  carotid  artery,  and,  having  received  the  left  jugular 
lymphatic  trunk,  opens  into  the  left  innominate  vein  at  the  confluence  of  the  inter- 
nal jugular  and  subclavian  veins.  The  cervical  portion  receives  the  lymphatics 
from  the  left  upper  extremity  and  left  side  of  the  head  and  neck. 

The  chief  variations  in  the  thoracic  duct. — (1)  The  thoracic  duct  luaj'  be  double  ;  when 
tliis  is  the  case,  the  left  duct  may  eud  normally  in  the  left  inuomiuate  vein,  and  the  right  in  the 
corresponding  situation  on  the  right  side  ;  or  the  two  ducts  maj'  unite  at  the  root  of  the  neck, 
and  open  into  the  left  innominate  vein.  (2)  The  reduplication  may  be  incomplete.  Thus:  {a) 
The  duct  may  at  first  be  single,  but  divide  into  two  separate  vessels  at  a  variable  distance  from 
its  termination,  and  then  (i)  one  branch  of  the  duct  may  enter  the  left  confluence  of  veins  at  the 
root  of  the  neck  ;  the  other  the  right  confluence,  a  normal  condition  in  some  animals ;  or  one 
may  enter  the  confluence  of  veins  in  the  normal  manner,  the  other  either  the  subclavian  or  inter- 
nal jugular  vein  ;  or  (ii)  the  two  branches  may  reunite — this  is  a  frequent  variety,  and  is  regarded 
as  a  normal  condition  by  some  anatomists,  {h)  It  maj'  break  up  into  several  branches  in  its 
course  throuafh  the  thorax,  forming  a  plexus  of  vessels,  which  subsequently  reunite  into  a  single 
duct.  (3)  The  thoracic  duct  may  lie  altogether  to  the  left  side  of  the  aorta,  and  terminate  as 
normal.  (4)  The  duct  may  open  into  the  confluence  of  the  subclavian  and  internal  jugular  veins 
on  the  right  side,  an  abnormal  arrangement  which  may  occur  under  the  following  conditions  : — 
(fl)  when  the  viscera  are  transposed  ;  (6)  when  there  is  a  right  aortic  arch  without  transposition 
of  vi-scera ;  and  (c)  when  the  vessels  and  viscera  are  normal.  (5)  The  duct  may  end  in  the 
vena  azygos  major. 


THE  LYMPHATICS  OF  THE  ABDOMEN  AND  PELVIS 

The  lymphatics  of  the  abdomen  and  pelvis  may  be  divided  into  the  parietal, 
which  ramify  in  the  abdominal  and  pelvic  w^alls;  and  the  visceral,  which  receive 
the  lymph  from  the  pelvic  viscera,  and  the  lymph  and  chjde  from  the  abdominal 
viscera. 


I.     THE    PARIETAL    LYMPHATIC    VESSELS   AXD    GLANDS 
OF   THE  ABDOMEN  AND  PELVIS 

1.  The  parietal  lymphatic  vessels  may  be  subdivided  into  the  superficial, 
which  ramify  beneath  the  skin  in  the  subcutaneous  tissue,  and  include  the 
lymphatics  of  the  skin  of  the  penis  and  scrotum  and  of  the  external  genital 
organs  in  the  female;  and  into  the  deep,  which  accompany  the  deep  arteries  of  the 
abdominal  and  pelvic  walls.  The  former  for  the  most  part  end  in  the  superficial 
inguinal  glands;    the  latter  in  the  lumbar  glands. 

(1)  The  superficial  parietal  lymphatics. — The  sui)erficial  parietal  lymphatics 
of  the  abdominal  walls  are  situated  betwec^n  tlie  skin  and  the  abdominal  muscles. 
Those  from  the  front  of  the  abdomen,  below  the  level  of  the  umbilicus,  ])ass  down- 
wards along  the  course  of  the  superficial  epigastric  artery  and  veins,  and  end  in  the 
superficial  inguinal  glands.  The  lymphatics  from  the  upper  part  of  the  front  of 
the  abdomen,  above  the  level  of  the  umbilicus,  pass  upwards  and  outwards  with 
the  lymphatics  from  the  front  and  side  of  the  chest  to  the  axillary  glands.  The 
lymi)hatics  from  the  lateral  abdominal  walls  run,  in  part  over  the  crest  of  the 
ilium,  in  the  course  of  the  superficial  circumflex  iliac  artery  and  veins,  into  the 
outer  superficial  inguinal  glands,  and  in  part  follow  the  course  of  the  lumbar  and 
ilio-lumbar  arteries,  and,  after  perforating  the  al)dominal  muscles,  end  in  the  lateral 
lumbar  glands.  The  suj)erficial  lymphatics  from  the  lower  part  of  the  back  and 
from  the  gluteal  region  for  the  most  part  pass  outwards  over  the  gluteal  muscles 
to  end  in  the  outermost  superficial  inguinal  glands;    but  those  from  the  region  of 


LYMPHATICS   OF  ABDOMEN  AM)   PELVIS  661 

the  unus  follow  the  course  of  the  periiueul  lyiii})liutics  through  the  fork  to  the  inuer- 
niost  superlieial  inguinal  glands. 

The  superficial  lymphatics  of  the  penis  hegin  in  the  prepuce,  and  thence  pass 
hackwards  to  the  corona  glandis,  where  they  form  a  ring  arountl  the  glans.  This 
ring  receives  the  su})erticial  lynipliatics  from  the  glans,  and  the  lynnjhatics  from 
the  anterior  two-thirds  of  the  urethra  which  run  from  hehind  forwards.  From  the 
glans  three  main  lymphatic  channels  run  hackwards  under  the  integuments  of  the 
penis,  one  on  the  dorsum,  and  one  on  each  side  of  the  organ.  At  the  root  of  the 
penis  the  dorsal  lym|)hatic  vessel  divides  into  a  right  and  a  left  branch,  each  branch 
passing  with  the  lateral  lymphatic  vessel  of  the  corresi)onding  side  to  the  superficial 
inguinal  glands.  The  deep  h'mphatics  of  the  penis  pass  with  the  dorsal  vein  m\o 
the  ]»('lvis,  where  they  join  the  lymphatic  glands  about  the  internal  iliac  arten,'. 

The  lymphatics  of  the  scrotum  in  the  male,  and  of  the  parts  corresponding 
thereto  in  the  female,  and  the  lymphatics  of  the  other  external  generative  organs 
in  the  female,  run  with  the  superticial  external  i>udic  arteries  to  the  superficial 
inguinal  glands.  It  will  be-noted  that  the  lymphatics  of  the  testicle  pass  with  the 
spermatic  artery  to  the  lumbar  glands. 

The  superficial  lymphatics  of  the  perinaeum  run  upwards  over  the  adductor 
muscles,  through  the  fork  Ijrtweeii  tht-  thighs,  and  join  the  superficial  inguinal 
glands. 

(2  )  The  deep  parietal  lymphatics. — The  deep  lymphatics  of  the  anterior  and 
lateral  abdominal  walls  accompany  the  parietal  vessels  to  the  back  of  the  abdomen, 
where  they  end  in  the  deep  glands.  Thus  some  follow  the  deep  epigastric  artery  to 
the  external  iliac  glands;  others  the  deep  circumflex  iliac  artery  also  to  the  external 
iliac  glands;  and  others,  again,  the  ilio-lumbar  and  lumbar  arteries  to  the  lateral 
lumbar  glands.  The  last  are  also  joined  by  the  lymphatics  from  the  muscles  of  the 
back  and  from  the  spinal  cord.  The  deep  lymphatics  from  the  ui)per  part  of  the 
abdominal  wall  pass,  with  the  superior  epigastric  artery,  into  the  thorax,  where 
they  end  in  the  internal  mammary  lymphatic  glands. 

The  deep  lymphatics  of  the  pelvic  walls  accompany  the  parietal  vessels,  and 
hence  are  found  with  the  obturator,  sciatic,  gluteal,  pudic,  and  sacral  arteries. 
They  end  in  the  glands  surrounding  the  internal  iliac  artery,  and  in  the  sacral  glands. 

2.  The  parietal  lymphatic  glands  lie,  for  the  most  part,  along  the  back  of  the 
abdomen  and  pelvis,  and  are  known,  from  their  position,  as  the  external  iliac,  internal 
iliac,  sacral,  lumbar,  and  cceliac  glands. 

The  external  iliac  lymphatic  glands  lie  along  the  course  of  the  external  iliac 
and  connnon  iliac  arttrit-s  an<l  veins.  They  are  three  to  five  or  more  in  numl)er. 
They  receive  the  lymphatics  from  the  inguinal  glands  and  femoral  glands,  and 
the  deep  lymphatic  vessels  accompanying  the  deep  epigastric  and  deep  circum- 
flex iliac  arteries  and  veins  from  the  anterior  and  lower  abdominal  walls.  Their 
efferent  vessels  join  the  lumbar  glands.  They  communicate  with  the  internal  iliac 
glands. 

The  internal  iliac  glands  are  situated  in  the  course  of  the  internal  iliac  artery 
and  its  branches.  They  vary  from  nine  to  twelve  or  more  in  number,  the  largest 
being  situatetl  at  the  upper  part  of  the  great  sciatic  foramen.  They  receive  the 
lymphatics  from  the  muscles  of  the  pelvis  and  the  lymi)hatics  corresponding  to  the 
branches  of  the  internal  iliac  artery.  Thus  the  greater  number  of  the  ]ymi)hatics 
from  the  pelvic  viscera,  from  the  deeper  j)arts  of  the  perina-um,  and  from  the 
hinder  and  deeper  parts  of  the  scrotum  or  labia  majora,  the  deejt  lymphatics  of  the 
penis  and  posterior  part  of  the  urethra,  the  deep  lymphatics  from  the  gluteal 
region,  and  some  of  the  lymphatics  from  the  adductor  muscles  of  the  upper  i»art 
of  the  thigh,  join  these  glands.     Their  efferent  ves.sels  pass  to  the  lumbar  glands. 

The  sacral  glands  are  situated  in  the  hollow  of  the  sacrum,  four  or  five  being 
placed  in  the  meso-rectal  fohls  op))Osite  its  promontory.  They  receive  the  lym- 
phatics from  the  rectum  and  the  hinder  walls  of  the  pelvis.  They  join  the  lumbar 
glands. 

The  lumbar  glands  lie  beneatli  the  peritoneum,  at  the  back  of  the  abdomen, 
on  the  front  and  sides  of  the  lumbar  vertebra.  They  are  usually  divided  intotliree 
groups,  a  median  and  two  lateral;  but  these  freely  connnunicate  witii  one  another 
across  the  aorta  and  vena  cava. 


( 


662  .  THE  LYMPHATICS 

The  median  group  (  aortic  lumbar  glands  i  consit^ts  (»f  about  six  large  glands 
placed  along  the  abdominal  aorta  and  vena  cava.  They  extend  from  the  bifurcation 
of  the  aorta  to  the  second  luml)ar  vertebra. 

The  median  group  receive  the  efferent  vessels  of  the  external  and  internal  iliac 
and  sacral  glands,  the  lymphatics  accompanying  the  spermatic  or  ovarian  vessels 
from  the  testicle  or  ovarian  plexus  respectively,  and  the  lymphatics  of  the  kidneys, 
suprarenal  bodies,  and  hinder  portion  of  the  diaphragm.  They  also  receive  most 
of  the  efferent  vessels  from  the  lateral  sets.  Their  efferent  vessels  commonly  unite 
about  the  level  of  the  second  lumbar  vertebra  to  form  a  right  and  a  left  lumbar 
lymphatic  trunk,  which  open,  with  some  small  vessels  from  the  lateral  sets,  into 
the  receptaculum  chyli.  The  left  lumbar  trunk  also  receives  the  lymphatics  of  the 
descending  colon  and  sigmoid  flexure. 

The  lateral  lumbar  glands,  transverse  lumbar  or  psoas  glands,  are  situated 
behind  the  psoas  between  the  transverse  processes  of  the  lumlxir  vertebrae.  They 
are  twenty  or  thirty  in  number,  and  smaller  than  the  glands  of  the  central  group. 
The  lateral  glands  receive  the  lymphatics  accompanying  the  lumhar  arteries, 
the  lymphatics  from  the  muscles  of  the  back,  the  spinal  canal,  and  from  the  deeper 
parts  of  the  parietes  of  the  posterior  abdominal  walls.  Their  efferent  vessels  0]jen, 
in  part  into  the  median  set,  and  in  part,  as  separate  vessels,  into  the  receptaculum 
chyli. 

The  coeliac  glands,  sixteen  to  twenty  in  number,  are  grouped  around  the  coeliac 
axis  in  front  of  the  aorta,  above  the  origin  of  the  superior  mesenteric  artery.  At 
the  back  of  the  transverse  meso-colon  they  receive  the  efferent  vessels  from  some 
of  the  hepatic  glands,  the  superior  gastric  glands,  the  inferior  gastric  glands,  the 
splenic  and  the  pancreatic  glands.  Their  efferent  vessels  join  the  intestinal  lymphatic 
trunk,  and  open  into  the  receptaculum  chyli. 


II.    THE   VISCERAL   LYMPILiTIC   VESSELS  AXD   GLAXDS   OF 
THE  ABDOMEN  AND   PELVIS 

The  lymphatics  of  the  pelvic  and  abdominal  viscera  are  considered  separately. 

1.  The  lymphatics  of  the  pelvic  viscera. — The  lymphatics  of  the  bladder 
pass  partly  backAvards,  beneath  the  peritoneum,  to  join  the  rectal  lymphatics,  or 
the  lymphatics  of  the  uterus  and  vagina  in  the  female;  and  partly  forwards,  to 
join  the  prostatic  lymphatics  and  the  lymphatics  of  the  vesiculse  seminales.  These 
anterior  sets  of  lympliatics.  together  with  tliose  from  the  prostate  and  vesiculee 
seminales,  pass  through  the  anterior  true  ligaments  of  the  bladder,  in  which  there 
is  a  small  gland,  into  the  internal  iliac  lymphatics. 

The  lymphatics  of  the  rectum  run  backwards  between  the  two  layers  of  the 
meso-rectum,  in  which  tliere  are  four  or  five  glands,  through  the  sacral  to  the 
luml)ar  glands.  At  the  lower  part  of  the  rectum  the  lymphatics  become  continuous 
with  the  cutaneous  lymphatics  round  the  anus,  and  for  this  reason  disease  of  the 
lower  part  of  the  bowel  involves  the  inguinal  glands. 

The  lymphatics  of  the  uterus,  vagina,  ovaries,  and  Fallopian  tubes. — 
The  su})crtici;d  lympliatics  of  the  uterus,  whicli  lie  l)eneath  tlie  i)eritoneuni,  pass, 
together  with  those  of  the  substance  of  the  fundus  and  upj)er  part  of  the  body  of 
the  organ,  outwards,  in  the  broad  ligament,  wliere  they  join  the  lymphatics  from 
the  ovaries  and  Fallopian  tubes,  and  pass  up,  with  the  ovarian  vessels,  to  the 
lumbar  glands.  The  lymphatics  from  the  lower  part  of  the  body  and  from  the 
cervix  of  the  uterus  run,  together  with  most  of  the  lymphatics  of  the  vagina,  along 
the  course  of  the  uterine  and  vaginal  vessels,  and  terminate  in  the  internal  iliac 
glands.  The  Ijunphatics  from  the  lower  part  of  the  vagina  join  the  superficial 
inguinal  glands. 

The  lymphatics  of  the  testicle  accompany  the  spermatic  vessels,  and  terminate 
in  the  lumbar  glands  situated  immediately  below  the  renal  arteries.  Hence  in 
carcinoma  of  the  testicle  the  lumbar  glands  are  those  which  first  become  enlarged, 
the  inguinal  not  being  affected  until  the  skin  of  the  scrotum  becomes  involved  in 
the  disease. 

2.  The  lymphatics  of   the  abdominal   viscera  are   divided    into — fl)  The 


LYMPHATICS   OF  ABDOMEN  AM)   PELVIS 


663 


lymphatics  of  the  stomach;  (2)  the  intestines;  (3)  the  liver;  (4)  tlie  sj^leen; 
(5)  the  pancreas;  (6)  the  kidneys;  (7)  the  ureters;  and  (8)  the  suprarenal 
capsules. 

(1)  The  lymphatics  of  the  stomach  begin  in  the  mucous  and  subserous  coat, 
and  thence  follow  the  course  of  the  blood-vessels.  Thus  some  run  upwards  to  the 
lesser  curve  of  the  stomach,  others  downwards  to  the  greater  curve,  and  others  left- 
wards to  the  greater  end.  Iw  this  way,  three  chief  sets  are  formed — the  sujx-rior 
gastric,  the  inferior  gastric,  and  the  left  gastric  lymphatics,  {a)  The  superior 
gastric  follow  the  course  of  tlie  coronary  vein  along  the  lesser  curvature  towards  the 
cardiac  end  of  the  stomach,  lying  between  the  layers  of  the  lesser  omentum.  They 
pass  on  their  way  through  five  or  six  small  (superior  gastric)  lymphatic  glands. 
Reaching  the  cardia,  they  turn  downwards,  and,  having  been  joined   by  some  of 


Fig.  399b. — Diagram  of  the  Arrangement  of  the  Lymphatics  of  the  Uterus,  Fallopian 
Tubes,  Ovaries,  Vagina,  and  External  Vulva.  (Alter  Drawiug  by  Dr.  Francis  R. 
Sherwood.) 

Lumbar  glands 


Internal 
Iliac  glands 


Superficia 
Femoral  Glands 


the  lymjihatics  from  the  left  lolie  of  the  liver,  enter  the  upper  coeliac  glands. 
(h)  The  inferior  gastric  lymphatics  follow  the  course  of  the  right  gastro-epiploic 
vessels  towards  the  i)ylorus,  along  the  greater  curv'ature  of  the  stomach,  between 
the  layers  of  the  greater  omentum.  After  passing  through  six  or  eight  small  glands 
(inferior  gastric),  they  are  joined  by  the  lymphatics  from  the  upper  part  of  the 
duodenum,  and  run  between  the  pylorus  and  pancreas  to  the  cneliac  glands,  (c)  The 
left  gastric  lymphatics  run  with  the  vasa  brevia,  between  the  folds  of  the  gastro- 
.-pleiiic  omentum,  to  the  splenic  lymphatic  glands. 

The  lymphatic  glands  of  the  stomach  are  the  superior  and  inferior  gastric 
glands. 

The  superior  gastric  glands,  five  or  six  in  number,  are  situated  along  the 
lesser  curve  between  the  layers  of  the  gastro-hepatic  omentum.  They  receive  the 
sui)erior  gastric  lymphatics;  their  efferent  ducts  pass   first  upwards  towards  the 


664  THE  LYMPHATICS 

oesophagus,  and  then,  after  receiving  tlie  lymphatics  from  the  up])erand  left  portion 
of  the  left  lobe  of  the  liver,  turn  downwards  behind  the  pancreas  to  join  the  coeliac 
glands. 

The  inferior  gastric  or  gastro-epiploic  glands,  six  or  eight  in  number,  lie 
along  the  greater  curve  of  the  stomach  Ijctwcen  the  layers  of  the  great  omentum. 
They  receive  the  inferior  gastric  lymphatics  and  the  lympliatics  of  the  great  omen- 
tum. Their  efferent  vessels  pass  with  the  lym^jhatics  from  the  ui)])er  jjart  of  the 
duodenum  into  the  coeliac  glands. 

(2)  The  lymphatic  vessels  of  the  intestine  are  divided  into  the  lymphatics 
of  the  small  intestine  and  the  lymphatics  of  the  large  intestine. 

The  lymphatics  of  the  small  intestine  are  called  the  lacteals,  because  they 
carry  the  cliyle  as  well  as  the  lymph  from  the  intestinal  walls.  Beginning  })artly 
beneath  the  peritoneal  coat — but  chietly  in  two  plexuses,  one  between  the  muscular 
coats,  and  one  beneath  the  mucous  membrane — they  pass  round  the  intestine  with 
the  blood-vessels  to  the  mesenteric  attachment,  and  thence  between  the  layers  of  the 
mesentery  to  the  mesenteric  glands. 

The  lymphatics  of  the  large  intestine  are  disposed  of  as  follows: — (a)  Those 
from  the  ca.^cum  and  ascending  colon  pass  between  the  layers  of  the  meso-colon  to 
the  meso-colic  glands,  (ft)  Those  from  the  transverse  colon  and  upper  half  of  the 
descending  colon  pass  with  the  middle  colic  artery  between  the  layers  of  the  meso- 
colon, also  to  the  meso-colic  glands,  (c)  Those  from  the  lower  half  of  the  descend- 
ing colon  and  sigmoid  flexure  pass  into  the  left  lymphatic  trunk  of  the  lumbar 
glands.  The  lymphatics  of  the  rectum  are  described  with  the  lymjihatics  of  the 
pelvis  (page  iWyl ). 

The  lymphatic  glands  of  the  intestines  are  the  mesenteric  and  meso-colic. 

The  mesenteric  glands,  some  one  hundred  and  tift}'  to  two  hundred  in  number, 
lie  l)etween  the  layers  of  the  mesentery.  They  are  arranged  roughly  in  three  sets: 
(a)  A  primary  set,  about  two  inches  from  the  intestinal  margin  of  the  mesentery, 
receive  the  lymphatics  from  the  intestine.  The  efferent  vessels  from  these  glands 
pass  into  the  next  or  secondary  set.  (ft)  The  secondary  set  are  situated  about  the 
primary  loops  of  the  superior  mesenteric  artery;  they  are  more  numerous  than  the 
primary  set,  and  receive  the  efferent  vessels  of  the  latter.  Their  efferent  vessels 
end  in  the  tertiary  set.  (c)  The  tertiary  set  of  glands  lie  along  the  course  of  the 
trunk  of  the  superior  mesenteric  artery.  They  are  larger  than  the  secondary  set, 
and  closer  together.  Their  efierent  vessels  unite  to  form  three  or  four  trunks,  or 
perhaps  more  often  a  single  trunk  (the  intestinal  lymphatic  trunk)  wdiich,  after 
receiving  the  efferent  vessels  from  the  meso-colic  glands,  oj)ens,  either  separately, 
or  together  with  the  efferent  ducts  of  the  coeliac  glands,  into  the  receptaculum  chyli. 

The  glands  and  lacteals  of  the  jejunum  are  more  numerous  than  those  of  the 
ileum. 

The  meso-colic  glands,  twenty  to  thirty  in  numl)er,  are  placed  between  the 
layers  of  the  meso-colon.  They  receive  the  lymphatics  from  the  ca?cum,  ascending 
and  transverse  colon,  and  from  part  of  the  descending  colon.  Their  efferent  vessels 
join  the  efferent  vessels  from  the  tertiary  set  of  mesenteric  glands,  and  open  with 
them  into  the  receptaculum  chyli. 

(3)  The  lymphatics  of  the  liver  consist  of  a  superficial  and  deep  set.  The 
former  are  arranged  in  a  plexus  beneath  the  peritoneal  covering;  the  latter  accom- 
pany the  blood-vessels  in  the  substance  of  the  organ. 

(a)  The  superficial  set  of  lymphatics  form  groups,  and  run  in  various  direc- 
tions. Those  on  tlic  upper  or  convex  surface  of  the  liver  are  disposed  of  as 
follows: — (i)  The  lymphatics  of  the  left  half  of  the  right  lobe,  and  of  the  right  half 
of  the  left  lobe,  converge  towards  the  falciform  ligament,  U])  which  they  run  to  the 
diaphragm.  They  then  pass  through  the  costo-xi])lioid  s])ace,  and  enter  the 
anterior  mediastinal  chain  of  glands,  and  thus  open  in  part  into  the  right  lymphatic 
duct,  (ii)  The  lymphatics  on  the  anterior  part  of  the  convex  surface  pass  over 
the  anterior  margin,  and  along  the  course  of  the  longitudinal  fissure  to  the  he})atic 
glands  in  the  gastro-hepatic  omentum,  (iii)  The  lymphatics  along  the  posterior 
margin  of  the  liver  pass  between  the  layers  of  the  coronary  ligament  to  the  dia- 
phragm, which  they  perforate,  and  end  in  small  glands  about  the  u])])er  part  of  the 
vena  cava  (Quain).      (iv)  A  group  from  the  right  half  of  the  right  lobe  pass  out- 


LYMPHATICS   OF  ABDOMEN  AXD   PELVIS  665 

AViirds  and  l)ac'k\vards  to  tlie  right  lateral  ligament,  where  they  either  perforate  the 
diaphragm  and  end  in  the  anterior  mediastinal  glands,  or  cross  its  erus  and  o])en 
into  the  coeliac  glands  or  receptaculum  chyli.  (v)  A  group  from  the  left  half  of 
the  left  lobe  pass  througii  the  left  lateral  ligament,  and  join  the  a^sophageal  lym- 
phatics at  the  (jesophageal  opening  of  the  diaphragm,  or  pass  with  the  superior 
gastric  lymphatics  behind  the  pancreas  to  the  cadiac  glands.  Or  they  may  pierce 
the  diaphragm  and  enter  the  glands  in  the  anterior  mediastinum. 

The  superficial  lymphatics  on  the  under  surface  of  the  liver  are  arranged 
as  follows: — (i)  The  greater  numl)er  converge  to  the  transverse  fissure,  and  thence 
pass  with  the  deep  lym})hatics  to  the  hepatic  glands  in  the  gastro-hepatic  omentum; 
(ii)  a  group  from  the  l)ack  of  the  right  lobe  pass  to  the  lumbar  glands;  (iii)  a  group 
from  the  back  of  the  left  lol)e  join  the  CESOphageal  lym])haties  or  superior  gastric 
lym{)hatics,  and  end  with  them  in  the  coeliac  glands;  (iv)  the  lymphatics  of  the 
gall-bladder  run  with  the  hepatic  artery  to  the  hepatic  glands  in  the  gastro-hei)atic 
omentum. 

(b)  The  deep  set  of  lymphatics  run,  in  part  with  the  portal  vein,  and  in  part 
with  the  hepatic  vein,  (i)  The  portal  set  emerge  at  the  transverse  fissure,  and 
pass  with  the  blood-vessels  to  the  hepatic  glands  in  the  gastro-hepatic  omentum, 
(ii)  The  hepatic  set  perforate  the  diaphragm  with  the  inferior  vena  cava,  and, 
having  passed  through  some  small  glands  round  the  upper  part  of  that  vessel,  join 
the  superficial  lymphatics  from  the  posterior  margin  of  the  liver,  and  with  them 
run  down  the  thoracic  surface  of  the  vertebral  portion  of  the  diaphragm  to  the 
connnencement  of  the  thoracic  duct  or  receptaculum  chyli. 

The  hepatic  glands  are  situated  in  front  of  the  portal  vein  between  the  layers 
of  the  gastro-hepatic  omentum.  They  receive  the  deej)  portal  set  of  lymphatics, 
the  anterior  group  of  the  superficial  lymphatics  from  the  convex  surface  of  the 
liver,  most  of  the  superficial  lymphatics  from  the  under  surface  of  the  liver,  and 
the  lymphatics  from  the  gall-bladder.  Their  efferent  vessels  proceed  to  the  cceliac 
glands. 

(4)  The  lymphatics  of  the  spleen. — The  si)lenic  lymphatics  are  arranged  in 
a  su])erficial  set  which  ramify  beneath  the  peritoneal  covering;  and  in  a  deep  set, 
Avhich  run  with  the  vessels  in  the  parenchyma  of  the  organ.  Both  sets  unite  at 
thehilum,  and  terminate  in  the  splenic  glands. 

The  splenic  glands,  eight  to  ten  in  number,  are  situated  in  the  hilum  of  the 
spleen,  and  along  the  course  of  the  splenic  artery  and  vein.  They  receive  the 
su})erficial  and  deep  lymphatics  of  the  spleen,  and  the  left  gastric  lymphatics  wdiich 
run  with  the  vasa  brevia  in  the  gastro-splenic  omentum  from  the  greater  end  of 
the  stomach.  The  efferent  vessels  run  behind  the  peritoneum  and  pancreas  with 
the  splenic  artery  to  the  coeliac  glands.  They  are  joined  on  the  Avay  by  the 
lymphatics  of  tin-  jiancreas. 

(5)  The  lymphatics  of  the  pancreas  consist  of  a  double  set,  a  superficial  and 
a  deep.  They  leave  the  pancreas  along  with  the  vessels  derived  from  the  splenic 
artery,  and,  j(Mningthe  lymphatics  of  the  spleen,  end  in  the  coeliac  glands. 

(6)  The  lymphatics  of  the  kidneys  ramify,  partly  on  the  surface,  and  partly 
in  the  substance  of  the  organ.  They  unite  at  the  hilum,  and  run  inwards  to  the 
central  set  of  luml)ar  glands,  situated  immediately  in  front  of  the  renal  vessels. 
They  receive  the  lymphatics  from  the  suprarenal  bodies  and  from  the  upper  jiart 
of  the  ureters. 

(7)  The  lymphatics  of  the  ureters  end  chieHy  in  the  renal  lymphatics.  Those 
from  the  lower  part  join  the  posterior  vesical  set  of  lym])hati<'S. 

(H)  The  suprarenal  lymphatics  leave  the  su])rarenal  l)odies  with  the  supra- 
renal veins,  and  join  for  the  most  i)art  the  renal  lym]ihati('S  in  the  hilum  of  the 
kidneys.     A  few  pass  direct  into  the  central  luml)ar  chain  of  glands. 


666 


THE  LYMPHATICS 


Fig.  400.-THE  Superficial  Lymphatics  of  the  Left  Lowee  Limb.     (Walsham.) 


Superficial  epigastric  vein 


Lympluitics  from  penis  and 
scroliim 
Common  frniornl  vein 

Superficial  femoral  lymphatic 

gUiiuli 
Superficial  external pudic  vein 


Internal  femoral  cutaneous  vei 


Long  saphenous  vein 


INTERNAL  MALLEOLUS 
Dorsal  venous  arch 


Superficial  lymphatics  from 
lateral  wall  of  abdomen 

Superficial  lymphatics  from 
lower  and  anterior  walls 
of  abdomen 


Superficial  inguinal 

lymphatic  glands 

Superficial  circumflex 

iliac  reiil 


I^iternal  femoral 
cutaneous  vein 


LYMPHATICS  OF  LOWER  EXTREMITY  667 


THE  LY2IPHATICS  OF  THE  LOWER  EXTEEJIITY 

The  lymphatics  of  the  lower  extremity,  like  those  of  the  upper,  may  be 
divided  into  the  superficial  and  thedeej).  The  former  run  in  the  subcutaneous  tissue 
with  the  superficial  veins,  the  latter  along  the  course  of  the  deep  arteries.  At  the 
groin  the  superficial  end  in  the  deep,  which  then  pass  under  Poupart's  ligament 
into  tlie  abdomen. 


I.    THE  SUPERFICIAL   LYMPHATIC   VESSELS  AND   GLANDS   OF 
THE  LOWER  EXTREMITY 

The  superficial  lymphatic  vessels  follow  in  chief  part  the  long  and  short 
saphenous  veins.  Passing  from  the  toes  to  a  plexus  on  the  dorsum  and  sole  of  the 
foot  respectively,  they  thence  run  up  the  leg,  forming  two  chief  sets  of  lymphatic 
vessels,  an  inner  and  an  outer.  The  inner  and  larger  accompanies  the  long 
saphenous  vein  in  front  of  the  ankle,  l)ehind  the  inner  side  of  the  knee,  and  then  up 
the  inner  and  front  part  of  the  thigh  to  the  inguinal  glands.  The  outer  set, 
beginning  on  the  outer  side  of  the  foot,  run  up  the  outer  side  of  the  leg,  some 
passing  round  the  front  of  the  tibia  to  end  in  the  inner  set  below  the  knee;  others 
passing  over  the  popliteal  space  to  join  the  inner  set  higher  in  the  limb;  and 
others,  again,  perforating  the  deep  fascia  along  with  the  short  saphenous  vein  to 
end  in  the  popliteal  glands. 

The  lymphatics  of  the  gluteal  region  wind,  in  part  round  the  inner  side  of 
the  thigli,  ovtn-  the  ujjper  portion  of  the  adductors,  to  join  the  innermost  inguinal 
glands;  and  in  part  over  the  crest  of  the  ilium  to  join  the  outermost  inguinal  glands. 
On  this  account  it  is  not  uncommon  to  find  tliat  an  abrasion  caused  V»y  wearing  an 
ill-fitting  truss  results  in  an  abscess  in  tlie  inguinal  region. 

The  superficial  lymphatic  glands. — There  are  no  superficial  glands  below 
the  inguinal. 

The  inguinal  glands,  six  to  twelve  in  number,  are  situated  in  the  inguinal 
region.  They  may  be  subdivided  into  the  oblique,  or  inguinal  projaer,  Avhicli  are 
grouped  along  the  course  of  Poupart's  ligament;  and  the  vertical,  or  femoral,  or 
saplienous,  which  surround  the  saphenous  opening. 

The  oblique  or  inguinal  glands  proper,  which  are  situated  on  a  higher  level 
than  the  vertical  set,  receive  tlic  lympliatics  from  the  integuments  of  the  penis  and 
scrotum,  and  the  skin  of  the  ]Uidenda  and  lower  part  of  the  vagina  in  the  female. 
They  also  receive  the  lymphatics  from  the  integuments  of  the  lower  part  of  the 
abdomen,  and  that  covering  the  perinatal  and  gluteal  regions.  Their  efferent  vessels 
in  part  pass  through  the  saphenous  opening,  and  in  part  perforate  the  deep  fascia 
to  end  in  tlie  deep  inguinal  and,  to  some  extent,  in  the  lumbar  glands.  It  is  these 
superficial  inguinal  glands  wliich  become  enlarged  in  venereal  disease,  in  chancres 
and  epithelioma  of  the  penis  and  scrotum,  or  labia  in  the  female,  and  in  boils  or 
other  sources  of  irritation  about  the  anus,  gluteal  region,  and  ]>erin.Tum. 

The  vertical  set,  or  saphenous  or  superficial  femoral  glands,  receive  the 
superficial  lymi)hatics  from  the  lower  limb.  They  are  found  enlarged  in  sores  on 
the  heel,  malignant  disease  of  the  skin,  etc. 


II.    THE  DEEP  LYMPHATIC  VESSELS  AND  GLANDS  OF  THE 
LOWER  EXTREMITY 

The  deep  lymphatic  vessels  of  the  lower  limb  follow  the  course  of  the  deep 
arteries  and  veins.  Thus  tliey  accom])any  tlie  internal  and  external  plantar  arteries 
in  the  sole,  and  the  dorsalis  pedis  artery  on  tlie  dorsum  of  the  foot.  In  the  leg 
they  are  found  following  the  posterior  tibial,  anterior  tibial,  and  ])eroneal  arteries, 
and,  after  passing  through  the  lymphatic  glands  in  the  popliteal  space,  accompany, 


668 


THE   LYMPHATICS 


first,  the  popliteal,  and  then  the  femoral  artery  up  the  thigh  to  the  deep  incruinal 
or  deep  femoral  glands.  Deep  lymphatics  also  run  with  the  profunda  artery.  These 
also  join  the  deep  femoral  lympliutic  glands.  Others  accompany  the  gluteal  and 
ischiatic  artery,  and  end  in  the  lymphatic  glands  of  the  same  name  at  the  great 
sciatic  foramen. 

The  deep  lymphatic  glands  of  the  lower  extremity  are  met  with  chiefly  in 
the  p(jpliteal  Sjjace  and  in  thi^  inguinal  region.  One.  or  .sometimes  two,  small 
glands,  however,  may  be  found  in  the  upper  yjart  of  the  front  of  the  leg,  h'ing  on 
the  interosseous  meml)rane  along  the  course  of  the  anterior  tibial  artery. 

The  popliteal  glands  are  placed  deep  in  the  popliteal  space  around  the  popliteal 


Fig.  400a.— Diagram  of  the  Superficial  and  Deep  Lymphatic  Vessels  and  Glaxds  of 
THE  Lower  Extremity,  including  the  Superficial  Lymphatics  of  the  Exteexal 
Genitals  and  the  Lymphatics  of  the  Gluteal  and  Lschial  Regions.  (After  Draw- 
ing by  Dr.  Francis  li.  -Sherwdorl.) 

Ef'erent  vessels  to  ext.  Iliac  glands 


Superficial  Lymphatics  of  Abdomi 
Lymphatics  of  Urethra  and  Vagin 

Perineal  and  Gluteal  Lymphatics 
Lymphatics  of  Penis  and  Scrotum 


Superficial  Inguinal 
Oblique  set  8  to 


Superficial  Ingu 
Vertical 


Internal  group 
External  group 


Deep  Lymphatics  of  leg  and  outer  side  of  foot 


'  Deep  g'jteal  L/mphatics 


Deep  ischial  L>mphat;cs 


artery  and  vein,  and  are  about  five  in  niniil)er.  They  receive  the  deep  lymphatics 
from  the  leg,  and  those  of  the  superficial  which  perforate  the  deep  fascia  along  with 
the  external  saphenous  A'cin.  Their  efterent  vessels  accompany  the  popliteal  and 
the  femoral  vessels  to  the  deep  inguinal  or  femoral  glands. 

The  deep  inguinal  or  deep  femoral  glands  surround  the  upper  jjart  of  the 
femoral  vessels.  One  or  more  are  constantly  found  in  the  femoral  canal.  They 
receive  the  deep  lymphatics  accompanying  the  femoral  artery,  and  a  few  of  the 
efferent  vessels  from  the  superficial  inguinal  glands.  Their  efferent  vessels  pass,  in 
part  along  the  course  of  the  femoral  vessels,  and  in  part  through  the  femoral  ring 
to  join  the  glands  along  the  course  of  the  external  iliac  artery. 


( 


SECTIOlN^    Y 

THE  i^EKYOUS  SYSTEM 

By  H.  ST.  JOHN  BROOKS,  M.D.,  B.Ch.,  D.Sc,  B.A. 
Revised  for  Second  Edition  by  ARTHUE  ROBINSON,  M.D.,  M.R.C.S.England 

LE(.TURER  ON  ANATOMY  IN   THE  MIDDLESEX   HOSPITAL  MEDICAL  SCHOOL;   EXAMINER   IN   ANATOMY  FOR  THE  CONJOINT 

BOARD  OF  ENGLAND 


^''FUEOLOGY 

nVTEUROLOGY  is  that  branch  of  Anatomy  which  deals  with  the  nervous  system. 
I_\  It  treats  of  the  brain  and  s{)inal  cord,  constituting  the  cerebro-spinal  axis 
or  central  nervous  system  ;  the  cranial  and  spinal  nerves,  or  peripheral 
nervous  system,  and  the  sympathetic  system,  which  is  intimately  connected 
with  the  two  former  and  closely  associated  with  the  vessels,  viscera,  and  glands. 
The  study  of  the  nervous  system  (of  the  brain  in  particular)  is  greatly  facilitated 
by  a  knowledge  of  its  mode  of  development  and  by  Comparative  Anatomy.     It 

Fig.  401. — Diagrammatic  Sagittal  Section  of  a  Vertebrate  Brain.    (After  Huxley.) 

CORPORA   qUADRIGEMINA        MESEXCEPHALOX  PIXEAL  BODY 


CEREBELL UM 


MEDULLA 
OBLOXGA  TA 


POXa  VAROLII 


LA  TERA  L 

VEXTRICLE 
(JEREBRA  L 

HEMISPHERE 
CORPUS 

STRIA  TUM 
RH/XEX- 

CEPHALOX 


CRURA  CEREBRI 


OPTIC  I       riTUITARY 

THALAMUS         \  BODY 

THA  LA  MENCEPHA  LON 


FOR  AM  EX  OF  MOXRO 


4.  fourth  ventricle  ;  k,  aqueduct  of  Sylvius  ;  3,  third  ventricle. 

is  not  our  purpose  to  enter  into  these  sultjects  here;  but  an  examination  of  the 
two  diagrams  (figs.  401  and  402),  which  are  based  upon  Embryology  and  Com- 
parative Anatomy,  will  familiarise  the  student  with  the  plan  upon  which  the 
brain  is  laid  down,  and  form  a  key  to  the  complicated  structure  of  the  adult  human 
brain. 

At  an  early  period  of  embryonic  life  the  cerebro-spinal  axis  consists  simply  of 
a  thin  walled  tube,  the  neural  tube,  Avhich  becomes  enlarged  at  the  ce]»halicend  of 
the  bodv.     Constrictions  appear  on  this  enlarged  cephalic  end,  dividing  it  into  three 

669 


670 


THE  XERVOVS  SYSTEM 


vesicles,  an  anterior,  a  middle,  and  a  posterior.  The  ventricles  of  the  brain  are 
afterwards  develo})ed  from  these  three  cerebral  vesicles,  and  the  remainder  of  the 
neural  tube  forms  the  central  canal  of  the  spinal  cord.  The  substance  of  the  brain 
and  cord  is  formed  by  thickenings  of  the  wall  of  this  neural  tube.  The  terminal 
or  anterior  cerebral  vesicle  liecomes  divided  into  an  anterior  and  a  posterior  division; 
the  latter  ]:)ersistsas  tlie  third  ventricle,  which,  with  the  parts  around  it.  constitutes 
the  thalamencephalon.  The  anterior  division  is  afterwards  differentiated  into  the 
cerebral  hemispheres  or  prosencephalon.  It  becomes  at  first  indented  in  the 
mitldle  line,  and  then  eonjpletely  Inlobed.  In  this  way  two  symmetrical  cavities, 
the  right  and  left  lateral  ventricles,  are  formed. 

The  anterior  part  of  the  wall  of  the  cerebral  vesicle  1)etween  the  tAvo  lienii- 
spheres,  thus  mapped  out,  is  called  the  lamina  terminalis.  The  lamina  terminalis 
is  carried  backwards  so  as  to  l)ound  the  third  ventricle  in  front,  and  the  aperture  of 
communication  (foramen  commune  anterius),  connecting  the  third  Avith  the 
lateral  ventricles,  Vu^comes  narrowed.  The  cavity  of  the  middle  cerebral  vesicle 
becomes  the  aqueduct  of  Sylvius,  and  the  parts  developed  around  it  constitute 
the  mid-brain  or  mesencephalon.  The  cavity  of  the  posterior  cerebral  vesicle 
l)ecomes  the  fourth  ventricle,  and  its  walls  are  differentiated  into  the  cerebellum 
and  pons  Varolii  (epencephalon),  and  into  the  medulla  oblongata  (meten- 
cephalon). 

The  walls  of  the  lateral  ventricles  become  greatly  thickened  and  form  the 
cerebral  hemispheres,  constituting  the  greater  part  of  the  mass  of  the  brain.     They 


Fig.  402.— Diagrammatic  Horizontal  Section  of  a  Vertebrate  Brain.     (After  Huxley.) 

EPESCEPHALOX        OPTIC  THALAMUS 


LATERAL 

VENTRICLE 
RHINEN- 

CEPHALOS 
LA  MIS  A 

TERMINALIS 


MEDULLA 
OBLONG  A  TA 


CEREBELLUM 


CORPUS 
STRIA  TUM 


MESENCEPHA  L  ON    PINE  A  L 
BODY 


FORAMEN  OF  MONRO 


grow  backwards  from  the  position  represented  in  the  diagram  (fig.  401),  and  cover 
the  mid-  and  hind-brain.  In  front  of  the  lamina  terminalis  the  walls  of  the  lateral 
ventricles  remain  thin,  and  approximate  so  as  to  enclose  a  narrow  space,  the  fifth 
ventricle.  Thus  the  fifth  ventricle  differs  entirely  in  its  nature  from  the  other 
ventricles  of  the  brain:  it  is  a  separated  portion  of  the  interhemispheric  or  great 
longitudinal  fissure,  and  has  nothing  to  do  with  the  true  ventricular  cavities;  accord- 
ing to  Testut  it  is  lined  l)y  a  rudimentary  layer  of  jna  mater.  Later  on,  a  great 
transverse  commissure  (corpus  callosum),  which  i)asses  from  one  hemisphere  to  the 
other,  is  developed.  It  commences  in  front  of  the  fifth  ventricle  in  the  secondarily 
fused  portions  of  the  cerebral  walls,  and  afterwards  extends  backwards  as  the 
hemispheres  grow  over  the  mesencephalon. 

The  oldest  i>ortion  of  the  cerebral  hemisphere,  l)oth  in  the  scries  of  vertebrates 
and  in  the  development  of  the  individual,  is  the  island  of  Reil  with  the  grey 
masses  which  lie  sul)jacent  to  it  (nucleus  caudatus  and  nucleus  lenticularis  of  the 
corpus  striatum).  These  structures  constitutes  a  central  portion  (Stammtheil  of 
Scliwall)e)  which  is  almost  completely  invested  l)y  the  remaining  larger  ])art  of  the 
hemisphere.  The  latter  forms  th(^  less  massive  i)art  of  the  wall  of  the  lateral 
ventricle,  and  may  lie  called  the  mantle-wall  (Manteltheil  of  Schwalbe). 

The  ventricular  cavities  of  the  brain  and  the  central  canal  of  the  spinal  cord 
are  lined  by  a  layer  of  epithelial  cells,  immediately  outside  which  is  a  stratum 
of  neuroglia,  free  from  nerve-cells,  which  is  called  ependyma.  The  ependyma 
around  the  central  canal  of  the  cord  is  often  termed  substantia  gelatinosa  centralis. 


MENINGES  G71 

Neuroglia  is  tlio  name  given  to  the  peculiar  interstitial  tissue  of  the  hrain  and  cord. 
It  is  continuous  with  processes  of  pia  mater  which  di})  in  from  the  surface. 

Nerve-fibres  are  processes  or  outgrowths  of  the  nerve-cells  of  the  central 
nervous  system,  from  which  they  pass  to  he  di.stril)uted  to  every  part  of  the  hody. 
They  are  classed  by  physiologists  into  efferent  and  afferent  fibres.  Efferent  "or 
centrifugal  nerve-fibres  convey  impulses  from  the  nerve-centres;  they  comi)rise 
motor  nerves  to  muscles,  secreto-motor  nerves  to  glands  and  vaso-motor  nerves. 
Afferent  or  centripetal  nerves  convey  impulses  towards  the  nerve-centres;  they 
comprise  sensory  nerves  and  other  nerves  conveying  impulses,  which  under  ordinary 
circumstances  do  not  produce  conscious  sensations.  Xerve-fibres  run  for  the 
greater  part  of  their  course  in  com})act  bundles  ui  various  sizes,  and  these  bundles 
are  called  nerves  in  the  most  general  u.se  of  the  term.  Nerves  are  usually  n)ixed 
(i.e.  contain  Ijoth  efferent  and  afferent  fibres).  Most  nerves  are  of  a  whitish  colour 
owing  to  a  medullary  sheath  which  invests  the  essential  parts  (axis-cylinders)  of 
the  individual  fibres.  Others  (chiefly  visceral  nerves)  are  of  a  pearly-grey  colour 
owing  to  the  absence  of  the  medullary  sheath  in  the  majority  of  the  fibres  which 
make  up  the  nerve. 

The  fibres  of  sensory  nerves  are  outgrowths  from  nerve-cells  contained  in  ganglia,  such  as  the 
Gasserian  gangUon  and  the  ganglia  on  the  posterior  roots  of  the  sjiinal  nerves.  These  ganglia, 
although  appearing  to  belong  to  the  peripheral  nervous  system  in  the  adult,  were  (in  early 
embryonic  life)  in  continuity  with  the  general  epiblast  of  the  neural  canal. 

Certain  terms  which  are  in  frequent  use,  such  as  coronal,  sagittal,  and  hori- 
zontal, may  be  defined  here.  A  coronal  section  is  a  vertical  section  j^assing 
through  or  parallel  to  the  coronal  suture,  in  other  words,  a  transverse  vertical 
section.  A  sagittal  section  is  a  vertical  section  taken  at  right  angles  to  a  coronal 
section — an  antero-posterior  vertical  section.  A  horizontal  section  is  a  section 
taken  at  right  angles  to  the  perpendicular  axis  of  the  Ixtdy.  Structures  which  lie 
in  the  planes  of  these  sections  are  sometimes  spoken  of  as  coronally  placed, 
sagittally  directed,  etc. 


THE  MENINGES 

The  brain  and  spinal  cord  are  invested  by  three  membranes,  termed  the  men- 
inges, which  afford  protection  and  support  to  the  delicate  nervous  structures  and 
also  furnish  a  convenient  medium  in  which  the  blood-vessels  can  ramify.  The 
outer  of  these  is  thick  and  tough,  and  is  termed  the  dura  mater.  The  intermediate 
and  inner  membranes  (arachnoid  ;nid  pia  mater)  are  thin  and  delicate.  These 
membranes  ijresent  differences  in  tlu-  regions  of  the  l,>rain  and  spinal  cord  res])ec- 
tively.  The  membranes  of  the  brain  will  be  first  considered,  and  the  dift'erences 
met  with  in  relation  to  the  spinal  cord  will  be  dealt  with  in  the  descrij)ti<tn  of  tiiat 
region. 

Dissection. — The  first  step  in  the  examination  of  tlio  meninges  is  the  removal  of  the  brain. 
The  calvaria  shituld  be  removed  as  fdlows  : — The  Ixjiie  havinir  Ix'cn  laid  bare,  a  .string  should  be 
tied  round  the  skull  passing  fniui  about  an  inch  and  a  i|uarter  alntve  the  external  oeciiiital  pm- 
tuberanee  behind,  to  an  inch  above  the  <»r!)ital  arches  in  front.  The  outer  table  olthe  skull  .•should 
then  be  .siwn  through  and  the  inner  table  afterwards  cracked  with  the  mallet  and  chisel.  A  slight 
wrench  will  now  disengage  the  calvaria.  AfhT  noticing  the  I'acchionian  bodies  an<l  the  menin- 
geal arteries,  the  student  will  do  well  to  examine  the  superior  lonLdtmlinal  sinus  by  laying  it  open. 
He  should  next  cut  throutrh  the  dura  mater  in  an  antero-jtosterior  direction  on  each  side  of  tlie 
siims,  and  then  make  incisions  directed  transversely  outwards  from  the  central  jioints  (d'  the  two 
previous  incisions  as  far  as  the  cut  margin  of  the  bone.  The  four  triangular  flajx-^  thus  mapped 
out  sh(juld  be  turned  downwards,  and  by  gently  drawimr  one  of  the  hemispheres  aside,  the  lalx 
cerebri  may  be  seen  in  situ  within  the  L^reat  longitmlinal  fis.-ure,  and  the  veins  entering  the  .^ujierior 
longitudinal  sinus  may  be  noted.  The  falx  should  then  be  divided  dose  to  its  attaclnnent  to 
the  crista  galli  and  thrown  backwards.    The  head  should  next  be  inclined  liackwards  and  the  frontal 


672  THE  NERVOUS  SYSTEM 

lobes  of  the  brain  gently  raised.  The  following  structures  will  then  come  into  view,  viz.  the 
olfactorj'  bulbs,  the  second,  third,  and  fourth  nerves,  the  infundibuluui,  and  the  internal  carotid 
arteries.  The  olfactory  bulbs  will  come  away  with  the  brain,  but  the  other  structures  willre(|uire 
to  be  divided  with  scissors,  as  the  nerves  are  frequently  torn  away  from  their  coiniections  by  using 
a  scalpel  for  this  jiurpose.  The  head  should  next  be  gently  inclined  towards  the  right  side,  and 
the  tentorium  divided  close  to  its  attachment  to  the  bone.  The  sixth,  seventh,  and  eighth  nerves 
should  be  cut  at  the  same  time.  This  dissection  should  be  repeated  on  the  opposite  side.  The 
head  should  then  be  tilted  backwards,  and  the  remaining  cranial  nerves,  the  vertebral  arteries, 
and  the  commencement  of  the  spinal  cord  cut  through.  The  latter  should  be  divided  as  low  down 
as  it  can  be  reached  with  the  scalpel.  The  brain  can  now  be  removed  from  the  cranial  cavity,  the 
veins  of  Galen  being  ruptured  by  this  process. 

The  DURA  MATER  is  a  tough  fil)rous  membrane  of  a  blnish-Avhite  colour  pre- 
senting externally  a  rough  apj^earance,  but  internally  smooth  and  shining.  It 
performs  the  double  function  of  an  endosteum  to  the  interior  of  the  skull  and  of 
affording  support  and  protection  to  the  brain.  In  correspondence  with  this  double 
function  it  may  be  regarded  as  consisting  of  two  layers,  an  outer  or  periosteal 
lamina,  and  an  inner  or  supporting  lamina.  These  layers  are  inseparable  for  the 
greater  part  of  their  extent,  but  along  certain  lines  the  inner  lamina  leaves  the  peri- 
osteal lamina  and  forms  shelf-like  projections  (of  which  the  falx  cerebri  and  the 
tentorium  cerebelli  are  examples)  into  the  cranial  cavity.  Along  the  lines  Avhere 
these  layers  divaricate  spaces  occur  which  form  cranial  sinuses.  A  cranial  sinus 
may  be  defined  as  a  space  formed  by  the  cleavage  of  the  dura  mater,  lined  by  a 
prolongation  of  the  lining  membrane  of  a  vein  and  conveying  venous  blood.  Some 
of  the  sinuses  are  placed  between  the  periosteal  and  supporting  layers  of  the  dura 
mater — the  lateral  sinus  is  a  good  example  of  this  class.  Others  (as  the  straight 
sinus)  are  bounded  wholly  by  the  inner  or  supporting  layer. 

The  cranial  sinuses  form  two  principal  systems,  which,  however,  communicate  with  each 
other.  The  following  is  a  list  of  the  sinuses  which  unite  to  form  the  larger  of  these  two 
systems  : — superior  longitudinal,  inferior  longitudinal,  straight,  occipital,  superior  petrosal. 
These  form  a  system  which  converges  at  the  torcular  Herophili,  a  dilated  blood-space  situated  on 
the  right  side  (rarely  on  the  left)  of  the  internal  occipital  protuberance.  The  blood  from  the 
torcular  is  drained  away  by  the  lateral  sinuses  (more  particularly  by  the  right  sinus),  which 
also  receive  blood  from  the  cavernous  sinuses  by  the  superior  petrosal  sinuses,  and  it  leaves  the 
cranium  through  the  posterior  compartment  of  the  jugular  foramen.  The  straight  sinus  usually 
passes  into  the  left  lateral  sinus.  The  smaller  sj^stem  comprises  the  spheno-parietal,  cavernous, 
circular,  transverse,  and  inferior  petrosal  sinuses.  The  blood  from  this  system  passes  into  the 
internal  jugular  vein  by  the  inferior  petrosal  sinus  through  the  atjterior  compartment  of  the 
jugular  foramen. 

Emissary  veins. — These  veins  are  possibly  extracranial  tributaries  of  the  cranial  sinuses  under 
normal  conditions,  but,  in  cases  of  engorgement  of  the  sinuses,  permit  the  flow  of  blood  in  the 
opposite  direction,  and  become,  in  accordance  with  their  name,  emissary.  The  mastoid  emissary 
is  the  most  important  of  these  veins  ;  it  passes  through  the  mastoid  foramen  to  enter  the  lateral 
sinus,  and  explains  the  value  of  applying  leeches  behind  the  ears  in  cases  of  cerebral  congestion. 
Three  small  emissaries  enter  the  superior  longitudinal  sinus,  one  of  these  passes  through  the 
foramen  caecum  :  the  others  traverse  the  parietal  foramina.  An  additional  vein  occasionally  passes 
to  the  torcular  Herophili  through  a  foramen  in  the  occipital  bone  near  the  external  occipital 
jirotuberance.  Emissary  veins  pass  through  the  foramen  ovale  and  foramen  of  Vesalius,  and 
place  the  cavernous  sinus  in  communication  with  the  pterj'goid  venous  plexus  ;  others  traverse 
the  cartilage  which  occupies  the  foramen  lacerinn  medium.  Small  veins  enter  the  lateral 
sinuses  through  the  anterior  and  posterior  condyloid  foramina.  A  minute  venous  plexus,  which 
accompanies  the  internal  carotid  artery  through  the  carotid  canal,  establishes  a  communication 
between  the  cavernous  sinus  and  the  internal  jugular  vein.     (Eektorzik.) 

The  dura  mater  of  the  brain  is  continuous  through  the  foramen  magnum  with 
the  dura  mater  of  the  cord.  It  is  also  continuous,  through  the  various  foramina 
in  the  cranium,  with  the  external  periosteum  of  the  skull.  This  is  most  easily 
observed  at  the  sphenoidal  fissure,  but  may  be  made  out  with  ordinary  care  at  any 
of  the  other  foramina.  It  sends  a  strong  prolongation  through  the  optic  foramen 
which  splits  into  two  layers,  one  of  which  forms  the  sheath  of  the  optic  nerve,  and 
the  other  is  continued  into  the  periosteum  of  the  orbit.  On  account  of  the  number 
of  foramina  at  the  base  of  the  skull,  it  follows  that  the  dura  mater  is  more  firmly 
connected  to  the  bone  here  than  at  the  roof  and  sides.  In  the  region  of  the  basilar 
process  of  the  occipital  bone,  the  dura  mater  splits  into  sujtporting  and  periosteal 
layers.     The  supporting  layer  passes  through   the  foramen  magnum  to   become 


MEXrXOES  673 

continuous  with  tlic  dura  niatcr  of  the  spinal  cord.  Tlic  periosteal  layer  clothes 
the  bone  and  is  thickened  into  a  ligamentous  band,  the  occipito-cervical  or  cervico- 
basilar  ligament  (page  188),  Avhich  passes  through  the  foramen  magnum  to  join  the 
posteiior  connnon  ligament  of  the  vertebne  and  to  gain  attachment  to  the  l>o(.ly  of  the 
axis.  Thus  a  connection  is  established  between  the  dura  mater  and  the  jieriosteum 
of  the  vertebra\  At  the  l)ack  and  sides  of  the  foramen  magnum  the  dura  mater 
does  not  split  into  periosteal  and  supporting  layers  until  it  reaches  the  margin  of 
that  opening,  where  its  layers  divaricate,  the  one  to  become  continuous  with  the 
external  periosteum  of  the  skull,  the  other  to  be  continued  into  the  spinal  dura 
mater.  In  the  middle  fossa  of  the  skull  there  is  a  separation  of  the  periosteal  and 
supi)orting  layers  to  form  the  cavernous  sinus;  on  the  inner  side  of  this  the  sup- 
])orting  layer  is  moulded  round  the  pituitary  body  and  then  folds  on  itself  to  form 
the  diaphragma  sellae  which  roofs  in  the  pituitary  fossa.  External  to  the 
cavernous  sinus  the  two  layers  remain  separate  for  some  distance,  forming  a  space 
(Meckel's  space),  which  encloses  the  Gasserian  ganglion.     The  outer  surface  of 


Fig.  403. — Coronal  Section  of  the  Head  passing  thkough  the  Mastoid  Process. 
(From  a  mounted  specimen  in  tbe  Anatomical  Department  of  Trinity  College,  Dublin.) 


•Superior  longi- 
tudinal sinus 


Falx  cerebri 


CORPUS 
f'ALLOHVM 

Choroid  plexus 
i'eins  o/  Galen 


Tentorium 
eerebelli 

Lateral  .sinus 

f  OR  PIS 
DENTA  TIM 


CA  IDA  TE 
M'CLEIS 

LATERAL 
VEyfRICLE 


Superior  petrosal 

sinus 
MASTOID  ANTRUM 

Lateral  sinus 


MASTOID  PROCESS 


the  dura  mater  is  covered  with  a  number  of  arteries,  which  ramify  between  it  and 
the  inner  table  of  the  skull.  These  vessels  break  up  into  small  twigs  which 
penetrate  the  bone.  The  term  meningeal,  a])i»lied  to  the  arteries  in  question,  is 
somewhat  misleading,  inasmuch  as  they  do  not  sujijily  any  of  the  meninges,  except 
the  dura  mater,  being  chiefly  destined  for  the  nutrition  of  the  cranial  bones.  These 
small  vessels,  together  with  a  number  of  fibrous  retinacula,  are  torn  across  when 
the  dura  mater  is  forcibly  detached  from  the  bone,  and  give  rise  to  the  rough 
appearance  which  is  presented  by  its  outer  surface.  An  examination  under  water 
will,  however,  reveal  smooth  s])ots  interspersed  among  the  bundles  of  ruptured 
vessels;  these  are  subperiosteal  lymph-spaces. 


674 


THE  XER VOL'S  SYSTEM 


which  usually  jtiorce  the  great  wing  of  the  sphenoid  near  the  outer  angle  of  the  sphenoidal  fis- 
sure, lu  the  middle  craiiial  fossa  tlie  following  arteries  are  uiet  with:  a  branch  of  the  ascending 
pharyngeal  which  i)erforates  the  cartilage  which  occupies  the  foramen  laccruni  medium  ;  the 
meningea  parva  which  enters  the  cranium  through  the  foramen  ovale  ;  the  meningeal  branch  of 
the  iiitcriiul  carutiil.  and  twigs  from  the  middle  meningeal.  In  the  po.-terior  cranial  fossa,  two 
meningeal  branches,  derived  i'rom  the  occii)ital  and  ascending  pharyngeal,  enter  through  the 
posterior  compartment  of  the  jugular  foramen,  another  twig  from  the  oiripital  pas.ses  through 
the  mastoid  foramen,  and  a  twig  from  the  ascending  i)haryngeal  makes  its  way  through  the  ante- 
rior condyloid  foramen.  A  meningeal  branch  of  the  vertebral  is  given  off  from  that  artery,  in 
the  interval  between  the  occipital  bone  and  the  posterior  arch  of  the  atlas,  and  enters  the  skull 
through  the  foramen  magnum. 

A  branch  of  the  occipital  artery  (ramus  parietalis,  Cruveilhier)  occasionally  passes  through 
the  parietal  foramen  to  the  dura  mater  lining  the  calvaria. 

The  following  are  the  infoklings  formed  l;)y  the  inner  or  siti)])orting  layer  of  the 
dura  mater,  taken  in  their  order  of  magnitude:  the  falx  cerebri,    the  tentorium 


Fig.  404. 


-CoROXAL  Section  of  the  Head  passing  through  the  Posterior  Horns  of 
THE  Lateral  Ventricles. 


(From  a  mounted  specimen  in  the  Anatomical  Department  of  Triuit}-  College,  Dublin.) 


Dura  mater 


BULB  OF 

POSTERIOR 

CORXU 

HIPPOCAM- 
PUS MINOR 


FASCICULI'S 
LONGITUDI- 
NALIS  IN- 
FERIOR 


Superior 
longitmiinal 
sinus 


Falx  cerebri 


Straight  sinus 

POSTERIOR 
CORNU  OF 
LA  TERA  L 
lENTRICLE 


CALCARINE 
FISSURE 


Lateral  sinus     CORPUS  DENTA  TUM       Tentorium  cerebelli 


cerebelli,  the  falx  cerebelli,  and  the  diaphragma  sellae.  There  are  also  two 
smaller  ])aired  fokls;  viz.  the  folds  which  project  from  the  lesser  wings  of  the 
s})henoid  l)one  into  the  Sylvian  fissures  of  the  brain,  and  the  crescentic  folds  which 
are  ])laced  over  the  optic  nerves  at  the  upper  margin  of  the  optic  foramina. 

The  Falx  Cerebri  is  a  large  sickle-sha})ed  process,  deeper  liehind  than  in  front, 
which  is  placed  in  the  great  longitudinal  iissure  of  the  brain.  It  is  attached  by  its 
base  to  the  tentorium  cerebelli,  in  the  middle  line,  and  maintains  l)y  its  tension  the 
vaulted  character  of  the  latter.  The  straight  sinus  follows  this  line  of  attachment. 
Its  apex  is  firndy  fixed  to  the  crista  galli  of  the  ethmoid,  and  has  also  an  attach- 
ment to  the  ethmoidal  spine  of  the  sphenoid  bone.  Its  convex  or  upper  margin 
corres})onds  to  the  superior  longitudinal  sinus,  and  is  attached  to  the  periosteal 
layer  opposite  to  the  edges  of  the  groove  for  that  sinus  in  the  frontal,  the  two 
parietal,  and  the  occipital  bones.  The  inferior  longitudinal  sinus  courses  along 
its  concave  or  free  margin.  This  margin  closely  a])iu-oaches  the  corjius  callosiun 
Itchind,  but  is  separated  from  it  by  a  considerable  interval  in  front. 


MEMXGES 


67.') 


The  Tentorium  Cerebelli  occupies  the  interval  between  the  cerel^runi  and 
cerelx-lluiu.  It  presents  for  examination  an  upper  surface,  a  lower  surface,  a  free 
or  ctjncave  1  (order,  and  an  attached  or  convex  Ijorder.  The  upper  surface  is  in 
contact  with  the  occipital  and  temporal  lobes  of  the  cerebrum,  ami  is  strongly 
convex  ujjwards,  forming  a  roof-like  structure,  to  the  ridge  of  which  the  base  of 
the  falx  cerel>ri  is  attached.  This  ridge  also  slopes  upwards  and  forwards,  so  that 
its  highest  i)oint  is  situated  at  the  free  l)ordcr.  The  under  surface  is  in  api)osi- 
tion  to  the  cerelxdlum.  The  free  border  Ijounds  an  opening  usually  described  as 
oval,  l)ut  which  is  more  properly  triangular  with  curved  sides,  the  apex  of  the  tri- 
angle being  turned  backwards,  and  corresponding  to  the  point  where  the  veins  of 
Galen  enter  the  straight  sinus.  This  opening  transmits  the  crura  cerebri  and  the 
superior  peduncles  of  the  cerebellum,  these  parts  forming  an  isthmus  connecting 
the  masses  of  brain  suljstance  above  and  below  the  tentorium ;  the  basilar  artery 
and  the  third  pair  of  cranial  nerves  also  jiass  upwards  through  it.       Followed 


Fig.  405. — The  Cranium  opened  to  shoav  the  Falx  Cerebri,  the  Tentorium  Cerebelli, 

AND  the   places   WHERE  THE   CRANIAL  NERVES   PIERCE  THE   DURA   MaTER.      (Sappey. ) 


FOURTH  SERVE 


THIRD  NERVE 


Falx  cerebri 


SECOSD  SERVE 


Superior  tonr/i- 
tiidinal  sinn.i 
Inferior  longi- 
tudinal sinus 


Vtiiis  of  Galen 


Straight  sinus 

Tentorium 
cerebelli 


Lateral  sinus    — 


Superior 
petrosal  sinus 

Falx  cerebelli 

.SEVESTlf  ASD 
EJiiHTH 
SERVES 
SISTH,  TESTH,  ASP 
ELEVKSTH  SERVES 

TWELFTH  SERVE 
SECOSD  CERVICAL  SERVE 


FIFTH 
SERVE 


Middle 
tn-ningeal 
artery 
Internal 
carotid  artery 


liigamentum  denticulatum 


SERVE    Inferior  petrosal  sinus 


forwards,  the  free  border  is  seen  to  be  attached  to  the  anterior  clinoid  processes  of 
the  sjthenoid  V)one.  The  attached  border  follows  the  lateral  sinus  along  the 
occipital  and  ])arietal  bones,  and  then  corresponds  to  the  sujierior  petro.'sal  sinus, 
along  the  .superior  l)order  of  the  petrous  portion  of  the  temporal,  and  finally  dips 
under  the  free  border,  to  be  attached  to  the  posterior  clinoid  process  of  the  splienoid 
bone. 

The  Falx  Cerebelli  is  a  small  ])rominent  fold,  which  is  ]>laced  lietween  the 
cerebellar  hemisjihcns.  Its  attached  l>order  corresponds  to  the  occii)ital  sinus 
along  the  internal  occipital  crest.  Above  this  it  is  attached  for  a  short  distance  to 
the  under  surface  of  the  tentorium.      Its  free  l)order  looks  upwards  and  forwards. 

The  diaphragma  sellae  is  a  small,  amiular.  shelf-like  fold  of  the  dura  mater 
which  root's  in  tlu-  ]iitnitary  fossa,  leaving  a  small  aperture  in  the  centre,  which 
transmits  the  infun<libulum. 

The  subdural  space  is  a  narrow  lym]ih-space  between  the  dura  mater  and 
the  arachnoid.     It  is  occupied  by  a  small  i)oi-tion  of  the  cerebro-spinal  tiuid,  the 


G76 


THE  XERVOUS  SYSTEM 


greater  part  of  which,  however,  is  lodged  in  the  meshes  of  the  subarachnoid  tissue, 
and  in  the  ventricles  of  the  brain  (page  678).  This  space  separates  the  arachnoid 
from  the  dura  mater,  except  where  it  is  crossed  by  the  veins  of  the  brain  passing 
to  the  cranial  sinuses,  by  the  Pacchionian  bodies,  and  by  the  cranial  nerves  at  tlieir 
points  of  exit  from  the  skull. 

The  ARACHNOID  is  a  thin  delicate  membrane,  which  presents  a  well-defined 
limiting  surface  towards  the  dura  mater,  but  on  its  deep  or  pia-matral  surface 
passes  insensibly  into  the  subarachnoid  tissue.  The  arachnoid  does  not  dip  into 
the  fissures  of  the  cerebrum  and  cerebellum,  Avith  the  exception  of  those  fissures 
which  contain  processes  of  dura  mater.  Thus  it  is  carried  into  the  great  longitu- 
dinal fissure  for  a  depth  corresponding  to  the  falx  cerebri,  and  it  passes  for  a  short 
distance  into  the  fissure  of  Sylvius  around  the  fold  of  dura  mater  which  projects 
from  the  lesser  wing  of  the  sphenoid. 

On  each  side  of  the  superior  longitudinal  sinus  groups  of  small  lobulated  bodies, 
the  so-called  Pacchionian  glands,  project  from  the  surface  of  the  arachnoid;  these 
are  enlargements  of  the  normal  villi  of  that  membrane  Avhich  perforate  the  dura 
mater  and  cause  absorption  of  the  bone  in  their  vicinity.     Most  of  these  bodies  are 


Fig.  406. — Coronal  Section'  through  the  Great  Longitudinal  Fissure,  showing  the 

Meninges.     (Key  aud  Retzius. ) 


SUB  A  HA  CHSOID  SPA  CE 


Superior  lomjititdinul  sinus 


PACCHIOXIAX  BODY 


CORPiS  CALLOSIM 


lodged  in  irregular  pits  in  thecalvaria;  others  project  into  the  superior  longitudinal 
sinus.     They  may  also  occur  in  other  situations. 

The  subarachnoid  tissue  consists  of  very  fine  trabeculae,  clotlied  with  endo- 
thelial cells,  which  pass  from  the  arachnoid  to  the  pia  mater.  Thus,  a  sub- 
arachnoid space,  in  the  proper  sense  of  the  word,  does  not  exist;  it  is  convenient, 
however,  to  retain  the  term  to  designate  the  region  which  is  occupied  by  the  sub- 
arachnoid tissue,  and  to  speak  of  the  accumulations  of  this  tissue  which  are  formed 
in  r(^gions  where  the  distance  between  the  araclnioid  and  pia  niater  is  increased  as 
subarachnoid  spaces.  It  should  be  understood,  however,  that  in  these  larger 
spaces  tlie  subarachudid  tissue  is  less  abundant  and  the  meshes  are  larger  than  in 
the  regions  where  the  arachnoid  and  the  pia  mater  are  more  ap])roximated. 

The  largest  of  these  spaces  is  the  cisterna  magna,  which  is  a  continuation  of 
the  posterior  subarachnoid  space  of  the  spinal  cord.  This  space  appears  triangular 
in  sagittal  section.  It  is  bounded  in  front  by  the  layer  of  pia  mater  (tela 
choroidea  inferior,  page  718)  which  closes  in  the  lower  part  of  the  roof  of  the 
fourth  ventricle,  and  above  by  the  inferior  vermiform  process  of  the  cerebellum.  It 
extends  laterally  as  far  as  the  outer  margins  of  the  tonsillar  lobes.  It  communi- 
cates with  the  fourtli  ventricle  by  means  of  three  small  o]>enings;  the  principal  of 
these  (foramen  of  Majendie)  is  in  the  middle  line  of  the  tela  choroidea  inferior 
immediately  above  the  obex   (page  718).     The  two  others  (foramina  of  Key  and 


ARACHXOJD—J'IA    MA  TKR 


077 


Retzius)  are  at  tlio  cxtreniitie^  of  the  reces?;us  laterales  of  the  fourth  ventricle, 
behind  the  upper  roots  of  the  glos.so-pharyngeal  nerves.  Another  large  space,  the 
cisterna  pontis,  is  continued  from  tlie  anterior  sul)ara(hnoid  space  of  the  cord,  and 
extends  forwards  as  far  as  the  commencement  of  the  great  l(jngitu<linal  fissure,  and 
laterally  to  the  inner  margins  of  the  temi)oro-sphenoidal  lobes.  The  ))asilar  artery 
and  the  circle  of  Willis  are  placed  in  this  space.  The  cisterna  })ontis  communicates 
freely  around  the  medulla  oblongata  with  the  cisterna  magna — thus  the  medulla  is 
encircled  Ijy  a  wide  subarachnoid  space. 

A  large  space  is  also  to  be  found  between  the  lower  edge  of  the  falx  cerebri 
fwhere  the  arachnoid  passes  across  from  one  cerel)ral  hemisphere  to  the  other)  and 
tlie  upper  surface  of  the  corpus  callosum.  This  space  contains  the  trunks  and 
larger   branches   of   the   anterior   cerebral    arteries.     Another   considerable   space 


Fig.  407. — Cranial  Nerves  ix  the  Base  of  the  Skill. 
(On  tlie  left  side  the  dura  mater  has  bt-eu  removed  iu  the  middle  fossa.) 


Meningeal  branch  of 
aiite.rior  ethmoidal  arteru 


Meningeal  branch  of  ]>us- 
teriur  ethmoidal  artery 

Middle  meningeal 
arteru 

OPJfr/f.iLV/r 

Divisioy  OF 

FIFTH  m:r\e 

THIRD  XERVE  — 

Carernous  sinus 
FOrnTII  SFRVF 
AVDinjRY  ASH 
FACIAL  SERVES 
Superior  petrosal  simis 
Inferior  petrosal  sin  us 
Pelro-sqiiamotis  sinus 
SI'ISAL  ACCES- 
SORY SERVE 
Sigmoi'l  portion  of 
lateral  sinus 
Posterior  meningeal 
branch  of  vertebral 
artery 
Left  marginal  sinus 


Left  lateral  sinus 
Superior  longitudinal  sinus 


<  irci'liir  sinus 
Carotid  artery 

SIXTH  ni:rve 

Basilar  artery 
Basilar  plexus  of  veins 
Auditory  artery 

rerlehral  artery 
QU)  SSO-  PH.\  R  r.VG  FA  L 
AXU  PXElWrjOASTRir 

Anterior  niiinnt  artery     {S. 

HYPOGLOSSAL 

SERVE 
SPISA  L  A  crES- 
SORY  SERVE 

Riiiht  mnrip,,,'!  .;.,„5 


tjceijiital  siii^ 


,l,t  Inl^riil  xi 


-exists  in  the  fissure  of  Sylvius,  and  in  this  the  middle  cerebral  artery  ramifies. 
Thus,  with  the  exception  of  the  cisterna  magna,  all  these  spaces  serve  for  the 
accommodation  of  large  arteries.  There  is  also  a  space  between  the  corpora  (juadri- 
geinina  and  the  anterior  extremity  of  tlie  suiierior  vermiform  process  of  the  yere- 
bellum,  and  through  this  the  veins  of  (ialen  pass  to  terminate  in  the  straight  sinus. 

The  PIA  MATER  is  a  delicate  vascular  membrane  wliich  closely  invests  the 
nervous  sul)stance.  It  follows  accurately  the  contour  of  the  surface  of  tlie  lirain, 
dipping  into  all  the  fissures  of  the  cerebrum  and  cerebellum — in  the  smaller  sulci 
of  the  latter,  however,  a  double  layer  cannot  be  distinctly  made  out.  Processes  or 
folds  of  this  membrane  project  into  some  of  the  ventricles  of  tlie  brain,  and  are 
separated  from  the  ventricular  cavities  only  l)y  a  layer  of  epitheliuuL  These 
folds  form  the  velum  interpositum  and  choroid  plexuses,  which  will  be  described 


678  THE  NERVOUS  SYSTEM 

with  the  anatomy  of  the  ventricles.  The  blood-vessels,  which  divide  freely  in  tlie 
subarachnoid  tissue,  sulidivide  into  the  pia  mater,  forming  by  their  inoscula- 
tions fine  networks  from  which  innumerable  minute  vessels  proceed  to  penetrate 
the  nervous  substance. 

Lymphatics  of  the  Brain  and  Spinal  Cord 

The  lymphatics  of  the  brain  and  spinal  cord  are  peculiar,  inasmuch  as  thej^  open  into  the 
subarachnoid  space,  and  are  oidy  indirectly  connected  with  the  geneial  lympliatic  and  venous 
systems.  The  communications  with  the  venous  system  are  effected  Ly  the  Pacchionian  bodies. 
The  lymphatics  of  the  peripheral  nerves  are  in  the  form  of  tubular  spaces  jilaced  between  the 
lamellae  of  the  perineural  sheaths.  These  tubular  channels  open  into  the  subdural  and  subarach- 
noid spaces. 

The  subdural  space  is  a  very  narrow  inteival  between  the  dura  mater  and  arachnoid  (page 
675).  It  normally  contains  only  sufficient  fluid  to  moisten  its  surfaces.  It  is  in  communication 
with  the  lymphatics  of  the  neck  and  also  of  the  back  and  loins.  It  also  communicates  with  the 
perineural  spaces  around  the  nerves,  and  with  the  lymph  spaces  which  surround  the  olfactory, 
optic,  and  auditory  nerves.  It  sends  prolongations  around  the  Pacchionian  bodies.  It  does  not 
communicate  with  the  subarachnoid  space. 

The  subarachnoid  space  contains  the  greater  part  of  the  cerebro-spinal  fluid,  the  fluid  occupy- 
ing the  meshes  of  the  subarachnoid  tissue.  The  lymphatics  of  the  brain  and  eoid  and  also  the 
perineural  spaces  of  the  nerves  open  into  this  space.  It  is  also  in  communication  with  the  ven- 
tricular system  of  the  brain  by  means  of  the  foramen  of  INbijendie  and  the  foramina  of  Key  and 
Retzius.  Slit-like  communications  between  the  subarachnoid  space  and  the  descending  horn  of 
the  lateral  ventricle  have  also  been  described  (Merkel  and  Mierzejewsky).  It  also  communicates 
with  the  perilymph  spaces  of  the  internal  ear  and  with  the  Ij-mphaties  of  the  mucous  membrane 
of  the  nose.     It  sends  prolongations  around  the  optic  and  auditory  nerves. 

The  lymphatic  vessels  of  the  brain  and  cord  surround  the  arteries,  and  are  hence  called  peri- 
vascular lymphatics.  As  each  artery  dips  into  the  nervous  substance  it  carries  with  it  a  tubular 
process  of  the  pia  mater.  This  tubular  jirocess  is  lined  by  endothelial  cells  and  a  .similar  la.yer 
covers  the  coat  of  the  arterj'.  In  this  manner  the  lymjih  space  is  bounded.  The  perivascular 
lymphatic  follows  the  artery  as  far  as  its  capillary  ramifications. 

There  is  a  Ij^mph-space  between  the  two  layers  of  the  spinal  pia  mater.  Lymph-spaces 
between  the  outer  and  middle  coats  of  the  cerebral  arteries  ( Virchow-Robin  space)  and  others 
around  the  individual  nerve-cells  of  the  brain  have  been  described,  but  these  are  very  generally 
believed  to  be  artificial,  being  due  to  shrinking  from  the  action  of  reagents.  According  to  Ober- 
steiner,  however,  the  existence  of  the  pericellular  spaces  'is  ]iroved  by  the  ])reseuce  within  them 
of  lymphatic  cells.'  The  so-called  epicerebral  and  epispinal  spaces,  situated  between  the  deep 
surface  of  the  pia  mater  and  the  nervous  substance,  are  also  artificial. 

Structure  of  a  Pacchionian  body. — A  Pacchionian  bodj'  consists  of  (a)  a  central  core  of  sub- 
arachnoid tissue  which  is  joined  to  the  general  subarachnoid  tissue  by  a  comparatively  narrow 
stalk.  This  is  limited  by  (b)  a  laj^er  of  arachnoid  ;  around  which  is  (c)  a  ])rolongation  of  the 
subdural  space.  Bounding  this  space  h{d)  a  very  thin  layer  of  membrane  derived  from  the 
inner  layer  of  the  dura  mater.  It  has  been  shown  exjierimentally  that  injections  thrown  into  the 
subarachnoid  space  permeate  the  Pacchionian  bodies  and  pass  into  the  venous  sinuses  into  which 
these  bodies  project.  In  this  course  the  injection  distends  the  subdural  space  of  the  Pacchionian 
body,  but  does  not  enter  the  general  subdural  space.  It  should  be  mentioned,  however,  that 
anatomical  pores  by  which  the  injection  could  ]iass  do  not  exist.  It  is  probable  from  these 
experiments  that  an  outlet  for  the  cerebro-spinal  fluid  is  provided  by  the  Pacchionian  liodies. 

Cerebro-spinal  fluid. — The  cerebro-spinal  fluid  occujiies  the  subdural  and  subarachnoid 
spaces  of  the  brain  and  cord  and  also  the  ventricular  cavities  of  the  brain.  The  average  quantity 
is  about  two  ounces  (Landois  and  Stirling).  Its  sjiecifie  gravity  is  about  1010.  It  is  of  a  very 
pale  yellow  colour,  and  presents  many  of  the  characters  of  ordinaiy  lymjdi.  but  diff"ers  from 
IjMuph  in  not  being  coagulable,  as  it  does  not  contain  either  fibrin  f;ictors  or  fibrin  ferment.  It 
contains  a  substance  which  acts  on  Fehling's  solution  like  dextrose,  but  which  is  not  a  .sugar 
(Foster). 

The  cerebro-spinal  fluid  is  derived  in  part  from  the  lymi)]iatic  vessels  which  ojien  into  the 
subarachnoid  and  subdural  si)aces,  but  is  also  believed  to  be  secreted  by  the  epithelial  cells  which 
cover  the  choroid  plexuses.  These  cells  are  cubical  in  form,  and  resemlde  secreting  cells;  a 
Jirocess  of  the  choroid  ])lcxus  covered  by  these  cells  has  been  ajitly  compared  by  Foster  to  'an 
everted  alveolus  of  a  secreting  gland,  with  the  epithelium  outside  and  the  blood-vessels  within.' 


THE  BR  MX  679 


THE  ENCEPHALON 

The  encephalon,  <!r  brain,  is  the  ])orti()n  of  the  cerebro-spinal  axis  whieli  is 
lodged  witliin  the  eranial  cavity  and  constitutes  (Vty  weight)  about  98  per  cent,  of 
the  whole.  It  consists  of  the  cerebrum,  the  cerebeiluni,  the  i)ons  Varolii,  and  the 
medulla  ol)longata.  The  medulla  is  continuous  with  the  spinal  cord  at  the  decus- 
sation of  the  i)yramids.  The  e!icei»halon,  taken  as  a  whole,  is  ellii»soidal  or  ovoidal 
in  form,  presenting  above  a  toleral)ly  even  convexity  formed  by  the  cerebral  hemi- 
spheres, but  below  a  mor(^  irregular  surface  corresponding  to  the  fossae  in  the  base  of 
the. skull.  The  cerebrum  comprises  the  cerebral  hemispheres  containing  the  lateral 
ventricles  (prosencephalon),  the  optic  thalami  with  the  third  ventricle  between 
them  ( thalamencephalon)^  and  the  mesencephalon.  It  occupies  the  upper 
compartment  of  the  cranial  cavity,  resting  on  a  Hoor  formed  by  the  anterior  and 
middle  cranial  fossie  and  the  tentorium  cerebelli.  The  cerebellum  occupies 
the  posterior  cranial  fossa,  and  is  ])laced  behind  the  fourtli  ventricle.  It  is  con- 
nected l)y  three  pairs  of  peduncles  or  crura  to  tlie  cereln'um,  pons,  and  the 
medulla  respectively.  The  fourth  ventricle  is  l^ounded  in  front  by  the  pons  and 
medulla. 

Ill  every  part  of  the  encephalon  two  ili>tinct  kinds  of  nervous  substance  are  to  be  met  witli. 
termed  grey  and  white  matter.  The  grey  matter  is  ciiiefly  disposed  upon  the  surface,  as  in  the 
convolutions  of  the  cerebiaim  and  cerebellunj  ;  but  it  is  also  met  with  in  detached  or  partially 
(letaclied  masses  or  nuclei,  such  as  the  eorjjora  striata  and  o])tic  thalami  in  the  cerebrum,  the 
nuclei  of  the  medulla  and  p(jns,  and  the  corpus  dentatum  of  the  cerebellum.  It  is  composed  of 
groups  of  gangliotr  cells,  wliich  possess  the  power  of  originating  neiTous  imjmlses;  or  of  receiv- 
ing impulses  produced  by  the  action  of  external  stimuli  on  the  end-organs  of  nerves  ;  or  of  modify- 
ing and  redirecting  i^uch  impulses.  The  white  matter  occurs  in  the  greatest  quantity  in  the 
central  j^arts  of  the  cerebral  hemispheres.  It  is  composed  of  medullated  nerve-fibres,  which 
conduct  the  impulses  to  and  from  the  ganglion  cells  in  the  grey  matter.  Both  grey  and  white 
matter  are  supported  by  a  delicate  interstitial  ti.ssue  termed  neuroglia. 

Base  of  the  Brain 

Dissection. — The  student  is  recommended  to  commence  the  dissection  of  the  brain  by  a 
general  examination  of  the  structures  forming  the  base  of  that  organ.  He  should  carefxdiy 
remove  the  remains  of  the  membranes  from  the  ba.se,  and  after  studying  that  region  shoidd  ]»ro- 
ceed  in  a  similar  manner  to  remove  the  membranes  from  the  superior  and  lateral  surfaces  of  the 
cerebral  hemispheres. 

The  base  of  the  brain  presents  for  examijiation  the  inferior  surfaces  of  the  frontal 
and  temi)oro-s)dienoidal  loVjes  of  the  cerebrum  ;  the  stnictures  contained  within  and  adjacent 
to  the  interpeduncular  space  ;  the  anterior  surfaces  of  the  pons  Varolii  and  medulla  oblongata, 
the  inferior  surfaces  of  the  lateral  hemis|iheres  of  the  cerebellum  ;  and  the  superficial  origins 
of  the  cranial  nerves.  In  front,  the  orbital  surfaces  of  the  frontal  lobes  are  seen  separated 
from  one  another  by  the  great  longitudinal  fissure,  and  indented  by  the  triradiate  and  olfactory 
.sulci,  the  latter  occupied  by  the  olfactory  tract  and  bulb.  Bchiml  and  somewhat  laterally 
the  frontal  lobes  are  marked  off  from  the  temporal  lobes  by  the  fissure  of  Sylvius,  near  the 
commencement  of  which  is  the  anterior  perforated  S|tace.  This  s]iace  is  of  a  grey  colour, 
and  is  formed  by  a  part  of  the  lenticular  nucleus  of  the  corpus  striatum,  which  comes  to 
the  surface  at  the  base  of  the  brain.  Tiie  perforations  are  causi-d  by  small  arteries  which 
proceed  from  the  middle  cerebral  arteiy  to  the  corpus  striatum.  Each  soace  is  linunded 
internally  liy  one  of  the  j)eduntlcs  of  the  corpus  callosum.  The  latter  are  white  bands  which 
liass  from  the  corpus  callosum  to  the  commencement  of  the  fi.^sure  of  Sylvius.  Between  the 
temporo-sphenoidai  lobes  is  a  large  recess,  which  is  bounded  in  front  by  the  frontal  lobes,  and 
bi-hind  Vjy  the  pons  Varolii  ;  within  this  is  the  remarkable  arterial  ana.stomosis  known  as  the 
circle  of  Willis,  the  crura  cerebri,  the  interpeduncidar  space,  portions  of  the  ontic  tracts  with  the 
optic  commissure,  the  lamina  cinerea.  and  portions  of  tlie  third  and  flairtli  jiairs  of  nerves. 
The  interpeduncular  space  is  situated  between  the  diverging  cnini  (-erebri.  It  correspomls  below 
to  the  deepest  iiart  of  the  cisterna  pontis,  and  alcove  to  the  posterior  part  of  the  flour  of  the  third 
ventricle.  It  contains  (1)  tlie  posterior  jierforateil  space,  and  in  front  of  this  (2)  a  jiair  of  white 
rounded  eminences,  the  corpora  albicantia  or  mammillaria,  and  i'.\)  a  conical  greyish  elevation,  the 
tuber  cinereum.  ending  in  a  thin  tulmlar  process,  the  infundibnlum.     The  latter  jiasses  to  the 

fituitary   liody,  from   which    it   is  detached   in   removing   the    brain    by   the  ordinary  method, 
mmediately  in  front  of  the  tuber  cinereum  is  the  optic  commissure,  from  which  tlie  optic  tracts 
can  be  traced  for  a  short  distance  backwards  and  outwards,  winding  round  the  crura  cerebri,  aud 


680 


THE  NERVOUS  SYSTEM 


finally  disappearing  under  cover  of  the  temporal  lobes.  A  thin  grey  lamina,  the  lamina  cinerea, 
passes  from  the  anterior  border  of  the  optic  commissure  to  the  commencement  of  the  great 
longitudinal  fissure,  where  it  gains  an  attacliment  to  tlie  rostrum  of  the  corpus  callosum.  Tlie 
crura  cerebri  ai)j)ear  as  two  strong  flattened  bundles  of  white  fibres,  which  emerge  from  the 
superior  border  of  the  pons,  and,  diverging  from  one  another,  pass  under  cover  of  the  temporal 
lobes,  and  are  soon  lost  to  view.  On  each  side  the  third  nerve  is  seen  passing  between  the 
posterior  cerebral  aud  superior  cerebellar  arteries,  it  springs  by  a  row  of  filaments  from  a 
groove  at  the  inner  margin  of  the  crus.  The  fourth  nerve,  a  slender  rounded  fasciculus,  winds 
round  the  outer  side  of  the  cnas.  The  i)ons  Varolii  aj>})ears  immediately  behind  the  crura  as  a 
broad  band  of  white  fibres  directed  transversely,  and  passing  from  one  cerebellar  hemisphere  to 
the  other.  It  narrows  on  each  side  as  it  passes  into  the  cerebellum.  It  is  marked  by  a  shallow 
groove  in  the  middle  line  in  which  the  basilar  artery  rests.  The  fifth  nerve  is  seen  jiiercing  the 
side  of  the  pons  near  its  upper  border  in  the  form  of  two  bundles,  a  large  posterior  or  sensory 
root,  and  a  small  anterior  or  motor  root,  separated  from  the  former  bj'  some  of  the  transverse 


Fig.  408. — View  of  the  Ba.se  of  the  Brain.     (After  Beaunis.) 


OPERCULUM 


3rd  or  OCULO- 
ilOTOR 
ilh  nr   TRO- 
CHLEAR 


eth  or  ABDUCENT- 

Tth  or  FACIAL 

Sth  or  AUDITORY. 

»th.  GLOSSO- 

PHARTXG. 

lOth.  PNEUMO- 

GAST. 

nth.  SPINAL 

ACCESS, 
nth.  HYPO- 
GLOSSAL 


ANTERIOR 

PERFORA TED 

SPACE 
PITUITARY 

BODY 
TUBER 

CINEREU.V 
CORPUS 

ALBICANS 
POST.  PERF. 

SPACE 
CRUS  CEREBRI 
PONS  VAROLII 


OLIVARY  BOl'Y 
AMYGDALA 


INFERIOR 
VER.MIFORM 
PROCESS 


fibres  of  the  pons.  The  sixth  nerves  are  seen  at  the  lower  Ijorder  of  the  pons  in  the  groove 
between  it  and  the  medulla,  emerging  from  the  latter  close  to  the  outer  side  of  the  pyramidal 
bodies  or  between  the  fibres  of  these  bodies.  The  jiyramidal  and  olivary  bodies  can  readily  be 
made  out  on  the  medulla,  and  a  portion  of  the  restiform  body  can  also  be  seen  without  disturbing 
the  parts.  The  twelfth  or  hypoglossal  nerve  emerges  by  a  row  t)f  filaments  i'rom  the  groove 
between  the  olivary  and  pyramidal  bodies.  The  ninth,  tenth,  and  eleventh  nerves,  which  ai)))ear 
in  numerical  order  from  above  downwards,  arise  from  the  groove  })etween  the  olivaiy  and  resti- 
form bodies  ;  the  origin  of  the  eleventh  or  s]iinal  accessory  nerve  being  continued  down  the  lateral 
column  of  the  ciml.  Tlie  seventh  and  eighth  nerves  are  close  to  the  edge  ol"  the  pons  in  the 
angle  between  the  latter  and  the  cerebellum.  The  cerebellar  hemis])heres  are  jjliiced  one  on  each 
side  of  the  medulla  and  conceal  the  occipital  lobes  of  the  cerebrum  when  viewed  from  the  base. 
The  cerebellum  stands  out  C(jnspicuouslv  from  the  cerebi'iun  on  accoiuit  of  its  darker  grey  colour 
and  the  smaller  size  and  narrowness  of  its  convolutions,  which  are  termed  folia.  Two  of  its  lobes 
are  more  prominent  than  the  rest,  viz.  the  amygdalae  or  tonsils,  which  are  jtlaced  close  to  the 
medulla,  one  on  each  side  ;  and  the  flocculi,  which  lie  close  to  the  pons  above  the  tenth  or 
l)neumogastric  nerves. 


FISSURES   OF  CEREBRUM  681 


THE  CEREBRAL  HEMISPHERES 

The  cerebral  hemispheres  constitute  al)<)ut  87.-")  per  cent,  of  the  entire  brain, 
and  viewed  fioin  ahove,  piesent  an  ovate  torni,  broader  behind  than  in  front. 
They  cc^ntain  the  lateral  ventricles  in  their  interior.  They  are  separated  from  one 
another  Ijv  the  great  longitudinal  tissure,  the  floor  of  which  is  formed  l)y  the  corpus 
callosum,  a  great  commissure  which  connects  each  hemis])here  with  its  fellow. 
Each  hemisphere  presents  for  examination  four  surfaces,  supero-external,  inferior, 
internal,  and  tentorial,  and  two  extremities  or  poles,  an  anterior  and  a  posterior;  the 
anterior  pole  presenting  an  edge  flattened  internally  and  bevelled  externally;  the 
posterior  forming  a  blunt  rounded  point  which  is  directed  l)ackwai-ds  with  an 
iiichnation  downwards.  With  the  exception  of  a  small  ]ii)rtion  of  tlie  inferior  sur- 
face, the  cerebral  hemis])heres  are  entirely  covered  with  fissures  or  sulci,  which 
mark  oft'  intervening  elongated  elevations  termed  convolutions  or  gyri.  By  this 
means  the  surface  area  of  the  brain  and  consequently  the  proj^ntion  of  grey  to  white 
matter  is  very  greatly  increased.  The  general  arrangement  of  the  convolutions  in 
the  two  hemispheres  of  the  same  brain  is  tolerably  syimnetrical,  but  minor  differ- 
ences always  occur.  These  differences  are  more  particularly  seen  when  there  is  any 
striking  deviation  from  the  normal  arrangement,  as  such  alniormalities  are  usually 
contined  to  one  hemisphere.  The  supero-external  surface  is  convex,  presenting 
a  shar])er  curve  in  the  transverse  than  in  the  antero-])osterior  direction.  It  is 
marked  oft"  from  the  internal  surface  at  the  great  longitudinal  fissure  l)y  a  well- 
defined  edge.  It  is  divided  for  aljout  its  middle  tliird  into  a  superior  and  an  inferior 
segment  by  the  horizontal  limb  of  the  fissure  of  Sylvius  which  lies  above  tin- 
temporo-sphenoidal  lobe.  The  internal  surface  is  flattened,  and  is  separated  from 
the  opposite  hemisphere  by  the  falx  cerebri  and  the  subarachnoid  space.  The  infe- 
rior surface  is  divided  into  two  parts  by  the  stem  of  the  fissure  of  Sylvius;  the  ])0s- 
terior  part  is  formed  ])v  the  anterior  end  of  the  temporal  lo1)e  which  is  rounded  and 
l)roniinent,  constituting  the  temi)oral  pole.  In  front  of  the  Sylvian  fissure  is  the 
orbital  area  of  the  frontal  lobe,  wliicli  is  concave  and  adapted  to  the  orltital  i)late 
of  the  frontal  l)one.  Tlie  tentorial  surface  is  directed  downwards  and  inwards;  it 
is  ct)ncavc  and  rests  upon  the  tentorium  cerebelli. 

Fissures. — Under  this  term  are  included:  (a)  narrow  intervals  formed  by  thr 
a))])roximation  of  parts  primitively  widely  sejjarated,  and  (b)  fissures  due  to 
infoldings  of  the  ventricular  wall  for  a  part  or  the  whole  of  its  thickness.  Only 
tw(j  fissures  are  included  in  the  former  category,  viz.  the  great  longitudinal  and  the 
great  transverse  fissures  of  the  cerebrum,  (o)  The  great  longitudinal  fissure 
extends  from  the  frontal  to  the  occipital  pole  of  the  cerel>rum  and  se])aratt's  thr 
hemispheres  from  one  another,  except  where  they  are  joined  Ijy  the  corjuiscallo.-um. 
It  contiiins  the  falx  cere])ri  and  the  anterior  cerebral  vessels.  The  great  trans- 
verse fissure  will  l)e  described  witli  the  anatomy  of  the  lateral  and  third  ventricles. 
ill)  Till-  ri'inaining  fissures  present  a  very  distinct  division  into  (•om]>lete  and 
incomplete.  The  complete  fissures  are  formed  by  an  infolding  of  the  entire  thick- 
ness of  the  ventricular  wall,  so  that  the  reverse  of  each  complete  fissure  a])]>ears 
as  a  bulging  into  the  cavity  of  the  ventricles.  The  complete  fissures  comprist^ 
the  dentate  fissure,  the  collateral  fissure,  the  calcarine  fissure,  and  parieto-occii>ital 
fissure.  The  fissure  of  Sylvius  is  sometimes  descriJjed  as  a  complete  fissure,  '  but 
the  itrojection  into  the  hemisi)here  cavity  which  corresi)onds  with  it  (viz.  the 
corj)Us  striatum)  is  not  formed  l)y  an  infolding  of  the  mantle  wall,  but  as  an 
elevation  on  tlie  floor  of  the  prosencci)halon.  The  i^urface  area  corresjionding  to 
this  internal  projection  does  not  keep  i)ace  witli  the  mantle,  as  the  latter  grows 
around  it,  and  in  consequence  the  Sylvian  dcpri'ssinn  makes  its  ai)]»earance.' 
(Cunningham. ) 

Interlobar  fissures. — Certain  fissures  are  termed  interlobar  because  tliey  have 
been  selected  to  determine  the  l)Oundaries  of  the  various  lobes  into  which  tiie 
hemispheres  have  been  (somewhat  artificially)  divided.  These  are  the  parieto- 
occipital fissure  and  the  fissures  of  Sylvius  and  of  Rolando. 

The  parieto-occipital  fissure  a])]iears  as  a  well-marked  vertical  sulcu,s  on 
the  i)0.sterior  i)art  of  the  inner  face  t>f  the  hemisphere,  and  is  continued  outwards 


682 


THE  XERVOUS  SYSTEM 


for  a  short  distance  on  to  tlie  convex  surface.  Tlie  ])iirtion  on  the  mesial  surface 
is  (listintruislied  as  the  internal  parieto-occipital  or  internal  perpendicular  fis- 
sure. It  will  be  more  itarticularly  dcscrilicd  with  the  hssurcs  and  convolutions  of 
the  inner  surface  of  the  hemisphere.  The  ]iortion  which  a])pears  on  the  convex 
surface  is  distin<:uished  as  the  external  parieto-occipital  fissure. 

The  fissure  of  Sylvius  is  situated  jtartly  on  the  base  and  partly  on  the  external 
surface  of  the  hemisi)liere,  and  is,  with  the  exception  of  the  great  longitudinal  fis- 
sure, the  most  conspicuous  sulcus  in  the  brain.  It  connnences  at  the  outer  angle 
of  a  depression  called  the  vallecula  Sylvii,  in  which  the  anterior  perforated  space 
is  situated.  It  passes  outwards  and  upwards  with  an  inclination  backwards,  and 
<livi(U's  into  tln-ee  l)ranches  or  limbs,  a  posterior,  an  ascending,  and  an  anterior.  The 
posterior  limb  is  by  far  the  largest,  and  is  to  be  regarded  as  the  continuation  of  the 


Fici.  409. — The  Fissures  and  Coxvolutioxs  of  the  Cerebrum,  viewed  from  above. 


OnBITA  L 

MARiiiy 
svPEnion 

FROXTA  I. 

COXVOLLTIOX 

MIDDLE 

FRONTAL 
COyvOLLTION 

IXFERIOR 

FRONTAL 

CONVOLVTIOS 


ASCEXDiya 

FRONT  A  I 

C0NV0LVTIO.\ 


ASCENDING 

PARIETAL 

CONVOLUTION 

SUPRA- 
MARGINAL 
CONVOLUTION 


SUPERIOR  PARI- 
ETAL LOBUL 

ANGULAR  GYR 
AND  POST-PA RI 
ETAL  GYRUS 

MIDDLE  OrriPITAL 
CONVOLUTION 

SUPERIOR  OCCIPITAL 
CONVOLUTION 


SUPERIOR 
FRONTA  L 
FISSURE 


INFERIOR 
PR^E- 
CENTRA  L 
FISSURE 


SUPERIOR 
PR.E- 
CENTRA  L 
FISSURE 


INTRA- 
PARIETAL 
FISSURE 

CALLOSO- 
MARGINAL 
FISSURE 

SULCUS  Or- 
CIPITA  LIS 
ANTERIOR 

EXTERNA  I. 
PARIETn- 
OCCIPITA L 
FISSURE 

TRANSVERSE 
OCCIPITAL 
FISSURE 

SUPERIOR 
OCCIPITAL 
FISSURE 


main  fissure;  it  passes  backwards  and  slightly  U]nvards,  separating  the  temporo- 
sphenoidal  from  the  frontal  and  parietal  lobes,  and  finally,  taking  a  more  upward 
direction,  ends  in  the  parietal  lolie.  The  ascending  limb  is  short  and  ])asses 
vertically  upwards;  the  inferior  frontal  convolution  arches  around  it.  The  anterior 
limb  is  about  the  same  length  as  the  ascending;  it  passes  directly  forwards  into 
the  substance  of  the  inferior  frontal  convolution. 

The  convolutions  Avhich  surround  the  fissure  of  Sylvius  cover  in  and  conceal 
the  central  lobe  and  are  therefore  called  the  opercula.  The  opercula  are  four  in 
number — the  tem])oral,  the  fronto-parietal,  the  frontal,  and  the  orbital.  The 
temporal  operculum  is  fonncd  liy  the  upper  temporo-sphenoidal  convolution, 
thi'  fronto-parietal  operculum  by  the  lower  ends  of  the  ascending  frontal  and 
parietal  c(jnv(jlutions   and  tiie  jtosterior   end  of  the  inferior  frontal  convolution. 


FISSURE  OF  ROLAXDO 


683 


The  frontal  operculum  is  the  small  part  of  the  inferior  frontal  convolution  inclosed 
between  tlie  iiscenilintr  and  the  anterior  horizontal  limbs  of  the  Sylvian  fissure  and 
the  orbital  operculum  is  the  part  of  the  interior  frontal  convolution  beneath  the 
latter  liml). 

The  fissure  of  Rolando,  or  central  sulcus,  serves  as  a  line  of  demarcation 
between  the  frontal  and  parietal  lobes.  It  is.  next  to  the  fissure  of  Sylvius,  the 
most  important  of  the  ineomi)lete  fissures  of  tlie  brain.  It  extends  from  the  great 
longitudinal  fissure  to  the  Sylvian  fissure,  and  may  connnunicate  Avith  the  latter 
(19  per  cent.,  Cunningham),  but  the  comnumication  is  always  shallow.  At  its 
upper  end  it  usually  (GO  per  cent,  Cunningham)  passes  into  the  great  longitu- 
dinal fissure  and  ap})ears  on  the  mesial  surface  of  the  hemisphere,  where  it  ends  by 
l)ending  backwards  for  about  a  quarter  of  an  inch.  The  fissure  of  Rolando  is 
directed  downwards  and  forwards  so  that  the  fissures  of  the  two  sides  taken 
together  form  an  angle  of  about  143°,  open  in  front.  The  fissure  does  not  pursue 
a  perfectly  straight  course,  but  is  somewhat  sinuous,   and  two  of  its  bends,  more 


Fig.  410. — Lateral  View  of  the  Fisskees  axd  Coxvolutioxs  of  the  Cerebeum. 


AscEynrxo 

PARIETAL 

coyvoLUTioy 


SUPERIOR 
PR.'E- 
FISSVRE  OF    CEXTRA  L 
ROLAXDO    FISSCRF 


ASrEXDIXG 
FliOXTA  L 
rnxvOLL'TIOX 


SUPERIOR 
FRO  XT  A  L 
FISSURE 


IXTRA  PA  RI- 
ETAL  FISSURE 

SUPERIOR 
PARIETAL 
LOBULE 
SUPRA- 
.VARGIXAL 
COX  VOL 

ASai-LAR 
AST)  rosT- 
PARIETAL 

(iYRI 
EXT ER SAL 
PAKIETO- 

orrrp/TAL 
F/.isrRE 

SCPBRKJR 
OCCIPITAL 

coyroLr- 

TIOS 

TRA  \.<- 

VERSE 

OCCIPITAL 

FISStRE 


IXFERIOR 

OCCIPITAL 

COS  VOL  r- 

TIOS 


SUPERIOR 

FROXTAL 

rOXV0LUTI0:i 
IXFERIOR 

FROXTA  L 

FISSURE 


MIDDLE 
FROSTAL 
COSVOLC- 
TIOS 


PR.K-()<  ilPlIAL     SULCUS 

XOTCH         OCCIPITALIS 
ANTERIOR 


SUPERIOR 

TE.VPORA  L 

FISSURE 


Mii'iuj-: 

TEMPORA  L 

FISSURE 


ISFERIOR 
FROSTAL 
COS  VOL  L-- 
TIOS 


ORBITAL  SURFACE 
•I  ULRIon   TEMPORAL 
COXVOLUTIOX 
MIDDLE  TEM- 
\  PtiR  \L  COXVOLUTIOX 
JXFERIOR 
TEMPORA  L 
COXVOLUTIOX 


conspicuous  and  constant  than  the  others,  have  been  described  as  the  superior  and 
inferior  genua.  These  genua  mark  off  the  fissure  into  three  api^roximately  equal 
l)arts.  The  superior  genu  is  directed  backwards.  The  inferior  genu  looks 
forwards;  it  is  more  constant  and  much  more  strongly  marked  than  the  superior 
genu.  In  rare  cases  the  fissure  of  Rolando  may  communicate  with  the  prsecentral 
or  intraparietal  sulci,  but  as  a  rule  it  pursues  an  isolated  course  across  the  convex 
surface. 


It  has  been  very  generally  taught  that  the  fissure  of  Rolando  is  caused  by  the  jiressure  of  a 
vein  which  pa.sses  during  foetal  life  (from  the  fliurth  to  the  sixth  month)  from  the  middle  cerebral 
vein  to  the  superior  longitudinal  sinus.  This  view  has  been  recently  disproved,  as  it  has  been 
shown  that  the  fi.ssure  develops  in  two  segments,  an  upper  and  a  lower,  and  the  fissure  is  after- 
wards completed  by  the  sinking  down  of  the  central  portion.  The  remains  of  this  central  eleva- 
tion can  always  be  seen  on  opening  the  fissure  of  Rolando  as  a  deeply  placed  ainiectant  or  bridging 
convolution  at  the  level  of  the  superior  genu.     (Cunningham.) 

The  fissure  of  Rolando  is  one  of  the  earliest  of  the  incomplete  fissures  to  appear,  and  is 
usually  developed  during  the  last  week  or  ten  days  of  the  fifth  month  of  intra-uterine  life.  By 
its  transverse  direction  it  interrupts  the  longitudinal  course  of  the  majority  of  the  cerebral  fissures  ; 


684  THE  SERVOUS  SYSTEM 

tills  peculiarity  is  shared,  however  (hut  uut  so  coustantlj'),  hy  the  i)ra3central  sulcus  and  hy  tlie 
vertical  part  of  the  intrai)arietal  fissure.  It  is  one  of  the  uiost  iiiii>ortaiit  landmarks  on  the  cere- 
hral  surface,  as  the  principal  motor  centres  of  the  cortex  are  situated  around  it. 

The  Lobes  of  the  Cerebral  Hemispheres  avith  the  Fissures  and 

Convolutions 

Each  cerebral  liemisphere  is  divided  into  five  lobes,  viz.  the  frontal,  jiarietal, 
occipital,  teniporo-sphenoidal,  and  the  central  lobe  or  island  of  Reil.  Four  of  these 
lobes  are  visible  on  the  peripheral  part  of  the  hemispheres;  the  fifth,  or  island  of 
Reil,  is  deeply  i)laced  and  is  concealed  by  the  operculum. 

Two  other  lobes,  the  liml)ic  and  the  olfactory  lobe,  are  also  described. 

The  FRONTAL  LOBE  occupies  the  fore  part  of  the  hemisphere  and  presents 
three  surfaces:  a  convex  supero-external  or  frontal,  an  inferior  or  orbital,  and 
an  internal  or  mesial.  The  convolutions  and  fissvu-es  on  the  mesial  and  tentorial 
surfaces  of  the  hemisj^here  will  be  described  sei^arately.  The  frontal  lobe  is  bounded 
beliind  bv  the  fissure  of  Rolando,  and  below,  for  al)outits  posterior  half,  by  the  stem 
and  posterior  limb  of  the  fissure  of  Sylvius.  It  is  limited  internally,  l\v  the  calloso- 
marginal  fissure. 

The  frontal  surface  is  separated  from  the  orbital  liy  a  well-marked  angle 
which  may  be  called  the  orbital  margin.  This  margin  is  usually  destitute  of  fis- 
sures, and  forms  a  curve  concentric  witli  the  orbital  arch  of  the  frontal  bone. 
Three  fissures  on  the  frontal  surface  recjuire  descrij^tion:  one  of  these,  running  in  a 
transverse  direction,  is  termed  the  prajcentral,  the  other  two,  which  run  parallel  to 
the  great  longitudinal  fissure,  are  named  superior  and  inferior  frontal. 

The  praecentral  sulcus  is  placed  in  front  of  and  parallel  to  the  fissure  of 
Rolando,  and  is  usually  divided  by  a  sagittally-placed  convolution  into  tAvo  parts, 
a  superior  and  an  inferior  praecentral;  the  former  is  usually  continuous  with  the 
superior  frontal  fissure. 

The  superior  frontal  fissure  is  sometimes  discontinuous  Avith  the  praecentral. 
At  its  orl)ital  end  it  (,>ften  jjasses  into  a  coronally  placed,  cuiTcd  fissure,  termed  the 
sulcus  fronto-marginalis.  The  latter  is  situated  just  aboA'e  the  orbital  margin  of 
the  frontal  lol)e. 

The  inferior  frontal  fissure  may  lie  continuous  with  the  pnrcentral,  luit  a 
narroAv  gyrus  usually  separates  the  tAvo  fissures. 

The  convolutions  on  the  frontal  surface  are  four  in  number:  one  directed  trans- 
A'crsely  to  the  long  axis  of  the  cerebrum,  the  ascending  frontal;  and  three  lying 
in  an  antero-posterior  direction,  named  superior,  middle,  and  inferior  frontal. 

The  ascending  frontal  convolution  bounds  the  fissure  of  Rolando  in  front, 
and  is  placed  l)etween  that  fissure  and  the  prsecentral  sulcus.  It  is  connected  at 
the  lower  end  of  the  fissure  of  Rolando  Avith  the  ascending  parietal  convolution,  and 
losses  into  the  })aracentral  lobule  on  the  inner  face  of  the  hemisphere. 

The  superior,  middle,  and  inferior  frontal  convolutions  occupy  the  remainder  of 
the  frontal  surface,  and  are  marked  off  by  the  superior  and  inferior  frontal  sulci. 
They  pass  forwards,  and  become  continuous  Avith  the  convolutions  on  the  orbital 
surface.  They  are  not  simple,  but  are  traversed  lioth  in  a  coronal  and  sagittal 
direction  by  tertiary  fissures. 

The  superior  frontal  convolution  is  continuous  l)ehind  Avith  the  ascending 
frontal,  and  ])asscs  in  front  into  the  gyrus  rectus  and  into  the  internal  and  anterior 
orbital  couA'olutions.  It  is  continuous  with  tlie  marginal  convolution  on  the  inner 
face  of  the  hemisphere. 

The  middle  frontal  convolution  is  continuous  behind  Avith  the  ascending 
frontal  Avhen  tlie  superior  and  inferior  praecentral  fissures  are  discontinuous.  It 
])asses  in  front  into  the  anterior  orbital  gyrus.  It  is  almost  invariably  continuous 
Avith  the  superior  and  inferior  frontal  convolutions  at  the  orbital  margin  of  the 
frontal  lobe,  and  is  often  connected  to  these  convolutions  l)y  secondary  gyri  passing 
across  the  su]ierior  and  inferior  frontal  fissures. 

The  inferior  frontal  convolution  is  continuous  behind  with  the  ascending 
frontal,   and   joins  the    external    orbital    gyrus  aroimd  the    orbital  margin.      The 


FRONTAL   AND   PARIETAL   LOBES  685 

ascending  and  anterior  limits  of  the  fissure  of  Sylvius  cut  into  the  substance  of  this 
convohition,  and  divide  it  posteriorly  into  three  parts,  viz.  pars  or])italis,  pars 
triangularis,  anil  ])ars  l)asilaris.  The  pars  orbitalis  is  situated  l)elo\v  the  anterior 
linilj  of  the  Hyivian  fissure.  The  pars  triangularis  is  included  between  the 
ascending  and  anterior  limits  of  the  fissure.  The  pars  basilaris  is  placed  Ijehind 
the  ascending  limb  of  the  Sylvian  fissure  between  the  latter  and  the  inferior  prte- 
central  sulcus. 

This  cuiivolutiun  is  of  great  physiological  interest,  as  the  faculty  of  articulate  speech  is  local- 
ised in  its  posterior  i)art  (Broca's  convolution).  Disease  of  tliis  liuiitcd  portion  of  brain  substance 
on  the  left  side  i)r(Kluces  apliasia,  except  in  lelt-handed  ])ersons,  in  whom  the  speech-centre  is 
placed  in  the  corresponding  position  on  the  right  side.  The  siieech-centre  is  limited  to  the  pars 
basilaris.  According  toFerrier,  the  speech-centre  includes  (in  addition  to  tlie  aliovej  the  inferior 
extremity  of  the  ascending  frontal  convolution  and  a  small  part  of  the  a.scending  jjarietal  imme- 
diately behind  the  lower  end  of  the  fissure  of  Rolando. 

The  orbital  surface  of  the  frontal  lolje  appears  flattened  in  brains  hardened  in 
the  ordinary  manner;  but  when  the  brain  is  hardened  in  situ  (fig.  410)  it  i)rc- 
sents  a  ver\'^  characteristic  concavity,  being  moulded  on  the  orbital  plate  of  the 
frontal  bone.  The  outer  half  of  the  orbital  surface  looks  directly  downwards,  but 
the  inner  half,  following  the  curve  of  the  orbital  plate,  looks  much  more  outwards 
than  downwards,  and  forms  a  tolerably  sharp  edge  where  it  meets  the  internal 
surface.  Two  fissures  are  situated  on  this  surface,  viz.  the  triradiate  and  the 
olfactory. 

The  triradiate  fissure,  as  its  name  implies,  is  formed  by  three  branches,  which 
radiate  from  a  common  point.  One  branch  is  directed  forwards,  anotlier  l)ackwards 
and  inwards,  and  the  third  outwards.  Another  branch  frequently  springs  from 
the  external  division  near  its  centre,  and  in  such  cases  the  triradiate  fissure  assumes 
an  H -shaped  outline. 

The  olfactory  or  straight  sulcus  is  placed  a  short  distance  external  to  the  great 
longitudinal  fissure,  and  lodges  the  olfactory  tract  and  bulb. 

The  convolutions  on  the  orljital  surface  comprise  the  three  orbital  convolutions 
and  the  straight  convolution. 

The  orbital  convolutions  are  Avedge-shaped  masses  placed  between  the  limbs  of 
the  triradiate  fissure.  They  are  called,  from  their  position,  internal,  anterior,  and 
posterior.  They  are  continuous  with  the  su])erior,  middle,  and  iid'eiior  frontal 
convolutions  ros]  x'ctively. 

The  straight  convolution,  or  gyrus  rectus,  is  situated  betAveen  the  sulcus  of 
the  same  name  and  the  margin  of  the  great  longitudinal  fissure.  It  is  continuous 
in  front  Avith  the  superior  frontal  convolution,  and  on  the  inner  margin  of  the 
hemisi»here  with  the  marginal  gyrus.  It  is  sometimes  described  as  a  part  of  the 
internal  orljital  convolution. 

The  convolutions  on  the  internal  surface  of  the  frontal  lobe  are  the  marginal  and  the 
paracentral.  The  student  is  recommended  to  defer  the  study  of  these  till  a  later  period  (page 
690). 

The  PARIETAL  LOBE  occupics  the  portion  of  the  convex  surface  betAveen  the 
frontal  and  occijdtal  lobes  and  above  the  temporo-sphenoidal  lobe.  It  is  bounded  in 
front  by  the  fissure  of  Rolando.  Internally  it  is  continued  into  the  mesial  surface 
of  the  hemisphere,  Avhere  it  is  marked  oft'  from  the  adjacent  lobes  by  the  upturned 
end  of  the  calloso-marginal  fissure  in  front,  by  the  intornal  i>arieto-o(ci]>ital  fissure 
behind,  and  more  ol)Scurely  below  by  the  variable  sulcus  subparietalis.  On  the 
convex  surface  of  the  hemisphere  the  posterior  limits  of  the  parietal  lobe  are  in  a 
great  measure  artificial.  The  external  parieto-occipital  fissure  marks  it  oft'  for  a  short 
distance,  and  the  l)oundarv  is  then  crossed  by  convolutions  termed  annectant  gyri, 
Avhich  run  in  a  sagittal  direction  and  so  bring  the  parietal  and  occi})ital  lobes  into 
direct  continuity.  There  is,  hoAvever,  a  notch,  the  pree-occipitnl  notch  (fig.  410), 
placed  at  the  loAver  margin  of  the  hemisphere  between  the  occipital  and  temporal 
lobes,  and  if  a  line  be  draAvn  from  the  extremity  of  the  external  jtarieto-occipital 
fissure  to  this  notch,  the  upper  ])art  of  the  line,  together  Avith  the  external  parieto- 
occipital fissure,  separates  the  parietal  from  the  occipital  lobe.     The  parietal  lolje 


686  THE  NERVOUS  SYSTEM 

is  limited  below  Ijy  the  posterior  limb  of  the  Sylvian  fissure  in  the  horizontal  part 
of  its  course,  and  behind  this  its  lower  limits  are  artificially  maj^ped  out  by 
l)roducing  the  horizontal  part  of  the  Sylvian  fissure  backwards  to  meet  the  posterior 
boundary.  The  ])arietal  lobe  contains  one  fissure  of  importance — the  intraparietal. 
The  intraparietal  fissure  is  a  system  of  three  fissures,  viz.  a  superior  and  an 
inferior  vertical,  })hu-cd  jiarallel  to  the  fissure  of  Rolando;  and  a  horizontal  placed  at 
right  angles  to  the  other  two.  These  parts  may  in  rare  cases  remain  sejjarate,  but 
most  connnonly  are  united  with  one  another,  forming  a  T-shaped  figure.  Moreover, 
the  horizontal  part  may  unite  with  a  fourth  part,  the  ramus  occipitalis,  which 
extends  into  the  occipital  lobe. 

Tlie  iiitniparietal  fissure  has  been  hitherto  regarded  as  consisting  of  an  ascending  and  a  liuri- 
zontal  part  ;  the  upper  vertical  limb  (postcentral  sulcus)  being  detached.  This  is  a  coiuukjh 
variety  of  the  fissure,  but  it  has  recently  been  shown  that  the  T-shaped  form  is  the  commonest 
or  normal  arrangement.     (Cunningham.) 

The  convolutions  of  the  parietal  lobe  are:  an  ascending  parietal,  bounding  the 
fissure  of  Rolando  posteriorly  and  placed  between  that  fissure  and  the  intraparietal 
sulcus;  and  two  parietal  lol^ules,  a  superior  and  an  inferior,  placed  above  and  below 
the  horizontal  limb  of  that  fissure.  The  inferior  parietal  lobule  is  further  sub- 
divided into  an  anterior  part  called  the  supramarginal  convolution,  a  middle,  termed 
the  angular  gyrus,  and  a  posterior  part,  the  post-parietal  convolution. 

The  ascending  parietal  convolution  extends  from  the  posterior  liml)  of  the 
Sylvian  to  the  great  longitudinal  fissure,  and  is  bounded  in  front  by  the  fissure  of 
Rolando,  and  behind  by  the  intraparietal  sulcus.  It  is  continuous  Avith  the  supra- 
marginal  convolution  below  the  intraparietal  fissure,  and  at  its  upper  end  is  con- 
tinued into  the  paracentral  lobule  on  the  inner  surface  of  the  hemisphere. 

The  superior  parietal  lobule  is  a  scpiarish  mass  indented  on  the  surface  by 
tertiary  fissures.  It  is  limited  internally  by  the  margin  of  the  great  longitudinal 
fissure  where  it  becomes  continuous  with  the  prsecuneus.  The  anterior  end  of  the 
ramus  occipitalis  of  the  intraparietal  fissure  terminates  in  this  lobule  Avhen  it  is 
not  continuous  with  the  remainder  of  the  intraparietal  fissure,  and,  in  such  cases, 
the  superior  and  inferior  parietal  lobules  are  continuous  posteriorly.  The  superior 
])arietal  loljule  is  joined  in  front,  by  a  convolution  of  variable  breadth,  with  the 
ascending  parietal,  and  is  connected  behind  to  the  suj^erior  occipital  convolution  by 
the  first  annectant  gyrus. 

The  supramarginal  convolution  is  the  anterior  part  of  the  inferior  parietal 
lobule.  It  arches  around  the  upturned  extremity  of  the  posterior  limb  of  the 
fissure  of  Sylvius.  It  is  continuous  in  front  with  the  ascending  parietal  convolu- 
tion, behind  Avith  the  superior  temporal  gyrus  and  also  Avith  the  angular  gyrus.  It 
is  often  very  obscurely  marked  off  from  the  latter. 

The  angular  gyrus  is  placed  behind  the  preceding  and  embraces  the  extremity 
of  the  parallel  fissure.  It  is  continuous  behind  Avith  the  middle  temporal  convolu- 
tion. It  is  also  usually  connected  to  the  middle  occipital  convolution  by  the  third 
annectant  gyrus. 

The  post-parietal  convolution  forms  the  posterior  ])art  of  the  inferior  parietal 
lobule.  It  curves  round  the  second  temi^oral  sulcus  and  joins  the  third  temporal 
convolution. 

The  OCCIPITAL  LOBE  occupies,  approximately,  the  portion  of  the  cranial  cavity 
Avhich  is  interjwsed  betAveen  the  superior  fossae  of  the  occipital  bone  and  the  tent- 
orium cerebelli.  It  presents  three  very  distinct  surfaces:  a  convex  su])ero-externa], 
a  mesial  or  internal,  and  a  tentorial.  The  latter  looks  doAVUAvards  and  slightly 
iuAvards.  These  three  surfaces  meet  at  the  occii)ital  ]>ole.  It  is  shar])ly  marked 
off  on  the  mesial  surface  by  the  internal  parieto-occipital  fissure.  On  the  convex 
surface  the  line  of  demarcation  (as  already  described  in  treating  of  the  parietal 
lobe)  is  made  l\v  draAving  a  line  from  the  extremity  of  the  external  i)arieto-occipital 
fissure  to  the  pra;'occi))ital  notch  (fig.  410).  This  line  separates  the  occipital  from 
the  parietal  and  temjjoral  lobes. 

The  praeoccipital  notch  (fig.  410)  is  produced  by  the  impression  of  the  A'eins 
AA'hich  enter  the  lateral  sinus.     Another  impression  (fig.  410,  n),  Avhich  is  produced 


OCCIPITAL   ASD    TEMPORAL   LOBES  687 

by  the  superior  border  of  the  petrous  portion  of  the  temporal  Ijone,   bus  been 
sonu'tinies  described  as  the  pra^occipital  notch. 

It  is  generally  stated  that  the  occipital  lobe  passes  into  the  temporal  lobe  on  the  tentorial 
surface  without  any  line  of"  demarcation.  A  number  of"  methods  of  marking  off"  the  occipital  lobe 
have  been  jiroposed  by  different  authors.  These  are  all  largely  artificial.  The  occipital  lobe  is 
due  to  a  backward  growth  common  to  the  parietal  and  temporal  lobes.  That  growth  carries  with 
it  a  jtrolongation  of  the  lateral  ventricle,  forming  the  posterior  cornu.  The  occipital  lobe  is  there- 
fore that  jiart  of  the  hemisphere  which  contains  the  posterior  cornu.  It  maj^  be  maiked  off  on 
the  teutoiial  surface  by  a  line  drawn  from  the  praeoccipital  notch  to  the  extremity  of  the  jjarieto- 
occij)ital  fissure  at  the  isthmus  of  the  gyrus  fornicatus  (fig.  4f  1).  The  remaining  boundaries  will 
be  the  parieto-oecipital  fissure  for  its  entire  length  and  (as  before)  a  line  drawn  from  the  extremity 
of  the  external  parieto-oecipital  fissure  to  the  prseoccipital  notch. 

The  fissures  on  the  convex  surface  of  the  occipital  lobe  are  the  superior,  middle, 
and  inferior  occipital  fissures;  to  these  may  be  added  the  ramus  occipitahs  of  the 
intraparietal  fissure  with  its  appendage  the  transverse  occipital  fissure. 

The  superior  occipital  fissure  may  be  represented  by  a  direct  continuation  of 
the  intraparietal  fissure  to  the  occipital  pole  of  the  cerebrum.  More  commonly, 
however,  it  is  limited  to  the  posterior  part  of  the  occipital  lobe  (fig.  409,  right 
side),  and  is  not  continuous  with  the  intraparietal  fissure.  The  ramus  occipitalis 
of  the  intraparietal  fissure  may  be  directly  continued  into  the  occipital  lobe  from 
the  horizontal  limb  of  the  main  fissure,  or  it  may  commence  in  the  superior  parietal 
lobule.  In  either  case  it  passes  backwards  into  the  occipital  lobe  between  the  first 
and  second  annectant  gyri,  and  usually  terminates  a  short  distance  behind  the 
external  parieto-oecipital  fissure  by  dividing  into  two  branches  which  extend 
upwards  and  downwards  at  right  angles  to  the  main  fissure,  and  together  constitute 
the  transverse  occipital  fissure. 

The  middle  occipital  fissure  is  often  feebly  developed.  It  is  directed  from 
l)efore  IjackAvards  and  meets  the  superior  occipital  fissure  at  the  occipital  pole. 

The  inferior  occipital  fissure  is  placed  along  the  margin  which  separates  the 
convex  surface  from  the  tentorial  surface  of  the  hemisphere.  It  may  extend  in  a 
tortuous  manner  from  the  praeoccipital  notch  to  the  occipital  pole  of  the  hemi- 
sphere but  is  often  broken  up  by  one  or  more  convolutions  crossing  it. 

The  convolutions  on  the  convex  surface  are  three  in  number,  and  are  imper- 
fectly marked  off  from  one  another  by  the  fissures  above  described.  They  pass 
from  before  backwards  and  become  confluent  at  the  occipital  pole. 

The  superior  occipital  convolution  is  placed  between  the  superior  occipital 
fissure  and  the  margin  of  the  great  longitudinal  fissure.  It  is  continuous  with  the 
cuneus  on  the  inner  surface  of  the  hemisphere,  and  is  joined  in  front  by  the  first 
annectant  gyrus  to  the  superior  parietal  lobule. 

The  middle  occipital  convolution  is  situated  between  the  superior  and  middle 
occipital  fissures,  and  is  united  in  front  to  the  i)Ost-parietal  by  the  second  and  third 
annectant  gyri. 

The  inferior  occipital  convolution  occupies  the  interval  between  the  middle 
and  inferior  occipital  fissures,  and  may  be  connected  to  the  middle  temporal  convo- 
lution by  a  fourth  aimectant  gyrus. 

The  annectant  gyri  are  four  small  sagittally-directed  convolutions  which  cross  the  boundary 
line  which  separates  the  occipital  from  the  parietal  and  temporal  lobes.  They  are  numbered  from 
above  d(jwnwards.  The  first  and  second  of  these  are  the  most  constant  and  are  placed  one  on  each 
side  of  the  ramus  occii)italis  of  the  intraparietal  fissure.  The  third  and  fourth  are  not  infre- 
quently absent  as  they  may  be  cut  through  by  a  fissure,  the  sulcus  occipitalis  anterior. 

The  sulcus  occipitalis  anterior  is  an  inconstant  fissure  which  is  parallel  to,  and  placed  a  little 
in  front  of,  the  anterior  boundary  of  the  occipital  lobe  on  the  convex  surface  of  the  hemis]ihere. 

The  TEMPORAL  LOBE  (temporo-sphenoidal  lobe)  is  sharply  marked  ofif  in  front 
by  the  Sylvian  fissure,  but,  as  we  have  already  seen,  it  jiasses  behind  Avithout  any 
surface  line  of  demarcation  into  the  parietal  and  occipital  lobes.  Its  anterior 
extremity  forms  a  bold  prominence  directed  downwards  and  forwards  (the  temporal 
pole  of  Broca).  It  has  four  siu'faces:  an  external,  forming  part  of  the  general  con- 
vexity of  the  hcmis])here;  an  inferior,  Avhieh  rests  on  the  great  wing  of  the  sphe- 
noid and  the  adjacent  part  of  the  petrous  jjortion  of  the  temporal  bone;  a  tentorial. 


688  THE  XERVOUS  SYSTEM 

and  a  superior,  which  is  situated  within  the  Sylvian  fissure  and  can  be  displayed 
by  pulling  up  the  operculum. 

The  boundaries  of  the  temporal  lobe  have  been  already  indicated  in  the  description  of  the 
other  lobes,  but  may  be  recapitulated  as  follows.  It  is  bounded  behiiid  by  the  lower  part  of  the 
line  drawn  from  the  external  jiarieto-uoeipital  fissure  to  the  prieocciitital  notch.  Above,  it  i.s 
limited  hv  tlie  huriznntal  part  of  the  posterior  limb  of-the  Sylvian  fissure  and  by  a  line  continuing 
the  horizitntal  direction  backwards  to  meet  the  posterior  boundary.  Its  tentorial  surface  may  be 
marked  off  from  the  occipital  lobe  by  a  line  drawn  from  the  praeoccipital  notch  to  the  isthmus  of 
the  gyrus  fornicatus. 

Three  fissures  traverse  the  temporal  lobe  in  a  direction  parallel  to  its  long  axis. 
The  first  of  these,  the  superior  temporal  or  parallel  fissure,  is  one  of  the  most  con- 
stant of  the  incomplete  fissures  of  the  cerebrum.  The  other  two,  termed  middle 
and  inferior  temporal,  seldom  appear  as  well-marked  sulci,  being  as  a  rule  broken 
up  by  fissures  and  gyri  crossing  at  right  angles  to  their  direction. 

The  collateral  fissure  on  the  tentorial  surface  is  approximately  parallel  to  the  three  temporal 
sulci ;  it  marks  off  the  temporal  from  the  falciform  lobe. 

The  parallel  fissure  commences  a  short  distance  behind  the  apex  of  the  lobe, 
and  takes  a  course  parallel  to  the  posterior  limb  of  the  fissure  of  Sylvius.  Its 
U])turned  extremity  ends  in  the  parietal  lobe,  where  it  is  embraced  by  the  angular 
gyrus. 

The  middle  temporal  fissure  runs  in  the  same  general  direction  as  the  parallel 
fissure  but  is  placed  at  a  hjwer  level.  It  may  communicate  behind  with  the  sulcus 
occipitalis  anterior. 

The  inferior  temporal  fissure  is  placed  on  the  under  surface  near  the  lateral 
margin  of  the  hemisphere.      It  is  in  a  line  with  the  inferior  occipital  fissure. 

Three  convolutions  are  j^resent  on  the  outer  surface,  running  in  an  antero- 
posterior direction.  They  are  termed  the  superior,  middle,  and  inferior  temporal 
convolutions.      They  liecome  confluent  witli  one  another  at  the  apex  of  the  lobe. 

The  superior  temporal  or  inframarginal  convolution  lies  between  the  Sylvian 
and  parallel  fissures.     It  is  continuous  alujve  witli  the  supramarginal  and  angular 

The  middle  temporal  convolution,  placed  between  the  parallel  and  the  middle 
temporal  fissures,  is  continuous  behind  with  the  angular  gyrus  and  the  post-parietal 
convolution.  It  is  usually  joined  to  the  inferior  occipital  by  the  fourth  annectant 
gyrus. 

The  inferior  temporal  convolution  is  situated  on  the  lateral  margin  of  the 
hemisphere.  It  may  Vje  coni^'cted  to  the  inferior  occipital  convolution  by  a  fifth 
annectant  gyrus. 

The  superior  surface  of  the  temporal  lol)e  is  in  contact  with  the  operculum.  It 
is  crossed  by  two  or  three  (sometimes  four)  transverse  temporal  convolutions. 
(Heschl. ) 

Dissection. — The  .student  should  now  raise  the  operculum  and  at  the  same  time  draw  the 
temporal  lobe  downwards  in  order  to  bring  the  island  of  Reil  into  view.  The  large  branches  of 
the  middle  cerebral  artery  which  lie  among  the  convolutions  of  the  island  should  be  removed, 
together  with  the  adherent  pia  mater. 

The  CENTRAL  LOBE  or  ISLAND  OF  REIL  corresponds  to  the  floor  of  the 
embryonic  fossa  Sylvii,  and  is  placed  external  to  the  claustrum.  Its  form  is  tri- 
angular; the  base  of  the  triangle  is  placed  upwards  and  inwards,  the  apex  forms  a 
prominence,  the  limen  insube,  which  separates  the  vallecula  Sylvii  from  the  fissure 
of  the  same  name.  It  is  hidden  by  tin;  o]»er('ula  and  is  sin-rounded,  except  at  the 
limen,  by  a  curved  furrow,  the  sulcus  circularis  Reilii  (Schwalbe).  From  five 
to  seven  convolutions,  the  gyri  operti,  radiate  from  the  limen  insula^.  The  island 
is  divided  into  a  larger  anterior  j)art  (pars  frontalis),  and  a  sn)aller  posterior  part 
(pars  parieto-falciformis )  by  a  constant  fissure,  the  sulcus  centralis  insulae 
(Hefltler  and  Kberstaller;,  which  has  the  same  direction,  and  is  in  the  same  plane, 
as  the  fissure  of  Rolando, 


MESIAL  AXD  TEXTORIAL  SURFACES  OF  THE  HEMISPHERE    G89 

The  jiars  ])arioto-falcit'onijis  is  usually  termed  pars  temporo-parietalis  ;  a  study  of  the  devel- 
opuieiit  oi'tliis  jiait  of  the  island  has  shown,  however,  that  it  is  connected  with  the  falciform  and 
not  with  the  temporal  lobe.     (Cunniniiham.) 

Dissection. — The  student  is  recdmuiended  to  defer  the  study  of  the  convolutions  on  the  mesial 
an<l  tentorial  surfaces  of  the  hemisphere  until  the  dissection  of  the  corpus  callosum  is  com]ileted, 
and  to  procee<l  as  follows.  He  should  luake  a  horizontal  section  through  the  uppermost  part  of 
the  cerebral  hemispheres  ;  this  will  disjilay  the  central  core  of  white  luatter  (centrum  ovale 
minus)  surrounded  by  a  convoluted  border  of  grey  matter.  Within  the  white  matter  a  number 
of  minute  vessels  will  be  seen  which  appear  as  bleeding  points  in  afresh  brain  (the  puncta  vascu- 
losa  vel  cruenta).  He  may  then  remove  successive  thin  sections  until  he  reaches  the  level  of  the 
corpus  callosum,  the  fibres  of  whicli,  spreading  out  into  the  hemisphere,  form  an  extensive  white 
layer  called  the  centrum  ovale  majus.  A  far  more  instructive  dissection,  however,  can  be  made 
by  cautiously  tearing  the  brain  substance  in  a  direction  from  within  outwards  until  the  callosal 
fissure  is  reached.  By  the  latter  method  the  following  points  can  be  made  out  in  an  ordinary 
well-hardened  brain  :  (1)  The  white  fibres  entering  each  convolution  spreading  out  so  as  to  end 
lierpendicularly  to  the  .surface.  (2)  The  fibres  from  the  body  of  the  corpus  callosum  passing  at 
hvxt  horizontally  outwards  into  the  hemisphere  and  then  diverging,  some  sweeping  upwards  to  the 
l)arietal  and  frontal  lobes,  others  bending  downwards  into  the  temporal  lobe  and  following  the  long 
axis  of  that  lobe.  At  the  point  where  they  bend  downwards  they  readily  break,^  as  they  are  here 
intersected  by  fibres  passing  upwards  from  the  inner  cap.sule.  (3)  The  fibres  from  the  anterior 
anil  jiosterior  extremities  of  the  corpus  callosum  passing  in  a  cuiTed  manner  into  the  frontal  and 
occipital  lobes  respectively,  forming  the  forceps  minor  and  the  forceps  major.  (4)  A  set  of 
fibres,  known  as  the  cingulum,  which  ran  within  the  gyrus  fornicatus,  forming  a  sagittally- 
directed  arch.  The  dissector  should  next  study  the  corpus  callosum  and  the  convolutions  on  the 
inner  face  of  the  hemisphere.  The  convolutions  on  the  tentorial  .surface  may  be  learned  from  a 
mounted  specimen,  or  better  still  from  a  cast  of  a  cerebral  hemisphere,  and  the  actual  convolu- 
tions can  be  examined  when  the  hemispheres  are  cut  away  from  the  mesencephalon  at  a  later 
stage. 

Mesial  and  tentorial  surfaces  of  the  hemisphere. — The  mesial  surface  of 
the  hemif^phere  is  marked  off  from  both  the  convex  siipero-external  and  the  tentorial 
surface  by  the  margin  of  the  great  longitudinal  fissure.  This  margin  follows  a 
curved  course  as  a  well-defined  border  from  the  posterior  extremity  of  the  gyrus 
rectus  as  far  as  the  occipital  pole  of  the  cerebrum.  From  this  point  it  passes  for- 
wards and  pursues  a  slightly  curved  course  to  the  splenium  of  the  corpus  callosum 
immediately  beneath  which  it  ends.  The  latter  part  is  termed  by  8chwalbe  the 
internal  occipital  border ;  it  is  only  seen  in  carefully-hardened  brains,  and  appears 
as  a  rounded  margin  crossing  the  lobulus  lingualis,  and  in  front  of  this  marking 
the  gyrus  fornicatus  immediately  above  its  isthmus  (fig.  411).  The  tentorial 
surface  is  marked  off  from  the  supero-external  surface  by  a  well-defined  border 
which  extends  from  the  occipital  pole  to  the  extremity  of  the  temporo-sphenoidal 
k)be.  forming  a  slight  curve  with  the  convexity  upwards.  The  fissural  system  of 
tlie  mesial  and  tentorial  surfaces  is  of  considerable  importance  and  interest,  as  all 
the  complete  fissures  of  the  cerebrum  appear  on  these  surfaces.  These  fissures  are, 
as  already  mentioned,  the  internal  parieto-occipital.  the  calcarine,  the  dentate,  and 
the  collateral.  The  calloso-marginal,  a  constant  and  important  incomplete  fissure, 
is  also  to  be  .seen  on  the  mesial  surface. 

The  calloso-marginal  fissure  commences  below  the  genu  of  the  corpus  callosum 
aufl  pursues  a  curved  course  parallel  to  the  corj)Us  callosum  until  it  reaches  a  point 
a  short  distance  behind  the  upper  extremity  of  the  fissure  of  Rolando.  It  then 
bends  upwards  and  extends  on  to  the  convex  surface  for  a  short  distance,  where  it 
indents  the  upper  end  of  the  ascending  parietal  convolution.  Tavo  branches  which 
pass  from  this  fissure  deserve  special  mention  as.  although  not  constantly  present, 
they  form  useful  lines  of  demarcation..  One  of  these,  the  sulcus  paracentralis, 
]>asses  upwards  between  the  paracentral  and  the  marginal  convolutions.  Another, 
the  post-limbic  or  sulcus  subparietalis,  passes  backwards  from  the  bend  of  the 
main  fissure  and  se}>aratrs  tlio  in-ieeuneus  from  the  gyrus  fornicatus. 

The  parieto-occipital  fissure  commences  at  the  isthmus  of  the  gyrus  fornicatus, 
and  passes  at  first  backwards  and  upwards,  and  then  almost  vertically  upwards  to 
reach  the  margin  of  the  hemisphere,  where  it  bends  outwards  and  ends  as  the 
external  ])arieto-occipital  fissure. 

The  calcarine  fissure  commences  by  a  bifid  extremity  near  the  occipital  pole, 
and  passes  horizontally  forwards  with  a  sliglitly  curved  course  to  become  confluent 
\vith  the  parieto-occipital  fissure. 
44 


690 


THE  XER VOL'S  SYSTEM 


From  what  has  been  said,  it  follows  tliat  the  internal  pavieto-occipital  and  calcaiine  fissuivs 
form  bj'  their  union  a  Y-shai)ed  titrure.  The  hinder  part  of  the  stem  of  the  Y  and  the  fore  ijart 
of  the  ealcarine  tissure  i)roduL-e  an  elevation  within  the  i)OSterior  corim  of  the  lateral  ventricK- 
known  as  the  hippocamims  minor.  It  has  been  recently  shown  that  in  its  (levelopmeut  the  stem 
of  the  Y  may  belong  to  the  parieto-occipital  fissure  alone,  or  to  the  ealcarine  alone,  or  may  be 
common  to  both.     (Cunningham.) 

Tlu'  callosal  fissure  is  a  deep  furrow  which  follows  the  curve  of  the  corpus  cal- 
losuni,  being  placed  between  that  body  and  the  gyrus  fornicatus.  It  commences 
below  the  rostrum  of  the  corpus  callosum  and  termmates  behind  the  splenium, 
where  it  becomes  continuous  with  the  dentate  fissure. 

The  dentate  or  hippocampal  fissure  extends  from  the  splenium  of  the  corpus 
callosum  to  tlie  hooked  extremity  (uncus)  of  the  uncinate  gyrus.  It  produces  an 
elevation  in  the  descending  cornu  of  the  lateral  ventricle,  which  is  termed  the 
hipi^ocanijius  major. 

The  collateral  fissure  is  common  to  the  occipital  and  temporal  lobes.     It  passes 


Fig.  411— Convolutions  and  Fissures  on  the  Mesial  and  Tentorial  Surfaces  of  the 

Hemisphere. 


PARACEXTRAL  LOBULE 


PR.^CU\E 


SULCUS  SI 
PARI  ETA 

PARIKTu- 

OCCIPITAL 

FISSURE 


SULCUS  PARACEXTRALIS 


CUXEUS 


CiL- 
CARIM 
FISIX  III 


CALLOSO-MARGIXAL  FISSURE 

3IAROIXAL 

COXVOLUTIOX 


FORXICA  TUS 


LOB UL US  LI^ i.l  Al.l^ 


IXFERIOR  OCCIPITO-TEMPORAL  / 

COXVOLUTIOX  I 

D EX  TATE  FISSURE 


FISSURE  OF  SYLVIUS 


\CISURA   TEMPORALIS 


UXCUS 


IMPRESSIO  PETROSA        TEXTORIAL  GROO  VE 


from  a  point  on  the  under  surface  of  the  temporal  lol>e,  near  its  apex  to  the 
occipital  pole  of  the  hemisphere.  The  reverse  of  this  fissure  appears  as  an  elevation 
(the  eminentia  collateralis)  in  the  descending  cornu  of  the  lateral  ventricle. 
The  follow-ill*'-  convolutions  appear  on  the  mesial  and  tentorial  surfaces:— 
The  marginal  convolution  commences  below  the  rostrum  of  the  corpus  callosum 
and  occui.ies  tin-  area  of  the  mesial  surface  between  the  calloso-margmal  fissure  and 
the  margin  of  the  hemis].here  as  far  as  the  iiaracentral  sulcus.  The  latter  separates 
it  from  the  paracentral  lobule.  It  is  continuous  around  the  margin  ot  the  hemi- 
sphere with  the  gyrus  rectus,  the  internal  orbital,  and  the  superior  frontal  con- 
volutions. It  is  marked  bv  tertiary  fissures  along  its  whole  course,  m  particular 
by  a  fissure  which  runs  for  "some  distance  parallel  to  the  calloso-margmal  sulcus 

The  paracentral  lobule  is  ])ounded  in  front  by  the  paracentral  sulcus;  below 
and  beViind  bv  the  calloso-marijinal  fissure.  It  is  continuous  around  the  margin  ot 
the  hemisi)here  with  the  tuscending  frontal  and  ascending  jiarietal  convolutions; 
but  as  it  is  connected  with  the  former  by  a  much  In'oader  band  than  with  the  latter. 


MESIAL   AXD   TENTORIAL   SURFACES  OF  HEMISPHERE        G91 

Wlien  the  typical  backward  turn  c^f  the  upper  extremity  of  the  fissure  of  Rolando  is  ]jresent, 
it  hooks  backwards  iiit(j  tlie  fbrwaid  bend  formed  by  the  upper  extremity  of  the  calloso-marginal 
fissure,  and  thus  the  frontal  and  jiarietal  lobes  are  only  connected  by  a  narrow  istlimus  between 
the  two  fissures. 

The  gyrus  fornicatus,  or  gyrus  cinguli,  Avhich  forms  part  of  tlie  limbic  lobe, 
commences  between  the  rostrum  of  the  corj^us  callosum  and  the  extremity  of  the 
marginal  convolution,  and,  }»ursuing  an  arched  course  ]»arallel  to  the  corpus 
callosum,  ends  in  a  narrow  convolution,  the  isthmus,  which  connects  it  to  the 
uncinate  gyrus.  It  is  placed  between  the  calloso-marginal  and  callosal  fissures, 
and  is  thus  clearly  marked  off  from  adjacent  structures  in  the  greater  part  of  its 
extent,  but  is  often  very  imperfectly  separated  from  the  superior  parietal  lobule. 
It  may  also  be  connected  to  the  hinder  end  of  the  marginal  convolution  by  a 
small  gyrus  crossing  the  calloso-maruinal  fissure. 

The  praecuneus,  or  quadrate  lobule,  is  a  squarish  mass  of  small  gyri  which  is 
continuous  around  the  margin  of  the  hemisphere  with  the  superior  parietal  lobule. 
It  is  l)ounded,  in  front  by  the  upturned  end  of  the  calloso-marginal  fissure;  behind, 
l)y  the  parieto-occi])ital  fissure;  and  it  may  be  marked  off  below,  from  the  gyrus 
fornicatus,  by  the  sulcus  subparietalis. 

The  cuneus,  or  cuneate  lobule,  is  a  wedge-shaped  mass  occupying  the  interval 
between  the  internal  parieto-occipital  and  calcarine  fissures.  It  is  continuous 
around  the  margin  of  the  hemisphere  with  the  superior  occipital  convolution.  In 
a  properly  hardened  right  hemisphere  it  shows  a  distinct  bevelling  near  the  margin. 
This  is  produced  by  the  impression  of  the  superior  longitudinal  sinus.  This 
bevelling  can  be  traced  downwards  to  the  extremity  of  the  lobulus  lingualis,  and  less 
distinctly  forwards  to  the  precuneus.  In  rare  instances  it  may  be  seen  in  the  left 
hemisphere  instead  of  the  right. 

Two  sagittally  directed  convolutions  are  situated  on  the  tentorial  surface.  They 
are  termed  the  superior  and  inferior  occipito-temporal  convolutions.  The 
superior  of  these  is  divided  into  an  anterior  part  called  the  uncinate  gyrus,  and  a 
posterior  part  which  is  known  as  the  lobulus  lingualis. 

The  uncinate  convolution  commences  behind  at  the  isthmus,  by  which  it  is 
continuous  with  the  gyrus  fornicatus,  and  ends  immediately  behind  the  anterior 
perforated  space  in  a  hook-like  elevation,  the  uncus.  It  is  separated  from  the 
dentate  convolution  by  the  dentate  fissure,  it  is  marked  off  from  the  inferior 
occi]^it<^)-tem])oral  convolution  by  the  collateral  fissure  and,  in  front  of  this,  by  the 
incisura  temporalis,  it  forms  part  of  the  limbic  lobe.  The  outer  part  of  the 
anterior  end  is  marked  by  a  distinct  gi'oove,  which,  as  it  is  jiroduced  by  the  free 
edge  of  the  tentorium  cerelDelli,  may  be  called  the  tentorial  groove  (fig.  411). 

The  uncinate  convolution  is  covered  with  a  peculiar  fine  network  of  white  fibres,  the  sub- 
stantia reticularis  alba.  These  fibres  are  derived  from  the  stria?  longitudinales  laterales  which 
l>ass  i'roni  the  splenium  of  the  corpus  callosum  on  to  the  istlimus,  and  from  thence  to  the  uncinate 
gyrus. 

The  dentate  convolution  or  fascia  dentata  will  be  more  conveniently  described  with  the 
anatomy  of  the  lateral  ventricle,  as  it  is  usually  dissected  in  connection  with  that  cavity. 

Tlie  lobulus  lingualis  is  the  posterior  part  of  the  superior  occipito-temporal 
convolution.  It  is  bounded  by  the  calcarine  and  parieto-occipital  fissures  above,  and 
by  the  collateral  fissure  below.  As  the  internal  occipital  border  crosses  this  lobule 
it  divides  it  into  two  parts,  an  upper  part  which  appears  on  the  mesial  surface,  and 
a  larger  loAver  portion  situated  on  the  tentorial  surface. 

The  inferior  occipito-temporal  convolution  extends  from  the  apex  of  the 
temporal  lobe  to  the  occi])ital  })olc  of  the  hemis})here.  It  is  l)ounded  above  by 
the  collateral  fissure,  and  below  l)y  the  inferior  temporal  and  inferior  occipital 
fissures.  It  is  marked  by  the  impressio  petrosa  at  the  junction  of  its  anterior  and 
middle  thirds. 

Three  distinct  impressions,  which  lie  in  a  line  with  one  another,  are  produced  on  the  brain  by 
the  petrous  portion  of  the  temporal  bone.  One  of  these  (fig.  410,  //)  corresponds  to  the  jwrtion 
of  1)1  ine  opposite  the  confluence  of  the  .superior  petrosal  with  the  lateral  sinus.  Another,  the 
impressio  petrosa,  which  may  be  large  and  conspicuous,  is  caused  by  the  prominence  of  the 


692  THE  X  KB  VOLS  SYSTEM 

superior  scuneircular  canal.     The  third  impression  (incisura  temporalis)    is  situated   near  the 
vallecula  Sylvii,  about  one-third  of  an  inch  external  to  the  tentorial  groove. 

The  LIMBIC  LOBE  lies  on  the  mesial  and  tentorial  surfaces  of  the  cerebrum.  It 
ii?  bounded  externally  by  the  calloso-marginal  sulcus,  the  subparietal  or  post-limbic 
sulcus,  the  stem  of  the  calcarine  tissure,  and  the  collateral  fissure.  It  consists  of 
an  outer  part  formed  by  the  callosal  convolution,  the  isthmus  and  the  uncinate 
gyrus,  and  an  inner  part  in  which  are  included  the  fornix,  the  sei)tum  lucidum, 
the  stria?  longitudinales  mediales  and  laterales,  and  the  fascia  dentata,  all  of  which 
will  be  subsequently  described. 

THE  OLFACTORY  LOBE. — The  olfactory  lobe  attains  a  considerable  size  in  some 
of  the  lower  mammals,  and  in  them  it  may  contain  a  prolongation  of  the  lateral 
ventricle  in  its  interior;  in  seals  it  is  small,  in  cetacea  it  is  absent,  and  in  monkeys 
and  men  it  is  rudimentary.  Its  anterior  part  is  developed  as  an  outgrowth  of  the 
cerebral  vesicle,  but  the  cavity,  which  is  present  at  first,  soon  disappears  in  man, 
thougli  its  position  is  indicated,  even  in  the  adult,  by  the  remains  of  the  ependyma 
which  lined  it. 

The  olfactory  lobe  is  divided  into  two  lobules — the  anterior  and  the  posterior. 
The  constituent  parts  of  the  anterior  olfactory  lobule  are  the  bulb,  the  tract, 
the  trigonum  olfactorium,  and  the  olfactory  area  of  Broca.  It  is  separated  from 
the  posterior  olfactory  area  by  a  curved  fissure,  fissura  prima,  which  runs  outwards 
from  the  great  longitudinal  fissure  in  front  of  the  anterior  perforated  space. 

The  olfactory  bulb  is  an  ovoid  mass  of  gray  and  white  matter  a  little 
more  than  a  thircl  of  an  inch  long  (1  cm.)  and  about  a  sixth  of  an  inch  (4  mm.) 
wide.  It  rests  below  on  the  cribriform  plate  of  the  ethmoid  bone,  and  is  lodged 
above  in  the  olfactory  sulcus  on  the  orbital  surface  of  the  frontal  lobe.  About 
twenty  olfactory  nerves  spring  from  its  lower  surface  and  pass  through  the  foramina 
in  the  cribriform  plate. 

The  olfactory  tract  is  a  triangular  band  of  white  matter  Avhich  extends 
backwards  f]-om  the  posterior  extremity  of  the  bulb.  It  is  about  three-quarters  of 
an  inch  long  (2  cm.)  and  one-tenth  of  an  inch  broad  (2.5  mm.).  Its  apex  is 
embedded  in  the  olfactory  sulcus  and  its  lower  surface  rests  on  the  presphenoid 
bone  (juguni  sphenoidale).  Posteriorly  it  terminates  in  two  roots,  the  mesial  and 
lateral,  which  enclose  the  trigonum  olfactorium.  The  lateral  root  passes  outwards 
and  backwards  across  the  anterior  perforated  space  to  the  anterior  end  of  the 
uncinate  gyrus;  the  mesial  root  curves  inwards  behind  Broca's  olfactory  area  and 
becomes  continuous  with  the  lower  end  of  the  callosal  gyrus.  The  anterior  olfac- 
tor}'  lobule  is,  therefore,  intimately  connected  with  the  anterior  part  of  the  limbic 
lobe,  the  two  together  forming  the  rhinencephalon,  or  racquet-shaped  lobe  of  Broca. 

The  trigonum  olfactorium  is  a  small  triangular  area  of  gray  matter  enclosed 
between  the  two  roots  of  the  olfactory  tract  and  bounded  behind  by  the  fissura 
prima. 

Broca's  olfactory  area  is  a  small  part  of  the  posterior  end  of  the  gyrus 
rectus  separated  off  from  the  remainder  by  a  small  oblique  sulcus  called  the  fissura 
serotina  and  bounded  ])osteriorly  and  externally  l)y  the  mesial  root  of  the  olfactory 
tract. 

The  posterior  olfactory  lobule  is  that  jxtrtion  of  the  gray  cortex  which 
forms  the  anterior  perforated  space.  It  is  bounded  internally  by  the  peduncle  of 
the  corpus  callosum,  anteriorly  by  the  fissura  prima  which  separates  it  from  the 
anterior  olfactory  lobule,  and  it  extends  externally  into  the  vallecula  Sylvii,  being 
crossed  by  the  lateral  root  of  the  olfactory  tract. 

The  Corpus  Callosum  is  a  great  white  transverse  commissure  which  unites  the 
cerebral  hemisi)heres.  Its  form  can  be  well  studied  in  a  mesial  section  of  the  brain 
(fig.  412),  in  which  it  a])pears  as  a  longitudinal  arch  with  rounded  anterior  and 
l)osterior  extremities.  The  posterior  extremity  is  called  the  splenium  ;  it  is 
rounded  off  ])ehind  and  is  formed  by  the  corpus  callosum  doul)ling  on  itself,  so  that 
a  small  portion  is  folded  forwards  under,  and  in  close  opposition  to,  the  larger  part 
(fig.  413).  The  anterior  extremity  or  genu  is  less  sharply  bent  than  the  poste- 
rior end.      It  is  continued  downwards  and  backwards  into  a  portion  which  appears 


CORPUS   CALL  OS  CM 


693 


Fig.  412. — Mesial  Sectiox  of  Extire  Brain.     (After  Heule.) 

The  (*)  points  to  the  anterior  extremity  of  the  gyru.s  fornicatus  ;  above  it  is  the  basal 

white  commissure. 


POSTERTOR      SCI.rfS  OF       MIDDLE  FORAMEN 

( OVVISitL'RE       MONRO      COVVISSURF       OF  MONRO 


PI\F4L  BODY 
SPLFJNIL  M  OF 
CORPUS  CAIIOSUM 

LAMINA 
)UADRIGEMINA 


I  /        (  iLIO'iil   FISSlRl 


ICIDLM 


li\TFRIOR 
COMMISSURE 


AQr'FDfc 
OF  SYLVirs 

VA  L  VE  OF 
VIEUSSFSS 


CEREBELL L M 
FOURTH  VENTRICLE 


UMIM    CI^EREA 


MEDULLA      I  '  >        BODY 

PONS  CORPUS    TUBER 

ALBICANS    CINEREUM 


.SECOND  i\ERVE 
OPTIC  COMMISSURE 


Fig.  413. — A  Dissection   of  the  White  Matter  of  the  Posterior  Part  of  the   Ki(;ht 

Cerebral  Hemisphere. 

(Viewed  from  the  inner  side.     Schwalbe.) 

REDUPLICATED  SPLENIUM  OF 

PORTION  OF  SPLENIUM      CORPUS  CALLOSUM      FORCEPS  MAJOR 


OCCIPITAL  POLE 


CORPUS 
CALLOSUM 

OPTIC 

THALAMUS  " 

CORPUS 

GENICULATl  M 

INTERNUM 


TEGMENTUM 


■^^1.  \kryJA    /<r(  \    \ 


PULVINAR 


TAP  I  TUM 


FASCICUL  US  LONGITUDINA  LIS 
INFERIOR 


G94  THE  NERVOUS  SYSTEM 

pointed  in  section  and  is  called  the  rostrum.  The  rostrum  is  connected  to  the 
lamina  cinerea  by  a  thin  layer  of  white  substance,  the  basal  white  commissure. 
The  portion  which  intervenes  between  the  splenium  and  rostrum,  and  which  con- 
stitutes the  greater  part  of  the  corpus  callosum,  is  called  the  body.  The  under 
surface  of  the  l)ody  is  adherent  behind  to  the  fornix,  and  in  front  to  the  sejitum 
lucidum.  In  coronal  sections  (tigs.  415  and  428)  it  can  be  seen  that  the  under  surface 
is  free  for  some  distance,  except  at  its  attachment  in  the  middle  line  to  the  fornix 
and  septum  lucidum.  This  free  portion  forms  the  roof  of  the  lateral  ventricles. 
The  upper  surface  remains  free  for  a  shorter  distance  than  the  lower,  and  ends  at 
the  floor  of  the  callosal  fissure,  where  the  fibres  of  the  corpus  callosum  enter  the 
substance  of  the  hemisphere.  It  forms  in  the  transverse  direction  a  gentle  curve 
with  the  concavity  directed  upwards.  Viewed  from  above,  the  corpus  callosum  is 
seen  to  present  a  transverse  striation,  this  being  an  indication  of  the  bundles  of  fibres 
passing  from  hemisphere  to  hemis})here.  These  transverse  striations  are  crossed 
superticially  by  narrow  longitudinal  l)ands,  the  strise  longitudinales  mediales  and 
the  strite  longitudinales  latcrales  or  ticnite  tecta\ 

The  striae  longitudinales  mediales  are  placed  one  on  each  side  of  the  middle 
line,  and  lie  very  close  together,  leaving  a  narrow  interval  between  them  which  is 
called  the  raphe.  Traced  forwards,  they  slightly  diverge  and  pass  round  the  genu 
to  the  rostrum;  here  they  separate  more  widely,  and  pass  along  the  inner  margin 
of  the  anterior  perforated  space,  under  the  name  of  the  peduncles  of  the  corpus 
callosum,  and  are  lost  at  the  commencement  of  the  fissure  of  Sylvius.  Traced 
1  »ackwards  each  medial  stria  is  found  to  be  continuous  at  the  splenium  of  the  corjjus 
callosum  with  the  fasciola  cinerea.  This  turns  round  the  splenium  and  is  con- 
tinuous beneath  it  with  the  fascia  dentata. 

The  taeniae  tectae,  or  striae  longitudinales  laterales,  lie  on  the  u})per  surface 
of  the  corpus  callosum  under  cover  of  the  callosal  gyrus.  They  also  can  be  traced 
backAvards  round  the  splenium  into  continuity  Avith  the  fasciola  cinerea.  The 
medial  and  lateral  striae  together  represent  the  free  margin  of  the  gray  matter 
on  the  inner  surface  of  the  brain,  in  the  same  Avay  that  the  fascia  dentata  represents 
it  on  the  tentorial  surface,  and  they  constitute  the  remains  of  a  degenerated  supra- 
callosal  gyrus. 

The  fibres  of  the  corpus  callosum  after  entering  the  cerebral  substance  spread  out  to  every 
])art  of  the  hemispheres  (with  the  exception  of  small  portions  of  the  temporal  lobes)  in  the 
following  sets  : — 

The  fibres  from  the  genu  pass  forwards  and  outwards  into  the  anterior  paitof  the  frontal 
lobe,  and  then  sweep  inwards  forming  the  forceps  minor. 

The  fibres  from  the  body  have  the  foll(nviiig  distribution  : — Tlie  uppermost  fibres  pass  out- 
wards and  then  upwards,  and  finally  curve  inwards  to  the  upper  and  mesial  surfaces  of  the  fnmtal 
and  i)arietal  lobes.  The  intermediate  fibres  pass  transverselj'  outwards  to  the  same  lobes.  The 
lowest  fibres  form  the  roof  of  the  lateral  ventricle,  and  are  separated  from  that  cavity  only  by 
the  epeudyma  and  epithelium,  and  divide  into  anterior  and  jjosterior  sets  which  are  differently 
distributed.  The  anterior  set  ends  in  the  opercula.  The  posterior  set  forms  a  layer  called  the 
tapetum  which  follows  the  descending  and  jiosterior  cornua  of  the  lateral  ventricle,  roofing  over 
and  bounding  these  cornua  externallJ^  The  part  which  follows  the  descending  cornu  is  destined 
i'or  the  temporal  lohe.  The  portion  which  accompanies  the  posterior  cornu  passes  to  the  under 
part  of  the  occipital  lobe. 

The  fibres  from  the  splenium,  and  from  the  part  which  is  folded  below  it,  pass  backwards  and 
outwards,  and  then  sweep  inwards  forming  the  forceps  major,  the  fibres  of  which  pass  to  the 
]»osti'rior  and  ujjper  parts  of  the  occipital  lobe. 

Dissection. — Having  completed  the  examination  of  the  corpus  callosum  and  of  the  mesial 
surface  of  the  hemisphere,  the  student  sliould  next  turn  his  attention  to  the  lateral  ventricles. 
The  remaining  fibres  of  the  body  of  tlu^  cor))US  callosum  should  be  divided  a  little  to  the  right 
of  the  middle  line  and  reflected  outwards.  This  dissection  will  expose  the  bo<1y  and  anteriorcornu 
of  the  lateral  ventricle.  The  posterior  and  descending  cornua  sliould  next  In:  exposed  by  removing 
their  outer  walls. 

The  Lateral  Vkntrtcles  are  cavities  in  the  cerebral  hemispheres  Avhich  are 
continuous  Avith  the  third  ventricle  and  Avith  one  another,  through  the  foramen 
commune  anterius  (page  098).  They  are  roofed  over,  as  already  cl escribed,  by  the 
corpus  callosum,  and  are  lined  throughout  by  epithelium,  Avliich  is  reflected  over  the 
choroid  plexuses,  and  is  not  continuous  Avith  the  lining  of  the  third  A-entricle  except 
at  the  foramina  of  Monro.     This  epithelial  lining  forms  the  ventricular  A\all  in 


LATERAL   VENTRICLES 


695 


the  region  of  the  so-called  transverse  fissure,  through  which  the  choroid  plexus 
projects.  This  fissure  is  therefore  not  a  breach  in  the  ventricle,  but  simply  a  thin 
part  of  the  wall  through  which  the  locally  thickened  pia  mater  (choroid  plexus) 

Fig.  414. — Diagkam.matic  Coronal  Section  of  Third  and  Lateral  Ventricles. 
(From  Schwalbe,  slightly  modified.)       lateral  VENTRICLE 

CA  UDA  TE 
NUCLEUS 

TAENIA  SEMI- 
CIRCULARIS 

Velum  interpositum 

Veins  of  Galen 

Choroid  plexuses  of  third 
ventricle 

OPTIC  THALAMUS 
THIRD  VENTRICLE 


TEGMEN 


The  red  lines  indicate  the  epithelium. 


Fig.  415. — Coronal  Section  of  the  Hemispheres  passing  through  the  Anterior 
cornua  of  the  lateral  ventricles. 

(From  a  mounted  specimen  in  the  Anatomical  Department  of  Trinity  College,  Dublin.) 


CAPSULE \~\ 
LESTICULA R  \X\ 


SVCLECS 
CLAVSTRVil 


OLFACTORY  TRACT 


GREA  T 
LOMil- 
TCUINAL 
FISSURE 

AXTERIOR 
HOR.y  OF 
LATERAL 
VESTRI- 
CLE 


GREAT 
LOSGI- 
TUDINAL 
FISSURE 


•an  be  seen.     Each  lateral  ventricle  consists  of  a  central  part  or  body  and  three 
•ornua:  an  anterior,  an  inferior  or  descending,  and  a  posterior. 

The  body  may  be  defined  as  the  portion  of  the  ventricle  which  extends  from 


696 


rilK  XKRVOUS  SYSTEM 


the  foraiiifii  of  Monro  to  the  point  where  tlie  cavity  l)ifureates  into  its  posterior 
and  deseendins:  eornua.  It  corresponds  ahno.-<t  exactly  in  length  to  the  portion  of 
the  optic  thalamus  which  lies  free  within  the  ventricular  cavity.  It  is  greatest  in 
its  antero-posterior,  and  smallest  in  its  vertical  diameter.  It  is  Hmited  on  the  inner 
side  by  the  attachment  of  the  fornix  to  the  corpus  callosum,  and  by  the  narrow 
posterior  part  of  the  septum  lucidum.  On  the  outer  side  it  is  bounded  by  the  fibre- 
of  the  corpus  callosum  entering  the  substance  of  the  hemisi^here.  Its  floor  looks 
upwards  and  slightly  inwards,  as  can  be  well  seen  in  coronal  sections,  and  is  formed 
by  a  series  of  structures  which  trend  forwards  with  an  inclination  inwards.  Thes(- 
structures  are  ]ilaced  in  the  following  order  from  without  inwards: — the  caudati- 
nucleus  of  the  corpus  striatum,  the  ttenia  semicircularis  and  lamina  cornea,  the 
optic  thalamus,  the  choroid  plexus  and  the  fornix  (figs.  414  and  419). 

The  anterior  cornu  is  directed  forwards,  downwards,  and  outwards.  It  appear^ 
crescentic  in  outline  both  in  coronal  and  horizontal  section.  The  concavity  of  the 
crescent  looks  downwards  and  outwards,  and  is  caused  b}'  the  projection  of  the 


Fig.  416.- 


-COEOXAL   SeCTIOX   OF   THE   HEAD    PASSING   THROUGH   THE   POSTERIOR   HoRXS  OF 

THE  Lateral  Ventricles. 


(From  a  mounted  specimeu  iu  the  Anatomical  Department  of  Trinity  College,  Dublin. 


Dura  mater 


Br  LB  OF 

POSTERIOR 

CORNU 

HIPPOCAM- 
PLS  xMISOJ: 


FAsncrus 

LOSalTiDl- 

y.xLis  jy- 

FERIOR 


Savri'ir 
loiiyitudinal 
sinus 


Falx  cerebri 


Strnighl  sinus 
POSTERIOR 

coRyr  OF 

LATERAL 
VEyTRICLE 

CALCARiyE 
FISSL'RE 


Lateral  sinus     CORPUS  PEyiATUM       Tentorium  cerebeUi 

caudate  nucleus  into  the  cavity.  The  anterior  cornu  is  bounded  internally  by  the 
septum  lucidum,  which  forms  a  thin  vertical  partition  between  the  anterior  eornua 
of  opposite  sides,  al>ove  and  in  front  by  the  corpus  callosum,  and  behind  and 
externally  by  the  head  of  the  caudate  nucleus. 

The  posterior  cornu  is  horizontal  in  its  whole  course,  and  is  directed  at  first 
backwards  and  outwards,  and  afterwards  backwards  and  inwards.  It  presents  on 
its  inner  wall  a  curved  prominence,  the  hippocampus  minor  or  calcar  avis  ;  and 
al)ove  this  a  second  prominence,  the  bulb  of  the  cornu,  whk-h  is  caused  bv  a  part 
of  the  force])s  major  projecting  into  the  cavity.  The  hipiiocampus  minor  is  caused 
])y  a  fold  of  the  cerel)ral  wall,  and  corresponds  to  the  calcarine  fissure  on  the 
mesial  surface  of  tlie  hemisphere  (fig.  41()).  Its  floor  i)resents  a  slight  elevation, 
caused  by  the  fasciculus  longitudinalis  inferior. 

Dissection.— Tiie  operculum  should  next  be  pulled  uiiwards,  when  the  small  portion  of  sub- 
stance still  attaching  it  to  the  brain  will  be  broken  through.     A  complete  view  of  the  island  of 


LA  TERAL   VENTRICLES 


69" 


Keil  is  then  obtained.  Lastly,  the  student  sliould  make  a  series  uftliin  sagittal  sections  thiouirh 
the  island  of  Keil  and  the  iVoMtal  lube  until  the  great  transverse  fissure  and  its  relation  to  the 
descending  cornu  of  the  lateral  ventricle  is  seen  (fig.  417).  The  sections  will  pass  through  the 
lenticular  and  caudate  nuclei  ol'the  corpus  striatum  and  through  the  optic  thalamus. 

The  inferior  or  descending  cornu  pursues  a  more  curved  and  complieated 
course  than  the  other  two  coruua.  It  is  directed  at  first  outwards  and  backwards, 
and  then  l)ends  somewhat  sharply  downwards;  lastly,  it  sweeps  forwards  Avith  an 
inclination  inwards,  following  the  long  axis  of  the  tem})oro-sphenoidal  lobe.  In 
transverse  section  it  is  seen  to  be  somewhat  triangular,  jjresenting  a  floor,  an  inner 
wall,  and  a  curved  roof  which  bounds  the  cavity  above  and  externally.  The  floor 
is  formed  by  the  eminentia  collateralis.  The  following  structures  appear  on  the 
inner  Avail: — the  hippocampus  major,  ending  in  the  pes  hii)pocampi;  the  corpus 
fimbriatum;  and  the  choroid  plexus,  the  latter  aj^parently  passing  through  a  fissure 
(the  great  transverse  fissure).  The  roof  is  formed  from  within  outwards  by  the 
taenia  semicircularis,  by  the  narrow  posterior  prolongation  of  the  caudate  nucleus 


Fig.  417. — A  Dissectiox  of  the  Descexdixg  Cokxu  of  the  Lateral  Yextricle, 
AVITH  A  Sagittal  Section  through  the  Basal  Gaxglia. 


FORNIX 


CORPUS  CALLOSVM 


Choroid  plexus 


FORCEPS  MA  JO  P. 
aiPPOCAMPr- 
MI.\ 
T.EXIA  SE.Uir/E< 
LABIS  Fl.VBI 

OPTIC  THALAM 
CORPrs  (;emi:. 

ISTERSCM 
EMISESTIA  COLLA- 
TERALIS 
CRVS  CEREBRI 
FASCIA  D  EXT  AT  A 


OPTIC  TRACT 


LEyilCrLAR  XCCLECS         CAUDATE  XUCLEUS 


of  the  corpus  striatum,  and  by  the  tapetum.  At  the  extremity  of  the  cornu  tlie 
roof  is  formed  by  the  amygdaloid  tubercle.  The  taenia  semicircularis  and  caudate 
nucleus  may  be  traced  to  this  tubercle. 

The  eminentia  collateralis  is  a  smooth  triangular  elevation,  Avhich  commences 
in  the  interA-al  betAveen  the  hippocampus  major  and  minor,  and  extends,  narroAving 
as  it  proceeds,  nearly  to  the  extremity  of  the  descending  cornu.  It  is  the  indenta- 
tion of  the  ventricular  Avail  produced  by  the  collateral  fissure. 

The  hippocampus  major,  or  cornu  Ammonis,  is  a  curved  Avhite  body  Avhich 
ends  in  a  blunt  extremity  (})cs  hijjpocampi),  on  Avhich  are  small  indentations, 
giving  it  an  obscure  resemblance  to  the  paAv  of  an  animal.  It  corresponds  tn  the 
dentate  fissure. 

The  corpus  fimbriatum,  taenia  hippocampi,  or  fimbria,  is  a  narrow  strip  of 
Avhite  matter  Avith  a  somewhat  Avavy  appearance,  Avhich  is  i>laced  along  the  concave 
side  of  the  hippocampus  major.  It  is  formed  by  a  portion  of  the  fibres  of  the 
fornix  continued  into  the  descending  cornu,  and  presents  apparently  a  free  edge 
toAvards  the  transverse  fissure,  but  is  in  reality  continued  into  the  eiiithelium  Avhich 


698 


THE  NERVOUS  SYSTEM 


covers  the  choroid  plexus.  When  this  epitheHum  is  torn  through  and  the  choroid 
plexus  pushed  forwards,  the  fascia  dentata  is  exposed;  the  latter  structure  is  placed 
above  the  dentate  fissure,  between  the  fiml)ria  and  the  uncinate  gyrus. 

The  choroid  plexuses  are  vascular  fringes  formed  i)y  an  infolding  of  the  pia 
mater  in  the  region  of  the  so-called  great  transverse  fissure.  They  extend  from 
the  termination  of  the  descending  cornua  to  the  foramina  of  Monro,  through  which 
they  disappear.  The  epithelial  lining  of  the  ventricle  passes  from  the  thin  (appar- 
ently free)  edge  of  the  fimbria  over  the  choroid  plexus  to  the  taenia  semicircularis. 
This  epithelium,  which  is  the  morphological  wall  of  the  cornu,  excludes  the  choroid 
plexus  (strictly  speaking)  from  the  ventricular  cavity. 

Tlie  foramina  of  Monro  are  the  apertures  through  Avhich  the  lateral  ventricles 
communicate  with  the  third  ventricle,  forming  at  their  communication  a  Y-shaped 
passage,  the  foramen  commune  anterius,  by  means  of  which  the  lateral  ventricles 


Fig.  418. — A  Dissection  showixg  the  Free  or  Intraventricular  Portion  of  the  Cau- 
date Nucleus.  The  Mesial  and  Tentorial  Surfaces  of  the  Hemisphere  are 
also  shown. 

(From  a  mounted  specimen  iu  the  Anatomical  Department  of  Trinity  College,  Dublin.) 


EXTRAVENTRICULAR  PART 
OF  OPTIC  THALAMUS 


SULCUS 
CHOROIDEUS 


CALLOSO-MARGISA  I, 
FISSURE 


CORPl'S  CALLOSVM 


INTFR  \  4  /■ 

PAH  It  TO 

OCCII  IT\r 

FIS:i  L  KL 


~  COMMISSrRE 
BVSDLE  OF 
r/ry  DAy.YR 


DENTA  TE 

FLSSURE 


CORPUS  GENICULA  TUM 
INTERXUM 


UNCUS 


of  opposite  sides  communicate  with  one  another.  The  clioroid  plexuses  of  the 
lateral  ventricles  are  continuous  with  one  another  through  this  passage.  Each 
foramen  of  ]\Ionro  is  crescentic  in  outline,  and  is  bounded  in  front  and  above  by 
the  anterior  pillars  of  the  fornix;  below  and  behind  by  the  anterior  extremity  of 
the  optic  thalamus;  and  l)ohin(l  V)y  the  reflexions  of  ei)itlielium  from  the  fornix  and 
optic  thalamus  on  to  tlic  clioroid  plexus. 

The  fascia  dentata,  or  dentate  convolution,  is  the  free  edge  of  the  grey 
matter  of  the  hemisphere,  and  derives  its  name  from  its  characteristically  notched 
or  indented  appearance.  It  is  placed  above  the  dentate  fissure,  and  follows  this 
fissure  upwards  towards  the  splenium  of  the  corpus  callosum,  where  it  becomes 
continuous  with  the  fasciola  cinerea.  The  fasciola  cinerea  is  a  grey  lamina 
resembling  the  fascia  dentata  but  with  a  smooth  margin.  It  ends  just  above  the 
splenium  of  the  corpus  callosum. 


BASAL    GANGLIA  699 

Dissection. — The  j^tudeut  should  .slice  away  the  left  hemisphere  and  expose  the  lateral  veii- 
tricle  of  that  side,  leavitifr  the  central  injitioii  of  the  corpus  callosum  in  situ  for  the  present.  He 
.should  then  make  a  series  of  horiz(jntal  sections  throULdi  the  island  of  Reil  and  corpus  striatum  of 
tlie  left  .side.  If  he  has  carried  out  the  di.ssection  as  recommended  on  the  right  side,  he  will  now 
be  in  a  position  to  study  the  corpus  striatum  both  in  horizontal  and  vertical  section,  and  at  the 
same  time  to  examine  its  intraventricular  part  more  fully.  The  hoiizontal  sections  will  ]iass 
through  both  nuclei  of  the  corpus  striatum  with  the  inner  and  outer  cap.sules,  the  claustrum,  and 
a  portion  of  the  optic  thalamus  (tig.  41 U). 

Basal  Ganglia  of  the  Hemispheres 

A  series  of  ganglionic  masses  is  placed  in  the  base  of  each  cerebral  hemisphere. 
They  are  subjacent  (with  the  exception  of  the  amygdaloid  nucleus)  to  the  island  of 
Reil  and  form,  with  that  lobe,  the  oldest  part  of  the  hemisphere;  that  is  to  say, 
they  constitute  the  portion  which  is  (as  already  mentioned)  the  first  to  appear  both 
in  the  vertebrate  series  and  also  in  the  development  of  the  individual.  They  are 
all  semi-detached  local  thickenings  of  the  grey  cortex,  and  may  be  enumerated  as 
follows: — the  corpora  striata,  each  composed  of  tAvo  nuclei,  the  nucleus  caudatus 
and  the  nucleus  lenticularis;  the  claustra,  and  the  amygdaloid  nuclei.  The  optic 
thalami  are  in  close  proximity  to  the  corpora  striata,  but  belong  to  the  thalam- 
encephalon.  Certain  important  fasciculi  of  white  matter  are  intimately  related 
to  the  corpora  striata.  The  chief  of  these  white  fasciculi  are  the  inner  and  outer 
cai>sules,  the  anterior  commissure,  and  the  taenia  semicircularis. 

The  nucleus  caudatus  is  an  elongated  mass  of  grey  matter  somewhat  resem- 
bling a  pear  with  a  long  curved  stalk.  It  presents  a  free,  or  ventricular,  surface,  and 
a  surface  which  is  embedded  in  the  hemisphere.  It  is  thickest  at  the  anterior  end. 
or  head.  The  free  surface  of  the  anterior  thickened  portion  looks  upwards  and 
inwards,  and  bulges  into  the  anterior  horn  of  the  lateral  ventricle.  Thence  it 
ascends  with  an  inclination  outwards  to  the  body  of  the  ventricle,  where  it  forms 
the  outermost  constituent  of  the  floor  of  that  cavity,  and  narrows  into  the  com- 
mencement of  the  tail.  In  this  situation  it  is  separated  from  the  oj^tic  thalamus  by 
the  lamina  cornea  and  tsenia  semicircularis.  The  tail  of  the  nucleus  caudatus  then 
passes  into  the  descending  cornu.  It  is  placed  at  first  in  front  of  the  cornu,  after- 
wards forms  part  of  the  roof  of  that  cavity,  and  ends  at  the  amygdaloid  tubercle. 
The  deep  surface  of  the  caudate  nucleus  is  separated  from  the  nucleus  lenticularis 
b\'  a  layer  of  Avhite  matter  called  the  inner  capsule.  The  two  nuclei  are,  however, 
connected  by  bands  of  grey  matter  which  intersect  the  fibres  of  the  anterior  limb 
of  the  inner  capsule,  and  they  are  directly  continuous  for  a  short  distance  in  front. 

The  nucleus  lenticularis  is  embedded  in  the  substance  of  the  hemisphere 
except  at  the  base  of  the  brain,  where  it  comes  to  the  surface  for  a  small  part  of  its 
extent  at  the  anterior  perforated  space.  Here  it  is  continuous  externally  Avith  the 
claustrum  and,  as  before  stated,  with  the  nucleus  caudatus.  In  horizontal  section 
it  appears  like  a  bi-convex  lens,  with  its  surface  directed  outwards  and  inwards,  the 
outer  surface  forming  a  curve  of  larger  radius  than  the  inner.  In  sagittal  section 
the  lenticular  nucleus  is  also  somewhat  lens-shaped  in  outline  (fig.  417).  In 
coronal  sections  through  the  anterior  part  it  appears  crescentic,  with  the  convexity 
turned  downwards  ancl  outwards  (fig.  415);  but  in  successive  sections  taken  from 
before  backwards  the  crescentic  gives  place  to  a  triangular  or  wedge-shaped  outline 
(fig.  421).  In  fresh  brains  this  grey  mass  can  be  seen  to  he  traversed  by  thin 
white  intersections,  the  internal  and  external  medullary  laminae,  which  divide  it 
into  three  zones.  The  middle  and  inner  zones  are  of  a  yellowish  grey  colour,  and 
constitute  the  globus  pallidus.  The  outer  zone  is  of  a  darker  reddish  grey,  and  is 
traversed  with  fine  white  .'Jtriie.      It  is  called  the  putamen. 

The  putamen  is  the  longest  part  of  the  lenticular  nucleus,  and  is  the  only  portion  of  that 
body  which  is  continuous  with  the  caudate  nucleus. 

The  above  agrees  substantially  with  the  account  which  is  given  by  Schwalbe  ;  this  anato- 
mist, however,  describes  the  amygdaloid  nucleus  as  discontinuous  with  the  tail  of  the  caudate 
nucleus.  According  to  Foster  and  Sherrington,  the  globus  pallidus  of  the  lenticular  nucleus  as 
well  as  the  putamen  is  continuous  with  the  caudate  imcleus. 

A  band  of  white  fibres,  the  ansa  lenticularis,  passes  inwards  below  the  inner  capsule.  It 
emerges  from  the  under  surface  of  the  lenticular  nucleus,  being  continued  from  the  medullary 


roo 


THE  XERVOUS  SYSTEM 


laminae.  It  also  receives  fibres  fruui  the  inner  segment  of  the  globus  pallidus.  The  ansa  lentie- 
iilaris  enters  the  subthalamic  region  and  passes  beneath  the  red  nucleus,  where  it  becomes 
indistinct. 

The  claustrum  is  a  thin  hand  of  grey  matter  Avliich  is  placed,  nearly  vertically, 
external  to  the  lenticular  nucleus,  and  separated  from  the  latter,  excei)t  at  its  lower 
part,  by  the  outer  capsule.  It  is  separated  from  the  grey  matter  of  the  island  of 
Reil  by  a  laver  of  white  matter,  into  which  it  sends  small  pointed  })rocesses  cor- 
responding to  the  gyri  operti  of  the  island.  It  is  fused  at  its  anterior  end  with  the 
amygdaloid  nucleus.     (Hill.) 


Fig.  419. — Horizontal  Section  of  the  Cerebrum. 

(After  Lanilois  and  Stirling.) 

G  YE  US  FORNICA  TVS 
CORPUS  CALLOSUM 


ASTERIOR  CORXU 


CA  UDA  TE 

NUCLEUS 

IXXER  CAPSULE 

{AXTERIOR  LIMB) 

OUTER  CAPSULE  — 

LENTICULAR 

NUCLEUS 

CLAUSTRUM- 

IXXER  CAPSULE 

(POSTERIOR  LIMB) 


OPTIC  THALAMUS 


CORPUS 
GEXICULA  TUM 
IXTERXUM 
CA  UDA  TE 
XUCLEUS     I 
HIPPOCA  MRUS  — ^ 

MAJOR 

HIPPOCAMPUS 

MIXOR 


CLA  VA 
FUXICUL  US  CUXEA  TUS  ' 
FUNICULUS  GRACILIS 


SEPTUM 
LUCID  UM 

'ORPUS 

STRIA  TUM 

—  ANTERIOR 
PILLAR  OF 
FORXIX 

—  T.EXIA  SEMI- 
CIRCULARIS 

OPTIC 

THALAMUS 


CORPORA 
QUADRI- 
GEMIXA 


SUPERIOR 

PEDUXCLE  OF 

CEREBELL UM 
IXFERIOR 

PEDUXCLE 
MIDDLE 

PEDUXCLE 

ALA  CIXEREA 


OBEX 


The  amygdaloid  nucleus  is  a  thickening  of  the  grey  cortex  of  the  apex  of  the 
temporal  lobe,  and  produces  a  bulging  (amygdaloid  tubercle)  into  the  roof  of  the 
extremity 'of  the  descending  cornu  of  the  lateral  ventricle. 

The  taenia  semicircularis,  or  stria  terminalis,  is  a  band  of  fibres  which  passes 
upwards  and  backwards  from  the  anterior  ])illar  of  the  fornix,  traversing  the 
groove  between  the  caudate  nucleus  and  the  optic  thalamus.  It  accompanies  the 
caudate  nucleus  into  the  roof  of  the  descending  cornu,  and  ends  in  the  amygdaloid 
nucleus.  In  its  course  along  the  groove  above  mentioned  it  is  partly  covered  l>v 
the  vein  of  the  cor})us  striatum  and  l>y  a  thickened  band  of  ependyma,  the  lamina 
cornea,  which  also  covers  the  vein. 


BASAL  GA^XiLIA— FORNIX  VOl 

The  inner  capsule  is  a  broad  Ijand  of  Avhite  fibres  which  is  placed  on  the  inner 
side  of  the  nucleus  Icntieularis.  In  horizontal  section  it  presents  an  anterior  limb 
})etween  the  two  nuclei  of  the  corpus  striatum,  and  a  posterior  limb  which  separates 
the  nucleus  lenticularis  from  the  optic  thalamus.  These  two  limbs  meet  at  an 
angle  salient  inwards.  This  angle  is  called  the  genu,  and  is  placed  adjacent  to  the 
ttenia  semicircularis. 

In  vertical  section  the  inner  capsule  presents  a  beautiful  arched  arrangement  of  radiating 
white  fibres  (fig.  417). 

The  outer  capsule,  much  narrower  than  the  inner,  is  a  band  of  white  fibres 
which  intervenes  between  the  claustrum  and  the  nucleus  lenticularis. 

Ill  a  horizontal  section  through  the  basal  ganglia  of  the  hemisphere  and  adjacent  part  of  the 
thalaniencephalon,  an  alternation  of  grey  and  white  layers  is  seen  in  the  following  order  from 
without  inwards  : — (1)  the  grey  matter  of  the  island  of  Reil ;  (2)  the  white  matter  of  the  same 
lobe;  (o)  the  claustrum;  (4)  the  outer  capsule  ;  (5)  the  nucleus  lenticularis;  (6)  the  inner  cap- 
sule ;  (7)  the  nucleus  caudatus  and  oi»tic  thalamus,  sej^arated  from  one  another  by  the  taenia 
semicircularis  (fig.  419). 

The  anterior  commissure  bounds  the  third  ventricle  in  front,  but  belongs  to 
the  cerebral  hemisplieres,  as  it  is  developed  in  connection  with  the  lamina  termi- 
nalis.  It  presents  a  cylindrical  free  surface  towards  the  third  ventricle,  where  it 
appears  like  a  small  trai:isverse  bar  in  the  interval  between  the  anterior  pillars  of 
the  fornix.  It  passes  outwards  in  front  of  the  fornix,  and  traverses  the  cerebral 
sul)stance  below  the  lenticular  nucleus  on  each  side  (fig.  421),  the  fibres  inclining 
backwards  and  assuming  a  twisted  arrangement  as  it  proceeds.  It  ends  in  the 
t»Mup(iral  lobe. 

Dissection. — The  student  should  cut  through  the  remaining  part  of  the  corpus  callosum 
about  the  middle,  raise  the  ])osterior  portion,  carefully  detaching  it  from  the  subjacent  fornix,  and 
tlirow  it  backwards.  This  dissection  will  reveal  the  body  and  the  diverging  posterior  pillars  of 
the  fornix.  He  should  then  rai.se  the  anterior  portion  of  the  corpus  callosum,  and  snip  through 
the  septum  lucidum  with  a  sharp  pair  of  scissors.  The  slit-like  fifth  ventricle  will  now  be  visible, 
or  may  be  brought  into  view  by  gently  separating  the  laminae  of  the  septum  lucidum  with  tlie 
point  of  the  scalpel.  The  fornix  should  next  be  examined  and  then  divided  by  cutting  through 
its  body  and  throwing  the  parts  b;ickwards  and  forwards.  By  this  dissection  the  so-called  trans- 
verse fissure  will  be  opened  up  and  the  velum  interpositum  exposed. 

The  FORNIX  is  a  longitudinally-arched  bundle  of  fibres  composed  of  two  sym- 
metrical halves  which  are  united  together  at  the  central  part,  forming  the  body,  but 
diverge  in  front  and  behind,  constituting  the  anterior  and  posterior  jiillars.  The 
body  forms  a  curve  parallel  to  the  corpus  callosum,  to  the  under  surface  of  which 
it  is  adherent. 

It  is  narrowest  and  thickest  in  front,  widest  and  tliinnest  behind.  It  lies  on  the 
velum  interpositum,  which  separates  it  from  the  third  ventricle  and  from  the  optic 
thalami.  The  outer  portions  of  its  upper  surface  are  placed  in  the  body  of  the 
lateral  ventricles,  covered  by  the  epithelium  which  passes  at  the  thin  outer  margin 
of  the  fornix  into  the  epithelial  covering  of  the  choroid  plexuses.  The  posterior 
pillars  diverge  from  the  body,  passing  backwards  and  outwards.  In  the  interval 
between  them  the  splenium  of  tlie  corpus  callosum  can  be  seen  if  viewed  from  below. 
This  is  marked  by  faint  longitudinal,  transverse,  and  oblique  lines,  and  is  described 
as  the  lyre.  The  posterior  pillars  expand  as  they  pass  outwards  and  enter  the 
descending  cornua  of  the  lateral  ventricles.  A  conspicuous  bundle  of  fornix  fibres 
passes  along  the  concave  border  of  the  hippocampus  major  as  the  fimbria,  Avhich 
can  be  traced  to  the  uncus.  Other  fibres  are  scattered  over  the  hipp()camj)us  major 
and  the  eminentia  collateralis.  The  anterior  pillars  sweep  downwards  with  a 
sharper  curve  than  the  corpus  callosum,  and  so  diverge  from  it,  leaving  an  interval 
which  is  occupied  by  the  septum  lucidum.  They  descend,  in  the  form  of  two 
rounded  slightly-diverging  bundles,  immediately  l)ehind  the  anterior  commissure. 
Here  they  are  joined  by  the  taenia  semicirculares,  and  receive  fibres  from  the 
peduncles  of  the  pineal  body  and  from  the  sejHum  lucidum.  In  this  situation  they 
present  a  free  surface,  except  in  front,  where  they  give  attachment  to  the  sej^tum 


702  THE  M:R VOL'S  SYSTEM 

lucidum.     Having  reached  the  base  of  the  Ijrain,  they  end  in  the  gre}- nuclei  of  the 
corpora  albicantia. 

The  anterior  pillars  of  the  fornix  were  formerly  dL'scriljeil  as  twisting  on  themselves  to  form 
bends  or  loops  in  the  base  of  the  brain,  the  corpora  albicantia,  the  fibres  alter  forming  the  beiul 
being  eontinued  ui)war(ls  on  the  inner  sides  of  the  descending  anterior  jtillars  as  the  bundles  of 
Vicq  d'Azyr.  This  description  is  borne  uut  by  naked  eye  dissection,  but  it  has  been  shown  that 
the  bundles  of  Vieq  d'Azyr  are  discontinuous  with  the  fornix  fibres.     (Forel  and  Gudden.) 

The  septum  lucidum  is  formed  by  tliiu  portions  of  the  heniisplicre  walls,  which 
have  become  api)roximated  and  in  part  fused,  but  are  separated  in  the  greater  i)art 
of  their  extent  by  the  fifth  ventricle.  It  appears  as  two  closely  api)roximated  thin 
vertical  laminie,  separating  the  anterior  cornua  of  the  lateral  ventricles  of  opposite 
sides.  It  is  attached  above  and  in  front  to  the  under  surface  of  the  body  and  back 
of  the  genu  of  the  corpus  callosum,  below  to  the  rostrum  and  to  the  basal  white 
connnissure,  and  behind  to  the  anterior  pillars  of  the  fornix.  Viewed  from  the 
side,  it  is  triangular  in  outline,  with  an  acute  angle  directed  backwards  and  occupy- 
ing the  narrow  interval  between  the  front  of  the  body  of  the  fornix  and  the  corpus 
callosum  (fig.  412). 

Each  of  the  two  laminfe  which  constitute  the  septum  lucidum  contains  three  layers  :  a  layer 
of  ependyma  and  epithelium  next  the  lateral  ventricle,  a  middle  layer  of  white  fibres,  and  a  layer 
of  rudimentary  grey  matter  next  the  fifth  ventricle.  A  layer  of  connective  tissue  immediately 
bounding  the  fifth  ventricle  (rudimentary  pia-matral  layer)  is  described  by  Testut. 

The  fifth  or  Sylvian  ventricle  is  a  narrow,  sagittally-directed,  slit-like  cavity 
which  originally  formed  a  part  of  the  great  longitudin;d  fissure.  It  lies  between 
the  layers  of  the  septum  lucidum  and  it  does  not  communicate  Avith  any  of  the 
true  ventricles  of  the  brain. 

The  great  transverse  fissure  of  the  cerebrum  is  of  a  horse-shoe  shape,  and  extends  from  the 
foramen  of  Monro  on  each  side  to  the  termination  of  the  descending  cornu  of  the  lateral  ventricle. 
It  is  not  a  fissure  in  the  sense  of  forming  a  communication  between  the  ventricles  and  the  exterior 
of  the  brain,  but  it  may  be  considered  as  a  fissure  in  the  same  sense  that  we  use  the  term  'com- 
plete fissure.'  If  we  compare  it  with  the  adjacent  dentate  fissure,  we  find  that  the  latter  produces 
a  bulging  (the  hii)pocampus  major)  into  the  ventricular  cavitj'.  This  bulging  contains  an  inner 
layer  of  white  and  an  outer  layer  of  grey  matter,  and  is  sim]>ly  a  fold  of  the  ventiicular  wall, 
which  is  here  thiimor  than  elsewhere.  The  floor  of  the  dentate  fissure  is  occu])ied  by  pia  mater. 
Now  if  we  supi)ose  the  substance  of  the  hipiK)campus  thinned  away  until  only  the  eiiithelial  lining 
of  the  ventricle  was  left,  this  epithelium  would  come  in  contact  with  the  external  pia  mater,  and 
an  arrangement  resembling  the  choroid  plexus,  coming  through  a  fissure,  the  hijipocampal  fissure, 
would  be  produced.  The  choroid  plexus  is  therefore  an  internal  convolution  reduced  to  a  layer  of 
epithelium  forming  the  morphological  wall  of  the  ventricle,  and  produced  by  a  fissure,  the  great 
transverse  fissure,  which  is  occupied  by  a  specialised  and  highly  vascular  part  of  the  i)ia  mater. 
In  comparing  the  great  transverse  fissure  with  the  complete  fissures  of  the  cerebral  hemispheres, 
however,  we  must  not  lose  sight  of  the  fact  that  it  is  not  limited  to  the  hemis])here  wall  (exce))t 
at  its  extremities  in  the  temporal  lobes),  but  is  ])roduced,  for  the  greater  jiart  of  its  extent,  by  the 
folding  of  the  |»rosencephalon  over  the  thalamencephalon  (page  670).  According  to  Merkel  and 
Mierztyewsky,  small  slit-like  ajiertures  are  found  in  the  region  of  the  transverse  fissure  near  the 
termination  of  the  descending  horn  of  the  lateral  ventricle.  These  place  the  cavity  of  the  lateral 
ventricle  in  communication  with  the  subarachnoid  space. 

Tlie  velum  interpositum,  or  tela  choroidea  superior,  is  a  large  triangular 
fold  of  pia  n)ater  which  overlies  the  third  ventricle.  The  Ixxly  and  posterior  jiillars 
of  the  fornix  and  the  splenium  of  the  corpus  callosum  rest  on  its  upi)er  surface.  It 
is  continuous  laterally  with  tlie  choroid  plexuses  of  the  lateral  ventricles,  which  are 
simi)ly  the  convoluted  and  highly  vascular  margins  of  the  fold.  Traced  backwards, 
the  layers  are  seen  to  divaricate  and  to  become  continuous  with  the  pia  mater 
covering  the  tentorial  surface  of  the  occipital  lobes  and  the  upjier  surface  of  the 
cerebellum.  Two  large  veins,  the  veins  of  Galen,  commence  at  the  anterior 
extremity  of  the  velum  interpositum.  The  veins  of  Galen  are  chiefly  formed  by 
the  veins  of  the  corpora  striata,  and  are  continued  backwards  in  the  middle  line 
to  end  in  the  straight  sinus.  In  this  course  they  lie  in  a  prolongation  of  the 
subarachnoid  space  between  the  two  layers  of  jiia  mater  which  form  the  velum 
interpositum,  and  usually  unite  into  one  vein  before  entering  the  straight  sinus. 


CHOROID   PLEXUSES 


f03 


The  under  surface  of  the  velum  interpositum  rests  on  the  inner  parts  of  the  optic 
thalanii,  and  between  the  hitter  it  is  phiced  directly  over  the  third  ventricle,  where 
it  is  covered  by  a  layer  of  ei)ith('lium  continuous  with  the  lining  of  that  cavity,  V)ut 
discontinuous  Avith  the  epitheliuiu  of  the  lateral  ventricles,  except  at  the  foramina 
of  Monro. 

The  choroid  plexuses  extend  from  the  extremity  of  the  descending  cornu  of 
each  side  to  the  foramen  of  Monro  where  they  become  continuous  with  one  another 
through  the  foramen  commune  anterius.  From  the  junction  of  the  two  plexuses 
a  pair  of  small  vascular  fringes  pass  backwards  on  the  under  surface  of  the  velum 
interpositum  in  the  middle  line,  and  depend  into  the  cavity  of  the  third  ventricle, 


Fig.  420. — Horizoxtal  Section  of  the  Ceeebeal  Hemispheres. 

(From  a  mounted  specimen  in  the  Anatomical  Department  of  Trinity  College,  Dublin.) 

(The  fornix  has  been  reflected  to  show  the  velum  interpositum.) 


.( XTERIOR 
PILLARS 
OF  FUR  MX 


POSTERIOR 

PILLARS 

OF  FORNIX     § 


Straight  sinus 


CFRF- 
RELLVM 


CORPUS 
CALLOSUM 
(in  section) 
SEPTUM 
LUCID  UM 

FIFTH 
VENTRICLE 


TJENIA  SEMI- 
CIRCULARIS 
OPTIC 
THALAMUS 

Velum 
interpositum 

Choroid  p/exus 

FIMBRIA 

HIPPOCAM- 
PUS MAJOR 

EMIXEXTIA 
COLL  A  TER- 
ALIS 

-  HIPPO- 
CAMPUS 
MIXOR 


constituting  the  choroid  plexuses  of  that  cavity  (fig.  414).  The  anterior  choroid 
artery  enters  the  choroid  plexus  at  the  termination  of  the  descending  cornu;  other 
smaller  arteries  are  supplied  to  the  plexus  from  behind,  and  are  derived  from  the 
posterior  cerebral  artery. 

Dissection. — The  student  should  divide  the  splenium  of  the  corpus  callosum  in  tlie  middle 
Hue,  and  remove  the  ]iortions  of  tlie  hemispheres  which  lie  ))osterior  to  tlie  great  transverse 
fissure  ;  they  will  readily  separate  at  the  fissure,  and  break  off  at  the  extremities  ol'  tlie  temi)oral 
lobe.s.  This  operation  should  be  conducted  with  gentleness,  as  the  walls  of  the  third  ventiicle 
are  very  prone  to  become  unduly  divaricated  by  this  di.ssection.  The  \y,\rt  removed  should  be 
re-examined,  as  the  relations  between  the  fissures  and  hip|)ocampi  can  be  studied  to  great 
advantage  at  this  stage.     The  cavity  of  the  third  ventricle  may  now  be  displayed  by  raising  the 


704 


THE  XFAIVOUS  SYSTEM 


velum  iutt'iposituui,  and  reflecting  it  backwards.  This  must  be  done  cautiously,  as  the  pineal 
body  is  closely  eiit'ulded  in  the  posterior  part  of  the  under  layer  ol'  that  membrane,  and  an 
attempt  should  be  made  to  retain  it  in  its  proper  place.  The  dissector  should  thoroughly 
examine  the  cavity  and  floor  of  the  third  ventricle  and  the  free  surfaces  of  the  optic  thalami, 
but  he  is  recommended  to  dissect  the  deep  surfaces  of  the  latter  bodies  in  connection  with  the 
luesencejthalon. 

The  Thalamencephalon 

The  THIRD  VENTRICLE  is  a  naiTow  cavity  whose  lateral  walls  are  so  closely 
a})proxirnated  that  in  I'orunal  sections  it  appears  as  a  vertical  slit.  It  communi- 
cates in  front  with  the  lateral  ventricles  by  the  foramina  of  Monro.  Behind,  it  is 
continuous  with  the  fourth  ventricle  through  a  narrow  passage,  the  aqueduct  of 
Sylvius.  The  opening  into  the  aqueduct  is  bounded  above  by  a  transverse  white 
bundle  of  fibres,  the  posterior  commissure  ;  and,  above  this,  a  prolongation  of  the 

Fig.  421. — Coronal  Section  through  the  Anterior  Part  of  the  Third  Ventricle. 
(From  a  mounted  specimen  in  the  Anatomical  Department  of  Trinity  College,  Dublin.) 


COB  PL'S  CALLOSUM 


SEPTUM  LUCID  CM 


ASTERIOR 
PILLAR-^  (IF'y 
FOR  MY 


T.e.VIA 
<EMICIR- 
rfLARIS 
IPERCULrM 
<  I.XUSTRVit 
PUT  AMES 


i;i.OBus 

PALLIDVS 
iS'TERIOR 
COMMIS- 
SURE 
iMYGDA- 
LOW 
SUVLECS 


PITUITARY  BODY 


ventricular  cavity  extends  into  the  stalk  of  the  pineal  body,  in  which  it  ends 
blindly.  The  third  ventricle  is  covered  by  the  corpus  callosuni,  the  fornix,  and  the 
velum  interpositum;  its  true  roof,  however,  is  formed  by  the  epithelium  lining  the 
under  surface  of  the  last-named  structure.  The  central  joart  of  its  cavity  is  crossed 
transversely  by  the  middle  or  grey  commissure.  It  is  bounded,  laterally  by  the 
optic  thalami,  and  in  front  l)y  the  anterior  pillars  of  the  fornix  and  by  the  anterior 
commissure.  It  is  limited  behind  by  the  commencement  of  the  aqueduct  of 
Sylvius,  by  the  posterior  commissure,  and  by  the  reflexion  of  epithelium  from  the 
U]iper  surface  of  the  pineal  body  on  to  the  under  surface  of  the  velum  interpositum. 
In  the  anterior  part  of  the  ventricle  the  floor  is  marked  off  from  the  lateral  walls 
by  the  anterior  jjillars  of  the  fornix,  which,  after  forming  part  of  the  anterior 
l)Oundary,  sweep  l)ackwards  with  an  inclination  downwards:  m  this  situation  they 
are  covered  by  a  thin  layer  of  the  central  grey  sulistance  of  the  ventricle,  and 
]»roject  as  slight  ridges.  The  third  ventricle  is  relatively  shallow  for  about  the 
posterior  third  of  its  extent,  but  in  its  anterior  two-thirds  it  presents  a  deep  recess 
which  is  divided  into  an  anterior  and  a  posterior  part  by  a  prominent  ridge.     This 


OPTIC  THALAMI  705 

ridge  is  formed  by  the  junction  of  the  tuber  cinereum  and  the  lamina  cinerea 
above  the  optic  commissure.  The  floor  is  formed  by  the  following  structures: — 
l)ehind,  by  the  tegmental  portion  of  the  diverging  crura  cerebri,  and  between  them 
by  the  posterior  perforated  space;  in  front  of  this  by  the  corpora  albicantia,  the 
tuber  cinereum  with  the  infundilnilum  and  the  lamina  cinerea.  The  latter  slopes 
upwards  to  the  anterior  commissure,  and  is  relegated  by  some  anatomists  to  the 
anterior  wall  instead  of  to  the  floor. 

The  central  grey  matter  of  the  third  ventricle  is  continuous  behind  with  the  grey  matter  of 
the  aciueduct  of  Sylvius,  and  [Jiisses  in  front  into  the  basal  grey  commissure.  _  It  also  covers  the 
lower  parts  of  the  internal  surfaces  of  the  o]>tic  thalami,  and  gives  a  thin  covering  to  the  anterior 
pillars  of  the  fornix  and  to  the  bundles  of  Vicq  d'Azyr. 

The  optic  thalami  are  a  pair  of  large  ganglia  placed  one  on  each  side  of  the 
third  ventricle.  Each  optic  thalamus  is  a  short  prismatic  body  whose  long  axis  is 
directed  forwards  and  inwards.  This  axis  is  not  straight,  but  is  slightly  curved 
with  its  convexity  upwards.  The  thalamus  presents  an  anterior  and  a  posterior 
extremity  or  tubercle,  and  four  surfaces:  a  superior  and  an  internal  which  are  free, 
and  an  inferior  and  an  external  which  are  imbedded  in  the  cerebral  substance. 
The  anterior  tubercle  is  a  blunt  rounded  point  Avhich  forms  the  posterior  bound- 
ary of  the  foramen  of  Monro.  The  posterior  tubercle,  or  pulvinar,  is  broader 
than  the  anterior,  and  is  compressed  from  above  downwards.  It  is  directed  back- 
wards and  downwards;  it  is  continued  externally  into  the  outer  geniculate  body, 
and  overhangs  the  inner  geniculate  body.  It  is  placed  above  and  in  front  of  the 
descending  cornu  of  the  lateral  ventricle,  but  is  separated  from  the  cavity  of  the 
latter  by  the  choroid  plexus.  The  superior  surface  shows  a  slight  convexity, 
more  pronounced  in  the  antero-posterior  than  in  the  transverse  direction.  It  is 
covered  with  a  layer  of  white  fibres.  It  presents  a  groove,  the  sulcus  choroideus, 
which  underlies  the  free  edge  of  the  fornix,  separated  from  the  latter  only  by  the 
velum  interpositum.  This  groove  marks  off  an  antero-external  area,  wider  in  front 
than  behind,  which  ends  in  the  anterior  tubercle  and  which  forms  part  of  the  floor 
of  the  lateral  ventricle.  Internal  to  the  sulcus  choroideus  is  a  larger  area,  w^hich  is 
covered  by  the  fornix  and  velum  interpositum.  This  area  is  limited  internally  for 
about  its  anterior  half  by  the  stria  pinealis,  or  peduncle  of  the  pineal  body,  a 
white  bundle  of  fibres  which  runs  along  the  sharp  edge  which  separates  the  superior 
from  the  median  surface.  The  posterior  part  of  this  area  slopes  gradually  into  the 
l)ulvinar.  Between  the  superior  surface  and  the  posterior  part  of  the'stria  pinealis 
is  a  small  triangular  area,  the  trigonum  habenulse,  which  is  sunk  below  the  level 
of  the  adjacent  part  of  the  thalamus.  The  internal  surface  is  nearly  flat  and 
bounds  the  cavity  of  the  third  ventricle,  towards  which  it  presents  a  slight  con- 
vexity. It  is  of  a  pale-grey  colour  owing  to  a  thick  layer  of  ependyma  covering 
the  ganglionic  substance,  and  is  united  to  its  fellow  of  the  opposite  side  by  a  broad 
band  of  grey  matter,  the  middle  or  grey  commissure  (commissura  mollis). 
It  is  crossed  at  its  lower  margin  by  a  groove,  the  sulcus  of  Monro,  which  passes 
from  the  foramen  of  Monro  to  the  commencement  of  the  aqueduct  of  Sylvius.  The 
external  surface  rests  against  the  fibres  of  the  inner  capsule  behind  the  genu, 
being  separated  from  the  nucleus  lenticularis  by  the  inner  capsule.  The  inferior 
surface  is  placed  over  the  crus  cerebri,  on  the  tegmental  part  of  Avhich  it  rests. 

In  coronal  sections  through  the  posterior  part  of  the  thalamus,  the  external  surface  is  seen  to 
be  separated  from  the  inferior  surface  by  a  distinct  angle  ;  but  in  similar  sections  through  the 
anterior  part  the  two  surfaces  pass  into  one  another,  the  angle  being  rounded  oif.  The  grey  sub- 
stance of  the  thalamus  is  indistinctly  marked  off  into  three  nuclei :  an  antero-superior,  an  external, 
and  an  internal.  The  largest  part  of  the  antero-superior  nucleus  forms  the  anterior  tubercle  ;  the 
thinner  portion  passes  backwards  above  and  between  the  other  two  nuclei ;  its  shape  has  been  not 
inaptly  compared  to  that  of  the  caudate  nucleus.  A  remarkable  bundle  of  white  fibres,  the  ansa 
lenticularis,  passes  below  the  optic  thalamus  and  inner  capsule  from  the  lenticular  nucleus  of  the 
corpus  striatum. 

The  pineal  body  (epiphysis  cerebri  or  conarium)  is  a  reddish-grey  body  about 

the  size  of  a  cherry-stone.      It  has  the  form  of  a  flattened  cone,  compressed  from 

above  downwards.     Its  long  axis  is  directed  forwards  and  slightly  upwards.     Its 

base  is  directed  forwards  and  passes  into  a  bilaminar  stalk.     Its  superior  surface  is 

45 


TOG 


THE  XER VOL'S  SYSTEM 


covered  l)y  epithelium  for  the  anterior  two-thirds  or  tliree-fourths  of  its  extent,  and 
hounds  in'  part  the  cavity  of  the  third  ventricle.  Its  inferior  surface  rests  in  the 
mesial  groove  between  the  su})eri(tr  (juadrigeminal  l)odies,  separated  from  the  latter 
by  a  fold  of  ])ia  mater.  The  stalk  of  the  pineal  body  is  continuous  Ijy  its  lower 
lamina  with  the  ])()sterior  commissure.  Its  upper  lamina  passes  into  the  peduncle 
or  stria  pinealis,  which  passes  at  first  outwards,  and  then  forwards,  along  the 
margin  of  the  optic  thalamus  which  separates  the  upper  and  mesial  surfaces  of  that 
bodv;  it  then  crosses  the  flocn-  of  th(.'  foramen  of  Monro  and  joins  the  anterior 
pillars  of  the  fornix. 

The  recessus  pinealis  is  a  diverticulum  from  the  cavity  of  the  third  ventricle,  ■whicli  extends 
into  the  stalk  and  a  short  distance  into  the  body  of  the  conarium.  "Within  the  pineal  body,  and 
in  the  adjacent  part  of  the  velum  interpositum,  a  number  of  gritty  particles  (acervulus  cerebri, 
i)rain  sand)  are  found.  These  particles  consist  chiefly  of  phosphate  and  carbonate  of  calcium. 
The  pineal  body  was  formerly  described  as  a  gland  (pineal  gland)  but  is  now  known  to  be  a 
rudimentary  unpaired  eye.     This  pineal  eye  lies  close  to  the  surface  in  some  of  the  lower  verte- 


FiG.  4-22. — CoKox.4L  Sectiox  theough  the  Middle  Commissure  of  the  Third 
Ventricle.     (Schwalbe.) 


CORPUS 
CALLOSL'Jf 


THIRD 

VENTRICLE 

INNER 

CAPSULE 


OPTIC  TRACT 


LA TERA L 
VENTRICLE 

TAENIA  SEMI- 
CIRCriARIS 

LENTKTLAR 
NUCLEUS 

OUTER  CAPSULE 
.MIDDLE 

COMMISSURE 
ISLAND  OF  REIL 
(LAUSTRUM 


AMYGDALOID 
NUCLEUS 


brates,  and  was  proljably  functional  at  a  former  period.     A  great  i)arietal  foramen  in  the  extinct 
reptile  Ichthyosaurus  is  strongly  suggestive  of  a  functional  pineal  eye. 

The  posterior  commissure  is  a  transverse  hand  of  fibres  which  projects  into 
the  posterior  part  of  the  cavity  of  the  third  ventricle  (page  708). 

The  subthalamic  tegmental  regitjn  and  the  corpora  geniculata  will  be  more  conveniently 
described  with  the  mesejicei)halon. 

The  basal  grey  commissure  is  a  continuous  plate  of  grey  matter  wliich  is 
formed  from  behind  forwards  by  the  posterior  perforated  space,  the  tuber  cinereum, 
and  the  lamina  cinerca. 

The  posterior  perforated  space  is  a  stratum  of  grey  matter  which  is  perforated 
by  a  numl)er  of  small  vessels  thrived  from  the  commencements  of  the  posterior 
cerebral  and  superior  cerebellar  arteries.  It  occujiies  the  back  part  of  the  inter- 
pediuicular  space  and  extends  for  a  short  distance  under  cover  of  the  pons,  where  it 
bounds  a  recess,  the  foramen  caecum  anterius.     It  is  cc^ntinuous  laterally  with  the 


BASAL   GREY  COMMISSURE 


707 


grey  matter  of  tlie  tegmenta  of  the  crura  cerebri,  and  is  attaclied  in  front  to  the 
corpora  allncantia.  The  portion  of  the  space  which  is  situated  in  front  of  the  exit 
of  the  third  nerve  forms  part  of  the  floor  of  the  third  ventricle;  the  posterior  part 
belongs  to  the  mesencephalon. 

The  corpora  albicantia  appear  as  a  pair  of  white  knobs  in  the  base  of  the 
brain.  Each  contains  in  its  interior  a  grey  nucleus.  This  nucleus  is  joined  b}'  the 
anterior  ]nllar  of  the  fornix  and  the  l)undle  of  Vicq  d' Azyr  of  the  same  side.  The 
bundle  of  Vicq  d'Azyr  passes  upwards  and  forwards  through  the  grey  matter  of 
the  optic  thalamus  to  the  anterior  tubercle  of  that  body. 

The  tuber  cinereum  is  a  gre}^  elevation  placed  inmiediately  behind  the  optic 
commissure.  It  is  the  largest  part  of  the  basal  grey  commissure,  and  is  continuous 
laterally,  above  the  optic  tracts,  with  the  grey  cortex  of  the  temporal  lobes  (fig.  421). 
In  front  it  passes  over  the  optic  commissure  into  the  lamina  cinerea.  It  is  con- 
tinued below  into  a  conical  process,  the  infundibulum,  which  is  directed  down- 
wards and  slightly  forwards,  through  the  central  opening  in  the  diaphragma 
selloe  to  end  in  the  posterior  lobe  of  the  pituitary  body.  The  upper  part  of  the 
infundibulum  is  hollowed  out  by  a  diverticulum  of  the  third  ventricle,  the  recessus 


Fig.  423. 


-Coronal  Sectiox  through  the  Third  Ventricle  behind  the  Middle 
OoiMiS'^rKK.      (Gegeabaur. 


CORPUS  CALLOSUM 

FORNIX 

OPTIC  THALAMUS 

MIDDLE  COMMISSURE 


suBSTAxrn  xigra 

CRUST  A 


An> .J** 


^ ' 

»          k 

^^ 

^ 

"*r 

1 

.  ) 

/>- 

'v— 

^ 
/ 

CA  UDA  TE  NUCLEUS 
LATERAL 
VENTRICLE 

CLAUSTRUM 

LENTICULAR 

NUCLEUS 
RED  NUCLEUS 


■/ FIMBRIA 


infundibuli.     The  tuber  cinereum  and  infundibulum   correspond  to  the  median 
recess  in  the  floor  of  the  third  venlrirlc. 

The  pituitary  body,  or  hypophysis  cerebri,  is  a  small  ellipsoidal  body  which 
is  lodged  in  the  pituitary  fossa  of  the  sphenoid  bone.  Its  long  axis  is  directed 
transversely,  and  its  antero-posterior  and  vertical  diameters  are  about  equal. 

Tlie  pituitar}'  body  consists  of  two  distinct  lobes,  an  anterior  and  a  posterior.  The  anterior 
lobe  is  of  a  reddish-gre.v  colour,  and  is  considerably  larger  than  the  i)Osteiior  lobe,  which  it  ]iai- 
tially  embraces.  The  posterior  lobe,  of  a  yellowish-grey  colour,  is  lodged  in  a  recess  in  the  anterior 
lobe,  and  is  the  only  part  connected  with  the  infuiKlibulum. 

This  body  was  formerly  described  as  the  pituitary  gland,  because  it  was  suppo.sed  to  secrete 
the  pituita,  or  mucus  of  the  nose.  According  to  Gaskell's  ingenious  theory,  the  infundibulum  is 
the  mouth  of  an  archaic  alimentary  canal.  The  ventricular  system  of  the  brain  is  the  mdiment 
of  the  c^eiihalic  stomach  as  found  in  Arthrojjods.  The  central  Ciinal  of  the  spinal  cord  is  the 
archaic  intestine,  and  the  neuro-enteric  canal  (an  cmbrj^onic  communication  between  the  neural 
tube  and  the  intestine)  connects  this  archaic  intestine  with  the  ano-rectal  )-egion.  This  pituitary 
body  is  of  great  interest  in  the  light  of  this  theory,  as  it  livings  the  archaic  mouth  to  the  surface. 
The  jiosterior  lobe  is  developed  in  coiniection  with  the  brain,  but  the  anterior  lobe  is  formed  inde- 
pendently. It  originates  as  an  upward  growth  of  the  epiblastic  invagination  which  forms  the 
mouth,  and  is  atterwards  cut  off  by  the  chondrification  and  subsequent  ossification  of  the  skull. 


708  THE  XER VOL'S  SYSTEM 

The  optic  commissure  is  formed  by  the  union  and  partial  decussation  of  the 
optic  tracts  of  opposite  sides.  Each  optic  tract  may  be  traced  backwards  from  the 
connnissure,  around  the  crus  cerebri,  to  the  region  of  the  corpora  geniculata 
(page  710). 

The  lamina  cinerea  is  a  thin  plate  of  gre}'  matter  which  may  be  seen  from 
the  base  of  the  brain  by  pulling  the  optic  conmiissure  slightly  l)ackwards.  It  is 
continuous  in  front  with  the  grey  matter  of  the  olfactory  convolutions  of  the 
frontal  lobes,  and  between  the  latter  it  is  connected  to  the  rostrum  of  the  corpus 
callosum  by  the  basal  white  commissure.  Laterally,  it  is  continuous  with  the 
anterior  perforated  space.  It  forms  the  anterior  sloping  part  of  the  floor  of  the 
third  ventricle. 

Nerve-tracts  in  the  substance  of  the  thalamencephalon  and  prosen- 
cephalon.— The  systems  of  fibres  which  are  connected  with  the  optic  thalanms 
may  be  tirst  considered;  the  principal  of  these  are:  (a)  The  posterior  commis- 
sure; (b)  the  corona  radiata  of  the  ojitic  thalamus;  and  (c)  the  bundle  of  Vicq 
d'Azyr. 

(a)  The  posterior  commissure  contains  a  tract  of  fibres  which  passes  from  the 
optic  thalamus  to  the  tegmental  region  of  the  mesencephalon  on  the  opposite  side; 
but  beyond  this,  nothing  is  known  with  any  degree  of  certainty.  It  is  said  to 
transmit  fibres  from  the  fillet  and  from  the  posterior  longitudinal  bundle  to  the  oppo- 
site side.  Fibres  are  also  said  to  proceed  via  this  commissure  from  the  ganglion 
habenulae  and  the  pineal  body  to  the  oculo-motor  nucleus  of  the  opposite  side.  It 
is  therefore  a  bundle  of  decussating  fibres  derived  from  various  sources,  and  prob- 
ably does  not  contain  any  true  commissural  fil)res. 

(6)  The  corona  radiata  of  the  optic  thalamus  is  formed  of  a  system  of  fibres 
which  converge  to  the  thalamus  from  tlie  cortex  of  the  frontal,  parietal,  occipital, 
and  temporal  lobes,  and  it  also  receives  a  small  Ijundle  from  the  cortical  part  of  the 
olfactory  tract.  Portions  of  this  system,  namely,  the  fibres  from  the  occipital  lobe 
(posterior  peduncle  of  the  thalamus),  and  from  the  tem])oral  lobe  (inferior  peduncle), 
require  special  notice.  The  posterior  peduncle  of  the  thalamus  (optic  radiation) 
passes  backwards  in  the  white  matter  of  the  hemisphere  in  company  with  a  great 
bundle  of  sensory  fibres  to  the  occipital  lol  le.  It  is  further  described  in  connection 
Avith  the  optic  nerve  (page  746).  The  inferior  peduncle  may,  for  the  sake  of 
simplicity,  be  described  with  the  ansa  peduncularis,  as  it  forms  an  important 
constituent  of  that  body. 

The  ansa  peduncularis  may  be  exposed  from  the  base  of  the  brain  by  dissecting 
the  optic  tract  from  the  surface  of  the  crus  cerebri.  It  is  a  band  of  fibres  which 
winds  round  the  ventral  surface  of  the  crusta  just  at  the  transition  of  the  latter 
into  the  inner  capsule.  Its  principal  constituents  are  the  ansa  lenticularis  and 
the  inferior  peduncle  of  the  thalamus.  The  ansa  lenticularis  proceeds  from  the 
medullary  laminae  of  the  lenticular  nucleus  and  passes  transversely  inwards 
immediately  below  the  globus  pallidus.  It  then  enters  the  subthalamic  region,  and 
without  doubt  passes  into  the  mesencephalon,  but  its  exact  course  cannot  be  followed 
witli  certainty.  The  inferior  peduncle  of  the  thalamus  is  })artly  formed  by  a 
sagittally-directed  bundle  which  passes  l)ackwards  through  the  sul)stance  of  the 
thalamus  l)etween  the  anterior  pillar  of  the  fornix  and  the  bundle  of  Vicq  d'Azyr. 
This  bundle  is  joined  by  fibres  from  the  superior  surface  of  the  thalamus  (stratum 
zonale).  The  fibres  from  the  stratum  zonale  pass  from  the  superior  to  the  internal 
surface  of  the  thalanms,  and  finally,  reaching  the  inferior  surface  of  that  body, 
join  the  sagittal  l)undle  first  mentioned  to  form  the  inferior  peduncle;  the  latter 
now  passes  outwards  below  the  ansa  lenticularis  and  ends  in  the  cortex  of  the  tem- 
poral lobe. 

(c)  The  bundle  of  Vicq  d'Azyr  passes  from  the  anterior  tubercle  of  the  thala- 
mus to  the  nucleus  of  the  corpus  all)icans.  It  might  be  regarded  as  a  constituent 
of  the  corona  radiata — the  nucleus  of  the  corpus  allncans  being  considered  as 
modified  cortex. 

The  white  matter  of  the  cerebral  hemispheres  contains  the  following  systems  of 
fibres:  (a)  The  corona  radiata;  (b)  commissural  or  interhemispheric  fibres;  (c) 
association  or  intrahemispheric  fibres.  These  three  systems  of  fibres  are  disposed 
in  more  or  less  defined  tracts  which  can  be  unravelled  by  dissection,  but  in  certain 


CORONA   RAD  I  AT  A  709 

situations  where  the  different  tracts  cross  one  another  tlie  arrangement  l^ecomes 
more  compHcatecl.  This  is  notably  the  case  in  the  region  where  the  fibres  of  the 
corpus  callosuni  intersect  the  fibres  of  the  inner  capsule. 

The  corona  radiata  is  the  name  given  to  the  prolongation  of  the  fibres  of  the 
inner  capsule  into  the  hemisphere.  It  is  continued  upwards  from  the  inner  capsule 
as  a  somewhat  narrow  band  (peduncle  of  the  corona  radiata),  but  the  fibres  soon 
spread  out  like  a  fan  and  proceed  to  the  cerebral  cortex.  It  will  be  well  at  this 
stage  to  re-examine  the  constitution  of  the  inner  capsule;  the  latter  contains  three 
sets  of  fibres,  namely:  (a)  Fibres  which  pass  frcnn  the  crusta  of  the  crus  cerebri 
directly  into  the  corona  radiata  without  the  intervention  of  nerve-cells;  (h)  fibres 
])assing  from  the  mesencephalon  int(j  the  optic  thalamus  and  corpus  striatum ;  and 
(e)  fibres  from  the  thalamus  (jjart  of  the  corona  radiata  of  that  body);  and  from 
the  corpus  striatum  to  the  cerebral  cortex.  We  have  already  seen  (page  701)  that 
the  inner  capsule  shows  in  horizontal  section  an  anterior  limb,  a  posterior  limb  and 
a  genu.  The  fibres  which  occupy  the  most  anterior  part  of  the  anterior  limb  belong 
to  the  corona  radiata  of  the  optic  thalamus.  Behind  these  fibres  is  a  tract  which 
extends  nearly  to  the  genu;  this  tract  is  formed  by  fibres  which  are  derived  from 
the  frontal  lobe,  and  although  their  function  is  not  accurately  known  they  are  sup- 
posed to  be  associated  with  the  higher  intellectual  functions.  Traced  downwards, 
this  bundle  passes  into  the  crusta,  forming  rather  more  than  the  inner  fifth  of  that 
body,  and  from  thence  enters  the  pons,  where  a  part  of  it  seems  to  terminate 
(frontal  pontine  tract).  Its  further  course  is  unknown.  The  portion  of  the  inner 
cai)sule  immediately  in  front  of  the  genu  is  intimately  associated  "with  the  faculty 
of  speech;  it  passes  in  the  crusta  immediately  external  to  the  frontal  pontine  tracts. 
The  genu  conveys  fibres  from  the  cortex  cerebri  to  some  of  the  motor  cranial  nerves. 
These  fibres  pass  immediately  external  to  the  preceding  (aphasia)  bundle,  and 
probaiily  decussate  in  the  pons  to  become  connected  to  the  nuclei  of  the  facial  and 
hypoglossal  nerves,  and  to  the  motor  nucleus  of  the  trigeminal.  The  anterior  two- 
thirds  of  the  posterior  limb  of  the  inner  capsule  is  formed  by  the  pyramidal  tract 
Avhich  is  described  elsewhere  (page  741).  The  posterior  third  of  the  posterior  limb 
of  the  inner  capsule  is  formed  by  sensory  fibres  comprising  the  oi:»tic  radiation;  the 
latter  proceeds  exclusively  from  the  occipital  lobe.  The  remaining  sensory  fibres 
are  derived  from  the  occipital  and  temporal,  and  to  a  certain  extent  from  the 
parietal,  lobes.  They  descend  in  the  crusta,  occupying  the  outer  third  of  that  body. 
As  this  sensory  tract  traverses  the  crusta,  its  outermost  part  is  formed  liy  fibres 
derived  from  the  fillet. 

The  commissural  system,  consisting  of  the  corpus  callosum  and  the  anterior 
commissure,  lias  l)een  already  described  (]iages  692,  701). 

The  intrahemispheric  or  association  fibres  unite  different  portions  of  the 
cortex  of  the  same  hemisphere  to  one  another.  These  fibres  are  in  two  sets — along 
and  a  short.  The  short  fibres  (fibrse  arcuata?  seu  proprise)  unite  two  adjacent  con- 
volutions, the  fibres  passing  round  lieneath  the  fissure  which  separates  the  two 
convolutions.  The  long  fibres  are  disposed  in  several  more  or  less  well-defined 
tracts,  namely:  the  cingulum,  the  fasciculus  arcuatus,  the  fasciculus  uncinatus,  the 
perpendicular  occipital  fasciculus,  and  the  fasciculus  longitudinalis  .inferior.  The 
cingulum  is  a  well-defined  band,  which  occupies  the  core  of  the  gyrus  fornicatus. 
Near  the  splenium  of  the  corpus  callosum  it  receives  an  accession  of  fil ires  from  the 
occipital  lobe.  The  fasciculus  arcuatus  passes  from  the  cortex  of  the  frontal  to 
the  occipital  lobe;  it  also  sends  some  filires  into  the  temporal  lobe.  The  fasciculus 
uncinatus  springs  from  the  orbital  gyri  and  from  the  inferior  frontal  convolution, 
and,  after  traversing  the  lower  part  of  the  claustrum,  ends  in  the  cortex  of  the 
temporal  lobe  near  the  amygdaloid  nucleus.  The  perpendicular  occipital 
fasciculus  passes  from  the  inferior  parietal  ]ol)ule  to  the  inferior  occipito-temporal 
convolution.  The  fasciculus  longitudinalis  inferior  is  an  extremely  well-defined 
bundle  which  ]>asses  from  the  occipital  to  the  temporal  lobe. 

The  external  capsule  also  belongs  to  the  association  system,  as  it  is  chiefly 
concerned  with  the  convolutions  of  the  island  of  Reil. 

Dissection. — Tlie  stiirlent  should  remove  the  pia  mater  from  the  anterior  part  of  the  upper 
surface  of  tlie  cerebellum,  and  also  any  of  that  membrane  which  may  be  still  adherent  to  the 
quadrigeminal  bodies.     The  anterior  part  of  the  cerebellum  should  now  be  gently  i)ushed  back- 


710  THE  yKRVOUS  SYSTEM 

wards  until  the  quadrigemiiial  bodies  and  the  latiTal  parts  of  tlie  crura  cerebri  are  fully  exposed. 
The  valve  of  A^ieusseus  and  the  slender  pair  of  iourth  nervi-s  which  spiin^^  from  its  upper  jiart 
are  verj'  liable  to  injury  at  this  stage.  In  conducting  this  dissection,  the  >tuileut  will  notice  a  pair 
of  broad  white  bands,  the  superior  peduncles  oi'  the  cerebellum,  converging  towards  the  lower 
pair  of  quadrigeminal  bodies,  and  a  thin  white  lamina,  the  valve  of  A^ieussens,  filling  tlie  inter- 
space between  them.  The  mesencephalon  is  now  fully  exposed,  and  its  Iree  surface  should  fir.^t 
be  examined.     Directions  will  be  subsequently  given  lor  the  examination  of  its  internal  structure. 

The  Mesencephalon 

The  aqueduct  of  Sylvius  is  a  narrow  passage,  a  little  more  than  half  an  inch 
long,  Avhich  unites  the  cavities  of  the  third  and  fourth  ventricles:  hence  it  is 
sometimes  called  iter  e  tertio  ad  quartum  ventriculum.  It  is  roofed  by  a  plate 
of  grey  matter,  the  lamina  quadrigemina,  which  is  surmounted  by  tAVO  jDairs  of 
elevations,  the  corpora  quadrigemina.  Its  floor  is  formed  by  the  tegmenta  of 
the  crura  cerebri.  Its  out  line  in  transverse  section  varies  in  different  parts  of  its 
course.  Thus,  at  its  commencement,  under  the  posterior  commissure,  it  has  the 
form  of  an  isosceles  triangle  with  the  apex  directed  downwards.  Below  the  anterior 
quadrigeminal  bodies  it  is  heart-shaped,  then  somewhat  shield-shaped.  Lower 
down,  on  the  level  of  the  posterior  corpora  Cjuadrigemina,  it  has  the  form  of  an 
ovate  leaf  with  the  stalk  directed  downwards;  and  finally,  at  its  junction  with  tlie 
fourth  ventricle,  it  is  T-shaped  in  section  (fig.  444). 

The  grey  matter  of  the  aqueduct  is  a  thick  stratum  which  surrounds  that  canal,  and  is  con- 
tinuous with  the  grey  matter  of  the  floor  of  the  fourth  ventricle.  It  is  bounded  below  by  the 
formatio  reticularis,  and  by  the  posterior  longitudinal  bundle  (fig.  424).  It  is  continuous  above 
with  the  grey  matter  of  the  lamina  quadrigemina.  Groups  of  cells  are  embedded  in  this  grej' 
substance  ;  the  most  important  of  these  is  a  long  column  of  nerve-cells  which  is  placed  near  the 
middle  line  beneath  the  aqueduct  close  to  the  formatio  reticularis  (fig.  424).  This  is  the  con- 
tinuous nucleus  of  the  third  and  fourth  nerves.  It  commences  near  the  junction  of  the  tliird 
ventricle  and  the  aqueduct,  and  extends  for  nearly  the  whole  length  of  the  latter.  It  is  on  a  line 
witli  the  nuclei  of  two  nen'es  (sixth  and  twelfth)  which  arise  from  the  floor  of  the  fourth  ventricle. 
The  nucleus  of  the  descending  root  of  the  fifth  nerve  is  a  group  of  cells  in  the  region  of  the 
upper  quadrigeminal  bodies,  situated  above  and  external  to  the  nucleus  of  the  third  nerve  ;  it  is 
limited  on  its  outer  side  by  the  white  fibres  of  the  nerve-root  itself 

The  formatio  reticularis  will  be  described  with  the  anatomy  of  the  medulla  and  pons. 

The  CORPORA  QUADRIGEMINA  are  four  greyish  elevations  which  surmount 
the  lamina  (juadrigemina.  The  superior  or  anterior  pair  are  termed  the  nates  ;  the 
inferior  or  posterior  pair,  the  testes.  Tlie  corpora  quadrigemina  arc  marked  oft' 
by  a  cruciform  groove,  the  transverse  limb  of  which  is  the  more  distinct.  The 
portion  of  the  vertical  groove  which  lies  between  the  nates  is  also  well  marked,  l)Ut 
the  groove  between  the  testes  is  shallow  and  is  obscured  by  a  rounded  bundle  of 
fibres,  the  frenulum  veli,  Avhich  passes  downwards  and  spreads  out  on  the  valve 
of  Vieussens,  immediately  below  the  testes.  The  corpora  quadrigemina  consist  of 
grey  matter  overlaid  by  a  thin  superficial  stratum  of  white  fibres. 

The  nates  are  broader  and  darker  in  colour  than  the  testes,  and  form  a  pair  of 
ovoid  elevations  with  their  long  axes  directed  ujiwards  and  outwards;  this  direction 
is  continited  into  the  corresponding  brachia. 

The  brachia  of  the  nates,  or  superior  brachia,  are  sliglitly-raised  white  bands 
which  pass  on  each  side  from  the  nates  in  the  intervals  between  the  pulvinar  of  the 
optic  thalami  and  the  corpora  geniculata  interna.  They  are  sharply  marked  off 
from  the  latter,  but  less  distinctly  from  the  thalami.  Each  brachium  is  contimied 
below  the  corpus  geniculatum  externum  of  its  own  side  directly  into  the  optic 
tract. 

The  testes  are  lighter  in  colour,  and  form  more  ])ronnimced  elevations  tlian  the 
nates.  Each  testis  is  a  somewhat  pear-shaped  body,  the  narrow  end  of  which  is 
continued  into  the  lirachium  of  its  own  side. 

The  brachia  of  the  testes,  or  inferior  brachia,  are  narrower  and  more  promi- 
nent than  the  brachia  of  the  nates,  and  run  iiaralld  to  the  latter.  Each  brachium 
]>asses  below  the  corpus  geniculatum  internum  of  its  own  side  and  disap])ears  from 
the  surface. 

The  corpus  geniculatum  internum  is  an  oval  elevation  which  is  jdaced  behind 


CORPORA   QUADRIGEMINA 


'11 


the  lateral  groove  of  the  mesencephalon  under  cover  of  the  pulvinar.  Its  long  axis 
is  directed  transversely.  A  band  of  white  fibres  is  prolonged  from  its  outer  end 
into  the  optic  tract.  This  passes  as  the  hindermost  layer  of  fibres  in  the  optic 
commissure  into  the  corresponding  bundle  of  the  opposite  side.  It  is  therefore 
commissural  in  nature.      It  does  not  contribute  any  fibres  to  the  optic  nerve. 

Tlie  corpus  geniculatum  externum  is  a  slight  elevation  at  the  outer  side  of 
the  pulvinar.      It  is  directly  continuous  with  the  optic  tract. 

The  remainder  of  the  mesencephalon  is  formed  b}'  the  crura  cerebri,  each  of 
which  is  divided  into  three  distinct  parts  easily  recognised  in  transverse  section  (fig. 


Fig.  424. — Deep  Origin  of  the  TiiiEn  Xerve.     (After  Krause 


AQUEDUCT  OF  SYLVIUS 


DESCENDING 
ROOT  Of 
TRIGEMINAL 
\'^ER  VE 


CLEUS  OF 
THIRD  NERVE 


POSTERIOR 
LONGITUDINA  L 
BUNDLE 


SUBSTANTIA 
NIGRA 


RAPHE 


THIRD  NER  VE 


r^k 


•4t 


,t*'. ',' 


%. 


CRUST  A 


mm 


424).  These  are  (1)  a  greyish  upper  portion,  the  tegmen  ;  (2)  a  band  of  almost 
black  substance,  the  substantia  nigra  ;  and  (8)  a  lower  white  portion,  the  crusta, 
which  appears  at  the  base  of  the  brain.  Tlie  tegmen  is  also  marked  of¥  superticially 
from  the  crusta  b}'  two  grooves,  the  oculo-motor  and  the  lateral  groove,  wliich 
may  be  seen  in  section  to  correspond  with  the  inner  and  outer  extremities  of  the 
substantia  nigra.  The  oculo-motor  groove  derives  its  name  from  the  third  or  oculo- 
motor nerve,  the  filaments  of  which  reach  the  surface  along  this  furrow.  The 
lateral  groove  of  the  mesencephalon  is  best  marked  near  the  upper  border  of  the 
pons,  where  it  is  bounded  below  by  the  superficial  fibres  of  the  crusta;  and  above 


712 


THE  NERVOUS  SYSTEM 


by  a  triangular  band  of  fibres,  the  fillet,  whieli  disappears  under  the  testis  and  its 
brachium. 

The  crusta,  or  pes,  is  a  large  flattened  band  of  white  fibres  which  is  crescentie 
in  section,  with  the  concavity  directed  backwards  and  inwards,  and  in  contact  with 
the  sul:)stantia  nigra.  Its  antero-inferior,  inner,  and  outer  surfaces  are  free. 
These  surfaces  are  marked  with  ridges  indicating  the  bundles  of  fibres  of  which  it 
is  composed.  These  ridges  do  not  run  parallel  to  the  axis  of  the  crus,  but  take  a 
slightly  curved  course,  passing  at  first  outwards  and  then  upwards.  The  crusta  is 
continuous  below  through  the  i)ons  with  the  pyramidal  ])ody  of  the  same  side,  and 
with  the  cerebellar  hemisphere  of  the  opposite  side.  It  is  somewhat  constricted 
where  it  emerges  from  the  pons.      It  is  continuous  above  with  the  inner  capsule. 

Dissection. — Tlie  student  sliould  scrape  away  the  remains  of  the  lenticular  nucleus  on  the 
left  side  until  the  white  substance  of  the  inner  capsule  is  exposed.  He  should  then  raise  the 
superficial  fibres  of  the  under  surface  of  the  crus  of  the  same  side,  and  by  tearing  off  these  fibres 
in  an  upward  direction  he  may  readily  demonstrate  the  continuity  of  the  crusta  with  the  inner 
capsule.  The  dissector  may  also  follow  the  fibres  of  the  crusta  downwards  to  the  pyramidal 
bodies  by  cutting  through  the  supei-ficial  transverse  fibres  of  the  pons,  but  it  is  better  to  defer  this 
dissection  till  a  later  period.     The  remainder  of  the  mesencephalon  with  the  optic  thalami  should 


Fig.  425. — Lateral  View  of  Mesencephalox,  Poxs,  and  Medulla.     (Gegenbaur.) 


CORPUS  GENICULA  TUM 
EXTERNUM 


CR  USTA 


poys 


OLIVARY  BODY 


PULVINAR  OF  OPTIC 
THALAMUS 

PINEAL  BODY 
CORPUS  GENICULATUM 
INTERNUM 


CORPORA 
qUADRIGEMINA 

FILLET 


MIDDLE  CEREBELLAR 
PEDUNCLE 


INFERIOR  CEREBELLAR 
PEDUNCLE 


be  carefully  preserved  until  the  end  of  the  dissection  of  the  brain,  when  they  should  be  examined 
in  connection  with  the  medulla  and  i)ons  by  a  series  of  sections. 

The  fibres  composing  the  central  third  of  the  crusta  are  derived  from  the  pyramidal  bodies 
and  pass  into  the  anterior  half  of  the  posterior  linil)  of  the  inner  ca])sule  to  the  ascending  frontal 
and  ascending  parietal  convolutions.  Its  outer  third  i.s  formed  by  fibres  which  are  i)artly  derived 
from  the  cerebellar  hemispheres  of  the  opposite  side,  and  which  pass  through  the  i)Osterior  half 
of  the  posterior  limb  of  the  inner  capsule  to  the  temporal  and  occipital  lobes.  "J'hese  fibres  are 
considered  to  be  senscny  in  function.  Lastly,  the  fibres  constituting  its  inner  third  pass  upwards 
through  the  genu  and  anterior  limb  of  the  cajjsule  to  the  convolutions  of  the  frontal  lobe,  while 
below  some  form  communications  with  the  iniclei  of  the  cranial  nerves,  and  others  are  distributed 
to  the  ct'r(!bellum  in  a  similar  manner  to  the  fibres  of  the  outer  third  of  the  crusta.  There  are 
other  tracts  of  minor  importance  in  the  crusta. 

The  tegmental  portions  of  the  crura  cerebri,  unlike  the  crusta^,  are  continuous 
with  one  another  across  the  middle  line,  where  they  unite  in  a  median  raphe. 
Each  tegmen  extends  into  the  thalamencephalon  beloAv  the  optic  thalamus,  wln're 
it  contains  a  yellowish-grey  lenticular  body  which  is  called  the  subthalamic  body. 
The  tegmentum  contains  both  grey  and  white  matter,  with  a  continuation  of  the 
formatio  reticularis  of  the  medulla  and  ])ons.  The  most  conspicuous  of  the  collec- 
tions of  grey  matter  is  the  tegmental  or  red  nucleus,  a  mass  of  brownish-grey 


ErEyCEPHALOy—TIIE   CEEEBELLUM  713 

matter  which  i;;  placeil  helow  the  optio  thalamus,  and  extends  backwards  into  the 
mesencei>halon  below  the  aqueiluct.      It  appeal"^  round  in  coixnial  sections  (^tig.  423). 

The  best  marked  of  the  white  strands  are  the  superior  peduncles  of  the  ceii^ 
helium,  the  tillet,  and  the  posterior  longitudinal  bundle  i^tig.  444).  The  tilaments 
of  origin  of  the  third  nerve,  passing  from  its  nucleus  through  the  tegmentum  and 
inner  part  of  the  substantia  nigra,  are  also  conspicuous  in  stations  (tig.  443). 

The  superior  cerebellar  peduncle  is  readily  distinguishable  in  stvtions  through 
the  lowest  part  of  the  mesencephalon  as  a  white.  crescent-shapiH.1  bundle  with  its 
inner  or  concave  side  bounded  by  the  grey-coloui-eil  formatio  reticularis  which 
separates  it  from  the  grey  matter  of  the  aqueduct.  Higher  up  it  takes  a  deeper 
course  below  the  lloor  of  the  aqut\iuct,  and  dtvussates  with  its  fellow  of  the  oppl^site 
side.  It  then  passes  into  the  subthalamic  region,  and  separates  into  an  inner  and 
an  outer  division.  The  inner  division  }nisses  internal  to  the  red  nucleus  and  entei-s 
the  under  surface  of  the  optic  thalamus.  The  outer  division  passes  external  to  the 
red  nucleus  and  probably  enters  the  globus  pallidus  of  the  lenticular  nucleus. 
Fibres  have  been  descrilxxl  as  passing  from  the  rt\I  nucleus  to  the  cerebral  cortex. 

The  fillet  appeai-s  at  the  level  of  the  lower  quadrigeminate  bodies  as  a  tiat  baud 
of  longitudinal  fibres  in  the  ventral  inirt  of  the  tegmentum,  into  which  it  has 
passed  from  the  pons  (fig.  429)  and  dorsal  to  the  substantia  nigra.  It  consists  of 
three  parts,  an  outer  or  lateral,  internal  or  mesial,  and  an  intermediate  or  middle 
l>art.  The  lateral  part  jnisses  outwards  to  the  surface  and  curving  round  the  outer 
side  of  the  superior  cerebellar  peduncle  it  terminates  at  the  lower  quadrigeminate 
body  i^fig.  4"2o).  It  is  also  known  as  the  lower  tillet,  and  in  addition  to  fibres 
derived  from  the  ascending  antero-lateral  tract  by  the  superior  medullary  velum 
it  contains  tiln-es  from  the  o}>}>osite  auditory  nucleus,  and  other  fibres  which 
ha\e  jnissed  from  the  nuclei  of  the  fasciculus  gracilis  and  fasciculus  cuneatus  of  the 
opi>osite  side  by  the  superior  pyramidal  de<.nissation.  The  internal  or  mesial  fillet 
turns  downwards  into  the  inner  part  of  the  crusta  and  is  continued  to  tlie  sub- 
thalamic tegmental  region,  where  it  enters  the  ansa  lenticularis,  by  which  it  is 
conveyed  to  the  medullary  lamimv  of  the  lenticular  nucleus.  The  middle  or  inter- 
mt\liate  fillet  is  separable  into  two  parts:  an  outer  part,  calkxl  the  uj^per  fillet, 
which  terminates  in  the  white  matter  of  the  superior  quadrigeminate  body,  and 
a  remaining  ]>ortion  which  }>asses  upwards  into  the  subthalamic  tegmental  region, 
and  possibly  reaches  the  brain  cortex.  The  fibres  of  the  middle  fillet  are  derivtHl 
from  the  antero-lateral  cohunn  of  the  cord  of  the  same  side,  from  the  nuclei  of  the 
funiculus  gracilis  and  the  funiculus  cuneatus  of  the  opposite  side  by  the  suinnior 
})yramidal  decussation,  and  from  the  cerebellum. 

The  posterior  longitudinal  bundle  is  a  strand  of  large  white  fibres  which  lies 
directly  beneath  the  ventral  i^art  of  the  central  grey  matter  of  the  aqueduct  in  the 
lower  part  of  the  mid-brain,  whilst  in  the  up]>er  part  it  gains  a  more  lateral  position 
(fig.  424);  it  can  be  traced  downwards  to  the  pons  (fig.  429)  and  medulla,  and 
upwards  to  the  posterior  connnissure.  the  pineal  body,  and  the  subthalamic  region. 
It  is  a  connnissural  strand  which  connects  the  cerebellum  with  the  nuclei  of  the 
cranial  nerves,  and  it  also  associates  the  various  cranial  miclei  together.  It  is  par- 
ticularly connected  with  the  third  and  sixth  cranial  nuclei  of  opposite  sides,  some 
of  the  fibres  decussating  through  the  raphe,  and  it  possibly  contains  fibres  which 
have  passed  upwards  from  the  antero-lateral  colunms  of  the  spinal  cord. 

ThK    ErENCEFHALON 

Dissection.— The  i>la  niator  should  l>o  i-ouiovtxi  fi-om  the  superior  and  inferior  snrtiuvs  of  tlie 
cinobolhmi  ;  earo  should  Ik>  taken,  however,  in  removiiisr  it  from  the  infoiior  vernntorm  pixxvss. 
In  disstvting  the  latter  region,  the  uiembranos  should  W  elinped  close  with  .<«.'i!v<^>rs  rather  than 
pulled  out,  as  by  the  latter  method  the  choroid  plexuses  of  the  fourth  ventricle  would  be  removtHl 
and  tlie  fniirile  posterior  medullary  velum  would  be  torn.  The  student  should  examine  tii-st  the 
upper  and  then  the  lower  siutaee  of  the  cerebellum,  but  he  should  defer  the  study  of  the  anterior 
parts  of  the  inferior  vermiform  process  (pyramid  and  nodule)  luitil  the  fourth  ventricle  is  opened. 

The  CEREBELLUM  consists  of  two  lateral  masses,  the  hemispheres,  which  are 
united  by  a  narrower  median  ]>ortion.  the  vermiform  ]n'ocess.  This  is  seen  in 
sagittal  section  in  fig.   427.     This  median  portion  is  but  slightly  raised  above  the 


714  THE  yERVOUS  SYSTEM 

level  of  the  hemisi)lieres  as  seen  from  above,  ^vhel•e  it  constitutes  the  superior 
vermiform  process  (fig.  427);  but,  as  seen  from  below  (inferior  vermiform 
process),  it  forms  the  roof  of  a  deep  recess  between  the  hemisi)lR-res,  the  vallecula, 
which  is  occupied  for  the  most  part  by  the  mi-dulla.  Tht-  vallecula  terminates  in 
front  at  the  cavity  of  the  fourth  ventricle.  Behind,  it  passes  into  a  deep  notch,  the 
incisura  marsupialis,  which  is  occupied  by  the  falx  cerebelli  and  the  cisterna 
nuunia  of  the  sul)araelnioid  space.  The  surface  of  the  cerebellum  is  covered  by  a 
number  of  folia,  which  are  curved,  Avith  a  general  direction  convex  backwards  and 
outwards.  The  folia  are  much  narrower  than  the  cerebral  convolutions,  and  are  of 
a  darker  grey  color  than  the  latter.  They  are  separated  ])y  fissures,  some  of  which 
appear  on  the  surface  separating  individual  folia;  others  dip  in  for  some  distance 
below  the  surface,  and  within  these  secondary  fissures  are  developed.  In  this  way 
the  great  horizontal  fissure  and  the  interlobar  fissures  are  formed.  The  separation 
hito  lobes  is  somewhat  arbitrary,  as  fissures  reseml)ling  the  interlobar  fissures  in 
character  traverse  the  substance  of  the  lobes. 

The  cerebellum  is  connected  to  the  adjacent  parts  of  the  cerebro-spinal  axis  by 
three  pairs  of  peduncles  :  a  superior  pair  to  the  cerebrum;  a  middle  pair  to  the 
pons;  and  an  inferior  pair  to  the  medulla. 

The  great  horizontal  fissure  is  deei>er  than  the  interlobar  fissures.  It  com- 
mences at  the  point  where  the  middle  peduncle  of  the  cerebellum  enters  the  hemi- 
sphere and  pursues  a  curved  course  around  the  margin  of  the  hemisphere,  inclining 
first  downwards,  and  then  curving  slightly  upwards,  and  crossing  the  middle  line 
immediately  above  the  incisura  marsupialis,  to  pursue  a  similar  course  on  the 
opposite  side.  On  opening  up  the  fissure,  numerous  folia  are  seen  to  run  oljliquely 
within  it,  some  of  which  cross  the  floor  of  the  fissure  so  as  to  connect  the  upper 
and  lower  surfaces  which  bound  the  fissure.  The  great  horizontal  fissure  separates 
the  superior  and  inferior  surfaces  of  the  cerebellum. 

The  superior  surface  of  the  cerebellum  has  a  general  inclination  backwards 
and  outwards.  This  surface  is  approximately  flat,  but  shows  a  slight  concavity 
corresponding  to  the  superjacent  occipital  lol^e  of  the  cerebrum.  Mesially  the  slope 
of  the  surface  becomes  more  abrupt,  and  forms  the  superior  vermiform  process. 
Of  the  fissures  which  traverse  this  surface  the  most  important  is  the  sulcus  cere- 
belli superior,  which  branches  off  from  the  great  horizontal  fissure  at  its  com- 
mencement and  curves  over  the  posterior  part  of  the  upper  surface  to  approach  the 
great  horizontal  fissure  again  at  the  superior  vermiform  process,  where  the  two 
fissures  are  separated  only  by  a  narrow  bandj  the  folium  cacuminis  (fig.  427).  The 
sulcus  cerebelli  superior  divides  the  superior  surface  into  a  larger  anterior  part,  the 
quadrate  lobe,  and  a  smaller  semilunar  posterior  portion,  the  posterior  superior 
lobe.  Another  fissure  divides  the  quadrate  lobe  into  an  anterior  crescentic  and 
a  posterior  crescentic  portion.  The  anterior  crescentic  portion  is  usually  sub- 
divided into  two  })()vtions  by  another  sulcus  parallel  to  the  fissure  last  mentioned. 

The  superior  vermiform  process  is  divided  by  fissures,  continuous  with  the 
sulci  above  described,  into  parts  which  are  placed  in  the  following  order  from  l)efore 
l»ack wards:  lol^ulus  centralis,  monticulus  cerebelli,  and  folium  cacuminis.  The 
lobulus  centralis  is  a  small  squarish  mass  which  is  placed  below  and  behind  the 
testes,  separated  from  the  latter  by  a  fold  of  pia  mater.  It  rests  below  on  the 
lingula,  which  separates  it  from  the  valve  of  Vieussens  (fig.  426).  It  ex])ands 
laterally  into  a  pair  of  somewhat  triangular  folds,  tlie  alae  (fig.  426),  which  are 
entirely  overlapped  and  hidden  l)y  the  quadrate  lobes  when  tlie  cereV)ellum  is  viewed 
from  above  in  its  undisturbed  position.  The  lingula  is  a  small  tongue-shaped 
portion  of  the  cerebellum  which  lies  on,  and  is  adherent  to,  the  valve  of  Vieussens. 
Its  basal  part  is  continuous  with  the  lobulus  centralis,  and  it  consists  of  from  four 
to  five  transverse  folia.  The  monticulus  cerebelli  is  divided  into  an  anterior 
elevated  portion,  the  culmen,  and  a  posterior  sloping  part,  the  declive.  The  culmen 
connects  the  anterior  crescentic  portions  of  the  quadrate  lobes  of  opposite  sides,  and 
is  traversed  by  the  fissures  which  intersect  these  portions.  The  declive  connects 
the  posterior  crescentic  portions,  and  consists  of  about  six  or  seven  transverse  folia. 
The  folium  cacuminis  is  a  narrow  band  whicli  connects  the  posterior  superior 
lobes  of  opposite  sides.  It  is  not  a  simple  folium,  but  is  marked  on  its  superior 
and  inferior  surfaces  by  transverse  furrows. 


KPESCEPHALOX 


715 


Tlic  inferior  surface  of  the  cerebellum  shows  a  pronounced  convexity  corre- 
sponding to  the  inferior  fossic  of  the  occipital  bone  on  which  it  rests.  It  is  smoothly 
rounded  off  externally  and  behind,  but  changes  its  direction  abruptly  internally  and 
in  front,  where  it  conies  in  contact  with  the  medulla  and  pons.  It  is  marked  off 
into  lol)es,  which  are  arranged  in  the  following  order  from  Ijehind  forwards:  i»ns- 
terior  inferior,  slender,  l>iventral,  tonsillar,  and  Hocculus.  The  posterior  inferior 
is  a  narrow  crescentic  lolic,  wliich  l)ounds  the  great  horizontal  fissure  inferiorly. 
The  slender  (lobulus  gracilis)  is  similar  in  shape,  l»ut  narrower,  as  its  name 
implies.  The  biventral,  sliorter  and  thicker  than  the  two  last  described,  is  divided 
by  a  well-marked  fissure  into  an  anterior  and  a  posterior  portion.  The  tonsillar 
lobe  (amygdala)  lies  internal  and  slightly  anterior  to  the  biventral,  and  is  partly 
hidden  in  the  vallecula.  The  flocculus  is  a  small  lobe  forming  a  marked  projec- 
tion in  front  of  the  biventral  lobe,  which  it  separates  from  the  middle  peduncle  of 
the  cerebellum. 

The  inferior  vermiform  process  is  formed  by  the  following  parts,  taken  in 
order  from  behind  forwards:  tuber  valvuhe,  pyramid,  uvula,  and  nodule.  The 
tuber  valvulae  is  a  transverse  l)and,  consisting  of  about  seven  or  eight  folia,  which 
connects  the  posterior  inferior  and  slender  lobes  with  their  fellows  of  the  opposite 


Fig.  426.  — Inferior  Surface  of  the  Cerebellum. 
(From  a  mounted  specimen  in  the  Anatomical  Department  of  Trinity  College,  Dublin. 
VALVE  OF  VIEUSSENS      LOBVLUS  CENTRALIS 


MIDDLE 
PEDUNCLE 
FLOCCUL 
FOURTH 
VENTRICLE 
BIVENTRAL 
LOBE 

UVULA 


PYRAMID 

SLENDER 

LOBE 


POSTERIOR 

INFERIOR 

LOBE 


SUPERIOR  PEDUNCLE 


POSTERIOR 
CRE.SCENTIC 
LOBULE 

SULCUS 
CEREBELLI 
>  I  PERIOR 


VOD  ULE 
IMYGDALA 


TUBER 

VALVULJE 

I  NCI  SURA 
MARSUPIALIS 


side.  The  pyramid  is  the  most  massive  portion  of  the  inferior  vermiform  process, 
and  is  connected  to  the  l)iventral  lobes  on  each  side.  It  consists  of  from  five  to 
eight  folia.  The  uvula  is  an  elongated  portion,  compressed  laterally,  and  connected 
to  the  amygdala  on  each  side  by  the  furrowed  band.  The  nodule,  or  laminated 
tubercle,  is  the  prominent  anterior  extremit}'  of  the  inferior  vermiform  process 
which  projects  into  the  cavity  of  the  fourth  ventricle.  It  is  connected  to  the  floc- 
culus on  each  side  by  a  thin  white  plate,  the  inferior  medullary  velum.  The 
latter  will  be  referred  to  in  connection  with  the  anatomy  of  the  fourth  ventricle. 

Dissection. — The  student  should  now  obtain  a  view  of  the  principal  systems  of  fibres  in  the 
cerebelhim  by  the  following  dissection,  which  we  shall  speak  of  as  Reil's  metliod.  The  great 
horizontal  fissure  should  be  opened  up  and  the  portion  of  the  cerebellum  which  lies  superior  to 
that  fissure  gently  torn  off  the  underlying  portion.  If  this  proceeding  has  been  successfully 
accomplished,  a  large  bundle  of  fibres  will  be  seen  passing  through  a  gap  between  the  superior 
and  middli'  jieduncies  of  the  cerebellum,  and  ])assing  towards  the  superior  surface.  This  bundle 
is  formed  by  the  restiform  body  and  by  tlie  lower  fibres  of  the  pons.  The  ]iosition  of  the  corpus 
dentatum  will  also  be  noticeable  near  tlie  middle  line,  as  the  white  fibres  which  form  the  capsule 
of  that  body  are  disposed  in  ridges  corresponding  to  the  plications  of  grey  matter  of  the 
nucleus.  A  more  superficial  dissection  on  the  opposite  side  will  show  the  fibres  of  the  above- 
mentioned  bundle  passing  inwards,  forming  at  first  curves  convex  backwards,  and  then  sweeping 
upwards  into  the  folia  of  the  superior  vermis.     A  li(jrizontal  section  through  tlie  corpus  dentatum 


716  THE  yERVOUS  SYSTEM 

on  the  right  side  will  expose  the  plicated  bag  of  grey  matter  which  constitutes  the  nu(_-lfus,  an 
opening  into  which,  the  hiluiu,  will  be  seen  on  the  inner  and  ujtper  side.  If  a  small  portion  of 
the  fibres  of  the  superior  peduncle  of  the  cerebellum  of  the  same  side  be  now  raised  and  torn 
gently  in  a  downward  direction,  the  fibres  are  readily  traceable  into  the  white  centre  of  the 
nucleus. 

A  horizontal  section  through  the  superior  vermis  will  show  the  smaller  nuclei  of  the  cerebel- 
lum (nuclei  fastigii,  embuliformis,  and  globosus).  These  are,  however,  somewhat  difficult  to  find. 
Lastly,  a  median  sagittal  section  will  expose  the  fourth  ventricle,  to  obtain  a  good  view  of  which 
the  remainders  of  the  cerebellar  hemi.spheres  should  be  drawn  gently  aside.  In  doing  this  care 
should  be  taken  of  the  inferior  medullary  velum. 

White  matter  of  the  cerebellum. — In  a  mesial  sagittal  section  of  the  cere- 
bellum (fig.  427)  the  amount  of  white  matter  is  smaller  in  proportion  to  the  grey 
matter  than  in  any  other  section.  It  ])resents  a  characteristically  branched  appear- 
ance which  is  called  the  arbor  vitae.  Two  main  divisions,  the  vertical  and 
horizontal  branches,  of  the  arbor  vittc  are  described,  and  from  these  secondary 
ramifications  arise.  The  vertical  branch  is  mainly  continued  into  the  culnien, 
Avhere  it  sul)divides  somewhat  freely.  It  sends  forwards  usually  two  branches  into 
the  lol)ulus  centralis,  and  a  slender  twig  into  the  lingula.  The  main  axis  of  the 
horizontal  branch  is  prolonged  into  a  slender  white  band,  which  enters  the  folium 
cacuminis.  From  the  upper  surface  of  the  horizontal  branch  a  stout  oft'set  is  sent 
into  the  declive,  and  from  its  lower  surface  branches  are  sent  into  the  tuber  val- 
vula?,  pyramid,  and  uvula.  A  small  offset  enters  the  nodule,  and  if  this  be  traced 
in  a  lateral  direction  it  will  be  found  to  be  continued  into  the  inferior  medullary 
velum. 

In  coronal  sections  the  disposition  of  the  white  matter  in  the  hemispheres  is 
well  seen.  It  forms  a  somewhat  ovoid  mass  in  each  hemisphere,  near  the  centre  of 
which  the  corpus  dentatum  is  placed  (fig.  416).  The  appearance  is  very  similar  in 
sagittal  sections  through  the  centre  of  a  hemisphere.  It  is  not  necessary  to  give  a 
separate  description  of  the  divisions  of  the  white  matter,  as  these  correspond  to  the 
lol)ulation  of  the  surface. 

The  grey  matter  in  the  interior  of  the  cerebellum  consists  of  four  pairs  of 
nuclei,  Avhich  are  everywhere  separated  Ijy  Avhite  matter  from  the  grey  matter  of  the 
folia.  The  largest  of  these  nuclei  in  each  hemisphere  is  called  the  corpus  dentatum. 
The  smaller,  which  are  placed  nearer  the  middle  line,  are  called  the  nucleus  emboli- 
formis,  nucleus  glolwsus,  and  nucleus  fastigii. 

The  corpus  dentatum  is  a  crumpled  sheet  of  grey  matter  which  presents  a 
similar  outline  in  coronal,  sagittal,  and  horizontal  sections.  This  outline  is 
approximately  an  oval  bounded  by  a  wavy  line.  This  line  is  broken  only  on  the 
inner  and  anterior  side,  where  the  white  matter  of  the  exterior  is  continuous  with 
that  of  the  interior  through  an  aperture  called  the  hilum. 

Tin-  nucleus  emboliformis  is  an  elongated  streak  of  grey  matter,  which  is 
placed  on  the  inner  side  of  the  corpus  dentatum.  It  is  somewhat  enlarged  at  its 
anterior  extremity,  hence  it  may  be  descrilx'd  as  club-shaped.  The  nucleus  glo- 
bosus consists  of  several  s^jheroidal  clumps  of  grey  matter,  which  are  ])laced  on  the 
inner  side  of  the  preceding;  these  clumps  are  connected  with  one  another,  and  also 
Avith  the  nucleus  emboliformis  and  nucleus  fastigii.  The  nucleus  fastigii  varies 
somewhat  in  its  minute  structure  from  the  three  nuclei  above  described.  It  is 
situated  innnediately  over  the  roof  of  the  fourth  ventricle,  separated  from  that 
cavity,  however,  by  a  thin  stratum  of  white  matter.  The  nuclei  of  opposite  sides 
nearly  touch  one  another  in  the  middle  line. 

The  fibres  of  the  cerebellum  may  be  described  under  the  following  heads: 
(rt)  Fibres  derived  from  the  cerebellar  peditncles,  and  (b)  intrinsic  fibres,  (a)  The 
fibres  of  the  middle  peduncle  connect  the  cerebellum  (1)  Avitli  the  miclei  of  the 
l)ons  on  the  same  side,  (2)  with  the  i)Osterior  longitudinal  Imndle  and  the  fillet  of 
the  same  side,  and  by  means  of  these  tracts  with  the  corpora  quadrigemina,  and 
the  antero-lateral  tract  of  the  spinal  cord,  (3)  with  the  pyramidal  tracts  of  the 
same  and  the  opposite  side  by  means  of  wbich  connections  are  established  with 
the  corpora  quadrigemina  and  the  corpus  striatum.  The  upper  fibres  of  the 
pons  pass  into  the  lateral  parts  of  the  cerebellar  hemispheres,  and  end  in  the  grey 
cortex.  The  middle  fibres  sweep  dowiiAvards,  fornung  tlie  oblique  fasciculus, 
and  end  in  the  folia  of  the  inferior  surface.     The  lower   fibres  accom]tany  the 


FOURTH  VEXTRICLE  717 

ivstiform  body  to  the  superior  surface.  The  restiform  body  T inferior  peduncle)  is 
joined  on  entering  the  cerebehuni  by  the  inferior  fibres  of  the  jions;  the  two  together 
unite  into  a  distinct  round  bundle,  the  inner  part  of  which  is  formed  by  the  resti- 
form 1)ody ;  the  outer  by  the  pons-tibres.  This  bundle  passes  through  a  distinct  gap 
or  interval  bounded  by  the  sui)erior  peduncle  internally,  and  by  the  greater  part  of 
the  middle  j)eduncle  externally.  Its  fibres  then  spread  out  into  a  layer,  the  fibrte 
semicirculares  of  Stilling  which  are  disposed  in  gentle  curves  convex  backwards 
and  outwards;  these  fibres  cover  the  capsule  of  the  corpus  dentatum,  and  finally 
sweep  abruptly  upwards  into  the  folia  of  the  superior  vermis.  Some  fibres  enter 
the  nucleus  fastigii.  The  fibres  of  the  inferior  peduncle  are  connected  with  the 
opposite  olivary  body,  Avith  the  fillet  and  posterior  longitudinal  bundle  of  the 
same  side,  and  with  the  antero-lateral  column  of  the  cord. 

The  corpus  dentatum  is  covered  by  a  distinct  capsule  of  fibres  (the  '  fleece '  of 
Stilling)  derived  from  the  olivary  nucleus  of  the  opposite  side.  The  fibres  are 
prol)ably  for  the  mr)st  part  interrupted  in  the  nerve-cells  of  the  corpus  dentatum, 
and  are  then  (indirectly)  continued  into  the  white  matter  Avhich  occupies  the 
interior  of  that  plicated  bag  of  grey  matter.  From  the  hilum  of  the  corpus 
dentatum  a  bundle  of  fibres  passes  out,  which  is  joined  by  fibres  from  the  fleece, 
and  thus  the  superior  cerebellar  peduncle  is  fomied.  The  superior  cerebellar 
peduncle  passes  upwards  and  inwards,  and  receives  a  covering  on  its  outer  side 
from  the  inferior  fillet.  It  disappears  from  the  surface  by  passing  under  cover  of 
the  testis  of  its  own  side,  and  assumes  a  deeper  position  in  the  mesencephalon, 
jjassing  to  the  ventral  side  of  the  aqueduct  of  Sylvius.  The  majority  of  the  fibres 
decussate  with  their  fellows  of  the  opposite  side,  the  decussation  being  most  pro- 
nounced at  the  level  of  the  centre  of  the  nates.  The  decussation  l^eing  com- 
pleted, the  decussated  fibres  and  those  which  remain  on  the  same  side  proceed 
brainwards  as  a  distinct  column.  This  column  of  fibres  soon  encounters  the  red 
nucleus,  and  the  fibres  pass  through  the  nucleus  in  small  bundles,  the  cross-section 
of  which  gives  the  punctated  appearance  to  the  red  nucleus  w^hich  is  so  charac- 
teristic of  that  body  when  seen  in  coronal  section.  Beyond  the  red  nucleus,  fibres 
<»f  the  superior  peduncles  certainly  enter  the  optic  thalamus,  and  proljably  the 
globus  pallidus  and  the  cortex  cerebri. 

(6)  Sagittally-directed  fibres  are  placed  within  the  superior  vermis.  When 
traced  forwards  these  fibres  are  found  to  decussate  with  their  fellows  of  the  opposite 
side  in  front  and  above  the  nucleus  fastigii;  here  they  are  joined  by  true  commis- 
sural fibres  from  its  hemispheres,  the  whole  forming  the  great  anterior  cerebellar 
commissure  of  Stilling. 

Filires  unite  the  different  folia  to  one  another,  constituting  a  system  of  fibres 
which  form  the  most  peripheral  ]k\v{  <>f  the  arbor  vitte.  These  fibres,  from  their 
general  arrangement,  are  called  garland-like  fasciculi. 

The  FOURTH  VENTRICLE  is  a  cavity  which  is  Avidest  and  most  lofty  about  its 
centre,  and  narrowed  at  its  anterior  and  posterior  extremities.  It  communicates 
with  the  third  ventricle  al)ove  through  the  aqueduct  of  Sylvius,  and  passes 
below  into  the  central  canal  of  the  spinal  cord.  Its  long  axis  is  directed  upwards 
and  forwards.  The  structures  Avhich  bound  it  behind  are  said  to  constitute  its 
roof,  while  the  parts  bounding  it  in  front  are  described  as  its  floor.  The  roof  is 
formed  from  above  doAvnwards  Ijv  the  folloAving  structures:  the  superior  peduncles 
of  the  cerebellum  with  the  valve  of  Vieussens  between  them,  the  Avhite  matter  of 
the  vermiform  process  of  the  cerebellum,  the  inferior  medullary  vela,  and  the  epi- 
thelial lining  of  the  choroid  plexuses  and  tela  choroidea  inferior.  Some  small 
plates  of  wliite  matter,  the  obex  and  the  ligula^  also  enter  into  the  fonuation  of 
the  roof.  The  inferior  part  of  the  floor  is  formed  by  the  medulla  and  the  superior 
part  by  the  posterior  surface  of  the  pons.  Some  white  lines  (stride  acustic^e), 
which  cross  the  floor  transversely,  approximately  separate  the  pontine  from  the 
medullary  pr)rtion  of  the  floor. 

The  valve  of  Vieussens,  or  superior  medullary  velum,  is  a  thin  plate  of 
white  matter  which  fills  in  the  angular  interval  between  the  superior  peduncles  of 
the  cerebellum.  It  is  continuous  behind  with  the  white  matter  of  the  superior 
vermiform  process  of  the  cerebellum.     The  lingula  rests  on  the  posterior  part  of  its 


718 


THE  yKRVOCS  SYSTEM 


upper  surface.  The  fibres  of  the  fourth  nerve  decussate  within  its  substance  at  its 
upper  part. 

The  inferior  medullary  vela  are  thin  crescentie  transhicent  bands  of  Avhite 
matter  which  extend  from  the  noduk^  to  the  flocculus  on  each  side;  hence  the}' 
have  been  called  commissurae  ad  flocculos.  Each  velum  presents  a  concave 
edge,  which  is  apparently  free,  but  which  is  in  reality  continued  into  the  epithe- 
lium, which  covers  the  choroid  plexuses.  It  is  attached  to  the  cerebellum  by  its 
convex  edge. 

The  choroid  plexuses  of  the  fourth  ventricle  are  convoluted  vascular  folds  of 
the  i)ia  mater,  wliich  project  into  the  cavity  of  the  fourth  ventricle,  but  are  excluded 
horn  tlie  ventricular  cavity  by  a  layer  of  epithelium.  The}-  run  at  first  forwards 
close  together  on  each  side  of  the  middle  line,  and  then  turn  outwards  along  the 
edges  of  the  inferior  medullary  vela  to  reach  the  lateral  recesses  of  the  ventricle, 
where  they  become  continuous  with  tlie  general  pia  mater. 

Fig.  427. — Eight  Half  of  the  Encephalic  Peduncle  as  seen  from  the  Inside  of  a 
Median  Section.     (Allen  Thomson,  after  Keichert. ) 


MIDDLE  COMMISSURE 

OPTIC  THALAMUS 

PIXEAL  BODY 

CORPORA   QUADRIGEMIXA 

DECEIVE rT*.-r*>^  1 

CR  US  CEREBRI  ^  ?^^^"^*^ 


STRIA  PISE  A  LIS 
THIRD  VEXTRICLE 

AXT.  PILLAR  OF  FORNIX 
ASTERIOR  COilMISSURK 


'  "m-  LAMIXA  CIXEREA 


TVBER  CIXERECM 
REI'ESSUS  I.VFl'X- 
DIBCLI 

PITUITARY  BODY 


AQUEDUCT  OF  SYL  VIUS 

POXS 

FO I  R  TH  I  'EXTRICLE 

IXFERIOR  MED  ULLA  R  Y  VEL  UM 

MEDULLA 


1,  culmcu  ;  2,  posterior  crescentie  lobe  ;  3,  posterior  inferior  lobe  ;  4,  slender  lobe  ;  5,  bi ventral 

lobe  ;   6,  amygdala. 


The  tela  choroidea  inferior  is  a  layer  of  pia  mater  which  closes  in  the  lower 
and  back  part  of  the  foiu-tli  ventricle.  It  extends  from  the  choroid  plexuses  to  the 
ligulffiand  obex,  where  it  is  continued  into  the  pia  mater  which  covers  the  posterior 
surface  of  the  lower  part  of  the  medulla.  As  already  mentioned  in  the  description 
of  the  meninges,  it  presents  three  openings  or  deficiencies:  one  (foramen  of 
Majendie)  in  the  middle  line  immediately  aliove  the  oliex,  and  two  (foramina  of 
Key  and  Retzius )  at  the  lateral  recesses. 

The  obex  is  a  thin,  somewhat  triangular  plate  of  white  matter,  occupying  the 
angular  interval  between  the  two  diverging  clava3.     It  is  not  infrequently  al)sent. 

The  ligulae  are  thin  narrow  strips  of  Avhite  matter,  which  project  from  the  inner 
margins  of  the  clavae.  They  run  at  first  upwards  and  forwards,  and  then  turn 
outwards  around  the  restiform  bodies.  They  may  sometimes  be  traced  as  far  as 
the  flocculi,  when  they  become  continuous  with  the  inferior  medullary  vela.  Their 
inner,  apparently  free,  edges  are  continuous  with  the  epithelial  roof  of  the  fourth 
ventricle. 


FOURTH   VEXTRICLE—POXS   VAROLII  719 

The  floor  of  the  fourth  ventricle  is  a  depressed  area,  Avhieli  is  rhomboidal  in 
outline,  the  longer  diainctfi'  of  tlic  rhomboid  Ijeing  directed  upwards  and  forwards 
and  marked  by  a  very  distinct  tissure,  the  sulcus  longitudinalis  medianus,  wliich 
is  continuous  below  with  the  central  canal  of  the  spinal  cord.  The  ventricular  floor 
is  bounded  laterally  hy  the  clava?  and  corpora  restiformia  below,  by  the  middle 
peduncles  of  the  cerebellum  in  the  middle,  and  by  the  superior  peduncles  of  the 
cerel)ellum  above.  Under  cover  of  the  obex,  where  the  fourth  ventricle  is  about  to 
join  the  central  canal  of  the  cord,  a  small  amjjulla  is  formed,  termed  the  ventricle 
of  Arantius,  The  widest  part  of  the  floor  corresponds  to  the  lateral  recesses  of  the 
ventricle.  Close  Ixdnnd  the  lateral  recesses,  the  floor  is  crossed  by  some  whit(^ 
lines,  the  striae  meduUares  or  striae  acusticae,  which  emerge  from  the  sulcus 
longitudinalis  medianus,  and  pass  outwards  to  the  auditory  nerve.  The  stria? 
diviile  the  flo(jr  into  two  ai)])roximattdy  equal  parts,  an  inferior  and  a  superior. 

The  inferior  moiety  of  the  floor  is  indented  b}'  an  angular  groove,  the 
fovea  inferior  ijr  posterior,  wliieh  marks  off  a  depressed  triangular  area  of  a  grey 
colour,  the  ala  cinerea.  The  latter  corresponds  in  position  to  the  subjacent  nuclei 
of  tlie  vagus  and  glosso-}»harvngeal  nerves,  and  is  therefore  also  termed  the  trigo- 
num  vagi.  The  apex  of  the  posterior  fovea  is  directed  forwards.  It  nearly  touches 
the  striffi  acusticic,  and  thus  two  other  triangular  areas,  both  of  a  Avhitish  colour, 
are  marked  off  in  the  inferior  moiety  of  the  floor.  The  internal  of  these  areas  is 
called  the  trigonum  hypoglossi,  since  it  corresponds  in  po.^ition  to  the  nucleus  of 
the  livpoglossal  nerve.  It  is  l)Ounded  by  the  inferior  fovea,  the  striae  acustica?, 
and  the  sulcus  longitudinalis  medianus.  The  outer  triangle  is  bounded  by  the 
inferior  fovea,  by  the  striae  acusticse,  and  by  the  clavse.  It  forms  the  inferior  part 
of  a  prominence  or  swelling  which  extends  into  the  pontine  portion  of  the  floor. 
This  prominence  is  called  the  tuberculum  acusticum.  It  is  well  marked  in  the 
brain  of  the  infant. 

The  superior  moiety  of  the  floor  is  completely  covered  by  a  thin  layer  of  white 
substance.  It  presents,  on  each  side  of  the  sulcus  longitudinalis  medianus,  a  semi- 
cylindrical  elevation  about  five  millimetres  in  length,  which  is  called  theeminentia 
teres.  It  is  caused  by  an  underlying  bundle  of  fibres,  the  fasciculus  teres, 
wiiich  is  now  known  to  be  a  part  of  the  intrapontine  course  of  the  fibres  of  the 
facial  nerve,  though  possibly  it  may  contain  fibres  from  other  sources.  External 
to  the  eminentia  teres  is  a  depressed  area,  the  fovea  superior,  which  is  occasion- 
ally crossed  by  a  whitish  band  of  fibres,  the  conductor  sonorus.  The  conductor 
sonorus  meets  the  stria  medullaris  of  its  own  side,  at  the  sulcus  longitudinalis 
medianus,  at  an  acute  angle.  Immediately  in  front  of  the  fovea  superior  is  a  Ijluish 
spot,  the  locus  caeruleus,  which  is  caused  by  the  substantia  ferruginea  showing 
through  the  white  covering  of  the  floor.  The  substantia  ferruginea  is  an  aggre- 
gation of  darkly-pigmented  cells,  which  is  very  conspicuous  in  transverse  sections 
through  the  upper  part  of  the  floor  of  the  fourth  ventricle  and  through  the  lower 
part  of  the  aqueduct  of  Sylvius. 

The  PONS  VAROLII  is  that  portion  of  the  epencephalon  which  lies  in  front  of  the 
proximal  part  of  the  fourth  ventricle.  As  seen  from  the  base  of  the  brain,  it  forms 
a  considerable  prominence,  which  narrows  on  each  side  as  it  passes  into  the  middle 
cerebral  peduncles.  At  its  lower  border  the  pyramidal  bodies  are  seen  disappear- 
ing into  its  substance,  while  at  its  upper  border  the  crvu'a  cerebri  are  seen  emerging. 
It  rests  on  the  body  of  the  si)henoid  Ijone,  reaching  upwards  as  far  as  the  margin 
I  >f  the  dorsum  sellse.  It  ]>resents  a  ventral  and  a  dorsal  surface,  and  a  superior  and  an 
inferior  1  )order.  Lateral  surfaces  have  also  been  described,  l)ut  these  are  determined 
artificially  l)y  dividing  the  pons  proper  from  the  middle  cerebellar  peduncles.  The 
boundary  between  the  pons  and  the  middle  cerebellar  peduncles  on  each  side  is 
arbitrarily  mapped  out  by  a  line  drawn  from  the  exit  of  the  trigeminal  nerve  to  the 
superficial  origin  of  the  facial.      (Henle. ) 

The  dorsal  surface  has  been  described  in  connection  with  the  floor  of  the  fourth 
ventricle. 

The  ventral  surface  is  broad  and  prominent,  strongly  convex  from  side  to  side, 
and  slightly  convex  from  l)efore  Itackwards.  It  presents  a  transverse  striation,  cor- 
responding to   the   bundles  of    commissural    fibres  passing  from    hemisphere  to 


720  THE  yERVOrS  SYSTEM 

hemisphere  of  the  cerebellum.  Mesially,  it  is  marked  by  a  sagittal  groove  or 
furrow,  which  usually  lodges  the  basilar  artery,  Init  is  in  no  way  caused  by  the 
contact  with  the  vessel.  On  each  side  of  the  groove  a  prominence  is  formed,  where 
the  sagittally-directed  tibres  of  the  pyramidal  bodies  pass  brainwards,  under  cover 
of  the  transverse  tilires  of  the  pons. 

The  superior  border  is  convex  forwards.  Its  fibres  pass  directly  into  the 
upper  border  of  the  middle  i)eduncle  of  the  cerebellum. 

The  inferior  border  is  marked  off  by  a  distinct  transverse  groove  from  the 
medulla.  It  is  formed  in  its  inner  part  by  the  lowest  fil^res  of  the  pons,  but  these 
are  crossed  near  the  junction  of  pons  and  middle  peduncle  by  the  oblique  fasciculus. 
The  oblique  fasciculus  is  formed  by  the  middle  transverse  fibres  of  the  pons, 
which  pass  downwards  and  backwards,  internal  to  the  exit  of  the  trigeminal  nerve, 
on  each  side,  and  cross  the  inferior  fibres  on  their  superficial  aspect. 

Coronal  sections  through  the  pons  (fig.  429)  shoAV  that  it  comprises  two  very 
distinct  regions — an  anterior  or  ventral  region  and  a  dorsal  region,  which  is  called 
tegmental,  as  most  of  its  constituents  are  continued  into  the  tegmentum  of  the 
mesencephalon.  The  ventral  region  consists  of  transverse  and  longitudinal  fibres, 
interspersed  with  small  aggregations  of  grey  matter.  The  transverse  fibres  are: — 
(a)  Fibres  which  pass  from  the  middle  peduncle  to  the  opposite  side,  where  they 
turn  upwards  to  the  brain  or  downwards  to  the  cord;  (6)  fibres  which  emerge 
from  the  cerebellum  by  the  middle  peduncles,  and  terminate  in  connection  with 
the  nuclei  of  the  pons  on  the  same  side.  The  longitudinal  fibres  are  the  upward 
continuation  of  the  pyramids.  They  pass  upwards  in  flattened  bundles,  separated 
from  one  another  by  some  of  the  transverse  fibres  of  the  pons. 

In  the  upper  or  tegmental  region  the  chief  things  to  be  observed  are:  the 
tract  of  the  fillet  (which  lies  next  to  the  ventral  region),  the  formatio  reticularis, 
the  posterior  longitudinal  bundle,  the  substantia  ferruginea,  and  the  funiculus  teres. 
The  superior  olivary  nucleus,  the  nuclei  of  the  sixth  and  seventh  cranial  nerves, 
the  motor  nucleus  of  the  trigeminal,  with  parts  of  the  ascending  and  descending 
roots  of  the  last-named  nerve  and  portions  of  the  nucleus  of  the  auditor}'  nerve,  are 
embedded  in  this  region  of  the  pons  (figs.  429  and  430). 

The  dorsal  and  ventral  parts  of  the  pons  are  separated  by  a  transverse  layer  of 
fibres  called  the  trapezium  or  corpus  trapezoides  (fig.  430),  because  in  some 
mammals  it  appears  on  the  ventral  surface  of  the  pons  in  a  quadrilateral  area 
between  the  bundles  of  the  pyramidal  fibres  of  the  two  sides.  It  consists  of  fibres 
crossing  from  side  to  side  through  the  raphe  many  of  which,  derived  from  the 
accessory  auditory  nucleus,  pass  through  the  trapezium  to  the  lateral  fillet  of  the 
opposite  side  and  by  it  are  conveyed  to  the  lower  quadrigeminate  body. 

Some  of  the  structures  mentioned  in  the  preceding  paragraph  are  visible  to  the  unaided  eye 
in  ordinary  dissecting-room  specimens.  The  nuclei  of  the  cranial  nerves  will  not  be  further 
described  here,  as  a  full  account  of  them  will  be  given  in  the  section  on  the  cranial  nerves. 

The  Metexcephalox 

The  MEDULLA  OBLONGATA,  or  bulb,  is  the  portion  of  the  cerebro-spinal 
axis  which  extends  from  the  inferior  border  of  the  pons  to  the  decussation  of  the 
pyramids.  It  presents  an  anterior,  a  posterior,  and  two  lateral  surfaces.  The 
anterior  surface  rests  upon  the  basilar  groove  of  the  occipital  bone,  and  extends 
downwards  as  far  as  the  point  Avhere  the  odontoid  process  is  crossed  by  the  trans- 
verse ligament  of  the  atlas  (Testut).  The  bulb  has  the  form  of  a  truncated  cone, 
the  base  of  which  is  continued  into  the  pons  above,  while  the  truncated  apex  is 
prolonged  into  the  spinal  cord  below.  The  posterior  surface  is  received  into  the 
vallecula,  between  the  cerebellar  hemispheres,  and  forms,  by  its  upper  part,  as 
already  descril)ed,  the  lower  part  of  the  floor  of  the  fourth  ventricle.  The 
ninth  to  the  twelfth  nerves  (with  the  exception  of  the  spinal  part  of  the  spinal 
accessory)  take  their  superficial  origin  from  its  sides.  The  sixth,  seventh,  and 
eighth  nerves  appear  in  the  transverse  groove  between  the  medulla  and  the  pons  in 
numerical  order  from  within  outwards. 

The  ventricular  part  of  the  medulla  has  been  already  described;  but  on  the 


ME  TEXCEPHA  L  ON 


"21 


extra  ventricular  portion  certain  fissures,  and  the  elevated  portions  which  these  fis- 
sures map  out,  require  notice. 

Fissures. — Commencing  in  front,  we  find  the  anterior  fissure  (fissura  longi- 
tudinalis  anterior)  occupying  the  middle  line.  It  is  shallow  below,  where  it  is 
almost  separated  from  the  anterior  longitudinal  fissure  of  the  cord  by  the  decussa- 
tion of  the  pyramids;  deeper  above,  where  it  separates  the  pyramids  of  opposite 
sides.  Superiorly,  it  ends  in  a  })lind  recess,  under  the  margin  of  the  pons,  the 
foramen  caecum  posterius,  or  foramen  caecum  of  Vicq  d'Azyr.  External  to 
the  anterior  fissure,  Ave  find  the  sulcus  lateralis  ventralis  ;  the  latter  intervenes 
between  the  pyramid  and  the  olive  above,  and  extends  downwards  immediately  in 


Fig.  428. — Metexcephalon,  Mesencephalon,  and  Thalamencephalox,  from  the  Doesai. 

Surface.     (After  Obersteiner. ) 


ANTERIOR  CORNU 

OF  LATERAL 

VENTRICLE 


FIFTH  VENTRICLE 

SEPTUM  L  VCID  UM 

ANTERIOR  PII^ 

LA  RS  OF  FORNIX 

TAENIA  SEMI- 

CIRCULARIS 

ANTERIOR 

COMMISSURE 

THIRD  VENTRICLE 

MIDDLE 
COMMISSURE 

SULCUS 
CHOROIDEUS 

NA  TES 

CORPUS  GENICU- 
LA  TUM  INTERNUM 

LA  TERA  L  OROO  VE 

OF 
MESENCEPHA  LON 
PONS 

CONDUCTOR 
SO  NOR  US 
SULCUS  LONGITUDINALIS 
MEDIAN  US 

TRIGONUM  HYPOGLOSSI 
CORPUS  RESTIFORME 

CLA  VA 
POSTERIOR  FISSURE 

SULCUS  PA RAMEDIANUS 
DORSALIS 

SULCUS  LA  TERA  LIS  DORSALIS 


\xUJ^ 


CORPUS  CALLOSUM 


CA  UDA  TE 
NUCLEUS 


FORAMEN  OF 
MONRO 


OPTIC  THALAMUS 


STRIA  PINE  A  LIS 

PEDUNCULUS 
CONARII 

PINEAL  BODY 

SULCUS  CORP. 
QUAD.  LONGI- 
TUDINALIS 

TESTIS 

FRENUL  UM  VELI 
LING  ULA 

EMINENTIA   TERES 


TUBERCULUM 
ACUSTICUM 


ALA  CINEREA 

TUBERCULUM  CUNEA  TUM 
FUNICULUS  GRACILIS 
FUNICULUS  CUNEA TUS 
LA  TERA  L  COL  UMN 


front  of  the  olive  and  the  lateral  cohunn.  It  is  joined  below  the  olive  by  the  post- 
olivary  sulcus.  FroTu  its  upper  part,  a  fissure  (sulcus  parapyramidalis)  passes 
downwiirds  and  inwards  to  join  the  anterior  fissure. 

On  the  posterior  surface  of  the  medulla  we  find  the  posterior  fissure  (fissura 
longitudinalis  posterior)  occupying  the  middle  line.  It  is  continuous  below  with 
the  posterior  fissure  of  the  spinal  cord,  and  ends  above  at  the  fourth  ventricle. 
External  to  this  we  find  the  sulcus  paramedianus  dorsalis,  and  more  externally 
the  sulcus  lateralis  dorsalis.  The  former  of  these  two  fissures  ends  above  at  the 
apex  of  the  clava,  the  latter  extends  for  some  distance  further  upwards.  To  reca- 
pitulate, the  fissures  of  the  medulla,  taken  in  order  from  before  backwards,  are  as 
46 


722 


THE  NERVOUS  SYSTEM 


follows:  fissura  longitudinalis  anterior,  sulcus  paraijyraiuidalis,  sulcus  lateralis  vcn- 
tralis,  sulcus  postolivaris,  sulcus  lateralis  dorsalis,  sulcus  paraiuedianus  dorsalis. 
fissura  longitudinalis  posterior.  As  will  be  seen  from  the  previous  descrii)tion, 
however,  this  summary  applies  only  to  the  ujjper  or  i)roximal  part  of  the  medulla; 
in  the  distal  part  the  fissures  become  reduced  in  numl)er  owing  to  some  of  them 
becoming  confluent  with  others.  Certain  of  the  above-mentioned  fissures  divide 
the  medulla  into  columns  or  areas  corresponding,  for  tlie  most  part,  to  the  columns 
of  the  cord.  Thus  we  have  an  anterior  area  between  the  anterior  fissure  and  the 
sulcus  lateralis  ventralis,  a  lateral  area  between  the  last-named  fissure  and  the 
sulcus  lateralis  dorsalis,  and  a  pt>sterior  area  between  the  sulcus  lateralis  dorsalis 
and  tlie  j)osti'rior  fissure. 

The  anterior  area  of  the  medulla  is  t)ccui)ied,  for  the  greater  part  of  its  extent, 
by  the  pyramidal  bodies.  These  are  a  pair  of  ])rominences  somewhat  pyriform 
in  outline,  which  lie  on  each  side  of  the  anterior  median  fissure.  Tlieir  larger  ends 
are  directed  upwards  and  abut  against  the  pons  where  they  become  slightly  con- 
stricted.    Laterally,   they  are  marked  off  by  the  sulci   parapyramidales.     Their 


Fig.  429. — Transverse  Section  through  the  Upper  Part  of  the  Pons.     (Schwalbe.) 

VALVE  OF  VIElSSEyS  LiyOULA 


DESCENDING  ROOT  OF 
TRIGEMINAL 


FOI'RTH 
VENTRICLE 


RAPHE 


FILLET 


SUPERIOR  PEDUNCLE 
OF  CEREBELLUM 


POSTERIOR  LONGI- 
TUDINAL BUNDLE 


FORMA  TIO 

RETICULARIS 
TRA CT  OF 

FILLET 


TRIG  EMI  N.\  L 
NER  VE 


BUNDLES  OF 
THE  PYRAMIDS 


TRANSVERSE  FIBRES  OF  PONS 


apices  are  directed  downwards  and  correspond  to  the  decussation  of  the  pyran)ids. 
The  greater  number  of  the  fibres  pass  across  at  this  point  and  make  their  way  into 
the  lat(iral  column  of  the  opposite  side  of  the  cord  (lateral  j>yramidal  tract);  a  small 
bundle,  however,  of  the  outermost  fibres  of  each  pyramid  runs  downwards  in  the 
anterior  column  of  the  cord  of  the  same  side  (anterior  pyramidal  tract). 

The  remainder  of  the  anterior  column  is  occupied  ])y  the  funiculus  anterior. 
This  is  a  triangular  area  of  white  substance  which  intervenes  betwet'ii  the  sulcus 
parapyramidalis  and  the  sulcus  lateralis  ventralis.  Its  l)aseis  directed  downwards, 
and  is  continuous  with  the  anterior  ground  bundle  of  the  anterior  cohmm  of  the 
cord.  Its  apex,  directed  upwards,  is  wedged  in  between  the  olivary  and  pyramidal 
bodices.  The  progressive  diminution  of  the  tract  when  traced  upwards  is  owing  to 
its  fibres  receding  from  the  surface,  being  overlapped  by  the  pyramidal  body. 

The  lateral  area  of  the  medulla  is  narrow  below,  being  formed  by  the  continua- 
tion of  a  j)ortion  only  of  the  lateral  colunm  of  the  cord.  Higher  up  it  ex])ands 
and  jiresents:  {a)  The  olivary  body  and  (b)  the  tubercle  of  Rolando.  The  lateral 
column  is  a  band  which  passes  uj)wards  between  the  sulcus  lateralis  ventralis  and 
the  sulcus  lateralis  dorsalis.      Above,  it  passes  behind  the  lower  })art  of  the  olivary 


METEXCEPHALOX  723 

bo.]}',  and  liere  a  greyish  ])r()inineiice,  the  grey  tubercle  of  Rolando,  conies  to  the 
surface.  Beyond  this  the  lateral  colunni  can  he  toilowed  as  a  narrow  hand  hehind 
the  olive  as  far  as  the  transverse  groove  at  the  lower  border  of  the  jions.  The 
olivary  body  is  an  ovoidal  prominence  from  twelve  to  sixteen  millimetres  long, 
which  extends  upwards  as  far  as  the  transverse  groove  at  the  lower  border  of  the 
pons.  It  is  separated  from  the  pyraniidal  Ijody  by  the  sulcus  lateralis  ventralis, 
and  marked  oflf  externally  l)y  the  sulcus  postolivaris.  Its  lower  end  is  crossed  l)y 
the  external  areiform  (il)res.  The  external  arciform  fibres  emerge  from  the 
anterior  longitudinal  fissure  and  from  the  sulcus  lateralis  ventralis,  and  arch 
round  the  pvramidal  and  olivary  l)odies  to  join  the  restiform  body  of  the  same 
side. 

The  posterior  area  of  the  medulla  is  occupied  in  its  lower  i)art  l)y  two  slender 
fasciculi,  each  of  whicli  cxjjands  al)()ve  into  a  tul»erclc.  The  inner  of  the  two  is 
call(Ml  the  funiculus  gracilis,  the  outer  the  funiculus  cuneatus.  The  funiculus 
gracilis  is  separated  from  its  fellow  of  the  opposite  side  by  the  ])osterior  fissure. 
As  it  approaches  the  lower  extremity  of  the  fourth  ventricle,  it  swells  out  into  a 
prominence  called  the  clava.  The  latter  diverges  from  its  fellow  of  the  opposite 
side,  bounding  the  fourth  ventricle.  When  traced  upwards  it  gradually  tapers  off 
into  a  fine  point.  To  the  inner  margins  of  the  diverging  portions  of  the  clava'  a\«' 
find  the  oliex  and  ligulae  attached,  as  already  described  (page  718).  The  funiculus 
cuneatus  is  placed  between  the  funiculus  last  described  and  the  lateral  area  of  the 
nieiluUa.  At  the  level  of  the  clava  it  swells  out  into  a  prominence,  the  cuneate 
tubercle.     Above  this  point  it  disappears  from  the  surface. 

The  upper  part  of  the  posterior  area  is  occupied  by  the  restiform  body.  The 
latter  a})})ears  at  first  sight  as  if  it  were  the  continuation  upwards  of  the  funiculus 
cuneatus  and  of  the  lateral  tract,  and  this  was  formerly  descrilied  to  be  the  case. 
It  is  now  known,  however,  that  it  is  formed  by  the  direct  cerebellar  tract  (page 
742),  the  external  arciform  fibres,  and  the  deep  or  internal  arciform  fibres. 
These  constituents  unite  and  form  a  rounded  cord  which  proceeds  upwards  and 
then  backwards  to  the  cerebellum,  forming  the  inferior  peduncle  of  that  body. 
In  its  lower  part  it  is  embraced  by  the  roots  of  the  auditory  nerve.  It  then  passes 
through  a  gap  or  interval  between  the  superior  and  middle  cerebellar  peduncles, 
and  ends  in  the  superior  vermiform  process  of  the  cereVjellum  in  the  nucleus  fastigii. 
It  is  connected  by  the  arcuate  fil)res  with  the  columns  of  GoU  and  Burdach,  partly 
by  uncrossed  and  partly  by  crossed  fibres.  The  uncrossed  fibres  have  been  shown 
to  take  a  larger  share  in  the  formation  of  the  restiform  body  than  the  crossed  fibres 
CDarkschewitsch  and  Freud).  The  crossed  fibres  all  reach  the  restiform  body  as 
arciform  fibres  ;  man}'  of  these  fibres  traverse  the  olivary  nucleus  but  without 
entering  into  connection  with  its  nerve-cells  (Edinger)  ;  they  also  traverse  the 
accessory  olives  and  may  pierce  the  ascending  root  of  the  trigeminal  nerve;  they  all 
decussate  at  the  raphe,  and  from  thence  proceed  in  two  grou])S,  superficial  and 
deep  arciform  fibres.  The  superficial  arciform  fibres  emerge  through  the 
anterior  fissure  of  the  medulla,  some  also  through  the  sulcus  i)aramedianus  ven- 
tralis, and  arch  round  the  pyramidal  body  and  olive  to  join  tlie  restiform  l)ody. 
In  this  part  of  their  course  tliey  pass  between  the  root-fibres  of  the  ninth,  tenth, 
eleventh,  and  twelfth  nerves.  The  deep  arciform  fibres,  after  crossing  in  the 
raphe,  traverse  the  olivary  nucleus  of  the  opposite  side,  and  pass  thence,  through 
the  su])stance  of  the  medulla,  into  the  restiform  body. 

The  olivary  body  also  sends  fibres  to  the  restiform  ])ody.  Fibres  ])assout  of  the 
hilum  and  cross  in  the  raphe;  they  then  traverse  the  olivary  l)ody  of  the  opposite 
side  and  join  the  restiform  body. 

As  already  mentioned,  the  superficial  origins  of  some  of  the  cranial  nerves  appear 
on  the  surface  of  the  medulla.  The  sixth,  seventh,  and  eighth  nerves  come  to  the  sur- 
face in  the  transverse  groove  l)etween  the  medulla  and  pons  (fig.  411 ).  The  twelfth 
nerve  appears  by  a  row  of  filaments  in  the  groove  between  the  olivary  and  pyra- 
midal bodies,  and  in  a  line  with  these  filaments,  opposite  the  decussation  of  the 
pyramids,  the  upper  part  of  the  anterior  root  of  the  first  cervical  nerve  comes  to 
the  surface.  Between  the  olivary  and  restiform  bodies,  the  ninth,  tenth,  and  the 
up])er  part  of  the  eleventh  nerves  make  their  appearance,  and  behind  the  latter  the 
upper  filaments  of  the  posterior  root  of  the  first  cervical  nerve  reach  the  surface. 


724 


THE  N^R VOL'S  SYSTEM 


Dissection.— If  the  student  has  fullowed  out  the  dissection  previously  reconiuiended,  the 
brain  will  now  he  rediieed  to  the  medulla,  the  pons,  the  mesencephalon,  and  small  portions  of  the 
liemispheres  (chietiy  thalamenceplialon).  He  should  now  tear  oft"  the  transverse  fibres  of  the 
pons  on  one  side  of  the  mid<lleline,  so  as  to  bring  into  view  the  flattened  bundles  which  Ibrm  the 
continuation  of  the  pyramidal  body  through  the  jions.  By  tearing  these  pyramidal  fibres  in  a 
sagittal  direction,  the  dissector  will  be  able  to  follow  them  through  the  crusta  into  the  inner  cap- 
sule. La.stly  the  dissector  should  make  a  series  of  transverse  sections  through  the  remaining  por- 
tion of  brain-substance.  An  inspection  of  figs.  423,  424,  429,  430,  and  431  will  materially  aid 
him  in  comprehending  the  somewhat  faint  indications  which  he  will  observe  in  his  sections. 

The  following  are  the  principal  jjoints  which  can  be  made  out  by  the  unaided  eye  in  an 
ordinary  brain,  hardened  in  spirit,  and  treated  iu  the  above-mentioned  manner.  (In  a  brain 
hardened  in  Miiller's  fluid  nnuiy  additional  details  can  be  made  out.)  In  the  uitiiermost  sections 
the  tegmental  or  red  nuck'us  is  readily  recognised  by  its  rounded  outline  ;  it  lies  below  the  optic 
thalamus,  and  extends  backwards  for  a  considerable  distance  (fig.  423).  If  the  section  pass  through 
the  external  geniculate  body,  curved  bands  of  white  matter  intersecting  the  grey  matter  can  be 
seen.  Sections  through  the  upper  part  of  the  mesencephalon  show  the  red  nucleus  in  the  teg- 
mentum, the  substantia  nigra,  the  crusta,  and  the  aqueduct  of  Sylvius.  Lower  down,  the  decus- 
sation of  the  superior  peduncles  of  the  cerebellum  forms  a  conspicuous  white  centre  in  the  teg- 
mentum ;  the  grey  matter  surrounding  the  aqueduct  is  distinct  in  colour  from  the  rest  of  the 
section,  and  on  the  ventral  side  of  this  grey  matter  the  posterior  longitudinal  bundle  can  be  faintly 
made  out.     Sections  through  the  inferior  corpora  quadrigemina  show  the  posterior  longitudinal 


Ficf.  430. — Transverse  Section  of  the  Pons  near  the  Centre  of  the  Foirtu 

Ventricle.     (Schwalbe. ) 


SEVESTH  NERVE 


NUCLEI'S  OF  SIXTH 


SEVENTH 
NEB  VE 

KA  I'HE 


NUCLEUS  OF  EIGHTH 


FORMA  TIO 
RETICULARIS 


NUCLEUS  OF 
SEVENTH 


ASCENDING 

ROOT  OF 

FIFTH 
AlI'irORY 

NERVE 
SUPERIOR 

OLIVE 


SIXTH  NERVE 


CONTINUA  TION  OF 
PYRAMIDS 


bundle  more  distinctly  ;  the  superior  peduncles  of  the  cerebellum  lie  on  the  ventral  side  of  the 
bundle,  touching  one  another  at  the  raphe,  but  commencing  to  rise  up  around  the  sides  of  the 
aqueduct ;  ventral  t(j  these  the  tract  of  the  fillet  may  be  seen  as  a  white  band  ;  and  ventrally  to 
the  fillet  the  longitudinal  fibres  of  the  pons  are  well  seen  intersecting  the  transverse  fibres. 
Sections  through  the  valve  of  Vieussens  (fig.  429)  show  the  su)>erior  peduncles  of  the  cerebellum 
in  the  form  of  distinct  white  crescents  placed  laterally  to  the  floor  of  the  fourth  ventricle.  The 
posterior  longitudinal  bundle  is  now  very  distinct.  It  appears  pear-shaped  in  cross-section  with 
the  narrow  end  jiointing  (jutwards  and  abutting  against  the  substantia  ferruginea  ;  the  latter  stands 
out  as  a  conspicuous  dark  spot.  The  tract  of  the  fillet  is  easily  recognised  as  a  white  flattened 
oval  bundle.  The  area  majiped  out  between  the  posterior  longitudinal  bundle,  the  sufjcrior 
])eduncles  of  the  cerebellum,  and  the  tract  of  the  fillet,  is  occupied  by  the  formatio  reticularis. 
In  sections  distal  to  this,  the  i>ost.erior  longitudinal  bundle  and  the  tract  of  the  fillet  rajndly  lose 
their  distinctness,  and  in  the  medulla  little  can  be  nnide  out  as  a  rule  excei)t  the  olivary  nucleus. 
The  latter  appears  as  a  thin  wavy  grey  line  occui)ying  the  interior  of  the  olivary  body. 

Internal  structure  of  the  medulla. — Transverse  sections  of  the  iiiedulla  show 
tliat  it  is  composed  of  syminctrical  halves  se])arated  by  a  central  ra])he.  Tlie  raplie 
is  entirely  formed  by  decussating  fibres.  Eacli  lateral  half  is  composed  of  both 
grey  and  \yhite  matter.  The  white  matter  will  be  dealt  with  in  common  with  the 
tracts  of  the  spinal  cord  and  with  the  cranial  nerves. 

The  arrangement  of  the  grey  matter  in  the  medulla  is,  for  the  most  part, 


METENCEPHAL  ON 


7'2d 


not  visil^le  to  the  unaided  eye,  and  therefore  will  be  dealt  with  very  l)riefly  here. 
It  is  usually  classified  into  two  categories:  (a)  Representatives  of  the  grey  crescents 
of  the  spinal  cord;  and  (6)  nuclei  or  aggregations  of  grey  matter  not  represented 
in  the  spinal  cord.  As  will  be  seen  on  consulting  the  section  on  the  Spinal  Cord, 
the  grey  matter  of  the  latter  consists  of  a  pair  of  bilaterally  symmetrical  grey  cres- 
cents which  are  united  in  the  middle  line  b}'  a  grey  commissure.  In  the  centre 
of  this  commissure  is  the  central  canal  of  the  cord.  The  central  canal  extends 
u])wards  into  the  lower  or  distal  part  of  the  medulla,  l)ut,  in  the  upper  part  of  the 
last-named  structure,  the  posterior  columns  diverge  from  one  another  so  that  th(^ 
central  canal  opens  out  and  expands  into  the  floor  of  the  fourth  ventricle.  There- 
fore the  ependyma  which  surrounds  the  central  canal,  together  with  the  grey 
masses  at  the  bases  of  both  anterior  and  posterior  horns,  is  spread  out  on  the  floor 


Fig.  481.— Transverse  Section  of  the  Medulla  a  little  above  the  Lower  Extremity 
OF  THE  Fourth  Ventricle.     (After  Krause.) 

FUNICUL  us  SOLITA  RIUS  NUCLE  CV  OF  A  UDITOR  Y 


yUCLEUS 
FUNICULI 
GRACILIS  ET 
CUNEA  TI 


SUBSTANTIA 

GEL  A  TINOSA 

ASCENDING 

ROOT  OF 

FIFTH 

VAGUS 

NUCLEUS 
LATERALIS 
VA  G  US 

EXTERNA  L 

ACCESSORY 
OLIVE 

ARCIFORM 
FIBRES 


OLIVARY 
NUCLEUS 


Nl  CLEUS  OF  VAGUS 


SULCUS  LONG I- 
TUDINALIS 
MELIUS 
NUCLEUS  OF 
HYPOGLOSSAL 


IIYPOGI0SS\L 


PYRAMIDAL  BODY 


INTERNA  L 
ACCESSORY 
OLIVE 


RAPHE 


FISSURA 
LONG  ITU DI- 
NALIS 
ANTERIOR 


of  the  fourth  ventricle.  From  the  nerve-cells  in  this  grey  matter  some  of  the 
cranial  nerves,  which  take  their  origin  in  the  medulla,  arise.  The  grey  matter 
of  the  base  of  the  anterior  horn  suffers  but  little  displacement,  and  lies  in  a 
column  on  each  side  of  the  sulcus  longitudinalis  medianus,  and  from  this  a 
motor  nerve  (the  twelfth)  arises.  The  sixth  nerve  arises  in  series  with  the  twelfth 
in  the  tegmental  region  of  the  pons,  and  the  nuclei  of  the  fourth  and  third 
nerves  continue  this  motor  column  of  cells  brainwards  in  the  floor  of  the  aqueduct 
of  Sylvius.  The  grey  matter  of  the  base  of  the  i)osterior  horn  is  displaced 
laterally,  so  that  it  underlies  the  surface  markings  which  have  been  described  above 
as  ala  cinerea  and  tuberculum  acusticum,  and  from  tliis  grey  matter  the  sensory 
parts  of  the  tenth  and  ninth  nerves  and  part  of  the  eighth  nerve  arise.  The  heads 
of  both  of  the  horns  of  the  grey  crescents  are  also  represented  in  the  medulla.     At 


'26 


THE  NERVOUS  SYSTEM 


the  decussation  of  the  jiyramids  (tig.  43S)  large  Imndles  of  tilires  pass  from  the 
lateral  columns  of  the  cord  to  cross  over  to  the  o])posite  side  and  ai)i)ear  in  the 
anterior  colunni  of  the  medulla,  forming  the  greater  part  of  the  pyramids.  These 
liundles  of  ti))res  cut  through  the  necks  of  the  anterior  horns  so  as  to  completely 
amputate  the  heads  of  the  horns.  A  little  higher  up  each  head  is  thrust  into  a 
more  lateral  position  by  the  increased  size  of  the  pyramids,  and  forms  the  nucleus 
lateralis  and  the  nucleus  ambiguus  (fig.  432).  The  motor  nuclei  of  the  portion  of 
the  eleventh  which  arises  in  the  medulla,  and  of  the  tenth  and  ninth  nerves,  are 
regarded  as  derivatives  from  the  head  of  the  anterior  horn,  and  the  series  is  con- 
tinued upwards  by  the  nucleus  of  the  seventh  (at  the  junction  of  the  pons  and 
medulla),  and  in  the  pons  by  the  motor  nucleus  of  the  trigeniinal.  A  little  above 
the  decussation  of  the  pyramids,  bundles  of  fibres,  chiefly  from  the  funiculi 
gracilis  and  cuneatus,  pass  forwards  and  cut  through  the  neck  of  the  posterior  horn, 
and  then  decussate,  forming  the  sensory  or  upper  pyramidal  decussation  (decus- 
satio  lemnisci).  The  separated  head  of  the  posterior  horn  (substantia  gelatinosa 
Rolandi)  is  continued  upwards  as  far  as  the  accessory  sensory  nucleus  of  the  fifth 
nerve.  This  sul)stantia  gelatinosa  is  one  of  the  sensory  nuclei  of  the  fifth  nerve, 
and  is  covered  externally  by  a  l)and  of  white  fibres,  concave  inwards,  the  ascend- 
ing root  of  the  trigeminal  nerve  (fig.  432).  At  one  point  the  substantia  gelatinosa 
approaches  very  near  the  surface,  and  forms  the  grey  tubercle  of  Rolando. 


Fig.  432. 


-Transverse  .Sectiox  of  the  Medulla  ix  thk  Region'  of  the  Decissatio 
Lemxisci.     (Sfhwalbe.) 


FcyiorLi's  crxEATrs 

XrCLEl'S  OF  THE  CLA  VA 
EXTERXAL  CCXEATE  XCCLEfS 

CUXEATE  XUCLEiS 
ASCEXDIXG  ROOT  OF 


TRIGEMIXAL  /  (  f' 

'AXTIA   GELATIXOSA  ■   I  '    ':'" 


SrSSTA 


FORMATIO  RETICULARIS 
XrCLEUS  LATERALIS 


OLIVARY  XL' CLE  US 

SUPERFICIAL  ARCIFORM 
FIBRES 
ARCIFORM  XUCLEUS 


FUXICULUS  GRACILIS 
POSTERIOR  FISSURE 


XUCLEUS  OF  SPIXAL 

A  CCESSOR  Y 

—  CEXTRAL  CAXAL 

—  XUCLEUS  OF  HYPOGLOSSAL 

—  DECUSSA  TIO  LEMXISCI 


ACCESSORY  OLIVARY 
XUCLEUS 


I'-f AXTERIOR  FISSU 


RE 


SUPERFICIAL  ARCIFORM 
FIBRES 


Of  the  nuclei  which  are  apparently  without  representatives  in  the  grey  matter 
of  the  spinal  cord,  the  most  important  is  the  olivary  nucleus  ;  this  is  a  crumpled 
bag  of  grey  matter  enclosing  white  matter  and  occupying  the  interior  of  the  olivary 
l)ody.  It  can  easily  be  seen  with  the  unaided  eye  in  cross-sections  of  the  medulla. 
It  presents  a  marked  resemblance,  in  miniature,  to  the  corpus  dentatum  of  the 
cerebellum,  and  is  often  called  the  corpus  dentatum  of  the  olivary  body.  It 
|)resents  an  opening  or  hilum  which  opens  downwards  and  inwards.  The  nucleus 
of  the  clava  and  the  nucleus  cuneatus  are  not  directly  represented  in  the  cord, 
but  their  connection  with  the  posterior  horns  can  be  seen  in  sections  through  the 
lower  part  of  the  medulla;  the}'  have  prol»al)ly  the  same  anatomical  value  as  a 
eolunin  of  nerve-cells  (Clarke's  column)  in  the  dorsal  region  of  the  s])inal  cord 
( Testut).  Other  nuclei  of  smaller  size  are  found  in  the  medulla;  the  nucleus  arci- 
formis  and  the  accessory  olives  will  serve  as  examples  of  these  (fig.  432).  None  of 
these  smaller  nuclei  are  visil)le  to  the  unaided  eve. 


Specific  Gravity  and   Weight  of  the  Brain 

The  white  matter  is  soiut-wliat  more 


The  average  specific  gravity  of  the  brain  is  about  1036 
heavy  (sp.  gr.  1040)  than  the  grey  matter  (sp.  gr.  1034). 


THE  BRAIX  AXD    THE   WALL,^   OE  THE  CRAMAL   rAVETY     727 

The  adult  male  brain  weiKlis  on  an  average  49 '5  ounces;  the  female  brain  is  somewhat 
lighter,  and  weighs  from  5  to  5 '5  ounces  less  than  the  male. 

The  cerebrum  forms  about  87'5  i)er  cent,  of  the  entire  brain  ;  the  cereVjellum  about  10'5  per 
cent. ;  and  the  pons  and  medulla  about  2  per  cent. 

Weight  (if  the  Spinal  Cord 

In  the  adult,  the  spinal  cord,  when  all  extraneous  structures  have  been  removed,  weighs  from 
1  to  1  5  ounce-s. 


For  description  of  C'ranio-eerebral  Topography  see  Section  X. 


THE  RELATIONS  OF  THE  BRAIX  TO  THE  WALLS  OF  THE 
CRAXIAL  CAVITY 

In  this  section  the  suliject  of  cranio-cerebral  topography  will  be  dealt  with  from 
a  purely  anatomical  standpoint,  for  the  precise  methods  by  which  the  exact  posi- 
tions of  the  more  important  fissures,  sulci,  convolutions,  and  areas  can  be  ascer- 
tained and  mapped  out  on  the  surface  of  the  head  in  the  living  subject  are  fully 
(lescribed  in  Section  X.  whilst  here  only  a  very  general  survey  of  the  relations  of 
the  brain  to  the  cranial  bones  will  be  given. 

The  parts  of  the  V)rain  which  lie  in  close  relation  Avith  the  walls  of  the  cranial 
cavity  are  the  olfactory  bulb  and  tract,  the  inferior  and  outer  surfaces  of  the  cerebral 
hemispheres,  the  lower  surfaces  of  the  lateral  lobes  of  the  cerebellum,  the  anterior 
surfaces  of  the  medulla  and  pons,  and  the  pituitary  body. 

Certain  of  these  portions  of  the  brain  lie  in  relation  wdththe  basi-cranial  axis, — 
that  is,  with  the  basi-occipital,  the  basi-sphenoid,  and  the  ethmoid  bones, — whilst 
others  are  separated  by  the  membranes  only  from  the  sides  and  vault  of  the  cranial 
space.  Considering  the  former  portions  first,  the  anterior  surface  of  the  medulla 
oblongata,  which  is  formed  by  the  anterior  pyramids,  lies,  posteriorly,  ujion  the 
u|)per  surface  of  the  basi-occipital  bone.  More  anteriorly  the  anterior  surface  of 
the  pons  rests  upon  the  basi-sphenoid,  from  which  it  is  partly  separated  by  the 
basilar  artery  and  the  sixth  pair  of  cranial  nerves.  In  front  of  the  dorsum  sellse 
the  pituitary  body  is  lodged  in  the  pituitary  fossa;  still  further  forwards  the  olfactory 
tracts  lie  in  grooves  on  the  upper  surface  of  the  presphenoid  section  of  the  sphe- 
noid bone;  and  in  front  of  the  sphenoid  the  olfactory  bull)s  rest  upon  the  cribriform 
plates  of  the  ethmoid. 

Behind  and  laterally  to  the  posterior  part  of  the  foramen  magnum  the  lateral  lobes 
of  the  cerebellum  are  in  relation  with  the  cranial  wall,  resting  upon  the  lower  parts 
of  the  supra-  and  the  posterior  parts  of  the  ex-occipital  i>ortions  of  the  occipital 
bone,  whilst,  anteriorly,  each  is  in  relation  with  the  inner  surface  of  the  mastoid  pro- 
cess and  the  posterior  surface  of  tlie  petrous  portion  of  the  temporal  bone.  The 
area  of  the  skull  wall  which  is  in  close  relationship  with  the  cerebellar  hemispheres 
may  be  indicated,  on  the  external  surface  of  the  skull.  l»y  a  line  which  commences 
from  the  lower  part  of  the  external  occipital  protuberance;  thence  it  runs  upAvards 
and  outwards.  It  crosses  the  superior  curved  line  a  little  beyond  its  centre,  and, 
continuing  in  the  same  direction,  it  crosses  the  lower  part  of  the  lambdoid  suture 
and  reaches  a  point  directly  above  the  asterion  (the  meeting-] )oint  of  the  occipital, 
temporal,  and  j)arietal  bones),  Avhence  it  descends,  just  in  front  of  the  occipito- 
mastoid suture,  to  the  tip  of  the  mastoid  process;  there  it  turns  inwards  to  its  ter- 
mination at  the  margin  of  the  foramen  magnum,  immediately  behind  tlie  posterior 
end  of  the  occipital  condyle. 

The  other  portions  of  the  brain  which  lie  in  close  relation  with  the  cranial  walls 
are  the  lower  and  external  surfaces  of  the  cerebral  hemis})heres. 

The  lower  surface  of  each  cerebral  hemisphere  consists  of  two  parts,  an  anterior 
and  a  posterior,  Avhich  are  separated  by  the  stem  of  the  Sylvian  fissure.  The 
anterior  part,  formed  bA'the  orbital  surface  of  the  frontal  lobe,  rests  upon  the  upper 


728  THE   XERVOrS  SYSTEM 

surfact'S  of  the  orbital  plate  of  the  frontal  lioneand  the  small  wing-  of  the  sphenoid; 
it  is  therefore  in  close  relation  with  the  upper  wall  of  the  or))ital  cavity.  The  pos- 
terior part,  behind  the  Sylvian  fissure,  is  formed  by  the  anterior-  portion  of  the 
temporal  lobe,  including  its  apex.  The  apex  itself  projects  against  the  orbital 
plate  of  the  great  wing  of  the  sphenoid  bone,  and  it  is  in  relationship  with  the 
posterior  part  of  the  outer  wall  of  the  orbit.  The  lower  surface  of  the  hemisphere, 
behind  the  apex  of  the  temporal  lobe,  is  in  contact  with  the  upper  surfaces  of  the 
great  wing  of  the  si)henoid  and  the  petrous  part  of  the  temporal  l)one. 

The  external  surfaces  of  the  cerebral  hemisplieres  have  the  most  extensive  rela- 
tionshii)s  with  the  cranial  wall,  and  it  is  more  especially  to  these  surfaces  that  the 
practical  surgeon  turns  his  attention.  The  general  area  in  which  the  outer  surface 
of  each  cerebral  hemisphere  is  in  relation  with  the  skull  bones  is  readily  indicated 
by  a  series  of  lines  wdiich  correspond  Avith  the  positions  of  its  supraciliary,  the 
infero-lateral,  and  the  supero-mesial  liorders. 

The  line  marking  the  supraciliary  margin  of  the  hemisphere  commences  at  the 
nasion  (the  mid-point  of  the  fronto-nasal  suture);  it  passes  outwards  above  the 
su]:)raciliary  ridge,  crosses  the  temporal  ridge,  then,  turning  backwards  in  the 
tem})oral  fossa,  it  reaches  the  parieto-sphenoidal  suture,  along  which  it  continues 
V)ack wards  to  its  posterior  extremity. 

The  line  n;iarking  out  the  infero-lateral  l)order  conunences  at  tlie  posterior  end 
of  the  parieto-sphenoidal  suture,  whence  it  passes  downwards,  in  front  of  the 
spheno-squamous  suture,  to  the  pterygoid  ridge  (infra-temporal  crest) ;  there  it 
turns  l^ackwards;  running  parallel  with  and  internal  to  the  zygomatic  arch,  it 
crosses  the  root  of  the  zygoma,  and  ascending  slightly  it  passes  above  the  external 
auditory  meatus;  continuing  backwards  with  an  inclination  upwards  it  reaches  a 
]M_)int  innnediately  above  the  asterion;  thence  it  descends,  and,  crossing  the  lower 
2)art  of  the  lambdoid  suture  and  the  superior  curved  line,  it  passes  inwards  to  the 
lower  part  of  the  external  occii)ital  protu Iterance. 

The  supero-mesial  1)order  is  defined  b}'  a  line  which  rims  from  the  nasion  to  the 
inion;  this  line  should  be  drawn  about  5  mm.  to  the  outer  side  of  the  sagittal 
suture,  because  the  mesial  area  is  occupied  by  the  superior  longitudinal  sinus,  and 
it  should  be  further  away  from  the  middle  line  on  the  right  than  on  the  left  side 
because  the  sinus  tends  to  lie  more  to  the  right  side. 

The  area  of  the  skull  wall  enclosed  by  the  three  linQS  which  mark  the  positions 
of  the  supraciliary,  infero-lateral,  and  the  supero-mesial  borders  of  the  cerebral 
hemisphere  is  formed  by  the  vertical  plate  of  the  frontal  Ijone,  the  parietal  bone, 
the  great  wing  of  the  sphenoid,  the  squamous  part  of  the  temporal,  and  the  ui)per 
section  of  the  supra-occipital  segment  of  tlie  occipital  bone;  it  covers  the  outer  sur- 
faces of  the  frontal,  parietal,  temj^oral,  and  occipital  lobes  and  the  fissures  and 
sulci  which  ])ound  and  mark  them. 

The  frontal  bone  covers  the  superior,  middle,  and  inferior  frontal  convolutions, 
except  their  posterior  extremities,  which  are  beneath  the  parietal  bone  (fig.  483). 
The  ascending  limb  of  the  fissure  of  Sylvius,  which  cuts  into  the  posterior  part  of 
the  inferior  frontal  convolution,  runs  ]iarallel  with  and  undercover  of  the  lower  part 
of  the  coronal  suture  or  innnediately  in  front  of  it,  and  the  anterior  horizontal  limb 
is  parallel  with  and  beneath  the  up])er  margin  of  the  great  wing  of  the  sphenoid. 
The  parietal  ])one  is  in  relation  with  the  outer  surfaces  of  four  lobes  of  the  l)i'ain. 
Speaking  very  generally,  it  may  l)e  said  that  the  anterior  third  covers  the  posterior 
part  of  the  frontal  lobe,  including  the  ascending  frontal  convolution  and  the  i)os- 
terior  ends  of  the  superior,  middle,  and  inferior  frontal  convolutions  and  the  u])])er 
and  lower  precentral  sulci,  whilst  the  posterior  two-thirds  are  superficial  to  the 
j>arietal  lobe,  the  posterior  part  of  the  temporal  lobe,  the  anterior  part  of  the  t)cci- 
l)ital  lobe,  the  posterior  part  of  the  horizontal  liml)  of  the  Sylvian  fissure,  tlieu]>])<'r 
and  lower  ])Ost-central  sulci,  the  intraparietal  sulcus,  the  })osterior  sections  of  the 
first  and  second  tem])oral  sulci,  and  the  external  ]iarieto-occipital  fissure.  The 
fissure  of  Rolando  is  beneath  the  ])ariet;d  l)one  at  the  junction  of  its  middle  and 
anterior  thirds  (fig.  483). 

The  upper  end  of  the  fissure  of  Rolando  lies  55  ]ier  cent,  of  the  whole  length  of 
the  naso-inionic  line  behind  the  nasion;  it  is  55  mm.  from  the  coronal  suture  in 
dolichocephalic,  and   54-4  nun.   in  brachycephalic  heads.     The  lower  end  of  the 


THE  BRAIN  AND   THE   WALLS  OF  THE  CRANIAL   CAVITY     729 

fissure  is  iimnediately  above  the  posterior  horizontal  limb  of  the  fissure  of  Sylvius; 
it  Hes  beneath  the  point  of  intersection  of  the  auriculo-bregniatic  line  with  a  line 
drawn  from  the  stephanion  (the  point  where  the  temp{jral  ridge  cuts  the  coronal 
suture)  to  the  asterion  (Macalister).  In  skulls  of  a  sagittal  length  of  18  cm.  and 
over  this  i)()int  is  45-5  per  cent,  of  the  horizontal  arc  from  the  glabella  to  tlie  inion. 
and  in  skulls  of  less  than  18  cm.  it  is  46  per  cent,  of  the  same  arc  posterior  to  the 
glabella. 

The  i)<)siti()n  of  the  posterior  horizontal  limb  of  the  fissure  of  Sylvius  varies;  its 
posterior  part  is  always  under  cover  of  the  parietal  bone  and  it  terminates  either  in 
front  of  or  below  the  parietal  eminence,  but  the  anterior  part  may  be  above, 
l)eneath,  or  below  the  squamo-parietal  suture.  In  the  adult  the  anterior  part  of 
the  fissure  runs  upwards  and  backwards  from  the  posterior  end  of  the  spheno- 


FiG.  433. — Drawing  of  a  Cast  of  the  Head  of  an  Adult  Male. 
(Prepared  by  Professor  Cunningham  to  illustrate  cranio-cerebral  topography.) 


POSITION  OF 
FRONTAL  EMINENCE 


FISSrjlE  OF 
STL  vies 


MIDDLE 

TEMPORAL 

FISSURE 


l)arietal  suture  along  the  anterior  part  of  the  squamo-i)arietal  suture  to  its  highest 
point;  thence  it  continues  in  the  same  direction  beneath  the  parietal  bone  towards 
the  laml)da,  terminating  either  in  front  of  or  below  tlie  parietal  eminence.  In  the 
child,  however,  the  fissure  is  considera])ly  above  the  line  of  the  squamo-parietal 
suture  (fig.  434),  which  it  gradually  approaches,  attaining  its  adult  position  about 
the  ninth  year;  this  cliange  of  position,  which  occurs  during  the  first  nine  years,  is 
•  Kie  i)artly  to  the  ascent  of  the  sutural  line  and  partly  to  the  descent  of  the  fissure 
on  the  surface  of  tlie  l)rain. 

The  upi)er  end  of  the  external  parieto-occipital  fissure  usually  lies  about  5  nun. 
in  front  of  the  lambda,  and  the  course  of  the  fissure  may  be  indicated  liy  a  line 
drawn  from  5  mm.  in  front  of  the  lambda  to  a  point"^  immediately  above  the 
asterion.  and.  as  the  latter  point  corresponds  with  the   i)re-occipital  notch  on,  the 


730 


THE  NERVOUS  SYSTEM 


infero-lateral  border  of  the  hemisphere,  the  hue  in  question  aviII  nidieate  the  adja- 
cent margins  of  the  parietal,  temporal,  and  occipital  lobes  of  the  brain. 

The  occipital  bone  is  in  close  relation  with  the  cerebellum,  as  already  pointed 
out  but  it  also  covers  the  posterior  part  of  the  outer  surface  of  the  occipital  lobe  of 
the'cerebrum  The  great  wing  of  the  sphenoid  covers  the  outer  surface  of  the  apex 
of  the  temporal  lobe,  and  the  squamous  part  of  the  temporal  bone  covers  the 
anterior  parts  of  the  superior,  middle,  and  inferior  temporal  convolutions  and  the 

sulci  which  separate  them.  ,  .     ,     ^     .  .    ,  ^     ^  i   ,• 

In  every  consideration  of  the  topographical  relations  of  the  cerebral  convokitions 
to  the  walls  of  the  cranial  cavity  it  must  be  borne  in  mind  that  the  conditions  are 


Fig.  434.— Drawixg  of  a  Cast  of  the  Head  of  a  Newly-born  Male  Infant. 
(Prepared  by  Professor  Cunningham  to  illustrate  cranio  cerebral  topography.) 


EXTERNAL 
PARIETO- 
OCCIPITAL 
FISSURE 


FISSURE  OF 
ROLANDO 


POSITION  OF  PARIETAL 

EMINENCE 
POSITION  OF  FRONTAL 

EMINENCE 

FISSURE  OF 

SYLVIUS 

PARALLEL 

FISSURE 


not  constant,  and  that,  therefore,  the  relations  are  variable.  The  three  main  factors 
upon  which  this  varial)ility  depends  are  age,  sex,  and  the  shape  of  the  skull.  As 
examples  of  the  variations  which  occur  it  maybe  mentioned  that  the  fissure  of 
Sylvius  is  higher  in  the  child  than  in  the  adult  (compare  figs.  433  and  434).  The 
upper  end  of  the  fissure  of  Rolando  is  further  away  from  the  coronal  suture  in 
the  female  and  the  child  than  in  the  adult  male,  and  in  dolichocephalic  than  in 
brachycephalic  heads.  The  angle  formed  betAveen  the  line  of  the  fissure  of  Rolando 
and  the  mid-sagittal  plane,  which  averages  about  69°  in  the  adult,  is  niore  acute 
in  dolichocephalic  heads,  and  the  external  parieto- occipital  fissure  is  further 
forwards  in  the  cliild,  and  possibly  in  the  female,  than  it  is  in  the  adult  male. 


THE  SPINAL   CORD 


731 


THE  SPINAL  CORD 

The  spinal  cord  is  the  elongated  portion  of  the  cerebro-spinal  axis  which  is 
contained  within  the  spinal  canal.  It  extends  from  the  level  of  the  transverse 
ligament  of  the  atlas  to  the  ))ody  of  the  second  lumbar  vertel)ra.  Occasionally  it 
only  extends  as  far  as  the  body  of  the  first  lumbar  vertebra.  It  is  invested,  in 
common  with  the  brain,  by  three  membranes:  dura  mater,  arachnoid,  and  pia 
mater.  The  portions  of  these  membranes  which  are  contained  within  the  cranial 
cavity,  and  are  therefore  in  relation  to  the  l^rain,  have  been  already  described  (page 
671).  There  are,  however,  certain  differences  betAveen  the  cranial  and  the  spinal 
meninges;  therefore,  a  short  separate  description  of  the  latter  will  be  necessary. 

Dissection. — The  subject  being  i)laeed  on  its  face,  the  neural  canal  may  be  laid  open  in  the  usual 
manner  by  cutting  through  the  pedicles  of  the  vertebrae  and  removing  the  neural  arches  of  the 
saciTim.  The  cord  and  its  membranes  should  be  first  examined  in  situ.  About  three  inches  of 
the  theca  should  be  ripped  U])  at  the  junction  of  the  dorsal  and  lumbar  regions  for  this  purpose. 
The  entire  cord  with  the  membranes  should  then  be  removed  by  dividing  both  cord  and  mem- 
branes at  the  level  of  the  articulation  between  the  atlas  and  axis  and  cutting  through  the  nerves 


Fig.  435. — Transverse  Section  of  the  Spinal  Cord  and  its  Membranes. 
(After  Key  and  Retzius.) 


SUBARAfUyoiD  SPACE 


A y  TERIOR  XER I  E-R 00 TS 
(in  stctiun) 


Ligamentum  denticulatum 


Dura  mater  - 


SlBARACJ/yOW 
TRABECl  LA    WITH 
BVyULES  OF  POSTERIOR 
XERVE-ROOTS 

Septum  poBticum 


as  they  enter  the  intervertebral  foramina.  Two  or  three  of  the  lower  lumbar  or  upper  sacral  neives 
should  be  cut  sufficiently  long  to  preserve  the  ganglia  on  the  posterior  roots.  The  cord  should 
now  be  pinned  out  with  its  posterior  surface  uppermost  in  a  cork-lined  tray  and  dissected  under 
water.  On  laying  open  the  dura  mater  by  a  mesial  longitudinal  incision,  the  arachnoid  will  come 
into  view  and  will  be  rendered  more  evident  ]jy  blowing  air  between  it  and  the  pia  mater  with  a 
blow])ipe.  On  slitting  up  the  arachnoid  some  of  the  coarser  strands  of  the  subarachnoid  tissue 
may  be  made  out.  The  posterior  and  anterior  nerve-roots  will  also  be  seen  with  the  ligamentum 
denticulatum  between  them.  The  connection  of  the  latter  with  the  pia  mater  is  well  seen  under 
water.  The  pia  mater  appears  white  and  glistening,  and  when  traced  downwards  is  verj- 
obviously  C(jntinuous  with  the  filum  terminale.  The  last-named  stiTicture  stands  out  conspicuously 
am(jng  the  duller-coloured  nerve-roots  which  constitute  the  eauda  equina.  On  the  anterior  asjject 
of  the  cord  the  linea  splendens  will  be  seen.  Lastly  the  student  should  make  a  series  of  trans- 
verse sections  through  the  cord  and  compare  the  disposition  of  the  grey  and  white  matter  in  the 
different  regions  (fig.  439). 

The  DURA  MATER  forms  a  loose  sheath  or  theca  around  the  cord.  It  invests 
not  only  the  cord  but  also  the  elongated  nerve-roots,  which  (under  the  name  of  cauda 
equina)  extend  beyond  the  cord.  It  invests  the  cauda  equina  as  far  as  the  second 
or  third  sacral  vertebra,  but  at  this  level  it  converges  so  as  to  form  a  blunt  hollow 
cone,  and  is  represented  lower  down  only  by  the  sheath  of  the  filum  terminale.  By 
means  of  this  sheath  it  is  attached  to  the  base  of  the  coccyx.     Its  outer  surface  is 


7:^0 


THE  SERVO  US  SYSTEM 


rougli  and  is  loosely  connected  by  fatty  tissue  to  the  ligaments  and  ])eriosteum 
which  line  the  neural  canal.  Some  stronger  retinacula  connect  it  to  the  posterior 
common  ligament.  Its  inner  surface,  smooth  and  shining,  is  separated  from  the 
arachnoid  by  a  narrow  subdural  space.  It  is  connected  to  the  cord  by  a  special 
develo])ment  of  the  pia  mater — the  ligamentum  denticulatum.  It  is  continuous 
through  the  foramen  magnum  with  the  supporting  layer  of  the  dura  mater  of  the 
l)rain.  It  sends  tul)ular  prolongations  around  the  spinal  nerves.  These  prolonga- 
tions gradually  merge  into  the  connective  tissue  sheaths  (epineurium)  of  the  nerves. 
Each  tube  is  divided  by  a  septum  into  two  compartments,  one  for  the  anterior,  and 
one  for  the  jtosterior  root  of  the  spinal  nerve. 

The  differences  Ijetween  the  dura  mater  of  the  brain  and  cord  may  be 
sunnnarised  as  follows: — The  dura  mater  of  the  cord  does  not  send  processes  or 
infoldings  into  the  fissures  of  the  cord.  It  represents  only  the  supporting  layer 
of  the  dura  mater  of  the  brain.  The  periosteal  layer  is  represented  by  the  periosteum 
of  the  neural  canal,  but  is  separated  from  the  supporting  layer  bj''  fatty  tissue, 
and  by  some  venous  plexuses.     Hence  this  periosteum  is  only  brought  into  relation 


Fig.  436. — View  of  the  Membranes  of  the  Spinal  Cord.     (Ellis.) 


Dura  mater 


POSTERIOR  ROOT 
ANTERIOR  ROOT 

liigamentum  denticulatum 
Linea  splendens 


witli  the  dura  mater  i)roper  by  the  fact,  already  noticed  (page  672),  that  the  dura 
mater  of  the  cranium  is  directly  continuous  Ijy  the  medium  of  the  posterior 
occipito-axial  ligament  with  the  periosteum  of  the  neural  canal. 

The  ARACHNOID  is  separated  from  the  dura  mater  by  a  narrow  subdural  space, 
and  is  comiected  to  the  dura  mater  only  opposite  the  attachments  of  the  ligamentum 
denticulatum,  to  be  presently  described.  It  is  a  thin  membrane  resembling  the 
cere])ral  arachnoid,  with  which  it  is  continuous.  It  sends  tubular  investments 
along  the  nerve-roots.  These  investments  eventually  become  continuous  with  the 
perineural  sheaths  of  the  nerves.  It  extends  downwards  within  the  thcca  as  far  as 
the  second  or  third  sacral  vertebra,  forming  a  common  investment  to  the  bundle  of 
nerve-roots  constituting  the  cauda  equina. 

The  subarachnoid  tissue  is  nnich  less  ainnidant  in  the  spinal  ])orti(in  than  in 
the  cerel)ral  part  of  the  sul)arachiioid  space.  It  ])asses  from  arachnoid  to  i»ia  mater 
in  the  form  of  delicate  threads,  which  are  separated  from  one  another  by  compara- 
tively wide  intervals.  It  also  gives  sujiport  to  the  nerve-roots  as  they  cross  the 
subarachnoid  s])ace  (fig.  435).  An  incomplete  membranous  septum,  the  septum 
posticum    (  Key  and  Retzius),   passes  from  arachnoid  to  pia  mater  opposite  the 


MENINGES  OF  THE  SPINAL  CORD 


733 


posterior  septum  of  tlie  spinal  cord,  and  serves  to  conduct  blood-vessels  to  the  cord. 
The  space  is  also  partially  divided  into  a  posterior  and  an  anterior  compartment 
by  the  ligamentum  denticulatum. 

The  PIA  MATER  of  the  cord  consists  of  two  layers,  an  outer  and  an  inner,  the 
latter  of  which  represents,  and  is  continuous  with,  the  pia  mater  of  tlie  brain. 
Both  layers  dip  into  the  anterior  fissure  of  the  cord,  and  the  inner  layer  is 
continuous  with  the  posterior  septum.      The  outer  layer  is  strong  and  fibrous,   and 

Fig.  437. — Posterior  View  of  the  Medulla  Oblongata  and  of  the  Spinal  Cord,  with 
ITS  Coverings  and  the  Roots  of  the  Nerves.     (Hirschfeld  and  Leveille.) 


MIDDLE 

PEDUNCLE        ( 
ISFERIOR 
I'EDVSCLE 

CLA  VA 

C.  I. 

II. 


SUPERIOR  PEDUNCLE 
OF  THE  CEREBELLUM 
SULCUS  LONGITUDI- 

XALIS  MEDIUS 
GLOSSO-PHARYNGEAL       x. 
VAGUS 


SPINA  L  A  CCESSOR  Y 


Ligamentum 
denticulatum 

POSTERIOR 
LONGITUDINAL 
FISSURE 


AN  ANTERIOR  ROOT 
A  POSTERIOR  ROOT 


XL 


NIL- 


L.  /.- 


llr 


IIL  — < 


/I-.— C 


CONUS 
MEDUL- 
LARIS 


FILUM  TER- 
MINALE 
SUR- 
ROUNDED 
BY  CAUDA 
EQUINA 


GANGLION 
ON  A 

/'OSTERIOR 
ROOT 


presents  certain  localised  thickenings  which  require  separate  description;  these  are 
the  ligamentum  denticulatum  and  the  linea  splendens.  The  filum  terminale  may 
be  conveniently  described  along  with  these. 

The  ligamentum  denticulatum  is  a  fibrous  band  which  is  attached  on  each 
side  of  the  cord  about  midway  Ijetween  the  anterior  and  posterior  nerve-roots.  It 
is  continuous  by  its  inner  margin  with  the  pia  mater.  Its  outer  margin  is  charac- 
teristically scalloped  or  denticulated,  and  presents  about  twenty-one  pointed  pro- 
cesses by  which  it  is  attached  to  tlie  dura  mater.     These  processes  do  not  pierce  the 


734  THE  NERVOUS  SYSTEM 

araclmoid,  Init  receive  funnel-shajx'd  sheatlis  from  it  (Key  and  Retzius).  The 
highest  of  these  processes  is  at  the  level  of  the  foramen  magnum,  and  is  placed 
between  the  hypoglossal  nerve  and  the  vertebral  artery.  In  the  upper  region  of 
the  cord  one  denticulation  is  regularly  placed  between  the  point  of  exit  of  each 
nerve  and  the  next  nerve  below;  lower  down  the  arrangement  becomes  less  regular. 
It  is  continuous  below  with  the  filum  terminale.  The  linea  splendens  (Haller) 
is  a  conspicuous  linear  thickening  which  is  placed  in  the  middle  line  in  front  of  the 
cord.  It  })resents  a  silvery  white  appearance.  It  is  continuous  below  with  the 
filum  terminale.  The  filum  terminale  is  the  continuation  of  the  pia-matral  sheath 
of  the  cord,  and  contains  l)ut  little  nervous  matter  in  its  interior.  It  is  easily 
distinguished  by  its  shining  Avhite  appearance  from  the  nerve-roots  among  which  it 
lies.  It  is  a  slender  strand  which  extends  from  the  pointed  lower  extremity  of  the 
spinal  cord  to  the  lower  end  of  the  sacrum,  or  first  piece  of  the  coccyx,  opposite 
which  it  is  attached  to  the  bone.  As  already  mentioned,  it  receives  a  sheath  from 
the  dura  mater  in  the  lower  part  of  its  course. 


EXTERNAL  CHARACTERS  OF  THE  SPINAL  CORD 

The  spinal  cord  is  about  eighteen  inches  in  length,  and  forms  (l>y  weight)  about 
two  per  cent,  of  the  cerebro-spinal  axis.  It  is  cylindrical  in  form,  and  is  slightly 
compressed  from  before  backwards,  so  that  the  transverse  exceeds  the  antero- 
posterior diameter.  It  is  continuous  with  the  medulla  oblongata  above  at  tlie 
decussation  of  the  pyramids;  below  it  tapers  off  into  a  cone,  the  conus  medul- 
laris,  the  apex  of  which  is  continued  dowuAvards  by  the  filum  terminale.  It 
follows  the  curvatures  of  the  canal  in  which  it  is  placed,  and  therefore  describes 
two  curves,  the  upper  or  cervical  convex  forwards,  and  the  lower  or  dorsal  concave 
forwards. 

In  two  regions  of  the  cord  distinct  enlargements  are  visible:  these  are  called 
the  cervical  and  the  luml^ar  enlargements.  The  large  size  of  the  nerves  Avhich  are 
given  off  to  supply  the  limbs,  forming  the  brachial  and  lumbo-sacral  plexuses, 
obviously  account  for  these  enlargements  of  the  cord.  The  increase  in  size  is 
almost  entirely  produced  by  an  increase  in  the  transverse  diameter.  The  cervical 
enlargement  is  more  pronounced  than  the  lumbar  swelling.  It  commences  at 
the  level  of  the  third  cervical  vertebra,  and  ends  at  the  second  dorsal.  It  is  at  its 
maximum  at  the  level  of  the  sixth  cervical  vertebra.  The  lumbar  enlargement 
commences  at  the  level  of  the  ninth  dorsal  vertebra,  and  reaches  its  maximum 
at  the  twelfth  dorsal;  below  this  point  it  rajiidly  diminishes  and  passes  into  the 
conus  medullaris. 

The  spinal  cord  is  bilaterally  symmetrical,  the  two  halves  being  defined  by  an 
anterior  fissure  and  a  posterior  septum.  From  the  antero-lateral  and  postero- 
lateral aspects  of  the  cord  the  anterior  and  posterior  nerve-roots  emerge,  forming 
two  parallel  series  of  fasciculi  which  extend  throughout  the  entire  length  of  the 
cord.  In  the  upper  cervical  region  the  intrathecal  course  of  the  nerve-roots  is  very 
short,  and  the  direction  taken  by  the  roots  is  nearly  transverse.  As  the  roots  are 
traced  downwards  in  the  dorsal  and  lumbar  regions,  they  become  progressively 
longer,  and  descend  with  an  increasing  degree  of  obliquity.  Hence  the  lumbar  and 
sacral  nerve-roots  have  a  very  long  intrathecal  course.  They  extend  beyond  the 
tern)ination  of  the  cord  (which,  it  will  be  remembered,  ends  at  the  body  of  the 
second  lumbar  verteln-a),  and  lie  within  the  theea  in  a  sheaf  somewhat  resembling 
a  horse's  tail,  and  therefore  called  the  cauda  equina. 

The  cord  is  divided  into  definite  macroscopical  areas  l:>y  one  fissure,  two  sulci, 
three  septa,  and  the  exits  of  the  anterior  nerve-roots. 

The  fissure. — The  anterior  fissure  separates  the  cord  into  two  lateral  areas 
anteriorly  (fig.  439).  It  is  relatively  wide  and  extends  from  the  surface  to  the 
anterior  white  commissure,  attaining  a  depth  equal  to  about  one-third  the  antero- 
posterior diameter  of  the  cord.  It  contains  a  fold  of  pia  mater  and  l)ranehes  of  the 
anterior  spinal  vessels.  It  is  continued  above  along  the  anterior  surface  of  the 
medulla,  being  partially  interrupted  by  the  decussation  of  the  pyramids,  and  it 
terminates  at  the  foramen  caecum  just  below  the  pons  (fig.  441). 


THE  SPINAL  CORD 


735 


Fig.  438.— Anterior  axd  Posterior  View  of  the  Spixal  Cord. 
(Modified  from  Quain.) 

X  represents  the  filum  termiuale. 


CLA  VA 
FUNICUL  US  CUNEA  TUS 


POSTERIOR 

LONGITUDINAL- 
FISSURE 


POSTERO-LA  TERAL  \- 
GROOVE 


POSTERO-LA  TERAL  -f 
GROOVE 


POSTERIOR 
LONGITUDINAL 
FISSURE 


OLIVARY  BODY 
LA  TERA  L  COL  UMN 
DECUSSATION  OF  PYRAMIDS 

ANTERIOR  LONGITUDINAL  FISSURE 


SECTION  OF  MEDULLA 


ANTERO-LA TERAL  GROOVE 


ANTERIOR  LONGITUDINAL  FISSURE 


736 


THE  XERVOUS  SYSTEM 


The  two  sulci  are  placed  dorso-laterally  (tig.  438)  and  the  posterior  nerve-roots 
emerge  from  them.  They  serve  to  divide  each  half  of  the  cord  into  a  posterior 
and  an  anterp-lateral  area  or  column  (fig,  439). 

The  anterior  nerve-roots  emerge  from  the  antero-lateral  aspects  of  the  cord,  not 
from  grooves  or  sulci,  but  in  a  relatively  scattered  manner.  They  divide  the  antero- 
lateral (tolunms  into  anterior  and  lateral  i)ortions  (fig.  439). 

The  three  septa  lie  in  the  dorsal  part  of  the  cord;  they  are  a  median  and  two 


Fiu.  439. — Sections  through  Different  Regions  of  the  Spinal  Cord. 

(After  Sfhvvalbe.) 

POSTERIOR  ROOTS 


AXTERIOR  ROOTS 


I '(IS  TEi:  I  ( >  i:  FISS I  RE 


A.  At  the  level  of  the  sixth  cervical 
nerve-roots. 


ASTER  J  OR  FISSURE 


B.   At  the  mid-dor.sal  resiou. 


CESTRAL  CAXAL 


C.   At  the  centre  of  the  luiuhiir  eu- 
largement. 


TV    At  the  u)»per  part  ot    the    coniis 
nieduHaris. 


E.   At  the  level   of  the  tifth  sacral 
nerve-roots. 


F.  At   the   level    of   the    coccygeal 
nerve  roots. 


lateral.  The  postero-median  septum  extends  throughout  the  whole  length  of  the 
cord,  separating  it  into  lateral  halves  dorsally  (tig.  439).  It  consists  of  neuroglial 
tissue  containing  branches  of  the  posterior  spinal  vessels,  and  it  passes  from 
the  pia  mater  to  the  posterior,  or  grey,  commissure.  The  postero-lateral  septa 
are  only  seen  in  the  dorsal  and  cervical  regions.  They  extend  from  the  pia 
mater  into  the  posterior  column,  dividing  it  into  })ostero-median  and  jiostero- 
lat<M-al  parts. 


THE  SPJXAL  CORD  737 


INTERNAL  STRUCTURE  OF  THE  SPINAL  CORD 

In  transverse  section,  each  lateral  half  of  the  cord  is  seen  to  be  composed  of 
!)oth  grey  and  white  matter,  the  latter  being  disposed  on  the  surface.  The  grey 
matter  is  in  the  form  of  a  crescent,  which  has  been  not  inaptly  compared  (by  Testut) 
to  a  large  comma  (  *  ).  The  head  of  the  comma  looks  forwards  and  constitutes  the 
anterior  horn  of  grey  matter;  the  tail  forms  the  posterior  horn,  and  the  convexity 
looks  inwards  and  is  united  to  the  grey  crescent  of  the  opposite  side  by  the  grey 
commissure.  The  two  crescents,  with  the  commissure,  form  a  figure  resembling  a 
capital  H.  Within  the  grey  commissure  is  the  central  canal  of  the  cord,  and  in 
front  of  the  grey  commissure,  occup3ang  the  floor  of  the  anterior  longitudinal 
fissure,  is  the  anterior  white  commissure.  Medullated  fibres  cross  the  middle  line 
both  in  the  white  and  in  the  grey  commissure.  The  term  commissure  is  somewhat 
misleading,  as  the  majority  of  the  nerve-fibres  which  pass  from  side  to  side  are  not 
commissural  l:)ut  decussating  fiV>res. 

The  grey  matter  of  the  cord  consists  of  two  varieties:  (a)  Substantia  gelatinosa, 
and  (6)  substantia  spongiosa.  The  former  (a)  covers  the  head  of  the  posterior 
horn  like  a  cap  fsubstantia  gelatinosa  Rolandi ),  and  is  also  foimd  around  the 
central  canal  (substantia  gelatinosa  centralis  ).  The  latter  is  continued  into  the 
ependyma  of  the  cerebral  ventricles,  (b)  The  substantia  spongiosa  is  much  more 
extensive  than  the  substantia  gelatinosa,  and  contains  large  nerve-cells.  Tliese 
cells  are  arranged  in  definite  groups,  forming  columns  in  the  grey  matter. 

The  cell  columns  in  the  anterior  cornua  are  arranged  as  follows: 


i   Dorso-niesial. 
1 
Mesial  (fig.  440  A;.    I 


These  colunms  are  the  most 
constant  in  all  situations, 
and  are  Ijelieved  to  supply 


[  Ventro-mesial.  [      the  spinal  muscles. 

Best   marked   o})j)osite   the 


r  Dorso-lateral.  \       limb  nerves  to  which  they 

T           1  ,^      .  ./v  A      !  ^      ^ive  origin. 

Lateral  (fig.  440  A),  j  ^  In    cervical     region,    gives 

I  ,.           ,          ,  i-ateral.        -j^       origin  to  spinal  accessory. 

\entro-lateral.  -,       ^^.^^^           ^  j^^    ^^^^     ^,^^.^^^     ^-^ 

I-  t.      origin  to  phrenic  nerve. 

The  cells  of  the  posterior  cornu. — The  cells  of  the  ])osterior  cornu  are  less 
regular  tlian  those  of  the  anterior  cornu  in  arrangement,  but  several  groups  are 
describi^l.  They  are  (1)  peripheral  cells,  some  of  which  possess  long,  curved  j)ro- 
cesses,  and  hence  are  called  coinet  cells;  (2)  central  cells;  (3)  basal  cells;  (4)  the 
cells  of  the  substantia  gelatinosa;  and  (5)  solitary  cells,  which  are  scattered  irreg- 
ularly and  which  vary  in  size.  The  protoplasmic  or  dendritic  processes  of  the  cells 
of  the  })Osterior  cornu  permeate  the  gray  matter  of  the  cornu;  their  axis-cylinder 
processes  or  axons  run  in  various  directions,  and  their  terminations  are  for  the  most 
])art  unknown;  some  of  them,  however,  pass  to  the  anterior  cornu  and  to  the 
anterior  connnissure,  and  these  are  believed  to  issue  from  the  cord  as  the  snudl 
fibres  of  till'  anterior  nerve-roots. 

Clarke's  column  of  cells  (fig.  440  A). — This  column  of  cells  lies  at  the  Itase  of 
the  posterior  cornu  internally.  It  consists  of  large  ovoid  cells  whose  long  axes  are 
parallel  with  the  axis  of  the  cord.  The  column  is  limited  to  the  dorsal  region, 
but  cells  of  similar  nature,  occupying  a  similar  position,  are  found  in  the  lumbar 
region  of  the  cord  opposite  the  second  and  third  sacral  nerves,  where  they  foim 
Stilling' s  nucleus.  Others  are  recognisable  in  the  cervical  region,  and  they  are 
probably  represented  in  the  medulla  by  the  cells  of  the  nucleus  gracilis  and  the 
nucleus  cuneatus.  Many  of  the  axons  of  the  cells  of  this  column  pass  upwards  to 
tlie  cerebellum  in  the  dorso-lateral  ascending  cerebellar  tract,  and  some  are  probal'ly 
distriV)uted.  as  anabolic  or  inhibitory  nerves,  to  the  blood-vessels,  glands,  and  to 
the  walls  of  tli<'  aliineiitarv  canal. 

The  intermedio-lateral  tract. — Tlie  intermedio-lateral  tract  or  column  of 
47 


738  THE  NERVOUS  SYSTEM 

nerve-cells  lies  at  the  base  of  the  anterior  cornu  externally;  it  is  limited  to  the 
dorsal  region,  but  cells  occupying  relatively  similar  positions  are  found  in  the 
cervical  and  luml)ar  regions  also.  The  axons  of  its  cells  probably  constitute  the 
katalwlic  or  motor  nerve-tibres  of  the  muscles  of  the  glandular  and  vascular 
systems. 

A  middle  column  of  cells  can  be  recognised  in  the  centre  of  the  grey  matter 
at  the  junction  of  the  anterior  and  posterior  cornua.  It  is  more  or  less  distinct 
throughout  the  whole  length  of  the  cord,  and  its  function  is  unknown. 

The  term  processus  reticularis  is  applied  to  a  number  of  strands  of  grey 
matter  which  project  into  the  white  matter  and  anastomose  together  on  the  outer 
side  of  the  base  of  the  posterior  cornu. 

The  central  canal  of  the  cord  is  lined  by  columnar  epithelium;  it  is  continued 
into  the  tilum  terminale  for  aljout  half  the  length  of  the  latter,  and  is  here  some- 
Avhat  dilated;  a  few  nerve-tibres  accompany  the  canal  into  the  filum  terminale,  and 
are  supposed  to  be  rudimentary  coccygeal  nerves.  The  canal  is  dilated  in  the 
conus  medullaris.  forming  an  irregular  cavity,  the  sinus  rhomboidalis  inferior, 
or  ventriculus  terminalis. 

lu  transverse  sections  through  the  spinal  cord  made  in  the  dissecting  room  the  general 
arrangement  of  the  grey  and  white  matter  can  be  made  out,  and  sections  from  the  different 
regions  of  the  cord  can  be  distinguished  from  one  another  in  fresh  specimens,  especiallj'  with  the 
aid  of  a  pocket  lens. 

In  the  upper  cervical  region  (at  the  level  of  the  second  or  third  cervical  nerves)  the  grey 
matter  forms  an  H-shaped  outline  bearing  a  great  resemblance  to  the  outline  in  the  dorsal  region 
(fig.  439,  B).  Sections  through  this  region  are  very  difficult  to  distinguish  from  sections  of  the 
dorsal  cord  with  the  naked  eye.  The  microscope,  however,  reveals  the  absence  of  Clarke's 
column  and  the  presence,  in  some  cases,  of  root-fibres  of  the  spinal  accessory  nerve. 

In  the  lower  ceiTical  region  (fig.  439,  A)  the  cord  is  elliptical  in  outline  and  the  anterior 
horns  of  the  grey  crescents  are  very  large  ;  the  section  shows  a  certain  similaritj'  to  a  section 
through  the  lumbar  region  (fig.  439,  C).  In  the  latter,  however,  the  anterior  horns  are  more 
evenly  rounded,  the  general  outline  approaches  more  nearly  to  a  circle,  and  the  proportion  of 
grey  to  white  matter  has  gi'eatly  increased. 

Sections  of  the  dorsal  region  can  be  easily  recognised  with  the  microscope  by  the  presence  of 
Clarke's  column,  which  is  confined  to  the  dorsal,  lowest  part  of  the  cervical,  and  the  uppermost 
part  of  the  lumbar  regions. 

Sections  through  the  part  of  the  cord  from  which  the  sacral  nerves  arise  show  a  great  jjre- 
ponderance  of  grey  matter.  This  feature  becomes  more  marked  as  the  termination  of  the  cord  is 
approached  (fig.  439,  D,  E,  and  F). 


THE    DEEP    CONNECTIONS   AND   ASSOCIATIONS   OF   THE    SPINAL 

NERVES 

But  little  information  can  be  gained  from  a  mere  macroscopical  or  microscopical 
examination  of  the  adult  cord  concerning  the  course  of  the  fibres  of  the  nerve-roots 
within  it,  and  the  facts  detailed  here  have  been  chiefly  ascertained  by  embry ©logical 
and  i)athol()gical  research.  The  success  of  the  embryological  method  depends 
upon  the  fact  tliat  certain  tracts  or  groups  of  fibres  myelinate  (or  acc[uire  their 
medullary  shi'ath)  at  an  earlier  period  than  others,  and  therefore  these  tracts  of 
nicdullated  lilires  can  be  followed  and  recognised  through  a  series  of  sections.  The 
pathological  method  rests  upon  the  influence  Avhich  nerve-cells  exert  upon  nerve- 
tilires;  this  so-called  trophic  influence  depends  upon  the  fact  that  every  nerve-fibre 
is  a  ])rocess  of  a  nerve-cell  and  can  only  exist  and  retain  its  functions  as  long  as  it 
remains  connected  with  the  cell.  The  trophic  cell,  therefore,  of  every  nerve-fibre 
is  that  cell  from  which  the  fibre  arises  and  with  which  it  is  in  direct  structural  con- 
tinuity. If  the  trophic  cell  is  destroyed  the  nerve-fil)re  dies,  or  if  the  structural 
continuity  of  the  cell  and  fibre  is  interrupted  l)y  section,  then  the  fibre  degenerates 
and  dies  beyond  the  point  of  interruption,  and  the  degeneration  and  death  occur 
sinudtaneously  throughout  tlie  whole  length  of  the  separated  portion.  In  connec- 
tion also  with  the  tro})hic  infiucnce  of  nerve-cells  it  must  be  borne  in  mind  that 
every  nerve-cell  with  its  processes  constitutes  a  distinct  entity,  called  a  neuron, 
which  has  close  associative  relations  with  other  nerve-cells  and  with  various  tissues 
of  the  body  by  means  of  its  processes,  but  it  is  absolutely  devoid  of  structural 


SPINAL  NERVES 


739 


Fig.   440.— Diagram  showing  Paths  Traversed  by  Sensory  and  Motor   Nerve-fibres 
AND  their  Course  to  and  from  the  Cortex  of  the  Brain. 

(Sensory  fibres  blue  ;  motor  fibres  red.) 


LENTICULAR  SUCLEUS 


CA  UDA  TE  NUCLEUS 


INTERNAL  CAPSULE 


OPTIC  THALAMUS 


FORMA  TIO 
RETICULARIS 


TRAPEZIUM  — 
PYRAMIDAL  FIBRES 


SUPERIOR  PYRAMIDAL 

DECUSSA  TION 


ANTERIOR  PYRAMID 


TEGMENTUM 

CRUS  CEREBRI 
CRUSTA 


PONS 


NUCLEUS  GRACILIS 
NUCLEUS  CUNEA  TUS 


MEDULLA 


POSTERIOR  PYRAMID 

POSTERIOR  CORNU 

DECUSSATION  OF  PYRAMIDS 

ANTERIOR  CORNU 

ANTERIOR  PYRAMID 


SPINAL  CORD 


LOWER  PART  OF  MEDULLA 


POSTERIOR  NERVE-ROOT 

SPINAL  GANGLION  CELLS 

PERIPHERAL  END- 
ORGAN 
DIRECT  CEREBEL- 
LAR TRACT 

CROSSED  PYRAMI- 
DAL TRACT 
PERIPHERAL  END- 
ORGAN 

A  NTERO-LA  TERA  J. 
A SCENDING  TRA L '  T 


MUSCLE 


MUSCLE 


740  THE  yERVOUS  SYSTEM 

continuity  with  them.  The  centre  of  tlie  neuron  is  the  body  of  the  celL  The  pro- 
cesses of  the  neuron  form  two  sets,  the  jirotoplasmic,  (.lendritic  or  afferent,  and  the 
axis-cylinder  process,  which  is  termed  the  axon  or  efferent  process.  The  dendritic 
I)r(^cesses  of  the  neurons  of  the  brain  and  s})inal  cord  are  usually  short,  relatively 
numerous,  and  profusely  branched,  but  the  dendritic  or  afferent  process  of  a  spinal 
ganglion  cell  frequently  runs  a  long  distance  before  dividing  into  its  terminal  rami- 
tications.  The  terminal  filaments  of  the  dendrites  may  be  associated  either  with 
the  arborisations  of  the  axons  and  dendrites  of  other  cells  or  with  specialised  end 
organs.  The  axons  may  be  short  or  long;  those  of  the  cord  and  l)rain  terminate 
either  in  ramifications  round  other  nerve-cells  or  in  association  Avith  special  end 
organs.  The  axons  of  the  spinal  ganglia  enter  the  cord  and  divide  into  an 
ascending  and  a  descending  branch,  both  of  which  give  off  numerous  collaterals, 
and  they  terminate  in  ramifications  around  other  nerve-cells. 

The  knowledge  of  the  above  facts,  and  the  careful  study  of  the  degenerations 
resulting  from  the  section  of  nerve-roots  and  the  destruction  of  nerve-cells,  com- 
bined with  repeated  observations  on  the  })henomena  observable  during  the 
development  of  the  nerve-roots  and  the  spinal  cord,  have  led  to  the  forma- 
tion of  the  following  conclusions  concerning  the  deep  connections  of  the  spinal 
nerve- roots. 

The  anterior  roots. — The  majority  of  the  fibres  in  the  anterior  nerve-roots  are 
axons  of  the  cells  of  the  anterior  cornua,  but  some  of  the  smaller  fibres  are  derived 
from  the  cells  of  the  posterior  cornua,  and  from  the  cells  of  Clarke's  colunm  and 
the  intermedio-lateral  tract,  whilst  others  which  pass  to  the  roots  from  the  white 
columns  are  believed  to  be  processes  of  some  of  the  nerve-cells  of  the  cerebellum; 
therefore  if  the  nerve-cells  in  the  regions  mentioned  are  destroyed,  or  if  the  anterior 
nerve-roots  are  divided  beyond  their  exits  from  the  cord,  the  nerve-fibres  which 
form  them  degenerate  to  their  peripheral  terminations. 

The  posterior  roots. — The  fibres  of  the  posterior  nerve-roots  are  processes  of 
the  cells  in  the  posterior  root  ganglia.  The  fibres  in  each  root  external  to  the 
ganglion  are  the  afferent  or  dendritic  processes,  and  the  fibres  in  the  internal  por- 
tion of  the  root  are  the  axons  or  efferent  processes,  which  pass  into  the  cord;  there- 
fore if  the  posterior  nerve-root  is  divided  external  to  the  ganglion  the  peripheral 
portion  undergoes  degeneration,  but  if  the  division  is  made  internal  to  the  ganglion 
tiien  the  central  part  degenerates  and  the  positions  of  its  fibres  in  the  substance  of 
the  cord  become  recognisable. 

Two  groups  of  fibres  are  distinguishable  in  each  posterior  root  as  it  enters  the 
cord,  an  outer  or  lateral  group  of  small  fibres,  and  an  inner  group  of  large  fibres 
intermixed  with  some  small  fibres.  The  filjres  of  the  outer  group  enter  the  cord  over 
the  apex  of  the  posterior  cornu  and  turning  upwards  they  form  a  small  column  called 
the  marginal  bundle  or  Lissauer's  column  (fig.  440a),  inw^hich  they  run  for  a  short 
distance  l)efore  entering  the  substantia  gclatinosa  Rolandi.  The  inner  group  passes 
into  the  outer  part  of  the  posterior  column,  and  it  is  i>ossible  that  some  of  its  fibres 
terminate  in  Clarke's  colunm,  but  the  majority,  if  not  all,  divide  into  two  branches, 
one  of  wdiich  passes  upwards  and  the  other  downwards;  both  the  main  fil»re  and  its 
two  ternnnal  Ijranches  give  off  numerous  collateral  branches  which  enter  the  grey 
matter  and  ramify  round  the  cells  of  Clarke's  column  and  the  cells  of  the  posterior 
and  anterior  cornua  of  the  same  side,  and  some  pass  through  the  grey  conmiissure 
to  the  grey  matter  of  the  opposite  side.  The  terminations  of  the  descending 
branches  of  the  posterior  root-fibres  are  not  definitely  known,  but  they  are  believed 
to  be  in  the  grey  matter  of  the  lower  segments  of  the  cord.  The  ascending  liranches 
j)ass  upwards  to  the  medulla,  gradually  nearing  the  }K)stero-ni(^dian  septum  as  they 
ascend,  and  they  terminate  in  arliorisations  round  the  cells  of  the  nucleus  gracilis 
and  the  nucleus  cuneatus  in  the  medulla  o])longata. 

Tracts  of  the  spinal  cord. — The  fibres  which  form  the  white  colunms  of  the 
spinal  cord  ar(^  the  axons  of  nerve-cells  of  the  cord,  brain,  or  ganglia,  which  are 
passing  upwards  or  downwards  in  the  cord  to  terminate  at  a  higher  or  lower  level; 
the  former  are  called  ascending  fibres,  the  latter  descending,  and  the  degenerations 
which  occur  in  them  are  termed  ascending  and  descending  degenerations  respec- 
tively. 

Both  the  ascending  and  descending  fibres  are  groujH'd  in  tracts,  but  it  must  be 


SPIXAL   NERVES  741 

clearly  undcrstuod  that  these  tracts  or  columns  are  onl}-  recognisable  during  their 
development  or  when  affected  with  disease  or  degeneration. 

The  following  tracts  are  recognised  in  the  posterior  colunms: — 


Ascendino-    I  '^'^^^  postero-lateral,  or  Burdach's  column. 
®     1  The  i^ostero-mesial,  or  GoU's  colunm. 

Descending  |  The  comma-shaped  tract. 


(fig.  440  A). 


The  two  ascending  columns  are  not  distinguishable  from  each  other  below  the 
mid-dorsal  region,  but  above  that  level  they  are  partially  separated  by  a  sejjtum  of 
neuroglia  called  the  postero-lateral  septum.  The  fibres  of  Goll's  column  are  small 
and  those  of  Burdach's  column  are  large,  but  both  are  derived  from  the  posterior 
nerve-roots,  and  as  they  pass  upwards  they  give  off  collaterals  which  enter  the  grey 
matter. 

Home  of  the  fibres  of  the  posterior  ascending  cohmms  terminate  in  arborisations 
round  the  cells  of  the  grey  matter  of  the  cord,  but  others  pass  U})wards  to  the 
medulla  ol)longata,  where  the  fibres  of  Goll's  column  ramify  round  the  cells  of  the 
nucleus  gracilis,  and  the  fibres  of  Burdach's  column  arborise  round  the  cells  of 
the  nucleus  cuneatus. 

The  descending  or  comma-shaped  tract  is  small,  often  ill-defined,  and  it 
lies  in  the  midst  of  the  postero-lateral  ascending  tract.  It  consists  of  fibres  from 
the  posterior  roots  which  are  passing  downwards  to  lower  segments  of  the  cord. 

The  tracts  which  have  been  defined  in  the  antero-lateral  colunm  are  the 
following: — 

{Crossed  pyramidal. 
Direct  pyramidal. 
Antero-lateral  descending  cerebellar. 

■   (fig.  440  A). 

!Dorso-lateral,  or  direct  cerebellar. 
Antero-lateral  ascending  cerebellar. 
Lissauer's  column,  or  the  marginal  bundle. 
Antero-lateral  ground  Ijundle. 

The  descending  tracts  of  the  antero-lateral  column. — The  crossed 
pyramidal  tract  is  a  somewliat  triangular  Inmdle  of  nerve-fibres  lying  in  tlic 
dorsal  part  of  the  antero-lateral  column,  in  front  of  and  somcAvhat  external  to  the 
posterior  cornu.  It  is  separated  from  the  surface,  except  in  the  lower  pait  of  its 
extent,  by  the  direct  cerebellar  tract  (fig.  440a).  Its  fibres  are  the  axons  of  nerve- 
cells  in  the  cortex  of  the  opposite  side  of  the  brain;  they  pass  downwards  througli 
the  corona  radiata,  the  internal  capsule,  the  crura  cereliri,  the  pyramidal  l)imdles 
<^f  the  anterior  pyramid  of  the  medulla  to  the  decussation  of  the  ])vramids;  there 
they  cross  the  middk'  line  and  continue  their  descent  in  the  o])]iosite  antero-lateral 
column;  finally  they  leave  the  antero-lateral  colunm  and  pass  into  the  substance  of 
the  anterior  cornu,  where  thev  terminate  in  ramifications  round  the  motor  cells 
(fig.  440a). 

The  direct  pyramidal  tract  is  a  small  quadrilateral  bundle  of  nerve-fibres 
situated  at  the  side  of  the  anterior  fissure.  It  cannot  be  traced  downwards  beyond 
the  mid-dorsal  region.  Its  fibres  are  the  axons  of  the  nerve-cells  of  the  brain 
cortex  of  the  same  side,  which  have  taken  the  course  descril)ed  in  connection  Avith 
the  crossed  pyranndal  fibres  as  far  as  the  medulla;  then,  instead  of  crossing  to  the 
opposite  side,  they  have  descended  in  tlie  anterior  column  of  the  same  side;  ulti- 
mately, however,  they  reach  the  o])})osite  side  by  passing  through  the  anterior 
white  commissure,  and  they  terminate  in  ramifications  round  the  motor  cells  of  the 
anterior  cornu. 

The  descending  antero-lateral  column  is  situated  peripherally.  It  extends 
forwards  from  the  crossed  pyramidal  and  direct  cerebellar  tracts  to  the  base  of  the 
direct  ]iyramidal  tract,  but  it  is  broader  dorsally  than  ventrally,  and  its  fibres  nro 
more   or  less  mixed  with  those  of   the   antero-lateral  ascending  cerebellar   tract 


742 


THE  XERVOUS  SYSTEM 


(fig.  440a).  Its  fibres  are  processes  of  nerve-eells  situated  in  tlie  veniuform 
process  and  the  lateral  lobe  of  the  cerel)ellunr,  they  descend  to  the  cord  through 
the  middle  peduncle  of  the  cerebellum,  and  througln  the  restiform  body. 

The  ascending  tracts  of  the  antero-lateral  column. — The  dorso-lateral 
or  direct  cerebellar  tract  occujnes  the  tlorsal  i)art  of  tlie  periphery  of  the  cord  on 
the  outer  side  of  the  crossed  pyramidal  tract,  extending  from  the  tip  of  the  posterior 
cornu  to  the  antero-lateral  ascending  and  descending  tracts  (fig.  440a).  It  separates 
tlie  crossed  pyramidal  tract  from  the  surface,  except  in  the  lower  dorsal  region, 
where  the  pyramidal  fibres  intervene  l)etween  it  and  Lissauer's  column.  Its  fibres 
are  processes  of  some  of  the  cells  of  Clarke's  colunm,  and  they  terminate  in  rami- 
fications in  the  cerebellum,  to  which  they  jtass  by  the  restiform  body. 

The  antero-lateral  ascending  cerebellar  tract  occupies  an  area  in  front 
of  the  crossed  pyramidal  tract  extending  forwards  to  the  region  of  tlie  anterior 
nerve-roots.     Its'  fibres  are  mingled  with  those  of  the  descending  antero-lateral  tract, 


Fig.  440a.— Diagram  of  the  Tracts  of  the  Spinal  Cord  and  of  the  Deep  Oricuxs  ok 

THE  Spixal  Nerves. 


BURDACWS  COL. 


SOLITARY  CELLS 


CLARKE'S  COL. 
GOLL'S  COMMA 
COL.      TRACT 


POSTERIOR 
ROOT 


POSTERIOR 
ROOT 
GANGLION 


LISSA  UER'S  COL. 
DIRECT  CERE- 
BELLAR TRACT 

DIRECT  PY- 
RAMIDAL TRACT 

DESCENDING 
ANTERO- 
LATERAL 
CEREBELLAR 
TRACT  {red) 

ASCENDING 
ANTERO- 
LATERAL 
CEREBELLAR 
TRACT  {blue) 


ANTERIOR  NERVE- 
ROOT 


CENTRAL  CELL 
GROUP 


MESIAL  CELL  GROUP 
ANTERIOR  COMMISSURE 
DIRECT  PYRAMIDAL  TRACT 


but  they  have  a  more  limited  anterior  extension  and  they  occupy  a  broader  area 
posteriorly;  they  are  processes  of  nerve-cells  of  the  cord  and  possibly  of  the  cells  of 
the  posterior  cornu.  They  pass  upwards  through  the  reticular  formation  of  the 
medulla  and  pons;  some  reach  the  cerebellum  by  the  superior  peduncle  and  others 
join  the  fillet. 

Lissauer's  column  is  a  small  Inmdle  of  small  fibres  situated  at  the  a})ex  of 
the  posterior  cornu  dorsal  to  the  crossed  iiyramidal  and  direct  cerebellar  tracts.  It 
consists  of  the  small  fibres  from  the  lateral  parts  of  tlie  posterior  nerve-roots  which 
are  passing  upwards  to  terminate  in  the  grey  matter  of  higher  segments  of  the 
cord. 

The  antero-lateral  ground  bundle  embraces  the  anterior  cornu  and  the  outer 
side  of  the  l)ase  of  the  jiosterior  cornu  (fig.  440a);  it  represents  all  the  antero-lateral 
column  not  included  in  the  previously  mentioned  tracts,  and  it  consists  of  ascend- 
ing and  descending  commissural  fibres  passing  between  different  segments  of  the 
cord. 


CRAM  A  L   XERVES  743 


THE  PERIPHERAL  NERVOUS   SYSTE3I 

The  cerebru-spinal  nerves,  together  witli  tlie  end-organs  of  these  nerves,  the 
syiiipatlietic  system  and  the  gangha  whieh  are  eonneeted  to  both  the  eerebro-spinal 
and  the  symi)athetic  nerves,  make  up  tlie  ])eripheral  nervous  system.  The  cerebro- 
spinal nerves  are  mvariably  paired,  and,  with  a  few  exceptions  (notably  the  vagus), 
are  synnnetrical  in  their  origin,  course,  and  distribution  on  the  two  sides  of  the  body. 
The  cranial  nerves  arise  directly  from  the  brain  and  pass  out  from  the  skull  through 
foramina  in  the  cranial  wall.  The  spinal  nerves  arise  by  anterior  and  posterior 
roots  from  the  spinal  cord,  and  leave  the  spinal  canal  by  passing  through  the  inter- 
vertebral foramina.  The  first  spinal  nerve  is  somewhat  exceptional,  as  its  origin 
is  partly  from  tlie  medulla,  and,  moreover,  it  leaves  the  spinal  canal  by  passing 
between  the  occipital  bone  and  the  atlas. 


THE  CRANIAL  NERVES 

The  cranial  nerves  are  classified  into  nine  pairs  by  Willis,  and  into  twelve 
j)airs  by  Soemmerring.  AMllis's  classification  depends  upon  the  manner  in  which 
the  nerves  pierce  the  dura  mater;  for  example,  the  glosso-pharyngeal,  vagus,  and 
spinal  accessory  nerves  all  pierce  that  membrane  opposite  the  jugular  foramen, 
lience  they  collectively  form  a  cranial  nerve  (the  eighth)  of  "Willis.  In  Soemmer- 
ring's  classification  each  nerve-trunk  is  considered  separately.  AMllis' s  classification 
was  formerly  in  use;  it  is  now,  however,  generally  discarded  in  favor  of  Soemmer- 
ring's  classification.     The  latter  Avill  be  followed  in  this  work. 

The  following  table  will  explain  the  relation  of  "Willis's  to  Soemmerring's 
classification: — 

Willis  Soemmerring  Xanies 

First  pair  of  nerves  First  pair  of  nerves  Olfactory 

Second         ,,  Second  .,  Optic 

Third  .,  Third  ,,  Oculo-niotor 

Fourtli         ,,  Fourth  ,,  Pathetic  or  trudilear 

Fifth  .,  Fifth  ,,  Trigeminal  or  trifacial 

Sixth  ,,  Sixth  .,  Alxlucent 

Q         .1  f  Portio  dura    Seventh  ,,  Facial 

&e\entli       .,       j  Portio  mollis  Eighth  .,  Auditory 

f  Ninth  ,,  Glosso-i)haiyngeal 

Eighth        ,,  Tenth  ,,  Pneumogastric  or  vagus 

(  Eleventh  ,,  Spinal  accessorj' 

Ninth  ,,  Twelfth  ,,  Hj'poglossal 


It  will  be  well  to  notice  here  that  the  olfactory  bulb  and  tract  and  optic  nerves 
are  not  serially  homohjgous  with  the  other  cranial  nerves,  but  are  ratlier  outgrowths 
of  the  cerebral  sul^stance  itself.  The  'filaments  of  the  olfactory  nerve,'  which 
pierce  the  cribriform  ])late  of  the  ethmoid  bone,  correspond  collectively  to  a  cranial 
nerve.  In  the  case  of  the  optic  nerve,  the  retina,  as  a  study  of  its  development 
shows,  is  a  portion  of  the  brain  extruded  beyond  the  cranial  wall,  and  the  gangli- 
onic layer  of  the  retina  in  all  probability  corresptmds  to  the  '  nucleus  of  origin '  of 
an  ordinary  cranial  nerve.  The  nervous  elements  which  intervene  between  the 
ganglionic  layer  of  the  retina  and  the  rods  and  cones  therefore  represent  tlie  true 
optic  nerves. 

Superficial  and  deep  origins. — The  ])oint  at  wliich  a  cranial  nerve  emerges 
from  the  substance  of  the  brain  is  called  its  su])erficial  origin;  while  the  collection 
of  nerve-cells  to  which  its  fibres  can  be  followed  is  called  its  dee])  origin.  It  must 
be  clearly  understood,  however,  that  the  deep  origin  is  only  the  proximate  origin 
of  the  nerve,  the  real  origin  is  in  the  cerebral  cortex.  For  example,  injuries  to  the 
lower  portions  of  the  ascending  parietal  and  ascending  frontal  convolutions  almost 


744 


THE  NERVOUS  SYSTEM 


as  surely  paralyse  the  facial  and  hypogloss^al  nerves  as  if  the  nuclei  of  tliese  nervet; 
had  been  dt^stroyed  in  the  medulla. 

General  distribution. — The  olfactory,  optic,  and  auditory  nerves  are  exclu- 
sively nerves  of  special  sensi',  and  are  distributed  to  the  nose,  the  eye,  and  the  ear, 
res}X'ctively.  Of  the  reniaininoj  nerves,  some  are  motor,  others  are  mixed.  The 
motor  nerves  are:  the  third,  fourth,  and  sixth  to  the  ocular  muscles,  the  seventh 
to  the  i>hitysma  and  to  the  superticial  muscles  of  the  face  and  scalp,  and  the  twelfth 
to  the  muscles  of  the  tongue.  The  mixed  are  the  fifth,  which  is  chiefly  sensory  to 
the  face,  teeth,  eye,  external  ear,  and  fore  part  of  the  scalp,  but  also  motor  to  the 
muscles  of  mastication;  the  ninth,  which  contains  fibres  for  the  special  sense  of 


Fit;.  441. — ScRFACE  Okkun'  of  the  Ceaxiai,  Nerves. 
(After  Allen  Thomson. — Quain.) 


OPTIC  THALAMUS 


OPTIC  TRACT 
TUBER  CINEREUM 

POSTERIOR  PER- 
FORATED SPACE 
CORPUS  GEXICU- 

LA  TUM  EXTERXUM 
CORPUS  GEXICU- 

LA  TUM  INTERNUM 


PYRAMIDAL  BODY 
OLIVARY  BODY 

ARCIFORM  FIBRES 


FIRST  CERVICAL  NERVE 

ANTERO-LATERAL  GROOVE 
OF  SPINAL  CORD 
ANTERIOR  COLUMN  OF 
SPINAL  CORD 


ISLAND  OF  REIL 


PITUITARY  BODY 


CORPORA 
ALBICANTIA 

CPUS  CEREBRI 


PONS  VAROLII 


GREA  T  HORIZONTAL 

FISSURE 
FLOCCULUS 

FORAMEN  CMCUM 


SPINA  L  A  CCESSOR  Y 
NER  VE 


taste,  also  ordinary  sensory  and  motor  fibres;  the  tenth,  wliich  conveys  sensory 
fibres  to  the  external  ear,  and  both  motor  and  sensory  fibres  to  the  jdiarynx,  larynx, 
heart,  lungs,  trachea,  oesophagus,  and  stomach;  and  the  eleventh,  which  divides 
into  a  spinal  part,  wholly  motor,  destined  for  the  sterno-mastoid  and  trapezius 
muscles,  and  a  mixed  or  accessory  part  w'hich  joins  the  tenth. 

In  the  following  pages  the  course  of  each  nerve  is  described  in  order  from  its 
so-called  deep  origin  to  its  peripheral  distribution;  the  ultimate  connection  with 
the  cortex  is  described  in  the  anatomy  of  the  brain.  An  exception  is  made,  how- 
ever, in  the  case  of  the  olfactory  and  optic  nerves,  the  cerebral  connections  of 
which  are  described  with  the  nerves. 


OLFACTORY  NERVES 


745 


FIRST  OR  OLFACTORY  NERVES 

The  olfactory  nerves  are  twenty  to  thirty  in  number  on  each  side.  They  rise 
from  the  lower  surfaces  of  the  olfactory  bulbs,  and  are  grey  filaments  devciid  of 
wliite  sheaths.  They  pass  in  two  rows,  inner  and  outer,  througii  the  foramina  in 
the  cribriform  plate  of  the  ethmoid.  Entering  the  olfactory  mucous  memlirane 
they  anastomose  together  and  afterwards  break  up  into  filaments.  The  filaments 
of  the  outt^"  group  are  distributed  over  the  upper  and  middle  turbinal  bones  in  the 
upper  fifth  of  the  outer  wall  of  the  nasal  cavity,  and  those  of  the  inner  group 
over  a  similar  extent  of  the  U})})er  part  of  the  septum. 

The  olfactory  nerve-fibres  are  processes  of  special  olfactory  cells  in  tbc  upper 
])arts  of  the  nasal  mucous  memln'ane.  They  terminate  in  tlie  olfactory  bull)  in 
ramifications  which  are  interwoven  with  the  dendrites  of  the  mitral  cells  of  the 
bulb  forming  with  them  the  olfactory  glomeruli.      From  the  mitral  cells  fil)res  pass 


Fig.  442. — Xekves  of  the  Nasal  Cavity. 


XA  SA  L     OLFA  CTOR  Y 

FRONTAL  SiN US  XER\'E         NERVE 


OLFAf'TORY  SERVE 
TO  SUPERIOR  TUR- 
BINATE HOSE 


^——    SPHENOIDAL  SINUS 


VIDIAN  SERVE 

MECKEL'S 

GANGLION 
DESCENDINU 

PALATINE 

ORIFICE  OF  EUSTACHIAN 
TUBE 

NASAL  BRANUllES 


POSTERIOR 

PALATINE 
ANTERIOR 

PALATINE 
MIDDLE  PA  LA  TINE 


backwards  into  the  olfactorv  tract.  Thest^  may  bt-  classified  int<^  two  groups, 
namely: — (a)  Fibres  which  enter  the  cortex  of  the  tract;  and  {b)  fibres  which  pass 
throtigh  the  white  matter  to  other  ])arts  of  the  l)rain  without  becoming  connected 
to  the  cortex  of  the  tract,  (a)  From  the  cortex  of  the  tract  some  fibres  pass  rid 
the  external  Avhite  root  to  the  cortex  of  the  temporal  lobe.  Others  enter  the  ante- 
rior coimnissure,  and  })roceed  to  the  cereliral  cortex  of  the  op])osite  side,  (h^  Of 
the  fibres  which  pass  directly  through  the  tract,  some  ])ass  by  the  external  white 
root  to  the  temporal  lobe;  others  pass  as  a  slender  tract  into  the  under  border  of 
the  internal  capsule,  and  so  reach  the  front  of  the  optic  thalamus  fObersteiner). 
A  ctunmissural  bundle  of  fibres,  which  passes  from  one  olfactorv  tract  to  its  fellow 
of  the  opposite  side,  rid  the  anterior  commissure,  is  also  descriljed. 

As  they  pass  through  the  foramina  in  the  cribriform  ]ilate,  the  olfactory  nerve- 
fibres  are  invested  In-  sheaths  derived  from  tlie  dura  mater. 


746  THE  NERVOUS  SYSTEM 


SECOND   OR   OPTIC   NERVES 


The  optic  nerves  a])pear  at  the  base  of  the  brain  as  a  pair  of  round  white 
cords,  which  arise  from  the  optic  chiasma.  From  the  posterior  aspect  of  the  latter 
structure,  two  somewhat  similar  cords,  the  optic  tracts,  pass  backwards  and  out- 
wards. Each  optic  nerve  is  continuous,  through  the  chiasma,  with  both  optic 
tracts.  It  will  be  convenient  to  trace  tirst  the  central  connections  of  the  optic  nerves 
through  the  optic  tracts,  and  afterwards  to  follow  the  nerves  forwards  from  the  optic 
chiasma  to  the  eyeball. 

The  optic  chiasma  or  commissure  rests  upon  the  optic  groove,  on  the  superior 
surface  of  the  sphenoid  l)one.  It  is  in  relation  above  with  the  third  ventricle,  1)eing 
separated  only  b}'  a  thin  layer  of  grey  matter  from  that  cavity.  The  internal  car- 
otid arteries  are  close  to  its  outer  sides,  behind  it  is  the  tuber  cinereum,  and  in  front 
the  lamina  cinerea,  tlie  anterior  cerebral  and  the  anterior  conmiunicating  arteries. 

Constitution  of  the  optic  chiasma. — Three  sets  of  fibres  are  described  in  the 
optic  chiasma,  namely:  (a)  Filires  from  one  optic  tract  to  the  optic  nerve  of  the 
same  side;  (b)  fibres  from  one  optic  tract  to  the  optic  nerve  of  the  opposite  side; 
(6-)  commissural  fibres  passing  from  one  optic  tract  to  its  fellow  of  the  opi)Osite 
side,  (a)  The  uncrossed  fibres  proceed  from  the  lateral  or  temporal  half  of  the 
retina  of  the  same  side.  They  occupy  the  outer  part  of  the  chiasma.  (b)  The 
crossed  fibres,  which  form  the  largest  constituent  of  the  chiasma,  are  derived  from 
the  mesial  or  nasal  half  of  the  retina,  and  i)ass  into  the  optic  tract  of  the  oi>posite 
side.  (c)  The  commissural  fibres  occupy  the  back  part  of  the  chiasma.  They 
have  nothing  to  do  with  vision.  Two  sets  are  described  under  the  names  of  Gudden's 
and  Meynert's  commissures. 

The  optic  tract  passes  backwards  and  outwards  between  the  outer  side  of  the 
tuber  cinereum  and  the  anterior  perforated  space,  then  it  passes  under  cover  of  the 
temporal  lobe,  Avinding  around  the  crus  cerebri.  As  it  applies  itself  to  the  latter, 
it  adheres  to  it,  and  becomes  flattened  from  above  downwards.  It  next  inclines 
upwards,  and  divides  into  an  external  and  an  internal  root.  These  roots  j^roceed 
towards  the  external  and  internal  geniculate  bodies,  respectively.  The  internal 
root  contains  the  filires  of  Gudden's  commissure. 

A  portion  of  the  external  root  becomes  connected  with  the  nerve-cells  in  the 
external  geniculate  body;  another  part  enters  the  pulvinar  of  the  optic  thalamus, 
while  a  third  part  passes  in  the  superior  brachium  to  the  superior  quadrigeminal 
body  of  the  same  side. 

The  fibres  of  the  optic  nerve  terminate  therefore  amidst  or  in  the  ganglion 
cells  of  the  external  geniculate  body,  the  pulvinar  of  the  optic  thalamus,  and  the 
superior  quadrigeminal  body;  hence,  these  three  bodies  have  been  said  to  contain 
the  nuclei  of  origin  of  the  optic  nerve.  Other  fil)res,  however,  collectively  termed 
the  optic  radiation,  emerge  from  these  three  })odies,  and  pass  through  the  most 
posterior  part  of  the  inner  capsule  to  the  occipital  lobe,  and  thus  the  cortical  origin 
of  the  optic  nerve  is  estal^lished.  The  exact  area  of  the  cortex  devoted  to  the 
sense  of  sight  is  still  a  matter  of  dispute,  l)ut  the  weight  of  evidence  seems  to  l)e 
in  favour  of  the  cuneus  being  the  cerebral  centre  of  vision. 

Other  roots  of  the  optic  nerve  are  described,  of  which  the  direct  cortical  root 
(Wernicke  and  Gudden)  is  perhaps  the  most  important.  This  root  leaves  the  optic 
tract  as  the  latter  is  crossing  the  crus  cerebri,  and  runs  upAvards  in  the  inner 
capsule  to  join  the  optic  radiati(^n.  Another  root  is  described  which  passes  from 
the  optic  chiasma  into  the  central  grey  matter  of  the  third  ventricle.  The 
descending  root  (Stilling)  enters  the  crus  and  is  variously  distril)Uted;  a  jiortion  of 
its  fil)res  become  connected  with  the  oculo-motor  nucleus,  and  thus  a  jiath  for 
refiex  movements  of  the  iris  and  ciliary  muscle  is  probably  established. 

Gudden's  commissure. — Fibres  emerge  from  the  posterior  (|uadrigeminal 
liody,  constituting  its  brachium,  and  enter  the  internal  geniculate  body.  After 
])artial  interruption  in  the  nerve-cells  of  the  latter,  these  fibres  are  continued  into 
the  optic  tract  and  pass  across  to  the  opposite  side,  forming  the  back  part  of  the 
optic  chiasma,  to  enter  into  a  similar  relation  to  the  internal  geniculate  and  posterior 
<juadrigeminal  bodies  of  the  opposite  side. 


OCVLO-MOTOR   XERVES  747 

Meynert's  commissure. — From  the  grey  matter  of  the  tuber  cinereum  fibres 
arise  which  cross  the  middle  line  beliind  Gudden's  commissure  and  enter  the 
crusta  on  the  opposite  side,  from  whence  they  are  said  to  pass  into  the  sub- 
thalamic body. 

The  optic  nerve  passes  forwards  and  outwards  from  the  chiasma  and  enters 
the  orl)it  through  the  optic  foramen,  accompanied  by  the  ophthalmic  artery,  the 
vessel  being  external  to  and  slightly  below  the  nerve.  It  then  slightly  changes  its 
direction  and  passes  almost  directly  forwards  to  enter  the  l)ack  of  the  eyeball  about 
three  millimetres  internal  to  and  slightly  below  tlie  posterior  extremity  of  the  optic 
axis;  having  gained  the  interior  of  the  eyeball  its  fibres  spread  out  in  the  retina.  In 
its  course  through  the  orbit  it  is  surrounded  l)y  the  ciliary  arteries  and  nerves;  its 
upper  surface  is  crossed  obliquely  by  the  ophthalmic  artery  and  the  nasal  nerve, 
and  the  lenticular  ganglion  is  in  contact  with  its  outer  surface.  Near  the  optic 
foramen  it  is  surrounded  by,  and  in  close  relation  to,  the  four  recti  muscles;  but 
further  forwards  it  is  separated  from  the  muscles  by  an  interval  containing  fat.  The 
arteria  centralis  retinae  pierces  the  under  surface  of  the  optic  nerve  near  the  middle 
point  of  the  intraorbital  part  of  its  course  and  thence  runs  into  the  eyeball  in 
the  axis  of  the  nerve.  Very  distinct  prr)longations  of  the  cerebral  membranes 
accompany  the  optic  nerve.  The  dura  mater,  having  entered  the  orbit  through  the 
optic  foramen,  delaminates  into  the  orl)ital  periosteum  and  the  sheath  of  the  optic 
nerve;  the  latter  is  tough  and  strong,  and  becomes  continuous  with  the  sclerotic  of 
the  eyeball.  Within  the  dura  mater  is  a  narrow  subdural  space,  then  the  arachnoid 
and  a  comparatively  wide  subarachnoid  space,  the  inner  boundary  of  which  is 
formed  by  the  pia  mater,  which  invests  the  bundles  of  nerve-fibres. 


THIRD   OR   OCULO-MOTOR   NERVE 

The  third  or  oculo-motor  nerve  arises  from  a  column  of  ner\'e-cells  which  is 
placed  in  the  grey  matter  V)eneath  the  floor  of  the  aqueduct  of  Sylvius  immediately 
dorsal  to  the  posterior  longitudinal  bundle.  This  nucleus  extends  from  the  level 
of  the  posterior  commissure  to  a  point  corresponding  to  the  interval  betAveen  the 
nates  and  testes,  where  it  is  imperfectly  separated  from  the  nucleus  of  the  fourth 
nerve.  The  fibres  arising  from  it  pass  downwards  and  forwards  in  a  series  of  fas- 
ciculi, which  traverse  the  posterior  longitudinal  bundle,  the  red  nucleus,  and  the 
inner  part  of  the  substantia  nigra,  and  they  emerge  (superficial  origin)  in  a  roAV  of 
about  nine  fasciculi  from  the  oculo-motor  groove  at  the  inner  side  of  the  crus  in 
the  posterior  fossa  of  the  skull. 

The  third  nerve  passes  between  the  superior  cerebellar  and  posterior  cerebral 
arteries,  traverses  the  aperture  in  the  tentorium,  enters  the  middle  fossa  of  the 
skull,  and  then  pierces  the  dura  mater  about  mid^vay  betAveen  the  anterior  and 
posterior  clinoid  processes  of  the  sphenoid  bone  in  the  centre  of  a  little  triangular 
space  which  has  the  following  boundaries:  externally,  the  free  margin  of  the  ten- 
torium cerebelli,  posteriorly  the  attached  margin  of  the  tentorium,  and  internally 
a  ridge  of  dura  mater  which  extends  from  the  posterior  to  tlie  anterior  clinoid 
process.  It  then  enters  the  outer  wall  of  the  cavernous  sinus  and  runs  forwards  to 
the  sphenoidal  fissure,  occuj^ying,  at  first,  a  position  superior  and  internal  to  the 
fourth  nerve.  Behind  the  sphenoidal  fissure  it  divides  into  a  su])erior  and  an 
inferior  division.  These  divisifins,  as  they  enter  the  orbit  through  the  sjihenoidal 
fissure,  pass  l)etween  the  two  heads  of  the  external  rectus  muscle,  and  are  se])arated 
from  one  another  by  the  nasal  branch  of  the  ophthalmic  division  (jf  tlie  hftli 
nerve. 

The  superior  division  supplies  the  superior  rectus.  It  enters  that  muscle  on 
its  ocular  surface  and  sends  a  branch  past  its  inner  liorder  to  supply  the  levator 
palpebrie  superioris. 

Tlie  inferior  division,  considerably  larger  than  the  superior,  divides  into  three 
branches:  two  of  these,  the  nerves  to  the  internal  and  inferior  recti  muscles, 
pierce  the  ocular  surfaces  of  the  muscles  which  they  supply.  The  third  branch,  the 
nerve  to  the  inferior  ol)li(|ue,  is  considerably  longer  than  the  other  two.  It  runs 
forwards  in  the  interval  lietween  tlie  inferior  and  external  rectus  muscles,  and  pierces 


748 


THE  NERVOUS  SYSTEM 


the  posterior  border  of  the  inferior  oblique.      Near  its  commencement  it  gives  off 
the  short  or  motor  root  to  the  lenticular  ganglion. 

The  third  nerve  supplies  all  the  orbital  muscles,   with  the  exception  of  the 


Fig.  443.— Deep  Origin  of  the  Third  Nerve.     (After  Krause. 


AQUEDUCT  OF  SYLVIUS 


DEHCEXDIXG 
ROOT  OF 
TRIGEMINA  L 
NER  VE 

NUCLEUS  OF 
THIRD  NER  VE 


POSTERIOR 
LONGI- 
TUDINAL 
BUNDLE 


SUBSTANTIA 
NIGRA 


i 


THIRD  NERVE 


CRl STA 


external  rectus  and  the  superior  oblique.     It  also  supplies  (through  the  lenticular 
ganglion)  the  ciliary  muscle  and  the  circular  fibres  of  the  iris  (sphincter  iridis). 

In  the  wall  of  the  cavernous  sinus  it  is  connected  with  the  cavernous  plexus  of 
the  sympathetic  and  with  the  ophthalmic  division  of  the  fifth. 


FOURTH  OR  TROCHLEAR  NERVE 

The  fourth  or  trochlear  nerve  arises  from  a  column  of  nerve-cells  which  is 
continuous  Avitli  the  nucleus  of  the  third  nerve.  This  column  of  cells  is  embedded 
in  the  central  grey  matter  below  the  aqueduct,  and  extends  from  the  level  of  the 
interval  between  the  nates  and  testes  to  the  lower  margin  of  the  latter  bodies. 
The  nerve-fibres  issuing  from  this  elongated  nucleus  form  two  or  three  rounded 
bundles,  which  run  downwards,  backwards,  and  slightly  outwards  along  the  outer 
side  of  the  nucleus,  and  then  incline  inwards  to  reach  the  valve  of  Vieussens,  in 


TROCHLEAR  AXD  TRIGEMLXAL   XERVES 


749 


the  substance  of  which  they  decussate  with  their  fellows  of  the  opposite  side  and 
become  collected  into  a  single  bundle  (fig.  444).  This  Vmndle  emerges  as  a  slender 
rounded  fasciculus  (superficial  origin)  from  the  valve  of  Vieussens,  close  to  the 
frenulum  veli,  immediately  Vjelow  the  testes,  and  mnds  round  the  crus  cerebri  to 
ap])ear  at  the  base  of  the  brain  near  the  anterior  margin  of  the  pons.  The  right 
nerve,  therefore,  arises  from  the  left  nucleus  and  vice  versa. 

The  fourth  nerve  ])ierces  the  dura  mater  at  a  point  a  little  behind  and  external 
to  the  posterior  clinoid  process  of  the  sphenoid  bcjne  in  the  posterior  fossa  of  the 
skull.  It  runs  forwards  in  the  outer  wall  of  the  cavernous  sinus,  being  placed 
between  the  third  nerve,  which  is  above  and  internal  to  it,  and  the  ophthalmic 


Fig.  444. — Sections  through  the  Origin  of  the  Fourth  Nerve.     (Stilling.) 
(The  upper  fij^nre  is  an  oblique  section,  the  lower  is  a  coronal  section.) 


AQUEDUCT  OF  SYLVIUS 


yUCLEUS  OF  FOURTH 
NER  VE 


POSTERIOR  LONGI- 
TUDINAL BUNDLE 


AQUEDUCT  OF  SYLVIUS 


SUPERIOR  CEREBELLAR 
PEDUNCLE 


division  of  the  fifth  nerve,  which  is  situated  below  and  to  its  outer  side.  As  it 
ajujroaches  the  sphenoidal  fissure  it  bends  upwards,  crosses  on  the  outer  side  of  the 
tliird  nerve,  and  passes  through  the  innermost  part  of  the  sphenoidal  fissure.  As 
it  passes  through  the  fissure  it  is  placed  above  and  internal  to  the  frontal  nerve. 
It  then  passes  inwards  above  the  origin  of  the  levator  palpebrae  superioris  muscle, 
and  pierces  the  orbital  surface  of  the  superior  oblique  muscle,  in  which  it  ends. 

The  fourth  nerve  is  the  smallest  of  the  cranial  nerves.  It  is  remarkable  for  the 
length  of  its  intracranial  course  and  for  its  mode  of  decussation.  \\'liilst  in  the 
wall  of  the  cavernous  sinus  it  is  connected  with  the  ophthalmic  branch  of  the  fifth 
nerve  and  with  the  cavernous  plexus  of  the  sympathetic. 


FIFTH  OR  TRIGEMINAL  NERVE 

The  fifth  or  trigeminal  nerve  consists  of  two  parts,  a  large  sensory  root  (portio 
major)  and  a  small  motor  root  (portio  minor).  The  portio  major  passes  into  a 
ganglion  (Gasserian  ganglion)  which  has  been  compared  to  the  ganglion  on  the 
posterior  root  of  a  spinal  nerve,  which  it  probably  resembles  in  exercising  a  tropliic 
influence  on  the  nerve-fibres,  though  this  has  not  been  experimentally  proved.  The 
'superficial  origin'  of  the  nerve  is  from  the  side  of  the  pons  near  its  upper  border. 
The  deep  origin  of  the  portio  major  is  chiefly  l)y  the  ascending  root,  a  long  tract 
of  fibres  which  runs  for  a  con.siderable  distance  within  the  cerebro-spinal  axis.  The 
portio  major  has,  however,  in  addition  to  this,  several  supplementary  origins.  The 
portio  minor  arises  principally  from  a  nucleus  which  is  embedded  in  the  grey 


750  THE  NERVOUS  SYSTEM 

matter  of  the  floor  of  the  fourth  ventricle,  but  it  also  receives  the  whole  or  the 
greater  part  of  a  long  tract  of  fibres,  -wliich  passes  downwards  from  the  mesen- 
cephalon, and  which  is  termed  the  descending  root. 

The  majority  of  the  fibres  of  the  portio  major  spring  from  the  nerve-cells  of  the 
Gasserian  ganglion;  they  enter  the  pons  at  the  base  of  the  middle  peduncle  and 
near  its  upper  l»order.  In  the  suljstance  of  the  pons  they  i)ass  Ijackwards  and 
downwards,  and  the  smaller  numl)er  teiininate  in  ar])orisations  around  the  cells  of 
the  upper  sensory  nucleus  of  the  fifth  nerve,  an  ovoid  group  of  nerve-cells  situated 
in  the  upper  and  lateral  part  of  the  floor  of  the  fourth  ventricle  external  to  the 
motor  nucleus  and  continuous  ])elow  with  the  substantia  gelatinosa  Rolandi,  which 
is  called  the  lower  sensory  nucleus.  The  greater  number  of  the  filjres  of  the  portio 
major  pass  downwards  in  the  pons,  medulla,  and  spinal  cord,  forming  a  crescentic 
bundle,  known  as  the  ascending  root  of  the  fifth  nerve,  which  lies  external  to  the 
sul)stantia  gelatinosa  of  Rolando.  It  diminishes  in  size  as  it  descends,  and  it 
finally  terminates  in  the  upper  part  of  the  cervical  region  of  the  cord.  Its  fibres 
pass  into  the  substantia  gelatinosa  and  probably  terminate  in  ar]:iorisations.  In  the 
pons  the  ascending  root  of  the  fifth  nerve  is  deeply  placed  between  the  auditory  and 
facial  nerve-roots  (fig.  430),  and  in  the  upper  part  of  the  medulla  it  is  covered  by 
the  restiform  body  (fig.  432),  but  in  the  lower  part  of  the  medulla  and  the  upper 
part  of  the  cord  it  lies  close  beneath  the  surface. 

The  descending  root  arises  from  a  column  of  nerve-cells  Avhich  is  embedded  in 
the  grey  matter  of  the  aqueduct  above  and  external  to  the  nucleus  of  the  third 
nerve.  The  root  commences  at  the  level  of  the  upper  part  of  the  nates,  and  increases 
in  size  as  it  descends,  forming  a  white  Inmdle  of  fibres  crescentic  in  section,  some 
of  these  fibres  being  connected  with  the  nerve-cells  which  are  placed  on  their  inner 
side  (fig.  444,  v).  It  passes  through  the  grey  matter  of  the  upper  part  of  the 
floor  of  the  fourth  ventricle,  close  to  the  outer  side  of  the  substantia  ferruginea, 
and  reaches  the  upper  part  of  the  motor  nucleus  of  the  fifth  nerve.  Here  it  is  joined 
by  the  principal  part  of  the  motor  root,  which  arises  from  the  motor  nucleus,  and 
by  a  few  fibres  from  the  motor  nucleus  of  the  opi^osite  side.  It  then  passes  down- 
wards and  forwards  through  the  pons  to  emerge  as  the  portio  minor  of  the  fifth 
nerve.  At  its  emergence  it  is  placed  a  little  in  front  of  the  sensory  portion,  and  is 
separated  from  the  latter  by  some  of  the  transverse  fibres  of  the  pons.  The  motor 
nucleus  is  an  ovoid  mass  of  cells  consideraVjly  shorter  than  the  accessory  sensory 
nucleus,  on  the  inner  side  of  which  it  is  placed.  It  is  on  the  same  line  as  the 
nucleus  of  the  facial  nerve,  and  is  immediately  in  front  of  that  nucleus. 

According  to  some  observers  some  fibres  of  tlie  descendiug  root  enter  the  sensorj'  root  and  are 
said  to  eventually  pass  into  the  ophthalmic  division. 

The  sensory  and  motor  roots  of  the  nerve  pass  downwards  and  fonvards  towards 
an  aperture  in  the  dura  mater  which  is  placed  under  cover  of  the  tentorium 
cerebelli,  a  little  external  to  the  apex  of  the  petrous  portion  of  the  temporal  l)one 
in  the  posterior  fossa  of  the  skull.  In  this  course  the  motor  root  takes  a  half- 
spiral  turn  around  the  sensory  root,  passing  first  to  the  inner  side,  and  then  beh^w 
the  latter.  Both  roots  then  pass  through  the  aperture  above  mentioned  to  enter 
Meckel's  space  in  the  middle  fossa,  between  the  supporting  and  periosteal  layers 
of  the  dura  mater.  The  motor  root  passes  out  of  the  skull  through  the  foramen 
ovale,  accompanied  by  a  larger  sensory  bundle  from  the  Gasserian  ganglion,  and 
joins  with  the  latter  outside  the  skull  to  form  the  mandiljular  (or  inferior  max- 
illary) division  of  the  fifth  nerve.  The  sensory  root  spreads  out  into  a  flattened, 
somewliat  fan-slia])('(l,  plcxiform  lumdle,  and  enters  the  Gasserian  ganglion. 

The  Gasserian  ganglion  is  a  reddish-grey  band  of  ganglionic  matter,  with  its 
long  axes  slightly  curved  so  as  to  present  a  convexity  forwards  and  outwards.  The 
upper  and  lower  surfaces  of  the  ganglion  are  also  slightly  convex  and  are  some- 
what adherent  to  the  dura  mater,  the  upper  surface  being  more  firmly  attached 
than  the  lower.  It  rests  in  a  depression  on  the  petrous  bone  and,  in  front  of  this, 
on  the  cartilage  which  occupies  the  foramen  lacerum  medium.  From  the  convex 
antero-external  liorder  of  tlie  ganglion,  three  large  bundles  of  nerve-fibres  arise. 
The  first  or  oplithalmic  division  enters  the  orbit  tln'ough  the  sphenoidal  fissure. 
The  second  or  maxillary  ( sujx'rior  maxillary)  division  leaves  the  skull  through  the 


OPHTHALMIC  DIVISIOX  OF  THE  FIFTH  NERVE 


51 


foramen  rotunduin.  The  tliinl  (livisioii  jiasscs  through  tlie  foramen  ovale  in  front 
of  the  motor  root  of  the  fifth  nerve,  with  which  it  unites,  as  already  described, 
to  form  the  mandibular  (inferior  maxillary)  division.  The  Gasserian  ganglion 
receives  communications  from  the  carotid  i)lexus  of  the  sympathetic,  and  is  said  to 
furnish  some  minute  twigs  to  the  dura  mater. 

First  or  Ophthalmic  Division  of  the  Fifth  Nerve 

The  ophthalmic  is  the  smallest  of  the  three  divisions  of  the  fifth,  and  is  entirely 
sensory  in  function.  It  passes  forwards  and  inwards  in  the  outer  wall  of  the 
cavernous  sinus,  where  it  is  placed  below  and  external  to  the  fourth  nerve.  Behind 
the  sphenoidal  fissure  it  divides  into  three  branches.  These  branches  pass  through 
the  sphenoidal  fissure,  piercing  the  fibrous  derivative  of  the  dura  mater  Avhich  closes 
it.  Two  of  them,  the  frontal  and  the  lachrymal,  enter  the  orbit  above  the  external 
rectus  muscle.  The  remaining  branch,  the  nasal,  passes  between  the  two  heads  of 
that  muscle.  In  its  course  in  the  outer  Avail  of  the  cavernous  sinus  the  o])hthalnjic 
division  receives  communications  from  the  carotid  plexus  of  the  sympathetic,  and 
gives  off  a  tentorial  )>ranch  (nervus  recurrens  rami  primi,  Luschka)  which  runs  l)ack- 
wards  for  a  short  distance  within  the  sheath  of  the  fourth  nerve,  and  is  distributed 


Fig.  445. — Nerves  of  the  Orbit,  from  the  Outer  Sihe. 
(From  f?appey,  after  Hirschfeld  aud  Leveille.) 

LEyriCVLAR  G.iyGLION 
SUPERIOR  DIVISION  OF  THE  THIRD  NERVE 


SUPRAORBITAL 
NERVE 


SHORT  CILIARY 
NERVES 


BRANCH  OF  THIRO  TO 
INFERIOR  OBLIQUE 


NASAL  BRANCH  OF  OPHTHA  LMIO 

LONG  ROOT  OF  LENTICU- 
LAR GANGLION 

OPTIC  NER  VE 


THIRD  NERVE 
SIXTH  NERVE 
GASSERIAN  GANGLION 


OPllTHA  LMIf   I) 1 1 ISION 
OF  FIFTH  NERVE 


SHORT  ROOT  OF  SYMPA  THETK'  ROOT  OF  LENTICULAR 

LENTICULAR  GANGLION  GANGLION 


between  the  layers  of  the  tentorium  cerebelli.  It  also  gives  communicating 
branches  to  the  third,  fourth,  and  sixth  nerves.  The  orbital  muscles  receive  their 
sensory  supply  through  these  communications. 

(1)  The  frontal  nerve  is  the  largest  brancli  of  tlic  ophthalmic  division.  It 
passes  forwards  and  ui)wards  on  the  inner  side  of  tlic  third  nerve,  and  enters  tlie 
orbit  immediately  external  to,  and  a  little  below,  the  fourth  nerve.  It  passes  for- 
wards between  the  periosteum  of  the  orbit  and  tlie  levator  ])alpebiw  superioris 
muscle,  and,  a  little  behind  the  middle  of  the  orbit,  divides  into  two  branches, 
termed  the  supraorbital  and  supratrochlear. 

(2)  The  supraorbital  nerve  leaves  the  or})it  by  passing  through  the  sui)raor])ital 
notch  or  foramen,  where  it  gives  twigs  to  the  upper  eyelid,  and  turns  upAvards  on 
the  frontal  bone,  accompanied  by  the  supraorbital  artery.  It  dlA'ides  into  tAvo 
branches,  an  external  and  an  internal.  Both  these  ])ranches  divide  into  several 
twigs,  AA'hich  pass  A'ery  obli(]uely  through  the  anterior  l)elly  of  the  occipito-frontalis 
muscle,  and  sui)))ly  the  integument  of  the  forehead  and  fore  ])art  of  the  scalp.  The 
external  branch,  Avhich  is  considerahly  larger  tlian  the  internal,  may  be  traced 
backwards  nearly  as  far  as  the  lamlxloidal  suture. 

(3)  The  supratrochlear  nerve  is  directed  forwards  an<l  inwards  above  the 
pulley  of  the  superior  ot)li(jue  nuiscle.      It  connnunieates  Avith  the  infratrochlear 


752  THE  NERVOUS  SYSTEM 

branch  of  the  nasal  nerve  and  turns  upwards  on  the  forehead,  accompanied  by  the 
frontal  artery.  It  is  much  smaller  than  the  supraorliital  nerve,  and  it  is  distributed 
to  a  small  area  of  integument  around  the  glabella.  It  gives  twigs  to  the  inner  part 
of  the  upper  evelid. 

(4)  Tbe  lachrymal  nerve  is  the  smallest  of  the  three  branches  of  the  ophthalmic 
division.  It  passes  through  the  sphenoidal  tlssure  external  to  and  slightly  below 
the  frontal  nerve,  and  is  directed  forwards  and  outwards  along  the  ujjper  border  of 
the  external  rectus  muscle  to  the  lachrymal  gland.  Immediately  behind  the 
lachrymal  gland  it  communicates  with  the  temporal  branch  of  the  orbital  nerve, 
forming  a  loop  convex  forwards;  from  this  loop  and  from  the  adjacent  part  of  thi' 
trunk  of  the  nerve  a  number  of  twigs  pass  into  the  gland  substance.  A  small  twig 
passes  beyond  the  gland  and  is  distributed  to  the  integument  and  conjunctiva  at 
the  outer  canthus  of  the  eye. 

(5)  The  nasal  nerve  enters  the  orbit  by  passing  forwards  between  the  superior 
and  inferior  divisions  of  the  third  nerve,  and  takes  an  oblique  course  forwards  and 
inwards  to  reach  the  inner  wall  of  the  orbit.  In  this  course  it  passes  between  the 
optic  nerve  and  the  superior  rectus  muscle.  It  then  passes  between  the  superior 
oblique  and  the  internal  rectus,  traverses  the  anterior  internal  orbital  canal, 
accompanied  by  the  anterior  ethmoidal  vessels,  enters  the  anterior  fossa  of  the 
skull,  crosses  the  cribriform  plate  of  the  ethmoid  l)one  under  cover  of  the  dura 
mater,  and  enters  the  nasal  fossa  through  a  slit-like  aperture  at  the  side  of  the  crista 
galli  (the  ethmoidal  fissure).  It  terminates  within  the  nasal  fossa  by  dividing  into 
three  branches:  an  internal,  or  septal;  an  external;  and  an  anterior,  or 
terminal. 

Branches. — The  long  root  to  the  lenticular  ganglion  is  given  off  at  the 
sphenoidal  fissure.  It  is  a  slender  filament  which  passes  forwards  to  join  the  upper 
and  back  part  of  the  ganglion.  The  long  ciliary  nerves,  usually  two  in  number, 
arise  from  the  nasal  trunk  as  the  latter  is  crossing  the  optic  nerve.  They  are 
directed  forwards  along  the  inner  side  of  the  optic  nei-ve,  and  join  the  lower  set  of 
short  ciliarv  nerves  after  they  pierce  the  sclerotic  (page  851).  The  infratrochlear 
nerve  is  given  off  by  the  nasal  just  before  the  latter  enters  the  anterior  internal 
orbital  canal.  It  passes  forwards  beneath  the  j^ulley  of  the  superior  oblique  muscle, 
and  supplies  the  skin  and  conjunctiva  around  the  inner  canthus  of  the  eye  and 
the  integument  of  the  upper  part  of  the  nose.  It  also  supplies  the  lachrymal  sac 
and  caruncle.  It  communicates  with  the  supratrochlear  nerve  in  front  of  (some- 
times behind)  the  pulley. 

The  internal  or  septal  branch  of  the  nasal  nerve  runs  downwards  and  for- 
wards on  the  upper  and  front  part  of  the  nasal  septum. 

The  external  branch  gives  tw^o  or  three  twigs- to  the  anterior  extremities  of  the 
superior  and  middle  turbinated  bones,  and  to  the  mucous  membrane  of  the  outer 
wall  of  the  nose. 

The  terminal  or  anterior  branch  runs  downwards  in  a  groove  on  the  inner 
surface  of  the  nasal  bone.  It  pierces  the  wall  of  the  nose  Ijetween  the  nasal  bone 
and  the  lateral  cartilage,  and  supplies  the  integument  of  the  lower  part  of  the 
dorsum  of  the  nose  as  far  as  the  tip  of  that  organ. 

Lenticular  Ganglion 

The  lenticular,  ciliary,  <>r  ophthalmic  ganglion  is  a  small  reddish-grey  body 
about  the  size  of  a  pin's  head.  It  is  (luadrilateral  in  outline,  and  its  outer  and 
inner  surfaces  are  slightly  convex.  It  is  ])laced  between  the  optic  nerve  and  the 
external  rectus  muscle,  about  a  quarter  of  an  inch  in  front  of  the  sphenoidal  fissure. 
Following  the  general  rule  applying  to  the  sporadic  ganglia  which  are  connected 
witli  the  fifth  nerve,  it  is  ])rovided  Avith  three  roots,  a  motor,  a  sensory,  and  a 
sympathetic.  The  motor  or  short  root  is  derived  from  the  branch  of  the  oculo- 
motor to  the  inferior  oblique  muscle;  it  enters  the  posterior  inferior  angle  of  the 
ganglion.  The  sensory  or  long  root  is  a  branch  of  the  nasal  nerve;  it  passes 
along  the  outer  side  of  tbe  o})tic  nerve,  and  enters  the  U})})er  and  back  part  of  the 
ganglion.  Tbe  sympathetic  root  is  derived  from  tlie  cavernous  plexus  of  the 
sympathetic;  it  may  enter  tlie  ])ack  \m\y{  of  the  ganglion  in  tlie  form  of  tine  tAvigs, 


MAX  I L  LA  J!  y  nnisioy  or  tiik  fifth  sfuve  :w^ 

but  usually  R';a-lie.s  the   j^anj^dioii  for  the  uiost  jtart   through  tlic  third  and  imsal 
nerves,  being  ineorj)orated  with  the  motor  and  sensory  root;-. 

From  the  anterior  Ijorder  of  the  ganglion  about  six  short  ciliary  nerves  arise; 
these  subdivide  and  communicate  with  the  long  ciliary  nerves,  forming  al)out  twenty 
nerves  which  separate  into  a  supero-external  and  an  infero-internal  group,  and 
surround  the  otitic  nerve.  The  nerves  jiierce  the  sclerotic  in  a  circle  around  the 
entrance  of  the  optic  nerve  into  the  eyeball,  and  pass  forwards  between  the  sclerotic 
and  choroid  coats  of  the  eye.  They  suj)ply  nerves  of  ordinary  sensation  and  trophic 
nerves  to  the  eyeball  (derived  from  the  nasal);  the  radiating  fibres  of  the  iris 
(derived  from  the  sympathetic);  and  the  ciliary  muscle  and  s})hincter  of  the  ])U]iil 
(derived  from  the  oculo-motor  j  (page  850). 

Second  ok  Maxillai;v  Division  of  the  Fifth  Nerve 

The  maxillary  (superior  maxillary)  division  of  the  fifth  nerve  is  intermediate 
in  size  between  the  mandibular  (inferior  maxillary)  and  ophthalmic  divisions,  and, 
like  the  latter,  it  is  entirely  sensory  in  function.      It  i>roceeds  forwards  from  the 

Fk;.  446. — The  Maxillary  Nerve  seen  from  wrrHorT.      (Beaxmis.) 

ANTERIOR  DEXTAL        MAAILLARi' NERVE        ORBITAL  BRANt'll 


NOLIOX 


LOOP  FORMED  BY  MIDDLE  AND  ANTERIOR  DENTAL  NERVES 


Gasserian  ganglion  for  about  one-third  of  cin  inch  Avithin  tlie  skull,  and  then  passes 
through  the  foramen  rotundum.  It  traverses  the  up]K'r  ])art  of  the  spheno- 
maxillary fossa,  and.  inclining  upwards,  passes  into  the  orbit  through  the  spheno- 
maxillary fissure.  It  then  courses  forwards  along  the  infraorbital  groove,  accom- 
panied by  the  infraorbital  artery,  to  the  infraorbital  canal,  and  passes  through  the 
canal  to  emerge  at  the  infraorbital  foramen,  where  it  terminates,  almost  innnediately, 
in  three  sets  of  branches,  which  ]>roceed  to  the  upper  lip,  the  nose,  and  the  lower 
eyelid. 

Branches. — The  l^raiuhes  of  the  maxillary  division  may  be  classified  intofom- 
sets,  namely: — (1)  Intracranial  branches:  {'!)  brandies  which  are  given  off  in  the 
spheno-maxillarv  fossa;  (;'>)  branches  which  arise  from  the  ])ortion  of  the  nerve 
which  is  [)laced  in  the  infraorlntal  canal:  and  (4  >  tcnninal  ])ranches. 

The  first  set  (1)  consists  of  one  or  two  recurrent  twigs  to  tlie  <lura  mater, 
which  form  loops  with  the  recurrent  branch  of  the  mandilmlar  (inferior  maxillary 
division.     The  second  set  (2)  comi>rises  the  orbital  nerve,  the  spheno-palatine 
nerves,  and  the  posterior  superior  dental  nerves.    ( 3)  The  middle  aixl  anterior 
48 


754  THE  NERVOUS  SYSTEM 

superior  dental  nerves  constitute  the  tliiid  set.      (4)  The  terminal  branches 
fall  into  three  groups,  which  are  tenne(l  hil)ial,  nasal,  and  pal}tel)ral  l)ranehes. 

The  orbital  or  temporo-malar  nerve  passes  uj)war(ls  and  forwards  through 
the  spheno-niaxillary  lissure  l)y  which  it  enters  the  orhit,  and  teiniinates  hy  divid- 
ing into  two  l)ranches,  temporal  and  malar.  The  temporal  branch  conimunicates 
Avith  the  lachrymal  nerve,  and  then  runs  forwards  tln-ough  the  periosteum  on  the 
outer  wall  of  the  orl)it,  and  traverses  the  spheno-malar  foramen.  It  enters  the 
temjjoral  fossa  and  pierces  the  deeper  of-  the  two  lamellae  of  the  temporal  fascia. 
It  runs  outwards  for  about  a  quarter  of  an  inch  in  the  fat  between  the  two  lamella' 
of  the  fascia,  and  pierces  the  superficial  lamella  about  an  inch  above  the  superior 
border  of  the  zygoma;  here  it  forms  a  well-marked  communication  with  the  tem- 
])oral  l:)ranch  of  the  facial  nerve,  and  then  ramifies  in  the  integument  of  the  anterior 
temporal  region.  The  malar  branch  (ramus  subcutaneous  malae)  runs  for- 
wards in  the  loose  fatty  tissue  of  the  orl)it,  and  ])asses  through  the  malar  foramen. 
It  })ierces  the  orl)icularis  palpebrarum  and  su])})lies  a  small  area  of  skin  oA'cr  the 
prominence  of  the  cheek.    It  communicates  with  the  malar  l)ranch  of  the  facial  nerve. 

The  spheno-palatine  nerves  are  two  stout  twigs  which  pass  downwards  to 
Meckel's  ganglion,  of  which  they  form  the  sensory  roots;  most  of  the  nerve- 
fibres  pass  on  the  inner  side  of  the  ganglion  without  traversing  the  ganglionic 
substance,  but  it  is  more  convenient  to  trace  these  nerves  with  the  branches  of  the 
ganglion. 

The  posterior  superior  dental  nerves,  usually  two  in  nunil>er,  pass  down- 
wards and  outwards  through  tlie  pterygo-maxillary  fissure.  They  furnish  several 
twigs  to  the  gums  ( nervuli  gingivales)  and  adjacent  part  of  the  mucous  membrane 
of  the  cheek.  They  then  enter  foramina  in  the  maxilla,  follow  the  curve  of  the 
alveolar  arch  through  minute  canals  in  the  bone  above  the  roots  of  the  molar  teeth, 
and  end  by  communicating  in  a  plexiforrn  manner  with  the  middle  dental  nerve. 
They  give  off  minute  branches  to  the  mucous  membrane  of  the  antrum,  and  furnish 
three  twigs  to  each  of  the  molar  teeth.  These  twigs  enter  the  foramina  at  the  ti])s 
of  the  fangs  of  the  teeth  and  ramify  in  the  pulp. 

The  middle  and  anterior  superior  dental  nerves  are  small  l)ranches  which 
pass  through  canals  in  the  substance  of  tin'  maxilla  to  su])ply  the  incisor,  canine, 
and  bicuspid  teeth  and  the  corresponding  regions  of  the  ginns.  In  the  upper,  and 
more  particularly  in  the  lower,  ])arts  of  these  canals  the  nerves  are  surrounded  on 
all  sides  by  thick  bone;  but  in  the  middle  part,  where  they  are  traversing  the 
anterior  w^all  of  the  antrum,  th&y  are  surrounded  by  a  mere  shell  of  bone,  which  is 
not  infrequently  deficient  on  the  deep  surface,  so  that  the  nerves  may  lie  in  grooves 
in  the  anterit)r  w^all  of  the  antrum  between  the  bone  and  mucous  membrane.  In 
this  situation  the  nerves  furnish  twigs  to  the  antrum.  The  middle  dental  nerve 
enters  a  foramen  at  the  posterior  part  of  the  infraorliital  canal.  It  sup])lies  the 
bicuspid  teeth,  and  communicates  with  the  anterior  and  posterior  dental  nerves.  It 
may  l)e  wanting.  The  anterior  dental  nerve  enters  a  canal  close  to  the  infni- 
orljital  foramen,  and  su])})lies  the  incisor  and  canine  teeth.  It  gives  off  a  nasal 
branch,  which  passes  through  a  minute  canal  in  the  bone  and  enters  the  anterior 
])art  of  the  inferior  meatus.  Here  it  ramifies  in  the  mucous  mend)rane,  and  com- 
municates with  the  naso-palatine  nerve  from  Meckel's  ganglion.  It  connnunicates 
with  the  middle  dental  nerve. 

Two  stuall  gangliform  enlargements  are  ooeasionally  found  on  the  plexiforrn  arch  formed  hy 
the  dental  nerves.  One  of  these,  tlie  ganglion  of  Valentin,  is  situated  above  the  root  of  the 
second  l)icuspid  at  the  junction  of  the  middle  and  posterior  dental  nerves.  The  other,  the 
ganglion  of  Bochdalek,  is  placed  on  the  junction  of  the  anterior  and  middle  dental  nerves. 

The  labial  branches,  usually  four  in  number,  are  the  largest  of  the  tln-ee 
terminal  divisions  of  the  maxillary  nerve.  They  pass  downwards,  S])reading  out  as 
they  descend,  under  cover  of  the  levator  labii  superioris  muscle,  and  ramify  in  the 
structures  forming  the  upper  lip,  very  large  twigs  being  supplied  to  the  mucous 
membrane. 

The  nasal  branches,  three  or  four  in  number,  are  intermediate  in  size.  They 
pass  inwards  under  cover  of  the  levator  labii  sui)erioris  alteque  nasi,  and  supply  the 
integument  on  the  lateral  aspect  of  the  nose. 


MECKEUS  GANGLION.  IT)-) 

The  palpebral  branches,  the  smallest  of  the  tenuinul  divisions  of  the  nerve, 
pierce  the  origin  of  the  levator  labii  superioris,  and  turn  upwards  around  the 
lower  border  of  the  orl)iculai-is  ])al]iebrarum.  They  are  usually  two  in  numl)er,  an 
external  and  an  internal;  they  ramify  in  the  integument  of  the  lower  eyelid. 

The  terminal  branches  of  the  maxillary  division  coiununiicatc  fn^ely  with  the 
infraorbital  brand)  of  th(^  facial,  forming  the  infraorbital  plexus.  Tiie  plexus  is 
placed  under  cover  of  the  levator  la)>ii  sujx'rioris. 

Meckel's  Ganglion 

The  spheno-palatine,  nasal,  or  Meckel's  ganglion  is  a  small  reddish-grey 
body  wliich  is  situated  in  the  spheno-maxillary  fossa.  It  is  triangular  in  form, 
llattened  at  the  sides,  and  measures  about  one-fifth  of  an  inch  in  its  longest  diameter. 
It  is  provided  with  three  roots,  a  motor  and  a  sympathetic,  which  reach  it  through 
the  Vidian  nerve,  and  a  sensory  root  from  the  maxillary  nerve.  The  latter  root  is 
in  tlie  form  of  two  stout  twigs,  wliich  are  described  as  the  spheno-})alatine  nerves. 

Roots. — Tile  great  superficial  petrosal  nerve  is  the  motor  root  of  the  ganglion. 
It  arises  from  the  geniculate  ganglion  of  the  facial  nerve  within  the  aqueduct  of 
Fallopius,  and  enters  the  cranial  cavity  by  traversing  the  hiatus  Fallopii.  It  then 
runs  forwards  and  inwards  in  a  groove  in  the  petrous  portion  of  the  temporal  bone, 
and,  after  passing  under  the  Gasserian  ganglion,  enters  an  ol)lique  canal  in  the 
cartilage  which  occupies  the  foramen  lacerum  medium.  Having  reached  the 
posterior  opening  of  the  Vidian  canal,  it  unites  Avith  the  great  deep  petrosal  nerve 
to  form  the  Vidian  nerve. 

The  great  deep  petrosal  nerve  is  of  a  grey  colour  and  is  soft  in  consistence. 
It  arises  from  the  carotid  ])lexus  of  the  sympathetic  close  to  the  intracranial  termi- 
nation of  the  carotid  canal,  traverses  a  canal  in  the  cartilage,  which  occu])ies  the 
foramen  lacerum  medium,  and  joins  the  Vidian  nerve. 

The  Vidian  nerve  runs  forwards  through  the  canal  of  the  same  name,  accom- 
panied l»y  the  N'idian  artery,  and  enters  the  spheno-maxillary  fossa,  where  it  ends 
in  the  posterior  angle  of  Meckel's  ganglion.  While  within  the  canal  the  Vidian 
nerve  furnishes  nasal  twigs  to  the  mucous  membrane  of  the  posterior  part  of  the 
roof  of  the  nose.  They  may  be  regarded  as  superior  nasal  nerves,  which,  after 
leaving  ^Meckel's  ganglion,  have  become  associated  with  the  Vidian  nerve  for  a  ])art 
of  their  course. 

Branches. — The  V)ranches  of  Meckel's  ganglion  are  classified  into  (1)  ascend- 
ing, to  the  orljit;  (2)  internal,  to  the  mucous  membrane  of  the  nose;  (8)  de- 
scending, to  the  liard  and  soft  palate;  and  (4)  posterior,  to  tlie  ]>harvnx. 

(Ij  Ascending  branches. — The  ascending  or  orbital  branches  are  two  or 
three  small  twigs  which  enter  the  orbit  through  tlie  spheno-maxillary  fissure,  and 
proceed  within  the  periosteum  to  the  inner  wall  of  the  orbit,  where  they  pass  through 
the  posterior  internal  orbital  canal  and  through  the  foramina  in  the  suture  behind 
that  canal  to  be  distributed  to  the  mucous  membrane  Avhich  lines  the  posterior 
ethmoidal  cells  and  the  sphenoidal  sinus. 

(2)  Iriternal  branches. — The  internal  branches  are  derived  in  ])art  from  the 
inner  side  of  the  ganglion,  but  are  also  largely  made  uj)  of  fibres  which  jiass  from 
tlie  s])heno-palatine  nerves  without  traversing  tlie  ganglionic  substance.  They  are 
dis])osed  in  two  sets,  the  sujierior  nasal  and  the  septal. 

The  superior  nasal  are  six  or  seven  small  twigs  which  pass  through  the  si)heno- 
palatine  foramen,  and  are  distributed  to  the  mucous  membrane  covering  the; 
j)osterior  parts  of  the  superior  and  middle  turbinated  bones.  They  also  furnish 
twigs  to  the  lining  membrane  of  the  posterior  ethmoidal  cells. 

The  septal  branches  are  two  or  three  in  number,  and  ]>ass  inwards  through 
the  spheno-palatine  foramen.  They  cross  the  roof  of  the  nasal  fossa  to  reach  the 
l)ack  part  of  the  nasal  septum,  where  the  smaller  twigs  terminate.  The  largest 
nerve  of  the  set,  naso-palatine  nerve,  or  nerve  of  Cotunnius,  runs  flownwards 
and  forwards  in  a  groove  in  the  vomer  between  the  periosteinn  and  the  mucous 
membrane  to  the  anterior  ])alatine  canal.  Here  it  communicates  with  the  nasal 
branch  of  the  anterior  superior  dental  nerve.  The  two  naso-palatine  nerves  then 
pass  through  the  foramina  of  Scarjta  in  the  inti'rmaxillary  suture,  the  left  nerve 


756  THE  SERVO  US  SYSTEM 

passing  through  the  anterior  of  the  two  foramina.  In  the  lower  })art  of  the  anterior 
I)alatine  canal  the  two  nerves  form  a  plexiform  conmiunieation  ( formerly  descrihed 
as  Chxiuet's  ganglion)  and  furnish  twigs  to  the  anterior  ])art  of  the  hard  palate. 
In  this  situiition  they  coiiiniunieate  with  the  anterior  palatine  nerves. 

(8)  Descending  branches. — The  descending  l)ranches  are  the  great  or  anterior, 
the  posterior,  and  the  external  palatine  nerves.  Like  the  internal  set  of  hranches, 
tliey  are  in  part  derived  from  the  ganglion  and  in  part  directly  continuous  with 
tlie  spheno-palatine  nerves. 

The  great  or  anterior  palatine  nerve  arises  from  the  inferior  angle  of  Meckel's 
ganglion,  and  passes  downwards  tlirough  the  posterior  palatine  canal,  accompanied 
hy  the  descending  palatine  artery.  Emerging  from  the  canal,  it  divides  into  two 
or  three  branches,  which  pass  forwards  in  grooves  in  the  hard  palate  and  su])ply 
the  glands  and  mucous  membrane  of  the  hard  palate  and  the  gums  on  the  inner 
;ispect  of  the  alveolar  border  of  the  upper  jaw.  During  its  course  through  the 
posterior  })a]atine  canal,  the  anterior  palatine  nerve  gives  off,  usually  two,  inferior 
nasal  nerves.  These  ner\^es  pass  through  small  openings  in  the  perpendicular 
plate  of  the  palate  bone  to  supply  the  mucous  membrane  covering  the  back  parts  of 
the  inferior  turVjinated  bone  and  lining  the  middle  and  inferior  meatuses  of  the  nose. 

The  posterior  or  small  palatine  nerve  passes  downwards  through  the  acces- 
sory i)alatine  canal,  and  enters  the  soft  palate,  distril^uting  branches  to  that  organ,  to 
the  uvula,  and  to  the  tonsil.  It  was  formerly  believed  to  convey  motor  fibres  from 
the  facial  nerve  to  the  levator  palati  and  azygos  uvuhe  muscles,  but  these  muscles 
are  now  known  to  be  supplied  l)y  the  spinal  accessory  nerve,  through  the  pharyn- 
geal plexus. 

The  external  palatine  nerve,  the  smallest  of  the  three,  traverses  the  external 
])alatine  canal,  and  supplies  twigs  to  the  tonsil  and  to  the  adjacent  part  of  the  soft 
palate. 

(4)  Posterior  branch. — The  \'idian  is  considered  by  some  anatomists  to  be  a 
branch,  in  which  case  it  w'ould  be  classed  here.  We  have,  however,  regarded  it 
as  the  united  motor  and  sympathetic  root  of  the  ganglion;  therefore,  the  pharyn- 
geal branch  only  remains  to  l)e  described. 

The  pharyngeal  branch  is  of  small  size,  and  passes  backwards  and  somewhat 
inwards  through  the  ])tery go-palatine  canal,  accompanied  by  the  pterygo-palatine 
artery.  It  is  distributed  to  the  mucous  membrane  of  the  uppermost  part  of  the 
pharynx,  to  the  upper  part  of  the  posterior  nares,  to  the  opening  of  the  Eustachian 
tube,  and  to  the  lining  of  the  sphenoidal  sinus. 

Third  or  Mandibular  Division  of  the  Fifth  Nerve 

The  mandibular  ( inferior  maxillary )  division  is  the  largest  of  the  three 
divisions  of  tlie  fifth  nerve,  and  is  formed,  as  Ix-fore  stated,  by  the  union  of  two 
distinct  parts,  namely,  the  entire  motor  root  of  the  fifth  nerve  and  a  large  bundle  of 
fibres  derived  from  the  sensory  root  and  traversing  the  Gasserian  ganglion.  These 
two  parts  pass  through  the  foramen  ovale  and  unite  immediately  outside  the  skull 
to  form  a  large  trunk  which  terminates  almost  directly  after  its  formation  by 
dividing  into  a  smaller  anterior  and  a  larger  posterior  portion.  The  anterior  portion 
is  chiefly  motor,  and  the  posterior  division  mainly  sensory  in  function.  Previous 
to  its  division,  two  branches  arise  from  the  trunk  of  the  nerve,  namely,  the  recur- 
rent nerve  and  tin-  nerve  to  the  internal  pterygoid. 

(1)  The  recurrent  nerve  enters  the  cranium  through  the  foramen  s])inosimi, 
ac(;ompanying  the  middle  meningeal  artery,  and  divides  into  an  anterior  and  a 
})osterior  l)ranch.  The  anterior  branch  conmmnicates  with  the  meningeal  l)ranch 
of  the  maxillary  division  of  the  fifth  nerve,  furnishes  filaments  to  the  dura  mater, 
and  ends  in  the  osseous  substance  of  the  great  wing  of  the  sphenoid.  The  posterior 
branch  traverses  the  petro-squamous  suture  and  ends  in  the  lining  membrane  of 
the  mastoid  cells. 

(2)  The  nerve  to  the  internal  pterygoid  passes  under  cover  of  a  dense  layer 
of  fascia  deprived  from  an  expansion  of  the  ligamentum  ])teryg(»-s])in()sum,  and 
enters  the  deej)  surface  of  the  muscle.  Near  its  connnencement  this  nerve  furnishes 
a  motor  root  to  the  otic  ganglion. 


MANDIBrLAR    DIVISION  OF  THE  FIFTH  NFIiVE  757 

The  ANTERIOR  PORTION  of  the  inaiidihular  division  of  tlie  fiftli  nerve  suppHes 
the  temporal,  inasseter,  and  external  pterygoid  mutscles,  and  gives  off  a  sensory 
hranch,  the  h)ng  biiccid  nerve;  the  latter  is  accompanied,  in  the  first  ])art  of  its 
course,  by  a  small  strand  of  motor  fi)>res  which  leaves  it  to  end  in  the  anterior  j)art 
of  the  temporal  muscle. 

(1)  Tli(!  temporal  nerves,  usually  two  in  innnlicr,  pass  Itetween  the  lK)ne  and 
the  upper  border  of  the  external  pterygoid  muscle,  and  turn  U])wards  around  the 
infra-temporal  crest  of  the  s])henoid  bone  to  end  in  the  deep  surfacu;  of  tlie  tem])oral 
nuiscle.  The  posterior  of  these  two  nerves  may  arise  in  common  with  the  mas- 
seteric nerve. 

(2)  The  masseteric  nerve  passes  between  the  l)one  and  the  external  pterygoid 
muscle  external  to  the  temporal  nerves,  and  accom])anies  the  masseteric  artery 
through  the  sigmoid  notch  of  the  mandible  to  be  distributed  to  the  masseter.      It 


Fig.  447.  — Distkihution  or  the  MANniBULAR  Division  oi-  tiik  TuKiK^iiN.u. 

Nerve.     (Henle.) 


LONG  BVCCAJ. 
NEHVI-: 


SUB- 

MANDIBULAI! 

GANGLION 

MENTA  L 

BRANCH 


ANTERIOR   TKM- 
I'ORAL  NERVE 

_  AVRICI'LO-TElM- 
I'ORAL  NERVE 
POSTERIOR  TEM- 
PORAL NERVE 


NERVE  TO   MAS- 
SETER 


CHORDA    TYM- 
PANI 

MYLO-nVOIl) 

NERVE 
LINGUAL 
NER  VE 

MANDIBULAR 
OR  INFERIOR 
DENT  A  I.  NER  VE 


may  be  readily  traced  through  the  deeper  fibres  of  tiie  masseter  nearly  to  tlie 
anterior  border  of  that  muscle.  As  it  emerges  from  under  cover  of  the  external 
pterygoid  it  gives  a  twig  to  the  t(*mporo-mandibular  articulation. 

(;>)  The  nerve  to  the  external  pterygoid,  after  a  course  of  about  an  eighth  of 
an  iiuih,  divides  into  twigs  which  enter  the  deep  surface  of  the  two  heads  of  the 
musck;.      It  is  usually  aclherent  at  its  origin  to  the  long  buccal  nerve. 

(4)  The  long  buccal  nerve  ])asses  between  the  two  heads  of  tlie  external  ]»tery- 
goid  nuiscle,  and  then  turns  forwards  and  emerges  from  undercover  of  the  temj)oral 
and  masseter  muscles  at  the  anterior  border  of  the  latter.  It  runs  forwards  and 
communicates  with  the  buccal  branch  of  the  facial,  being  in  this  situation  covere<l 
only  by  the  integument  and  fascia,  to  which  it  gives  branches;  then  it  pierces  the 
buccinator  muscle  and  ramifies  in  the  mucous  membrane  lining  the  cheek,  its.  ter- 
minal twigs  reaching  as  far  forwards  as  the  angle  of  the  mouth.      As  it  emerges 


758  THE   NERVOUS  SYSTEM 

I'rum  l>et\veen  the  heads  of  the  external  pterygoid,  it  gives  off  a  slender  twig  to  the 
temporal  niusel(\ 

The  POSTERIOR  PORTION  of  the  mandihiilar  division  of  the  fifth  nerve  divides 
into  three  large  branehes;  two  of  these,  the  auriculo-teniporal  and  the  lingual,  are 
exelusively  sensory;  the  remaining  branch,  mandil)ular  (inferior  dental),  contains 
a  strand  of  motor  fibres — the  mylo-hyoid  nerve. 

(1)  The  auriculo-temporal  nerve  arises  by  two  roots,  whicli  usually  embrace 
the  middle  meningeal  artery,  and  ])asses  backwards  and  outwards  between  the 
internal  lateral  ligament  of  the  temp()ro-mandil)ular  articulation  and  the  condyle  of 
the  mandible,  closely  eml)racing  the  ca])sular  ligaments  of  the  joint.  It  then  ascends 
under  cover  of  the  parotid  gland  and  traverses  the  glandular  substance  as  it 
crosses  the  root  of  the  zygoma.  It  accompanies  the  temporal  artery,  being  placed 
under  cover  of  and  slightly  behind  that  vessel,  and  terminates  at  the  level  of  the 
tragus  of  the  ear  by  dividing  into  auricular  and  temporal  branches.  As  it  passes 
through  the  parotid  gland  it  communicates  with  the  temporo-facial  division  of  the 
facial  nerve  by  two  stout  twigs,  which  may  surround  the  temporal  artery.  The 
auriculo-temporal  nerve  receives  conmiunicating  twigs  from  the  otic  ganglion,  and 
gives  off  the  articular  branch,  the  nerves  to  the  meatus,  and  the  parotid  branches. 
It  terminates  in  the  anterior  auricular  and  superficial  temporal  branches. 

(a)  The  communicating  twigs  from  the  otic  ganglion  join  the  nerve  close 
to  its  commencement  in  the  form  of  several  fine  filaments. 

These  filaments  have  been  shown  by  physiological  experiments  to  be  derived  from  the  glosso- 
pharyngeal nerve  through  the  lesser  superficial  petrosal.  They  run  for  a  short  distance  in  the 
trunk  of  the  auriculo-temporal,  and  leave  it  under  the  name  of  parotid  branches.  They  are  the 
secreto-motor  fibres  of  the  jiarotid  gland. 

(6)  The  articular  branch  is  supplied  to  the  temporo-mandibular  articulati(Mi 
as  the  auriculo-temporal  nerve  is  passing  between  the  capsular  ligament  and  the 
parotid  gland. 

(c)  The  nerves  to  the  meatus,  two  in  number,  pass  between  the  bony  and 
cartilaginous  parts  of  the  external  auditory  meatus  and  supply  the  skin  lining  the 
meatus.  The  upper  of  the  two  nerves  furnishes  a  filament  to  the  upper  and  anterior 
l>art  of  the  membrana  tympani.  The  lower  nerve  gives  twigs  to  the  lobule  of  the 
ear.  Occasionally  only  the  upper  nerve  is  present,  the  lower  being  replaced  by  a 
twig  from  the  great  auricular.      (Henle. ) 

(d  )  The  parotid  branches  are  a  variable  number  of  fine  twigs  which  arise  either 
directly  from  tlie  auriculo-temporal  nerve  or  from  the  loops  of  communication 
between  it  and  the  facial.    As  al  )ove  mentioned,  they  supply  the  glandular  sul)stance. 

(e)  The  anterior  auricular  branches,  two  in  numl)er,  are  sup|)lied  to  the 
upper  part  of  the  pinna,  and  are  chiefly  distributed  to  the  integument  which  coveis 
the  anterior  asjiect  of  the  tragus  and  helix. 

(/)  The  superficial  temporal  branches  divide  at  acute  angles  and  ramify 
over  the  integument  which  covers  the  temporal  fascia.  The  largest  twig  accom- 
})anies  the  posterior  branch  of  the  temporal  artery.  The  anterior  twigs  communi- 
cate with  the  tenijxiral  branches  of  the  facial  nerve. 

(2)  The  mandibular  (inferior  dental)  nerve  is  the  largest  branch  of  the 
mandil)ular  division.  It  passes  downwards  under  cover  of  the  external  pterygoid 
muscle  to  reach  the  interval  between  the  ramus  of  the  lower  jaw  and  the  spheno- 
mandibular  ligament.  In  this  situation  it  is  placed  on  the  outer  side  of  and  some- 
what l)ehind  the  lingual  nerve,  and  is  connected  to  the  latter  by  a  transverse  com- 
municating branch.  It  then  enters  the  mandibular  canal  accompanied  by  the 
mandibular  artery,  and  lies  at  first  behind  and  then  below  that  vessel  as  it  follows 
the  course  of  the  canal.  Opposite  the  mental  foramen  it  terminates  by  dividing 
into  an  incisive  and  a  mental  branch.  The  branches  of  the  inferior  dental  nerve 
are  the  mylo-hyoid,  the  alveolar,  tlie  incisive,  and  the  mental. 

(a)  The  mylo-hyoid  is  given  off  from  the  mandibular  nerve  immediately 
before  the  latter  enters  the  dental  canal.  It  runs  downwards  and  forwards  in  the 
mylo-hyoid  groove  of  the  mandible  between  the  bone  and  the  internal  pterygoid 
muscle.  In  this  course  it  is  accompanied  by  the  mylo-hyoid  artery.  It  then  runs 
forwards  on  the  inferior  surface  of  the  mylo-hyoid  muscle,  under  cover  of  the  sub- 


MASDIBULAR  DIVISIOX  OF  THE  FIFTH  NERVE  7oO 

maxillary  _irlan(l  and.  after  su))iilying  the  iniisc-lc  with  several  twigs,  it  pierces  the 
anterior  helly  of  the  digastric,  in  the  sul)stanee  of  wliieh  it  ends. 

(b)  The  alveolar  branches  are  a  series  of  twigs  which  are  given  off  within  the 
mandihular  canal  to  sui)]>ly  the  molar  and  bicuspid  teeth.  They  connnunicate  with 
one  another  within  the  bone,  forming  a  fine  plexus.  From  this  plexus  twigs  are 
given  off  corresponding  in  numl)er  to  the  fangs  of  the  teeth;  they  enter  the  minute 
apert\n-es  at  the  ti]is  of  the  fangs  and  end  in  the  })ulp.  Twigs  are  also  given  to  the 
adjacent  part  of  the  gums  (nervi  gingivales). 

(c)  The  incisive  branch,  the  smaller  of  the  two  terminal  divisions,  is  continued 
forwards  and  inwards  in  tlie  dental  canal,  and  sup])lies  the  canine  and  incisor  teeth 
and  the  corresponding  region  of  the  gums. 

((/)  The  mental  branch  is  a  nerve  of  considerable  size  which  emerges  through 
the  mental  foramen.  It  communicates,  near  its  exit,  with  the  supramandilndar 
branch  of  the  facial  nerve,  and  then  divides  into  three  branches.  The  smallest 
branch  turns  downwards  to  supply  the  chin.  The  other  two  pass  upwards,  diverg- 
ing as  they  ascend,  and  divide  into  a  number  of  twigs.  The  stoutest  twigs  ramify 
upon  the  mucous  membrane  which  lines  the  lower  lip.  Other  twigs  are  distributed 
to  the  integument  and  fascia  of  the  li]i  and  chin. 

(8)  Tlie  lingual  (formerly  called  gustatory)  nerve  is  slightly  smaller  than  the 
mandibular  nerve,  and  is  placed  at  first  in  front  of  and  close  to  the  inner  side  of 
the  latter  under  cover  of  the  external  i)terygoid  muscle.  In  this  situation  it  is 
joined  by  the  chorda  tympani  nerve;  the  latter  enters  the  lingual  on  its  outer  side, 
the  two  nerves  uniting  at  an  acute  angle.  The  lingual  then  escai^es  from  under 
cover  of  the  external  pterygoid  muscle,  and  is  connected  to  the  mandibular  nerve 
by  a  transverse  communicating  branch.  It  then  passes  between  the  ramus  of  the 
mandible  and  the  internal  pterygoid  muscle,  and  is  continued  forwards  l)etween  the 
nuicous  membrane  of  the  mouth  and  the  mylo-hyoid  muscle,  and  lies  on  the  origin 
of  this  nuiscle  close  to  the  bone.  In  this  )>art  of  its  course  it  can  be  easily  divided 
by  an  incision  through  the  mucous  membrane  at  the  level  of  the  second  lower 
molar  tooth.  It  then  runs  between  the  mylo-hyoid  and  hyo-glossus  muscles, 
crosses  below  Wharton's  duet,  and  finally  courses  forwards  by  the  side  of  the 
tongue,  so  as  to  reach  the  tip  of  that  organ.  As  it  crosses  the  hyo-glossus  muscle 
it  fonns  a  curve  with  the  convexit}'  directed  downwards,  and  is  connected  at  the 
most  dependent  part  of  the  curve  to  the  submandibular  (submaxillary)  ganglion,  to 
which  it  furnishes  sensory  roots.  Immediately  l)eyond  the  ganglion  it  communi- 
cates freely  with  the  hypoglossal  nerve,  the  communications  forming  several  loops. 

Branches. — (a)  Connnunicating  branches  are  given  to  the  mandiltular  nerve, 
to  the  submaxillary  ganglion,  and  to  the  hypoglos.'^al  nerve.  These  have  already 
been  described. 

(b)  Twigs  are  distributed  to  the  interval  between  the  tongue  and  gums,  and 
ramify  in  the  mucous  membrane  of  the  floor  of  the  mouth. 

(c)  A  twig  enters  the  sublingual  gland.  This  twig  conveys  secreto-motor  fibres 
from  the  chorda  tympani  to  the  gland. 

(d  )  The  lingual  V)ranches  are  a  series  of  twigs  Avhich  are  given  off  by  the  lingual 
nerve  in  the  last  stage  of  its  course  as  it  i«  ])assing  forwards  towards  the  tip  of  the 
tongue.  They  pierce  the  musculature  at  the  side  of  the  tongue,  and  jiroceed  to  the 
dorsum  of  the  nn'ddle  and  anterior  ]>art  of  that  organ.  Avhere  they  end  in  the  filifonn 
and  fungiform  paiiilbe. 

SlBMANTHBlLAR    (PuBMAXILLARV)  GaNOLIOX 

The  submandibular  ganglion  is  a  small  reddish  fusiform  body  which  is  placed 
between  the  mylo-hyoid  and  hyo-glossus  muscles  above  Wharton's  duct.  It  is 
connected  with  the  lingual  nerve  by  two  communications,  an  anterior  and  a  posterior. 
The  posterior  communication  contains  the  motor  and  sens(»rv  roots  of  the  ganglion. 
The  anterior  communication  represents  a  branch  ]»assing  from  the  ganglion  to  the 
lingual  nerve.  The  motor  root  is  derived  from  the  dutrda  tympani.  The  ser.sorv 
root  is  furnished  by  the  lingual.  The  ganglion  also  receives  a  sympathetic  root 
from  the  ]>lexus  of  the  sympathetic  which  accompanies  the  facial  artery. 

Branches. — The  ganglion    furnishes  live   (jr  six   twigs  to  the  submandibular 


760  THE  NERVOUS  SYSTEM 

(submaxillary)  gland,  and  gives  minute  twigs  to  Wharton's  duct,  which  accompany 
the  duct  to  its  termination.  From  the  fore  part  of  the  ganglion  a  branch  passes  to 
the  lingual  nerve,  and  through  this  branch  fibres  from  the  chorda  tympani  are 
conveyed  to  the  sublingual  gland  and  to  the  tongue. 

Sublingual  ganglion. — A  small  ganglion  has  been  described  l)y  Blandin  an«l 
others  on  the  twig  to  the  sublingual  gland.     According  to  Bose,  it  is  not  constant. 


Otic  Gaxgliox 

The  otic  ganglion,  or  ganglion  of  Arnold,  is  a  small  reddish-grey  body  which 
is  placed  innnediately  l)elow  the  foramen  ovale,  internal  to  the  mandibular  division 
of  the  trigeminal  nerve.  The  cartilage  of  the  Eustachian  tube  and  the  tensor 
tympani  muscle  are  placed  close  to  its  inner  side,  and  the  middle  meningeal  artery 
is  behind  it.  The  ganglion  is  oval  in  form,  and  compressed  in  its  coronal  diameter. 
It  is  greatest  in  its  sagittal  diameter,  Avhicli  is  aljout  four  millimetres. 

Roots. — The  mandibular  division  of  the  trigeminal  nerve  supplies  one  or  mor(^ 
roots  to  the  otic  ganglion;  these  roots  probably  contain  both  sensory  and  motor 
fibres,  and  are  associated  with  the  nerve  to  the  internal  pterygoid.  The  lesser 
superficial  petrosal  nerve  enters  the  ganglion,  being  a  motor  root.  The  ganglion 
receives  a  sympathetic  root  from  the  plexus  which  surrounds  the  middle 
meningeal  artery. 

Branches. — The  otic  ganglion  furnishes  muscular  twigs  to  the  tensor  palatiand 
tensor  tympani;  these  twigs,  especially  the  former,  pass  for  the  most  part  from  the 
mandibular  division  of  the  fifth  nerve  to  the  nuiscles  without  interrujition  in  the 
nerve-cells  of  the  ganglion.  It  also  gives  communicating  branches  to  the  auriculo- 
temporal, the  chorda  tympani,  and  to  the  Vidian  nerves. 


SIXTH  OR  ABDUCENT  NERVE 

The  sixth  or  abducent  nerve  arises  from  an  ai)i)roximately  spherical  cluster  of 
nerve-cells  which  is  i^Iaced  l)etween  the  grey  matter  of  the  floor  of  the  fourth 
ventricle  and  the  formatio  reticularis.  This  nucleus  is  situated  near  the  middle 
line,  a  little  in  front  of  the  striae  acusticse,  and  corresponds  to  the  eminentia  teres. 
It  is  on  a  line  with  the  nuclei  of  the  third  and  fourth  nerves.  The  fibres  which 
arise  from  it  plunge  forwards  and  downwards  through  the  substance  of  the  pons, 
and  emerge  at  the  lower  border  of  the  latter  structvu-e  (superficial  origin).  Some 
of  the  fibres  pass  througli  the  pyramidal  body;  others  pass  out  in  the  interval 
between  the  latter  and  the  olivary  body. 

The  stKth  nerve  was  formerly  described  as  giving  fibres  of  origin  to  tLe  facial,  but  Gudden 
and  (jrowers  have  shown  that  this  is  not  the  case.  A  remarkable  strand  of  fibres  passes  from  the 
abdueens  nucleus  to  the  posterior  longitudinal  bundle.  It  runs  brainwards,  forming  tlie  inner 
border  of  the  bundle,  and  decussates  below  the  corpora  quadrigemina  with  its  fellow  of  the 
opposite  side  ;  it  then  joins  the  third  nerve,  and  passes  eventually  into  the  internal  rectus  muscle. 
Thus  the  eyes  can  be  directed  to  the  right  or  left,  as  the  case  maj'  be,  by  the  action  of  a  single 
nucleus,  e.  g.  in  turning  the  eyes  to  the  right,  the  right  external  rectus  and  the  left  internal 
rectus  are  used,  and  these  are  both  supplied  by  the  right  abducens  nucleus. 

The  sixth  nerve  pierces  the  dura  mater  at  a  point  a  little  above  the  junction  of 
the  basilar  process  of  the  occipital  bone  with  the  sjihenoid.  It  runs  u})wards 
between  the  pons  and  the  V)ody  of  the  sphenoid  and  at  the  side  of  the  basilar  artery, 
and  turns  forwards  in  the  interval  between  the  apex  of  tlie  petrous  portion  of  the 
temporal  bone  and  the  posterior  clinoid  process  of  the  sphenoid,  passing  in  this 
situation  under  cover  of  a  ligament  which  connects  the  osseous  jirominences  above 
mentioned.  It  enters  the  flocH-  of  the  cavernous  sinus,  and  passes  on  to  the  outer 
.side  of  the  internal  carotid  artery.  In  this  situation  it  receives  several  communi- 
cations from  the  carotid  plexus  of  the  sympathetic.  It  enters  the  orbit  through 
the  sphenoidal  fissure,  ])assing  between  the  inferior  division  of  the  third  nerve  and 
the  ophthalmic  vein,  in  the  interval  between  the  two  heads  of  the  external  rectus 
muscle,  and  ends  by  piercing  the  ocular  surface  of  that  muscle. 


FACIAL   SERVE 


761 


SEVENTH  OR  FACIAL  NERVE 

The  seventh  (jr  facial  nerve  is  formed  by  two  distinct  parts — the  main  trunk, 
or  facial  nerve  proper,  and  an  accessory  ]>ortion,  the  pars  intermedia  of  \\'risl)er<f. 
Tlie  facial  nerve  jjroper  arises  from  an  elongated  nucleus  which  is  deeply  j^laced  in 
tlie  reticular  formation  of  the  pons  below  the  Hoor  of  the  fourth  ventricle.  This 
nucleus  commences  at  the  level  of  the  striae  acustic«,  and  extends  brainwards  for 
al)out  four  millimetres.  The  fibres  which  arise  from  it  ])ursue  a  remarkal)ly  tortuous 
course  within  the  sul»stance  of  the  ]>ons.  At  first  they  i)ass  Ijackwards  and  inwards 
so  as  to  approach  the  ependyma  of  tlie  Hoor  of  the  fourth  ventricle  close  to  the 
sulcus  longitudinalis  niedianus  (crus  of  origin).  They  then  run  upwards  and  for- 
wards in  a  compact  l)undle  (  fasciculus  teres,  or  ascending  crus),  which  produces 
an  elevation  (eminentia  teres)  on  the  Uoor  of  the  fourth  ventricle  immediately 
external  to  the  median  fissure.  The  bundle  of  fibres  then  l)ends,  and  is  directed 
at  right  angles  to  its  former  course;  it  arches  outwards  over  the  nucleus  of  the 
sixth  nerve,  and  passes  forwards,  outwards,  and  chjwn wards  (issuing  crus).  In 
this  part  of  its  course  it  passes  to  the  outer  side  of  its  own  nucleus,  l)etween  the 
latter  and  the  ascending  root  of  the  fifth  nerve.  Finally  it  emerges  at  the  lower 
l)()rder  (jf  the  pons  in  the  interval  between  the  olivary  and  restiform  liodies  f  super- 
ficial origin). 

From  the  above  description,  it  will  Ix'  seen  that  the  facial  nerve  embraces  the 


Fi(i.  44s. — Dia(;ramm.\tic  Lateral  View  of  the  Origin  ok  the  Facial  Nkkve.      Kmuse. ) 


SUPERIOR  OLIVE 
ASCEXDiyO  CEL'S 

yrCLEl.S  OF  A  BDUCEXS 
CRCS  OFORIOIN 

yiCLEIS  OF  FACIAL 
MEIU'LLA 


POXS 


OLIVARY  NUCLEUS 


nucleus  of  the  abducens;  the  term  genu  nervi  facialis  internus  is  applierl  to  the 
nerve  in  this  part  of  its  course.  Within  the  substance  of  the  i)ons  the  issuing  root 
t^f  the  facial  nervx'  is  joined  l)y  fibres  from  the  oculo-motor  and  hypoglossal  nuclei 
which  pass  to  it  by  means  of  the  posterior  longitudinal  bundle.  The  fibres  from 
the  oculo-motor  nucleus  are  distributed  by  the  temporal  ])ranches  of  the  facial 
nerve  to  the  corrugator  supercilii,  the  upper  part  of  the  orbicularis  paljiebrarum  and 
to  the  frontalis  muscles,  whilst  the  fibres  received  from  the  hy]>oglossal  are  said  to 
sup])ly  the  orbicularis  oris. 

T\\{'  pars  intermedia  of  ^A^risbe^g  arises  from  the  extreme  upper  i  ]»roximal) 
end  of  the  sensory  nucleus  of  the  glosso-pharyngeal  nerve  (Duval).  Its  fibres 
]>ass  obli(juely  through  the  substance  of  the  pons,  and  emerge  at  the  lower  border 
of  the  last-named  structure  innnediately  external  to  the  facial  nerve,  between  the 
latter  and  the  auditory  nen'e  (suj)erficial  (jrigin).  Thence  the  nerve  ])asses,  in  the 
form  of  a  small  compact  bundle,  and  enters  the  internal  auditory  meatus.  In  this 
situation  it  lies  on  the  upper  surface  of  the  auditory  nerve,  while  the  facial  is 
placed  above  it.  It  joins  the  facial  nerve  at  the  commencement  of  the  geniculate 
ganglion. 

This  nerve  is  rocardorl  as  an  aberrant  fasciculus  of  the  trl()Sso-iihar3'iigcal  nerve,  an<l  aiMi- 
tional  support  is  siven  to  this  view  hy  the  fact  that  it  also  receives  fibres  from  the  funiculus 
solitarius  (Testut).  The  chorda  tyui|)ani  is  usually  regarded  as  the  coutiuuatiou  of  it,  and  thus 
the  anterior  part  of  the  tongue  receives  fibres  from  the  glosso-pharyugeal  through  the  chorda 


762  THE  XERVOrS  SYSTEM 

tyiupaiii,  while  the  posterior  part  of  the  organ  is  supplied  directlj'.     (See  Glosso-piiakvn»;kai- 
2S  ERVE. ) 

At  its  superficial  origin  the  facial  nerve  is  placed  immediately  internal  to  tlx- 
auditory  nerve,  the  pars  intermedia  of  A\'risl»erg  intervening  l)etween  them.  As 
the  facial  nerve  enters  the  internal  auditory  meatus,  it  is  placed  above  the  auditory 
nerve.  It  then  parts  company  with  the  auditory  nerve  by  entering  the  aqueduct 
of  Fallo})ius.  While  traversing  the  aqueduct,  it  necessarily  follows  the  windings 
of  that  canal.  It  passes  at  first  outwards  and  forw^ards  through  the  bone  above 
and  between  the  cochlea  and  the  vestibule.  It  then  makes  a  sharp  bend,  and  runs 
backwards  and  slightly  downwards,  being  separated  from  the  tym})anum  in  this 
j)art  of  its  course  only  by  a  very  thin  scale  of  bone  and  by  the  mucous  membrane 
lining  the  cavity.  Lastly,  it  runs  directly  downwards,  and  emerges  at  the  stylo- 
mastoid foramen.  The  portion  of  the  nerve  corresponding  to  the  first  bend  is 
c()iisideral)ly  thickened,  and  contains  some  nerve-cells;  it  is  called  tlie  geniculate 
ganglion.  The  ganglionic  substance  forms  a  little  conical  cap  on  the  bend  of  tlie 
nerve,  the  apex  of  the  cone  being  directed  towards  the  hiatus  Fallo}>ii. 

After  its  emergence  from  the  stylo-mastoid  foramen,  the  facial  nerve  runs 
downw^ards  and  forwards  within  the  substance  of  the  parotid  gland,  and  terminates 
by  dividing  into  two  divisions — an  upper  or  temporo-facial,  and  a  loAver  or  cervi(v-»- 
facial. 

The  branches  of  the  facial  nerve  may  be  classified  into  three  sets: — (1 )  Branches 
given  off  within  the  aipteduct  of  Fallopius;  (2)  branches  from  the  extracranial 
portion  of  the  nerve  before  its  terminal  division;  (3)  branches  of  the  temporo-facial 
and  cervico-facial  divisions. 

(1)  Six  branches  are  given  off  within  the  aqueduct:  viz.  three  from  the  genicu- 
late ganglion,  the  great,  the  lesser,  and  the  external  superficial  petrosal  nerves; 
and  three  from  the  facial  nerve  in  the  descending  part  of  its  course — viz.  the  nerve 
to  the  stapedius,  the  chorda  tympani,  and  a  communicating  twig  to  the  pneumo- 
gastric. 

(a)  The  great  superficial  petrosal  nerve  receives  a  communicating  filament 
from  the  tympanic  liranch  of  the  glosso-})haryngeal,  and  leaves  the  acjUeduct  by 
])assing  through  the  hiatus  Fallopii.  It  runs  f(jrwards  and  inwards  in  a  groove  on 
the  petrous  portion  of  the  temporal  bone  under  cover  of  the  dura  mater.  It  passes 
beneath  the  Gasserian  ganglion,  and  pierces  o))liquely  the  cartilaginous  substance 
which  occupies  the  foramen  lacerum  medium;  here  it  is  joined  by  the  great  deej) 
petrosal  nerve,  and  forms,  with  the  latter,  the  Vidian  nerve  as  already  described. 

(6)  The  lesser  superficial  petrosal  nerve  arises  from  the  geniculate  ganglion 
external  to  the  preceding.  It  receives  a  relatively  large  communication  from  the 
tympanic  branch  of  the  glosso-pharyngeal.  This  conmiunication  is  often  considered 
to  l)e  the  main  root  of  the  nerve  (Schw^albe  and  others).  It  leaves  the  a(iueduct 
through  a  canal  which  is  placed  external  to  the  hiatus  Fallopii,  and  passes  forwards 
for  a  short  distance,  lying  in  a  groove  in  the  bone,  under  cover  of  the  dura  mater. 
It  escapes  from  the  cranium  through  a  small  foramen  situated  between  the  foramen 
ovale  and  the  foramen  spinosum  (canalis  innominatus),  and  enters  the  otic  ganglion. 
Occasionally  it  leaves  the  skull  by  traversing  the  suture  between  the  great  wing  of 
the  sphenoid  and  the  petrous  portion  of  the  tenq^oral  bone,  or  by  passing  through 
the  foramen  ovale. 

(c)  The  external  superficial  petrosal  is  the  smallest  of  the  three  petrosal 
nerves.  It  passes  through  a  minute  canal  in  the  temporal  bone  immediately  external 
to  the  point  of  emergence  of  the  lesser  su})erficial  nerve.  It  then  runs  forwai-ds. 
under  cover  of  the  dura  mater,  and  joins  the  j^lexus  of  the  sympathetic  on  the  miildle 
meningeal  artery  close  to  the  forammi  spinosum. 

(rf)  The  nerve  to  the  stapedius  is  a  minute  twig  which  is  given  oft'  by  the 
facial  nerve  immediately  below  the  second  bend  which  the  nerve  forms  within  the 
arjueduct.  It  passes  through  a  small  canal  leading  from  the  aqueduct  to  the  interior 
of  tlie  pyramid,  and  ends  in  the  muscular  sul)stance  of  the  stapedius. 

(g)  The  chorda  tympani  arises  from  the  facial  nen'e  about  five  millimetres 
above  the  stylo-mastoid  foramen.  It  pursues  a  slightly  recui'rent  course,  iq)wards 
and  forwards,  through  the  iter  chorda"  posterius.  and  thus  enters  the  tyni])anum. 


FACIAL   yEJiVE 


r63 


It  crosses  the  menibrana  tvnii)ani  at  the  junction  of  the  upper  and  middle  thirds  of 
that  membrane.  In  this  part  of  its  course  it  runs  forwards  between  the  fil^rous  and 
mucous  layers  of  the  mend>rana  tymj)ani,  ])assing  on  the  inner  side  of  the  manu- 
brium of  the  malleus.  It  leaves  the  tymj)anum  by  ])assin<r  throu<rh  the  iter  chordje 
anterius,  or  canal  of  HuLMiier.  crosses  the  inner  side  of  the  spine  of  the  sj)lienoid  in 
the  groove  described  by  Mr.  Lucas,  and,  after  connnunicating  with  the  otic  gan- 
glion, passes  forwards,  under  cover  of  the  external  ])terygoid  muscle,  to  gain  the 
outer  side  of  the  lingual  nerve,  which  it  joins  at  an  acute  angle.  Thence  it  runs  in 
the  sheath  of  the  lingual  n(;rve,  a  })ortion  of  its  fibres,  as  already  descriljed  (see 
Lingual  Nerve),  passing  into  the  submandibular  ganglion.  Other  fibres  reach  the 
sul)lingual  gland,  and  the  dorsum  of  the  tongue. 


Fig.  449.— Supeefici.vl  DisTHiurTiox  of  the  Facial  and  othek  Nerves  of 
THE  Head.     (After  Hirschfeld  and  Leveille.) 


SUPRA-ORBITA  L 

F.ILPKHRALTWIG 
OF  LACHRYMAL 

ISFKA TROCHLKA R 

TEMPORA  L 
HRAyCII  OP 
SEVES 


MALAR  BR. 

OF  SEVEXTH 

MAXILLARY 

I)l\:  OF  FIFTH 

IXFRA- 

ORBITAL 

BR.  OF  a  EVE. 


BrrCAL  HRAXr 
OF  ."EtEXr// 


MEXTAL  bra: 
OF  MAXDIBCL 


SrPRA-MAXniB 
BRAXrjI  OF 


POSTER 10 R 
AURICULAR 

A  URICULO- 
TEMPORAL 

GREA  T 
OCCIPITAL 

FACIAL 


LESSER  OCCIPITAL 
GREAT  A  URICULAR 


SUFERFICIAL 
CERVICAL 


(/)  The  communicating  twig  to  the  pneumogastric  is  given  of¥  at  the  same 
level  as  the  cliorda  tyiiipani.  and  joins  the  nuricular  branch  of  tlie  pneunH)gastric 
while  the  latter  is  traversing  the  substance  of  the  temporal  bone. 

(2)  The  branches  whicli  arise  from  the  facial  nerve  lietween  the  stylo-mastoid 
foramen  and  the  terminal  bifurcation  are  the  posterior  auricular  and  the  nerves  to 
the  posterior  belly  of  the  di<rastrie  and  to  the  .^tylo-hyoid  muscles.  A  lingual  l>rancli 
is  also  desen])ed. 

(a)  The  posterior  auricular  nerve  is  the  first  branch  of  the  extracranial  por- 
tion of  the  facial.  It  passes  Ix'tween  the  parotid  gland  and  the  anterior  border  of 
the  sterno-mastoid  muscle,  and  runs  ui)wards  in  the  deep  interval  between  tlie 


764  THE   XER VOL'S  SYSTEM 

external  aiulitorv  meatus  and  tlie  mastoid  proeess.  In  this  situation  it  eonmiuni- 
cates  with  the  auricular  branch  of  tlie  pneumogastric.  It  supplies  the  retraliens 
aurem,  and  sends  a  slender  twig  upwards  to  the  attollens  aurem,  and  ends  in  a  long 
slender  branch,  Avhich  passes  backwards  to  sui)plythe  ])ostcrior  belly  of  the  occipito- 
frontalis.  It  also  receives  filaments  from  the  small  occipital  and  ])osterior  auricular 
nerves,  and  supplies  the  oblique  and  transverse  muscles  on  the  inner  surface  of 
the  pinna. 

(6)  The  nerve  to  the  posterior  belly  of  the  digastric  arises  from  the  facial 
nerve  close  to  the  stylo-mastoid  foramen,  and  enters  the  digastric  near  the  centre  of 
that  muscle,  or  sometimes  near  its  origin.  It  frequently  communicates  with  the 
glosso-pharyngeal  nerve. 

(c)  The  nerve  to  the  stylo-hyoid  arises  at  the  same  level  as  the  preceding 
nerve,  the  two  nerves  sometimes  forming  a  common  trunk.  It  ends  in  the  upper 
part  of  the  muscle  for  which  it  is  destined. 

The  lingual  branch  is  remarkable  fur  its  lung  course.  It  arises  close  to  the  two  small  muscular 
uerves  above  described.  It  pa.sses  ou  the  outer  side  of  the  stj'lo-pharj-ngeus  muscle,  and  gains 
the  side  of  the  phar3'nx.  In  this  situation  it  is  joined  by  filaments  from  the  glosso-pharyngeal. 
It  then  passes  between  the  palato-glossus  muscle  and  the  tonsil,  and  reaches  the  base  of  the 
tongue,  where  it  ends  in  filaments  to  the  mucous  membrane  and  in  twigs  to  the  palato-glossus 
and  stylo-glossus  muscles.     (Testut.) 

(3)  Six  branches  are  given  off  from  the  two  terminal  divisions  of  the  facial 
nerve.  These  branches  traverse  the  substance  of  the  jjarotid  gland,  and  emerge  at 
its  margin.  At  their  emergence  they  range  from  a  point  on  the  zygoma,  a  little  in 
front  of  the  spot  where  the  temporal  artery  crosses  the  bone,  to  the  angle  of  the 
lower  jaw.  These  branches  proceed  forwards  over  the  face  and  front  of  the  neck, 
and  by  frequently  communicating  with  one  another  form  a  great  expanded  plexus 
which  is  called  the  pes  anserinus.  Taken  in  order  from  above  downAvards,  the 
temporo-facial  division  gives  off  the  following  branches:  temporal,  malar,  and 
infraorbital.  The  cervico-facial  division  divides  into  buccal,  supra-mandilndar  and 
infra-mandibular  branches. 

The  TEMPORO-FACIAL  DIVISION  of  the  facial  nerve  runs  obliquely  upAvards 
and  forwards  through  the  substance  of  the  parotid  gland,  crosses  the  external  carotid 
artery  and  the  temporo-maxillary  vein  on  the  superficial  aspect  of  those  vessels,  and 
terminates,  as  above  described,  in  three  branches. 

In  this  course  it  receives  communications  from  the  auriculo-temporal  nerve,  as 
mentioned  in  the  description  of  the  fifth  nerve. 

(a)  The  temporal  branch  passes  upwards  through  the  parotid  gland,  and 
emerges  at  the  upper  border  of  the  gland  at  a  point  a  little  in  front  of  the  temporal 
artery.  It  divides  into  several  branches,  which  communicate  with  one  another  and 
with  the  malar  branch.-  It  also  communicates  with  the  temporal  branch  of  the 
orbital,  and  with  the  supraorbital  nerve.  Its  largest  l)ranches  are  distributed  to  the 
upper  part  of  the  orbicularis  palpebrarum,  and  to  the  anterior  belly  of  the  occijnto- 
frontalis.  It  also  supi3lies  the  attrahens  aurem,  th(^  corrugator  supercilii,  and, 
occasionally,  the  attollens  aurem. 

The  fibres  which  run  in  the  facial  nerve  to  end  in  the  orbicularis  palpebrarum,  the  cornigator 
supercilii,  and  the  frontalis  muscles  are  probably  derived  from  the  oculo-motor  nucleus  of  the  same 
side,  and  pass  downwards  in  the  posterior  longitudinal  bundle  to  ioin  the  genu  nervi  facialis. 
(Mendel.) 

(b)  The  malar  branch  is  a  smaller  neiwe  than  the  preceding.  It  is  directed 
upwards  and  forwards  to  reach  the  most  prominent  part  of  the  malar  bone;  it 
supplies  the  lower  part  of  the  orbicularis  palpebrarum.  It  also  gives  twigs  to  both 
eyelids;  it  communicates  with  the  malar  branch  of  the  orbital,  Avith  the  supra- 
orbital and  lachrymal  branches  of  the  ophthalmic,  with  the  palpebral  tAvigs  derived 
from  the  superior  maxillary  division  of  the  fiftli.  and  witli  the  temporal  and  infra- 
orbital branches  of  the  facial. 

{(•)  The  infraorbital  is  the  largest  of  the  nerves  which  enter  into  the  })es  anser- 
inus. It  escajies  from  the  })arotid  gland  above  Stenson's  duct,  and  diA'ides  into 
seA'eral  branches.      These  branches  comii)uni<'ate  freely  with  one  another,  and  ]>ass 


FACIAL   yERVE—AVDITORY  XERVE  765 

inwards  on  the  deoi)  surface  of  tlie  zygoniatici  and  the  levator  lahii  superioris. 
Under  cover  of  the  latter  muscle  they  communicate  with  the  terminal  branches  of 
the  superior  maxillary  division  of  the  fifth  nerve,  formin<i  the  infraorbital  plexus  ; 
thence  twigs  extend  to  the  nose,  and  communicate  with  the  nasal  hrandi  of  tln^ 
o])hthalniic  nerve.  The  infraorlntal  hranch  also  forms  communications  with  other 
branches  of  the  facial,  namely  with  the  malar  above  and  with  the  Ituccal  below.  It 
sui)i)lies  the  zygomatici,  the  levator  labii  superioris,  the  levator  labii  sujterioris 
aliesiue  nasi,  the  levator  anguli  oris,  the  pyramidalis  nasi,  the  compressor  nasi,  and 
the  depressor  ala;  nasi.  It  also  gives  twigs  to  the  buccinator  and  to  the  orbicularis 
oris. 

The  CERVICO-FACIAL  DIVISION  of  the  facial  nerve  is  directed  forwards  and 
downwards  through  the  parotid  gland,  and,  like  the  temporo-facial  division,  it 
crosses  on  the  outer  side  of  the  external  carotid  artery.  As  it  traverses  the  glandu- 
lar substance  it  communicates  with  the  facial  branches  of  the  great  auricular  nerve. 
As  above  descril)ed,  it  terminates  in  three  branches:  the  buccal,  the  supra-mandi- 
bular,  and  the  infra-mandibular. 

(a)  The  buccal  branch  is  of  small  size,  and  is  the  highest  of  the  three  l)ranches 
of  the  cervico-facial  division.  It  is  placed  between  the  infraorbital  and  supra- 
mandibular  branches  of  the  facial,  and  communicates  Avith  both  these  branches. 
It  emerges  from  the  parotid  gland  below  Stenson's  duct,  and  crosses  the  masseter 
muscle.  In  front  of  the  anterior  border  of  the  masseter,  it  communicates  wdth  the 
long  buccal  branch  of  the  fifth,  and  then  breaks  into  twigs,  which  end  in  the 
buccinator  and  orl)icularis  oris. 

{}))  The  supra-mandibular  branch,  after  escaping  from  the  parotid  gland, 
crosses  the  loAver  part  of  the  masseter  muscle,  a  little  way  above  the  angle  of  the 
lower  jaw,  and  j^asses  forwards,  under  cover  of  the  risorius  and  the  depressors  of 
the  lower  lip,  as  far  as  the  middle  line.  It  communicates  with  the  buccal  and 
infra-mandibular  branches  of  the  facial,  and  with  the  mental  branch  of  the  man- 
dil)ular  nerve.  It  supplies  the  risorius,  the  depressor  anguli  oris,  the  depressor 
labii  inferioris,  and  the  levator  menti. 

(c)  The  infra-mandibular  branch  becomes  superficial  at  the  lower  margin  of 
the  parotid  gland,  and  runs  ol)li(piely  downwards  and  forwards,  under  cover  of  the 
)ilatysma,  across  the  side  and  front  of  the  neck.  It  forms  one  or  more  communi- 
cating loops,  near  its  commencement,  with  the  great  auricular  nerA'e,  and  longer 
loops,  lower  down,  with  the  superficial  cervical  nerve.  It  supplies  the  platysma 
my  (tides. 

EIGHTH  OR  AUDITORY  NERVE 

The  auditory  nerve  appears  at  the  lower  border  of  the  pons  (superficial  origin), 
innnediately  external  to  the  facial  nerve.  It  arises  by  two  roots,  a  lateral  and  a 
mesial.  These  roots  embrace  the  restiform  body,  the  lateral  root  being  extern;d. 
and  the  mesial  root  internal  to  that  body  (fig.  450).  The  lateral  root  ( su])erficial, 
dorsal,  inferior,  or  posterior  root)  is  continuous  with  the  cochlear  nci-vi-,  and  is  the 
true  nerve  of  hearing;  while  the  mesial  root  (deep,  ventral,  superior,  or  anterior 
root)  is  continued  into  the  vestibular  nerve,  and  is  concerned  in  the  maintenance 
of  eciuilibriuni.      The  mielei  in  connection  with  these  roots  will  be  first  described. 

The  small-celled  or  chief  nucleus  is  superficially  placed  in  the  floor  of  tht> 
fourtli  ventricle.  It  is  largest  in  the  region  of  the  strife  medullares,  in  which 
situation  it  appears  in  coronal  sections  as  a  triangular  grey  mass,  which  reaches  the 
middle  line.  It  extends  forwards  from  this  point  as  far  as  the  al)ducens  nucleus 
and  l)ackwards  for  about  an  ecjual  distance.  Both  in  front  and  behind  it  recedes 
from  the  middle  line.      The  nerve-cells  forming  this  nucleus  are  all  of  small  size. 

The  large-celled  or  Deiters'  nucleus  is  placed  close  to  the  inner  side  of  the 
restiform  bodv.  It  is  al)out  the  same  length  as  the  small-celled  nucleus,  Itut 
occupies  a  position  deeper  and  further  forwards  tlian  the  latter.  The  cells  of  this 
nucleus  are  of  large  size,  and  are  most  numerous  at  the  anterior  ])art.  It  degene- 
rates after  destruction  of  the  upper  cervical  region  of  the  cord  or  of  the  lateral  lobe 
of  the  cerebellum  of  the  same  side,  therefore  it  must  have  close  associatiojis  with 
these  parts,  Init  it  is  probably  unconnected  with  tlie  auditory  nerve. 


766 


THE   XERVOrS  SYSTEM 


The  accessory  nucleus  (lateral  or  ventral  nucleus)  is  a  group  of  cells  chiefly 
contained  witliin  the  lateral  root,  but  also  occupying  the  angular  interspace  between 
the  lateral  and  the  mesial  roots.  It  presents  marked  affinities  to  a  spinal  nerve- 
ganglion,  particularly  in  the  character  of  the  nerve-cells  in  its  anterior  (sui)erior) 
part.  Some  of  the  fibres  which  spring  from  it  pass  tlirough  tlie  trapezium  to  the 
tillet  of  the  opposite  side,  l)y  means  of  which  they  reacli  the  posterior  C[Uadrigemi- 
nate  body,  whilst  others  terminate  in  the  upper  olive  of  the  same  and  the  op])osite 
sides. 

Lateral  root. — The  lateral  root  arises  chiefly  from  the  cells  of  the  accessory 
nucleus,  but  a  certain  number  of  fibres  are  believed  to  pass  by  that  nucleus  with- 
out interruption.  Both  sets  of  fibres  travel  in  a  tolerably  compact  bundle  around 
the  outer  side  of  the  restiform  body.  A  certain  number  take  origin  in  the  cells  of 
the  tuberculum  acusticum,  the  others  cross  the  floor  of  the  fourth  ventricle,  as  striae 
mcdullares,  and,  having  crossed  the  middle  line,  take  origin  partly  in  the  so-called 
nucleus  funiculi  teretis  of  the  opposite  side,  and  pass  partly  into  the  conductor 
sonorus.  The  origin  of  the  conductor  sonorus  is  unknown;  its  course  has  l)een 
noticed  in  the  description  of  the  fourth  ventricle  (page  719). 

Mesial  root. — This  root  passes  to  the  inner  side  of  the  restiform  body  and  has 


Fig.  450. — Transverse  Section  of  the  Pons,  passino  TiiRorciu  the  most 
Distal  of  the  Stri.e  Meduli.ares.     (Kiause. ) 


STRIA  

MEDULLARIS 

NUCLEUS  OF X— 

HYPOGLOSSAL  ,is 


VENA  CENTRALIS 


OLIVARY  NUCLEUS 


NUCLEUS  PONTIS 


CONTINUA  TION  OF 
PYRAMIDAL  BODY 


CHIEF  NUCLEUS  OF 
A  UDITOR  Y  NER  VE 


RESTIFORM  BODY 


SUBSTANTIA 
GEL  A  TINOSA 


A  CCESSOR  Y  NUCLEUS 


MESIAL  ROOT 


no  connection  with  the  ventral  nucleus;  most  of  its  fibres  terminate  in  the  small- 
celled,  chief,  or  dorsal  nucleus,  l)ut  some  probably  pass  directly  to  the  cerel)ellum. 

There  appears  to  be  but  little  doubt  that  the  superior  temporal  convolution  is 
the  cortical  centre  for  hearing  (Ferrier).  According  to  Obersteiner,  the  probable 
links  between  the  nerves  of  hearing  and  the  cortical  acoustic  field  are  as  follow: 
lateral  root,  accessory  nucleus,  superior  olive,  lateral  fillet,  posterior  quadrigeminal 
l^ody,  internal  geniculate  body,  temporal  lobe. 

The  two  roots  unite  at  the  ventral  l)order  of  the  restiform  Ixxiy,  and  the  nerve 
thus  formed,  proceeding  upwards,  outwards,  and  forwards,  enters  the  internal  audi- 
tory meatus,  near  the  outer  end  of  which  it  divides  into  an  anterior  or  upj)er,  and  a 
posterior  or  lower  l)ranch.  In  its  course  througli  the  meatus,  it  is  accom})anied  by 
the  facial  nerve,  the  pars  intermedia,  and  the  internal  auditory  artery.  These 
structures  are  all  contained  in  a  common  sheath  of  arachnoid.  \\'ithin  the  meatus 
the  auditory  nerve  becomes  flattened,  and  it  is  curved  in  such  a  maimer  as  to  form 
a  half-cylinder,  open  above.  The  pars  intermedia  lies  in  the  concavity  of  this  half- 
cylinder,  and  above  this  is  the  facial  nerve,  the  three  nerves  being  connected  by  a 
lax  connective  tissue.  This  connective  tissue  has  often  been  mistaken  for  nervous 
comnnmications.      (Testut. ) 


GLOSSO-PHARYNGEAL   NERVE  7G7 

Tilt'  anterior  or  upijcr  branch  consists  entirely  of  vestil)ular  libres,  it  divides 
into  three  parts  which  pass  above  the  crista  falciforniis,  through  the  area  cril)rosa 
superior,  and  are  distributed  to  the  utricle,  and  to  the  ampullae  of  the  sui)erior  and 
external  semicircular  canals.  Cianglionic  nerve-cells  are  found  in  this  part  of  the 
nerve. 

The  lower  or  posterit)r  branch  contains  l)Oth  vestil)ular  and  cochlear  iil)res.  It 
trives  oft'  the  former  in  two  twigs  which  contain  ganglion  ci-lls,  one  passes  through 
the  area  cribrosa  media  to  the  saccule,  and  the  other  through  the  foramen  singulare 
to  the  am}>ulla  of  the  ))osterior  vertical  semicircular  canal.  The  remaining  and 
larger  ])art  of  the  lower  branch  consists  of  cochlear  libres  which  pass  through  the 
tractus  si)iralis  foraminulentus  of  the  inferior  cribriform  area  into  the  central 
canal  of  the  modilus  and  the  spiral  lamina  of  the  cochlea.  They  are  connected 
with  the  nerve-cells  of  the  spiral  ganglion  of  the  cochlea,  and  they  terminate 
in  the  or^an  of  Corti. 


NINTH  OR  GLOSSO-PHARYNGEAL  NERVE 

The  glosso-pharyngeal  nerve  is  made  up  of  fibres  derived  from  three  different 
sources.  Two  of  these  sets  of  fibres  arise  from  distinct  groups  of  cells,  and 
re})resent  the  motor  part  of  the  nerve  and  the  portion  devoted  to  the  special  sense 
of  taste.  The  third  set  of  fibres  takes  the  form  of  an  ascending  root  (funiculus 
solitarius)',  the  round  cross-section  of  which  forms  a  consi)icuous  object  in  sections 
through  the  lower  part  of  the  medulla.  The  fibres  from  these  three  sources  emerge 
in  the  form  of  several  fasciculi  (superficial  origin)  in  the  groove  between  the  olivary 
and  restiform  l^odies,  near  the  lower  border  of  the  pons,  in  series  with  the  roots  of 
the  vagus  nerve. 

The  two  principal  nuclei  are  called  the  small-celled  and  the  large-celled  nuclei, 
and  are  absolutely  continuous  with  the  nuclei  of  the  vagus  and  of  the  accessory 
part  of  the  spinal  accessory  nerve. 

The  small-celled  nucleus  (sensory,  or  accessorio-vago-glosso-pharyngeal 
nucleus)  i-orresponds  for  the  most  part  to  the  ala  cinerea  in  the  floor  of  the  fourth 
ventricle.  In  this  situation  it  lies  immediately  external  to  the  chief  nucleus  of  the 
hypo-glossal  nerve.  Higher  up,  it  recedes  from  the  middle  line,  and  is  more  dee]>ly 
))lace(l,  being  covered  by  the  chief  nucleus  of  the  auditory  nerve.  It  is  from  this 
d(H'i)er  (up])er)  ))art  that  the  glosso-pharyngeal  fil)res  take  origin  and  these  fibres 
are  regarded  as  the  conductors  of  the  s])ecial  sense  of  taste. 

The  large-celled  nucleus  (motor  nucleus,  nucleus  aml)igvuis)  contains  ci'lls 
resembling  the  motor  cells  in  the  anterior  horn  of  the  sjnnal  cord,  and  is  regarded 
as  a  portion  of  the  head  of  that  horn  which  has  been  ami)Utated  from  the  neck  l)y 
the  decussation  of  the  pyramids.  *  It  is  more  deeply  placed  than  the  small-celled 
nucleus.  It  is  i)laced  between  the  nucleus  lateralis  and  external  accessory  olive,  and 
somewhat  dorsally  to  both.  It  extends  in  a  sagittal  direction  from  the  level  of  the 
stria,'  medullares  downwards  to  a  point  a  little  below  the  fourth  ventricle.  From 
the  upper  end  of  this  nucleus  fi'bres  j)ass  dorsally  and  then  arch  outwards  to  join 
the  fibres  derived  from  the  small-celled  nucleus.  Both  sets  of  fibres  then  ])rocee(I 
forwards  and  outwards,  piercing  the  ascending  root  of  the  trigeminal,  and  emerge 
at  the  ventral  margin  of  the  restiform  body. 

The  ascending  root  (funiculus  solitarius)  commences  at  a  i)oint  innuediately 
above  the  level  of  the  decussation  of  the  pyramids.  It  ])asses  u}nvards  in  the  form 
of  a  shar])ly  circumscribed  round  bundle,  gaining  in  strength  as  it  ascends.  It  is 
placed  at  first  close  to  the  outer  side  of  the  nucleus  of  the  hypoglossal  nerve; 
higher  up  it  is  related  to  the  outer  side  of  the  small-celled  (accessorio-vago-glosso- 
l)haryngeal)  nucleus  (fig.  4?>\),  and  lies  dorsally  to  the  roots  of  the  vagus.  Finally, 
at  the  level  of  the  stria?  medullares,  it  lu-nds  at  right  angles  to  its  former  course,  and 
runs  forwards  and  outwards, traversing  thi'  sul)stantia  gelatinosa  and  the  ascending 
root  of  the  trigeminal  to  join  the  rest  of  the  glosso-pharyngeal  nerve,  forming  the 
uppermost  (most  ])roximal)  of  the  series  of  fasciculi  which  has  been  descri])ed  as 
the  superficial  origin  of  that  nerve. 


768  THE  NERVOUS  SYSTEM 

The  term  aweiuliiiji  as  applied  to  the  fibres  of  the  glosso-pharyi)geal  nei-ve  which  he  in  the 
funiculus  solitarius  is  unjustifiable.  In  reality  the  funiculus  consists  of  fibres  of  the  glosso- 
pharyngeal and  vagus  nerves,  derived  from  the  ganglicjii  cells  of  these  nerves,  which  are  i)assing 
downwards  to  lower  levels  of  the  medulla,  and  which  correspond,  therefure,  tn  a  certain  extent, 
with  the  fibres  of  the  descending  comma-shaped  tract  of  the  spinal  cord. 

From  its  superficial  origin  the  glosso-pharyngeal  nerve  proceeds  outwards  and 
sliglitly  forwards,  below  and  in  front  of  the  flocculus,  to  reach  the  middle  compart- 
ment of  the  jugular  foramen,  which  it  traverses  in  common  witli  the  vagus  and 
spinal  accessory  nerves.  As  it  passes  through  the  foramen  it  is  jilaced  in  front  of. 
and  a  little  internal  to,  the  vagus  and  spinal  accessory  nerves,  but  occupies  a  sepa- 
rate compartment  in  the  dura  mater,  and  is  lodged  in  a  groove  on  the  lower  l)order 
of  the  petrous  portion  of  the  temporal  bone.  Having  emerged  at  the  base  of  the 
skull,  it  lies  at  first  in  contact  with  the  vagus,  but  leaves  the  latter  almost  immedi- 
ately and  passes  forwards  and  inwards  between  the  internal  jugular  vein  and  the 
internal  carotid  artery  and  curves  round  the  outer  side  of  the  latter  vessel  between 
it  and  the  external  carotid.  In  this  part  of  its  course  it  is  placed  under  cover  of  the 
stylo-pharyngeus  muscle.  It  then  winds  round  the  lower  border  of  that  muscle, 
and  finally  passes  upwards  in  front  of  it  and  gains  the  deep  surface  of  the  hyo- 
glossus,  where  it  breaks  up  into  its  terminal  or  lingual  branches.  In  the  course 
above  described,  the  glosso-pharyngeal  descril)es  a  curve  with  the  convexity  directed 
downwards  and  backwards. 

In  its  course  through  the  jugular  foramen,  two  ganglia  are  formed  upon  the 
trunk. of  the  nerve,  the  lower  of  these  bodies  (petrous  ganglion)  is  the  more  con- 
stant, the  upper  or  jugular  ganglion  being  generally  regarded  as  a  segmentation 
from  the  petrous  ganglion.  The  two  ganglia  taken  together  are  generally  assumed 
to  l)e  equivalent  to  the  ganglion  on  the  posterior  root  of  a  spinal  nerve. 

The  jugular  ganglion  (ganglion  of  Ehrenritter)  is  a  small  greyish  body  which 
involves  only  tlie  back  part  of  tlie  nerve.  It  is  lodged  in  the  U]^])er  part  of  the 
groove  in  the  temporal  bone  through  which  the  nerve  passes.  This  ganglion  does 
not  give  off  any  branches. 

The  petrous  ganglion  (ganglion  of  Andersch)  is  an  ovoid  greyish  body  which 
prolmbly  involves  all  the  fibres  of  the  nerve.  Its  long  axis" coincides  with  the  axis 
of  the  nerve,  and  measures  two  or  three  millimetres.  It  is  placed  in  the  lower  part 
of  the  jugular  fossa.  The  nerve  of  Jacobson  and  some  communicating  1)ranches 
arise  from  it. 

Branches. — The  following  branches  are  given  off  by  the  glosso-pharyngeal 
nerve: — (1)  meniingeal;  (2)  tympanic;  (8)  communicating;  (4)  muscular;  (5) 
pharyngeal;   (G)  tonsillar;  and  (7)  lingual. 

(1)  The  meningeal  branches  are  slender  twigs  Avhieh  are  given  off  within 
the  cranium,  and  are  distributed  to  the  pia  mater  and  arachnoid.  (Boch- 
dalek. ) 

(2)  The  tympanic  branch,  or  nerve  of  Jacobson,  is  a  small  twig  which  arises 
from  the  petrous  ganglion.  It  enters  a  minute  canal  (the  tympanic  canaliculus), 
which  commences  below  on  the  ridge  between  the  jugular  fossa  and  the  inferior 
opening  of  the  carotid  canal,  and  ends  above,  in  the  tympanic  cavity,  immediately 
below  the  promontory.  The  nerve,  having  traversed  this  canal,  ramifies  on  the 
promontory,  grooving  the  bone,  and  forming  the  tym])anic  plexus.  The  following 
i)ranches  arise  from  the  nerve  within  the  tympanum:  (a)  a  communicating  twig 
to  the  great  superficial  petrosal;  (b)  a  twig  to  the  lesser  superficial  petrosal,  whieii 
is  considered  by  some  anatomists  to  be  the  main  root  of  the  nerve;  (c)  a  twig  to 
the  mucous  membrane  surrounding  the  fenestra  ovalis;  (cZ)  a  twig  to  the  fenestra 
rotunda;  (e)  a  twig  to  the  lining  membrane  of  the  Eustachian  tube;  (/)  a  twig 
which  passes  through  the  carotico-tympanic  canal  to  join  the  carotid  plexus  of  the 
sympathetic. 

(3)  The  communicating  branches  arise  from  the  petrous  ganglion.  One  joins 
the  superior  cervical  ganglion  of  the  sym])at}ietic;  another  forms  a  loop  Avith  the 
auricular  branch  of  the  vagus;  while  a  third,  l(>ss  constant  than  the  other  two,  joins 
the  ganglion  of  the  root  of  the  vagus.  Immediately  below  the  })etrous  ganglion 
a  twig  is  given  off  which  joins  the  lingual  branch  of  the  facial  as  above 
described  (i)age  764). 


PNEUMOGASTRIC  NERVE  769 

(4j  The  muscular  branch  is  distributed  to  the  stylo-pharyngeus  inusele.  Tliis 
branch  receives  a  communication  from  the  facial. 

According  to  Tcstut,  tlie  glosso-iiliaryngeal  gives  off  carotid  branches  wliicli  join  the  car()ti<l 
plexus  of  the  sympathetic  and  also  muscular  twigs  to  the  digastric,  stylo-hyoid,  and  stylo- 
glossus muscles. 

(5)  The  pharyngeal  branches  may  be  two  or  three  in  number,  and  arise  from 
the  nerve  a  short  distance  below  the  petrous  ganglion.  The  ])rineipal  and  most 
constant  of  these  nerves  passes  on  the  outer  side  of  the  internal  carotid  artery,  and 
after  a  very  short  independent  t-ourse  joins  the  {)haryngeal  branch  of  the  vagus  to 
form  the  pharyngeal  plexus  with  that  nerve,  and  with  branches  of  the  superior 
cervical  ganglion. 

(6)  The  tonsillar  branches  are  a  number  of  small  twigs  which  arise  under 
cover  of  the  hyo-glossus  muscle;  these  proceed  to  the  tonsil,  around  which  they 
form  a  plexus.  From  this  plexus  fine  twigs  proceed  to  the  pillars  of  the  fauces 
and  to  the  soft  ]ialate. 

(7)  The  lingual  branches  arise  from  the  termination  of  the  nerve  and  proc(X'd 
to  the  dorsum  of  the  tongue,  where  they  are  chiefly  distributed  to  the  circumvallate 
})apill8e.  Some  small  twigs  pass  backwards  to  the  follicular  glands  of  the  tongue, 
and  to  the  anterior  surface  of  its  epiglottis.  Other  twigs  are  distributed  around 
the  foramen  caecum,  where  they  communicate  with  the  corresponding  twigs  of  the 
opposite  side. 

TENTH  OR  PNEUMOGASTRIC  NERVE 

Tbe  pneumogastric  or  vagus  nerve  is  the  longest  of  the  cranial  nerves.  It  is 
remarkable  for  its  extensive  distril)Ution,  for  the  asymmetry  which  it  shows  in 
certain  parts  of  its  course  and  distribution,  and  for  the  almost  vertical  course  whicii 
it  pursues.  It  sui)j)lies,  as  its  name  implies,  the  lungs  and  the  stomach,  but  also 
furnishes  branches  to  the  external  ear,  the  pharynx,  larynx,  oesophagus,  trachea, 
heart,  and  al)dominal  viscera. 

The  pneumogastric  nerve  arises  in  the  medulla  in  a  manner  nearly  identical 
with  the  glosso-pharyngeal  nerve,  the  roots  of  the  former  nerve  being  a  serial  con- 
tinuation of  the  roots  of  the  latter.  Thus  we  find  that  sensory  roots  arise  from 
the  small-celled  nucleus  (in  a  position  corresponding  to  the  ala  cinerea  in  the  floor 
of  the  fourth  ventricle),  and  motor  roots  arise  from  the  nucleus  ambiguus.  The 
latter  arch  round  to  join  the  sensory  roots.  The  vagus  is  also  said  to  he  connected 
by  a  few  fine  filaments  with  the  funiculus  solitarius.  The  roots  from  tiiese  dif- 
ferent sources  unite  and  pass  forwards  and  outwards  to  emerge  (superficial  origin) 
in  the  form  of  from  ten  to  fifteen  fasciculi,  between  the  restiform  body  and  the 
lateral  column  of  the  medulla.  This  row  of  fasciculi  is  in  series  above  with  the 
glosso-pharyngeal  roots,  and  below  with  the  bulbar  roots  of  the  spinal  accessory. 
The  roots  of  these  three  nerves  cannot  be  distinguished  from  one  another  either  at 
their  superficial  origin,  or  at  the  points  where  they  spi'ing  from  their  nuclei  in  the 
medulla,  unless  the  connecticm  of  the  roots  Avith  their  respective  trunks  has  been 
])reserved. 

From  its  superficial  origin  the  vagus  nerve  proceeds  outwards  and  slightly 
upwards  and  forwards  beneath  the  flocculus  to  reach  the  jugular  foramen.  It 
traverses  the  middle  compartment  of  the  foramen  accompanied  V)y  the  spinal 
accessory  and  glosso-pharyngeal  nerves.  The  former  nerve  occupies  the  same 
compartment  in  the  dura  mater  as  the  vagus.  The  glosso-])harvngeal  is  provided 
with  a  separate  sheath,  and  is  in  front  of  and  somewhat  internal  to  the  other  two 
nerves.  As  the  vagus  traverses  the  jugular  forameiv  it  bends  at  a  right  angle  to  its 
former  course,  and  proceeds  vertically  downwards.  In  its  course  down  the  neck  it 
is  placed  in  front  of  the  rectus  ca])itis  anticus  major  and  longus  colli  muscles,  but 
separated  from  them  by  the  prevertebral  layer  of  the  cervical  fascia.  In  the  upper 
part  of  the  neck  it  is  placed  between  an<l  on  a  ])lane  posterioi' to  the  internal  jugular 
vein  and  the  internal  carotid  artery.  In  the  lower  }>art  of  the  neck  it  occupies  a 
similar  position  in  regard  to  the  internal  jugular  vein  and  conmion  carotid  artery, 
the  vein  being  in  front  and  external,  and  the  artery  in  front  and  internal  to  the 
49 


770 


THE  NERVOrS  SYSTEM 


nerve.     The  three  striutures  are  enclosed  in  a   conniiDii   sheatli  derived  froin   the 
deep  cervical  fascia. 

In  their  course  throuiih  the  thora.x  tlu-  nerves  of  the  left  and  right  sides  differ 
in  some  respects  from  each  other. 


Fig.  451.— Distribution  of  thk  Pneumogastric  Nervk,  viewed  from  hehind.     (Krause.) 

Stylo-hyoid  Ligamentuin  pharyngeum 


Posterior  belly  of 
digastric 


Sterno-mastoid 

Kectus  capitis 
anticua  major 

Stylo-pharyngeus 

Stylo-glossuB 

Internal  pterygoid 

SUPERIOR 
CERVICAL 
GANGLION 

Middle  constrictor 

Common  carotid 
artery 

Inferior  constrictor 

GANGLION 
THYROWEUM 
(VARIETY) 

THYROID  GLAND 


Inferior  thyroid 
artery 
Subclavian  artery 


RECURRENT 
LARYNGEAL 
NER  VE 


Thoracic  aorta 


Cru8  of  diaphragm 


Infernal  carotid 
artery 
-  RIGHT 

SYMPA  TIIETIC 

Occipital  arlerii 

—  Posterior  belly  of 
digastric 


_  DESCENDENS 
HYPOGLOSSI 

Common  carotid 
iirfeni 

Sterno-mastoid 

TWIG  OF 
RECURRENT 
LARYNGEAL  TO 
PHARYNGEAL 
PLEXUS 


Thyroid  axis 

INFERIOR 
CERVICAL 
GANGLION 


RECURRENT 
LARYNGEAL 


PLEXUS  G  ULM, 


RIGHT 
PNEUMOGASTRIC 


\ 


The  right  vagus  nerve  })asses  in  front  of  the  first  stage  of  the  subclavian  artery 
between  the  latter  and  the  right  innominate  vein,  and  then,  inclining  backwards, 


PNEUMOGASTRIC  NERVE  771 

runs  downwards  on  the  side  of  the  trachea,  jxjsterior  to  tiie  riglit  innominate  vein 
and  the  superior  vena  cava,  to  reach  the  posterior  aspect  of  the  right  bronchus. 
Behind  the  Ijronchus  it  expands  into  a  great,  flat,  plexiforni  band,  from  Avhich  the 
posterior  puhnonarv^  plexus  proceeds.  The  vagus  then  inclines  inwards  in  the  form 
of  two  cords,  and  conmumicates  with  the  pneumogastric  of  the  oi)i)osite  side  both 
in  front  and  behind  tlie  o'sophagus  to  form  the  o'sophageal  plexus  (i)lexus  guhe). 
Having  interchanged  a  considerable  number  of  fi]>res  with  the  other  nerve,  the  right 
vagus  then  descends  (having  regained  the  form  of  one  nerve)  behind  the  O'sophagus 
through  the  (i^sophageal  opening  of  the  diai)hragm,  and  spreads  out  on  the 
posterior  surface  of  the  stomach. 

The  left  vagus  nerve  enters  the  thorax  behind  the  left  common  carotid  artery 
between  the  latter  and  the  left  subclavian  artery.  As  it  approaches  the  arch  of 
the  aorta  it  bends  suddenly  backwards,  and  crosses  the  root  of  the  subclavian  artery 
on  the  left  side  of  that  vessel,  immediately  under  cover  of  the  pleura.  It  then 
crosses  the  left  side  (in  front)  of  the  arch  of  the  aorta,  and  bends  backwards  to 
reach  the;  posterior  aspect  of  the  left  l)ronchus,  where  it  si)reads  out  in  a  similar 
manner  to  the  nerve  of  the  right  side.  It  then  descends  on  the  (esophagus,  entering 
into  the  plexus  gula?,  and  on  reaching  the  dia])ln"agm  passes  in  the  form  of  a  single 
trunk  in  front  of  the  (psoi)hagus  into  the  abdominal  cavity,  and  spreads  out  on  the 
anterior  surface  of  the  stomach. 

At  the  base  of  the  skull  the  vagus  presents  two  ganglia:  an  upper  ganglion,  or 
ganglion  of  the  root ;  and  a  loAver,  or  ganglion  of  the  trunk. 

The  ganglion  of  the  root  is  placed  within  the  jugular  foramen  opposite  the 
jugidar  ganglion  of  the  glosso-pharyngeal.  It  is  an  irregular  greyish  swelling  of 
from  four  to  six  millimetres  in  length.  It  is  usually  regarded  as  corresponding  to 
a  sjjinal  ganglion. 

The  ganglion  of  the  trunk,  situated  a  little  below  the  preceding,  is  a  fusiform 
enlargement  of  the  nerve  about  twenty  millimetres  in  length,  and  four  to  live  milli- 
metres in  transverse  diameter  at  its  thickest  part.  The  hypoglossal  nerve  isfirndy 
attached  to  it  by  connective  tissue  and  encloses  it  in  a  spiral  turn,  being  placed  at 
tirst  to  the  inner  side  of  the  vagus,  then  passing  behind,  then  to  its  outer  side,  and 
finally  ca'ossing  it  in  front.  The  superior  cervical  ganglion  of  the  sj'mpathetic  is 
behind  and  a  little  external  to  the  vagus;  the  glosso-pharyngeal  is  in  front  of  it. 
The  accessory  portion  of  the  spinal  accessory  nerve  joins  the  ganglion  ofthetruidc; 
some  of  the  fil)res  running  over  the  ganglion  into  the  pharyngeal  and  superior 
laryngeal  l)ranches. 

Branches. — The  branches  of  the  vagus  may  be  classified  into  (1 )  connnunicating 
])ranchcs;  and  (2)  ])ranch('S  of  distril)ution. 

(1)  Communicating  branches. — The  vagus  communicates  with  the  following 
nerves: — (a)  the  glosso-pharyngeal  to  the  auricular  branch  of  the  pneumogastric; 
(b)  the  spinal  accessory;  (c)  the  hypoglossal;  (d)  the  sympathetic;  and  {e)  the 
upper  two  spinal  nerves. 

(a)  Besides  the  communicating  branch  to  the  vagus  just  referred  to,  a  communi- 
cating twig  is  given  off  from  the  pneumogastric,  close  to  the  base  of  the  skull, 
which  joins  the  glosso-jtliaryngeal  nerve  immediately  below  the  petrous  ganglion. 

(6)  The  spinal  accessory  gives  some  fine  filaments  to  the  ganglion  of  the  root 
of  the  vagus  within  the  jugular  foramen.  Lower  down,  the  remainder  of  the 
accessory  portion  joins  the  ganglicm  of  the  trunk. 

(c)  Tlie  hypoglossal  furnishes  two  or  three  fine  filaments  to  the  ganglion  of  the 
trunk  of  the  vagus.  These  fihunents  are  given  off  l)y  the  hypoglossal  as  it  winds 
round  the  ganglion. 

(d)  Two  or  three  twigs  from  the  superior  cervical  ganglion  of  the  sympa- 
thetic join  the  ganglia  of  the  trunk  and  root.  Lower  down  the  branches  of  distri- 
bution of  the  vagus  communicate  extensively  with  the  sympathetic. 

(e)  A  twig  passes  from  the  loop  formed  by  the  anterior  primary  divisions  of 
the  up])er  two  spinal  nerves  to  the  ganglion  of  the  trunk  of  the  vagus.  This  com- 
numication  is  not  constant. 

(2)  Branches  of  distribution. — These  are  («)  the  meningeal;  (6)  auricular; 
{<•)  pharyngeal;  (r/)  su])cri()r  laryngeal;  (e)  inferior  laryngeal;  (/)  cardiac; 
(g)  pulmonary;   (/t)  oesophageal;  and  (/)  abdominal  branches. 


772  THE  NERVOUS  SYSTEM 

(a)  The  meningeal  or  recurrent  branch  is  a  slender  filament  which  is  given 
off  from  the  ganglion  of  the  root.  It  takes  a  recurrent  course  through  the  jugular 
foramen,  and  is  distrihutcd  to  the  dura  mater  around  the  lateral  sinus. 

{b)  The  auricular  branch,  or  nerve  of  Arnold,  arises  from  the  ganglion  of  the 
root  in  the  jugular  t'oranien.  It  traverses  the  Ixtne,  ])assing  to  the  inner  side  of  the 
a(jueduct  of  P^allo{)ius;  forming  a  connnunication  with  the  facial  nerve,  and  emerges 
hehind  the  pinna,  wliere  it  divides  into  two  hranches,  one  of  Avhich  joins  the  pos- 
terior auricular  branch  of  the  facial  while  the  other  supplies  the  posterior  and 
inferior  part  of  the  external  auditory  meatus  and  the  back  of  the  pinna.  It  also 
supplies  twigs  to  the  osseous  part  of  the  external  auditory  meatus  and  to  the  lower 
])art  of  the  outer  surface  of  the  membrana  tympani. 

(c)  The  pharyngeal  branches  may  be  two  or  three  in  number.  The  ])rin(ii)al 
of  these  joins  the  pliaryngeal  branch  of  the  glosso-pharyngeal  in  front  of  the  internal 
carotid  artery,  and  passes  witli  the  latter  behind  the  external  carotid  artery  down- 
wards and  inwards  to  reach  the  j^osterior  aspect  of  the  pharynx.  Here  the  two 
nerves  are  joined  by  branches  from  the  superior  cervical  ganglion  of  the  sympa- 
thetic, and  form,  with  the  latter,  the  pharyngeal  plexus. 

(d)  The  superior  laryngeal  nerve  arises  from  the  lower  part  of  the  ganglion 
of  the  trunk,  and  passes  obliquely  downwards  and  inwards  behind  and  internal  to 
both  internal  and  external  carotid  arteries  towards  the  larynx.  In  this  course  it 
describes  a  curve  with  the  convexity  downwards  and  outwards,  and  divides  into 
(i)  a  larger  internal  and  (ii)  a  smaller  external  branch.  Before  its  division  it  is 
joined  by  communications  from  the  sympathetic  and  from  the  pharyngeal  plexus. 

(i)  The  internal  branch  accompanies  the  superior  laryngeal  artery  to  the  interval 
between  the  ui)per  border  of  the  thyroid  cartilage  and  the  great  cornu  of  the  hyoid 
bone.  It  passes  uhder  cover  of  the  thyro-hyoid  muscle  and  pierces  the  thyro-hyoid 
membrane  to  gain  the  interior  of  the  larynx;  here  it  divides  into  a  number  of 
diverging  branches.  The  ascending  branches  supply  the  mucous  membrane  on 
both  surfaces  of  the  epiglottis.  The  descending  branches  ramify  in  the  mucous 
membrane  lining  the  larynx,  communicate  with  the  recurrent  laryngeal  nerve,  and 
supply  the  mucous  meml)rane  which  covers  the  back  of  the  cricoid  cartilage. 

(ii)  The  external  laryngeal  branch  runs  downwards  towards  the  lower  border 
of  the  thyroid  cartilage.  It  pierces  the  lower  fibres  of  the  inferior  constrictor  of 
the  pharynx,  and  ends  for  the  most  part  in  the  crico-thyroid  muscle.  A  fcAV  fila- 
ments pierce  the  crico-thyroid  membrane,  and  are  distributed  to  the  lining  mem- 
brane of  the  larynx.  It  gives  off  a  cardiac  branch  which  joins  one  of  the  cardiac 
branches  of  the  sympathetic;  it  also  furnishes  twigs  to  the  inferior  constrictor  and 
communicating  twigs  to  the  pharyngeal  plexus,  and  it  receives  a  comnumication 
from  the  superior  cervical  ganglion  of  the  sympathetic. 

(e)  The  inferior  or  recurrent  laryngeal  nerve  of  the  right  side  arises  at  the 
root  of  the  neck  in  front  of  the  first  stage  of  the  right  subclavian  artery.  It  hooks 
round  the  artery,  passing  l)elow  and  then  behind  that  vessel,  and  runs  upwards  and 
slightly  inwards,  crossing  obliquely  behind  the  conunon  carotid  artery.  Having 
gained  the  side  of  the  trachea,  it  runs  u})wards  in  the  groove  between  that  canal 
and  the  fpsophagus,  accompanied  by  the  inferior  thyroid  artery,  and  enters  the 
larynx  by  passing  under  cover  of  the  lower  border  of  the  inferior  constrictor  of 
the  pharynx.  It  then  breaks  up  into  branches,  which  are  distributed  to  all  the 
intrinsic  muscles  of  the  larynx  with  the  exception  of  the  crico-thyroid,  and  it 
communicates,  as  above  mentioned,  with  the  superior  laryngeal  nerve.  Near  its 
commencement  it  usually  gives  off  a  cardiac  branch. 

In  its  course  between  the  oesophagus  and  trachea  it  gives  numerous  twigs  to 
these  structures,  and  near  the  termination  it  furnishes  one  or  two  twigs  to  the 
inferior  constric-tor  of  the  ])harvnx. 

On  the  left  side  the  nerve  arises  in  front  of  the  aortic  arch,  and  winds  round 
the  concavity  of  tlu;  arch  just  behind  the  obliterated  ductus  arteriosus.  It  crosses 
obliquely  behind  the  root  of  the  left  common  carotid  artery,  gains  the  angular 
interval  between  the  o}sophagus  and  trachea,  and  corresponds  to  the  nerve  of  the 
right  side  for  the  remainder  of  its  course  and  distribution. 

(/)   Cardiac  branches. — These  are  named  (from  the  different  levels  at  which 


SPINAL  ACCESSORY  NERVE  773 

they  take  origin)  cervical  and  tlioracic,  and  form  altogetlier  three  or  four  pairs  of 
nerves.  Tliese  all  proceed  to  the  deep  cardiac  plexus,  witli  one  exception,  the 
inferior  cervical  cardiac  of  the  left  side,  which  joins  the  superficial  cardiac  plexus. 

(i)  The  superior  cervical  cardiac  nerves,  one  or  two  in  nundjer,  join  the 
corresponding  branches  from  the  sym])athetic.  A  full  account  of  these  nerves  will 
l)e  given  in  the  description  of  the  cardiac  plexus.      (See  Sympathetic  System.) 

(ii)  The  inferior  cervical  cardiac  nerve  of  the  left  side  passes  downwards 
on  the  left  side  of  the  aortic  arch  between  the  latter  and  the  ]>leura,  ;ind  joins  the 
superficial  cardiac  plexus.  As  it  crosses  the  arch  the  phrenic  nerve  is  in  front  of 
it,  and  the  left  uj)])er  cervical  cardiac  of  the  synipathetic  is  behind  it.  The  right 
inferior  cervical  cardiac  |)asses  downwards  on  the  side  of  the  trachea  to  join  the 
deep  cardiac  plexus. 

(iii)  The  thoracic  cardiac  branches  usually  arise  close  to  and  in  connection 
with  the  recurrent  laryngeal  nerves;  consequently  the  nerves  on  the  left  side  arise  a 
little  lower  than  the  right.  They  are  directed  inwards  to  the  front  of  the  lower  end 
of  the  trachea  to  terminate  in  the  dee])  cardiac  plexus. 

(f/)  The  anterior  pulmonary  branches  are  one  or  two  small  twigs,  which  arise 
at  the  ui)per  l)order  of  tlie  root  of  the  lung  and  pass  forwards  to  gain  the  anterior 
aspect  of  the  bronchus,  where  they  connnunicate  with  the  synipathetic  and  form 
the  anterior  pulmonary  plexus,  whence  fine  twigs  pass  along  the  })ronchus  into 
the  lung. 

The  posterior  pulmonary  plexus  is  formed  by  a  great  flattened  expansion  of 
the  pneumogastric  nerve  on  the  posterior  aspect  of  the  bronchus.  From  this  several 
stout  twigs  proceed,  which  communicate  with  twigs  from  the  second,  third,  and 
fovirth  thoracic  ganglia  of  the  sympathetic,  and  pass  into  the  lung,  and  it  anasto- 
moses witli  the  corres})onding  plexus  of  the  opposite  side. 

(//)  QEsophageal  branches. — Numerous  twigs  are  given  off  from  the  plexus 
gula;  as  it  encircles  the  (esophagus,  and  are  distributed  to  the  muscuhir  and  mucous 
coats  of  that  canal. 

(/)  Abdominal  branches. — The  termination  of  the  left  vagus  nerve  passes 
through  tlie  u'so])liageal  oi)ening  in  the  diaphragm  on  the  anterior  asi)ect  of  the 
(I'sophagus,  and  is  distributed  over  the  anterior  surface  of  the  stomach.  The 
strongest  branches  accompany  the  coronary  artery  along  the  lesser  curvature  of 
the  stomach,  and,  from  these,  twigs  pass  on  to  the  hepatic  artery  and  join  the 
hepatic  plexus.  The  termination  of  the  right  vagus  is  distributed  upon  the  pos- 
terior surface  of  the  stomach,  and  gives  twigs  to  the  coeliac,  splenic,  and  left  renal 
plexuses. 

ELEVENTH  OR  SPINAL  ACCESSORY  NERVE 

The  spinal  accessory  nerve  consists  of  two  distinct  parts,  which  are  usually 
known  as  the;  s})inal  and  the  accessory  portions  of  the  nerve.  The  former  of  these 
(spinal  portion)  is  a  purely  motor  nerve  which  arises  from  the  nerve-cells  in  the 
ventro-lateral  group  of  the  anterior  cornu  of  the  cervical  portion  of  the  spinal  cord. 
The  accessory  portion,  on  the  other  hand,  arises  by  a  series  of  roots  from  the  distal 
parts  of  both  the  motor  and  sensory  accessorio-vago-glosso-pharvngeal  nuclei  in  the 
medulla,  and  would  l)e  more  properly  described  as  the  most  distal  vagal  roots 
(Obersteiner)  than  as  a  s('))arate  nerve. 

The  accessory  portion  (distal  vagal  roots,  or  bulbar  accessory)  consists  of  four 
or  five  fasciculi  which  arise  in  a  precisely  similar  manner  to  the  roots  of  the  vagus 
with  which  they  are  in  series.  Shortly  after  their  emergence  from  the  medulla 
they  join  the  s})inal  portion  and  accompany  the  latter  through  the  jugular  foramen. 
Having  gained  the  exterior  of  the  skull,  the  bull)ar  accessory  leaves  the  nerve 
with  wdiich  it  has  been  associated  in  part  of  its  course,  and  joins  the  ganglion  of 
the  root  of  the  vagus;  some  of  its  fibres  pass  into  the  ])haryngc:d  and  su])erior 
laryngeal  nerves  as  already  descril)ed. 

The  spinal  portion  arises  from  the  ventro-lateral  group  of  nerve-cells  in  the 
anterior  cornu  of  the  cn^rvical  })ortion  of  the  si)inal  cord.  Some  of  the  fibres  run 
longitudinally  for  a  short  distance  and  join  other  more  direct  fibres,  which  arch 
backwards  and  outwards  to  emerge  from  the  lateral  colunm  of  the  cord  between  the 


774  THE   XERVOrS  SYSTEM 

posk'rior  nerve  roots  and  the  attacluncnt  of  the  liganu'ntuni  denticulatuni.  The 
.superficial  origin  of  the  nerve  is  tiius  constituted  by  a  row  of  filaments  which  extend 
from  the  tiftli  or  sixth  (rarely  the  seventh)  to  the  first  cervical  nerve.  The  lowest 
of  this  series  of  roots  is  close  to  the  ligamentum  denticulatuni;  the  highest  is  near 
to  the  i)oint  of  emergence  of  the  posterior  roots  of  the  first  cervical  nerve.  The 
roots  unite  to  form  a  rounded  cord  which  courses  upwards,  increasing  in  size  as  it 
ascends,  and  enters  the  cranial  cavity  by  passing  through  the  foramen  magnum. 
Here  it  is  joined,  for  the  time  being,  l)v  tlie  accessory  portion,  and  passes  with  the 
latter,  in  the  form  of  a  single  trunk,  through  the  middle  compartment  of  the  jugular 
foramen.  At  the  base  of  the  skull  it  runs  downwards,  outwards,  and  l>ack wards 
between  the  occipital  artery  and  the  internal  jugular  vein,  to  pass  under  cover  of 
the  sterno-mastoid  muscle;  it  })ierces  the  clavicular  fil;)res  of  the  muscle  and  com- 
municates with  a  branch  derived  from  the  second  cervical  nerve.  From  the  jilexus 
so  formed  the  sterno-mastoid  is  supplied.  The  nerve  then  emerges  at  the  ])()sterior 
l)order  of  the  muscle,  crosses  the  floor  of  the  posterior  triangle  of  the  neck  obliijuely, 
and  ])asses  under  cover  of  the  trapezius;  on  the  deep  surface  of  that  muscle  the 
spinal  accessory  is  joined  by  branches  from  the  third  and  fourth  cervical  nerves, 
and  forms  with  them  the  subtrapezial  plexus,  from  wliich  the  trapezius  is  supplied. 


TWELFTH   OR   HYPOGLOSSAL   NERVE 

The  hypoglossal  nerve  arises  from  an  elongated  column  of  nerve-cells  which 
extends  from  the  stride  medullares  in  the  floor  of  the  fourth  ventricle  downwards  to 
the  level  of  the  lower  end  of  the  olivary  body.  This  colunni  contains  nerve-cells 
(tf  large  size.  It  represents  the  neck  of  the  anterior  horn  of  the  grey  crescent  in 
the  spinal  cord,  and  is  continued  into  that  structure  below.  In  its  lower  part  the 
column  is  placed  ventro-laterally  to  the  central  canal,  but,  as  the  central  canal 
expands  into  the  floor  of  the  fourth  ventricle,  the  grey  column  is  displaced  laterally, 
and  thus  apparently  occupies  a  more  dorsal  position.  It  corresponds  to  the  area 
described  as  the  trigonum  hypoglossi,  and  is  separated  from  the  ependyma  of  th(^ 
ventricle  only  by  a  thin  layer  of  medullated  fibres.  From  the  cells  embedded  in 
tliis  grey  column  the  nerve-fil)res  arise.  These  fibres  pass  in  bundles  which  are 
directed  ventrally  and  outwards,  internal  to  the  olivary  nucleus,  between  the  latter 
and  the  internal  accessory  olive.  Finally  they  emerge  in  a  row  of  from  ten  to 
twelve  filaments  in  the  furrow  between  the  olivary  and  pyramidal  bodies,  consti- 
tuting the  superficial  origin  of  the  hypoglossal  nerve. 

An  accessoiy  nucleus  is  also  described  which  is  placed  ventro-laterally  to  the  above  described 
(or  chief)  nucleus.     This  accessory  nucleus  represents  a  portion  of  the  liead  of  the  anterior  liorn. 

Fibres  pass  from  the  inner  side  of  the  hypoglossal  nucleus,  and  cross  in  the  raphe  from  where 
they  ascend  brainwards  to  establish  the  cortical  origin  of  the  nerve. 

The  filaments  unite  to  form  two  fasciculi,  each  of  which  pierces  the  dura  mater 
separately  at  a  point  opposite  to  the  anterior  condyloid  foramen.  As  these  fasciculi 
traverse  the  foramen,  they  unite  to  form  a  single  trunk,  which  is  ]>laced  at  first  on 
the  inner  side  of  the  pneumogastric,  but  then  winds  spirally  round  the  ganglion  of 
the  trunk  of  the  latter  nerve,  passing  behind,  external  to,  and  finally  in  front  of  the 
ganglion.  In  this  situation  the  hypoglossal  receives  two  or  three  conimunicating 
l)ranches  from  the  first  and  second  cervical  nerves,  and  some  minute  twigs  from 
tlie  vagus  and  sym]iathctic.  The  hypoglossal  then  runs  forwards  and  inwards, 
describing  a  curve,  the  convexity  of  which  looks  downwards  and  outwards.  At  the 
conunencement  of  this  ])art  of  its  course  it  crosses  the  internal  carotid  artery  and 
hooks  round  the  occipital  artery,  passing  immediately  below  that  vessel.  It  then 
crosses  external  to  the  external  carotid  artery,  the  lingual  artery,  the  middle  con- 
strictor of  the  pharynx,  and  the  hyo-glossus  muscle,  and,  passing  under  cover  of 
the  mylo-hyoid,  breaks  uj)  into  its  terminal  branches.  As  it  lies  on  the  midilh' 
constrictor  the  great  cornu  of  the  hyoid  bone  is  below  it  and  the  tendon  of  the 
digastric  muscle  is  above  it.  As  it  passes  on  to  the  hyo-glossus  it  is  crossed  on  its 
superficial  surface  by  the  digastric  and  stylo-hyoid  muscles.  It  is  also  overlapped 
in  this  situation  by  the  submaxillary  gland. 


HYPOCLOSSAL   XERVE  775 

Branches. — Tlie  meningeal  branch  (  Lusclika)  is  given  off  by  the  hypoglossal 
as  it  is  traversing  the  anterior  condyloid  foramen,  and  takes  a  recurrent  course  into 
the  cranial  cavity,  where  it  is  distributed  to  the  dura  mater.  It  is  probably  derived 
from  the  connnunicating  branches  of  the  pneumogastric  or  from  the  first  cervical 
nerve. 

The  remaining  lirnnclics  of  tlic  liyjioglossal  may  be  classified  into  branches  of 
the  cervical  plexus  which  are  simply  adiierent  for  the  time  being  to  the  cranial 
nerve,  and  true  hypoglossal  branches;  the  latter  are  exclusively  distributed  to  the 
muscles  of  the  tongue  and  the  genio-hyoid. 

The  BRANCHES  DERIVED  FROM  THE  CERVICAL  PLEXUS  are  the  descendens 
hyjjoglossi,  and  the  muscular  twig  to  the  thyro-hyoid  muscle. 

The  descendens  hypoglossi  parts  company  with  the  hypoglossal  at  the  point 
where  the  latter  hooks  round  the  occipital  artery.  It  runs  downwards  and  slightly 
inwards  on  the  sheath  of  the  great  vessels  (occasionally  within  the  sheath),  and  is 
joined  at  a  variable  level  by  the  communicantes  hypoglossi  from  the  second  and 
third  cervical  nerves,  forming  a  loop,  the  ansa  hypoglossi.  The  ansa  hypoglossi 
may  be  placed  at  any  level  from  a  point  immediately  below  the  occipital  artery  to 
al)out  an  inch  and  a  half  aVjove  the  sternum.  A  twig  to  the  anterior  belly  of  the 
omo-hyoid  arises  from  the  descendens  hypoglossi  in  the  upper  part  of  its  course. 
The  nerves  Avhich  supply  the  sterno-hj^oid,  sterno-thyroid,  and  posterior  belly  of 
the  omo-hyoid  are  given  off  by  the  ansa  hypoglossi.  Twigs  from  the  first  two 
nerves  pass  in  the  muscles  behind  the  manubrium  stemi  and  in  rare  cases  com- 
nnmicate  with  the  phrenic  within  the  thorax.  The  nerve  to  the  posterior  belly  of 
the  omo-hyoid  runs  in  a  loop  of  the  cervical  fascia  below  the  central  tendon  of 
the  muscle. 

The  nerve  to  the  thyro-hyoid  is  given  off  near  the  tip  of  the  great  cornu 
of  the  hyoid  bone,  and  runs  oblicpiely  downwards  and  inwards  to  reach  the 
nuiscle. 

The  TRUE  HYPOGLOSSAL  BRANCHES  supply  the  stylo-glossus,  hyo-glossus, 
genio-hyo-glossus,  the  genio-hyoid,  and  the  intrinsic  muscular  fibres  of  the 
tongue.  *-«-,...«..-«^.-.   -     -      •      "'"'■'" 

Tlie  nerve  to  the  stylo-glossus  is  given  off  near  the  oviter  border  of  the 
hyo-glossus.  It  pierces  the  stylo-glossus,  and  its  fibres  pursue  a  more  or  less 
recurrent  cour.se  within  the  muscle. 

The  nerves  to  the  hyo-glossus  are  several  tAvigs  Avhich  are  supplied  to  the 
muscle  as  the  hypoglossal  nerve  crosses  it. 

The  nerves  to  the  genio-hyo-glossus  and  genio-hyoid  arise  under  cover 
of  the  mylo-hyoid  in  common  with  the  terminal  1)ranches  to  the  intrinsic  muscles 
of  the  tongue.  They  communicate  freely  with  branches  of  the  lingual,  forming 
long  loops  which  lie  on  the  hyo-glossus  muscle.  From  these  loops  twigs  pass  into 
the  genio-hyo-glossus  and  into  the  muscular  substance  of  the  tongue. 


7(i  THE  NERVOUS  SYSTEM 


SPINAL   NERVES 

The  spinal  nerves  s])rinjf  t'loni  the  spinal  cord  l)v  four  long  series  of  roots, 
namely,  an  anterior  and  a  ])osterior  series  on  each  side  of  the  cord.  These  origins 
correspond  with  the  superficial  origins  of  the  cranial  nerves,  l)eing  the  points 
at  which  the  nt-rve-tihres  emerge  from  the  cere])ro-spinal  axis.  Like  the  cranial 
nerves,  the  spinal  nerves  have  also  a  deep  origin.  This  is  situated  in  the  anterior 
and  posterior  horns  of  the  grey  crescents  and  has  heen  already  described  (i)age  738). 
The  spinal  nerves  also  resemble  the  cranial  nerves,  inasmuch  as  this  '  deep  '  origin 
is  only  a  preliminary  interruption  in  nerve-cells  or  in  plexuses  in  the  grey  matter, 
and  from  the  deep  origin  tracts  of  fibres  pass  ujiwardsto  establish  a  connection  Avith 
the  cere])ral  cortex.  They  differ  from  the  cranial  nerves  inasmuch  as  they  arise 
from  the  spinal  cord  instead  of  from  the  encephalon,  in  their  mode  of  origin  l)y  an 
anterior  motor  and  posterior  sensory  root,  and  by  the  development,  on  each  of  tlu^ 
posterior  roots,  of  a  ganglion  (the  spinal  ganglion).  Certain  of  the  cranial  nerves 
resemble  the  spinal  nerves  in  the  two  latter  respects;  for  example,  the  vagus  arises 
from  the  large-celled  (motor  nucleus),  a  derivative  of  the  anterior  horn,  and  from 
the  small-celled  (sensory  nucleus)  derived  from  the  basal  part  of  the  posterior 
horn;  the  roots  from  these  two  sources  have,  however,  united  before  the  nerve 
has  reached  the  surface  of  the  medulla.  The  ganglion  of  the  root  of  the  vagus 
and  the  ganglion  on  the  sensory  root  of  the  trigeminal  (Gasserian  ganglion)  are 
clearly  homologous  to  the  ganglia  on  the  posterior  roots  of  the  spinal  nerves.  The 
hyjioglossal  nerve  is,  in  rare  cases,  joined  by  a  small  posterior  root  on  which  a 
ganglion  is  developed,  and,  on  the  other  hand,  cases  are  recorded  in  Avhich  the 
posterior  root  of  the  first  spinal  nerve  was  devoid  of  a  ganglion. 

The  anterior  roots  stand  out  in  marked  contrast  to  the  posterior  roots  in  regard 
to  their  function,  being  motor,  whereas  the  posterior  roots  are  sensor}'.  They  also 
differ  from  the  posterior  roots  in  several  anatomical  points.  The  anterior  roots 
(with  the  single  exception  of  the  first)  are  smaller  than  the  posterior;  they  arise  by 
four  to  six  fasciculi,  and  their  origins  do  not  form  a  linear  series,  but  map  out  a 
longitudinal  area  of  one  to  tAvo  millimetres  in  breadth  on  the  surface  of  the  cord. 
The  posterior  roots  are  larger  than  the  anterior,  they  arise  by  six  to  eight  fasciculi, 
are  ])laeed  in  a  strictly  linear  series,  and,  as  each  I'oot  is  traversing  the  corivs- 
ponding  intervertebral  foramen,  it  enters  into  a  sjiinal  ganglion,  a  structure  with 
Avhich  the  motor  root  has  no  connection  A^hatever. 

The  posterior  roots  are  from  one  and  a  half  to  three  times  as  large  as  the 
anterior,  the  ratio  being — 

1  to  1*5  in  the  thoracic  nerves.  1  to  2  in  the  lumbar  nerves. 

1  to  3  in  the  cervical  nerves. 

Course  and  direction. — From  their  superficial  origin,  both  anterior  and 
posterior  roots  proceed  towards  the  intervertebral  foramina,  and  unite  near  the 
outer  limits  of  the  foramina  into  single  trunks.  The  ganglia  on  the  posterior  roots 
are  placed,  in  the  case  of  the  majority  of  the  nerves,  within  the  foramina  inune- 
diately  internal  to  the  point  of  junction  of  the  tAvo  roots.  The  ganglia  of  the  first 
and  second  cervical  nerA'es  are  placed  on  the  laminae  of  the  atlas  and  axis.  The 
ganglia  of  the  sacral  and  coccygeal  nerves  are  placed  Avithin  tire  sj^inal  canal.  Each 
spinal  ganglion  is  an  ovoid  greyish  ])ody,  the  long  axis  of  Avhich  corresponds  to  the 
axis  of  the  nerve  Avith  Avhich  it  is  incorporated.  It  is  someAvhat  adherent  to  its 
meningeal  sheath. 

The  roots  of  the  first  spinal  nerve  ascend  slightly  to  reach  the  interval  between 
the  atlas  and  the  occipital  bone.  The  second  and  third  nerves  pass  horizontally 
outAvards,  the  fourth  passes  obliquely  doAvuAvards  and  outAvards,  and  the  remaining 
nerves  pass  out  Avith  increasing  degrees  of  obliquity,  the  intraspinal  course  of  the 
nerve-roots  increasing  in  length  as  the  series  is  folloAved  doAVUAvards.  It  folloAVs 
from  the  above  statement  that  the  loAver  nerve-roots  are  directed  almost  vertically 
dowuAvards,  and  as  the  si)inal  cord  ends  at  the  level  of  the  second  lumbar  vertebra, 
Avhile  the  series  of  intervertebral  foramina  is  continued   to  the  lower  end  of  the 


SPLXAL   M'lRVES  111 

saeiuiii,  the  nerve-roots  }jassin^  within  the  verteljral  eanul  beyond  the  cord  form  a 
great  sheaf  of  fibres,  the  cauda  equina  (fig.  437).  The  distance  of  the  points  of 
emergence  (superficial  origins)  of  certain  of  the  nerves  from  the  corresponding 
intervcrteljral  foramina  is  given  in  the  following  table.  This  table  gives  the 
measurements  made  by  Testut  in  a  suljject  of  eighteen  years.  Tlie  length  of  the 
spinal  cord  was  in  this  case  forty-one  centimetres. 

Right  side         Left  side 
mm.  nitii. 

Third  pair  of  cervical  nerves 18  17 

Fifth  ,,          „           ,,        25  25 

First  ,,  tlioracic       , 3;>  32 

Fifth  ,.         „            ,,        47  47 

Tenth  ,,          „            ,,         68  68 

Twelfth  .,          „            , Ill  110 

Fii-st  ,,    lumbar       114  114 

Second  ,,          , 138  134 

Third  ,,          151  151 

Fourtli  ,,          „            .,         163  164 

Fifth  ,,          „           , 181  180 

First  .,      sacral         188  188 

Fiftli  „          ,,            ,,        280  280 

Each  spinal  nerve,  as  it  enters  the  intervertebral  foramen,  is  enclosed  in  a  strong 
tubular  slieath  formed  by  the  dura  mater.  This  sheath  is  at  first  divided  l)y  a  par- 
tition into  two  compartments,  one  for  the  anterior  and  the  other  for  the  posterior 
root.  The  sejjtum  soon  disappears  and  allows  the  posterior  and  anterior  roots  to 
intermingle  their  fibres.  Immediately  beyond  the  ganglion  on  the  posterior  root 
the  sheath  thins  away  into  the  epineurium  and  perineurium  of  the  nerve.  The 
arachnoid  and  pia  mater  also  send  tubular  processes  around  the  nerves;  these 
become  continuous  with  the  perineurium,  and  a  connection  is  thus  estaljlished 
between  the  l3'mph  spaces  around  the  nerves  and  the  subdural  and  subarachnoid 
spaces. 

Topography. — Tlie  relation  of  the  superficial  origins  of  the  spinal  nerves  to  the 
spinous  processes  of  the  vertebne  has  been  investigated  by  Nuhn,  and  more  recently 
by  Reid.  In  the  folhjwing  table,  which  is  given  by  the  latter  anatomist,  A  signi- 
fies the  highest  point  of  origin;  B  the  lowest  point  of  origin;  it  gives  the  extreme 
limits  of  origin  as  observed  in  six  subjects.  For  example,  the  origin  of  the  sixth 
thoracic  nerve  mnr/  extend  as  high  as  the  lower  border  of  the  spine  of  the  second 
thoracic  vertebra,  or  as  low  as  the  upper  border  of  the  spine  of  the  fifth,  but  it  does 
not  necessarily  extend  either  as  high  or  as  low  as  the  points  indicated. 

Second  cersMcal     (.\)  A  little  above  the  posterior  arch  of  atlas. 

(B)  Midway  between  posterior  arch  of  atlas  and  spine  of  axis. 
Third  (A)  A  little  below  posterior  arch  of  atlas. 

(B)  Junction  of  upper  two-thirds  and  lower  third  of  si)iiie  of  axis. 
Fourtli      .,  (A)  Just  below  upper  biirdi-r  of  spine  of  axis. 

(B)  3Iiddle  of  spine  of  third  ccivical  vertebra. 
Fifth        .,  (A)  Just  below  lower  border  of  si)iiie  of  axis. 

(B)  Just  below  lower  border  of  spine  of  fourth  cervical  vertebra. 
Sixth        ..  (A)  Lower  border  of  spine  of  third  cervical  vertebra. 

(B)  Lower  border  of  sj)iue  of  fifth  cers'ical  vertebra. 
Seventh    .,  (A)  Just  below  upper  border  of  spine  of  fourth  cervical  vertebra. 

(B)  Just  above  lower  border  of  spine  of  sixth  cervical  vertebra. 
Kiirhth  (A)  Upper  border  of  spine  of  fifth  eer\ncal  vertebra. 

(B)  Upper  border  of  spine  of  seventh  cervical  vertebra. 
First     thoracic      (A)  Midway  between  spines  of  fifth  cervical  and  sixth  cervical  vertebrai. 

(B)  Junction  of  upper  two-thirds  and  lower  third  of  interval  between  seventh 
cervical  and  first  thoracic  vertebne. 
Second     ..  (A)  Tjower  border  of  spine  of  sixth  cervical  vertebra. 

(B)  Just  above  lr>wer  border  of  spine  of  first  thoracic  vertebra. 
Third       ,,  (A)  Just  above  middle  of  spine  of  seventh  ceivical  vertebra. 

(B)  Lower  border  of  spine  of  second  thoracic  vertebra. 


778 


THE  NERVOUS  SYSTEM 


Nerccs 
Fourth  thoracic     (A)  Just  below  upper  border  of  spine  of  first  thoracic  vertebra. 

(B)  Junction  of  upper  third  and  lower  two-thirds  of  spine  of  third  thonicic 
vertebra. 
Fifth         . .  (A)  Tapper  border  of  si)ine  of  second  thoracic  vertebra. 

(B)  Junction  of  upper  quarter  and  lower  three-quarters  of  spine  of  fourtli 
thoracic  vertebra. 
Sixth        .,  (A)  Lower  border  of  spine  of  second  thoracic  vertebra. 

(B)  Just  below  upper  border  of  spine  of  fifth  thoracic  vertebra. 
Seventh   .,  (A)  Junction  of  upper  third  and  lower  two-thirds  of  spine  of  fourth  thoracic 

vertebra. 
(B)  Just  above  lower  border  of  spine  of  fifth  thoracic  vertebra. 
Eighth     ,,  (A)  Junction  of  upper  two-thirds  and  lower  third  of  interval  between  spines 

of  fourth  thoracic  and  fifth  thoracic  vertebrae. 
(B)  Junction  of  upper  quarter  and   lower   three-quarters   of  spine  of  sixth 
thoracic  vertebra. 
Ninth       ,,  (A)  Midway  between  spines  of  fifth  thoracic  and  sixth  thoracic  vertebra. 

(B)  Upper  border  of  spine  of  seventh  thoracic  vertebra. 
Tenth       ,,  (A)  Midway  between  spines  of  sixth  thoracic  and  seventh  thoracic  vertebrae. 

(B)  Middle  of  spine  of  eighth  thoracic  vertebra. 
Eleventh  ,,  (A)  Junction  of  upper  quarter  and  lower  three-quarters  of  spine  of  seventh 

thoracic  vertebra. 
(B)  Just  above  spine  of  ninth  thoracic  vertebra. 
Twelfth    ,,  (A)  Junction  of  upper  quarter  and  lower  three-quarters  of  spine  of  eighth 

thoracic  vertebra. 
(B)  Just  below  spine  of  ninth  thoracic  vertebra. 
First     lumbar       (A)  Midway  between  spines  of  eighth  thoracic  and  ninth  thoracic  vertebrae. 

(B)  Lower  border  of  spine  of  tenth  thoracic  vertebra. 
Second     ,,  (A)  Middle  of  spine  of  ninth  thoracic  vertebra. 

(B)  Junction  of  upper  third  and  lower  two-thirds  of  spine  of  eleventh  thoracic 
vertebra. 
Third        ,,  (A)  Middle  of  spine  of  tenth  thoracic  vertebra. 

(B)  Just  below  spine  of  eleventh  thoracic  vertebra. 
Fourth     ,,  (A)  Just  below  spine  of  tenth  thoracic  vertebra. 

(B)  Junction  of  upper  quarter  and  lower  tlu'ee-quarters  of  spine  of  twelfth 
thoracic  vertebra. 
Fifth        ,,  (A)  Junction  of  upper  third  and  lower  two-thirds  of  spine  of  eleventh  thoracic 

vertebra. 
(B)  Middle  of  spine  of  twelfth  thoracic  vertebra. 
First      sacral         (A)  Just  above  lower  border  of  spine  of  eleventh  thoracic  vertebra. 
Fifth        ,,  (B)  Lower  border  of  spine  of  first  lumbar  vertebra. 

Coccygeal  (A)  Lower  border  of  spine  of  first  lumbar  vertebra. 

(B)  Just  below  upper  border  of  spine  of  second  lumbar  vertebra. 


Classification  and  number. — There  are  thirty-one  pairs  of  spinal  nerves,  viz. — 
eight  cervical,  twelve  tlioracic,  five  lumbar,  five  sacral,  and  one  cocc3'geal  nerve.  The 
cervical  nerves  are  named  from  the  vertebrae  below  them;  the  thoracic,  lumbar, 
sacral  and  coccygeal  nerves  from  the  vertebrae  above  them.  The  first  cervical  or 
suboccipital  nerve  escapes  through  the  interval  l)etween  the  occipital  bone  and  the 
atlas;  the  eighth  cervical  passes  through  the  intervertebral  foramen  between  the 
seventh  cervical  and  first  thoracic  vertebrae. 

General  distribution. — Each  spinal  nerve,  at  its  exit  from  the  intervertebral 
foramen,  gives  a  small  recurrent  branch  (Luschka),  which  receives  a  communicat- 
ing twig  from  the  sympathetic,  and  re-enters  the  neural  canal  to  be  distributed  to 
the  meninges  and  blood-vessels  Avithin  the  canal.  Innnediately  after  its  exit  eacli 
nerve  divides  into  an  anterior  and  a  posterior  primary  division.  Botli  the  anterior 
and  posterior  ]irimary  divisions  are  mixed  nerves,  containing  fibres  derived  from 
both  the  anterior  and  tlie  posterior  roots. 

The  posterior  primary  divisions  are,  with  two  exceptions,  smaller  than  the 
anterior  divisions.  The  posterior  divisions  of  the  first  and  second  cervical  nerves 
are  larger  than  the  anterior;  that  of  the  second  cervical  nerve  being  three  or  four 
times  as  large  as  the  anterior  division.  In  the  regions  of  the  great  plexuses 
(brachial,  lumbar,  and  sacral)  the  anterior  division  is  very  much  larger  than  the 


POSTERIOR    DIVISIONS  OF  SPIXAL   XERVES  779 

por^terior,  2»articularly  in  the  case  of  the  upper  sacral  nerves.  The  posterior  primary 
divisions  are  distrihuted  to  the  intcfrunient  of  the  occiput,  posterior  aspect  of  tlie 
neck,  of  the  back,  and  of  the  greater  part  of  the  gluteal  region.  They  also  supj)ly 
the  muscles  of  the  posterior  part  of  the  neck  and  the  muscles  of  the  back,  with  the 
exception  of  such  of  the  posterior  cervical  and  dorsal  muscles  as  are  connected  with 
the  superior  extremity,  the  serrati  postici,  and  the  levatores  costarum. 

The  anterior  primary  divisions  may  be  broadly  stated  to  supply  the  anterior 
surface  of  the  l>ody  from  the  level  of  the  chin  downwards,  and  also  the  limbs.  Each 
anterior  division  is  comiected  with  the  sympathetic  system  by  rami  communi- 
cantes.  The  anterior  divisions  contrast  forcibly  with  the  posterior  divisions  in  the 
great  size  that  they  attain  to  in  the  lower  cervical  and  lumbo-sacral  regions.  In 
these  regions  they  communicate  with  one  another  to  form  plexuses,  from  which  a 
number  of  branches  are  given  off  to  supply  the  limbs. 


POSTERIOR  PRIMARY  DIVISIONS 

The  posterior  primary  divisions  of  the  spinal  nerves  are,  Avith  the  exception 
of  the  first  and  second  cervical  nerves,  smaller  than  the  anterior  divisions.  With 
the  exception  of  the  first  cervical,  the  fourth  and  fifth  sacral  and  the  coccygeal 
nerves,  each  nerve  divides  shortly  after  its  commencement  into  an  internal  and  an 
external  branch. 

CERVICAL  NERVES. — The  posterior  divisions  of  the  first  and  second  cervical 
reipiire  separate  description.  The  third,  fourth,  and  fifth  cervical  ner\-es  are  of 
small  size.  They  pass  backwards  at  the  outer  border  of  the  semispinalis  colli, 
and  divide  into  internal  and  external  branches. 

The  internal  branches  pass  between  the  semispinalis  colli  and  the  complexus, 
giving  twigs  to  both  these  muscles  and  to  the  multifidus  spinte.  They  then  j)ass 
between  the  complexus  muscle  and  the  ligamentum  nuchae,  pierce  the  origin  of 
the  trapezius,  and  are  distributed  to  the  integument  of  the  back  of  the  neck.  As 
they  enter  the  fascite  they  are  directed  ujnvards  and  outwards.  The  branch  from 
the  third  nerve  is  directed  nearly  vertically  upwards,  and  is  called  the  third  or 
smallest  occipital  nerve.  It  connnunicates  with  the  great  occipital  nerve  and 
reaches  the  integument  of  the  occiput. 

The  external  branches  are  distributed  to  the  trachelo-mastoid,  the  cervicalis 
ascendens,  the  transversalis  colli,  and  to  the  splenius. 

The  internal  branches  of  the  sixtii,  seventh,  and  eighth  cervical  nerves  pass 
under  cover  (tf  the  semispinalis  colli,  and  end  in  that  muscle  and  in  the  adjacent 
))art  of  the  multifidus  spina\  The  external  branches  are  distributed  to  the  com- 
plexus, splenius,  cervicalis  ascendens,  and  transversalis  colli  muscles. 

The  posterior  primary  division  of  the  first  cervical  nerve  passes  backwards 
between  the  posterior  arch  of  the  atlas  and  tlie  vertel)ral  artery,  and  traverses  the 
fatty  tissue  which  occu})ies  the  triangular  space  bounded  by  the  ol)liquus  superior, 
the  oljlicpus  inferior,  and  the  rectus  capitis  posticus  major.  It  gives?  a  branch  to 
each  of  these  three  muscles,  and  a  twig  which  crosses  the  superficial  surface  of  the 
rectus  capitis  posticus  major  to  reach  the  rectus  capitis  posticus  minor.  Another 
twig  forms  a  communicating  loo]i  with  the  great  occipital  nerve  on  the  posterior 
surface  of  the  oWiquus  inferior.  A  l)raneh  is  also  furnished  to  the  complexus.  In 
a  few  cases  it  gives  a  cutaneous  twig  to  the  back  of  the  occiput. 

The  posterior  division  of  the  second  cervical  nerve  divides  into  a  small 
external  and  a  very  large  internal  ln-anch.  The  external  branch  gives  a  twig  to  the 
obli(|UUs  inferior,  and  ends  in  the  complexus  and  trachelo-mastoid  nuiscles.  The 
internal  branch  is  the  great  occipital  nerve.  It  gives  ofif  communicating  l)ranches 
which  pass  upwards  and  downwards,  forming  loops  with  the  first  and  third  cervical 
nerves.  In  this  manner  a  small  plexus  (i)osterior  cervical  plexus  of  Cruveilhier) 
is  formed.  The  great  occipital  nerve  is  then  directed  upwards,  crossing  the  trian- 
gular space  descril)ed  in  connection  with  the  first  nerve,  and  being  covered  by  the 
complexus.  It  gives  one  or  two  twigs  to  the  latti-r  muscle,  and  then  ])ierces  it  to 
reach  the  deep  surface  of  the  trapezius.      It  pierces    the  outer  border  of  the  trape- 


7S0 


THE  XER VOL'S  SYSTEM 


zius  imniediately  below  the  superior  cairved  line,  and  divides  at  acute  angles  into 
a  number  of  l)ranehes,  which  ramify  in  the  scalp.  Tliese  branches  comnmnicate 
freely  with  the  lesser  occipital  nerve,  and  run  in  the  subcutaneous  fat  between  the 
skin  and  the  occipito-frontalis.    In  this  situation  they  are  accompanied  by  l)ran(hes 

Fig.  452. — Distribution  of  the  Posterior  Primary  Divisions  of 
THE  Spinal  Nerves.    (Henle.) 


Semi-spinalis 


Multifldua  spinae 


Ilio-costaliB 


Hhoni  boideus 
major 


liatissinius 
dorsi 


of  the  occipital  artery.  They  supply  the  integument  which  covers  the  ])()rtion  of  the 
occipital  bone  above  the  superior  curved  line,  and  the  ])()sterior  ])art  of  the  parietal 
bone.  One  of  them  occasionally  reaclu's  the  pinna  and  supplies  the  skin  on  the 
upper  part  of  its  inner  asi)ect. 


POSrERIOR   DIVISIONS  OF  SPINAL   NERVES  781 

THORACIC  NERVES. — The  pos^tcrior  i)riiimrv  divit^ioii.s  of  the  thoracic  nerves 
I)ass  backwards  between  the  transverse  processes  of  the  thoracic  vertebrae,  and 
divide  into  internal  and  external  branches.  The  internal  branches  become  })ro- 
gressively  smaller  from  the  second  to  the  last  of  the  series.  The  external  branches 
show  a  reciprocal  increase  in  size. 

The  internal  branches  pass  to  the  inner  side  of  the  longissimus  dorsi,  giving 
branches  to  that  muscle  and  to  the  sj)inalis  dorsi,  semis})inalis,  multifidus  spina;, 
rotatorcs  spinte,  intertransversales,  and  interspinales.  Large  branches  from  the 
upper  six  or  seven  nerves  reach  the  surface  l)y  piercing  the  origin  of  the  trapezius 
close  to  the  spinous  processes  of  the  vertebrae  They  run  outwards  in  the  superfi- 
cial fascia,  and  supply  the  integument  of  the  back,  including  the  skin  over  the 
imier  half  of  the  infraspinous  part  of  the  dorsum  scapula)  and  the  integument  over 
th(!  supraspinous  fossa.  The  cutaneous  branch  of  the  second  nerve  is  the  largest  of 
tlie  series.  Frtun  the  lower  five  or  six  nerves  small  twigs  usually  reach  the  surface 
and  become  cutaneous. 

Tlie  external  branches  of  the  ui)per  six  or  seven  nerves  end  in  the  accessorius 
and  longissimus  dorsi  muscles.  The  lower  five  or  six,  after  supplying  the  adjacent 
muscles,  pierce  the  outer  series  of  insertions  of  the  longissimus  dorsi,  and  appear 
in  the  interval  between  that  muscle  and  the  accessorius.  They  then  pierce  the 
latissimus  dorsi,  and  are  distributed  to  the  integument  on  the  lower  and  outer  part 
of  the  back. 

LUMBAR  NERVES. — The  internal  branches  of  all  the  lumbar  nerves  end  in 
the  multifidus  spin;e. 

The  external  branches  of  the  upper  three  nerves,  after  supplying  twigs  to 
the  adjacent  muscles,  pierce  the  posterior  layer  of  the  lumbar  aponeurosis  at  the 
outer  border  of  the  erector  spinjB.  The  three  nerves  cross  the  crest  of  the  ilium 
and  occupy  different  planes  in  the  thick  superficial  fascia  which  covers  the  upper 
part  of  the  gluteus  medius.  The  branch  from  the  first  nerve  is  comparatively 
small,  and  occupies  the  most  superficial  plane.  The  second  occupies  an  interme- 
diate j)Osition.  The  branch  from  the  third  nerve  is  the  largest  of  the  three,  and 
occupies  the  deepest  position;  it  distributes  branches  over  the  gluteus  maximus  as 
far  as  the  great  trochanter.  The  three  nerves  communicate  Avith  one  another  and 
also  with  the  cutaneous  branches  from  the  i)osterior  divisions  of  the  two  upper 
sacral  nerves.  The  external  branch  of  the  fourth  lumbar  nerve  is  of  small 
size  and  ends  in  the  lower  part  of  the  erector  sjjina'.  The  external  branch  of  the 
fifth  lumbar  is  distributed  to  the  erector  spinas  and  communicates  with  the  first 
sacral  nerve. 

SACRAL  AND  COCCYGEAL  NERVES. — The  posterior  divisions  of  the  upjier 
four  sacral  nerves  csca]>e  from  the  neural  canal  by  passing  through  the  posterior 
sacral  foramina;  the  fifth  sacral  nerve  passes  between  the  sacrum  and  coccyx.  The 
coccygeal  nerve  escapes  through  the  termination  of  the  neural  canal.  The  upper 
three  sacral  nerves  divide  in  the  ordinary  manner  into  internal  and  external 
branches,  the  lower  two  sacral  and  the  coccygeal  nerves  remain  undivided. 

The  internal  branches  of  the  U])per  three  sacral  nerves  are  of  small  size,  and 
are  distri])Uted  to  the  multifidus  sj^ina*.  The  external  branches  unite  with  one 
another  and  with  the  external  branch  of  the  last  lumbar  nerve  to  form  loops  on  the 
])osterior  surface  of  the  sacrum.  From  these  loops  branches  proceed  to  the  poste- 
rior surface  of  the  great  sacro-sciatic  ligament,  where  they  communicate  to  form 
a  second  series  of  loo{)s,  whence  two  or  three  branches  are  given  ofl^.  These 
branches  pierce  the  gluteus  maximus  and  come  to  the  surface  of  that  muscle  in  a 
line  between  the  posterior  superior  spine  of  the  ilium  and  the  tip  of  the  coccyx. 
Tiiey  are  distributed  to  the  integument  over  the  inner  part  of  the  gluteus  maximus, 
and  connnunicate,  in  their  course  through  the  superficial  fascia,  with  the  posterior 
branches  of  the  linnbar  nerves. 

The  posterior  divisions  of  the  lower  two  sacral  and  of  the  coccygeal  nerve 
unite  with  one  another  and  with  the  posterior  l)ranch  of  the  third  sacral,  and  form 
loops  whence  twigs  pass  to  the  integument  over  the  lower  end  of  the  cocc^'x. 


782 


THE  XKRVOrS  SYSTEM 


ANTERIOR  PRIMARY  DIVISIONS 

The  anterior  divisions  of  the  spinal  nerves  (with  the  two  exceptions  above  men- 
tioned) are  hirger  than  the  posterior  divisions,  and  each  is  connected  by  one  or  two 
rami  commimicantes  with  the  ganglionated  cord  of  the  sympathetic.  In  the  cervi- 
cal, lumbar,  sacral,  and  coccygeal  regions  they  combine  to  form  plexuses;  in  the 
thoracic  region  each  nerve  takes  for  the  most  part  an  independent  course,  and  its 
typical  division  into  a  lateral  or  dorsal,  and  an  anterior  or  ventral  branch  is  very 
obvious.  This  division,  however,  is  not  confined  to  the  dorsal  nerves;  it  is  recog- 
nisable, though  with  more  difficulty,  in  the  lower  cervical,  lumliar,  and  sacral 
regions,  and  it  cannot  be  clearly  distinguished  in  the  upper  cervical  and  coc- 
cygeal regions. 

CERVICAL  NERVES. — The  anterior  primar}^  divisions  of  the  upper  four  cervical 
nerves  are  of  moderate  size;  each  is  connected  by  one  or  two  branches  with  the 
superior  cervical  ganglion  of  the  sympathetic,  and  they  unite  with  one  another  to 
form    a   looped    plexus,   the   cervical   plexus.     The  anterior  primary  division   of 


LESSER 
OCCIPITAL 

TO  RECTrS 

CA  PITIS 
LATERALIS 

TO  RECTUS 

CA  PITIS 

AMICUS 

MINOR 

AND  MAJOR 


STERyO- 
MASTOID 


SCALENUS 
M EDI  US 

LEVATOR 
ANGULI 

SCA  PULJE 

SCALE.VrS 

MEDIUS 
LEV.  A.VG. 
SCAPULA 


FROM  FIFTH 
CERVICAL 


PHRENIC 


Fui.  453. — Diagram  of  the  Cervical  Plexus. 


PERFICIAL 


HYPOGLOSSAL 

TO  GENIO- 
HYOID 

TO  THYRO- 
HYOID 

TO  OMOHYOID 


TO  STERNO-HYOID 

TO  STERNO- 
THYROID 

TO  OMO-HYOin 
(POST-BEI.l.Y) 
TO   TRAPEZIUS 


SUPRA- 

ACROMIAL 

SUPRA- 
CLA  VICULAR 

SUPRA- 
STERNAL 


\ 


the  first  cervical  nerve,  smaller  than  the  posterior  division,  passes  outwards  in  the 
groove  on  tlie  posterior  arch  of  the  atlas  beneath  the  vertebral  artery,  turns 
forwards  ])etween  the  vertebral  artery  and  the  lateral  mass  of  the  atlas,  and  bends 
downwards  in  front  of  the  transverse  process  of  that  l)one  to  unite  witli  the  second 
nerve.  The  anterior  division  of  the  second  nerve  runs  outwards  behind  the  superior 
articular  process  of  the  axis,  passes  behind  and  to  the  outer  side  of  the  verteljriil 
artery  and  in  frtint  of  the  second  posterior  intertransverse  muscle  to  the  interval 
between  the  scalenus  medius  and  the  rectus  capitis  anticus  major,  where  it  unites 
with  the  first  and  third  nerves.  The  anterior  divisions  of  the  third  and  fourth 
nerves,  after  their  exits  from  the  intervertebral  foramina,  pass  behind  the  verte- 
bral artery  and  between  the  anterior  and  posterior  intertransverse  muscles  to 
appear  in  tlie  intersi)ace  between  th(>  rectus  capitis  antieus  major  and  the  s('alenus 


CERVICAL   NERVES  783 

niedius,  where  tlie  tliird  unites  with  the  see(jiid  and  fourth  nerves,  eoni})letin^  the 
plexus. 

The  lower  four  cervical  nerves  increase  rapidly  in  size  from  the  fifth  to  the 
eighth,  and  unite  with  the  greater  part  of  the  first  thoracic  nerve  to  fomi  the 
brachial  plexus.  Each  of  these  nerves  is  connected  by  one  or  two  twigs  to  the 
cervical  sympathetic. 

cp:rvical  plexl^s 

The  anterior  divisions  of  the  upper  four  cervical  nerves  unite  to  form  the 
cervical  plexus  in  the  following  manner:  the  second  and  third  nerves  are  connected 
hy  ascending  and  descending  branches  with  one  another,  and  with  the  first  and 
fourth  nerves.  In  this  way  a  series  of  three  loops  is  formed.  The  fourth  nerve  is 
also  connected  with  the  brachial  plexus  by  a  descending  twig.  The  plexus  lies  in 
the  upper  part  of  the  side  of  the  neck,  upon  the  scalenus  medius  muscle,  and 
under  cover  of  the  u})per  part  of  the  sterno-mastoid.  The  branches  of  the  plexus 
are  classified  into  a  superficial  and  a  deep  series.  The  superficial  series  is  sub- 
divided into  ascending,  transverse,  and  descending  branches;  the  deep  series  into 
external  and  internal  Ijranches. 

Superficial  Branches 

Ascending  branches. — 1.  The  lesser  occipital  nerve  is  derived  from  the 
second  cervical.  It  i)asses  backwards  and  slightly  ui)wards  under  cover  of  the 
sterno-mastoid  muscle  to  reach  the  posterior  border  of  that  muscle.  It  then  ascends, 
running  parallel  to  the  posterior  l)order  of  the  muscle,  being  occasionally  overlapped 
liy  it,  and  passes  on  to  the  scalp,  where  it  divides  into  auricular,  mastoid,  and 
occi{)ital  l)ranches.  (a)  The  auricular  branch  runs  upwards  and  slightly  forwards 
to  reach  the  integument  on  the  jjosterior  and  up])er  part  of  the  pinna,  and  is  dis- 
tributed there.  (6)  The  mastoid  branch  is  distributed  to  the  skin  covering  the 
base  of  the  mastoid  process,  (c)  The  occipital  branches  ramify  over  the  occipi- 
talis muscle,  and  are  distributed  to  the  skin  of  the  scalp;  they  communicate  with 
one  another  and  wath  the  great  occipital  nel've.  The  branches  of  the  small  occipital 
nerve  anastomose  with  twigs  of  the  posterior  auricular,  great  auricular,  and  great 
occipital  nerves. 

2.  The  great  auricular  nerve  arises  by  two  roots,  one  from  the  second,  and 
the  other  from  the  third  cervicid  nerve.  It  acconi])anies  the  lesser  occipital  nerve 
as  far  as  the  posterior  border  of  the  sterno-mastoid.  and  then  Avinds  round  that 
muscle,  and  crosses  it  obliquely.  In  this  course  it  runs  upwards  and  forwards 
towards  the  tip  of  the  mastoid  process,  and  is  covered  by  the  skin,  sujierficial  fascia, 
and  platysma.  At  a  point  about  the  centre  of  its  course  across  the  sterno-mastoid 
muscle,  it  begins  to  divide  into  branches,  which  diverge  from  one  another  as  the}' 
approach  the  level  of  the  mastoid  ])rocess,  forming  mastoid,  auricular,  and  facial 
branches,  (a)  The  mastoid  branch  is  small,  and  is  distributed  to  the  integument 
covering  the  mastoid  process.  It  anastomoses  with  the  ])osterior  auricular  and 
small  occipital  nerves,  (b)  The  auricular  branches  are  three  or  four  stcnit  twigs 
which  anastomose  with  the  l)ranches  of  the  posterior  auricular  nerve;  they  cross 
the  superficial  surface  of  the  posterior  auricular  branch  of  the  facial,  and  are 
distributed  to  the  skin  on  the  back  of  the  pinna  with  the  exception  of  its  upi)ermost 
j>art.  One  or  two  twigs  pass  through  fissures  in  the  cartilage  of  the  ear,  and  are 
distributed  to  the  integument  on  the  outer  surface  of  the  lobule  and  the  outer 
surface  of  the  loAver  part  of  the  helix  and  antihelix.  (c)  The  facial  branches  pass 
upwards  and  forwards  among  the  su|)erticial  lobules  of  the  parotid  and  ^u])ply  the 
skin  over  that  gland  and  immediately  in  frcMit  of  it,  and  they  anastomose  in  the 
substance  of  the  gland  with  the  cervico-facial  division  of  the  facial  nerve.  In  some 
cases  fine  twigs  may  l)e  traced  forwards  nearly  to  the  angle  of  the  mouth. 

Transverse  branch. — Tiie  superficial  cervical  nerve  arises  from  the  second 
and  tliird  nerves,  and  api)ears  at  the  i)osterior  border  of  the  sterno-mastoid,  a 
little  below^  the  great  auricular  nerve.  It  jjasses  transversely  across  the  sterno- 
mastoid  under  cover  of  the  integuments,  platysma,  and  external  jugular  vein.      It 


784 


THE  XERVOUS  SYSTEM 


divides  into  a  luuiiljor  of  twigs  which  spread  out  after  the  manner  of  a  fan,  and 
extend,  as  they  approach  the  middle  Une,  from  the  chin  to  the  sternum.  The 
upper  two  or  three  of  these  twigs  unite,  beneath  the  platysma,  with  the  infra-mandi- 
bular  branch  of  the  facial,  and  thus  form  loops.  From  the  terminal  branches  of 
the  nerve  numerous  twigs  ])ierce  the  platysma  to  end  in  the  skin  of  the  front  part  of 

the  neck. 

Descending  branches. — These  are  derived  from  the  third  and  fourth  cervical 
nerves,  and  arise  under  cover  of  the  sterno-mastoid.  At  their  conmiencement  they 
are  usually  united  with  the  muscular  branches  destined  for  the  trapezius.     They 


Fig.  454.— Superficial  Beanches  of  the  Cervical  Plexus. 
(After  Hirschfeld  aud   Leveille. ) 


POSTERIOR 

AURICULAR 
NER  VE 


FACIAL  NERVE 


AURICULAR  BR.  OF  

GREAT  AURICULAR      ^ 

INFRAMANDIB  ULAR 


SUPERFICIAL   CERVICAL 
BRANCHES  OF  SUPER 
FICIAL  CERVICAL 
NERVE 


SUPRA  STERNA  L 


\  BRANCHES  OF 
y         GREA T 
\     AURICULAR 

GREAT  OCCIPITAL 


LESSER  OCCIPITAL 


GREAT  AURICULAR 
MASTOID  BR.  OR  Slid 

SMALL  OCCIPITAL 
SPINAL  ACCESSORY 

TWIGS  FROM  THE 
MASTOID  BRAyCff 

BR.  TO  LEVATOR 

ANGULI  SCAPULJi 
SUPRA- A  CROMIAL 

SUPRA  CLA  VICULA  R 


BRANCHES  TO 

TRAPEZIUS 


SUPRACLA  VICULAR 


>^^^^. 


become  superficial  at  the  posterior  liorder  of  the  storno-mastoid,  about  the  centre 
of  that  muscle,  and  are  termed  sui)ra-sternal,  supra-clavicular,  and  supra-acronnal 
nerves.  (1)  The  supra-sternal  twigs  are  small,  and  cross  over  tbe  clavicular  origin 
of  the  sterno-mastoid  to  reach  the  integument  over  the  upper  part  of  the  manu- 
brium sterni.  They  also  supply  the  sterno-clavicular  joint.  (2)  The  supra- 
clavicular nerves,' of  considerable  size,  cross  in  front  of  the  middle  third  of  the 
clavicle  under  cover  of  the  platysma,  and  are  distributed  to  the  skin,  covermg 
the  upper  ]mrt  of  the  pectoralis  major  as  low  as  the  third  rib.  (3)  The  supra- 
acromial  branches  cross  the  clavicular  insertion  of  the  trapezius  and  the  acromion 


CERVICAL   XERVES  7S5 

process,  and  are  distributed  to  the  skin  which  invests  the  upper  two-thirds  of  the 
deltoid  muscle.     They  supply  the  acromio-clavicular  joint. 

Deep  Branches 

External  branches. — The.se  consist  of  communicating  branches  from  the  second 
and  third  cervical  nerves  to  the  signal  accessory,  and  of  muscular  branches  which 
supply  the  sterno-mastoid,  scalenus  medius,  levator  anguli  scapulae,  and  trapezius. 

1.  The  nerve  to  the  sterno-mastoid  arises  from  the  second  cervical  nerve.  It 
pierces  the  deep  surface  of  the  sterno-mastoid,  and  communicates  within  the  muscle 
with  the  spinal  accessory  nerve. 

2.  The  nerves  to  the  scalenus  medius  are  derived  from  the  third  and  fourth 
cervical  nerves  close  to  their  exit  from  tli(!  intervertebral  foramina. 

3.  The  nerves  to  the  levator  anguli  scapulae  are  derived  from  the  third  and 
fourth  nerves,  and  occasionally  from  the  second.  They  pierce  the  superficial  surface 
of  the  levator  anguli,  and  supply  the  upper  three  divisions  of  that  muscle. 

4.  The  branches  to  the  trapezius  are  usually  in  the  form  of  two  stout  twigs 
which  are  given  off  Ijy  the  third  and  fourth  cervical  nerves.  They  emerge  at  the 
posterior  border  of  the  sterno-mastoid,  and  cross  the  posterior  superior  triangle  oi 
the  neck  at  a  lower  level  than  the  spinal  accessory  nerve.  They  pass  under  cover 
of  the  trapezius  in  company  with  the  last-named  ners-e,  and  communicate  with  it 
to  form  the  subtrapezial  plexus,  from  which  the  trapezius  is  supplied. 

Internal  branches. — The  internal  set  of  deep  branches  comprise  communicat- 
ing branches  and  muscular  branches.  1.  The  communicating  branches  pass  to 
the  vagus  and  hypoglossal  nen^es,  from  the  loop  formed  by  the  first  and  second 
nerves,  and  to  the  sympathetic  from  all  of  the  four  ner^^es  which  enter  into  the 
cervical  plexus.  The  muscular  branches  are  distributed  to  the  rectus  capitis 
lateralis,  to  the  recti  capitis  antici  major  and  minor,  to  the  longus  colli,  to  tlie 
depressors  of  the  hyoid  bone  (communicantes  hypoglossi),  and  to  the  diaphragm 
(phrenic  nerve). 

2.  The  branch  to  the  rectus  capitis  lateralis  is  furnished  to  that  muscle  l)y 
the  first  nerve  as  it  cro.^ses  the  deep  surface  of  the  muscle. 

3.  The  nerve  to  the  rectus  capitis  anticus  minor  is  given  off  by  the  first 
nerve  at  the  upper  part  of  the  loop  in  front  of  the  transverse  process  of  the  atlas. 

4.  The  rectus  capitis  anticus  major  receives  twigs  from  the  upper  four  cervi- 
cal nerv^es. 

5.  The  longus  colli  receives  branches  from  the  second,  third,  and  fourth  cervi- 
cal nerves,  and  additional  branches  also  from  the  fifth  and  sixth  nerves. 

6.  The  communicantes  hypoglossi  are  given  off  by  the  second  and  third 
cervical  nerves,  and  run  oblicpiely  downwards  and  inwards  in  front  of  the  great 
vessels  of  the  neck  to  form  a  loop,  the  ansa  hypoglossi,  with  the  so-called  descen- 
dens  hypoglossi.  They  supply  the  depressor  muscles  of  the  hyoid  bone.  (See 
HvpoGLOss.\L  Nerve.  ) 

7.  The  PHRENIC  NERVE  may  arise  by  one,  two,  or  three  roots,  the  strongest, 
and  occasionally  the  only,  root  being  derived  from  the  fourth  cervical  nerve.  A 
root  from  the  fifth  is  commonly  ])resent,  and  is  usually  associated  either  with  the 
nerve  to  the  subclavius  or  Avith  the  communicating  branch  which  passes  from  the 
cervical  to  the  brachial  plexus.  A  slender  root  from  the  third  nerve  is  occasionallv 
present.  The  cervical  sympathetic  also  furnishes  a  communicating  twig.  The 
phrenic  ner\'e  passes  downwards  and  inwards  under  cover  of  .the  sterno-mastoid, 
cros.sing  obliquely  in  front  of  the  scalenus  anticus  muscle.  It  is  Crossed  by  the  tran.s- 
verse  cervical  and  suprascapular  arteries,  and  also  by  the  omo-hyoid  muscle.  It 
pa.sses  behind  the  subclavian  vein,  and  enters  the  thorax.  In  this  situation  it  crosses 
in  front  of  or  behind  the  commencement  of  the  internal  manmiarv  artery,  and  is 
commonly  joined  at  this  point  by  a  communicating  twig  from  the  nerve  to  the  sub- 
clavius muscle.  On  the  left  side  it  is  crossed,  in  addition,  by  the  terminal  part  of 
the  thoracic  duct. 

The  further  course  of  the  phrenic  differs  on  the  two  sides.     On  the  right  side 
the  nerve  passes  downwards,  running  on  the  outer  side  of  the  right  innominate 
vein,  the  superior  vena  cava,  and   the   pericardium.  Vietween   these  structures  and 
50 


786 


THE  NERVOUS  SYSTEM 


the  pleura.  In  its  course  between  tlie  pericardium  and  pleura  it  crosses  in  front 
of  the  root  of  the  lung.  It  tlien  pierces  the  diaphragm  immediately  on  the 
left  side  of  the  opening  for  the  vena  cava  inferior,  and  is  distril>uted  to  the 
diaphragm,  the  branches  entering  the  muscle  on  its  lower  surface.  On  the  left 
side  the  ])hrenic  nerve  passes  on  to  tlie  left  side  of  the  aortic  arch,  Ijetween  the  latter 
and  the  pleura,  and  in  front  of  the  inferior  cervical  cardiac  branch  of  the  vagus.  It 
then  runs  downwards  between  the  pericardium  and  the  })leura  in  front  of  the  root 
of  the  lung,  taking  a  longer  course  tlian  on  the  right  side  in  consequence  of  the  incli- 
nation of  the  heart  to  the  left  side,  and  also  on  account  of  the  lower  level  of  the  left 
cupola  oi  the  diaphragm.  It  pierces  the  diaphragm  immediately  to  the  left  of  the 
attachment  of  the  pericardium  to  that  muscle,  and  is  distributed  to  its  abdominal 
surface  in  a  similar  manner  to  the  nerve  on  the  right  side. 

Branches. — Minute  twigs  are  supplied  (a)  to  the  pleura;  and  (6)  to  the 
pericardium.  On  the  right  side  the  nerve  communicates  with  the  diaphragmatic 
plexus  of  the  sympathetic,  forming  a  small  ganglion  (ganglion  diaphragmat- 
icum  I. 


BRACHIAL  PLEXUS 

The  BRACHIAL  PLEXUS  is  formed  by  the  anterior  primary  divisions  of  the 
four  lower  cervical  nerves  and  the  greater  i)art  of  the  first  thoracic  nerve  ;  it 
is  usually  joined  l)y  small  communicating  twigs  from  the  fourth  cervical  and 
second  thoracic  nerves.     The  four  lower  cervical  nerves  emerge  in  the  interval 


Fig.  455. — Diagram  of  the  Brachial  Tlexis. 
The  posterior  cord  of  the  plexus  is  darkly  shaded. 

FROM  FOURTH  CERVICAL 


FIFTH 
CERVICAL 


SIXTH 
CERVICAL 


HEVEXTH 
CERVICAL     x^ 
TO  SCALENI  &       '     \S\ 

Loyors  COLLI 

EKiHTH 
CERVICAL 
POSTERIOR 
THORA  CIC 

FIRST 
THORACIC 

FIRST 
INTERCOSTAL 

sEcoyn 

THORA  CIC 
SECOND 
INTERCOSTAL 
THIRD 
THORACIC 
THIRD 
INTERCOSTAL 


RHOMBOID  NERVE 
TO  PHRENIC 


■NERVE  TO  SUBCLAVIUS 

SUPRASCAPULAR 


EXTERNAL  ANTERIOR  THORACIC 

—  OUTER  CORD  OF  PLEXUS 
CIRCUMFLEX 
MUSCUL  O-  CUT  A  NEO I 'S 
MUSCULO-SPIRA  L 
INNER  CORD  OF  PLEXUS 
LONG 
SUBSCAPULAR 


MEDIAN 


ULNAR 
INTERNA  L 
CUTANEOUS 

NERVE  OF 
WRISBhRCr 


INTER  COS  TO- HUMERAL        LATERAL  CUTANEOUS 


between  the  anterior  and  nuddle  scaleni  muscles.  The  first  thoracic  nerve,  after 
traversing  the  intervertebral  foramen  between  the  first  and  second  tlioracic  vertebra', 
appears  in  the  first  intercostal  space  and,  after  giving  off  the  small  first  intercostal 
nerve,  crosses  the  inner  margin  and  upper  surface  of  the  first  rib  ol)li(iuely,  and 
joins  the  eighth  cervical  nerve. 

The  brachial  plexus  is  divisible  into  four  distinct  stages,      in  the  first  stage  all 


BRA.WHES  OF  BRACHIAL    P LEXISES  787 

tlif  cumjjoiicnt  nerves  are  sejKinite  from  <'aeh  other.  In  the  secund  stage  the  nerves 
unite  witli  one  another  to  form  three  trunks.  In  the  third  stage  the  trunks  divide 
into  anterior  and  posterior  divisions.  In  the  fourth  stage  tlie  six  divisions 
l)eeonie  collected  into  three  rounded  bundles,  which  are  termed  cords. 

The  tifth  and  sixth,  and  usually  a  communicating  twig  from  the  fourth,  cervical 
nerves  unite  to  form  the  upper  trunk;  the  seventh  remains  indeiiendent  and  forms 
the  middle  trunk;  the  eiglith  cervical  and  first  thoracic,  with  occasionally  a  c(tm- 
municatiiiLT  twig  from  the  second  thoracic,  imite  to  form  the  lower  trunk.  Eacli  of 
these  trunks  divides  into  an  anterior  and  a  jtosterior  division.  The  anterior  and 
posterior  divisions  of  the  upper  and  middle  trunks  are  al>out  equal  in  size.  The 
anterior  division  of  the  lower  trunk  is  very  much  larger  than  the  j)osterior  division. 
The  three  posterior  divisions  unite  to  form  the  posterior  cord.  The  anterior 
divisions  of  the  upper  and  middle  trunks  join  to  form  the  outer  cord.  The  anterior 
division  of  the  lower  trunk  is  c(Mitinued  into  the  inner  cord. 

The  first  stage  of  the  plexus  is  situated  upon  the  middle  scalene  in  the 
posterior  triangle  of  the  neck.  The  second  stage  is  placed  in  th<'  posterior  inferior 
triangle  of  tlie  neck,  the  lower  trunk  of  the  ]ilcxus  l)eing  Itehind  the  third  stage  of 
the  subclavian  artery  and  the  upper  and  middle  trunks  aljove  and  on  a  plane 
posterior  to  that  vessel.  When  a  posterior  scapular  artery  arises  from  the  third 
stage  of  the  subclavian,  it  passes  backwards  Ix-tween  the  trunks  of  the  plexus.  In 
its  third  stage  the  plexus  lies  under  cover  of  the  clavicle  and  subclavius  muscle, 
and  is  placed  al)Ove,  external,  and  on  a  plane  posterior  to  the  axillary  artery.  In 
its  fourth  stage  the  plexus  is  situated  under  cover  of  the  pectoral  muscles,  and  the 
cords  surround  the  second  stage  of  the  axillar}'  artery,  occupying  the  positions 
indicated  by  their  names,  the  external  cord  being  in  contact  with  the  outer  side  of 
the  artery,  the  internal  cord  on  the  inner  side,  and  the  posterior  cord  behind  the 
vessel.  A  little  external  to  the  outer  border  of  the  pectoralis  minor,  the  plexus 
terminates  by  dividing  into  large  nerves,  wliich  surround  the  third  stage  of  the 
axillary  artery. 

The  branches  of  the  brachial  plexus  are  classified  into  branches  which  arise 
above  the  clavicle,  and  branches  which  are  given  off  beloAv  that  bone.  The  branches 
which  arise  below  the  clavicle  may  be  conveniently  subdiA-ided  into  short  branches 
which  end  in  the  axilla,  and  long  branches  which  arise  from  the  terminations  of  the 
three  cords  and  are  destined  to  supply  the  shoulder,  arm,  forearm,  and  hand. 

Braxciies  given  off  Ai«nE  THE  Clavicle 

These  are  all  nuiscular  l>ranches,  and  com])rise  the  following  nerves: — (\)  Supra- 
scapular; (2)  rhomboid;  To)  posterior  thoracic;  (4)  communicating  to  the  phrenic; 
nerves  to  (5)  the  sul)clavius,  ((>;  scaleni,  and  (7)  longus  colli. 

(1)  The  suprascapular  nerve  arises  from  the  upper  trunk  of  the  plexus,  and 
therefore  contains  fibres  derived  from  the  fifth  and  sixth,  and  in  some  cases  from 
the  fourth,  cervical  nerves.  It  runs  downwards  and  outwards,  crosses  internal  to 
the  posterior  belly  of  the  omo-hyoid  muscle,  and  passes  imder  cover  of  the  trapezius 
to  reach  the  suprascapular  notch;  here  it  crosses  the  suprascapular  artery,  and  takes 
a  lower  position  than  that  vessel.  It  then  passes  through  the  suprascapular  notch 
beneath  the  transverse  ligament,  and,  after  furnishing  a  twig  to  tlie  .«houlder  joint, 
divides  into  a  supraspinous  and  an  infras]iin(»us  l)ranch.  The  sujn-aspinous  branch 
inclines  inwards  and  ends  in  the  supraspinatus  muscle.  The  infraspinous  branch 
passes  through  the  great  scapular  notch  under  cover  of  the  spino-glenoid  ligament, 
and  terminates  in  the  infrasjnnatus  muscle. 

(2)  The  nerve  to  the  rhomboids  arises  from  the  fifth  cerA'ical  nerve  shortly 
after  its  exit  from  the  intervertebral  foramen.  It  arises  in  connnon  with  the  u]»per 
root  of  the  posterior  thoracic  nerve,  and  passes  V)ackwards  and  outwards  through 
the  fibres  of  the  scalenus  medius.  It  then  usually  divides  in  a  jdexiform  manner 
into  several  ])ranches,  the  strongest  of  which  pa.^ses  below  the  levator  anguli 
scapula^  while  the  others  traverse  the  lowest  division  of  that  nuiscle  and  supply  it 
with  one  or  more  twigs.  In  the  c(^llular  interval  l)etween  the  levator  and  therhom- 
boideus  minor,  the  twigs  reunite  to  form  one  nerv<\  which  jia.^ses  to  the  deeji  surface 
of  the  two  rhomboid  muscles  and  supplies  them. 


788  THE  NERVOUS  SYSTEM 

(3)  The  posterior  thoracic  nerve  (external  respiratory  of  Bell)  arises,  by  three 
roots,  from  the  fifth,  sixth,  and  seventh  eervical  nerves.  The  upper  two  roots 
traverse  the  substance  of  the  scalenus  niedius;  the  root  from  the  seventh  passes  in 
front  of  that  muscle.  Twigs  are  furnished  to  the  superior  portion  of  the  serratus 
magnus  1)V  the  upper  two  roots;  lower  down  they  unite  and  are  su))sequently  joined 
by  the  root  from  the  se\'enth.  The  nerve  now  passes  downwards  behind  the  brachial 
plexus  and  the  first  stage  of  the  axillary  artery,  and  runs  along  the  axillary  surface 
of  the  serratus  magnus,  supplying  twigs  to  each  of  the  digitations  of  that  muscle. 

(4)  The  communicating  twig  to  the  phrenic  arises  from  the  tifth  nerve  close 
to  the  point  where  the  latter  nerve  receives  the  connnunicating  twig  from  the  cervical 
plexus. 

(5)  The  nerve  to  the  subclavius  is  a  small  twig  which  arises  from  the  fifth 
nerve  or  from  the  upper  trunk  of  tlie  plexus.  Its  tiln-es  are  derived  from  the  fifth 
or  in  some  cases  from  the  fourth  cervical  nerve  through  the  connnunicating  twig 
from  the  cervical  plexus.  It  run  downwards  in  front  of  the  tliird  stage  of  the  sub- 
clavian artery  and,  after  giving  off  a  communicating  l:>ranch  to  the  phrenic,  pierces 
the  posterior  layer  of  the  costo-coracoid  membrane,  and  enters  the  subclavius  at 
the  lower  border  of  that  muscle. 

Variety, — In  rare  cases  the  entire  phrenic  nerve  may  pass  via  the  nerve  to  the  suhclavius  in 
front  of  tlie  third  stage  of  the  subclavian  artery. 

(6)  The  scnleni  and  (7)  longus  colli  are  supplied  by  twigs  Avliich  arise  from 
the  lower  two  or  three  cervical  nerves  immediately  after  their  exit  from  tlie 
intervertebral  foramina. 

Branches  given  off  below  the  Clavicle 

The  AXILLARY  or  SHORT  BRANCHES  are  (1)  the  external  and  (2)  internal 
anterior  thoracic,  and  (3)  the  three  subscapular  nerves. 

(1)  The  external  anterior  thoracic  nerve  arises  from  the  outer  cord  of  the 
plexus;  it  contains  fibres  from  the  fifth,  sixth  and  seventh  nerves.  After  communi- 
cating with  the  internal  anterior  thoracic,  it  pierces  the  costo-coracoid  membrane 
and  ends  in  branches  which  supply  the  pectoralis  major. 

(2)  The  internal  anterior  thoracic  nerve  arises  from  the  inner  cord  and  passes 
forwards  between  the  first  stage  of  the  axillary  artery  and  the  axillary  vein.  It 
contains  fibres  of  the  eighth  cervical  and  first  dorsal  nerves,  and  it  gives  branches  to 
the  pectoralis  minor,  some  of  which  pass  through  the  latter  muscle  and  end  in  the 
great  pectoral.  The  nerve  then  unites  with  a  branch  from  the  external  anterior 
tlioracic,  and  forms  a  loop  which  is  placed  in  front  of  the  first  stage  of  the  axillary 
artery.  From  this  loop  additional  branches  are  furnished  to  the  greater  pectoral 
muscle. 

(3)  The  subscapular  nerves  are  branches  of  the  posterior  cord.  They  are 
three  in  number,  are  distinguished  as  upper,  middle,  and  lower,  and  are  distributed 
to  the  subscapularis,  latissimus  dorsi,  and  teres  major  muscles. 

(a)  The  upper  or  short  subscapular  nerve  is  derived  from  the  fifth  and  sixth 
cervical  nerves.  It  is  distributed  exclusively  to  the  subscapularis  muscle.  It  is 
occasionally  double. 

(h)  The  middle  or  long  subscapular  nerve  contains  fibres  of  the  seventli 
cervical  nerve;  it  accompanies  the  subscapular  artery  along  the  axillary  margin  of 
the  subscapularis  muscle  and  ends  in  the  latissimus  clorsi. 

(c)  The  lower  subscapular  nerve,  carrying  fibres  of  the  fifth  and  sixth  cervi- 
cal nerves,  ]iasses  behind  the  subscapular  artery,  beloAV  the  dorsalis  scapulae  branch, 
and  is  distril)uted  to  the  teres  major;  furnishing  one  or  two  twigs  to  the  subscapu- 
laris, Avliich  enter  the  subscapularis  near  the  axillary  margin  of  that  muscle. 

TERMINAL  OR  LONG  BRANCHES. — These  are  given  off  as  follows:  from  the 
outer  cord,  the  musculo-cutaneous  and  the  outer  head  of  the  median;  from  the 
inner  cord,  the  inner  head  of  the  median,  the  ulnar,  the  internal  cutaneous,  and 
the  lesser  internal  cutaneous;  from  the  posterior  cord,  the  muscido-sj)iral  and  the 
circumflex  nerves.     The  circumflex,  lesser  internal  cutaneous,  internal  cutaneous, 


BRANCHES  OF  BRACHIAL    PLEXUSES 


'SU 


and  luuisc'ulu-cutaiicous  arc  iiioiv  proxiiual  in  tlifir  distribution  than  the  median, 
ulnar,  and  nmsculo-spiral,  and  may  therefore  be  first  described. 

(1)  The  circumflex  nerve  is  a  brancli  of  the  posterior  cord,  and  is  composed  of 
fibres  derived  from  the  lifth  and  sixth  cervical  nerves.  It  accompanies  the  i)osterior 
circumflex  artery  through  tlie  (piadrilateral  space  bounded  by  the  teres  major,  long 
head  of  triceps,  and  subscai)ularis  muscles,  and  by  the  surgical  neck  of  the  humerus, 
and  it  divides  into  a  smaller  ])osteri()r  and  a  larger  anterior  division.  Previous  to 
its  division  it  furnishes  an  articular  twig  to  the  shoulder  joint.  This  twig  ])ierces  the 
inferior  i)art  of  the  ca])sular  ligament. 

(a)  Th{>  anterior  division  accompanies  the  ])osterior  circumflex  artery  around 
the  neck  of  the  humerus,  and  gives  off  a  number  of  stout  twigs  which  enter  the 


Fig.  456.— Distribution  of  Cutaneous  Xervks  on  the  Anterior  and  PosTERiort  Aspects 

OF  the  Superior  Extremity. 


INTERNAL 
CUTASEOirs  OF 
.Vl'SCULO- 
SPIKA  /, 


INTERNAL 
CUTANEOUS 


PA  LMA  R 

rUTANEOUa  OF 

MEDIAN 
PALMAR 

CUTANEOUS  OF 

ULNAR 


SUPRA- 

ACROMIAL 


CIRCUMFLEX 


CIRCUM- 
FLEX 


CUTANEOVS 

EXTERXAL 
CI'TANEOUS  OF 

MUSCCLO- 

SPIRAL 


MUSCULO- 
CUTANEOUS 


EXTERNAL 

CUTANEOUS 

OF 

MUSCULO- 

SPIRAL 


RADIAL 


PALMAR 
CfrTANEOUS 
OF  RADIAL 


SUPRA- 

A  CROMIA  L 


IXTERSAL 
CITASKOrS  O 

MUSCrLU- 

SPIRAL 
ISTERCOSTO- 

HUMERAL 


NER VE  OF 
WRISBERC 


INTERNAL 
CUTANEOUS 


ULNAR 


deltoid  muscle.  A  few  fine  filaments  pierce  the  deltoid  and  end  in  the  integiunent 
which  covers  the  middle  third  of  that  muscle. 

(fe)  The  posterior  division  divides  into  cutaneous  and  muscular  branches. 
The  cutaneous  branch  sup})lies  the  skin  covering  the  lower  third  of  the  deltoid  and 
a  small  area  of  integument  below  the  insertion  of  that  muscle.  One  muscular 
branch  is  distributed  to  the  teres  minor;  it  swells  out  into  an  ovoid  or  fusiform 
reddish  gangliform  enlargement  before  entering  the  muscle,  others  sui)]ily  the 
lower  and  {posterior  ))art  of  the  deltoid. 

(2)  The  lesser  internal  cutaneous  nerve,  or  nerve  of  Wrisberg,  arises  from 
the  inner  cord  of  the  lirachial  i)lexus.  and  is  formed  of  fibres  derived  from  the 
eighth  cervical  and  first  thoracic  nerves  or  from  the  first  thoracic  nerve  alone.  It 
runs  downwards  on  the  inner  side  of  the  axillary  vein,  being  separated   bv  that 


790  THE  yEJlVOUS  SYSTEM 

vessel  from  the  ulnar  m-rve.  It  passes  ilou  invards  with  a  slight  inclination  hack- 
wards  under  cover  of  tiie  deej)  fascia  on  the  inner  side  of  the  arm.  At  the  middle 
of  the  arm  it  i)ierces  the  fascia,  and  near  the  hend  of  the  elbow  it  turns  soniewhiit 
sharj)ly  backwards  to  supply  the  intejzunicnt  ■which  covers  the  olecranon  process. 
As  it  traverses  the  axilla  the  nerve  of  ^\'risl>erg  communicates  with  the  intercosto- 
humeral  nerve  forming  one  or  sometimes  t^vo  loops.  In  its  course  down  tlie  arm  it 
gives  a  few  fine  twigs  to  the  integument. 

(3)  The  internal  cutaneous  is  a  l)rancli  of  the  inner  cord,  its  fibres  being  ulti- 
mately derived  from  the  eighth  cervical  and  first  thoracic  nerves.  At  its  origin  it 
lies  on  the  inner  side  of  the  axillary  artery,  but  it  soon  passes  forwards  and  lies  in 
the  groove  between  the  artery  and  the  vein  anteriorly.  In  the  upper  two-tliirds  of 
the  arm  it  lies  in  front  and  to  the  inner  side  of  the  brachial  artery. 

It  then  pierces  the  deep  fascia  in  company  with  the  V)asilic  vein,  and  divides 
into  an  anterior  and  a  posterior  braneli.  Previous  to  its  division  it  gives  off  a  twig 
which  [)ierces  the  deep  fascia,  and  su])])lies  tlie  integument  of  the  upi)er  and  inner 
part  of  the  arm.  (a)  The  anterior  branch  is  larger  than  the  posterior,  and 
divides  at  acute  angles  into  several  twigs,  some  of  Avhich  pass  in  front  of  and  some 
liehind  the  median  basilic  vein,  and  then  run  down  the  forearm  to  supply  the 
integuments  covering  its  anterior  and  internal  aspect  as  far  as  the  wrist,  anasto- 
mosing with  the  branches  of  the  ulnar  nerve,  (b)  The  posterior  branch  passes 
downwards  and  backwards  in  front  of  the  internal  condyle  of  the  humerus,  and 
divides  into  branches  which  su})ply  tlie  skin  on  the  postero-internal  aspect  of  the 
forearm.  It  anastomoses  with  the  inferior  external  cutaneous  branch  of  the  in\is- 
culo-spiral  nerve  and  the  dorsal  brancli  of  tlie  ulnar  nerve. 

(4)  The  musculo-cutaneous  nerve  is  a  branch  of  the  outer  cord  of  the 
brachial  plexus.  It  is  composed  of  fibres  which  are  derived  from  the  fifth,  sixth, 
and  seventh  cervical  nerves.  It  is  i)laced  at  first  close  to  the  outer  side  of  the 
]>rachial  artery,  but  soon  leaves  that  vessel  and  pierces  the  coraco-brachialis  muscle 
in  a  direction  olilif][uely  downwai'ds  and  outwards.  Continuing  this  oblique  direc- 
tion, it  passes  between  the  ])iceps  and  Ijrachialis  anticus  muscles,  and  becomes  super- 
ficial at  the  outer  l^order  of  the  former  muscle,  a  little  above  the  bend  of  the  elljow. 
It  then  passes  on  the  deep  surface  of  the  median  cej)halic  vein,  and  divides  into  an 
anterior  and  a  posterior  branch.  Previous  to  its  division,  the  musculo-cutaneous 
nerve  supplies  three  muscles,  viz.  the  coracQ-hrachialis,  the  biceps,  and  the  bradtlalh 
anticus.  It  also  supplies  twigs  to  the  humerus,  the  nutrient  artery,  and  the  elbow- 
joint.  The  nerve  to  the  coraco-brachialis  consists  of  two  or  three  twigs  which 
are  given  off  from  the  nerve  close  to  its  origin,  and  before  it  has  traversed  the 
muscle.  In  the  child  this  branch  rises  separately  from  the  seventh  cen'ical  nerve. 
The  nerves  to  the  biceps  and  brachialis  anticus  muscles  arise  from  the 
musculo-cutaneous  nerve  as  it  is  ])assing  between  these  muscles.  There  is  a  sep- 
arate branch  for  each  head  of  the  biceps.  The  posterior  terminal  branch  is 
small,  and  is  directed  downwards  and  liackwards  in  front  of  the  external  condyle 
of  the  humerus  to  be  distributed  to  the  skin  on  the  outer  and  posterior  aspect  of 
the  forearm  as  low  as  the  wrist.  It  anastomoses  wdth  the  radial  nerve  and  Avith 
the  inferior  external  cutaneous  branch  of  the  nnisculo-spiral  nen'c.  The  anterior 
branch  runs  cloAvnwards  on  the  outer  and  anterior  part  of  the  forearm,  supplying 
tbe  integument  of  that  region,  and  having  communicated  near  the  wrist  with  the 
radial  nerve,  it  sends  a  branch  through  the  deep  fascia  Avhich  accom])anies  the 
radial  artery  to  the  back  of  the  wrist;  it  terminates  in  the  skin  covering  the  middle 
part  of  tin?  thenar  eminence. 

(•"))  The  median  nerve  is  formed  by  filn-es  derived  from  the  fifth,  sixth, 
seventh,  and  eighth  cervical  and  first  thoracic  nerves.  It  arises  by  two  heads, 
one  from  the  outer,  and  one  from  the  inner  cord.  The  inner  head  crosses  ol)li(]uely 
in  front  of  tho  third  stage  of  the  axillary  artery,  and  joins  the  outer  head  on  the 
external  side  of  that  vessel.  The  median  nerv(^  runs  almost  vertically  down  the 
arm  under  cover  (^f  the  skin  and  fascia,  and  is  partially  overlapped  by  the  biceps. 
In  the  upper  part  of  the  arm  it  is  placed  on  the  outer  side  of  the  brachial  artery. 
About  the  middle  of  the  arm  it  crosses  in  front  of  that  vessel,  and  then  runs  down 
on  the  iimer  side  of  the  artery  to  the  bend  of  the  elbo\v.  It  then  passes  between 
the  two  heads  of  the  ])i-on;itor  radii  teres,  and  is  separated  from  the  ulnar  artery  in 


BRA.XCHES  OF  BRACHIAL   1' LEXISES 


Till 


this  situation  by  the  deep  head  of  the  iiiusele.  It  continues  vertically  di)\vn\vards 
in  the  middle  line  of  the  forearm  between  the  flexor  sublimis  and  flexor  profundus 
digitorum;  in  this  part  of  its  course  it  is  accompanied  by  a  compani(jn  artery,  the 
comes  nervi  mediani.  At  the  upper  border  of  the  annular  ligament  it  is  ]ilaccd 
between  the  tendons  of  the  iiexor  carpi  radialis  externally  and  the  i)almaris  longus 
and  flexor  sublimis  digitorum  muscle  internally.  It  passes  under  cover  of  the 
anterior  annular  ligament,  on  the  superficial  surface  of  the  Hexor  tendons,  and,  at 
the  lower  border  of  the  ligament,  it  enlarges,  and  l)ifurcates  into  two  terminal  divi- 
sions, an  iimer  larger,  and  an  outer  smaller. 

Branches. — The  median  nerve  does  not  supply  any  jtart  of  the  U])i)er  arm.    In 
front  of  the  ell)ow-joint  it  furnishes  one  or  two  filaments  to  tlu^  articuliition.      In 


Fig.  457. — A  Dissection  siiowix(j  the  Akraxoemext  of  thjc  Xekves  ix  kroxt 

(JK  THE  Elbow. 

(From  a  mounted  specimen  in  the  Anatomical  Department  of  Trinity  Colle<;e    Dul)lin.) 


POSTERIOR  BRANCH 

OF  IXTKRXAL 

CVTAXEOUS  SERVE 
A  XTERIOR    BRA  NCH 

OF  IXTFRXAL 

rCTAXEOVS  NERVE 

Brachial  artery 


BRANCH  TO 
PRONATOR  TERES 

Bicipital  fascia,  cut  abort 


Pronator  radii  teres 
muscle 


MEDIAN  NERVE 

Ulnar  arlerv 


Biceps  muscle 


.    BRANCH  OF  MUSCUHt- 

SPIRAL  XERVE  TO 
sr FIXATOR  LONGUS 

—    RADIAL  NERVE 

Radial  recurrent  artery 
n,„l  POSTERIOR 
—       I XTFR  OSSEOUS 
XFi;  VE 

Tendon  of  biceps 

MTSfUL  O-CUTA  XEO  US 
XER  VE 

Supinator  longus  muscle 


Railial  artery 


the  forearm  it  supplies  all  the  superficial  anterior  muscles  (with  the  exception  of 
the  flexor  carpi  ulnaris)  directly  from  its  trunk,  and  supplies  the  deep  muscles 
(with  the  exception  of  the  inner  half  of  the  flexor  profundus)  by  its  anterior  inter- 
osseous branch.  In  the  hand  it  sup])lies  the  group  of  short  muscles  of  the  thumb 
(with  the  exception  of  those  whicli  are  ])laced  on  the  ulnar  side  of  the  tendon  of 
the  flexor  longus  pollicis),  the  two  outer  lumbricales,  the  integument  covering  the 
central  part  of  the  palm  and  inner  part  of  the  tln-nar  eminence,  and  th(^  palmar 
aspect  of  the  thumb,  index,  middle,  and  radial  half  of  the  ring  fingers.  It  also 
sends  tAvigs  to  the  dorsal  as])ect  of  these  digits. 

(a)  The  nerve  to  the  pronator  radii  teres  arises  a  little  above  the  bcnil  of 
the  elbow,  and  pierces  the  outer  border  of  that  muscle. 


702 


THE  XER VOL'S  SYSTEM 


(h)  The  nerves  to  the  flexor  carpi  radialis,  palmaris  longus,  and  flexor 
sublimis  digitorum  ari^e  a  little  linver  down,  and  pierce  the  pronator-tlexor  mass 
of  niuselef^,  tn  end  in  the  respective  members  of  the  group  for  whieh  thev  are 
destined. 

(c)  The  anterior  interosseous  nerve  arises  from  the  median  at  the  level  of  the 
bicipital  tubercle  of  the  ra-dius    and  run  downwards  on  the  interosseous  membrane 


Fig.  457a. — Dissection'  of  the  Left  Arm  from  the  Front,  Showixg  Portioxs  of  the 
Ulnar,  Median,  Musculo-cutaxeous,  and  Musculo-spiral  Nerves. 


Subscapularis 


Teres  major 

Long  head  of  triceps 
Latissimus  dorsi 

MUscuLO-CL'TA XEO  f '>  \nn  I 

MEDIA  X  XER  V 


UJ.XAR  XERVE 


Internal  head  of  triceps 


Pronator  radii  teres 
Flexor  carpi  radialis 


Pronator  radii  teres 
deep  head) 


Flexor  sublimis  digitorum 


Coraoo-braohialis 
Biceps 

Peotoralis  major 


Brachialis  antlcus 


Biceps 


.1/  ( -^'iCUL  0-SPIRA  L 
XER  VE 


RADIAL  XERVE 
POSTERIOR  IXTER- 

OSSEOUS  XERVE 

Extensor  carpi  radialis 

longior 


AXTERIOR  IXTER- 
OSSEOLS  XERVE 


accompanied  by  the  anterior  interosseous  artery.  It  passes  under  cover  of  the 
pronator  quadratus,  and  pierces  the  deep  surface  of  that  muscle.  The  anterior 
interosseous  nerve  also  furnishes  a  twig  to  tlie  front  of  the  Avrist-joint  and  supplies 
the  flexor  profundus  digitorum"  and  the  flexor  longus  pollicis.  The  nerve  to  the 
former  muscle  arises  from  the  anterior  interosseous  near  its  commencement  and 
supplies  the  outer  two  divisions  of  the  muscle,  and  communicates  wdthin  its  sub- 
stance with  twigs  derived  from  the  ulnar  nerve. 


MhDIAX  A.XD   ULNAR   yKRVES 


r93 


It  also  supplies  a  ln'anch  to  the  iiitcrosse(jus  ni(.'iul)raiie  which  runs  dowinvurds 
upon,  or  in,  the  membrane  sui)plyinff  it  and  giving  branches  to  the  anterior  inter- 
osseous and  medullary  arteries  and  to  the  periosteum  of  the  radius  and  ulna. 

(d)  The  palmar  cutaneous  branch  arises  immediately  above  the  anterior 
annular  ligament  and  ])asscs  Ijetween  the  tendons  of  the  flexor  carpi  radialis  and 
the  palmaris  longus.  It  then  crosses  the  superficial  surface  of  the  annular  liga- 
ment, is  distributed  to  the  integument  and  fascia  on  the  central  depressed  surface 
of  the  palm,  and  su))])li('s  a  few  twigs  to  the  inmn*  border  of  the  thenar  eminence; 
these  twigs  communicate  with  the  museulo-cutaneous  and  radial  nerves. 

(e)  The  external  terminal  division  gives  oft"  a  branch  which  supplies  the 
abductor,  the  opjtonens,  and  the  superficial  head  of  the  flexor  brevis  pollicis 
muscles,  then  it  divides  into  two  liranches.  The  outer  branch  passes  obliquely 
across  the  long  flexor  tendon  of  tiie  thumb,  and  runs  along  the  radial  border  of  the 


Fig,  45d. — t5UPEBFici.\L  Nerves  of  the  P.vlm.     (,Ellis.) 


BRASCII  TO  MU.SCLES 
OF  THUMB 


COLLATERAL 
BRASCIIES  OF 
MEDIA  y 


I  I  \  \R  yERlE 


'  o^r^fuyIr AT/OX 

BI  rWEES  MED  I  AX 
1  \D  ULXAl: 


COLLATERAL 
jif  /  BRANCHES  or 

"-  I'LXAR 


tlmmb  as  far  as  its  extremity.  It  gives  numerous  branches  to  the  pulj)  of  the 
thumb,  and  a  strong  twig  which  passes  on  to  the  dorsum  to  su])ply  the  matrix  of 
the  nail.  The  inner  branch,  after  running  a  course  varying  from  an  eighth  to  a 
half  an  inch,  divides  into  two  digital  collateral  branches.  The  outer  collateral 
branch  supplies  the  ulnar  side  of  the  volar  asi)ect  of  the  thuml),  and  gives  oft'  a 
twig  to  the  matrix  of  the  thumb  nail.  The  inner  collateral  branch  is  distributed 
in  a  similar  manner  to  the  radial  side  of  the  index  finger.  It  gives  oft'  a  twig  to 
supply  the  first  lumbrical  muscle. 

(./")  The  internal  terminal  division  divides  into  an  outer  and  an  inner  l)ranch. 
The  outer  branch  gives  a  twig  to  supply  the  second  lumbrical  muscle,  and  divides 
a  little  above  the  metacarpo-phalangeal  articulation  into  collateral  ])ranches.  which 
supply  the  adjacent  sides  of  the  index  and  middle  fingers,  and  also  give  twigs  to 
the  dorsum  of  each  of  these  digits.     These  dorsal  twigs  will  be  more  particularly 


794  THE  yERVOUS  SYSTEM 

described  later  on  (page  797).     Tlie  inner  branch  communicates  with  the  ulnar 
nerve  and  divides  to  supply  the  adjacent  sides  of  the  middle  and  ring  lingers. 

As  the  branches  of  the  median  nerve  pass  downwards  in  tlie  palm  of  the  hand,  they  cross  the 
deej)  or  posterior  suifaee  of  the  supertieial  palmar  arch.  Tliis  ivlation  to  the  art  dies  is  reversed 
in  the  fingers,  where  the  digital  arteries  are  i)laccd  behind  the  nerves.  As  each  digital  nerve 
pursues  its  cour.se  along  the  margin  of  the  corresponding  finger,  it  gives  off"  twigs  to  the  dorsum 
of  the  finger,  which  supply  the  skin  on  the  dorsum  of  the  second  and  third  phalanges,  particu- 
larly stout  twigs  passing  to  sui)i)ly  the  matrix  of  the  nail.  Each  nerve  terminates  in  branches  to 
the  pulp  of  the  finger,  and  on  these  terminal  branches  as  well  as  on  the  more  j^roximal  twigs  to 
the  volar  aspect  of  the  fingers,  ovoid  bodies,  about  the  size  of  millet  seeds,  are  developed.  These 
bodies  are  called  Pacinian  corpuscles,  and  are  one  of  the  forms  of  sensory  nerve-terminations. 

(6)  The  ulnar  nerve  is  the  largest  branch  of  the  inner  cord  of  the  brachial 
plexus,  and  is  derived  from  the  eighth  cervical  aiul  lirst  thoracic  nerves.  It  runs 
downwards  between  the  axillary  artery  and  the  vein,  posteriorly,  and  preserves  the 
same  relation  to  the  brachial  artery  for  the  upper  third  of  the  arm.  It  then 
diverges  from  the  brachial  artery  at  an  acute  angle,  and  accompanies  the  inferior 
profunda  artery  through  the  internal  muscular  septum  and  downwards  upon  the 
inner  head  of  the  triceps  to  the  interval  between  the  internal  condyle  of  the  humerus 
and  the  olecranon  processes  of  the  ulna.  In  this  course  it  is  jjlaced  under  cover  of 
the  deep  fascia.  It  then  passes  between  the  two  heads  of  the  flexor  carpi  ulnaris, 
comes  into  relation  with  the  posterior  ulnar  recurrent  artery,  and  runs  downwards 
under  cover  of  the  flexor  carpi  ulnaris  muscle,  1;)etween  it  and  the  flexor  profundus 
digitorum,  to  reach  the  wrist.  At  the  junction  of  the  upper  and  middle  thirds  of 
the  forearm  it  is  joined,  at  an  acute  angle,  l\v  the  ulnar  artery,  and  runs  jiarallel  to 
the  inner  side  of  that  vessel  in  the  middle  and  lower  two-thirds  of  the  forearm 
under  cover  of  the  flexor  carpi  ulnaris,  and  between  that  muscle  and  the  flexor 
sublimis  digitorum.  Just  above  the  wrist  it  pierces  the  deep  fascia,  enters  the 
hand  by  crossing  the  superficial  surface  of  the  anterior  annular  ligament  close  to  the 
radial  border  of  the  pisiform  bone,  and  terminates  1)V  bifurcating  into  a  superficial 
and  a  deep  division. 

Branches. — The  ulnar  reseml)les  the  median  nerve  in  not  furnishing  any 
branches  to  the  upper  arm.  As  it  passes  lietween  the  olecranon  process  and  the 
internal  condyle,  it  gives  off  two  or  three  fine  filaments  to  the  elbow-joint.  In  the 
forearm  it  supplies  the  flexor  carpi  ulnaris  and  the  inner  portion  of  the  flexor 
profundus  digitorum,  and  gives  off  the  three  cutaneous  branches.  In  the  hand  it 
supplies  the  integument  of  the  hypothenar  eminence,  the  little  finger  and  half  of 
the  ring  finger  and  part  of  the  dorsum;  it  also  gives  twigs  to  the  palm  and  supplies 
the  short  intrinsic  muscles  of  the  hand  with  the  exception  of  the  abductor,  tlie 
opponens,  the  outer  head  of  the  flexor  brevis  pollicis,  and  the  two  outer  lumbri- 
cales. 

(ft)  The  nerves  to  the  flexor  carpi  ulnaris  and  to  tlie  inner  two  divisions  of 
the  flexor  profundus  digitorum  arise  from  the  ulnar  in  the  upper  third  of  the 
forearm. 

(6)  The  Palmar  Cutaneous  Branch, — About  the  middle  of  the  forearm  it  gives 
off  two  cutaneous  Ijranches;  one  pierces  the  fascia  and  anastomoses  with  the  anterior 
branch  of  the  internal  cutaneous  nerve,  and  the  other,  the  palmar  cutaneous  branch, 
runs  downwards  in  front  of  the  ulnar  artery,  and  is  conducted  liy  the  vessel  intct 
the  palm.  It  furnishes  some  filaments  to  the  vessel,  and  ends  in  the  integument 
covering  the  central  depressed  surface  of  the  })alm  and  supjtlies  a  few  twigs  to  the 
skin  of  the  hypothenar  eminence. 

(c)  The  dorsal  or  posterior  cutaneous  branch  arises  al)out  two  inches 
above  the  Avrist-joint,  and  passes  backwards  under  covi'r  of  tlie  lh>xor  carpi  ulnaris 
to  reach  the  dorsal  aspect  of  the  wrist.  It  crosses  superficial  to  the  tendon  of  the 
extensor  carpi  ulnaris  innnediately  below  the  lower  end  of  the  idna,  and,  after 
giving  off  twigs  to  supply  the  skin  of  the  dorsum  of  the  hand,  divides  into  three 
l)ranches,  namely:  a  branch  to  the  inner  l)order  of  the  little  finger;  a  branch  which 
divides  to  supply  the  contiguous  borders  of  the  ring  and  little  fingers,  and  a  branch 
which  communicates  with  the  radial  and  participates  in  the  supi)ly  of  the  adjacent 
borders  of  the  ring  an<l  middle  fingers. 

(d)  The  superficial  terminal  branch  of  the  ulnar  nerve  gives  off  a  branch  to 


MUSCULO-SPIBAL  NERVE  795 

sujiply  the  palniaris  l)rrvi,s  muscle,  several  twigs,  whieh  an*  distrilmted  to  the  skin 
covering  the  hypotlienar  eminence,  and  then  it  divides  into  two  branches,  an  inner 
and  an  outer.  The  inner  branch  is  distributed  to  the  inner  side  of  the  little  linger 
<tn  its  volar  aspect.  The  outer  branch  comnmnicates  with  the  median  nerve,  and 
then  divides  to  supply  the  contiguous  margins  of  the  ring  and  little  lingers.  The 
distriI)ution  of  these  branches  to  the  lingers  ri'sembles  that  of  the  digital  branches 
of  the  median  nerve,  which  has  been  already  described. 

(f )  The  deep  branch  of  the  ulnar  nerve  accompanies  the  deep  branch  of  the 
ulnar  artery  int(j  the  interval  between  the  abductor  and  flexor  lirevis  minimi  digiti 
muscles,  and  then  passes  through  the  libres  of  the  o})ponens  minimi  digiti  to  reach 
the  deep  surface  of  th(?  flexor  tendons.  It  supplies  the  abductor,  flexor  l)revis, 
and  op})onens  minimi  digiti,  the  two  inner  lumbrieales,  all  the  interossei,  the 
adductors,  and  the  inner  head  of  the  flexor  brevis  pollicis.  Occasionally  it  also 
gives  a  twig  to  the  outer  head  of  the  flexor  brevis  ])ollicis. 

(7)  The  musculo-spiral  nerve  is  the  largest  branch  of  the  brachial  plexus. 
It  arises  from  the  posterior  cord,  and  contains  fibres  derived  from  the  fifth,  sixth. 
seventh,  and  eighth  cervical  nerv'es.  It  is  i)laced  at  first  behind  the  third  stage  of 
the  axillary  artery;  low'er  down  it  has  a  similar  relation  to  the  upper  part  of  tlie 
brachial  artery.  It  soon  leaves  the  latter  vessel  and  accompanies  the  superior  pro- 
funda artery  into  the  inter\'al  betw^een  the  inner  and  outer  heads  of  the  tricejis. 
Having  followed  the  si)iral  groove  around  the  humerus,  it  pierces  the  external 
inter-muscular  septum  and  runs  downwards  in  the  interval  between  the  supinator 
longus  (brachio-radialis)  and  the  brachialis  anticus  muscles.  A  little  above  the 
bend  of  the  elbow  it  terminates  by  dividing  into  the  radial  and  the  posterior  inter- 
oss(M)us  nerves. 

Branches. — The  musculo-spiral  nerve  gives  oflf  three  cutaneous  branches,  one 
internal  and  two  external,  and  supplies  the  following  muscles:  triceps,  anconeus, 
brachialis  anticus  in  part,  supinator  longus,  and  extensor  carpi  radialis  longior. 

(a)  The  internal  cutaneous  branch  *irises  within  the  axilla,  usually  in 
common  with  tlie  branch  to  the  long  head  of  the  triceps.  It  crosses  the  tendon  of 
the  latissimus  dorsi  muscle  and  passes  l)ehind  the  intercosto-humeral  nerve  to 
the  back  of  the  arm,  supplying  a  strip  of  integument  in  the  middle  of  the  dorsal 
surface  extending  nearly  dow^n  to  the  elboAV,  and  placed  betw^een  the  areas  of 
distribution  of  the  circumflex  and  intercosto-humeral  nerves. 

(h)  The  external  cutaneous  branches  are  distinguished  as  U])per  and  lower. 
The  upper  branch,  much  the  smaller,  i)ierces  the  deep  fascia  in  the  line  of  the 
external  intermuscular  septum;  it  accompanies  the  lower  part  of  the  cei)halic  vein 
and  su]>plies  the  skin  over  the  lower  half  of  the  outer  and  anterior  asjjcct  of  the 
arm.  The  lower  branch  is  of  consideral>le  size.  It  pierces  the  deep  fascia  a  little 
below  the  upi)er  branch,  runs  behind  the  external  condyle,  and  supj)lies  the  skin  of 
the  middle  of  the  back  of  the  forearm  as  far  as  the  wrist,  anastomosing  with  tlie 
internal  cutaneous  and  musculo-cutaneous  nerves. 

(<■)  Muscular  Branches. — ^Muscular  branches  are  given  off  in  the  axilla  to 
the  long  and  internal  heads  of  the  tricejos;  one  of  the  latter  is  a  long  filament  which 
accompanies  the  ulnar  nerve  and  is  known  as  the  ulnar  collateral.  At  tlie  l)ack  of 
the  humerus  muscular  branches  are  given  to  the  outer  and  imier  heads  of  the  tri- 
ceps and  to  the  anconeus;  the  latter  descends  in  the  substance  of  the  inner  head  of 
the  triceps  accompanied  by  a  branch  of  the  superior  ])rofimda  artery.  At  the  outi-r 
side  of  the  humerus  branches  are  supplied  to  the  supinator  longus,  the  extensor 
carpi  radialis  longior.  and  to  a  section  of  the  brachialis  anticus;  from  one  of  these 
an  articular  twig  is  given  off  to  the  elliow-joint. 

(^d)  The  posterior  interosseous  nerve  passes  downwards  in  thi'  interval 
between  the  brachialis  anticus  and  the  extensor  carpi  radialis  longior,  and.  having 
given  oft'  branches  to  sup))ly  the  extensor  carpi  radialis  brevior  and  sui)inator 
brevis,  it  is  crossed  by  the  radial  recurrent  artery;  then  it  runs  downwards  and 
backwards  through  the  substance  of  the  sui)inator  brevis,  and  enters  the  cellular 
interval  between  the  suiierficial  and  deep  layers  of  muscles  at  the  back  of  the  fore- 
arm; here  it  comes  into  relation  with  the  ])osterior  interosseous  artery,  which  it 
accompanies  across  the  extensor  ossis  metacar]>i  jiollicis.  At  the  lower  border  of 
the  latter  muscle  it  gives  off  a  branch  to  the  extensor  secundii  interno<lii  ]>ollicis, 


r96 


thp:  xervous  system 


and  another  which  crosses  the  secundii  intemodii  pollicis  to  reach  tlie  extensor 
indieis:  then,  leaving  the  posterior  interosseous  arterk',  it  dips  beneath  the  extensor 
secundii  iutem<xiii  poUicis  and  conies  mto  relation  with  the  anterior  interosseous 
artery,  which  it  accompanies  upon  the  interosseous  membrane  and  the  back  of  the 
radius,  passing  through  the  groove  for  the  extensor  communis  digitonim  and  the 
extensor  indicis,  to  the  back  of  the  wrist,  where  it  terminates  in  a  ganglifonn  en- 
largement, from  which  branches  are  given  to  the  carpal  articulations.  The  muscles 
supplied  by  the  posterior  interosseous  nerve  are  the  extensor  carpi  radialis  bre\'ior, 

Fig.  459. — A  Dissection  of  the  CuTAXEors  Xebves  ox  the  Doe.^.\l  Aspect  of  the 
Haxd  axd  Fixgees.      H.  St.  J.  B.) 

The  brauches  of  the  median  nerve  are  shown  in  black. 


DOnsAL  BRAXCB 
OF  CLXAIt 


BRASCB  OF 
MEDIA  y 
.VERVE 


BRASCH  OF  yirSClLO-^^PIRAL 


RADIAL  SERVE 


the  supinator  brevis.  the  extensor  communis  digitorum,  extensor  minimi  digiti. 
extensor  carpi  ulnaris.  the  three  extensor  muscles  of  the  thumb,  and  the  exten.- 
indicis.     The  supinator  brevis  receives  too  twigs,  one  of  which  is  given  off  befcn 
the  nerve  pierces  the  muscle,  and  the  other  while  it  is  traversing  the  muscular 
substance. 

(J  )  The  radial  nerve  is  somewhat  smaller  than  the  posterior  interosseous,  an<l 
is  a  purely  cutaneous  nerve.  It  runs  downwards  under  cover  of  the  supinator 
longus.  crossing  the  radial  recurrent  artery  and  the  supinator  brevis:  it  approaches 
the  radial  artery  at  an  acute  angle,  and  runs  parallel  to  the  outer  side  of  that  vessel 


THE  RADIAL   NERVE  797 

in  the  middlf  tliird  of  the  forearm,  erossing  the  pronator  radii  teres.  It  then  i)arts 
company  Avith  the  artery  by  bending  Ijaekwards  on  the  deep  surface  of  the  tendon 
of  the  sui)inator  longus.  It  pierces  the  deep  fascia  in  the  lower  third  of  the  fore- 
arm and  is  directed  towards  the  back  of  the  wrist,  where  it  divides  into  its  terminal 
^tranches.  One  of  these,  the  })almar  cutaneous  of  the  radial  nerve,  sup])lies  the 
outer  part  of  the  thenar  eminence;  two  others  supply  the  dorsum  of  the  thumb,  a 
fourth  branch  runs  along  the  radial  side  of  the  index  finger,  a  fifth  divides  to 
supi)ly  the  adjacent  side  of  the  index  and  middh?  fingers,  and  a  sixth  branch  com- 
municates with  the  dorsal  branch  of  the  ulnar  nerve  to  sup])ly  the  adjacent  side  of 
the  middle  and  ring  fingers. 

Nerve-supply  of  the  dorsal  integument  to  the  hand. — It  will  be  seen,  by  the  foregoing 
description  of  tiie  radial  and  ulnar  ncirves,  that  the  tliuiub,  index,  and  half  the  middle  finger  are 
supplied  by  the  nulial ;  the  little  and  half  the  ring  finger  by  the  ulnar ;  and  the  adjacent  sides 
of  the  ring  and  middle  fingers  by  both  radial  and  ulnar  nerves.  The  distance  to  which  these 
nerves  extend  on  the  digits  is  somewliat  variable,  but  the  following  is  the  average  condition: — The 
radial  nerve  extends  to  the  base  of  the  thumb  nail,  to  the  distal  interphalangeal  joint  of  the  index, 
and  not  (juite  to  the  proximal  interphalangeal  joint  of  the  middle  finger,  and  sends  a  fine  twig 
in  some  ca.ses  to  the  skin  covering  the  metaphalangeal  articulation  of  the  ring  finger.  The  ulnar 
nerve  extends  to  the  nail  of  the  little  finger,  to  the  distal  interphalangeal  joint  of  the  ring,  and 
in  some  eases  to  the  integument  covering  the  proximal  interphalangeal  joint  of  the  middle,  and 
the  metacarpo-phalangeal  articulation  of  the  index  finger.  The  distal  paits  of  the  dorsum  of  the 
fingei-s  are  supplied  by  twigs  fr(jm  the  palmar  collateral  branches  of  the  median  and  ulnar  nerves, 
almost  tlu^  whole  of  the  middle  finger  being  supi)lied  in  this  way,  and  the  other  digits  to  a  less 
degree.  The  matrix  of  the  thumb  nail  is  supplied  by  twigs  from  the  jjalmar  branches  of  the  median. 
A  considerable  part  of  the  dorsum  of  the  hand  is  usually  supi)lied  by  twigs  from  both  the  radial 
and  the  ulnar  nerves,  as  these  nerves  overlap  one  another  in  their  distribution  (fig.  459). 
Occasionally  two  other  nerves,  the  musculo-cutaneous  and  the  l(jwer  external  cutaneous  branch 
of  the  museulo-spiral,  take  part  in  the  supply  of  the  back  of  the  hand. 


Table    Showing    Relation  of  Cervical   and    Dorsal  Nerves  to  Branches  or 

Brachial   Plexus 

Nerve  Roots.  Kerves. 

-  Q  J  Nerve  to  rhomboids 

'■  ,,      subclavius 

f  Suprascapular 
I  Nerve  to  subclavius 

5  and  6  C Upper  subscapular 

Lower  , , 

Circumflex 
(  Posterior  thoracic 

5,  6.  and  7  C \  External  anterior  thoracic 

^  Musculo-cutaneous 

5,  6,  7,  and  8  C Musculo-spiral 

6,  7,  8C.,  and  1  D Median 

7  and  8  C Middle  subscapular 

r  Internal  anterior  thoracic 

8  C.  and  ID J  Ulnar 

i  Internal  cutaneous 

ID Lesser  internal  cutaneous 


798 


THE   XKRVOUS  SYSTEM 


Table  Showing  the  Relations  of  the   Misoles  of  the  Upper  Extremity  to 

THE  Cervical  Nerves 


Xekve  Roots. 
nth  cranial,  2  C. 

3,  4C. 
3  and  4  C.      .    .    . 


and  6  C. 


6C. 


Muscles. 
Sterno-mastoid 
Trapezius 

Levator  angidi  scapuhe 
r  Subclavius 
I  Supraspinatus 
Infraspinatus 
I  Subscapularis 
\  Teres  major 
Teres  minor 
Deltoid 

Brachialis  anticus 
.  Biceps 

r  Supinator  longus 
I  Supinator  brevis 
Pronator  radii  teres 
Flexor  carpi  radialis 
[  Palmaris  longus 
(  Ext.  carpi  radialis  longior 
,,  ,,  brevior 

()  and  "  C  '  -Abductor  poUicis 

^  Opponens      ,, 
Flexor  brevis  pollicis 

(superf.  head) 
Serratus  magnus 
r  Coraco-brachialis 
Ext.  comm.  digitorum 
,,     minimi  digiti 
,,     carpi  ulnaris 
,,     oss.  metac.  pollii-is 
,,     primi  inter.        ., 
, ,     sec.^  ^      , ,  . , 

, ,     indicis 
Latissimus  dorsi 
Triceps 
Anconeus 
Pectoralis  major 
f  Dorsal  inteross. 
Palmar       ,, 
^  J  Obliq.  add.  pollicis 

^^' I  Trans.     ,, 

Flex.  brev.        ,, 
I  (deep) 

Pectoralis  minor 
Flex.  subl.  digit, 
umbricals 
f  Flex,  carpi  ulnaris 
J       ,,     prof,  digit.  _ 
I       ,,     long,  pollicis 
[  Pronator  quadratus 


5,  6,  and  7  C. 


7C. 


7  and  8  C.      .    . 
5,  6,  7,  and  8  C. 


7,  8  C. ,  and  1  D. 


8  C.  and  1  D. 


r  Pc 

Fl 

^  Li 


Nekves. 
spinal  accessor}' 

3  and  4  C. 
3  and  4  V. 
Xcrve  to  su))clavius 

I  Suprascapular 

Upper  and  lower  sul)scapular 
Lower  sul>scapular 

[  Circumflex 

\  IMusculo-cutaneous 

Musculo-spiral 
Posterior  interosseous 
Median 


Musculo-spiral 
Posterior  interosseous 
Median 


Posterior  thoracic 
Musculo-cutaneous 
Posterior  interosseous 


Long  subscapular 
Musculo-spiral 

Ext.  and  int.  ant.  thoracic 
Ulnar 


Int.  ant.  thoracic 
^Median 

and  ulnar 
Ulnar 

,,        and  median 
IVIedian 


mo  RACK'  XENVKS  TUD 


THORACIC  NERVES 

The  sinuller  part  of  the  first  thoracic  nerve  and  tlir  second  to  tlic  elcventli 
thoracic  nerves  follow  the  contour  nf  tlic  hody  wall  in  the  intervals  l)etween  the 
rihs,  and  are  therefore  termed  intercostal  nerves.  The  twelfth  thoracic  nerve 
j)ursues  a  parallel  course  to  the  others,  below  the  twelfth  ril).  Each  of  the  inter- 
costal nerves  is  accompanied  by  an  intercostal  artery  and  vein.  These  vessels  are 
l)laced,  inniiediately  above  the  nerve,  in  the  groove  at  the  lower  border  of  the  rib. 
The  twelfth  thoracic  nerve  is  accompanied  by  the  first  hinibar  artery.  Each 
thoracic  nerve  is  joined,  near  the  head  of  the  rib,  by  two  rami  communicantes 
from  the  gangliated  cord  of  the  sympathetic.  The  first  and  last  thoracic  nerves 
reijuire  separate  di'scrii)tion.  The  remaining  ten  nerves  fall  naturally  into  an  u[>]Kr 
and  a  lower  group.  The  members  of  the  upper  group  (the  second  to  the  sixth ) 
run  between  the  ribs  as  far  as  the  margin  of  the  sternum.  The  mem1)ers  of  the 
lower  group  (  seventh  to  eleventh  ner\'es)  lie  for  a  i)art  of  their  course  l)etween  the 
layers  of  the  al)dominal  wall,  the  extent  of  the  abdominal  distribution  increasing 
from  the  liighest  to  the  lowest  member  of  the  series. 

A.  First  thoracic  nerve. — The  greater  part  of  the  first  thoracic  nerve  crosses 
the  neck  of  the  first  rib  to  join  the  brachial  plexus,  as  already  descril)ed.  The 
smaller  part,  about  one-fifth  of  the  entire  nerve,  runs  for  about  two  inches  in 
contact  with  the  under  surface  of  the  first  rib  between  the  bone  and  the  pleura,  and 
tiien  enters  the  cellular  interval  between  the  external  and  internal  intel-costal 
muscles.  For  the  remainder  of  its  course  it  corresponds  to  the  upper  intercostal 
nerves  in  its  distribution,  but  it  does  not  usually  give  a  lateral  or  an  anterioi- 
cutaneous  branch. 

Variety. — In  some  cases  a  lateral  cutaneous  nerve  arises  from  the  first  intercostal  nerve.  It 
...ay  be  of"  small  size,  but  is  sometimes  as  large  as  an  ordinary  intereostu-liunieral  nerve.  It 
LMjmmuiiieates  with  the  intercostohumeral  nerve  and  with  the  nerve  of  Wri.sberg. 

B.  Upper  intercostal  nerves. — The  second,  third,  fourth,  fifth,  and  sixth  inter- 
costal nerves,  after  receiving  connnunications  from  the  sympathetic,  are  directed 
outwards  in  the  intercostal  spaces  in  front  of  the  posterior  intercostal  membrane, 
between  that  membrane  and  the  jdeura.  They  then  enter  the  interval  between  the 
external  and  internal  intercostal  muscles,  and  follow  the  curve  of  the  thoracic  wall 
l)etween  these  muscles  as  far  as  the  mid-axillary  line,  and  then,  taking  a  dee])er 
position,  they  run  through  the  fibres  of  the  internal  intercostals  as  far  as  the  junction 
of  the  bony  parts  of  th(!  ribs  with  their  cartilages.  Hence  they  pass  forwards  on  the 
deej)  surface  of  the  internal  intercostal  muscles,  lying  on  the  pleura  and  on  the  slips 
of  the  triangularis  sterni,  and  cross  in  front  of  the  internal  mammary  vessels. 
Lastly,  they  bend  forwards  and  pierce  the  internal  intercostals,  the  anterior  inter- 
costal membranes  and  the  pectoralis  major,  and  terminate  as  the  anterior  cutaneous 
nerves  of  the  thorax.  In  this  course  they  give  off  nuiscular  branches  to  the 
l(>vatores  costarum,  serratus  posticus  superior,  external  and  internal  intercostals, 
and  triangularis  sterni.  Il^ach  nerve  also  gives  off  two  cutaneous  branches — 
namely,  the  lateral  and  ant(n"ior  cutaneous  nerves  of  the  thorax. 

The  lateral  cutaneous  nerves  of  the  thorax  ])ierce  the  external  intercostal 
nmscles,  and  divide  into  anterior  and  j)o.steriitr  branches.  These  l)ranches  pa.ss 
l)etween  the  digitations  of  the  serratus  magnus,  and  are  separated  by  an  interval  of 
about  half  an  inch  when  they  appear  on  the  superficial  surface  of  that  muscle. 
The  anterior  branches  run  forwards,  cross  the  lower  border  of  the  great  pectoral, 
and  supi)ly  the  integuments  which  cover  the  lower  and  outer  jtortion  of  that  muscle, 
and  give  twigs  to  the  mannnary  gland.  They  increase  jirogressively  in  size  from 
above  downwards.  In  the  case  of  the  second  lateral  (nitaneons  nerve,  the  anterior 
Itranch  is  usually  wanting.  The  posterior  branches  turn  backwards,  and  su]>ply 
the  skin  covering  the  outer  ])art  of  the  latissinuis  dorsi  and  the  infericn-  angle  of 
the  scapula.  The  lateral  cutaneous  l)ranches  of  the  second  and  third  intercostal 
nerves  are  larger  than  the  others,  and  reijuire  separate  notice.     The  lateral  cuta- 


m 


SCO 


THE   yERVOVS  SYSTEM 


FiC     460  — Cl-TANEOUS   NKRVE.S   OF   TIIK   THORAX    AND   AhDOMKX,   VIKWKD    FROM   UIK 
■         ■  SiDK.      (After  Heule.) 


SUPRA  CLA  VICVLA  R 
BRANCH  OF 
CERVICAL  PLEX 


INTJ:ii('OSTiK 
JllMERAL 


—  LatiBsimue  dorsi 


Pect  oralis  minor 


SerratuB  maKnua 


Sheath  of  rectus 


ANTERIOR 

CUTANEOUS  OF 
LAST  THORACIC 


ILIO- 
HYPOGASTRIC 


ILIO-ING  UINA  I. 


External  oblique 


-RAL  CVTANEOVS 
LAST  THORACIS 
'iVE 


INTERCOSTAL   XERVES— THORACIC  XERVE  SOI 

noous  branch  of  the  second  intercostal  nerve  is  called  the  intercosto-humeral 
nerve.  It  passes  outwards  across  the  axillary  space,  crosses  the  tendon  of  the 
latissimus  dorsi  and  the  internal  cutaneous  branch  of  the  musculo-spiral  nen-e  to 
reach  the  ami.  It  is  distril;»uted  to  the  integument  of  the  inner  and  posterior  part 
of  the  ann  in  its  U{)per  two-thirds.  Within  the  axilla  it  connnunicates  with  the 
lesser  internal  cutaneous  ner%'e  of  the  brachial  plexus,  and  with  the  lateral  cutane- 
ous bnuicli  of  the  third  intercostal.  The  lateral  cutaneous  branch  of  the  third 
intercostal  divides  intt»  a  small  anterior  and  a  larLa-  ]t<'>ttri(>r  brancli.  The  ante- 
rior branch  ends  near  the  margin  of  the  great  {>ectoral  muscle.  The  posterior 
branch  communicates  with  the  intercosto-humeral  nerve,  and  then  turns  round  the 
posterior  fold  of  the  axilla,  and,  after  giving  a  twig  to  the  integument  of  the  arm, 
ends  in  the  skin  ctivering  the  dorsum  of  the  scapula. 

The  anterior  cutaneous  nerves  of  the  thorax  are  the  terminal  branches  of 
the  upper  intercostal  nen'es.  Thev  i>ierce  the  pect oralis  major  in  company  with 
the  perforating  branches  of  the  internal  mammary  artery.  On  reaching  the  surface 
of  the  muscle,  they  give  off  minute  twigs,  Avhich  supply  the  skin  over  the  steniiim, 
and  then  end  in  slender  branches  which  are  directed  outwards  to  supply  the  skin 
covering  the  greater  part  of  the  pectoralis  major.  Some  twigs  from  the  third, 
fourth,  tifth,  and  sixth  ner\-es  are  distributed  to  tlie  mammary  gland. 

C.  Lower  intercostal  nerves. — The  seventh,  eighth,  ninth,  tenth,  and 
eleventh  intercostal  nerves,  in  the  part  of  their  course  which  lies  between  the  ribs, 
present  the  same  relations  as  the  upper  intercostal  nerves.  Leaving  the  intercos- 
tal spaces  they  pass  behind,  or  in  the  last  two  spaces  between  the  costal  cartilages, 
and  then  forwards  between  the  internal  oblique  and  transversalis  muscles,,  where 
they  anastomose  together,  in  a  plexiform  manner.  Piercing  the  posterior  lamella 
of  the  internal  oblicjue  aponeurosis,  they  enter  the  sheath  of  the  rectus  abdominis; 
they  supjdy  the  rectus  muscle,  pass  through  it,  pierce  the  anterior  part  of  its  sheath 
ami  tenninate  as  the  anterior  cutaneous  nerves  in  the  skin  of  the  abdomen. 

Branches. — The  lower  intercostal  ner\-es  supply  the  external  and  internal 
intercostal  muscles,  the  levatores  costarum,  the  serratus  posticus  inferior,  the  inter- 
nal oblique,  the  transversalis,  the  rectus,  and  from  one  or  more  of  them  twigs  are 
given  to  the  costal  fibres  of  the  diaphragm.  They  also  give  off  lateral  cutaneous 
branches,  by  which  the  external  oblique  is  supplied. 

The  lateral  cutaneous  nerves  of  the  abdomen  are  the  continuation  of  the 
series  of  tlie  lateral  cutaneous  nerves  of  the  tliorax.  They  divide  into  anterior  and 
posterior  branches,  which  pierce  the  external  oblii|ue.  The  anterior  branches 
are  directed  fc^rwards  and  somcAvhat  downwards,  and  supply  the  integument  e<ner- 
ing  the  anterior  abdominal  wall  as  far  as  the  outer  margin  of  the  rectus.  Each 
nerve  gives  ofl"  a  muscular  twig,  which  pierces  the  adjacent  diiritation  of  the  exter- 
nal obli(jue  muscle  on  its  superficial  surface.  The  posterior  branches  pass  back- 
wards around  the  margin  of  the  latissimus  dorsi.  and  end  in  the  skin  of  the  outer 
part  of  the  back. 

The  anterior  cutaneous  nerves  of  the  abdomen  are  the  terminal  branches 
of  the  lower  intercostal  nerves,  and  pierce  tlu-  anterior  part  of  the  sheath  of  the 
rectus  to  supply  the  skin  covering  that  muscle.  These  nerves  are  of  small  size,  and 
sometimes  divide  before  their  emergence,  so  as  to  fonu  a  double  series. 

D.  Last  thoracic  nerve. — This  nerve  gives  off  a  communicating  twig  to  the 
first  lumbar  nerve,  and  tlien  passes  lieneath  the  external  arcuate  ligament,  and  runs 
outwards  below  the  twelfth  ril)  across  the  front  of  the  quadratus  lumborum,  accom- 
panied by  the  first  lumbar  artery.  It  pierces  the  posterior  aponeurosis  of  the  trans- 
versalis, and  follows  the  curve  of  the  abdominal  wall  between  the  transversalis  and 
internal  ol)lique  muscles.  In  the  remainder  of  its  course  it  resembles  a  lower 
intercostal  nerve.  After  piercing  the  rectus,  however,  it  supplies  the  pyramidalis 
((Jriffin).  Its  lateral  cutaneous  liranch  remains  undivided,  and  represents  the 
anterior  division  of  an  ordinary  lateral  cutaneous  branch.  On  account  of  its  dis- 
tribution, it  is  named  the  iliac  branch.  The  iliac  branch  pierces  the  external 
obli(|ue  about  three  inches  above  the  iliac  crest,  and  is  ilireeted  downwards,  acro.cs 
the  crest,  a  short  distance  behind  the  anterior  superior  .spine.  It  ends  in  the 
integument  covering  the  anterior  part  of  the  gluteal  region. 
51 


802  THE  XERVOUS  SYSTEM 


LU3IBAR  NERVES 

The  anterior  divisions  of  the  five  luml^ar  nerves  increase  progressively  in  size 
from  above  downwards,  the  first  lumbar  being  about  the  size  of  an  intercostal  nerve, 
and  the  fifth  a  nerve  of  considerable  magnitude.  The  first,  second,  third,  and  part 
of  the  fourth  nerves  unite  to  form  the  lumbar  plexus.  The  remainder  of  the  fourth 
unites  with  the  fifth  to  form  the  luml)o-sacral  cord,  which  passes  to  the  sacral  plexus. 
Each  lumbar  nerve  is  connected  to  the  gangliated  cord  of  the  sympathetic  by  rami 
communieantes.  These  rami  communicantes  reach  the  lumbar  nerves  by  accom- 
panying the  lumbar  arteries  through  the  fibrous  arches  from  which  the  psoas  takes 
origin. 

LUMBAR   PLEXUS 

The  lumbar  plexus  is  placed  among  the  deeper  fibres  of  the  psoas,  and  is  con- 
stituted as  follows:  the  first  lumbar  nerve  is  joined  by  a  communicating  twig  from 
the  tAvelfth  thoracic  and  divides  into  two  branches;  one  of  these  is  the  common 
origin  of  the  ilio-hypogastric  and  ilio-inguinal  nerves;  the  other  branch  unites  with 
a  branch  of  the  second  lumbar  to  form  the  genito-crural  nerve.  The  second,  third, 
and  fourth  lumbar  nerves  divide  into  anterior  and  posterior  divisions.  A  part  of 
the  anterior  division  of  the  second  lumbar  nerve  enters  into  the  composition  of  the 
genito-crural  nerve  as  above  mentioned;  the  remainder  of  the  anterior  division  of 
the  second  nerve  unites  with  the  anterior  division  of  the  third  and  part  of  the  fourth 
nerve  to  form  the  obturator  nerve.  The  remainder  of  the  anterior  division  of  the 
fourth  nerve  enters  the  lumbo-sacral  cord.  The  fourth  lumbar  nerve,  therefore, 
takes  part  in  the  formation  of  l^oth  the  lumbar  and  sacral  plexuses;  and  it  is  known 
as  the  "nervus  furcalis."  The  posterior  divisions  of  the  second,  third,  and  fourth 
nerves  end  chiefly  in  two  large  nerves — the  external  cutaneous  and  the  anterior 
crural.  The  external  cutaneous  arises  from  the  second  and  third  nerves.  The 
anterior  crural  springs  from  the  second,  third,  and  fourth  nerves.  A  part  of  tht- 
posterior  division  of  the  fourth  nerv^e  enters  the  lumbo-sacral  cord.  The  large  ter- 
minal ])ranches  above  described  are  given  off  within  the  substance  of  the  psoas; 
three  of  these,  the  ilio-hypogastric,  ilio-inguinal,  and  external  cutaneous,  appear  at 
the  outer  border  of  the  psoas,  l^etween  that  muscle  and  the  quadratus  lumborum: 
one,  the  genito-crural,  pierces  the  anterior  fibres  of  the  psoas  and  appears  in  front 
of  the  muscle;  another  l^ranch,  the  obturator,  appears  at  the  inner  border  of  tin- 
psoas  close  to  the  lower  margin  of  the  fifth  lumbar  vertebra;  lastly,  the  anterior 
crural  nerve,  the  largest  branch  of  the  plexus,  runs  downwards  in  the  interval 
between  the  psoas  and  iliacus.  AMthin  the  psoas  small  twigs  are  given  oft'  l\v  the 
lumbar  nerves,  which  end  in  the  nmscular  substance  of  the  psoas  and  quadratus 
lumljorum. 

Branches. — The  nerves  to  the  psoas  and  quadratus  Ivmhorum  from  the  first  and 
second  luml)ar  nerves  arise  in  the  sul)stance  of  the  psoas. 

The  ilio-hypogastric  and  ilio-inguinal  nen'es  are  in  some  cases  represented 
by  a  common  trunk  Avhich  arises  from  the  first  lumbar.  More  commonly  they 
exist  as  two  se})arate  nerves,  the  upper  and  larger  nerve  being  ilio-hypogastric:  tlu' 
lower  and  smaller,  ilio-inguinal.  Taken  together  they  correspond  in  many  respects 
to  a  lower  intercostal  nerve.  They  run  for  a  considera1)le  part  of  their  course 
between  the  transversalis  and  internal  oblique,  giving  twigs  to  both  these  muscles. 
The  ilio-hypogastric  gives  off  a  lateral  cutaneous,  which  is  called  the  iliac  branch, 
and  terminates  in  an  anterior  cutaneous  which  is  termed  the  hypogastric  branch. 

(1)  The  ilio-hypogastric  nerve  is  a  l)ranch  of  the  first  lumbar.  It  ai»})ears  at 
the  outer  l^order  of  the  psoas  and  crosses  the  quadratus  lumliorum  ol)li<iuely  \o 
reach  the  crest  of  the  ilium.  In  this  part  of  its  course  it  is  surrounded  by  the 
extra-peritoneal  fat.  It  then  pierces  the  transversalis  and  runs  along  the  crest  of 
th(^  ilium  between  that  nmscle  and  the  internal  ol)li(]ue.  and.  about  two  and  a  half 
inches  behind  the  anterior  superior  spine  of  the  ilium,  divides  into  an  iliac  and 


LUMBAR  PLEXUSES 


803 


an  hypoirastric  branch,  (a)  The  iliac  branch  j^icrees  the  internal  and  external 
obli(|Ue  muscles  and  crosses  the  crest  of  the  ilium,  lying  close  to  the  bone.  It  is 
directed  downwards  towards  the  great  tnjchanter  of  the  fenmr;  some  of  its  twigs  reach 
as  far  as  that  prominence,  and  su})ply  the  integuments  covering  the  fore  part  of  the 
gluteal  region,  (b)  The  hypogastric  branch  continues  the  direction  of  the  main 
trunk,  and  perforates  the  internal  ol)lique  near  the  anterior  superior  spine  of  the 
iHum.  In  this  part  of  its  course  it  communicates  in  a  plexiform  manner  with  the 
ilio-inguinal  nerve.     It  is  then  directed  forwards  and  inwards  under  cover  of  the 


Fig.  461. — Diagram  of  the  Lumbar  axd  Sacral  Plexuses.     (Modified  from  Pate rson.) 

FHOM  LAST  THORACIC 

FIRST  LUMBAR 

SECOSD  LUMBAR 


OEXITO-CRURAL 

ILIO-HYPOGASTRIC 

ILIO-IXGUIXAL 


EXTERXAL 
CUTAXEOUS 


OBTURA TOR 


A CCESSOR  r 
OBTURATOR 


BRAXCII  TO  ILIACUS 
AXTERIOR  CRURAL 


SUPERIOR  GLUTEAL 
IXFERIOR  GLUTEAL 


GREA  T  SCIA  TIC 

XERVE  TO 

QUADRATUS 

FEMORLS 

EXTERXAL 

POPLITEAL 

SECTIOX 

IXTERXA  L 

POPLITEAL 

SECTIOX 

TO  HAMSTRIXGS 


THIRD  LUMBAR 


FOURTH  L  UMBAR 


FIFTH  LUMBAR 


FIRST  SACRAL 


SECOXD  SACRAL 


THIRD  SACRAL 

VISCERAL 
FOURTH  SACRAL 

PERFORA  TIXG 

CUTAXEOUS 
PERIX^EAL 
FIFTH  SACRAL 

KERVE  TO  COffYGErs 

XER  VE  TO  LEVA  TOR 
A  XI 

FIRST  COCCYGEAL 


VISCERAL 


SMALL  SCIATIC 
XERVE  TO  OBTURATOR  IXTERXUS 


PUDIC 


aponeur()sis  of  the  external  ol)li(jue.  Finally  it  pierces  the  aponeurosis  outside  the 
sheatJi  of  the  rectus  at  a  point  a1)out  an  inch  above  the  external  abdominal  ring, 
and  .supi)lies  the  skin  in  that  situation,  forming  a  continuation  of  the  series  of 
anterior  cutaneous  nerves  of  tlie  abdomen. 

(2)  The  ilio-inguinal  nerve  arises  from  the  first  luml)ar  nerve  in  common 
Avith  the  ilio-hypogastric.  and  acc(jmpanies  the  last-named  nerve  acro.ss  the  quad- 
ratus  lumborum,  but  at  a  Liwer  level.  It  then  passes  ol)liriuolv  across  the  upj.er 
part  cf  the  ihacus  and  pierces  the  transversalis  muscle.  It  f<.ll..ws  the  curve  of  the 
crest  of  the  ilium  in  company  with  the  ilio-hypoga.stric.  connnunicatin-  witli  tliat 


804 


THE  NERVOUS  SYSTEM 


nerve  in  a  plexiform  manner.  It  pierces  the  internal  oblique  a  little  in  front  of  the 
anterior  superit)r  spine  of  the  ilium,  and  runs  forwards  under  cover  of  the  aponeu- 
rosis of  the  external  oblique  innnediately  above  Poui)art's  ligament,  enters  the 
lower  part  of  the  inguinal  canal  and  reaches  the  external  abdominal  ring.  It  then 
traverses  the  ring  and  divides  into  its  terminal  brandies,  whicli  are  distributed  to 
the  skin  covering  the  upper  part  of  the  adductor  longus.  the  integuments  of  the 
scrotum  in  the  male,  and  of  the  labium  majus  in  the  female. 

(3)  The  genito-crural  nerve  arises  from  the  first  and  second  lumbar  nerve  by 
two  roots  which  pass  forwards  and  downwards  through  the  fibres  of  the  psoas,  and 
unite  to  form  a  single  trunk.     The  nerve  then  appears  on  the  surface  of  the  psoas 


Fig.  462. — Branches  of  the  Lumbar  and  Sacral  Plexus  viewed  from  before. 
(After  Hirschfeld  and  Leveille. ) 
GAXGLIATED  CORD  OF  SYMPATHETIC  AORTIC  PLEXUS 

LAST  THORACIC  NERVE  JfT^^TV  /  ,  LAST  THORACIC  NERVE 

FIRST L 


ILIO- 
HYPOGASTRIC 
TLIO-INGUIXAL 

SECOND 
LUMBAR 


FOURTH 

LUMBAR 

ILIO-INGUINAL 

EXTERNAL 

CUTANEOUS 

GEXITO-CRVRAL 

LCMBO- SACRAL 

CORD 

ANTERIOR  CRURAL 

OBTURATOR 


ILIO-INGUINAL 

DISTRIBU-   I 

TION  OF 
EXTERNAL  \ 
CUTANEOUS 

CRURAL 
BRANCH 
OF  GENITO- 
CRURAL 


ILIO-HYPO. 
GASTRIC 

ILIO- 
INGUINAL 

THIRD 
LUMBAR 
NERVE 

GENITO- 
CRURAL 


EXTERNA  L 
CUTANEOUS 

GENITAL 
BRANCH 
OF 
GENITO- 

CRURAL 

CRURAL 
BRANCH  OF 
GENITO- 
CRURAL 

OBTU- 
RATOR 


SACRAL 
PLEXUS 


close  to  the  vertebral  column,  at  the  level  of  the  third  lumbar  vertebra  and  runs 
downwards  under  cover  of  the  peritoneum.  After  lieing  crossed  by  the  ureter  it 
readies  the  outer  side  of  the  external  iliac  artery,  where  it  divides  into  a  genital 
and  a  crural  branch. 

(a)  The  genital  branch  accompanies  the  s]->ermatic  vessels  through  the  inguinal 
canal,  and,  emerging  from  the  external  al)dominal  ring,  pierces  the  internal  sper- 
matic fascia,  and  is  distributed  to  the  cremaster  muscle.  In  the  female  this  branch 
is  rudimentary  and  accompanies  the  round  ligament. 

(6)  The  crural  branch  is  carried  downwards  in  front  of  the  external  iliac  and 
femoral  artery  into  tlie  external  compartment  of  the  femoral  sheath.  It  pierces  the 
femoral  sheath  and  becomes  subcutaneous  about  two  inches  below  Poupart's  liga- 


OBTURATOR  AND   EXTERNAL  CUTANEOUS  NERVES  805 

ment  by  piercing  the  fascia  lata.      It  is  distributed  to  the  skin  covering  the  upjter 
and  central  j)art  of  the  anterior  aspect  of  the  thigh. 

(4)  The  obturator  nerve  arises  from  tiie  third  and  fourth  lumbar  nerves,  and  in 
the  majority  of  cases  receives  an  additional  root  from  tlie  second.  It  passes  between 
the  i^soas  muscle  and  the  body  of  the  tifth  lumbar  vertebra.  It  then  runs  downwards 
and  forwards  outside  the  internal  iliac  vessels  and  the  ureter,  and  below  the  external 
iliac  vessels  to  reach  the  upper  margin  of  the  thyroid  foramen.  In  this  part  of  its 
course  it  runs  parallel  to  and  a  little  ]:)elow  the  brim  of  the  pelvis,  and  is  i)laced  in 
the  extra-peritoneal  fat  l)etween  the  peritoneum  and  the  parietal  pelvic  fascia.  It 
is  accom})anied  1)V  the  obturator  vessels  which  are  placed  below  it.  The  nerve  then 
]»asses  through  tlie  deficiency  in  the  obturator  membrane,  and  divides  into  tw(j 
branches,  an  anterior  and  a  posterior. 

(a)  The  anterior  branch  passes  across  the  upper  border  of  the  obturator 
externus,  and  is  directed  downwards  and  inwards  l)etween  the  pectineus  and 
adductor  brevis,  and  divides  into  the  following  branches: — (i)  A  twig  for  the  hip- 
joint;  (ii)  a  branch  for  the  adductor  longus;  (iii)  a  branch  to  supply  the  adductor 
l)revis;  (iv)  a  branch  for  the  gracilis;  (v)  in  rare  cases,  a  twig  for  the  pectineus ; 
(vi)  a  cutaneous  branch;  and  (vii)  a  Ijranch  to  the  femoral  artery.  The  cutaneous 
branch  becomes  superficial  by  passing  between  the  adductor  longus  and  adductor 
brevis,  and  is  then  directed  along  the  posterior  border  of  the  sartorius,  where  it 
communicates  with  twigs  from  the  long  saphenous  and  from  the  posterior  Ijranch 
of  the  internal  cutaneous  to  form  the  subsartorial  plexus. 

(h)  The  posterior  branch  gives  off  branches  to  supply  the  hip-joint  and  the 
ol)turator  externus,  and  then  pierces  the  upper  part  of  that  muscle  and  reaches  the 
interval  between  the  adductor  brevis  and  adductor  magnus.  It  runs  downwards 
on  the  anterior  surface  of  the  latter  muscle,  supplying  it  with  tAvigs,  and  terminates 
in  an  articular  twig,  the  geniculate  branch,  Avhich  is  distributed  to  the  knee-joint. 
(i)  The  twig  to  the  hip-joint  enters  the  acetabulum  by  passing  through  the  coty- 
loid notch.  It  ramifies  in  the  fat  occupying  the  floor  of  the  acetabulum  and  in  the 
adjacent  synovial  memln'ane.  (ii)  The  branch  to  the  ol)turator  externus  pierces 
the  deep  surface  of  the  muscle,  (iii)  Several  large  twigs  enter  the  adductor  mag- 
nus. (iv)  The  geniculate  branch  pierces  the  lower  part  of  the  adductor  magnus 
and  appears  on  the  posterior  surface  of  that  muscle  close  to  the  opening  for  the 
l)opliteal  vessels,  and  descends  on  the  inner  side  of  (sometimes  behind)  the  pop- 
liteal artery.  Having  given  off  a  filament  which  accompanies  the  superior  internal 
articular  artery,  it  breaks  up  into  terminal  twigs  which  separateh'  pierce  the  pos- 
terior ligament  of  the  knee-joint. 

An  accessory  obturator  nerve  is  occasionally  present.  It  arises  between  the  anterior  cruial 
and  obturator  nerves  from  the  third  and  fourth  lumbar  nerves.  It  runs  along  the  imier 
border  of  the  psoits,  and  cros.ses  in  front  of  the  brim  of  the  pelvis  to  gain  the  deep  surface  of  the 
pectineus.  In  this  situation  it  breaks  up  into  branches.  The  largest  ofthe.se  branches  joins  the 
obturator  nerve,  others  enter  the  capsule  of  the  hip-joint,  and  a  branch  is  furnished  to  the  pec- 
tineus. 

The  branch  which  joins  the  obturator  nerve  may  carry  filaments  for  the  adduc- 
tors longus  and  brevis,  and  the  gracilis. 

(5)  The  external  cutaneous  nerve  arises,  by  two  roots,  from  the  second  and 
third  lumbar  nerves.  It  riuerges  at  the  outer  l)order  of  the  psoas,  and  crosses 
ol)li(|uely  in  front  of  the  iliacus  to  reach  the  interval  between  the  anterior  superior 
and  anterior  inferior  spines  of  the  ilium.  In  this  course  it  runs  under  cover  of  the 
fascia  iliaca.  It  then  passes  behind  Poupart's  ligament,  crosses  in  front  of  the 
origin  of  the  sartorius,  and  divides  into  an  anterior  and  a  posterior  branch.  The 
posterior  branch  passes  backwards  and  downwards  under  cover  of  the  fascia  lata, 
and  divides  into  twigs  which  supply  the  integument  covering  the  insertion  of  the 
gluteus  maximus  and  the  upper  and  outer  part  of  the  thigh.  The  anterior  branch 
is  much  larger  than  the  posterior.  It  runs  downwards  for  several  inches  in  a  canal 
formed  by  the  fascia  lata,  and  enters  the  superficial  fascia  at  the  junction  of  the 
upper  with  the  middle  third  of  tlie  thigh.  It  divides  into  branches  which  supply 
the  skin  of  the  outer  part  of  the  thigh,  a  few  of  the  terminal  twigs  reaching  as  far 
as  the  knee  and  entering  into  the  composition  of  the  plexus  patellae. 


806 


THE  XERVOUS  SYSTEM 


(6)  The  anterior  crural  nerve  is  the  largest  branch  of  the  luinhar  iilexiis.  It 
arises  by  three  roots,  Avhicli  spring  from  the  second,  third,  and  fourth  lunil)ar 
nerves;  these  roots  traverse  the  substance  of  the  psoas  and  unite  into  a  single  trunk 
in  the  deep  groove  between  the  psoas  and  iliacus  muscles.  The  nerve  then  passes 
under  cover  of  the  fascia  iliaca,  behind  Poupart's  ligament,  into  Scarpa's  triangle, 
where  it  lies  external  to  the  femoral  sheath  and  divides  into  two  groups  of  terminal 
branches — the  superticial  and  deep. 

In  the  abdominal  part  of  its  course  the  anterior  crural  nerve  gives  branches  to 
the  iliacus,  and  a  twig  to  the  femoral  artery. 


Fig.  463.— Axtekior  Crural  axd  Obturator  Nerves.     (Ellis.) 

Femora'  vein  Femoral  nrtery 


Peetineus 
OBTURATOR  {ANTERIOR  DIV.) 

OBTURATOR  (POSTERIOR 
1)1  VISION) 

/  ■ 
Adductor  longus  — k 


Adductor  brevis 


OBTURA TOR 

(ANTERIOR 

DIVISION) 


Adductor  magnus 

GENICVLA  TF 
BRANCH  01 
OBTURATOR 

Semi-membranosus 


Sartoriua 

Iliacus 

ANTERIOR  CRURAL 


Tensor  vaginae  femoris 


Profunda  artery 

Peetineus 
Eeetus  femoris 


LONG  SAPHENOUS 


XERVE  TO  VASTUS 
INTERNUS 


Adductor  longus 


Femoral  artery 


Anaslomotica  artery 


PATELLAR  BRANCH  OF 
LONG  SAPHENOUS 


The  superficial  terminal  branches  are  muscular  and  cutaneous;  they  are  sc})- 
arated  from  the  dee])  branches  by  the  external  circumflex  artery. 

The  muscular  branches  of  the  superticial  series  contain  fibres  from  the  second 
and  third  lumljar  nerves;  they  are  tAvo  in  number — one  to  the  peetineus,  Avhich 
passes  behind  the  femoral  sheath  to  the  anterior  surface  of  the  peetineus  muscle, 
and  one  to  the  sartorius.  The  latter  usually  accompanies  one  of  the  two  divisions 
of  the  middle  cutaneous  ner^-e. 

The  cutaneous  branches  of  the  superficial  series  are  the  internal  and  middle 


IXTERXAL   AXD   MIDDLE  CUTANEOUS  XERVES 


807 


cutaneous  nerves.     They  also  contain  filjres  from  the  second  and  third  luniliar 
nerves. 

The  internal  cutaneous  nerve  is  directed  downwards  along  the  outer  side  of 
the  femoral  artery,  giving  off  in  this  situation  two  or  three  cutaneous  twigs,  which 
pierce  the  fascia  lata.  It  then  crosses  obliquely  in  front  of  the  femoral  artery,  at 
the  lower  angle  of  Scarpa's  triangle,  and  divides  into  an  anterior  and  a  posterior 
branch.  Tlie  anterior  branch  is  the  larger.  It  runs  downwards,  in  front  of  the 
sartorius.  under  cover  of  the  fascia  lata.  It  pierces  the  fascia  lata  about  the 
middle  of  tlie  lower  third  of  the  thigh,  and,  after  giving  twigs  to  the  skin  of  that 
refson,  turns  outwards  to  end  in  the  plexus  patella?.  The  posterior  branch  runs 
along  the  posterior  border  of  the  sartorius,   and,   after  giving  twigs  to  the  sub- 


flg.  464.— dlsteibutiox   of  cftaxeous   nerves  os  the  posterior  and 
Aspects  of  the  Ixfeeior  Extremity. 


LAST 
THORACIC 
ILIO-HYPO- 
GASTRIC 


EXTERNAL 
CLTAyEOUS 


EXTERNA  L 
(  VTASEOVS 


COMMCXI- 

(AXS 
FIB  CLARIS 


SHORT 
SAPHEXOCS 


POSTERIOR 

nn.iSiHES 

OF  LUMBAR 
.\ER  r£S 

POSTERIOR 
BRANCHES 
OF  SACRAL 
XERTES 

PER FOR A TISO 
CVTASEOVSOF 
SECOSD  ASH 
THIRD  SACRAL 

LOSG 
PVDESDAL 

B RANCHES  OF 
SMALL 
SCI  A  TIC 

OBTURATOR 


ILIO- 
IXGUIXAL 


TWIG 
FROM  IX- 
TERXAL 
CUTA- 
XEOl'S 


POSTERIOR 
BRANCH  OF 
INTERNA  L 

CCTANEOrS 

COMMUNI- 
CANS 
TIBIALIS 


IXTERXAL 
CUTA- 
XEOUS 


PA  TELLAR 
BRAXCH 
OF  LOXG 
SAPHE- 

xors 

LOXG 
SAPHE- 
NOUS 


TWIGS  FROM 
LOXG 
SAPHEXOUS 


IXTERXA  L 
CALCAXEAX 


AXTERIOR 
TIBIAL 


Anterior 


EXTERXAL 
CUTA- 
XEOUS 


GEXITO- 
CRURAL 


MIDDLE 
CU  TA- 
XED US 


CUTA- 

XKOUS 
BRAXCH  OF 
EXTERXAL 
POPLITEAL 


MUSCULO- 
CUTA- 
XEOUS 

SHORT 

SA  PHE- 

XOUS 


sartorial  plexus,  runs  downwards  to  the  inner  aspect  of  the  knee,  where  it  pierces 
the  deep  fascia  and  ends  in  the  integument  of  the  upper  and  inner  part  of  the 
calf. 

The  middle  cutaneous  nerve  usually  takes  the  form  of  two  strong  branches, 
which  run  a  nearly  parallel  course.  One  of  these  branches  usually  pierces  the 
sartorius,  while  the  other  crosses  the  superficial  surface  of  that  muscle;  they  pierce 
the  fascia  lata  a  little  above  the  middle  of  the  thigh.  They  ramify  in  the  super- 
ficial fascia,  supplving  the  skin  of  the  anterior  part  of  the  thigh  as  far  as  the  knee, 
where  they  end  in  the  plexus  patellre. 

The  deep  branches  are  six  in  number — one  cutaneous  (the  long  saphenous) 
and  five  muscular.  They  are  arranged  in  the  following  order,  from  within  out- 
wards: the  long  saphenous  nerve,  the  nerve  to  the  vastus  internus,  the  nerve  to  the 


808  THE  SERVO  US  SYSTEM 

subcrureus,  the  nerve  to  tlie  crureus,  the  nerve  to  the  vastus  externus,  and  the 
nen-e  to  the  rectus  femoris.  They  all  contain  fibres  from  the  third  and  fourth 
lumbar  nerves. 

(g)  The  long  or  internal  saphenous  nerve  accompanies  the  nerve  to  thi- 
vastus  internus  in  its  course  through  Scarpa's  triangle,  being  placed  between  the 
latter  nerve  and  the  femoral  artery.  It  passes  througli  Hunter's  canal  with 
the  femoral  artery,  lying  first  to  the  outer  side,  then  in  front,  and  finally  to  the 
inner  side  of  that  vessel.  At  the  lower  end  of  the  canal  it  joins  the  superficial 
l)ranch  of  the  anastomotic  artery  which  it  accompanies,  ])etween  the  posterior  border 
of  the  sartorius  muscle  and  the  anterior  border  of  the  gracilis  tendon,  to  the  imier 
side  of  the  knee  where  it  becomes  superficial.  At  this  point  it  approaches  the  long 
saphenous  vein,  and  accompanies  that  vessel  for  the  remainder  of  its  course.  It 
runs  down  the  anterior  and  inner  part  of  the  leg,  supplying  l;)ranches  to  the  skin  of 
that  region,  passes  in  front  of  the  inner  malleolus,  and  suiJi^lies  the  integument  for 
a))out  two  inches  below  tliat  prominence. 

As  it  leaves  Hunter's  canal,  the  long  saphenous  nerve  gives  ofif  a  patellar 
branch.  This  branch  pierces  the  sartorius,  and  runs,  at  first  downwards  and  then 
outwards,  towards  the  ligamentum  patellse.  It  gives  twigs  to  the  integument 
covering  that  ligament,  and  others  which  curve  U2)wards  to  join  the  plexus 
patellne. 

Plexus  patellae. — The  skin  covering  the  patella  is  profusely  sui)plied  with  neiTes  which 
commuuicate  with  one  another,  and  are  derived  from  the  external,  middle,  and  internal  cutaneous 
and  from  the  long  saphenous. 

Subsartorial  plexus. — At  the  posterior  border  and  partlj-  under  cover  of  the  sartorius 
muscle,  on  the  roof  of  Hunter's  canal,  and  a  little  below  the  middle  of  the  thigh,  branches  of 
tlie  obturator,  long  saphenous,  and  internal  cutaneous  nerves  communicate  in  a  plexiform  manner 
and  supply  the  adjacent  skin.  The  posterior  branch  of  the  internal  cutaneous  has  an  independent 
distribution,  as  already  described.  Occasionally  the  cutaneous  branch  of  the  obturator  is  unusu- 
ally large,  and  may  supply  an  area  of  integument  covering  the  lower  part  of  the  inner  hamstring 
muscles. 

The  nerve  to  the  vastus  internus  accompanies  the  long  saphenous  nerve,  in 
Scarpa's  triangle,  lying  to  its  outer  side.  At  the  upper  end  of  Hunter's  canal  it 
passes  beneath  the  sartorius,  external  to  the  roof  of  the  canal,  and  enters  the  inner 
surface  of  the  vastus  internus.     It  sends  down  a  twig  to  the  knee-joint. 

The  nerve  to  the  subcrureus  frequently  rises  from  the  nerve  to  the  crureus. 
It  passes  between  the  vastus  internus  and  the  crureus  to  the  lower  third  of  the 
thigh,  where  it  supplies  the  subcrureus  and  sends  a  branch  to  the  knee-joint. 

The  nerve  to  the  crureus  is  represented  by  two  or  three  branches  which 
enter  the  upper  part  of  the  muscle.  One  of  them  frequently  sends  a  twig  to  the 
knee-joint. 

The  nerve  to  the  vastus  externus  j^asses  downwards  beneath  the  rectus  and 
along  the  anterior  border  of  the  vastus  externus,  accompanied  by  the  descending 
l)ranch  of  the  external  circumflex  artery.  It  also  sends  a  Ijrancli  to  tlie  knee- 
joint. 

The  nerve  to  the  rectus  femoris  enters  the  deep  surface  of  that  nuiscle,  having 
previously  given  off  a  twig  to  the  hip-joint  which  accompanies  the  ascending  branch 
of  the  external  circumflex  art*^rv. 


ISACRAL   yERVE— SACRAL   PLEXUS  809 


SACRAL  AXD  COCCYGEAL  NERVES 

The  anterior  primary  divisions  of  tlie  uj)i)er  four  .sacral  nerves  escape  from  the 
neural  canal  by  passing  through  the  anterior  sacral  foramina,  while  the  anterior 
division  of  the  fifth  passes  forwards  between  the  sacrum  and  coccyx.  The 
coccygeal  nerve  escapes  from  the  neural  canal  by  passing  through  thu  terminal 
opening.  Its  anterior  primary  division  pierces  the  sacro-sciatic  ligaments  and 
])asses  forwards.  The  sacral  nerves  decrease  progressively  in  size,  from  the  first  to 
the  fifth.  The  first  sacral  nerve  is  the  largest  nerve  in  the  body,  while  the  fifth  is 
very  small.  Each  sacral  nerve  is  connected  to  the  gangliated  cord  of  the  sym])a- 
thetic  by  a  gray  ramus  communicans.  The  anterior  divisions  of  the  first,  second, 
third,  and  part  of  the  fourth  nerves  join  the  sacral  plexus;  another  part  of  the 
fourth  has  an  independent  distribution.  The  lower  part  of  the  fourth  joins  the 
fifth  sacral  and  the  coccygeal  nerve  to  form  the  coccygeal  })lexus. 

The  branches  of  the  fourth  sacral  nerve  and  the  coccygeal  plexus  may  be 
conveniently  described  first,  as  their  distribution  is  confined  to  a  limited  area  in 
the  innnediate  neighbourhood  of  the  sacral  plexus. 


FOURTH   SACRAL   NERVE 

The  fourth  sacral  nerve,  called  the  "nervus  l)igeminus, "  gives  of¥  an  ascend- 
ing branch  to  join  the  sacral  plexus,  and  a  descending  twig  to  the  coccygeal  plexus. 
In  the  interval  between  these  communicating  branches  several  ofi'sets  arise  directly 
from  the  fourth  sacral  without  entering  into  a  plexiform  arrangement.  These 
direct  offsets  are  the  i)erin8eal  branch,  and  the  muscular  nerves  to  the  coccygeus 
and  to  the  levator  ani. 

The  perinaeal  branch  of  the  fourth  sacral  pierces  the  pelvic  diaphragm, 
between  the  contiguous  margins  of  the  coccygeus  and  levator  ani,  and  appears 
close  to  the  tip  of  the  coccyx.  It  is  then  directed  forwards,  and  ends  in  twigs  to 
the  external  s]ihinctor  ani  and  to  the  integument  of  the  anus. 

The  branches  to  the  coccygeus  and  levator  ani  enter  these  muscles  on  their 
deep  or  pelvic  surfaces. 


SACRO-COCCYGEAL  PLEXUS 

The  anterior  primary  division  of  the  fifth  sacral  nerve  divides  into  ascending 
and  descending  branches.  The  ascendhig  branch  unites  with  the  descending  l)ranch 
of  the  fourth  sacral.  The  descending  branch  joins  the  coccygeal  nerve.  In  this 
manner  two  small  loops  are  formed:  these  loops  constitute  the  sacro-coccygeal 
plexus.  Anterior  and  posterior  branches  are  given  oflE  by  the  plexus.  The  anterior 
branches  join  the  hypogastric  plexus  (Testut).  The  posterior  branches  i)ierce 
the  coccygeus  muscle,  an<l  are  distributed  to  the  skin  covering  the  posterior  surface 
of  the  coccyx.  The  coccygeal  nerve  gives  a  twig  to  the  coccygeus  and  (according 
to  Testut)  gives  of^'  a  branch  which  pierces  the  great  sacro-sciatic  ligament  and 
ends  in  the  lower  fibres  of  the  gluteus  maximus.  The  plexus  is  placed  in  front  of 
the  lower  part  of  the  sacrum  and  behind  the  second  part  of  the  rectum. 


SACRAL  PLEXUS 

The  sacral  plexus,  with  the  exception  of  the  roots  of  the  lumbo-sacral  cord,  is 
situated  in  the  ])elvis,  l)ehind  the  ])arietal  pelvic  fascia.  It  lies,  for  the  most  part, 
on  the  pyriformis.  the  fi1)res  of  that  muscle  often  interlacing  with  the  roots  of  the 
plexus. 

It  is  behind  the  branches  of  the  internal  iliac  vessels,  two  of  which,  the  gluteal 
and  sciatic,  pass  through  its  loops.     On  the  left  side  it  is  also  liehind  the  first 


810  THE  XERVOrS   SYSTEM 

part  of  the  rectum,  and  on  the  right  the  lower  end  of  the  ileum  passes  in  front 
of  it. 

It  is  formed  as  follows:  a  pai't  of  the  fourth  lumhar  nerve,  "  nervus  furcalis, " 
joins  the  tifth  lumbar  nerve  to  form  the  lumbo-saeral  cord;  this  cord  is  then  joined 
b}''  the  first,  second,  and  third  sacral  nerves  to  form  a  great  flattened  band,  which  is 
directed  outwards  and  dowuAvards  towards  the  lower  margin  of  the  great  sacro- 
sciatic  foramen,  and,  on  crossing  that  margin,  is  no  longer  called  the  sacral  plexus, 
but  takes  the  name  of  the  great  sciatic  nerve.  A  part  of  the  third  sacral  nerve 
is  joined  by  branches  from  the  second  and  fourth  sacral  nerves  to  form  a  second  or 
lower  band  of  relatively  small  size,  which  ends  in  the  pudic  nerve.  Several 
branches,  to  be  presently  enumerated,  spring  from  the  plexus;  l)Ut  l)y  far  the  larger 
part  of  the  plexus  is  directly  continued  into  the  great  sciatic  and  pudic  nerves. 
The  plexus  is,  therefore,  more  condensed  and  more  simple  in  its  formation  than  any 
other  plexus  in  the  body.  The  two  constituents  of  the  lumbo-sacral  cord  unite  to 
form  that  structure  on,  or  a  little  below,  the  brim  of  the  pelvis.  The  jjlexus  has 
the  following  important  vascular  relations:  the  internal  iliac  vessels  are  placed  a 
little  in  front  of  its  upper  part;  the  gluteal  artery  passes  lietween  the  luml)o-sacral 
cord  and  the  first  sacral  nerve;  the  sciatic  artery  passes  through  the  lower  part  of 
the  plexus  (fig.  466). 

It  has  been  shown  (Paterson)  that  the  anterior  primary  divisions  of  the  lower  four  lumbar 
and  the  ujiper  two  sacral  nerves  divide  into  anterior  and  posterior  parts.  The  branches  derived 
from  the  anterior  parts  (hghtly  shaded  in  fig.  465)  always  cross  in  front  of  the  posterior  parts  and 
unite  to  form  trunks  (e.g.  obturator,  internal  popliteal),  which  are  distributed  to  what  is  mor- 
phologically the  anterior  aspect  of  the  limb.  The  trunks  which  are  formed  from  the  posterior 
parts  (e.g.  external  cutaneous,  anterior  crural,  external  ])opliteal)  are  distributed  to  the  (mor- 
phologically) posterior  aspect  of  the  limb  ;  these  nerves  are  darkly  shaded  in  fig.  465. 

The  1)ranches  of  the  sacral  plexus  are  classified  into  collateral  and  terminal. 
The  collateral  branches  are  the  superior  gluteal,  the  inferior  gluteal,  the  nerve  to 
the  pyriformis,  visceral  liranches,  the  nerve  to  the  quadratus,  the  small  sciatic,  the 
nerve  to  the  obturator  internus,  and  the  perforating  cutaneous  nerve.  The  terminal 
branches  are  the  great  sciatic  and  the  pudic  nerves. 

COLLATERAL  BRANCHES. — 1.  The  Superior  gluteal  nerve  arises  by  two 
roots,  one  from  the  lumbo-sacral  cord,  and  the  other  from  the  first  sacral  nerve. 
The  upper  root  contains  fibres  derived  from  the  fourth  and  fifth  lumbar  nerves. 
The  nerve  accompanies  the  gluteal  vessels  through  the  great  sacro-sciatic  foramen, 
passing  above  the  pyriformis.  It  then  divides  into  a  smaller  upi)er  and  a  larger 
lower  branch.  The  upper  branch  accompanies  the  upper  division  of  the  deep  part 
of  the  gluteal  artery  and  terminates  in  the  gluteus  medius;  the  lower  brancli  crosses 
the  gluteus  minimus  with  the  lower  branch  of  the  deep  part  of  the  gluteal  artery, 
sup]ilying  filaments  to  the  gluteus  medius  and  mininnis  and  a  ternnnal  branch, 
which  passes  between  their  anterior  borders,  or  through  the  fibres  of  the  minimus, 
to  the  tensor  fascia  femoris. 

2.  The  inferior  gluteal  nerve  arises  from  the  posterior  aspect  of  the  plexus,  and 
contains  fibres  derived  from  tlie  fifth  lumbar  and  the  first,  second,  and  third  sacral 
nerves.  It  escapes  through  the  great  sacro-sciatic  foramen,  below  the  pyriformis, 
and  in  this  situation  is  often  adherent  to  the  small  sciatic  nerve.  It  divides  into 
several  stout  twigs,  which  enter  the  deep  surface  of  the  gluteus  maximus. 

3.  The  nerve  to  the  pyriformis  is  given  oft'  eitlier  from  the  second  or  from 
the  third  sacral  nerve  before  they  join  the  plexus. 

4.  The  visceral  branches  arise  from  the  third  and  fourth  sacral  nerves.  They 
will  be  described  in  connection  with  the  sympatlietic. 

5.  The  nerve  to  the  quadratus  femoris  rises  from  the  front  of  the  plexus, 
obtaining  fibres  from  the  fourtli  and  fifth  lumbar  and  first  sacral  nerves.  It  passes 
through  the  great  sacro-sciatic  foramen  lielow  the  pyriformis.  and  is  usually 
adherent  for  some  distance  to  the  deep  surface  of  the  great  sciatic  in  the  part  of  its 
course  where  it  lies  between  the  latter  nerve  and  the  bone.  It  then  passes,  under 
cover  of  the  tendon  of  the  obturator  internus  and  the  gemelli,  and,  having  sup])lied 
the  gemtdlus  inferior,  ends  in  the  deep  or  anterior  surface  of  the  quadratus  femoris, 
and  in  the  posterior  part  of  the  capsule  of  the  hip-joint. 


BRANCHES  OF  THE  SACRAL   PLEXUS 


811 


6.  Till'  small  sciatic  nerve  springs  from  the  posterior  aspect  of  the  second  and 
third  saenil  nerves,  and,  passing  downwards,  escapes  through  the  great  sacro-sciatic 
foramen  by  passing  below  the  pyriformis.  It  then  rims  downwards  on  the  posterior 
surface  of  the  great  sciatic  nerve,  under  cover  of  the  gluteus  maximus  muscle,  to 
wdiich  it  furnishes  a  branch.  This  branch  is  i)rol)ably  a  portion  of  the  inferior 
gluteal  nerve,  which  has  adhered  in  a  i»art  of  its  course  to  the  small  sciatic. 
p]merging  from  beneath  the  gluteus  maximus  it  crosses  the  biceps,  accomi>anicd  l)y 
a  branch  of  the  sciatic  artery,  and  passing  down,  beneath  the  deep  fascia  it  enters 


Fig.  4G5. — Diagram  of  the  Lumbar  and  Sacral  Plexuses.     (Modified  from  Paterson.) 

FROM  LAST  THORACIC 

FIRfiT  LUMBAR 

SECOND  L  UMBA  R 


GEyiTO-CRVRAL 

ILIO-H  YPO  GA  STRI C 

ILIO-IXGIINAL 


EXTERXA  L 
CVTAXEOIS 


OBTURATOR 


A  CCESSOR  Y 
OBTURATOR 


BRANCH  TO  ILIACUS 
ANTERIOR  CRURAL 


S  UPERIOR  G  L  UTEA  L 
INFERIOR  GLUTEAL 


GREA  T  SCIA  TIC 

NERVE  TO 
QUADRATIC 


FEMORIS 


EXTERNA  L 

POPLITEA L 

SECTION 

IXTERXA  L 

POPLITEAL 

SECTION 


THIRD  LUMBAR 


FO  UR  TH  L  UMBA  R 


FIFTH  LUMBAR 


FIRST  SACRAL 


SECOND  SACRAL 


THIRD  SACRAL 

VISCERAL 
FOURTH  SACRAL 

PERFORA  TING 

CUTANEOUS 
PERIXEAL 
FIFTH  SACRAL 
KEKVE  TO  roCCYGEVS 
NER  VE  TO  LE  VA  TOR 
ANI 

FIRST  COCCYGEAL 


VISCERAL 


TO  HAMSTRINGS      /'      SMALL  SCIATIC 
NERVE  TO  OBTURATOR  INTERNES 


PUDIC 


the  popliteal  space  and  pierces  the  deep  fascia  of  the  leg  a  little  below  the  knee, 
ending  in  the  integument  of  the  upper  part  of  the  calf,  where  it  may  connnunicate 
with  the  external  saphenous  nerve.  In  its  course  down  the  thigh  it  gives  off 
numerous  branches,  which  pierce  the  fascia  lata  to  supply  the  skin  covering  the 
back  of  the  thigh  and  the  popliteal  space.  At  the  lower  border  of  the  gluteus 
maximus  it  gives  off  (a)  reflected  Immches,  and  (6)  a  large  branch  termed  the 
long  pudendal  nerve. 

\a)  The  reflected  branches,  three  or  four  in  number,  wind  round  the  lower 


812 


THE  XERVOUS  SYSTEM 


border  of  the  gluteus  maximus,  and,  having  pierced  the  deep  fascia,  supply  the 
inteo-unient  covering  the  lower  and  outer  ])art  of  that  muscle. 

(6)  The  long  pudendal  nerve,  or  nerve  of  Soemmerring,  winds  round  the 
origin  of  the  hamstring  muscles,  just  below  the  ischial  tuberosity,  giving  twigs  to 
thiTintegument  on  the  inner  and  upper  part  of  the  thigh,  and  then  curves  upwards 
and  forwards  towards  the  external  genitals.  Having  pierced  Colics' s  fascia,  it 
connnunicates  with  the  superficial  perina^il  nerves,  and  ends  in  the  integument  of 


Fig.  466.— a  Dissection  of  the  Lumbar  and  Sacral  Plexuses,  from  behind. 
(The  anterior  crural  uerve  is  placed  betweeu  the  external  cutaneous  and  obturator  nerves.) 


TWELFTH  RIB 


LA^T  THORACIC  NERVE 


ILIO- 
HYPOGASTRIC 


ILIAC  BRANCH 

OF  ILIO- 
HYPOGASTRIC 


Gluteus  medius 

Gluteal  artery 
SUPERIOR 
GLUTEAL  NERVE 


GREA  T  SCIA  TIC  NER  VE 

INFERIOR  GLUTEAL 
NER  VE 

SMALL  SCIATIC  NER  VE 


Dura  mater  of  cord 


^     POSTERIOR  PRIMARY 
DITISIOS 


'  GENI TO-CRURAL 


CAUDA  EQUINA 


Filum  terminale 


EXTERNAL 
CUTANEOUS 


OBTURATOR 
LVMBO-SACRAL  CORD 


FIRST  SACRAL 
NER  VE 


—  FIFTH  SACRAL 
NERVE 


—  VISCERAL  BRANCHES 
Sciatic  artery 
Sman  saero-seiatic 

ligament 
PUDIC  NERVE 

NERVE  TO 
OBTURATOR 
INTERNUS 


PER  FOR  A  TING 
CUTANEOUS  OF 
SECOND      AND 
THIRD  SACRAL 
NER  VES 


the  scrotum.     In  the  female  it  is  distrilnited  in  a  similar  manner  to  the  lalnum 
majus. 

7.  The  nerve  to  the  obturator  internus  arises  from  the  front  of  the 
plexus  from  tbc  fifth  luml)ar  and  the  first  :ind  second  sacral  nerves.  It  passes 
through  the  great  sacro-sciatic  foramen,  below  the  pyriformis,  and  crosses  the  base 
of  the  ischial  si)ine,  Ixnng  placed  on  the  outer  side  of  the  pudic  vessels.  Having 
furnished  a  twig  to  the  superior  gemellus,  it  enters  the  lesser  sacro-sciatic  foramen, 
and  ends  in  the  obturator  internus. 

8.  The  perforating  cutaneous  nerve  rises  from  the  second  and  third  sacral 
nerves.     It  runs  in  the  angular  interval  between  the  great  and  lesser  sacro-sciatic 


BRANCHES  OF  THE  SACRAL  PLEXUS 


813 


ligaments,  and  tht-n,  perforating'  tlie  former  ligament,  runs  between  it  and  the 
gluteus  maximus.  It  then  winds  round  the  border  of  that  muscle,  ])ehind  the 
ischio-rectal  fossa,  and  supplies  the  integument  covering  the  lower  and  inner  part 
of  the  muscle  (figs.  464  and  466). 

TERMINAL  BRANCHES. — 1.  The  pudic  nerve  arises  b}'  three  roots  from  the 
anterior  divisions  of  the  second,  third,  and  fourth  sacral  nerves,  and  escapes  from 
the  pelvis  by  passing  through  the  great  sacro-sciatic  foramen,  below  the  pyrifomiis. 
It  crosses  the  posterior  surface  of  the  sniall  sacro-sciatic  ligament,  near  the  attach- 
ment of  that  ligament  to  the  spine  of  the  ischium,  and  to  the  inner  side  of  the 
pudic  vessels.  It  then  accompanies  the  pudic  vessels  tln-ough  the  small  sacro- 
sciatic  foramen,  and  enters  a  canal  formed  by  a  delamination  of  the  parietal  pelvic 
fascia  (Alcock's  canal),  and,  having  given  off  the  inferior  ha-morrhoidal  nerve, 
terminates  by  dividing  into  the  perinaeal  ner\'e  and  the  dorsal  nerve  of  the  penis. 
At  its  origin,  the  pudic  nerve  is  often  connected  in  a  plexiform  manner  with  the 
nerve  to  the  obturator  internus. 


Fig.  467. — A  Dissection  of  the  Xerves  in  the  Gluteal  Region. 

(The  gluteus  maximus  and  gluteus  medius  have  been  divided  near  their  insertions,  and 

thrown  upwards.) 


Sciatic  artery 


INFERIOR  GLUTEAL  NERVE 


Gluteal  artery 


Gluteus  maximus 


BRANCH  TO  GLU- 
TEUS MAXIMUS 


Tendon  of  obturator  extemus 


Vastus  esternus 


Gluteus  maximus 


(a)  The  inferior  haemorrhoidal  nerve  pierces  the  wall  of  Alcock's  canal,  and 
pa.sses  inwards  through  the  fatty  tissue  which  occupies  the  ischio-rectal  fossa.  It 
is  deejjly  placed  at  the  outer  part  of  the  fossa,  but  becomes  superficial  as  it 
approaches  the  anus.  It  divides  into  terminal  twigs,  some  of  which  sup])ly  the 
external  sphincter  ani,  Avhile  others  are  distril»uted  to  the  adjacent  integument. 

(b)  The  perinseal  nerve  runs  for  a  short  distance  in  Alcock's  canal  at  a  lower 
level  than  the  ])udic  vessels,  and  then  divides  into  cutaneous  and  muscular  divisions. 
The  cutaneous  division  takes  the  form  of  two  nerv'es,  which  are  termed  }>osterior 
and  anterior  superficial  perinteal  nerves.  The  posterior  or  external  superficial 
perinaeal  nerve  escapes  from  Alcock's  canal  at  the  anterior  part  of  the  ischio-rectal 
fossa,  ] tierces  the  base  of  the  triangular  ligament,  winds  round  the  transverse 
perinseal  muscle,  and  passes  forwards  under  cover  of  Colles's  fascia.  It  then 
divides  into  several  long  slender  twigs,  which  communicate  with  the  anterior  sujjcr- 
ficial  perina\il  and  long  pudendal  nerves,  and  end  in  the  integuments  of  the  scrotum. 
In  the  female  they  are  distributed  in  a  similar  manner  to  the  labium  majus.     The 


S14  THE  NERVOUS  SYSTEM 

anterior  or  internal  superficial  perinaeal  nerve  a])pears  a  little  furtluT  forwards 
than  the  ])reeeding  nerve;  it  pierces  the  base  of  the  triangular  ligament,  and  usually 
passes  through  the  tibres  of  the  transverse  perinatal  muscle.  Its  terminal  offsets 
acconqiany  the  branches  of  the  jiosterior  perinatal  nerve,  and  have  a  similar 
distribution.  The  muscular  division  of  tlie  perinatal  nerve  is  more  deeply  placed 
than  the  cutaneous  division.  It  l^reaks  uj)  into  the  following  l)ranches:  a  twig  to 
the  bulb  of  the  urethra,  and  branches  to  supply  the  transversus  i)erin8ei,  erector 
penis  (or  clitoridis),  accelerator  urina?  (or  sphincter  vaginae),  and  compressor 
urethrffi  muscles. 

(c)  The  dorsal  nerve  of  the  penis,  wliich  is  i)laced  at  its  origin  l:)elow  the 
pudic  artery,  crosses  that  vessel  and  courses  along  above  it.  It  insinuates  itself 
between  the  layers  of  the  triangular  ligament,  and  lies  close  to  the  bone  at  the 
outer  side  of  the  pudic  vessels.  It  then  pierces  the  anterior  layer  of  the  triangular 
ligament,  and,  having  furnished  a  branch  to  the  corpus  cavernosum,  passes  between 
the  bone  and  the  crus  penis,  and  is  directed  downAvards  between  the  layers  of  the 
suspensory  ligament  on  the  dorsum  penis  external  to  the  dorsal  artery.  Having 
given  off  tAvigs  to  the  prepuce,  it  ends  in  l^ranches  to  the  glans.  As  it  runs  on 
the  dorsum  2:)enis  the  ners'e  is  under  cover  of  a  thin  strong  fascia,  and  often  appears 
in  the  form  of  two  or  three  flattened  parallel  bundles.  The  dorsal  nerve  of  the 
clitoris  is  distril)uted  in  a  similar  manner  to  the  dorsal  nerve  of  the  penis,  but  is 
of  much  smaller  size. 

2.  The  Great  Sciatic  Nerve 

The  GREAT  SCIATIC  NERVE  is  the  largest  nerve  in  the  body.  It  is,  as  above 
mentioned,  the  main  termination  of  the  sacral  plexus,  and  commences  at  the  lower 
liorder  of  the  great  sacro-sciatic  foramen.  It  is  directed  vertically  down  the  thigh, 
and  terminates  a  little  below  the  middle  of  the  thigh  by  dividing  into  the  external 
and  internal  popliteal  nerves.  In  this  course  it  is  covered  by  the  skin  and  fascia-, 
the  gluteus  maximus,  the  long  head  of  the  biceps,  and  the  small  sciatic  nerve.  Its 
deep  or  anterior  relations  are  the  following,  taken  in  order  from  above  downwards: 
the  ischium,  gemellus  superior,  tendon  of  obturator  internus,  gemellus  inferior, 
quadratus  femoris,  and  adductor  magnus. 

The  great  sciatic  nerve  consists  of  two  parts,  the  external  and  the  internal 
po^Dliteal,  Avhich  are  usually  bound  together  into  a  single  trunk  by  a  connective 
tissue  sheath;  sometimes,  however,  they  remain  separate,  a  great  sciatic  nerve,  in 
the  proper  sense  of  the  w^ord,  being  absent. 

About  the  middle  of  the  thigh  the  external  popliteal  part  supplies  a  twig  con- 
taining filaments  of  the  fifth  lumliar  and  the  first  and  second  sacral  nerves  to  tlie 
short  liead  of  the  biceps.  At  the  upper  part  of  the  thigh  the  internal  popliteal  j)or- 
tion  gives  branches  to  the  long  head  of  the  biceps,  the  semitendinosus,  the  semi- 
membranosus, and  the  adductor  magnus.  There  are  always  two  l)ranches  to  the 
semitendinosus,  one  to  each  l)elly,  and  they  contain  filaments  of  fifth  lumbar  and 
the  first  and  second  sacral  nerves.  The  branch  to  the  adductor  magnus  supjilies 
the  ischial  section  of  that  muscle  by  filaments  derived  from  the  fourth  and  fifth 
lumbar  nerves,  it  is  usually  given  o&  with  the  branch  to  the  semimembranosus 
Avhich  also  contains  fibres  of  the  first  sacral  nerve.  The  branch  to  the  long  head 
of  tlie  biceps  contains  fibres  from  the  first,  second,  and  third  sacral  nerves.  The 
EXTERNAL  POPLITEAL  NERVE,  formed  of  fibres  derived  from  the  fourth  and 
fiftli  luni1)ar  and  the  first  and  second  sacral  nerves,  enters  the  superior  angle  of  the 
popliteal  s})ace  and  runs  downwards  and  outwards  in  contact  with  the  iimer  liorder 
of  the  biceps.  It  leaves  the  space  by  passing  between  the  bicei)S  tendon  and  the 
outer  head  of  the  gastrocnemius,  it  crosses  the  poj)liteus  and  the  inferior  ext(>rnal 
articular  artery,  then  it  winds  round  the  neck  of  the  fil)ula  lictween  the  l)on(' 
and  the  peroncus  longus  muscle,  and  terminates  by  dividing  into  the  recurrent 
articular,  tlie  musculo-cutaneous,  and  the  anterior. tibial  nerves. 

Branches. — The  branches  of  the  external  ])o])litcal  nerve  maybe  classified  into 
articular,  cutaneous,  and  terminal. 

(1)  The  articular  branches  accompany  the  su])erior  and  inferior  external 
articular  In-anclics  of  the  i)Oi)liteal  artery,  and  are  distributed  to  the  knee-joint. 

(2)  The  cutaneous  branches  are  two  in  number;  they  often  arise  l>y  a  connnon 


EXTERNAL  POPLITEAL  NERVE  815 

trunk.  One  of  these,  the  external  cutaneous  nerve,  whicli  contains  filjres  fnjm  the 
fifth  himbar  and  the  first  and  second  sacral  nerves  is  distributed  to  the  skin  cover- 
ing; tlie  (lUtHr  and  U])per  i)art  of  the  leg.  The  other  branch,  the  nervus  commu- 
nicans  peronei  or  fibularis,  containing  fibres  from  the  same  roots,  runs  downwards 
and  inwards  beneath  the  deep  fascia,  and  joins  the  nervus  communicans  tibialis 
to  form  the  external  or  short  saphenous  nerve  (page  817). 

(3)  The  recurrent  articular  nerve  ends  principally  in  the  upi)er  ])art  of  tlie 
tibialis  anticus  muscle.  A  few  tiiK-  filaments  accompany  the  anterior  tibial  recur- 
rent artery  to  the  front  of  the  knee-joint,  some  pass  the  superior  tiltio-fibular articu- 
lation, and  others  to  the  head  of  the  tibia. 

(4)  The  musculo-cutaneous  nerve,  containing  fibres  from  the  fourth  and  fifth 
lumbar  and  the  fir.<t  sacral  nerves,  is  directed  dowuwards  through  the  substance 
of  the  peroneus  longus,  and  is  afterwards  placed  between  the  peronei  and  extensor 
longus  digitorum.  Having  given  off  branches  to  supply  these  muscles,  it  divides 
into  an  external  and  an  internal  branch;  these  branches  pierce  the  deep  fascia  in 
the  line  of  the  intermu.^cular  septum  between  the  peronei  and  the  extensor  grou{> 
of  muscles.  The  external  branch  runs  downwards,  in  front  of  the  anterior  annular 
ligament,  and  divides  into  the  following  V)ranches:  a  tAvig  which  communicates  with 
the  short  saphenous;  a  branch  which  divides  to  sup])ly  the  adjacent  sides  of  the 
fourth  and  fifth  toes;  and  a  branch  whidi  communicatis  with  the  internal  division 
of  the  musculo-cutaneous  nerve.  The  internal  branch  crosses  the  anterior  annular 
ligament  about  an  inch  to  the  inner  side  of  the  external  branch,  and  divides  into 
four  branches:  the  first  of  these  communicates  with  the  external  branch,  forming 
with  it  a  nerve  Avhich  bifurcates  to  supply  the  adjacent  sides  of  the  third  and  fourth 
toes;  the  second  divides  to  be  distributed  to  the  contiguous  sides  of  the  second  and 
third  toes;  the  third  communicates  with  the  internal  terminal  branch  of  the  anterior 
tibial  at  the  cleft  between  the  great  and  second  toes;  and  the  fourth  supplies  the 
inner  border  of  the  great  toe. 

In  their  course  across  the  dorsum  of  the  foot  the  branches  of  the  musculo- 
cutaneous nerve  pass  beneath  the  dorsal  venous  arch,  and  from  the  two  main  divi- 
sions of  the  nerve  a  number  of  collateral  twigs  are  given  off,  which  supply  the 
integument  of  the  lower  part  of  the  front  of  the  leg  and  the  dorsum  of  the  foot. 

(5)  The  anterior  tibial  nerve,  formed  from  fibres  of  the  fourth  and  fifth 
lumbar  and  the  first  sacral  nerves,  pierces  the  intermuscular  septum  between  the 
peronei  and  extensors,  and,  having  traversed  the  upper  fibres  of  the  extensor  longus 
digitorum,  runs  downwards  on  the  interosseous  membrane  between  the  last-named 
muscle  and  the  tibialis  anticus;  lower  down  it  is  placed  between  the  tibialis  anticus 
and  the  extensor  longus  hallucis.  It  crosses  beneath  the  extensor  longus  hallucis, 
passes  under  cover  of  the  anterior  annular  ligament,  and  temiinates  in  front  of  the 
bend  of  the  ankle  by  dividing  into  an  external  and  an  internal  branch.  In  this 
course  it  is  placed  external  to  the  anterior  tibial  arter}^  in  the  upper  third  of  the 
leg;  it  lies  on  the  anterior  surface  of  that  vessel  in  the  middle  third,  and  in  the 
remainder  of  its  course  it  is  again  external  to  the  artery. 

Branches. — In  addition  to  the  two  terminal  branches  above  mentioned,  the 
anterior  til>ial  nerve  gives  oflf  an  articular  twig  to  the  ankle-joint,  and  branches  to 
supply  the  tibialis  anticus,  extensor  longus  hallucis,  extensor  longus  digitorum, 
and  jjeroneus  tertius.  The  branches  destined  for  the  two  latter  muscles  arise  in 
conmion,  and  take  the  form  of  a  long  slender  nerve  which  runs  along  the  inner  side 
of  the  muscles.  su]tplyintr  them  with  numerous  twigs. 

The  external  branch  is  directed  outwards  under  cover  of  the  extensor  brevis 
digitorum,  and,  having  supplied  that  muscle,  ends  in  twigs  which  are  distributed 
to  the  tarsal  articulations.  This  nerve  presents  a  gangliform  enlargement  near  its 
termination,  thus  resembling  the  posterior  intero.sseous  nerve  in  the  superior 
extremity,  and  from  its  terminal  branches  filaments  pass  to  the  interosseous  s])aces, 
where  they  anastomose  with  branches  of  the  external  jilantar  nerve  and  supjily  the 
tarso-metatarsal  articulations  and  one  or  more  dorsal  interossei  muscles. 

The  internal  branch  is  directed  forAvards  towards  the  interval  between  the  first 
and  second  toes,  Avhere  it  is  joined  by  a  tAvig  from  tiie  musculo-cutaneous,  and  then 
divides  to  su])i)ly  the  contiguous  margins  of  the  above-mentioned  toes.  In  its 
course  on  the  dorsum  pedis  it  lies  to  the  outer  side  of  the  dorsal  artery  of  the  foot. 


816 


THE  XERVOUS  SYSTEM 


and  it  is  crossed  on  its  superficial  surface  by  the  innermost  division  of  the  extensor 
brevis  ditritoruni.      In  aoldition  to  supplying  the  integument  in   the  area  aV)ove 


Fig.  468. — Distribution  of  the  Muscllo-cutaneous  and  Anterior  Tibial  Nerves  ox 
THE  Anterior  Aspect  of  the  Leg  and  on  the  Dorsum  of  the  Foot.— (Hirschfeld  and 
Leveille. ) 


EXTERSAL  POPLITEAL 
NERVE 
RECURRENT  ARTICULAR 


MUSCUL  0-  CUT  A  NEO  US 

BRANCH  TO  PERONEUS 
LONG  US 


BRANCH  TO  EXTENSOR 
LONG  US  DIG  I  TO  RUM 


BRANCH  TO  PERONEUS 
BREVIS 


MUSCULO-CUTANEOUS 


MUSCUL  0-  CUT  A  NEO  US 
{OUTER  DIVISION) 


SHOP  T  SA  PHENO  US 


COLLATERAL 
BRANCHES  OF  EX- 
TERNAL SAPHENOUS 
AND  MUSCULO- 
CUTANEOUS TO  TOES 


ANTERIOR  TIBIAL 
NER  VE 


Anterior  tibial  artery 


Tibialis  antieus 


ANTERIOR  TIBIAL 
NER  VE 

M  USCULO-CUTANEO  US 
(INNER  DIVISION) 


ANTERIOR  TIBIAL 
(OUTER  DIVISION) 

ITS  DISTRIBUTION  TO 
EN TKNSOR  BREVIS 
Dial  TO  RUM 

ANTERIOR  TIBIAL 
(INNER  DIVISION) 


COLLATERAL 
BRANCHES  OF 
MUSCULO-CUTANEOUS 
TO  TOES 


mentioned,  it  also  gives  branches  to  the  tarso- metatarsal  articulations  and  to  the 
first  dorsal  interosseous  muscle. 


INTERNAL  POPLITEAL  NERVE  817 

The  INTERNAL  POPLITEAL  NERVE,  formed  of  fil)res  from  tlie  fourth  aiul 
fifth  himbar  and  tlie  lirst,  second,  and  tliird  sacral  nerves,  is  larger  than  the  external 
])o})liteal  nerve;  it  runs  downwards,  following  the  same  direction  as  the  great  sciatic, 
to  reach  the  lower  border  of  the  popliteus  muscle,  ■where  it  is  continued  into  the 
posterior  tibial  nerve.  In  this  course  it  occu])ies  the  middle  vertical  diameter  of 
the  popliteal  space,  and  is  the  most  superficially  i)laced  of  the  important  contents 
of  tiiat  sjjace.  It  is  overlapped  l)y  the  hamstring  muscles  above  and  by  the  heads 
of  the  gastrocnemius  below;  but  is  covered  only  by  the  skin  and  fasciae  for  about 
two  inches  above  the  line  of  the  knee-joint.  The  popliteal  vein  intervenes  between 
the  internal  popliteal  nerve  and  the  artery,  and  the  nerve  is  on  a  })lane  superficial 
to  the  vessels.  In  the  up]>er  i)art  of  the  popliteal  space  the  vessels  are  internal  to 
the  nerve;  at  the  level  of  the  knee-joint  they  are  immediately  in  front  of  the  nerve; 
and  at  tlie  lower  part  of  the  space  they  are  placed  external  to  it. 

Branches. — The  branches  of  the  internal  popliteal  nerve  may  be  classified  into 
cutaneous,  articular,  musculai',  and  terminal. 

(1)  The  cutaneous  branch,  the  nervus  communicans  tibialis,  containing 
fibres  from  the  first  and  second  sacral  nerves,  arises  from  the  internal  popliteal 
al)Out  the  centre  of  the  popliteal  space,  and  runs  vertically  downwards,  under  cover 
of  the  deep  fascia,  to  reach  the  interval  between  the  two  heads  of  the  gastrocnemius; 
then,  inclining  a  little  outwards,  it  pierces  the  deep  fascia,  and  unites  with  the 
conmumicans  fibularis  to  form  the  short  saphenous  nerve.  The  external  or  short 
saphenous  nerve  is  formed  alwut  the  middle  of  the  calf  (sometimes  higher  up  or 
lower  d(jwn),  and  runs  downwards  and  out^vards,  accom]ianied  by  the  vein  of  the 
same  name,  to  reach  the  interval  betAveen  the  external  malleolus  and  the  calcaneum. 
It  crosses  superficial  to  the  external  annular  ligament,  and  then  runs  forwards  along 
the  outer  border  of  the  foot,  supplying  numerous  twigs  to  the  integument  of  the 
region.  Having  communicated  Avith  the  external  branch  of  the  musculo-cutaneous, 
it  terminates  by  supplying  the  integument  on  the  outer  side  of  the  little  toe. 

Varieties. — In  a  large  number  of  cases  the  distribution  of  this  nerve  is  much  more  extensive. 
It  may  supply  the  fiftli  and  fourth  toes  and  the  outer  border  of  the  third.  In  some  cases  the 
communicans  fibularis  does  not  join  the  communicans  tibialis,  but  ends  independently  in  the 
intci-'uments  of  the  calf 

(2)  The  muscular  branches  of  the  internal  popliteal  nerve  are  distributed  to 
the  gastrocnemius,  soleus,  plantaris,  and  popliteus  muscles.  There  is  a  separate 
branch  for  each  head  of  the  gastrocnemius,  containing  fibres  from  the  first  and 
second  sacral  nerves.  The  branches  to  the  plantaris  and  popliteus  muscles  are 
formed  of  fibres  from  the  fourth  and  fifth  lumbar  and  first  sacral  nerves.  The 
l)ranch  to  the  popliteus  arises  lower  doAvn  than  the  other  branches.  It  crosses  the 
superficial  surface  of  the  popliteal  artery  to  reach  the  outer  side  of  that  vessel,  runs 
downwards  on  the  posterior  surface  of  the  popliteus,  and  winds  round  the  lower 
border  of  that  muscle  to  gain  its  deep  or  anterior  surface,  where  it  ends  in  the  mus- 
cular substance;  before  it  turns  round  the  lower  border  of  the  muscle,  it  gives  a 
branch  to  the  superior  tibio-fibular  articulation,  another  to  the  tibia  along  the  medul- 
lary artery,  and  a  long  branch  to  the  interosseous  membrane;  the  latter  gives  twigs 
to  the  anterior  and  posterior  tibial  arteries  and  then  runs  down  in  the  interosseous 
membrane  and  ends  in  the  inferior  tibiofibular  articulation.  The  nerve  to  the 
soleus  is  relatively  large,  it  crosses  the  plantaris  to  gain  the  posterior  surface  of  the 
soleus  carrying  fil>res  of  the  fifth  lumbar  and  the  first  and  second  sacral  nerves. 

(3j  The  articular  branches  are  three  in  numlier,  and  accompany  the  superior 
and  inferior  internal  articular  and  the  azygos  branches  of  the  ])Opliteal  artery,  to  be 
distril)uted  to  tlie  knee-joint. 

The  POSTERIOR  TIBIAL  NERVE  contains  fibres  derived  from  the  fourth  and 
fifth  lumbar  and  llie  first  and  sec-ond  sacral  nerves;  it  is  the  terminal  branch  of  the 
internal  popliteal,  or  rather  the  direct  continuation  of  that  nerve.  It  runs  down- 
wards with  an  inclination  inwards  to  reach  the  interval  between  the  inner  malleolus 
and  the  os  calcis,  and,  having  passed  under  cover  of  the  origin  of  the  abductor 
hallucis  muscle,  terminates  by  dividing  into  the  internal  and  external  plantar 
nerves,  at  a  point  midway  between  the  tip  of  the  internal  malleolus  and  the  most 
prominent  part  of  theos  calcis.      In  the  upjter  ]>art  of  its  course  it  is  covered  by  the 


818 


THE  NERVOUS  SYSTEM 


gastrocnemius,  plantaris,  and  soleus  muscles,  and  b}'  the  intermuscular  part  of  the 
cleep  fascia  of  the  leg.  Lower  down,  as  it  approaches  the  ankle,  it  is  covered  only 
Ijy  the  skin  and  fasciie.  Its  anterior  relations  are  the  tibialis  posticus  in  the  upper 
and  the  flexor  longus  digitorum  and  the  tibia  in  the  lower  portion  of  its  cours(\ 
The  posterior  til )ial  vessels  are  i)laced  externally  to  its  upper  part;  alcove  the  middle 
of  the  leg  they  cross  in  front  of  the  nerve,  and  run  downwards  jiarallel  to  its  inner 
side. 

Branches. — The  posterior  tibial  nerve  supplies  the  three  deep  muscles  of  the 


Fig.  469. — Superficial  Nerves  in  the  Sole  of  the  Foot.     i^Ellis.) 


Abduetor  hallueis 


Flexor  brevis  digitorum 

INTERNAL  PLANTAR 
NERVE 

Internal  plantar  artery 


BRANCH  OF  INTER- 
NAL PLANTAR 
NERVE  TO  INNER 
SIDE  OF  HALLUX 


Abduetor  minimi  digiti 


Exiernal  plantar  artery 

EXTERNAL  PLANTAR 
NER  VE 


DIGITAL  COLLATERAL 
BRANCHES  OF  EX- 
TERNAL  PLANTAR 


DIGITAL  COLLATERAL 
BRANCHES  OF  INTER- 
NAL PLANTAR 


I 


calf,  viz.  the  tibialis  jy^-'^tic^'^,  flexor  longus  digitorum,  and  flexor  longus  hallueis,  the 
two  former  V)y  twigs  from  the  fifth  lumbar  and  the  first  sacral  nerves,  whilst  the 
latter  receives  additional  fibres  from  tlic  second  sacral  nerve,  and  it  gives  a  l)ranch 
to  the  soleus.  It  also  furnishes  one  or  two  articular  filament^s  to  the  ankle-joint, 
and  gives  off  a  cutaneous  branch,  the  internal  calcancan. 

(1)  The  internal  calcanean  or  calcaneo-plantar  cutaneous  branch  contains 
fibres  from  the  first  and  second  sacral  nerves.  It  arises  from  the  posterior  til>ial 
nerve  a  little  above  the  level  of  the  inner  malleolus,  and  passes  under  cover  of  the 
internal  annular  lisfament.  where  it  divides  into  several  branches.     These  branches 


SYMPATHETIC  XERVES  819 

pierce  the  internal  annular  liganjent,  accompanying  the  branches  of  the  internal 
calcanean  artery,  and  are  distrilnited  to  the  thick  fascia  and  integument  which 
covers  tlie  heel  and  adjacent  part  of  the  sole. 

(2)  The  internal  plantar  nerve  is  formed  of  fibres  from  the  fourth  and  fifth 
lumbar,  and  the  first  and  second  sacral  nerves.  It  is  the  larger  of  the  two  terminal 
branches  of  the  posterior  tibial,  and  corresponds  in  its  distribution  to  the  median 
nerve  in  the  hand.  It  runs  forwards  in  the  interval  between  the  abductor  hallucis 
and  the  flexor  brevis  digitorum;  gives  off  branches  to  supply  both  these  muscles, 
and  a  number  of  cutaneous  twigs  which  appear  in  the  interval  between  the  middle 
and  internal  parts  of  the  plantar  fascia.  It  also  sup^dies  the  astragalo-navicular 
and  the  internal  intercuneiform  joints.  Near  the  level  of  the  tarso-nietatarsal 
articulation  it  terminates  l:)y  dividing  into  four  digital  Ijranches.  The  first  digital 
branch  gives  off  a  branch  to  supply  the  flexor  brevis  hallucis,  and  then  runs  along 
the  inner  side  of  the  great  toe  as  far  as  the  extremity  of  that  digit.  The  second 
branch  gives  off  a  twig  to  supply  the  first  or  innermost  lumbrical  muscle,  and  then 
divides  into  two  collateral  branches  which  supjdy  the  adjacent  sides  of  the  great  and 
second  toes.  The  third  branch  divides  in  a  similar  manner  to  supply  the  contigu- 
ous sides  of  the  second  and  third  toes.  The  fourth  branch  communicates  with  tlie 
superficial  di\'ision  of  the  external  plantar,  and  divides  to  supply  tlie  adjacent  sides 
of  the  third  and  fourth  toes.  The  muscular  twigs  to  the  flexor  1:)revis  hallucis  and 
the  first  lumbrical  muscle  contain  fibres  from  the  fifth  lumbar  and  first  sacral 
nerves. 

(3)  The  external  plantar  nerve  is  formed  by  fibres  of  the  first  and  second 
sacral  nerves.  It  shows  many  points  of  resemblance  to  the  distribution  of  the 
ulnar  nerve  in  the  hand.  From  its  origin,  at  the  temiination  of  the  posterior  til)ial 
nerve,  it  is  directed  outwards  and  forwards  between  the  flexor  brevis  digitorum  and 
the  flexor  accessorius.  In  this  part  of  its  course  it  supplies  the  accessorius,  the 
al)ductor  minimi  digiti,  and  the  calcaneo-cuboid  joint.  It  is  then  directed  forwards 
in  the  interval  between  the  last-named  muscle  and  the  flexor  brevis  digitorum,  and 
terminates  at  the  level  of  the  tarso-metatarsal  articulations  by  dividing  into  a  super- 
ficial and  a  deep  division.  Previous  to  its  division  it  gives  oft'  several  cutaneous 
twigs,  which  appear  in  tlie  inter\'al  between  the  middle  and  external  divisions  of  the 
plantar  fascia.  The  superficial  division  divides  into  two  digital  nerves,  an  exter- 
nal and  an  internal.  The  internal  branch  supplies  the  interosseous  muscles  which 
occupy  the  fourth  interosseous  space,  and,  having  communicated  with  the  internal 
plantar,  divides  into  two  collateral  branches  which  supply  the  contiguous  sides  of 
fourth  and  fifth  toes.  The  external  branch  supplies  the  flexor  brevis  minimi 
digiti,  and  is  then  directed  along  the  f)Uter  border  of  the  little  toe  to  terminate  at 
the  extremity  of  that  digit.  The  deep  division  of  the  external  plantar  nerve  runs 
inwards  and  forwards  on  the  dorsal  or  deep  surface  of  the  flexor  tendons,  and  rami- 
fies in  the  interval  between  these  tendons  and  the  interosseous  muscles.  It  sup- 
plies the  three  outer  lumbrical  muscles,  the  interosseous  muscles  occupying  the 
three  inner  interosseous  spaces,  the  transvcrsus  pedis,  and  the  adductor  hallucis. 
and  it  gives  branches  to  the  adjacent  articulations. 


Table  Showing  Relations  of  Lumbar   and   Sacral   Xerves   to   Branches   ov 

Lumbar  and  Sacral  Plexuses 
XicKVE  Roots.  Nekves. 

I  J  r  Ilio-hypogastris 

(.     ,,    inguinal 

1  and  2  1 Genito-crural 

2  and  3  L External  cutaneous 

2,  3,  and  4  1 .[  Anterior  crural 

'     '  (  Ol»turator 

4,  5  L. ,  and  IS /  ^npoi'ior  gluteal 

I  Xerve  to  quadratus  femoris 

4,  5  L.,  land  2  S Gt.  sciatic  (ext.  poplit.  i)art) 

4,  5  L.,  1.  2,  and  3  S Qt.  sciatic  (int.  poplit.  part) 


820  THE  NERVOUS  SYSTEM 

Table  Showing  Relations  of  Lumbar  and  Sackal  Nerves  to  Branches  of 
Lumbar  and  Sacral  Plexuses. — Continued 

Nekve  R(jots.  Nerves. 

5  L     1  and  2  8 ^  Inferior  gluteal 

■ '      '        "  ' 1  Xerve  to  obturator  internus 

1  and  2  S Nerve  to  pyriforniis 

o       1  .-)  o  (  Perforating  cutaneous 

2  and  o  b J  ^,       „      .7. 

\  Small  sciatic 

2,  3,  and  4  S Pudic 


Table   Showing 
Xerve  Roots. 

2  and  3  L.      .    . 

2,  3,  and  4  L.    . 

3  and  4  L.      .    . 

3,  4,  and  5  L.    . 


4,  5  L.,  and  IS.     .    . 


Relations  of  Muscles   of  Lower   Extremity   to   Nerves   of 
Lumbar  and  Sacral  Plexuses 


5  L.  and  1  S.     . 


5  L.,  1  and  2  S. 


1  and  2  S.       .    . 


1,  2,  and  3  S. 


4,  5  L.,  and  IS. 


Muscles. 
Ilio-psoas 
Sartorius 
Pectineus 
Adductor  longus 
CTracilis 

Adductor  brevis 
Quadriceps  extensor 
Ol^turator  externus 
Adductor  niagnus 
Gluteus  medius 

.,         minimus 
Tensor  fasc.  femoris 
Semimembranosus 
Plantaris 
Popliteus 

Quadratus  femoris 
Inferior  gemellus 

f  Flex.  long,  digit. 
Tibialis  posticus 
Flexor  brev.  digit. 
,,          ,,      hallucis 

I  Abductor  ,, 

I  First  lumbrical 
Superior  gemellus 
Obturator  internus 
Gluteus  maximus 

I  Semitendinosus 

I  Soleus 

L  Flex.  long,  hallucis 

f  Pyriforniis 
Gastrocnemius 
Flexor  accessorius 
Abd.  min.  digiti 
Plantar  interossei 
Dorsal  , , 

Add.  hallucis  trans. 
,,  ,,        obliq. 

Long  head  of  bicejis 

^  Ext.  long.  hall. 
. ,       digit, 
brev.     ,, 
Tibialis  anticus 
Peroneus  tertius 
,,         longus 

[         , ,         brevis 


Nerves. 
Anterior  crural 


Obturator 


Anterior  crural 
Obturator 

,,  and  gt.  sciatic 

Superior  gluteal 


Gt.  sciatic 
Internal  popliteal 

Nerve  to  quad.  fem. 

"     .    "  .   .    " 
Posterior  tibial 

?5  11 

Internal  plantar 

"  "    . 

Nerve  to  obt.  int. 

."  " 

Inferior  gluteal 

Gt.  sciatic 

Int.  poplit.  and  j^ost.  tib. 

Posterior  tibial 

Int.  popliteal 
External  plantar 


Gt.  sciatic 
Anterior  tibial 


Musculo-cutaneous 


DISTRIBUTIOX  OF  CUTANEOUS  BRANCHES  821 


THE  DISTRIBUTIOX  OF  THE  CI'TAXEOUS  BRAXCHES  OF  THE 
SEXSORY  AXD  MIXED  XERVES 

The  ciitani^vms  filaments  of  the  sensory  and  mixed  nerves  are  distril)uted  to 
definite  regions  of  the  surface  of  the  l)ody  which  are  known  as  "  cutaneous  areas." 
Each  cutaneous  area  has  one  special  nerve  of  supply  and  the  central  part  of  the 
area  receives  that  nerve  alone,  but  wherever  the  borders  of  two  areas  meet  they 
reciprocally  overlap,  therefore  each  margin  of  every  cutaneous  area  receives  two 
nerves  of  supply,  its  own  nerve  and  that  of  an  adjacent  area,  and  of  these  sometimes 
one  and  sometimes  the  other  preponderates. 

The  Cutaneous  Areas  of  the  Scalp 

The  limits  of  the  cutaneous  areas  in  the  scalp  region  are  indicated  in  Figs.  469a, 
469b,  but  in  general  terms  it  may  be  said  that  the  skin  of  the  scalp  in  front  of  the 
pinna  is  supplied  by  four  cutaneous  nerves,  the  mesial  part  b}"  the  supratrochlear 
and  the  supraorbital  l)ranches  of  the  first  division  of  the  fifth  cranial  nerve,  and 
the  lateral  part  by  the  temporal  branch  of  the  second  division,  and  the  auriculo- 
temporal In'anch  of  the  third  division  of  the  same  nerve. 

The  portion  of  the  scalp  behind  the  pinna  also  receives  four  cutaneous  nerves; 
laterally  it  is  sui)plied  by  the  great  auricular  and  small  occipital  branches  of  the 
cervical  plexus  which  contain  filaments  from  the  second  and  third  cervical  nerves, 
and  mesially  it  receives  the  great  and  smallest  occipital  nerves  which  are  derived 
from  the  internal  divisions  of  the  posterior  primary  branches  of  the  second  and 
third  cervical  nerves  respectively. 

The  Cutaneous  Areas  of  the  Face 

^^'itll  tlie  exception  of  the  skin  over  the  posterior  part  of  the  masseter  muscle 
the  whole  of  the  skin  of  the  face  is  supplied  by  the  branches  of  the  fifth  cranial 
nerve.  The  nose  is  supi^lied  mesially  by  the  supratrochlear,  the  infratrochlear,  and 
the  nasal  branches  of  the  first  division,  and  laterally  by  the  infraorbital  branch  of 
the  second  division.  The  upper  eyelid  is  supplied  by  the  supratrochlear,  the  supra- 
orljital,  and  the  lachrymal  branches  of  the  first  division;  the  lower  eyelid  by  tlie 
infratrochlear  liranch  of  the  first  division  and  by  the  infraorbital  and  the  malar 
l)ninches  of  the  second  division.  The  skin  over  the  upper  jaw  and  the  malar  Ijone 
i:s  supplied  by  the  infraorbital  and  malar  liranches  of  the  second  division,  that  over 
the  buccinator  muscle  by  the  buccal  branch  of  the  third  division,  and  that  over  tli(^ 
lower  jaw,  from  before  backwards,  by  the  mental,  Iniccal,  and  auricnlo-temporal 
branches  of  the  third  division,  except  a  small  part  near  the  posterior  border  which 
receives  its  supply  from  the  great  auricular  nerve. 

The  Cutaneous  Areas  of  the  Pinna 

The  upjier  two-thirds  of  the  outer  surface  of  the  pinna  are  supplied  by  the 
auriculo-temporal  branch  of  the  third  division  of  the  fifth  cranial  nerve,  and  tlic 
lower  third  by  twigs  of  the  great  auricular  nerve.  The  cranial  surface  of  the  pinna 
is  supplied  in  the  lower  part  of  its  extent  l»y  the  great  auricular  nerve,  and  in  the 
upper  part  by  the  small  occipital  nerve.  The  posterior  surface  of  the  external 
auditory  meatus  receives  filaments  from  the  auricular  Ijranch  of  the  tenth  cranial 
nerve. 

The  Cutaneous  Areas  of  the  Xeck 

The  skin  over  the  anterior  part  of  the  neck  is  supplied  by  the  superficial  cervical 
branch  of  the  cerx-ical  plexus,  which  contains  filaments  of  the  .second  and  thinl 
cervical  nerves,  and  in  the  lower  part  of  its  extent  by  the  suprasternal  l)ranch, 
which  conveys  twigs  of  the  third  and  fourth  cervical  nerves  (fig.  469a).  The  lateral 
part  of  the  neck  receives  filaments  from  the  second,  third,  and  fourth  cervical  nerves 


822 


THE  NERVOUS  SYSTEM 


by  the  great  auricular,  small  occipital,  and  supraclavicular  branches  of  the  cervical 
plexus  (fig.  469a),  and  posteriorly  the  skin  of  the  neck  is  sui)plied  by  the  small 
occipital  nerve  and  by  the  internal  branches  of  the  posterior  primary  divisions  of 
the  cervical  nerves  from  the  second  to  the  sixth  inclusive  (fig.  469b). 


Fig.  469a. — Diagram  of  the  Cutaxeous  Nekve  Areas  of  the  Head  axd  Neck. 

Red — First  division  of  fifth.  White — Second  division  of  fifth. 

Blue — Third  division  of  fifth. 
Dark  shading — Posterior  primary  division  of  cervical  nerve. 

Oblique  shading — Ascending  and  transverse  superficial  branches  of  cervical  plexus. 
Transverse  shading — Descending  superficial  branches  of  cervical  plexus. 
It  must  be  understood  the  boundaries  of  each  area  are  not  distinct ;   wherever  two  areas  meet  they  overlap. 


SMALLEST 
OCCIPITAL 


TEMPO  RA  L 
SUPRA 
TROCHLEAR 

LACHRYMAL 

INFRA 
'ROC  H  LEAR 

NASAL 


\ 


The  Cutaneous  Areas  of  the  Body 

The  skin  over  the  anterior  aspect  of  the  body  as  far  down  as  the  second  rib  is 
supplied  by  the  suprasternal  and  supraclavicular  branches  of  the  cervical  plexus, 
which  contain  filaments  from  the  third  and  fourtli  cervical  nerves  (fig.  469b);  from 
the  second  rib  to  the  lower  part  of  the  abdominal  wall  it  receives  the  anterior  cuta- 
neous branches,  and  the  anterior  divisions  of  the  lateral  cutaneous  l)ranches  of  the 
dorsal  nerves  except  the  first,  second,  and  twelfth  (fig.  469b);  and  the  skin  over  the 


DISTRIBUTION  OF  CUTANEOUS  BRANCHES  823 

lower  and  anterior  part  of  the  abdominal  wall  is  supplied  by  the  ilio-liypogastric 
branch  of  the  tirst  lumbar  nerve. 

The  cutaneous  supply  of  the  lateral  aspect  of  the  body  is  derived  from  the  lateral 
branches  of  the  anterior  primary  divisions  of  the  dorsal  ner\'es  from  tlie  second  to 
the  eleventh,  and  the  skin  over  the  jjosterior  aspect  of  the  l)ody  is  supplied  externally 
by  the  posterior  divisions  of  the  lateral  branches  of  the  dorsal  nerves  from  the 
third  to  the  eleventh,  and  internally  l>y  the  posterior  i)rimary  divisions  of  the  dorsal 
nerves  (fig.  469b),  in  the  upper  half  by  their  internal  branches  and  in  the  lower 
half  i»rincipally  by  their  external  branches. 

The  Cutaxeous  Areas  of  the  VprER  Limb 

The  skin  over  the  upper  third  of  the  deltoid  muscle  is  supplied  by  the  supra- 
acromial  and  supraclavicular  branches  of  the  cervical  plexus,  which  contain  fila- 
ments of  the  third  and  fourth  cervical  nerv^es,  and  that  over  the  lower  two-thirds 
bv  the  circumflex  nerve,  which  conveys  fibres  of  the  fifth  and  sixth  cer^'ical  nerves 
(iig.  469b). 

The  skin  over  the  front  of  the  upper  ami  is  supplied  externally  by  the  circum- 
flex nerve  above  and  by  the  superior  external  cutaneous  branch  of  the  musculo- 
spiral  nerve  below;  the  former  contains  filaments  of  both  the  fifth  and  sixth  cervical 
nerves,  and  the  latter  filaments  of  the  sixth  alone.  Internally  the  skin  of  the  upper 
arm  is  supplied  by  the  internal  cutaneous  nen'e  with  filaments  of  the  eighth  cervical 
and  first  dorsal  nerv^es,  and  by  the  lesser  internal  cutaneous  and  intercosto-humeral 
nerves  which  are  derived  from  the  first  and  second  dorsal  nerves.  The  back  of  the 
ujtper  arm  is  supplied,  externally,  by  the  fifth  and  sixth  cervical  nerves  through  the 
circumflex  nerve,  and  the  external  cutaneous  branches  of  the  musculo-spiral  nerve; 
mesially  by  the  eighth  cervical  nerve  through  the  internal  cutaneous  branch  of  the 
musculo-spiral  nerve,  and  internally  by  the  first  and  second  dorsal  ner^^es  through 
the  lesser  internal  cutaneous  and  intercosto-humeral  ner^^es  (fig.  469). 

The  front  of  the  forearm  is  divided  into  two  areas,  an  external,  which  is  sup- 
plied by  the  fifth  and  sixth  cervical  nerves  through  the  musculo-cutaneous  branch 
of  the  brachial  plexus,  and  an  internal,  supplied  by  the  eighth  cervical  and  first 
dorsal  nerves  through  the  internal  cutaneous  nerve.  On  the  back  of  the  forearm 
there  are  three  areas:  an  external,  supplied  by  filaments  of  the  fifth  and  sixth  cer- 
vical nerves  through  the  musculo-cutaneous  nen-e;  a  middle,  which  receives  fila- 
ments of  the  sixth,  seventh,  and  eighth  cervical  nerves  through  the  inferior  external 
cutaneous  branch  of  the  musculo-spiral  nen'e;  and  an  internal,  which  receives  the 
eighth  cervical  and  first  dorsal  ner\-es  through  the  internal  cutaneous  nerve 
(fig.  469b). 

The  front  of  the  hand  is  supplied  by  the  sixth,  seventh,  and  eighth  cervical 
nerves  and  by  the  first  dorsal  nerve  through  the  radial  branch  of  the  musculo-sjtiral 
nerve  and  through  the  median  and  ulnar  branches  of  the  brachial  plexus.  The 
radial  nerve  supplies  the  radial  side  of  the  thumb  by  its  palmar  cutaneous  branch; 
the  remainder  of  the  palm  and  the  palmar  aspects  of  the  fingers  are  supplied  by 
the  median  and  ulnar  nerves  through  their  palmar  cutaneous  and  digital  branches, 
the  median  supplving  three  and  a  half  digits  and  the  ulnar  the  remaining  one  and 
a  half  (fig.  469b)I 

The  dorsal  aspect  of  the  hand  is  supplied  by  the  sixth,  seventh,  and  eighth 
cervical  nerves  which  reach  it  through  the  radial  branch  of  the  musculo-spiral 
nerve  and  through  the  median  and  ulnar  nerv'es.  The  radial  nerve  supplies  the 
outer  part  of  the  dorsum  and  the  outer  three  and  a  half  digits,  except  the  lower 
}>arts  of  the  index,  middle,  and  half  the  ring  digits  Avhich  receive  twigs  from  the 
median  nerve,  and  the  ulnar  nerve  supplies  the  ulnar  half  of  the  dorsum  including 
the  inner  one  and  a  half  digits. 

The  Cutaneous  Areas  of  the  Lower  Extre:mity 

There  are  six  cutaneous  areas  in  the  region  of  the  buttock,  three  upper  and  three 
lower.  Of  the  upper  areas  the  external  is  supplied  by  the  anterior  ])rimary  divi- 
sions of  the  last  dorsal  and  first  lumbar  nervt-s  through  the  iliac  l)ranches  of  the 


Fig.  469b. — DiA(iK.\M  showing  the  Ark.vs  of  Distribution  of  Citaneous  Nerves. 

Head: — 

Ked — First  division  of  fifth.  AVhite — .Second  division  of  fifth.  Blue — Third  divi.-^ion  of  fifth.  Dark- 
area— Posterior  j>rimary  divisions  of  cervical  nerves.  Oblique  and  transverse  shading — Branches  of 
cervical  ]>lexus. 

Body  and  Limbs: — 

Red — Anterior  divisions  of  anterior  primary  branches.  Blue — Posterior  division  of  anterior  primary  branches. 
Two  colors  in  one  area  indicate  that  the  area  is  sunplied  by  two  sets  of  nerves,  and  it  should  be  under- 
stood that  wherever  two  nerve  areas  approach  each  other  they  overlap.  The  dotted  blue  area  of  small 
sciatic  indicates  that  the  nerve  comes  from  the  posterior  part  of  anterior  primary  divisions  of  sacral 
nerves,  but  it  supplies  a  flexor  area.  The  area  of  the  ])erforating  cutaneous  nerve  i.s  left  uneohmred, 
because  its  true  nature  is  uncertain.  Dark  shading — Posterior  primary  divisions.  The  numbers  and 
initial  letters  refer  to  the  nerve  roots  from  which  the  nerves  are  derived. 


Ut  DIVISION  OF 5th 

Sd  DIVISION  OF  5th   ~ 

M  DIVISION  OF  5th  - 

GREA  T  A  URICULA  R    - 

2,3  C,  SUPERFICIAL  CERVICAL  - 


SUPERFICIAL 
DESCENDING  CERV. 

CIRCUMFLEX 
LA  TERA  L  CUTA  NEO  US  — 
NER VES 
ANTERIOR   CUTANE-   " 
OUS  NERVES 

LESSER  IXTERyAL  Cl'TASE- 
Ors  AXD    IXTERCOSTO-BU-     — ' 

MERAL,  I,  2  D 
VPPER   EXTERNAL    CUTANE-   ... 
OUS  OF  ML'SCULO-SPIRAL 

INTERNAL  CUTANEOUS  - 
MUSCULO-CUTANEOUS  " 

EXTERNAL 
CUTANEOUS  " 


SUPRAORBITAL 

GREAT  OCCIPITAL 
SMALL  OCCIPITAL 
SMALLEST  OCCIPITAL 
GREA  T  A  URICULAR 

POSTERIOR  PRIMARY  DIVI- 
SIONS OF  CERVICAL  NERVES 


SUPERFICIAL  DE- 
SCENDING CER  VI- 
CAL,  S,  U  C 


GENITO-CRURAL 


RADIAL,  6  C 
ILIO-ISGVIXAL,  I  L 
JfEDIAX,  6,7,  S  C.  ID 

ULNAR,  1  D 


INTERNAL  CUTANEOUS 
MIDDLE  CUTANEOUS 


EXTERNAL  POPLITEAL  - 
INTERNAL  SAPHENOUS  - 


CIRCUMFLEX,  5,6  C 


UPPER  EXTERNAL    CUTAXE- 
OrS  OF  iirSliLOSPIRAL 

IX  TER  COS  TO- HI  HERA  L    A  XI> 
LESSER  JXT.  CUTAXEOrS 

JXTERXAL  CUTANEOUS  OF 
MUSCULO-SPIRAL 


LOWER  EXTERXAL  OF 
MUSCULO-SPIRAL,  6,  7,  a  C 

IXTERXAL  CUTAXEOUS 
POSTERIOR  PRIMARY 

LUMBAR 
LATERAL  CUTAXEOUS  OF 

ILIOHYPOGASTRIC 
MUSCULO-CUTANEOUS.  S,  6  C 

POSTERIOR  PRIM.  SACRAL 
PER  FOR  A  TINC, 
CUTANEOUS  OF  2d 
Aa\I)  3d  SACRAL 

--    ULNAR,  S  C 
RADIAL,  S,  7  C 

>.._    AREA  SUPPLIED    BY 
RADIAL  AND   ULNAR 
NER  VES 


MEDIAN.  6,  7,8C, 
ID 


MI :sCJ'L <)- (n- TA  NEO  I S    . 

EXTERNAL  SAPHENOCS    , 

ANTERIOR  TIIilAL  •■ 
INTERNAL  PL  A  NT  A  K  .. 


EXTERNAL  CUTANEOUS 
SMALL  SCIATIC 


INTERNA  L  CUTA  NEO  US  A  ND 
OBTURATOR 


EXTERNAL  POPLITEA  L,5L,1,2S 
.  INTERNAL  SAPHENOUS,  S,  U  L 

.  EXTERNAL  SAPHENOUS,  J,  S  S 


CA  L  CA  NEO-PLA  NT  A  R   {Post- 
tibial),  1,2  S 

EXTERNAL  PLANTAR,  1,  2  S 
INTERNAL  PLANTAR,  ',,  5  L,l  s' 


824 


DISTRIBUTION  OF  CLTAXEOi'S  B RANCHES  825 

twelftli  dorsal  and  the  ilio-hypogastric  nerves;  the  middle  ui)[)er  area  receives  the 
external  divisions  of  the  j)osterior  primary  Ijranehes  of  the  U))})er  three  lumliar 
nerves,  and  the  inner  and  ujjiier  area  is  suijjdied  Ijy  twigs  fr(jm  the  external  divi- 
sions of  the  posterior  primary  branches  of  the  upper  two  or  three  sacral  nerves 
(fig.  469b). 

Of  the  lower  three  areas  the  outer  receives  filaments  from  the  second  and  third 
lund)ar  nerves  through  the  external  cutaneous  branch  of  the  lumbar  plexus,  the 
middle  area  is  supplied  l»y  the  first,  second,  and  third  sacral  nerves  through  the 
small  sciatic  nerve,  and  the  inner  area  by  the  second  and  third  sacral  nerves  through 
the  perforating  cutaneous  l)ranch  of  the  sacral  plexus  (fig.  469b). 

On  the  back  of  the  thigh  there  are  three  areas.  The  external  and  the  internal 
are  su})pHed  l)y  the  second  and  third  lumbar  nerves,  the  former  thvougli  the 
external  cutaneous  branch  of  the  lumbar  plexus  and  the  latter  through  the  internal 
cutaneous  branch  of  the  anterior  crural  nerve;  the  middle  area  receives  twigs  from 
the  first,  second,  and  third  sacral  nerves  through  the  small  sciatic  branch  of  the 
sacral  plexus  (fig.  469b). 

The  front  of  the  thigh  is  supplied  by  the  first,  second,  and  third  lumbar  nerves, 
and  there  are  five  cutaneous  areas;  the  outer  receives  twigs  of  the  second  and  third 
lumbar  nerves  through  the  external  cutaneous  nen'e.  There  are  two  mesial  areas, 
an  upper  and  a  lower.  The  former  is  suj^plied  by  the  crural  l^ranch  of  the  genito- 
crural  wliich  conveys  twigs  of  the  first  and  second  lumbar  nerves,  and  the  latter 
receives  filaments  of  the  second  and  third  luml)ar  nerves  through  the  middle 
cutaneous  branch  of  the  anterior  crural  nerve.  The  small  upper  and  internal  area 
is  supi)lied  by  the  first  lumbar  nerve  through  the  ilio-inguinal  branch  of  the 
luml>ar  ])lexus,  and  the  lower  internal  area  receives  twigs  of  the  second  and  third 
lumbar  nerves  through  the  internal  cutaneous  branch  of  the  anterior  crural  nerve 
(fig.  469b). 

The  front  of  the  knee  is  supi^lied  b}^  the  second,  third,  and  fourth  lumbar 
nerves  through  the  middle  cutaneous,  the  internal  cutaneous,  and  the  long  saphen- 
ous liranches  of  the  anterior  crural  nerve  (fig.  469b). 

The  skin  over  the  region  of  the  popliteal  space  receives  filaments  internally 
from  second,  third  and  fourth  luml)ar  nerves  through  the  internal  cutaneous  l)ranch 
of  the  anterior  crural  nen-e  and  through  the  superficial  division  of  the  ol:)turator 
nerve;  mesially  and  externally  it  receives  twigs  of  the  first  three  sacral  nerves 
through  the  small  sciatic  nerve  (fig.  469b). 

The  skin  of  the  front  and  inner  side  of  the  leg  is  supplied  h\  the  third  and 
fourth  lumbar  nerves  through  the  long  saphenous  branch  of  the  anterior  crural 
nerve,  and  the  skin  of  the  front  and  outer  side  of  the  leg  receives  filaments  of  the 
fifth  luml)ar,  and  the  first  and  second  sacral  nerves  through  the  external  cutaneous 
branch  of  the  external  poi)liteal  nerve.  The  skin  of  the  lower  and  middle  j^art  of 
the  anterior  aspect  of  the  leg  is  supplied  by  tlie  musculo-cutaneous  nerve  which 
convevs  filaments  of  the  fourth  and  fifth  lumliar  and  the  first  sacral  nerve 
(fig.  469b}. 

In  the  skin  of  the  ])ack  of  the  leg  five  areas  can  be  distinguished,  two  internal, 
upper  and  lower,  two  middle,  ujjper  and  lower,  and  an  external.  The  ui)per  and 
inner  area  is  supplied  Ijy  the  second,  third,  and  fourth  lumbar  nerves  through  the 
internal  cutaneous  branch  of  the  anterior  crural  nerve  and  the  superficial  Viranch  of 
tlie  obturator  nerve,  the  lower  internal  area  receives  filaments  from  the  third  and 
fourth  lumbar  nerves  through  the  long  sa]ihenous  nerve.  The  upper  middle  area 
is  sujiplied  by  the  first,  second  an<l  third  sacral  through  the  small  sciatic  nerve.  an<l 
the  lower  middle  area  by  the  first  and  second  sacral  nerves  through  the  external 
saphenous  nerve.  The  outer  area  is  sup])lied  l)y  the  fifth  luml)ar  and  the  first  and 
second  sacral  nerves  through  the  external  cutaneous  branch  of  the  external  popli- 
teal nerve  (fig.  469b).  , 

The  skin  of  the  dorsum  of  the  foot  is  supplied  principally  b}'  the  fourth  and 
fifth  lumbar  and  by  the  first  sacral  nerves;  the  majority  of  the  nerve  filaments 
travel  by  the  musculo-cutaneous  nerve,  but  the  adjacent  sides  of  the  first  and 
second  toes  are  supplied  by  the  anterior  crural  nerve,  and  the  outer  side  of  the 
dorsum  of  the  little  toe  is  su])plied  by  the  first  and  second  sacral  nerves  through 
the  external  saphenous  nerve  (fig.  469b). 


,S26  THE  NERVOUS  SYSTEM 

The  skin  of  the  region  of  the  heel  is  supphed  by  the  first  and  second  sacral 
nerves,  on  the  inner  surface  and  inner  part  of  the  under  surface  by  means  of  the 
calcaneo-plantar  branch  of  the  }tosterior  tibial  nerve,  and  on  its  posterior,  external, 
and  lower  aspects  by  the  ext^-rnal  saphenous  nerve  (fig.  469b). 

The  sole  of  the  foot  in  front  of  the  heel  receives  cutaneous  filaments  from  the 
last  two  lumbar  and  the  first  two  sacral  nerves,  the  inner  area,  Avhich  includes  the 
inner  three  and  a  half  digits,  being  sujiplied  by  the  internal  plantar  nerve  which 
conveys  filaments  of  the  fourth  and  fifth  lumbar  and  the  first  sacral  nerve,  and  the 
outer  area  by  the  first  and  second  sacral  nerves  through  the  external  plantar  nerve. 

The  inner  side  of  the  foot  is  supplied  l\v  the  third  and  fourth  lumbar  nerves 
through  the  long  saphenous  nerve,  and  the  outer  side  b}'  the  first  and  second  sacral 
nerves  through  the  external  saphenous  nerve  (fig.  469b). 

The  skin  of  the  scrotum  and  penis  is  supplied  by  the  first  lumbar  nerve  through 
the  ilio-inguinal  nerves,  and  the  second  and  third  sacral  nerves  through  the  per- 
ineal and  dorsal  penile  branches  of  the  pudic  nerves  (fig.  469b). 


SYJIPATHETIC  NERVES 


The  sympathetic  nerves  were  formerly  supposed  to  be  a  separate  system, 
linked,  it  is  true,  to  the  cerebro-spinal  system  by  numerous  communications,  yet 
possessing,  in  their  ganglia,  a  certain  governing  power  independent  of  the  cerebro- 
spinal axis.  It  is  now  very  generally  admitted  that  the  sympathetic  nerves  are 
merely  the  visceral  branches  of  the  spinal  nerves,  but  they  differ  from  the  somatic 
nerves  in  the  following  respects:  (a)  in  the  individual  fibres  being  of  smaller  calibre 
than  the  somatic  nerve-fibres;  (h)  in  the  great  preponderance  of  non-medullated 
fibres;  (c)  in  the  fibres  being  interrupted  in  the  nerve-cells,  which  are  contained  in 
a  chain  of  ganglia  which  is  called  the  gangliated  cord  of  the  sympathetic,  and  often 
also  interrupted  in  secondary  and  tertiary  ganglia,  of  which  the  semilunar  ganglia 
and  the  nerve-cells  in  the  plexuses  of  Auerbach  and  Meissner  are  examples;  and 
(d)  in  the  tendency  that  these  nerves  show  to  form  extensive  and  closely-meshed 
plexuses. 

The  somatic  nerves  are  the  nerves  Avhich  supply  the  bodj^-wall  as  distinguished 
from  the  viscera.     They  have  been  described  above  as  the  cranial  and  spinal  nerves. 

Certain  visceral  nerves — for  example,  the  visceral  branches  of  the  third  and  fourth  sacral 
nerves — do  not  join  the  gangliated  cord.  While  the  sj'mpathetic  nerves,  taken  as  a  wliole,  can 
no  lunger  be  regarded  as  a  separate  sj'stem,  certain  ganglia  connected  with  the  syuii>athetic  are 
capable  of  automatic  action  ;  for  example,  the  ganglia  in  the  heart  and  in  the  intestinal  walls. 

The  sympathetic  system,  as  usually  described,  consists  of  (a)  a  pair  of  gangliated 
cords  Avhich  are  placed  on  the  front  and  sides  of  the  vertebral  column;  and  (6) 
three  great  prevertebral  plexuses  containing  many  ganglia;  and  (e)  numerous 
terminal  ganglion  cells  situated  close  to  or  within  the  various  organs  and  vessels. 
One  of  the  plexuses,  the  cardiac  plexus,  is  contained  in  the  thoracic  cavity.  The 
other  two,  which  are  termed  the  solar  and  hypogastric  plexuses,  are  placed  in  the 
abdominal  cavity.     The  gangliated  cords  will  be  first  described. 


.   GANGLIATED  CORDS  OF  THE  SYMPATHETIC 

The  gangliated  cords  of  the  sympathetic  consist  of  a  series  of  ganglia  united 
together  by  intervening  cords.     These  ganglia  are  of  a  reddish-grey  colour,  soft  in] 
consistence,  but  enclosed  in  tolerably  firm  investments  of  connective  tissue.     The 
nerve-cords  uniting  them  are  pearly  grey  in  colour.     Morphologically  speaking, 
there  should  l)e  thirty-one  pairs  of  ganglia,  that  is  to  say,  a  j)air  corresponding  to 


CERVICAL   GANGLIA  827 

each  pair  of  sjdnal  nerves.  We  find,  lioweve^r,  owing  to  the  cohesion  of  certain 
gangha,  i)articularly  in  the  cervical  region,  that  the  number  is  reduced  to  from 
twenty  to  twenty-three  })airs.  In  the  tlioracic  region  the  arrangement  is  the  most 
ty])ical,  twelve  j)airs  of  ganglia  corresponding  to  the  twelve  thoracic  nerves  being 
frequentlv  present.  In  the  thoracic  region,  also,  the  arrangement  of  the  rami 
communicantes  is  most  easily  studied. 

Each  thoracic  ganglion  is  connected  with  the  anterior  primary  division  of  the 
corresponding  spinal  nerve  by  two  rami  communicantes  (fig.  470a),  a  white  and 
a  grey.  The  white  ramus  consists  of  small  medullated  liljres  which  leave  the 
spinal  cord  by  the  anterior  nerve  root  and  pass  to  the  ganglion.  Some  of  the 
fibres  of  the  white  ramus  pass  through  the  ganglion  and  leave  the  chain  directly, 
or  more  generally  after  running  upwards  or  downwards  for  some  distance  within 
it,  by  the  rami  efFerentes  (fig.  470a). 

The  rami  cf^'crcntes  pass  to  the  prevertebral  i)lexuses  where  they  may  end  in 
arborizations  round  the  cells  of  the  ganglia,  or  i)assing  through  these  ganglionic 
]»lexuses  they  end  round  the  cells  of  the  terminal  ganglia,  which  are  situated  either 
close  to  or  within  the  walls  of  the  vessels  and  organs.  Other  fibres  of  the  white 
rami  aflferentcs  terminate  round  the  cells  of  the  vertebral  ganglia  (ganglia  of  the 
chain). 

From  the  cells  of  the  various  ganglia,  vertebral,  ^prevertebral,  and  terminal, 
non-medullated  fibres  arise  which  end  in  the  walls  of  the  viscera,  vessels,  and 
glands.  ^lany  of  the  non-medullated  fibres  which  issue  from  the  thoracic  verteljral 
ganglia  form  the  grey  rami  (fig,  470a).  They  pass  to  the  spinal  nerves.  Some  of 
tliem  turn  inwards  along  the  posterior  nerve  roots  to  the  membranes  of  the  spinal 
cord  and  the  walls  of  the  spinal  canal;  others  travel  peripherally,  with  the  branches 
of  the  nerve;  they  terminate  in  the  blood  vessels,  hair  muscles,  and  skin  glands. 
The  remaining  non-medullated  fibres,  wdiich  issue  from  the  vertebral  ganglia,  leave 
in  the  rami  efferentes  and  pass  through  the  prevertebral  plexuses  to  their  termina- 
tions (fig.  470a). 

In  addition  to  the  fibres  above  mentioned,  it  is  possible  that  there  are  also 
afferent  (sensory)  fil)res  passing  from  the  viscera,  glands,  and  vessels  through  the 
sympathetic  ganglia  to  the  posterior  nerve  roots  and  thence  to  the  spinal  cord. 

Cranial  portion  of  the  sympathetic. — The  small  sporadic  ganglia  (ophthalmic,  spheno-jiala- 
tine,  otic,  and  submaxillary),  which  have  already  been  described  in  connection  with  the  tri- 
geminal neiTC,  are  regarded  by  some  anatomists  as  representing  a  cranial  portion  of  the  gangliated 
cord,  and  sympathetic  fibres  are  undoubtedly  given  off  from  the  ninth,  tenth,  and  eleventh  cranial 
nerves. 

CERVICAL  PORTION  OF  THE  GANGLIATED  CORD 

The  cervical  portion  of  the  gangliated  cord  consists  of  three  ganglia  united 
by  intervening  nerve-cords.  Of  these  the  superior  cervical  ganglion  is  the  largest, 
and  probal)ly  represents  four  coalesced  ganglia;  the  middle  cervical  ganglion  is  the 
smallest,  and  represents  two  ganglia;  the  inferior,  intermediate  in  size,  is  probably 
formed  by  the  union  of  two  ganglia.  The  cord  takes  a  vertical  course  down  the 
neck,  and  is  in  contact  posteriorly  with  the  prevertebral  layer  of  the  cervical  fascia. 
Behind  this  fascia  it  corresponds  to  the  rectus  capitis  anticus  major  above,  and  the 
longus  colli  below.  These  muscles  and  the  prevertebral  fascia  intervene  between 
tlie  cord  and  the  transverse  processes  of  the  cervical  vertebrcT.  The  internal  carotid 
above,  and  the  common  carotid  artery  below,  are  j)laced  in  front  of  the  gangliated 
cord,  and  the  pneumogastric  nerve  is  external  to  it. 

Superior  Cervical  Ganglion 

The  superior  cervical  ganglion  is  a  fusiform  body,  about  one  inch  to  an  inch 
and  a  half  in  length  (2.5  to  o.75  cm.).  It  corresponds  to  the  transverse  processes 
of  the  second  and  third  (and  sometimes  the  first)  cervical  vertebra\  Al)Ove,  it  is 
continued  into  a  stout  trunk  which  is  called  the  ascending  branch.  Below,  it  ends 
in  a  cord  which  passes  downwards  to  join  the  middle  cervical  ganglion.  It  is  con- 
nected to  the  anterior  primary  divisions   of  the  four  upi)er  cervical   nerves  by  as 


828  THE  NERVOUS  SYSTEM 

many  grey  rami  communicantes.  Occasionally  the  number  of  rami  is  increased 
to  five  or  six.  Th.^  ganglion  is  occasionally  constricted  at  intervals — these  constric- 
tions affording  an  indication  of  the  individual  ganglia  ))y  the  coalescence  of  which 
the  sujM'rior  cervical  ganglion  is  formed. 

Branches. — The  branches  of  the  superior  cervical  ganglion  are  the  ascending 
branch;  branches  which  follow  the  distrit)Ution  of  the  external  carotid  artery  (nervi 
molles);  branches  of  communication  to  cranial  nerves;  pharyngeal  nerves;  the 
superior  cervical  cardiac  nerve,  and  branches  to  the  upper  cervical  vertebrae  and 
their  ligaments. 

1.  The  ascending  branch  enters  the  carotid  canal  in  the  temporal  bone  and 
divides  into  a  larger  external  l^ranch  which  forms  the  carotid  plexus,  and  a  smaller 
internal  branch  which  ends  in  the  cavernous  plexus.  These  plexuses  connnunicate 
frequently  with  one  another  around  the  artery,  and  may  be  regarded  as  different 
parts  of  the  same  plexus  rather  than  distinct  plexuses. 

The  carotid  plexus  is  formed  by  repeatedly  communicating  branches,  which 
follow  the  internal  carotid  artery  in  the  carotid  canal,  keeping  close  to  the  outer 
side  of  that  vessel.  The  following  nerves  arise  from  it:  tympanic;  great  deep 
petrosal;  and  a  communicating  branch  to  the  sixth  nerve. 

(a)  The  tympanic  branch  (small  deep  petrosal)  enters  a  minute  canal 
(carotico-tympanic  canal)  in  the  temporal  bone,  by  which  it  is  conducted  to  the 
tympanic  plexus  (page  768). 

(6)  The  great  deep  petrosal  nerve  passes  forwards  and  inwards  through  the 
cartilage  which  occupies  the  foramen  lacerum  medium,  and  unites  with  the  great 
superficial  petrosal  to  form  the  Vidian  ncrvo  (]>age  755). 

(c)  The  branches  to  the  Gasserian  ganglion  are  given  off  from  the  plexus  as 
it  emerges  from  the  carotid  canal. 

(d)  The  branches  to  the  sixth  nerve  are  very  distinct,  and  can  be  easily  seen 
when  the  cavernous  sinus  is  opened.  They  join  the  abducens  as  it  is  crossing  the 
outer  side  of  the  internal  carotid  artery. 

The  cavernous  plexus  is  placed  on  the  inner  side  of  the  internal  carotid  artery 
near  the  pituitary  body.  Its  terminal  offsets  follow  the  ophthalmic  and  cerebral 
liranches  of  the  internal  carotid  artery.  In  addition  to  these  it  gives  off  the  fol- 
lowing branches : — 

(a)  Communicating  branches  to  the  third,  fourth,  and  ophthalmic  divi- 
sion of  the  fifth  cranial  nerves. 

(6)  The  sympathetic  root  of  the  lenticular  ganglion.  This  root  is  usually 
in  the  form  of  several  fine  filaments  which  enter  the  ganglion  at  its  posterior 
border. 

(c)  Two  or  three  fine  twigs  enter  the  pituitary  body. 

2.  The  nervi  molles  are  given  off  from  the  anterior  part  of  the  superior  cervical 
ganglion,  and  accompany  the  branches  of  the  external  carotid  arter}-.  yse  have 
already  noted,  in  the  description  of  the  fifth  cranial  nerve,  that  the  otic  and  sul>- 
maxillary  ganglia  receive  their  sympathetic  roots  from  plexuses  of  the  sympathetic 
Avhich  reach  them  via  the  middle  meningeal  and  facial  arteries  respectively.  In 
addition  to  these  roots  to  the  ganglia,  vaso-motor  branches,  and  twigs  which  enter 
the  parotid  gland,  are  given  off.  Other  twigs,  taking  a  downward  direction,  enter 
the  intercarotic  and  thyroid  bodies;  the  latter  follow  the  course  of  the  superior 
thyroid  vessels. 

3.  Communicating  branches  to  cranial  nerves. — Branches  of  communication 
arise  directly  from  the  gangliDU  to  join  tlie  vagus,  glosso-pharyngeal,  and  hypo- 
glossal nerves.  Communications  are  effected  Avitli  the  ganglia  of  the  root  and  trunk 
of  the  vagus,  and  with  the  jugular  and  petrous  ganglia  of  the  glosso-pharyngeal. 

4.  The  pharyngeal  branches,  four  or  five  in  number,  pass  downwards  and 
inwards  l)ehind  the  external  and  internal  carotid  arteries  to  join  the  pharyngeal 
plexus. 

5.  The  superior  cervical  cardiac  nerve  arises  from  the  lower  part  of  the 
ganglion,  or  occasionally  from  the  nerve-cord  between  the  superior  and  middle 
cervical  ganglia.  The  nerves  of  the  two  sides  run  a  corresponding  course  in  the 
neck,  but  differ  in  their  arrangement  in  the  thorax.  In  the  neck,  each  nerve  is 
directed  downwards  on  the  prevertebral  fascia  in  front  of  the  longus  colli  muscle. 


CER I ICA  L    a  A  .\(r  L I  A 


829 


and  communicates  with  the  iipjxT  cervical  cardiac  hrancli  of  the  pneumogastric 
Avith  tlie  middle  cardiac  nerve  of  the  sympathetic,  and  with  the  external  laryngeal 
and  recurrent  larvngeal  nerves. 


Fig.  470.— The  Cervical  Portion  of  the  Sympathetic  and  the  Distribution  of 
THE  Pneumogastric  Nerve,  viewed  from  behind.     (Kiause.) 

Stylo-hyoid  Ligamentum  pharyngeum 

\i 

Posterior  belly  of 
digastric 


Steruo-mastoid 


HectuB  capitis 
anticus  major 

Stylo-pharyngeue 

Stylo-glossus 

Internal  pterygoid 

SUPERIOR 
CERVICAL 
GASGLlOy 

Middle  constrictor 

Common  carotid 
artery 

Inferior  constrictor 

GAXGLIOX 
THYROIDECM 
(VARIETY) 

THYROID  GLAND 


Inferior  thyroid 
artery 
Subclavian  artery 


RECURREST 
LARYNGEAL 
NER  VE 


Thoracic  aorta 


CruE  of  diaphragm 


Internal  carotid 

artery 
RIGHT 
SYMPATHETIC 

Occipital  artery 

Posterior  belly  of 
digastric 


DESCEyDEXS 
HYPOGLOSSI 

Common  carotid 
itrtery 

Sterno-mastoid 


TWIG  OF 
RECURRENT 
LARYNGEAL  TO 
PHARYNGEAL 
PLEXUS 

Thyroid  axis 

INFERIOR 
CERVICAL 
GANGLION 

RECURRENT 
LARYNGEAL 

PLEXUS  GUL^ 


L_  RIGHT 

PNEUMOGASTRIC 


On  the  right  side  the  nerve  passes  in  front  of  (occasionally  behinfl)  the  sub- 
clavian artery,  and  is  directed  along  the  innominate  artery  to  reach  the  bifurcation 
of  the  trachea,  in  front  of  which  it  terminates  in  the  deep  cardiac  })lexus. 


830  THE  XERVOUS  SYSTEM 

On  the  left  side  the  nerve  is  conducted  into  the  thorax  in  front  of  the  common 
carotid  artery,  and  crosses  in  front  (or  rather  to  tlie  left  side)  of  the  arch  of  the 
aorta  in  the  interval  hetween  the  trunk  of  the  vagus  and  its  inferior  cervical  cardiac 
branch,  and  ends  in  the  superficial  cardiac  plexus. 

Middle  Cervical  Ganglion 

The  middle  cervical  ganglion  is  a  small,  somewhat  triangular,  ganglionic 
thickening  of  the  cord  of  the  sympathetic.  It  is  situated  at  the  point  where  the  cord 
crosses  the  inferior  thyrcnd  artery  at  the  level  of  the  sixth  cervical  vertebra.  It 
gives  grey  rami  communicantes  to  the  fifth  and  sixth  cervical  nerves.  It  is 
connectecl  below  to  the  inferior  cervical  ganglion  by  the  main  cord  of  the  s^'mpa- 
thetic,  which  passes  behind  the  subclavian  artery,  and  l)y  one  or  more  nerve-cords 
which  pass  in  front  of  that  vessel,  forming  the  ansa  Vieussenii.  The  middle 
cervical  ganglion  gives  off  iDranches  to  the  thyroid  l;)ody  and  the  middle  cardiac 
nerve. 

The  branches  to  the  thyroid  body  communicate  with  the  superior  cardiac 
nerve,  and  proceed  to  the  gland,  following  the  branches  of  the  inferior  thyroid 
artery. 

The  middle  cardiac  nerve  enters  the  thorax,  passing  sometimes  in  front  of  tin- 
subclavian  artery,  and  sometimes  l^ehind  that  vessel.  It  communicates  in  the  neck 
'with  the  upper  cardiac  nerve,  and  in  the  thorax  with  the  recurrent  laryngeal.  It 
terminates  in  the  deep  cardiac  plexus.  On  the  left  side  this  nerve  passes  down 
between  the  left  carotid  and  subclavian  arteries. 

Inferior   Cervical  Ganglion 

The  inferior  cervical  ganglion  is  larger  than  the  middle  ganglion,  and  is  con- 
nected by  sh(n*t  grey  rami  communicantes  to  the  seventh  and  eighth  cervical 
nerves.  It  is  irregular  in  form  and  is  deeply  placed,  being  lodged  in  a  depression 
between  the  neck  of  the  first  rib  and  the  transverse  process  of  the  seventh  cervical 
vertebra.  In  this  situation  it  is  concealed  by  the  vertebral  artery,  the  vessel  being 
placed  in  front  of  the  ganglion.  It  is  united  to  the  first  thoracic  ganglion  by  one 
or  two  stout  cords  and  often  by  a  band  of  ganglionic  substance.  It  gives  off 
branches  to  the  vertebral  artery  and  the  inferior  cardiac  nerve. 

The  branches  to  the  vertebral  artery  are  of  considerable  size  and  accompany 
the  vessel  into  the  arterio- vertebral  foramina  in  the  transverse  processes.  The 
plexus  thus  formed  is  continued  on  the  vertebral  and  basilar  to  the  cerebral 
arteries. 

The  inferior  cardiac  nerve  connnunicates  with  the  middle  cardiac  and  recurrent 
laryngeal,  and  passes  along  the  side  of  the  trachea  to  join  the  deep  cardiac  plexus. 
It  occasionally  arises  from  the  first  dorsal  ganglion. 

The  majority,  if  not  all,  of  the  medullated  fibres  of  the  cervical  part  of  the 
sympathetic  cord  enter  it  from  the  dorsal  jiart,  to  which  they  pass  by  the  Avhite  rami 
from  the  upper  dorsal  ners'es.  The  destination  of  many  of  these  fibres  is  unknown, 
y)ut  some  terminate  in  ramifications  round  the  cells  of  the  upper  cervical  ganglion 
and  others  in  a  similar  manner  round  the  cells  of  the  middle  and  lower  ganglia. 
The  fiV)res  which  terminate  in  the  upper  ganglion  are  the  vaso-motor  fibres  of  the 
head,  the  secretory  fil^res  of  the  submaxillary  glands,  the  dilator  fibres  of  the  pupil, 
the  motor  fibres  for  the  smooth  muscle  of  the  eyelids  and  orbit,  and  the  pilo-motor 
fibres  (to  the  muscles  of  the  hairs)  of  the  face  and  neck.  Those  which  terminate 
in  the  middle  and  lower  cervical  ganglia  are  the  cardiac  accelerator  fibres,  and 
possibly  some  of  the  secretory  fibres  of  the  sweat  glands  of  the  upjier  extremity. 


THORACIC  PORTION  OF  THE  GANGLIATED  CORD 

The  thoracic  portion  of  the  gangliated  cord  is  represented  by  a  chain  of 
twelve  pairs  of  ganglia.  In  a  few  cases,  on  account  of  the  coalescence  of  some  of 
the  members  of  the  series,  the  number  may  be  reduced  to  eleven  or  ten  pairs.     The 


SPLANCHNIC  NERVES  831 

upper  ten  ganglia  lie  upon  the  heads  of  the  corresponding  ril)S,  ininiediatdy  under 
cover  of  the  jdeura.  The  lower  two  are  i)laced  further  forwards,  and  lie  on  the 
sides  of  the  bodies  of  the  eleventh  and  twelfth  thoracic  vertebra?  between  the  bones 
and  the  diaphragm.  The  cord  is  continuous  above  with  the  cervical  part  of  the 
cord,  the  first  thoracic  ganglion  being  sometimes  united  across  the  neck  of  the  first 
rib  with  the  inferior  cervical  ganglion.  Below,  the  cord  enters  the  abdominal 
cavity  In-  i»assing  lx4nnd  the  ligamentum  arcuatum  internum  to  become  continuous 
with  the  lunil)ar  part  of  the  cord.  The  first  thoracic  ganglion  (ganglion  stella- 
tum)  is  larger  than  the  others,  and  is  of  an  irregular  form.  The  remainder  of  the 
series  are  triangular  in  outline,  two  of  the  angles  being  continued  into  the  inter- 
ganglionic  part  of  the  cord,  and  the  other  into  the  rami  communicantes.  On  some 
of  the  loAver  ganglia  a  fourth  angle  makes  its  appearance,  and  is  continued  into  one 
of  the  roots  of  the  splanchnic  nerves. 

Branches, — The  l^ranches  are  classified  into  external  and  internal.  The 
external  branches  are  the  rami  communicantes.  A  grey  and  a  white  ramus 
(.•onnnunicans  connects  each  ganglion  with  the  corresponding  thoracic  nerve.  The 
internal  branches  are  the  rand  efferentcs,  those  of  the  upper  four  ganglia  are 
distriluited  chiefiy  to  the  aorta  and  lungs.  The  internal  branches  of  the  lower 
eight  ganglia  form  three  splanchnic  nerves  which  are  distributed  to  tlie  alidominal 
viscera. 

Internal  branches. — Upper  series. — From  the  upper  four  or  five  ganglia  fine 
twigs  arise  Avhich  are  distributed  to  the  thoracic  aorta,  mediastinum,  lungs,  verte- 
brae, and  ligaments. 

Internal  branches, — Lower  series. — These  branches,  although  arising  in  the 
thorax,  are  destined  for  the  abdominal  viscera.  The  branches  from  the  fifth  to  the 
ninth  ganglia  unite  to  form  the  great  splanchnic  nerve;  the  lesser  splanchnic  nerve 
arises  by  two  roots  from  the  tenth  and  eleventh  ganglia,  while  the  internal  Ijranch 
of  the  twelfth  ganglion  forms  the  smallest  splanchnic  nerve. 

GREAT  SPLANCHNIC  NERVE. — The  five  roots  of  this  nerve  run  downwards 
and  inwards,  Ix'tween  the  ])L'ura  and  the  bodies  of  the  thoracic  vertebrae,  and  unite 
within  the  posterior  mediastinum  to  form  a  trunk  of  considerable  size.  The  nerve 
thus  fomied  pierces  the  crus  of  the  diaphragm,  and  enters  the  semilunar  ganglion 
of  its  own  side. 

The  great  splanchnic  nen'e  is  whitish  in  colour,  owing  to  a  number  of  luedullated  fibres 
iitering  into  its  composition.     Occasionally  a  small  ganglion  (splanchnic  ganglion)  is  developed 
upon  it  in  the  mediastinum.     This  ganglion  is  constant  on  the  right  side.     (Cunningham.) 

The  LESSER  SPLANCHNIC  NERVE  runs  a  shnilar  course  to  the  great  splanch- 
nic, but  at  a  lower  le-vel.  It  ]>ierees  the  crus  of  the  diapln-agm,  or  passes 
through  the  internal  arcuate  ligament,  and  enters  the  solar  and  renal  plexuses. 

The  SMALLEST  SPLANCHNIC  NERVE  passes  behind  the  internal  arcuate  liga- 
ment or  through  the  crus  of  the  diaphragm  and  enters  the  renal  plexus. 

The  majority  of  the  sympathetic  fibres  which  pass  from  the  central  nervous 
system  enter  the  dorsal  part  of  the  sympathetic  chain;  some  end  there,  in  ramifi- 
cations around  the  cells  of  the  ganglia,  and  others  merely  pass  through  on  their 
way  to  more  distant  terminations.  V\  ith  regard  to  those  which  terminate  in  the 
ganglia  it  has  been  shown  that  in  the  dog  and  cat  many  end  in  the  ganglion  stel- 
latum.  which  corresponds  with  the  last  cer\'ical  and  the  upper  three  or  four  dorsal 
ganglia  in  man:  amongst  these  are  the  secretory  fibres  to  the  sweat  glands  of  the 
U))per  limb  which  emerge  from  the  spinal  cord  by  the  dorsal  nerves  from  the  sixth 
to  the  ninth,  and,  in  the  dog,  vaso-constrictor  fibres  of  the  pulmonary  blood-vessels 
which  leave  the  spinal  cord  by  the  second  to  the  seventh  dorsal  nerves.  Other 
fibres  which  terminate  around  the  thoracic  ganglion  cells  in  the  dog  and  the  cat  are 
the  vaso-con.strictor  fibres  of  the  upper  limbs  and  some  of  the  vaso-constrictor  fibres 
of  the  lower  liml). 

Of  the  fibres  which  traverse  the  dorsal  part  of  the  sympathetic  cord,  to  gain 
more  distant  terminations,  some  ascend  to  the  cervical  region  (p.  830),  others 
descend  to  the  lumbar  region,  and  many  pass  by  the  rami  efferentes  to  the  splanch- 
nic nerves. 

Amongst  those  which  descend  to  the  lumbar  region  are  pilo-motor  fibres,  vaso- 


832 


THE  NERVOUS  SYSTEM 


motor  fibres,  and  secretory  fibres  to  the  lower  limb,  some  vaso-constrictor  fibres  to 
the  abdominal  blood-vessels,  motor  fibres  to  the  circular,  and  inhibitory  fibres  to 
the  longitudinal  muscle  of  the  rectum:  the  latter  enter  the  sympathetic  cord  by  the 
lower  dorsal  nerves,  thev  pass  by  the  lumbar  efferentes  to  the  aortic  plexus  and 
terminate  round  the  cells  of  the  inferior  mesenteric  ganglion. 

The  fibres  which  pass  through  the  dorsal  ganglia  to  the  splanchnic  nerves  are 


GANGLION  OF 
POSTERIOR 
NERVE  ROOT 

POSTERIOR 
PRIMARY 
DIVISION 


ANTERIOR 
PRIMARY 
DIVISION 


VASO-MOTOR,  J. 

PILO-MOTOR  AND  — ^• 
SECRETORY  FIBRES 


Fig.  4 70 a. 
VASO-MOTOR  RECURRENT  NERVE 


ANTERIOR  NERVE  ROOT 


SY2IPA  TIIETIC  CORD 


-  SYMPATHETIC  GANGLION 


RAMUS  EFFERENS 


SYMPATHETIC  CORD 


WHITE  RAMUS 
COMMUNICANS 


GREY  RAMUS 
COMMUNICANS 


SYMPA  THETIC  CORD 


RAMUS  EFFERENS 


PERIPHE- 
RAL 

GAN- 
GLION 


PERIPHERAL  ORGAN 


mainly  vaso-motor  fibres  to  the  abdominal  blood-vessels,  the  majority  of  them 
probably  terminate  around  the  cells  of  the  ganglia  in  the  solar  plexus,  but  those 
for  the  renal  blood-vessels  are  said  to  end  in  the  renal  ganglia.  In  addition  to  all 
the  above-mentioned  fibres  there  are,  in  the  dorsal  part  of  the  sympathetic  cord 
afferent  (splanchnic  sensory)  fibres,  passing  towards  the  posterior  roots  of  the 
dorsal  nerves. 


LUMBAR   AXD  SACRAL   PORTIOXS  OF  GAXGLLATED   CORD     833 


LUMBAR  PORTION  OF  THE  GANGLIATED  CORD 

TIk'  lumbar  part  of  the  gangliated  cord  consists  of  a  chain  of  ganglia,  usually 
four  in  number,  which  are  placed  in  front  of  the  bodies  of  the  vertel)ri;e,  close  to 
the  anterior  border  of  the  psoas  muscle.  On  the  right  side  the  cord  is  covered  by 
the  vena  cava,  and  on  the  left  side  it  is  behind  and  external  to  the  aorta.  Above, 
it  is  continuous  with  the  thoracic  part  of  the  cord.  Below,  it  is  continued  into  the 
sacral  i)art  of  the  cord  by  passing  behind  the  common  iliac  vessels.  The  rami 
communicantes  are  longer  in  tliis  part  of  the  gangliated  cord  than  in  any  other 
region  of  the  Ijody.  Usually  two  rami  pass  from  each  ganglion  backwards  through 
the  tibrous  arches  from  which  the  psoas  takes  origin,  and  join  the  lumbar  ners'es  in 
a  somewhat  variable  manner.  Frequently  there  is  only  one  ramus  communicans 
and  sometimes  the  number  of  rami  is  increased.  The  rami  communicantes  are 
attoiiipaiiied  by  the  lumbar  arteries. 

Branches. ^-Some  of  the  branches  join  the  aortic  plexus;  others  pass  in  front 
of  the  common  iliac  arteries  to  form  the  hypogastric  plexus,  and  some  terminate  in 
the  vertebra?  and  ligaments. 

The  lumbar  j)ortion  of  the  sympathetic  cord  contains  a  number  of  fibres  already 
described  (p.  881)  which  have  descended  to  it  from  the  dorsal  region,  but  it  also 
obtains  others  by  the  white  rami  from  the  lumbar  ners'es;  amongst  the  latter  are 
additional  vaso-constrictor  fibres  for  the  renal  blood-vessels,  secretor}-  fibres  for  the 
glands  of  the  hind  limb,  constrictor  fibres  for  the  blood-vessels  of  the  lower 
extremity,  ])ilo-motor  fibres,  motor  fibres  for  the  circular,  and  inhibitory  fibres  for 
tile  longitudinal  nuiscle  of  the  rectum,  motor  fibres  for  the  uterus,  vas  deferens  and 
round  ligament,  motor  fibres  for  the  circular  and  inhibitory  fibres  for  the  longi- 
tudinal fibres  of  the  IJadder,  and  vaso-motor  fibres  for  the  penis. 

The  motor  filjres  for  the  bladder  and  uterus  leave  the  lumbar  sympathetic  cord 
by  the  rami  efferentes  and  pass  by  the  aortic  plexus  to  the  inferior  mesenteric 
ganglion.  The  motor  fibres  to  the  vas  deferens  and  spermatic  cord  enter  the  genito- 
crural  nerve.  Of  the  vaso-motor  fibres  of  the  penis  some  of  the  constrictor  fibres 
]»ass  down  to  the  sacral  portion  of  the  sympathetic  cord  where  they  ramify  round 
the  cells  of  the  sacral  ganglia,  the  impulses  they  carry  being  transmitted  by  the 
grey  rami  of  the  sacral  ganglia  to  the  pudic  ner%-e.  Others  travel  by  the  inferior 
mesenteric  ganglion,  and  the  latter  are  accompanied  by  the  vaso-dilator  fibres  of 
the  penis. 

SACRAL  PORTION  OF  THE  GANGLIATED  CORD 

Tlie  sacral  part  of  the  gangliated  cord  consists  of  a  chain  of  four  small 
ganglia,  which  is  placed  in  front  of  the  sacrum  internal  to  the  anterior  sacral  fora- 
mina. From  the  lowest  of  these  ganglia,  branches  proceed  on  each  side  and 
converge  to  a  median  ganglion  (ganglion  impar)  which  is  situated  in  front  of  the 
last  i>iece  of  the  sacrum  or  the  first  piece  of  the  coccyx.  The  sacral  ganglia  are 
connected  in  a  somewhat  irregular  manner  to  the  sacral  nerves  by  short  grey 
rami  communicantes. 

Branches. — From  the  upper  sacral  ganglia  branches  are  given  off  which  join 
the  i»elvie  i>lexuses.  Others  pass  across  the  sacrum  to  join  corresponding  branches 
from  the  cord  of  the  opposite  side.  From  the  ganglion  impar  twigs  pass  down- 
wards to  enter  the  coccygeal  body. 

There  are  no  white  rami  from  the  sacral  ner\'es  to  the  sacral  sympathetic  ganglia, 
therefore  all  the  medullated  fibres  contained  in  the  sacral  sympathetic  cord  have 
descended  to  it  from  the  dorsal  and  lumbar  regions.  They  include  some  vaso- 
constrictor and  secretory  fibres  for  the  hind  limb,  pilo-motor  fibres  for  the  posterior 
part  of  the  body,  including,  in  the  cat,  the  tail,  and  some  vaso-constrictor  fibres  of 
the  penis. 

The  white  rami  of  the  sacral  nerves  are  represented  by  their  visceral  branches, 
the  so-called  pelvic  splanchnics.  These  contain  motor  fiV)res  to  the  longitudinal 
muscle  of  the  bladder,  motor  fibres  for  the  longitudinal  and  inhibitory  fibres  for 
the  circular  muscle  of  the  rectum,  motor  fibres  for  the  utt^us,  secretory  fibres  for 
the  prostate  gland,  and  vaso-dilator  fibres  for  the  penis. 
53 


8;M  the  nervous  SYSTEM 


THE  GPvEAT  PREVERTEBRAL  PLEXUSES 

Tho  great  prevertebral  plexuses,  as  we  have  already  noticed,  are  the  cardiac, 
solar,  anil  hv})()gastric.  They  are  formed  mainly  by  branches  derived  from  the 
gangliated  cords,  but  also  receive  fibres  from  the  cerebro-s])inal  nerves;  thus  the 
cardiac  plexus  and  solar  plexuses  are  joined  by  branches  of  the  iineumo,2;astric,  and 
the  hyjiogastric  plexus  is  joined  l)y  branches  of  the  third  and  fourth  and  sometimes 
the  second  sacral  nerves. 

CARDIAC  PLEXUS 

As  already  noted,  each  pneumogastric  nerve  gives  off  two  or  three  cervical 
cardiac  branches,  a  thoracic  cardiac  branch,  and  additional  branches  may  s])ring 
from  the  recurrent  laryngeal  nerve.  There  are  also  three  cardiac  nerves  which 
arise  from  the  cervical  sympathetic  cord  on  each  side.  These  nerves  all  proceed 
to  the  cardiac  plexus,  but  their  course  and  arrangement  is  extremely  varialilc. 
It  is  very  common  to  find  the  upper  cervical  cardiac  branches  of  the  vagus  and 
sympathetic  uniting  to  form  a  common  trunk;  in  other  cases  the  nerves  l)ranch 
and  communicate  with  one  another  in  a  plexiform  manner.  The  cardiac  plexus, 
although  forming  a  continuous  network  of  nerves,  is  for  convenience  divided  into 
a  superficial  and  a  deep  plexus.  The  superficial  plexus  is  situated  immediately 
l)elow  the  arch  of  the  aorta,  internal  to  the  ligamentum  ductus  arteriosus;  it 
receives  the  left  superior  cardiac  nerve  of  the  sympathetic  and  the  left  inferior 
cervical  cardiac  branch  of  the  pneumogastric.  The  deep  cardiac  plexus  is  placed 
in  front  of  the  ])ifurcation  of  the  trachea  between  tliat  structure  and  the  aortic 
arch;  it  receives  all  the  other  cardiac  nerves. 

Superficial  cardiac  plexus. — The  superior  cardiac  branch  of  the  sympathetic 
and  the  inferior  cervical  cardiac  branch  of  the  vagus  cross  the  aortic  arch  on  its  left 
side,  being  placed  between  the  artery  and  the  left  pleura.  The  nerves  then  enter 
the  interval  between  the  aortic  arch  and  the  bifurcation  of  the  pulmonary  artery, 
Avhere  they  communicate  with  the  deep  cardiac  plexus.  A  small  ganglion  (the 
carfliac  ganglion  of  M^risberg)  is  usually  developed  at  the  point  of  communication. 
Branches  are  furnished  to  the  right  coronary  plexus  and  also  to  the  left  lung.  The 
latter  Ijranches  join  the  anterior  pulmonary  plexus. 

Deep  cardiac  plexus. — The  deep  cardiac  plexus  receives  all  the  right  cardiac 
nerves,  and  also  the  cardiac  nerves  of  the  left  side,  with  the  excejition  of  the 
superior  cervical  cardiac  of  the  sympathetic  and  the  inferior  cervical  cardiac  of 
the  vagus.  The  plexus  is  placed  in  front  of  the  l^ifurcation  of  the  trachea,  and 
gives  off  the  following  branches: — (a)  Branches  to  the  anterior  pulmonary  plexuses 
of  both  sides;  (6)  the  left  coronar}^  plexus;  (c)  branches  to  the  right  auricle; 
(d  )  communicating  branches  to  the  superficial  cardiac  plexus;  and  (e)  branches  to 
the  right  coronary  plexus. 

Right  coronary  plexus. — This  plexus  is  formed  by  branches  from  both  the 
superficial  and  deep  cardiac  plexuses.  It  follows  the  branches  of  the  right  coronary 
artery  for  a  certain  distance,  beyond  Avhich  the  nerves  diverge  from  the  arteries,  and 
run  between  the  pericardium  and  the  muscular  sulistance  of  the  heart.  Finally 
they  enter  the  muscular  substance. 

Left  coronary  plexus. — This  plexus  is  larger  than  the  riglit.  It  arises  from 
the  deep  cardiac  plexus,  passes  forwards  between  the  left  auricular  appendix  and 
the  pulmonary  artery,  and  accompanies  the  branches  of  the  left  coronary  artery. 

The  auricles  are  supplied  by  the  lower,  and  the  ventricles,  pulmonary  artery 
and  aorta  l)y  the  upper  cardiac  nerves. 

The  cardiac  plexuses  and  the  network  of  nervous  structures  in  the  walls  of  the 
auricles  are  the  remains  of  the  i)rimitive  jilexuses  found  in  the  endiryo  whicli  are 
called  the  bulbar,  the  intermediate,  and  tlie  atrial  plexuses,  terms  which  sufficiently 
indicate  their  relative  positions.  The  Indbar  jilexus  gives  oft"  the  coronary  nerves 
and  is  transformed  into  the  superficial  and  part  of  the  deep  cardiac  ])lexus;  the 
remainder  of  the  deep  cardiac  i)lexus  is  formed  l^y  the  intermediate  plexus  and  the 
atrial  plexus  becomes  the  auricular  network. 


SOLAR   PLEXUS  835 

The  fibres  which  pass  to  the  cardiac  plexuses  are  medullated  and  iion-medullated; 
the  former  are  inhit)itory.  the  hitter  motor.  The  inhil)it()ry  fibres  leave  the  central 
nervous  system  Ijy  the  spinal  accessory  and  vagus  nerves,  the  motor  fibres  Ijy  the 
roots  of  the  dorsal  nerves. 

SOLAR  PLEXUS 

The  solar  plexus  is  placed  in  front  of  the  commencement  of  the  abdominal 
aorta.  It  is  the  largest  of  tlie  prevertebral  plexuses,  and  is  formed  by  the  two 
semilunar  ganglia,  and  by  a  number  of  interlacing  nerve-cords  Avhich  surround  the 
ganglia.  Each  semilunar  ganglion  is  placed  at  the  side  of  the  coeliac  axis,  embrac- 
ing the  artery  in  its  concavity.  The  upper  and  the  lower  extremities  of  the  ganglia 
of  oj)posite  sides  are  connected  to  one  another  l)y  nerve-cords,  above  and  below  the 
artery.  In  this  manner  the  cceliac  axis  is  surrounded  by  a  neuro-ganglionic  collar. 
From  this  neuro-ganglionic  collar  a  numlxn*  of  branches  arise  which  are  joined  by 
branches  from  the  right  vagus  and  Ijy  both  small  sitlanchnic  nerves,  and  in  this 
manner  the  solar  plexus  is  formed.  From  the  solar  plexus  a  number  of  nerves 
arise  which  accom])any  the  abdominal  aorta  and  its  branches,  forming  secondary 
plexuses,  which  take  their  names  from  the  arteries  they  accompany. 

Semilunar  ganglia. — These  are  a  pair  of  reddish-grey,  irregularly  sha]»ed 
bodies  whicli  rest  ou  the  crura  of  the  diaphragm,  close  to  the  ea4iac  axis.  The 
great  sjjlanchnic  nerve  on  each  side,  after  piercing  the  crus  of  the  diaphragm, 
enters  the  outer,  or  convex,  side  of  the  corresponding  ganglion. 

Cceliac  plexus. — The  celiac  plexus  surrounds  the  coeliac  axis,  and  divides  into 
splenic,  hepatic  and  coronary  plexu.ses. 

The  splenic  plexus,  after  receiving  a  communication  from  the  right  pneumo- 
gastrie  nerve,  accompanies  the  splenic  artery  to  the  sjileen.  It  gives  ofif  j^ancreatic 
and  left  gastro-epiploic  plexuses. 

The  hepatic  plexus  is  joined,  near  the  pyloric  end  of  the  stomach,  by  branches 
from  tlie  left  imeumogastric.  and  accompanies  the  hepatic  artery  to  the  liver,  where 
it  divides  into  right  and  left  liepatic  plexuses.  Previous  to  its  ili vision,  it  gives  off 
pyloric,  right  gastro-epiploic,  and  pancreatico-duodenal  plexuses.  From  the 
right  hepatic  plexus  a  cystic  i»lexus  is  furnished  to  the  gall-bladder. 

The  coronary  plexus  follows  the  lesser  curvature  of  the  stomach,  pi'oceeding 
from  left  to  right.  In  this  course  it  is  joined  by  ])ranches  from  the  left  pneumo- 
gastric,  and.  after  giving  off  numerous  twigs  to  the  stomach,  ends,  near  the  pylorus. 
by  joining  the  pyloric  plexus. 

The  diaphragmatic  plexuses  arise  from  the  upper  extremities  of  the  semilunar 
ganglia,  and  accompany  tlie  diai)hragmatic  arteries  to  the  under  surface  of  the 
dia|)hragm.  On  the  rii:ht  side  a  eoniiiiunication  is  efTected  Avith  the  phrenic  nerve, 
a  small  ganglion  (ganglion  diaphragmaticum )  being  formed  at  the  point  of  com- 
munication. 

The  suprarenal  plexuses  are  derived,  in  part  from  the  diaitlu-agmatic.  in  i)art 
from  the  solar,  and  in  ])art  from  the  renal  ])lexuses;  they  are  distributed  chiefiy  to 
the  medullary  portions  of  the  suprarenal  liodies. 

The  renal  plexuses  are  formed  by  branches  of  the  solar  and  aortic  plexuses, 
and  are  joined  })Osteriorly  by  the  smallest  splanchnic  nerves.  Each  renal  ]^lexus 
surrounds  the  corresponding  renal  artery;  it  contains  groups  of  ganglion  cells  and 
enters  the  hiluni  of  the  kidney,  where  it  subdivides  in  the  fatty  tissue  whieli  occu- 
pies the  sinus,  and  enters  the  substance  of  the  kidney  with  the  V)lood-vessels. 

The  superior  mesenteric  plexus  is  <if  large  size,  and  is  remarkal)le  for  the 
comparatively  white  eolovu-  of  the  nerves  whicli  com]>ose  it.  It  is  derived  from 
the  solar  plexus,  anil,  after  emerging  from  under  cover  of  the  jiancreas.  closely 
surrounds  the  trunk  of  the  su]>erior  mesenteric  artery.  In  this  situation  a  few 
ganglia  (ganglia  mesenterica)  are  formed.  Having  given  off  branches,  which 
accompany  the  coliea  media,  colica  dextra,  and  ileocolic  arteries,  the  greater  jiart 
of  the  plexus  enters  the  mesentery,  where  the  nerv'es — no  longer  closely  following 
the  blood-vessels,  spread  out  lietween  the  layers  of  the  mesentery,  and  eventually 
reach  the  small  intestine. 

The  aortic  plexus  is  in  the  form  of  two  vast   networks  of  nerves  whicli  are 


836 


THE  NERVOUS  SYSTEM 


Fig    471.— Lumbar  Portion  of  the  Gangliated  Cord,  with 
Hypogastric  Plexuses.      (Henle.) 


THE  Solar  and 


GAXGLION  DIA  PHK.i  GMA  TICUM 


SUPRARENAL 
CAPSULE 


Hepalic  iirtcry 


GREA  T  SPLANCH- 

XI C  y'ER  VE 
RIGHT  SEMILV- 
SAR    GANGLION 


RENAL  GANGLION 

S3IALL  SPLANCHNIC 
NER  VE 

Renal  ailery  — ^\i 

GANGLIA  TED  CORD 

RAMUS  COMMUNICA.^'^ 


BRANCH  TO  iORTIC 
PLEXL  b 


LEFT  SE.VILT'- 
NAR    GANGLION 

GREAT  SPLANCH- 
NTC  NERVE 

SMA  LL  SPLA  SCH- 
NIC  NERVE 

Superior  mesenteric 
artery 

RENAL  GANGLION 


Renal  artery 


SUPERIOR  MESENTERIC 
GANGLION 


BRANCH  TO  AORTIC 
PLEXUS 


GANG  LI  A  TED  CORD  OF 
SYMPATHETIC 


Inferior  mesenteric  artery 


INFERIOR  MESEN- 
TERIC GANGLION 


Disc  between  last  lumbar 
and  first  sacral  vertebra 


Common  iliac  vein 
Commmi  iliac  artery 


HYPOGASTRIC  PLEXUS— PELVIC  PLEXUSES  837 

massed  along  the  sides  of  tlio  abdominal  aorta,  and  are  connected  by  coniniuni- 
cating  branches  which  ])ass  across  the  front  of  the  great  vesseL  It  is  formed 
mainly  by  the  downward  continuation  of  the  solar  plexus,  but  receives  strong  rein- 
forcements from  the  upper  three  lumbar  ganglia.  It  gives  off  the  spermatic  and 
inferior  mesenteric  jilexuses,  and  terminates  below  in  strong  branches  to  the  hj^po- 
gastric  plexus. 

The  inferior  mesenteric  plexus  is  much  smaller  than  the  superior  mesenteric 
plexus,  but,  like  the;  latter,  is  remarkable  for  its  whitish  colour.  It  is  derived 
from  the  aortic  plexus,  and  is  conveyed  by  the  branches  of  the  inferior  mesenteric 
artery  to  the  descending  colon,  the  sigmoid  flexure,  and  to  the  upper  part  of  the 
rectum.  In  the  latter  situation  it  communicates  Avith  the  pelvic  plexuses.  It 
contains  the  inferior  mesenteric  ganglion. 

The  spermatic  plexus  is  derived  from  the  aortic  and  renal  plexuses.  It  ac- 
companies the  spermatic  artery  as  far  as  the  internal  abdominal  ring,  Avhere  it  is 
joined  l)y  a  fine  plexus  derived  from  the  pelvic  plexus  and  accompanying  the  vas 
deferens.     Thus  reinforced,  it  is  conducted  by  the  spermatic  cord  to  the  testicle. 

In  the  female  it  accompanies  the  ovarian  vessels  to  the  ovary  and  uterus. 

The  more  important  fibres  which  pass  to  the  solar  plexus  have  already  been 
described  in  connection  with  the  lumbar  and  dorsal  portions  of  the  sympathetic  cord. 


HYPOGASTRIC  PLEXUS 

From  the  lower  ganglia  of  the  lumbar  sympathetic  cord,  two  or  three  strong 
branches  ])roceed  which  cross  oblicjuely  in  front  of  the  connnon  iliac  arteries. 
These  nerves  are  joined  by  stout  offsets  from  the  aortic  plexus,  and  interlace  in 
front  of  the  body  of  the  fifth  lumljar  vertebra  with  the  corresponding  nerves  of  the 
opposite  side  to  form  a  broad  flattened  band,  Avhich  is  termed  the  hypogastric 
plexus.  This  plexus  is  remarkable  in  that  it  contains  little  or  no  ganglionic 
matter.  It  soon  divides  into  two  lateral  portions,  the  pelvic  or  inferior  hypogastric 
plexuses. 

Pelvic  Plexuses 

Each  of  the  two  lateral  continuations  of  the  hypogastric  plexus  contains  gan- 
glion cells;  it  passes  downwards  on  the  side  of  the  rectum,  where  it  is  joined  hy 
slenfier  branches  from  the  sacral  part  of  the  gangliated  cord,  and  by  branches  from 
the  third  and  fourth  (sometimes  the  second)  sacral  nerves.  In  this  manner  the 
pelvic  plexuses  are  formed.  Each  pelvic  plexus  gives  off  branches  to  the  pelvic 
viscera;  these  branches,  in  the  greater  part  of  their  course,  follow  the  arteries  of 
the  ])elvis.  We  distinguish  middle  hsemorrhoidal,  vesical,  prostatic,  and  (in  the 
female)  vaginal  and  uterine  jilexuses. 

The  middle  haemorrhoidal  plexuses  form  a  closely-meshed  expansion  on  the 
sides  of  the  rectum;  they  comnmnicate  above  with  branches  from  the  inferior 
mesenteric  plexus,  and  below  with  the  inferior  haemorrhoidal  branches  of  the  pudic 
nerve.     • 

The  vesical  plexus  is  clneily  formed  by  fil)res  derived  from  the  third  and  fourth 
sacral  nerves.  The  nerves  pass  forwards  on  each  side  of  the  l)ladder,  and  divide 
into  two  groups — a  superior  group,  which  sup])lies  the  up])er  two-thirds  of  the 
bladder;  and  an  inferior  group,  which  is  distributed  to  the  lower  third  of  that 
viscus.  In  the  male,  braiichc^s  are  given  off  to  the  vesicula^  seminales  and  vasa 
deferentia.  The  nerves  to  the  vas  deferens  form  a  slender  plexus  which  accom- 
panies that  structure  as  far  as  the  internal  abdominal  ring,  where  it  unites  with  the 
spermatic  plexus. 

The  prostatic  plexus  is  placed  a  little  lower  down  than  the  vesical  plexus,  of 
which  it  is  in  some  measure  a  continuation.  The  nerves  which  pass  to  it  are 
of  relatively  large  size,  and  are  massed  on  the  sides  of  the  organ,  where  several 
ganglionic  masses,  from  one-eighth  to  a  quarter  of  an  inch  in  length  (ganglia 
prostatica  of  Miiller),  are  developed.  From  the  prostatic  ))lexus,  oft'sets  are 
furnished  to  the  vesicuhe  seminales,  and  also  branches  to  the  erectile  structures  of 
the  penis;  the  latter  l)ranches  are  called  cavernous  nerves. 


838  THE  NERVOUS  SYSTEM 

The  small  cavernous  nerves  are  several  fine  twigs  which  pierce  the  layers  of  the 
triangular  ligament  and  tlie  muscular  structures  Avhich  surround  the  membranous 
portion  of  the  urethra.  They  enter  the  corpora  cavernosa  just  in  front  of  the 
sul)pubic  ligament. 

The  large  cavernous  nerve  takes  a  similar  course  through  the  triangular  liga- 
ment, and  runs  forwards  on  the  dorsum  penis  as  far  as  the  middle  of  the  organ, 
where  it  communicates  with  the  dorsal  nerves  of  the  penis.  It  ends  in  twigs  to  the 
corpus  cavernosum. 

In  the  female  there  are  similar  nerves,  but  of  nnich  smaller  size,  distributed  to 
the  clitoris. 

The  vaginal  plexus  is  formed  largely  by  branches  from  the  sacral  nerves.  It 
ramifies  on  the  sides  of  the  vagina,  giving  off  twigs  to  the  erectile  substance,  and  to 
the  mucous  membrane.     A  few  fine  twigs  pass  forwards  to  reach  the  clitoris. 

The  uterine  plexus  accompanies  the  uterine  artery  between  the  layers  of  the 
broad  ligament,  and,  having  received  communicating  twigs  from  the  ovarian  plexus, 
enters  the  muscular  substance.  In  the  gravid  uterus  this  plexus  is  increased  in 
size,  chiefly  on  account  of  an  hypertrophy  of  the  connective  tissue  sheaths  of  the 
nerves. 

The  more  important  fibres  passing  to  the  pelvic  plexuses  are  described  with  the 
visceral  branches  of  the  sacral  plexus. 


SECTION    VI 

OEGANS  OF  SPECIAL  SENSE 


{ 


THE  EYE 

By  R.  MARCUS  GUNN,  M.A.,  F.R.C.S. 

SURGEON   TO   THE  ROYAL  LONDON   OPHTHALMIC  HOSPITAL,    MOORFIELDS ;    OPHTHALMIC  SURGEON  TO   THE 

NATIONAL   HOSPITAL 


THE   EYEBALL   AND    ITS    SURROUNDINGS 

General  Surface  View 

Tliis  examination  is  to  be  made  i)rior  to  anj'  disturbance  of  the  parts,  and  is,  indeed,  best 
ct»nducted  on  the  Uving  body.  A  pocket  magnifying  lens  should  be  at  hand  for  use  when 
required. 

THE  two  eyes  are  situated  nearly  in  the  line  where  the  upper  and  middle  thirds 
of  the  face  meet;  they  lie  rijjht  and  left  of  the  root  of  the  nose,  the  most 
prominent  part  of  the  front  of  each  globe  being  about  an  inch  and  a  quarter 
from  the  middle  line  of  the  face.  Each  eye  is  overshadowed  b}'  the  corresponding 
eyebrow,  and  is  capable  of  being  concealed  by  its  eyelids,  upper  and  lower. 

The  orbital  margin  may  be  traced  all  round  with  the  finger.  At  the  junction  of 
the  inner  and  middle  thirds  of  the  upper  margin,  the  supraorbital  notch  can  usually 
be  felt,  and  the  supraorbital  nerve  passing  through  it  can  sometimes  be  made  to  roll 
from  side  to  side  under  the  finger.  The  inner  margin  is  the  most  difficult  to  trace 
in  this  way,  partly  because  it  is  more  rounded  of?  than  tlic  others,  partly  because 
it  is  l)ridged  over  by  a  firm  fibrous  V)and  (tendo  oculi,  or  inner  palpebral  liga- 
ment), passing  inwards  from  the  eyelids;  l»elow  this  band,  however,  a  sliarp  l>ony 
crest  is  felt,  which  lies  in  front  of  the  lachrymal  sac.  Note  how  the  eye  is  pro- 
tected by  the  rim  of  the  orbit,  above  and  V)elow;  if  we  lay  a  hard  flat  body  over 
the  orbital  opening,  it  will  rest  upon  the  upper  and  lower  bony  prominences,  and 
will  not  touch  the  surface  of  the  globe.  Inwards,  the  eye  is  protected  from  injury 
mainly  by  the  Vjridge  of  the  nose;  outwards  it  is  most  readily  vulnerable,  as  here 
the  orbital  rim  is  comparatively  low.  With  one  finger  ])laced  over  the  closed  upper 
lid,  now  press  the  eyeball  gently  backwards  into  the  orbit,  and  ol»serve  the  elastic 
resistance  met  with,  due  to  the  fact  that  the  glol)e  rests  j)Osteriorly  on  a  pad  of  fat. 

Till-  space  between  the  free  edges  of  the  up])er  and  lower  lids  is  known  as  the 
palpebral  aperture  :  it  is  a  mere  slit  when  the  lids  are  clo.ssed;  but  when  they  are 
open  its  sliape  is.  roughly,  that  of  an  almond  lying  with  its  long  axis  horizontal, 
and  aViout  thirty  millimetres  in  length. 

When  the  eyes  are  directed  to  an  object  .straight  in  front  of  them,  this  aperture 
is  about  twelve  millimetres  wide,  but  its  width  varies  with  upward  and  downward 

839 


840  ORGANS  OF  SPECIAL  SEXSE 

movements  of  the  eyeball,  being  greatest  on  looking  strongly  upwards,  diminishing 
gradually  as  the  eye  looks  progressively  lower.  The  angles  formed  l)y  the  meeting  of 
the  lids  at  each  end  of  the  palpebral  aperture  are  named  respectively  the  outer  and 
inner  canthus,  of  which  the  outer,  or  temporal,  is  sharp,  while  the  inner,  or  nasal, 
is  rounded  off.  On  a  closer  inspection,  it  will  be  found  that,  for  the  last  five  milli- 
metres or  so  before  reaching  the  inner  canthus,  the  edges  of  the  lids  run  an  almost 
parallel  course,  and  are  here  devoid  of  lashes.  Through  the  open  palpel^ral  aperture 
the  front  of  the  eyeball  comes  into  view,  extending  quite  to  the  outer,  but  not  reach- 
ing as  far  as  the  inner,  canthus;  just  within  the  latter  we  find  a  small  reddish 
prominence,  the  lachrymal  caruncle  ;  an<l  lietween  this  and  the  eyeball  a  fold  of 
conjunctiva  known  as  the  plica  semilunaris,  ^^'hile  the  eye  is  open,  press  one 
finger  on  the  skin,  a  little  beyond  the  outer  canthus,  and  draw  it  firmly  outwards 
from  the  middle  line;  observe  that  the  upper  lid  then  falls  over  the  eyeball,  and 
that  the  outline  of  a  firm  band  already  referred  to  (the  tendo  oculi)  becomes 
evident,  passing  between  the  inner  canthus  and  the  nose.  The  falling  of  the  lid  is 
caused  by  our  dragging  upon  a  ligament  (the  outer  jialpebral)  to  which  the  outer 
end  of  its  tarsus  is  attached,  and  so  putting  the  lid  itself  u])on  the  stretch.  If, 
while  the  eyeball  is  directed  downwards,  we  place  one  finger  on  the  outer  end  of  the 
up})er  eyelid  and  draw  it  forci])ly  upwards  and  outwards,  we  can  usually  cause  the 
lower  division  of  the  lachrymal  gland  to  present  just  above  the  outer  canthus. 

The  upper  eyelid  is  much  broader  than  the  lower,  extending  upwards  as  far  as 
the  eyebrow.  The  skin  covering  it  is  loosel}'  attached  to  the  subjacent  tissues  above, 
but  more  firmly  below^,  nearer  the  free  margin,  Avhere  it  overlies  a  firm  fibrous 
tissue  called  the  tarsus.  When  the  eye  is  open,  a  fold  is  present  at  the  upper  border 
of  this  latter  more  tightly  applied  portion  of  skin,  called  the  superior  palpebral 
fold,  and  by  it  the  lid  is  marked  off  into  an  upper  or  orl)ital,  and  a  lower  or  tarsal, 
division.  The  presence  of  the  tarsus  can  be  readily  appreciated  on  our  pinching 
horizontally  the  entire  thickness  of  the  eyelid  below  the  palpebral  fold.  The  lower 
eyelid  is  similarly  divided  anatomically  into  a  tarsal  and  an  orbital  part,  l)ut  the 
demarcation  is  sometimes  unrecognisable  on  the  surface,  though  there  is  usually 
here  also  a  fold  or  groove  (the  inferior  palpebral)  visible  when  the  eye  is  Avidely 
opened.  There  is  no  precise  limit  of  this  lid  Ijelow,  but  it  may  be  regarded  as 
extending  to  the  level  of  the  lower  margin  of  the  orl)it.  Numerous  very  fine  short 
hairs  are  seen  on  the  cutaneous  surface  of  both  eyelids.  The  free  margin  of  each 
lid  has  two  edges — (a)  An  outer,  or  anterior,  rounded  edge,  along  which  the  stiff 
eyelashes,  or  cilia,  are  closely  placed  in  several  rows;  and  (b)  a  sharp  jtosterior 
edge,  which  is  applied  to  the  surface  of  the  globe.  The  lashes  of  both  eyelids  have 
their  points  turned  away  from  the  palpebral  aperture,  so  that  the  u|)per  ones  curve 
upwards,  and  the  lower  downwards;  the  cilia  of  the  upper  lid  are  the  stronger,  and 
those  in  the  middle  of  each  row^  are  longer  than  those  at  each  end.  Between  the 
tw^o  edges  just  described,  the  lid-margin  has  a  smooth  surface,  on  which  we  observe 
a  single  row  of  minute  apertures,  Avhich  are  the  openings  of  large  modified  sebaceous 
glands  (the  Meibomian  follicles)  ;  it  is  by  these  glistening,  well -lubricated  sur- 
faces that  the  ojiposite  lids  come  into  apposition  when  they  are  closed.  The  sharj) 
l)Osterior  edge  of  the  lid-margin  marks  the  situation  of  the  transition  of  skin  into 
mucous  membrane.  Not  far  from  the  inner  end  of  this  edge  we  find  a  ])rominence, 
the  lachrymal  papilla,  on  the  summit  of  which  is  a  small  hole  (lachrymal  punc- 
tum),  the  opening  of  the  canaliculus  for  the  passage  of  tears  into  the  lachrymal 
sac.  The  lower  punctum  is  rather  larger  than  the  up])er,  and  is  placed  further 
from  the  inner  canthus. 

If  we  now  examine  the  inner  surface  of  the  eyelids — e.g.  of  the  lower — we 
observe  that  it  is  lined  by  a  soft  mucous  membrane,  the  palpebral  conjunctiva. 
Over  the  tarsal  part  of  the  lid,  the  conjunctiva  is  closelv  adherent,  but  beyond  this 
it  is  freely  movable  along  with  the  loose  subniucous  tissue  here  present.  On 
tracing  it  backwards,  we  find  that  it  covers  the  whole  inner  surface  of  the  lids,  and 
is  then  continued  forimnh  over  the  front  of  the  eyeliall,  forming  the  ocular 
conjunctiva;  the  bend  it  makes  as  it  changes  its  direction  here  is  called  the  con- 
junctival cul-de-sac,  or  fornix.  Numerous  underlying  blood-vessels  are  visible 
through  the  palpeliral  conjunctiva,  and  beneath  the  tarsal  part  of  it  we  can  see 
a  series  of  nearly  straight,  parallel,   light  yellow  lines,   arranged  per])endicularly 


I 


THE   EYEBALL   AXD   ITS  SURROUXDINGS 


841 


to  the  free  inar<iin  of  the  lid — the  Meil)onii;in  follicles.  The  conjunctiva  over  the 
outer  and  inner  fourths  of  each  lid  is  not  (juite  so  smooth  as  elsewhere,  and  is  nor- 
mally of  a  deeper  red  colour;  we  shall  find  later  that  there  are  glands  well  devel- 
oped in  these  positions. 

When  the  eyelids  are  opened  naturally,  we  see  through  the  ])alpebral  aj)erture 
the  following:  the  greater  part  of  the  transparent  cornea,  and  behind  it  the  coloured 
iris  with  the  pu])il  in  its  centre;  white  sclerotic  to  the  outer  and  inner  sides  of  the 
cornea;  the  semilunar  fold  and  lachrymal  caruncle  at  the  inner  canthus.  The 
extent  of  the  eyel>all  visible  in  this  way  varies  according  to  its  i)osition.  Thus, 
with  the  eyes  looking  straight  forwards,  the  loAver  margin  of  the  upper  lid  is  nearly 
opposite  to  the  top  of  the  cornea,  or,  more  strictly,  to  a  line  mithvay  between  the 
top  of  the  cornea  and  the  ujiper  l)order  of  the  pupil,  while  the  lower  lid  corresponds 
with  the  lower  corneal  margin.  When  the  eyes  are  directed  strongly  upwards,  the 
ui)per  lid  is  relatively  on  a  slightly  higher  level,  as  it  is  simultaneously  raised,  but 
the  lower  lid  now  leaves  a  strip  of  sclerotic  exposed  below  the  cornea.  On  looking 
downwards  the  upper  lid  covers  the  upper  part  of  the  cornea  as  low  down  as  the 
le\el  of  the  top  of  the  pupil,  while  the  lower  lid  is  about  midway  between  the  pupil 
and  the  lower  corneal  l)order. 

If  we  draw  the  eyelids  forcibly  apart,  we  expose  the  whole  cornea,  and  a  zone 
of  sclerotic  al)out  eight  and  a  half  millimetres  in  ])readth  above  and  below,  and  ten 
millimetres  in  l)readth  to  the  outer  and  inner  sides,  altogether  about  one-third  of 


Fig.  472. 


-View  of  Evkball,  ktc,  obtained  on  drawing  the  Lids  fokciblv  apart. 
(After  Merkel,  slightly  modified.) 


SEMILUNAR  FOLD  -Sfc-/' 
UPPER   LACHRYMAL   PUNCTU.i 
CARUNCLE 
LOWER  LACHRYMAL  PUNCTUM 

OPENINGS  OF  MEIBOMIAN  FOLLICLES 


CONJUNCTIVAL  FORNIX 


the  globe;  all  the  eyeball  thus  exposed  is  covered  l)v  the  ocular  conjunctiva.  Over 
the  sclerotic  the  conjunctiva  is  freely  movable,  and  through  it  we  see  superficial 
l)lood- vessels  that  can  be  made  to  slip  from  side  to  side  along  with  it  (conjunctival 
vessels).  Occasionally  otiier  deeper  vessels  may  also  be  seen  which  do  not  move 
with  the  conjunctiva,  l)ut  are  attached  to  the  sclerotic  (anterior  ciliary  arteries  and 
veins).  Near  the  corneal  border  the  conjunctiva  ceases  to  be  freely  movable,  and 
it  is  closely  adherent  to  the  whole  anterior  surface  of  the  cornea,  giving  the  latter 
its  characteristic  bright,  reflecting  appearance;  no  blood-vessels  are  visible  through 
it  here  in  health.  (\\'hen  the  lids  are  shut,  the  space  enclosed  between  their  pos- 
terior surfaces  and  the  front  of  the  eycljall  is  thus  everywhere  covered  by  conjunc- 
tiva, and  is  known  as  the  conjunctival  sac. ) 

Not  infrecjuently,  the  tendinous  insertions  of  some  or  all  of  the  recti  muscles 
into  the  sclerotic  may  be  seen  through  the  conjunctiva,  each  insertion  appearing  as 
a  series  of  Avhitish  parallel  lines  running  towards,  but  terminating  aliout  seven 
millimetres  from  the  corresponding  corneal  border.  The  cornea  appears  as  a 
transparent  dome,  having  a  curvature  greater  than  that  of  the  sclerotic;  the 
junction  of  the  two  unecjually  curved  surfaces  is  marked  by  a  shallow  depression 
nmning  around  the  cornea,  known  as  the  scleral  sulcus.  In  outline  the  cornea 
is  nearly  circular,  but  its  horizontal  diameter  is  slightly  greater  than  its  vertical. 
Between  it  and  the  iris  a  space  exists,  whose  depth  we  can  estimate  roughly  by 
looking  at  the  eye  from  one  side  ;  this  si)ace,  or  anterior  chamber,  is  occupied   by 


842  ORGAyS  OF  SPECIAL  SENSE 

a  clear  fluid,  the  aqueous  humour.  Almost  the  whole  anterior  surface  of  the  iris 
is  visible,  its  extreme  periphery  only  being  concealed  by  sclerotic.  In  colour  the 
iris  varies  greatly  in  different  individuals.  Near  its  centre  (really  a  little  up  and 
in)  a  round  hole  exists  in  the  iris,  the  black  ])ni)il,  whose  size  varies  consideraljl}^ 
in  different  eyes,  and  in  the  same  eye  according  to  temporary  conditions,  such  as 
exposure  to  light,  etc. 

Ill  exaiuiiiing  the  surface-markings  of  the  living  iris,  one  of  dark  colour  is  to  be  preferred. 
Focal  illumination  will  be  found  useful,  for  which  purpose  a  second  convex  lens  will  be  required. 

On  the  surface  of  the  iris  we  see  a  number  of  ridges  running  more  or  less 
radially;  adjoining  ones  occasionally  unite  and  interlace  to  some  extent,  so  as  to 
leave  large  depressed  meshes  at  intervals.  The  ridges  coming  from  the  edge  of  the 
pupil,  and  those  coming  from  the  more  peripheral  part  of  the  iris,  meet  in  a  zigzag 
elevated  ridge,  concentric  with  the  pupil,  and  by  this  ridge  the  iris  is  roughly 
marked  off  into  tAVO  unequal  zones — an  outer  or  ciliary,  and  an  inner  or  pupillary 
— of  which  the  inner  is  much  the  narrower.  The  border  next  the  pupil  is  edged 
with  small,  roundish,  bead-like  prominences  of  a  dark  brown  colour,  separated 
from  one  another  by  depressions,  so  that  it  presents  a  finely  notched  contour.  Not 
infrequently,  in  a  light-coloured  iris,  we  may  see  the  Si3hincter  muscle  through  the 

Fig.  473. — Left  Fundus  Oculi,  as  seex  by  direct  Ophthalmoscopic  Method. 


Retinal  artery 
Retinal  vein 


LAMINA  CRIBROSA 
FOVEA  CENTRALIS 
PIGMENT  AT  OUTER  BORDER  OF  DISC 


anterior  layers,  in  the  form  of  a  ring  about  one  millimetre  in  breadth  around  the 
pupil.  The  ciliary  zone  may  be  described  as  consisting  of  three  parts:  (a)  A 
comparatively  smooth  zone  next  the  zigzag  ridge;  (h)  a  middle  area,  showing 
concentric  but  incompletely  circular  furroAvs;  (c)  a  small  peripheral  darker  part, 
presenting  a  sieve-like  appearance.  On  the  tloor  of  the  large  depressed  meshes,  or 
crypts,  parallel  radial  vessels  can  be  traced,  belonging  to  the  iris-stroma.  The 
zigzag  line  mentioned  above  corresponds  to  the  position  of  the  circulus  arteriosus 
minor.  Occasionally,  especially  in  a  light  iris,  superficial  pigment  spots  of  a  rusty 
brown  colour  occur. 

If  we  are  examining  the  living  eye,  the  ophthalmoscope  should  now  be  used,  so  as  to  gain  a 
view  of  the  ftmdus.  We  can  thus  study  the  termination  of  the  optic  nerve,  the  distribution  of 
the  larger  retinal  vessels,  etc. 

The  general  red  reflex  obtained  from  the  fundus  is  due  to  the  blood  in  a  capil- 
lary network  (chorio-capillaris)  situated  in  the  inner  part  of  the  clioroid.  To 
the  nasal  side  of  the  centre  of  tlie  fundus  is  a  paler  area  of  a  disc  shai)e  corre- 
S])()nding  to  the  intraocular  end  of  the  optic  nerve,  and  known  as  the  optic  disc, 
or  papilla.  This  optic  disc  is  nearly  circular,  but  usually  slightly  oval  vertically; 
it  is  of  a  light  orange-pink  colour,  with  a  characteristic  superficial  translucency; 
its  outer  third  segment  is  paler  than  the  rest  from  the  nerve-fibres  and  cajHllaries 
here  being  fewer.  About  its  centre  we  often  observe  a  Avell-marked  whitish  depres- 
sion or  gap,  formed  by  the  dispersion  of  the  nerve-fibres  as  they  spread  out  over 
the  fundus;  at  the  bottom  of  this  depression  a  sieve-like  appearance  may  be  seen, 
due  to  the  presence  of  the  lamina   cribrosa,  which   consists  of  a  white  fibrous 


EXAMINATION  OF   THE  EYEBALL  843 

tissue  framework,  with  small,  roundish,  light-grey  meshes  iu  it,  through  which 
latter  the  nerve-lihre  bundles  pass.  Also  near  the  centre  of  the  disc,  the  retinal 
hlood-vessels  first  come  into  view',  the  arteries  narrower  in  size  and  lighter  in  colour 
than  the  veins;  they  divide  dichotomously  as  they  are  distributed  over  the  fundus. 
The  retina  proper  is  so  transparent  as  to  be  ophthalmoscopically  invisible,  but  its 
pigment-epithelium  gives  a  very  tinely  granular  or  darkly  stippled  appearance  to 
the  general  red  retiex.  In  the  centre  of  the  fundus,  and  therefore  to  the  outer  side 
of  the  disc,  the  ophthalmoscope  often  shows  a  shifting  halo  of  light  playing  round 
a  horizontally  oval,  comparatively  dark  enclosed  area;  this  latter  corresponds  to 
the  yellow  spot  region,  and  about  its  centre  a  small  pale  spot  usually  marks  the 
position  of  the  fovea  centralis. 

Two  structures  visible  at  the  nasal  end  of  the  palpebral  aperture  have  been 
l)reviously  mentioned,  and  should  now  be  examined  more  narrowly.  The 
lachrymal  caruncle  is  in  reality  an  island  of  modified  skin,  and  fine  hairs  can 
connnonly  be  detected  on  its  surface.  On  its  outer  side,  separated  from  it  by  a 
narrow  groove,  is  the  semilunar  fold  of  conjunctiva  ;  it  rests  on  the  eyeball, 
and  is  a  rudiment  of  the  third  eyelid  or  nictitating  membrane,  present  in  birds 
and  well  represented  in  many  other  vertebrates. 


Examination  of  the  Eyeball 

The  eyeball  of  a  cadaver  should  now  be  removed  by  snipping  with  scissors  the  conjunctiva 
near  the  corneal  border,  then  cutting  through  the  ocular  muscles  near  their  insertion  into  the 
gl(jbe,  and  finally  dividing  the  optic  nerve  close  to  the  sclerotic. 

The  eyeball  is  almost  spherical,  but  not  perfectly  so,  mainly  because  its  an- 
terior, clear,  or  corneal  segment  has  a  greater  curvature  than  the  rest  of  the  eye. 
Considering  it  as  a  globe,  however,  we  speak  of  an  anterior  and  of  a  posterior 
pole  ;  the  former  corresponding  to  the  middle  of  the  front  of  the  cornea,  the 
latter  to  the  middle  of  the  posterior  curvature.  An  imaginary  straight  line  joining 
tin-  two  poles  is  called  the  antero-posterior  or  sagittal  axis  of  the  eyeball.  The 
equator  of  the  eye  is  that  part  of  its  surface  Avhich  lies  midway  between  the  two 
poles.  The  sagittal  axis  of  the  globe  is  the  greatest  (about  24 "o  mm.),  the  ver- 
tical equatorial  the  least  (about  23*5  mm.),  and  the  transverse  equatorial  axis  is 
intermediate  in  length  (about  23-9),  so  that  the  eyeball  is  in  reality  an  ellipsoid, 
flattened  slightly  from  above  dow^nwards.  Again,  if  the  globe  is  divided  in  its 
antero-jxjsterior  vertical  plane,  the  nasal  division  will  be  found  to  be  slightly 
smaller  than  the  temporal.  The  optic  nerve  joins  the  globe  three  or  four  milli- 
metres to  the  nasal  side  of  the  posterior  pole. 

The  shape  of  the  eye  depends  on,  and  is  preserved  by,  the  outermost  tunic, 
formed  conjointly  by  the  cornea  and  sclerotic,  the  entire  outer  surfaces  of  which 
are  now  in  view.  The  anterior  or  corneal  part  has  been  already  examined.  All 
round  the  cornea  there  remains  a  little  adherent  conjunctiva;  elsewhere,  the 
sclerotic  is  directly  exposed,  except  for  some  loose  connective  tissue  which  adheres 
to  it,  especially  around  the  optic  nerve  entrance.  In  front  of  tlie  equator  we  see 
the  tendinous  insertions  of  the  four  recti  muscles.  Behind  the  equator  are  the 
insertions  of  the  two  oblique  muscles — that  of  the  superior  ol)lique  tendinous, 
and  further  forwards;  that  of  the  inferior  more  fleshy,  and  placed  between  the  optic 
nerve  and  the  external  rectus. 

It  is  difficult  to  recognise  the  different  recti  muscles  by  their  insertions  if  we  do  not  know 
whether  the  eye  examined  is  a  right  or  a  left  one.  To  determine  tliis  we  should  liold  the  globe 
with  the  optic  nerve  towards  us,  and  in  the  natural  position  with  the  su|)erior  ob]i<|ue  tendon 
uppermost.  The  inferior  oblique  tendon  will  now  point  to  the  side  to  which  the  eye  belongs,  and 
we  can  consequently  determine  the  different  recti  muscles. 

The  internal  rectus  is  inserted  nearest  (7  nun.  from)  the  corneal  border;  the 
external  rectus  commonly,  sometimes  the  sujierior,  is  inserted  furthest  from  it 
(about  8  nun.).  All  the  recti  tendons  are  broad  and  thin,  but  that  of  the  internal 
is  the  broadest  (8  mm.);  those  of  the  external  and  inferior  the  narrowest  (6  mm.) 


844 


ORGANS  OF  SPEC  FA  L  SENSE 


The  greatest  interval  between  two  neighl)Ouring  tendons  is  tliat  between  the 
superior  and  internal  recti  (about  12  mm.);  the  least  is  between  the  superior  and 
external  (7  mm.).  The  form  of  the  lines  of  insertion  of  the  different  tendons 
varies  considerably,  the  inferior  being  almost  straight,  the  superior  and  external 
convex  forwards,  the  internal  further  removed  from  the  corneal  border  below  than 
above. 

The  insertions  of  the  obliques  are  at  more  than  double  the  average  distance  of 
the  insertions  of  the  recti  from  the  corneal  border.  That  of  the  superior  oblique  is 
found  on  the  superior  surface  of  the  sclerotic,  about  sixteen  millimetres  from  the 
corneal  edge,  in  the  form  of  a  line  sloping  from  before  backwards  and  inwards. 
The  inferior  oblique  has  a  long  fleshy  insertion  lying  betAveen  the  external  rectus 
and  the  optic  nerve  entrance;  the  posterior  end  of  the  insertion,  which  is  also  the 
highest,  is  only  about  six  millimetres  from  the  optic  nerve,  and  from  this  point 
it  slopes  forwards,  outwards,  and  slightly  downwards. 

Several  small  nerves  and  two  arteries  may  be  seen  running  forwards  and  ulti- 
mately perforating  the  sclerotic  not  far  from  the  entrance  of  the  optic  nerve.  The 
two  arteries  are  the  long  posterior  ciliary;  they  both  perforate  the  globe  in  the 
horizontal  meridian,  one  on  the  outer,  the  other  on  the  inner  side.  The  short 
ciliary  arteries  are  too  small  to  be  seen  in  an  ordinary  examination.     The  nerves 


Fig.  474.— Diagrammatic  View  of  the  Insertions  of  the  Ocular  Muscles. 

(After   Merkel.) 


are  the  long  and  short  ciliary.  Nearer  the  equator,  the  large  venous  trunks  emerge; 
they  can  be  traced  for  some  distance  in  front  of  their  exit  as  dark  lines,  running 
antero-posteriorly  beneath  the  sclerotic.  The  optic  nerve  is  seen  in  section,  sur- 
rounded loosely  by  a  thick  outer  slieath;  in  the  centre  of  the  nerve-section  a  small 
red  spot  indicates  the  position  of  the  central  retinal  blood-vessels. 

For  ordinary  dissections  eyes  of  the  sheep,  pig,  or  Ijullock  should  be  obtained.  Divide  an 
eyeball  into  fore  and  hind  halves  by  cutting  through  it  in  the  equatorial  plane. 

1.  Posterior  hemisphere  seen  from  in  front.  This  is  mucli  the  sjiuk'  view  that  tlie  oi)lithal- 
moscope  affords  us.  Unless  tlie  eye  be  very  fresh,  however,  the  retina  will  have  lost  its  tians- 
pareney,  and  will  now  present  the  appearance  of  a  thin  whitish  nienihrane,  detached  in  liilds 
from  the  underlying  coats,  but  still  adherent  at  the  ojitic  disc.  The  vitreous  jelly  lying  within 
the  retinal  cup  may  he  torn  away.  In  the  human  eye  the  retina  next  the  {)osterior  pole  is 
stained  yellow  (macula  lutea).  On  turning  the  retina  over,  a  little  jtigment  may  he  seen  adher- 
ing to  its  outer  surface  here  and  there.  Cut  through  the  retina  close  to  the  ojitic  disc  all  round 
and  remove  it  :  note  how  easily  it  is  torn.  We  now  see  a  dark  brown  surface,  consisting  of  the 
retinal  pigment  layer,  adhenMit  to  the  inner  surface  of  the  choioid.  Brush  off  the  retinal  pig- 
ment under  water.  The  choroid  thus  exposed  can  for  the  most  part  be  fairly  easily  torn  away 
from  the  thick  sclerotic,  as  a  lymph-space  exists  between  them,  but  the  attachment  is  firm 
around  the  oi)tic  nerve  entrance,  and  also  where  the  arteries  and  nerves  join  the  choroid  alter 
penetrating  the  sclerotic.  The  choroid  is  darkly  i)igmented  of  a  brown  colour,  with  markings  ou 
its  surfaces  corresponding  to  the  distribution  of  its  large  veins.     The  inner  surface  of  the  sclerotic 


EXAMrXATfOX   OF   THE  EYEBALL  845 

is  of  a  lipVit  browniish  coldur,  mainly  in»iu  tlie  presence  of  a  delicate  piffuieiited  layer,  tlic  mem- 
brana  suprachoroidea,  wiiieli  adlieies  jmrtly  to  it,  partly  to  the  choroid,  giving  to  their  adjacent 
surface.^  a  fl(tcculent  appearance  when  examined  under  water. 

2.  Anterior  hemisphere  viewed  from  behind.— Tiie  round  opening  of  the  pupil  is  visible  in 
the  middle,  with  the  large  clear  crystalline  lens  lying  behind  it.  The  retina  proper  extends 
forwards  a  little  way  from  our  line  of  .section,  and  then  ends  abruptly  in  a  wavy  line  called  the  ora 
serrata,  beyond  which  it  is  only  re|iresented  by  a  very  thin  m(nd)rane  (pars  ciliaris  retinae). 
Outside  the  periphery  of  the  lens  are  a  number  of  ciliary  processes  arrangeil  closely  together 
in  a  circle  concentric  with  the  pupil,  and  each  radially  elongated  ;  posteriorly  they  are  continuous 
with  numerous  fine  Iblds,  also  radial,  which  ."^oon  get  vi'ry  indistinct  as  they  pa.-^s  bac-kwards,  hut 
reach  almost  to  the  ora  serrata  (plicae  ciliares).  Between  the  front  ol'  the  ciliary  i)roeesses  and 
the  edge  of  the  iiupil  lies  the  iris.  On  removal  of  the  retina  the  inner  surface  of  all  this  regi(jn 
is  seen  to  be  darkly  pigmcjnted,  but  especially  dark  in  front  of  the  positi(jn  of  tiie  ora  serrata. 
Vitreous  probably  still  adheres  to  tiie  back  of  the  lens,  and  by  pulling  upon  it  the  lens  can  be 
removed  along  with  its  capsule  and  suspensory  ligament  ;  some  jiigincnt  will  now  be  iifund 
adhering  to  the  front  of  the  vitreous,  torn  from  the  ciliary  processes,  which  are  consefiuciitly 
now  lighter  in  colour  than  before.  The  lens-capsule  is  transparent,  and  has  a  smooth  glistening 
outer  surfice  ;  through  it  a  greyish  star-shaped  figure  may  be  observed  on  the  anterior  and 
posterior  surfaces  of  the  lens.  The  suspensory  ligament  is  a  transi>arent  membiane  attached  to 
the  cajisule  of  the  lens  about  its  eijuator,  and  is  bi-st  seen  by  floating  the  lens  in  water  in  a  gla.ss 
vessel  jilaced  on  a  dark  ground.  On  oiiening  the  cajisule  we  expose  the  lens  itself  which  is 
supeifi -ially  .soft  and  glutinous  to  the  tcnich,  but  Ix'comes  firmer  as  we  rub  off  its  outer  layers  and 
approach  its  centre.  Carefully  tear  the  choroid  and  iris  from  the  sclerotic  :  a  firm  adhesion  exists 
just  behind  the  corneal  iieriphery.  Their  outer  surface  thus  exposed  is  found  to  be  also  rather 
darkly  pigmented  (as  far  forward  as  the  base  of  the  iris  at  least),  but  it  shows  a  white  ring  corre- 
sponding to  tlie  adhesion  just  mentioned,  and  a  pale  area  behind  this  ring  indicates  the  position 
of  the  ciliary  muscle.     On  this  surface  numerous  white  nerve-cords  are  visible  running  forwards. 

Fig.  475. — Equatorial  Section'  of  Eyeball  :  Anterior  Segment  viewed  from 

BEHIND.     (After  Merkel. ) 


PUPIL 
CILIARY  PROCESSES 


PLIC/t  CILIARES 


Observe  that  the  iris,  the  ciliary  processes,  etc.,  and  the  choroid  are  all  different  i)arts  of  the 
same  ocular  tunic — mere  local  modifications  of  it.  Similarly  the  sclerotic  and  cornea  are  seen  to 
blend  together  to  form  one  outer  coat. 

An  eyeball  should  now  be  placed  for  half  an  hour  in  a  freezing  mixture  of  crushed  ice  and 
salt.  It  will  thus  become  (|uite  hard,  and  should  at  once  be  divided  into  two  jiarts  by  cutting  it 
antero-posteriorly  through  the  centre  of  the  cornea  and  the  optic  nerve.  We  thus  gain  another 
view  of  the  relations  of  parts,  the  position  of  the  lens  between  the  aqueous  and  vitreous  chambers, 
etc.  On  removing  the  lens,  vitreous,  and  retina,  and  brushing  oft'  its  pigment,  the  light  mark- 
ings corresponding  to  the  choroidal  veins  (venae  vorticosae")  should  be  noted,  and  their  distri- 
bution studieil.  Usually  four  vortices  or  fountain-like  markings  are  found  in  the  whole  choroid, 
their  points  of  junction  situated  at  aiiproximatcly  e(|ual  distances  from  one  another  at  about  the 
line  where  the  posterior  and  middle  thirds  of  the  globe  meet.  These  sections  should  be  kept  for 
reference  while  following  the  further  description  of  the  ocular  tunics. 

1.  The  outer,  fibrous  coat  of  the  eye  is  foniud  by  fhe  sclerotic  an<l  corncn. 
wliich  pass  into  one  another  at  the  scleral  sulcus.  It  c(jnsists  throughout  mainly 
of  fine  coiuiective-tissue  filjres,  arranged  in  intcrlaeintr  bundles,  with  small  lympli- 
s|)aces  at  intervals  between  them.  The  naked-eye  a})])earance  of  the  two  divisions 
of  this  fibrous  coat  is,  however,  (|uite  difTerent,  the  cornea  heinj;  trans|iar<nt,  while 
the  sclerotic  is  white  and  opacjue. 

The  sclerotic  encloses  the  posterior  five-sixths  or  so  of  tlie  eyeball,  but  there  is 
a  hole  in  it  at  the  entrance  of  tlie  optic  nerve  (foramen  sclerae),  only  partially 
bridged  .across  by  fibres  from  its  inner  layers  forming  the  lamina  cribrosa.  The 
fibre-bundles  composing  the  sclerotic  are  arranged  more  irregularly  thati  in  the 
cornea,  and  run  mainly  in  two  directions,  viz.  from  before  backwards,  and 
circularly;  the  circular  fibres  are  particularly  well  developeil  just  behind  the 
sulcus.      It  is  thickest  (about  1  mm.)  posteriorly,  where  it  is  strengthened  chiefly 


846  ORGAAS  OF  SPECIAL  SENSE 

by  the  outer  sheath  of  the  optie  nerve,  and  i)artly  also  ])y  tlie  tissue  surrounding 
the  cihary  vessels  and  nerves.  It  becomes  gradually  thinner  as  it  passes  forwards, 
up  to  the  line  of  insertion  of  the  recti  muscles,  in  front  of  which  line  it  is  again 
reinforced  by  their  tendinous  fibres  becoming  incorporated  Avith  it.  In  children 
the  sclerotic  is  often  so  thin  as  to  allow  the  underlying  choroidal  pigment  to  show 
through,  appearing  then  of  a  bluish  white.  In  the  aged,  again,  it  is  sometimes 
yellowish.  It  always  contains  a  few  pigment  cells,  but  these  are  in  the  deej)  layers, 
and  only  become  visible  externally  where  the  sclerotic  is  })ierced  by  vessels  and 
nerves  going  to  the  choroid.  It  is  itself  almost  non-vascular,  but  quite  at  its 
anterior  end  a  large  venous  sinus  (canal  of  Schlemm)  runs  in  its  dee])er  layers 
circularly  around  the  cornea.  Just  in  front  of  this  sinus,  at  the  corneal  limbus, 
the  sclerotic  merges  into  the  cornea,  its  deep  layers  changing  first,  and  tinally  the 
su})erticial  ones. 

The  cornea  is  thickest  at  its  periphery,  and  becomes  gradually  thinner  towards 
its  centre;  the  curvature  of  its  posterior  is  consequently  greater  than  that  of 
its  anterior  surface,  but  even  the  latter  is  more  curved  than  the  surface  of  the 
sclerotic.  In  the  cornea  proper,  fil^re-ljunclles  are  arranged  so  as  to  form  a  series 
of  superposed  lamella?,  each  of  which  is  connected  here  and  there  to  the  adjacent 
ones  by  fibres  passing  from  one  to  the  other,  so  that  they  can  only  be  torn  apart 
with  difficulty.  The  corneal  lymph-spaces  communicate  with  one  another  by  very 
fine  canals,  and  thus  not  only  is  a  thorough  lymph-circulation  provided  for,  but 
the  protoplasm  with  which  these  spaces  are  partially  occupied  may  be  also 
regarded  as  continuous  throughout.  It  contains  no  blood-vessels,  with  the  excep- 
tion of  a  rich  plexus  at  its  extreme  peripher}',  on  which  its  nutrition  is  ultimately 
dependent. 

The  most  superficial  part  of  the  true  cornea  appears  homogeneous,  even  when 
highly  magnified  (Bowman's  membrane),  though  there  is  reason  to  believe  that 
its  structure  only  differs  from  that  already  described  in  the  closeness  of  its  fibrous 
texture;  the  two  parts  are  certainly  connected  by  fine  fibres.  Anteriorh',  the  cornea 
is  covered  hx  an  extension  of  the  ocular  conjunctiva,  in  the  form  of  an  epithelium 
several  la^-ers  deep.  Posteriorly,  the  cornea  is  lined  b}'  a  firm,  thin,  glass-like  layer 
(membrane  of  Descemet,  posterior  elastic  lamina),  distinct  from  the  corneal 
tissue  both  anatomically  and  chemically.  At  the  periphery  this  membrane  breaks 
up  into  a  nuniV)er  of  fil)res.  which  mainly  arch  over  to  join  the  base  of  the  iris 
(ligamentum  pectinatum  iridis).  The  interstices  between  these  fibres  constitute 
spaces  (spaces  of  Fontana )  freely  communicating  with  the  aqueous  chamber  on  the 
one  hand,  and  indirectly  with  the  canal  of  Schlemm  on  the  other.  Descemet' s 
mem1)rane  is  in  turn  lined  hx  a  single  layer  of  flat  cells,  which  are  continuous 
peripherally  Avith  cells  lining  the  spaces  of  Fontana  and  the  anterior  surface  of  the 
iris.  The  cornea  is  richly  supplied  with  nerves,  particularly  in  its  most  superficial 
layers. 

2.  The  dark,  middle,  or  vascular  coat  of  the  eye,  generally  known  as  the 
uveal  tract,  is  formed  ))y  the  iris,  ciliary  body,  and  choroid.  It  is  closely  applied 
to  the  sclerotic,  but  actually  joins  it  only  at  the  anterior  and  posterior  limits  of  their 
course  together,  viz.  at  the  scleral  sulcus,  and  around  the  optic  nerve  entrance.  In 
front  of  the  sulcus  the  middle  coat  no  longer  lines  the  outer,  being  separated  from 
it  (i.e.  the  iris  from  the  cornea)  by  a  consideraWe  space  filled  with  fluid,  called  the 
anterior  aqueous  chamber.  The  uveal  tract  has  two  openings  in  it;  a  larger  one  in 
front,  the  pupil,  and  a  smaller  one  behind,  for  the  passage  of  the  optic  nerve.  Its 
structure  is  that  of  a  pigmented  connective  tissue,  supporting  numerous  blood- 
vessels and  containing  many  nerves  and  two  deposits  of  smooth  muscle-fibres. 

The  choroid  forms  the  posterior  part  of  the  uveal  tract,  and  extends,  with 
slowly  diminishing  thickness,  forwards  as  far  as  the  ora  serrata.  Its  outer  and 
inner  surfaces  are  both  formed  by  non-vascular  layers;  that  covering  the  outer,  the 
membrana  suprachoroidea,  is  jngmented,  arranged  in  several  fine  loose  lamella", 
and  has  been  seen  in  our  dissection;  that  covering  the  inner  surface  is  a  thin,  trans- 
parent, homogeneous  membrane,  called  the  vitreous  lamina  of  the  choroid,  or  the 
membrane  of  Bruch.  The  intervening  choroidal  stroma  is  very  rich  in  blood- 
vessels, which  are  of  largest  size  next  its  outei'  surface,  and  become  progressively 
smaller  as  we  approach  the  vitreous  lamina,  next  to  which  we  find  a  layer  of  closely 


EXAMLXATIOX   OF   THE  EYEBALL 


847 


placed  wide  capillaries,  called  tlie  chorio-capillaris.  The  pigment  becuUR-n  less  in 
aniDunt  as  we  pass  inwards,  and  tinally  ceases,  being  absent  entirely  from  the 
chorio-capillaris  and  vitreous  lamina. 

In  front  of  the  ora  serrata  the  uveal  coat  becomes  considerably  modified,  and 
the  i)art  reaching  from  here  to  the  iris  may  conveniently  ])e  termed  the  ciliary  region 
of  the  tract,  or  ciliary  body.  Its  superficial  aspects  have  ])een  already  l»rit'fiv 
descril)ed.  In  front,  the  ciliary  processes,  about  seventy  in  number.  ])roject  towards 
the  interior  of  the  eye,  forming  the  corona  ciliaris.  Behind  this  i)art  lies' the 
orbiculus  ciliaris,  whose  inner  surface  is  almost  smooth,  faint  radial  folds  only 
being  present,  three  or  four  of  which  join  each  ciliary  process.  The  more  minute 
structure  of  tliis  ciliary  region   resemljles  closely  that  of  the  choroid,  except  that 


Fig.  476. — Diagrammatic  Horizontal  Skctiox  of  Eyeball  and  Orbit. 
(After  Fuchs,  much  modified.) 

Periorbita  green;  mascle-fascia  red;  Tenon's  capsule  yellow. 

Lower  lachrymal  punctnm 
Cornea 
Opening  of  Meibomian  gland 


CARUNCLE 

Inner  palpebral  ligament 


Anterior  chambfr 
Iris 


NASAL  PROCESS  OF  UPPER  JAW 

Anterior  limb  of  inner 
palpebral  ligament 

Lachnniiat  sac 

Posterior  limb  of  inner  palpe- 
bral ligament  with  Horner's 
muscle  springing  from  it 

LACHRYMAL  BONE 

Process  of  muscle-fascia  to  under 
surface  of  conjunctiva 

Ora  serrata 

Tendon  of  insertion  of  internal 
rectus 

Inner  check  ligament 
Periorbita 

ORBITAL  PLATE  OF  ETHMOlO  BONE 

Posterior  lamina  of  muscle-fascia 
lined  by  Tenon's  capsule 


Central  retinal  vessels  in 
optic  nerve 


External  rectus  muscle 


Internal  rectus  muscle 


OPTIC  .SERVE 


the  chorio-capillaris  is  no  longer  present,  that  the  stroma  is  thicker  and  richer  in 
blood-vessels,  and  that  a  muscular  element  (ciliary  muscle)  exists  l>etween  the 
vascular  laver  and  the  membrana  suprachoroidea.  On  antcro-i>osterior  section  the 
ciliary  body  is  triangular;  the  shortest  side  looks  ftirward,  and  from  about  its  mid- 
dle the  iris  arises;  the  two  long  sides  look  respectively  inwards  and  outwards,  the 
inner  having  the  ciliary  ])rocesses  upon  it,  while  the  outer  is  formed  by  th(^  ciliary 
muscle.  This  muscle  possesses  smooth  fibres  and  consists  of  an  outer  and  an  inner 
division;  in  the  outer  the  fibres  run  longitudinally,  inserted  into  the  outer  fibrous 
coat  of  the  eye  at  the  sclero-corneal  junction  in  front,  and  passing  backwards  to 
join  the  outer  lavers  of  the  orbiculus  and  choroid;  the  inner  contains  circularly  run- 
ning fibres  situated  next  to  the  ciliary  i)rocesses.  .Tlie  entire  muscle  is  destitute  of 
pigment,  and  therefore  is  recognisable  in  the  section  by  its  liglit  col<jur.     The  wiiole 


848  ORGAXS  OF  SPECIAL   SEXSE 

thickening  of  the  uveal  tract  in  this  region,  muscle  and  folds  and  processes  together, 
is  named  the  ciliary  body. 

The  iris  projects  into  the  interior  of  the  front  half  of  the  eye  in  the  form  of  a 
circular  disc  perft)rated  in  the  middle.  The  appearance  of  its  anterior  surface  has 
already  been  described.  Its  posterior  surface  exhiy)its  numerous  radial  folds  run- 
ning from  the  ciliary  ])rocesses  to  near  the  pupillary  border;  a  thick  layer  of  black 
pigment  covers  it  and  curls  round  its  inner  edge,  so  as  to  conie  into  view  all  round 
the  pupil  as  seen  from  in  front.  The  peripheral  or  ciliary  border  of  the  iris  is 
continuous  with  the  front  of  the  ciliary  body,  Avhere  it  also  receives  fibres  from  the 
ligamentum  pectinatum  iridis;  in  other  respects  the  iris  is  quite  free,  merely  resting 
on  the  front  of  the  lens-capsule  near  the  pupil.  Its  stroma  is  s})ongy  in  character, 
being  made  up  of  vessels  covered  by  a  thick  adventitia,  running  from  the  periphery 
to  the  pupillary  border,  with  interspaces  filled  by  branching  pigment  cells,  Avhich 
are  particularly  abundant  near  the  front  surface.  Deep  in  the  stroma,  running 
round  near  the  pupillary  border,  we  find  a  broad  flat  band  of  smooth  muscle  fibres, 
constituting  the  sphincter  iridis.  Immediately  behind  the  vascular  tissue  lies  a 
thin  membrane,  consisting  of  fine,  straight  filjres  running  radially  from  the  ciliary 
border  to  just  l)ehind  the  sphincter.  The  nature  of  these  fibres  has  long  been  in 
dispute,  but  they  are  now  accepted  as  being  undoubtedl}'  smooth  muscular,  a  dila- 
tor iridis. 

The  sphincter  iridis  and  the  ciliary  muscle  are  supplied  by  the  third  nerve,  and 
the  dilator  iridis  by  the  sympathetic,  all  by  Avay  of  the  ciliary  ganglion. 

Quite  posteriorly  is  the  pigment  already'  mentioned,  really  consisting  of  two 
layers  of  pigmented  cells,  each  layer  representing  the  extension  forwards  of  one 
subdivision  of  the  retina.  The  front  of  the  iris  is  covered  by  a  delicate  epithelial 
layer,  a  continuation  of  that  lining  Descemet's  membrane.  The  colour  of  the  iris 
in  different  individuals  dej^ends  upon  the  amount  of  stromal  pigment. 

3.  The  innermost  or  nervous  coat. — The  inner  surface  of  the  uveal  tract 
is  everywhere  hned  by  a  layer  of  i^igment  of  corresponding  extent,  which  usually 
adheres  to  it  closely  on  dissection.  Developmentally,  however,  this  general  pigment 
lining  is  quite  distinct  from  the  uveal  coat,  and  represents  the  outer  wall  of  the 
secondary  optic  vesicle  or  embryonic  retina:  it  consists  of  a  single  layer  of  pig- 
mented epithelial  cells.  The  amount  of  pigment  is  greatest  anteriorly,  over  the 
ciliary  region  and  iris,  and  there  is  again  a  small  local  increase  posteriorly,  corre- 
sponding to  the  macula  lutea  and  to  the  edge  of  the  optic  foramen.  In  the  ciliary 
region  these  cells  have  recently  been  described  as  lining  numerous  narrow  tubular 
depressions  in  the  inner  part  of  the  uveal  tract,  and-  they  seem  here  to  have  a 
special  function,  viz.  that  of  secreting  the  intraocular  fluids. 

From  the  manner  in  which  the  secondary  optic  vesicle,  or  optic  cup,  is  formed, 
its  two  walls  are  necessarily  continuous  in  front,  at  what  may  be  termed  the  lip  of 
the  cup;  we  have  just  observed  that  the  outer  wall  lines  the  uveal  coat  everywhere 
and  corresponds  in  extent;  consequently,  the  li])  nntst  be  looked  for  at  the  edge  of 
the  pupil,  i.e.  at  the  termination  of  this  coat  anteriorly.  The  inner  icalloi  the  cu]), 
consequently,  reaches  from  the  lip,  or  pupillary  edge,  in  front,  to  the  optic  stalk  or 
nerve  behind,  and  is  in  close  apposition  to  the  pigment-epithelium;  unlike  the  outer, 
however,  this  wall  is  represented  in  the  developed  eye  by  tissues  very  dissimilar  in 
structure  in  different  parts  of  its  extent.  Tracing  it  backwards  from  the  pupillary 
edge,  we  find  that  over  the  whole  posterior  surface  of  the  iris  it  exists  as  a  single 
layer  of  pigmented  epithelimn,  the  developmental  changes  having  here  produced  a 
result  similar  to  what  we  have  found  throughout  in  the  outer  wall:  here,  accord- 
ingly, we  have  a  double  layer  of  pigment  cells.  At  the  root  of  the  iris  the  single 
inner  layer  of  cells  still  exists;  but  now  they  become  destitute  of  pigment,  and  this 
condition  obtains  over  the  entire  ciliary  region,  constituting  what  is  known  as  the 
pars  ciliaris  retinae.  At  the  line  of  the  ora  serrata  the  tissue  derived  from  the 
imu-r  wall  a1)ruptly  increases  in  thickness,  and  rapidly  acquires  that  com])lexity  of 
structure  characteristic  of  the  retina  proper,  Avhich  ext<nids  from  here  to  the  optic 
nerve.  It  consists  of  several  layers — nerve-fibres,  nerve-cells,  and  nerve-epithelium — 
held  together  by  a  supporting  framcAvork  of  delicate  connective  tissue.  The  nerve- 
epithelium  is  on  the  outer  surface,  immediately  applied  to  the  pigment-epithelium; 
at  the  posterior  pole  of  the  eye  a  small  spot  (fovea  centralis;  exists,  where  this  is 


EXAMIXATIOX  OF   THE  EYEBALL 


849 


the  only  retinal  layer  re])resented,  and  where  consequently  tlie  retina  is  extremclv 
thin.  The  nerve-tiljres  run  on  the  inner  surface  of  the  retina  and  are  continuous 
with  those  of  the  optic  nerve;  they  constitute  the  only  retinal  layer  that  is  con- 
tinued into  the  intraocular  end  of  the  nerve.  The  nerve-cells  are  found  l^etween 
these  surface  layers.  The  larger  hlood-vessels  of  the  retina  run  in  the  inner  layers, 
and  none  encroach  on  the  layer  of  nerve-epithelium. 

Within  the  coats  mentioned,  the  interior  of  the  eyeball  is  fully  occupied  by  con- 
tents, which  are  divided  into  three  parts,  and  differently  named  according  to  their 
consistence  and  anatomical  form.  They  are  all  transparent,  as  through  them  the 
light  has  to  pass  so  as  to  gain  the  retina.  Of  these  the  only  one  that  is  shari)ly  and 
independently  outlined  is  the  lens, which  is  situated  in  the  anterior  half  of  the'glol)e 
at  the  level  of  the  ciliary  processes,  where  it  is  suspended  between  the  other  con- 
tents, which  fill  respectively  the  space  in  front  of  it  and  the  space  behind  it.     The 


Fig.  477. — Semi-diaorammatio  Horizontal  Pkctiox  TiiRoroii   Eyeball  and  Optic 
Nekve.     (Alter  Elfinger.     Keduced  and  altered.) 

Corneal  epithelium 
CORNEA 

; ,yX "^ 

CANAL  OF  SCHLEWy 

Ciliary  muscle 

,^^^e5^^^^^-V^  LENS  v^^^*^'*'^»^^\ 

CANAL  OF  PET;T 


RETL\A 


Central  retinal  vessel- 
OPTIC  NERV E- 
SUBSTASCI: 
PIAL  NERVE- 
SHEA  TH 


SCLEROTIC 

[covered  eiler- 
iiallyby  Tenon's 
capsule  anil 
loose  tisstm) 


D  IRA  L  yER  \  -E-SHEA  TH 


space  in  front  is  called  the  anterior  or  aqueous  chamber;  that  behind  the  lens  is  tbe 
vitreous  chamber. 

The  lens  is  a  biconvex  V)ody.with  its  surfaces  directed  anteriorly  and  posteriorly: 
these  surfaces  meet  at  its  rounded-oft'  edge  or  equator,  which  is  near  (but  does  not 
touch)  the  ciliary  processes  all  round.  The  posterior  is  considerably  mori"  convex 
than  the  anterior  surface;  the  central  part  of  each  surface  is  called  its  pole.  The 
lens  is  closely  encased  in  a  hyaline  elastic  capsule,  thicker  over  the  anterior  than 
over  the  posterior  surface.  Thus  enclosed,  it  is  held  in  position  in  the  globe  by  a 
suspensory  ligament,  attached  to  its  capsule  near  the  ecjuator  all  round,  and  swung 
from  the  ciliary  region.  Posteriorly,  the  lens  rests  in  a  cup  formed  ]»y  tbe  front  jtart 
of  the  vitreous,  while  its  anterior  capsule  is  in  contact  with  the  aqueous  fluid  and 
lies  close  against  the  back  of  tbe  pujiillarv  l)order  of  tbe  iris,  ^^'ben  in  j)osition 
the  lens  measures  nine  millimetres  across,  and  about  four  milHmetres  between  its 
poles.  On  eacb  surface  a  series  of  fine,  sinuous,  grey  lines  can  Ix^  seen  radiating 
from  the  pole  towards  the  equator,  called  respectivelv  tb*- anterior  and  posterior 
54 


SoO  ORGAXS  OF  SPECIAL  SENSE 

stellate  figures.  The  lines  observable  on  the  posterior  are  always  so  placed  as  to 
l)e  internifdiale  with  those  on  the  anterior  surface,  so  that  on  viewing  them  through 
the  lens  they  occupy  a  position  corresponding  to  the  intervals  between  the  lines  on 
the  anterior  surface.  The  lens-capsule  is  comparatively  brittle,  and  can  be  readily 
cut  through  when  scraped  with  a  sharjvpointed  instrument;  on  doing  so  the 
divided  edges  curl  outwards,  away  from  the  lenticular  substance.  When  removed 
from  its  capsule,  the  outer  portion  of  the  lens  is  found  to  be  soft  and  glutinous,  but 
its  substance  gets  progressively  firmer  as  we  approach  the  centre.  This  harder 
central  partis  known  as  the  nucleus,  and  the  surrounding  softer  matter  as  cortex. 
The  cortical  part  shows  a  tendency  to  peel  off  in  successive  layers.  It  consists  of 
long  fibres,  the  ends  of  which  meet  in  front  and  behind  at  the  anterior  and  posterior 
stellate  figures. 

Histologically  the  capsule  is  not  in  immediate  contact  with  the  cortex  over  the  front  surface 
of  the  lens,  a  single  laj-er  of  cells  intervening,  called  the  subcapsular  epithelium. 

The  suspensory  ligament  of  the  lens  is  formed  by  a  thickening  of  the  ante- 
rior part  of  a  membrane  enclosing  the  vitreous,  strengthened  by  numerous  fibres 
derived  from  the  folds  of  the  ciliary  region.  Its  chief  attachments  to  the  lens-capsule 
are  a  little  in  front  of  and  behind  the  equator,  and  the  space  included  between 
the  most  anterior  and  most  posterior  divisions  of  the  ligament  is  termed  the  canal 
of  Petit.  This  space  is  bridged  across  l)y  fine  intermediate  suspensory  fibres,  and 
is  occupied  by  fiuid. 

The  vitreous  humour  is  a  transparent,  colourless,  jelly-like  mass,  enclosed  in  a 
delicate,  clear,  structureless  membrane,  called  the  hyaloid  membrane.  This  latter 
is  closely  applied  to  the  back  of  the  posterior  lens-capsule  and  of  the  suspensory 
ligament,  and  to  the  inner  surface  of  the  pars  ciliaris  retinae,  retina  proper,  and 
optic  papilla.  Although  possessing  some  degree  of  firmness,  the  vitreous  humour 
contains  quite  98  per  cent,  of  water,  and  has  no  definite  structure.  Membranes 
have  been  described  in  it,  but  these  are  really  artificial  products.  In  certain  situa- 
tions spaces  exist  in  the  vitreous  mass,  the  most  determinate  of  which  runs  in  the 
form  of  a  canal  from  the  optic  papilla  to  the  posterior  pole  of  the  lens,  corre- 
sponding to  the  position  of  the  foetal  hyaloid  artery  (hyaloid  canal,  or  canal  of 
Cloquet).  Other  very  fine  spaces  are  described  running  circularly  in  the  peri])heral 
part  of  the  vitreous  concentric  with  its  outer  surface.  Microscopically,  wandering 
cells  are  found  in  the  vitreous,  which  often  here  assume  peculiar  forms  which  the 
observer  can,  not  infrequently,  study  subjectively. 

The  aqueous  humour  is  a  clear,  Avatery  fluid,  occupying  the  space  between 
the  cornea  on  the  one  hand,  and  the  ciliary  body,  suspensory  ligament,  and  lens  on 
the  other.  The  iris,  projecting  into  this  space,  has  both  its  surfaces  bathed  in  the 
aqueous;  but,  as  its  inner  part  rests  on  the  lens,  it  is  regarded  as  dividing  the 
space  into  two  parts,  an  anterior  larger,  and  a  posterior  smaller  aqueous  cham- 
ber, which  communicate  freely  through  the  pupil. 

Ciliary  nerves  of  the  eyeball. — The  long  and  short  ciliarj'^  nerves,  after  per- 
forating the  sclerotic,  run  forward  between  it  and  the  choroid  to  the  ciliary  region, 
where  they  form  a  plexus,  from  which  proceed  branches  for  the  ciliary  muscle,  the 
iris,  and  the  cornea.  The  nerves  of  the  iris  enter  it  at  its  ciliary  border,  and  run 
towards  its  pupillary  edge,  losing  their  medullary  sheath  sooner  or  later,  and 
supplying  specially  the  s{)hincter  muscle.  The  corneal  nerves  form  an  annular 
plexus  near  the  limbus,  from  Avhich  a  few  twigs  proceed  to  the  sclerotic  and  con- 
junctiva, while  most  of  the  offsets  enter  and  run  radially  in  the  corneal  stroma, 
branching  and  anastomosing  so  as  to  form  a  plexus.  The  nerves  entering  the  cornea 
are  about  sixty  in  number,  each  containing  from  two  to  twelve  non-medullated 
nerve-fibres  (page  758). 

Blood-vessels  of  the  eyeball. — The  ocular  tissues  receive  blood  from  two  sets 
of  vessels,  viz.  tlie  retinal  and  the  ciliary  arteries. 

1.  The  arteria  centralis  retinae  either  comes  direct  from  the  ophthalmic  artery, 
or  from  one  of  its  branches  near  the  a]iex  of  the  orhh.  Entering  the  optic  nerve 
twenty  millimetres  or  less  behind  the  globe,  it  runs  forward  in  its  axis  to  the  end  of 


EXAMINATION  OF   THE  EYEBALL  851 

the  nerve-tmnk,  iind  tlu-n  divides  into  branches  which  run  in  the  inner  layers  of  the 
retina,  and  divide  dicliotoniously  as  they  radiate  towards  tlie  equator.  The  smaller 
branches  lie  more  deeply  in  the  retina,  Imt  none  penetrate  into  the  nerve-epithelium, 
so  that  the  fovea  centralis  is  non-vascular.  In  the  retina,  the  branches  of  the  cen- 
tral artery  do  not  comnmnicate  with  any  other  arteries,  Ijut  while  still  in  the  oijtic 
nerve  fine  communications  take  place  between  this  artery  and  neighl)ouring  vessels. 
Thus  (a)  minute  twigs  from  it,  which  hel])  to  nourish  tlie  axial  part  of  the  nerve 
communicate  with  those  running  in  the  septa  derived  from  the  pial  sheath.  Again,' 
as  the  nerve  passes  through  the  sclerotic,  it  is  surrounded  by  a  vascular  ring  (circle 


Fig.  478.— DiAGR.VMJi.vnc  Representation  of  the  Blood-ve.ssei>s  of  the  Eyeball. 

(Leber.) 

Arteries  rerf;  veiiis  Wwe. 


Canal  of  Schlentm  and  con- 

nections  with  anterior 

ciliary  vein 

Branch  from  ciliary  body  to 

anterior  ciliary  vein 


Cessels  of  ciliary  processes 

Vein  from  iris  and  ciliory 
body  to  vena  rorticosa 


Branch  from  short  posterior 
ciliary  artery  to  optic  nerve 


Short  posterior  ciliary  artery_ 


I'ena  centralis  retince 


Jfarffinal  corneal  plexus 

Ttnlerior  conjunctival  vein 

Cireulus  iridis  major 
Posterior  conjunctival  vein 


Anterior  ciliary  vein 

Posterior  conjunctival 

artery 
A  nierior  ciliary  artery 


Episcleral  vein 
Episcleral  artery 


I'ena  vorticosa 

Posterior  long  ciliary  artery 
Posterior  short  ciliary  arteries 

Vessels  of  pial  sheath  of  optic  nerve 
Vessels  of  dural  sheath 

Arleria  centralis  retince 


of  Haller),  formed  of  fine  branches  derived  from  the  short  jnj.sterior  ciliary  arteries; 
fine  twigs  ]jassing  inwards  from  this  ring  to  the  optic  nerve,  join  the  vessels  of  the 
pial  sheath,  and  (b)  an  indirect  communication  is  thus  l)rought  about  between  the 
retinal  and  ciliary  vessels.  Finally,  as  the  nerve  passes  througii  the  choroid,  there 
is  (c)  a  direct  connection  between  these  two  sets  of  vessels,  the  cajiillary  network  of 
the  optic  nerve  being  here  continuous  with  the  chorio-ca))illaris.  Not  infre(|uently, 
a  branch  from  a  short  posterior  ciliary  artery  ])ierces  the  ojitic  jiapilla,  and  then 
courses  over  the  adjoining  retina  (a  cilio-retinal  artery),  supplying  the  latter  in  part 
in  place  of  the  central  artery. 


852 


OBGANS  OF  SPECIAL   SEXSE 


The  vena  centralis  retinae  returns  the  blood  of  the  corresponding  artery, 

2.  The  ciliary  system  of  blood-vessels  (pafi;es500,  501,  and  ()25j. — There  are 

three  sets  of  arteries  belonging  to  this  s}'steni,  all  derived  directly  or  indirectly 

from  the  ophthalmic  artery. 

(1)  Short  posterior  ciliary  arteries,  twelve  to  twenty  in  number,  pierce  the 
sclerotic  round  tlie  optic  nerve  entrance,  and  are  distributed  in  tlie  choroid. 
Before  entering  the  eyeball,  small  twigs  are  given  off  to  the  adjoining  sclerotic  and 
to  the  dural  sheath  of  the  optic  nerve. 

(2)  Two  long  posterior  ciliary  arteries,  piercing  the  sclerotic  further  from  the 
nerve  than  the  short  ciliaries,  run  horizontally  forwards  between  the  sclerotic  and 
choroid,  one  on  each  side  of  the  globe.  On  arriving  at  the  ciliary  body,  they 
join  with  the  anterior  ciliary  arteries,  forming  the  circulus  iridis  major,  which 
sends  off  branches  to  tlie  ciliary  processes  and  the  iris.  The  long  ciliaries  also 
give  twigs  to  the  ciliary  muscle,  and  small  recurrent  branches  run  backwards  to 
anastomose  Avith  the  short  ciliary  arteries.  The  arteries  of  the  iris  run  radially  to 
the  })upillary  ]»order,  anastomosing  with  one  another  oj^posite  the  outer  border  of 
the  sphincter  so  as  to  form  the  circulus  iridis  minor. 

(3)  The  anterior   ciliary  arteries   come  from  the  arteries  of  the  four  recti 


Fig.  479. — Surface  of  Choroid  and  Iris  exposed  by  removal  of  Sclerotic  and 
Cornea,  showing  Distribution  of  Blood-vessels  and  Nerves. 

(Twice  natural  size.     After  Zinn.) 


A  CILIARY  NERVh 


SURFACE  OF  CHOROID  IN 
CILIARY  REGION 


A  CILIARY  NERVE 

Long  posterior  ciliary 
artery 


FLAP  OF  SCLEROTIC, 
REFLECTED 


muscles,  one  or  two  from  each;  they  run  forwards,  branching  as  they  go,  and 
finally  pierce  the  sclerotic  near  the  corneal  border.  Outside  the  globe  they  send 
twigs  to  the  adjoining  sclerotic,  to  the  conjunctiva,  and  to  the  border  of  the  cornea. 
After  passing  through  the  sclerotic  the  arteries  enter  the  ciliary  muscle,  where  they 
end  in  twigs  to  the  muscle  and  to  the  circulus  iridis  major,  and  recurrent  branches 
to  the  choroid. 

Veins. — The  venous  blood  from  almost  the  whole  uveal  tract  (choroid,  ciliary 
processes  and  iris,  and  part  of  the  ciliary  muscle)  ultimately  leaves  the  eyeliall  by 
(1)  the  venae  vorticosae,  which  have  been  already  noticed  in  describing  an  antero- 
posterior section  through  the  globe.  One  large  vein  passes  backwards  from  each 
vortex,  piercing  the  sclerotic  obliquely;  it  is  joined  by  small  ei)iscleral  veins  when 
outside  the  glol)e. 

(2)  The  anterior  ciliary  veins  commence  by  the  junction  of  a  few  small  veins 
of  tiie  ciliary  muscle;  they  pass  outwards  through  the  sclerotic  near  the  corneal 
border,  receiving  blood  from  the  veins  in  connection  with  Schlemm's  canal,  and 
afterwards  from  episcleral  and  conjunctival  veins,  and  from  the  marginal  corneal 
plexus.      Finally  tliey  join  the  veins  running  in  the  recti  muscles. 

Lymphatic  system  of  the  eyeball. — A])art  from  those  in  the  conjunctiva 


EXAmNATION  OF  THE  EYEBALL 


853 


there  are  no  lymphatic  vessels  in  the  eyeball,  but  the  fluid  is  contained  in  spaces  of 
various  sizes.     Tlicse  are  usually  divided  into  an  anterior  and  a  posteri<jr  set. 

1.  Anteriorly,  we  have  the  anterior  and  posterior  aqueous  chambers,  which 
communicate  freely  through  the  pui)il.  The  aqueous  humour  is  secreted  in  tlie 
posterior  of  these  chambers,  from  the  vessels  of  the  ciliary  body  and  posterior 
surface  of  the  iris  (see  also  page  849).  The  stream  passes  mainly  forwards  througli 
the  pu])il  into  the  anterior  aqueous  chamber,  whence  it  escapes  slowly  bv  passing 
througli  tlie  s})aces  of  Fontana  into  Schlemm's  canal,  and  thence  into  the  anterior 
ciliary  veins.  Part  of  the  lymph-stream  passes  from  the  posterior  aqueous  cham- 
ber backwards  into  the  canal  of  Petit,  out  of  which  fluid  can  pass  into  the  lens 
substance,  or  diffuse  itself  into  the  front  of  the  vitreous. 

In  the  cornea  the  lymph  travels  in  the  spaces  already  mentioned  as  existing 
between  the  fibre-bundles,  and  in  the  nerve-channels,  and  at  the  periphery  of  the 
cornea  it  flows  off  into  the  lym})]iatic  vessels  of  the  conjunctiva. 

Fig.  480. — Thk  Lymphatics  of  thi-:  Eyeball.     (Diagrammatic.     After  Fuchs.) 


Anterior  cilhtri/  rein 

CANAL  OF   SCHLEMM 


PROLONGATION     OF    TENON'S 
CAPSULE  ON  TENDONS 


PERICHOROIDAL  SPACE 
HYALOID  CANAL 


SPACE  ROUND  VENA  VORTICOSA 
COMMUNICATING  WITH  THE 
PERICHOROIDAL  SPACE  AND 
TENON'S     SPACE 

TENONS    SPACE 


SUPRAVAGINAL    SPACE 


INTERVAGINAL    SPACE 


In  the  iris  there  is  a  system  of  lymphatic  spaces  opening  anteriorly  on  its 
free  surface  by  the  crypts  previously  described,  and  communicating  peripherally 
Avith  the  spaces  of  Fontana. 

2.  Posteriorly,  we  have  (a)  the  central  or  hyaloid  canal,  lietween  the  ]tostt*- 
rior  pole  of  the  lens  and  the  optic  nerve  entrance,  and  {b)  the  perivascular  canals 
of  the  retina;  the  lymph  from  both  of  these  situations  flows  into  the  spaces  of  the 
optic  nerve,  which  communicate  with  the  intervaginal  space  of  the  nerve,  and  thus 
with  the  great  intracranial  spaces.  Further,  between  choroid  and  sclerotic,  we 
have  (c)  tlie  ])erich()roidal  si)ace,  which  gets  the  lym]>h  from  the  choroid,  and 
communicates  with  Tenon's  space  outside  the  sclerotic  by  the  jierforations  corre- 
sjionding  to  the  vasa  vorticosa  and  posterior  ciliary  arteries,  and  with  the  interva- 
ginal space  around  the  optic  ncn-e  entrance.  Tenon's  space,  again,  is  continuous 
with  the  supravaginal  space  around  the  optic  nerve,  which  communicates  l)oth 
with  the  intervaginal  spaces,  with  the  lym])h  spaces  of  the  orbit,  and  directly  with 
the  intracranial  spaces  at  the  apex  of  the  orltit. 


854 


ORG  ASS  OF  SPECIAL   SEXSE 


CAVITY  OF  THE  ORBIT 

General  Arrangement  of  its  Contents 

The  anterior  wider  half  of  the  cavity  is  mainly  occu])ie<l  by  the  eyel)all,  -which 
lies  almost  axially,  but  is  rather  nearer  to  the  upper  and  outer  than  it  is  to  the 
other  walls.  The  posterior  two-thirds  of  the  globe  are  in  relation  with  soft  parts, 
chiefly  muscles  and  fat,  and  its  posterior  pole  is  situated  midway  lietween  the  base 
(or  opening)  and  the  apex  of  the  orbital  cavity.  The  anterior  third  of  the  eye- 
ball is  naturally  free,  except  for  a  thin  covering  of  the  conjunctiva,  and  projects 
slightly  beyond  the  opening  of  the  orbit,  the  degree  of  prominence  varying  with 
the  amount  of  orbital  fat,  and  also  to  some  extent  with  the  length  of  the  globe.  A 
straight  line  joining  the  inner  and  outer  orbital  margins  usually  cuts  the  eye  behind 
the  cornea — externally  behind  the  ora  serrata,  nasally  further  forward,  at  the 
junction  of  the  ciliary  body  and  iris.  The  globe  is  held  in  position  by  numerous 
bands  of  connective  tissue.     The  lachrymal  gland  lies  under  the  outer  part  of  the 


Fig.  481.  — Left  Eyebai.l  seen  in  its  Normal  Position  in  the  Orbit,  with  Yikw 
OF  THE  Ocular  Muscles.     (After  Merkel,  uuHlified.) 

Tendon  of  superior  oblique 


Levator  palpebrae  super- 

ioris,  cut 
Superior  rectus 


Inernal  rectus 


Inferior  oblique  muscle 


External  rectus 


Inferior  rectus 


roof  of  the  orbit  anteriorly.  The  orbital  fat  occupies  the  spaces  between  the  orl)ital 
muscles,  and  is  in  greatest  amount  immediately  behind  the  eyeball;  it  also  exists 
between  the  muscles  and  the  orbital  walls  in  the  anterior  half  of  the  cavity.  Six 
muscles,  viz.  the  four  recti,  the  superior  oblique,  and  the  levator  pali)ebr£e  supe- 
rioris,  arise  at  the  apex  of  the  orbit,  and  diverge  as  they  pass  forwards.  The  recti 
muscles — superior,  inferior,  external,  and  internal — run  each  near  the  correspond- 
ing orl)ital  wall,  but  the  superior  is  overlapped  in  part  by  the  levator  palpebne. 
The  superior  oV)li(|ue  lies  about  midway  between  the  superior  and  internal  recti. 
A  seventh  muscle,  the  inferior  oblique,  has  a  short  course  entirely  in  the  anterior 
part  of  the  orbit,  coming  from  its  inner  wall  and  passing  beneath  the  globe  ])etween 
the  termination  of  the  inferior  rectus  and  the  orbital  floor.  The  optic  nerve  with 
its  sheaths  passes  from  the  o])tic  foramen  to  the  back  of  the  ej'-eball,  surrounded  by 
the  orbital  fat,  and  more  immediately  by  a  loose  connective  tissue.  Among  the 
contents  of  the  cavity  are  also  to  he  enumerated  many  vessels  and  nerves,  and 
flbrous  tissue  septa,  Avhile  its  walls  are  clothed  by  periosteum  (periorbita). 

The  muscles  of  the  orbit  are  seven  in  number,  of  which  six  are  omhtr,  i.e.  arc 
inserted  into  the  eveljall  and  rotate  it  in  different  directions.     Tliese  ocular  muscles 


CAVITY   OF   THE   OB  JUT 


S55 


are  arranged  in  opponent  pairs,  viz.  superior  and  inferior  recti,  superior  and 
inferior  obliques,  external  and  internal  recti.  With  the  excej.tion  oi  the  short 
inferidi-  ohliiiuc  they  all  arise  from  th<-  liack  of  the  orhit  along  with  the  seventh 
orhital  muscle,  the  elevator  of  the  upper  lid.  All  these  hmg  niuseles  take  tlieir 
origin  from  the  periosteum  in  the  viciinty  of  the  <i])tic  foramen.  The  f(nir  recti 
muscles  arise  from  a  tihrous  ring,  which  arches  close  over  the  ujtper  and  inner  edge 
of  the  foramen,  and  extends  down  and  out  so  as  to  embrace  part  of  the  opening  of 
the  sphenoidal  fissure.  Their  origins  may  be  said  at  first  to  form  a  short,  com- 
mon, tendinous  tube,  from  which  the  individual  muscles  soon  separate,  taking 
the  positions  indicated  by  their  respective  names.  The  external  rectus  has  two 
origins  from  bone,  one  on  either  side  of  the  sphenoidal  fissure.  But  in  the  fresli 
state  the  fissure  is  here  bridged  across  by  fibrous  tissue,  from  which  this  rectus 
also  springs,  so  that  its  origin  is  in  reality  continuous.     The  part  of  this  fibrous 


Fio   43-3.— Section  through  Contexts  of   Khjht  Orbit  8-11   mm.  behixd  the   Eyeball, 
VIEWED  FROM  BEHIXD.      (After   Lauj^e.) 


SUPRA  OR  RITAL 
NERVE 

Supraoibilal  artery 

Levator  palpebrae 
Buperiori3  ruuucle 


Superior 
rectus  muscle 


LAr/finMAL 

SERVE 
Lachrymal  ardry 


—   Lachrymal  vein 
Ojjhthal/iiic  vein 


Nasn-fronlid 
artery 

OPTIC  NER  VE 

Ciliary  arterii 
Central  retinal 
artery 
Ciliary  artery 


Inferior  rectus 
muscle 


Ciliary  artery 


External  rectus 
muscle 


(iiiury  artery 


—  Tllinn   SERVE 
{ERA  sen    W 
ISFERIOR 
ORLiqiE 
ML.SCLE) 


ring  nearest  the  foramen  (corresponding  to  the  origins  of  the  superior  and  internal 
recti)  is  closely  connected  with  the  outer  sheath  of  the  optic  nerve.  The  remain- 
ing two  long  muscles  arise  just  outside  the  upper  and  inner  part  of  the  above- 
mentioned  ring,  and  are  often  partially  united;  the  levator  palpe])rte  tendon  is  in 
close  relation  to  the  origin  of  the  superior  rectus,  while  the  superior  ol)li<iue  arises 
from  the  perio.steum  of  the  body  of  the  sphenoid  bone  one  or  two  millimetres  in 
front  of  the  origin  of  the  internal  rectus. 

The  four  recti  muscles  lie  rather  close  to  the  corresponding  orbital  walls  for  the 
first  half  of  their  course,  the  superior  rectus,  however,  being  overlapped  in  jiart  by 
the  levator  palpebra:*;  they  then  turn  towards  the  eyeball,  running  obli(|Uely 
through  the  orbital  fat,  and  are  finally  inserted  by  broad,  thin  tendons  into  the 
sclerotic  in  front  of  the  equator.  The  thickest  of  these  muscles  is  the  internal 
rectus,  next  the  external,  then  the  inferior,  and  the  superior  rectus  is  the  thinnest. 


856  ORGANS  OF  SPECIAL  SENSE 

As  regards  length,  the  muscular  belly  of  the  superior  rectus  has  the  longest  course, 
and  the  others  dmnnish  in  the  order — internal,  external,  and  inferior  rectus.  The 
external  rectus  is  supplied  by  the  sixth  nerve.  The  other  three  recti  muscles  are 
all  supplied  by  the  third  nerve. 

The  levator  palpebrae  superioris  courses  along  the  roof  of  the  orbit  close  to 
the  periosteum  for  the  greater  part  of  its  course,  partially  overlajiping  the  superior 
rectus;  it  finally  descends  through  the  orbital  fat,  and  widens  out  to  be  inserted 
into  the  root  of  the  upper  lid.  It  may  be  briefly  descriljed  as  being  inserted  in  two 
distinct  layers  separated  by  a  horizontal  interval.  The  upper  or  anterior  layer  of 
insertion  is  fibrous,  and  passes  in  front  of  the  tarsus,  Avhere  it  comes  into  relation 
with  fibres  of  the  orbicularis.  The  lower  layer  consists  of  smooth  muscle  (Miiller's 
superior  palpebral  muscle)  and  is  inserted  along  the  upper  border  of  the  tarsus. 
The  levator  has  also  connections  with  the  sheath  of  the  superior  rectus.  These 
different  insertions  of  the  muscle  will  be  referred  to  later  along  Avith  the  description 
of  the  orbital  fasciae  and  of  the  upper  eyelid.  It  gets  its  nervous  supply  from  the 
third  nerve,  but  the  smooth  muscle  developed  in  its  lower  layer  of  insertion  is  sup- 
plied by  the  sympathetic  nervous  system.  As  its  name  expresses,  its  action  is  to 
raise  the  U|)per  lid  and  to  support  it  while  the  eye  is  open. 

The  superior  oblique  runs  forward  close  to  the  inner  part  of  the  orbital  roof 
until  it  reaches  the  fossa  trochlearis  near  the  internal  angular  process,  where  it 
becomes  tendinous  and  passes  through  a  fibro-cartilaginous  pulley  attached  to  the 
fossa  just  named.     On  passing  through  this  pulley,  or  trochlea,  the  tendon  bends 


Fig.  483. — Diagrammatic  Repeesentation  of  Origins  of  Ocular  Muscles  at  the  Apex 

OF  THE  Right  Orbit. 
(After  Schwalbe,  slightly  altered.) 


Superior  rectus 
FOURTH  SERVE 


Lachrymal  ana 


Levator  palpebrae  superioris 


d  frontal  vein  __\,i-_j[    ^^%\T^~  Superior  oblique 

from    fibrous ^^^#v,    ^% OPTIC  FORAMEX  AXD 

1  fissure  _E-®    ^^^     I'/ 


Origin    of    external   rectus  from    fibrous ^^fy^,    V^^rT^ OPTIC  FOR  \  VEX  A  XD  NER  VE 

bridge  over  sphenoidal  " -^^ 

ya.-iu-ciliary  of  fifth  nerve Z^^  ©^^-o"  Internal  rectus 

SIXTH  NERVE  "^"^       /     ^l"'^  ^\ 

/  \  N  Inferior  rectus 

External  rectus       THIRD  NERVE 


at  an  angle  of  50°,  running  backwards  and  outwards  under  the  superior  rectus  to 
its  insertion  into  the  sclerotic.      It  is  supplied  by  the  fourth  nerve. 

The  inferior  oblique  arises  from  the  front  of  the  orbit,  about  the  junction  of  its 
inner  and  lower  walls,  just  external  to  the  lower  end  of  the  lachrymal  groove.  It 
runs,  in  a  sloping  direction,  outwards  and  backwards,  lying  at  "first  between  the 
inferior  rectus  and  the  orbital  floor,  then  between  the  external  rectus  and  the  globe; 
finally  it  ascends  slightly,  to  l)e  inserted  by  a  short  tendon  into  the  sclerotic  at  tlie 
back  of  the  eye.  Its  nervous  supply  is  derived  from  the  third  nerve.  The  precise 
manner  of  insertion  of  the  different  ocular  muscles  has  been  described  above  in  our 
Examination  of  the  Eyeball.  (For  INIuscles  of  the  Eyelids  and  Eyebrows,  see 
pages  429  and  following. ) 

Action  of  the  ocular  muscles. — While  rotating  the  globe  so  that  the  corneals 
turned  in  different  directions,  the  ocular  muscles  do  not  alter  the  position  of  the 
eyeball  in  the  orbit  either  laterally,  vertically,  or  antero-posteriorly.  In  speaking, 
therefore,  of  the  eye  being  moved  upwards,  or  outioards,  etc. ,  it  is  the  altered  position 
of  the  cornea  or  front  of  the  eye  that  we  mean  to  express;  it  is  manifest  that,  if  the 
cornea  moves  up,  the  back  of  the  eyeball  must  simultaneously  be  depressed,  and 
similarly  with  other  movements.  All  the  movements  of  the  globe  take  i)lace  by  rota- 
tion, on  axes  passing  through  the  centre.  Though  the  possible  axes  are  numerous 
in  combined  muscular  action,  there  are  three  principal  axes  of  rotation  of  the  eye- 
ball, and  in  reference  to  these  the  action  of  individual  nniscles  must  be  described. 
Two  of  these  axes  are  horizontal,  and  one  vertical;  they  all  pass  through  the  centre 


CAVITY   OF   THE   ORBIT 


857 


of  rotation  at  right  angles  to  one  another.  By  rotation  of  the  eye  on  its  vertical 
axis  the  cornea  is  moved  outwards  (towards  the  temple),  and  inwards  (towards  the 
nose):  movements  called  respectively  abduction  and  adduction.  In  upward  and 
downward  movements  of  the  cornea,  the  eye  rotates  on  its  liorizontal  (Mjuatorial 
axis.  The  other  ])rincipal  axis  of  rotation  is  the  sagittal,  which  we  liave  i>revi()usly 
described  as  corresponding  to  the  line  joining  the  anterior  and  ])osterior  i)olesof  the 
globe  (page  843).  In  rotation  of  the  eye  on  its  sagittal  axis,  therefore,  the  cornea 
may  be  said  to  move  as  a  wheel  on  its  axle,  for  its  centre  now  corresj)onds  to  one 
end  of  the  axis;  in  other  words,  this  is  a  rotation  of  the  cornea.  Such  movements 
may,  consequently,  be  expressed  with  reference  to  their  effect  on  an  imaginary 
spoke  of  the  corneal  wheel — e.g.  one  running  vertically  upwards  from  the  corneal 
centre.  Thus  we  may  say  'rotation  of  the  cornea  outwards'  when  this  part  of  the 
wheel  moves  towards  the  outer  canthus,  or  '  inwards '  when  towards  the  nose. 

The  only  two  muscles  that  rotate  the  eyeball  merely  on  one  axis  are  the 
external  rectus  nnd  the  internal  rectus  ;  the  former  abducting,  and  the  latter 
adchictiuii;  the  cornea. 


f'iG.  484. — View  of  Left  Orbit  feom  above,  showing  the  Ocilar  Miscles. 
(From  Hirschfeld  and  Leveille.) 


Internal  rectus  muscle 


Superior  oblique  muscle 


Trochlea 


Levator  palpebrae  superioris 
muscle,  cut 


External  rectus  muscle 

Inferior  oblique  muscle 
Superior  rectus  muscle 


Levator  palpebrae  superioris 
muscle,  cut 


The  chief  action  of  the  superior  rectus  is  to  draw  the  cornea  uj^wards,  but  at 
the  same  time  it  adducts  and  rotates  the  cornea  inwards. 

The  inferior  rectus  mainly  draws  the  cornea  downwards,  also  adducting  it  and 
rotating  it  outwards. 

The  chief  action  of  the  superior  oblique  is  to  rotate  the  cornea  inwards,  also 
drawing  it  downwards  and  sliglitly  alKlucting  it. 

Tlie  inferior  oblique  mainly  rotates  the  cornea  outwards,  also  drawing  it 
upwards  and  slightly  abducting  it. 

The  fasciae  of  the  orbit. — The  orbital  contents  are  bound  together  and  sup- 
ported by  fibrous  tissues,  which  are  connected  with  each  other,  but  Avhich  may 
conveniently  be  regarded  as  belonging  to  three  systems.  These  are:  (1)  Those 
lining  the  bony  walls;  (2)  those  ensheathing  the  muscles;  and  (3)  the  tissue  which 
partially  encapsules  tlio  eyol)all. 

1.  The  orbital  periosteum,  or  periorbita,  is  closely  appli id  totlie  I)oncs  form- 
ing the  walls  of  the  cavity,  but  may  be  stripped  off  with  coin]>arative  ease.  It 
presents  openings  for  the  passage  of  vessels  and  nerves  entering  and  leaving  tlie 
orbit.  Posteriorly  tliis  tissue  is  very  firm,  being  joined  by  jirocesses  of  the  dura 
mater  at  the  optic  canal  and  sphenoidal  fissure;  at  the  optic  foramen  it  is  also 


858 


ORGANS  OF  SPECIAL   SENSE 


connected  -with  the  dural  sheath  of  the  optic  nerve.  As  it  covers  thespheno- 
niaxillarv  ti?;sure  its  fibres  are  interwoven  with  smooth  muscle,  forming  the  orbital 
muscle  of  Miiller.  From  its  inner  surface  processes  run  into  the  orbital  cavity, 
separating  the  fat  lobules.  One  imi)ortant  process  comes  from  the  periorbita  al)out 
midway  along  the  roof  of  the  orbit,  runs  forward  to  the  back  of  the  ui)per  division 
of  the  lachrymal  gland,  and  there  splits,  helping  to  form  the  gland-capsule:  this 
capsule  is  joined  at  its  inner  border  by  other  periorbital  bands  coming  off  near  the 
upper  orbital  rim,  and  forming  the  suspensory  ligament  of  the  gland.  On  the 
inner  side  of  the  orbit  the  periorbita  sends  fibrous  processes  to  the  trochlea  of  the 
superior  oblique,  which  keep  it  in  position.  On  arriving  at  the  lachrymal  groove 
the  periorbita  divides  into  two  layers,  a  thin  posterior  one  continuing  to  line  the 
bone  forming  the  floor  of  the  groove,  whilst  the  thicker  anterior  layer  bridges  over 


Fig.  485. — Vertical  Sectiox  through  the  Eyeball  and  Orbit  in  the  direction  of 
THE  Orbital  Axis,  with  Closed  Eyelids. 

(Semi-diagrammatic.     After  Schwalbe,  modified  to  show  fasciae.) 
Periorhita  green;  muscle-fascia  red ;  Tenon's  capsule  yellow. 


SKIN  OF  LOWER  LID 

LOWER  TARSUS 

Palpebral   faaeia   and 

ant.  lamina  of  musole- 

fascia 

Orbicularis  palpe- 
brarum 
Extension  of  sheath  of 
inferior  rectus  to 
lower  eyelid 


FORNIX  CONJUNCTI 


Inferior  oblique  muscle, 
cut  across 


Posterior  lamina  of 
muscle-fascia 


SUPRAVAGINAL    SPACE   CONTINUOUS 

WITH  TENON'S  SPACE 
SPACE  OCCUPIED  BY  ORBITAL  FAT,  PRO- 
CESSES OF  FASCIA  SEPARATING  THE 
LOBULES     AND    ENCLOSING     BLOOD- 
VESSELS 

Inferior  rectus 


SKIN   OF  UPPER  LID 

UPPER  TARSUS 

CORNEA 

Orbicularis  palpe- 
brarum 

UPPER  R!M  OF  ORBIT,  WITH 
Splitting  of  periorbita 
Upper  or  anterior  insertion 

of  levator  palpebrae 
Superior  palpebral  muscle  of 
FORNIX  CONJUNCTIV/t         [Miiller 

Connection  betTveen  levator 
palpebrae  and  sup.  rectus, 
and  fibres  to  conjunctiva 

PROCESS  FROM    PERIORBITA   TO 
CAPSULE  OF  LACHRYMAL  GUND 


Superior  rectus 


Levator  palpebrae 
superioris 
Posterior  lamina  of  muscle- 
fascia  lined  by  prolongation  of 
Tenon's  capsule 


OPTIC  NERVE 


the  groove  and  the  sac  which  lies  in  it,  forming  the  limbs  of  the  inner  palpebral 
ligament  (page  867). 

Quite  anteriorly,  at  the  rim  of  the  orbit,  the  periorbita  sends  off  a  membranous 
process  which  aids  in  forming  the  fibrous  tissue  of  the  eyelids  (orbito-tarsal  liga- 
ment, or  palpebral  fascia),  and  is  itself  continuous  with  the  periosteum  of  the 
bones  outside  the  orbital  margin. 

2.  The  orbital  muscles  are  connected  by  a  common  fascia,  which  splits  at  their 
borders  and  furnishes  a  sheath  to  each.  Processes  of  this  fascia  give  membranous 
investments  for  the  vessels  and  nerves  (including  the  optic  nerve),  splitting  similarly 
to  enclose  them;  these  membranous  processes  also  assist  in  separating  the  fat 
lobules.  Posteriorly,  this  fascia  is  thin  and  loose,  and  blends  with  the  periorbita  at 
the  origin  of  the  muscles.  Anteriorly,  it  becomes  thicker  and  firmer,  accompanies 
the  muscles  to  near  tlie  equator  of  the  eyeball,  and  there  divides  into  two  lamina^ 


CAVirr  OF  THE   ORBIT 


859 


an  anterior  and  a  posterior;  the  former  continues  a  forward  course,  forming  a 
complete  funnel-shaped  investment  all  round,  passing  ultimately  to  the  eyelids  and 
or))ital  margin — whilst  the  latter  turns  backwards,  covering  the  hinder  third  of  the 
globe. 

The  anterior  lainlna  is  a  well-marked  membrane  everywhere,  liut  in  certain 
situations  it  presents  si)ecial  bands  of  thickening,  corresponding  to  the  direct  c(»n- 
tinuation  forwards  of  the  sheath  of  each  rectus  n)uscle.  Above  and  below,  this 
lamina  spreads  out  in  the  form  of  two  large  men)l)ranes,  which  are  finally  ap'i>lied 
to  the  deep  surface  of  the  palt)ebral  fascia;  the  lower  membrane  constitutes  what 
has  been  described  as  '  the  suspensory  ligament  of  the  eyeball.'  The  upi>er  mem- 
brane recjuires  a  fuller  description,  as  its  distribution  is  modified  by  the  presence  of 
the  levator  palpebrie  muscle. 

The  upper  part  of  the  sheath  of  the  superior  rectus  (along  Avith  the  adjoining 


Fig.  486.— Horizontal  Section  Through  Left  Orbit,  viewed  feoji  auove. 
(After  Von  Gerlach.     To  show  check  ligaments,  etc. ) 


CONJUNCTIVAL  FORNIX 
LACHRYMAL  GLAND 


Outer  palpebral 
ligament 


External  cheek 
ligament 


OUTER  ORBITAL  WALL 


External  rectus 


ORBICULARIS 
PALPEBRARUM 


SPACE  OCCUPIED  BY 
SUBCONJUNCTIVAL 
TISSUE,  AND  BY 
TENON'S  CAPSULE 
FURTHER  BACK 
Upper  part  of 
Horner's  muscle 
Palpebral  fascia 

Internal  check 
ligament 


TENON'S  SPACE 
INNER  WALL  OF  ORBIT 

OPTIC  NERVE 
Internal  rectus 


ETHMOIDAL  CELLS 


ni'jmbrane  on  each  side  of  it)  passes  to  the  deep  surface  of  the  levator,  to  which  it 
closely  adheres,  and  completely  ensheaths  this  tendon  by  extending  round  its 
borders  to  its  upper  surface.  The  lower  part  of  this  levator-sheath  is  api>lied  to  the 
inferior  surface  of  the  deeper  of  the  two  divisions  of  the  muscle  (orbito-jxilpebral 
muscle  of  Sappey,  superior  palpebral  muscle  of  ^liiller),  and  is  attached  to  the  upjjcr 
border  of  the  tarsus  of  the  upper  lid,  reaching  laterally  to  the  outer  and  inner  angles 
of  the  orbit.  The  upper  part  of  the  sheath  of  the  orl)ito-palpel)ralis  muscle  reaches 
to  the  middle  of  the  jialpcbral  fascia,  and  is  mainly  continued  forward  between  the 
muscle  and  the  fascia  to  the  anterior  surface  of  the  tarsus. 

The  lower  membrane  (susi)ensory  ligament  of  the  eycl)all).  joined  by  the  sheath 
of  the  inferior  rectus,  reaches  forward  to  the  attached  (hinder)  l)order  of  the  tarsus 
of  the  lower  lid,  where  it  is  mainly  attached,  wliile  a  i«\rt  of  it  extends  to  the  lower 
palpeljral  fascia. 


860  ORGANS  OF  SPECIAL  SEXSE 

To  understand  the  special  bands  mentioned  above,  we  must  follow  the  sheath  of 
each  rectus  muscle  forwards,  when  we  find  that,  while  it  is  rather  loosely  applied  to 
the  muscular  belly  in  its  posterior  two-thirds,  it  then  suddenly  liecomes  thicker, 
and  is  firmly  attached  to  the  muscle  for  some  distance  before  finally  leaving  it,  and 
is  thereafter  often  accompanied  by  some  muscle-fibres.  The  best  developed  of 
these  bands,  the  external  check  ligament,  passes  forwards  and  outwards  to  the  outer 
angle  of  the  orbit,  helping  to  support  the  lachrymal  gland  on  its  way,  and  is 
inserted  near  the  orbital  edge  immediately  behind  the  external  pali)ebral  ligament. 
The  inner  band,  or  internal  check  ligament,  is  larger  than  the  outer,  but  not  so  thick; 
it  passes  forwards  and  inwards  to  be  inserted  into  the  upper  part  of  the  lachrymal 
crest  and  just  behind  it.  These  two  bands,  external  and  internal,  come  from  the 
sheaths  of  the  corresponding  recti  muscles.  From  the  sheath  of  the  superior 
rectus  come  two  thin  bands,  t)ne  from  each  border.  The  inner  joins  the  sheath  of 
the  tendon  of  the  superior  oblique;  the  outer  goes  to  the  external  angle  of  the  orbit, 
assisting  in  the  support  of  part  of  the  lachrymal  gland.  The  sheath  of  the  inferior 
rectus  is  thickened  in  front,  and,  on  leaving  the  muscle,  goes  to  the  middle  of  the 
inferior  oblique,  splitting  to  enclose  it;  it  then  passes  to  be  inserted  into  the  lower 
inner  angle  of  the  orbit  close  behind  its  margin,  about  midway  between  the  internal 
check  ligament  and  the  orbital  attachment  of  the  inferior  oblique. 

3.  In  addition  to  its  partial  investment  by  the  muscle-fascia,  the  eyeball  lias  a 
special  membrane  enclosing  its  hinder  two-thirds,  usually  called  Tenon's  capsule. 
This  is  a  thin,  transparent  tissue,  situated  immediately  beneath  the  muscle-fascia. 
It  follows  the  curve  of  the  sclerotic  from  the  insertion  of  the  recti  to  about  3  mm. 
from  the  optic  nerve  entrance,  when  it  leaves  the  eyeball  and  blends  with  the 
posterior  lamina  of  the  muscle-fascia;  the  combined  membrane  may  be  traced 
backwards,  enveloping  the  optic-nerve  sheath  loosely,  approaching  it  as  it  nears  the 
optic  foramen,  but  never  actually  joining  it.  The  interval  between  it  and  the  nerve- 
sheath  is  called  the  supravaginal  lymph  space.  Tenon's  capsule  first  comes  into 
relation  with  the  muscles  at  the  point  where  they  are  left  by  their  proper  sheaths  ; 
it  there  invests  their  tendons,  forms  a  small  serous  bursa  on  the  anterior  surface  of 
each,  and  adheres  to  the  sclerotic  in  the  form  of  a  line  running  round  the  globe, 
joining  the  insertions  of  the  four  recti  muscles.  Between  this  line  and  the  corneal 
border,  the  conjunctiva  is  separated  from  the  sclerotic  by  the  subconjunctival  tissue, 
strengthened  by  a  fine  expansion  of  the  muscle-fascia. 

The  inner  surface  of  the  capsule  is  smooth,  and  is  only  connected  with  the 
sclerotic  by  a  loose,  wide-meshed  areolar  tissue.  This  interval  between  the  sclerotic 
and  capsule,  known  as  Tenon's  space,  is  a  lymph  cavity,  and  permits  free  move- 
ments of  the  eyeball  within  the  capsule. 

Relation  of  Tenon^ s  Capsule  to  the  Oblique  Muscles. — The  ca])sule  surrounds  the 
posterior  third  of  the  inferior  oblique  and  its  tendon,  running  along  its  ocular 
surface  till  it  meets  the  fascial  band  coming  from  the  inferior  rectus  (see  above), 
and  forming  a  serous  bursa  on  the  superficial  surface  of  the  oblique  near  its  inser- 
tion. The  tendon  of  the  superior  oblique  for  about  its  last  five  millimetres  is 
invested  solely  by  Tenon's  capsule;  in  front  of  this,  as  far  as  the  trochlea,  the 
tendon  lies  in  a  membranous  tube  derived  from  the  muscle-fascia,  the  inner  lining 
of  which  is  smooth,  and  may  be  considered  as  a  prolongation  of  Tenon's  capsule. 

The  Optic  Nerve  \ 

The  part  of  this  nerve  with  which  we  have  here  to  do  lies  within  the  orbit, 
extending  from  the  optic  foramen  to  the  eyeball.  Its  course  is  somcAvhat  S-shaped; 
thus,  on  entering  the  orbit,  it  describes  a  curve,  with  its  convexity  down  and  out, 
and  then  a  second  slighter  curve,  convex  inwards.  Finally,  it  runs  straight 
forwards  to  the  globe,  which  it  enters  to  the  inner  side  of  its  posterior  pole 
Besides  curving  as  just  described,  the  nerve  also  rotates  on  its  long  axis,  so  thal\ 
the  surface  which  is  ]:)elow  at  the  foramen  becomes  temporal  Itefore  entering  the; 
eyeball. 

In   its   passage  through  the  optic    canal  the  nerve  is  surrounded    by  a    pro- 
longation of  the  meninges.       The    dura   mater  splits  at  the  optic  foramen,   partj 
of    it   joining    the    periorbita,   while    the    remainder    continues    to    surround  thej 


OPTIC  NERVE 


861 


nerve  loosely  as  its  outer  or  dural  sheath.  The  nerve  is  elosely  enveloped  l.y 
a  vascular  coverinjf  derived  from  the  pia  mater,  named  aecordingly  the  pial 
sheath.  The  space  between  these  two  sheaths,  known  as  the  inter rafjinal  x^xirc, 
is  subdivided  hyaline  prolongation  of  the  arachnoid  (the  arachnoidal  sheath  j  into 
two    parts,   viz.   an    outer,   narrow,   aabdaral,   and    an    inner,    wider,   .■oilxinirhndld 


Fio.  487. — Transverse  Section  thuolgii  Optic  Nerve,  showing  the  Relations  of 
ITS  Sheaths  and  Connective  Tissue  Framework. 


SUBARACHNOID  SPACF 


SUBDURAL  SPACE 


DURAL  SHEATH 
ARACHNOIDAL  SHEATH 


Central  retinal  artery 
Central  retinal  vein 


Conneetive-tisBue  frame- 
work, with  meshes  in 
which  the  nerve-flbre 
bundles  lie 


space,  communicating  with  the  corresponding  intracranial  spaces.  The  arachnoidal 
sheath  is  connected  with  the  sheath  on  each  side  of  it  by  numerous  fine  processes 
which  bridge  across  the  intervening  spaces.  The  pial  sheath  sends  processes 
iuAvards,  which  form  a  framework  separating  the  bunclles  of  nerve-libres ;  between 
the  enclosed  nerve-tiljres  and  each  mesh  of  this  framework  there  is  a  narrow  interval 


Fig.  488.— Longitudinal  Section  through  Termination  of  Optic  Nerve. 

physiological  pit 


RETINA 

PIGMENT  EPITHELIUM 


OURAL  SHEATH 
PIAL  SHEATH 

ARACHNOIDAL  SHEATH 


OPTir     XERl'E 
n/T/f  ITS 
COSSKCTIVE- 
TISSVE 
FRAMEWORK 


SJf?i—  SUPRACHOROIDAL 
'*T%"  SPACE 

-2^-  LAMINA  CRIBROSA 

"'  SCLEROTIC 


occupied  l>y  lymph.  The  nerve-filtres  are  medullated.  but  have  no  primitive  sheath. 
About  fifteen  or  twenty  millimetres  l)ehind  the  globe  the  central  vessels  enter, 
piercing  ol)liquely  the  lower  outer  (|uadrant  of  the  nerve,  and  then  run  forward 
in  its  axis.  They  are  accom])anied  throughout  by  a  special  process  of  tin-  j'ial 
sheath,  which  forms  a  fibrous  cord  in  the  centre  of  the  nerve. 


862 


ORGANS  OF  SPECIAL  SENSE 


On  reaching  the  eyeball,  the  dural  sheath  is  joined  l)v  the  arachnoid,  and  turns 
away  from  the  nerve  to  be  continued  into  the  outer  two-thirds  of  the  sclerotic. 
Similarly  the  pial  sheath  also  here  leaves  the  nerve,  its  greater  part  running  into 
the  inner  third  of  the  sclerotic,  Avhile  a  few  of  its  fibres  join  the  choroid;  the  inter- 
vaginal  space  consequently  ends  abruptly  in  the  sclerotic  around  the  nerve-entrance. 
In  this  locality  the  connective-tissue  framework  of  the  nerve  becomes  thicker  and 
closer  in  its  meshwork,  and  has  been  already  alluded  to  as  the  lamina  cribrosa.  It 
is  formed  by  processes  passing  out  from  the  central  fibrous  cord  at  its  ti'mdnation, 
and  l>y  processes  passing  inwards  from  the  pial  sheath,  sclerotic,  and  choroid.  It  does 
not  pass  straight  across  the  nerve,  but  follows  the  curve  of  the  surrounding  sclerotic, 
being  therefore  slightly  convex  Ijackwards.  The  nerve-trunk  here  quickly  becomes 
reduced  to  one-half  its  former  diameter,  the  fibres  losing  their  medullary  sheath, 
and  being  continued  henceforward  as  mere  axis  cylinders.  Apart  from  the  conse- 
quent loss  of  bulk,  this  histological  change  may  be  readily  recognised  macroscopi- 
cally  in  a  longitudinal  section  of  the  nerve,  its  aspect  here  changing  from  opaque 
white  to  semi-translucent  grey.  The  part  of  the  nerve  within  the  lamina  cribrosa 
has  already  been  seen  in  our  ophthalmoscopic  examination  of  the  living  eye. 

The  optic  nerve  is  mainly  nourished  by  fine  vessels  derived  from  those  of  the 
pial  sheath,  which  run  into  the  substance  of  the  nerve  in  the  processes  above  men- 
tioned. In  front  of  the  entrance  of  the  central  retinal  artery  this  vessel  aids  to 
some  extent  in  the  blood-supply  of  the  axial  part  of  the  nerve. 

Fig.  489. — The  Blood-vessels  of  the  Left  Orbit,  viewed  from  above. 


Sujiraorbital  artery 
LACHRYMAL  GLAND 

Superior  rectus IS^ 

EYEBALL 


External  rectus 

Lachrymal  artery 

Superior  rectus,  cut 
Inferior  ophthalmic  vein 
Superior  ophthalmic  vein 


OPTIC  NER  VE 

Common  ophthalmic  vein 


Commencement  of  superior 
ophthahiiic  vein 

TT Reflected  tendon  of  superior 

n'l,  oblique 

Tt'' Ophthalmic  artery 


Anterior  ethmoidal  artery 


Posterior  ethmoidal  artery 
Ciliary  arteries 

Levator  palpebrae,  cut 
Ligament  of  Zinn 
Ophthalmic  artery 

OPTIC  COMMISSURE 


Internal  carotid  artery 


The  Blood-vessels  a\d  Nerves  of  the  Orbit 

As  these  structures  will  be  more  particularly  described  in  other  sections  of  this 
work,  a  very  short  general  account  will  suffice  here. 

Arteries. — The  main  ])lood-sui)ply  is  afforded  by  the  ophthalmic  artery,  a 
branch  of  the  internal  carotid,  which  gains  the  orbit  through  the  optic  canal,  where 
it  lies  beneath  and  to  the  temporal  side  of  the  nerve.  On  entering  the  orbit  it 
ascends,  and  passes  obliquely  over  the  optic  nerve  to  the  inner  wall  of  the  orl)it; 
in  this  early  part  of  its  course  it  gives  off  most  of  its  branches,  which  vary  much 
in  their  manner  of  origin  and  also  in  their  course.     The  arteries  of  the  orbit  are 


i 


NERVES  OF  ORBIT 


8G3 


remarkable  for  their  tortuous  course,  for  their  delicate  walls,  and  for  their  loose 
attachment  to  the  surrounding^  tissues.  The  oplithalmic  artery  gives  off  si)ecial 
branches  in  the  orl)it  to  the  lachrymal  gland,  tlie  muscles,  the  retina  (through  the 
optic  nerve),  and  the  eyeball,  as  well  as  to  the  meninges,  the  ethmoidal  cells,  and  the 
nasal  mucous  memln-ane.  Twigs  from  all  the  different  l)ranclies  go  to  sui)iily  the 
fat,  fasciffi,  and  ordinary  nerves  of  the  orbit.  Branches  which  leave  the  orl)it  ante- 
riorly ramify  on  the  forehead  and  nose,  and  also  go  to  the  supply  of  the  eyelids 
and  the  tear-passages.  The  ophthalmic  artery  has  many  anastomoses  with  Ijranches 
of  the  external  carotid.  The  contents  of  the  orbit  are  also  supplied  in  part  by  the 
infraorbital  artery,  a  branch  of  the  internal  maxillary;  in  particular  tliis  artery 
sui)plies  part  of  tlie  inferior  rectus  and  inferior  o1)li(iue  muscles  in  the  cavitv,  and 
also  gives  a  branch  to  tlie  lower  eyelid. 

Veins. — Branches,  corresponding  generally  to  those  of  the  artery,  unite  to  form 
the  superior  and  inferior  ophthalmic  veins,  which  ultimately,  either  separately 
or  united  into  one  trunk,  ])ass  through  tlie  si)lienoidal  fissure  and  empty  into  tlie 
cavernous  sinus.  The  inferior  vein  is  connected  with  the  pterygoid  jilexus  ])y  a 
l)raiich  which  leaves  tlie  orbit  by  the  spheno-maxillary  fissure. 

Nerves  of  the  orbit. — These  are  motor,  sensory,  and  sympathetic,  and  all 
enter  the  orbit  by  the  sphenoidal  fissure,  with  the  exception  of  one  small  sensory 

Fig.  490. — Section'  tiikough   Contexts  of   Right  Orbit.  1-2  mm.  ix  froxt  of  the  Optic 
Foramen,  viewed  from  beuind.     (After  I.ange.) 


FOURTH  XER\  I 


Superior  rectus  and  levator 
palpebrse  superioris  uiuscles 


Superior  oblique  muscle 


OPTIC  SER  VE 


Internal  rectus  muscle 


Inferior  rectus  muscle 


Ophlhalmic  rein 

onilTIlALMir  XERVE 
(/ROXT.IL,  .v.). v.)/,, 
AX  It  J.KHRYMAL 
RRAXCIIES) 


T  Ophthahnic  vein 


Ophthalmic  artery 
SIXTH  XERVE 

THIRD   XERVE 
External  rectus  muscle 


branch  pa.ssing  througli  the  spheno-maxillary  fissure.      (The  optic  nerve  has  been 
already  described,  and  is  not  included  in  this  account. ) 

A.   The  motor  nerves  are  the  third,  fourth,  and  sixth  cranial. 

1.  The  third  nerve  enters  the  orbit  in  two  parts,  an  u})per  smaller,  and  a 
lower  larger  division.  The  upper  division  gives  off  two  branches:  one  su]tplies  tlie 
superior  rectus,  entering  its  lower  surface  far  back;  the  other  Ijranch  goes  to  the 
levator  palpebne,  entering  its  loAver  surface  in  its  posterior  third.  The  loner  diri-fitrn 
divides  into  three  branches,  of  which  one  supplies  the  inferior  rectus,  entering  its 
upper  surface  far  back,  and  another  supplies  the  internal  rectus,  entering  its  inner 
surface  a  little  behind  its  middle.  The  third  branch  of  the  loAver  division  gives  ( 1 ) 
the  short  root  to  the  ciliary  ganglion,  and  (2)  one  or  more  twigs  to  the  inferior 
rectus,  and  the  remainder  of  this  branch  then  enters  the  lower  surface  of  tlie  inferior 
oblique  muscle  about  its  mid<lle. 

2.  The  fourth  nerve  sui)))lies  the  superior  oblique  muscle,  entering  its  ui)i»er 
surface  about  midway  in  its  course. 

3.  The  sixth  nerve  su])plies  the  external  rectus,  entering  its  inner  surface  abdut 
the  junction  of  the  ])osterior  and  middle  thirds  of  the  muscle. 

As  regards  the  manner  of  termination  of  these  motor  nerves,  it  is  found  that 
in  all  the  ocular  muscles  the  nerve  on  its  entrance  lireaks  up  into  numerous  ]iun<lles 
of  fibres,  which  form  first  coarse  and  then  fine  plexuses,  the  latter  ultimately 
sending  off  fine  twigs  supplying  the  muscle  throughout  with  nerve-endings.     The 


864  ORGANS  OF  SPECIAL  SENSE 

posterior  third  of  these  muscles  is,  however,  comparatively  ill  supplied  with  lioth 
kinds  of  plexus  and  with  nerve-endings. 

B.  The  sensory  nerves  are  supplied  by  the  tirst  and  second  divisions  of  the 
fifth  cranial  nerve.  The  tirst  division,  or  ophthalmic  nerve,  is  entirely  orbital; 
while  the  second,  or  maxillary,  only  sends  a  small  branch  to  the  orbit. 

1.  The  ophthalmic  division  of  the  fifth  nerve  enters  the  orbit  in  three 
divisions,  namely: — 

(1)  Frontal,  splitting  subsequently  into  supratrochlear  and  sujwaorbital,  both 
passing  out  of  the  orbit.  It  is  distributed  to  the  corresponding  ui)i)er  eyelid,  and 
the  skin  over  the  root  of  the  nose,  the  forehead,  and  the  hairy  scalp  as  far  back  as 
the  coronal  suture  on  the  same  side.  It  also  gives  branches  to  the  periosteum  in 
this  region,  and  to  the  frontal  sinus. 

(2)  Lachrymal,  supplying  the  lachrymal  gland,  anastomosing  with  a  branch 
of  the  superior  maxillary  in  the  orbit,  aiid  finally  piercing  the  upper  eyelid.  Out- 
side the  orbit  it  is  distributed  to  the  outer  part  of  the  upper  lid,  the  conjunctiva  at 
the  external  eanthus,  and  the  skin  between  this  and  the  temporal  region. 

(3)  Nasal,  giving  off  (a)  a  branch  to  the  ciliary  ganglion,  constituting  its  long 
root;  (6)  two  or  three  long  ciliary  nerves;  and  (c)  the  infratrochlear,  passing  out  of 
the  orbit.  The  nasal  nerve  then  leaves  the  orbit,  re-entering  the  cranial  cavity 
before  being  finally  distributed  to  the  nose.  The  infratrochlear  branch  supplies  the 
eyelids  and  skin  of  the  side  of  the  nose  near  the  inner  eanthus,  the  lachrymal  sac, 
caruncle,  and  plica  semilunaris.  The  nasal  nerve,  after  its  second  course  in  the 
cranial  cavity,  passes  through  an  aperture  in  the  front  of  the  cribriform  plate  of 
the  ethmoid  bone,  and  is  ultimately  distributed  to  the  nasal  mucous  membrane, 
and  to  the  skin  of  the  side  and  ridge  of  the  nose  near  its  tip. 

2.  The  maxillary  division  of  the  fifth  nerve  gives  a  branch,  called  the  orbital 
nerve,  which  passes  into  the  orbit  through  the  spheno-maxillary  fissure,  anasto- 
moses with  the  lachrymal,  and  leaves  the  orbit  in  two  divisions.  These  are 
distril)Uted  to  the  skin  of  the  temple  and  of  the  prominent  part  of  the  cheek. 

A  few  minute  twigs  from  Meckel's  ganglion^  and  sometimes  from  the  maxillary 
division  of  the  fifth  nerve,  also  pass  through  the  spheno-maxillary  fissure  to  supply 
the  periorbita  in  this  neighbourhood. 

C.  The  sympathetic  nerves  of  the  orbit  are  derived  from  the  plexus  on  the 
internal  carotid.  With  the  exception  of  branches  accompanying  the  ophthalmic 
artery,  and  of  the  distinct  sympathetic  root  of  the  ciliary  ganglion,  the}'  enter  the 
orbit  in  the  substance  of  the  other  nerve-cords.  The  connections  between  the  ocular 
nerves  and  the  carotid  plexus  are  recognisal:)le  as  fibres  going  to  the  third,  sixth,  and 
ophthalmic  nerves;  as  a  rule,  the  comparatively  large  twigs  going  to  the  sixth  join 
it  furthest  back,  and  those  to  the  third  furthest  forward.  Sym])athetic  connections 
with  the  fourth  nerve  are  very  doubtful. 

The  lenticular  or  ciliary  ganglion  is  situated  between  the  optic  nerve  and 
external  rectus  far  back  in  the  orbit.  Its  three  roots — motor,  sensor}',  and  sympa- 
thetic— have  been  already  mentioned.  Anteriorly,  it  gives  off  three  to  six  small 
trunks,  which  subdivide  to  form  the  short  ciliary  nerves,  about  twenty  in  num- 
ber, ])iercing  the  sclerotic  around  the  o])tic  nerve  entrance. 

The  lymphatic  system  of  the  orbit. — Although  there  are  no  lym])hatic 
vessels  or  (jlanxh  in  the  orbit,  the  passage  of  lymph  is  nevertheless  well  ])rovided  for. 
We  have  already  observed  the  lymph  channels  within,  between,  and  outside  the 
sheaths  of  the  optic  nerve,  and  have  seen  how  these  communicate  anteriorly  with 
the  lymph  channels  of  the  eyeball,  and  posteriorly  with  the  intracranial  meningeal 
spaces.  In  addition,  there  are  lymph-spaces  around  the  blood-vessels,  situated 
between  the  outer  coat  and  the  loose  investment  furnished  by  the  muscle-fascia. 
The  nerves  of  the  orbit  (apart  from  the  optic)  are  probably  similarly  surrounded 
by  lymph-spaces.  In  the  absence  of  lymi)hatic  vessels  it  is  difficult  to  trace  the 
circulation  thoroughly;  much  of  the  lymph  from  the  orbital  cavity  is  .^Jaid  to  pass 
into  the  internal  maxillarv  glands. 


THE  EYELIDS 


805 


TiiK  Eyelids 

The  cutaneous  and  conjunctival  surfaces  of  the  Hds  have  already  been  examined, 
and  the  position  of  the  tarsus  lias  been  indicated.  We  have  now  to  ascertain  the 
nature  and  relations  of  the  tarsus,  and  describe  the  other  tissues  entering  into  the 
formation  of  the  eN'elids. 

Tlie  skin  here  is  thin,  bearinjjj  line  hairs,  and  having  small  sebaceous  and 
numerous  small  sweat  glands.  Immediately  beneath  it  is  a  loose  subcutaneous 
tissue,  destitute  of  fat,  separating  the  skin  from  the  palpel)ral  part  of  the  orbicularis 
muscle.  The  lid-tibres  of  this  muscle  arise  from  the  inner  palpebral  ligament  and 
course  over  the  whole  ui>per  and   lower  eyelids  in  a  succession  of  arches,  so 'as  to 


Fic.  491.— Vkktical  Tra.\sv7:rsk  Sectiox  throtigh  thk  Uppkr  Evklid. 
(After  Waldeyer  and  P'uchs.j 


Cutaneous  surface  just 
above  superior  palpe- 
bral fold 

Orbicularis  fibres,  cut 
across 


FINE  HAIR  WITH  SEBACEOUS 
GLAND  AT  ITS  BASE 


Orbicularis  fibres,  cut 
across 


MODIFIED  SWEAT  GLAND  OF 
MULL 


l/t^W        f^-    CONJUNCTIVA  NEAR  FORNIX 

y       Anterior    layer    of   inser- 
tion   of    levator    palpe- 
brae  superioris 
Superior  palpebral 

muscle  of  Mailer 
Fibres  from  levator 
passing  through 
orbicularis  to  skin 

Superior  vaxcular  (trch, 
cut  across 


WALDEYER'S  GLANDS 


Conjunctival  papillae 
over  attached  border 
of  tarsus 


MuBculuB  ciliariB 
Riolani 


Posterior  edge  of  lid- 
margin 


OPENING  OF  DUCT  OF 
MEIBOMIAN   GLAND 


meet  again  beyond  the  outer  cantlius:  there  they  in  ])art  join  one  another,  in  part 
are  inserted  into  the  outer  pal})ebral  ligament.  The  muscular  fibres  are  arranged 
in  loose  bundles,  with  spaces  between  them  occui)ied  by  comiective  tissue:  in  the 
upiier  lid  these  connective-tissue  fil>res  may  be  traced  u])wards  and  backwards  int<^) 
the  fibrous  expansion  of  the  tendon  of  the  U'vator  paljiebra' sujx'Horis.  One  strong 
bundle  of  orliicularis  fibres,  called  the  musculus  ciliaris  Riolani,  is  found  near 
the  edge  of  the  lid.  in  front  of.  and  behind,  the  clfcrcnt  ducts  of  the  Meil)omian 
glands. 

A  central  connective  tissue  si-parates  the  orbicularis  muscle  from  the  tarsus 
in  the  tarsal  division  of  the  lids.      In  the  ujiper  lid  this  is  to  be  regarded  as  mainly 
the  anterior  or  fii)rous  ex]iansion   of  the  tendon  of  the  levator  palpebrsp,  which 
55 


866  ORGAXS  OF  SPECIAL   SEXSE 

sends  connective-tissue  septa  l»et\veen  the  bundles  of  the  ovi'rlying  orl)icularis  (as 
just  mentioned)  going  to  the  skin.  In  the  orbital  part  of  this  lid  the  central  con- 
nective tissue  includes  also  the  palpebral  fascia,  lying  here  innnediately  beneath  the 
orbicularis  muscle;  l)ut  this  soon  thins  off  and  fades  into  the  more  deeply  placed 
levator  expansion.  This  latter  is  strengthened  l)y  an  extension  of  the  sheath  of 
the  su])erior  rectus,  Vn'  -which  this  nnisclc  is  (-nal)led  to  influence  the  elevation  of 
the  lid  indirectly.  In  the  lower  lid  the  central  coimective  tissue  similarly  consists 
of  palpel)ral  fascia,  l)lended  with  a  thin  tibrous  extension  of  the  sheath  of  the 
inferior  rectus.  Innnediately  in  front  of  each  tarsus  is  a  little  loose  connective 
tissue,  which  contains  the  large  blood-vessels  and  nerves  of  the  lids. 

The  tarsus  of  each  lid  is  a  stiff  plate  of  close  connective  tissue,  with  its  sur- 
faces directed  anteriorly  and  posteriorly;  in  its  substance  the  Meibomian  glands 
are  embedded.  One  tarsal  border  is  free,  viz.  towards  the  edge  of  the  lid,  the 
other  is  attached;  the  former  is  straight,  while  the  latter  is  convex,  especially  in 
the  upper  lid.  The  length  of  each  tarsus  is  about  twenty  millimetres.  Its  breadth 
is  greatest  in  the  middle  of  the  lid,  and  becomes  gradually  smaller  towards  each 
canthus,  where  the  tarsi  are  joined  to  the  outer  and  inner  palpebral  ligaments.  The 
breadth  of  the  upper  tarsus  (10  mm.)  is  about  twice  that  of  the  lower.  The  thick- 
ness of  each  is  greatest,  and  its  texture  closest,  at  the  middle  of  its  length,  thin- 
ning off  towards  the  canthi  and  towards  both  l)orders.  Into  the  superior  anterior 
l)order  of  the  upper  tarsus  the  lower  layer  of  the  levator  expansion  is  attached,  con- 
sisting of  smooth  muscle-fibres  constituting  the  superior  palpebral  muscle  of 
Miiller.  In  like  manner,  at  the  inferior  bord(n-  of  the  lower  tarsus,  bvmdles  of 
smooth  muscle  fibre  are  inserted  (the  inferior  palpebral  muscle  of  Miiller),  devel- 
oped in  what  has  l^een  regarded  as  part  of  the  extension  of  the  sheath  of  the  in- 
ferior rectus. 

The  palpebral  conjunctiva  is  firmly  adherent  to  the  back  of  the  tarsus;  but  in 
the  orl)ital  ]>art  of  the  lid  loose  subconjunctival  tissue  intervenes  between  it  and 
Miiller' s  palpebral  muscle.  Adenoid  tissue  occurs  in  the  substance  of  the  conjunc- 
tiva, especially  in  its  orbital  division.  Near  the  upper  fornix,  the  conjunctiva 
receives  expansions  of  the  tendon  of  the  levator  palpebrse  and  of  the  sheath  of  the 
superior  rectus,  and,  at  the  lower  fornix,  of  the  sheath  of  the  inferior  rectus.  The 
surface  of  the  tarsal  conjunctiva  shows  small  elevations  or  papillae  everywhere;  but 
these  are  particularly  well  marked  over  the  attached  border  of  the  tarsus. 

Glands  of  the  eyelids.— From  its  manner  of  formation  the  eyelid  may  be 
regarded  as  consisting  of  two  thicknesses  of  skin,  the  inner  (or  posterior)  having 
been  doubled  l)ack  upon  the  outer  at  the  edge  of  the  lid;  thus  the  cuticle  and 
corium  of  the  skin  proper  are  represented  respectively  by  the  conjunctiva  and  tai'sus 
of  the  inner  thickness.  At  the  free  border  of  the  lid,  accordingly,  Ave  find  glands 
corresponding  to  the  sebaceous  and  sweat  glands  of  the  skin,  viz.  large  sebaceous 
glands  of  the  cilia  ( Zeiss' s  glands)  and  Moll's  modified  sweat  glands.  Again^in  the 
inner  skin-thickness  of  the  lid,  the  Meibomian  glands  of  the  tarsus  are  sebaceous, 
and  acino-tul:)ular  glands  present  at  the  attached  border  of  the  tarsus  ("Waldeyer's 
glands)  may  be  reckoned  as  modified  sweat  glands.  Glands  similar  in  structure  to 
Waldeyer's  also  occur  at  the  fornix,  and  are  especially  altundant  near  the  outer 
canthus  of  the  upper  lid,  close  to  the  efferent  ducts  of  the  lacln-ymal  gland;  from 
tlieir  structure,  and  the  character  of  their  secretion,  these  acinous  or  acino-tulnilar 
glands  have  been  termed  by  Henle  '  accessory  lachrymal  glands.'  Other  simple 
tubular  glands  (Henle),  formed  merely  by  the  depressions  between  the  papilla^, 
are  best  developed  in  the  inner  and  outer  fourths  of  the  tarsal  conjunctiva  of 
both  lids. 

Blood-vessels.— Tlie  arteries  run  in  the  central  connective  tissue  of  the  lids, 
mainly  in  tlie  form  of  arches  near  the  borders  of  the  tarsus,  from  Avhich  twigs  go 
to  the  different  pal))el)ral  tissues.  They  are  supplied  by  the  lachrymal  and  j>al])e- 
l)ral  branches  of  the  o])hthalmic,  and  by  small  l)ranches  derived  from  the  temporal 
artery.  The  veins  are  more  numerous  and  larger  than  the  arteries,  and  form  a 
close  plexus  beneath  each  fornix.  They  em])ty  themselves  into  the  veins  of  the 
face  at  the  imier,  and  into  the  orbital  veins  at  the  outer  canthus. 

The  lymphatic  vessels  of  the  lids  are  numerous,  and  are  ])rincipally  situated 
in  the  conjunctiva.      Lyniph-si)aces  also  surround  the  follicles  of  the  Meibomian 


LACHRYMAL   APPARATUS  SG7 

glands.  The  palpebral  lymphatic  vessels  niainl}-  pass  through  the  jn-eauricular 
gland;  but,  sometimes  at  least,  those  from  the  inner  half  of  the  lower  lid  go  to  the 
submaxillary  lymphatic  glands. 

Nerves. — (a)  Sensory.  The  upper  lid  is  chiefly  supplied  by  l)ranches  of  the 
supraorVjital  and  supratrochlear  nerves,  the  lower  lid  by  one  or  two  l^ranches  of 
the  infraorbital.  At  the  inner  canthus  the  infratrochlear  nerve  also  aids  in  the 
supply,  and,  at  the  outer  canthus,  the  lachrymal.  (6)  Motor.  The  palpebral  part 
of  the  orbicularis  is  supplied  l:)y  branches  of  the  facial  nerve,  which  mainly  enter 
it  near  the  outer  canthus.  Miiller's  palpebral  nmscles  are  supplied  by  the  sympa- 
thetic nervous  system. 

The  inner  palpebral  ligament,  or  tendo  oculi,  has  been  referred  to  previously. 
Arising  from  the  frontal  process  of  the  maxilla,  it  extends  outwards  over  the 
front  wall  of  the  lachrymal  sac,  bends  round  the  outer  wall  of  the  sac,  and  then 
passes  liackAvards  to  the  posterior  crest  on  the  lachrymal  bone.  It  is  thus  U-shaped, 
having  its  limbs  anterior  and  posterior,  embracing  the  lachrymal  sac;  the  anterior 
limb  lies  immediately  beneath  the  skin,  and  is  visible  in  the  living.  The  palpei)ral 
fibres  of  the  orbicularis  are  inserted  into  the  outer  surface  of  both  limbs,  those 
attached  to  the  posterior  limb  constituting  Horner's  muscle.  The  outer  palpe- 
bral ligament  is  merely  a  stronger  development  of  connective  tissue  in  the  orbicu- 
laris.    Both  ligaments  are  connected  with  the  tarsi  as  already  mentioned. 

The  Lachrymal  Apparatus 

The  tears  are  secreted  by  an  acinous  gland,  and  flow  through  fine  ducts  to  the 
upper  outer  part  of  the  conjunctival  sac,  whence  they  are  drained  off  through  the 
puncta,  pass  along  the  canaliculi  into  the  lachrymal  sac,  and  ultimately  run  down 
the  nasal  duct  to  gain  the  inferior  meatus  of  the  nose. 

The  lachrymal  gland  is  situated  near  the  front  of  the  outer  part  of  the  roof  of 
the  orbit,  lying  in  a  depression  in  the  orbital  plate  of  the  frontal  bone.  It  consists 
of  two  very  unequal  parts,  one  placed  above  and  the  other  beneath  the  tendinous 
exi^ansion  of  the  levator  palpel^rse  superioris,  but  small  gaps  in  the  expansion 
permit  of  connections  between  these  two  parts  of  the  gland.  The  upper  and  larger 
subdivision  {superior  lachrymal  gland)  is  a  firm  elongated  body,  al^out  the  size  of 
a  small  almond;  it  has  a  greyish-red  colour,  and  is  made  up  of  closely  aggregated 
lobules.  The  upper  surface  (next  the  orbital  roof)  is  convex,  and  its  lower  surface 
is  slightly  concave.  Anteriorly,  the  gland  almost  reaches  the  upper  orbital  mar- 
gin, and  it  extends  backwards  for  approximately  one-fourth  the  depth  of  the 
orbit,  measuring  about  twelve  millimetres  in  this  direction.  The  outer  border  oi 
the  gland  descends  to  near  the  insertion  of  the  fascial  expansion  of  the  external 
rectus,  while  its  inner  border  almost  reaches  the  outer  edge  of  the  superior  rectus; 
its  transverse  measurement  is  al)out  twenty  millimetres.  It  is  enveloped  in  a 
capsule,  which  is  slung  by  strong  fibrous  bands  passing  to  its  inner  border  from 
the  orbital  margin  (suspensory  ligament  of  the  gland). 

The  lower  subdivision  of  the  gland  (inferior  lachrymal  gland)  is  composed  oi 
loosely  applied  lobules,  and  lies  immediately  over  the  outer  third  of  the  up])er 
conjunctival  fornix,  reaching  outwards  as  far  as  the  external  canthus. 

Each  subdivision  of  the  gland  jiossesses  several  excretory  ducts,  Avhich  all  open 
on  the  outer  part  of  the  upper  fornix  conjunctivse,  about  four  millimetres  above  tlie 
upper  border  of  the  tarsus.  Those  of  the  superior  gland,  three  or  four  in  number, 
pass  between  the  lobules  of  the  lower  gland;  the  outermost  duct  is  the  largest,  and 
opens  at  the  level  of  the  external  canthus.  The  ducts  of  the  inferior  gland  in  part 
discharge  themselves  into  those  of  the  upper,  but  there  are  also  several  line  ducts 
from  this  subdivision  that  run  an  independent  course. 

Near  the  inner  canthus  are  the  two  puncta  lachrymalia,  upjierand  lower,  each 
situated  at  the  summit  of  its  pajnlla.  The  to])  of  each  pai)illa  curves  backwards 
towards  the  conjunctival  sac,  so  that  the  i)uncta  are  well  adapted  for  their  function 
of  draining  off  any  fluid  collecting  there. 

The  canaliculi  lachrymales  <-xtend  from  tlie  puncta  to  the  lachrymal  .^ac. 
The  lumen  at  the  punetuni  is  horizontally  oval,  from  its  lips  being  slightly  com- 


868 


ORGANS  OF  SPECIAL  SENSE 


j)ressed.  antero-posteriorly;  the  lumen  of  the  lower  ])unetuiu  is  somewhat  larger 
than  that  of  the  upper.  As  the  lower  papilla  is  a  little  further  from  the  inner 
canthus  than  the  upper,  the  corresponding  canaliculus  is  longer. 

On  tracing  either  canaliculus  from  its  origin,  we  tind  that  at  first  it  runs  nearly 
vertically  for  a  short  distance,  then  bends  sharply  toAvards  the  nose,  and  finally 
courses  more  or  less  horizontally,  converging  slightly  towards  its  fellow,  and  not 
infrequently  joining  it  before  opening  into  the  sac.  The  calibre  varies  considerabh' 
in  this  course,  being  narrowest  a  short  distance  from  the  punctum,  and  widest  at 
the  bend,  from  which  point  it  again  narrows  very  gradually  as  it  nears  the  sac. 
The  wall  of  the  canaliculus  consists  mainly  of  elastic  and  white  fibrous  tissue, 
lined  internally  by  epithelium,  and  covered  externally  by  striated  muscle  (part  of 
the  orbicularis).  The  muscle-fibres  run  parallel  to  the  canaliculus  in  the  horizontal 
part  of  its  course;  but  they  are  placed,  some  in  front  and  some  behind,  around  the 
vertical  part,  acting  here  as  a  kind  of  sphincter.  .Just  before  their  termination,  the 
canaliculi  pierce  the  periosteal  thickening  that  constitutes  the  posterior  limb  of  the 
inner  palpebral  ligament. 

The  lachrymal  sac  lies  in  a  depression  in  the  bone  at  the  inner  angle  of  the 
orbit  (the  lachrymal  fossa).  It  is  vertically  elongated,  and  narrows  at  its  upper 
and  lower  ends;  the  upper  extremity  or  fundus  is  closed,  Avhile  the  low^er  is  contin- 
uous directly  with  the  nasal  duct.  Laterally,  the  sac  is  somewhat  compressed,  so 
that  its  antero-posterior  is  greater  than  its  transverse  diameter.     The  canaliculi, 


Fig.  492. — Lachrymal  Apparatus.      i^After  Sebwalbe.) 


SUPERIOR  LACHRYMAL  GLAND 
INFERIOR  LACHRYMAL  GLAND 


DUCT  FROM  SUPERIOR  GLANC 


UPPER  EYELID  PARTIALLY 
DIVESTED  OF  SKIN 


UPPER  PUNCTUM 

LACHRYMAL  SAC,  NEAR  ITS  FUNDUS 

COMMON  DUCT  FORMED  BY  JUNC- 
TION OF  CANALICULI 

UPPER  AND  LOWER  CANALICULI 
LOWER  PUNCTUM 


either  separately  or  by  a  short  common  tube,  open  into  a  bulging  on  the  outer  sur- 
face of  the  sac  near  the  fundus.  As  has  previously  been  mentioned,  the  sac  is 
surrounded  by  periosteum,  but  between  this  and  the  mucous  membrane  forming 
the  true  sac-wall  there  is  a  loose  connective  tissue,  so  that  the  cavity  is  capable 
of  considerable  distension.  The  relations  of  the  inner  palpebral  ligament  have 
already  been  described;  it  is  to  be  noted  that  the  fundus  of  the  sac  extends  above 
this  ligament. 

The  nasal  duct  reaches  from  the  lower  end  of  the  sac  to  the  top  of  the  inferior 
meatus  of  the  nose,  opening  into  the  latter  just  beneath  the  adherent  border  of  the 
inferior  turbinated  bone.  Traced  from  above,  its  main  direction  is  downwards,  but 
it  has  also  a  slight  inclination  backwards  and  outwards.  It  lies  in  a  bony  canal, 
whose  periosteum  forms  its  outer  covering.  Between  this  and  the  mucous  mem- 
brane of  the  duct  there  is  a  little  intermediate  tissue,  in  which  run  veins  of  consid- 
erable size  connected  with  the  plexus  of  the  inferior  turlnnated  bone.  The  duct 
does  not  usually  open  directly  into  the  nasal  cavity  at  the  lower  end  of  the  bony 
canal,  l)ut  pierces  the  nasal  mucous  membrane  very  ol)liciuely,  so  that  a  fap  of 
mucous  membrane  covers  the  lower  border  of  the  opening  in  the  bone,  ujion  which 
tlap  the  tears  first  trickle  after  escaping  from  tlie  duct  proper. 

The  sac  and  nasal  duct  together  constitute  the  lachrymal  canal,  lined  through- 
out by  a  continuous  mucous  membrane.  This  membrane  presents  folds  in  some 
situations,  especially  near  the  opening  of  the  canaliculi,  at  the  junction  of  the  sac 


LACHRYMAL   APPARATUS 


869 


and  duct  and  at  the  lower  end  of  the  duct.  That  at  the  top  of  the  duct  is  the  most 
important,  as  it  sometmies  mterferes  with  the  proper  fiow  of  tears  onT  of  fW 
The  total  length  of  the  lachrymal  canal  is  roughly ^t'4ntv-foLmmimetr^  h.lf  f 
this  being  sac,  and  half  nasal  duct.  If,  howe^yer  ::1^JZ^Tc!te  ollue 
passage  through  the  nasal  mucous  membrane,  this  measurement  may  occastnaHy 
be  mcreased  by  eight  or  ten  millimetres.  The  lachrymal  sac,  whin  dfstended 
measures  about  six  milhmetres  from  before  backwards,  by  four  millimetlis  Trans' 
versely.  The  nasal  duct  is  practically  circular,  and  has  a^  diamete  Ja  out  th?'; 
milhme  res,  rather  less  at  its  junction  witli  the  sac,  where  we  find  the  narrowest 
part  of  the  whole  lachrymal  canal.  me  narro\\est 


THE  EAR. 

By  ARTHUR  HENSMAN,  F.R.C.S. 
Revised  by  ARTHUR  ROBINSON,  M.D.,  M.R.C.S. 

LECTURER   ON   AUATOMY   IN   THE   MIDDLESEX   HOSPITAL   MEDICAL  SCHOOL.      EXAMINER    IN   ANATOMY   FOR   THE 

CONJOINT   BOARD   OF   ENGLAND 


The  organ  of  hearing  may  he  (Hvidcd  into  three  parts: — the  EXTERNAL  EAR, 
wliich  inchides  the  pinna  and  external  auditory  meatus;  the  middle  ear,  or 
tympanum,  with  its  ventilating  shaft  the  Eustachian  tube  ;  and  the  internal 
EAR,  which  inchides  the  osseous  labyrinth,  within  which  is  placed — the  essential 
portion  of  the  organ — the  membranous  labyrinth. 


THE  EXTERNAL  EAR 

The  Pinna,  or  Auricle,  is  attached  to  the  side  of  the  head,  midway  hetween 
the  forehead  and  occiput.  Its  level  is  indicated  by  horizontal  lines  extending  back- 
wards from  the  evebrows  above,  and  from  the  tij)  of  the  nose  beloAv.     SomcAvhat 


Fig.  493.— Exterxal  View  of  the  Left  Aukicle. 


Triangular  fossa 


TRAGUS    


Scaphoid  fossa 


j)yrif()rm  in  shape,  its  irregular  concave  outer  surface  is  turned  morc^  or  less  for- 
wards, but  the  angle  of  inclination  varies  considerably  in  diiferent  sulgects.  The 
incurved  rim  of  the  ear,  which  divides  its  surfaces  from  each  other,  commences 
below  in  a  deej)  concavity  which  surrovnids,  like  the  mouth  of  a  trumpet,  the 
external   auditory  meatus.      This  rim   is  called  the  helix,  and,  traced  round  the 

870 


EXTERN AL   EAR 


871 


ear,  ends  below  at  the  posterior  margin  of  the  lobule.  On  the  upper  part  of 
the  inverted  edge  of  the  hehx  a  little  irregular  process  often  exists,  which  has  been 
regarded  as  the  shrivelled  tip  of  the  primitive  ear,  and  anteriorly,  where  it  begins 
to  bend  backwards,  there  is  a  small  projection,  the  spine  of  the  helix  (Fig.  495). 
The  hollow  from  which  the  helix  starts  is  called  the  concha.  Within  the  helix, 
but  separated  from  it  by  the  scaphoid  fossa  (fossa  of  the  helix)  runs  a  second 
curved  ridge,  the  antihelix.  It  commences  lielow  in  the  little  process  known  as 
the  antitragus,  and  bifurcating  superiorly  bounds  a  shallow  fossa  just  above  the 
concha,  the  so-called  triangular  fossa  (fossa  of  the  antihelix).  The  concha, 
bounded  by  the  antihelix,  is  deeply  notched  below  (incisura  intertragica).  Over- 
lapping the  commencement  of  the  notch  before  and  behind  are  two  eminences, 
the  anterior  and  larger,  the  tragus  ;  the  posterior,  the  antitragus.  The  auricle 
varies  greatly  in  different  individuals,  and  the  lobule  perhaps  more  than  any 
other  part. 

The  cartilaginous  framework  of  the  ear,  although  it  does  not  enter  into  all 
its  parts,  gives  to  it  the  general  character  and  appearance  already  described. 
It  consists  of  pliable  reticular  cartilage  of  the  yellow  elastic  kind.  It  does  not 
enter  into  the  formation  of  the  lobule,  which  consists  entirely  of  dense  connec- 
tive tissue  and  fat.  Its  lower  portion  is  so  rolled  upon  itself  as  to  form  a  tube 
incomplete  above,  which  tails  off  as  it  passes  inwards  to  be  attached  to  the  lower 
third  of  the   external   auditory  meatus.     This   attachment   is   effected  by  means 

Fig.  494. — Section  through  the  Orifice  of  the  Right  External  Auditory  Meatus. 


Fissure  of  Santorin 
Posterior  auricular  artery 


Section  of  cartilaginous  portion 


EXTERNAL  AUDITORY  CANAL 


Lining  membrane 


Fissure  of  Santorini 


of  a  dense  fibro-elastic  tissue  which  allows  considerable  shifting  on  traction  of 
the  pinna  upwards  and  backwards.  A  section  passing  through  the  orifice  of  the 
meatus  shows  the  cartilage  greatly  in  excess  of  the  fibrous  membrane  which 
completes  its  contour.  Deeper  sections  show  the  cartilage  diminishing  more 
and  more  until  it  forms  scarcely  a  third  of  the  lumen  of  the  tube  near  the  bony 
meatus. 

The  wall  of  the  channel  is  traversed  by  fissures,  the  fissures  of  Santorini ; 
l:»ut  these  are  not  constant  in  their  m^mber,  extent,  or  direction;  they  are  filled  with 
fibrous  tissue,  and  allow  the  canal  to  be  straightened  by  traction  on  the  pinna. 
The  lower  segment  of  the  cartilaginous  meatus  is  in  close  contact  with  the  parotid 
gland.  An  abscess  in  this  region  may  thus  burrow  through  the  fissures  and  dis- 
charge itself  through  the  external  meatus.  There  is  also  a  gap  between  the  helix 
and  the  tragus  bridged  over  by  a  band  of  dense  fibrous  tissue.  Several  fissures 
traverse  the  cartilage,  and  a  deep  cleft  dividing  the  antihelix  severs  the  caudate 
process  from  the  rest  of  the  cartilage  below. 

Ligaments. — An  anterior  ligament  connects  the  spine  of  the  helix  with  the 
root  of  the  zygoma,  and  a  posterior  passes  from  the  concha  to  the  mastoid  pro- 
cess. 

A  pair  of  ligaments  belong  to  the  cartilage  itself,  the  strong  band  already 
described  completing  the  orifice  of  the  meatus,  and  one  less  marked  passing  l)etween 
the  concha  and  the  processus  caudatus. 

Muscles. — The  extrinsic    muscles,  the   attollens,    attrahens,    and  retrahens 


872 


ORGANS  OF  SPECIAL   SEXSE 


aureiii,  luive  been  described  on  i»age  431.  The  sjjecial  intrinsic  muscles  are  six  in 
nunil)er.      They  are  ditiicult  to  display,  and  sometimes  appear  to  be  absent. 

Helicis  major  is  a  narrow  slip  Avliich  arises  from  the  spine  of  the  helix  and 
passes  upwards  along  the  rim  of  the  helix  to  near  its  summit. 

Helicis  minor  is  an  oblique  fasciculus  overh'ing  the  commencement  of  the 
helix. 

The  tragicus  consists  of  nearly  vertical  fibres  lying  over  the  outer  surface  of 
the  tragus. 

The  antitragicus  arises  from  the  outer  surface  of  the  antitragus  to  pass  to  the 
caudate  process. 

The  transversus  auris  consists  of  mixed  muscular  and  tendinous  fibres  which 
with  the  following  lies  on  the  cranial  aspect  of  the  pinna,  and  traverses  the  hollow 
formed  between  the  bulging  of  the  concha  and  the  convexity  corresponding  to  the 
groove  of  the  helix. 

The  obliquus  auris  crosses  the  hollow  between  the  concha  and  fossa  of  the 
antihelix. 


Fig. 


495. — External  and  Interxal  Surface  of  the  Cartilage  of  the  Right 
Pinna  and  its  Muscf.ES,  etc. 


Helicis  major 


Obliquus 


Helicis  minor 


Fibrous  band 

completing  fore  —7 

part  of  meatus 


PROCESSUS  

CAUDATUS  y 


Transversus 


Antitragicus 


Tragicus       Spine  Fissure  of  Santorini 

of  Helix 


Vessels. — The  arteries  are  the  posterior  auricular  from  the  external  carotid, 
and  the  anterior  auricular  from  the  temporal. 

The  veins  enter  the  posterior  auricular  and  temporal  veins. 

Nerves. — The  inner  surface  of  the  pinna  is  supplied  by  three  cutaneous  nerves, 
the  great  auricular,  the  small  occipital  and  the  auricular  branch  of  tlie  vagus.  The 
great  auricular  sui)})lies  the  lower  three-quarters,  with  the  exception  of  a  small 
])()rtion  near  the  meatus  which,  together  with  the  back  of  the  meatus,  is  supplietl 
by  the  auricular  branch  of  the  vagus.  The  small  occipital  supplies  the  upi)er 
fourth.  Occasionally  the  great  occipital  sends  a  branch  to  the  uppermost  part 
of  the  inner  surface.  The  upper  two-thirds  of  the  outer  surface  receive  their 
cutaneous  suppl}^  from  the  auriculo-temporal  nerve,  and  the  lower  third  is  supplied 
by  the  great  auricular.  The  intrinsic  muscles  on  the  inner  surface  are  supplied 
by  the  posterior  auricular  liranch  of  the  facial  and  those  on  the  outer  surface 
by  the  tcni])or;il  brnncb  of  the  same  nerve. 

The  External  Auditory  Meatus  is  al)out  an  incli  long  (25  mm. ).  It  com- 
mences at  the  bottom  of  the  conclia,  and  passes  inwards  and  a  little  forwards  to 
end  at  the  membrana  tymi)ani.  It  is  narrowest  at  its  centre.  Near  its  orifice  it 
is  oval  from  above  downwards,  but  at  its  termination  it  is  somewhat  l)roader  from 


EXTERNAL   EAR— MIDDLE  EAR 


873 


side  to  side.  Owing  to  the  obliquity  of  the  membrana  tympani,  the  floor  is  longer 
than  the  roof,  and  the  anterior  longer  than  the  posterior  wall  of  the  canal. 

Its  cartilaginous  portion,  which  is  a  little  less  than  half  an  inch  (11  mm.)  in 
length,  is  formed  by  the  incomplete  tube  of  cartilage  already  described,  with 
fibrous  membrane  to  complete  its  upper  and  front  part. 

The  osseous  portion  of  the  tube,  a  little  more  than  half  an  inch  (14  mm.  j  in 
length,  is  slight Iv  curved,  with  its  convexity  looking  upwards  and  backwards 
(fig.  496). 

The  lining  membrane  is  a  reflexion  from  the  skin  externally.  It  is  thick  and 
strong  in  the  cartilaginous,  but  becomes  thinner  in  the  osseous  portion;  especially 
is  this  the  case  near  the  membrana  tympani,  over  which  it  is  reflected  to  form  its 
cuticular  layer.  In  the  cartilaginous  portion  the  dermis  is  supplied  with  numerous 
hairs,  and  sebaceous  glands  open  into  their  follicles.  Tubular  ceruminous  glands, 
the  orifices  of  which  stud  the  whole  of  the  cartilaginous  portion,  appear  as  dark 
}»oints  to  the  naked  eye. 

Fig.  496.— Section  of  the  Middle  axd  Exterxal  Ear. 


SEMI-      ^    GLANDS 
CIRCULAR      IN    OSSEOUS 
CANALS  MEATUS 

Membrana 
tympani 

COCHLEA 


CAVITY  OF 
TYMPANUM 


PINNA 

CARTILAGINOUS   MEATUS 

OSSEOUS  MEATUS 

CARTILAGE  OF  EXTERNAL 
MEATUS 

'AROTIO  GLAND 

STYLOID  PROCESS 

Internal  carotid 
artery 


CARTILAGINOUS  EUSTACHIAN 
TUBE 


OSSEOUS  EUSTACHIAN  TUBE 


These  glands  extend  a  short  distance  into  the  upper  and  back  part  of  the  bony 
meatus,  in  the  form  of  a  triangular  patch,  but  elsewhere  they  appear  to  be  absent. 

The  arteries  are  derived  from  the  posterior  auricular,  temporal,  and  internal 
maxillary;  and  the  nerves  from  the  auriculo-temporal  and  the  auricular  branch 
of  the  vasrus. 


THE  MIDDLE  EAR 

The  Membrana  Tympani  is  an  irregularly  rounded  concave  membrane  stretched 
oblicjuely  across  the  bottom  of  the  osseous  meatus  in  sucli  wise  as  to  form  an 
obtuse  angle  with  its  upper  wall  (according  to  Von  Troltsch,  140°)  and  an  acute 
one  with  its  lower. 

The  circumference  of  the  membrane  is  lodged  in  the  groove  of  the  tympanic 


874 


ORGANS  OF  SPECIAL  SENSE 


ring  (tig.  498a).  Above  and  in  front  where  the  ring  is  wanting  there  is  a  slight  recess 
known  as  the  notch  of  Rivinus,  and  here  the  membrane  is  extended  outwards,  to 
\mite  with  the  groovelcss  margin  of  the  tympanum  to  form  what  is  known  as  the 
Rivinian  segment. 

The  shape  of  the  membrane  varies  with  tliat  of  the  inner  end  of  tlie  meatus. 
Its  long  axis  is  from  above  downwards  and  forwards.  The  membrane,  broadly 
viewed,  is  concave  externally,  and  convex  towards  the  cavity  of  the  tympanum. 
This  is  mainly  due  to  the  traction  of  the  handle  of  the  malleus,  Avhich  descends 
obliquely  downwards  and  backwards  between  its  two  inner  layers  to  a  ])oint  a  little 
))elow  the  centre  of  the  membrane.  This  curvature  is  deepest  at  the  umbo,  opposite 
the  flattened  extremity  of  the  handle.  In  front  of  and  below  the  umbo,  extending 
towards  the  periphery,  the  membrane  is  slightly  convex  externally. 

At  the  anterior  superior  pole,  the  short  process  of  the  malleus  is  plainly  visible 
as  a  rounded  point  projecting  outwards.  A  fold  of  the  membrane  passes  backwards, 
and  another  forwards  from  this  spot,  and  above  these  folds  may,  under  favorable 
conditions,  be  seen  two  short,  tightly  stretched  striae,  which,  taking  origin  from  the 
corners  of  the  notch  of  Rivinus  above,  converge  as  they  descend  to  meet  at  the 
short  process.  The  membrane  between  these  stria?  and  the  edge  of  the  notch  is 
thin  and  flaccid,  and  appears  above  the  short  process  as  a  small  pit-like  depression 


Fig.  497. — External  View  of  the  Left  Membrana  Tympani.     (Enlarged  from  life.) 

Shrapnell's  membrane       Posterior  fold  of  membrana  tympani 


Anterior  fold  of  membrana 
tympani 


SHOST  PROCESS  OF  MALLEUS 


UMBO,   OR  LOWER  EXTREMITY  OF 
HANDLE  OF  MALLEUS 


Cone  of  light 


LONG  PROCESS  OF  INCUS 


Posterior  portion  of 
membrana  tympani 


(membrana  Shrapnelli).  An  anastomosis  between  the  tympanic  vessels  and  those 
of  the  external  meatus  occurs  at  this  si)ot. 

Viewed  from  within,  the  head  of  the  malleus  is  seen  above  the  membrane 
articulating  with  the  incus,  its  curved  handle  passing  downwards  and  slightly  back- 
wards between  its  layers,  and  strongly  projecting  from  the  inner  surface.  The 
chorda  tympani  nerve  may  be  seen  crossing  the  neck  of  the  malleus  forwards  to 
the  CJlaserian  fissm-e.  Folds  of  the  membrane  occur  in  front  of  and  behind  the 
malleus,  bounding  what  are  known  as  the  anterior  and  posterior  ])ouches  of  the 
membrana  tympani.  The  free  margin  of  the  posterior  ])ouch  is  commonly  well 
marked.  Passing  slightly  downwards  and  outwards  to  the  base  of  the  handle  of 
the  malleus,  is  the  strongly  marked  fold  containing  the  tendon  of  the  tensor 
tympani  muscle. 

Structure, — The  membrana  tympani  consists  of  three  layers — as])ecial  fibrous 
layer,  with  a  cuticular  covering  externally  continuous  with  that  which  lines  the 
external  auditory  meatus;  and  a  mucous  lining  internally  derived  from  the  tym- 
})anic  cavity. 

The  fibrous  layer  consists  of  two  lanielhe  closely  connected — an  external,  in 
which  the  fibres  radiate  from  the  handle  of  the  malleus;  and  an  internal,  the 
fibres  of  which  are  arranged  concentrically,  and  are  especially  strong  at  the 
circumference. 


MIDDLE  EAR 


875 


The  membrane  of  Shrapnell  is  extremely  thin,  and  consists  only  of  the  outer 
and  inner  layers,  the  fibrous  layer  being  absent. 

The  handle  of  the  malleus  descends  between  the  two  inner  layers,  accompanied 
by  the  vessels,  which  are  often  clearly  visible  in  the  living  memV^rane. 

The  Tympanic  Cavity  or  middle  ear  is  a  narrow  space  which  intervenes  be- 
tween the  external  auditory  meatus  and  the  labyrinth  of  the  internal  ear  (figs.  496 
and  498a).  It  is  a  narrow  irregular  cavity,  varying  in  width  from  a  twelfth  to  a 
sixth  of  an  inch  (2  to  4  mm.),  and  having  a  total  height  of  a  little  more  than  half 
an  inch  (15  mm).  It  consists  of  two  parts,  a  lower  and  narrower,  bounded  exter- 
nally by  the  tympanic  membrane,  and  an  upper  and  wider  part,  called  the  attic,  or 
epitym|)anum,  which  is  continued  l^ackwards  as  the  mastoid  antrum  into  the  mas- 
toid air  cells.  It  is  prolonged  downwards  and  forwards  into  the  Eustachian  tube, 
through  which  it  communicates  with  the  pharynx.  It  contains  air,  and  it  is  crossed 
from  without  inwards  liy  a  movable  chain  of  bones — the  tympanic  ossicles — which 
conduct  viln-ations  from  the  membrana  tympani  to  the  internal  ear. 


Fig.  498. — Internal  View  of  Right  Membkana  Tympani.     (Enlarged.) 

Suspensory  ligament  of  malleus  INCUS 


HEAD  OF  MALLEUS 


CHORDA   TYMPANI 
NER  VE 


Tendon  of  tensor 
tympani 


HANDLE  OF  MALLEUS 
Tensor  tympani  muscle 

EUSTACHIAN  TUBE 


POSTERIOR  PORTION  OF 
RECESS  FOR  OSSICLES 
ABOVE  MEMBRANE 


FOOTPIEGE  OF  STAPES 


LENTICULAR  PROCESS  (OS 
ORBICULARE) 


Posterior  portion  of 
membrana  tympani 


The  roof  is  a  thin  plate  of  the  petrous  part  of  the  temporal  bone,  which 
separates  the  cavity  from  the  middle  fossa  of  the  skull. 

The  floor  is  narrower  than  the  roof.  It  is  formed  by  the  tympanic  plate, 
and  it  separates  the  cavity  from  the  jugular  fossa. 

The  outer  wall  is  formed  below  by  the  tympanic  membrane,  and  above  by 
a  part  of  the  squamous  portion  of  the  temporal  bone. 

The  chorda  tympani  nerve.,  which  traverses  the  outer  wall,  enters  by  a  minute 
orifice,  the  aperture  of  the  iter  chordae  posterius,  and  leaves  the  cavity  by  the 
iter  chordae  anterius,  which  leads  into  the  canal  of  Huguier.  The  Glaserian 
fissure  lies  immediately  below  the  latter  orifice,  but  these  minute  openings  are 
hidden  by  the  mucous  lining. 

The  inner  wall  is  vertical,  and  looks  directly  outwards.  It  presents,  antero- 
inferiorly,  a  rounded  prominence,  the  promontory,  marked  by  grooves  for  the  tym- 
panic plexus,  and  caused  by  the  first  turn  of  the  cochlea.  In  front  of  tlie  promon- 
tory, is  the  commencement  of  the  Eustachian  tube  (fig.  498a),  above  is  the  outer 
extremity  of  the  canal  for  the  tensor  tympani  muscle  bounded  by  a  prominent 
ridge  of  bone  called  the  cochleariform  process,  and  behind  it  is  a  recess,  the  sinus 
tympani,  which  intervenes  between  the  fenestra  ovalis  above  and  the  fenestra  ro- 


876 


ORGANS   OF  SPECIAL  SENSE 


tunda  below.  The  fenestra  ovalis  leads  into  the  vestilmle  of  the  internal  ear  (fig. 
498a),  and  in  the  recent  state  it  lodges  the  base  of  the  stapes.  The  fenestra  rotunda 
is  closed  by  the  secondary  membrane  of  the  tympanum,  which  separates  the 
scala  tympani  of  the  cochlea  from  the  tympanic  cavity.  Above  the  fenestra  ovalis 
there  is  a  rounded  ridge  of  l)one,  indicating  the  position  of  the  afjueduct  of  Fallo- 
pius,  Avhich  contains  the  facial  nerve. 

The  posterior  wall  presents  the  hollow  pyramid  which  lodges  the  stapedius 
muscle  and  the  openings  which  lead  into  the  mastoid  cells;  these  vary  much  in 
size,  and  receive  a  mucous  lining  from  the  cavity. 

Anteriorly  the  tympanic  cavity  is  continued  int(j  the  Eustachian  tube,  and 
it  is  separated  from  the  carotid  canal  by  a  thin  plate  of  bone. 

The  Eustachian  tube  is  about  one  and  a  half  inches  (37  mm.)  in  length, 
passes  from  the  tympanum  downwards,  forwards,  and  inwards.  It  is  partly 
bony  and  partly  cartilaginous. 

The  osseous  portion  (fig.  498a)  is  about  half  an  inch  (13  mm.)  in  length.  It 
commences  just  below  the  orifice  which  transmits  the  tendon  of  the  tensor  tympani 
muscle,  and,  gradually  contracting,  ends  at  the  isthmus  by  a  jagged  and  oblique 
orifice  iDetween  the  petrous  and  squamous  portions  of  the  temporal  bone.  To  it  is 
attached  the  cartilaginous  portion  of  the  tube,  which  is  about  an  inch  in  length 


Fig.  498a. — Horizontal  Sectiox  of  Left  Temporal  Boxe,  showing  the  Various 

Parts  of  the  Ear. 


EXTERNAL  MEATUS 


MASTOID  AIR  CELLS 


TYMPANIC  RING  TYMPANUM 

FLOOR  OF  TENSOR  TYMPANI   CANAL 
EUSTACHIAN  TUBE 
I  COCHLEA 

CAROTID  CANAL 


INTERNAL  MEATUS 
AQUEDUCTUS  FALLOPII 
POINTER  PASSING  THROUGH  FENESTRA  OVALIS 


(24  mm.).  This  is  composed  of  an  elongated  triangular  plate,  so  folded  upon  itself 
as  to  leave  an  interval  below  which  is  completed  by  fibrous  tissue.  At  first  the 
canal  is  narrow^  but  it  becomes  much  expanded  towards  its  trunq)et-shaped 
termination.  Its  orifice,  which  is  somewhat  oval,  opens  into  the  ui)per  part 
and  side  of  the  pharynx,  on  a  level  with  and  just  behind  the  inferior  meatus  of 
the  nose. 

The  mucous  membrane  possesses  a  ciliated  lining.  It  is  thin  near  the  tym- 
panic cavity,  but  it  is  much  more  vascular,  thicker,  and  possesses  mucous  glands 
and  adenoid  tissue  near  its  pharvngeal  orifice. 

Sections  of  the  cartilaginous'  portion  of  the  tuljc  show  that  the  cartilagmous 
plate  is  curled  round  like  a  hook  Avith  the  bend  above  and  the  shank  mternal. 
The  membranous  portion  is  thin  whore  it  is  attached  to  the  tip  of  the  hook,  but 
that  it  becomes  much  thicker  below.  A  small  space  near  the  bony  portion  of 
the  tube,  immediately  below  the  hook,  remains  permanently  open,  but  elsewhere 
the  walls  are  in  contact,  except  when  separated  by  the  action -of  the  tensor  palati 
muscle,  or  when  forcibly  driven  asunder,  as  in  the  act  of  sneezing,  etc. 

A  number  of  small  sesamoid  fibro-cartilages,  some  of  wdiich  are  visible  to  the 
naked  eve,  are  buried  in  the  submucous  tissue. 


THE  MIDDLE  EAR 


877 


The  ossicles  of  the  ear  are  described  on  pages  66-6S. 
Articulation  of  the  Ossicles. — The  malleus  with  the  incus. 

The  oblong  articular  surface  which  descends  as  far  as  the  neck,  on  the  posterior 
surface  of  the  head  of  the  malleus,  is  divided  into  two  portions  by  a  nearly  vertical 
edge.  The  incus  presents  a  corresponding  surface  similarly  divided  into  two  por- 
tions, and  both  of  these  surfaces  are  coated  l)y  a  delicate  layer  of  hyaline  cartilage. 
A  thin  capsule,  from  the  inner  surface  of  which  a  delicate  wedge-shaped  meniscus 
projects  from  above  into  the  cavity  of  the  joint,  is  attached  to  the  grooves,  Avhich 
limit  the  articular  surfaces.  The  mechanism  has  been  compared  by  Helmholtz  to 
the  check  movement  inside  the  key  of  a  Geneva  watch,  and  permits  considerable 
gliding  Ijetween  the  two  l>ones. 

The  incus  with  the  stapes. — This  joint  is  formed  by  the  convex  surface  of  the 
lenticular  process  (orbicular  bone)  which  terminates  the  long  crus  of  the  incus 
and  the  corresponding  concave  surface  of  the  head  of  the  stapes.  Both  surfaces 
are  covered  with  a  layer  of  hyaline  cartilage. 

The  elastic  capsular  ligament  permits  but  very  slight  separation  between  the 


Fig.  499. — Section  of  the  Ty.aipaxum,  etc.     (Enlarged.) 


HEAD  OF  MALLEUS 


LONG  CRUS  OF  INCUS 
BASE  OF  STAPES 
HEAD  OF  STAPES 

ORBICULAR  BONE,  OR 

LENTICULAR  PROCESS 

EUSTACHIAN  TUBE 


Fibrous  layer  of 
membrana  tympani 


CAVITY  OF  TYMPANU^ 


Suspensory  ligament 

ATTIC  OF  THE  TYMPANUM 

External  ligament 

SHORT  CRUS  OF  VALLEUS 

—   HANDLE  OF  MALLEUS 

_    EXTERNAL  AUDITORY  CANAL 


."  I  ,  /       I  ;  ' 


bones.  Init  allows  a  somewhat  freer  lateral  movement.  This  articulation  has  been 
regarded  by  some  writers  as  a  synchondrosis,  but  it  is  now  usually  described  as  a 
true  joint. 

The  stapes  with  the  margin  of  the  fenestra  ovalis. — The  so-called  annular 
ligament  is  not  equally  l)r()ad  throughout,  and  con-sists  of  elastic  fibres  which 
radiate  as  they  pass  outwards  from  the  edge  of  the  footpiece  of  the  stapes  to  the 
margin  f)f  the  fenestra.  According  to  Toynbee,  these  edges  are  covered  by  a  tliin 
layer  of  cartilage. 

The  Ligaments  of  the  Ossicles. — In  addition  to  the  capsular  ligaments  al- 
ready described,  certain  well-marked  bands  limit  the  movements  of  the  ossicles. 

The  superior  ligament  of  the  malleus  descends  as  a  firm  rounded  band  from 
the  up|)er  and  outer  wall  of  the  tym])anic  cavity  to  the  head  of  the  malleus.  It 
limits  the  outward  movement  of  the  linndle  of  tlie  malleus. 

The  anterior  ligament  of  the  malleus  is  broad  and  strong.  According  to 
Helmholtz  it  encircles  the  long  process  of  the  malleus,  and  is  inserted  into  the 
fore  part  of  its  neck  and  head. 


878  ORGAXS  OF  SPECIAL  SENSE 

Some  of  the  fil)re.s  of  this  ligament  have  been  descriljed  as  musevilar  under  the 
name  of  the  laxator  tynipani  muscle.  But  although  occasionally  nuiscular  fibres 
can  be  detected,  in  the  majority  of  cases  they  appear  to  be  absent. 

The  external  ligament  of  the  malleus  prevents  the  handle  of  the  malleus 
being  turned  too  much  outwards.  It  passes  from  the  margins  of  the  notcli  of  Ri- 
vinus  to  the  short  process  of  the  malleus. 

The  ligament  of  the  incus. — The  short  crus  of  the  incus  is  covered  Avith  a  layer 
of  fibro-cartilage  and  rests  on  a  depression  of  the  posterior  tymi)anic  Avail,  close 
to  the  oritice  leading  into  the  mastoid  cells.  The  posterior  ligament  l)inds  the 
process  to  this  Avall. 

The  Muscles  of  the  Tympanum. — Two  muscles — the  tensor  tympani  and  the 
stajjedius,  Ijoth  of  which  lie  "within  bony  canals — transmit  their  tendons  into  the 
cavity  of  the  tympanum  for  insertion  into  the  chain  of  ossicles. 

The  tensor  tympani  is  a  penniform  muscle  about  half  an  inch  in  length;  it 
arises  in  small  part  from  the  cartilaginous  Eustachian  tube  and  adjacent  surface  of 
the  sphenoid  l)one  as  well  as  from  the  Avail  of  the  canal  in  Avhich  it  lies.  The 
tendon,  Avhich  extends  outAvards  almost  at  a  right  angle  to  the  belly  of  the  muscle, 
can  1)6  traced  some  distance  iuAvards  on  its  loAver  aspect.  It  is  inserted  on  the 
inner  margin  of  the  handle  of  the  malleus,  near  its  root.  The  tendon  glides 
Avithin  a  sheath  continuous  Avith  the  periosteum  lining  the  canal  and  surrounded 
by  mucous  membrane.  This  muscle  draAvs  the  handle  of  the  malleus,  and  Avith  it 
the  membrana  tympani,  iuAvards. 

The  stapedius  is  a  pyriform  muscle;  it  arises  from  the  interior  of  the 
pyramidal  eminence  Avhich  projects  from  the  posterior  Avail  of  the  tympanum. 
The  tendon,  Avhich  can  he  traced  iuAvai-ds  for  more  than  half  the  length  of  the 
muscle,  passes  through  the  aperture  at  the  summit  of  the  eminence,  to  be  inserted 
into  the  posterior  aspect  of  the  neck  of  the  stapes.  Its  tendon,  like  that  of  the 
tensor  tympani,  is  surrounded  b}''  a  fibrous  sheath  enveloped  in  the  tympanic 
mucous  membrane.  This  muscle  depresses  the  posterior,  Avhilst  at  the  same  time 
it  slightly  raises  the  anterior,  end  of  the  footpiece  of  the  stapes. 

Nerves. — The  stapedius  is  supplied  by  the  facial  nerve.  The  tensor  tympani 
receives  a  filament  from  the  otic  ganglion  Avhich  is  probably  derived  from  the 
motor  portion  of  the  fifth  nerve. 

The  Mucous  Membrane  of  the  Tympanum  is  continuous  through  the  Eusta- 
chian tube  with  that  Avliich  lines  the  pharynx.  It  is  thin  and  transparent,  and  in 
places  it  is  easily  detached. 

Several  vascular  folds  extend  from  the  tympanic  Avails  to  the  ossicles,  all  of 
Avhich  receive  a  complete  coA'cring  of  mucous  membrane. 

The  folds  divide  parts  of  the  cavity  into  pouch-like  recesses,  four  of  Avhich, 
lying  in  relation  Avith  the  malleus,  are  of  some  importance;  they  are  the  superior 
and  inferior  external  pouches  and  the  anterior  and  posterior  pouches  of  Troltsch. 
The  superior  external  pouch  lies  in  the  epitympanic  region,  to  the  outer  side  of 
the  heads  of  the  malleus  and  incus,  and  above  the  anterior  and  external  ligaments 
of  the  malleus,  Avhich  separate  it  from  the  inferior  external  pouch  beloAV.  The 
inferior  external  pouch  lies  betAveen  the  last  mentioned  ligaments  above  and  the 
short  process  of  the  malleus  beloAV.  It  is  of  special  clinical  importance  because  it 
is  bounded  externally  by  the  flaccid  portion  of  the  membrana  tympani,  anteriorly 
it  is  closed  but  posteriorly  it  opens  into  the  general  cavity.  The  pouches  of 
Troltsch  lie  in  front  of  and  behind  the  handle  of  the  malleus,  and  they  are  sepa- 
rated by  a  fold  of  mucous  membrane  Avhich  envelops  the  chorda  tympani  nerve. 

The  mucous  membrane  of  the  roof  of  the  tympanum  and  that  Avhich  lines 
the  meml)rana  tympani  and  covers  the  ossicles  ])ossesscs  a  flattened  non-ciliated 
epithelium.  ElscAvhere  for  the  most  part,  including  the  Eustachian  tube,  it  is 
columnar  and  ciliated. 

Vessels  and  nerves  of  the  tympanum. — Arteries. — The  tympanic  branch 
of  tile  internal  maxillary  Avhich  passes  through  the  Glaserian  fissure,  and  the  stylo- 
mastoid branch  of  the  posterior  auricular  Avhich  passes  through  the  Falloi)ian 
canal,  supply  the  front  and  back  part  of  the  tympanic  cavity,  and  form  a 
vascular  chain  around  the  circumference  of  the  membrana  tympani.  In  addition 
to  these  chief  branches  the  hiatus  Fallopii  transmits  the  petrosal  branch  from  the 


THE  EAR 


879 


middle  meningeal,  whilst  fine  branches  leave  the  carotid  artery  as  it  traverses  the 
carotid  canal  and  pass  into  the  tympanic  cavity.  The  ascending  pharyngeal  sends 
branches  to  the  Eustachian  tube,  some  of  which  reach  the  tympanum. 

Veins. — The  veins  empty  into  the  superior  petrosal  sinus  and  into  the  tem2)oro- 
maxillary  vein. 

Nerves. — The  tympanic  mucous  membrane  is  supplied  by  the  tympanic  plexus 
whicli  occu})ies  the  grooves  on  the  ijromontory  and  inner  wall  of  the  cavity. 

The  i)lexus  is  formed  l^y  the  follcjwing  nerves. 

The  tympanic  branch  of  the  glosso-pharyngeal,  which  enters  the  cavity 
through  a  foramen  in  the  floor;  a  communicating  branch  from  the  carotid  plexus 
of  the  sympathetic,  which  passes  tlirough  the  carotid  canal. 

A  branch  from  the  great  superficial  petrosal,  Avhich  enters  by  the  inner  wall 
close  in  front  of  the  fenestra  ovalis;  and  one  from  the  small  superficial  petrosal, 
which  enters  near  the  canal  for  the  tensor  tympani. 

The  course  of  the  chorda  tymj^ani  nerve  has  already  been  sufhciently  indicated 
(page  762). 

THE  INTERNAL  EAR,  OR  LABYRINTH 

The  INTERNAL  EAR,  or  LABYRINTH,  is  the  essential  part  of  the  organ  of 
hearing,  and  receives  the  terminations  of  the  auditory  nerve. 

The  Osseous  Labyrinth  is  divided  into  three  portions:  the  vestibule,  the 
semicircular  canals,  and  tlie  cochlea — recesses  holloAved  in  the  substance  of  the 
})etro\is  portion  of  the  temporal  l>one. 


Fig.  500. — The  OssEors  Labyrinth  of  the  Right  Side. 
(Modified  from  Soeminening.     Enlarged.) 


Superior  semicircular  canal 


Posterior  semicircular  canal 
External  semicircular  canal 
Vestibule  and  fenestra 


Second  turn  of  cochlea 
Apez  of  cochlea 


Ampulla 
Fenestra  rotunda 
Commenceinent  of  first  turn  of  the  cochlea 


The  Vestibule  lies  between  the  cochlea  and  semicircular  canals,  on  the  inner 
side  of  the  tymi)anum  (tig.  489a).  It  is  a  laterally  compressed  ovoidal  cavity,  and 
is  about  one-fifth  of  an  inch  in  horizontal  and  vertical  measurement. 

The  outer  wall  i)resents  the  fenestra  ovalis  filled  with  the  foot-piece  of  the 
stapes  and  its  annular  ligament.  On  its  inner  wall  there  is  a  small  saucer-like 
depression,  the  fovea  hemispherica,  perforated  ])elow  and  in  front  by  several 
minute  orifices  f  macula  cribrosa)  for  the  filaments  of  the  auditory  nerve.  Imme- 
diately behind  this  is  a  vertical  ridge,  the  i^yramidal  eminence  or  crista  vestibuli, 
behind  which  is  the  orifice  of  the  aqueductus  vestibuli. 

On  the  roof  there  is  a  second  dcjjression,  oval  in  slia|)c,  the  fovea  hemiellip- 
tica.     The  two  depressions  are  separated  by  tlie  pyramidal  eminence. 

Behind,  the  semicircular  canals  open  by  five  orifices;  and  in  front  by  means 
of  a  large  oval  opening,  apertura  scalae  vestibuli,  the  vestibular  cavity  com- 
municates with  the  scala  vestibuli  of  the  cochlea. 

The  Three  Semicircular  Canals  are  placed  above  and  behind  the  vestibule. 
They  are  unequal  in  length,  but  each  forms  the  greater  part  of  a  circle,  is  laterally 


880 


ORGANS  OF  SPECIAL  SEXSE 


compressed,  and  measures  about  one-twentieth  of  an  inch  (l-o  nnn.)  in  diameter. 
One  extremity  of  each  canal  is  suddenly  dilated  to  nearly  double  its  size  to  form 
the  ampulla.  As  two  of  the  canals  join  to  open  by  a  common  oritice,  collectively 
they  present  only  five  o])enings. 

The  superior  semicircular  canal,  the  highest  of  the  canals,  is  almost  vertical, 
and  is  directed  transversely.  A  smooth  eminence  on  the  anterior  surface  of  the 
petrous  l)one  closely  corresponds  to  the  summit  of  its  arch.  Its  ampullary  end  is 
at  the  outer  extremity,  and  presents  a  separate  opening  at  the  upper  part  of  the 
vestibule;  the  opposite  end,  which  is  not  dilated,  joins  to  form  a  common  orifice 
with  .the  similar  extremity  of  the  posterior  canal. 


Fig.  501. — Interior  of  the  Osseous  Labyrinth  of  the  Left  Side. 
(Modified  from  Soemmerring.     Enlarged.) 

Superior  Bemiciroular  oanal 


Fovea  hemielliptiea 
Fovea  hemispherica 


Lamina  spiralis 


Seala  tympani  of 
the  cochlea 


Posterior  semicircular  canal 


External  semicircular  oanal 
Orifice  common  to  the  superior 

and  posterior  semicircular 

canals 
Orifloe  of  the  vestibular 
aqueduct 


Orifice  of  the  cochlear  aqueduct 


The  posterior  semicircular  canal  is  the  longest.  Its  dilated  end  is  placed  at 
the  lower  and  back  part  of  the  vestibule;  its  non-dilated  extremity  joins  the 
superior  canal.      It  is  placed  nearly  vertically,  and  is  directed  backwards. 

The  external  semicircular  canal  curves  horizontally  outwards,  and  presents 
two  openings,  of  which  the  anterior  is  ampullated,  in  the  upper  and  back  part  of 
the  vestibular  cavity. 

The  Cochlea  has  a  rough  resemblance  to  a  snail's  shell,  and  coils  itself  almost 
horizontally  immediately  in  front  of  the  vestibule.  Its  base  corresponds  to  the 
lower  and  front  part  of  the  fundus  of  the  internal  auditory  meatus  (fig.  498a), 


Fig.  502. — Interior  of  the  Osseous  Cochle.\.     (Enlarged.) 


Scala  vestibuli 


Scala  tympani 


i— i^>_i_     Lamina  spiralis 


and  is  there  marked  by  the  series  of  minute  holes  which  form  the  tractus  spiralis 
foraminulentus,  whilst  its  apex  is  directed  forwards  and  outwards,  towards  the 
u}»i)er  and  fore  part  of  the  inner  wall  of  the  tympanum. 

The  cochlea  is  about  a  quarter  of  an  inch  (6  mm.)  in  length,  and  its  basal  meas- 
urement is  nearly  the  same.  It  is  composed  of  a  central  pillar,  tbi'  modiolus,  or 
columella,  around  which  curls  for  two  and  a  half  turns  a  spiral  canal,  which 
contains  a  delicate  spiral  shelf  or  plate,  the  lamina  spiralis.  This  ])artially  divides 
its  cavity  into  two  portions,  as  it  follows  its  windings  from  base  to  ajx'x.  Near  the 
apex  it  ends  in  a  hook-like  process,  the  hamulus,  which  bounds  a  small  opening, 


THE  EAR  881 

the  helicotrema.  The  osseous  spiral  canal  is  nearly  an  inch  and  a  half  (about 
3"5  cm.)  in  length.  The  lamina  spiralis  is  thin  and  dense  in  structure  at  its  edge, 
hut  it  is  spongy  and  channelled  ^vith  canals  for  nerves  and  blood-vessels  where  it 
starts  shelf-like  from  the  modiolus. 

The  spiral  canal  of  the  modiolus  coils  round  the  pillar  as  it  tunnels  the  base 
of  the  spiral  lamina. 

In  the  recent  state,  membranous  structures  complete  the  bony  partition  into  two 
separate  chambers,  or  scalse:  the  scala  vestibuli  and  the  scala  tympani,  which 
communicate  through  the  helicotrema  at  the  summit  of  the  cochlea. 

The  scala  vestibuli  commences  from  the  cavity  of  the  vestibule;  in  its  first  turn 
it  is  somewhat  narrower  than  the  scala  tympani. 

The  scala  tympani  commences  at  the  fenestra  rotunda,  which  is  filled  with  the 
secondary  membrane  of  Scarpa,  and  forms  a  kind  of  window  which  shuts  it  off 
from  the  cavity  of  the  tympanum.  Near  its  commencement  is  the  small  orifice  of 
the  aqueductus  cochlese,  which  lodges  a  minute  vein,  and  forms  a  communication 
with  the  subarachnoid  sjiace. 

The  central  axis,  or  modiolus,  extends  from  the  base  to  the  apex  of  the  cochlea. 
It  starts  with  a  Ijroad  base  where  it  corresponds  Avith  the  first  turn  of  the  cochlea, 
and  it  is  pierced  by  minute  canals  to  receive  the  filaments  of  the  cochlear  division 
of  the  auditory  nerve.  In  the  second  coil  the  axis  is  diminished  by  more  than 
half,  and  it  terminates  in  the  remaining  half  coil  or  cupula  in  a  bony  plate,  the 
infundibulum,  which  expands  towards  the  summit  of  the  cochlea,  with  which  it 

Fict.  503. — Section  uf  the  Osseous  Cochlea.     (Enlarged.) 


Lamina  spiralis 


Scala  tympani 


Termination  of  internal  auditory  meatus 

becomes  continuous.  The  central  canal  of  the  modiolus  runs  through  its 
centre. 

The  Membranous  Labyrinth,  which  lies  within  the  bony  labyrinth  just  de- 
scribed, receives  the  terminations  of  the  auditory  nerve.  It  is  for  the  most  part 
separated  by  the  perilymph  from  the  membrane  Avhich  lines  the  bony  chambers, 
and  it  contains  within  its  own  cavity  the  fluid  endolymph.  In  the  vestiljule  and 
semicircular  canals  it  bears  a  near  resemblance  (tliough  it  is  much  smaller)  to  the 
enclosing  structures.  V)Ut  in  the  cochlea  it  not  only  divides  the  bony  canal  into  the 
two  scalar,  but  forms  between  them  a  third  space,  the  canal  of  the  cochlea. 

Within  the  vestibule  the  membranous  labyrinth  consists  of  two  sacs,  which 
do  not  directly  communicate:  the  utricle,  connected  with  the  semicircular  canals; 
and  the  saccule,  with  the  cochlea. 

The  Utricle  is  the  larger.  It  is  oblong,  laterally  compressed;  it  occupies  the 
upper  and  back  ]5art  of  the  cavity,  and  is  in  contact  with  the  wall  of  the  fovea 
hemielliptica.  Filaments  of  the  auditory  nerve  are  distributed  to  the  wall  of  the 
sac  opposite  the  crista  vestibuli,  passing  through  the  bony  foramina  already  de- 
scribed. Its  wall  is  here  thicker  than  elsewhere,  and  calcareous  particles  (otoliths) 
are  attached  to  its  inner  surface.  Behind,  the  cavity  communicates  by  five  orifices 
with  the  semicircular  canals. 

The  Saccule,  which  is  slightly  flattened,  occupies  the  front  and  lower  part  of 
the  cavity  at  the  opening  of  the  scala  vestibuli  of  the  cochlea.  From  the  hollow  of 
the  fovea  hemispherica  it  receives  numerous  nerve  filaments,  and  presents  a  thick- 
ened area  with  attached  otoliths. 

.56 


882 


ORGAXS    OF  SPECIAL   SEXSE 


The  membranous  canal  of  the  cochlea  is  connected  with  the  saccule  by  a  short 
canal;   canalis  reuniens. 

The  two  sacs  are  indirectly  connected  by  means  of  a  small  tube,  ductus  endo- 
lymphaticus.  which  leaves  the  saccule,  joins  the  commencement  of  a  minute  canal 
which  passes  to  the  utricle,  and  descends  in  the  aqueductus  vestibuli  to  terminate 
in  an  enlargement,  the  saccus  endolymphaticus. 


Fig.  504. — Membranous  Labyrixth  (magnified),  with  Nerves. 
(Modified  from  Breschet.) 


BRANCH  TO  POSTERIOR 
CANAL 

SACCULE 
BRANCH  TO  SACCULE 
BRANCH  TO  COCHLEA 


BRANCH  TO  SUPERIOR  AND 
EXTERNAL  CANALS 


BRANCH  TO  UTRICLE 
FACIAL  NERVE 


Within  each  semicircular  canal  the  membranous  labyrinth  occupies  less  than 
a  third  of  the  area  of  the  tube,  but  follows  its  curves  and  repeats  its  ampullary 
enlargement;  and  here  the  wall  of  the  membranous  canal  is  thicker  and  more 
opaque,  and  more  completely  fills  the  cavity.  The  membranous  ampullse  are 
flattened  on  their  external  walls,  where  they  receive  vascular  and  nervous' filaments, 


Fig.  505.— Enlarged  Diagrammatic  View  of  Membranous  Labyrinth. 


SCALA  MEDIA  OF 
COCHLEA 


SUPERIOR 
SEMICIRCULAR 
CANAL 


EXTERNAL 
SEMICIRCULAR 
CANAL 


POSTERIOR 
SEMICIRCULAR 
CANAL 


and  their  cavities  are  partially  divided  by  a  transverse  crest  or  ridge  (crista  acustica). 
The  outer  convex  l)order  of  each  membranous  canal  is  fixed  to  the  osseous  wall. 

Structure. — The  membranous  labyrinth  consists  of  three  layers:  a  tunica 
propria,  witli  a  fibrous  investment  externally,  and  an  epithelial  lining  Avithin. 

Within  the  cochlea,  the  membranous  structures  divide  the  canal  into  thrcii 
compartments.     The  lamina  spiralis  (which  in  macerated  specimens  only  partially 


THE  EAR 


883 


divides  it)  is  continued  into  a  projection  from  the  periosteum  of  the  outer  wall 
(spiral  ligament)  by  means  of  a  distinct  membrane,  membrana  basilaris,  thus 
completely  roofing  in  the  scala  tymi)ani  which  before  connnunicated  with  the  scala 
vestibuli.  In  addition,  a  delicate  membrane,  the  membrane  of  Reissner, 
stretches  from  the  upper  surface  of  the  lamina  internal  to  its  free  edge  to  the 
periosteum  of  the  outer  wall,  shutting  off  a  small  triangular  space  (scala  media) 
from  the  scala  vestibuli ;  the  sides  of  this  space  are  bounded  by  the  tw^o  membranes 
(basilar  and  Reissner),  and  its  base  which  lies  externally  is  formed  by  the  osseous 
wall  with  its  periosteal  lining.  This  canal  is  lined  with  epithelium,  winds  through 
the  whole  length  of  the  cochlea,  and  is  commonly  known  as  the  ductus  cochlearis, 


Fig.  506. — Enlarged  View  of  Longitudinal  Section  of  the  First  Turn  of  the 
Cochlea,  showing  the  Positions  and  Boundaries  of  the  Three  Scal^. 


MEM3RANE  OF  REISSNER    — 
SCALA  MEDIA    -^ 

MEMBRANA  BASILARIS 


SCALA  VESTIBULI 


SPIRAL  GAXGLIOX 


SCALA  TYMPANl 


or  membranous  canal  of  the  cochlea.  It  ends  blindly  by  pointed  extremities, 
one  situated  at  the  apex  of  the  cochlea  and  the  other  at  its  base,  the  latter  lies  in 
relation  with  the  floor  of  the  vestibule  and  receives  the  small  canal  already 
described,  the  canalis  reuniens,  which  proceeds  from  the  saccule.  The  canal  of 
the  cochlea  and  the  saccule  are  thus  brought  into  communication. 

The  Auditory  Nerve  divides  into  two  portions  before  it  reaches  the  fundus 
of  the  internal  auditory  meatus. 

The  superior  division  consists  of  three  branches  which  pass  to  the  crista 
vestibuli,  through  special  openings,  to  be  distributed  to  the  utricle  and  the  ampul- 
lary  enlargements  of  the  superior  and  external  semicircular  canals. 

The  inferior  division  supplies  the  cochlea  through  the  foramina  of  the  tractus 
foraminulentus;  also  a  Ijranch  to  the  saccule,  the  filaments  of  whicli  pass  through 
the  openings  of  the  fovea  hemispherica;  and  a  longer  branch  to  the  posterior 
semicircular  canal,  which  reaches  it  by  a  special  channel,  the  foramen  singulare, 
situated  behind  the  foramina  which  transmit  the  filaments  to  the  saccule. 

Vessels. — The  internal  auditory  branch  of  the  basilar  artery,  which  accom- 
panies the  auditory  nerve,  supplies  both  the  vestibule  and  cochlea,  with  their 
membranous  contents.  The  veins  correspond  and  open  into  the  inferior  petrosal 
sinus,  which  also  receives  the  minute  veins  which  traverse  the  aqueductus 
vestibuli. 


THE    TONGrE 

By  ARTHUR  HENSMAN,  F.R.C.S. 
Revised  for  Second  Edition  by  ARTHUR  ROBINSOX,  M.D.,  M.R.C.S. 

LECTURER   ON   ANATOMY   IN   THE  MIDDLESEX   HOSPITAL  MEDICAL    SCHOOL  ;     EXAMINER  IN   ANATOMY   FOR    THE 

CONJOINT   BOARD  OF   ENGLAND 


The  tongue  is  a  freely  inoval)le,  highly  sensitive,  and  muscular  organ,  and  is 
endowed  witli  the  special  sense  of  taste.  It  participates,  moreover,  in  the 
function  of  speech,  and  plays  an  important  part  in  mastication  and  deglutition. 

Its  upper  surface,  or  dorsum,  with  its  sides  and  tip,  are  free,  whilst  its  Ijase  is 
attached  by  muscles  to  tlie  hyoid  bone  and  lower  jaw.  Folds  of  mucous  membrane 
loosely  connect  it  with  the  epiglottis  and  soft  palate,  as  well  as  Avith  the  symphysis 
of  the  lower  jaw.  From  beneath  its  rounded  borders  the  mucous  covering  liecomes 
continuous  with  the  inner  surface  of  tlie  gums.  The  anterior  two-thirds  of  the 
tongue  occupies  the  floor  of  the  mouth,  lying  between  the  halves  of  the  lower  jaw, 
with  its  convex  dorsum  overarched  by  the  vault  of  the  palate,  and  its  sides  and  tip 
in  contact  with  the  teeth  and  gums.  The  posterior  third  of  the  dorsum,  situ- 
ated in  the  anterior  wall  of  the  pharynx,  forms  a  rounded  surface  overhanging  the 
epiglottis. 

The  mucous  membrane,  which  is  really  a  modified  skin,  covers  the  whole  of 
the  free  surface  of  the  tongue.  It  forms  three  folds:  the  glosso-epiglottidean  in 
connection  with  the  epiglottis;  and  on  each  side  of  the  median  fold — fraenum 
epiglottidis — is  formed  the  glosso-epiglottidean  pouch,  or  vallecula,  which 
is  bounded  externally  hy  the  more  rounded  lateral  fold.  On  each  side  of  the 
tongue,  near  the  junction  of  the  posterior  and  middle  third,  the  membrane  ascends 
to  form  the  anterior  pillars  of  the  fauces,  and  in  front  beneath  the  tip  it  forms 
the  sharp  fold  of  the  fraenum  linguae  (fig.  509),  which  extends  forwards  to  the 
back  of  the  symphysis. 

A  slight  longitudinal  groove,  the  median  raphe,  divides  the  dorsum  of  the 
tongue  along  its  anterior  two-thirds.  It  ends  posteriorly  near  a  small  foramen, 
the  foramen  caecum,  which  represents  the  upper  termination  of  the  thyro-glossal 
duct.  The  orifice,  however,  is  not  at  all  constant  in  the  adult  tongue,  although 
occasionally  it  is  present  and  may  sometimes  lead  into  the  still  patent  duct  which 
tunnels  the  tongue  as  far  as  the  body  of  the  hyoid  bone.  The  course  of  the 
obliterated  duct  may  in  many  cases  be  demonstrated. 

The  foramen  ctecum  is  easily  seen  in  the  foetus  at  the  angle  of  meeting  of  two 
shallow  grooves  which  form  tlie  V-shaped  line  liehind  the  circumvallate  papilke. 
These  grooves  indicate  the  line  of  junction  of  the  anterior  and  posterior  portions 
of  the  tongue,  and  are  faintly  visible  in  the  adult  organ. 

The  papilhe  crowd  the  anterior  two-tliirds  of  the  dorsum  as  well  as  the  sides 
and  tip  of  the  tongue,  l)ut  at  the  back  they  are  small  and  hidden  ))y  the  epithelial 
coating.      Of  the  papilhe  three  chief  kinds  can  be  distinguished. 

The  circumvallate  or  calyciform  papillae  are  the  largest,  but  they  are  few  in 
number,  varying  from  seven  or  eight  to  twelve,  and  they  form  a  V-shaped  line  in 
front  of  and  parallel  witli  the  grooves  already  mentioned. 

884 


THE   TONGUE 


88i 


Each  papilla  presents  a  narrow  attached  base  and  a  broad  free  end  and  is 
seated  in  a  circular  cup  which  is  surrounded  bv  a  rim  or  vallum.  ' 

Upon  the  bases  of  most  of  these  papilla?  a  central  depression  marks  the  orifice 
ot  one  or  more  glands.  Secondary  i^apillae  lie  hidden  under  the  thick  epithelial 
covering  both  of  the  chief  papilla  and  the  circular  rim  which  surrounds  it. 

The  fungiform  papillae  are  more  thinly  covered  with  epithelium,  and  are  redder 
in  colour  than  the  smaller  papillae  amongst  which  thev  are  scattered.  They  occur  ir- 
regularly over  the  dorsum,  sides,  and  tip  of  the  tongue^  and  are  most  numerous  in  the 
two  latter  situations ;  each  papilla  is  attached  by  a  comparatively  narrow  base  and 
has  a  broader,  rounded,  and  free  extremity,  studded  with  smaller  secondary  papilla? 


EXTREMITY  OF  CORNU  OF       False  voeal  cord 

HYOIO  BONE 

SUPERIOR  CORNU  OF  THYROID 
CARTILAGE 

LATERAL  GLOSSO- 
EPIGLOTTIDEAN  FOLD 


Fig.  507. — Dorsum  of  the  Toxgue. 

lower  end  of  pharynx 


ANTERIOR  WALL  OF  THE 
PHARYNX 

CORNICULUM  LARYNGIS 

-    CUNEIFORM  CARTILAGE 

SINUS  PYRIFORMIS 

True  voeal  cord 


MEDIAN  GLOSSO- 
EPIGLOTTIDEAN  FOLD 


J  vf   ^ff' 


POSTERIOR  PILLAR  OF  FAECES 


A:<TERI0R  pillar  of  FAUCES 


CIRCUMVALLAtE  PAPILL/E 


ADENOID  TISSUE  AT  BACK  OF 
TONGUE 


FORAMEN  C/tCUM 


FUNGIFORM  PAPILL/€ 


The  filiform  or  conical  papillae,  named  from  their  general  shape,  thickly  beset 
the  whole  of  the  dorsum,  sides,  and  tip  of  the  tongue  in  front  of  the  circumVallate 
group.  They  faintly  ridge  the  organ  with  delicate  lines,  Avhich  posteriorly  lie 
parallel  with  the  circumvallate  papillae,  but  become  more  and  more  transverse  in 
direction  as  they  approach  the  tip  and  sides  of  the  tongue.  They  present  secondary 
papilke  upon  their  surfaces  thickly  overlaid  with  epithelium. 

The  lingual  glands  are  especially  abundant  near  the  foramen  caecum  and  in 
the  neighborhood  of  the  circumvallate  papillae,  as  well  as  along  the  borders  of  the 
tongue. 


886 


ORGANS  OF  SPECIAL   SEXSE 


A  special  group  forms  an  elongated  mass,  the  gland  of  Nuhn,  on  either  side  of 
the  organ,  and  just  beneath  its  tip.  It  occupies  the  groove  between  the  genio-hyo- 
glossus  muscle  and  the  inferior  lingualis. 


Fig.  508.— The  Fcetal  Tuxoie. 


SUPESIOR  APERTURE  OF  GLOTTIS 


POSTERIOR  ROUNDED  PORTION  OF  TONGUE 


LOWER  PART  OF  PHARYNX 


FORAMEN   C/ECUM 
■      GROOVE  DIVIDING  ANTERIOR  AND  POSTERIOR 
PORTIONS  OF  TONGUE 

CIRCUMMLLATE  PAPILL,€ 


Fig.  509.— Uxdek  Surface  of  the  Tongue  with  .Muscles. 


FR/ENUM  LINGUA 


Lingualis  inferior 


Hyo-glos8U8 


Genio-hyoid 


Mylo-hyoid,  reflected 


Sterno-hyoid 


Lingualis  inferior 


Genio-hyo-glossuB 


'- —   Stylo-glossuB 
Hyo-glossus 
BODY  OF  HYOID  BONE 
Genio-hyoid 


THYROID  CARTILAGE 


The  mucous  membrane  of  the  posterior  third  of  the  tongue  contains  abundant 
lymphoid  tissue,  collected  into  rounded  masses.  This  often  becomes  much 
developed,  and  gives  to  this  part  of  the  tongue  an  irregular  nodular  appearance. 


THE   Toy  QUE 


887 


Fig.  510. — Teansveese  Section  theough  the  Left  Half  of  the  Tongue. 

(Magnified.) 

(From  a  preparation  by  Mr.  J.  Pollard,  Middlesex  Hospital  Museum. ) 

Transverse  muscular  fibres 


PAP!LL,€    — ^' 


Superior  lingual  — 
muscle 


Septum 


Inferior  lingual 
muscle,  mixed 
•with  extrinsic 
fibres 


Vertical  muscular  fibres 


Fig.  511.— Side  View  of  the  Toxgve,  avith  its  Muscles. 

Stylo-glossuB 


DORSUM  Of  TONGUE 


Genio-hyo-gloBsus 
Genio-hyoid 


GREATER  CORNU  OF  HVOID  BONE 


STVLOIO  PROCESS 

Stylo-hyoid 

POSTERIOR  PORTIOn 
OF  TONGUE 


Stylo-pharyngeus 


HyO-glOBBUS 

Thyro-hyoid 
ligament 

CARTIUGO  TRITICEA 


Thyro-hyoid 
membrane 


THYROID  CARTIUGE 


Median  portion  of 
crico-thyroid 
membrane 

CRICOID  CARTILAGE 
FIRST  RING  OF  TRACHEA 


888  ORGANS  OF  SPECIAL  SENSE 

A  fibrous  septum  separates  the  halves  of  the  tongue  and  extends  in  the  middle 
plane  from  base  to  apex;  and  a  strong  fibrous  membrane,  the  hypoglossal  mem- 
brane, passes  from  l)eneath  the  l>ase  of  the  tongue  to  the  body  of  tlie  liyoid  bone. 

The  Muscles  of  the  Tongue. — The  muselesdf  the  tongue  are  both  extrinsic, 
and  special  or  intrinsic. 

The  extrinsic  muscles  are  the  hyo-glossus,  genio-hyo-glossus,  stylo-glossus, 
palato-glossus,  and  a  small  part  of  the  superior  constrictor.  (For  extrinsic  mus- 
cles of  tongue  see  pages  451-454. ) 

The  intrinsic  muscles. — The  lingualis  superior  constitutes  a  superficial 
longitudinal  stratum,  which  extends  from  the  liase  to  the  tip  of  the  organ,  imme- 
diately beneath  the  mucous  membrane.  The  fil)res  form  short  fascicles  attached  to 
the  overlying  tissues,  and  are  placed  between  the  hyo-  and  stylo-glossi  muscles  of 
the  opposite  sides  of  the  tongue,  both  pairs  of  which,  near  the  base,  overlap  the 
fibres  of  the  lingualis. 

The  inferior  lingualis  is  composed  of  two  bands  which  reach  from  the  base  to 
the  apex  on  the  under  surface  of  the  tongue.  Posteriorly  some  of  the  fibres  become 
attached  to  the  body  of  the  hyoid  bone.  Each  of  these  bands  is  placed  between 
the  hyo-  and  genio-hyo-glossus,  and  near  the  tip  some  of  its  fibres  mix  Avith  those 
of  the  stylo-glossus  muscle. 

The  transverse  fibres  mixed  with  fat  lie  l:)etween  the  two  muscles  just  de- 
scriljed,  and  form  a  considerable  part  of  the  bulk  of  the  tongue.  Tliey  take  origin 
from  the  luedian  fibrous  septum,  and,  curving  outwards  and  upwards,  are  inserted 
into  the  sides  and  dorsum  of  the  organ. 

The  vertical  fibres  decussate  with  the  transverse,  and  pass  from  the  dorsum  to 
tlie  under  surface  of  the  tongue  in  curves  with  their  concavities  looking  outwards. 
The  fi1>res  become  shorter  as  they  approach  the  margin  of  the  tongue. 

Arteries. — The  arteries  are  derived  from  the  lingual,  facial,  and  ascending 
pharyngeal. 

Nerves. — The  nerves  are — the  lingual  branch  of  the  mandibular  division  of 
the  fifth,  which  supplies  the  papillae  of  the  fore  part  and  sides  of  the  tongue;  the 
lingual  branch  of  the  glosso-pharyngeal,  which  supplies  the  base  and  sides,  in- 
cluding the  circumvallate  papilla';  the  fine  branches  from  the  superior  laryngeal, 
which  reach  the  root  close  to  the  epiglottis,  and  a  lingual  branch  from  the  facial 
(Testut). 

The  hypoglossal  supplies  the  muscular  substance  of  the  tongue,  as  well  as  most 
of  the  extrinsic  muscles;  and  the  chorda  tympahi'IHi-ouglV  the  facial  contributes 
also  some  filaments.  ^      ./ 


THE    NOSE 

By  ARTHLR  HENSMAN,  F.R.C.S. 
Revised  foe  Second  Edition  by  ARTHUR  ROBINSON,  M.D.,  M.R.C.S. 

LECTURER  OS    ANATOMY   IN   THE  MIDDLESEX   HOSPITAL  MEDICAL  SCHOOL;    EXAMINER    IN  ANATOMY    FOR  THE 

CONJOINT     BOARD   OF   ENGLAND 


The  nose  includes  a  visible  external  portion,  the  nose  proper ;  and  an  internal 
cavity,  the  nasal  fossa. 

The  Nose  Proper  is  triangular  in  shape;  its  root  al)ove  is  at  the  forehead,  from 
which  the  bridge  or  dorsum  slopes  downwards  and  forwards  to  end  in  a  rounded 


Piu.  512. — Side  View  of  the  Nose,  showing  its  Cartilages,  etc. 


NASAL  PROCESS  OF  THE  MAXILLA 

UPPER  LATERAL  CARTILAGE 
CARTIUGE  OF  SEPTUM 


OUTER  PLATE  OF  LOWER  LATERAL 
CARTILAGE 


INNER  PLATE  OF  LOWER  UTERAL 
CARTILAGE 


ACCESSORY  QUADRATE  CARTILAGES 
Fibrous  tissue 
SESAMOID  CARTILAGES 

CELLULAR  TISSUE  FORMING  ALA 


tip  or  lobe.    The  base  beloAv  overhangs  the  upper  lip:  it  here  presents  two  orifices, 
the  nostrils,  which  are  divided  l)y  the  columna. 

The  nostrils  are  protected  hy  stiff  hairs,  and  each  opens  into  a  cavity,  extending 
a  little  above  the  cartilages,  called  the  vestibule.  Its  sides  slo])e  from  the  dorsum 
outwards  and  backwards,  and  terminate  below  in  the  alae  <>r  wings,  whicli  l)ound 
the  nostrils  externally.  It  presents  a  dense  unyielding  bony  framework,  formed 
by  the  two  nasal  bones,  with  the  nasal  processes  of  the  maxilla?  above,  and  l>v  the 

889 


890 


ORGANS   OF  SPECIAL  SEXSE 


projecting  anterior  nasal  spine  below.  To  this  is  added  a  yielding  cartilaginous 
portion,  which  completes  the  organ,  and  forms  its  chief  part. 

The  nose  is  enveloped  in  skin,  lined  by  a  mucous  membrane,  and  supi^lied  Avitli 
vessels  and  nerves,  and  its  cartilages  are  acted  upon  by  small  nmscles. 

The  cartilages. — The  principal  cartilages  are  five  in  number  :  a  i)air  above,  the 
superior  lateral;  a  pair  below,  the  inferior  lateral;  and  the  cartilage  of  the 
septum,  the  persistent  unossified  remnant  of  the  facial  segment  of  the  chondro- 
cranium  (page  90).  With  these  must  be  included  a  group  of  small  irregular 
cartilages  known  as  sesamoid  and  accessory  quadrate. 

The  cartilages,  ensheathed  in  perichondrium,  are  for  the  most  part  loosely 
held  together  by  tough  intervening  fibrous  tissue,  and  this  in  turn  becomes  con- 
tinuous with  the  periosteum  of  the  surrounding  bones. 

The  upper  lateral  cartilages  are  nearly  flat  and  somewhat  triangular  in  shape, 
each  presenting  an  outer  and  an  inner  surface. 

Their  anterior  margins  are  continuous  above  with  the  rounded  borders  of  a 
shallow  groove  which  furrows  the  cartilage  of  the  septum;  but  below  for  about  two- 
thirds  of  their  extent,  though  their  edges  are  closely  applied  to  the  borders  of  the 


Fig.  513. — Antekiok  View  of  the  Nose,  showing  its  Cartilages,  etc. 


ORIFICE  OF  LACHRYMAL  CANAL 


GROOVE  ON  ANTERIOR  BORDER  OF 
SEPTAL  CARTILAGE 

ACCESSORY  QUADRATE  CARTILAGES 1_  ^^— -Z-"^ 

SESAMOID  CARTILAGES 

CELLULAR  TISSUE  OF  ALA 


«L NASAL  PROCESS  OF  THE  MAXILLA 


UPPER  LATERAL  CARTILAGE 


OUTER  PLATE  OF  LOWER   LATERAL 
CARTILAGE 


groove,  there  is  on  each  side  a  narrow  cleft  of  separation  Avhich  opens  out  below 
into  an  angular  notch. 

Their  curved  posterior  margins  are  firmly  attached  superficially  by  somewhat 
jagged  edges  to  the  nasal  bones;  but  deeply,  and  especially  near  the  septum,  they 
underlie  these  bones  for  a  considerable  distance. 

The  rest  of  the  border  is  smooth,  free,  and  loosely  connected  by  intervening 
fibrous  tissue  to  the  nasal  process  of  the  maxilla. 

Their  inferior  borders  are  connected  with  the  lower  lateral  cartilages;  one  or 
more  narrow  plates  of  cartilage  occasionally  intervene  and  fill  the  fibrous  interval. 
On  account  of  their  continuity  Avith  the  septal  cartilage,  the  upper  lateral  cartilages 
should  be  regarded  as  its  wings  or  lateral  expansions.      (Henle. ) 

The  lower  lateral  cartilages  are  thin,  pliant,  and  curved,  and  so  folded  back- 
wards that  each  forms  an  inner  and  an  outer  plate. 

The  inner  plates  are  loosely  attached  to  one  another,  where  they  meet  below 
the  sejitum  to  form  the  tip  of  the  nose  and  fore  part  of  the  columna. 

The  outer  plates  are  oval,  and  curve  backwards  above  the  masses  of  dense 
cellular  tissue  which  form  the  alee.  They  maintain  the  contour  of  the  nostrils, 
and  serve  to  keep  these  orifices  open.  Posteriorly  they  are  connected  by  fibrous 
tissue  to  the  nasal  margins  of  the  superior  maxillary  Itones. 


THE  XOSE 


891 


In  this  tissue  are  embedded  several  extremely  tliin  and  irregular  cartilages 
named  sesamoid,  and  above  these  commonly  a  pair  still  smaller,  called  accessory 
quadrate. 

The  septal  cartilage  fills  in  the  triangular  interval  of  the  bony  septum.  The 
anterior  border  is  attached  to  the  nasal  bones  at  their  junction  below  the  crest. 
Beyond  it  presents  a  shallow  groove,  the  borders  of  M-hich  are  at  first  continuous 
with  the  upper  lateral  cartilages,  as  already  described.  This  groove  becomes 
narrowed  by  the  gradual  approximation  of  its  borders,  which  ultimately  meet  in  a 
faint  transverse  ridge  below.  Still  lower,  it  dips  for  a  short  distance  between  the 
inner  plates  of  the  lower  lateral  cartilages,  Avhich  meet  bej'ond  it  to  form  the  tip 
of  the  nose. 

The  posterior  border  is  connected  with  the  perpendicular  plate  of  the  ethmoid, 
wdiilst  its  inferior  is  attached  to  the  vomer,  which  is  often  channelled  like  the 
ethmoid  plate  to  receive  it.  The  anterior  part  of  the  lower  border  is  attached  to 
the  anterior  nasal  spine. 

The  cartilage  does  not  simply  dip  into  the  groove  which  is  more  or  less  marked 
on  the  upper  surface  of  the  nasal  spine,  Vjut  broadens  out  to  obtain  the  widest 
possible,  though  somewhat  lax,  attachment  to  it.  Viewed  from  below,  it  appears 
to  embrace  the  spine.      The  border  of  its  rounded   angle  in  front  is  somewhat 


Fig.  .514.  — Uxder  Vikw  of  the  Xose,  showixg  its  Cartilages,  etc. 

septal  cartilage 


OUTER  PLATE  OF  LOWER   LATERAL 
CARTILAGE 


INNER  PLATE  OF   LOWER  LATERAL 
CARTIUGE 


NASAL  SPINE  OF  THE  MAX'LLA 


SEPTAL  CARTILAGE 
Cellular  tissue  of  ala 


thickened  before  terminating  in  a  thin  smooth  edge.  It  is  extremely  thin  near  the 
centre. 

The  shape  of  the  sejital  cartilage  varies  in  relation  to  the  extent  of  ossification 
in  the  bony  septum,  and  even  in  the  adult  a  strip  of  cartilage  may  extend  for  a 
varying  distance  backwards  and  upwards  between  the  vomer  and  ethmoid,  some- 
times even  reaching  the  body  of  the  sphenoid  bone. 

It  may  be  here  noted  that  the  septum  of  the  nose  is  almost  always  straight  in 
children  and  in  aboriginal  skulls  (eighty  per  cent.);  but  in  Europeans  it  is  deflected 
to  one  or  other  side  in  the  proportion  of  three  out  of  every  four. 

Jacobsonian  cartilages. — In  the  septal  cartilage  above  the  opening  of  Stenson's 
canal  there  is  a  small  pouch  which  presents  a  minute  opening  below.  This  is  the 
representative  of  the  so-called  .lacobsonian  organ.  A  strip  of  cartilage  underneath 
this,  firmly  adherent,  but  distinct  from  the  septal  cartilage,  is  known  as  the  Jacob- 
sonian cartilage. 

Muscles. — The  muscles  are  seven  in  number,  and  may  be  grou]ied  as  dilators 
and  constrictors.     The  latter  are  comparatively  feeble  in  their  action. 

The  dilators. — The  pyramidaUs  nasi  is  a  downward  prolongation  of  the 
oceipito-frontalis.  Each  muscle  descends  on  the  side  of  the  nose,  to  blend,  after 
becoming  tendinous,  with  the  compressor  nasi.  They  diverge  from  one  another  as 
they  pass  downAvards.  The  levator  labii  superioris  alaeque  nasi  arises  from  the 
nasal  process  of  the  maxilla. 


892 


ORGANS   OF  SPECIAL  SENSE 


It  divides  in  its  passage  downwards,  one  slip  being  inserted  into  tlie  eartilage  of 
the  wing,  the  other  extending  to  the  ui)per  lij)  to  l)lend  with  its  nmscidar  fibres. 

The  tAvo  foregoing  niuseles  may  be  regarded  as  extraordinary-  or  reserve  muscles 
of  dilatation. 

The  dilator  naris  consists  of  two  small  muscular  slips,  requiring  a  lens  for 
their  proper  demonstration;  in  some  cases  they  are  absent. 

The  dilator  naris  anterior  is  a  small  and  indistinct  muscle.  It  is  placed 
between  the  skin  and  cartilage  of  the  ala. 

The  dilator  naris  posterior  arises  from  the  edge  of  the  nasal  notch  of  the 
maxilla  and  the  sesamoid  cartilages,  to  be  inserted  into  the  margin  of  the  nostril. 
In  paralysis  of  the  facial  nerve,  a  deep  insjdration  through  the  nostril  j^roduces 
complete  collapse  of  its  cartilaginous  wall,  thus  showing  tlie  importance  of  the 
dilator  muscles  in  keeping  patent  the  nasal  orifices. 

The  constrictors,  or  compressors. — The  compressor  naris  arises  from  the 


Fig.  515. — Section  showixg  Boxy  and  Caetilagixous  Septum. 
The  dotted  lines  indicate  the  coarse  of  the  anterior  palatine  canal. 


Frontal  sinus 


Sphenoidal  sinus 


UPPER  LATERAL  CARTILAGE 

Groove  between  septal 
and  upper  lateral 
eartilage 


LOWER  LATERAL 


THICKENED  BUKUEH  OF  CARTILAGE  RESTING  I  \  Pouch  at  upper 

UPON  ANTERIOR  NASAL  SPINE  Incisive  papilla      \  extremitv  of  St( 


ORIFICE  OF  EUSTACHIAN 
Sten-  TUBE 

SEPTAL  CARTILAGE  8°°'^  °^°^1  SOFT  PALATE 


maxilla  near  the  incisive  fossa,  its  fibres  mixing  with  those  of  the  levator  anguli 
oris.  It  expands  as  it  passes  inwards,  to  end  in  a  thin  aponeurosis,  which  joins 
with  its  fellow  as  well  as  with  the  pyramidalis,  and  it  also  blends  with  the  sul)- 
cutancous  tissue  over  the  bridge  of  the  nose. 

The  depressor  alae  nasi  arises  from  the  incisor  fossa;  its  fibres  pass  upwards 
to  the  septum  and  ])osterior  part  of  the  Aving. 

The  compressor  narium  minor  consists  of  a  few  indistinct  fibres,  occasionally 
found  between  the  alar  cartilage  and  skin  over  the  tip  of  the  nose. 

Tliese  muscles  are  all  supplied  by  the  facial  nerve. 

The  skin  covering  the  nose  is  for  the  most  part  thin  and  freely  movable  ujjon 
the  subjacent  parts,  Init  at  the  tij)  and  over  the  cartilages  it  is  much  thicker  and 
more  adherent  and  furnished  with  numerous  sebaceous  glands. 

The  mucous  membrane  becomes  continuous  with  the  skin  at  the  nasal  orifices, 
and  ])osteriorly  with  the  membrane  which  lines  the  nasal  fossse. 


THE  NOSE 


893 


The  vessels. — The  arteries  of  the  nose  which  arise  from  the  facial  are  the 
lateralis  nasi  and  tlie  artery  to  the  septum  derived  from  the  coronary  of  the  same 
trunk.  This  latter  also  supplies  the  ala.  The  nasal  branch  of  the  ophthalmic 
and  infraorbital  are  distributed  to  the  sides  and  dorsum. 

The  veins  terminate  by  joining  the  facial  and  ophthalmic. 

The  nerves. — The  nerves  are  sup])lied  by  the  facial,  which  is  motory,  and  by 
the  infratrochlear  and  nasal  branch  of  the  ophthalmic  division  of  the  fifth  and  the 
infraorljital  nerve,  which  are  sensory. 

The  nasal  fossae. — The  nasal  fossae  have  been  already  described  (page  79). 

The  mucous  membrane  (pituitary  or  Schneiderian). — In  the  recent  state  the 
area  of  the  fossie  is  much  contracted  l)y  its  mucous  lining.  This  is  loosely  folded 
around  the  lower  edges  of  the  turl)inal  bones,  and  extends  beyond  them  in  front 
and  behind.  Especially  is  this  marked  where  it  envelops  the  inferior  turbinal 
bone,  and  it  is  here  very  thick  and  spongy.  It  is,  moreover,  thick  where  it  covers 
the    septum,    but    thin  at  the  bottom   of    the   meatuses  and  within   the  sinuses. 


Fjg.  olG.— Muscles  of  the  Nose.      (After  Bourgerj-.) 

i 


Levator  labii  superioris 
alseque  nasi 


Accessory  slip  of  compressor 
naris 


Dilator  naris  posterior 


Orbicularis  oris 


Oceipito-lrontalis 


Fyramidalis  nasi 


Compressor  naris 


\^^ Dilator  naris  anterior 

i^— ^^ —    Compressor  narium  minor 


Some  of  the  openings  into  the  nasal  cavities  which  are  apparent  in  the  dried  skull 
are  quite  hidden  in  the  recent  state;  those,  however,  which  lead  into  the  air-spaces 
together  with  the  lachrymal  duct  remain  patent,  though  the  bony  orifices  are  mucli 
reduced  in  size.  There  is  a  small  conical  closed  sac,  close  to  the  septum  at  its 
fore  part,  which  indicates  the  position  of  the  now  obliterated  canal  of  8tenson. 
The  termination  is  marked  in  the  mouth  by  the  incisive  pajiilla.  The  membrane 
is  continuous  in  front  through  the  anterior  nares  with  the  skin;  behind,  it  extends 
through  the  posterior  nares  to  line  the  naso-pharynx,  the  Eustachian  tube,  the 
tympanum  and  the  mastoid  cells.  It  is  intimately  adherent  to  the  periosteum  and 
perichondrium.  The  acinous  glands  which  are  imbedded  in  its  structure  secrete 
for  the  most  j)art  a  thin  wateiy  fluid.  They  are  especially  large  over  the  inferior 
turbinal  bone,  and  very  numerous  at  the  middle  and  back  of  the  fossae  near  the 
orifices  of  the  posterior  nares. 

The  vestibule  is  lined  with  a  scaly  epithelium;    more  posteriorly  the   nasal 
cavity  is  divided  into  an  upper  olfactory  and  a  lower  or  respiratory  region.     The 


894 


ORGAXS  OF  SPECIAL   SEysE 


olfactory  region  is  lined  with  a  columnar  unciliated  epithelium.  The  mucous 
membrane  is  here  of  a  yello^vish  colour,  thicker  than  elsewhere,  and  contains  the 
olfactory  cells  of  Max  Schultze. 

The  lower  or  resi)irat(»ry  is  a  much  wider  portion,  in  wliicli  the  eiiithelium  is 
columnar  and  cihated,  and  includes  the  inferior  turbinal  l)()ne  with  the  lower  jjart 
of  the  fossa. 

Immediately  l)eliind  the  vestilnilc  there  are  Iavo  shallow  depressions  separated 
by  a  ridge,  the  agger  nasi,  or  naso-turl)inal;  the  area  below  the  ridge  is  the  atrium 
of  the  middle  meatus.  It  is  bounded  posteriorly  by  the  anterior  vertical  border 
of  the  middle  turbinal,  beneath  which  it  is  continued  into  the  middle  meatus.  The 
upper  depression  is  the  sulcus  olfactorius;  it  leads  upwards  and  backwards  to  the 
olfactory  region  of  the  nasal  fossa. 

The  roof  })resents  Ijut  one  opening  posteriorly,  which  leads  into  the  sphenoidal 
sinus.     The  orifices  in  the  cribriform  plate  are  entirely  closed  over. 


Fig.  517. — Oblique  Section   passing  through  the  Nasal  Foss.e,  just  in   front  of  the 
Posterior  Xares.     (Seea  from  behind.) 


Front  wall  of  left 
sphenoidal  sinus 
with  orifice  below 


Orifice  of  right  sphe-  .   

noidal  sinus 


SUPERIOR  TURBINAL    _. 
BONE  ff, 


MIDDLE  TURBINAL  BONE 


ORIFICE  OF  EUSTACHIAN 
TUBE 


UPPER  SURFACE  OF 
SOFT  PALATE 


CRISTA  GALL! 


A  closed  anterior 
ethmoidal  cell 

""/^^/v POSTERIOR  ETHMOIDAL 

CELLS 


RIGHT  ANTRUM  WITH 
ORIFICE 


INFERIOR  TURBINAL 
BONE 


ORIFICE  OF  EUSTACHIAN 
TUBE 


In  the  floor  the  openings  leading  into  the  anterior  palatine  canal  are  closed. 
The  small  cul-de-snc  already  described  indicates  their  position. 

The  superior  meatus  is  the  shortest  of  the  three;  it  lies  in  the  posterior  third 
of  the  outer  wall  under  cover  of  the  sujserior  turbinal  bone,  and  it  has  but  a  single 
opening,  which  leads  into  the  posterior  ethmoidal  cells.  The  spheno-palatine 
foramen  is  entirely  covered  by  membrane. 

The  middle  meatus  lies  in  the  pcisterior  two-thirds  of  the  nasal  chamber  under 
cover  of  the  middle  turbinal  bone.  On  its  outer  Avail  is  a  rounded  eminence,  the 
bulla  ethmoidalis,  which  is  perforated  by  the  aperture  of  the  middle  ethmoidal 
cells;  and  in  front  and  below  this  is  a  curved  groove,  the  sulcus  semilunaris,  whicli 
is  continued  above,  by  the  infundil)ulum,  into  the  frontal  sinus;  it  receives  the 
openings  of  the  anterior  ethmoidal  cells  and  the  antrum. 

The  inferior  meatus  is  the  longest  of  the  three;  it  lies  under  cover  of  the 
inferior  turbinal  bone,  and  it  receives  the  nasal  duct  anteriorly.  The  mucous 
membrane  is  arranged  around  the  opening  in  a  circular  valve,  the  valve  of  Hasner, 
which  is  sometimes  double  (page  8G8). 


THE  NOSE 


89o 


Fig.  518.— Section-  of  the  Xcse,  showing  the  Tuebixal  Bones  and  Meatises, 
WITH  the  Openings  ix  Dotted  Outline. 


Orifice  of  middle  ethmoidal  cells 
SUPERIOR  TURBiNAL  BONE 
Oriflee  of  the  posterior  ethmoidal  cells 
Orifice  of  the  sphenoidal  sinus 
Sphenoidal  sinus 


Frontal  sinus 


Orifice  of  frontal  sinus 


UPPER  ORIFICE  OF 
NASAL  DUCT 


ORIFICE  OF  EUSTACHIAN 
TUBE 
MIDDLE  TURBINAL  BONE 


LUAER  ORIFICE  OF  NASAL  DUCT 


l.'<F£RIOR  TURBiNAL  BONE        ORIFICE  OF  THE  ANTRUM        ORIFICE  OF  INFUNDIBULUM 


Fig.  519.— Transverse  Section  passing  through  the  Nasal  Foss^  and  Avtr\   \t  the 
Posterior  Extremity  of  the  Middle  Turbinal  Bone.     (Seen  from  the  front.'; 


Frontal  sinuses  < 


MIDDLE  TURBINAL 
BONE 


RIGHT  ANTRUM  — >? J-^"-  >-. 

INFERIOR  TURBINAL       ''•^^^^^ 
BONE 


896 


OBGANS   OF  SPECIAL  SESSE 


The  nerves. — The  olfactory  or  special  nerves  of  smell,  the  filaments  of 
which  pas^s  through  the  foramina  in  the  criljriform  plate  of  the  ethmoid  bone,  lie 
for  some  distance  in  the  grooves  of  the  bony  walls  before  terminating  in  the 
Schneiderian  membrane. 

Those  which  supply  the  septum  ramify  in  its  upper  fifth,  whilst  those  which 
reach  the  outer  Avails  are  distributed  in  two  groups — a  posterior,  to  sui)ply  the 
membrane  covering  the  superior  turbinal  bone,  and  an  anterior,  to  ramify  in  the 
membrane  over  the  middle  turbinal  bone  and  the  smooth  surface  of  the  ethmoid 
in  front  of  this. 

In  addition  to  the  special  nerves  of  smell,  the  cavity  is  supplied  Avith  nerves  of 
common  sensation  derived  from  the  fifth  pair. 

The  nasal  branch  of  the  ophthalmic  supplies  the  front  and  upper  part  of  the 
septum,  the  anterior  part  of  the  roof  and  also  the  anterior  part  of  outer  Avail  of 
the  nasal  fossa. 

The  Vidian,  Avith  the  upper  nasal  branches  of  Meckel's  ganglion,  supply 


FRONTAL  SINUS 


Fig.  520. — Nera'es  of  the  Nasal  Caa'ity. 

na  sa  l   olfa  ctor 1 " 
xeh  ve       ner  ve 


OLFA  CTOR  Y  NER  VE 
TO  SUPERIOR  TUR- 
BINA  TE  BONE 

SPHENOIDAL  SINUS 


VIDIAN  NERVE 

MECKEL'S 
\  GANGLION 

^7—  DESCENDING 
PALATINE 

ORIFICE  OF  EUSTACHIAN 
TUBE 

NASAL  BRANCHES 


POSTERIOR 

PALATINE 
ANTERIOR 

PALATINE 
MIDDLE  PA  LA  TINE 


the  upper  and  back  portion  of  the  septum,  the  roof,  and  the4)Uter  Avail,  including 
the  superior  spongy  bone. 

The  naso-palatine  supplies  the  lower  and  posterior  portion  of  the  septum. 

The  anterior  dental  branch  of  the  maxillary  division  of  the  fifth  nerve  is 
distributed  to  the  anterior  pai't  of  the  inferior  meatus  and  inferior  turl)inal  bone. 

The  anterior  or  large  palatine  nerve  supplies  in  its  course  downwards  the 
posterior  })art  of  tlie  middle  and  Ljwer  turbinal  liones. 

The  arteries  are  distributed  asfolloAvs: — 

Tlie  spheno-palatine,  from  the  internal  maxillary  by  its  internal  or  naso- 
palatine branch,  supi)lies  the  septum  as  it  courses  doAVUAvards  and  forwards  in 
the  groove  on  the  vomer  to  the  incisor  foramen.  Its  external  branches  su]iply 
the  antrum  (also  supplied  by  the  alveolar  branch  of  the  facial)  and  frontal  sinus, 
the  ethmoidal  cells,  and  inner  surfaces  of  the  turbinal  bones  with  tlic  meatuses. 
It  enters  the  cavity  through  the  si^heno-palatine  foramen. 


THE  XOSE  897 

The  anterior  and  posterior  ethmoidal  arteries  derived  from  the  ophthahnic 
supi)ly  the  upper  purtiuii  i)t'  tlie  septum,  tlic  roof,  the  outer  wall  (anteriorly)  and 
the  anterior  and  posterior  ethmoidal  cells. 

The  descending  palatine  of  the  internal  maxillary  sends  a  few  small  hranches 
to  the  back  of  tlie  inferior  meatus  and  lower  turbinal  bone. 

The  Vidian  and  pterygo-palatine  supply  the  l)ack  part  of  the  roof. 

The  branch  to  the  septum  derived  from  the  superior  coronary  of  the  facial 
ramifies  in  the  membrane  covering  its  lower  and  front  portion. 

The  veins  form  a  plexus  in  the  mucous  membrane,  especially  marked  at  the 
lower  and  hinder  portions  of  the  fossa.  The  emissary  trunks  accompany  the 
arteries,  the  spheno-palatine  joins  the  pterygoid  plexus,  the  ethmoidal  pass  to 
the  ophthalmic  vein  but  also  have  communications  with  the  meningeal  veins,  and 
the  anterior  part  of  the  plexus  is  drained  by  veins  which  pass  forwards  to  termi- 
nate in  the  tributaries  of  the  facial  vein. 

Communications  are  formed  with  the  veins  within  the  cranial  cavity,  through 
the  cribriform  foramina  and  foramen  ceecum,  and  also  with  the  facial  vein  through 
small  foramina  in  the  nasal  bone  and  nasal  process  of  the  maxilla. 

The  lymphatics  form  a  well-developed  j^lexus,  which  communicates,  through 
the  lymphatics  surrounding  the  olfactory  nerves,  Avith  the  subdural  space  within 
the  cranial  cavity,  posteriorly  with  the  j^haryngeal  lymphatics,  and  anteriorly  with 
the  lymphatics  of  the  face. 


67 


SECTION    Til 

THE  THOKAX 

INCLUDING  THE   ORGANS   OF  VOICE, 
RESPIRATION,  AND  CIRCULATION 

By  ARTHUR  HENSMAX,  F.R.C.S. 
Revised  for  Second  Edition  by  ARTHUR  ROBINSON,  M.Tt.,  M.R.C.S. 

LECTURER  ON  ANATOMY  IN  THE  MIDDLESEX  HOSPITAL  MEDICAL  SCHOOL  ;    EXAMINER   IN  ANATOMY   FOR  THE 

CONJOINT  BOARD  OF  ENGLAND 


THE  THORAX 

THE  thorax,  or  trunk  of  the  body — l3'ing  between  the  neck  and  the  al)domen — 
is  formed  partly  of  bones  and  partly  of  soft  connecting  tissues.  In  the  living 
l)ody  it  is  constantly  varying  in  relation  to  the  respiratory  process.  The  cavity 
is  bounded  in  front  by  the  sternum  and  upper  six  costal  cartilages  and  internal 
intercostal  muscles;  behind  by  the  thoracic  veitebrse  and  posterior  ends  of  the 
ribs;  and  laterally  by  the  ribs  with  the  internal  and  external  intercostal  muscles. 

Its  form  is  conical,  flattened  in  the  adult  from  before  backwards,  so  that  its 
transverse  is  its  greater  diameter.  In  the  human  foetus,  as  in  the  lower  animals, 
it  is  flattened  laterally,  its  antero-posterior  diameter  being  the  greater. 

It  is  narrow  above,  where  the  ribs  are  short,  and  broad  below.  Owing  to  the 
backward  set  of  the  hinder  extremities  of  the  ril)s,  the  bodies  of  the  vertebne  pro- 
ject forwards  into  the  cavity,  which  thus,  on  a  transverse  section,  appears  more  or 
less  cordiforni. 

The  superior  aperture  is  Ixjundcd,  in  front  by  the  upper  margin  of  the  ster- 
num; behind  by  the  body  of  the  first  thoracic  vertebra;  on  each  side  l)y  the  first 
rib.  It  measures  in  a  well-formed  adult  al)out  two  and  a  quarter  inches  from  l)efore 
l)ackwards,  and  four  and  a  quarter  inches  from  side  to  side.  The  ribs  slope  down- 
Avards  towards  the  sternum,  the  upper  margin  of  Avhich  corresponds  to  the  inter- 
vcrtel^ral  substance  l^etween  the  second  and  tliird  thoracic  vertel)ra'.  It  transmits 
the  following  structures: — (1)  The  sterno-hyoid  and  sterno-thyroid  nuiscles.  and 
more  deeply  a  thin  layer  of  the  deep  cervical  fascia  whicli  blends  below  with  the 
sheath  of  the  great  vessels  and  the  pericardium;  (2)  the  tliynnis  gland  in  the  infant, 
or  its  shrunken  remains  in  the  adult;  (3)  an  occasional  middle  thyroid  artery,  the 
trachea,  the  oesophagus,  the  thoracic  duct,  the  longus  colli  muscles,  and  a  thin  layer 
of  fascia  overlying  them.  Laterally:  the  innominate  artery  (on  the  right  side),  the 
common  carotid  and  subclavian  (on  the  left),  with  the  internal  mannnary  and 
superior  intercostal  arteries;  the  innominate  and  inferior  thyroid  veins;  the  phrenic, 
pneumogastric,  and  sympathetic  nerves.  Avith  the  left  recurrent  laryngeal,  some 
cardiac  l>ranches,  and  the  anterior  ])ranches  of  the  first  thoracic   nerve.      On  each 

898 


THE  LOWER    OPENING 


899 


side,  ill  addition,  there  is  a  small  ])()rti()n  of  the  a])ex  of  the  lung  with  its  pleural 
covering. 

The  lower  opening,  or  base,  is  limited  in  front  l)y  the  ensiform  cartilage,  he- 
hind  hy  the  twelfth  thoracic  vertehra,  and  laterally  l)y  the  twelfth  rihs. 

The  diaphragm  arches  upwards  to  form  a  vaulted  floor  to  the  intervening  space. 
It  is  aliout  one  inch  higher  on  the  right  side  than  on  the  left,  and  its  flattened 
central  portion  is  lower  than  either  of  the  lateral  arches.  The  thoracic  cavity  is 
mucli  dee]icr  l)ehind  than  in  front. 

The  following  structures  i)ass  through  the  /out/- opening  of  the  thorax: — (1)  The 
aorta,  vena  azygos  major,  thoracic  duct,  the  trunks  of  the  eflerent  lymphatics  from 
the  lower  inten-ostal  spaces,  and,   occasionally,  the"  left  sym])athetic   nerve  pass 


Fig.  521. 


-Anterior  View  of  the  Thorax,  with  Outlines  of  the 
Diaphragm  and  Lungs. 


through  the  aortic  opening.  (2)  The  oesophagus,  pneumogastric  nerves,  and  some 
small  I  esophageal  arterial  branches  emi-rge  through  the  a^sophageal  o]iening. 

(o)  The  vena  cava  inferior  ascends  through  the  caval  opening,  and  the  branches 
of  the  phrenic  nerves  pierce  the  diajjhragm  to  reach  its  lower  surface. 

(4)  The  splanchnic  nerves,  the  vena  azygos  minor,  and  the  symi»athetic  trunk 
of  each  side  pass  tlirough  the  crura. 

The  viscera  contained  within  the  thoracic  cavity  are:  the  heart,  wliieh  is  en- 
closed in  the  ])ericar<lium;  and  the  lungs,  with  tlieir  ]ileural  investments. 

The  heart  lies  between  the  lungs  in  the  so-called  mediastinal  space.  This  is 
l)Ounded  on  each  side  by  the  reth'xions  of  the  ]>leune,  which  jiassfrom  the  front  to 
the  back  of  the  thoraci*-  cavity;  ami  tin;  connuon  space  is  further  subdivided  into 
a  superior  mediastinum  above  the  heart  sac,  an  anterior  and  a  posterior  resiK'C- 


900 


THE   THORAX 


lively  in  front  of  and  behind  it,  and  a  middle  mediastinum  which  contains  the 
heart  itself. 

The  superior  mediastinum  has  the  following  boundarii's: — the  nianulirium 
with  the  origins  of  tlie  stcrno-liyoid  and  sterno-thyroid  muscles  in  front ;  the  l)odies 
of  the  four  highest  thoracic  V('rtel)r;e  behind,  with  the  lower  i)ortions  of  the  longus 
colli  muscles;  and  on  each  side  the  })leural  sacs.  Above,  the  l)oundary  corresponds 
with  the  superior  aperture  of  the  thorax,  and  below  with  a  nearly  horizontal  plane 
passing  backwards  from  the  articulation  between  the  manul»rium  and  gladiolus  of 
the  sternum,  to  the  lower  part  of  the  body  of  the  fourth  thoracic  vertebra.     This 


Fig.  522. — Superior  View  of  a  Section  of  the  Thorax,  passing  through  the  Sternum 
immediately  below  the  first  costo-sternal  articulation,  through  the  trachea 
at  its  division,  and  through  the  body  of  the  fourth  thoracic  vertebra. 
(Braune.) 


Arch  of  aorta 
PHBENIC  NER  VE 


SECOND  COSTAL  CARTILAGE 


Axilla?  1/  if»! 


POSTERIOR  SURFACE  OF  STERNUM 
I'ena  cara  superior 

PHRENIC  NER  VE 

SECOND  COSTAL  CARTILAGE 


Axillary  rein 


THIRD  RIB 

SCAPULA 


SCAPULA 
THIRD  RIB 
FOURTH  RIB 


VAGVS  NERVE 

BODY  OF  FOURTH  THORACIC  VERTEBRA 


iower  plane  nearly  corresponds  with  the  upper  part  of  the  pericardium  and  roots  of 
the  lungs. 

The  superior  mediastinum  contains  the  thoracic  portion  of  the  trachea, 
oesophagus,  thoracic  duct,  the  arch  of  the  aorta,  the  innominate  artery,  thyroidea 
ima,  and  thoracic  portions  of  the  left  carotid  and  left  subclavian;  the  innominate 
veins  and  upper  i)art  of  the  superior  vena  cava,  the  terminations  of  the  inferior 
thyroid  and  internal  mammary  veins  of  both  sides,  and  the  superior  intercostal  vein 
of  the  left  side;  the  two  pneumogastric  nerves,  with  the  left  recurrent,  the  phrenic 
and  cardiac  nerves;  the  thymus  gland  or  its  remains,  and  some  bronchial  lymphatic 
glands,  with  the  superior  sterno-pericardiac  ligaments. 


THE  LARYNX  901 

The  middle  mediastinum  contains  the  heart,  the  ascending  portion  of 
the  aorta  and  tlic  ])uhnonary  artery,  the  superior  vena  cava  (lower  half),  all  of 
which  are  placed  within  the  pericardium;  and  in  addition  the  phrenic  nerves  and 
their  companion  arteries,  the  termination  of  the  azygos  vein,  the  roots  of  the  lungs, 
with  some  bronchial  lym])liatic  ghmds. 

The  anterior  mediastinum  is  narrow  above,  lying  Ijehind  the  sternum  op])osite 
the  second,  thiid,  and  luuith  cartilages.  Below,  it  o])ens  out  into  a  quadrangular 
space,  having  nearly  the  whole  of  the  lower  lialf  of  the  sternum,  the  lower  edge  of 
the  fourth,  the  fifth,  part  of  the  sixth,  and  the  termination  of  the  seventh  cartilages 
of  the  left  side,  Avith  the  triangularis  sterni  muscle  in  front  (fig.  521).  The  pericar- 
dium forms  its  posterior  wall.  The  space  merely  contains  some  small  lymphatic 
glands  and  areolar  tissue,  and  a  few  irregular  bands,  the  inferior  sterno-pericardiac 
ligaments,  with  the  thymus  gland  or  its  vestiges.  It  corresponds  to  the  area  of 
cardiac  dullness. 

The  posterior  mediastinum  is  bounded  in  front  by  the  roots  of  the  lungs  and 
posterior  surface  of  the  pericardium,  and  behind  by  the  thoracic  vertebral  column 
below  the  fourth  thoracic  vertebra.  On  each  side  it  is  bounded  by  the  pleural  sacs. 
It  contains  the  descending  aorta,  oesophagus,  and  pneumogastric  nerves,  azygos 
veins,  thoracic  duct,  and  lym])hatic  glands. 


THE  ORGANS  OF  VOICE 

THE  LARYNX 

The  larynx  is  the  organ  of  the  voice,  and  the  protector  of  the  air  passages  from 
the  intrusion  of  foreign  bodies.  By  its  closure,  moreover,  it  retains  the  air  within 
the  chest  cavity,  contril)uting  to  the  fixity  of  the  thorax,  a  condition  which  is 
essential  to  the  due  performance  of  a  variety  of  muscular  actions. 

It  consists  of  a  framework  of  cartilages  held  together  by  ligaments  and  acted 
U])()n  by  muscles  (extrinsic  and  intrinsic).  It  is  lined  by  a  very  sensitive  mucous 
membrane,  and  sup])lied  with  blood-vessels,  nerves,  and  lymphatics. 

The  cartilages  of  the  larynx  are  nine  in  numl)er.  '  Some  of  these  are  single, 
some  are  arranged  in  pairs. 

Single  cartilages  : —  Paired  cartilages  : — 

Thyroid.  Arytenoid. 

Cricoid.  Cornicula  larvngis  (Santorini). 

Epiglottis.  Cuneiform  ( Wrisberg). 

From  their  general  structure  they  may  be  arrranged  as  follows: — 

Hyaline  : —  Yellow  elastic  : — 

Thyroid.  E})igl()ttis. 

Cricoid.  Cornicula  larvngis. 

Arytenoid  (the  tip  of  the  arytenoid       Cuneiform, 
is  yellow  elastic). 

In  the  anteater  there  extends  backwards  from  each  side  of  the  epiglottis  to  the  summit  of 
the  arytenoids  a  continuous  rim  of  yellow  elastic  cartilage.  It  is  the  broken  remnant  of  this 
which  in  man  forms  tlie  cornicula  and  the  cuneiform  cartilages.     (Blaud  Sutton.) 

The  THYROID  CARTILAGE  forms  the  front  and  sides  of  the  upper  ])art  of  the 
l.'irvnx,  being  placed  al)Ove  the  cricoid.  It  consists  of  two  nearly  square  symmetrical 
plates,  or  alte,   united  in  front,  where  they  form  the  ponunn  Adami,  but  widely 


902 


THE   ORGANS   OF   VOICE 


separated  behind.  They  inchide  ])etween  them  an  angle  varying  from  80°  to  90°,  and 
are  somewhat  obhquely  inehned,  their  outer  surfaces  looking  slightly  downwards  as 
well  as  outwards.  Eaeh  plate  has  an  outer  and  an  inner  surface  and  four  borders. 
The  upper  and  lower  posterior  angles  of  each  plate  project  upwards  and  down- 
wards to  form  its  superior  and  inferior  cornua. 

The  outer  surface  is  smooth,  and  is  crossed  by  an  oblique  and  often  very  faintly 
defined  line,  or  by  an  occasional  filirous  band.  This  is  marked  at  each  extremity 
by  a  small  tu])ercle.  These  tubercles  are  more  pronounced  in  old  subjects.  The 
line  and  the  adjacent  cartilage  give  attachments  to  the  thyro-hyoid  and  sterno- 
thyroid muscles,  and  thi^  inferior  constrictor  which  overlaps  the  smaller  portion  of 
the  ala  lying  behind  the  line. 

The  inner  surface  is  also  smooth ;  it  is  concave,  and  in  contact  with  the  mucous 
membrane  which  lines  the  sinus  pyriformis,  with  branches  of  the  laryngeal  nerves  and 
vessels,  and  with  the  external  thyro-ar3'tenoid  and  lateral  crico-arytenoid  muscles. 


Fig.  523. — Front  View  of  the  Cartilages  of  the  Lakvxx. 

Bourgerv  and  Jacob.] 


BODY  OF  HYOIO  BONE 
Thyro-hyoid  ligament 

Cartilago  triticea 
Foramen  for  superior 
laryngeal  nerve 
Median  portion  of  thyro- 
hyoid membrane 
SUPERIOR  CORNU  OF  THYROID 
CARTIUGE 

MEDIAN  NOTCH  OF  THYROID 
CARTILAGE 

Fomum  Adami 


(Modified  from 


OBLIQUE  LINE  OF  THYROID 
CARTILAGE 


Crieo-thyroid  membrane 


INFERIOR  CORNU  OF  THYROID 
CARTILAGE 


THIRD  RING  OF  TRACHEA 


OBLIQUE  LINE  BELOW  SUPERIOR 

TUBERCLE 
WING  OF  CARTILAGE  BEHIND 

OBLIQUE  LINE 

OBLIQUE  LINE  ABOVE  INTERIOR 

TUBERCLE 

ANTERIOR  BORDER  OF  INFERIOR 
CORNU 


The  anterior  or  isthmic  border,  which  is  also  the  shortest,  corresponds  to  the 
junction  of  the  two  al;r  in  the  median  line  in  front;  very  prominent  above,  where 
it  forms  the  pomum  Adami,  it  becomes  depressed  before  again  ])rojecting  less 
markedly  l^elow.  Posteriorly,  at  the  angle  of  junction  it  gives  attachment  to  the 
stalk  of  the  epiglottis,  tlie  true  and  false  vocal  cords,  the  thyro-arytenoid  and  thyro- 
epiglottidei  muscles. 

The  superior  border,  which  gives  attachment  to  the  thyro-hyoid  membrane,  is 
sinuous.  Slightly  dc]  tressed  posteriorly,  it  rises  in  front,  and  then  becomes  abruptly 
scooped  out  and  everted  to  form  tlie  side  of  the  great  median  notch. 

The  inferior  border  is  somewhat  sinuous.  It  gives  attachment  in  front  to  the 
middle  portion  of  the  crico-thyroid  membrane,  and  Ix-hind  to  tlie  crico-thyi-oid 
muscle,  and  presents  the  small  tubercle  already  noticed  at  the  termination  of  the 
oV)lique  line. 


THE  LARYXX 


903 


The  posterior  border,  thick  and  rounded,  projects  above  and  below  into  the 
superior  and  inferior  eornua,  and  gives  partial  insertion  to  the  stylo-  and  palato- 
pharvngei  muscles. 

The  superior  eornua  jiroject  inwards  as  well  as  ui)wards  and  backwards.  To 
their  tijis  are  attachefl  the  thyro-liyoid  ligaments,  and  near  root  of  each  appears  the 
tultcrcle  at  tlic  upi)cr  end  of  the  oblique  line. 

The  inferior  eornua  are  short,  blunt  processes.  The}'  project  inwards  as  well 
as  downwards  and  forwards.  By  means  of  small  oval  concave  facets  (directed 
downwards  as  well  as  inwards)  placed  on  their  inner  faces,  the  inferior  eornua 
articulate  with  the  facets  on  the  sides  of  the  cricoid  cartilage.  They  give  partial 
attachment  to  the  inferior  constrictors  of  the  pharynx  and  crico-thyroid  muscles  in 
addition  to  the  ligaments  of  the  joint. 

The  CRICOID  CARTILAGE  is  thick  and  strong,  and  forms  a  complete  ring  around 
the  lower  part  of  the  larynx.      Behind,  it  presents  a  quadrate  surface,  but  narrows 


Fig.  524.— Side  View  of  the  Cartilages  of  the  Laeyxx.     (Modified  from 

Bourgery  and  Jacob.) 


Thyro-hyoid  membrane 


SUPERIOR  BORDER  OF  THYROID 


Crico-thyroid  rauBcle 
Crico-thyrojd  membrane 
median  portion 

Crico-thyroid  muscle 


THIRD  RING  OF  TRACHEA 


Thyro-hyoid  ligament 

CARTILAGO  TRITICEA 


SUPERIOR  CORNU 


Superior  tubercle 
Stylo-pharyngeus  and 
palato-pharyngeus 

Thyro-hyoid  muscle 


SURFACE  OF  ALA  OVERLAPPED  BY 
INFERIOR  CONSTRICTOR 


Stemo-thyroid  muecle  and 
inferior  tubercle 


Inferior  constrictor 


rapidly  in  its  anterior  half  to  only  one-fourth  or  one-fifth  of  its  posterior  de)>th. 
Hence  its  comparison  to  a  signet  ring.  It  thus  possesses  an  anterior  and  a  posterior 
portion,  and  a  superior  and  inferior  border,  and  presents  four  articular  surfaces. 

The  posterior  quadrate  portion  is  divided  behind  by  a  median  vertical  ridge 
which  separates  two  broad  and  shallow  depressions.  To  this  ridge  some  of  the 
longitudinal  fibres  of  the  oesophagus  are  attached,  and  the  depressions  give  origin 
to  the  posterior  crico-arvtenoid  muscles. 

The  anterior  portion  is  narrow  and  rounded,  and  gives  attachment  in  front  to 
the  crico-thyroid  muscles,  and  more  posteriorly  to  some  iil»res  of  the  inferior 
constrictor  of  the  pharynx. 

Between  these  two  halves  of  the  ring,  Init  nearer  the  lower  border,  is  jdaced  the 
oval  surface  (looking  upwards  and  outwards)  for  articulation  with  the  inferior  cornu 
of  the  thyroid  cartilage. 

The  inner  surface  is  smooth  and  lined  bv  mucous  membrane. 


904 


THE  ORGAXS   OF  VOICE 


The  superior  border  liounds  the  quadrate  plate  above,  and  then  passes  obUquely 
downwards  and  forwards.  An  oval,  convex,  obliqueh' placed  articular  surface,  upon 
which  moves  the  arytenoid  cartilage,  separates  these  two  portions  of  the  upper 
border  on  each  side. 

The  o])lique  half  gives  attachment  to  the  crico-thyroid  meml)rane,  and,  laterally 
and  external  to  this,  to  the  lateral  crico-arytenoid  muscle. 

The  inferior  border — horizontal,  and  often  deejily  notched  at  the  sides — is 
attached  to  the  tirst  ring  of  the  trachea  by  fibrous  membrane. 

The  arytenoid  cartilages  are  irregular,  three-sided  pyramids,  which  articulate 


Fio.  525. — Front  View  of  the  Cricoid  and  Arytenoid  Cartilages.     (Modified 

from  Bourgery  and  Jacob.) 


Thyro-arytenoideus  muscle 


Attachment  of  crieo-thyroid  muscle 


ANTERIOR  SURFACE  OF  ARYTENOID  CARTILAGE 


Cut  edge  of  capsular  ligament 
Lateral  crico-arytenoid  muscle 


MUSCULAR  EXTERNAL  ANGLE  OF  ARYTENOiO 
CARTIUGE 


Lateral  crico-arytenoid  muscle 

CRICOID  CARTILAGE 


l3y  their  leases  with  the  oblique  facets  on  the  superior  border  of  the  cricoid  cartilage, 
and  support  upon  their  apices  the  cornicula  laryngis. 

The  space  between  them  in  certain  animals  has  been  likened  to  the  mouth  of  a 
pitcher,  and  hence  their  name.  Each  cartilage  presents  three  surfaces,  divided  by 
three  borders,  with  a  base,  apex,  and  angles. 

The  surfaces. — The  posterior  is  concave,  smooth,  and  gives  attachment  to  the 
arytenoid  muscle. 

The  anterior  is  irregular  and  convex.  It  gives  attachment  by  a  small  tuljercle 
to  the  false  vocal  cord,  and  also  to  the  thvro-arvtenoid  muscle. 


Fig.  526. — Back  View  of  the  Cricoid  and  Arytenoid  Cartilages.     (Modified 
from  Bourgery  and  Jacob. ) 

CORNICULUM   LARYN&IS 


POSTERIOR  SURFACE  OF  ARYTENOID 


MUSCULAR  EXTERNAL  ANGLE 
Crico-arytenoid  joint 


MEDIAN  RIDGE 


POSTERIOR  SURFACE  OF  CRICOID 
CARTILAGE 


Longitudinal  fibres  of  cesophagus 


Arytenoideus  muscle 


Crico-arytenoideus  posticus  muscle 


Crico-arytenoideus  posticus  muscle 


.  ARTICULAR  SURFACE  FOR  INFERIOR  CORNU 
OF  THYROID  CARTILAGE 


The  internal  is  almost  flat,  smooth,  and  narrow,  and  covered  by  mucous 
membrane. 

The  base  is  obliquely  hollowed,  and  presents  internally  the  facet  for  articulation 
witli  the  cricoid  cartilage. 

The  angles. — Tht-  anterior  is  ]>rolonged  for  tlie  attachment  of  the  true  vocal 
cord.  It  is  known  as  tlic  vocal  process,  and  with  the  aid  of  the  laryngoscope  is 
easily  seen  during  life. 

The  external  or  muscular  is  thick  and  l)lunt.  and  gives  attachment  in  front  to 
the  lateral  crico-arytenoid,  and  l)ehind  to  the  i)osterior  crico-arytenoid  mu.scle. 


TH?:  LARYNX  905 

The  internal  is  unimportant;  it  is  tied  to  the  corresponding  cartilage  and  to  the 
cricoid  by  a  til>ri)us  l)and  which  is  known  as  the  transverse  or  crico-arytenoid 
ligament. 

The  borders. — The  two  internal,  which  limit  the  narrow  inner  face,  are  nearly 
jKirallt-l  and  aliuust  vertical;  wliilst  the  external  slojx's  upwards,  inwards,  and 
l)ackward<. 

The  apex  ])rojects  inwards  and  backwards,  and  supports  the  corniculum.  Tlie 
cartilage  here  becomes  tibrous  in  structure. 

The  EPIGLOTTIS  is  a  median  leaf-like  plate  of  yellow  elastic  cartilage  attached 
by  a  stalk  infcriorly  to  the  retiring  angle  of  the  thyroid  cartilage  below  the  median 
notch.  \\'hen  denuded  of  its  mucous  covering,  it  is  seen  to  be  pitted  with  numerous 
depressions  for  the  lodgment  of  glands  (fig.  580). 

Placed  with  its  lingual  surface  al)ove,  and  its  stalk  in  front,  it  has  been 
compared  to  an  elongated  saddle.  It  varies  very  considerably  Vjoth  in  shape  and 
inclination,  its  leaf-like  portion  being  sometimes  considerably  curled  upon  itself. 
It  is  placed  nearly  vertically  in  the  adult,  but  in  children  is  frequently  so  much 
depressed  that  its  po.sterior  free  surface  is  inclined  below  its  anterior.  Hence  its 
varialde  appearance  when  examined  in  the  living  subject  with  the  laryngoscope. 
It  is  somewhat  depressed  and  folded  upon  itself  during  deglutition. 

Its  anterior  or  lingual  aspect  is  free  aljove  and  covered  with  mucous  membrane, 
which  lower  down  is  reflected  forward  upon  the  base  of  the  tongue  in  three  folds — 
one  median  (which  encloses  elastic  tissue)  and  tAvo  lateral — the  glosso-epiglotti- 
dean  folds.  Beneath  the  mucous  membrane  the  deeper  attached  poi^^on  of  this 
surfaci'  is  tied  to  the  hyoid  bone  by  a  median  elastic  membrane,  named  hyo-epi- 
glottidean  ligament,  and  by  small  bands  of  muscular  fibres. 

A  ([uantity  of  elastic  and  fatty  tissue,  closely  blended  with  the  hyo-epiglotti- 
dean  ligament  al)ove,  connects  the  epiglottis  to  the  thyro-hyoid  membrane  in  front. 
This  is  known  as  the  periglottis  (fig.  528).  Still  lower,  the  fibro-elastic  tissue 
which  forms  the  thyro-epiglottidean  ligament  attaches  the  stalk  to  the  thyroid  car- 
tilage. 

The  posterior  or  laryngeal  surface,  concavo-convex  from  above  downwards,  and 
concave  from  side  to  side,  is  free  and  covered  with  mucous  membrane  for  its  whole 
exti-nt.  Al)out  its  centre  it  projects  backwards  to  form  the  cushion  of  the 
epiglottis. 

Tlie  lateral  margins,  which  are  free  above,  give  attachment  below  to  the  aryteno- 
epiglottidean  folds  of  mvicous  membrane  which  form  the  boundaries  of  the  supe- 
rior aperture  of  the  larynx,  and  also  on  each  side  to  a  fold  of  the  membrane,  con- 
taining fibrous  tissue,  which  runs  upwards  to  the  posterior  pillar  of  the  fauces — 
the  pharyngo-epiglottidean  fold. 

The  CORNICULA  LARYNGIS,  or  cartilages  of  Santorini,  are  the  two  little 
cone-shaped  yellow  elastic  cartilages  which  jiroject  backwards  and  inwards  from  tlie 
summits  of  the  aryten(jids,  with  which  they  are  sometimes  directly  continuous. 
A  joint,  however,  is  usually  present. 

The  CUNEIFORM  CARTILAGES,  or  cartilages  of  Wrisberg,  are  placed  within 
the  aryteno-epiglottidean  folds.  Tiiese  small  conical  and  elongated  yellow  elastic 
cartilages  produce  the  thickenings  of  the  folds  in  front  of  the  cornicula. 

Calcification. — The  hyaline  cartilages  of  the  larynx  are  especially  ]irone  to 
calcify  after  middle  life,  but  the  yellow  elastic  cartilages  take  no  share  in  the  pro- 
cess. The  little  cartilago  triticea,  however,  which  lies  in  the  thyro-hyoid  liga- 
ment, is  fre(|uently  converted  into  bone. 

In  the  thyroid  cartilage  the  deposit  f)f  l)ony  salts  usually  commences  near  the 
posterior  V)order  and  in  the  cornua.  extending  forwards  into  the  lower  i>art  of  the 
ala,  and  finally  upwards,  until  in  advanced  cases  the  whole  cartilage  is  involved. 

In  the  cricoid  cartilage  the  calcification  commences  above  on  each  side  in  the 
neighbourhood  of  the  crico-arytenoid  joints,  and  extends  downwards,  and  finally 
both  forwards  and  backwards. 

In  the  arytenoid  the  calcification  commences  in  the  ba.se,  but  it  finally  involves 
the  whole  cartilage  with  the  exception  of  the  sunnint,  where  the  hyaline  structure 
(as  already  noted)  disa)i)x>ars. 

The   ligaments    (extrinsic). — The    thyro-hyoid    membrane    is   composed 


906 


THE   ORGANS   OF   VOICE 


mainly  of  elastic  fibres.  It  is  attached  l)elo\v  to  the  upper  margin  of  the  thyroid 
cartilage,  and  above  to  the  upper  and  hinder  margin  of  the  hyoid  bone.  It  presents 
a  thick  central  portion  (stretching  between  the  median  notch  and  the  body  of  the 
hyoid  bone),  and  thinner  lateral  jiortions,  looser  in  texture,  which  are  pierced  by 
the  superior  laryngeal  nerves  and  arteries.  Posteriorly,  the  membrane  is  loosely- 
connected  with  the  sui)erior  cornua  of  the  tliyroid  cartilage,  and  above  these  it  is 
bouniled  on  each  side  by  thickened  bands,  the  thyro-hyoid  ligaments,  wliich  pass 
between  their  tips  and  the  greater  cornua  of  the  hyoid  bone. 

A  little  grain-like  cartilage  (cartilago  triticea)  is  usually  imbedded  in  this  band 
just  above  the  superior  thyroid  cornu. 

The  central  portion  of  the  membrane  is  mainly  subcutaneous,  a  bursa  interven- 
ing where  it  is  overhung  by  the  body  of  the  hyoid  bone. 

Its  lateral  portions  are  covered  by  the  thyro-hyoid  muscles.  Posteriorly  it  is 
separated  from  the  epiglottis  by  the  mucous  membrane  at  the  base  of  the  tongue 
and  the  areolar  fatty  tissue  already  described.  It  is  pierced  by  the  internal  laryn- 
geal vessels  and  nerves. 

The  crico-thyroid  membrane  (intrinsic)  is  composed  chiefly  of  elastic  tissue. 
It  presents  a  prominent  rounded  median  portion  overlapped  slightly  b}'  the  crico- 
thyroid muscles,  but  between  these  muscles  it  is  subcutaneous.  It  is  crossed  by  a 
small  anastomotic  arch  formed  by  the  crico-thyroid  twigs  of  the  superior  laryngeal 
artery;  one  or  two  small  holes,  which  pass  through  it,  transmit  vessels  from  the 
arch  to  the  interior  of  the  larynx. 

0 
Fig.  527. — Superior  View  of  the  Cartilages  of  the  Larynx. 


ANTERIOR  SURFACE  OF 
CRICOID  CARTILAGE 

True  vocal  cord 
Crico-thyroid 
membrane 

CRICOID  CARTILAGE 

VOCAL  PROCESS 


ANTERIOR  SURFACE  OF 

ARYTENOID  CARTILAGE 

INFERIOR  CORNU  OF 

THYROID  CARTILAGE 

SUPERIOR  CORNU  OF 
THYROID  CARTILAGE 

POSTERIOR  SURFACE  OF 
ARYTENOID  CARTILAGE 


Anterior  portion  of 
crico-thyroid  membrane 

Cut  edge  of 
crico-thyroid  membrane 

SUPERIOR  BORDER  OF 
THYROID  CARTILAGE 


CRICO-THYROID 

ARTICULATION 
SUPERIOR  BORDER  OF 

CRICOID  CARTILAGE 


CORNICULUM  LARYNGIS 


POSTERIOR  SURFACE  OF 
CRICOID  CARTILAGE 


This  median  portion  of  the  membrane  stretches  between  the  borders  of  the  two 
cartilages.  The  lateral  and  thinner  portions  pass  upwards  from  the  inner  border 
of  the  upper  margin  of  the  cricoid  cartilage  in  contact  with  the  laryngeal  mucous 
membrane,  and  within  the  embrace  of  the  thyroid  cartilage,  to  form  the  true  vocal 
cords  or  inferior  thyro-arytenoid  ligaments.  These  elastic  liands  extend  from 
the  vocal  processes  of  the  arytenoid  cartilages  to  the  retiring  angle  of  the  thyroid 
near  its  centre. 

The  lateral  portions  of  tliis  membrane  are  covered  superficially  by  the  thyro- 
arytenoid and  lateral  crico-arytetioid  muscles. 

The  superior  thyro-arytenoid  ligaments  are  contained  within  the  arched  folds 
of  mucous  membrane  which  form  the  false  vocal  cords.  They  consist  of  a  few 
bundles  of  fibrous  tissue. 

The  crico-arytenoid  nr  transverse  ligament  has  been  already  sufficiently 
noticed. 

The  Joints  of  the  Larynx.— Tlie  crico-thyroid  joints  are  lined  l)y  a  synovial 
membrane,  embraced  l)ya  thin  capsule  of  radiating  filires,  and  often  strengthened 
posteriorly  ])y  a  well-marked  fibrous  band.  They  ])ennit  of  movement  l)etween  the 
two  cartilages  U])on  an  ax'is  i)assing  transversely  through  both  joints,  and  a  limited 
gliding  of  the  cricoid  upwards  and  l)ackwards.  As  can  be  sliown  on  the  living 
body,  the  (Ticoid  is  the  cartilage  which  swings  between  the  inferior  thyroid  cornua. 


I 
J 


THE  LARYNX 


907 


The  crico-arytenoid  joints  possess  a  synovial  membrane  enveloped  in  a  thin 
and  moderately  loose  capsule,  strenfi;thened  posteriorly  by  a  band  ])assino:  Ix'twccn 
the  cricoid  and  the  inner  and  back  jjart  of  the  arytenoid — the  posterior  crico- 
arytenoid ligament;  and  internally  by  tlic  intcrarytenoid  band,  which  is  occa- 
sionally lijianicntoiis — the  crico-arytenoid  ligament. 

The  cricoid  articular  surface  is  oval,  convex,  and  oblique,  Avith  its  long  axis 
passing  from  behind,  forwards,  and  outwards.  The  opposed  articular  surface  on 
the  base  of  the  arytenoid  is  also  oval,  but  it  is  concave  with  its  long  axis  passing 
from  before  backwards. 

It  follows  that  the  two  surfaces  never  completely  cover  each  other  at  any  one 
time.  The  arytenoid  rotates  on  a  vertical  axis  near  to  and  parallel  with  its  inner 
surface,  and  it  also  glides  forwards  and  inAvards,  or  in  an  opjoosite  direction. 
Tbese  movements  are  associated — the  gliding  forwards  and  inwards  with  the  inward 
rotation,  and  the  gliding  outwards  and  l)ackwards  with  the  outward  rotation. 


Fig.  528.— Side  View  of  the  Muscles  and  Ligaments  of  the  Larynx. 

Epiglottis  — 


Cut  edge  of  hyo-epiglottidean 
ligament 

SECTION  THROUGH  BODY  OF  HYOID 
BONE 

Periglottis 


Cut  edge  of  thyro-hyoid 
membrane 


ihyro-epiglottideus  muscle 


SECTION  OF  THYROID  CARTILAGE 
Thyro-arytenoideus  muscle 


Crico  -  arytenoideus  lateralis 
muscle  I  the  pointer  crosses 
crico-thyroid  membrane) 

CRICOID  CARTILAGE 


Aryteno-epiglottidean  fold 
Aryteno-epiglottideus  muscle 


Arytenoideus  muscle 


Crico-arytenoideus  posticus 


Heeurrent  laryngeal  nerve 


IWIII'"  w  W*""'    1'' 


The  Muscles. — The  muscles  are  divisible  into  an  extrinsic  group,  passing 
between  the  larynx  and  parts  beyond;  and  an  intrinsic  group,  belonging  entirely  to 
the  organ  itself. 

The  extrinsic  muscles  are  the  sterno-thyroid,  thyro-hyoid,  stylo-  and  palato- 
pharyngei,  and  the  inferior  constrictors  of  the  pharynx.  It  should  be  noted  that 
tb.e  muscles  whicli  fix  the  hyoid  bone,  and  also  those  which  close  the  loAver  jaw, 
assist  the  action  of  the  above  mentioned. 

The  intrinsic  muscles. — The  crico-thyroid  is  attached  lielow  to  the  front  and 
side  of  tbc  cricoid  cartilage,  and  nl)ove  to  the  lower  border  of  the  thyroid  cartilage. 
The  loAver  fibres,  which  are  horizontal  and  often  distinct,  pass  to  tbe  front  ))order 
of  its  inferior  cornu,  and  act  by  i)ulling  the  cricoid  directly  backwanls,  whilst  the 
s])reading  fi])res  whicli  form  the  rest  of  the  muscle  swing  tlie  cricoid  l)etween  the 
crico-thyroid  joints,  pulling  it  upwards  as  well  as  backwards.  Both  portions  of  the 
muscle  make  tense  the  vocal  cords,  and  are  su]>pned  by  the  external  laryngeal 
nerve.      It  is  overlapped  laterally  by  the  sterno-thyroid,  having  beneath  it  a  small 


908 


THE  ORGANS   OF    VOICE 


portion  of  the  crico-thyroid  meniljrano  and  some  of  the  lower  fibres  of  the 
lateral  crico-arytenoid  muscle.  The  central  portion  of  the  crico-thyroid  membrane 
api)ears  in  the  an<iular  interval  between  the  two  muscles. 

The  crico-arytenoideus  posticus  arises  from  the  quadrate  surface  situated  on 
each  side  of  the  j)osteri{M-  metUan  ridge  of  the  cricoid  cartilage.  Its  fibres  rajjidly 
converge  to  be  inserted  into  tlie  posterior  portion  of  the  outer  angle  (muscular 
process)  of  the  arytenoid  cartilage. 

Fig.  529.— Scheme  of  Kima,  showing  Action  of  Crico-aeytenoideus  Posticis,  which 
DRAWS  THE  ARYTENOID  CARTILAGE  FROM  I  TO  II.     (Modified  from  Stirling.) 


The  upper  fibres  are  chiefly  concerned  in  rotation  of  the  arytenoid  cartilage, 
whilst  the  lower  produce  its  gliding  movement.     It  is  a  dilator  of  the  rima  glottidis. 

Some  of  the  lowest  fibres  occasionally  pass  to  the  inferior  cornu  of  the  thyroid 
cartilage,  and  are  known  as  the  kerato-cricoideus  or  kerato-thyroideus. 

It  is  covered  posteriorly  by  mucous  membrane,  and  is  supplied  by  the  recurrent 
laryngeal  nerve.  A  few  of  the  longitudinal  fibres  of  the  oesophagus  arise  from 
the  ridge  which  separates  the  two  muscles. 


Fig.  530. — Posterior  View  of  Thyroid  Cartilage  with  Epiglottis. 


GREATER  CORNU  OF  HYOID 
BONE 
BODY  OF  HYOID  BONE 


Thyro-hyoid  ligament 


Median  notch 

Origin  of  thyro-epiglottio 
ligament 

POSTERIOR  EDGE   OF  THYROID 

CARTILAGE 

Origin  of  thyro-aryte- 

noideus  muscle 


INFERIOR  CORNU 


SMALLER  CORNU  OF  HYOID 
BONE 


CARTILAGO  TRITICEA 


SUPERIOR  CORNU  OF  THYROID 
CARTILAGE 


RIGHT  ALA  OF  THYROID 
CARTILAGE 


False  vocal  cord 
True  vocal  cord 


Origin  of  thyro-epiglot- 
tideus  muscle 


The  crico-arytenoideus  lateralis  arises  from  the  uj>per  border  of  the  cricoid 
cartilage  between  tlie  origin  of  tlie  crico-thyroid  and  the  crico-arytenoid  articulation. 
It  narrows  to  be  inserted  into  the  fore  part  of  the  muscular  process  of  the  aryte- 
noid cartilage.  It  draws  the  cartilage  forwards,  relaxing  and  ap])roximating  the 
cords. 

It  is  overlapped  l\y  the  thyroid  cartilage,  and  anteriorly  by  the  crico-thyroid 


THE   LARYNX  909 

muscle;  internally  it  is  covered  by  mucous  membrane.  The  upper  portion  is  con- 
tiguous to  the  thyro-arytenoid,  with  which  it  is  occasionally  blended.  It  is  su}i})li('il 
by  the  recurrent  hirvn^cal  nerve 

The  thyro-arytenoid  muscle,  which  is  i)laced  above  the  foregoing,  arises 
broadly  from  th(;  lower  two-thirds  of  the  inner  surface  of  the  thyroid  cartilage 
close  to  its  retiring  angle,  and  sHghtly  from  the  external  surface  of  the  crico-thy- 
roid  meml)rane.  Narrowing  as  it  passes  outwards  and  backwards,  it  is  inserted 
into  the  anterior  surface  of  the  arytenoid  cartilage,  and  also  into  its  base  close  to 

Fig.  531. — Scheme  Showing  Action  of  Thyro-arytenoid  drawing  the  Vocal  Cords 
AND  Vocal  Processes  from  II  to  I.      (Modified  froiu  Stirling.) 


the  attachment  of  the  lateral  crico- arytenoid  muscle.  Some  few  of  its  fibres  pass 
onwards  and  become  continuous  with  the  oblique  fibres  of  the  arytenoid  muscle. 

The  lower  portion  of  the  muscle  lies  parallel  to  and  blends  Avith  the  outer 
surface  of  the  vocal  cord.  The  upper  and  thinner  portion  is  placed  immediately 
beneath  the  mucous  membrane,  and  overlies  the  ventricle  and  laiyngeal  pouch. 

These  muscles  by  rotating  the  arytenoid  cartilages  draAV  the  vocal  processes 
downwards  and  inwards,  and  thus  approximate  the  vocal  cords.  By  pulling 
forward  the  cartilages,  they  relax  the  cord  as  a  Avhole.  According  to  some 
authorities,  the  fil)res  attached  to  the  outer  border  of  the  vocal  cord  act  upon  it  l)y 

Fig.  532.— Scheme  showing  Action  of  Arytenoidet's  drawing  Arytenoid  Cartilage 
FROM  Neutral  Position  I  to  II.     (Modified  from  Stirling.) 


modifying  its  elasticity,  tightening  a  portion  in  front  and  relaxing  the  remainder, 
in  this  somewhat  resembling  the  stop-action  of  thi'  finger  on  a  violin  string. 

The  fibres  lying  near  the  true  vocal  cords,  in  the  angle  l)etween  the  midtlle  and 
lower  sections  of  the  laryngeal  cavity,  are  frequently  described  as  a  separate  portion 
called  the  thyro-arytenoideus  internus;  they  form  a  triangular  prismatic  bundle, 
attached  anteriorly  to  the  thyroid  cartilage  and  the  anterior  part  of  the  true  vocal 
cord,  and  posteruirly  to  the  arytenoid  cartilage  in  the  neighbourhood  of  the  vocal 
process.     The  remainder   of   the   muscle,    the  thyro-arytenoideus  externus,    is  a 


910  THE   ORdAXS   OF    VOICE 

broad,   flat  band  which  intL-rvfiU's  Ijctwe'cn  the  vuntrifle  of  the   larynx  and  the 
inner  surface  of  the  thyroid  cartihitre. 

The  arytenoideus  consists  of  transverse  fibres  passing  from  one  arytenoid 
cartilage  to  the  other,  and  attached  to  their  posterior  concave  surfaces.  Super- 
ficially are  some  oblicpie  fibres,  which  decussate  where  they  meet.  These  i)ass 
from  the  outer  angle  of  one  cartilage  l)elow  to  the  summit  of  the  opposite.  A  few 
of  these  fibres  pass  onwards  to  the  aryteno-epiglottidean  fold  and  side  of  epiglottis. 
These,  reinforced  liy  fil)res  attached  Xo  the  sunnnit  of  the  arytenoid  cartilage, 
constitute  the  aryteno-epiglottideus  muscle.  A  few  fibres  l)lend  with  the  thyro- 
arytenoid nuiscle. 

'  The  arytenoideus  approximates  and  depresses  the  arytenoid  cartilages.  These 
actions  are  assisted  by  the  aryteno-epiglottidei,  which  depress  the  epiglottis  and 
contract  the  superior  aperture  of  the  larynx. 

The  thyro-epiglottideus  (sometimes  described  as  part  of  the  thyro-arytenoid) 
consists  of  fibres  attaclu'(l  below  to  the  thyroid  cartilage  which,  spreading  al)ove. 
reach  the  aryteno-epiglottidean  fold,  and  the  outer  Avail  of  the  laryngeal  pouch  as 
well  as  the  ei)iglottis.    (For  the  nerve-supply  of  the  laryngeal  muscles  see  ]^age  912. ) 

The  Interior  of  the  Larynx. — The  superior  aperture,  or  opening  of  the 
glottis,  is  triangular  in  shape,  wide  in  front,  narrow  l)ehind,  and  placed  so 
obliquely  as  to  be  almost  vertical  in  the  living  subject.  Above  and  in  front  it  is 
bounded  by  the  epiglottis,  behind  and  below  by  the  interarytenoid  notch,  whilst 
on  each  side  stretches  the  aryteno-epiglottidean  fold  containing  muscular  and  liga- 
mentous fil^res.  This  fold  presents  two  thickened  areas,  one  at  the  summit  of  the 
arvtenoid  cartilage,  and  one  just  in  front  and  above  this,  formed  by  the  bulging  of 
the  cornicular  and  cuneiform  cartilages  respectively. 

Bounded  internally  by  this  fold,  and  externally  l)v  the  wing  of  the  thyroid 
cartilage,  is  a  shallow  depression — the  sinus  pyriformis. 

The  cavity  of  the  larynx  extends  from  the  ajierture  above  described  to  the  lower 
border  of  the  cricoid  cartilage. 

Its  lining  of  mucous  membrane  varies  much  in  its  colour  and  thickness  and 
its  fixity  to  the  structures  which  it  overlies.  On  the  surface  of  the  true  vocal  cords 
it  is  extremely  thin,  pale  and  adherent,  whilst  above  and  below  this  it  is  more 
vascular  and  more  loosely  attached  to  the  underlying  parts.  The  submucous  tissue 
contains  numerous  elastic  fibres  and  mucous  glands. 

The  cavity  is  naturally  divided  into  two  portions — supra-  and  infra-rimal — 
divided  l)y  the  glottis  or  interval  between  the  two  true  vocal  cords. 

The  suprarimal  portion  corresponds  to  the  space  between  the  wings  of  the 
thyroid  cartilage.  It  is  broad  and  triangular  above,  but  narrower  below,  and  its 
walls  are  much  deeper  in  front  than  l^ehind.  Immediateh'  above  each  vocal  cord 
is  an  oblong  depression — the  ventricle — bounded  above  by  the  crescent-shaped 
edge  of  the  false  vocal  cord,  below  b}'  the  straight  margin  of  the  true  vocal  cord, 
and  externally  by  the  thyro-arytenoid  muscle.  The  ventricle  extends  nearly  the 
whole  length  of  the  vocal  cords,  and  is  lined  by  a  thin  and  tightly  adherent  mucous 
membrane.  It  allows  the  free  vibration  of  the  true  vocal  cords  in  the  production 
of  sound.  From  the  anterior  part  of  the  ventricle  there  extends  upwards,  for  about 
half  an  inch,  a  small  blind  sac,  named  the  laryngeal  pouch.  This  reaches  as  high 
as  the  up])er  l)order  of  the  thyroid  cartilage;  its  mouth  below  is  narrow  and  guarded 
by  two  little  folds  of  mucous  membrane.  A  delicate  fibrous  investment  is  continued 
from  the  true  vocal  cord  around  the  sac.  Some  fatty  tissue  is  enclosed  within  this, 
and  its  mucous  lining  contains  numerous  glands.  On  its  outer  side  are  some 
fibres  of  the  thyro-arytenoid  muscle;  whilst  on  its  inner  side  is  a  thiij  layer  of 
muscular  fibres,  derived  from  the  aryteno-e])iglotti(leus.  and  sometimes  known  as 
Hilton's  muscle,  or  the  compressor  sacculi  laryngis. 

The  superior  or  false  vocal  cords  stand  farther  ai)art  than  the  true,  andcannoi 
be  made  absohitely  tense.  Tliey  liave  already  been  sufficiently  described.  A 
shallow  fossa — the  fossa  innominata — is  ol)servable,  especially  during  ])honation, 
between  the  false  cord  midtlie  aryteno-e]>igl()ttidean  fold;  it  is  ]ilaced  a  little  behind 
the  epiglottic. 

The  inferior  or  true  vocal  cords  are  the  structures  concerned  in  the  production  of 
the  voice.     They  stretch  from  the  vocal  processes  of  the  arytenoid  cartUages  to  the 


THE  LARYXX 


911 


tliyroid  cartilage,  their  tension  and  ])<)siti()n  varying  under  muscular  action.  The 
cords  are  pearly  white  in  a})pcarance,  and  i)rcsent  flattened  surfaces  where  they  face 
•  ■ach  other  internally,  Avith  a  free  sharp  edge  above.  Itis  this  edge  which  is  thrown 
into  vil)rations  during  plionation. 

They  are,  according  to  Testut,  al)()Ut  four-fifths  to  one  inch  long  (20  to  24  mm.  ), 
in  tlie  male,  and  three-  to  four-fifths  of  an  inch  (15  to  20  mm.)  in  length,  in  tlie 
female. 

Fig.  533. — View  of  Interior  of  Larynx  as  seen  during  Inspiration. 


Vallecula — 

Cushion  of  epiglottis 

True  vocal  cord 

Rima  glottidis 

Sinus  pyrilormis 

Arytenoid  commrssure 


BASE  OF  TONGUE 


Median  glosso-epiglottidean  fold 

EPIGLOTTIS 

Fossa  innominata 
Aryteno-epiglottidean  fold 

CARTILAGE  OF  WRISBERG 

CARTILAGE  OF  SANTORINI 

Pharynx 


The  rima  glottidis  is  the  chink  bounded  on  each  side  by  the  vocal  cords  and 
tlie  inner  surfaces  of  the  arytenoid  cartilages  with  their  vocal  processes;  the  inter- 
cordal  jiortion  is  known  as  the  glottis  vocalis,  and  the  interarvtenoid  part  as  the 
glottis  respiratoria;  the  length  of  the  former  is  the  same  as  that  of  the  vocal  cords, 
and  that  of  the  latter  is  about  a  quarter  of  an  inch  (6  to  7  mm.)  in  the  male  and 
5  to  6  mm.  in  the  female.      (Testut. ) 

Fig.  5.34. — View  of  Interior  of  Larvnx  as  seen  during  Vocalisation. 


BASE  OF  TONGUE  • 


Median  glosso-epiglottidean  fold  ^ 


fc— sJT 

/ 

%.  V': 

/ 

Sinua  pyriformis  — \l   J 
PROCESSUS  VOCALIS 

"'\  "v. 

f 

Pharynx . — 

X 


h 


EPIGLOTTIS 

Cushion  of  epiglottis 

Ventricle 
Aryteno-epiglottidean  fold 

-      —  CARTILAGE  OF  WRISBERG 

CARTILAGE  OF  SANTORINI 

Arytenoid  commissure 


It  is  limited  behind  l)y  the  interarvtenoid  fold,  and  presents  the  aiii)earance  of 
an  elongated  triangle. 

When  observed  during  life,  the  rima  glottidis  is  seen  to  vary  very  considerably. 
On  inspiration  the  vocal  cords,  whilst  almost  touching  in  front,  are  separated 
behind  from  a  quarter  to  half  an  inch  (6  to  12  mm.),  forming  an  angle  directed 
outwards,  where  they  terminate  in  the  vocal  processes,  the  glottis  presenting  a 
lozenge-shaped  appearance. 


912 


THE  ORGANS   OF   VOICE 


On  plionation  the  cords  bt'conic  parallel  and  closely  approximated,  and  the 
vocal  processes  ap})roaching  each  other  cause  the  angle  to  be  turned  inwards. 

The  infrarimal  portion  of  the  larynx  rapidly  widens  out  into  a  nearly  circular 
cavitv  at  the  lower  border  of  the  cricoid  cartilage,  from  which  point  it  is  continuous 
witli  the  lunuui  of  the  trachea. 

Nerves. — The  nerves  of  the  larynx  are  derived  from  the  superior  and  inferior 
(recurrent )  laryngeal  l)ranc]ies  of  tlie  vagus. 

The  superior  laryngeal. — The  sensory  nerve  of  the  larynx  gives  ofT  near  its 
origin  behind  tlie  carotid  sheath  a  long  and  slender  filament,  Avhich  is  principally 
motor.  This  (external)  branch  is  distributed  to  the  crico-thyroid  muscle,  a  few 
minute  filaments  reaching  the  mucous  membrane  of  the  larynx. 

Its  larger  and  main  branch    (internal)    is   sensory,   and  passes  through  the 


Fig.  535. — Nerves  of  the  Laryxx.     (Posterior  view.) 


GREATER  CORNU  OF 

HYOID  BONE 
CARTILAGO  TRITICEA 


SUPERIOR      CORNU      OF 
THYROID  CARTILAGE 


BRANCH  TO  LA  TEBAL 
VRICO  -  ARYTENOID 
AND  THTRO-ARTTE- 
SOID  .VVSCLES 
H RANCH  JOINING   THE 
srPERIOR        LARYN- 
GEAL NERVE 
Crieo-arytenoideus 
posticus  muscle 
INFERIOR    CORNU    OF 
THYROID  CARTILAGE 


FORAMEN  C/ECUM 


BASE  OF  TONGUE 


EXTERXAL  LARYN- 
GEAL NERVE 

INTERNAL  LARYN- 
GEAL NERVE 

,   Cut  edge  of  thyro- 
hyoid membrane 


Arytenoideus  muscle 


RECURRENT 
LARYNGEAL 
NER  VE 


aperture  in  the  thyro-hyoid  membrane  above  the  superior  laryngeal  artery.  It 
divides  l)eneath  the  mucous  membi'ane  which  lines  the  sinus  pyriformis,  distributing 
branches  upwards  to  supply  both  surfaces  of  the  epiglottis  and  the  base  of  the 
tongue  immediately  in  front;  inwards  to  the  aryteno-epiglottidean  fold  and  its 
neighbourhood;  whilst  others  pass  downwards  to  the  mucous  membrane  of  the 
deeper  portions  of  the  larynx  as  far  as  the  true  vocal  cords. 

The  inferior  (recurrent)  laryngeal,  the  motor  nerve  of  the  larynx,  ascends  in 
the  groove  between  tbe  traeliea  and  (esophagus,  l)oth  of  which  structures  it  supplies. 
It  reaches  the  larynx  below  the  edge  of  the  inferior  constrictor,  and  immediately 
behind  the  crico-thyroid_  joint.  At  this  spot  it  divides  into  two  l»ranches:  an 
anterior  to  su])]»ly  the  thyro-arytenoideus,  crieo-arytenoideus  lateralis,  Avith  the 
niuseles  of  the  epiglottis;  and  a  posterior  branch  to  the  crieo-arytenoideus  posti- 
cus and  arytenoideus. 


THE   TRACHEA  913 

The  superior  laryngeal  communicates  with  this  })ranch  by  a  slender  filament, 
which  passes  downwards  near  to  the  posterior  border  of  the  thyroid  cartilage. 
This  communication  sometimes  takes  place  beneatli  the  posterior  crico-arytencnd 
muscle. 

The  arteries  are  derived  from  the  superior  and  inferior  thyroid,  the  e})iglottis 
receiving  some  twigs  from  tlie  dorsalis  lingute  of  tlic  lingual. 

Tlie  veins  correspond  with  the  arteries;  and  the  lymphatics,  which  are  scanty, 
follow  the  vessels  and  end  in  the  deep  cervical  glands. 


THE   TRACHEA 

The  trachea,  or  air-tube,  which  is  cylindrical  in  shape,  but  flattened  posteriorly, 
extends  from  the  lower  border  of  the  fifth  cervical  vertebra  to  the  fourth  or  fifth 
thoracic  vertebra.  It  is  continuous  with  the  larynx  above,  and  divides  into  the  two 
bronchi  below.  It  measures  from  four  and  a  half  to  five  inches  (10  to  12  cm.)  in 
length,  and  is  nearly  an  inch  ('I'o  cm.)  in  width. 

Relations. — In  its  cervical  portion  it  rests  upon  the  oesophagus,  wliicli  curves 
somewhat  to  the  left  at  the  root  of  the  neck;  on  each  side,  but  especially  on  the 
left,  it  comes  into  relationshij)  with  the  lateral  lobes  of  the  thyroid  gland,  the 
inferior  tliyroid  arteries,  and  the  recurrent  laryngeal  nerves  (these  latter  running 
upwards  gain  the  lateral  groove  between  the  trachea  and  oesophagus) ;  and  lastly, 
it  is  in  relation  with  the  sheath  containing  the  comuKju  carotid  artery,  internal 
jugular  vein,  and  pneumogastric  nerve. 

In  front  it  is  crossed,  opposite  the  second,  third,  and  fourth  rings,  by  the 
isthmus  of  the  thyroid  body;  above  the  isthmus  it  is  concealed  in  part  by  the 
pyramidal  lobe  of  the  thyroid  and  by  the  levator  glandule  thyroidea  muscle,  and 
it  is  crossed  liy  the  internal  terminal  branches  of  the  superior  thyroid  arteries. 
Below  the  isthmus  the  inferior  thyroid  veins,  the  thyroidea  ima  artery,  if  it  is 
present,  and  the  remains  of  the  thymus  gland  lie  in  close  relation  with  it,  and 
more  .anteriorly,  separated  from  it  by  the  deep  cervical  fascia,  are  the  anterior 
jugular  veins  and  their  anastomosis  above  the  sternum. 

It  is  overlapped  on  each  side  l)y  the  sterno-hyoid,  sterno-thyroid,  and  sterno- 
niastoid  muscles,  and  the  interval  between  the  muscles  of  the  two  sides  is  crossed 
by  a  strong  deep  and  a  thinner  superficial  layer  of  deep  ceiwical  fascia,  whilst  still 
more  superficially  lie  the  superficial  fascia  and  skin. 

In  its  thoracic  portion  the  trachea  still  rests  U)ton  and  retains  its  comiection 
with  the  (esophagus,  wliicli  separates  it  from  the  sjiine.  It  lies  between  the  two 
|)leural  sacs  and  pneumogastric  nerves..  In  front  of  it  is  tlie  sternum  with  the 
origins  of  the  sterno-hyoid  and  sterno-thyroid  muscles,  the  thymus  gland,  the  deep 
cardiac  plexus,  the  aortic  arch  which  crosses  the  tube  just  above  its  bifurca- 
tion, the  connnencements  of  the  innominate  and  left  connnon  carotid  arteries  and 
the  left  innominate  vein  which  crosses  the  roots  of  the  latter  vessels.  On  its  right 
sifle  are  the  pleural  sac,  the  vagus  nerve,  and  the  innominate  artery,  and  on  its  left 
side  the  left  connnon  carotid  and  subclavian  arteries,  the  left  vagus  and  left  recur- 
rent nerves,  and  the  left  pleural  sac. 

Structure. — The  trachea  is  made  up  of  a  series  of  imperfect  cartilaginous  riniis. 
deficient  behind,  connected  throughout  by  fibro-elastic  mend)rane,  and  behind  with 
muscular  fibres  (the  trachealis  muscle),  a  special  layer  of  yellow  elastic  fibres,  and 
a  lining  of  mucous  memitranc. 

The  cartilaginous  rings  vary  in  number  from  sixteen  to  twenty.  They  are 
incomplete,  being  deficient  in  the  hinder  third,  and  are  connected  in  a  continuous 
series  by  a  fibrous  membrane,  which  divides  to  enclose  them,  but  reunites  in  the 
narrow  intervals  l)etween.  It  forms  a  definite  layer  where  the  cartilages  are  want- 
ing, so  that  it  mav  be  regarded  as  complete  throughout  the  tube.  The  inside  of 
58  *  " 


914 


THE   ORGANS   OF   VOICE 


the  trachea  is  ridgod  transversely  l)y  the  rings,  which  are  rounded  on  their  inner 
surfaces;  hut  it  is  con:iparatively  smooth  externally,  where  the  outer  surfaces  of  the 
rings  are  llattened. 

The  first  cartilage  is  l)road,  and  is  occasionally  united  with  the  cricoid  ahove, 
or  second  ring  of  the  trachea  helow. 

The  last  cartilage  is  likewise  broad  and  strong,  and  sends  a  curved  beak 
downwards  and  backwards  at  the  point  of  bifurcation  of  the  tracliea.  It  forms 
an  imperfect  ring  on  each  side  above  the  commencement  of  the  corresponding 
bronchus. 

Two  cartilages  not  uncommonly  unite  in  part,  and  thus  present  a  bifurcated 
appearance. 

The  fibres  of  the  trachealis  are  unstripod,  and  form  a  transverse  layer  at  the 


Fig.  536.— Anterior  View  of  the  Larynx,  with  the  Trachea  and  Bronchi. 

(Modified  from  Bourgery.) 


FIRST  RING  OF  TRACHEA 


A rch  of  aorta 


Jiiflht  pulmonary  artern 


POSITION   OF  THYROID  ISTHMUS 


LEVEL  OF  STERNUM 


LAST  RING  OF  TRACHEA 


L'ft  jiuliiioiiary  artery 
LEFT  BRONCHUS 


posterior  flattened  part  of  the  tube,  wdth  an  indistinct  layer  of  longitudinal  fibres 
superimposed. 

The  yellow  elastic  fibres,  which  exist  throughout  the  entire  mucous  mem- 
brane, f(jriii  a  detinite  and  deep  layer  at  the  posterior  flattened  portion  oi  the  tube. 
They  are  gathered  into  strong  longitudinal  flattened  bands,  especially  well  seen  at 
the  lower  part  of  the  trachea,  and  where  the  fibres  separate  to  ))ass  into  the 
bronchi. 

The  mucous  membrane  is  smooth  and  i)inkish  in  colour;  it  is  i)rovided  with 
numerous  glands,  especially  at  its  hinder  ])art,  and  is  lined  by  a  columnar  ciliated 
e})itheliuni. 

The  arteries  are  derived  from  the  inferior  thyroid. 

The  veins  join  the  thyroid  i)lexuses;  and  the  nerves  are  supplied  by  In-anches 
from  the  i)neum()gastric,  the  recurrent  laryngeal,  and  sympathetic. 


I 


BRONCHI— THYROID   GLAND  915 


THE  BRONCHI 


Tlie  right  bronchus  (fig.  536),  from  its  commencement  to  the  origin  of  its  first 
branch,  i^  about  one  incli  in  length  (25  nun.).  It  is  shorter  and  wider  than  the 
left,  and  in  (Hrcction  more  horizontal  in  its  passage  to  the  root  of  the  lung. 

Relations. — The  vena  azygos  maj(n"  arches  above  it  from  behind  to  end  in  the 
superior  vena  cava,  which  latter  is  placed  anteriorly.  The  right  iiulnionary  artery 
is  at  first  below,  and  then  in  front  of  it. 

The  left  bronchus  is  about  two  inches  in  length  (50  mm.)  outside  of  the 
lung.      It  is  more  obH(|ue,  longer,  and  narrower  than  the  right. 

Relations. — It  lies  beneath  the  arch  of  the  aorta,  and  rests  upon  the  oesoph- 
agus and  the  descending  aorta.  The  left  pulmonary  artery  lies  in  front  of  it.  On 
looking  down  the  trachea  the  dividing  ridge  between  the  two  bronchial  orifices  is 
seen  to  be  on  the  left  of  the  middle  line,  more  of  the  right  orifice  for  this  reason 
being  visible.  This  explains  the  fact  that  foreign  bodies  entering  the  trachea  most 
commoidy  become  lodged  in  the  right  bronchus. 

Above  the  point  where  it  is  crossed  by  the  pulmonary  artery  the  right  bronchus 
gives  off  an  eparterial  branch  to  the  u})per  lol)e  of  the  rigid  lung.  Below  thejioints 
wdiere  they  are  crossed  by  the  pulmonary  arteries,  in  the  substance  of  the  lungs, 
both  bronchi  give  off  two  series  of  hyparterial  branches,  lateral  and  dorsal,  which 
rise  alternately.  The  dorsal  branches  pass  towards  the  posterior  borders  of  the 
lungs,  and  the  lateral  branches  curve  outAvards  and  forwards  towards  the  anterior 
borders.  The  first  lateral  branch  on  the  right  side  sui)])lies  the  middle  lobe,  and 
the  first  lateral  bi-anch  on  the  left  side  the  upper  lobe,  all  the  remaining  hyi)arterial 
branches  are  distril)uted  to  the  lowxn*  lobe.  In  addition  to  the  two  main  sets  of 
hyparterial  branches  a  number  of  small  accessory  1:)ronchi  arise  from  the  antero- 
lateral aspect  of  each  stem  bronchus;  of  these  one  Avhich  rises  on  the  right  side  a 
short  distance  below  the  level  of  the  first  dorsal  bronchus  is  called  the  cardiac 
bronchus,  ))ecause  in  some  mammals  it  supplies  a  special  lobe  of  the  right  lung 
which  lies  l)elow  and  posterior  to  the  heart.  This  small  bronchus  is  the  fourth 
branch  from  the  right  stem  bronchus. 

As  the  pulmonary  artery  passes  dowaiwards  in  the  lung  it  lies  on  the  postero- 
external aspect  of  the  stem  bronchus  between  the  lateral  and  dorsal  branches,  and 
the  pulmonary  vein  is  situated  on  the  opposite  side  of  the  tul>e. 


THE  THYROID  BODY  OR  OLAXD 

The  thyroid  body  is  of  a  reddish  e(jlour,  and  is  classed  amongst  the  ductless 
glands.  It  consists  of  two  lateral  lobes,  and  a  connecting  isthmus  which  unites 
them  below. 

The  gland  is  convex  and  rounded  on  its  outer  surface,  but  deeply  it  is  moulded 
to  the  parts  which  it  overlies.  It  commonly  weighs  from  one  to  two  ounces,  l)ut  is 
larger  in  the  female,  and  is  often  increased  in  size  during  menstruation. 

The  lateral  lobes  are  pyriform  in  shape,  with  their  broad  ends  below,  and 
measures  about  two  inclies  (50  nnii.  )  in  length,  three-<iuarters  of  an  inch  (18  mm.) 
in  breadth,  and  al)out  an  inch  (25  mm.  )  in  thickness  near  the  middle. 

Relations  of  the  lateral  lobes. — Tiie  ai)ex  lies  between  the  sterno-thyroid 
and  the  inferior  constrictor  of  the  jiharynx,  the  latter  separating  it  from  the  liinder 
part  of  the  ala  of  the  thyroid  cartilage  and  its  inferior  cornu.  The  base  is  rounded; 
it  lies  under  cover  of  the  sterno-thyroid  and  sterno-hyoid  muscles  at  the  level  of  the 
sixth  ring  of  the  trachea  and  about  tliree-cpiarters  of  an  inch  (18  nnn.)  aliove  the 
sternum.  Some  large  radicles  of  the  inferior  thyroid  vein  issue  from  it.  The  exter- 
nal surface  is  convex,  it  is  covered  l)y  the  sterno-hyoid.  sterno-thyroid,  and  omo- 
hyoid muscles,  and  it  is  overlapped  by  the  anterior  part  of  the  sterno-mastoid. 
The  internal  surface  is  concave;  it  is  moulded  on  the  trachea.  Tlu^  j^osterior  bor- 
der is  thick,  it  is  in  contact  witli  the  carotid  sluvith,  and  is  grooved  l>vthe  common 
carotid  artery;  on  the  left  side,  it  lies  in  front  of  the  opsophagus.  and  on  both  sides 
in  front  of  the  recurrent  laryngeal  nerve  and  tlie  inferior  thyroid  artery.  The 
anterior  border  is  thin,  above  it  is  in  relation  with  tlie  internal  terminal  lirancli  of 


916 


THE   ORGANS   OF   VOICE 


tin-  inferior  thyn.id  artery,  and  in  the  lower  part  of  its   extent  it  is   united  to  its 
fellow  of  the  oi)i)osite  side  l>y  the  isthnnis. 

Relations  of  the  Isthmus. — The  isthmus  varies  in  )»readth  from  a  quarter  to 
three-quarters  of  an  inch  (6  to  18  nmi. ).  Its  anterior  surface  is  convex  and  it  lies 
in  relati«Mi  with  the  dee})  fascia,  anterior  jugular  veins,  superficial  fascia  and  skin. 
Its  posterior  concave  surface  rests  upon  the  second,  third,  and  fourth  rings  of  the 
trachea.  Its  extremities  are  connected  with  the  lower  parts  of  the  inner  borders  of 
the  lateral  lobes.  Its  lower  border  gives  exit  to  some  trilnitaries  of  the  inferior 
thyroid  veins  and  its  upper  border  is  in  relation  with  the  anastomosis   between  the 


Fui.  ry'M. — View  of  Thvkuid  Body. 


SMALLER  CORNU  OF  HVOID  BONE 


Thyro-hyoid  ligament 


THYROID  CARTILAGE 


THYROID  ISTHMUS 


BODY  OF  HYOID  BONE 


Thyro-hyoid  membrane 


Thyro-hyoid  muscle 
Inferior  constrictor 


Sterno-thyroid  muscle 


Median  portion  of  crico- 
thyroid membrane 


Crieo-thyroid  muscle 


LATERAL  LOBE  OF  THYROID  BODY 


SECTION  THROUGH   CARTILAGES 


internal  terminal  ])ranches  of  the  superior  thyroid  arteries,  frequently  a  pyramidal 
])rocess  springs  from  it,  and  the  levator  glandulse  thyroidea,  if  present,  is  attached 
to  it. 

The  pyramidal  process  is  variable;  when  present  it  is  attached  l)y  its  base  to 
the  upper  border  of  the  istlimus  or  to  the  adjacent  part  of  the  left  lateral  lobe.  It 
is  the  remains  of  a  duct,  tlie  thyro-glossal  duct,  which  extends  in  the  foetus  from 
the  foramen  cfccum  of  tlie  tongue,  l)eliind  the  hyoid  l)one,  to  the  isthmus  of  the 
thyroid  l)ody,  wliicli  is  developccl  from  its  lower  extremity. 

The  capsule  and  suspensory  ligaments. — A  ti])rous  capsule  of  deep  cervical 
fascia  completely  encloses  the  thyroid  body  and   sends  septa  inwards  between  its 


THYROID    (iLASn 


91  • 


loVjes.     The  superficial  vessels  ramify  l)eneath  it  and  from  its  inner  and  hack  part 

two  liroad  hands,  the  suspensory  ligaments,  pass  upwards  to  the  cricoid  cartilage. 

Structure. — The  thvroid    hody,    enveloped  in  a  dense  but  thin    covering  of 


Fig.  538. — Thyroid  Body,  with  Middle  Lobe  and  Levator  Muscle. 

Stylo-hyoid  lieament   — — \,\  ^SIPT''  -225(1% EPIGLOTTIS 


L  BODY  OF  HYOID  BONE 

Thyro-hyoid  ligament 


Steruo-hyoid  muscle 

Omo-hyoid 

Thyro-hyoid 


Crico-thyi 

Sterno-thyroiil    -rrr'i 

ISTHV 


Thyro-hyoid  membrane 


Levator  glanduls  thyroideae 

THYROiO  CARTILAGE 


PYRAMIDAL  PROCESS  OF  THYROlO  BOOY 


LEFT  LATERAL  LOBE 


Fio.  .530. — The  Suspensory  Ligaments  of  the  Thyroid  Body.     (After  Berry.) 


Crico-arytenoideus  posticus 
UTERAL  BONE  OF  THYROIO  GLANO 


Suspensory  ligament  of  the  left 
side 


l:  E(  ■  t  J!  liES  T  LA  II )  '.V^'  AM  L 


areolar  tissue,  is  made  up  of  a  number  of  closed  follicles.  These  are  surrounded 
bv  an  open  vascular  meshwork  supported  by  the  interstitial  connective  tissue.  The 
follicles  are  grouped  into  irregular  lobules,  and  tliese  form  in  turn  the  lobes  of  the 


918 


THE   ORG  ASS   OF    VOICE 


gland.  Both  the  interior  of  the  follicles  and  the  spaces  in  the  connecting  areolar 
tissue  may  become  filled  with  colloid  material. 

Vessels. — The  arteries — which  are  relatively  very  large  and  frequently  anas- 
tomose— are  the  two  superior  thyroids,  the  two  inferior  thyroids,  and  an  occasional 
branch  which  ascends  on  the  front  of  the  trachea,  the  thyroidea  ima.  This  latter 
is  derived  either  from  the  innondnate  artery  or  from  the  arch  of  the  aorta. 

The  superior  thyroid  arteries  descend  to  supply  the  ai)ices  and  inner  and  fore 
parts  of  the  lateral  lohes;  whilst  the  inferior  ascend  to  supply  their  outer  and 
hinder  portions  below. 

The  veins  are  the  superior  middle  and  the  inferior  thyroid.  The  two  former 
join  the  internal  jugular  vein,  and  the  latter  the  innominate  of  the  corresponding  side. 

The  nerves  are  derived  from  the  middle  cervical  ganglion  of  the  sympathetic. 

Fig.  540. — Thymps  Gland  in  a  Cmi.n  at  Bieth. 


Thyro-hyoid  membrane 


THYROID  CARTILAGE  ~-iA  / 


Stemo-thyroid  muscle 
Crico-thyroid 
membrane 


Crico-thyroid  muscle  

THYROID  GLAND 

Right  common  earofid 

artery 

RIGHT  PXEVMrt- 

GAUTRJC  XERVh 

Rifi/il  internal  jugular 

rein 

Level  of  sternum 


SECTION  OF  CLAVICLE  ^ 
SECTION  OF   FIRST  RIB 


SECTION  OF  STERNUM    _ 


=^    Thyro-hyoid  muscle 

Lateral  portion  crico- 
thyroid membrane 

Omo-hyoid  muscle 
j^ij  Sterno-mastoid  muscle 

CRICOIU  CARTILAGE 
FIRST  RING  OF  TRACHEA 

—    TRACHEA 

Lett  suspensory 

\  ligament 

\        LI:FT  liECJ-RREST 
\Elt  VK 
CEsophagus 

Left  iiiiioiniiiate  vein 
LEFT  LOBE  OF  THYMUS 


Left  internal  manitnury 
artery 


Pericardium 


SECTION  OF  FIFTH   RIB 
CARTILAGE 


ENSIFORM   CARTILAGE 


TJiK  Til Y:\rrs  body  or  gland 

The  thymus  body,  lil>:e  the  thyroid,  is  ductless.  It  reaches  its  highest  de- 
velopment about  the  end  of  the  second  year.  Although  it  occasionally  retains  a 
considerable  size  in  the  adult,  it  usually  disappears  or  shrivels  away  to  an  insigni- 
ficant vestige. 


THYMUS   GLAND 


919 


It  is  common]}'  made  up  of  two  elongated,  nearly  equal  pyramidal  lo})es  of  a 
greyish  pink  colour,  which  meet  each  other  near  the  middle  "line;  Imt  they  vary 
in  number  and  are  inconstant  in  size.  There  may  be  but  a  single  lobe  present  or 
a  third  may  intervene  between  the  other  two.'  Sometimes  the  right  lol)e  and 
sometimes  the  left  lol)e  is  the  larger. 

The  thymus  body  is  about  two  inches  (50  mm.)  in  length,  about  one  inch  and 
a  half  (87  mm.)  in  breadth  at  its  base,  and  a  quarter  of  an  inch  (16  mm.)  in 
thickness. 

Its  weight  at  l)irth  is  about  half  an  ounce. 

Relations.— The  thymus  body  at  the  period  of  its  fullest  development   lies 


Fk;.  r)41.— TnvMts  Gi.axd  tx  a  Child  at  the  Age  ok  Two  Yeaes. 


SEVENTH  Ring  of  trachea 
Ritjht  carotid  arterij 

Kiff/it  fiibclaiian  artery 

IHnlii  i'momiiiale  rein 

THYMUS  GLAND 
Vena  rara  superior 

A  rch  of  aorta 


THYROID  CARTILAGE 

Central  portion  of  crico-thyroid 

membrane 
Crieo-thyroid  muscle 

FIRST  RING  OF  TRACHEA 

THYROID  BODY 


Ligament  connecting  thyroid 
and  thymus  bodies 


Left  carotid  artery 


Li  ft  xubclavian  intery 


LOBE  OF  THYMUS  PASSING 
BEHIND  VEIN 


innominate  rein 


A icli  of  aorta 


w 


jtartlv  in  the  thorax  and  partly  in  the  neck.  It  extends  upwards  as  far  as  the 
thyroid  body  covered  Ity  the  stcrno-hyoid  and  thyroid  muscles,  completely  hiding 
the  trachea  and  the  carotid  sheaths.  Below,  it  descends  into  the  superior  niedias- 
tinum  between  the  pleural  sacs  and  internal  mammary  vessels  as  far  as  the  fourth 
rib  cartilages,  and  lies  l)ehind  the  sternum,  the  sterno-hyoid,  and  stemo-thyroid 
muscles,  and  in  front  of  the  pericardium  and  larger  vessels. 

Structure. — A  thin  areolar  capsule  invests  the  lobes  of  the  thymus  gland,  and 
extends  ujjwards  in  the  form  of  two  flattened  fibrous  bands  to  be  attached  to  each 
lobe  of  the  thyroid  body.  These  bands  are  well  marked  at  the  period  of  liirth,  and 
seem  to  act  as  susi)ensory  ligaments.     If  the  capsule  is  removed,  it  is  .><een  to  send 


1)20  TEE   URUAXS   OF  RESPIRATION 

inwards  nuuieruus  prolongation;?  t'nnn  its  dct'p  surface,  which  pass  between  tlie 
lohules  to  surround  and  connect  them. 

The  lohuk's  are  irreguhir  and  many-sided,  and  consist  of  numerous  lymph 
follicles.  They  are  grou{)ed  around  a  central  tubular  cord  of  connective  tissue,  and 
when  unravelled  the  lo))e  can  l)e  lengthened  out,  the  lobules  then  apjjcaring  to  be 
attached  to  the  cord  in  a  spiral  fashion. 

The  vessels. — The  arteries  are  derived  from  the  internal  mannnary  and 
from  the  sui)evior  and  inferior  thyroids. 

The  veins  join  the  left  innominate  and  thyroid  veins. 

The  nerves  are  very  minute,  and  ]»roceed  from  the. sympathetic  and  pneumo- 
gastric. 


THE   ORQANS   OF  RESPIRATIOX 

THE  LUNGS  AND  PLEURA 

The  lungs — which  are  two  in  number — are  the  special  organs  of  respiration, 
and  occupy  the  greater  portion  of  the  chest  cavity.  They  are  separated  one  from 
the  other  by  the  heart  and  great  vessels,  and  the  other  contents  of  the  mediastinal 
spaces,  and  each  is  enclosed  in  a  i)leural  sac. 

THE  PLEURiE 

Each  lung  is  closely  invested  by  an  invaginated  serous  sac,  the  pleural  sac. 
The  inner  wall  of  the  sac,  which  is  closely  attached  to  the  lung  substance  and  sur- 
rounds its  root,  is  the  visceral  pleura.  The  outer  wall  of  the  sac  is  the  parietal 
])leura.  and  the  two  jiarts  are  directly  continuous  at  the  root  of  the  lung.  The 
l)arietal  pleura  covers  the  inner  surface  of  the  thoracic  wall,  and  it  forms  the  lateral 
l)oundary  of  the  mediastinal  space  of  the  thorax.  Under  ordinary  circumstances 
the  inner  surface  of  the  i)arietal  pleura  is  in  contact  with  the  outer  surface  of  the 
visceral  pleura,  or  at  the  most  only  a  tliin  layer  of  serous  fluid  intervenes,  and 
both  surfaces  are  smooth  and  glistening;  but  if  the  pleural  sac  is  opened  the  lung 
shrinks,  on  account  of  its  elasticity,  and  a  space,  the  pleural  cavity,  is  develo])ed 
between  the  two  layers. 

For  convenience  of  description  the  parietal  i)levu-a  may  Ix-  divided  into  three 
parts — the  external  or  costal,  the  inferior  or  diaphragmatic,  and  the  internal  or 
mediastinal.  The  costal  ])ortion  of  the  parietal  pleura  is  in  relation  with  the  ribs, 
the  costal  cartilages,  the  contents  of  the  intercostal  spaces,  the  triangularis  sterni. 
and  the  subcostal  muscles,  to  which  it  is  attached  l)y  the  endothoracic  fascia.  The 
dia])ln'agmatic  portion  rests  upon  the  diaphragm,  and  the  mediastinal  part  is  in 
relation  with  the  contents  of  the  mediastinal  space — that  is,  on  both  sides,  with 
the  pericardium,  the  phrenic  nerve  and  its  accompanying  vessels,  on  the  right  side 
in  addition  with  the  ascending  aorta,  the  superior  vena  cava,  the  vena  azygos 
major,  the  right  innominate  vein,  the  innominate  artery  and  the  right  vagus 
nerve;  and  on  the  left  side  the  additional  relations  are  the  transverse  and  descend- 
ing portions  of  the  aorta,  the  left  common  carotid  and  sulx-lavian  arteries,  the 
thoracic  duct,  the  left  su])erior  intercostal  vein  and  the  left  vagus  nerve. 

The  upper  extremity  of  each  ])leural  sac  extends  into  the  neck,  reaching  a  ])oint 
an  inch  (25  mm.)  to  an  inch  and  a  half  (37  nun.)  above  the  clavicle,  but  never 
al)ove  the  neck  of  the  fir.st  ril);  it  is  covered  by  a  lay(T  of  fascia  called  Sibson's 
fascia;  it  is  in  relation  with  the  subclavian  artery,  which  lies  in  a  groove  on  its 
antero-internal  aspect,  and  with  the  .scalenus  medius  and  anticus  muscles. 

The  borders  of  each  {)leural  sac  are  anterior,  inferior  and   posterior.      On  the 


THE  LUNGS 


921 


right  side  the  anterior  l)order  passes  obli(j[uely  downwards  from  the  apex,  Ix'hind 
the  sterno-clavicular  articulation,  to  the  middle  line,  at  the  Junction  of  the  manu- 
I)rium  with  the  body  of  the  sternum  (tig.  521),  thence  it  descends  vertically  to  the 
lower  end  of  the  gladiolus.  The  lower  border  extends  round  the  l)ase  of  the  sac, 
commencing  at  the  lower  end  of  the  gladiolus  it  runs  downwards  and  outwards 
behind  the  seventh  costal  (iartilage,  still  descending  it  crosses  the  seventh,  eighth, 
and  ninth  ribs  reaching  the  lower  border  of  tlie  latter  in  the  mid-axillary  line; 
passing  backwards  it  comes  into  relation  with  the  tenth,  eleventh,  and  twelfth  ribs, 
and  ascending  to  the  head  of  the  latter  it  joins  the  posterior  border,  and  then, 
turning  forwards,  it  passes  along  the  groove  between  the  pericardium  and  the  dia- 
phragm to  its  point  of  commencement.  The  posterior  border  extends  from  the 
neck  of  the  first  rib  to  the  head  of  the  twelfth;  it  is  broad  and  rounded.  The 
anterior  border  on  the  left  side  descends  inwards  ))ehind  the  sterno-clavicular  artic- 
ulation as  on  the  right  side,  and  reaches  the  middle  line  at  the  same  point,  then 
it  passes  vertically  downwards  to  the  level  of  the  fifth  chondro-st(!rnal  articulation 
(fig.  521),  from  this  i)oint  it  runs  downwards  and  outwards  behind  the  cartilages 


Fig.  542. — Antkrior  View^  of  Fcetal  Heart,  Vessels,  and  Lungs. 


SUPERIOR  LOBE  OF  RIGHT  LUNG 


Aorta 
I'liliKiiiiiiry  artery  — 

RIGHT  AURICULAR  APPENDIX  


DUCTUS  ARTERIOSUS 


'-   i  / 


—  I'lilinonary  artury 


SUPERIOR  LOBE  OF  LEFT 
LUNG 


LEFT  AURICULAR  APPENDIX 
Piihnonary  artery 


INFERIOR  LOBE 
4—  Descending  aorta 


of  the  fifth  and  sixth  ribs  to  the  seventh  costo-chondral  joint,  where  it  join.s  the 
inferior  border.  The  inferior  Ijorder  descends  across  the  eighth,  nine,,  and  tenth 
ril)S  to  the  lower  l)order  of  the  latter  in  the  mid-axillary  line,  further  back  it  crosses 
the  eleventh  rib  and  ascends  along  the  twelfth  ril)  to  join  the  posterior  lx)rder,  as 
on  the  right  side.  The  general  relaticms  of  the  inner  part  of  the  lower  border  and 
the  whole  of  the  posterior  border  are  the  same  as  on  the  right  side. 

The  lower  extremity  of  the  pleural  sac  does  not  extend  to  the  lower  extremity 
of  the  thorax,  laterally;  therefore  for  a  short  distance  the  diai)hragm  and  the 
lowest  intercostal  nniscles  are  in  <'ontact. 

Below  the  root  of  each  lung  a  fold  of  tlir  i»lt'ura  descends  to  tlu'  diai)hragm,  the 
ligamentum  latum  pulmonis.  The  ))leurai  sacs  on  each  side  j)ass  for  an  inch  or 
more  above  the  level  of  the  anterior  part  of  the  first  rib,  beneath  the  scalene  muscles, 
covering  the  apices  of  the  lungs,  and  the  ]»arietal  layer  is  here  strengthened  l»y  a  dome 
of  fascia  which  descends  from  beneath  the  nuiscles  to  the  inner  border  of  the  first 
rib.  The  interval  between  the  two  .sacs  is  considerable  ])oth  altove  and  below:  but 
opposite  the  second  piece  of  the  sternum,  corresponding  with  the  second,  third,  and 
fourth  rib  cartilages  (fig.  521),  they  are  clo.sely  approximated  or  in  actual  contact. 

The  lungs  are  not  (juite  so  extensive  as  the  jileural   sacs,  and  this  is  more  espe- 


922 


THE   ORGANS   OF  RESPIRATION 


cially  the  case  in  the  regions  of  tlie  intVi-ior,  and  the  lower  i)arts  of  the  anterior 
borders  where  two  layers  of  parietal  pleura  are  in  contact  with  each  other,  these 
regions  are  known  asthe  pleural  sinuses,  and  tliey  vary  in  extent  with  the  disten- 
sion of  the  lungs. 

The  right  pleural  sac,  though  shorter  and  wider  than  the  left,  reaches  as  a  rule 
somewhat  higlier  in  the  neck. 

The  Lungs. — Each  lung  presents  an  outer  and  an  inner  surface,  se})arated  by 
an  anterior  and  a  posterior  l)order,  with  a  base  and  an  apex. 

The  outer  surface  is  convex,  and  mainly  corresiwnds  to  the  concavity  of  tlic 
iimer  surface  of  Xho  lateral  wall  of  the  thorax. 

The  inner  surface  is  concave,  and  comes  into  contact  Avith  the  pericardium  and 
lateral  pleural  wall  of  the  mediastinal  spaces. 


Fio.  .^43. — Anterior  View  of  the  Thorax  with  Chest  Wall  removed,  showing  the 
Lungs.     (Modilied  from  Bourgery. ) 


Peetoralis  major  muscle 
Pectoralis  minor  muscle 

SUPERIOR  LOBE 


Serratus  magnus 
muscle 


INFERIOR  LOBE 


Diaphragm 

STERNUM 


INFERIOR  LOBE 


SECTION   OF  SEVENTH  RIB 


ENSIFORM  CARTILAGE 


The  posterior  border  is  the  longer;  it  is  thiek,  rounded,  and  siimotli,  and 
occupies  the  groove  on  tlie  side  of  the  vertebral  eolumn. 

The  anterior  border  is  thin,  irregular,  and  sharply  edged,  and  is  deeply  notehed 
in  the  left  lung  leaving  the  pericardium  uncovered. 

The  base  is  concave,  and  rests  on  the  corresponding  arch  of  the  diaphragm ; 
whilst  the  apex  passes  above  the  anterior  part  of  the  first  rib  to  lie  beneath  the 
subclavian  artery.  Each  lung  is  divided  into  two  lobes  by  a  deep  fissure  which 
passes  obliiiuely  upwards  and  inwards  almost  to  the  root  of  the  organ.  This  fissure 
commences  at  the  posterior  l)order,  about  7 '5  cm.  below  the  a])ex,  and,  sweeping 
round  the  convex  surface  of  the  lung,  ends  near  the  anterior  boixler  below. 

In  the  right  lung  a  second  fissure  passes  from  the  anterior  edge  to  reach  the 
main  fissure  near  its  centre,  marking  off  a  third  or  middle  lobe. 


THE  LUNGS 


923 


The  right  lung  is  somewhat  larger  than  the  left;  it  i.s  also  shorter,  and,  as  just 
mentioned,  possesses  three  lobes. 

Above  the  middle  of  the  inner  aspect,  but  nearer  to  the  posterior  than  the  ante- 
rior border,  each  hmg  is  connected  to  the  puhiionarv  vessels  and  bronclii  whicli 
form  the  main  ])art  of  its  root. 

Tlic  root  of  the  lung  is  composed  of  tiir  pulmonary  artery  and  tlie  pul- 
monary veins  with  the  corresponding  bronchial  tube  ;  and,  in  addition,  tlic 
bronchial  vessels,  tlie  l)ranches  of  the  anterior  and  posterior  pulmonary 
plexuses  with  .some  bronchial  lymphatic  glands  and  areolar  tissue — the  whole 
being  encased  in  a  pleural  covering. 

The  right  root  lies  bcliind  the  superior  cava  and  upper  jmrtion  of  the  rigiit 

Fio.  544. — PosTERioK  View  ok  tiik  Thokax  with   Chp:st  Wall  Re.moved,  showing   the 

LrxGS.     (.Motlilied  iVom  Ijunri'erv. ) 


Supra-spiuatus  muscle 


SPINE  OF  SCAPULA 


Infra-spinatua  muscle 


Cut  edge  ol  pleura 


(ESOPHAGUS 
Cut  edge  of  pleura 


Diaphragm 


auricle  of  the  heart,  the  anterior  pulmonary  plexus  and  the  phrenic  nerve;  above, 
tlie  vena  azygos  major  arches  to  join  the  superior  cava;  behind  is  the  posterior 
l)uhnonary  plexus,  the  jMieumogastric  nerve,  and  the  vena  azygos  major;  whilst 
below  is  the  ligamentum  latum  pulmonis. 

The  left  root  has  tlie  pulmonary  i)lcxus  and  left  phrtnic  in  front;  above  it  is 
the  arch  of  the  aorta;  behind,  the  descending  aorta  and  ]ineunu)gastric  nerve  with 
the  po.sterior  j)ulmonary  plexus;  whilst  below  stretches  downwards  the  ligamentum 
latum  pulmonis. 

The  chief  structures  contained  within  the  i-oot  vary  in  ])osition  on  the  two  sides. 

From  above  downwards  on  th<'  right  side,  they  lie  as  follows — bronchus, 
artery,    and  ui)per  vein;    whil.st  on  the  left  side   the  artery  is  the  highest,    the 


924 


THE  OROAXS  OF  RESPIRATIOX 


l)i-()nclius  is  ))lacc'(l  lu'xt.  and  tlir  upper  vein  is  again  tlic  lowest.  From  before 
backwards  on  both  sides,  the  arrangement  is — upi)er  vein,  artery,  and  bronehus. 

The  weight  of  the  lungs  together  is  about  forty-two  ounces;  the  right  lung  is 
about  two  ounces  heavier  than  the  left. 

In  color  the  lungs  are  of  a  i)inkish  white;  but  they  become  darker,  mottled, 
and  even  black,  as  age  advances. 

Structure. — The  lungs  possess  an  external  serous  coat  derived  from  the 
pleura,    beneath  which  is  a  delicate  subserous  layer. 

The  parenchyma,   or  lung  substance,   is  comjmsed  of  minute   lobules   con- 


FiG.  545. — Anterior  View  of  the  Luxos:  PERiCARmrM.     (Moditied  IVoni  Bourgery.] 


Vaia  cai  a  svpei  toi 


BRONCHUS 
Puhnonai  y  ailfiy 
Pulmonai  ii  lein 


A)fli  01  aotia 

Puhiii»iai  >i  ntlfry 
BRONCHUS 
Puhnonat  y  vein 


ENSIFORM   CARTILAGE 


nected  by  interlobular  areolar  tissue.  Each  lobule  is  made  up  of  a  ramification  of 
a  bronchial  tube  with  its  cluster  of  terminal  air  cells,  with  a  minute  plexus  of 
pulmonary  and  bronchial  vessels,  nerves,  and  lymphatics. 

The  vessels. — The  pulmonary  arteries  convey  venous  blood  from  the  heart 
to  the  lungs;  they  divide  into  bvaneln^s  wliich  follow  the  bronchial  tubes,  and 
finally  terminate  in  a  flat  mesln\H)rk  upon  the  walls  of  the  intercellular  passages 
and  air  cells. 

The  radicles  of  the  pulmonary  veins  start  from  this  network;  they  coalesce 
into  larger  brandies  wliieb  aceompany  the  artei'ies  and  terminate  in  two  large  ves- 
sels on  each  side,  wliieb  retui-n  tbe  arterial  blood  to  the  left  auricle  of  the  heart. 


THE  PERICARDIUM  925 

The  bronchial  arteries,  one  on  the  right  side,  and  two  on  the  left,  are  the 
nutrient  vessels  of  the  knigs.  The  right  springs  from  the  first  aortic  intercostal 
artery  or  from  the  upper  left  bronchial  artery.  The  two  left  bronchial  arteries  are 
branches  of  the  descending  thoracic  aorta.  Some  of  tlieir  branches  ramify  in  an 
open  jilexus  outside  tlie  hmg  beneath  tiie  i)leura;  another  set  supply  the  inter- 
lol)ular  areohir  tissue;  whilst  a  third  set  of  branches  supply  the  bronchial  tubes 
witli  their  lining  membrane  and  muscular  walls,  the  walls  of  the  vessels,  and  the 
lironchial  glands.  The  ramifications  of  this  set  reach  and  mingle  Avith  the  pul- 
monary vessels,  and  thus  a  small  quantity  of  the  blood  conveyed  by  the  bronchial 
arteries  is  returned  as  arterial  through  the  pulmonary  veins  to  the  heart. 

The  bronchial  veins  consist  of  a  superficial  and  a  deep  set,  which  join,  to 
foiin  a  single  vessel  on  each  side;  the  right  bronchial  vein  oi)ens  into  the  vena 
azygos  major,  and  the  left  into  the  left  superior  intercostal  vein. 

The  lymphatics  form  a  suj^erficial  and  a  deep  set. 

The  nerves  nrc  dcrixcd  frnni  the  anterior  and  ]»(jsterior  pulmonary  plexuses. 


THE    ORGANS   OF   CIRCrLATlOX 

THE   PEEICARDIUJH 

The  pericardium  is  a  cone-shaped,  fibro-serous  sac  surrounding  the  heart,  with 
its  apex  above,  and  its  base  below  and  adherent  to  the  diaphragm.  The  fibrous 
layer  is  very  strong  and  inelastic,  and  is  composed  of  interlacing  fibres.  Below, 
its  connection  with  the  central  tendon  of  the  diaphragm  is  close  and  intimate.  It 
is  very  firmly  bound  to  the  caval  opening,  but  loosely  attached  and  easily  separable 
elsewhere.  Above,  it  is  lost  on  the  sheaths  of  the  great  vessels,  all  of  which  receive 
distinct  investments,  with  the  single  exception  of  the  inferior  vena  cava,  which 
pierces  it  from  below. 

The  aorta.  su])erior  vena  cava,  botli  divisions  of  the  jjulmonary  artery,  with  the 
ductus  arteriosus,  together  with  the  four  pulmonary  veins,  are  all  ensheathed  in 
tliis  manner.  The  fibrous  portion  of  the  pericardium,  through  the  sheaths  pro- 
longed over  the  great  vessels,  ultimately  becomes  continuous  above  with  the  deep 
cervical  fascia.  Two  slight  bands  of  fibrous  tissue — the  sterno-pericardial  bands 
or  ligaments — connect  the  front  of  the  pericardium,  above  and  below,  with  the 
posterior  surface  of  the  sternum. 

The  serous  layer  is  smooth  and  glistening.  Its  parietal  portion  lines  the 
inncn-  surface  of  tlie  fibrous  bag.  The  visceral  portion  is  retiected  over  the  surface 
of  the  heart  and  the  roots  of  the  great  vessels,  the  two  layers  being  in  close  contact, 
and  moistened  with  a  thin  secretion  to  allow  the  free  movement  of  the  heart.  A 
seri(;s  of  pouches  or  sinuses  are  thus  formed  at  the  line  of  reflexion.  Between  the 
inferior  vena  cava  and  lower  left  ])ulmonarv  vein,  the  oblique  sinus  ascends 
behind  the  left  auricle,  partially  investing  the  pulnK)nary  arteries  and  the  pul- 
monary veins  of  the  right  and  left  sides,  between  which  it  passes.  Small  ])ouches 
from  the  main  sac  dip  betAveen  the  veins  to  meet  the  inflexions  from  the  sides  of  the 
oVjli(jue  sinus  just  noticed,  thus  completing  the  serous  coverings  to  these  vessels. 

Pouches  can  be  further  traced  between  the  inferior  vena  cava  and  lower  pulmo- 
nary vein  of  the  right  side,  between  the  superior  vena  cava  and  iii^i^er  ]>ulmonarv 
vein  of  the  same  side,  and  also  between  the  left  ])ulmonary  artery  and  left  U]tper 
pulmonary  vein. 

A  tubular  prolongation,  moreover,  surrounds  both  the  root  of  the  pulmonary 
artery  and  the  aorta  in  common,  and  these  are  the  only  vessels  whicli  can  be  said 
to  have  a  complete  and  continuous  investment. 

There  is,  therefore,  a  connnunication  behind  them  between  the  riglit   an<l  left 


926  THE  ORG  Ays   OF  CIRCULATION 

sides  of  tlie  pericardial  sac;  this  is  tlie  irreat  sinus  of  the  })ericardiuni.  The  infe- 
rior vena  cava  rt'ccivcs  a  very  iiii]i«rfc(t  covering. 

The  vestigial  fold  of  the  pericardium  is  a  doul»ling  of  the  serous  layer  which 
passes  hetween  the  left  pulmonary  artery  ahove  and  left  superior  i)uhnonary  vein 
below.  It  contains,  besides  some  fatty  and  areolar  tissue,  the  shrunken  remains  of 
the  left  superior  vena  cava.  It  is  connected  aliove  with  the  left  superior  intercostal 
vein,  and  below  with  the  left  auricle  and  oblique  vein  of  Marshall, — these  veins 
with  the  coronary  sinus  iiaving  originally  formed  ])ortions  of  the  left  ujjper  cava. 

Relations. — In  front  are  found  the  thymus  gland  or  its  remains,  areolar  tissue, 
the  sterno-jiericardiac  ligaments,  the  left  triangularis  sterni  muscle,  the  internal 
mammary  vessels,  the  anterior  margins  of  the  pleural  sacs  and  lungs,  and  the  ster- 
num. Laterally,  it  is  overlapped  by  the  lungs  with  their  pleural  sacs,  and  it  is  in 
relation  with  the  i)hrenic  nerves  and  their  accompanying  vessels.  Posteriorly,  it  is 
in  relation  with  the  o?so]>hagus,  and  pneumogastric  nerves,  the  descending  aorta, 
the  thoracic  duct,  and  vena  azygos  major. 

On  opening  the  pericardium  the  following  structures  may  ])e  observed:  the 
greater  part  of  the  right  and  a  portion  of  the  left  ventricle  with  the  interventric- 
ular sulcus,  the  right  auricle  and  right  auricular  appendix  (the  latter  overlaji- 
})ing  the  root  of  tlie  aorta),  the  auriculo-ventricular  suk-us;  the  first  portion  of  the 
aorta  with  the  superior  vena  cava  on  its  right  side,  and  the  pulmonary  artery 
at  first  overlying  and  then  passing  to  its  left  side,  with  the  tip  of  the  left  auricular 
appendix.  If  the  heart  be  raised  upwards  and  to  the  right,  its  posterior  surface 
is  seen  to  consist  of  the  greater  part  of  the  left  ventricle,  and  the  remaining  por- 
tion of  the  right,  the  interventricular  sulcus  dividing  the  two.  Lying  transversely 
above  the  ventricle  in  the  auriculo-ventricular  groove  is  the  coronary  sinus, 
receiving  some  of  the  cardiac  veins,  and  also  the  oblique  vein  of  Marshall  from 
the  back  of  the  left  auricle,  the  roots  of  the  pulmonary  veins,  and  the  very  small 
portion  of  the  inferior  cava  above  the  diaphragm,  may  also  l)e  noticed. 

The  two  ventricles  rest  in  about  ecjual  ])roportions  on  the  central  tendon  of  the 
diaphragm.  The  main  branches  of  the  coronary  arteries  of  the  heart  occupy  the 
grooves. 

Vessels. — The  arteries  of  the  pericardium  are  derived  from  the  pericardiac, 
oesophageal,  and  bronchial  branches  of  the  thoracic  aorta  and  from  the  internal 
manmiary  and  phrenic  arteries. 


THE  HEART 

The  heart — enclosed  in  the  pericardium — occupies  the  greater  ]iart  of  the  middle 
mediastinal  space.  It  is  a  somewhat  flattened,  cone-shaped,  hollow,  muscular 
organ. 

Position. — In  the  adult  the  heart  lies  obliquely  behind  the  lower  two-thirds  of 
the  sternum,  projecting  considerably  to  its  left  side.  .  Its  base  is  directed  slightly 
upwards  and  backwards,  and  to  the  right;  its  apex  downwards  and  forwards,  and 
to  the  left.  The  base  corresponds  to  the  sixth,  seventh,  and  eighth  thoracic 
vertebrae;  and  the  apex  to  the  chest  wall  on  the  left  side,  between  the  fifth  and 
sixth  rib  cartilages. 

It  may  be  mapped  out  on  the  chest  wall  in  the  following  manner:  a  line  drawn 
across  the  sternum  about  the  level  of  the  lower  borders  of  the  second  costal  carti- 
lages, passing  half  an  inch  to  the  right  and  one  inch  to  the  left  of  the  sternum,  will 
indicate  the  jiosition  of  its  base,  from  which  the  great  vessels  arise. 

The  apex,  as  l)efore  ol)served,  strikes  the  chest  wall  between  the  fifth  and  sixtli 
rib  cartilages  on  the  left  side,  at  a  spot  about  a  couple  of  inches  (50  mm.)  below 
the  nipple,  and  one  inch  (25  mm.)  to  its  sternal  side,  or  three  and  a  quarter  inch(>s 
(81  nnn. )  from  the  middle  line  of  the  sternuni,  in  the  fifth  interspace. 

The  lower  border  is  formed  l)y  the  right  ventricle  and  rests  on  the  central 
tendon  of  the  diai)hragm.  It  is  defined  by  a  line  curving  downwards,  connnencing 
at  the  apex,  and  crossing  close  to  the  sterno-xiphoid  articulation  and  ternnnatiug 
at  the  right  edge  of  the  sternum  near  its  junction  with  tlie  sixth  cartilage. 

The  lateral  borders  may  l)e  completed  ])y  drawing  curved  lines  upwards  from 


THE  HEART 


92; 


the  points  last  named  to  the  ends  of  the  basal  line.  The  right  border  consists 
entirely  of  the  right  auricle,  and  the  left  of  the  left  ventricle. 

Tlie  position  of  the  auriculo-ventricular  sulcus  is  indicated  by  a  line  from  the 
third  left  costal  cartili^ge  to  the  sixth  right. 

Size  and  weight. — In  the  adult  the  heart  measures  about  five  inches  (125 
mm.  J  from  base  to  apex,  three  and  a  half  inches  (87  mm.)  acnjss'  where  it  is 
broadest,  and  two  and  a  lialf  (62  nnn. )  at  its  thickest  portion.  In  the  male  its 
weight  averages  about  eleven  ounces,  and  in  the  female  about  nine  ounces.  It 
increases  both  in  size  and  weight  up  to  advanced  life,  the  increase  being  most 
marked  up  to  the  age  of  twenty-nine  years. 


Fig.  546. — Anterior  View  of  the  Heart  with  the  Larger  Vessels. 
(By  permissiou.     Museum  of  the  Royal  College  of  Surgeons.) 


Left  common 

carotid  artery 

Right  superior  thyroid  vein     Lfjt  superior      | 

Right  common  carotid  artery 

Internal  Jugular  vein 

Vertebral  vein 


Internal  jugular  vein 

Left  vertebral  rein 

i 


Subclavian  vein 
Inferior  thyroid  veins 


I'ena  azygos  major 

Vena  cava  superior 


Aorta 

Right  pulmonary 

artery 

PERICARDIUM 
RIGHT  AURICLE  /, 

RIGHT  VENTRICLE 


Vena  cava  inferior \^ 


ICxternal  jugular  vein. 


Left  subclavian  vein 
Left  innominate  vein 


Left  superior  intercostal  vein 
DUCTUS  ARTERIOSUS 


Left  pulmonary  artery  and 

ve  in 
LEFT  AURICULAR  APPENDIX 


Pulmonary  artery 


LEFT  VENTRICLE 


The  anterior  surface  of  tbe  heart  is  convex,  and  looks  upwards  and  i'( .r\vard.<. 
Its  lower  and  posterior  surface,  whicli  rests  ])art]y  on  the  diajjhragm,  is  Hattened. 
The  borders  wliicli  (Uvide  the  two  surfaces  of  tlie  "heart  nu-et  near  the  ajiex;  the 
right  b(jrder  is  tliin  and  rather  longer  tlian  the  left,  wliilst  tlie  latter  liorder  is  thick 
and  wunded. 

The  auricles  are  divided  from  tlie  ventricles  l)y  a  transviT-^e  groove,  the 
auriculo-ventricular,  which  is  interrujited  in  front  l>y  the  origin  of  the  jailmoiiary 
artery.  Tlie  ventricles  are  similarly  divided  from  eacli  otlier  by  tbe  interventricu- 
lar groove,  Avhich  runs  ol)liquely  on  the  anterior  and  posterior  surfaces  of  the 
heart,  meeting  below  just  to  the  right  of  the  apex  where  they  are  continuous. 


928 


THE   ORGANS   OF  CIRCULATION 


Tiie  grooves  are  placed  near  the  borders  of  the  heart,  so  that  the  right  ventricle 
is  mainly  anterior,  and  the  left  i)osterior. 

Of  the  four  cavities  into  which  the  heart  is  divided,  the  right  auricle  and 
ventricle  constitute  its  venous  side,  whilst  the  left  auricle  and  ventricle  belong  to 
its  arterial  side. 

The  riglit  auricle  receives  the  venous  blood  of  the  body  through  the  two  venae 
cavfe,  and  of  the  heart  through  the  coronary  sinus,  and  transmits  it  into  the  right 
ventricle.  The  right  ventricle  in  turn  transmits  the  venous  blood  to  the  lungs 
through  the  pulmonary  artery.  From  the  lungs  it  is  returned  arterialised  to  the 
left  auricle  of  the  heart  by  the  pulmonary  veins.     From  the  auricle  it  passes  into 

Fig.  547. — Sno^mNG  the  Position  of  the  Heart  and  its  Valves  in  Relation  to  the 

Chest  Walls. 

(Reduced  from  Hensman  and  Fisher's  Anatomical  Outlines.) 

(The  rightauricle  ami  ventricle,  with  the  puhiionary  .semilunar  and  tricuspid  valve?,  are  outlined  in  blue  tints; 

whilst  the  left  auricle  and  ventricle,  with  their  corresponding  valves,  are  indicated  in  red.) 


the  corresponding  ventricle,  and  thence  through  the  aorta  and  its  branches  to  all 
parts  of  the  body,  including  the  heart  itself. 

The  right  auricle, — The  right  auricle  forms  the  upper  and  right  part  of  the 
heart;  below  it  is  the  right  ventricle;  to  the  inner  side  anteriorly  it  embraces  the 
root  of  the  i)ulmonary  artery,  and  posteriorly  it  is  separated  from  the  left  auricle 
by  the  interauricular  septum,  and  it  is  in  relation  with  the  right  inferior  pulmo- 
nary vein.  It  is  lined  by  a  smooth  and  delicate  membrane,  the  endocardium, 
wliich  is  continuous  with  the  inner  coats  of  the  l)l(K)d-vessels.  It  ])r('sents  a  large 
(juadraiigular  cavity,  the' sinus  venosus  or  atrium,  and  one  nuich  smaller  within 
the  auricular  appendix.  The  auricle  forms  the  right  and  fore  part  of  the  base  of 
the  heart. 


THE  HEART 


929 


Openings. — Of  tlie  tliree  tliit'f  (j})t'nings,  that  of  tlie  superior  cava  appears  at 
tlie  iip])er  and  l»ack  ]»art  of  tlic  cavity;  whilst  at  tlic  lower  ami  hack  part  is  the 
opening  of  the  inferior  cava.  The  right  auriculo-ventricular  opening,  which 
leads  into  the  ventricle,  is  ])laced  helow  and  in  front;  whilst  alcove  and  in  front  the 
cavity  is  })rol()nged  into  the  auricular  a})j)endix. 

The  orifice  of  the  coronary  sinus  lies  between  the  lower  eaval  and  auriculo- 
ventricular  oi)enings.  J5(sidcs  these  there  are  about  a  score  of  small  scattered 
orifices,  known  as  the  foramina  Thebesii. 

The  superior  caval  opening  is  valveless,  and  is  directed  downwards  and  for- 
wards towards  the  auriculo-ventricular  opening. 

The  inferior  caval  opening  is  somewhat  larger,  and  is  directed  u]iwards  ami 
inwards.  It  is  usually  guarded  l)y  a  semilunar  fold,  the  Eustachian  valve,  whidi 
is  much  larifer  in  f(etal  life,  and  which  then  serv-es  to  direct  the  current  of  hlood 


Fig.  548. — Tkaxsvekse  Section   passing  through  the  Aukicles  of  the  Heart,  showing 

THE  Al'RICri.O-VENTRIClLAR   ORIFICES  AND  THE  SEMILUNAR  VaLVES  OF  THE   PULMONARY 

Artery  and  Aorta.     Seen  from  above. 

(The  portions  of  the  auricles  removed  are  seeu  in  Fig.  oo2.) 

Right  aurieulo-ventrieular  orifice  and  tricuspid  valve 


LEFT  ANTERIOR  SEGMENT  OF  PULMONARY 
SEMILUNAR  VALVE 


CHORD<€  TENDiNE>E 


I y  ^^     "'G.HJ.fOSTERIOR  SEGMENT  OF 


AORTIC  SEMILUNAR  VALVE 


Left  auriculo-ventricular  orifice  and  mitral  valve 


tlirough  a  foramen  in  the  wall  tlividing  the  two  auricles.  It  is  attached  by  its 
convex  margin  to  the  front  and  left  side  of  the  vein,  its  free  concave  edge  looking 
upwards  and  to  the  right.  The  left  cornu  or  horn  of  the  crescent  is  continuous 
with  the  anterior  edge  of  the  annulus  ovalis,  whilst  the  right  horn  is  lost  on  the 
auricular  wall.  The  Eustachian  valve  contains  interlacing  muscular  filu-es;  it  is 
often  very  incomplete  and  sometimes  perforated. 

The  coronary  sinus  returns  the  blood  from  the  heart  substance,  and  is  gunrded 
by  a  semilunar  or  sometimes  doul)le  valve,  known  as  the  coronary  valve,  or  valve 
of  Thebesius.  Like  the  Eustachian,  it  is  formed  of  a  fold  of  the  endocardium, 
and  serves  to  direct  the  blood  current,  but  does  not  prevent  regurgitation.  It  is 
sometimes  perforated,  and  occasionally  presents  the  most  delicate  lacework. 

The  foramina  Thebesii. — The  greater  number  of  these  small  orifices  end 
blindly,  but  the  rest  are  the  terminations  of  minute  veins  from  the  muscular  sub- 
stance (venae  minimae  cordis  .  One  of  these,  more  constant  tlian  tlie  others, 
59 


r)30  TIIK   ORdAXS    OF  ClRClLATIOX 

the  vena  Galeni  (right  marginal),  usually  open,  b.low  the  superior  cava,  en  the 

''^^'xhe'cavityof  the  right  auricle  is  smooth,  except  upon  its  anterior  wall,  and 
within  'iH  M.p.ndix,  whore  it  is  ridged  with  muscular  bands  (the  muscuh 
nect^^nati)    w   ich  terminate,  aix.ve,  along  a  ridge,  the  crista  termmahs  . 

^     T IK   er kta   terminalis   corresponds   externally  with  a  sulcus,  the  sulcus  termi- 


K„.     -,49-\NTEKIUK    VIKW    OK   THE   RiOHT   CHAMBERS   OF  THE   HEART,    WITH   THE 

■  Great  Vessels. 


Left  carotid 


Innomiiiale 


Arcli  of  Aorta 
Vfiia  cara  siij/erior 


RIGHT  AURICULAR 
APPENDIX 


Orifice  of  vein 
of  Galen       \ 


ANNULUS  OVAL] 


Left  siiliclarian 


Jii(//tl pulmonary  a.rtery 
.'  Ductus  arteriosus 

Left  ptiliiKiunry  artery 

Pulmotiari/  artery 
Pulmonary  semilunar  valves 

LEFT  AURICULAR  APPENDIX 


Small  papillary  muscle  connected 
with  septum 

tl    Columna  carnea 
X  •   CHORD/E  TENDINE/E 


Anterior  papillary 
muscle 


Left  coronary  artery 


FOSSA  OVALIS 


T'cjia  card  inferior    jj^^g 
ANTERIOR  SEGMENT  OF  TRICUSPID  VALVE 


RIGHT  SEGMENT  OF  TRICUSPID  VALVE 

SECTION  OF  VENTRICULAR  WALL 


Vena  cara  inf 


3    Posterior  papil-      2    Columna  carnea 
lary  muscle 


nalis  which  runs  across  the  auricle  from  the  front  of  the  superior  cava  to  the  left 
of  the  inferior  cava,  and  both  the  groove  and  the  ridge  indicate  the  line  ot  union 
of  the  sinus  venosus  of  the  fretus  Avith  the  auricle  proper. 

\t  the  lower  part  of  the  posterior  wall  or  septum  which  dividi'S  the  two  aiincltjs, 
and  just  above  the  orifice 'of  the  inferior  cava,  is  a  smooth  oval  depression,  the 
fossa  ovalis.  It  marks  the  position  of  the  opening  in  the  f(vtal  heart,  to  he 
descrilied  hereafter;  and  is  bounded  bv  a  well-marketl  rounded  edge,  the  annulus 


THE  HEART 


981 


ovalis.  Bcneatli  its  upper  inaririn  a  little  valvular  i)OU{li  may  usually  l»e  notiet'd 
Avhicli  leads  iuto  a  small  orifice  ])assin,i^  iuto  the  left  auricle. 

The  tubercle  of  Lower — which  is  jtlaced  on  the  rijiht  of  the  cavity  between  the 
orifices  of  the  two  cavte — is  well  marked  in  some  of  the  lower  animals,  hut  it  is  quite 
an  insignificant  eminence  in  man. 

The  right  ventricle  forms  the  larger  })art  of  the  heart  in  front,  where  it  is 
convex;  hut  helow,  where  it  rests  upon  the  diaphragm,  it  is  flattened.  It  forms 
the  whole  of  the  lower  l)order  (iiiargo  acuti(s)  of  the  heart,  but  it  does  not  reach  the 
apex,  which  is  formed  entirely  by  the  left  ventricle. 

It  lies  l)ehind  the  lower  part  of  the  body  of  the  sternum  and  the  cartilages  of 
the  fifth,  sixth,  and  seventh  ribs  of  the  left  side. 

In  form  the  ventricle  is  triangular,  in  section  semilunar,  and  its  walls  are  much 
thinner  than  those  of  the  left  ventricle.  Its  upper  and  left  angle  is  continuous 
Avith  the  root  of  the  pulmonar}'  artery;  and  ujjon  opening  the  cavity  the  two  are 
seen  to  be  continuous  through  a  cone-shaped  prolongation — the  infundibulum  or 
conus  arteriosus. 

At  the  opposite  angle  there  is  a  second  and  larger  opening,  leading  from  the 
right  auricle,  the  auriculo-ventricular  orifice.  It  lies  below  and  to  the  right  of  the 
jiulmonary  orifice.     The  apex  of  the  ventricle  points  to  the  left. 


Fig.  5.50. — Traxsversp:  Sectiox  through  the  Heart  xear  its  Apex.  Showixg  the  Rela- 
tive Thickness  of  its  Muscular  Walls,  the  Bulging  of  the  Sf.ptum  towards  the 
Kight  Ventricle,  and  the  Shape  of  the  Cavities. 


CAVITY  OF  LEFT 
VENTRICLE 


CAVITY  OF  RIGHT 
VENTRICLE 


Section  of  papil- 
lary muscle 


Posterior  coronnri/ 

arti-ni 


Th(^  two  openings  just  named  are  guarded  by  valves  and  se])arated  by  a  rounded 
muscular  projection  of  the  ventricular  wall.  The  inner  surface,  or  body,  of  the 
ventricle  ])resents  a  somewhat  complicated  arrangement  of  muscular  ridges,  bands, 
and  columns,  which  become  smaller,  more  numerous,  and  more  closely  interlaced 
at  the  a})ex  and  near  the  margin,  but  which  disappear  in  the  infundibulum. 

These  projections,  or  columnae  carneae,  are  usually  divided  into  three  sets  : 
(1)  mere  ridges:  (2)  bands  attached  to  either  end  but  elscAvhere  free;  and  (8)  a  third 
set,  the  musculi  papillares,  which  need  a  more  detailed  description  (fig.  549). 

A  special  band,  the  so-called  moderator  band,  which  is  constant  in  the  .sheei>, 
is  occasionally  a  well-marked  structure  in  tlie  luniian  heart,  stretching  between  its 
anterior  and  sej)tal  walls.  The  musculi  papillares  are  attached  l>y  their  broad 
end  to  the  ventricular  Avail,  and  liy  their  extreiiiiiies  to  tendinous  cords  (chordae 
tendineae),  Avhich  restrain  and  harmonise  the  action  of  the  valves  guarding  the 
auiicul(j-ventricular  oi)ening.  Three  of  these  are  larger  and  more  constant  than 
the  rest:  an  anterior,  connected  Avith  the  front  Avail  aboA-e  the  moderator  band;  a 
right,  near  the  margin,  Avhich  is  also  attached  to  the  anterior  Avail;  and  a  posterior, 
Avhich  arises  from  the  septum.  The  septal  Avail  of  the  A-entricle  so  bulges  into  the 
cavity  as  to  make  its  cross-section  appear  crescentic. 


932 


THE   ORCAXS    OF  CIRCILATIOX 


The  Openings  and  their  Valves 

The  orifice  of  the  pulmonary  artery  is  circular  and  obliquely  placed  at  the 
suniiuit  of  the  infundilmlum  near  the  scptuui.  It  is  guarded  ])y  three  valves,  the 
pulmonary  semilunar  valves.  Of  these  two  are  placed  anteriorly  and  one  pos- 
teriorlv  (tig.  ")4S).  liuiucdiately  above  and  liehind  each  semilunar  valve  there  is 
a  ])<incli  or  sinus.  These  collectively  constitute  the  i)ulnionary  sinuses,  or  sinuses 
of  Valsalva. 

Each  valve  is  formed  of  a  fibrous  layer  within  a  redu])lication  of  the  lining 
membrane,  which  is  continuous  on  the  upper  surface  with  the  innermost  coats  of 
the  artery,  and  on  the  opposite  surface  with  endocardium  of  the  ventricle. 

In  the  centre  of  the  free  straight  edge  of  each  valve  there  is  a  little  fibro-carti- 
laginous  nodule,  the  corpus  Arantii,  and  this  margin  is  further  strengthened  by  a 
delicate  tendinous  band.  Another  fibrous  band  in  like  manner  strengthens  the 
convex  attached  portion  of  the  valve,  and  from  this  a  third  set  of  obli<juely  inter- 
lacing filires  pass  througliout  the  whole  valve  towards  the  nodule.  Two  narrow 
crescent-s4iaped  areas,  the  lunulae,  near  the  free  edge  on  each  side  of  the  nodide, 
remain  almost  free  from  this  fibrous  invasion,  and  it  is  these  thinner  portions 
which  are  in  apposition  during  closure  of  the  valve.  A  fibrous  ring  strengthens  the 
pulmonary  orifice,  giving  attachment  beloAv  to  the  muscular  fibres  of  the  heart;  whilst 
above,  opposite  the  sinuses  of  Valsalva,  it  is  deeply  hollowed  into  three  semilunar 


Fig.  551. — Interior  View  of  the  Aortic  Semilunar  Valves. 

n 


Sinus  of  Valsalva 

Section  of  fibrous  ring 

Free  edge  of  valve 


Orifice  of  right  coronary 
artury 

Corpus  Arantii 
~    Semilunar  valve 


Decussating  fibrous  tissue 
of  valve 


notches.  The  valves  are  attached  to  the  edges  of  these  notches  as  Avell  as  to  the 
horns  which  project  inwards  and  separate  them  from  one  another.  (See  fig.  551,  of 
the  aortic  valves,  in  wliich  these  characters  are  present  and  more  strongly  marked. ) 

The  auriculo- ventricular  opening  is  oval  and  guarded  by  the  tricuspid  valve. 
The  three  triangular  flaps  of  this  valve  are  continuous  with  one  another  at  their 
broad  ends,  and  so  form  a  continuous  fold  around  the  orifice;  but  Ijeyond,  they 
])roject  with  jagged  and  sharply  dentated  edges  towards  the  apex  of  the  ventricle. 

The  chordie  tendinea%  which  chiefly  arise  from  the  papillary  muscles  already 
described,  pass  to  their  free  borders  and  ventricular  surfaces.  The  largest  segment 
of  the  valve  is  placed  in  front,  between  the  auriculo-ventricular  orifice  and  the 
infnndibulum,  the  smallest  behind  near  the  septum,  and  tlic  third,  which  is  the 
most  movable,  is  situated  on  the  right. 

Smaller  segments  intervene  l)etween  the  larger  flaps.  The  cliorda^  tendinea', 
which  arise  in  groups  from  the  papillary  muscles,  divide  as  they  pass  to  l)e  attached 
to  the  edges  and  ventricular  surfaces  of  the  neighbouring  segments.  Additional 
cords  are  furnislied  from  the  ventricular  walls,  and  es{)ecially  from  the  sei)tum  to 
the  small  segment,  and  soine  of  these  are  provided  with  little  pajiillary  muscles. 

The  segments  of  this  valve,  except  at  the  extremities  and  margins,  contain 
abundant  fibrous  and  a  small  amount  of  muscular  tissue.  They  are  attached  by 
their  thickened  bases  to  a  fibrous  ring  which  surrounds  and  strengthens  the  orifice. 
The  surfaces  whicli  lof)k  towards  the  o]ioning  arc  smooth,  wliilst  u])on  the  op])Osite 


THE  HEART 


9i)0 


surfaces  the  chordse  tendineop  form  an  arched  interlacement,  which  has  bocn  well 
likened  to  tin-  fan  tracery  of  Gothic  architecture.      (Macalister. ) 

The  left  auricle  is  placed  hehind  the  roots  ui  the  aorta  and  pulmonary  artery, 
with  the  right  auricle  overlapping  it,  and  lying  to  the  right  of  these  structures. 
Behind,  it  receives  on  each  side  the  pulmonary  veins,  and  it  is  separated  Ijy  the 
pericardium  from  the  oesophagus  and  the  descending  thoracic  aorta.  Its  narrow 
and  much  curved  appendix  arches  round  the  root  of  the  pulmonary  arter}',  and  is 
the  only  part  of  the  auricle  to  be  seen  from  the  front.  The  cavity  of  the  auricle 
is  smooth,  with  the  exception  of  the  api^endix,  in  which  the  musculi  pectinati  are 
well  marker  1. 

Openings. — Besides  the  narrow  opening  which  leads  from  the  atrium  into  tin- 
appendix,  the  left  auricle  presents  posteriorly  the  orifices  of  the  four  pulmonary 
veins,  two  of  which  sometimes  have  a  single  mouth,  whilst  ;i  third  may  l)e])resent, 
especially  on  the  right  side.  The  oval  auriculo-ventricular  opening  is  placed 
below  and  in  front.  Several  small  orifices,  the  foramina  Thebesii,  are  also  to  be 
found  in  the  cavity.  A  crescentic  indentation  on  the  sei>tal  wall,  with  its  con- 
cavity upwards  and  placed  above  the  level  of  the  annulus  ovalis,  indicates  the 
upper  border  of  the  valve,  which  has  grown  upwards  to  obliterate  the  foramen 
ovale,   but  which  now  is  adherent  and  forms  part  of  the  wall  dividing  the  two 


Fig.  552. — Vikw  of  the  Aurtcul.vr  C.avitiks  from  below  (the  Transverse  Section 

PA.SSIXG    above   their    MIDDLE). 


^^=-^.: 


^"         ■  Orifice  of  supe- 


rior reiiii  ciirii 


Musculi 
pectiuati 


<^     V  ^^   \,     '■    Vf     pectinat 


■  "-^fV-  •'         Ri'jilt  auricular 
a]>peniiii 


auricles.  As  already  ol)served,  a  small  obli(iue  oritiee  sometimes  remains  un- 
closed. 

The  left  ventricle  forms  the  chief  jjart  of  the  heart  behind,  with  its  ajiex  and 
left  border.  It  is  somewhat  longer  and  narrower  than  the  right.  Its  cavity  is 
conical  with  the  apex  below  and  it  is  somewhat  ovoid  in  transverse  section.  Its 
muscular  wall,  which  is  much  thicker  than  that  of  the  right  ventricle,  is  thinnest 
at  the  apex  and  thickest  at  the  junction  of  the  uj)per  and  middle  thirds. 

The  columnae  carneae  are  numerous,  small,  and  closely  reticulated,  giving  to 
the  interior  of  the  ventricle,  especially  near  the  apex,  a  cavernous  appearance. 

The  musculi  papillares  are  usually  represented  by  two  large,  sometimes  com- 
pound, muscular  ])illars,  which  arise  from  the  nnterior  and  the  posterior  wall 
respectively;  and  from  tliese  tlie  chordse  tendineae  pass  to  the  edges  and  surfaces 
of  the  two  segments  of  the  Ijicusjnd  valve. 

The  orifice  of  the  aorta  looks  somewhat  forwards,  and  is  guarded  V)y  three 
semilunar  valves,  which  are  sifnilar  in  structure,  but  present  more  strongly 
marked  i-haracters  than  are  to  l)e  found  in  the  corresi)onding  valves  of  the  pulmo- 
nary artery.  One  of  these  segments  is  placed  anteriorly  and  two  lie  posteriorly. 
It  is  surrounded  by  a  fil)rous  ring,  similar  to  that  which  strengtliens  the  i»ulmonary 
orifice,  and  the  walls  of  that  ])ortion  of  the  cavity  which  lies  immediately  below  it, 
the  aortic  vestibule,  are  entirely  fibrous. 


934 


THE   ORGAXS   OF  CIRCVLATION 


The  auriculo- ventricular  opening  is  unaixUd  by  the  bicuspid  valve.  Its  two 
une<iual  se<rinents  are  larirer  and  thicker  than  those  on  the  rij^ht  side  of  the  lieart, 
thousjh  the^oriliee  itself  is  somewhat  smaller,  and  they  are  similarly  separated  by 
smaller  lobes  or  cusps.  Of  the  two  segments,  the  one,  which  is  the  larger  and  the 
more  free  and  smooth,  is  i)laced  in  front  and  to  the  right  l)etAveen  the  two  open- 
int^s,  whilst  the  other  lies  behind  and  to  tlie  left.  The  fibrous  ring  surrounding  the 
orifice  serves  to  give  attachment  to  muscular  fibres  as  Avrll  as  to  the  valves.  By  its 
right  border  it  is  tied  to  tlie  aortic  ring  by  fibrous  tissue,  which  also  extends  to  the 

Fig.  553.— Postbrior  View  of  the  Left  Chambers  of  the  Heart,  with  the  Great 
Vessels  and  the  Coronary  Sinus  laid  open. 


Left  carol  ill 


Left  mhclmian 


LEFT  AURICULAR  APPENDIX 


INTERIOR  OF  LEFT  AURICLE  - 


Great  cardiac  rein 


Vulres  of  great  canliac 
vein 


ANTERIOR 
SEGMENT  OF 
MITRAL  VALVE 


Innontinate 


Ductus  urtf-rioius 


Commencement  of  left 
pulmonary 


Left  jiulnionari/  reins 


CONCAVE  EDGE  OF  THE  VALVE 
OF  THE  FORAMEN  OVALE 


Rifjlil  ptilmonai-y 

reins 
Left   auriculu-rentri- 

culiir  open  in  </ 
Valved  orifice  of  rein 

in  coronary  sinus 
Coronary  sinus 

Valve  if  T/iebesius 
I  en«  lara  inferior 


POSTERIOR  SEGMENT  OF  MITRAL 
VALVE 

CHORD/E  TENDINE/E 

Compound  posterior  papil- 
lary muscles 


FINE    MESH- 
WORK  OF 
COLUMN/t 
CARNE/E 
AT  APEX  OF 
VENTRICLE 


Coronary  artery 


SECTION  THROUGH  VALL  OF  LEFT 
VENTRICLE 


COLUMN/E  CARNE/E 


ring  surroun(Hng  tlic  tricus])id  valve.  In  the  angular  space  thus  bound(Ml  there  is 
imljedded  a  fibro-cartilagc,  whicli  in  somcMuammals  is  represent(Hl  by  a  l^oiie  wliich 
is  known  as  the  os  cordis. 

The  interventricular  .^eptum  whicli  separates  the  cavities  of  the  ventricles  is 
thickest  beloAV.  In  the  greater  part  of  its  extent  it  consists  of  muscular  tissue,  but 
its  upper  portion,  which  intervenes  not  only  betw^een  the  two  ventncl(>s  Init  also 
between  the  left  ventricle  and  right  auricle,  is  a  fibrous  septum  devoid  of  nmscle- 
fibres. 


THE  HEART 


985 


The  Position  of  the  Chief  Ohifices  one  to  the  othkr  and 
TO  THE  Chest  Wall 

The  pulmonary  orifice  is  })la((Ml  in  front  of,  and  to  the  k-ft  of  tlie  ri«.dit  auriculo- 
vcntri(*ul;ir  ()[>(nin^,  whilst  tiu-  aortic  orifice  is  in  front  of,  and  to  the  right  of  the 
h'ft  uuiiculo-ventricular  o})ening.  The  rehition  of  the  valved  orifices  to  the  chest 
wall  can  only  1)C  a])i)roxiniately  determined  (Fig.  547). 

The  pulmonary  semilunar  valves,  wliich  are  anterior  in  position  to  the  aortic, 
are  placed  l)ehind  the  junction  of  the  third  rib  with  tlie  sternimi  on  the  left  side. 

Fig.  554.— Showing  the  Position  of  the  Heart  and  its  Valves  in  Relation  to  the 

Chest  Walls. 

(Reduced  from  Hensman  and  Fisher's  Anatomical  Outlines.) 

(The  right  auricle  ami  ventricle,  with  the  pulmonary  semilunar  and  tricusipid  valves,  are  outlined  in  blue  tints; 
whilst  the  left  auricle  and  ventricle,  with  their  corresponding  valves,  are  indicated  in  red.) 


The  aortic  semilunar  valves,  more  deeply  placed,  correspond  to  the  third 
space,  close  to  the  sternum. 

The  tricuspid  valve  is  situated  Inhind  the  strrnum  m-ar  the  middle  line,  ahout 
the  level  of  the  fourth  s))ace. 

The  mitral  valve  lies  deeply  behind  the  sternum  o})posite  the  fourth  cartilage 
(  Fig.  547  ). 

The  muscular  walls  of  the  heart  vary  very  much  in  thickness,  and  tlie  fotal 
differs  from  the  adult  heart  in  the  relative  muscularity  of  its  chambers. 

The  right  auricle  is  thinner  than  the  left,  the  right  measuring  about  one-twelfth 
of  an  inch,  and  the  left  abf)Ut  one-eighth  of  an  inch  in  thickness.      The  right  ven- 


936 


THE   OR(;AyS   OF  rTRC'T'LATlOX 


tricular  wall  in  the  adult  is  nmch  thinner  than  the  left,  being  thickest  at  the  base, 
and  thinnest  at  the  apex. 

The  left  ventricular  wall  is  about  double  the  thickness  of  the  right;  and  it  is 
thickest  where  the  ventricle  is  broadest,  being  thinner  both  at  its  base  and  apex. 

The  Vessels  and  Nerves 

The  arteries. — The  two  coronary  arteries,  right  and  left,  arise,  the  right  from 
the  anterior,  and  the  left  from  the  left  posterior  sinus  of  Valsalva  just  above  the 
free  borders  of  the  right,  and  of  the  left  posterior  semilunar  valves. 

The  right  coronary  artery  ])asses  fonvards  between  the  pulmonary  artery  and 
tlu^  right  auricular  ajtjxndix.  and  then  winds  to  the  right  border  of  the  heart,  around 
whiili  it  turns  to  gain  its  po.sterior  surface.     In  this  course  it  lies  in  the  aurifulo- 


FiG.  5r)5. — Anteeior  View  of  the  Heart,  showing  its  Arteries  and  Veins. 


Innomiiiati' 


Right  jiulinoriari/  vein 


RIGHT  AURICLE 
RIGHT  AURICLE  APPENDIX 

liiffht  loronary 

Btanrh  lo  anterior  wall 
of  right  ventricle  (pre- 
venlricn/or) 

Riff/it  inarginnl  artery 
and  vein  {rein  of  Galen) 


Lfft  carotid 
Lej'l  snbclarian 


Lfft  jjiilnioiiiiri/  vein 


LEFT  AURICULAR  .WENDIX 


Left  DKirginal  artery 


A  nlerior  interrenlricnlar 
lirunch  of  the  great  cnr- 
•tiac  vein 


[.■ft  coronary  (interven- 
tricular) 


'iininteucing  radicles  of 
posterior  interventric- 
ular vein 


ventricular  groove.  At  the  commencement  of  the  posterior  interventricular  groove 
it  divides  into  its  two  main  branches,  one  of  which,  still  i>assing  onwards  in  the 
auiiculo-ventricular  groove,  anastomoses  with  the  left  coronary,  whilst  the  other 
( interventricularj  descends  in  the  furrow  between  the  ventricles  towards  the 
apex,  near  whicli  it  anastomoses  with  branches  derived  from  the  left  coronary 
artery  which  have  reached  the  posterior  surfa(;e  of  the  heart  after  passing  around 
its  apex.  In  this  course  the  right  coronary  artery  sup])lies  branches  to  the  riglit 
auricle  (  auricular  j  and  roots  of  the  pulmonary  artery  and  aorta,  as  well  as  one 
that  descends  near  the  right  border  of  the  heart  (right  marginal),  and  a  second 
(preventricular)  to  the  anterior  Avail  of  the  right  ventrick-.  It  supplies  both 
ventricles  and  the  septum. 

The  left  coronary  artery  passes  for  a  short  distance  forwards,  between  the 
pulmonary  artery  and  tliu  left  auricular  a{)pendix,  and  then  divides  into  two  prin- 
cipal branches,  one  of  whicli  descends  in  the  interventricular  groove  to  the  apex  of 


THE  HE  ART 


937 


the  heart  (interventricular),  around  wliieh  it  sends  branches  to  anastomose  with 
the  right  coronary;  whilst  the  other  winds  to  the  back  of  the  heart  in  the  auricul(j- 
ventricular  groove,  to  anastomose  after  division  with  the  corresi)onding  twigs  of 
the  right  artery.  In  this  course  it  gives  off  a  branch  which  descends  near  the  left 
border  of  the  heart  (left  marginal),  as  well  as  smaller  branches  to  the  left  auricle, 
both  ventricles,  and  the  cDiiniicncement  of  the  aorta  and  pulmonary  vessels. 

The  cardiac  oi-  coronary  veins  accompany  the  coronary  arteries  and  return 
the  blood  from  the  walls  ol'  tht;  heart. 

The  (so-called)  great  cardiac  vein  ascH'uds  in  the  anterior  interventricular  sul- 
cus, ])assing  round  tlu'  left  side  of  the  heart  to  its  posterior  surface  in  the  auriculo- 
ventrieular  groove  to  terndnate  in  the  commencement  of  the  coronary  sinus.  Its 
mouth   is  usually  guarded  bv  two  valves,    and   it  receives  in  its  course  the  left 


Fig.  556. — Posterior  View  of  the  He.\rt,  showing  its  Arteries  and  Veins. 

liiyhl  caiidid  aitefy 

Left  carotid  artery 
Left  subclarUiii  iirleri/ 


Aorta  - 
Ductus  arteriosus 

Pulriionary  artery 
LeJ'l  imlmonary  veins 
LEFT  AURICLE 
Left  coroitarij  artery 
Left  marginal  artery  - 
Oblique  rein  of  Marshall 
Left  marginal  vein  ' 
PERICARDIUM  ^ 
Coronary  sinus  _ 

Posterior  cariliav  I  • 


A  nterior  interventricular 
brancli  of  left  coronary 


lunoniinute  artery 


Vena  cava  sui>eriur 
Hiylit  jjuhiKiiuny  vHus 


-    RIGHT  AURICLE 


\'eiia  cava  iuferior 

I'iylit  coronary  artery 
Posterior  iulerventriculur  rein 


I'usterior  interventricular  liranch 
of  right  coronary 


marginal  vein,  with  other  smaller  veins  from  the  left  aiiriek'  (the  left  auricular) 
and  ventricle,  all  of  which  are  guarded   by  valves. 

The  posterior  cardiac  vein  (posterior  interventricular ),  sometimes  the  larger 
of  the  two  chief  veins,  connnunicates  with  the  foregoing  at  its  commencement  on  the 
anterior  surface  above  the  heart's  apex.  It  ascends  in  the  })osterior  interventricular 
groove,  receiving  blood  from  the  ventrieidar  walls,  and  joins  the  coronary  sinus, 
tbi'ougb  an  orifice  guarile<l  by  a  single  valve,  close  to  its  termination. 

The  anterior  cardiac  veins  (  preventricular )  consist  of  several  small  br.inebes 
from  the  front  of  tlie  right  ventric-le,  wliieh  o])en  separately  into  the  riLdit  aurieli-, 
or  into  the  right  auricular  vein;  and  a  right  marginal  vein  (  vein  of  Galen  ),  which 
joins  the  coronary  sinus  near  its  termination,  or  opens  separately  into  the  lower 
part  of  the  right  auricle  (Figs.  549,  555). 

The  coronary  sinus  may  lie  regarded  as  a  much  dilated  terminal  portion  of  the 
great  cardiac  vein.      It  is  about  an  inch  in  length,  covered  by  muscular  lil)res  from 


9o8 


THE   ORGANS   OF  CIRCULATION 


Fig.  557. — Anterior  View  of  a  Fcetus.     The  Heart,  Vessels,  anp  Chief  Organs 
displayed,  with  the  placenta  and  umbilical  cord. 


THE   F(KTAL    JIEAUr  93*J 

the  auricle;  and  lies  in  the  auriculo-ventricular  groove  on  the  posterior  surfaee  of 
the  heart.  Its  cardiac  orifice  with  the  coronary  (Thebesian)  valve  has  already  l)een 
described.  Besides  tlie  tributary  veins  already  named,  a  small  oblique  vein  of 
Marshall  may  sometimes  l)e  traced  from  the  vestifrialfold  to  the  sinus.  This  little 
vein,  wliicli  is  not  always  pervious  or  easy  of  demonstration,  never  i)ossesses  a  valve 
at  its  orifice,  anil  like  the  coronary  sinus  formed  a  part  of  the  left  su]K'rior  vena 
cava  of  early  f(otal  life.  The  sinus  also  receives  the  jiosterior  interventricular  vein, 
one  or  more  rigbt  auricular  branches,  and  several  post-ventricular  veins  from  tlie 
back  of  the  left  ventricle. 

The  cardiac  nerves  descend  into  the  su})erior  mediastinum,  passing  in  front  of 
and  behind  the  arch  of  tlie  aorta,  to  unite  in  the  formation  of  the  superficial  and 
deep  cardiac  plexuses. 

The  deep  cardiac  plexus,  the  larger  and  more  important,  is  placed  immecliately 
above  the  ])ulmonarv  artery  at  its  jioint  of  division,  lying  between  the  trachea  and 
arch  of  tlu^  aorta.  It  is  usually  tormed  by  the  interlacement  of  all  the  cardiac 
branches,  with  the  excei)tion  of  the  left  sui)erior  cardiac  branch  from  the  sym- 
pathetic and  the  left  inferior  cardiac  from  the  pneumogastric. 

A  mesh  work  of  branches  descends  from  the  plexus,  some  passing  to  the  riglit 
and  some  to  the  left.  The  greater  number  of  the  right  l>ranches  follow  the  course 
of  the  right  coronary  artery  to  form  the  right  coronar}'  plexus;  some,  however, 
pass  forwards  to  enter  the  superficial  cardiac  plexus. 

The  left  branches,  which  are  both  larger  and  more  numerous,  descend  beneath 
tlie  corresponding  pulmonary  artery  to  join  the  left  coronary  plexus;  some  of  these 
pass  right  and  left  to  join  thf  anterior  pulmonary  plexuses  at  the  roots  of  the  lungs. 

The  superficial  cardiac  plexus,  which  lies  in  front  of  the  right  pulmonary 
artery  as  it  passes  beneath  the  arch  of  the  aorta,  is  formed  Ijy  the  interlacement  of 
the  left  superficial  cardiac  l>ranch  from  the  sympathetic,  the  inferior  cardiac  from 
the  pneumogastric,  togctlicr  with  branches  derived  from  the  deep  plexus.  A  small 
ganglion,  the  cardiac  ganglion  of  Wrisberg,  is  sometimes  found  close  to  the  right 
side  of  the  ductus  arteriosus.  The  greater  numl)er  of  the  filaments  from  this  plexus 
go  to  the  right  coronary  jjIcxus.  Some,  however,  reach  the  left  anterior  pulmonary 
plexus. 

The  coronary  plexuses  follow  the  course  of  the  vessels,  and  their  filaments 
enter  the  muscular  walls  of  tlie  lieart.  Minute  ganglia  are  connected  with  these 
filaments,  and  are  especially  abundant  near  the  auriculo-ventricular  groove. 

Peculiakitiks  of  the  F<etal  Heai!T 

The  foetal  heart  is  at  first  almost  vertical  in  position,  but  during  the  latter  half 

of  intra-uterine  life  it  gradually  assumes  the  ol)li(jue  i)osition  it  retains  in  the  adult. 

Its  weight   in   relation  to  the  body  varies  consi<lerab]y.      Thus  at   the  second 

The  black  connecting  arrows  indicuto  the  course  of  the  circulation  through  the  head  and 
neck,  the  upper  extremities,  the  lungs,  the  liver,  ami  the  lower  extremities. 

The  red  arrows  ^linw  tlie  ilircctinu  nf  the  ciUTeiit  from  the  placenta,  tlir(iai:li  tlir  umbilical 
vein,  ductus  venosus  (D.  V.)  ami  liver,  to  the  uplter  portion  of  the  inferior  vena  cava. 

The  red  arrows  with  the  blue  tails  and  the  dotted  line  show  the  (•(lursf  of  the  impure 
blood,  as  it  cntfis  the  right  auricle  through  tlie  inferior  vena  cava,  and  traverses  the  foramen 
ovale,  iruided  by  the  Eustachian  valve,  to  gain  the  left  auricle,  left  ventricle,  ;nid  aorta,  to  lie 
(Hstributed  by  its  eluef  branches  to  the  head  and  neck  and  upper  extremities. 

T'.ie  blue  arrows  are  placed  on  the  superior  and  inferior  venae  cavae.  and  .<ome  oi'  their  main 
tributary  trunks. 

The  stream  derived  from  the  superior  cava  passes  through  the  right  auricle  — in  front  of  that 
already  described — to  reach  tlu'  right  ventricle  ;  thence  it  passes  into  tiie  pulmonary  artery  (a 
small  portion  oidy  reaching  the  lungs  through  tlie  right  and  left  pulmonary  luanclio).  ductus 
arteriosus,  and  descending  aorta. 

The  stn-am  derivcil  from  tlie  inferior  cava  mixes  witli  the  blood  of  tlie  umbilical  vein,  and 
that  which  lias  passed  through  the  liver,  beyond  the  junction  of  the  ihictus  venosus  and  hei»atic 
veins. 

The  blue  arrows  with  the  red  heads  show  tlie  coui"se  of  the  blood  throui:li  the  descending 
aorta  to  the  lower  extremities,  and  tlirouLdi  tiie  umbilical  arteries  to  the  i>laci;nta. 

The  colours  of  the  arrows  roughly  indicate  the  proportion  of  pure  and  impure  blood  to  the 
different  parts  of  the  circulation. 


940 


THE   ORGANS   OF  CIRCULATIOX 


month  it  is  about  1  to  50;  at  l)irtli  it  is  1  to  120;  whilst  in  the  aduU  it  is  about 
1  to  160. 

Tlie  auricular  portion  is  at  first  more  cai)acious  than  the  ventricular,  and  the 
right  auricle  is  larger  than  the  left.  The  ventricular  walls  are  at  first  about 
equal  in  thickness,  l)ut  at  birtli  the  left  wall  is  the  thicker  of  the  two. 

The  foramen  ovale  is  largest  about  the  sixth  month  of  intra-uterine  life,  and 
there  is  \\\)  to  this  })criod  a  direct  communication  between  the  two  auricles.  The 
valve  of  the  foramen  ovale,  however,  gradually  advancing  upwards  bej'ond  the 
annulus,  on  its  left  side,  acts  as  a  perfect  valve  during  the  latter  half  of  foetal  life, 
and  thus  prevents  the  return  of  blood  into  the  right  auricle. 

The  Eustachian  valve  has  already  been  described;  it  is  of  large  size  in  the  foetal 


Fig.  558.— Anterior  View  of  Heart  and  Great  Vessels  of  Fcetus,  the  Anterior 
Chest  Wall  beixc;  removed  axd  the  Heart  Sac  opened. 


Lffl  Left 

caivlid         si'Uluiiini         SECTION  OF  CLAVICLE 


Duclus  arleriosiis 
Aoita 


Pulmonary  artery 


PERICARDIUM 
REFLECTED 


RIGHT  AURICLE 


fV  LEFT  VENTRICLE  LEFT  AURICULAR 


CUT  EDGE  OF 
PERICARDIUM 


UPFtR  SURFACE  RIGHT   AURICULAH        RIGHT 

OF  DIAPHRAGM  APPENDIX  VENTkICLE 


lieart,  and  serves  to  direct  the  current  of  blood  from  the  inferior  cava  into  the  left 
auricle. 

The  ductus  arteriosus  continues  the  i)ulmonarv  artery  onwards  to  the  concavity 
of  the  arch  of  the  aorta,  to  a  ])oint  just  beyond  the  origin  of  the  left  subclavian 
artery,  and  so  transmits  the  l)lood  from  the  right  ventricle  into  the  descending 
aorta.  The  ductus  arteriosus  during  the  growth  of  the  ]nilmonarv  artery  becomes 
ultimately  associated  with  its  left  branch. 

The  foetal  circulation. — The  right  auricle  of  the  heart  receives  its  blood  from 
both  vense  cavie,  as  well  as  from  the  coronary  sinus.  That  which  is  conveyed  by 
the  superior  cava  is  venous  l)lood  returned  from  the  head  and  neck  and  upper 
extremities.  The  inferior  cava  returns  the  blood  from  the  lower  half  of  the  body, 
as  well  as  that  which  comes  from  the  i)lac<'nta  througli  the  umbilical  vein.  This 
latter  stream  nniclies  the  inferior  cava,  in  })art  directly  through  the  ductus  venosus, 
and  in  part  through  the  liver  and  hepatic  veins. 


THE   FiKTAL   HEART  <)41 

Tlic  Itlood  t)f  the  superior  vena  cava  passes  from  the  riglit  aurich-  into  the  rijrht 
ventricle,  and  thence  through  the  jiuhnonary  artery  (a  small  ])ortion  only  reaching 
the  lungs)  and  ductus  arteriosus  to  the  descending  aorta.  Througli  tliis  trunk  it 
is  conducted  to  the  lower  lialf  of  the  hody  as  well  as  to  the  jilacenta  through  the 
uml)ilical  arteries.  From  thesi>  parts  it  is  returned  to  the  right  auricle  Ity  the 
inferior  cava,  which  also  receives  the  l^lood  returning  from  tlu'  i)lacenta  as  alrcadv 
descrihed. 

The  current  which  passes  through  the  inferior  cava  only  in  a  slight  degree 
mingles  with  that  of  the  superior  cava,  as  it  is  guided  directly  through  the  foramen 
ovale  by  means  of  the  Eustachian  valve  into  the  left  auricle.  This  cavity  also 
receives  a  small  quantity  of  blood  (which  has  traversed  the  lungs)  through  the 
pulmonary  veins.  From  the  left  auricle  the  blood  current  passes  into  the  left 
ventricle,  and  thence  through  the  aorta  to  the  head  and  neck  and  the  upper 
extremities. 


SECTION    YIII 

THE  ORGANS  OF  DIGESTION 


THE  ORGANS  ABOVE  THE  DIAPHRAGM 

Bv  ARTHUR  HENSMAX,  F.R.C.S. 

RKVI?:KI)   FOK    second    KDITION     1(Y    ARTHUR    ROBINSON,    M.D.,     M.R.C.S.,    LECTURER    ON     ANATOMY    IN     THE    MIDDF-ESEX 
IIOSPITAI,    MEDICAL  SCHOOL;   EXAMINER   IN   ANATOMY   FOR   THE   CONJOINT   BOARD   OF    ENGLAND 


T' 


THE    MOUTH 

iHE  mouth  is  the  cavity  at  the  commencement  of  the  alimentary  canal  ■svhich 
j        contains  the  organs  of  taste  and  mastication  and  the  greater  part  of  those  of 
speech.     It  comnmnicates  with  the  exterior  through  a  transverse  orifice  (the 
buccal  orifice)  and  with  the  pharynx  through  the  fauces. 

It  is  bounded  anteriorly  and  laterally  by  the  teeth  and  alveolar  arches;  external 
to  which  is  a  second  cavity,  often  described  as  the  vestibule  of  the  mouth,  which 
is  enclosed  by  the  lips  and  cheeks.  Its  roof  is  formed  by  the  hard  palate,  its  floor 
by  the  tongue,  with  the  nuicous  membrane  re-flected  from  it  to  the  inner  surface  of 
the  gums  over  the  sublingual  glands  and  the  A^'hartonian  ducts;  and  posteriorly  it 
opens  into  the  fauces.  It  is  lined  by  mucous  membrane,  which  is  continuous  with 
that  of  the  pharynx,  and  at  the  outer  margin  of  the  lips  it  is  continuous  with  the  skin. 

The  buccal  orifice  is  a  horizontal  slit,  the  extremities  or  "  angles  "  of  which  are 
ojiposite  the  first  bicusj^id  teeth.  The  orifice  is  bounded  by  the  upper  and  lower 
lips,  of  Avhich  the  former  is  distinguished  by  a  median  tubercle,  the  remains  of  the 
free  extremity  of  the  fronto-nasal  process.  The  lips  are  covered  b}'  a  dry  mucous 
membrane,  bright  red  in  color,  and  extremely  sensitive,  containing  large  numbers 
of  vascular  papillae,  in  many  of  which  are  nerve-terminations  resembling  touch- 
corpuscles.  Near  to  the  junction  of  the  skin  and  mucous  membrane  are  numerous 
sebaceous  follicles,  but  these  are  devoid  of  haii'-bulbs. 

The  substance  of  the  lips  consists  of  the  orbicularis  oris  and  a  quantity  of 
areolar  tissue  in  which  are  eml^edded  the  coronary  vessels,  lymphatics,  and  small 
l»ranclH's  of  the  infraorbital  and  mental  nerves.  Around  the  orifice  of  the  mouth 
on  its  inner  aspect,  and  })laced  beneath  the  mucous  membrane,  are  a  number  of 
small  lobulated  glands  known  as  the  "labial  glands." 

The  cheeks  consist  of  the  buccinator  muscle,  covered  externally,  first  by  a 
stratum  of  sul)cutaneous  fat,  then  by  the  dermal  muscles,  zygomatici  and  risorius, 
and  lastly  by  the  skin.  They  are  lined  with  mucous  membrane,  which  contains 
numerous  buccal  glands  similar  to,  but  smaller  than,  the  labial  glands.  Between 
the  integument  and  the  buccinator,  in  each  cheek,  besides  vessels  and  nerves  there 
are  several  glands,  the  molar  glands,  whose  ducts  pierce  the  Ijuccinator  and  open 
in  the  vestibule  opposite  tlie  last  molar  teeth,  and  a  large  quantity  of  fat,  which 
gives  rotundity  to  the  features,  and  constitutes  what  is  sometimes  spoken  of  as  the 
sucking  cushion  of  the  cheek.  Opposite  the  second  upper  molar  tootli  is  a  papilla 
which  marks  the  opening  of  the  duct  of  the  parotid  gland. 

The  gums  are  formed  by  a  layer  of  tough  areolar  tissue  covering  the  alveolar 
processes,  and  firmly  attached  to  their  periosteum. 

They  are  covered  on  l)oth  aspects  l)y  the  mucous  membrane  of  the  mouth,  the 
iimer  surfaces  receiving  reflexions  from  the  sides  and  anterior  extremity  of  the 
tongue,  a  median  fold  forming  the  frffiuum  of  that  organ;  and  the  outer  surfaces 
receiving  reflexions  from'tlie  cheeks  and  lips.  In  the  median  line  alcove  and  below 
the  orifice  of  tlie  mouth  are  folds  of  mucous  membrane,  forming  the  fraena  laljiorum, 
of  whicli  the  upper  is  the  more  marked. 

042 


THE  PALATE 


•.>43 


THE  PALATE 

The  palate  consists  of  two  portions,  the  anterior  or  hard  })ahite,  and  tlie  ])<).st>- 
rior  or  soft  palate. 

The  hard  palate,  which  is  Hmited  in  front  and  laterally  by  tlie  alveolur 
I>roeesses,  ends  posteriorly  in  a  free  border  to  wliieh  the  soft  palate  is  attached. 

The  mucons  membrane  which  covers  it  is  corru<jrated,  thick  and  somewhat  pale, 
and  is  linnly  bound  down  to  its  periosteum.      In  the  median  line  of  the  palate  is  a 


Fig.  558a. — Palato-glossus  Muscle,  seen   from  thp:   Moith,  with   Section  of  Base  ok 

ToX(JlE. 


Palato-glossus 


Genio-hyoglossua 


ridge  called  the  raphe;  at  tiic  anterior  extremity  of  tiiis  is  a  small  ])ai)illa  which 
marks  the  inferior  opening  of  the  anterior  palatme  canal,  and  extending  from  its 
sides,  anteriorly,  are  five  or  six  transverse  ridges.  The  mucous  rneml^rane  cover- 
ing the  hard  palate  receives  its  nerve-supply  from  the  anterior  palatine  and  naso- 
palatine nerves. 

The  SOFT  PALATE  (fig.  560)  is  attached  to  the  posterior  border  of  the  hard 
palate,  of  which  it  forms  a  backward  prolongation  hanging  down  at  the  back  of  the 
mouth,  and  thus  partially  separating  the  latter  cavity  from  the  })harynx.  Its  si<les 
are  merged  in  the  })harvngeal  wall,  and  its  lower  l)order  is  free. 

From  the  centre  of  this  border  a  somewhat  conical  process,  the  uvula,  de]->ends, 
and  from  tlie  base  of  this  two  folds  of  mncous  memln'ane  on  each  side  extend  in  ;in 
outward  and  downwaid  direction,  receiving  the  name  of  the  pillars  of  the  fauces. 

The  anterior  pillar  is  formed  ])rinci})ally  l)y  the  jialato-glossus  muscle,  and 
its  directi(ni  is  downwards,  outwards,  and  forwards  to  the  side  of  the  base  of  tlie 
tongue. 

The  posterior  pillar  is  formed  principally  i>y  the  palato-pharyngeus.  It 
a]>proaclie.<  nioie  nenrly  to  its  fellow  of  the  opposite  side  than  does  tlie  anterior. 
Its  direction  is  outwards,  downwards,  and  backwnrds.  and  tliere  thus  exists  lietween 
it  and  the  anterior  pillar  a  triangular  space,  the  tonsillar  recess. 

The  space  l)etween  the  anterior  pillars  is  known  as  tlie  isthmus  of  the  fauces, 
and  forms  the  buccal  opening  of  the  ]»harynx.  It  is  bounded  below  by  the  tnnguf. 
above  1)V  the  soft  palate,  and  laterally  by  the  pillars  of  the  fauces. 

The  anterior  surface  of  the  soft  palate  is  concave,  directed  forwards  an<l 
downwards,   and   is    continuous  with    the   lower   surface  of   the  hard  palate;    its 


944  THE  ORGANS  OF  DIGESTIOX 

posterior  surface,  which  is  convex,  is  a  coiitiimation  of  tlic  floor  of  the  nasal 
cavity,  and  it  forms  a  part  of  the  anterior  wall  of  tiie  pharynx. 

Structure. — The  soft  palate  is  a  fold  of  mucous  meni])rane  enclosing  an 
aponeurosis,  muscles,  vessels,  and  nerves.  It  is  marked  in  the  middle  line  b}'  a 
ra]ihe  indicating  the  line  of  junction  of  the  two  halves  from  which  it  was  formed. 

The  posterior  layer  of  the  mucous  fold  which  is  directed  towards  the  cavity  of 
the  pharynx  is  continuous  with  the  nasal  niucous  membrane;  the  anterior  layer 
lies  in  the  posterior  l)oundary  of  the  mouth  and  is  continuous  with  the  mucous 
membrane  of  the  hard  ])alate;  the  lower  margin  is  free.  Glands  are  numerous  in 
both  layers,  but  more  especially  in  the  anterior. 

The  ajioneurosis  is  attached  above  to  the  posterior  margin  of  the  hard  ]ialate; 
laterally  it  is  continuous  with  the  aponeurotic  layer  of  the  pharyngeal  wall;  below, 
towards  the  lower  margin  of  the  soft  palate,  it  gradually  disappears,  and  it  gives 
attachment  to  fibres  of  the  levator  palati  and  the  palato-pharyngeus  and  to  the 
tendon  of  the  tensor  palati. 

The  muscles  are  arranged  in  layers  either  Ijehind  or  in  front  of  the-aponeurosis, 
and  in  a  horizontal  section  of  the  soft  palate  the  following  layers  are  met  with  from 
behind  forwards:  (1)  The  mucous  membrane  on  the  pharyngeal  surface  ;  (2)  the 
posterior  layer  of  palato-pharyngeus  fibres  ;  (3)  the  azygos  uvulae  ;  (4)  the  levator 
palati  ;  (o)  the  anterior  layer  of  ]ialato-]-)harvngeus  fibres  ;  (6)  the  palatal  aponeuro- 
sis with  the  tensor  palati  ;  (7)  the  palato-glossus  ;  and  (8)  the  mucous  membrane 
on  the  buccal  aspect. 

The  Palato-Glossus  is  described  on  page  453. 

The  Palato-Pharyngeus — named  from  its  attachments — is  a  thin  sheet. 

Origin. — (1  j  From  the  aponeurosis  of  the  soft  palate  by  two  heads  which  are 
separated  by  the  insertion  of  the  levator  palati;  (2)  one  or  two  narrow  bundles 
from  the  lower  part  of  the  cartilage  of  the  Eustachian  tube  {salpingo-'pharyngeus). 

Insertion. — (1)  By  a  narrow  fasciculus  into  the  posterior  border  of  the  thj^roid 
cartilage  near  the  base  of  the  superior  cornu;  (2)  b}^  a  broad  expansion  into  the 
fibrous  layer  of  the  pharynx  at  its  loAver  part. 

Structure. — The  upper  head  of  the  muscle  consists  of  scattered  fibres  which 
l)lend  with  the  opposite  muscle  across  the  middle  line;  the  lower  head  is  thicker, 
and  follows  the  curve  of  the  posterior  border  of  the  palate.  The  two  heads  with 
the  fasciculus  from  the  Eustachian  tube  form  a  compact  muscular  band  in  the 
posterior  pillar  of  the  fauces;  the  fibres  mingle  with  those  of  the  stylo-pharyngeus, 
at  the  lower  border  of  the  superior  constrictor,  and  then  expand  upon  the  lower 
part  of  the  pharynx. 

Nerve-supply. — From  the  pharyngeal  plexus. 

Action. — ( 1  )  Approximates  the  posterior  pillars  of  the  fauces;  (2)  depresses 
the  soft  palate;   (3)   elevates  the  pharynx. 

The  Levator  Palati — named  from  its  action  on  the  soft  palate — is  somewhat 
rounded  in  its  upper,  but  flattened  in  its  low^er  half. 

Origin. — (1)  The  under  surface  of  the  petrosal  anterior  to  the  orifice  of  the 
carotid  canal;  (2)  the  lower  margin  of  the  cartilage  of  the  Eustachian  tube. 

Insertion. — The  aponeurosis  of  the  soft  palate;  the  terminal  fibres  of  the 
muscles  of  each  side  meet  in  the  middle  line  in  front  of  the  azygos  uvulff. 

Structure. — Its  origin  is  l:)y  a  short  tendon;  the  muscle  then  becomes  fleshy, 
and  continues  so  to  its  insertion. 

Nerve-supply. — It  is  usual  to  describe  this  muscle  as  being  innervated  by  the 
facial  through  th(>  petrosal  l)ranch  of  the  Vidian.  The  nerve  is  supposed  to  reach 
the  muscle  through  the  small  i)alatine  nerve  from  Meckel's  ganglion.  Stimulation 
of  the  facial  trunk  within  the  skull  of  monkeys  produces  no  result  on  the  soft 
palate,  whereas  stimulation  of  the  eleventh  causes  elevation  of  the  soft  palate  on 
the  same  side.  The  motor  branch  probably  passes  to  the  palate  in  the  upper 
branches  of  the  pharyngeal  plexus  (Horsley  and  Beevor). 

Action. — (1)  To  raise  up  the  palate,  and  bring  it  in  contact  with  the  posterior 
wall  of  tlie  pharynx;  (2)  when  the  nmscle  contracts  it  presses  up  and  closes  the 
pharyngeal  orifice  of  the  'Eustachian  tul)e  (Cleland).  This  action  is  not  admitted 
by  many  anatomists. 


THE  PALATE 


945 


The  Tensor  Palati— nanicd  from  its  action  on  the  soft  palate— is  a  thin,  flat 
and  narrow  sheet.  '         ' 

Origin. — (1)  The  scaphoid  fossa  at  the  root  of  the  internal  pterygoid  plate; 
(2)  tlie  alar  spine  of  the  sphenoid;  (3)  the  outer  side  of  the  pharyngeal  extrem- 
ity of  th(>  Eustachian  tube. 

Insertion. — (  1  )  into  the  transverse  ridge  on  tlic  under  surface  of  the  horizontal 
plate  of  the  palate  bone;   (2;  the  aponeunjsis  of  the  soft  palate. 


Fig.  558b.— Vikw  of  Muscles  of  Soft  Palatk,  as  seen  from  withtx  riri-:  Pharynx. 

(Modified  from  Bourgerv. ) 


Pharyngeal 
aponeurosis 


Levator  palati 


Tensor  palati 


Azygos  uvulae 
Hamular  process 


Palato- 
pharyngeus 


Crico-arytenoideus 
posticus 


EUSTACHIAN  TUBE 
Levator  palati 


Palato-pharyngeuB 


-  Superior  constrictor 


Thyroid  cartilage 


_   Cricoid  cartilage 


(ESOPHAGUS 


Structure. — Its  l)elly  as  it  descends  bttwei-n  the  internal  jitervgoid  nuiscle  and 
the  internal  pterygoid  plate  is  muscular.  On  approaching  the  hamular  ])roee.<s  it 
becomes  tendinous,  and  continues  so  to  its  insertion.  A  ])ursais  interposed  between 
the  hamular  process  and  the  tendon.  The  belly  of  the  mu.^cle  is  at  nearly  a  right 
angle  with  its  tendon. 

Nerve-supply. — From  the  otic  ganglion  on  the  mandil)ular  divi.sion  of  the  liftli 
nerve. 

GO 


946  THE   ORGAXS   OF  DIGESTIOX 

Actions. — (1)  Tiiilitcns  t\\v  soft  })al:ite;  (2)  ojicnstho  Eustachian  tulx'  (luring 
deulutition. 

The  Azygos  Uvulae — named  bwause  it  was  supposed  to  1)0  a  sinjile  muscle. 

Origin.  —  (  1  )  From  the  aponeurosis  of  tlie  soft  i)alate;  (2)  the  nasal  spine  of 
the  palate  hone. 

Insertion. — Into  the  uvula. 

Structure. — The  muscle  consists  of  two  narrow  parallel  strips  lying  on  each 
side  of  the  middle  line  of  the  palate. 

Nerve-supply. — Probably  from  the  same  source  as  tlie  levator  ytalati. 

Action. — To  draw  U])  the  uvula. 

The  Mucous  Membrane  of  the  soft  palate  is  continuous  with  that  of  the 
mouth  on  its  anterior  aspect,  and  with  that  of  the  nasal  chamber  on  its  posterior 
surface;  its  epithelium  is  columnar  and  ciliated  in  the  vicinity  of  the  Eustachian 
tuI)o,  but  elsewhere  it  is  squamous  and  not  ciliated.  The  glands  form  an  espe- 
cially thick  layer  on  its  su])erior  aspect. 

Arterial  supply  of  the  soft  palate. — (1)  Ascending  palatine  of  facial;  (2) 
palatine  branch  of  ascending  pharyngeal;  (3)  twigs  from  descending  palatine  of 
internal  maxillary,  which  enter  the  smaller  palatine  canals,  and  are  distributed  to 
the  soft  palate  and  tonsils,  and  communicate  with  the  ascending  palatine  of  the 
facial  artery;   (4)  lingual  artery,  by  twigs  from  the  dorsal  branch. 

Nerves  to  the  soft  palate. — (1)  Branches  from  Meckel's  ganglion  ('small  or 
posterior  palatine'  and  'external  palatine  nerve');  (2)  tonsillitic  branches  of 
glosso-pharyngeal  nerve;  and  (3)  the  nerves  supplying  the  muscles. 

The  TONSILS  (figs.  507  and  oGO)  are  two  bodies  situated  one  in  each  of  the 
recesses  between  the  anterior  and  posterior  pillars  of  the  fauces  and  beneath  a  small 
fossa,  the  supra-tonsillar  recess,  which  is  the  remains  of  the  second  visceral  cleft. 
They  are  about  an  inch  (20-25  mm.)  in  length,  and  half  an  inch  (12-15  mm.)  in 
width  and  thickness;  but  their  size  is  liable  to  considerable  variation. 

On  their  inner  surfaces  are  a  number  of  puncture-like  openings  (twelve  to  fifteen 
on  each  tonsil),  which  form  the  orifices  of  small  recesses  or  crypts,  into  which 
numerous  follicles  open.  The  mucous  membrane  is  continued  into,  and  forms  a 
lining  for,  these  follicles;  their  walls  are  surrounded  by  an  aggregation  of  closed 
capsules  somewhat  similar  to  the  solitary  glands  of  the  intestine,  and  they  contain 
a  thick  secretion. 

The  tonsil  corresponds  in  jjosition  with  the  angle  of  the  jaw;  it  is  in  relation 
externally  with  the  superior  constrictor  muscle,  which  separates  it  from  the  ascend- 
ing pharyngeal  artery;  about  one  inch  externally  and  posteriorly  to  it  is  the  internal 
carotid  artery,  and  still  more  externally  the  internal  pter^-goid  muscle. 

Tlie  arteries  of  the  tonsil  are  five  in  number,  viz. : — (1)  Dorsalis  lingua3  from 
the  lingual;  (2)  ascending  pharyngeal  from  the  external  carotid;  (3)  ascending 
palatine  from  the  fa(;ial;  (4)  tonsillar  from  the  facial;  and  (5)  descending  2)alatine 
from  the  internal  maxillary. 

The  veins  of  the  tonsil  form  a  plexus  which  lies  upon  the  outer  side  of  the 
gland,  and  opens  externally  into  the  pharyngeal  plexus. 

The  lymphatics  of  the  tonsil  communicate  with  those  of  the  dorsum  of  the 
tongue,  and  they  pass  to  a  gland  which  lies  near"  the  angle  of  the  jaw. 

The  nerves  of  the  tonsil  are  branches  of  the  fifth  and  glosso-pharyngeal. 


THE  SALIVARY  GLA^^DS 

The  three  chief  salivary  glands  are  the  parotid,  the  submaxillary  (mandib- 
ular), and  the  sublingual.  These  all  pour  their  secretions  into  the  cavity  of  the 
mouth. 

The  PAROTID  GLAND  is  the  largest  of  the  salivary  glands.  It  lies  just  below 
and  in  front  of  the  ear,  and  it  varies  from  a  little  ox'cr  Jialf  an  ounce  to  an  ounce  in 
weight. 


THE  SALIVARY  GLANDS 


94' 


Its  superficial  surface  is  liniitcd  above  Ity  tin-  root  of  tlio  zygoma;  lu'liind,  l)v 
the  external  auditory  meatus,  the  mastoid  process,  and  the  sterno-mastoid  muscle 
with  the  posterior  belly  of  the  digastric;  anteriorly,  it  extends  for  a  varying  dis- 
tance over  the  masseter  muscle;  and  lielow,  it  is  liounded  Ity  a  line  passing  from 
the  angle  of  the  jaw  backwards. 

It  is  enclosed  in  an  aponeurotic  capsule.  The  eapsule  is  continuous  with  tin; 
deep  cervical  fascia  and  it  is  strengthened  at  the  lower  i)art  of  the  gland,  where  it 
extends  from  the  styloid  ])rocess  to  the  angle  of  the  jaw  as  the  stylo-maxillary 
ligament  Avhich  intervenes  between  the  i)arotid  and  submaxillary  glands.  Above 
ili<^  cai)sule  is  attached  to  the  lower  margin  of  the  tympanic  ])lat(M»f  the  temporal 
bone  and  to  the  posterior  l)ordcr  of  the  Glasserian  fissure. 

The  gland  is  somewhat  prismatic  in  form,  j)ossessing  three  borders  and  sin-faces 
and  two  extremities.  The  outer  surface  is  covered  by  fascia  and  skin  and  in  the 
lower  part  of  its  extent  by  platysma.  Embedded  in  it  are  several  superficial  lym- 
l)hatic  glands  which  receive  afferent  vessels  from  the  temple,  cheek,  eyebrows,  eye- 

Fio.  559. — The  Salivaky  Glands. 


PAROTID  GLAND 


Maaseter  muscle 


SOCIA  PAROTIDIS 


DUCT  OF  SOCIA 
PAROTIDIS 


DUCT  OF  PAROTID 


Bristle  inserted 
into  duct 


Fraenuiu  linguae 

DUCT  OF  RIVINUS 


SUBLINGUAL  GUNO 


DUCT  OF  SUBMAXILLARY 
GLAND 
Mylo-hyoid  muscle 


Anterior  belly  of 
digastric  muscle 


DEEP  PORTION  OF  SUBMAXILLARY  GLAND 


Sterno-mastoid 
muscle 


Posterior  belly  of 
digastric  muscle 


SUBMAXILLARY  GLAND, 
DRAWN  BACKWARDS 


Loop  of  fascia 


lids,  and  from  the  outer  aspect  of  tlio  "pinna.  The  ])osterior  surface  is  in  relation 
with  the  posterior  belly  of  the  digastric,  the  styloid  i)rocess,  the  styloid  group  of 
muscles,  the  mastoid  i)rocess,  and  the  ])Osterior  auricular  artery.  A  backward 
process  of  this  surfaci;  which  embraces  the  styloid  jiroeess  and  insinuates  itsc^lf  be- 
tween the  carotid  arteries  is  known  as  the  carotid  lobe.  The  anterior  surface  is  in 
contact  with  the  posterior  border  of  the  ramus  of  the  jaw  by  which  it  is  grooved 
and  with  the  internal  pterygoid  nuiscle.  It  sends  forwards  an  irregular  process, 
the  ])terygoid  lobe,  l)etween  the  jitervgoid  muscles.  The  anterior  border  is  irregu- 
lar and  thin;  it  extends  forwards  for  a  variable  distance  over  the  masseter  nmsde, 
the  duct  and  several  branches  of  the  facial  nerve  emerge  from  it.  and  in  front  of  it, 
above  the  duct,  there  is  a  small  se]iarate  lobe,  the  socia  })arotidis.  The  jiosterior 
border  is  in  relation  below  with  th(?  sterno-mastoid,  and  altove  with  the  mastoid 
process.  The  internal  l)order  is  separated  fnnn  the  wall  of  the  jtharynx  l)y  the 
carotid  vessels,  the  internal  jugular  vein,  and  the  ninth,  tenth,  and  eleventh  cranial 
nerves.      The  u])per  extremity  lies  in  tlie  posterior  jtart  of  the  glenoi<l  ftissa  of  the 


948  THE   ORGANS   OF  DIGESTION 

temporal  bone,  liehind  the  condyle  of  the  jaw,  and  in  contact  with  the  tympanic 
plate;  the  supt-rtieial  temporal  artery  and  the  temi)oral  branch  of  the  facial  nerve 
emerge  from  its'  outer  side.  The  lower  extremity  rests  u^ton  the  stylo-maxillary 
ligament  which  separates  it  from  the  posterior  end  of  the  submaxillary  gkmd. 

Within  the  substance  of  the  gland  are  the  following  structures:  Tlie  upper  part 
of  the  external  carotid  artery  with  its  superticial,  temporal,  and  internal  maxillary 
branches;  the  commencements  of  the  transverse  facial,  orbital,  and  middle  tem- 
poral branches  of  the  superticial  temporal  artery,  and  the  deep  auricular  branch  of 
the  internal  maxillary  trunk;  the  temporo-maxillary  vein,  its  tributaries,  and  its 
two  terminal  l)ranches;  the  facial  nerve,  its  cervico-facial  and  temporo-facial 
divisions  crossing  the  temporo-maxillary  vein  horizontally,  and  their  terminal 
l)ranches;  the  auriculo-temi)oral  nerve,  branches  of  the  great  auricular  nerve,  and 
a  few  deep  lymphatic  glands  which  receive  afferent  vessels  from  the  posterior  part 
of  the  nasal  fossa,  the  soft  })alate,  and  the  external  auditory  meatus. 

The  duct  of  the  parotid  (Stenson's)  issues  from  the  anterior  border  of  the 
gland  and  crosses  the  masseter  a  finger's  breadth  below  the  zygoma.  It  ])enetrates 
the  fat  of  the  cheek  and  the  fibres  of  the  buccinator  muscle,  between  which  and  the 
mucous  membrane  it  runs  for  a  short  distance  before  it  terminates  on  the  summit 
of  a  little  i)apilla,  by  a  minute  orifice.  This  opening  is  placed  opposite  the  crown 
of  the  second  upper  molar  tooth.  The  duct  commences  by  numerous  branches, 
Avhich  converge  towards  the  anterior  border  of  the  gland,  and  receives  in  its  passage 
across  the  masseter  the  duct  of  the  socia  parotidis.  The  canal  is  about  the  size  of  a 
crow-t|uill.  Its  mucous  membrane  is  covered  by  a  columnar  e])ithelium.  The 
coat  of  the  duct  is  thick  and  tough,  and  consists  of  fil)rous  tissue  intermixed  with 
contractile  fibres. 

The  arteries  are  derived  from  those  lying  in  the  gland  substance  and  from  the 
posterior  auricular  arter}'. 

The  veins  terminate  in  the  temporo-maxillary  trunk. 

The  nerves  are  derived  from  the  facial,  great  auricular,  the  carotid  plexus  of  the 
sympathetic,  and  the  auriculo-temporal.  The  latter  also  conveys  a  branch  derived 
from  the  giosso-pharyngeal  through  the  lesser  petrosal  and  the  otic  ganglion.  The 
lymphatics  terminate  in  the  superficial  and  deep  cervical  glands. 

The  parotid  gland  has  been  observed  to  retain  its  primitive  condition,  lying  over 
the  mandil)le  and  masseter  muscle.     Its  lobes  are  absent  in  early  childhood. 

The  SUBMAXILLARY  GLAND  weighs  from  two  to  three  drachms  and  it  is 
enclosed  in  a  capsule  of  deep  cervical  fascia,  except  externally,  where  it  is  in  con- 
tact with  the  body  of  the  jaw.  It  consists  of  two  portions,  the  superficial  and  the 
deei*.  The  superficial  portion  is  much  larger  than  the  deep  portion;  it  occupies 
the  fore  part  of  the  submaxillary  triangle  and  is  prismatic  in  form,  possessing  three 
surfaces  and  two  extremities.  The  external  surface  lies  in  the  submaxillary  fossa 
on  the  inner  side  of  the  body  of  the  jaw,  and  is  in  relation  posteriorly  with  the 
internal  pterygoid  muscle.  The  lower  surface  looks  downwards  and  outwards;  it 
is  covered  by  deep  fascia,  platysma,  superficial  fascia,  and  skin;  several  suj^erficial 
lymi)hatic  glands,  which  receive  afferent  vessels  from  the  lower  part  of  the  face,  lie 
upon  or  embedded  in  it,  and  it  is  crossed  by  the  facial  vein  and  some  branches  of 
the  facial  nerve.  The  internal  surface  rests  upon  the  mylo-hyoid,  hyo-glossus, 
and  stylo-glossus  muscles,  and  between  it  and  the  mylo-hyoid  muscle  are  the  mylo- 
hyoid nerve  and  artery  and  the  submental  branch  of  the  facial  artery.  The  ante- 
rior extremity  is  in  contact  with  the  anterior  belly  of  the  digastric;  the  posterior 
extremity  is  grooved  by  the  facial  artery  and  is  in  relation  with  the  stylo-maxillary 
ligament  and  the  posterior  belly  of  the  digastric. 

The  dee):)  portion  is  a  m(n-e  tongue-like  projection  Avhich  rises  from  the  internal 
surface  of  the  superficial  portion  at  the  posterior  l)order  of  the  mylo-hyoid  muscle. 
It  runs  forwards  and  upwards,  in  comi^any  with  the  duct,  under  cover  of  the  mylo- 
hyoid and  upon  the  hyo-glossus,  stylo-glossus,  and  genio-glossus  muscles;  at  its 
commencement  the  sul)maxillary  ganglion  lies  just  above  it,  and  at  its  termination 
it  is  in  close  relation  AvitJi  the  sublingual  gland. 

The  duct  of  the  submaxillary  gland  (Wharton's)  springs  from  the  deep  sur- 
face of  the  superficial  }»art  ^A  the  gland;  it  passes  forwards  and  inwards  acc()mj)anying 


THE  PHARYXX  949 

the  (h'c|)  lohe  just  described,  io  open  l>y  a  small  oi'ilice  on  the  snnnnit  of  a  jiapilla 
by  the  side  of  the  fra.'uuiii  of  the  tongue.  In  this  course  it  is  crossed  su|»erlicially 
by  the  Iin<fual  nerve.  It  lies  at  iirst  between  the  niylo-hyoid  and  hyo-glossus;  next, 
between  the  niylo-hyoid  and  genio-hyo-glossus;  and  lastly,  under  cover  of  the 
mucous  membrane  of  the  mouth,  between  the  <ienio-hyo-glossus  and  the  sublincrual 
jrland.  The  duct  is  about  two  inches  (5  cm.)  in  length,  and  has  com])aratively 
thin  coats.      It  is  lined  by  columnar  epithelium. 

The  arteries  to  the  gland  are  derived  from  the  facial  and  lingual,  and  they  are 
accompanied  l)y  corrcsi)onding  veins. 

The  nerves  proceed  from  the  submandil)ular  ganglion,  from  the  mylo-hyoid  of 
the  mandiliuLir  nerve,  and  from  branches  of  the  synii)atheti(-. 

The  SUBLINGUAL  GLAND — the  smallest  of  the  salivary  glands — is  al)Out  one 
drachm  in  weight.  It  lies  beneath  the  f(jre  })art  of  the  tongue  and  mucous  mem- 
brane of  the  tloor  of  the  mouth,  resting  deeply  upon  the  mylo-hyoid  muscle.  Its 
position  is  indicatetl  by  a  ridge  of  mucous  meml)rane,  the  sublingual  ridge,  which 
runs  outwards  and  backwards  from  the  fraenum.  It  is  limited  externally  by  the 
sublingual  fossa  of  the  mandil)le,  and  internally  by  the  genio-hyo-glossus,  stylo- 
glossus, and  Wharton's  duct;  in  front  it  touches  its  fellow,  and  behind  it  approaches 
the  deep  lol>e  of  the  submaxillary  gland. 

The  duct  from  the  main  portion  of  the  gland — the  duct  of  Rivinus  oi-  Bartholin 
— runs  alongside  the  sulmiaxillary  duct,  and  opens  either  into  it  or  on  llie  same 
pa|)illa.  The  fore  part  of  the  gland  consists  of  a  cluster  of  little  lobules,  each  with 
its  own  separate  duct — the  ducts  of  "NValther.  They  open  in  a  line  on  the  floor  of 
the  mouth,  on  the  sublingual  ridge. 

The  arteries  are  derived  from  the  sul)lingual  and  suljinental,  with  their  cori'e- 
sponding  veins. 

The  nerves  are  derived  from  the  gustatory  (through  the  submandibular  gan- 
glion) and  from  the  sympathetic. 


THE  PHARYNX 


The  pharynx  is  i)laced  l>ehind  the  nose  and  mouth,  and  extends  from  the  base 
of  the  skull  to  the  lower  part  of  the  cricoid  cartilage  opposite  the  sixth  cervical 
vertebra.  The  soft  |)alate  jjrojects  into  it  from  the  front,  dividing  it  into  a  nasal 
portion  above,  and  a  buccal  portion  l)elow. 

The  openings  of  the  two  posterior  nares  which  are  in  front,  and  the  orifices  of 
the  two  Eustachian  tubes,  one  on  each  side,  open  into  the  naso-])harynx;  -whilst 
into  the  buccal  ])ortion  l)clow  the  velum  are  the  single  openings  of  the  mouth  in 
front,  and  the  larynx  and  a\sophagus  below. 

Thus  there  are  seven  openings  leading  into  its  cavity. 

It  measures  from  above;  downwards  about  four  and  a  half  inches  (11  "3  cm.). 
It  is  flattened  from  before  backwards,  so  that  the  cavity  in  this  direction  is 
extremely  contracted,  its  mucous  membrane,  especially  above,  being  thrown  into 
numerous  folds  and  recesses;  whilst  below  the  cavity  becomes  entirely  obliteratt^d, 
and  its  anterior  and  ]>osterior  walls,  except  during  the  act  of  swallowing,  are  in 
actual  contact.  It  is  widest  opposite  the  cornua  of  the  hyoid  l)one,  and  narnjwest 
below  wbei'e  it  jiasses  into  the  (eso])hagus. 

The  pharyngeal  walls  arecomi)osed  of  a  fibrous  coat,  the  ])haryngeal  ajtoneu- 
rosis,  lined  l)y  a  nuicous  memliranc,  and  sumamded  externally  by  muscular  layers 
invested  by  a  delicate  areolar  sheath  which  lies  i)en(>ath  the  stronger  post-jiharyngeal 
fascia. 

The  pharyngeal  aponeurosis  is  well  marked  above,  l)ut  lielow  it  loses  its  density 
and  gradually  disappears  as  a  definite  structure.  Above,  it  is  attached  to  the  basi- 
occipital  bone  in  front  of  the  jtharyngeal  tubercle.      Its  attachment  may  be  traced 


950 


THE   ORGAXS   OF   DIGESTfOX 


outwards  to  the  apex  of  the  petrous  portion  of  tlie  trniporal  lionc,  and  thenee  to 
the  Eustachian  tuhe  and  internal  pterygoid  plate. 

It  descends  alone:;  the  ptervgo-maxillary  ligament  to  the  posterior  of  the 
mylo-hyoid  ridge  of  the  lower  jaw  and  jiasses  thence  along  the  side  of  the  tongue 
to  the  hyoid  1)on('  and  larynx. 

The  mucous  membrane  of  the  pliarynx  is  continuous  with  the  several  cavities 
which  ojx-n  into  it.  It  is  closely  adherent  to  the  base  of  the  skull,  thick  and  spongy 
and  dark  in  colour.  It  l)econies  thinner  where  it  approaches  the  openings  of  the 
posterior  nares  and  Eustachian  tul»cs,  and  Ix'low  it  is  ])al(r  and  folded  longitudi- 

FiG.  559a. — The  Muscles  of  the  Pharynx. 


INTERNAL  PTERYGO  0  PLATE 
Superior  eoustrietor 


Pteryg  o-raandibular 
ligament 
Stylo-hyoid  ligament    — 


Stylo-pharyngeus    


Inferior  constrictor 


Crieo-thyroid 
Cricoid  cartilage 


nally.  Lynii)hoid  follicles  and  numerous  racemose  glands  exist  throughout  the 
mucous  membrane. 

The  epithelium  is  ciliated  and  columnar  in  the  naso-pharynx,  but  becomes 
stratified  and  scaly  in  the  lower  portion. 

Muscles. — The  muscular  coat  consists  of  the  three  constrictor  muscles, 
witli  additional  librcs  dcrivc<l  from  the  stylo-  and  palato-pharyngei  muscles. 

The  inferior  constrictor  is  tliick  and  strong.  It  arises  from  the  thyroid  carti- 
lage immediately  bcliiiul  the  r»l)li(jue  line  and  superior  tubercle,  and  also  from  the 
inferior  cornu  and  the  side  of  the  cricoid  cartilage,  behind  the  crico-thyroid  muscle 
(fig.  524).  The  fibres  spread  backwards  and  inw\irds,  the  lowest  horizontally, 
whilst  those  above  ascend  more  and  more  obliquely,  and  are  inserted  into  the 


THE   rilARYNX 


951 


fibrous  raphe  of  the  pharynx.  Some  of  the  lowest  fil)res  are  continuous  witli  the 
muscular  fibres  of  the  (esoj)hagus,  and  the  upper  overlap-  the  middle  constrictor 
(fig.  5o9a). 

Near  the  upper  border  the  superior  laryn>j;eal  nerve  and  artery  }>ierce  the  thyro- 
hyoid membrane  to  reach  the  larynx.  The  recurrent  huyngeal  nerve  ascends 
beneath  tlie  lower  l)order  innnediately  behind  the  crico-thyroid  articulation. 

The  middle  constrictor  is  a  fan-shaped  muscle  which  arises  from  the  lesser  cornu 
of  the  hyoid  bone,  the  whole  length  of  the  greater  cornu,  and  from  the  stylo-hyoid 
ligament.  The  diverging  filjres  are  inserted  into  the  median  raphe,  and  blend  with 
those  of  the  opposite  side.  The  lower  fi})res  of  the  muscle  descend  beneath  the 
inferior  constrictor  to  the  lower  part  of  the  pharynx;  the  u])])er  overlap  the  superior 
constrictor,  and  reach  th(!  basilar  process  of  the  occipital  l)one;  whilst  the  middle 
fibres  run  transversely  (fig.  SoOa). 

The  glosso-pharyngeal  nerve  passes  downwards  above  its  upper  border,  thestvlo- 


FiG.  560. — Section  showing  thi-:  Postkriok  Wall  of  the  Pharynx,  with  the  Pharyn- 
geal Bursa,  Fauces,  etc. 


SECTION  THROUGH  POSTERIOR 
PORTION  OF  BODY  OF  SPHE- 
NOID BONE 

Internal  carotid  drier!/ 

SECTION  OF  CARTILAGE  OF 
EUSTACHIAN  TUBE 


EUSTACHIAN  ORIFICE 

SECTION  OF  EUSTACHIAN   _L 
TUBE  "~ 

Tensor  palati  muscle 

Levator  palati  muscle 


BUCCAL  PORTION  OF  PHARYNX 


Sphenoidal  sinus 

NASAL  BONE 


MIDDLE  TURBINAL  BONE 


PHARYNGEAL  BURSA  AND  NASO- 
PHARYNX 


INFERIOR  TURBINAL  BONE 


ANTERIOR  PILLAR  OF  FAUCES 
TONSIL 


pharyngeus  is  inserted  between  it  and  the  superior  constrictor,  and  near  its  origTu 
it  LS  overlai)ped  l)y  the  hyo-glossus  and  crossed  by  the  lingual  artery. 

The  superior  constrictor  is  (juadrilateral  in  sha]>e,  |>ale,  and  thin  (fig.  o-'jOa  ). 
It  arises  from  the  lower  third  of  the  hinder  edge  of  the  internal  ]»tervgoid  i)late  and 
its  hamular  process,  from  the  ptervgo-mandilnilar  ligament,  from  the  posterior  fifth 
of  the  mylo-hyoid  ridge  of  the  mandible,  and  from  the  side  of  the  tongue.  The 
fibres  pass  backwards  to  be  inserted  into  the  median  ra})he,  the  highest  reaching 
the  pharyngeal  spine.  The  Eustachian  tube  and  the  levator  palati  muscle  are 
])laced  above  the  sui)erior  arched  bcu'der,  and  the  space  between  this  and  the  l)asilar 
jH'ocess,  devoid  of  muscular  fibres^  is  strengthened  by  the  ]»haryngeal  ai)oncurosis. 
It  is  semilunar  in  shape,  and  named  the  sinus  of  Morgagni. 

The  stylo-pharyngeus  arises  from  the  base  of  the  styloid  process  internally. 
It  passes  downwards  and  inwards  to  reach  the  ])harynx  between  the  superior  and 
middle  constrictors.  Its  fibres  s]trea<l  out  as  it  descends  beneath  the  mucous  mem- 
V)rane.      At  the  lower  l)order  of  the  superior  constrictor  some  of  its  fibres  join  fibres 


952  THE  OEGAys  OF  DIGESTION 

of  the  palato-pharyngeus  and  are  inserted  into  the  posterior  border  of  the  thyroid 
cartihige  ( htr.  ooOa):  tin-  rest  blend  with  the  constrictors. 

The  palato-pharyngeus  is  described  with  tlie  muscles  of  the  soft  palate. 

The  niu.scular  coat  of  tlie  pharynx  is  svipplied  by  the  pharyngeal  plexus  and 
the  external  and  recurrent  laryngeal  nerves.  The  stylo-jjliaryngeus  is  sujjplied  by 
the  gloss()-])haryngeal  nerve. 

Relations.-^The  pharynx  is  loosely  connected  by  areolar  tissue  with  the  pre- 
vertebral fascia,  the  longus  colli,  and  the  rectus  capitis  anticus  major  muscles, 
and  vertebral  colunni.  Laterally,  it  is  in  relation  with  the  styloid  process  and  its 
muscles,  the  ninth,  tenth,  and  eleventh  cranial  nerves,  the  superior  laryngeal  nerve 
and  its  internal  and  external  laryngeal  branches,  the  parotid  and  thyroid  glands, 
the  sheath  of  the  carotid  vessels,  the  pharyngeal  plexus  of  nerves,  the  ascending 
pharyngeal  artery,  and  the  ascending  palatine  branch  of  the  facial  artery;  above, 
it  is  separated  from  the  ramus  of  the  mandible  and  internal  pterygoid  muscle  by  a 
cellular  interval;  and  beneath  its  investing  fascia  there  is  a  plexus  of  veins. 

The  interior  of  the  pharynx,  viewed  from  behind,  presents  the  seven  open- 
ings already  named.  At  its  upper  and  back  part  the  mucous  membrane  forms  a 
rounded  projection  which  corresponds  to  the  anterior  recti  muscles,  and  on  each 
side  of  this  it  sinks  backwards,  beneath  the  tip  of  the  petrous  portion  of  the  tem- 
poral bone,  and  l)ehind  the  Eustachian  tube,  to  form  a  ad-de-sac  known  as  the 
pharyngeal  recess,  or  fossa  of  Rosenmiiller. 

In  the  roof  of  the  cavity  just  below  the  body  of  the  occipital  bone  and  in  the 
middle  line,  the  jnucous  membrane  dips  into  a  little  pouch  with  a  contracted  orifice, 
the  pharyngeal  bursa,  wdiich  is  easily  demonstrated  in  the  foetus  and  young  child, 
but  commonly  entirely  disapj^ears  in  the  adult. 

Embedded  in  the  roof  of  the  pharynx,  in  front  of  the  pharyngeal  l)ursa,  and 
between  the  oritices  of  the  Eustachian  tul)es,  there  is  a  collection  of  lymphoid 
follicles  which  is  known  as  the  pharyngeal  tonsil,  or  Luschka's  tonsil.  Tliis  por- 
tion of  the  naso-pharynx  is  exceedingly  liable  to  become  swollen  and  chronically 
thickened  in  naso-pharyngeal  catarrh. 


TRF    OESOPHAGUS 


The  CESophagus  is  that  portion  of  the  alimentary  tract  which  extends  between 
the  pharynx  and  the  stomach.  It  is  more  constricted  than  the  rest  of  the  canal, 
being  narrowest  at  its  commencement  opposite  the  sixth  cervical  vertebra  and  lower 
border  of  the  cricoid  cartilage.  It  is  again  somewhat  contracted  in  its  passage 
through  the  dia])hragm,  which  is  opposite  the  upper  border  of  the  eleventh  thoracic 
vertebra.  It  is  nine  or  ten  inciies  (25  cm.)  in  length,  and  in  its  course  downwards 
follows  the  curv(^s  of  the  vertebral  colunm,  until  it  finally  ])asses  forwards  in  front 
of,  and  slightly  to  the  left  of  the  aorta  to  gain  the  oesophageal  opening  in  the  dia- 
phragm. In  addition  to  these  curves  it  presents  two  lateral  cur^^atures,  one  convex 
towards  the  left  side  at  the  root  of  the  neck  and  in  the  upper  part  of  the  thorax, 
and  the  other  concave  towards  the  left  in  the  lower  part  of  the  thorax  where  it  leaves 
the  vertebral  column.  It  lies  in  the  middle  line  at  its  commencement  opposite  the 
sixth  cervical  vertebra,  and  again,  at  a  lower  level,  opposite  tlu^  fifth  thoracic  vertebra. 

Relations  in  the  neck. — The  oesophagus  has  in  front  of  it  the  trachea,  the 
])()sterior  portion  of  the  left  lateral  lol^e  of  the  thyroid  gland,  and  the  left  recurrent 
laryngeal  nerve,  l)ranches  of  the  inferior  thyroid  artery  and  the  carotid  sheath. 
Behind,  it  rests  upon  the  vertebral  column,  the  left  longus  colli  muscle,  and  pre- 
vertebral fascia. 

On  its  right  side  are,  placed  the  right  carotid  and  right  recurri'nt  nerve;  and  on 
the  left  side  the  left  inferior  thyroid  vessels,  left  carotid  artery,  left  subclavian, 
and  the  thoracic  duct.      The  recurrent  nerves  pass  upwards  on  each  side  to  gain  the 


THE  (ESOPHAGUS  958 

interval  between  tlie  trachea  and  (esopliagns.  The  left  nerve,  as  already  deserihcd, 
lies  in  front  of  the  tube,  and  the  riu;ht  at  some  little  distance  from  it. 

In  the  thorax  the  cesophagus  descends  through  the  superior  and  the  ])osterior 
mediastina.  In  the  superior  mediastinum  its  anterior  relations  are  the  trachea, 
with  the  deep  cardiac  plexus  in  front  of  its  bifurcation,  the  left  subclavian  and 
carotid  arteries  crossing  its  left  border  oljliquely,  the  left  recurrent  laryngeal  nerve 
and  the  arch  of  the  aorta.  To  the  left  are  the  left  carotid  and  sul)clavian  arteries, 
the  end  of  the  arch  of  the  aorta,  and  the  left  pleural  sac.  To  the  ritrht  it  is  in 
relation  with  the  right  vagus  nerve  and  the  right  i)leural  sac.  Behind,  it  rests 
upon  the  vertebral  column,  the  left  longus  colli  muscle,  and  it  overla])s  the 
thoracic  duct.  As  it  enters  the  posterior  mediastinum  it  passes  behind  the  left 
bronchus  and  the  right  pulmonary  artery,  resting  posteriorly  on  the  vertebral 
column  and  thoracic  duct.  In  the  posterior  mediastinum  it  has  in  front  of  it  the 
pericardium,  which  separates  it  from  the  left  auricle  of  the  heart  and  a  portion  of 
diajiliragm;  it  rests  upon  the  vertel:>ral  column,  the  vena  azygos  minor,  sujierior 
and  inferior,  the  right  aortic  intercostal  arteries,  and  the  thoracic  duct.  To  1h<' 
right  is  the  right  pleural  sac,  the  vena  azygos  major,  which  it  ])artly  overlaps,  and 
below  the  thoracic  duct.  To  the  left  in  the  u])per  part  is  the  descending  thoracic 
aorta,  and  below  the  left  pleural  sac  is  separated  from  it  by  a  little  loose  areolar 
tissue.  It  is  surrounded  by  the  (esoi)hageal  plexus  formed  by  the  vagi  nerves,  and 
as  they  emerge  from  the  lower  part  of  the  plexus  the  left  vagus  lies  in  front  of  the 
oesophagus  and  the  right  vagus  behind. 

In  the  abdomen  the  oesophagus  lies  in  the  epigastric  region.  In  front  of  it  is 
the  left  lobe  of  the  liver.  To  the  left  the  left  lobe  of  the  liver  and  the  fundus  of  the 
stomach.  To  the  right  the  Spigelian  lobe  of  the  liver,  and  Ijehind  the  decussating 
fibres  of  the  crura  of  the  diaphragm  and  the  left  inferior  phrenic  artery. 

The  arterial  suii])ly  of  the  oesophagus  is  derived  from  the  inferior  thyroid,  the 
oeso])hageal  branches  of  the  aorta,  the  intercostals,  the  inferior  phrenic,  and  the 
coronary  arteries. 

The  veins  accompany  the  arteries. 

The  nerves  are  filaments  of  the  spinal  accessory  which  pass  to  it  by  the  vagus, 
and  the  recurrent  laryngeal  nerves. 

After  death  the  gullet  is  somewhat  flattened  from  before  backwards,  but  it  is 
more  rounded  during  life.     It  is  closed  except  during  the  passage  of  food,  etc. 

Structure. — Tlie  wall  of  the  oesophagus  is  composed  of  three  coats — muscular, 
submucous,  and  mucous.  It  is  surrounded  wath  elastic  cellular  tissue,  loosely 
connecting  it  with  the  neighbouring  structures,  and  freely  permitting  its  distension. 

The  muscular  coat  is  thick,  red,  and  consists  of  striped  muscular  fil)res  in  its 
upper  thir<l  or  more.      It  is  made  up  of  two  distinct  layers. 

The  longitudinal  fibres  commence  as  three  flattened  l)ands:  a  strong  anterior 
arising  from  the  ridge  on  the  back  of  the  cricoid  cartilage  (fig.  526),  and  two  lateral 
bands  wliich  blend  with  the  fibres  of  the  pharynx.  These  all  unite  into  a  continu- 
ous layer  which  passes  below  into  the  muscular  coat  of  the  stomach.  Several 
accessory  bands  have  been  described,  connected  with  the  trachea,  left  bronchus, 
pericardium,  and  left  pleura. 

The  circular  fibres  are  continuous  above  with  the  inferior  constrictor,  and  l)elow 
with  the  ol)li(|Ue  Hl)res  of  the  stomach;  they  form  a  uniform  layer  Avhich  l)ecomes 
.somewhat  ()bli(jn(ly  disposed  towards  the  middle  of  the  gullet. 

The  submucous  coat  loosely  connects  the  inner  mucous  and  outer  nniscular 
coats.  It  is  the  seat  of  numerous  racemose  glands  whose  ducts  open  on  the  surface 
of  the  mucous  membrane. 

The  mucous  coat  is  thick,  reddish  above,  paler  l)elow.  and  deeply  folded 
longitudinally.  It  i)resents  numerous  jiapillte  and  contains  racemose  glands.  It 
is  covered  by  a  stratitied  .squamous  epithelium. 


THE  ABDOMINAL  AaSCERA 

By  FEEDERICK  TREVES,  F.R.C.S.,ENn. 

SURGEON  IN  ORDINARY  TO  H.  R.  H.  THE  DUKE  OF  YORK  ;  SURGEON  TO  AND  LECTURER  ON  SURGERY'  AT  THE 

LONDON  HOSPITAL 


TRE   PERITONEUM 

Its  general  character. — The  peritoneum  i^;  a  thin  and  delicate  serous  mem- 
brane wliich  lines  the  cavity  of  the  abdomen  from  the  diaphragm  to  the  pelvic  floor, 
and  invests  or  covers  to  a  varying  extent  the  viscera  which  that  cavity  contains. 
Viewed  in  its  very  simplest  condition,  it  may  be  regarded  as  a  closed  sac,  the  inner 
surface  of  which  is  smooth  and  perfectly  polished,  while  the  outer  surface  is  rough 
and  is  attached  to  the  tissues  which  surround  it.  Could  it  be  possible  for  the 
]ieritoneum  to  be  removed  entire  from  the  body  by  some  process  of  superhuman 
dissection,  it  would  appear  simply  as  a  huge  thin-walled  bag. 

In  the  male  subject  the  peritoneum  forms  actually  a  closed  sac;   but  in  the 

Fig.  501. — Transverse  Section  of  the  Peritoneal  Sac  at  about  the  Level 

OF  THE  Umbilicus. 


female  its  wall  exhibits  two  minute  punctures,  which  correspond  to  the  openings 
of  the  Fallopian  tulles.  That  part  which  lines  the  walls  of  the  abdomen  is  termed 
the  parietal  peritoneum;  that  which  is  reflected  on  to  the  viscera  is  the  visceral 
peritoneum.  The  disposition  of  the  peritoneum  may  first  be  studied  by  noting  its 
arrangement  as  made  evident  in  transverse  sections  of  the  abdomen  at  certain  levels. 
The  first  section  to  be  described  shows  the  peritoneum  in  its  simplest  condition. 
This  is  a  transverse  section  through  the  body,  at  about  the  level  of  the  ui)per 
surface  of  the  fourth  lumbar  vertebra,  and  therefore  about  the  site  of  tlie  umbilicus 
(fig.  561).  Starting  on  the  inner  surface  of  tlie  anterior  abdominal  parietes,  the 
peritoneum  is  seen  to  cover  the  transversalis  fascia,  and  indirectly  the  anterior 
abdominal  muscles;  then,  passing  to  tlie  left,   it  lines  the  side  of  "the  abdomen, 

954 


rilE  PEIUTOyFA'M 


955 


until  it  reaches  the  descending  colon.  This  it  covers,  as  a  rule,  in  front  and  on 
the  sides,  though  occasionally,  as  shown  in  the  diagram  (fig.  561),  it  forms  a 
meso-colon.  Then  it  passes  over  the  hodies  of  tlie  vertehra?  with  the  large  vessels 
upon  them,  and  leaves  the  back  of  the  a])domen  to  run  forward  to  enclose  the 
termination  of  the  small  intestine,  returning  again  to  the  si)ine.  The  two  layers 
thus  form  the  mesentery,  liaving  jjetwirn  tliem  the  terminal  branches  of  the  sujx'- 
rior  mesenteric  vessels.  It  tlien  passes  over  the  right  half  of  the  i)osterior  abdom- 
inal wall,  covering  the  ascending  colon  in  front,  and  at  the  sides  only,  vmless  there 
be  a  meso-colon,  and  then  passes  on  to  the  side  and  front  of  the  abdomen  to  the 
point  from  whi('h  it  was  first  traced. 

In  tracing  the  peritoneum  in  a  section  of  the  Ixxly  (fig.  562)  opposite  the 
stomacii,  on  a  level  with  the  first  lumbar  vertel)ra,  its  course  becomes  more  com- 
plicated and  difficult  to  follow. 

In  the  section  already  given  tlie  peritoneum  as  a  sim]»l('  closed  sac  can  l)e 
readily  conceived;  but  at  the  level  now  exposed  the  serous  membrane  has  ])een  so 
introverted  that  there  appears  to  be  two  sacs,  one  leading  from  tlie  other.  The 
lesser  is  indeed  but  a  diverticulum  or  l)ulging  from  the  greater,  and  the  manner  of 
its  formation  is  exi)laincd  on  page  1002.  These  two  sacs  are  called  the  greater 
and  the  lesser  sacs  of  the  peritoneum.  They  communicate  through  a  narrow 
strait  or  neck,  the  foramen  of   W'inslow.     The  lesser  sac  or  cavity  is  discovered 


Fiu.  562. — Transverse  Section  of  the  Abdomex  at  the  Level  of  the  Foramen 

OF    WlNSLOW. 

GASTRO-HEPATIC  OMENTUM 


GASTRO-SPLENIC 
OMENTUM 


bt'bind  tlie  stomach,  so  that  on  first  opening  the  abdomen  no  trace  of  it  is  to  l)e 
seen.  It  extends  downwards  between  the  layers  of  the  great  onnaitum  (though  this 
part  of  the  lesser  sac  is  always  obliterated  by  adhesion  in  the  adult ).  It  extends 
upwards  to  the  under  surface  of  the  liver,  and  is  limited  behind  l)y  the  i>osterior 
abflominal  wall;  and  below,  Ix'hind  the  great  omentum,  by  the  transverse  meso- 
colon.     Its  disi)osition  on  vertical  si'ction  is  shown  in  fig.  563. 

The  foramen  of  Winslow  is  situated  just  l>elow  the  liver;  it  looks  forwards  and 
towards  tlie  right,  and  will  readily  admit  one  or  two  fingers.  It  is  bounded  above 
by  the  caudate  lobe  of  the  liver;  below,  by  the  duodenum  and  hepatic  vessels; 
behind,  by  the  vena  cava;  and  in  front  by  the  gastro-hepatic  or  lesser  omentum, 
containing  the  structures  passing  to  and  from  the  liver. 

Starting  at  the  foramen  of  Winslow,  tlic  lesser  sac  Avill  be  found  to  turn  to  the 
left. 

If  ni>\v  the  ])critoncuni  be  vii-wcd  in  a  transverse  section  of  the  body  at  the 
level  named,  viz.,  through  the  lirst  lumbar  vertebra,  it  will  be  found  that  the  sec- 
tion has  probaldy  passed  through  the  foramen  of  W'inslow  ( lig.  5(i2).  Starting  at 
the  front  of  the  abdomen  and  going  to  the  right,  tlie  peritoneum  is  seen  to  line  the 
anterior  abdominal  wall,  to  pass  over  the  side  of  the  abdomen,  and  to  cover  the 
front  of  the  right  kidney;  it  then  extends  on  to  the  vena  cava,  when  it  becomes  a 
l»art  of  the  lesser  sac;  then  along  the  back  of  the  lesser  sac,  over  the  aorta  and  i)an- 


956 


THE   ORGANS   OF  DKiESTIOX 


creas,  which  sepamtc  it  from  the  vertel)ral  column;  next  it  roaches  the  anterior  of 
the  two  internal  surfaces  of  the  si)leen  in  front  of  the  hilum.  Here  it  meets  with 
another  layer  of  peritoneum,  and  helps  to  form  the  gastro-splenic  omentum. 
Leavinij;  the  spleen,  it  changes  its  direction,  and  runs  to  the  right  to  the  stomach, 
forming  the  })osterior  layer  of  the  gastro-splenic  omentum;  it  covers  the  posterior 
surface  of  the  stomach,  and  leaves  its  upper  border  to  form  the  posterior  layer  of 
the  gastro-hepatic  omentum,  and  then  passes  upwards  and  to  the  right  to  the  liver. 
In  this  transverse  s(H^tion,it  is  only  seen  passing  on  the  right  to  the  hepatic  vessels, 
where  it  forms  the  posterior  lioundary  of  the  foramen  of  ^Vinslow.  Here  it  bends 
sharplv  round  and  forms  the  anterior  layer  of  the  gastro-hepatic  omentum;  and 
passing  to  tlie  left  reaches  the  stomach,  which  it  covers  in  front.     It  then  forms  the 


Fig.  563.— DiAtiUAM  to  show  the  Peritoneum  as  seex  in  a  vertical  Section. 

(Allen  Thomson. 


GASTRO-HEPATIC  OMENTUM 
STOMACH 


TRANSVERSE  COLON 
MESENTERY 


FORAMEN  OF  WINSLOW 
PANCREAS 


DUODENUM 

TRANSVERSE  MESO-COLON 


anterior  layer  of  the  gastro-splenic  omentum,  and  once  more  reaches  the  spleen. 
It  passes  riglit  round  the  spleen  to  the  back  of  the  hilum,  where  it  is  reflected  on 
to  the  left  kidney  (fig.  562).  Hence  the  ])eritoneum  ]iasses  along  the  side  and  front 
of  the  alxlonien  to  the  })oint  from  which  it  started.  In  this  section  the  liver  is  so 
divided  as  to  ajjpear  separated  from  all  connection  with  the  other  viscera  and  the 
alxlominal  wall,  and  to  be  surrounded  l)y  jM-ritoneum. 

The  course  of  the  peritoneum  in  a  longitudinal  section  of  the  body  will  now 
be  considered  (fig.  563).  Starting  at  the  uml>ilicus.  and  passing  downwards,  the 
periton(nnn  is  seen  to  line  the  anterior  abdominal  wall.  Before  reaching  the  pelvis 
it  covers  also  the  urachus,'  the  deep  epigastric  arteries,  and  obliterated  hypogastric 
arteries,  which  can  be  seen  to  form  ridges  l)oneath  it.  For  some  little  way  above 
the  OS  ])ubis  the  peritoneum   is  loosely  connectecl  with  the  abdominal  wall,  a  cir- 


THE  PERITOXFJM  957 

ciiiiistanci'  which  is  uiikU'  use  of  in  suin'a-puliic  {■ystntoiiiy.  Moreover,  as  the  dis- 
tt'iuk'd  hlackler  rises  from  tlie  ])elvis  it  can  detach  the  serous  nieiiil)rane  to  some 
extent  from  the  anterior  parietes.  In  extreme  distension  of  tlie  hhidder  the  peri- 
toneum may  he  lifted  up  for  some  two  inches  vertically  ahove  the  symphysis.  On 
reaching  the  os  jjubis  it  is  reflected  on  to  the  upper  part  of  the  l)ladder,  covering  it 
as  far  l)aclv  as  the  base  of  tlie  trigone;  thence  it  is  retiected  on  to  the  rectum,  which 
it  covers  in  front  and  at  the  sides  on  its  upper  i)art,  or  forms  for  such  ])art  a  distinct 
meso-rectum.  Between  the  bladder  and  rectum  it  forms  the  recto-vesical  pouch. 
The  mouth  of  this  pouch  is  bounded  on  eitlier  side  by  a  creseentic  fold,  the  plica 
semilunaris.  In  the  female  the  peritoneum  is  reflected  from  the  bladder  on  to  the 
uterus,  which  it  covers;  it  then  extends  so  far  down  in  the  ])elvis  as  to  pass  over 
the  upper  part  of  the  vagina  behind;  thence  it  extends  to  the  rectum.  The  i)eri- 
toneum  wliich  invests  the  uterus  is  retiected  laterally  to  form  the  broad  ligaments. 
The  fold  between  the  vagina  and  rectum  forms  the  recto-vaginal  pouch,  or  })0Uch 
of  Douglas.     The  membrane  has  now  bei'n  traced  back  to  the  s})ine. 

Following  it  ui)wards,  the  sigmoid  Hexure  will  be  found  to  be  completely  cov- 
ered by  peritoneum,  a  meso-colon  attaching  the  gut  to  the  al)dominal  wall.  As 
seen  in  fig.  561,  the  ascending  and  descending  colon  in  cither  loin  are  covered  Ijy 
peritoneum,  as  a  rule,  in  front  and  on  the  outer  sides.  A  little  higher  up  in  the 
median  line  the  peritoneum  passes  forwards,  to  enclose  the  small  intestine,  and. 
returning  to  the  spine,  forms  the  mesentery  (fig.  563).  It  now  i)asses  over  tlie 
third  part  of  the  duodenum  to  the  pancreas,  from  which  point  it  again  passes  for- 
wards to  form  the  lower  layer  of  the  transverse  meso-colon.  It  invests  the  trans- 
verse colon  below' and  })artly  in  front,  and  then  leaves  it  to  ])nss  downwards  to 
take  part  in  the  great  omentum.  Running  downwards  some  distance,  it  returns 
and  forms  the  anterior  layer  of  the  omentum.  On  reaching  the  stomach  it  goes 
over  the  anterior  surface,  and  at  the  upper  border  forms  the  anterior  layer  of  the 
lesser  or  gastro-hepatic  omentum,  w'hich  extends  between  the  stomach  and  the  liver. 
It  invests  the  inferior  surface  of  the  liver  in  front  of  the  transverse  fissure,  and, 
turning  over  its  anterior  border,  covers  the  upper  surface.  At  the  posterior  limit 
of  the  upper  surface  it  leaves  the  liver  and  goes  to  the  diaphragm,  forming  the 
superior  layer  of  the  coronary  ligament.  It  covers  the  anterior  part  of  the  dome 
of  the  diaphragm,  and,  once  more  reaching  the  anterior  al)dominal  wall,  can  be 
followed  to  the  umbilicus,  where  it  was  first  described.  On  reference  to  tlie  dia- 
gram (tig.  563),  the  student  might  be  led  to  suppose  that  the  two  sacs  as  above 
described  are  (juite  separate.  This,  of  course,  is  not  the  case;  but  in  a  longitudinal 
section  of  the  body  made  anywhere  to  the  left  of  the  foramen  of  A\'inslow,  it  is 
impossible  to  show  the  direct  connection  between  the  two  sacs. 

The  peritoneum  has  only  been  traced  in  this  longitudinal  section  so  far  as  it 
concerns  the  greater  sac.  It  now  remains  to  follow  upon  the  same  section  such 
part  of  the  mein])rane  as  forms  the  lesser  sac.  The  ])eritoneum  here  will  be  seen 
to  cover  the  posterior  surface  of  the  stomach;  and  from  thence  it  runs  U]iwards  to 
the  liver,  forming  the  posterior  layer  of  the  lesser  or  gastr()-hei)atie  omentum.  It 
reaches  the  liver  behind  tlie  transve!rse  fissure.  It  covers  only  a  ]iart  of  its  ]»oste- 
rior  surface,  and  is  retiected  on  to  the  diaphragm,  forming  the  lowi'r  layer  of  the 
coronary  ligament.  It  now  goes  downwards  over  the  hinder  part  of  the  dome  of 
the  diaphragm  to  the  spine,  separated  from  the  latter  by  the  great  vessels.  On 
reaching  the  pancreas  it  passes  forwards,  and  forms  the  upper  layer  of  the  trans- 
verse meso-colon.  It  then  covers  the  upper  half  of  the  transverse  colon,  and 
descending^  forms  the  innermo.st  layer  of  the  great  omentum.  It  now  ascends, and, 
arriving  at  the  greater  curvature  of  the  stomach,  ])asses  on  to  its  j^osterior  wall. 
At  this  point  its  description  was  commenced.  From  fig.  562  it  will  also  be  evident 
that  the  peritoneum  forming  the  lesser  sac  comes  into  contact  with  the  spleen,  forms 
one  layer  of  the  gastro-splenic  omentum,  and  is  in  relation  with  the  upper  jiart  of 
the  left  kidney. 

The  precise  manner  in  which  certain  organs — su<-h  as  the  liv<'r.  the  cax'um.  the 
duodenum,  and  the  kidneys — are  invested  by  ])eritoneum.  is  dePcril)e<l  in  theacc«)unt 
of  those  viscera.  To  such  accounts  the  reader  is  referred  for  a  description  of  tlie 
many  'ligaments'  (such  as  those  of  the  bladder  and  liver)  which  are  formed  by  the 
])eritnneum. 


958 


THE   ORGANS   OF  DIGESTION 


The  great  omentum. — It  will  be  seen  that  the  great  onientuni  is  fonued  of 
four  layers  of  peritoneum,  though  this  is  quite  impossible  to  demonstrate  in  an 
adult,  the  individual  layers  having  become  adherent. 

The  great  omentuni^  acts  as  a  sort  of  apron,  protecting  the  intestines  and  ])ro- 
viding  them  with  a  heat-economising  covering  of  fat.  It  is  nearh'  quadrilateral  in 
sha])e,  and  is  variable  in  extent. 

In  tig.  5(34  the  great  omentum  is  shown  to  be  connected  with  the  greater  curva- 
ture (^f  the  stomach  on  the  one  hand,  and  the  transverse  colon  on  the  other.  This 
is  the  arrangement  described  in  the  text.  Under  certain  conditions  (as  show^n  in 
fig.  5G3)  the  posterior  layer  of  the  great  omentum  returns  to  the  posterior  parietes, 
and  is  independent  of  the  transverse  meso-colon.  This  variation  is  explained  in 
the  account  of  the  evolution  of  the  peritoneum  (page  1002). 

Mr.  Lockwood  has  made  some  investigations  on  the  lengths  of  the  transverse 
meso-colon  and  great  omentum  in  thirty-three  cases.  In  twenty,  under  the  age  of 
forty-five,  only  one  subject  had  a  great  omentum  long  enough  to  l:)e  drawn  beyond 
the  "pubic  spine;  in  five,  the  omentum  reached  as  far  as  the  pubes.  In  the  cases 
beyond  forty-five  years,  it  Avas  the  exception  rather  than  the  rule  to  find  an  omen- 
tum which  could  not  l)e  |)ulled  l^eyond  the  lower  limits  of  the  abdomen. 

The  lesser  or  gastro-hepatic  omentum  consists  of  a  double  layer  of  perito- 
neum extending  between  the  lesser  curvature  of  the  stomach  and  the  transverse 


Fig.  564.- 


-DlAGRAM  TO  SHOW  THE   PERITONEUM    AS  SEEN   IN   VERTICAL  SECTION. 
(Allen  Thomson.) 


GASTRO-HEPATIC  OMENTUM 


MESO-COLON 
TRANSVERSE  COLON 


FORAMEN  OF  WINSLOW 


SMALL  INTESTINE 


fissure  of  the  liver.  If  the  two  anterior  layers  of  the  great  omentum  are  traced 
upwards,  they  are  seen  to  enclose  the  stomach,  and  then  join  together  again  at  the 
lesser  curvature  to  form  the  lesser  or  gastro-hepatic  omentum  (fig.  563).  It  is 
connected  al)ove  with  the  transverse  fissure  of  the  liver,  below  with  the  upper  curva- 
ture of  the  stomach;  the  left  extremity  encloses  the  oesophagus;  the  right  border 
contains  the  hepatic  vessels,  and  is  free,  forming  the  anterior  boundary  of  the 
foramen  of  Winslow. 

The  gastro-splenic  omentum  connects  the  left  extremity  of  the  stomach  with 
the  S])leen,  continuing  the  layers  of  peritoneum  which  enclose  the  stomach. 

The  gastro-phrenic  and  phreno-colic  ligaments. — As  the  peritoneum  passes 
from  the  diaphragm  to  the  stomach  it  forms  a  small  fold  just  to  the  left  of  the 
oesophagus.  This  is  the  gastro-phrenic  ligament.  A  stout  fold  of  the  membrane 
also  extends  from  the  diaphragm  (opposite  the  tenth  and  eleventh  ribs)  to  the 
spleniit  fiexurc  of  the  colon,  and  is  known  as  the  phreno-colic  or  costo-colic  ligament. 

Subperitoneal  connective  tissue. — An  elaborate  account  of  this  tissue  has 
been  written  by  Mr.  Anderson  and  INIr.  Makins.  According  to  these  observers, 
'  the  su1)])(n-itoneal  and  subpleural  fascite  are  to  be  regarded  as  a  portion  of  a  wide 
system  of  mesoblastic  connective  tissue  which  surrounds  the  great  vessels  of  the 
trunk,  accompanying  these  branches  from  origin  to  termination,  and  extending 
mainly  in  the  form  of  perivascular  sheaths  to  all  })arts  of  the  body.' 


THE  ABI)()Mi:X 


959 


The  su)»i»crit()ii(';il  S('<iineiit  of  tlic  tissue  tliey  divide  into  two  portions:  a  jmrietal 
layer,  elosely  conneeted  to  tlie  wall  of  the  eavity,  and  vi.seei'al  hiniina  whieh  aeeoni- 
pany  the  branehes  of  the  aorta  to  their  distribution. 

The  parieUd  Utijcr  is  developed  ehielly  in  front  of  the  vertebral  cohnun,  '  from 
wliich  point  it  may  be  traced  as  a  Inroad  expansion  between,  and  intimately  e(»n- 
neeted  with,  the  i)eritoneum  on  the  one  hand,  and  the  transversalis,  dia})hraf!;mati(', 
iliac;,  oljturator,  and  recto-vesical  faseiic  on  the  other. '  It  forms  a  sheath  for  the 
large  vessels,  and  is  continuous  with  the  vessels  outside  the  abdomen. 

Tlie  visccnil  portion  follows  the  course  of  the  branches  of  the  aorta,  and  greatly 
assi.sts  in  fixing  certain  viscera,  such  as  the  liver,  pancreas,  etc.,  becoming  continu- 
ous with  their  connective-tissue  tunic.  This  tissue  can  be  seen  })assing  ])etw(,'en  the 
layers  of  ])eritoneum  to  thos(i  organs  wliich  are  connected  to  the  abdominal  wall  by 
dui)licatures  of  peritoneum. 

For  an  account  of  the  evolution  of  the  peritoneum,  and  an  explanation  of  its 
arrangement  in  the  human  l)ody,  the  student  is  referred  to  page  991. 


Fio.  o6.j.— TiTK  Viscera  as  skex  ox  fci.ly  opening  the  Abdomen  without 
DisAKKANGEMENT  OF  THE  INTERNAL  Pakts.     (After  Sarazin.) 


GREAT  OMENTUM 


SMALL  INTESTINE 


THE    AlWOJfhW 


The  abdomen  properly  consists  of  that  part  of  the  body  cavity  situated  between 
the  diaphragm  and  the  pelvis.  It  is  Ixmnded  almve  l)y  the  diajihragm;  below,  by 
the  brim  of  the  true  pelvis;  behind,  by  the  vertebral  cohunn,  dia|>hragm,  ipKulratus 
lumlwrnm  and  ]>soas  muscles,  and  by  tlie  posterior  ))ortions  of  tlie  ilia.  At  the 
sides  it  is  limited  by  the  anterior  parts  of  the  ilia  and  the  hinder  segmcMits  of  the 
muscles  whirh  compose  tin- anterior  abdominal   wall,  viz.,  the  transversalis,  inter- 


5)00  THE   ORGAXS   OF  DIGESTION 

nal  oblique,  and  external  oljlique.  In  front,  besides  tbese  muscles,  there  are  the 
two  recti  and  pyraniidales  muscles.  External  to  the  peritoneum  the  abdomen  is 
lined  bv  a  special  laver  of  fascia. 

The  abdomen  is  the  largest  serous  cavity  in  the  body.  Its  serous  membrane  is 
the  peritoneum,  which,  through  its  various  complicated  arrangements,  is  always 
(with  one  uninii)ortant  exception)  a  closed  sac,  so  that  the  viscera  are  in  reality 
situated  outside  tlie  enclosure.  The  principal  viscera  found  in  the  al)d(>nien  are 
those  connected  with  digestion  and  the  excretion  of  urine. 

On  freelv  laying  oi)en  an  abdomen  from  the  front,  the  general  form  of  the  s]iace 
is  seen  to  be  an" irregular  hexagon,  the  sides  of  which  are  formed  as  follows: — The 
upper  two  by  the  niargins  of  the  costal  cartilages  with  the  ensiform  cartilage 
between;  the 'two  lateral  sides  by  the  edges  of  the  lateral  boundary;  and  the  two 
lower  by  the  two  ligaments  of  Poupart  which  meet  at  the  pubes. 

In  this  irre<rular  hexagon  the  following  organs  can  be  observed  without  dis- 
arrauizing  their'  normal  position  (fig.  565).  Above,  on  the  right  side  under  the 
costal  cartilages,  can  be  seen  the  liver,  which  extends  from  the  right  across  the 
median  line  to  a  point  below  the  left  costal  cartilages.  Below  the  liver,  and  lying  to 
the  left  side,  can  be  seen  the  anterior  surface  of  the  stomach;  from  the  lower 
border  of  the  stomach  the  omentum  extends  downwards,  and  shining  through  it  can 
be  seen  the  middle  part  of  the  transverse  colon.  On  each  side  and  below  the  irregu- 
larly folded  omentum  are  exposed  the  coils  of  the  small  intestine;  in  the  right  iliac 
fossa  apart  of  the  ca3cum  appears;  and  in  the  left  iliac  fossa  a  coil  of  the  sigmoid 
flexure  is  usually  evident. 

To  the  left  of  the  stomach  and  under  cover  of  the  lower  ribs  of  the  left  side  the 
edge  of  the  spleen  may  possibly  be  observed;  and  just  below  the  edge  of  the  liver, 
and  about  the  level  of"  the  tip  of  the  ninth  rib,  the  gall  bladder  may  be  seen.  _  The 
dome  of  tlie  urinary  l)ladder  may  be  noticed  just  beliind  the  symphysis  pul^is  and 
in  the  median  line.     The  disposition  of  the  viscera  in  the  foetus  is  shown  in  fig.  578. 


THE  ST03IACH 


General  description. — The  stomach  is  situated  in  the  upper  part  of  the  abdo- 
minal cavity  and  to  the  left  side,  ^^'hen  empty  it  is  found  in  the  left  hypochon- 
drium  and  left  half  of  the  epigastric  region.  Above  it  are  the  liver  and  diaphragm, 
while  below  is  the  transverse  colon.  It  is  somewhat  pyriform  in  outline,  Avith  the 
small  end  of  the  figure  twisted  upward.  Its  length  is  about  twelve  inches,  and  its 
width  four  to  five  inches.  The  distance  between  its  two  orifices  varies  from  three 
to  six  inches.  Its  average  capacity  is  about  five  pints  (two  to  three  litres).  It 
weighs  four  ounces  and  a  lialf. 

There  are  two  orifices,  two  borders,  and  two  surfaces  to  be  noticed.  The  left, 
splenic,  or  cardiac  end  of  the  viscus  is  much  expanded,  and  forms  the  great  rul-de- 
snc  or  fundus.  At  the  right  or  pyloric  end  there  is  another  slighter  ex])ansion, 
called  the  antrum  pylori  or  small  cul-de-sac  (fig.  566). 

The  cardiac  orifice,  by  which  the  oesophagus  opens  into  the  stomach,  is  situ- 
ated about  three  inches  from  the  left  extremity,  owing  to  the  bulging  to  the  left  of 
the  great  cid-de-sac.  Tlie  pyloric  orifice,  or  pylorus,  is  situated  to  the  extreme 
right,  and  is  more  anterior  in  i)osition  tlian  the  canHac  orifice. 

The  pylorus  is  jiroduced  ])y  a  thickening  of  the  visceral  walls  l)etween  the  duo- 
denum and  stomach.  The  circular  muscular  fibres  which  surround  the  stomacli 
are  here  thickened  into  a  strong  ring,  thus  forming  a  sphincter  which  can  be  felt 
from  the  outside.  The  longitudinal  fibres  pass  over  the  circular  fibres,  and  are  not 
generally  supposed  to  take  ])art  in  the  thickening.  The  mucous  membrane  is 
pushed  in  by  the  muscular  ring  and  also  thickened.  The  pyloric  opening  will 
hardly  admit  a   sixpence,   its    fullest  diameter  being  about  one-half   of  an  inch 


THE  STOMACH 


9()1 


(loMiiu.)-  It  is  the  narrowest  jmrt  of  the  difrcstive  cnnal.  Tlicrc  is  no  siuli 
special  s])liinct('r  apparatus  at  the  ("inline  end  of  thestomacli.  tlic  ri-soplia<.'Us  passing' 
directly  into  its  walls,  and  hecominii:  wider  as  it  does  so.  \\'lien  the  stoniaeli  is  dis- 
tended the  fjullet  may  become  a  little  l)ent  at  its  jimctif)n  with  the  stomach,  and 
the  escape  of  fhiiil  into  the  esophagus  be  thus  i)revented. 

The  two  borders  are   situated  above  and    below,    and    run   l)etween  the   two 


Fiu.  566. — PosTEraoK  Surfack  of  the  Stomach. 

CARDIAC  ORIFICE 


ANTRUM  PYLORI 


orifices.  Tlic  upper  is  known  as  the  lesser  curvature,  and  is  about  three  to  tive  inches 
long;  it  is  concave  along  its  whole  length,  except  near  the  pylorus,  where  it  takes 
l^art  in  the  antrum  pylori  (fig.  567).  The  lower  border  is  called  the  greater  curva- 
ture, and  is  convex  except  near  the  right  extremity  just  before  the  formation  of  the 
antrum  pylori,  where  there  is  a  slight  depression.  It  is  about  four  times  as  long  as 
the  upper  l^order. 

Fig.  567. — Anterior  Surface  of  the  Stomach. 
pylorus  cardiac  orifice 


ANTRUM  PYLORI 


The  two  surfaces  lie  between  the  two  borders.  They  are  of  equal  extent,  and 
are  named  the  antiriorand  ])(>sterior  surfaces. 

Relations  to  surrounding  parts. — The  degree  of  obliquity  of  the  stomach  in 

its  relations  to  the  long  axis  of  the  body  has  been  a  disjiuted  j>oint.  the  majority  of 

authorities  holding  that  it  lies  slightly  obli(|Uely  from  left  to  rijrht:  wliile  a  few 

(Luschka  and  T.esshaft )  maintain  that  its  dirt  ction  is  vertical.      In  an  earlv  period 

61 


962 


THE   ORGAXS   OF  DIGESTION 


of  devc'lopmeiit  the  orsan  is  certainly 
may  be  maintained  throughout  life. 


vertical,  and  in  rare  instances  this  position 
As  a  rule,  however,  the  organ  is  placed 
obliquely,  and  lies  in  the  left  hypochondriac  and  epigastric  regions  (figs.  578,  582, 
and  58o).  Its  position,  under  normal  conditions,  must  be  liable  to  much 
variation. 

The  cardiac  end,  or  fundus,  reaches  as  high  as  the  level  of  the  sixth  chondro- 
sternal  articulation,  being  a  little  above  and  behind  the  heart  apex.  The  cardiac 
orifice  is  opposite  the  seventh  left  costal  cartilage,  and  is  about  one  inch  from  the 
sternum.  Behind,  it  is  about  on  the  level  Avith  the  body  of  the  tenth  or  eleventh 
dorsal  vertebra.  The  pylorus  is  on  a  lower  level  and  nearer  the  surface  than  the 
cardiac  end,  and  is  opposite  a  point  to  the  right  of  the  middle  line  two  to  three 
inches  below  the  sterno-xiphoid  articulation,  on  the  level  of  a  line  drawn  between 
the  bony  ends  of  the  seventh  ribs  (fig.  582).  Behind,  it  is  on  a  level  with  the 
twelfth  thoracic  spine  (fig.  583).  Its  position  is  nmch  influenced  Ijy  the  state 
of  distension  of  the  stomach. 

Tiie  posterior  sxirface  of  the  stomach  looks  backwards  and  downwards,  lying  on 
the  transverse  meso-colon,  spleen,  splenic  arter}^,  pancreas,  left  kidney  and  supra- 
renal capsule,  and  great  abdominal  vessels  (figs.  586,  590). 


Above. 
Liver,  small  omentum,  diaphragm. 


Ix  Feont. 

(From  left  to  right.) 

Diaphragm,    abdominal   wall, 
liver. 


GENERAL  RELATIONS 

OF  THE 

STOMACH 


Behind. 

Trausverse  meso-colon,  pancreas, 
crura,  solar  plexus,  great  ves- 
sels, spleeu,  left  kidney,  and 
capsule. 


Below. 
Great  omentum,  transverse  colon,  gastro-splenic  omentum. 


The  anterior  surface  looks  upwards  and  forwards.  Its  relations  are  of  import- 
ance in  connection  with  the  operation  of.  gastrostomy.  A  certain  portion  of  this 
surface  comes  into  immediate  contact  with  the  abdominal  wall;  this  portion  is 
triangular  in  shape,  is  bounded  on  the  right  by  the  edge  of  the  liver,  and  on  the 
left  by  the  cartilages  of  the  eighth  and  ninth  ribs;  and  below  by  a  horizontal  line 
passing  between  the  tips  of  the  tenth  costal  cartilages  (fig.  582).  Besides  the 
abdominal  wall,  this  surface  is  covered  by  the  diaphragm  and  the  under  surface  of 
the  left  lol)e  of  the  liver  (fig.  590). 

Relations  to  the  peritoneum, — The  stomach  is  covered  by  peritoneum  in  its 
whole  extent,  except  immediately  along  the  curvatures  and  upon  a  small  triangular 
space  at  the  back  of  the  cardiac  orifice,  where  the  viscus  lies  in  direct  contact  with 
the  diaphragm  and  possibly  with  the  upper  part  of  the  left  supra-renal  capsule. 
It  is  enclosed  between  two  layers.  These  two  layers  at  its  upper  border  or  lesser 
curvature  come  together  to  form  the  lesser  omentum,  and  at  the  lower  border  or 
greater  curvature  extend  downwards,  to  form  the  great  omentum  (figs.  562,  563). 
At  the  left  of  the  oesophagus  the  two  layers  pass  to  the  diajihragm,  forming  the 
gastro- phrenic  ligament;  and  at  th(^  fundus  they  pass  on  to  the  sjileen,  forming  the 
gastro-splenic  omentum. 

Alteration  of  position. — When  the  stomach  is  em])ty  the  surfaces  are  flat 
and  the  ])yl()rie  end  is  situated  near  the  median  plane  and  under  cover  of  the  liver. 
As  it  distends,  it  occupies  the  left  dome  of  the  diaphragm  and  tilts  up  the  heart 
apex.  Moreover,  it  undergoes  some  alteration  in  position.  The  greater  curvature 
is  elevated  and  carried  forwards,  the  anterior  surface  is  directed  u}) wards,  and  the 
posterior  downwards,  and  the  pylorus  ]iasses  some  inches  to  the  right.  The  pyloric 
orifice,  which  in  the  empty  stomach  looks  to  the  right,  is  so  turned  as  to  look  back- 


THE  STOMACH 


968 


wards.      This  rcjtatioii   al)<)Ut  its  long  axis  is  inlluciiccd  hy  the  tixitv  <tf  the  Icsst-r 
curvature  of  the  ortran. 

Structure. — TIk-  Avails  of  the  stomach  consist  of  four  coats, — serous,  muscular, 
sultnnicous,  and  mucous. 


Fig.  568. — MrsciLAK  Coat  of  the  .^tomacii.     (Luschka.) 


LONGITUDINAL  LAYER 


CIRCULAR  LAYER 


The  external  serous  coat  is  formed  by  the  peritoneum,  and  has  to  the  naked  eye 
the  usual  shiny  appearance  of  that  membrane. 
The  muscular  coat  consists  of  three  layers: 
A  longitudinal  layer  externally,  which  is  continued  from  similar  fibres  on  the 


Fig.  569. — MuscuLAE  Coat  of  the  Stomach.     (Luschka.) 

OBLIQUE   UYER 


T 


ft 


CIRCUUR  UYER 


oesophagus,  and  is  thickest  along  the  curvatures,  more  ]iarticularly  tlie  lesser.     At 
the  pylorus  the  fibres  are  more  regularly  placed  round  that  orifice  (fig.  .508). 

A  circular  lai/er.  which  regularly  surrounds  the  whole  stomach  and  becomes 
much  thicker  at  the  pyloric  end.  where  it  forms  the  sphincter.  These  circular 
fibres  are  arranged  perpendicularly  to  the  long  axis  of  the  stomach  (fig.  560). 


964  THE   ORGANS    OF  DIGESTION 

An  oblique  l((i/er,  continuous  with  the  circular  fibres  of  the  oesophagus.  They 
pass  tt)  the  left  of  the  a'sophagus  towards  the  great  curvature.  They  unite  finally 
with  the  circular  fibres  (fig.  560 ). 

The  submacouti  coat  is  made  up  of  areolar  tissue,  in  which  tlu"  ])l()()d-vessels 
break  up. 

The  mvcou--<  or  internal  coat  is  pink  in  colour  and  soft  to  the  touch,  and  when 
the  stomach  is  not  distended  has  a  rugose  appearance.  It  is  covered  Avith  colunmar 
epithelium,  and  with  a  lens  shows  the  openings  of  numerous  glands.  A  thin  layer 
of  muscular  tissue — the  musadaris  mucosx — supports  the  mucous  memlDrane  ex- 
ternally. The  mucous  membrane  is  thickest  in  the  pyloric  area  and  thinnest  over 
the  great  cnl-clc-mc.  In  the  stomachs  of  young  persons  the  surface  of  the  stomach 
may  l)c  studded  by  little  elevations  due  to  local  accumulations  of  lymphoid  tissue. 

Nerves. — The  nerves  of  the  stomach  are  the  right  and  left  pneumogastric,  the 
right  nerve  passing  over  the  posterior  surface,  and  the  left  over  the  anterior.  The 
organ  is  also  connected  Avith  the  sympathetic  SA'stem  l:>y  means  of  the  solar  j^lexus. 

Blood-supply. — The  stomach  receives  its  blood-supply  from  many  branches. 
From  the  cieliac  axis  there  is  the  gastric  artery,  which  runs  along  the  lesser  curve 
from  left  to  right,  anastomosing  with  the  pyloric  branch  of  the  hepatic.  Along  the 
greater  curve  run  the  right  and  left  gastro-epiploic  arteries,  anastomosing  at  the 
middle  of  the  border,  the  left  being  a  branch  of  the  splenic,  the  right  a  branch  of 
the  hepatic  through  the  gastro-duodenal  artery.  The  stomach  also  receives 
l)ranches  from  the  splenic  (vasa  brevia)  at  the  fundus. 

The  blood  of  the  stomach  is  returned  into  the  portal  vein.  The  coronary  vein 
and  pyloric  vein  open  separately  into  the  portal  vein;  the  right  gastro-epiploic  vein 
opens  into  the  superior  mesenteric,  the  left  into  the  splenic. 

Lymphatics. — There  is  a  set  of  glands  lying  along  the  greater  and  the  lesser 
curvatures,  and  others  at  the  pyloric  and  cardiac  ends.  These  are  entered  l)y 
lymphatic  vessels  beginning  in  the  mucous  membrane. 


THE  INTESTINES 

THE   SMALL    INTESTINE 

The  small  intestine  is  that  part  of  the  intestinal  canal  w-hich  lies  between  the 
pylorus  and  the  ileo-ciccal  valve.  It  is  conveniently  divided  into  three  portions: 
the  duodenum,  jejunum,  and  ileum.  It  is  of  the  average  length  in  the  adult 
male  (between  the  ages  of  twenty  and  fifty)  of  tw^enty-two  feet  six  inches.  In  the 
female  it  is  longer,  the  average  length  being  twenty-three  feet  four  inches.  The 
length  is  inde|)endent,  in  the  adult  at  least,  of  age,  height,  or  weight.  The  length 
may  vary  in  the  male  from  thirty-one  feet  ten  inches  to  fifteen  feet  six  inches.  In 
the  female,  from  twenty-nine  feet  four  inches  to  nineteen  feet  ten  inches. 

With  the  exception  of  the  duodenum,  the  small  intestine  lies  for  the  most  part 
inside  the  more  fixed  portions  of  the  large  intestine  (figs.  565,  578).  It  is  also, 
with  the  exce]ition  of  the  duodenum,  connected  to  the  posterior  abdominal  wall  by 
a  process  of  ])eritoneum,  the  meMntery.  This  broad  membrane  is  seen  to  extend 
from  above  downwards,  and  from  left  to  right  from  the  duodenum  above  totheileo- 
ca?cal  valve  below,  enclosing  tlic  jejunum  and  ileum  along  the  wliole  of  their  ex- 
tent (figs.  561,  568,  and  599). 

The  duodenum — the  first  portion  of  the  small  intestine — is,  unlike  the  otl)er 
parts  of  that  bowel,  very  definite  in  position  and  extent.  It  is  that  part  which  is 
not  contained  by  the  mesentery.  It  is  formed  from  the  end  of  the  embryonic  fore- 
gut,  and  its  peculiar  position  V)ehind  the  transverse  colon  is  due  to  the  rotation  from 
left  to  right  of  the  intestine  in  the  foetus  (page  995).  It  is  the  most  fixed  as  well 
as  the  widest  part  of  the  small  intestine.     It  measures  one  and  a  half  to  two  inches 


THE  SMALL    INTESTINE 


965 


in  (liaiuctcr,  and  is  al)()ut  ten  inches  lon-r.  Tt  lias  been  compared  in  general  sliajjc 
to  a  liorsc'shoc,  though  not  very  aptly,  as  the  one  side  is  so  much  hjiiger  than  the 
other.  It  is  arranged  in  a  curved  manner  round  the  pancreas,  and  readily  lends 
itself  to  a  division  into  four  parts  (tig.  577). 

Tlie  Jird  part — the  superior,  or  a>icendin(j — is  hardly  t\V(j  inches  long.  Begin- 
ning at  tlie  ])yl()rus,  and  passing  upwards  and  backwards  to  the  right,  it  ends  at  the 
neck  of  the  gall-bladder.  It  is  the  most  moval)le  of  tlie  four  portions.  It  is 
covered  l)y  the  two  layers  of  peritoneum  which  are  continued  from  the  stomach,  and 
by  these  it  is  completely  surrounded  in  front,  but  is  only  covered  behind  in  the 
vicinity  of  the  pylorus.  Above  it  are  found  the  liver  (quadrate  lobe)  and  gall 
l)ladder.  The  gut  itself  forms  the  lower  boundary  of  the  foramen  of  Winslow. 
Below  it  is  the  pancreas;  and  behind  are  the  common  bile-duct,  hepatic  vessels  and 
portal  vein. 

The  second  jxirt — the  descendiiuj  portion — not  (luite  three  inches  long,  extends 
from  the  neck  of  the  gall  l)ladder  t(j  the  third  lumljar  vertebra,  a  short  bend  mark- 
ing the  separation  between  the  first  and  second  ])arts.  This  part  is  covered  In- peri- 
toneum in  front  only,  the  memljrane  l)eing  derived  from  a  continuation  of  the 
•superior  layer  of  the  transverse  meso-colon  (fig.  570). 

Fig.  570. — The  Duodenum  from  ik  front. 

superior  layer  of  transverse  meso-colon 


SECOND  PART  OF 
DUODENUM 


FOURTH  PART  OF  DUODENUM 


INFERIOR  LAYER  OF  TRANSVERSE  MESO-COLON 

THIRD  PART  OF  DUODENUM 


SUPERIOR  MESENTERIC  VESSELS 


It  is  more  fixed  than  the  first  portion.  It  is  in  relation  in  front  with  the  trans- 
verse colon  and  meso-colon.  On  its  leftside  is  the  pancreas  (fig.  577),  and  the 
common  l)ile-duct  a  little  more  i)osteriorly.  The  looj)  formed  by  the  pancreatico- 
duodenal arteries  runs  also  along  the  left  margin  of  this  part  of  the  bowel. 

Behind  lie  tlie  right  kidney  and  the  renal  vessels  and  vena  cava  (fig.  590). 

Some  of  the  nmscular  fibres  of  this  part  of  the  duodenum  are  said  to  be  continu- 
ous with  the  lobules  of  the  pancreas.  Into  this  segment  of  the  bowel,  at  its  inner 
and  back  part  and  some  four  inches  from  the  ]\vlorus  tlie  common  bile-duct  and 
pancreatic  duct  enter  (figs.  571,  58(5,  and  587). 

The  tJiird  part,  or  tranxrcrxe  portion,  is  the  longest,  l)eing  al)out  five  inches  long. 
It  extends  from  the  body  of  the  third  luml)nr  vertebra  on  the  right  side,  and  ]>asses 
ol)li(]uely  across  the  spine  to  the  ujijier  ])art  of  the  left  side,  ascending  a  little  on 
its  way.  In  front  of  the  third  part  of  the  duo<lenum  is  found  the  lower  layer  of 
the  transverse  meso-colon.  The  su])crior  mesenteric  vessels  cross  this  part  of  the 
bowel,  running  lietween  it  and  the  pancreas  to  reach  the  mesentery  (fig.  570). 
Along  the  ujiper  Ijorder  runs  the  inferior  pancreatico-duodenal  artery.  The  gut  is 
in  relation  above  with  the  pancreas  and  su]ierior  mesenteric  artery.  Behind  are 
the  vena  cava,  aorta,  and  crura  of  the  dia|)hragm  (figs.  571,  577).  It  is  the  most 
fixed  portion  of  the  duodenum,  and  is  covered  in  front  only  by  |)eritoneum. 


966 


THE   ORGAXS   OF  DIGESTION 


The  fourth  part  of  the  duodenum,  or  second  ascending  portion,  ascends  vertically 
by  the  left  side  of  the  spine.  This  vertical  portion — which  is  covered  entirely  iii 
front  and  i)artly  at  the  sides  by  peritoneum — is  at  least  an  inch  in  length  (figs.  570, 
571,  and  572).  The  end  of  the  duodenum  is  very  firndy  fixed  in  its  place  by  the 
muscidus  suspensorius  daodeni.  This  name  has  been  given  to  a  fibrous  band  that 
contains,  according  to  Treitz,  some  plain  muscular  fibres,  and  that  descends  to  the 

Fig.  571.— The  Diuukxum  fkom  behind. 

Portal  vein 


COMMON  BILE 
DUCT 


FOURTH  PART  OF  DUODENUM 


HEAD  Of  PANCREAS 


vertical  part  of  the  duodenum  from  the  left  crus  of  the  diaphragm  and  the  tissues 
about  the  coeliac  axis. 

Mr.  Lockwood  points  out  that  this  band  is  continued  on,  after  being  inserted 
into  the  duodenum,  between  the  layers  of  the  mesentery.  He  suggests  the  name 
of  the  *  suspensory  muscle  of  the  duodenum  and  mesentery, '  and  snys,  '  together 
Avith  the  other  constituents  of  the  root  of  the  mesentery,  it  forms  a  band  of  con- 


FiG.  572. — The  Fossa  Duodeno-jejunalis.      (Treves.; 
'^R^^^svERSE  colow 


THE  DUODENAL 
FOLD 


Inferior  mesenteric 
rein 


sidcrable  strength,  sufticicnt  not  only  to  support  the  weiglit  of  tlic  intestines  and 
mesentery,  but  also  to  resist  the  pressure  of  the  descent  of  the  diaphragm.' 

In  coimection  with  the  termination  of  the  duodenum  may  be  mentioned  the 
fossa  duodeno-jejunalis.  It  is  formed  as  a  pouch  behind  a  fold  of  peritoneum. 
Tliis  fold  runs  from  tlie  parietal  peritoneum,  just  to  tlic  left  of  the  terminal  or 
fourth  part  of  tlie  duodenum,  and   is  attaclicd   in  n  vertical   line  to  the  anterior 


I 


THE  SMALL   IXTESTiyE  967 

h^iirface  of  this  portion  of  the  bowel.      It  i.-;  <>t"  interest  as  1)eing  the  seat  of  origin 
oi  a  retroperitoneal  hernia. 

The  fold  forming  the  fossa  is  the  remains  of  the  'duodenal  fold,'  modified  by 
growth  and  disjilaeed  by  the  ])roeess  of  unequal  development  in  the  intestinal  eanal 
(page  1003  and  ligs.  (iOo,  (300).  The  jjoeket,  or  fossa,  is  of  triangular  outline, 
with  the  base  or  orifiee  upwards.  Its  apex  extends  below  the  last  bend  of  the 
duodenum  (fig.  572).  The  capacity  of  the  fossa  varies.  In  -well-marked  speci- 
mens it  will  lodge  the  thumb  up  to  the  first  joint.  It  is  actually  occupied  \^y  the 
duodcno-jejunal  junction  or  bend.  Out  of  on(.'  hundred  Ijodies  examined,  I  found 
this  fossa  in  forty-eight  examjjlcs. 

Jejunum  and  ileum. — There  is  no  unvarying  method  in  the  arrangement  of 
tlie  individual  coils  of  the  small  intestine. 

In  the  majority  of  adult  bodies  the  small  intestine  is  disposed  in  an  irregularly 
curved  manner  from  left  to  right.  The  gut,  starting  from  the  duodenum,  will  first 
occupy  the  contiguous  parts  of  the  left  side  of  the  epigastric  and  umbilical  regions; 
the  coils  then  fill  some  part  of  the  left  hypochondriac  and  luml)ar  regions;  they 
now  commonly  descend  into  the  pelvis,  reappearing  in  the  left  iliac  quarter,  and 
then  occupy,  in  order,  the  hypogastric,  lower  umbilical,  right  luml)ar,  and  right 
iliac  regions.  Before  reaching  the  last  situation  they  commonly  descend  again  into 
the  pelvis. 

In  many  instances  no  kind  of  methodical  arrangement  is  apparent.  The  coils 
of  small  intestine  most  usually  found  in  the  pelvis  belong  to  the  terminal  part  of 
tlie  ileum,  and  to  that  part  of  the  intestine  that  has  the  longest  mesentery — the 
part,  namely,  that  extends  between  two  points,  respectively  six  and  eleven  feet 
from  the  end  of  the  duodenum.  In  five  out  of  one  hundred  cases  examined,  the 
coils  were  arranged  in  an  exactly  reverse  manner  to  that  just  described. 

The  jejunum  (jejunvs,  empty). — The  jejunum  is  the  name  given  to  the  upper 
two-fifths  of  the  small  intestine  Ijelow'  the  duodenum. 

The  term  ileum  (eUstv,  to  twist)  is  api:)lied  to  the  last  three-fifths  of  the  l)owel. 
The  ileum  ends  at  the  ileo-cajcal  valve.  The  coils  formed  by  the  jejunum  and 
ileum  are  ver\^  movable,  are  completely  invested  by  peritoneum,  and  are  supported 
and  attached  to  the  posterior  parietes  by  the  extensive  membrane  known  as  the 
mesentery. 

The  intestine  alters  gradually  in  character  from  above  dowuAvards.  If  a  segment 
from  the  middle  of  the  jejunum  be  compared  Avith  a  portion  of  the  middle  ileum, 
tlie  following  differences  would  be  noted.  The  diameter  of  the  jejunum  is  about 
an  inch  and  a  half,  that  of  the  ileum  one  and  a  quarter.  The  jejunum  has 
thicker  walls,  is  more  vascular,  and  is  provided  with  a  more  complex  mucous 
membrane. 

Meckel's  diverticulum, — From  one  to  three  feet  from  the  end  of  the  ileum 
is  sometimes  seen  a  diverticulum,  or  l)lind  tube  or  cord,  coming  off  from  the  free 
margin  of  the  bowel.  This  is  Meckel's  diverticulum,  and  represents  the  remains 
of  the  vitello-intestinal  duct  (page  994). 

The  mesentery. — The  mesentery  extends  from  the  end  of  the  duodenum  to  the 
ileo-ctecal  junction.  It  envelopes  and  supports  the  ileum  and  jejunum.  Its  upper 
or  right  layer  is  continuous  with  the  under  layer  of  the  transverse  meso-colon  and 
with  tlie  jieritoneum  that  invests  the  ascending  colon.  Its  lower  or  left  layer  joins 
with  the  serous  membrane  that  encloses  the  descending  colon  and  that  forms  the 
sigmoid  mesentery  (fig.  5G1). 

The  point  at  which  the  mesentery  is  attached  above  is  on  a  level  with  the  lower 
l)order  of  the  pancreas  and  just  to  the  left  of  the  vertebral  bodies.  From  this  point 
the  insertion  of  the  mesentery  follows  an  oblirpie  line  that  runs  downwards  and  to 
the  right,  crossing  the  great  vessels,  and  ending  in  some  part  of  the  iUac  fossa  (fig. 
599).  In  the  al)sence  of  an  ascending  meso-colon  (the  normal  condition)  the  peri- 
toneum that  covers  the  ca?cum  is  reflected  from  tlie  hinder  surface  of  that  part  of 
the  bowel  fm  to  the  posterior  parietes;  at  this  reflexion  the  mesentery  ends.  If  an 
ascending  meso-colon  exi.«!ts,  the  mesentery  terminates  by  joining  it.  The  parietal 
attachment  of  the  mesentery  measures,  as  a  rule,  about  six  inches  ffig.  509).  The 
length  of  the  mesentery  from  the  spine  to  the  intestine  varies  in  dift'crent  parts  of 
the  canal;  its  average  length  ni;iv  betaken  ;is  liefwecn  eiL'lit  and  nine  inches.      It 


968 


THE   OEGAXS   OF  DIGESTIOX 


soon  attains  its  full  length,  and  within  one  foot  of  the  end  of  the  duodenum  is 
already  six  inehes  in  length. 

The  ordinary  type  of  mesentery  conforms  to  the  figure  of  half  a  circle,  ))Ut  the 
membrane  is  lial>ie  to  considerable  variation.  It  is  not  unconnnon  to  find  the 
mesentery  maintaining  a  considerable  length  up  nearly  to  the  end  of  the  ileinn. 

Structure  of  the  small  intestine. — Its  coats  are  four  in  number — viz.,  serous, 
muscular,  areolar,  and  mucous.  The  intestine  receives  its  serous  covering  from  the 
peritoneum,  and,  with  the  exception  of  certain  parts  of  the  duodenum  which  have 
l)een  described,  it  is  covered  entirely  by  it,  save  only  where  the  layers  leave  it 
behind  to  form  the  mesentery.  The  line  of  attachment  of  the  mesentery  marks 
the  attached  border  of  the  small  intestine. 

The  mu-n-ulnr  coat  is  divided  into  an  external  longitudinal  layer  and  an  internal 
circular,  the  circular  being  the  thicker  of  the  tAvo.  Both  layers  are  uniform  around 
the  liowel,  and  l)ecome  thinner  as  the  crecum  is  approached. 

The  areolar  or  submucous  coat  consists  of  areolar  tissue  connecting  the  muscular 
and  mucous  tunics.  A  thin  layer  of  muscular  tissue  separates  the  mucous  mem- 
brane from  the  areolar  coat  (muscularis  mucosae). 

The  mucous  coat,  thicker  at  the  upper  part  than  the  lower  part,  is  lined  through- 
out with  colunmar  epithelium  and  is  very  vascular.     The  Avhole  surface  is  covered 


Fig.  57:1 


-PORTIOX   OF  THE  SmAI.I.   INTESTIXE,    LAID  OPEX  TO  SHOW   THE 

Valvule  Coxniventes.    (Biintou.) 


Avith  minute  jjrocesses  called  villi ;  these  give  the  membrane  a  finely  flocculent 
apj>earance,  which  has  been  compared  to  the  pile  of  velvet.  They  are  largest  and 
most  numerous  in  the  duodenum  and  jejunum,  and  become  gradually  shorter, 
smaller,  and  fewer  on  the  ileum.  Besides  the  villi  are  certain  large  folds  or  valvu- 
lar flaps:  these  are  the  valvule  conniventes.  They  are  permanent  crescentic  folds  of 
mucous  membrane  set  transversely  to  the  long  axis  of  the  intestine.  The  majority 
extend  from  one-half  to  two-thirds  of  the  distance  round  the  lumen  (tig.  573).  The 
largest  are  more  than  two  inches  long,  and  al)out  one-third  of  an  inch  wide.  Some 
of  the  valvula?  conniventes  form  complete  circles  and  others  spirals.  These  mucous 
folds  do  not  exist  at  the  beginning  of  the  duodenum.  They  are  very  large  just 
Ix'low  the  entrance  of  the  Inle-duct,  and  remain  conspicuous  until  the  middle  of  the 
jejunum  is  reached.  They  then  become  smaller,  and  gradually  disa])pear  at  the 
lower  part  of  the  ileum. 

Scattered  over  the  whole  of  the  mucous  membrane  of  the  small  intestine  are 
numerous  minute  soft  rounded  bodies  composed  of  retiform  tissue.  These  are  the 
so-called  solitary  glands. 

Certain  patches,  called  reijer\s  patches,  are  found  in  the  lower  ileum.  They  are 
oval,  are  from  one-half  to  three  inches  in  length,  and  about  one  inch  in  breadth, 
and  are  placed  in  the  long  axis  of  the  bowel  along  a  line  most  remote  from  the 
mesentery.     They  are  made  up  of  an  aggregation  of  solitarv  glands. 


THK  LARGE  IXTESTLXE 


9G9 


A  number  of  closely  set  acino-tulnilar  <;lands,  called  Brunner^s  glanch,  iiiav  lu' 
exjtosed  l»y  dissection  in  the  tirst  ])art  of  the  duodenum. 

Blood-supply  of  the  small  intestine. — The  small  intestine  receives  its  blond 
from  the  su])(.'ri(»r  URSt-ntt-'ric  artery,  and  a  branch  coming  indirectly  from  the 
liei)atic,  the  superior  pancreatico-duodenal.  The  superior  mesenteric  runs  between 
the  layers  of  the  mesentery,  and  uives  off  about  twelve  or  fifteen  branches,  runniujr 
downwards  and  to  the  left  (vasa  intestini  tenuis ),  which  l)reak  uj)  and  form  a  series 
of  arches,  finally  eiicirclinir  the  intestine  as  small  branches.  It  also  gives  off  a 
small  branch  at  the  beginning,  the  inferior  pancreatico-duixlenab  which,  with  the 
superior  pancreatico-duodenal,  forms  an  arch,  which  lies  in  the  concavitv  of  the 


Fig.  574. — Ve.ssels  of  the  Smalt.  Intestine. 


\'eins 


duodenum  and  supplies  it.  The  blood  is  returned  liy  means  of  the  sui>eri(jr 
mesenteric  vein,  which  with  the  si)lenic  vein  forms  the  portal  (tig.  574). 

The  lymphatics  form  a  continuous  series,  which  is  divided  into  two  sets — viz., 
tliat  of  the  mucous  membrane  and  that  of  the  muscular  coat.  The  lymph-vessels 
(if  l)oth  sets  form  a  copious  plexus  and  end  in  the  mesenteric  lacteals  (fig.  574). 

The  nerves. — The  small  intestine  is  sui)i)lied  by  means  of  the  sujjerior 
mesenteric  jilexus,  which  is  continuous  with  the  lower  part  of  the  solar  plexus. 
The  brandies  follow  the  blood-vessels,  and  finally  form  two  plexuses:  one  (Auer- 
'-ach's)  which  lies  between  the  muscular  coats;  and  another  (^leissner's)  in  the 
submucous  coat. 


THE  i.ar(;e  intestine 

The  large  intestine  is  that  i)art  of  the  alimentary  canal  which  extends  between 
the  ileum  and  the  anus.  It  is  divided  into  the  following  ])arts:  Ca-cum,  ascending, 
transverse,  and  descending  colon,  sigmoid  flexure,  and  rectum.  It  is  so  arranged 
as  to  surround  the  small  intestine,  making  a  circuit  round  the  alKlominal  cavity 
from  right  to  left  (fig.  565).  The  coscuni  lies  in  the  right  iliac  fossa;  thence  the 
colon  passes  vertically  upwards  on  the  right  side  (ascendini/  colon)  until  the  liver 
is  reached.  Here  it  forms  a  more  or  less  rectangular  bend  (hepatic  flexure),  and 
then  passes  transversely  acro-ss  the  belly  (transverse  colon)  below  the  stomach.  It 
then  reaches  the  splenic  area,  where  it  makes  a  second  shariil)end  f  splenic  flexure), 
and,  pa.ssing  vertically  downwards  on  the  left  side  (drxirwUnci  calon),  reaches  the 
left  iliac  fossa.  At  this  point  it  forms  the  looji  of  the  s'ujmoiil  flexure,  and  finally 
passes  through  the  pelvis  as  the  n^ctum  (fig.  577).  It  is  much  larger  in  diameter 
than  the  small  intestine,  and  has  not  the  same  general  convoluted  arrangement. 
Leaving  out  of  consideration  the  dilated  portion  of  tbi'  rectmn    it  is  wid.  i-  .it  tho 


970 


THE   ORdAXS   OF  DIGESTION 


beiiinniiiif  than  at  the  rml.  It  varies  in  width  at  different  parts  from  two  and  a 
half  to  one  and  a  quarter  inehes.  The  length  from  the  root  of  the  a})pendix  or 
tip  of  the  eteeum  to  the  point  where  the  meso-reetum  ends  is,  in  the  male,  about 
four  feet  eight  inches,  and  in  the  female  about  four  feet  six  inches. 

The  extremes  found  in  a  number  of  cases,  were  for  both  sexes  respectively,  six 
feet  six  inches,  and  three  feet  three  inches. 

The  large  intestine,  in  all  parts  except  the  rectum,  has  a  peculiar  arrangement 
of  its  walls,  which  gives  it  a  very  different  appearance  from  the  small  intestine. 
It  is  mcculdted,  and  the  sacculation  is  produced  by  the  gut  having  to  adopt  its 
length  to  three  shorter  muscular  bands  which  run  the  course  of  the  intestine. 
These  bands,  which  are  about  12  mm.  wide  and  1  nnii.  thick,  are  really  the  longi- 
tudinal tibres  of  the  muscular  wall,  which  are  chiefly  collected  at  three  parts  (fig. 
575).  One  band  is  situated  podcriorhj  on  the  attached  border,  another  runs  onte- 
riorly,  and  the  third  is  situated  on  the  inner  side  of  the  ascending  and  descending 
colon,  and  on  the  lower  border  of  the  transverse  colon.  All  these  bands  start  at 
the  vermiform  appendix,  and  are  lost  on  the  rectum.  Along  the  Avhole  length  of 
the  large  intestine,  except  the  lower  part  of  the  rectum,  are  certain  small  append- 
ages (appendices  epiploicas),  seen  mostly  along  the  line  of  the  inner  muscular  band. 
They  are  ])ouches  of  peritoneum  containing  fat. 

The  caecum,  or  caput  coli. — The  caecum  is  a  cul-de-S(tc  forming  the  first  part 
of  the  large  intestine.      It  is  defined  as  that  part  of  the  colon  which  is  situated 

Fig.  575.— The  Four  Types  of  C^cum.     (Treves.) 
ABC  D 


below  the  entrance  of  the  ileum.  Its  breadth  is  about  three  inches,  and  its  length 
about  two  and  a  half  inches. 

It  lies  in  the  right  iliac  fossa,  and  is  usually  situated  upon  the  psoas  muscle, 
and  so  ]>laced  that  its  apex  or  lowest  ]ioint  is  just  projecting  lieyond  the  inner 
border  of  that  inner  muscle  (figs.  565,  577).  It  is  entirely  enveloped  in  perito- 
neum, and  is  free  in  the  abdon)inal  cavity.  The  apex  of  the  caecum  usuallv  cor- 
responds with  a  point  a  little  to  the  inner  side  of  the  middle  of  Poupart's  ligament. 
Less  frequently  the  ctecum  will  be  found  to  be  in  relation  with  the  iliacus  musch^ 
only;  or  the  bulk  of  the  caput  will  lie  upon  that  nmscle,  while  the  apex  rests  u]»on 
the  psoas.  In  a  number  of  cases  the  caecum  is  entirely  clear  of  both  psoas  and 
iliacus  muscles,  and  hangs  over  the  pelvic  brim,  or  is  lodged  entirely  Avithin  the 
jielvic  cavity.  Some  part  of  the  ca)cum  may  pass  even  to  the  left  of  the  median 
line  of  the  body. 

This  part  of  the  colon  is  liable  to  consideral)le  variation. 

Its  rnriation.<i  may  be  described  under  Jmir  typef<  : 

1.  The  foetal  type  is  conical  in  shape,  the  appendix  arising  from  the  apex. 
This  process  is  a  continuation  of  the  long  axis  of  the  colon.  Th(i  three  mustular 
bands  Avhich  meet  at  the  appendix  are  nearly  at  equal  distances  apart  (fig.  575,  A.). 

2.  The  second  form  is  more  fiuadrilateral  in  shape  than  the  last;  the  three  bands 
retain  their  relative  positions;  the  appendix  ap)>ears  l)etwcen  two  bulging  sacculi. 
instead  of  at  the  summit  of  a  cone  (fig.  575,  B. ). 

8.    In  the  third  tyjie.  that  part  of  the  caput  eoli  that  lies  to  the  right  side  of  the 


TllK   LARdE   ISTESTINE  <)71 

anterior  band  grows  out  of  proportion  to  that  part  to  tlie  left  of  tin*  band.  Tlie 
anterior  wall  becomes  more  devi'lopecl  than  the  j)osterior,  so  that  the  ajjex  is  turned 
so  mu(!h  to  the  left  and  posteriorly  that  it  nearly  meets  tbe  ileo-eseeal  junction.  A 
false  aj>ex  is  formed  by  the  hiiihly  developed  ])art  to  the  right  of  the  anterior  band. 
This  is  the  usual  can-um  foimd  (iig.  o75,  C. ). 

4.  In  the  fourth  ty))e,  the  develojtment  of  the  part  to  the  right  of  the  anterior 
band  is  excessive,  while  the  segment  to  the  left  of  the  band  has  atrophied.  In  this 
form  the  anterior  band  runs  to  the  inferior  angle  of  junction  of  the  ileum  with  the 
cjecum.  The  root  of  the  appendix  is  jjosterior  to  that  angle.  There  is  no  trace  of 
the  original  apex,  and  the  api)cndix  a])pears  to  spring  almost  from  the  ileo-ca'cal 
junction  (fig.  575,  D. ). 

()ll)cr  variations. — The  ca'cum  may  vary  in  its  general  development.  It  is  some- 
times small  and  insignificant,  in  other  cases  it  reaches  a  large  size.  It  may  be  so 
rotated  that  the  ileum  })asses  behind  the  colon  and  o))ens  on  the  right  side.  The 
posterior  part  has  been  seen  much  more  develo])ed  than  the  anterior,  so  that  the 
ileum  has  entered  from  the  front,  and  the  appendix  has  come  off  from  the  anterior 
wall.  The  ca3cum  may  remain  undescended,  and  be  found  just  under  the  liver  or 
in  the  vicinity  of  the  umbilicus.  The  ca3cum  and  colon  may  be  suspended  by  a 
mesentery  common  to  the  whole  intestinal  canal.  In  such  cases  the  primitive 
condition  of  the  peritoneal  fold  which  supports  the  small  and  large  intestine  is 
permanently  retained  (page  997). 

The  vermiform  appendix. — Attached  to  what  is  really  the  original  ajx'x  of 
the  ca'cum  is  a  narrow,  blind  tube:  this  is  the  vermiform  appendix.  It  usually 
comes  off  close  to  tlie  ileo-ctecal  valve  on  the  inner  and  posterior  side  of  the  bowel, 
though  occasionally  it  forms  the  true  apex  of  the  caecum.  In  the  adult  the  average 
length  is  four  inches,  the  extremes  being  one  inch  and  six  inches.  In  the  majority 
of  instances  the  appendix  is  much  twisted  upon  itself.  Its  usual  position  is  ])ehind 
the  end  of  the  ileum  and  its  mesentery,  and  pointing  in  the  direction  of  the  sjaleen. 
It  may  occasionally  ascend  vertically  behind  the  caecum. 

It  has  a  definite  mesentery,  which  comes  off  from  the  left  layer  of  the  mesentery 
of  the  ileum.  Its  origin  from  this  layer  is  along  a  straight  line  which  is  situated 
at  a  short  distance  from  tlie  intestine,  and  which  is  not  (piite  parallel  with  the 
margin  of  the  liowel.  In  general  outline  the  mesentery  is  triangular.  In  theadidt  it 
does  not  extend  along  the  whole  length  of  the  tube.  It  is,  in  fact,  too  short  for  the 
appendix,  and  it  is  this  that  accounts  for  the  twisted  condition  of  the  little  process. 
Along  the  free  margin  of  the  mesentery  runs  a  branch  of  the  ileo-colic  artery. 

Ileo-caecal  fossa. — About  the  ccecum,  and  especially  in  the  vicinity  of  the  ileo- 
cecal junction,  are  certain  fossse  collectively  knoAvn  as  the  ileo-ca?cal.  Two  only 
appear  to  be  fairly  constant.  The  first,  tlie  svperior  ileo-caecal,  is  formed  by  the 
passage  across  the  junction  of  the  caecum  and  ileum  of  a  l)ranch  of  the  ileo-colic 
artery,  which  produces  a  fold  of  peritoneum  limiting  a  pouch.  It  is  on  the  anterior 
aspect  of  the  bowel,  and  the  pouch  o])ens  downwards. 

The  second  fossa  is  not  (juite  so  simple.  If  the  ca'Cum  l>e  tinnied  u]nvards  so 
as  to  expose  its  posterior  surface  as  it  WoBinsitu,  and  if  the  a]ipendix  be  drawn  down 
so  as  to  put  its  mesentery  on  the  stretch,  a  peculiar  fold  will  be  found  t()  join  that 
mesentery.  This  fold  arises  from  that  border  of  the  ileum  which  is  most  remote 
from  the  insertion  of  its  mesentery.  It  then  passes  over  the  ileo-ca?cal  junction  on 
its  inferior  aspect,  is  adherent  to  the  caecum,  and  finally  joins  the  surface  of  tlie 
mesentery  of  the  apjiendix.  This  fold  is  peculiar  in  tlie  absence  of  any  visible 
vessels.  Between  it  and  the  appendix  there  is  an  almost  constant  fossa,  the  inferior 
ileo-aecal.  It  is  large,  admitting  two  fingers.  It  o]iens  outwards,  and  is  bounded 
on  one  side  by  the  small  intestine,  and  on  the  other  by  the  caxnim. 

The  ileo-caecal  valve. — The  ileo-ca'cal  valve,  which  is  situated  at  the  entrance 
of  the  ileum  into  the  large  intestine  at  the  u])per  border  of  the  ca'Cum,  is  found  on 
the  inner  side  and  towards  the  j)os-terior  asjiect  of  the  intestine.  The  ileum  ])asses 
from  Vielow  ujiwards  and  towards  the  right,  and  terminates  with  a  consideralde 
degree  of  obliquity.  The  valve  is  formed  by  two  semilunar  folds  projecting  into 
the  large  intestine,  the  upper  being  nearly  transverse,  the  lower  being  a  little 
oblique.  The  ojiening  between  them  takes  the  form  of  a  narrow  slit  about  half  an 
inch  in  length,  rounded  in  front  but   narrow  behind.      At  the  ends  of  the  slit  tlie 


972 


THE   ORGANS   OF  DIGESTION 


valves  unite  and  iivo  i)ri)l()n.-rrd  at  either  end  as  a  ridge  partially  surrounding  the 
intestine  (fnena).  Villi  cover  tliat  surface  of  the  folds  looking  towards  the  ileum. 
Tile  surface  towards  the  large  intestine  is  free  from  villi.  In  the  formation  of  this 
valve  the  longitudinal  nuiscular  fibres  pass  across  from  the  ileum  to  the  large 
intestine  without  dipi)ing  down  between  the  two  layers  of  each  fold.  The  circular 
muscular  fibres,  on  the  other  hand,  are  contained  between  the  layer  of  the  mucous 
mcmt)ran(^  and  submucous  tissue  which  form  them. 

The  colon. — In  the  adult  the  ascending  and  the  descending  parts  of  the  colon 
are  i)laced  vertically,  while  the  direction  of  the  transverse  colon  is  i)ractically 
horizontal.  The  average  length  in  the  adult  of  the  ascending  colon  (as  measured 
from  the  tip  of  the  ciecum"  to  the  hepatic  flexure)  is  eight  inches,  and  of  the 
descending  colon  (as  measured  from  the  splenic  bend  to  the  connii  en  cement  of  the 
sigmoid  loop)  is  eight  and  a  half  inches.  The  descending  colon  is  thejiart  of  the 
large  bowel  that  is  least  liable  to  variation.  It  is  the  only  part  of  the  gut  except  the 
duodenum  that  retains  its  original  position  as  a  portion  of  the  great  primary 
vertical  loop.  The  transverse  colon,  on  the  other  hand,  is  liable  to  considerable 
variation   in   length,    position,    and    arrangement.      Its   average   length   is  twenty 


Fig.  57(}.— Section  of  the  Ascending  Colon.     (Allen  Thomson.) 

Crescentic  ridge  of  mucous 

membrane  which  divides  the  sacculi  Longitudinal  muscle 


Serous  coat 

Anterior  band 

Mucous  membrane  7^5y  x^^S Posterior  band 

-  Mucous  membrane 


Crescentic  ridge  of 
mucous  membrane 


Circular  muscle 


Appendix  epiploica 


Crescentic  ridge  of 
mucous  membrane 


Serous  coat 


Inner  band 


Circular  muscle 


inches  in  the  adult.  It  has  been  found  to  vaiy  in  adults  from  twelve  to  thirty- 
three  inches. 

The  ascending  colon. — The  ascending  colon  extends  from  the  ca?cum  to  the 
inferior  surface  of  tht;  liver  external  to  the  gall  bladder,  forming  there  the  hepatic 
flexun!.  It  is  covered  by  peritoneum  in  front  and  at  the  side,  but  in  a  certain 
])roiiortion  of  cases  (twenty-six  per  cent,  in  one  hundred  dissections)  this  part  of 
the  large  intestine  is  connected  with  the  posterior  wall  of  the  al)domen  by  a  meso- 
colon, that  is  to  say,  it  is  quite  surrounded  by  peritoneum.  Connected  Avith  the 
ascending  colon  is  sometimes  found  a  fold  of  i)eritoneum,  extending  from  the  right 
side  of  the  gut  to  the  parietes  at  a  little  above  the  level  of  the  highest  part  of  the 
iliac  crest.  It  forms  a  shelf  upon  which  rests  the  extreme  right  margin  of  tlie 
liver.     It  might  be  called  the  sustentacnlum  he/path. 

The  ascending  colon  is  in  relation  behind  with  the  right  kidney,  second  portion 
of  the  duodenum,  and  quadratus  lumborum.  In  front  are  some  of  the  coils  of  the 
ileum  (fig.  577). 

The  transverse  colon: — The  transverse  colon,  smaller  in  diameter  than  the 
ascending,  (extends  from  tlie  under  surface  of  the  liver  to  the  s))leen.  Being  longer 
than  a  straight  Hue  between  these  two  ])oints,  it  lias  to  describe  an  arch  with  its  con- 


THE   COLON  973 

vexity  forwards;  it  also  liciids  a  little  downwards.  It  crosses  thr<)U<(h  the  uiuliilical 
r(.'gion  from  the  ri;i;lit  liyj)oc'lioiidriiiin  to  the  left  hypochondrium  (tig.  oC)")). 

In  the  majority  of  cases  the  superticial  part  of  the  colic  arch — as  seen  before  the 
viscera  are  disturbed — is  either  in  whole  or  in  greater  ])art  above  a  straight  line 
drawn  transversely  across  the  body  between  the  highest  points  of  tlie  iliac  crest. 
In  the  proportion  of  one  to  four  it  lies,  in  whole  or  in  greater  part,  below  this  line 
(%.  582). 

Certain  remarkable  bends  are  sometimes  formed  by  this  part  of  the  bowel.  The 
bending  is  always  in  the  same  direction,  namely,  downwards,  and  is  usually  abrupt 
and  angular.  The  apex  of  the  V  or  U-shaped  bend  thus  formed  may  reach  the 
pubes.  This  bend  appears  to  be  due  to  two  distinct  causes:  namely,  long-continued 
distension  on  the  one  hand,  and  to  congenital  malformati(jn  on  the  other. 

The  transverse  colon  is  in  relation  above  with  the  liver  and  gall  bladder,  the 
stomach,  and  at  its  left  extremity  with  the  s])leen.  The  third  portion  of  the  duo- 
denum passes  behind  it.  B(>low  are  the  coils  of  the  small  intestine.  It  is  sur- 
rounded with  ]K'ritoneum,  being  connected  with  the  posterior  al)dominal  wall  by  a 
meso-colon. 

The  descending  colon  extends  from  the  spleen  to  the  sigmoid  liexure.  It  is 
more  movable  than  the  ascending  colon.  It  is  also  narrower.  At  its  beginning 
it  is  connected  with  the  diaphragm,  on  a  level  with  the  tenth  and  eleventh  ribs,  by 
a  fold  of  peritoneum,  the  codo-ndlc  ligament  (or  sustentaculum  lienis,  from  the  fact 
that  it  supports  the  s])leen).  The  bend  between  the  transverse  colon  and  descend- 
ing colon  is  called  the  splenic  flexure.  The  descending  colon  is  situated  in  the  left 
hypochondriac  and  luml)ar  regions  (tig.  501).  Its  relations  to  the  ]~)eritoneum  are 
the  same  as  obtain  with  the  ascending  colon,  that  is,  it  is  covered  in  front  and  on 
the  sides.  A  meso-colon  is  met  with  oftener  on* this  side  than  on  the  right.  In  one 
hundred  dissections  it  was  found  thirty-six  times.  The  descending  colon  is  covered 
in  front  by  the  small  intestine;  behind,  are  part  of  the  diaphragm,  the  left  kidney, 
and  the  quadratus  lumborum  muscle  (fig.  577). 

The  sigmoid  flexure  and  rectum. — The  segment  of  gut  termecl  the  sigmoid 
flexure,  and  the  so-called  first  part  of  the  rectun),  form  together  a  single  simple 
loop  that  cannot  be  divided  into  parts.  This  loop  begins  where  the  descending 
colon  ends,  viz.,  in  the  left  iliac  fossa,  and  ends  at  the  commencement  of  the 
so-called  second  piece  of  the  rectum — at  the  spot  where  the  meso-rectum  ceases, 
op])osite  ai)out  the  third  piece  of  the  sacrum  in  the  median  line.  The  loop  Avhen 
unfolded  describes  a  figure  that  may  be  compared  to  the  capital  omega.  The  aver- 
age length  of  this  sigmoid  or  omega  loop  is  seventeen  inches  ancl  a  half.  The 
normal  position  of  the  loop  is  not  in  the  left  iliac  fossa,  but  wholl}'  in  the  pelvis. 
The  most  common  disposition  of  it  may  now  be  described. 

The  descending  colon  ends  just  at  the  outer  border  of  the  psoas.  The  gut  here 
suddenly  changes  its  direction,  and  the  sigmoid  or  omega  loop  l)egins  (figs.  565, 
577  ).  The  bowel  crosses  the  nuiscle  at  right  angles  and  about  midway  between  the 
lumbo-sacral  (eminence  and  Poupart's  ligament.  It  now  descends  vertically  along 
the  left  ])elvic  wall,  and  may  at  once  reach  the  ])elvic  floor.  It  then  ])asses  more  or 
less  horizontally  and  transversely  across  the  pelvis  from  left  to  right,  and  commonly 
comes  into  conta(;t  with  the  right  pelvic  wall.  At  this  point  it  is  bent  upon  itself, 
and,  pa.ssing  once  more  towards  the  left,  reaches  the  middle  line  and  descends  to 
the  anus.  It  will  lie  therefore  in  more  or  less  direct  contact  with  the  bladder  and 
uterus,  and  may  possibly  touch  the  ca?cum.  It  is  very  closely  related  with  tlie 
coils  of  small  gut  that  occupy  the  pelvis,  and  by  these  coils  the  loop  is  usually 
hidden. 

The  sigmoid  or  omega  loo])  is  attach(>d  to  the  abdominal  and  ])clvie  wall  by  a 
meso-colon,  so  that  it  is  (piite  surrounded  by  peritoneum.  The  line  of  attachment 
of  this  meso-colon  is  as  follows:  It  crosses  the  ]>soas  at  a  right  angle,  and  then 
takes  a  slight  curve  upwards  so  a«  to  pass  over  the  iliac  vessels  at  or  about  their 
bifurcation.  The  curve  ends  at  a  point  either  just  to  the  inner  side  of  the  psoas 
nmscle,  or  between  the  jisoas  and  the  middle  line,  or,  as  is  most  frecjuently  the  case, 
just  over  the  liifurcation  of  the  vessels.  From  this  ]>oint  the  line  of  attachment 
proceeds  vertically  down,  taking  at  first  a  slight  cun-e  to  the  right.  Its  course  is 
to  tlie  left  of  the  middle  line,  while  its  ending  will  be  ujton  that  line,  about  the  thinl 


974 


THE   ORGANS   OF  DIGESTION 


piece  of  the  sacrum.     The  siirmoiJ  meso-eolon  measures  from  one  and  a  (juarter  to 
three  and  a  half  inelies  in  wicUh — i  e.,  from  the  parietes  to  the  bowel. 

When  a  descending  meso-eolon  exists  it  joins  tliat  of  the  loop,  and  the  line  of 
attachment  is  then,  as  a  rule,  directed  obliiiuely  across  the  psoas  and  the  lower  end 
of  the  kidney,  Avhile  beyond  the  pelvic  brim  the  attachment  is  as  above  described. 

There  is  often  no  meso-eolon  over  the  psoas,  the  gut  being  adherent  to  that 
muscle. 

Fig.  577.— View  of  the  Deeper  Abdominal  Viscera.     (Rlidinger.) 


Superior  vena  cava 


THORACIC  DUCT 


Inferior  vena  cava 


ASCENDING  COLON 


Aorta 

LEFT  BRONCHUS 


KIDNEY 
DUODENUM 
DESCENDING  COLON 

SIGMOID  FLEXURE 


In  ponnection  with  the  sigmoid  meso-eolon  is  often  found  a  fossa  or  pouch  of 
peritoneum,  known  as  the  intersigmoid  fossa.  The  pouch  is  formed  by  the  layers 
of  the  meso-eolon,  and  is  produced  by  the  sigmoid  artery.  It  is  generally  found 
over  the  bifurcation  of  the  iliac  vessels.  The  pouch  is  funnel-shaped,  and  the 
opening  looks  downwards  and  to  the  left.  The  fossa  varies  in  depth  from  one  to 
one  and  a  half  inches,  and  is  the  seat  of  the  sigmoid  hernia. 

The  rectum. — The  rectum  has  been  described  as  divided  into  three  jxirtions. 
Such  division  is  (juitc  arbitrary,  and  is  inconvenient.  What  is  usually  described 
as  the  first  portion  has,  in  the  account  just  given,  been  included  with  the  sigmoid 
tiexure. 


Tin:  llECTl'M  AM)   A  XL'S  97.') 

Tho  two  roiniiiniiii^  ])()rti()iis  of  the  intestine  extend  I'roui  tlic  niiiMIe  of  tlu'  lliinl 
piece  of  the  sacrum  to  the  anus. 

It  would  be  well  if  the  term  '  rectum  '  were  to  be  limited  to  that  part  of  the 
bowel  which  is  below  the  level  of  the  third  segment  of  the  sacrum,  and  which  is 
free  of  an}'^  meso-colon.  This  ])ortion  of  bowel — the  rectum  proper — may  l)e 
divided  into  two  i)ortions.  Tlie  lirst  i)ortion  extends  from  thi'  tliird  ])i(ce  of  the 
sacrum  to  tlio  tij)  of  the  ct)ccyx. 

This  i)ortion,  about  three  and  a  half  in(^hes  long,  is  only  covered  by  peritoneum 
above,  and  then  only  over  the  anterior  surface.  Behind,  it  is  in  relation  with  the 
sacrum  and  coccyx.  In  front  it  is  in  relation  with  the  trigone  of  the  bladder,  the 
vesiculie  seminales,  and  under  surface  of  the  prostate.  In  tlie  female  the  anterior 
surface  is  in  relation  with  tlie  vagina  and  the  cervix  uteii. 

The  peritoneum  is  reflected  from  the  rectum  to  the  bladder  in  the  male,  and 
the  vagina  in  the  female  (recto-vesical  or  recto-vaginal  pouch).  This  pouch 
extends  in  the  male  to  witliin  al)out  three  inches  of  the  anus.  On  the  posterior 
surface  of  the  gut  there  is  no  peritt)neum  below  a  i)oint  five  inches  from  the  anus. 

The  second  portion  (or  what  used  to  be  called  the  tliird  portion)  extends  from 
the  tip  of  the  coccyx  to  the  anus;  it  is  about  an  inch  and  a  half  long.  It  differs 
from  the  first  portion  in  the  direction  of  its  curve:  while  that  follows  the  curve  of 
the  sacrum  and  coccyx,  this  portion  turns  backwards  and  downwards.  It  is  not 
connected  with  the  peritoneum.  It  is  surrounded,  after  leaving  the  prostate,  by  the 
internal  sphincter,  while  the  levator  ani  is  attached  to  its  side.  At  its  end  the 
external  spliincter  is  situated;  in  front  is  the  triangular  ligament  of  the  perineum. 
Just  aI)ove  the  anus  the  n.'ctum  is  much  dilated. 

The  anus. — The  anus  is  the  aperture  l)y  which  the  intestine  opens  externally. 
During  life  it  is  contracted  by  the  sphincters,  so  as  to  give  the  skin  around  a 
wrinkled  a])pearance.  Round  the  lower  part  of  the  rectum  and  anus  certain 
muscles  that  are  connected  with  its  proi:)er  function  are  situated.  They  are  the 
internal  sphincter,  the  levator  ani,  and  the  external  sphincter.  The  levator  ani 
and  external  sphincter  will  be  found  described  in  another  part. 

The  internal  sphincter  is  a  thickening  of  the  circular  fibres  of  the  intestine, 
situated  round  the  rectum  about  an  inch  above  the  anus,  and  extending  over  half 
an  inch  of  the  intestine.  It  forms  a  complete  muscular  ring.  It  is  two  lines  thick, 
and  is  paler  than  tlie  external  sphincter. 

The  rectum  differs  from  the  rest  of  the  colon  in  presenting  perfectly  smootli 
walls  marked  ))V  no  sacculi,  by  no  longitudinal  muscular  liands,  and  by  no  ap])en- 
dices.  The  mucous  membrane  of  the  rectum  is  thicker  than  that  of  the  rest  of  the 
large  intestine.  Certain  folds,  chiefly  longitudinal  in  direction,  are  seen  in  the  lax 
state  of  the  tube,  which  disappear  when  distended.  Houston  has  described  three 
oblique  semilunar  folds,  which  project  into  the  lumen  of  the  tube:  one  in  front  l>y 
the  ])rostate,  and  two  others  higher  up;  one  from  the  left  side,  and  one  on  the 
right,  the  highest. 

Structure  of  the  large  intestine. — Tliere  are  four  coats:  a  serous,  muscular, 
mui'ous,  and  submucous. 

The  serons  is  derived  from  the  peritoneum,  and  is  more  or  less  (■om])lete. 

The  appendices  cpiploicse  in  conneetion  with  this  laver  liave  lieen  mentioiu'd 
(fig.  576). 

The  muscular  coat  is  divided  into  circular  and  longitudinal  layers,  the  longi- 
tudinal being  external.  The  arrangement  of  the  longitudinal  fibres  has  been 
described  in  as  far  as  they  make  up  th(!  three  longitudinal  ])ands  (fig.  576).  Only 
a  small  amount  of  longitudinal  fibres  arc  found  between  the  l)ands,  except  on  thi' 
vermiform  appendix  and  lower  part  of  the  sigmoid  llexure,  where  they  an- 
arranged  all  round. 

The  circular  iibres  form  a  thin  layer,  and  are  mostly  collected  in  the  interval 
between  the  sacculi. 

The  mucoKS  mnnhrnne,  se])arated  from  the  muscular  lavfr  by  the  Kuhmiiroii.^ 
layer,  has  no  villi,  and  no  valvuhe  coimiventes. 

Blood-vessels. — The  large  inti'stine  is  su]i])lied  with  blood  by  the  branches  of 
the  su])erior  mesenteric  and  inferior  mesenteric  arteries,  while  it  also  receives  a 
l)lood-supi)ly  from  the  internal  iliac  at  the  rectum.     The  vessels  form  a  continuotis 


976  THE  ORGAXS   OF  DIGESTION 

series  of  arches  from  the  cfficuni.  where  the  vasa  intestini  tenuis  anastomose  with 
the  ileo-colica,  the  first  branch  of  the  superior  mesenteric  given  to  the  large 
intestine. 

The  blood-supply  of  the  rectum  is  from  the  inferior  mesenteric  by  the  superior 
ha^morrhoidal,  from"  tlie  internal  iliac  by  the  middle  ha^morrhoidal,  and  from  the 
internal  pudic  by  the  inferior  luemorrhoidal.  The  vessels  at  the  lower  end  of  the 
rectum  assume  a  longitudinal  direction,  connnunieating  freely  near  the  anus,  and 
less  freely  above. 

The  blood  of  the  large  intestine  is  turned  into  the  portal  vein  by  means  of  the 
superior  mesenteric  and  inferior  mesenteric  veins.  At  the  rectum  a  communication 
is  set  up  between  the  systemic  and  portal  system  of  veins,  since  some  of  the  l)lood 
of  that  part  of  the  intestine  is  returned  into  the  internal  iliac  veins.  In  the  lower 
end  of  the  rectum  the  veins,  like  the  arteries,  are  arranged  longitudinally.  This 
arrangement  is  called  the  luvmorrhoidal  plexus. 

The  nerves  and  lymphatics  of  the  large  intestine  differ  in  no  important 
particular  from  those  of  the  small  intestine. 


TRE  LIVER 

The  liver — the  largest  gland  in  the  body — is  situated  in  the  upper  and  right 
part  of  the  abdominal  cavity  f  figs.  565,  578).  It  is  of  most  irregular  shape.  It 
weighs  between  forty-five  and  sixty  ounces.  In  females  the  liver  is  smaller  than 
in  males.  It  bears  a  different  relation  to  the  body  weight  at  different  ages.  It 
forms  one-fortieth  part  of  the  weight  of  the  body  in  the  adult  male,  and  one- 
thirty-sixth  in  the  adult  female.  In  the  foetus,  at  the  fourth  month,  it  is  one-tenth 
the  weight  of  the  body,  and  in  the  infant  at  birth  one-twentieth  (fig.  578).  It 
measures  from  right  to  left  seven  to  ten  inches,  from  before  backwards  three  to 
six  inches,  and  six  to  seven  inches  from  above  downwards  in  the  thickest  part  of 
the  right  lobe.  It  is  of  a  chocolate  or  reddish-brown  color,  is  solid  and  firm  to  the 
touch,  but  frial)le.     Its  bulk  is  equal  to  ninety-five  cubic  inches. 

In  the  description  which  follows  it  will  be  noted  that  there  are  two  borders — 
anterior  and  posterior;  two  extremities — right  and  left;  three  surfaces — superior, 
inferior,  and  posterior;  five  lobes — right,  left,  quadrate,  caudate,  and  Spigelian; 
five  fissures — umbilical,  fissure  for  the  ductus  venosus,  transverse,  fissure  of  the 
vena  cava,  fissure  for  the  gall  bladder;  five  ligaments — coronary,  suspensory  or 
falciform,  round,  right  and  left  lateral. 

The  liver  is  seen  to  be  divided  by  means  of  a  fold  of  peritoneum — the  suspen- 
sory ligament — into  two  very  distinct  parts,  the  right  and  left  lobes  (figs.  578,  579). 

The  anterior  border  of  the  liver  is  well  defined,  appearing  as  a  sharp  thin  edge. 
To  tlie  left  of  the  middle  point  at  the  beginning  of  the  longitudinal  fissure  is  the 
interlobar  notch,  marking  the  division  between  the  right  and  left  lo1)es.  Further 
to  the  right  is  a  notih  for  the  gall  bladder. 

The  posterior  border  is  thick,  rounded,  and  fixed,  is  slightly  marked  by  the 
spinal  colunni,  and  notched  for  the  vena  cava. 

The  right  extremity  is  tliick,  and  rounded  like  the  posterior  border.  The  left 
extremity  is  thin  and  fiat  like  the  anterior  border. 

The  surfaces  are  described  as  thoy  are  seen  in  a  liver  which  has  been  hardened 
III  fi'itii. 

The  superior  surface  of  the  liver  is  convex,  and  moulded  to  the  surface  of  the 
diaphragm.  It  is  smooth,  and  covered  by  peritoneum.  It  is  divided  by  the  sus- 
pensory ligament,  which  runs  from  ])efore  backwards,  into  two  parts:  the  right  and 
left  lol)es,  the  right  division  l)eing  much  the  larger  (fig.  579).  Upon  this  surface  of 
the  left  lobe  is  a  shallow  de})ression  for  the  heart.  The  surface  of  the  left  lobe  is 
much  less  convex  than  that  of  the  right.  A  considerable  portion  of  this  surface 
faces  anteriorly,  and  some  writers  divide  it  into  anterior  and  upper  surfaces. 


THE   LIVER  977 

The  inferior  surface  consists  of  that  part  of  tlic  liver  in  front  of  and  including 
the  transvcTi^c  lisisuri'.  It  is  irregularly  concave.  It  is  covered  hy  peritoneum, 
exeejjt  where  the  gall  bladder  comes  in  contact  with  its  surface,  and  at  the  trans- 
verse fissure  where  the  lesser  omentum  leaves  the  liver.  It  consists  of  three  r)arts 
— viz.,  the  «iuadrate  lobe,  nearly  all  the  left  lol)e,  and  the  under  surface  of  the  right 
lolie  riig.  oSO).  This  inferior  surface  is  divided  into  right  and  left  sections  hy  The 
longitudinal  fissure  which  forms  \\w  inferior  separation  between  the  right  anil  left 
lobes.  _  The  part  of  the  longitudinal  fissure  seen  on  this  surface  is  known  as  the 
umbilical  fissure  from  its  contahiing  during  f(ptal  life  the  umbilical  vein,  the 
remains  of  which  are  now  to  be  seen  as  the  round  ligament.      It  runs  from  before 


Fm.  578.— The  Visckra  of  tttk  Farns.     (KUdiuger.) 


LIVER 
Suspensory  ligament 


SMALL  INTESTINE 


LUNG 

RIGHT  AURICLE 


RIGHT  VENTRICLE 


PART  OF  TRANSVERSE 
COLON 


Hypogastric  artery 


backwards,  meeting  the  transverse  fi.^sure  Ix-hind.  The  portion  of  the  left  lobe 
included  on  this  surface  is  nuich  smaller  than  the  similar  surface  of  the  right  lobe. 
It  lies  over  the  cardiac  i)art  of  the  stomach  and  the  anterior  surface  adjoining  the 
le.><ser  curvature,  and  sliows  an  impression  (impre.^'o'o  t/nstriai)  made  ])y  that  organ. 
Its  anterior  border  is  sharp  and  freer  but  l)ehind,  tlie  si-i)aration  from  the  jiosterior 
surface  is  very  ill  defined. 

The  under  surface  of  the  right  lobe  is  divided  into  two  by  the  gall  bladder, 

which  is  contained  in  a  fossa  (the  fo>i$a  of  the  ffttll  bladder).     The  inner  of  these  two 

l)ortions,  which  is  bounded  In-  the  umbilical  fissure  to  the  left,  the  fossa  of  the  gall 

bladder  to  the  right,  and  the  transverse  (issure  behind,  is  called  the  quadrate  lobe, 

62 


978 


THE   ORGANS   OF  DIGESTION 


and  is  coniuvted  with  the  left  l(»h(>  very  often  l)y  a  hridge  of  liver  substance  (pons 
hepatis)  across  the  umbilical  fissure.  The  outer  of  the  two  portions  is  much  the 
larger,  and  presents  three  depressions  upon  its  surface:  an  anterior  one  for  the 
hepatic  flexure  of  the  colon  {impressio  colica),  a  posterior  one  for  the  right  kidney 

Fig.  579.— Supkriok  Sikface  of  the  Liver. 


GALL  BLADDER 


Falciform  or  suspensory  ligameut 


Fig.  580. — The  Inferior  Surface  of  the  Liveu. 

Vena  cava 


BILE  DUCT 

Portal  veih  \ 

Hepatic  artery  \ 
SPIGELIAN  LOBE      , 


UMBILICAL  FISSURE 


(impressio  rrnalis),  and  one  situated  on  the  inner  side  of  the  impressio  renalis  for 
the  descending  part  of  the  duodenum  (hnpressio  duodenal  is).  In  a  hardened  liver 
these  impressions  are  well  marked,  and  are  separated  by  well-defined  ridg(-s. 

The  posterior  surface  is  directed  backwards  towards  the  vertebral  column,  at 


THE  LIVER 


079 


wliich  part  it  is  concave.  It  includes  that  part  of  the  liver  behind  the  transverse 
lissure,  and  consists  of  the  following  ])arts  (tig.  581): — 

(1)  The  posterior  portion  of  the  left  lobe,  not  very  well  defined;  it  ])resents  a 
protuberance  (the  tuber  omenUde)  in  front,  which  projects  against  the  lesser  omen- 
tum; behind,  a  concavity  coming  in  contact  with  the  cardia. 

Tliis  ])()rti(>ii  is  separated  by  means  of  the  fissure  of  the  ductus  venosus  from 
(2)  the  Spigelian  lobe,  which  lies  between  tliis  lissun;  and  that  of  the  vena  cava. 
This  lobe  is  directed  l)ackwards,  is  longer  from  above  dow'uwards  than  from  side  to 
side,  and  is  somewhat  concave  from  side  to  side.  It  is  opjjosite  to  the  tenth  and 
eleventh  thoracic  vertebrae,  and  rests  on  the  crura  of  the  diaphragm.  Behind  its 
up})er  left-hand  corner  the  oesophagus  passes  to  enter  the  stomach.  Below,  it  pro- 
jects and  forms  part  of  the  posterior  boundar}^  of  the  transverse  fissure.  It  is  con- 
nected with  that  part  of  the  right  lobe  which  enters  into  the  posterior  surface  ])y 
means  of  (3)  the  caudate  lobe,  Avhich  is  a  small  mass  of  liver  substance  rurming 
from  left  t<^  right  l)eliind  the  transverse  fissure.  It  lies  directly  over  the  foramen  of 
W'inslow.  It  varies  a  good  deal  in  form;  is  sometimes  well  defined,  at  other  times 
hardly  to  be  seen.  When  well  defined, it  is  about  two  to  three  inches  long;  behind 
is  tiie  termination  of  the  fissure  of  the  vena  cava. 


Fic4.  581. — Posterior  Surface  of  the  Liver. 

LEFT  LOBE  Vena  cava 


SPIGELIAN  LOBE 


(4)  The  portion  of  the  right  lobe  taking  part  in  the  posterior  surface  consists  of 
a  strip  two  and  a  half  to  three  inches  broad  (Quain).  This  is  uncovered  by  peri- 
toneum, except  at  the  extreme  right.  Lying  betAveen  the  two  layers  of  the  coro- 
nary ligament  close  to  the  vena  cava  and  near  the  caudate  lobe  is  an  imju-ession  for 
the  right  suprarenal  capsule  {iinprcs.^io  suprarenalk). 

Fissures. — The  tissui'es  on  the  inferior  and  posterior  surfaces  of  the  liver  are 
arrange(l  very  like  a  cajiital  letter  H.  The  left  upright  of  the  H  is  formed  by  the 
longitudinal  fissure;  the  anterior  portion  containing  the  umlalical  vein  is  seen  on 
the  inferior  surface,  and  is  known  as  the  umbilical  fissure  ;  the  ])osterior  portion, 
seen  on  the  ])osterior  surface,  contains  the  ductus  venosus,  and  is  therefore  called 
the  fissure  of  the  ductus  venosus.  Tlie  transverse  bar  of  the  H  is  formed  by  the 
transverse  or  portal  fissure,  which  runs  across  at  right  angles  to  the  longitudinal 
tissurc,  and  contains  the  vessels  entering  the  liver,  viz.,  the  portal  vein,  hepatic 
artery,  and  hepatic  duct  (fig.  oSO).  . 

The  right  u))right  of  the  H  is  formed  by  the  fossa  of  the  gall  bladder  in  front; 
it  is  interrupted  l)y  the  caudate  lobe;  and  is  continued  ])ehind  as  the  fissure  of 
the  vena  cava,  containing,  as  its  name  imi)lies,  the  inferior  vena  cava. 

General  position. — The  liver  is  situated  in  the  right  hypochondriac  and  epi- 
gastric regions,  and  usually  extends  into  the  left  hypochondrium  (fig.  582).      It  is 


980 


THE   ORGANS   OF  DIGESTION 


opposite  the  iiintli.  tentli.  and  eleventh  dorsal  verteln-fe  hehind  (fig.  583),  and  on 
the  right  side  extends  hetween  the  seventh  and  eleventh  ribs;  in  front,  it  lies  behind 
the  fifth,  sixth,  seventh,  eighth,  and  ninth  costal  cartilages;  and  its  anterior  border 
corresponds  on  the  right  to  the  line  of  the  margin  of  the  costal  cartilages,  and  to 
the  left  it  is  in  contact  with  the  anterior  al)doniinal  -wall  below  the  sternal  notch 
(fig.  582). 

The  liver  is  very  movable,  and  alters  its  position  under  various  circumstances. 
It  is  depressed  at  each  inspiration,  the  anterior  border  being  pushed  below  the  ribs 
by  a  deep  breath.  When  lying  down,  the  liver  edge  is  half  an  inch  above  the 
margin  of  the  ribs.     In  children,  the  gland  being  larger  in  proportion  to  the  body 

Fig.  582.— Relation  of  the  Abdominal  Visceka  to  the  Paeietes.      (Treves.) 


than  in  the  adult  state,  it  extends  below  the  ril)s  and  reaches  the  left  hypochon- 
drium. 

The  liver's  extreme  left  point  is  al>out  an  inch  and  a  half  beyond  the  left  margin 
of  the  sternum;  in  front,  in  the  middle  line,  it  reaches  to  about  half  way  between 
the  xiphoid  cartilage  and  the  navel.  The  lower  edge  as  it  crosses  the  subcostal 
angle  is  represented  l)y  a  line  drawn  from  the  ninth  right  to  the  eighth  left  costal 
cartilage.      (Quain.) 

Its  upper  limit  is  indicated  by  a  line  crossing  the  mesostfrnum  close  to  its  lower 
end,  and  rising  on  the  right  side  in  the  mannnary  line  to  the  level  of  the  fifth  rib. 
On  the  left  the  line  is  ))ractically  horizontal.  Behind,  the  liver  is  nearest  the  surface 
at  the  tenth  and  eleventh  thoracic  vcrtcl)rie. 


THE  LIVER 


981 


Its  upper  convex  surface  is  in  contactt  witli  llie  whole  of  the  right  arch  of  the 
(liaplirajiiu  and  a  part  of  the  left,  as  well  as  with  the  ril)s  and  tlie  anterior  wall  of 
the  ahdonien. 

The  undi'r  surface. — The  left  lohe  li<'S  over  tlie  cardiac  end  and  a  |)()rtion  of  the 
anterior  wall  of  the  stomach. 

The  rij^ht  lohe  lies  over  tin'  hepatic  flexure  of  the  colon  and  ri^lit  kidnev,  and 
deseendinii  jiortion  ()f  the  duodenum. 

Thi'  quadrate  lohe  lies  over  the  pyloric  end  of  the  stomach  and  lirst  part  of  the 
iluodenum. 

The  posterior  surface. — The  Spigelian  lohe  lies  against  the  tenth  and  eleventh 

Fui.  .'jSJ.— i;i:i..VTKi.\s  OK  TiiK  .AnnoMix.vi,  Visii;k.v  to  the  P.VKnnics.     'Treves.) 


thoracic  vertehrre,  the  right  crus  of  the  dia})hragm,  and  the  lower  euil  of  the 
fesophagus.  That  portion  of  the  right  lohe  which  takes  i)art  in  this  surface  lies 
against  the  right  suprarenal  capsule  and  dia|)hragni. 

The  inferior  vena  cava  lies  in  a  groove  in  this  lohe.  The  small  portion  of  the 
left  lohe  taking  ])art  in  the  posterior  surface  lies  against  the  cesophagus. 

The  fundus  of  the  gall  hladder  is  o])posite  the  ninth  costal  cartilage,  close  to 
the  outer  margin  of  the  liglit  rectus  muscle. 

Relation  to  the  peritoneum. — The  liver  is  nceived  hetween  the  layers  of  the 
gastro-lu'patic  omentum.  The  niitcrior  hii/cr  on  leaving  the  transverse  lissure  ])asses 
alongtothe  anterior  horder  of  the  liver,  where  it  meets  the  rouml  ligament,  encloses 
it,  and  is  then  continued  on  to  the  sui>erior  surface  in  two  jioitions.  owing  to  tlie 


982  THE  ORGANS  OF  DIGESTION 

intervention  of  the  round  li^anient,  the  two  layers  reflected  on  to  this  structure 
l)eing  known  as  tlie  suspensory  lijzanient.  At  the  posterior  border  of  the  superior 
surface  it  leaves  the  liver  and  forms  the  u])per  layer  of  the  coronary  ligament. 

The  posterior  layer  of  the  gastro-hei)atic  omentum  passes  backwards,  covers  a 
portion  of  the  posterior  surface  of  the  liver,  and  leaves  uncovered  that  part  of  the 
right  lobe  (except  the  extreme  right)  which  takes  part  in  this  surface.  It  is  finally 
retlected  to  form  the  inferior  layer  of  the  coronary  ligament. 

The  ]iarts  of  the  liver  uncovered  by  i)eritoneum  are:  the  transverse  fissure,  the 
fossa  of  the  gall  l)ladder,  and  that  portion  of  the  posterior  surface  made  up  l)y  the 
right  lobe,  and  to  which  allusion  has  already  lieen  made. 

Underneath  the  peritoneal  investment  of  the  liver  is  a  thin  fibro-elastic  mem- 
brane which  is  intimately  adherent  to  the  peritoneum,  and  is  continuous  over  the 
liver  where  the  peritoneum  is  deficient.  At  the  transverse  fissure  this  filjrous  layer 
invests  the  hepatic  vessels,  forming  a  special  sheath  which  follows  the  vessels  as 
they  enter  the  liver:  this  structure  receives  the  name  of  Glisson's  capsule. 

Above. 
Diaphragm  and  anterior  M-all  of  abdomen. 

Behind. 

Tenth  and  eleventh  thoracic 
vertebrae ;    crura    of    dia- 
phragm ;     lower    end    of  GENERAL 
oesophagus  ;    right    supra-                 EELATIONS 
renal  capsule  ;    great  ves-            qF  THE  LIVER 
sels. 


Below 

Cardiac  end  of  stomach  ;  hepatic  flexure  of  colon  ;  right  kidney  ;  first  and  second  portions 

of  duodenum. 

Ligaments  of  the  liver. — "With  the  exception  of  the  round  ligament,  the  liga- 
ments are  formed  by  the  peritoneum,  and  (with  the  same  exception)  are  all 
attached  to  the  diaphragm.  The  reflexion  of  the  two  layers  of  peritoneum  from 
the  posterior  surface  of  the  liver  to  the  dia^jhragm,  as  just  descril^ed,  forms  the 
coronary  ligaments,  the  extremities,  or  lateral  continuations,  being  called  the 
right  and  left  lateral  ligaments.  The  left  lateral  ligament  is  the  longer,  and  is 
attached  to  the  diaphragm  in  front  of  the  oesophagus.  The  right  is  attached  to  the 
back  part  of  the  diapliragm. 

The  broad  ligament  (falciform  or  suspensory  ligament)  is  also  continuous 
behind  with  the  coronary  ligament;  it  is  formed  by  the  adjacent  surfaces  of  the 
two  portions  of  peritoneum  covering  the  superior  surface;  it  extends  from  the 
umbilicus  where  is  the  apex  of  the  falx.  The  upper  rounded  border  is  connected 
with  the  anterior  abdominal  Avail  and  diaphragm.  The  free  or  anterior  border 
contains  the  round  ligament;  the  lower  or  attached  border  extends  froni  before 
backwards  on  tlie  up])er  surface  of  the  liver. 

Tlie  round  ligament  is  a  fibrous  cord  (the  remains  of  the  umbilical  vein), 
extending  on  tlie  free  l)oi(ler  of  the  broad  ligament  from  the  longitudinal  fissure  to 
theumliilicus. 

Blood-vessels, — The  liver  receives  its  arterial  sujjplyof  blood  from  the  hepatic 
artery,  a  branch  of  the  ca?liac  axis,  which  passes  up  betw^een  the  two  layers  of  the 
lesser  omentum,  and,  dividing  into  two  branches,  one  for  each  lobe,  enters  the  liver 
at  the  transverse  fissure.  The  right  branch  gives  off  a  branch  to  the  gall  bladder. 
The  liver  receives  a  nnich  larger  supply  of  blood  from  the  portal  rein,  which 
conve3-s  to  the  liver  ])lood  from  tlie  stomach,  intestines,  pancreas,  and  spleen.  It 
enters  the  transverse  fissure,  and  there  divides  into  two  branches.  Below  this 
fissure  the  hepatic  artery  lies  to  the  left,  the  bile  duct  to  the  right,  and  the  portal 
vein  behind  and  between  the  two  (fig.  5H4).  These  three  structures  ascend  to  the 
liver  between  the  layers  of  the  gastro-hepatic  omentum  in  front  of  the  foramen  of 


THE   LIVER  983 

^\'insl()\v.  At  tlu;  actual  lis.^untlir  order  of  tlic  tl)nc  structuros  from  before  back- 
wards is — duct,  artery,  vein. 

The  hepatic  veins,  l»y  which  the  hloocl  of  the  liver  passes  into  the  inferior  vena 
cava,  open  by  several  larj^e  and  small  openings  into  that  vessel  at  the  posterior 
surfaces  of  the  irland  at  the  liottom  of  the  fossa  of  the  vena  cava. 

Lymphatics. — The  lymi>hatics  are  divided  into  a  deep  and  a  sui)erfi(ial  set. 
The  deep  .set  run  with  the  branches  of  the  portal  vein,  artery,  and  duct  through  the 
liver,  leaving  at  the  transverse  fissure,  where  they  join  the  vessels  of  the  super- 
ficial set. 

The  superficial  set  begin  in  tlie  subperitoneal  tissue.  Those  of  the  upper  surface 
consist: — (1)  Of  vessels  which  jiass  U]),  i)rincipally,  in  the  broad  ligament  and 
right  and  left  lateral  ligaments,  through  the  diai)hragm,  and  so  into  the  anterior 
mediastinal  glands;  occasionally  lynii)hatics  of  tlie  right  ligament  pass  straiglit 
into  the  thoracic  duct.  (2)  Of  a  set  passing  over  the  anterior  Ijorder  of  the  liver 
to  the  glands  in  the  small  omentum  al)OUt  the  transverse  fissure. 

On  the  under  surface,  the  lymphatics  to  the  right  of  the  gall  bladder  enter  the 
lumbar  glands. 

Those  round  the  gall  bladder  enter  the  glands  of  the  lesser  omentum. 

Those  to  the  left  of  the  gall  bladder  enter  the  glands  of  the  oesophagus  and  lesser 
curvature  of  the  stomach. 

Fig.  584.— Rf:latiox  of  Striictuees  at  and  bkluvv  thk  Tkansvekse  Fissure.      (Thane,  j 


GALL  BLADDER 


Ifepatic  artery 


Structure  of  the  liver. — If  a  section  be  made  of  the  liver,  the  following  features 
in  its  general  structure  ma}'  be  noted: — 

Outside  of  all  will  be  seen  the  investment  of  periioneinu,  which  is  incomplete  in 
parts,  and  which  has  been  already  described. 

Within  this  a  thin  Jihrejus  coat  will  be  ol)served  to  invest  the  entire  gland.  At 
the  transverse  fissure  this  coat  turns  into  tlie  substance  of  the  liver  with  the 
branches  of  the  iM)rtal  vein. 

Glis--<on\s  capsule. — The  capsule  is  in  all  ])arts  closely  adherent  to  the  gland- 
substance,  and  is  thickest  where  the  peritoneum  is  absent. 

The  liver  on  section  is  seen  to  be  mottled,  and  when  a  portion  is  torn  the 
surface  presents  a  granular  appearance.  This  is  produced  by  the  minute  lobules 
(one  twenty-fourth  to  one-twelfth  of  an  inch  in  diameter)  of  which  the  liver  tissue 
is  com])osed. 

The  cut  surface  will  also  exhibit  the  openings  of  a  number  of  canals.  A  slight 
examination  will  show  that  these  are  of  two  kind.>< — viz.  the  canals  for  the  branches 
of  the  portal  vein  and  the  canals  for  the  hepatic  veins. 

In  the  portal  catuil.^  the  vein  is  accompanied  l)y  a  branch  of  the  duct  and  a 
l)ranch  of  the  hepatic  artery.  The  vein  has  thick  walls  which  will  l)e  seen  to  be 
more  or  less  collapsed  on  section.  The  vessels  in  the  canal  are  s»oparated  from  the 
liver  substance  by  much  connective  tissue  (Glis.son's  capsule,  fig.  5<S5). 

In  the  hepatic  canals  the  veins  are  solitary,  their  walls  are  exceedingly  thin,  and 
their  mouths  open  and  gaping.  The  wall  of  the  vein  is  directly  adherent  to  the 
liver  suljstance,  no  connective  tissue  ca))sule  intervening. 

The    gall  bladder,  which   retains  the  liile.  i.^;  situated  Ix'tween  the  right  and 


984  THE  ORGANS  OF  DIGESTION 

quadrate  lobes  on  the  under  surface  of  the  liver.  It  is  of  pyriforni  outline,  and 
when  full  is  seen  projecting  l)eyond  the  anterior  border  of  the  liver,  coming  in 
contact  with  the  abdominal  wall'  opposite  tlie  ninth  costal  cartilage.  It  extends 
back  as  far  as  the  trans vi>rse  tissure. 

It  measures  in  length,  from  before  backwards,  from  two  and  a  half  to  four  inches 
(75  to  100  mm.),  and  an  inch  and  a  half  (35  mm.)  across  at  the  widest  i)art, 
and  will  hold  about  one  ounce.  The  broad  end  of  the  sac  is  directed  forwards, 
downwards,  and  to  the  right,  and  is  called  the  fimdm.  The  narrow  end,  or  neck, 
Avhich  is  curved  first  to  the  right,  then  to  the  left,  is  at  the  transverse  fissure.  The 
intervening  part  is  called  the  body. 

Its  upper  surface  is  in  contact  with  the  liver,  lying  in  the  fossa  of  the  gall 
l)ladder.  It  is  attached  to  the  liver  by  connective  tissue.  The  lower  surface  is 
covered  by  peritoneum,  which  passes  over  its  sides  and  inferior  surface,  though 
occasionally  it  entirely  surrounds  the  gall  l^ladder,  forming  a  sort  of  mesentery  to 
attach  it  to  the  liver.  The  lower  surface  comes  into  contact  with  the  first  part  of 
the  duodenum  and  hepatic  flexure  of  the  colon,  and  occasionally  with  the  pyloric 
ends  of  the  stomach  or  small  intestine,  which  are  often  post  mortem  found  stained 
with  bile. 

The  neck  of  the  gall  bladder  opens  into  the  cystic  duct.  This  is  a  tube  an  inch 
and  a  half  long  (35  mm.)  and  one-twelfth  of  an  inch  wide  (2.3  mm.),  Avhich 
unites  with  the  hepatic  duct  to  form  the  common  duct;  it  is  directed  backwards 

Fiti.  585. — Sectiox  of  a  Poktal  Caxal.     (Qiiaiu.) 


Lymphatics  in  Glissoyi's  capsule 


Lymphatics  in  Glisson's  capsule 


Artery 


and  to  the  left  as  it  runs  in  the  lesser  omentum,  the  hepatic  artery  being  to  the  left 
and  the  portal  vein  behind.     It  joins  the  heijatic  duct  at  an  acute  angle. 

The  hepatic  duct  begins  with  a  branch  from  each  lobe  right  and  left  in  the 
transverse  fissure,  and  is  directed  downwards  and  to  the  right  in  the  folds  of  the 
lesser  omentum,  the  hepatic  artery  being  to  the  left.  It  is  not  quite  two  inches 
long;  its  diameter  is  one-fifth  of  an  inch  (4  mm.).  Uniting  Avith  the  cystic  duct,  it 
forms  the  conrmon  hilc  duct  fductus  connnnnis  choledochus). 

The  common  bile  duct  is  about  three  inches  in  lengtli.  It  i)asses  down 
lietween  the  layers  of  the  lesser  omentum,  in  fi'ont  of  the  portal  vein,  and  to  the 
right  of  the  hepatic  artery  (fig.  584);  it  then  passes  behind  the  first  part  of  the 
duodenum,  then  between  the  second  part  and  the  head  of  the  pancreas,  and  ends 
at  the  lower  part  of  the  second  segment  of  the  duodenum  by  opening  into  that  part 
of  the  intestine  on  its  left  side  and  somewhat  l)ehind  (figs.  571,  586,  and  587).  It 
pierces  the  intestinal  wall  very  oblicpiely,  running  between  the  muscular  layer  for 
about  three-quarters  of  an  inch.  Tliere  is  a  slight  constriction  at  its  termination. 
The  pancreatic  duct  is  united  with  the  conmion  liile  duct  just  liefore  its  termina- 
tion. There  is  a  sliglit  i^aijilla  at  their  ])lace  of  opening  on  the  nuicous  surface  of 
the  duodenum.  Tliis  i)h))illa  is  aliout  four  inches  from  the  ])vlorus.  After  tlie 
pancreatic  duct  has  cntci'cd  tlie  l)ile  duct  there  is  a  dilatation  of  the  common  tube 
called  the  ampulla  of  Vater. 


THE   GALL   BLADDER 


9S5 


The  common  duct  has  u  diameter  of  alxmt  one-fourtli  of  an  inch  (0  nnn.  ). 
Its  width  at  the  ampulhi  is  greater.  It  is  narrowest  at  its  outlet  into  tlie 
duodenum.  The  cvstic  and  hejjatic  ducts  are  a  Httle  narrower  than  the  common 
«hict. 

Structure  of  the  gall  bladder, — Tlu-  wall  of  the  gall  bladder  is  made  up  of 
three  coats — serous,  muscular  or  lilimus.  and  mucous. 


Fig.  586. — Abdominal  Vi.scera,  from  liiiiiiNn.    (Uudiuger.) 


DESCENDING   COLON 

Inferior  mesenteric 
vein 


Vena  cava 


Superior  mesntteric 

reiit 
ASCENDING  COLON 


1.  The  serom  coat  being  formed  by  the  ]ieritoneuni,  is  only  found  on  the  lower 
surface  and  i)art  of  the  sides.     li(>neath  this  coat  is  a  nerve  ]>lexus. 

2.  T\w  Jihrous  coat  consists  of  idain  muscular  iibres  and  tibrous  tissue.  The 
muscular  fibres  run  mostly  hMigitndinally,  some  transversely.  The  lil»rous  tissue 
consists  of  white  fibres  running  in  every  direction.  This  layer  contains  the  i>rin- 
cipal  blood-vessels  and  lymphatics,  and  also  contains  a  nerv«'  ph-xus. 


986  THE   ORGANS   OF  DIGESTION 

3.  The  mucoKS  coat  is  raised  into  ruira^  boundino:  polygonal  spaces,  which  are 
largest  about  the  body.  It  is  lined  with  columnar  epithelium,  and  contains  many 
mucous  glands.  At  the  neck  the  mucous  membrane  forms  folds  which  project  into 
the  interior,  acting  as  valves.  This  laj'er  contains  an  anastomosis  of  blood-vessels, 
and  a  fine  plexus  of  lymi)hatics. 

The  duds  consist  of  a  fibrous  and  a  mucous  layer.  In  the  filjrous  layer  are  mus- 
cular fibres  which  are  chiefiy  circular,  together  with  many  strong  white  connective 
tissue  and  elastic  fibres.  The  mucous  layer  is  lined  with  columnar  epithelium,  and 
has  many  mucous  glands.  In  the  cystic  duct  the  mucous  membrane  is  raised  into 
folds,  which  are  crescentic  in  form,  and  so  directed  obliquely  as  to  seem  to  surround 
the  lumen  of  the  tube  in  a  sjjiral  manner. 

Varieties  of  the  Liver 

Varieties  are  more  rare  in  the  liver  than  in  almost  any  other  organ  of  the  body. 

The  left  lobe  may  be  very  small;  on  the  other  hand,  it  may  be  much  larger, 
occasionally  extending  in  an  attenuated  form  much  more  towards  the  left.  The 
left  lobe,  or  a  portion  of  it,  may  be  attached  only  by  a  pedicle  of  peritoneum  and 
vessels  to  the  main  organ.  The  gall  bladder  has  been  seen  through  an  opening  in 
the  upper  surface,  owing  to  the  depth  of  the  fossa  of  the  gall  bladder. 

The  liver  may  be  subdivided  into  many  lobes,  or  may  show^  no  division  at  all. 
It  may  retain  the  thick  rounded  form  of  the  foetus.  The  gall  bladder  may  be  absent, 
in  which  case  the  hepatic  duct  usually  Ijecomes  much  dilated  before  it  reaches  the 
duodenum. 

The  gall  bladder  may  be  partially  divided  either  transversely  or  longitudinally. 
The  common  duct  may  enter  the  bowel  independently  of  the  pancreatic  duct. 


THi:  PANCREAS 


The  pancreas  is  situated  in  the  epigastric  and  left  hypochondriac  regions.  It 
is  a  compound  racemose  gland.  It  lies  transversely  across  the  body,  on  a  level  Avith 
the  first  and  second  lumbar  vertebrae,  and  is  deeply  placed  (fig.  577).  It  differs  in 
shape  as  it  is  examined  in  situ,  or  removed  from  the  body.  AA'hen  examined  in  situ 
it  shows  various  impressions  for  the  different  organs  with  which  it  is  in  contact 
(figs.  570,  571);  when  removed  from  the  body  it  appears  to  be  longer,  and  runs  to 
a  point  at  tlie  left  extremity  (fig.  587).  It  is  of  a  pinkish-cream  colour  and  soft  in 
texture.  It  shows  upon  its  surface  the  markings  between  the  lobules  of  which  it  is 
made  up.  It  may  be  divided  into  four  portions:  a  head,  a  neck,  a  body,  and  a  tail. 
The  pancreas  varies  considerably  in  size.  Its  average  length  is  five  to  six  inches 
(120  to  150  mm. ),  and  its  thickness  from  half  an  inch  to  one  inch.  It  weighs  from 
2^  to  3|  ounces.  The  head  of  the  pancreas  is  situated  at  the  right  extremity  of 
the  gland,  and  is  contained  in  the  loo}!  of  tlie  duodenum.  It  is  disc-shaped  and 
flattened  from  before  })ackwards.  The  head  is  bent  downwards,  so  that  it  extends 
lower  than  the  lower  liorder  of  the  body.  Behind  it  are  found  the  common  bile 
duct,  which  runs,  as  a  rule,  in  a  canal  in  its  substance,  the  vena  cava,  the  left  renal 
vein,  and  the  aorta  (fig.  571).  In  front  are  the  superior  mesenteric  vessels,  the 
pancreatico-duodenal  vessels,  and  the  transverse  colon  and  its  meso-colon. 

The  neck  springs  from  the  upper  part  of  the  head  in  front  and  turns  upwards 
and  to  the  left  to  join  the  body.  It  lies  over  the  ]ioint  of  junction  of  the  superior 
mesenteric  and  portal  veins.  At  its  attachment  to  the  head  it  is  grooved  by  the 
gastro-duodenal  and  su]W'rior  ])Hncreatico-duodenal  arteries.  In  front  of  it  would 
be  the  first  part  of  the  duodenum. 

According  to  Professor  Plis,  tliere  are  three  surfaces  on  tlic  body  of  the  pan- 
creas:  anterior,  inferior,  and  ]tosterior.      The  body  extends  from  the  head  of  the 


THE   PAXCREAS 


987 


gland  to  tlie  spleen;  it  is  situated  transversely  across  the  vertebral  cnhnun  uitli  the 
large  vessels  intervening. 

The  anterior  ■wrfarc  is  in  ('(^itaet  with  tlu'  stoniaeh,  whieli  organ  gives  a.  eon- 
cavity  to  the  surface  (fig.  ">5J0).  This  surface  is  covered  l)y  peritoneum  derived 
from  the  ascending  layer  of  the  transverse  meso-colon. 

The  posterior  surface  is  in  contact  with  the  crura  of  the  diaphragm,  the  aorta, 
and  superi(jr  mesenteric  vessels,  which  structures  are  interposed  l:)etween  it  and  tiie 
spine  (figs.  571,  586).  The  splenic  artery  and  vein  run  lengthways  above  the  hack 
of  the  upper  border  of  the  i)osterior  surface.  To  the  left,  the  posterior  surface  is  in 
contact  with  the  left  kidney  and  suprarenal  capsule.  The  upper  border  in  the 
middle  line  abuts  against  the  crcliac  axis. 

The  inferior  surface  is  navYow ,  and  lies  over  the  fourth  part  of  the  duodenum  and 
beginning  of  the  jejunum.  The  transverse  meso-colon  is  continued  from  the  front 
of  the  head  along  the  border  sc^parating  this  surface  from  the  anterior  surface.  The 
splenic  end  of  the  transverse  colon  lies  under  the  left  extremity  of  this  surface. 
From  the  under  surface  of  the  transverse  meso-colon  a  layer  of  peritoneum  passes 
to  the  central  part  of  the  inferior  surface.  The  posterior  surface  is  devoid  of 
peritoneum. 

The  tail  of  the  pancreas  is  the  name  given  to  the  left  extremity  of  the  organ; 
it  touches  the  lower  part  of  the  inner  surface  of  tlie  spleen. 


Fig.  587. — The  Pancreas  and  its  Duct. 

duct  of  pancreas  duct  of  pancreas 


COMMON  BILE  DUCT 


The  duct  of  the  pancreas,  or  the  canal  of  ^^'irsung,  white  in  appearance,  runs 
from  nearly  the  extreme  left  of  the  gland,  concealed  by  the  proper  substance  of  the 
pancreas,  nearer  its  posterior  surface  than  the  anterior,  between  the  upjter  and  lower 
l)orders,  to  empty  into  the  lower  and  inner  part  of  the  second  ])ortion  of  the  duo- 
denum with  the  common  bile  duct.  It  runs  sinuously,  receiving  its  branches  as  it 
goes,  which  enter  nearly  at  right  angles.  These  branches  are  straight.  Its  diam- 
eter near  its  termination  is  one-tenth  of  an  inch.  The  pancreatic  duct  often  does 
not  join  the  common  bile  duct  until  its  termination,  running  side  l\v  side  with  it 
through  the  walls  of  the  intestine.  Occasionally  the  pancreatic  duct  opens  by  itself 
into  the  duodi-num. 

Blood-supply. — The  i)ancreas  receives  l>lood  from  the  splenic  artery  through 
its  })ancreatic  liranches.  and  from  the  superior  mesenteric  and  hepatic  Ity  the  infe- 
rior and  superior  ])ancreatico-duodenal  arteries,  which  form  a  loop  running  round, 
below,  and  to  the  right  of  its  head. 

The  blood  is  return<'d  into  the  jiortal  vein  by  means  of  the  splenic  an<l  superior 
mesenteric  veins. 

Lymphatics. — TIk^  lymjihatics  terminate  in  two  glands  whii-h  lie  on  the 
superior  mesenteric  artery. 

Nerves. — These  are  branches  of  the  solar  plexus  which  accomiianv  the  arteries 
enterinir  the  trland. 


988  THE   ORGANS   OF  DIGESTION 


THE  SPLEEX 

Position. — Tho  spleen— ono  of  the  ductless  glands — is  situated  for  the  most 
part  in  the  left  hypochondriac  region  (tigs.  577,  591).  It  is  deeply  placed  betAveen 
the  fundus  of  tlie  stomach  and  the  diaphragm,  and  in  the  line  of  the  axilla  it 
extends  between  the  eighth  and  eleventh  ril)S.  It  is  covered  Ijy  the  ninth,  tenth, 
and  eleventh  ribs  (lig.  583),  and  is  separated  from  them  by  the  diaphragm,  and  to 
a  smaller  extent  by  the  lung.  Its  upper  end  reaches  to  the  level  of  the  ninth 
tlioracic  spine,  and  its  loAver  end  to  the  level  of  the  first  lumbar  spine.  Its  inner 
extremity  is  Avithin  tAVO  inches  of  the  median  plane  of  the  body,  and  its  outer 
boundary  is  posterior  to  the  mid-axillary  line.  A  line  draAA'n  from  the  left  sterno- 
clavicular joint  to  the  tip  of  the  eleventh  left  rib  bounds  the  anterior  margin  of  the 
spleen. 

It  is  bluisli-red  in  colour,  is  soft,  and  easily  lacerated. 

Its  shape  varies,  and  depends  much  upon  the  condition  in  Avhich  it  is  exam- 
ined.    If  soft,  and  as  usuallv  found  after  removal  from  the  bodv,  it  can  onlv  l)e 


Fig.  588. — Outer  Aspect  of  the  Spleex. 


ANTERIOR  BORDER. 


said  to  have  tAvo  surfaces,  an  outer  convex  and  an  inner  concave;  but  if  examined 
after  it  has  been  hardened  in  situ,  after  the  manner  of  Professor  His,  it  is  seen  to  be 
of  a  much  more  precise  shape,  and  to  present  three  surfaces  (fig.  590). 

VicAved  from  the  outside,  it  presents  a  form  Avhich  is  irregularly  oval,  Avidei- 
above  tlian  Ix'loAV,  Avith  a  bulging  of  the  anterior  border  (fig.  588).  The  three 
surfaces  are  the  external,  anterior,  and  inner.  The  external  or  posterior  surface 
is  the  largest.  It  is  regularly  convex,  and  is  directed  outAvards  and  baclcAvards  and 
somcAA'hat  upwards  (ligs.  588,  590).  It  lies  against  the  commencement  of  the  arch 
of  the  diaphragm.  It  is  covered  l)y  peritoneum.  This  surface  is  named  by  Cuii- 
ningliam  the  })hrenic  surface.  It  is  separated  Ity  the  peritoneum  and  diaphragm, 
and  to  some  part  of  its  extent  by  the  pleura  and  lung  from  the  eighth,  ninth,  tenth, 
and  eleventh  ribs.  VicAved  from  the  inside,  the  tAVO  other  surfaces  are  seen  to  be 
divided  by  a  distinct  vertically  directed  ridge  (fig.  590).  The  anterior  of  the  tAVO 
looks  forAvards,  iuAvards,  and  a  little  doAVUAvards.  It  is  concave  from  above  doAvn- 
Avards,  and  from  side  to  side.  It  is  a  good  deal  tlie  larger  of  the  tw^o,  and  is  semi- 
lunar in  shape  (fig.  589).  It  is  in  contact  Avith  tlu-  great  cul-de-sac  of  th(>  stomach, 
Avith  the  tip  of  the  pancreas,  and  the  extreme  ])oint  of  the  splenic  fiexure  of  the 
colon  (fig.  586).  This  surfac(>  is  named  by  Cunningham  the  gastric  surface.  Near 
the  posterior  l)order  of  this  surface  and  bounded  I)y  the  ridge  is  seen  the  hilum  of 
the  spleen,  a  de})ressi()n  running  vertically  fi'om  above  doAVUAvards.     It  is  here  that 


THE  SPLEEX 


989 


tlie  splenic  artery  and  vein  enter  the  <ilan(l,  the  vein  being  V)eliin(l.  In  front  of  and 
behind  the  hiluni  is  seen  the  attachment  of  the  gastro-splenic  omentum.  The  ridge 
separating  this  surface  from  the  inner  surface  is  Avell  defined,  and  runs  from  the  top 
of  the  spleen  to  the  lower  part  of  the  ])osterior  border. 


Fig.  589. — Innkr  Aspect  of  the  Spleen. 


INNER  SURFACE 


ANTERIOR  SURFACE 


TIP  OR  LOWER  ENO 


EOGEOFGASTRO-SPLENIC 
OMENTUM 


The  inner  or  renal  surface  is  much  narrower  and  shorter  than  the  anterior. 
It  is  only  slightly  concave  in  l)oth  directions.  It  is  directed  inwards  antl  down- 
wards, and  is  in  relation  with  the  outer  border  of  the  left  kidney. 


Fui.  590.— Transverse  Section  of  the  Body  at  the  Lower  Part  of  the 
Epigastric  Eegion.     (Kiidiuger. ) 


TRANSVERSE  COLON 


SUPRA-RENAL  - 
CAPSULE 


The  anterior  border  of  the  sjjleen  is  more  defined  than  the  ])osterior.  is 
sharper,  and  is  marked  by  several  notches,  one  of  which  is  occasionally  larger 
than  the  others.     This  border  is  convex.      The  posterior  border  is  shorter  and 


990 


THE   ORGANS   OF  DIGESTION 


straighter.  It  separates  the  renal  and  jjhrenic  surfaces.  The  term  inner  border 
is  api^lied  to  the  rid<;c  Ijetween  the  gastric  and  renal  surfaces. 

The  lower  end  of  the  spleen  is  blunt  and  presents  a  triangular  area  which  Cun- 
ninuhani  calls  the  l)asal  surface.  It  lies  against  the  splenic  flexure  of  the  colon 
and  the  costo-colic  ligaments.  The  term  basal  ai)plied  to  this  extremity  is  due  to 
the  circumstance  that  the  shape  of  the  spleen  //(  .-iitn  is  that  of  an  irregular  tetra- 
hedron with  its  liase  below  (Cunningham). 

The  spleen  is  set  obliquely  in  the  body.  Its  long  axis  about  corresponds  to 
the  line  of  the  tenth  rib. 

In  size  it  varies,  owing  to  the  fact  that  it  increases  in  dimensions  after  food 
and  under  other  circumstances.      In  the  adult  it  measures  generally  about  five  to 

Fig.  591.— ViivW  of  the  Spleen,  etc.,  from  behind.     (RUdiuger.) 


six  inches  in  length,  three  or  four  inches  in  breadth,  and  one  to  one  and  a  half 
inches  in  thickness;  its  usual  volume,  according  to  Krause,  is  from  nine  and  three- 
quarters  to  lifteen  cubic  inches.  Its  average  weight  is  one  hundred  and  seventy 
grammes. 

It  is  entirely  surrounded  by  ])eritoneum  exee])t  at  the  liilum.  On  either  side  of 
the  hilum  the  gastro-splenic  ligament  is  attached.  This  reflexion  of  ])eritoneuu), 
sometimes  called  the  gastro-splenic  omentum,  ])asses  inwards  to  the  left  extremity 
of  the  stomach  and  the  left  margin  of  the  great  omentum.  N  fold  of  peritoneum, 
the  i)hreno-splenic  ligament,  connects  the  upper  end  of  the  spleen  to  the  dia- 
])hragm.  The  reflection  of  peritoneum  from  the  spleen  to  the  left  kidney  is  called 
the  lieno-renal  ligament. 


THE  PERITONEUM 


m\ 


Varieties. — Tlic  jn-incipal  iK-ouliarity  is  due  to  the  presence  of  supplementary 
spleens  (lieneuli),  found  in  tlie  u;astro-splenic  omentum,  or  less  often  in  the  jrreat 
omentum.  From  one  to  twenty  of  these  small  l)odies  may  he  met  with.  They 
are  red  and  n^und,  of  the  same  structure  as  the  spleen,  and  vary  in  size  from  a  ]i('a 
to  a  walnut. 

Structure. — Bene-atli  the  eoverinj^  of  ])eritoneum  is  a  thin  but  tough  aipMik  of 
areolar  tissue,  ealh'd  tlie  tunica  propria,  which  is  very  adherent  to  the  serous  mem- 
brane. It  is  remarkably  elastic.  It  sends  a  jjrolongation  in  at  the  hilum,  which 
follows  and  sup})orts  the  vessels  to  their  termination.  Within  the  ea])sule  is  the 
•pulp.  This  is  a  very  soft  frialile  tissue  of  a  dark  reddish-brown  color,  not  unlike 
grumous  blood  in  color  and  consistence.  It  can  be  squeezed  out  from  the  cut 
s{)leen,  and  then  it  will  lie  seen  that  the  whole  organ  is  pervaded  by  a  network  of 
tine  fibres  which  support  the  pulp.  The  larger  of  these  come  off  directly  from  tlie 
fibrous  capsule,  and  are  called  trabecule. 


In*  Front. 
Stomach  ;  splenic  flexure  of  colon. 


Outer  Side. 

Diaphragm  ;  ninth  to  eleventh 
ribs  between  axillary  line. 


GENERAL  RELATIONS 

OF 

THE  SPLEEN 


Inner  Ride. 

Stomach;  pancreas;  left  kidney 
and  capsule. 


Behind. 
Diaphragm. 

Blood-supply. — The  si^leen  receives  its  lilood  from  the  splenic  artery,  which  is 
very  large  in  i)roportion  to  the  body  it  is  going  to  supply.  It  divides  before 
entering  into  about  six  branches.  The  artery  is  very  tortuous.  The  vein,  on  tiie 
other  hand,  is  straight,  and  lies  below  the  artery. 

.  The  lymphatics  are  divided  into  a  superficial  and  a  deep  set.  The  former 
forms  a  ])lexus  beneath  the  peritoneum.  The  latter  are  derived  from  fine  peri- 
vascular spaces  in  the  adenoid  tissue  around  the  vessels.  They  join  at  tlie  hilum, 
and  ])ass  l)etween  the  layers  of  the  gastro-hepatic  omentum  to  the  glands  in  that 
neighI)ourliood. 

The  nerves  are  from  the  solar  plexus.     They  pass  in  along  the  splenic  artery. 


THE    EVOLUTION    OF    THE    PERITONEUM    AND    AX    EXPLANATION 
OF    ITS   ARRANGEMEXT   IX   THE   HUMAX    BODY 

The  peritoneum  is  a  serous  membrane,  and  is  identical  with  other  like-named 
membranes  which  are  less  complicated  in  their  disposition.  It  differs  in  no 
essential  ])articular  from  the  ])leura.  from  the  pericardium.  fr<jm  the  tunica  vagi- 
nalis, from  the  synovial  mend)rane  of  a  joint,  or  from  the  simph'  vaginal  sheath  of 
a  tendon.  In  all  there  is  practically  a  closed  sac  of  thin  membrane,  which  is  so 
disposed  as  to  both  line  a  cavity  and  to  invest  the  structures  which  encroach  upon 
tiiat  cavity. 

Imagine  a  pleiu'al  cavity  from  which  the  lung  ha<l  vanished  without  disturbance 
of  parts.  The  membrane  lining  it  would  ajtpear  as  a  simjjle  ser<»us  bag.  Xext 
conceive  the  lung  gradually  budiling  towards  tliis  sac.  It  would  ]»usli  the  mem- 
l>rane  before  it,  and  as  it  did  so  it  would  both  encroach  upon  the  cavity  lined  liy 
the  mend)rane,  and  be  itself  covered  or  invested  l»y  it. 

AVhen  the  lung  had  attained  nearly  to  the  dimensions  of  the  rigid  cavity  it  was 
occupying,  the  serous  lining  would  i)e  found  to  invest  the  whole  of  it  exce]>ting 
only  its  pedich — tlie  stalk  of  the  original  bud — the  root  of  tlie  lung. 


092 


THE   ORGANS   OF  DIGESTIOX 


Although  the  thoracic  space  might  be  ahnost  obliterated,  the  lung  would  i^till 
remain  eiitirelv  outride  the  cavity  of  the  serous  sac.  It  would  be  convenient  then 
to  speak  of  tlie  undisturlied  layer  which  still  lined  the  tiioracic  space  as  ihe  parietal 
layer,  and  the  layer  which  had  come  in  a  passive  way  to  invest  the  lung  as  the 
vi'<ceral  layer. 

In  the  abdomen  a  similar  condition  exists.  Imagine  all  the  viscera  to  have 
vanished  from  the  abdominal  cavity.  A  great  space  would  exist,  bounded  above  by 
the  diaphragm,  l>elow  by  the  pelvic  floor,  and  in  front  and  behind  by  the  abdominal 
parietes.  This  space  would  be  evenly  lined  by  the  peritoneum  in  the  form  of  a 
simple  closed  sac.  As  the  viscera  reappeared  they  would  emerge,  as  it  were,  from 
the  posterior  wall  of  the  belly,  and  would  project  into  the  cavity  of  the  abdomen. 
In  so  doing  thev  would  push  before  them  the  peritoneum  lining  the  posterior  wall 
of  the  cavitv.  aiul  would  each  in  turn  become  invested  by  the  displaced  memltrane. 
All  the  abdominal  viscera  are  outside  the  peritoneal  cavity,  although  they  are 
obviously  within  the  abdominal  space.  The  peritoneal  sac  remains  entirely  empty, 
anil  its  wall,  with  the  exception  of  the  Fallopian  orifices,  is  unbroken. 

That  part  of  the  simple  sac  which  lines  the  anterior  abdominal  parietes  is 
practically  the  only  part  which  retains  its  original  connections  undisturbed. 

One  main  function  of  a  serous  membrane  is  to  minimise  the  effects  of  friction. 
Those  ^^scera  wliich  are  exposed  to  most  movement,  such  as  the  small  intestines, 


Fig.  592. — Diagram  of  the  Peimitive  Alimextary  Canal. 
(A  :  a  indicates  the  vitello-intestinal  duct  :  b  points  to  the  future  position  of  the  cseoum.) 


are  the  most  completely  invested  by  the  smooth  membrane;  those  whieh  ivmain 
fixed,  such  as  the  kidney,  are  only  casually  invested.  The  movements  of  the 
viscera  in  respiration,  the  alteration  in  shape  and  position  which  Avill  occur  in  such 
organs  as  the  stomach  and  bladder,  are  provided  for  by  the  peritoneum  in  such  a 
manner  that  these  movements  are  practically  without  friction. 

The  viscera  contained  in  the  abdomen  are  not  only  numerous,  but  they  are  of 
very  complex  outline  for  the  most  part,  and  they  are  disposed  in  a  manner  which 
tends  to  greatly  confuse  their  relations  to  one  another. 

A  bare  description  of  the  peritoneum,  as  it  is  met  with  in  the  human  subject, 
must  needs  be  intricate  and  complicated,  and  if  considered  without  reference  to 
more  primitive  and  simpler  conditions  is  almost  inexplicable.  The  descrij^ion 
may  be  followed,  but  it  needs  interpretation,  and  no  account  of  this  membrane  can 
be  "considered  to  be  satisfactory  unless  it  be  rendered  evident  how  the  complex 
arrangement  has  come  aljout,  and  unless  the  student  base  his  conceptions  upon  the 
simple  and  rudimentary  disposition  which  an  elaborate  development  of  parts  ami 
a  remarkable  specialisation  of  structure  have  rendered  intricate  and  confusing. 

The  readiest  idea  of  the  disposition  of  the  peritoneum  is  to  be  derived  from  a 
study  of  the  development  and  most  rudimentary  forms  of  that  membrane.  Such 
a  study  is  founded  upon  an  examination  of  the  human  embryo  at  various  periods, 
and  of  the  peritoneum  in  the  mammalia  and  lower  animals. 


THE   M.niKXTAUY   ClXAL 


993 


The  simple  alimentary  tube. — The  alimcntarv  canal  first  aj>pears  as  a  simple 
tube  lyin.i4al)()Ut  ihv  niciliau  line  in  front  of  the  ])(^sterior  alidoniinal  parietes,  and 
placed  vertically.  This  tube  is  corniected  with  the  posterior  parietes  by  a  simple 
fold  of  ])eritoneum — a  species  of  fr<nieral  mesentery  (fig.  ol)2). 

The  fact  that  the  abdominal  cavity  is  at  an  early  period  open  in  front,  and  that 
the  rudimentary  intestine  protrudes  beyond  the  limits  of  the  future  cavitv  may  be 
disreganlcd.  The  cavity,  such  as  it  is,  is  lined  by  a  membrane  wliicji  is  later 
recognisable  as  the  perit<^»neum,  and  tiie  general  mesentery  is  produced  l)v  the 
growth  and  protrusion  forwanls  of  the  elementary  Ijowel  from  the  tissues  liehind, 
i.e..  outside  the  peritrMieum. 

The  simple  straight  tube,  suspended  on  the  ])osterior  mesial  line  by  its  fokl  of 
peritoneum,  becomes  in  due  course  differentiated  (fig.  592). 

Theu[)per  part  becomes  the  stomach;  the  bowel  immediately  beyond  forms  the 
'luodenum;  then  follow  the  small  intestine;  and  lastly  the  colon  and  rectum. 

The  point  of  separation  of  the  small  bowel  from  the  colon  is  indicated  bv  the 
appearance  of  the  ciecum. 

It  will  be  understood  also  that  the  up]ier  part  of  the  mesial  peritoneal  fold  is 
called  the  meso-gaster  (  m-g,  fig.  593);  the  next  part  the  meso-duodenum   (^m-d); 

Fig.  593.— Di.iGKAM  of  the  Primitive  Alimentary  Canal. 


and  the  succeeding  portions,  in  order,  the  mesentery,  the  meso-colon,  andthemeso- 
rectuin  (fig.  598,  mks,  m-c,  m-r).  The  stomach  liecomes  more  distinctly  marked; 
the  tul)e  below  lengthens  and  forms  an  intestinal  loop,  which  in  the  embryo  i)ro- 
jects  beyond  the  site  of  the  future  umbilicus,  taking  the  mesentery  with   it. 

This  elementary  condition  of  the  intestinal  canal  jx-rsists  in  certain  fully 
develoi)ed  animals.  As  an  example  may  l)e  taken  the  alimentary  canal  of  the 
salamander,  as  depicted  in  fig.  594.  In  this  figure  the  vi.sci'ra  are  shown  undis- 
turbed. In  fig.  595,  the  })eritoneum  has  been  drawn  forwards  so  as  to  show  the 
])arts  in  one  median  plane,  and  well  represents  tiie  simjile  arrangement.  In  many 
mammals  among  the  Edenttites  the  simple  vertical  median  fold  of  peritoneum  is 
retained.  This  is  shown  in  the  great  anteater,  and  in  Hoffman's  sloth  (fig.  590). 
wliere  the  intestinal  canal,  from  the  pylorus  to  the  rectum,  is  still  quite  simple, 
altliough  it  is  of  considerable  h-ngth,  and  is,  as  a  conse<iuence,  thrown  into 
numerous  coils.  The  whole  of  this  long  tube  is  su)>i)orte(l  by  a  single  median  fold 
of  peritoneum  attached  to  the  midtlle  line  behind,  and  serving  the  purpose  of 
meso-duodenum,  mesentery,  meso-colon.  and  meso-rectum  in  one. 

Where  this  fold  is  attachi'd  behind,  ruiLs  the  aorta;  and  In'twi-en  the  layers  of 
the  fold  vessels  pass  forwards  to  su})ply  the  visci-ra.     (Fig.  592,  B,  a.  represents  the 


994 


THE   ORGANS   OF  DICESTION 


intestinal  tube  to  whicli  an  artery  is  passing.)  Tliere  will  l)e  an  artery  to  the 
stomach  (1,  tig.  593)  and  the  great  nie-st-nterie  artery.  The  latter  vessel  will  supply 
the  rudimentary  duodenum,  the  small  intestines,  the  caecum,  and  such  part  of  the 
colon  as  is  later  on  known  as  the  ascending  and  transverse  segments.  The  arrange- 
ment of  tlie  vessel  is  shown  in  tigs.  598,  2,  and  596. 

The  descending  colon  and  rectum  are  supi)lied  by  a  separate  vessel,  the  inferior 
mesenteric,  direct  from  the  aorta  (3,  figs.  593  and  596). 

At  the  summit  of  the  primitive  loop  which  forms  the  principal  part  of  the  intes- 
tine will  be  the  vitello-intestinal  duct  or  vitelline  stalk  (v.  d,  fig.  593;  a, fig.  592, A). 
It  is  to  this  point  that  the  great  or  superior  mesenteric  artery  is  directed.  The 
morphological  ending  of  the  superior  mesenteric  artery  is  at  this  spot,  while 
branches  pass  off  from  either  side  of  it.  The  student  may  be  reminded  that  a  trace 
of  the  vitelline  duct  may  persist  in  the  form  of  a  process  known  as  Meckel's 
(Hverticulum,  and  that  this  process,  when  existing,  is  situated  in  the  lower  part  of 
the  ileum  not  far  from  the  csecum  (page  967).  In  the  adult  the  trunk  of  the 
artery  may  be  represented  by  a  line  drawn  from  its  place  of  origin  to  a  point  on  the 
ileum  from  one  to  three  feet  from  the  caecum. 

The  primitive  intestinal  loop  increases  in  length,  and  forms  longer  and  more 
complex  coils.  A  large  part  of  these  coils  will  lie  without  the  abdomen,  the 
anterior  abdominal  w'all  being  still  incomplete. 

As  the  loop  lengthens,  a  species  of  neck  forms  which  tends  to  become  narrower. 


Fig.  594. — Alimentary  Canal  of  Salamandra  maculosa. 


GASTRO-HEPATIC 
OMENTUVI 


Tlie  upper  part  of  this  neck  or  strait  is  bounded  or  formed  by  the  duodenum;  the 
lower  part  by  that  portion  of  the  large  bowel  which  is  at  a  later  period  knoAvn  as 
the  transverse  colon  (fig.  593). 

The  transverse  colon  and  the  duodenum  are  thus  brought  near  together,  and  it 
is  notew'orthy  that,  no  matter  how  complex  the  relations  of  the  bowel  become, 
these  segments  of  the  intestinal  tube  are  never  separated.  In  the  narrow  neck 
formed  betAveen  them  runs  the  trunk  of  the  superior  mesenteric  artery.  The  great 
loop  beyond  this  neck  will  form  the  small  intestine,  the  csecum,  and  the  ascending 
colon.  The  descending  colon  retains  its  sim])le  connections  with  the  median  line 
(fig.  593). 

The  mesentery  does  not  increase  in  the  same  ])roportion  as  the  intestines  grow, 
and  hence  the  bowel  is  thrown  into  innumerable  convolutions.  In  the  human 
subject  the  increase  in  the  breadth  of  the  mesenter}''  is  somewhat  more  noteworthy 
than  its  increase  in  length. 

There  is  a  time,  then,  when  the  great  mass  of  the  intestine  is  supported  by  a 
simple  but  extensive  mesentery,  which  is  entirely  free,  and  which  is  attached 
behind  by  means  of  a  narrow^  neck  bounded  by  the  duodenum  and  the  right  end  of 
the  transverse  colon,  and  through  which  the  superior  mesenteric  artery  runs. 

The  great  intestinal  loop  ^n-ojects  at  first  anteriorly  and  mesially.  The  small 
intestine  is  above,  the  large  intestine  below  (figs.  593,  595). 


THE   IXTFSTIXAL    CAXAL 


995 


As  the  coils  of  bowel  become  more  fully  developed,  it  will  be  seen  that  all  the 
small  intestines  lie  to  the  right  hand  side,  and  the  eiecum  and  the  connnencement 
of  the  colon  to  the  left.  The  vasa  intestini  tenuis  of  the  superior  mesenteric  artery 
consi'(|uently  arise  from  the  right  side  of  the  vessel,  while  the  ileo-colic,  right  colic, 
and  middle  colic  all  arise  from  the  left  (fig.  59o). 

Further  devel()j)ment  in  this  direction  may  not  proceed,  and  the  condition  al)()ve 
described  is  met  witli  in  some  of  the  lower  mammals  as  a  permanent  arrangement 
(tig.   ')9(;). 

The  rotation  of  the  intestinal  canal. — As  development  proceeds,  the  jjiates 
which  are  forming  the  anterior  abdominal  parietes  approach  one  another,  and  the 
closure  of  the  cavit}'^  of  the  abdomen  is  immment.  The  loops  which  have  up  to 
tliis  time  jirojected  beyond  the  site  of  tlie  future  umbilicus  are  now  withdrawn  into 
the  abdomen. 

About  this  time  a  remarkable  and  (juite  characteristic  rotation  of  the  general 
mesenteric  fold  takes  place.  The  rotation  is  from  left  to  right,  and  is  around  an 
axis  whit'h  may  be  represented  by  a  line  drawn  from  the  neck  or  pedicle  of  the 
common  mesentery  to  the  site  of  the  vitelline  duct.  This  is  in  fact  the  line  of  the 
superior  mesenteric  artery  (fig.  593).  The  rotation  is  therefore  at  the  neck  of  the 
great  and  complex  loop  of  intestine,  which  neck,  as  has  been  already  said,  is 
bounded  by  the  duodenum  and  the  right  end  of  the  transverse  colon. 


Fig.  595. — Alimentary  Canal  of  Salamaajjua  maculosa. 


As  a  result  of  this  rotation,  the  cajcum  and  the  ascending  colon  turn  over  to  the 
right,  while  the  great  mass  of  the  small  intestines  is  brought  to  the  left  (fig.  597). 

The  lower  end  of  the  duodenum  will  consequently  be  carried  to  the  left;  the 
transverse  colon  will  lie  in  front  of  it,  instead  of  below  it;  and  the  superior  mesen- 
teric artery  (2,  tig.  597),  which  must  still  run  between  these  two  segments  of  the 
1  towel,  will  now  be  descrilx'd  as  passing  over  the  duodenum,  or  as  crossing  its 
anterior  surface.  It  is  needless  to  say  that  in  the  fully-developed  l)ody  this  artery 
crosses  the  left  end  of  the  third  ])art  of  the  duodenum,  and  is  l)ehind  the  right  end 
of  the  transverse  colon.  It  will  be  seen  that,  in  spite  of  this  revolution,  the 
duodenum  and  the  transverse  colon  still  retain  their  relations  to  one  another,  and 
still  mark  the  neck  or  pedicle  of  attachment  of  the  common  mesenteric  fold. 

The  effect  of  this  rotation  of  the  intestinal  tube  is  shown  in  the  diagram 
(fig.  597). 

The  caecum  and  ascending  colon  are  now  moved  to  the  right;  the  transverse 
colon  is  more  distinctly  transverse;  the  small  intestine  has  ))asse(l  over  to  the  left 
side.  The  right  side  of  the  mesentery  has  become  the  left  side,  and  rice  verm  ;  and 
the  vasa  intestini  tenuis  now  ai)i)ear  to  arise  from  the  left  border  of  the  superior 
mesenteric  artery  instead  of  from  the  right  (tig.  597).  The  duodenum  is  almost 
hidden  from  view,  and  has  been  brought  into  close  contact  with  the  vertebral 
column.  The  descending  colon  remains  unchanged,  and  is  supported  l)y  the  still 
undisturbed  median  fold  of  the  jteritoneum. 


996 


THE   ORGANS   OF  DIGESTION 


Tlie  duodenum  still  lias  a  lueso-duodciiuin,  and  is  still  entirely  invested  by 
peritoneum. 

In  man  further  changes  take  place,  hut  in  mammals  below  man  the  condition 
just  described  is  that  which  rc^presents  the  normal  arrangement.  Fig.  597  may  be 
considered  to  represent  in  diagrannnatic  fashion  the  simple  intestine  of  a  carnivo- 
rous animal. 

In  the  human  sulgect  even  development  may  not  proceed  bex'ond  this  point, 
and  the  condition  detailed  may  be  met  with  in  the  adult  as  a  permanent  arrange- 
ment. I  have  described  some  examples  of  this  ( '  The  Anatomy  of  the  Intestinal 
Canal  and  Peritoneum  in  Man,'  London,  1885;  and  'Lancet,'  Oct.  13,  1888).  In 
these  instances  the  whole  of  the  small  intestine,  together  with  the  caecum  and  the 
ascending  colon,  were  slung  from  a  common  mesentery,  the  attachment  of  which  to 
the  posterior  parietes  was  by  a  narrow  neck  giving  passage  to  the  superior  mesen- 
teric artery,  and  bounded  by  the  duodenum  and  the  transverse  colon.     In  these 

Fig.  596.— Alimentary  Canal  of  Cholcepus  Hoffmaiunl 


sul)jects  there  was  no  trace  of  the  mesentery  proper  as  it  is  found  in  the  normal 
human  body.  The  duodenum  had  been  deprived  of  its  meso-duodenum,  and  the 
descending  meso-colon  was  comparatively  scanty;  but,  with  these  and  some  minor 
exceptions,  the  resemblance  of  the  arrangement  of  the  bowels  to  that  met  with  in 
the  lower  animals  was  very  exact.  It  is  the  existence  of  this  inmiature  condition 
that  predisposes  to  certain  forms  of  twist  or  volvulus  of  the  bowel. 

The  progress  of  this  rudimentary  revolution  of  the  intestinal  tube  may  be  noted 
by  observing  the  progress  of  the  caecum. 

That  prominent  diverticulum  lies  at  first  below  the  looj)  forming  the  lesser 
bowel,  and  then  to  its  left  side.  It  is  at  first  Avithout  the  abdomen,  and  is  gradu- 
ally withdrawn  in  the  progress  of  development  through  the  rapidly  closing 
umbilical  opening. 

It  then  lies  about  the  middle  of  the  belly  and  just  below  the  liver.  Later,  it 
passes  to  the  right  side,  and  then  descends  into  the  right  iliac  fossa. 

It  may  be  permanently  arrested  at  any  point  of  its  course.  In  the  condition 
known  as  the  congenital   umbilical   hernia,    the  gap   in   the    anterior  abdominal 


THE   PKRITOXFJM 


9i>7 


parietes  has  nover  closed,  and  tlic  })rittrudiii<:  looj)  of  l)owi'l  has  never  heen  quite 
witluh'awn  into  tlie  al)don)en.  The  sae  of  such  a  hernia  is  made  out  of  the  tissues 
of  the  Tuiibilieal  cord,  and  the  contents  are  usually  the  c;ecuni  and  lower  ]»art  of 
the  ileum,  and  not  infrequently  a  Meckel's  diverticulum.  As  has  been  mentioned 
already,  the  ciecum  may  l)e  found  near  the  middle  line  or  in  the  right  hypochon- 
driac region  (page  971).      It  is  then  spoken  of  as  undescended. 

Final  changes  in  the  peritoneum. — Further  changes  in  the  position  of  the 
intestine  and  in  the  arrangement  of  the  peritoneum  are  finally  l)r()Ught  about,  and 
these  changes  are  almost  entirely  limited  to  the  human  subject.  The  intestine 
grows,  and  other  abdominal  viscera  are  encroaching  upon  the  {leritoneum.  This 
membrane  is  mol)ile,  is  easily  drawn  from  one  ])oint  to  another,  and  is  capable  of 
consideral)le  adjustment.  It  does  not,  however,  continue  to  grow  at  the  same  rate 
as  the  viscera  which  it  serves  to  cover.  The  peritoneum  is  relatively  more  extensive 
in  the  frtus  than  in  the  adult,  and  in  the  lower  mammals  than  in  man. 

If  the  viscera  grow  out  of  proportion  to  the  peritoneuu),  it  is  evident  that  the 
reflections  of  that  membrane  must  here  and  there  be  shortened;  and  it  is  possible 
that  a  viscus  which  was  at  one  time  entirely  covered  by  i)eritoneum  may  in  due 
course  become  almost  bared  of  it.  This  is  so.  In  the  diagram  (fig.  598)  a  trans- 
verse section  of  the  body  is  imagined,  the  section  traversing  the  spot  where  the 
duodenum  and   transverse  colon  are  in   relation  at  the  neck  of  the  great  comn)on 


Fig.  5S>7. — Uiagkam  to  show  thk  Rotation  of  the  Intestinal  Canal. 


mesentery.  Here,  by  reason  of  the  rotation  of  the  intestine  from  left  to  right,  the 
mesenteric  lamina  has  become  folded  ujjou  itself  (A,  fig.  598).  The  fold  would 
be  V-sha))ed,  ojjcn  al)ove,  but  coming  to  a  point  below.  On  transverse  section  the 
meso-duodenum  (m-d)  and  transverse  meso-colon  (m-c)  can  be  seen  side  by  side. 
Now  a  constantly  increasing  demand  upon  the  peritoneum  is  made  by  the  rapidly 
growing  viscera.  The  meml)rane  is  drawn  in  this  directi(jn  and  in  that.  There  is 
some  symmetry,  however,  within  the  abdomen,  and  the  mendjrane  may  be 
conceived  to  be  drawn  ecjually  upon  in  the  direction  of  the  arrows  r  and  l. 

The  result  of  such  traction  upon  the  |)eritoneum  in  this  particular  instance  will 
be  to  lessen  the  length  of  the  transverse  meso-colon,  and  to  use  up  the  meso-duo- 
denum altogether  (fig.  598,  B).  That  piece  of  bowel  is  indeed  at  last  left  uncovered 
by  peritoneum  behind,  and  is  brought  into  contact  with  the  ])osterior  ])arietes.  The 
serous  membrane  which  formed  the  nu'so-duodenum  has  been  utilised  to  ali'ord  a 
covering  for  adjacent  viscera,  which  are  increasing  in  size,  and  are  pushing  the  peri- 
toneum before  tliem  as  they  advance.  In  this  particular  region  of  the  abd(»men 
the  growth  of  the  liver,  stomach,  anil  sideen  make  great  demands  u]»on  the  adjacent 
jK'ritoneum.  As  has  been  already  said,  it  is  evident  that  the  growth  of  the  general 
sac  of  the  peritoneum  does  not  keei>  pace  with  the  growth  of  the  structures  it  covers, 


998  THE   ORGANS   OF  DIOKSTION 

and  tliat  it  is  possible  for  one  organ  to  be  elothed  with  peritoneum  at  the  expense 
of  another. 

To  complete  the  account  of  the  general  relation  of  the  peritoneum  to  the  intes- 
tine, the  following  changes  remain  to  be  noticed: — 

The  meso-colon. — The  descending  colon  is  displaced  by  the  growth  of  the 
rest  of  tilt'  bowel  to  the  left  side,  and  comes  to  occupy  the  position  which  it  holds 
in  the  fully  developed  body.  The  i)rimitive  meso-colon  is  displaced  also  to  the 
left,  and  survives  as  the  descending  meso-colon,  the  sigmoid  meso-colon,  and  the 
meso-rectum  (fig.  599).  It  may  be  so  curtailed  that  no  distinct  fold  that  can  be 
called  a  descending  meso-colon  is  left,  and  the  posterior  part  of  the  bowel  is  in  such 
a  case  found  to  be  more  or  less  uncovered  by  the  peritoneum.  The  meso-rectum 
is  a  genuine  and  but  little  disturbed  relic  of  the  simple  median  vertical  fold  of  the 
primitive  body. 

Fig.  598. — Diagram  to  show  the  Relation  of  the  Peritoneum  to  the  Duodenum. 

A 


C. 


The  duodenum  is  more  or  less  bared  of  peritoneum,  especially  so  far  as  its  third 
part  is  concerned. 

The  ascending  colon  has,  like  the  descending  colon,  been  deprived  of  a  con- 
siderable amount  of  its  peritoneum.  This  membrane  originally  belonged  to  the 
common  mesentery,  but  so  much  of  it  may  have  been  abstracted  from  the  bow^el 
that  this  part  of  the  colon  may  be  free  from  peritoneum  behind,  or  may  be  con- 
nected to  tlic  posterior  ])arietes  by  a  short  meso-colon.  The  parietal  attachments 
(so-called)  of  this  ascending  meso-colon  are  entirely  acquired,  and  have  no  relation 
whatever  to  tlu;  ])rimary  attachment  of  the  median  fold — the  primitive  meso-colon 
— to  tlie  {)ostcrior  wall  of  the  a[)domen  (fig.  599). 

The  mesentery. — The  mesentery  proper — the  fold  belonging  to  the  small 
intestines — in  like  manner  and  by  a  similar  process  acquires  a  new  connection  with 
the  posterior  parietes.  Jn  using  the  term  '  new  connection,'  it  must  be  understood 
that  the  sac  of  the  peritoneum  remains  quite  unbroken,  and  that  the  numerous 
duplicatures  of  the  meml)rane  have  simply  been  so  readjusted  and  disi)laced  that  it 
has  in  more  i)oints  than  one  a  refiexion  from  the  posterior  wall  of  the  abdomen. 


THE  MESEXTERY 


999 


The  mesentery  is  described  as  Ix-iiig  '  attju-hcd  posteriorly  by  a  very  sliort  bonU-r 
which  extends  from  the  h'vel  of  the  attaelniient  of  the  traiisverse  meso-colon  to  the 
left  of  the  middle  line  directly  down  to  the  right  iliac  fossa  where  the  ilenni  falls 
into  the  caecum'  ((^uain;.  This  is  the  ])recise  attachment  made  evident  when  the 
intestines  have  been  all  cut  away,  and  nothing  but  the  stumj)  of  the  mesenterv  is 
left  (fig.  599).  The  attachment  is,  however,  wholly  acquired  or  secondarv.  and 
has  been  brought  about  by  an  extensive  readjustment:  of  the  peritoneum.     The  real 


Fig.  599.— Diaoram  to  show  thk  Lines  along  which  the  Peritoneim  leaves  the 
Wall  of  the  Abdo.men  to  inve.st  the  Viscera.     (Cuuniughain.j 

Falciform  ligament    Left  lateral  ligament 
of  liver  of  liver 


Vena  cava 


COMMENCE- 
MENT OF 
COLON 


Gaetro-phrenio 

ligament 
(ESOPHAGUS 


GASTRO-SPLENIC 
OMENTUM 


Splenic  artery 
Costo-eolic  lig. 

TRANS.MESO-COLON 
•S'lperior  iiu'sph- 

Ipric  nrlerij 
BARE  SURFACE  tOR 

DESCENDING 

COLON 


SIGMOID  MESO- 
COLON 


attachment  of  the  mesentery  is  about  tlie  origin  of  the  superior  mesenteric  ailerv, 
and  this  attachment  obtains  in  mammals  Ix'low  man.  In  fig.  599  is  shown  the 
posterior  wall  of  the  abdomen  after  the  removal  of  the  intestines,  togetlier  with 
the  stomach,  liver,  and  spleen.  The  lines  of  the  various  perit<tneal  reflexions 
are  depicted  in  a  diagrammatic  manner.  A  line  drawn  downwards,  commencing 
at  the  falciform  ligament  of  the  liver,  and  continued  past  the  a'soj^hagus.  througji 
th<i   gastro-splenic    omentum,    descending    meso-colon.    and    sigmoid    meso-colon, 


1000 


THE   ORGANS   OF  DIOESTIOX 


represents  the  ori<;iiial  attaehment  of  the  ])riuntiv(^  median  fold.  All  other  lines 
of  reflexion  must  l)e  regarded  us  acquired  or  secondarv. 

The  meso-gaster. — It  now  remains  to  consider  what  becomes  of  the  upper 
part  of  the  simple  primitive  fold  of  peritoneum — the  meso-gaster  (m-g,  tig.  598). 

The  stomach  enlarges,  assumes  more  of  its  characteristic  outline,  and  becomes 
less  vertical. 

The  liver  may  be  regarded  as  an  outgrowth  from  the  duodenum.  Its  connec- 
tions with  the  great  veins  of  the  heart  cause  it  to  extend  upwards  and  to  the  right 
side.  As  it  grows  it  se])arates  the  layers  of  the  highest  part  of  the  peritoneal  fold, 
and  from  this  memljrane  it  receives  a  covei'ing.  The  remains  of  the  primitive 
mesial  fold  persist  in  the  form  of  tlie  falciform  ligament  (tigs.  593,  595,  and  599). 

The  gastro-hepatic  omentum. — The  connection  of  the  liver  to  the  stomach  is 
intimate,  partly  througli  the  association  of  the  great  gland  Avith  the  duodenum,  and 
partly  through  certain  blood-vessels  which  pass  to  the  stomach  and  liver  from  the 
aorta.  As  the  stomach  enlarges,  its  duodenal  end  is  drawn  towards  the  right  side; 
the  viscus  becomes  transverse,  the  left  wall  becomes  anterior,  and  the  right  poste- 
rior. The  layer  of  peritoneum  which  stretches  between  the  two  organs  is  called  the 
gastro-hepatic  or  lesser  omentum.     The  right  or  free  margin  of  this  omentum  was 


Fig.  600. — Diageabi  to  show  the  Formation  of  the  Great  Omextum. 


qastro-}ie]iat.  om 


ME50- 
W7    RECTUM 


originally  anterior,  and  the  whole  fold  is  directly  derived,  with  but  little  dis- 
turbance of  the  membrane,  from  the  upper  part  of  the  primitive  meso-gaster  (figs. 
593,  595). 

The  great  omentum. — The  formation  and  disposition  of  the  great  omentum 
are  a  little  ditticult  to  follow  in  the  adult  human  species,  and  the  student's  concep- 
tion of  the  right  character  of  this  fold  may  l)e  a  little  distorted  by  a  study  of  certain 
diagrams  which  show  the  omentum  from  one  point  of  view  only.  In  mammals  and 
in  the  human  fo'tus  the  dis})osition  of  the  great  omentum  is  readily  appreciated. 

This  fold  ai)pears  as  a  bulging  of  the  meso-gaster  forwards  and  to  the  left. 
When  the  stomach  has  assumed  its  final  position,  this  bulging  of  the  membrane  is 
of  course  entirely  in  the  direction  forwards. 

At  first  the  great  omentum  forms  a  shallow  and  wide-mouthed  bag.  Its  appear- 
ance is  such  as  could  be  produced  in  imagination  if  the  fingers  were  to  be  pressed 
against  the  right  (pf)sterior )  side  of  the  meso-gaster,  and  were  to  force  a  l)ag  of  the 
yielding  membrane  Ijeforethem.  The  pendulous  bag-like  projection  could  be  seen 
from  th(^  left  side  of  the  "meso-gaster  and  the  wide  opening  into  the  V)ag  from  the 
right  (tig.  ()00).  Here  the  bag  is  re})resented  as  cut  away.  An  arrow  passing  from 
right  to   left,  i.e.,  from    behind   forwards,  shows  the  direction   of  the  ])r()trusion. 


THE   GREAT  OMESTl'M 


1001 


The  dotted  line  represents  the  position  of  tlie  hag  ;  a  and  p  represent  sections  of  its 
anterior  and  posterior  walls. 

The  bag  becomes  larger  and  larger,  and  more  and  more  pendulous,  until  it  at 
last  hangs  down  over  the  transverse  colon  ayd  the  small  intestines  as  a  kind  of 
apron.  Its  orifice^  becomes  narrowed  in  time  by  the  growth  of  structures  around 
it,  and  is  known  as  the  foramen  of  Winslow. 

If  the  finger  be  introduced  into  this  foramen,  it  will  touch  the  ])Osterioi-  wall  of 
the  stomach,  and  consecjuently  the  right  (or  jx^sterior)  layer  of  the  original  meso- 


Ficj.  (>01.— GuEAT  Omentum  in  Mavuoi'Vh  peswillatuh. 


TOMACH 

TURNED  Aaice 


"-  O-  '-.,.  OMENTUM 

cur  op.cN. 


gaster.  As  both  layers  of  the  meso-gaster  enter  into  the  formation  of  this  pouch 
or  apron,  it  must  of  necessity  be  formed  of  four  layers  of  peritoneunj. 

The  place  where  the  bulging  takes  place  is  a  matter  of  importance.  Originally 
such  part  of  the  meso-gaster  is  involved  in  it  as  extends  from  the  region  of  the 
])ylorus  to  about  the  middle  of  the  fundus  of  the  stomach  (fig.  600). 

In  the  lower  mammals'  the  rudimentary  disposition  of  the  great  omentum  is 
well  seen.     Thus  in  the  two-toed  anteater  it  may  be  observed  in  its  simplest  possible 

Fig.  602. — Foemation  of  Great  Omentum  as  seen  in  Vertical  Section. 


condition.  It  here  takes  the  form  of  a  slight  bag  jirojecting  towards  the  left,  and 
formed  solely  by  that  part  of  the  primitive  meso-gast«'r  which  is  nearest  to  the 
greater  curvature  of  the  stomach.  It  extends  to  the  right  as  far  as  the  i)ylorus.  It 
is  quite  horizontal.  Its  greatest  depth  does  not  exceecl  an  inch,  and  its  orifice  is  a 
wide,  shallow^  opening  upon  the  right  side  of  the  meso-gaster. 

In  higher  mammals — as  in  some  marsu]iials — the  great  omentum  apjicars  as  a 
loose,  pendulous,  open  l)ag,  with  so  large  an  oi)ening  tiiat  it  could  not  l)e  termed  a 
foramen.      (Fig.  601  shows  the  great  omentum  in  the  kangaroo.) 


1002 


THE   ORGANS   OF  DIGESTION 


In  man  and  in  must  of  tlic  hi^trher  mammals  not  only  is  the  meso-gaster 
(m-g,  fig.  602,  A)  involved  in  the  bulging  which  forms  the  great  omentum,  but 
some  part  of  the  transverse  meso-eolon  (M-r)  l)ecomes  involved  also.  This  depends 
upon  the  close  connection  which  exists  between  the  right  end  of  the  transverse  colon 
and  the  duodenum.  It  will  be  seen  from  figs.  600  and  602,  A,  that  but  a  little 
extension  of  the  bulging  of  the  membrane  is  needed  for  the  transverse  meso-colon 
to  become  involved.     In  such  case  the  anterior  layer  of   the  great  omentum  will 


Fig.  603. — Kklatiox  of  Great  Omentum  to  Transverse  Colon, 

;     TRANS.  MESO-COLON  \ 


appear  to  come  oflP  from  the  greater  curvature  of  the  stomach,  while  the  posterior 
layer  will  return  to  the  transverse  colon  and  will  become  continuous  wdth  the 
meso-colon  (figs.  602,  C,  and  603,  A).  In  the  adult  man  this  arrangement  usually 
extends  throughout  the  greater  part  of  the  width  of  the  great  omentum.  It  is  in 
all  instances  to  be  observed  in  all  that  part  of  the  great  omentum  which  is  about 
and  to  the  right  of  the  middle  line.  In  the  foetus  (as  in  the  lower  primates)  the 
posterior  layer  of  that  part  of  the  great  omentum  Avhich  is  quite  to  the  left  of  the 

Fig.  604. — Transverse  Section  of  the  Abdomen  at  the  Level  of  the  Foramen 

OF  WiNSLOW. 


middle  line  is  clear  of  the  transverse  meso-colon.  and  is  oln'ioush- derived  from  the 
meso-gaster  solely  (figs.  602,  B,  and  603,  B). 

This  difference  between  the  right  and  the  left  extremities  of  the  transverse 
meso-colon  and  omentum  can  sometimes  be  made  out  in  the  adult  man. 

The  term  'the  lesser  cavity  of  the  peritoneum'  is  ajjplied  to  the  cavity  formed 
by  this  protrusion  of  the  peritoneum.  The  term  is  of  use  for  descriptive 
purposes,  but  it  is  apt  to  be  misleading  if  it  favors  the  impression  that  the  general 
sac  of  the  peritoneum  is  divided  into  two  perfectly  distinct  parts. 


THE  DVODEXAL    FOLD 


1003 


If  the  diagram  (fig.  562),  wliieh  shows  a  transverse  section  of  the  abdomen  at 
the  level  of  the  foramen  of  Winslow,  be  examined,  it  will  be  seen  that  the  posterior 
layer  of  the  gastro-heijatie  omentum,  the  covering  of  the  posterior  wall  of  the 
stomach,  the  right  layer  of  the  gastro-sijlcnic  omentum,  and  the  })eritf)n('um  over 
the  pancreas,  are  all  derived  from  this  so-called  lesser  sac  of  the  peritoneum.  If 
one  could  imagine  the  stomach  to  be  once  more  brought  back  to  its  original  median 
position,  some  such  a]>pearance  as  is  shown  in  fig.  (j()4  would  be  presented. 

Fig.  (J05.— Intestine  of  MACRons  pesk-illatl-s. 

COLON 


From  this  it  will  be  seen  that  the  gastro-splenic  omentum,  the  coverings  of  the 
stomach,  and  the  gastro-hepatic  omentum  are  all  derived  from  the  original  meso- 
gaster,  the  posterior  attachment  of  which  has  been  shifted  considerably  to  the  left. 
The  left  margin  of  the  foramen  of  Winslow  will  then  be  seen  to  be  the  free  anterior 
or  ventral  margin  of  this  sim])le  ])vimitive  fold. 

The  gastro-splenic   omentum. — The   spleen    develops    in    the    meso-gaster 

Fig.  606.— Duodenal  Fold  of  Macropus  penicillatus. 


j^osterior  to  the  stomach,  and  the  gastro-splenic  omentum  is  V>ut  a  little  altered  jiart 
of  the  original  membrane. 

This  relation  of  the  spleen  to  the  meso-gaster  is  very  admirably  demonstrated 
in  some  animals  (figs.  oOS,  594,  595,  and  001). 

The  duodenal  fold  is  to  be  seen  in  the  bodies  of  nearly  all  mammals  below 
man.  excluding  those  somewhat  lower  species  in  which  the  intestinal  tube  remains 
still  as  a  median  loop  (pages  993,  994). 


1004  THE  ORGANS   OF  DIGESTION 

If  figs.  593,  597,  and  598  be  exanuned,  it  Avill  l)r  understood  that  when  the 
rotation  of  the  intestine  takes  plaee  and  tlie  eolon  rises  uj)  and  crosses  in  front  of  the 
duodenum,  the  peritoneum  between  the  nieso-duo(Unium  and  meso-colon  must  be 
folded  upon  itself.  The  folding  is  V-shaped,  the  ai)ex  of  the  V  l^eing  placed  below, 
and  the  plication  being  in  or  about  the  median  line.  The  two  membranes  on  a 
transverse  section  would  have  the  relation  to  one  another  shown  in  fig.  598,  C. 

The  third  part  of  the  duodenum  is  brought  closer  to  the  posterior  parietes;  the 
peritoneum  in  connection  with  it  is  curtailed;  and  the  relations  of  the  structures 
around  are  readjusted.  As  a  result  of  these  changes,  which  can  be  followed  in 
many  of  the  lower  mammals,  a  distinct  fold  is  produced  which  is  connected 
Svith  the  third  and  terminal  parts  of  the  duodenum,  and  is  often  of  considerable 
size.  This  fold  can  be  well  studied  in  jMnrropus.  It  appears  to  come  off  from 
tliat  margin  of  the  bowel  which  is  immediately  opposite  to  the  attachment  of  the 
meso-duodenum  (figs.  605,  606).  It  ends  below  in  a  free  edge,  and  posteriorly  it 
either  joins  the  peritoneum  on  the  posterior  parietes  close  to  the  origin  of  the 
descending  meso-colon,  or  it  joins  the  meso-colon  at  some  little  distance  from  the 
spine. 

The  traction  about  this  somewhat  firmly  held  segment  of  bowel  has  been  such 
that  it  has  been  drawn  between  the  layers  of  its  own  meso-duodenum.  It  is 
by  this  fold  that  is  ft)rmed  the  wall  of  the  fossa  duodeno-jejunalis  (page  966, 
fig.  572). 


SECTION  IX 


THE  URINARY  AND  REPRODUCTIVE  ORGANS 


By  WILLIAM  ANDEKSUN,  IMl.C.S. 


SURGEON   TO   AND   LKCTl'RER   ON    ANATOMY   AT  ST.    THOMAS'S   HOSPITAL;   PROFESSOR  OF   ANATOMY    IN   THE   ROYAL 

academy;    EXAMINER   IN   SURGERY  AT  THE   UNIVERSITY   OF   LONDON    AND 

ROYAL  COLLEGE  OF  SURGEONS  OF   ENGLAND 


THE  KIDNEYS 

THE  fundamental  elements  of    the  urinary   a^jparatus  are  the  kidneys — two 
glandular  organs  situated  in  the  loins  behind  the  peritoneum,  each  of  which 
is  provided  with  a  duct — the  ureter — for  the  passage  of  the  secretion  to  a 
reservoir — the   bladder — l)y   wliich    it   is    periodically   expelled   from   the   body 
throuirh  a  tube  of  outlet — the  urethra. 


Fig.  607. — PoSTEKo-iXTKRXAL  Aspect  of  the  Left  Kidney. 


Branches  of  the  renal  artery 

Renal  rein   {a   lower  brunch   it  seen 
below  the  duct) 


DUCT,  showing  sui)eriiir  ami  iiilVrMr 
pelves  with  cinnniipn  jiclvis  ami 
coniiueiiceuieut  of  ureter  proper 


Physical  characters. — The  kidney  in  its  typical  form  is  bean-shaped.  It  is 
elongated  from  alxjvc  downwards,  compressed  between  its  ]iarictal  antl  abdominal 
surfaces,  and  presents  at  its  anterior  and  internal  aspect  a  cleft,  tlie  hilum,  leading 
to.  a  cavity,  called  the  sinus,  in  which  lie  the  renal  vessels,  nerves,  and  duct.  The 
gland  in  the  male  avenigts  about  four  and  three-cjuarter  inches  (  12  cm.)  in  length, 
an  inch  and  an  eighth  in  thickness,  and  weighs  about  live  ounces.  The  dimen- 
sions of  the  female  kidnev  differ  little   from   those  of  the  male,  but  its  weight   is 

1005 


1006 


THE    URIXARY   ORGANS 


from  one-seventh  to  one-fifth  less.  In  tlie  eliild  tlie  orojan  is  relatively  large,  hut 
its  i)ernuinent  relation  to  the  hody-weight  is  usually  attained  at  the  end  of  tlie 
tenth  year  of  life. 

It  "offers  for  il(scrii)tion  two  surfaces,  two  extremities,  and  two  horders.  Tlie 
anterior  or  visceral  surface  is  convex,  and  looks  obliquely  forwards  and  out- 
wards; the  posterior  or  parietal  surface,  less  eonvix  than  the  anterior,  looks 
inwards  and  backwards;  the  rountled  upper  extremity  is  usually  somewhat 
larger  than  the  lower,  and  is  placed  about  half  an  inch  nearer  to  the  median 
sagittal  i»lane  of  the  body.  The  external  border  is  narrow  and  convex.  The 
internal  border  (or  surface),  looking  forwards,  inwards,  and  slightly  downw'ards, 
is  relatively  broad,  and  is  fissured  vertically  in  the  middle  third  of  its  length  by 
the  hilum. 

The  hilum  is  a  slit-like  aperture  bounded  in  front  and  behind  by  two  rounded 
lips  of  variable  and  unequal  thickness.  The  posterior  lip  is  nearer  to  the  middle 
line  than  the  anterior,  and  lietween  the  tw^o  pass  the  renal  vessels  and  nerves,  the 
duct,  and  a  quantity  of  fat-bearing  connective  tissue.  The  sinus  (fig.  609), 
occupied  by  the  structures  just  named,  is  narrowest  near  its  entrance,  and  about 


FiCx.    G08.  — DiAGEAM   SHOWING   RELATION   OF   KlDXEY   TO   CAPSULE.       (W.  A.) 


TRANSVERSE  COLON 


DESCENDING  COLON 

PERITONEUM 

FATTY  CAPSULE 


PERITONEAL  CAVITY 


Diaphragmatic 
fascia 


Parietal  muscle  ' 

SUBPERITONEAL  TISSUE         FATTY  CAPSULE        lienal  lesucls  embedded  in  subperitoneal  tissue 


CUT  EDGE  OF 
PERITONEUM 

Muscular  fibre  in 
subperitoneal 
tissue 

PANCREAS 


Sup.  tnesentefic  vein 
DUODENUM 
Vena  cava 
LYMPHATIC  GLAND 


LUMBAR  VERTEBRA 


an  inch  (25  mm.)  in  depth.  Its  fundus  is  pierced  by  the  renal  vessels  and  nerves, 
and  l)y  the  uriniferous  tubules;  and  gives  attachment  to  the  primary  branches 
(calices)  of  the  duct. 

Investment  and  fixation. — The  entire  organ  is  enveloped  and  supported  by  a 
kind  of  capsule  of  fat-bearing  connective  tissue  derived  from  the  parietal  layer  of 
the  subperitoneal  fascia  (tig.  608).  The  adipose  element  is  usually  small  at  birth, 
but  tends  to  increase  about  puberty  and  during  adult  life.  ^Mien  it  is  scanty,  the 
sub))eritoneal  investment  often  appears  as  a  transparent  fascial  })lane,  which  in 
renal  operations  may  be  mistaken  for  peritoneum  or  fascia  transversalis;  or  if  the 
fat  be  excessively  developed  over  the  posterior  asi)ect  of  the  organ,  it  may  form  a 
kind  of  hernial  protrusion  into  the  parietal  incision.  Should  the  sustentacular 
power  of  the  fatty  cajisule  become  impaired  by  atrophy  from  wasting  disease,  by 
the  pressure  of  a  pregnant  uterus  or  tight  stays,  or  from  any  other  cause,  the 
phenomenon  of  movable  or  wandering  kidney  may  be  set  up  by  slight  external 
violence,  the  organ  tending  to  shift  its  place  as  far  as  the  attachment  of  its  vessels 
to  the  main  trunk  will  ])ermit. 

Position  and  relations. — The  kidney  is  commonlv  said  to  lie  in  the  lumbar 


TIIK   KIDXFA'S 


1007 


region.  It  is,  however,  intersected  liy  the  liorizontal  and  verticcal  planes  \Yhich 
separate  the  hypochondriac,  huiil):ir.  epigastric,  and  mnbilical  regions  from  eacli 
other,    and    hence   belongs   to    all    tiiese  segments  of    the   abdominal  space.     Its 


Fig.  609.— Section  of  Kidney  showing  the  Sints.     (After  Heule.) 

CORTEX  PROPER   ^-r-rjCT 


/     \ 


Vessels 

BOTTOM  OF  SINUS 

ATTACHMENT  OF  CALYX 

APEX  OF  PAPILLA  WITH 
ORIFICES  OF  URINIFER- 
OUS  TUBULES 


MARGIN  OF  HILUM 


BOTTOM  OF  SINUS 


-    TWO  PAPILL/E  SURROUNDED  BY  A 
SINGLE  CALYX 


Fig.  610.— Diagram  of  Relations  of  Posterior  Surface  of  I^v.yt  Kidney. 


Outer  border  of  quadratus 
lumboruiu 


)  LOWER  BORDERS  OF  ELEVENTH 
/  AND  TWELFTH  RIBS 


AREA  OF  PLEURAL  CONTACT  OPPOSITE 
■HIATUS  DIAPHRAGMATICUS  ' 

Ligamentum  arcuatum 
internum 


Ligamentum  arcuatum 
externum 


vertical  level  may  be  said  to  correspond  to  tlie  last  thoracic  and  two  ujtper  lumbar 
vertebra',  the  right  lying  in  most  cases  from  a  tliinl  to  half  an  incli  lower  than  tin- 
left,  but  excfptioiis  to  tliis  rule  are  not  unfrecpu'ut. 

The  posterior  surface   (ligs.  GIO,  (HI),  with  the  corresponding  portion  of  the 


1008 


THE    URINARY  ORGANS 


fatty  capsule,  rests  against  the  posterior  alxloniinal  wall,  extending  upwards  in 
front  of  the  eleventh  and  twelfth  ribs  and  inwards  to  overlap  the  tips  of  the 
transverse  processes  of  the  first  and  second  lumbar  vertebrae;  the  left  kidney 
usually  reaching  as  hiirh  as  the  upjier  l)ordcr  of  the  eleventh  ril),  the  right  only  to 
its  lower  loonier.  The  only  visceral  relation  i>osteriorly  is  on  the  left  side,  where  the 
spleen  slightly  overlaps  the  kidney  opposite  the  upper  half  of  its  outer  border.  The 
parietal  relations  on  both  sides  areas  follows:  (1)  the  diaphragm,  and  if  a  well- 
marked  hiatus  diaphragmaticus  exist  above  the  ligamentum  arcuatum  externum,  the 
kidney  may  come  into  relation  with  the  subplenral  tissue  and  pleura;  at  this  point 
the  ciiest  may  become  invaded  by  a  circumrenal  abscess,  or  an  empyema  may 


Fig.  611. — The  Abdominal  Viscera,  seen  from  behind. 

(From  the  model  of  His.) 

The  kidneys  are  .somewhat  lower  than  usual  in  their  relations  to  the  ribs. 


^' 

^^-    "^, 

LOBUS  SPIGELII  OF 
LIVER 

^ 

^^^ 

Aorta 

i 

OUTLINE  OF  LAST  RIB 

1 

SPLEEN 

-? 

LEFT  KIDNEY,  WITH 
SUPRARENAL  BODY 

COLON 

PERITONEUM 

OUTLINE  OF  ILIAC 
CREST 



''/ " 

FIRST  PORTION  OF 
RECTUM 


SIGMOID  FLEXURE 


SECOND  PORTION  OF 
RECTUM 


LUNG 
SUPRARENAL  BODY 

OUTLINE  OF  LAST  RIB 
Vena  cava 


RIGHT  KIDNEY  WITH 
URETER  INTERNALLY 


SMALL  INTESTINE 


OUTLINE    OF  ILIAC 

CREST 
COLON 


PARIETAL  PERITONEUM 
WITH  COLIC  VESSELS 


SMAU  INTESTINE 


-  BLADDER 
AMPULLA  OF  RECTUM 


find  its  way  from  the  ]>leura  into  the  subperitoneal  tissue  behind  the  kidne}';  (2) 
the  anterior  lamella  of  the  posterior  aponeurosis  of  the  transversalis  fse])arating 
the  organ  from  the  (juadratus  luniborum;  (3)  the  psoas;  (4)  the  three  fasciie — 
diaphragmatic,  transversalis,  and  iliac — which  line  these  muscles  respectivel}';  and 
(5)  the  last  thoracic,  the  ilio-hypogastric,  and  the  ilio-inguinal  nerves,  and  the 
ant(!rior  divisions  of  the  first  and  second  luml)ar  vessels,  all  runnuig  obliquely 
downwards  and  outwards  in  front  of  the  quadratus  lumborum  to  })ierce  the 
transversalis  beyond  the  outer  border  of  the  quadratus.  Owing  to  the  higher  level 
of  the  left  kidney,  its  diaphragmatic  area  of  contact  is  larger  than  that  of  the  right 
organ.     This   area,  moreover,   mav  l)e   increased  on  eitlicr  side  when  the  arcuate 


THE  KIDNEYS 


1009 


ligaments,  which  give  origin  to  a  large  portion  of  the  posterior  fibres,  are  attached 
to  the  tip  of  the  transverse  process  of  tlie  second  lumbar  vertebra  instead  of  that 
of  the  first. 

Tlie  pleura  has  an  indirect  but  important  relation  to  the  kidney  besides  the  more 
direct  relation  at  the  '  hiatus  diaphragmaticus '  referred  to  above.  The  inferior 
limit  of  the  pleural  sac  extends  almost  horizontally  outwards  from  the  lower  lK)rder 
of  the  twelfth  thoracic  vertebra,  crossing  the  last  lib  near  its  neck,  and  the  eleventh 
rib  about  two  inches  farther  outwards.  As  a  rule,  the  incision  in  renal  oi)erations 
may  be  carried  safely  to  the  lower  lK)rder  of  the  last  rib;  l>ut,  should  this  boiK;  l)e 
absent  or  very  short,  the  eleventh  ril)  may  be  mistaken  for  it,  and  the  serous  mem- 
brane would  then  be  in  danger.  It  is  probalile,  too,  that  the  pleura  reaches  to  a 
lower  point  in  tliose  cases  where  the  arcuate  ligaments  are  attached  to  the  second 
lumbar  transverse  process.  The  presence  of  a  thirteenth  rib  would  involve  a  con- 
traction of  the  space  available  for  the  surgical  exploration  of  the  organ. 

The  upper  extremity  of  each  kidney  is  crowned  by  the  suprarenal  body  (figs 
611,  612),  which  encroaches  also  upon  its  anterior  surface  and  inner  border,  and 
is  fixed  to  it  by  connective  tissue  derived  from  the  subperitoneal  fascia. 

The  anterior  or  visceral   surface  (fig.  612)  is  moulded  to  the   contiguous 


Fig.  612. — Diagram  showing  Axtekior  Kelatkjxs  of  Kidneys  and  Suprarenal  Bodies. 


DUODENAL  AREA  HEPATIC  AREA  GASTRIC  AREA 

(NON-PERITONEAL)       (NON-PERITONEAL)       CAVAL  AREA       (PERITONEAL) 


DUODENAL  AREA 
(NON-PERITONEALl 


COLIC  AREA 
(NON-PERITONEAL 


PERITONEAL  AREA  WITH  RIGHT 
COLIC  VESSELS 


PERITONEAL  AREA  WITH  LEFT 
COLIC  VESSELS 


PANCREATIC   AREA 
(NON-PERITONEAL) 


COLIC  AREA  OF 
SPLEEN 


COLIC  AREA 
(NON-PERITONEAL) 


organs.  The  right  kidney  is  in  contact  in  about  its  ui)i)er  half  with  the  renal 
impression  on  the  liver  (page  978),  and  below  with  the  ascending  colon  and 
duodenum;  the  hepatic  area  being  covered  with  peritoneum,  while  the  second  stage 
of  the  duodenum  and  more  externally  the  ascending  colon  are  directlv  attached  to 
the  surface  ])y  subperitoneal  tissue;  but  the  two  non-peritoneal  areas"  vary  consid- 
erably in  their  relative  ])roi»ortions,  not  only  in  different  sul)jects.  but  in  the  same 
subject  under  different  con<litions  of  distension  of  the  duod(^num  and  the  colon. 
The  second  stage  of  the  duodcnmn  is  also  more  or  less  in  relation  with  the  right 
renal  vessels. 

The  left  kidney  lies  behind  the  stomach,  the  pancreas,  the  s]ilenic  vessels,  the 
descending  colon,  and  the  colic  vessels.  Its  anterior  surface  may  lie  divided  into 
three  portions:  an  upper  or  gastric  area,  separated  from  the  stomach  by  the 
peritoneum  of  the  lesser  sac;  a  middle  or  pancreatic  area,  attached  to  the  pan- 
creas by  suliperitoneal  connective  tissue,  and  crossed  also  by  the  sjdenic  vein 
behind  the  upper  border  of  the  pancreas,  and  by  the  splenic  artery,  which  runs  in 
a  ser])entine  course  immediately  above  the  vein;  and  an  inferior  or  colic  area, 
the  outer  portion  of  which  is  covered  by  the  splenic  flexure  and  up))er  ])art  of  the 
descending  colon;  the  inner  by  a  layer  of  peritoneum  (of  the  greater  sac)  and  the 
colic  vessels. 
64 


1010  THE   URIXARY  ORGAXS 

The  cuter  border  of  the  kidney  reaches  u  jioint  about  three  and  a  half  or  four 
inches  external  to  the  lumbar  spinous  processes.  On  the  right  side,  it  is  in  contact 
with  the  liver  in  its  upjier  lialf  or  two-thirds;  on  the  left,  its  upper  third  or  half 
rests  against  the  renal  groove  in  the  posterior  portion  of  the  visceral  surface  of  the 
spleen. 

The  inner  border  of  the  right  kidnw  apjtroaches  very  close  to  the  vena  cava, 
especially  above;  that  of  the  left  is  divided  from  the  aorta  by  an  interval  of  an  incli 
or  more. 

The  position  of  the  kidne3'S  at  the  l)ack  of  the  al)dominal  cavity  involves  a  cer- 
tain amount  of  pressure  upon  the  organs  and  their  vessels  and  nerves  by  the  weight 
of  the  viscera  in  front  Avhen  the  body  is  supine,  and  there  is  reason, to  believe  that 
their  secretory  functions  are  consequently  influenced  by  changes  of  posture  to  an 
extent  that  may  be  utilised  in  therapeutics. 

The  structures  lying  within  the  sinus  are  the  renal  artery  and  vein,  the  renal 
lym|)haties  (ves.'^els  and  glands  ),  a  plexus  C)f  nerves,  the  duct,  and  more  or  less  con- 
nective and  adipose  tissue  continuous  with  the  fatty  capsule.  The  renal  artery  is 
a  branch  of  the  aorta  given  off  opposite  the  first  lumbar  vertebra  and  behind  the 
pancreas.  On  reaching  the  hilum  it  usually  breaks  up  into  four  branches,  three  of 
which  pass  in  front  of  the  pelvis  to  supply  the  superior,  middle,  and  inferior  zones 
of  the  organ,  while  a  fourth  runs  behind  the  pelvis  close  to  the  posterior  lip  of  the 
hilum  and  is  distributed  over  the  lower  half  or  two-thirds.  This  may  be  wounded 
in  an  attempt  to  remove  a  calculus  b}^  incision  of  the  posterior  wall  of  the  pelvis. 
Besides  these,  irregular  vessels  may  lAerce  the  gland  above  or  below  the  hilum 
(fig.  607).  The  left  renal  vein  receives  the  spermatic  or  utero-ovarian  vein,  and  is 
usually  somewhat  lower  than  the  right.  The  shortness  of  the  right  renal  rein  should 
be  remembered  in  the  operation  of  nephrectomy. 

Structure. — The  kidney  Avhen  removed  from  its  fatty  investment  is  seen  as  a 
yellowish-red  organ  covered  b}^  a  thin  but  strong  fibrous  capsule  (tunica  propria), 
which  is  prolonged  through  the  hilum  into  the  sinus,  where  it  becomes  continuous 
with  the  sheaths  of  the  renal  vessels,  and  extends  as  far  as  the  attachments  of  the 
suljdivisions  of  the  duct  around  the  renal  papillse.  The  whole  capsule  may  be  easily 
peeled  off  from  the  healthy  kidney,  except  at  the  bottom  of  the  sinus,  where  it  is 
fixed  1)y  the  vessels  and  duct;  and  as  the  capsular  vessels  are  of  small  size,  the 
process  of  stripping  is  attended  with  little  hsemorrhage  when  practised  in  the  coui'se 
of  operations  upon  the  living  suljject. 

On  section  through  the  kidney,  its  substance  is  found  to  comprise  an  external 
or  cortical  and  an  inner  or  medullary  segment.  The  medulla  consists  of  a  variable 
numl)er  (eight  to  eighteen)  of  conical  segments  called  pyramids  of  Malpighi,  the 
apices  of  which  project  into  the  bottom  of  the  sinus  (fig.  609)  and  are  surrounded 
by  the  primary  segments  (calices)  of  the  duct,  while  their  l:)ases  are  turned  towards 
the  surface,  but  are  separated  from  it  and  from  each  other  by  the  cortex.  The 
pyramids  average  in  their  axial  diameter  about  three-quarters  of  an  inch,  and  have 
a  width  at  the  liase  of  about  two-thirds  of  an  inch  (16  mm.).  They  are  smooth 
and  somewhat  glistening  in  section,  and  marked  with  delicate  strife  which  converge 
from  base  to  apex,  and  indicate  the  course  of  the  uriniferous  tubules.  The  blunted 
apex,  or  papilla,  single  or  blended  with  one  or  even  two  of  its  fellows,  is  embraced 
by  a  calyx,  and  if  examined  with  a  hand  lens  will  be  seen  to  present  a  varial)le 
number  (twelve  to  eighty)  of  minute  apertures,  the  foramina  papillaria,  through 
which  the  secretion  escapes  into  the  duct. 

The  cortex  may  be  divided  into  two  portions:  a  peripheral  layer,  the  cortex 
proper,  whieh  is  a  little  less  than  half  an  inch  (12  mm.)  in  thickness,  and  extends 
from  the  cajjside  to  the  leases  of  the  ])yramids  of  Malpighi;  and  processes  called 
columns  of  Bertin,  which  dip  inwards  between  the  Malpighian  pyramids  to  reach 
the  bottom  of  the  sinus,  where  they  are  covered  by  the  fil)rous  capsule  and  more  or 
less  adipose  tissue  {[\^.  613).  In  section  the  cortex  is  somewhat  granular  in  aspect, 
and  in  an  injected  kidney  is  seen  to  be  dotted  with  minute  points  corresi)onding  to 
vascular  glomeruli  lying  within  the  cajcal  origin  of  the  uriniferous  tubules  (capsules 
of  BoAvman).  Examined  more  closely,  it  displays  a  number  of  small  pyramidal 
groups  of  tubules,  some  l:)elonging  to  the  cortex  proper,  with  their  bases  resting  uj^on 
the  bases  of  the  Malpighian  pyramids,  the  apices  directed  towards,  but  not  reaching, 


THE  KIDXEYS 


1011 


the  periphery;  others  forming  a  part  of  the  colunins  of  Berlin,  and  flisposed  almost 
at  ri<rht  an<:l('s  to  the  last.  These  cortical  groups  arc  called  pyramids  of  Ferrein, 
in  contradistinction  to  the  mnch  larger  nicdullarv  pyramids  of  ,Mali)ii:lii. 

The  kidney  of  a  foetns  differs  from  that  of  the  adult  in  the  lo])ular  suljdivision  of 
its  surface,  each  lobule  corresponding  to  the  l)ase  of  a  pyramid  of  Malpighi  ca[>ped 
by  a  thin  layer  of  cortex.  Such  a  condition  is  permanent  in  some  of  the  lower 
animals;  but  in  man  the  superficial  indications  of  morphological  segmentation 
usually  become  obliterated  during  the  progress  of  growth  of  the  cortical  tissue,  and 
are  s<'l(loin  visiltle  after  the  age  of  ten. 

Urinifercus  tubes  (tig.  (U4). — The  secreting  tubules  commence  ])y  a  number 
of  spherical  capsules  (capsules  of  Bowman),  Avbich  lie'in  the  cortex.  From  each 
capsule  ])nsses  a  tul)e  witli  a  narrow  iieek,  which  l)ecomes  wide  and  convoluted, 
then,  nai-i-o\ving  again,  runs  down  into  the  suljjacent  ]\Iali)ighian  pyramid,  forms 
a  loop  (looped  tube  of  Henle),  returns  into  the  cortex,  where  it  again  becomes 
dilated  and  contorted,  and,  after  undergoing  a  final  constriction,  opens  into  a 
straight  collecting  tube,  the  axial  element  of  a  pyramid  of  Ferrein.  The  collect- 
ing tubes  run  into  the  Malpighian  pyramids,  and  unite  with  each  other  to  form  a 

Fig.  (JIj. — JIuHizuxTAL  .Section  of  Kidney,  showing  the  Sincs. 


COLUMN 

PYRAMID 

Cortico- 

OF 

OF 

medullary 

BERTIN 

MALPIGHI 

artery 

CORTEX  WITH  PYRAMIDS 
OF  FERREIN 


Branch    OUCT    Portion    Irregular 

0/  of  fatty       branch 

artery  capsule      of  artery 


smaller  number  of  larger  tubes,  which  terminate  l)v  opening  on  to  the  papillary 
ajjcx  of  the  pyramid,  and  into  the  corresi)onding  calyx  of  the  duct.  The  tul>es  arc 
lined  with  epithelium  throughout,  the  cells  being  tesselated  in  the  capsule,  irregu- 
larly cubical  in  the  convoluted  tubes,  flattened  on  the  loops  of  Henle,  and  columnar 
in  the  cortical  collecting  tubes  and  in  the  straight  tubes  of  the  medulla. 

Vessels  (fig.  (514). — The  kidney  is  very  vascular.  The  larger  arterial  liranehes. 
if  traced  in  section  from  the  point  at  which  they  ])ierce  the  bottom  of  the  sinus,  will 
l)e  found  to  run  u]i  between  tlie  jtyramids  of  Mal)»ighi  to  subdivide  at  their  bases 
into  cortico-medullary  arches  wbieli  lie  between  the  cortex  and  medulla,  giving 
off  arterioles  in  both  directions,  the  cortical  branches  sup] living  afferent  twigs  to 
the  glomeruli  within  the  capsules  of  Bowman;  the  medullary  branches  running 
inwards  to  form  ph-xuses  around  the  straight  and  looj)ed  tut»ules  of  the  Malpighian 
pyramids.  The  efferent  vessels  of  the  Malpighian  glomeruli  form  a  capillary 
l)iexus  around  the  uriniferous  tubules  and  tt'rminate  in  the  renal  veins.  The  sur- 
face of  the  kidney  receives  small  collateral  arteries  whicli  pass  through  the  fatty 
capsule  from  the  su]irarenal.  spermatic,  and  lumliar  v(\ssels.  The  su])erficial  veins 
appear  in  the  form  of  little  stellate  groups  (stars  of  Verheyen  »,  which  eonnnuni- 


1012 


THE    URIXARY   ORG  ASS 


cate  with  the  vt'iious  plexus  in  the  adipose  capsule  and  l)y  means  of  this  with  the 
visceral  and  parietal  veins  in  the  neighbourhood.  They  are  very  distinct  Avhen  the 
orsan  is  congested.  The  renal  lymphatics  may  be  divided  into  two  sets,  capsular 
and  parenchymatous.  Thev  terniinate  in  a  series  of  glands  lying  with  the  renal 
vessels  in  the  subperitoneal  tissue,  and  their  contents  are  ultimately  conveyed  into 
the  receptaculum  chvli. 

Nerves.— The  nerves  form  a  plexus  accompanying  the  vessels,  and  arc  derived 


Fig.  614.— Scheme  of  Tubules  axd  Vessels  of  the  Kidney. 


TUNICA  PROPRIA  .-t= 
Cortical  vein 


Glomenthis  and 
capsule  of  Bowman 


CORTEX  -J 


Cortical  vein 

Cortieo-medullary  f_ 

artery 

Medullary  artery 


Efferent  vessel  form- 
ing medullary  plexus 


MEDULLA  -V 


Papillary  plexus 
surrounding  lite 
foramina  papil- 
laria 


PRIMARY  CONVOLUTED 
TUBE 


CAPSULE  OF  BOWMAN 


SECONDARY   CONVOLUTED 
TUBE 


LOOPED  TUBE  OF 
HENLE 


ULTIMATE  TUBE  OPENING 
ON  TO  THE  FORAMEN 
PAPILLARE 


mainly  from  the  sympathetic  through  the  solar  and  aortic  plexuses,  and  the  splaneh- 
nics.  They  communicate  with  the  spermatie  i)lexuses.  8onie  filaments  have  also 
been  traced  from  the  pneumogastrics. 

Varieties. — The  principal  variations  of  the  kidney  arc  as  follows: — 

1.  In  Jo  nil. — Disproportionate  increase  of  one  or  other  diameter,  producing  the 
long,  globular,  triangular,  and  discoid  types. 

2.  la  size. — Ine(|uality;  one  being  small,  the  other  compensatingly  large. 

3.  Ill  number. — The  organ  may  be  single,  then  usually  occupying  its  ordinary 


THE  SUPRAREXAL   BODIES 


1013 


position  in  one  or  other  loin;  or,  still  more  rarely,  it  may  l)e  triple,  in  whieli  case 
the  additional  gland  is  either  lateral  or  median. 

4.  In  position. — One  or  both  kidneys  may  be  above  or  below  the  normal  level, 
in  the  latter  and  far  more  fretjiK'nt  case  encroaching  upon  the  iliac  iossa,  or  even 
entering  the  true  jjclvis  in  front  of  or  behind  the  rectum;  or  the  displacement  may 
lie  horizontal,  the  organ  lying  ui)on  the  vertebral  colunm  ov  even  in  the  oi)i»osite  loin. 

5.  By  fusion  of  the  two  kidneys;  the  union  involving  the  lower  extremities 
only  ('  horseshoe  ki<lney  '),  or  the  whole  length  of  their  iimer  borders. 

6.  In  mobiliti/. — Undue  mobility  is  usually,  if  not  always,  due  to  a  laxity  of 
that  portion  of  the  subperitoneal  tissue  Avhich  constitutes  the  fatty  capsule;  but  a 
peritoneal  meso-nephron  is  said  to  have  been  seen  in  extremely  rare  cases  of 
movable  kidney 

THE    SUPRARENAL    BODIES 

These  structures  do  not  form  any  i)art  of  the  genito-urinary  a])paratus.  but  it 
is  convenient  to  describe  them  in  association  with  the  glands  l;y  which  they  are 
supported. 

The  suprarenal  bodies  (fig.  615)  are  two  solid  viscera  resting  each  upon  the 
upper  extremity  of  the  corresi)onding  kidney  and  the  adjoining  ]xirts  of  its  inner 
and  anterior  surfaces,  and  bound  to  it  by  subperitoneal  connective  tissue.  They 
lie  against  the  diaphragm  opposite  the  eleventh  rib,  or  tenth  intercostal  space,  and 
are  separated  from  each  other  l)y  a  space  of  about  two  inches  and  a  half.  The  left 
is  usually  a  little  higher  than  the  right,  owing  to  the  greater  elevation  of  its  kidney. 


Fig.  G15. — I)ia(;kam  sirowixo  Antekior  Rei.atioxs  of  Kidxkys  axd  Slpraeexal  lioDiES. 


DUODENAL  AREA 
(NON-PERITONEAL) 


HEPATIC  AREA 
(NON-PERITONEAL) 


GASTRIC  AREA 
(PERITONEALl 


DUODENAL  AREA 
(NON-PERITONEAL) 


COLIC  AREA 
(NON-PERITONEAL) 


PERITONEAL  AREA  WITH  RIGHT 
COLIC  VESSELS 


PERITONEAL  AREA  WITH  LEFT 
COLIC  VESSELS 


PANCREATIC  AREA 
(NON-PERITONEAL) 


COLIC  AREA  OF 
SPLEEN 


COLIC  AREA 
(NON-PERITONEAL) 


The  organ  varies  widely  in  dimensions  within  ])hysiol(jgical  limits.  Its  average 
weight  is  about  a  drachm,  its  height  an  inch  and  a  quarter  (3  cm.),  and  its  greatest 
breadth  at  the  ba.se  an  inch  and  throe-cpiarters  (4.5  cm.). 

The  /-/(/A^  suprarenal  body  is  pyramidal  in  form  with  the  apex  directed  upwards 
and  somewhat  inwards.  Its  anterior  surface  is  related  above  to  a  special 
im]»ression  upon  the  under  and  back  ))art  of  the  right  lobe  of  the  liver,  between  the 
layers  of  the  coronary  ligament;  internally  to  the  inferior  vena  cava  whicli  slightly 
overla])s  it  (Rolleston);  and  below  is  covenxl  with  peritoneum  continuous  with 
that  of  tlie  kidney,  except  at  its  internal  inferior  angle  whore  it  is  cro.^sed  by  the 
hepatic  flexure  of  the  duodenum.  It  is  rather  firmly  adherent  to  the  liver,  and  the 
vessels  of  the  two  organs  anastomose  with  each  other  at  tliis  point. 

The  left  suprarenal  body  is  a  little  larger  than  its  fellow,  somewhat  cresei-ntic 
in  shape,  and  encroaches  less  upon  the  .summit  of  the  kidney  than  the  riglit.  and 
more  upon  the  inner  border,  reaching  even  to  the  hilum.      Its  anterior  surface  is 


1014  THE   URIXARY  ORGAXS 

covered  above  by  the  peritoneum  of  the  lesser  sac,  ^Yhich  sei)arates  it  from  the 
stomach;  and  below,  near  its  internal  inferior  angle,  it  is  crossed  by  the  ui)i)er 
border  of  the  pancreas  and  the  splenic  artery.  Externally  it  is  in  contact  Avith 
the  upper  extremity  of  the  spleen,  which  passes  a  little  beliind  it,  and  its  inner 
border  is  separated  from  its  aorta  by  the  fibres  of  the  diaphragm. 

Accessory  suprarenal  bodies  are  often  present  in  the  neighbourhood  of  the 
principal  organs. 

Structure. — On  section  the  organ  is  found  to  V)e  covered  by  a  thin  fil;trous 
capsule  ^hich  sends  trabecular  processes  between  the  cellular  elements  of  its  proper 
substance.  The  parenchyma  consists  of  a  peripheral  portion  or  cortex,  of 
yellowish  colour,  excei^t  in  its  deepest  layer,  which  is  darkly  pigmented,  and  a 
central  portion  or  medulla,  soft  and  greyish,  and  tending  to  break 'doAvn  under 
decomposition  in  such  a  manner  as  to  give  the  appearance  of  an  irregular  cavity 
(whence  the  name  suprarenal  '  capsule'). 

Vessels  and  nerves. — It  is  richly  supplied  both  with  vessels  and  nerves.  Its 
arteries  are  derived  from  three  sources — the  aorta,  the  phrenic,  and  the  renal — 
and  pierce  the  organ  in  various  places,  but  chiefly  on  the  anterior  surface  along  a 
furrow  sometimes  called  the  hilum.  The  veins  terminate  on  the  right  side  in  the 
vena  cava,  and  sometimes  by  means  of  small  l)ranches  in  the  phrenic  and  renal 
trunks;  on  the  left,  in  the  left  renal  vein.  The  lymphatics  pass  to  the  renal 
glands,  which,  like  the  suprarenal  bodies,  themselves  contain  a  good  deal  of  pig- 
ment. The  nerves  form  a  rich  and  complex  interlacement,  and  are  derived  chiefly 
from  the  solar  and  renal  plexuses,  but  include  filaments  from  the  splanchnics.  and 
according  to  some  authors  from  the  phrenic  and  vagus  also.  It  is  disproportion- 
ately large  in  early  foetal  life,  and  has  nearly  reached  its  full  growth  at  the  time  of 
birtii. 

THE  REXAL  DUCTS 

The  excretory  duct  of  the  kidney  (figs.  607,  611,  616)  is  a  musculo-mucous 
canal,  expanded  and  in-egularly  Ijranched  a1)ove,  narrow  and  of  fairly  uniform 
dimensions  in  the  rest  of  its  course.  At  its  origin  in  the  sinus  renalis  it  a]4)ears 
in  the  form  of  a  number  of  short  tubes,  usually  eight  or  nine,  called  calices,  (^ach 
of  which  embraces  the  papillary  extremity  of  a  pyramid  of  Malpighi  two  or  three 
lines  above  its  apex,  or  occasionally  two  papillae  may  be  connected  with  a  single 
calyx.  The  calices  average  about  a  third  to  half  an  inch  (8  to  12  mm.)  in  length, 
and  open  directly  or  by  means  of  intermediate  tuljes  (infundibula)  into  two  short 
passages,  the  superior  and  inferior  pelves,  which  in  turn  coml)ine  after  a  longer 
or  shorter  course  to  form  the  common  pelvis.  The  inferior  and  larger  pelvis  has 
a  diameter  of  about  two-fiftlis  of  an  inch  (10  mm.);  the  superior  is  about  one-third 
less.     Occasionally  a  third  or  middle  pelvis  is  present. 

The  common  pelvis  varies  greatly  in  different  subjects.  It  usually  appears  as 
a  more  or  less  funnel-shaped  portion  of  the  canal,  Avider  above  (about  three-fifths 
of  an  inch — 15  mm. ),'  where  it  lies  between  the  two  lips  of  the  hilum;  narrow  below, 
Avhere  it  arches  downwards  and  inwards  to  become  continuous  with  the  relatively 
uniform  portion  of  the  duct  known  as  the  ureter  proper.  In  some  cases,  how- 
ever, it  can  scarcely  be  said  to  exist  as  a  dilatation.  I'nder  ordinary  circumstances 
it  is  flattened  from  before  backwards,  its  anterior  and  posterior  Avails  being  in  con- 
tact, and  its  chaimel  represented  by  a  fissure.  It  is  in  relation  behind  Avith  the 
posterior  lip  of  the  hilum,  from  Avhich  it  is  separated  1)v  more  or  less  adipose  tissue 
continuous  with  tlie  fatty  capsule,  and  occasionally  Ity  an  irregular  branch  of  the 
renal  artery.  The  renal  vein  and  artery  lie  in  front,  iml)edded  in  fat,  and  anterior 
to  these  structures  is  situated  the  descending  portion  of  the  duodenum  on  the  right 
side,  and  the  pancreas  on  the  left. 

The  ureter  extends  from  the  termination  of  the  pelvis  to  the  l)ladder,  running 
in  a  kind  of  lymph-space  betAveen  the  lamina  of  the  subperitoneal  tissue.  It  is  a 
tube  of  about  a  fifth  of  an  inch  (5  mm.)  in  diameter  Avhen  distended,  and  is  fairly 
uniform  in  size,  except  about  two  inches  beloAv  tlie  kidney,  Avhere  a  slight  constric- 
tion is  usually  foimd  (Bruce  Clark).  Its  length  is  variously  stated,  but  the  average 
in  the  male  adult  may  he  taken  as  aliout  tAvelve  inches  (30  cm.),  the  right  being 
usuallv  a  little  the  shcjrter.     The  excessive  estimates  sometimes  given  de^icnd  upon 


THE  RENAL  DUCTS  1015 

tlu'  untrustworthy  indications  afforded  liy  adnieusjurement  after  the  removal  of  the 
structure  from  the  l)ody. 

Course  and  relations. — The  tuhes  lie  about  three  inches  apart  at  their  com- 
mencement, but  this  distance  gradually  lessens  to  about  two  inches  as  they  descend 
towards  the  sacro-iliac  joint.  In  the  true  pelvis  they  at  first  diverge,  but  finally  on 
nearing  the  base  of  the  bladder  run  forwards  and  inwards  to  pierce  the  wall  of  the 
viscus,  and  at  their  termination  are  separated  b}'  a  distance  of  about  an  inch 
( 25  nnn.  ).  The  course  of  each  tube  may  be  conveniently  divided  into  three  stages, 
abdominal,  pelvic,  and  vesical.  The  abdominal  portion,  running  downwards  and 
slightly  inwards,  is  in  relation,  poster iorlij,  with  the  psoas  and  its  fascia,  and  tlie 
genito-crural  nerve,  and  with  the  common  iliac  artery  near  its  bifurcation.  Ante- 
riorly, it  is  covered  by  peritoneum  and  intestines,  and  is  crossed  by  the  colic  and 
spermatic  vessels.  Internally,  it  is  opposed  on  the  right  side  to  the  inferior  vena 
cava,  on  the  left  to  the  aorta;  the  vein  being  almost  in  contact  Avitli  the  right  ureter, 
while  the  artery  is  separated  from  the  left  tube  by  an  interval  that  gradually  dimin- 
ishes from  one  inch  above  to  half  an  inch  opposite  the  bifurcation  of  the  vessel. 
In  the  fciDale  tlic  utero-ovarian  veins  lie  on  its  inner  side. 

The  pelvic  portion  runs  in  front  of  the  saero-iliac  synchondrosis,  then  ui)on  the 
obturator  intcrnus  and  its  fascia  Ix'hind  and  below  the  psoas,  and  on  the  outer  side 

Fig.  G16. — Upper  Portiox  of  Duct.     (After  Heule.) 


INFUNDIBULUI/ 


SUPERIOR  PELVIS 


C3MM0N  PELVIS 


INFERIOR  PELVIS 


of  the  pelvic  coils  of  intestine  (sigmoid  colon  on  left  side,  small  intestine  on  right), 
tinally  leaving  the  pelvic  wall  to  join  the  bladder.  In  this  ])Osition,  in  the  male  it 
is  crossed  superi(jrly  and  internally  by  the  vas  deferens,  and  lies  under  cover  of  the 
free,  extremity  of  the  vesicula  seminalis,  separated  from  its  fellow  by  a  distance  of 
an  inch  and  a  half  (37  mm.).  In  the  female  it  runs  parallel  with,  and  four  to  six 
lines  (8  to  12  mm.)  from,  the  cervix  uteri,  V>ehind  the  uterine  artery,  tlirough  the 
uterine  j^lexus  oi  vt'ins,  and  Ijcneath  tlierootof  the  l)r<)ad  ligament;  tinally  crossing 
the  upper  third  of  the  vagina  to  reach  the  vesico-vaginal  interspace  and  jnerce  the 
bladder  oi)})osite  the  middle  of  the  vagina.  A  calculus  in  the  lower  end  of  the  tul)e 
might  be  detected  l)y  a  vaginal  examination. 

The  vesical  portion,  al)OUt  lialf  an  inch  (12  mm.)  in  length,  runs  obliquely 
downwards  and  inwards  througli  tlie  coats  of  the  l>ladder,  and  opens  on  to  the 
mucous  surface  at  a  distance  of  about  three-quarters  of  an  inch  to  an  inch  (18  to 
25  nmi.)  from  its  fellow,  and  from  tlie  internal  urinary  meatus. 

Structure. — The  wall  of  the  ureter  is  al)out  a  twenty-fifth  of  an  inch  (1  nnn.) 
in  thickness,  and  consists  of  a  nnicous  mem])rane.  a  muscular  coat,  and  an  external 
connective  tissue  investment.  The  mucous  membrane  is  longitudinally  plicatecl, 
and  is  lined  with  a  multiple  layer  of  transitional  i]iithelium,  continuous  with  that 


1016  THE  VRIXARY  ORGANS 

of  tlie  papillae  above,  and  with  that  of  the  bladder  below.  ^Mucous  follicles  of  sim- 
ple form  have  been  found  in  the  upper  part  of  the  canal.  The  muscularis  is  about 
one-fiftieth  of  an  inch  (.5  mm.)  in  thickness,  and  consists  of  two  layers,  an  exter- 
nal composed  of  annular  fibres,  an  internal  of  filn-es  longitudinally  disposed.  After 
the  tube  has  entered  the  bladder  the  circular  fil)res  ap})ear  as  a  kind  of  s})hincter 
around  its  vesical  orifice;  wliile  the  longitudinal  fibres  spread  out  to  foi-m  with 
those  of  the  opjiosite  side  a  triangular  expanse  witli  its  a})ex  at  the  internal  urinary 
meatus  and  its  base  corresponding  to  a  line  drawn  between  the  two  ureteric  orifices, 
the  upper  (interureteric)  and  lower  (uretero-meatal)  fil)res  forming  strong  bands 
which  bound  the  triangle 

Vessels  and  nerves. — The  arteries  of  the  ureter  come  from  the  renal,  sper- 
matic or  utero-ovarian,  internal  iliac,  and  vesical;  the  veins  terminatcin  the  corre- 
sponding trunks;  and  the  lymphatics  pass  to  the  renal,  lumbar,  and  pelvic  glands 
and  into  the  receptaculum  chyli.  The  nerves  are  supplied  by  the  spermatic, 
renal,  and  hypogastric  plexuses. 

Varieties. — The  most  important  variation  consists  in  the  partial  or  complete 
duplication  of  the  tube  owing  to  the  late  union  or  to  the  non-union  of  the  superior 
and  inferior  infundibula  or  pelves.  In  rare  cases  three  pelves  may  in  like  manner 
remain  separate  in  part  or  in  the  whole  of  their  course  to  the  bladder. 


THE  BLADDER 


The  urinary  bladder  is  a  recej^tacle,  of  which  tlie  form,  size,  and  position  vary 
with  the  amount  of  its  contents.  The  adult  organ  in  its  empty  or  moderately  filled 
condition  lies  entirely  below  the  level  of  the  oblique  plane  of  the  pelvic  inlet;  but 
when  considerably  distended  it  rises  into  the  abdomen  and  shows  itself  beneath  the 
parietes  as  a  characteristic  mesial  projection  above  the  symphysis,  a  projection  Avhich 
in  certain  cases  may  extend  nearly  to  the  level  of  the  umbilicus.  It  is  invested  over 
its  whole  extent  by  recto-vesical  fascia,  and  is  partially  covered  above  and  behind 
l)y  peritoneum  (fig.  617). 

Form, — AMien  fully  distended  it  assume^  in  the  male  an  ovoid  shape  Avith  its 
longest  diameter  directed  downwards  and  backAvards,  but  in  women  the  transverse 
diameter  is  commonly  the  greatest,  owing  to  the  different  shape  of.  the  pelvic  cavity. 
In  the  child  it  is  somewhat  pear-shaped,  the  stalk  being  represented  by  the  urachus. 

The  form  of  the  empty  bladder  is  still  doubtful,  as  the  appearances  in  the  dead 
sul)ject  do  not  necessarily  coincide  with  the  condition  existing  during  life.  In , 
mesial  sagittal  section  it  usually  appears  somewhat  cup-shaped,  its  upper  Avail  pre- 
senting a  rounded  or  pyramidal  hoUoAV  to  the  intestines,  while  its  cavitv'  is  repre- 
sented by  a  T  or  Y-shaped  fissure  (as  in  plate  1  of  Symington's  'Anatomy  of  the 
Child').  It  is  prol)able  that  this  'diastolic'  form,  as  it  has  been  termed,  is  not 
altogether  the  normal  result  of  a  relaxation  preliminary  to  refilling;  but  is  ]:)artly 
due  to  the  loss  of  vital  elasticity  of  the  muscular  Avail,  and  that  the  healthy  living 
bladder  maintains  a  rounded  or  ovoid  form  even  when  empty. 

The  three  terms,  '  apex '  or  '  superior  fundus,'  '  inferior  fundus,'  and  '  neck,'  are 
connnonly  applied  to  parts  of  the  bladder:  the  first  to  the  point  of  attachment  of  the 
superior  ligament  or  urachus  (a  relic  of  the  tube  of  communication  l)ctAveen  the 
bladder  and  allantois)  Avhich  connects  it  Avith  the  umlnlicus;  the  second  to  the  loAver 
part  of  the  organ,  and  the  third  to  the  point  at  Avhich  the  vesical  cavity  becomes 
continuous  Avith  the  urethra;  but  the  expressions  are  all  more  or  less  o]ijectiona])le, 
and  serA'e  no  useful  ])uri)ose.  Under  ordinary  distension  the  so-called  '  a})ex  '  is 
as  much  rounded  as  the  rest  of  the  viscus;  the  anatomical  limits  of  the  '  inferior 
fundus'  are  still  undefined;  and  the  only  'neck'  that  can  be  assigned  to  the  blad- 
der is  represented  by  the  prostate  and  prostatic  urethra. 

Relations. — The  Idadder  Avhen  moderately  filled  may  be  said  to  present  for 


riiK  i;ladt)ER 


1017 


description  five  aspects  or  surfaces:  anteroinferior  or  pul)ic,  jjosterior  or  rectal, 
superior  or  intestinal,  and  two  lateral  or  obturator  surfaces.  The  anteri<jr,  poste- 
rior, and  lateral  surfaces  meet  above  at  the  urachus,  and  converge  below  towards 
the  base  of  the  prostate — the  posterior  wall  sometimes  approaching  the  urethral 
orifice  almost  in  a  vertical  direction,  as  in  Braune's  section  (plate  2),  or  curviim 
first  downwards,  and  then  forwards,  as  in  fig.  617;  and  in  old  subjects  this  curve 
may  be  so  exaggerated  that  a  kind  of  pouch  is  formed  Ijeliind  the  internal  meatus. 
The  antero-inferior  surface  looks  downwards  and  forwards  towards  the  symphvsis. 
Jt  is  uiicovcrcd  l)y  ])erit()neuni,  but  has  a  strong  investment  of  recto-vesical  fascia, 
and  is  si'j>arate<l  from  the  i)ul)ic  l»ones  and  anterior  attncliincnts  of  the  ol)turatores 
interni  and  levatores  ani  by  a  space  known  as  the  cavum  Retzii,  which  contains  a 


Fig.  617. — Median  Sagittal  Section  of  the  ISIale  Pelvis. 
(From  a  preparation  in  the  Aluseum  of  St.  Thomas's  Hospital.) 


RECTO- 
VEilCAL  POUCH 
W  TH  ADIPOSE 
FOLD 


bphincter  mi 


variable  quantity  of  loose  fat  continuous  witli  the  pelvic  and  altdominal  subj^cri- 
toneal  tissue.  Each  lateral  surface  is  covered  by  peritoneum  down  to  the  level  of 
a  line  extending  from  the  urachus  backwards  to  a  jjoint  below  the  sunnnit  of  the 
vesicula  seminales,  al^out  an  inc-h  above  the  base  of  the  prostate.  Below  this  level 
it  is  separated  from  the  levatores  ani  by  subperitoneal  tissue,  which  usually  1  tears 
much  fat  in  its  meshes  and  ensheathstlie  vesical  vessels  and  nerves;  and  it  is  cro.«;.*ed 
l\v  the  vas  deferens,  and  at  the  point  of  jieritoneal  reflexion  by  the  oblitcrat<'d  hypo- 
gastric artery.  The  ureter  ])ierccs  the  junction  of  the  ])osterior  and  lateral  surfaces 
aliout  an  inch  and  a  half  above  tin-  ])rostate,  the  vas  running  between  it  and  the 
vesical  wall.  External  to  these  structures  the  lateral  wall  is  in  relation  to  the  leva- 
tor ani  and  the  obturator  internus.  The  posterior  surface  may  be  divided  into 
two  portions,  an  upjter  covered  by  the  jieritoneum  of  the  ncto-vesical  or  utero- 


1018  THE   URIXARY   ORGANS 

vesical  pouch,  a  lower  in  direct  contact  witli  the  anterior  wall  of  the  rectum,  and 
the  lower  part  of  the  vasa  deferentia  and  vesicul»  seminales.  The  distance  of  the 
recto-vesical  cul-de-sdc  of  i)eritoneum  from  tlie  prostate  is  very  variable,  but  usually 
ranges  between  half  an  inch  and  one  inch  (12  to  25  nun.),  and  may  be  increased 
to  two  inches  (5  cm.  )  Ijy  distension  of  the  bladder.  It  is,  however,  very  small  in 
the  child.  The  ureters  where  they  lie  at  the  outer  limits  of  this  surface  are  near  to 
though  not  in  contact  with  the  rectum,  and  a  calculus  in  the  lower  end  of  the 
urinary  tube  might  l)e  felt  l\v  an  exploration  from  witliin  the  l)ow(l.  In  the  lower 
portion  of  the  posterior  wall  in  the  male  is  a  triangular  space,  the  sides  of  Avhich 
are  formed  by  the  diverging  vasa  deferentia,  the  base  by  the  line  of  reflexion  of  the 
recto-vesical  pouch  of  peritoneum,  and  the  apex  by  the  meeting  of  the  ejaculatory 
ducts  at  the  summit  of  the  prostate.  It  was  formerly  selected  as  Xhe  position  for 
the  introduction  of  a  trocar  through  the  rectum  into  the  bladder  in  cases  of  reten- 
tion of  urine.  In  the  female  the  posterior  surface  is  adherent  below  to  the  cervix 
uteri  and  upper  part  of  the  anterior  wall  of  the  vagina,  luit  is  separated  above  from 
the  body  of  tlu^  uterus  l»y  a  shallow  utero-vesical  pouch  of  peritoneum. 

The  superior  surface  is  entirely  covered  with  peritoneum.  It  looks  almost 
directly  upwards  into  the  abdominal  cavity,  and  lies  in  contact  with  the  small 
intestines,  and  sometimes  Avith  a  portion  of  the  sigmoid  colon  behind  these. 

Effects  of  distension. — When  the  bladder  becomes  excessively  full  it  rises 
above  the  level  of  tlie  symphysis,  and  in  certain  chronic  conditions  of  retention 
may  even  mount  as  high  as  the  umbilicus.  During  the  process  of  distension  the 
anterior  wall  carries  U})wards  the  peritoneal  fold  reflected  on  to  its  upper  surface. 
This  elevation  is,  however,  variable  and  limited  in  extent;  at  its  maximum  it 
seldom  exceeds  two  inches  (5  cm.),  and  in  some  instances  fails  even  to  pass  the 
upper  border  of  the  symphysis,  hence  there  is  some  danger  in  tapping  the  bladder 
above  the  pubes,  unless  the  part  is  exposed  by  a  careful  dissection.  In  recent 
years  Garson  and  Pietersen  have  demonstrated  that  the  introduction  into  the 
rectum  of  a  bag  of  suitable  dimensions  filled  Avith  air  or  water  pushes  forward  the 
expanded  viscus  and  may  still  further  increase  the  available  space  for  surgical 
operation,  but  it  does  not  ensure  the  elevation  of  the  peritoneal  fold  aljove  the 
symphysis. 

The  relation  of  the  internal  urinary  meatus  to  the  pelvic  wall  has  become  a 
subject  of  interest  since  the  revival  of  suprapuljic  operations  \x\)0\\  the  bladder.  As 
a  rule  it  lies  at  some  point  opposite  the  upper  half  of  the  symphysis,  but  in  great 
distension  of  the  viscus  (see  Riidinger,  plate  3)  it  may  descend  to  a  lower  level. 
On  the  other  hand,  in  young  children  it  usualh'  reaches  the  level  of  the  upper 
border  of  the  symphysis,  and  in  old  persons  with  prostatic  disease  it  may  rise  even 
above  this  point.  In  the  male  adult  it  lies  from  three-quarters  of  an  inch  to  an 
inch  (2  cm.  to  2.5  cm.)  behind  the  symphysis,  and  about  two  or  two  and  a  half 
inches  (5  cm.)  above  the  perinteum. 

Structure. — The  bladder  w^all  is  composed  mainly  of  unstriped  muscular  fibre, 
invested  externally  by  a  layer  of  recto-vesical  fascia  and  a  partial  covering  of 
peritoneum,  and  lined  with  mucous  membrane  and  submucous  tissue.  Its  thick- 
ness varies  greatly  in  different  subjects  and  in  the  same  su])ject  under  dift'erent 
conditions  of  distension.  It  is  estimated  at  about  an  eighth  of  an  inch  when 
moderately  stretched,  but  may  reach  half  an  inch  or  even  more  when  completely 
contracted.     It  is  somcAvhat  thicker  at  the  trigone. 

The  arrangement  of  the  peritoneum  over  the  su])erior,  lateral,  and  posterior 
walls  has  l)een  described,  and  it  only  remains  to  mention  that  its  reflexions  over 
the  urachus  above,  and  from  the  sides  and  back  of  the  bladder  bt'low,  form  the 
superior,  lateral,  and  posterior  false  ligaments.  The  recto-vesical  fascia  is  a 
well-developed  layer  of  tissue  over  the  lower  part  of  the  viscus,  but  is  greatly 
attenuated  above.  It  is  continuous  below  Avith  the  capsule  of  the  prostate,  and 
passes  on  to  the  pubic  bones  in  front  of  the  latter  organ  in  tlie  form  of  a  doulile 
fold  called  the  pubo-prostatic  or  anterior  true  ligaments,  and  u]ion  the  IcA'ator 
ani  at  the  sides,  Avhere  its  reflexions  are  termed  the  lateral  true  ligaments,  while 
the  urachus  aboA^e  represents  a  superior  ligament.  These  traditional  names. 
hoAA^ever,  are  misleading  and  haA'e  no  praeticnl  value.  The  muscular  coat  is 
composed  of  unstri])ed  fibres,  Avhich  may  be  divicU'd  n)Ughly  into  three  layers,  an 


THE  BLADDER 


101'.) 


outer  principally  longitudinal,  a  middle  chietly  transverse,  and  an  inner  jjlexiforni, 
l)Ut  tending  towards  the  vertical  din^ction.  The  lil>res  of  the  outer  layer  are  most 
distinctly  longitudinal  on  the  anterior  and  jjosterior  surfaces,  and  extend  altove 
along  tlie  urachus,  but  they  run  ohlicjuely  over  the  sides  of  the  l>ladder,  decus- 
sating with  each  other  in  a  coni])lex  manner;  and  near  the  urethral  end  of  the 
viscus  two  strong  bundles  of  the  anterior  longitudinal  iibres  run  one  on  each  side 
of  the  middle  line  in  front  of  the  anterior  wall  of  the  jjrostate  and  l)eneath  the 
pubo-i>rostatic  ligament,  to  bccunif  attachid  to  the  liack  of  the  pubic  bones  on 
eacli  side  of  the  synii)hysis  (vesico-pubic  muscle).  The  lower  fibres  of  the 
iiiiildle  layer  form  a  kind  of  annular  sphincter  near  the  urethral  orifice  (sphincter 
vesicae  internus),  the  fibres  of  which  are  continuous  with  the  upper  sphincteric 
fil)res  of  the  j)rostate,  and  at  the  trigone  are  reinforced  by  the  exi)ansion  of  the 
longitudinal  ureteric  filjres  named  on  page  1016.  The  inner  layer  ajjpears  as  a  set 
of  well-defined  bands  running  in  a  longitudinal  direction  and  communicating  with 
eacli  other  by  means  of  oblique  fasciculi.  These  bands,  when  hypertro))hied, 
appear  as  distinct  ridges  l)eneath  the  nuicous  membrane,  and  their  interspaces 
may  be  seen  as  depressions  wiiich  occasionally  develop  into  diverticula.  At 
the  trigone,  the  inner  layer  is  strengthened  by  the  radiation  of  the  ureteric 
filjres. 

The  rather  coarse  meshwork  formed  by  the  decussating  muscular  Ijundles  is  apt 


Fig.  618.— The  Posterior  Wall  of  the  Bladder.     (After  Hcnle.) 


URETER  PIERCING  VESICAL 
WALL 


PLICA  URETERICA 
VESICAL  APERTURE  OF 
URETER 

MUSCULARIS 

UVULA  OF  LiEUTA'j: 


VERUMONTANUM 

OPENING  OF  EJACULATORY  DUCT 

SINUS  POCULARIS 

PROSTATIC  SINUS 


to  ])re>ent  weak  points  througli  whicli  the  mucous  membrane  may  protrude  as 
diverticular  sacculations,  sometimes  of  considerable  size  and  capable  of  lodging 
calculous  concretions.  On  the  other  hand,  Avhen  the  muscular  tissue  becomes 
hypertrophied  from  excessive  use,  it  often  forms  strong  ridge-like  ])rojections  which 
may  give  rise  to  deceptive  impressions  during  exploration  of  the  cavity  with  the 
sound. 

The  submucous  coat  consists  of  a  highly  clastic  connective  tissue  devoid  of 
muscular  fibres. 

The  mucous  membrane  is  smooth,  soft,  and  rose-coloured  during  life.  In  the 
empty  bladder  it  is  tlirowninto  irregular  folds,  which  become  efFaeed  l\v  distension. 
It  is  modified  posteriorly  over  a  triangidar  area  called  the  Trigone  of  Lieutaud 
(fig.  61.'*'),  the  three  angles  of  which  lie  at  the  internal  meatus  and  the  two  mvteric 
orifices,  and  are  at  a  distance  from  each  other  of  three-(iuarters  of  an  inch  to  an 
inch  (18  to  25  mm. ).  This  region,  which  lies  opposite  to  the  '  second  portion  '  of  the 
rectum,  is  free  from  the  ])lication  that  a])p»'ars  in  tlie  rest  of  the  mucous  membrane 
during  contraction  of  the  cavity,  nod  is  bounded  V)y  a  transverse  elevati">n  l>etwcen 
the  in-eters,  called  the  plica  ureterica,  and  jiresents  a  longitudinal  mesial  ridge, 
the  uvula  of  Lieutaud.  near  the  lU'cthral  orifice.  It  is  smaller  and  less  distinct 
in  the  female.      The  infmidl  urinary  meatus  usually  lies  ;it  tlie  niosf  dependent  part 


1020 


THE    URIXARY  OnOAXS 


of  tlic  bladder,  but  in  mor])id  conditions  of  the  ])rostatc  the  borders  of  the  aperture 
may  be  considerably  elevated  al)Ove  the  adjacent  vesical  zone. 

The  female  bladder  (fig.  619)  presents  no  peculiarities  of  importance,  except 
that  its  frontal  diameter  is  usually  increased  at  the  ex]K>nse  of  the  sagittal  diameter, 
partly  in  consequence  of  the  greater  widtli  of  the  pelvis,  and  partly  owing  to  the 
presence  of  the  vagina  and  uterus,  which  encroach  U}jon  the  space  in  the  middle 
line.  Lateral  asymmetry  is  very  common.  Furthermore,  the  symphysis  being  of 
less  depth  than  in  the  male,  the  urinary  orifice  lies  nearer  its  lower  border. 

In  the  infant  the  bladder  is  said  to  be  an  abdominal  organ,  but  this  is  not 
strictly  accurate.  The  relatively  small  j)elvic  cavity  at  this  period  of  life  is  occupied 
mainly  liy  the  rectum,  and  there  is  little  room  for  tin-  bladder,  which  hence  rises 

Fig.  (519.— Section  of  the  Fejiale  Pelvis.     (After  Heule.) 


VESICAL  WALL 

CAVITY  OF  BLADDER 

Prevesical  fat 

Dorsal  vein 
CLITORIS 

Deep   trausver- 
sus  perinaei 


LABIUM  MAJUS 
Unatriped  muscular  fibre 


URETHRA 
LABIUM  MINUS 
TJustriped  muscular  fibre 


ANUS 
Internal  sphincter  ani 
Part  of  external  sphincter  ani 


RECTUM 

COCCYX 

Recto-coecy- 
geal   muscle 

POSTERIOR  LIP  OF  OS 

UTERI 
ANTERIOR  LIP 

VAGINA 

External 
sphincter  ani 

Internal 
sphincter  ani 


i'essi'ls 


VAGINAL  ORIFICE 


into  the  abdomen  even  in  moderate  degrees  of  distension;  Ijut,  as  pointed  out  T)y 
Symington,  if  a  line  be  drawn  from  the  sacral  promontory  to  the  top  of  the 
symphysis,  fully  one-half  of  the  bladder  will  be  found  to  lie  below  it,  and  hence 
within  the  j)elvis.  The  internal  meatus,  however,  is  behind  the  upper  margin  of  the 
symphysis,  and  the  whole  organ  is  hence  above  the  horizontal  level  of  the  pubic 
crests.  This  relation  gradually  changes  from  the  period  at  which  indej^endent 
locomotion  begins,  till,  by  the  age  of  six,  when  the  pelvic  wall  has  grown  u]i  around 
the  viscus,  the  position  does  not  differ  materially  from  that  in  the  adult.  It  should 
also  be  noted  that  the  recto-vesical  fold  of  j)(,'ritoneum  extends  in  infancy  nearly  as 
low  as  the  base  of  tlie  prostate. 

Vessels. — The  arteries  of  the  bladder  are  derived  from  the  internal  iliac  and 


THE  PROSTATE  1021 

iiitornal  piulic,  and  in  the  female  some  twigs  are  also  aivcii  off  l»y  the  uterine  and 
vaginal  arteries.  The  veins  terminate  in  the  internal  iliae  trunk.  They  form 
plexuses  whieli  are  especially  large  ahout  the  parts  adjacent  to  the  prostate,  and 
communicate  in  the  male  with  all  the  veins  in  the  neigiibourhood.  Liimpli(itic>< 
ajijiearas  a  subnuicous  plexus  wiiieh  is  most  developed  in  the  neigh])Ourhood  of  the 
internal  meatus.  They  accompany  the  veins  and  terminate  in  the  internal  iliac 
glands. 

Nerves. — The  nerves  are  derived,  partly  from  the  sympathetic  system  through 
the  hypogastric  plexuses,  partly  from  the  cerehro-spinal  system  through  the  third 
and  fourth  sacral  nerves.     The  former  supply  the  mucosa,  the  latter  the  muscularis. 


THE  MALE  REPRODUCTIVE  ORGANS 

The  reproductive  organs  of  the  male  consist  of  (1)  two  testicles  or  seminal 
glands,  with  their  excretory  tubes;  (2)  a  musculo-glandular  organ,  the  prostate, 
which  provides  a  material  for  the  dilution  of  the  semen,  and  by  its  sphincteric 
contraction  aids  in  the  ejaculation  of  the  spermatic  fluid,  and  at  the  same  time 
intercepts  its  retrograde  i)assage  into  the  bladder;  (3)  an  organ  of  copulation,  the 
penis;  and  (4)  a  canal,  the  urethra,  which  pierces  the  prostate  and  penis,  and 
serves  for  the  transit  of  both  the  generative  and  urinary  secretions. 


THE  PROSTATE 

The  prostate  is  a  firm  clastic  and  contractile  organ,  lying  between  the  bladder 
and  the  penis,  and  perforated  by  the  urethra  (figs.  620,  624,  and  649).  It  is 
roughly  comparable  to  a  horse-chestnut  in  form  and  dimensions;  its  broader 
extremity  or  Imse  lies  ui)permost  and  l)lends  with  the  vesical  sphincter,  while  its 
apex  rests  against  the  sui)erior  triangular  ligament.  Its  long  axis  is  vertical  (in 
the  erect  posture),  or  inclines  slightly  forwards  below  (fig.  6i7),  and  is  nearly  an 
inch  and  a  ciuarter  (3  cm. )  in  length.  Its  transverse  diameter,  greatest  near  the 
base,  measures  about  an  inch  and  a  half,  and  its  antero-posterior  diameter  about  an 
inch.  Its  average  weight  is  a])out  six  drachms,  nearly  the  same  as  that  of  the 
testicle,  and  it  may  be  noted  that  the  active  evolution  of  the  two  organs  begins  at 
the  same  period,  at  puberty,  and  that  the  structural  and  functional  development 
of  the  one  is  intimately  associated  Avith  that  of  the  other  during  the  period  of 
sexual  vigor.  It  offers  for  description  a  base,  an  apex,  and  anterior,  lateral,  and 
posterior  walls.  The  base  is  connected  -with  the  musculature  of  the  bladder, 
receiving  the  attachment  of  the  longitudinal  fiJ)res  and  sui'rounding  the  sphincteric 
portion  of  the  circular  layer  at  the  urethral  orifice.  It  usually  lies  a  little  above  the 
level  of  the  middle  of  the  symphysis.  The  apex,  resting  against  the  su]ierior  or 
dee[)  triangular  ligament,  is  from  one-half  to  three-fourths  of  an  inch  (12  to  1<S  mm. ) 
l)ehind  and  a  little  below  the  subpubic  angle,  and  on  rectal  exploration  will  be 
foTind  about  an  inch  and  a  (piarter  above  the  margin  of  the  anus.  The  anterior 
wall  is  rounded,  and  is  covered  by  the  ])rostatic  plexus  of  veins  and  the  vcsico- 
pul)ic  nniscle  and  pul)o-prostatic  ligaments  (page  1018).  The  lateral  walls  are  in 
contact  with  the  inner  borders  of  the  two  levatores  ani  muscles  and  tlu'  marginal 
])ortion  of  the  venous  plexus,  and  project  al)ove  and  behind  in  the  form  of  ill- 
dctined  lateral  lobes,  which  may  be  looked  upon  as  the  jtersistent  indication  of 
its  development  in  two  halves.  The  posterior  wall  is  tiattened  and  is  opjioscd  to 
the  rectum,  from  which  it  is  separated  by  some  connective  tissue  and  unstri]>ed 
muscular  filu'es  continuous  with  the  subperitoneal  tissue  and  jx'lvic  fascia. '  Near  its 
upper  border  is  a  transverse  median  cleft,  the  prostatic  fissure  (fig.  624),  whidi 
extends  deeply  inwards  and  forwards  towards  the  middle  of  the  prostatic  urethra, 
transmitting  the  connnon  ejaculatory  ducts  and  the  sinus  pocularis,  and   in  section 


1022 


THE  MALE  REPRODUCTIVE  ORGANS 


(fig  620)  appearing  as  the  posterior  and  inferior  Itonndarv  of  a  portion  of  tlie  sub- 
stance of  tlie  organ,  the  so-called  '  middle  lobe.' 

An  irregular  artery,  usually  derived  from  the  internal  iliac  trunk,  is  sonietiines 
found  running  b)'  the  side  of  the  prostate  to  reach  the  dorsum  of  the  penis,  and 
may  be  the  source  of  dangerous  haemorrhage  in  lateral  lithotomy.  It  rej)laces  one 
or  more  of  the  terminal  branches  of  the  internal  pudic. 

Structure  and  function. — The  ])rostate  is  invested  by  a  fibro-muscular  capsule, 
derived  from  the  recto-vesieal  segment  of  the  pelvic  fascia,  unstriped  muscle  exist- 
ing in  largest  proportion  over  its  rectal  aspect,  bet^A'een  the  ojtposed  borders  of  the 
levatores  ani.  The  organ  itself  is  composed  of  muscular  and  glandular  tissue. 
The  muscular  element,  comprising  both  striped  and  unstriped  fil)res,  represents  about 
one-half  of  the  entire  mass.  The  unstri]ied  fil^res  embrace  the  vesical  sphincter 
above,  forming  with  this  a  ring  of  great  firmness  and  strength  above  the  urethral 
orifices  of  the  ejaculatory  ducts,  and  discharging  in  all  probability  the  function  of 
intercepting  the  backward  flow  of  the  semen  and  prostatic  fluid  into  the  bladder 
during  sexual  congress;  below  this  point,  the  muscle  is  intermingled  with  gland 
tissue  and  striated  fibres.     The  striped  fibres  lie  chiefly  in  the  anterior  wall  of  the 

Fig.  620. — Semi-diageammatic  Sectiox  of  the  Male  Pelvis. 

■MIDDLE  LOBE'  OF  PROSTATE  ABOVE  THE  PROSTATIC  FISSURE 


SINUS  POCULARIS  IN  PROSTATIC  FISSURE 


MUCOUS  MEMBRANE  OF  BLADDER 


INTERNAL  URINARY 
MEATUS 


VASA  DEFERENTIA  AND  VESICUL/€  SEMINALES 
ANTERIOR  WALL  OF  RECTUM 


CAVITY  OF  RECTUM  WITH  FOLD  OF 
KOHLRAUSCH 


Fascia  trans- 
versalis 

Kecto-vesieal 
fascia 
Fat  in  space 
of  Ketzius 

SYMPHYSIS 

Vesico-pubic 
muscle 

ANTERIOR  WALL  OF 
PROSTATE  WITH 
CAPSULE 

Dorsal  vein 
of  jii'nis 


SEPTUM  PECTINIFORME 


CORPUS  SPONGIOSUM 
URETHR/E 


STERIOR  WALL 
OF  PROSTATE 
WITH   CAPSULE 

Seetal  por- 
tion of  recto- 
vesical   fascia 

Sphincter  ani 


LOWER  END  OF 

RECTUM 
Sphincter  ani 


Fascia  of  Colles 
Deep  transversus  perinaei  between  superficial 
and  deep  triangular  ligaments 


Junction  of  deep  and  superficial  triangular 
ligaments  with  fascia  of  Colles 


COWPER'S  GLAND 


prostate,  but  completely  encircle  the  apex  of  the  organ,  and  are  there  pr(i])ably 
(•oiinected  with  the  deep  transversus  perinaei.  The  mus(;ular  fibres  of  both  kinds 
Ijelow  the  ejaculatory  ducts  undoubtedly  initiate  the  forward  projuilsion  of  the 
mingled  prostatic  and  seminal  secretions;  the  ejaculation  being  further  aided  by 
the  contraction  of  the  deep  transversus  perinsei,  and  Intlbo-cavernosi. 

The  glands  are  of  the  branched  tul)ular  type,  and  lie  chiefly  in  the  jiosterior  and 
lateral  i^arts  of  the  organ,  their  ducts  opening  into  the  urethral  recesses  (prostatic 
sinuses )  l)y  the  sides  of  the  verumontanum.  They  secrete  a  mucus,  the  princij^al 
use  of  which  is  to  dilute  and  give  bulk  to  the  semen,  and  they  are  sometimes  the 
seat  of  pathological  concretions.  In  addition  to  the  true  glands  are  seen  a  number 
of  simple  follicles  in  the  anterior  wall  of  the  prostatic  urethra,  probably  of  the 
same  nature  as  the  rest  of  the  urethral  follicles.  The  prostatic  urethra  will  be 
described  hereafter  (page  1087). 

The  organ  is  essentially  generative,  but  serves  also  to  reinforce  the  vesical 
sphincter,  although  its  absence  in  the  female  and  its  imi)erfect  development  in  chil- 
dren and  eunuchs  ap)>ear  to  entail  no  defect  in  th(>  control  of  the  bladder.  The 
muscular  fibres  are,  however,  to  some  extent  rei)resented  in  the  female  (page  1042). 


THE  TESTICLES 


1028 


Vessels  and  Nerves. — Tlic  arteries  of  \hv  prostate  arise  from  the  adjacent 
vesical  and  lueniorrhoidal  vessels.  'I'Ih'  prostatic  veins  receive  the  dorsal  vein  oi 
the  penis,  and  after  forming  a  plexns  (  plexus  of  Santorini)  investing  the  anterior 
and  a  portion  of  the  lateral  surfaces,  terniinate  in  tiie  adjacent  vesical  veins.  The 
lymphatics  end  in  the  ])elvie  glands,  and  a  small  gland  may  sometimes  ))e  foimd 
on  each  side  near  the  base  of  the  organ.  Tlu;  nerves  are  d(  rived  from  tin' 
hyi)og;istric  plexus. 


THE   TESTICLES   AND   THEIR   APPENDAGES   AND   COVERINGS 

The  two  testicles  lie  in  a  common  pouch  of  integument  called  tlie  scrotum,  and 
each  organ  is  invested  in  addition  by  a  series  of  coverings  Avliich  join  in  the  middle 
line  to  form  a  septum  scroti.  There  are  three  ])rincipal  layers:  an  outer  (the 
dartos)  of  unstrijxHl  muscular  fibre,  a  middle  (the  cremasteric)  containing  strijicd 
nuiscular  fibre,  and  an  inner  serous  (tlie  tunica  vaginalis),  separated  from  each 
other  by  layers  of  connective  tissue.  The  coverings  (tig.  G21),  named  from  without 
inwards,  are  (1)  the  dartos  ;  (2)  the  external  spermatic  fascia  ;  (3)  the  cremasteric 
or  middle  spermatic  fascia  ;  (4)  the  internal  spermatic  fascia  ;  (o)  subi^eritoneal 
fascia  ;  and  (6)  the  tunica  vaginalis. 


Fig.  621. — IIokizoxtal  Sectiox  of  the  Scrotum  and  Testicle.     (Diagrammatic.) 


Septum  scroti 


MEDIASTINUM    TESTIS 


VAS  DEFERENS 


-   Skin 

Dartos 

External  spermatic  fascia 

Cremasteric  fascia 

- —    Parietal  layer  of  tunica  vaginalis 

=7—;^ —    Internal  spermatic  fascia  and 
subperitoneal  fascia 

Cavity  of  tunica  vaginalis 
Visceral  layer  of  tunica  vaginalis 
Tunica  albuginea 
Digital  fossa 
EPIDIDYMIS 


THE  SCROTUM. — Tlie  scrotal  integument  is  more  or  less  pigmented,  and 
covereij  in  the  adult  with  coarse,  scattered  hairs,  and  provided  with  strongly  devil- 
oped  sebaceous  and  sudoriparous  glands.  It  presents  in  the  middle  line  a  longi- 
tudinal impression,  the  raphe,  from  which  start  on  either  side  a  multitude  of 
transverse  wrinkles,  efl"aceal)le  by  distension. 

(1)  The  dartos  is  a  thin  reddish  layer  composed  of  elastic  tissue  freely  inter- 
mingled with  unstriped  muscular  fibres.  It  is  adherent  to  the  deep  surface  of  the 
skin,  but  passes  inward  septally  betAveen  the  two  testicles,  forming  a  sejiarate  sac 
for  each,  and  is  prolonged  over  the  penis  and  perina-iun.  Its  fibres  assume  various 
directions,  but  for  the  most  part  run  longitudinally  at  right  angles  to  the  scrotal 
wrinkles,  of  which  they  are  the  cause.  They  are  always  moderately  contracted  in 
health,  and  contract  still  more  under  the  influence  of  cold  and  of  mental  emotion, 
but  are  not  affected  l)y  electricity.  They  ]>eeome  relaxed  in  conditions  of  general 
enfeei)lement.  According  to  Barrois.  the  dartos  is  divided  int<i  two  layers,  the 
more  superlicial  Ix'ing  connnon  to  l)oth  testicles,  while  the  de(^]M'r  and  stronger 
forms  a  separate  investment  for  each  testicle.  an<l  assists  in  the  formation  of  the 
septum  scroti. 

(2)  The  external  spermatic  or  '  intercolumnar  '  fascia  consists  of  a  fatless, 
laminated  C(nmeetive  tissue,  within  and  closelv  adherent  to  the  darttxs,  blending  at 


10-24  THE  MALE  REPRODUCTIVE  ORGANS 

the  external  inguinal  openinjj;  with  the  t^troiig  lihrous  bands  crossing  the  cohnnus 
of  the  ring-,  and  i)rolonged,  like  the  dartos,  over  the  penis  and  periniemn.  It  is 
continuous  behind  with  the  deep  layer  of  the  superticial  perinneal  fascia,  and  above 
Avith  the  superficial  fascia  over  the  symphysis. 

(3)  The  cremasteric  or  middle  spermiatic  fascia  is  a  well-defined  fibro-mus- 
cular  expansion  covering  the  cord  and  testicle.  It  consists  of  a  strong  double 
lamina  of  areolar  and  elastic  tissue  enclosing  and  connecting  longitudinal  bundles 
of  striped  muscle,  the  fibres  of  which  may  be  traced  above  to  the  external  inguinal 
ring,  where  they  are  divided  into  two  principal  sets:  an  inner  (often  absent),  attached 
to  the  pubic  spine,  and  an  outer  derived  from  the  lower  border  of  the  internal 
ol:)lique,  and  arising  ixowi  Pou})art's  ligament  opposite  the  inguinal  ring.  Below, 
the  tunic  lilends  with  the  dartos  opposite  the  lower  extremity  of  the  testicle.  The 
cremaster  contracts  during  convulsive  expiratory  actions  of  the  abdominal  muscles 
and  under  emotional  influences. 

(4)  The  internal  spermatic  or  '  infundibuliform  '  fascia  is  a  delicate  con- 
nective tissue  derived  from  the  fascia  transversalis. 

(5)  The  subperitoneal  fascia  beneath  the  last,  and  more  or  less  blended  with 
it,  is  a  laminated  prolongation  of  the  sul)peritoneal  tissue  closely  investing  the 
elements  of  the  cord  and  testicle.  It  contains  elastic  fibres,  adipose  tissue,  and 
unstriped  muscular  elements,  and  is  the  seat  of  the  fatty  tumors  of  the  cord  which 
occasionally  simulate  inguinal  hernia.  The  muscular  fibres  form  a  longitudinally 
directed  layer  on  the  deep  aspect  of  the  connective-tissue  fibres,  and  are  called 
'  middle  cremaster '  by  Klein  and  Barrois  to  distinguish  them  from  the  '  external  cre- 
master '  of  striped  fibres  and  the  '  internal  cremaster '  described  in  connection  with 
the  cord. 

(6)  The  tunica  vaginalis,  a  serous  investment  of  the  testicle,  is  described 
below. 

Vessels  and  Nerves. — The  skin  and  dartos  are  supplied  by  branches  of  the 
external  pudic  and  superficial  perinajal  arteries,  while  the  cremaster,  the  internal 
spermatic  fascia,  the  subperitoneal  fascia,  and  the  visceral  layer  of  the  tunica  vagi- 
nalis receive  a  special  branch  from  the  deep  epigastric;  the  corresponding  veins 
communicate  with  the  pudic,  the  long  saphenous,  and  the  dorsal  vein  of  the  penis. 
The  lymphatics  terminate  in  the  innermost  set  of  the  inguinal  glands  (the  lym- 
phatics of  the  testicle  itself  passing  to  the  lumbar  glands).  The  nerves  are  derived 
from  the  genito-crural  and  superficial  perinseal. 

THE  TESTICLES. — The  testicles  (fig.  62'2),  two  in  number,  are  suspended  from 
the  inguinal  region  by  the  spermatic  cords.  The  left  is  supposed  to  hang  some- 
what lower  than  the  right  in  the  majority  of  persons.  Each  gland  consists  of  two 
pt)rtions,  the  testicle  proper  and  the  epididymis.  Its  weight  as  a  whole  averages 
between  five  and  six  drachms,  rarely  attaining  the  maximum  of  an  ounce;  it  is 
al)out  an  inch  and  a  half  (4  cm.)  in  length,  an  inch  and  a  quarter  (3  cm.)  in 
depth  (from  the  anterior  to  the  posterior  border),  and  somewhat  less  than  an  inch 
(22  mm. )  in  thickness.  It  is  so  suspended  in  the  scrotum  that  its  upper  extremity 
inclines  a  little  more  forward  than  the  lower,  and  its  inner  surface  is  turned  slightly 
forwards  as  well  as  inwards. 

The  Testicle  proper  is  shaped  somewhat  like  a  kidney  bean;  it  is  elongated 
from  above  downwards,  and  flattened  from  side  to  side.  Its  surface  is  smooth  and 
white,  and  is  covered  by  the  visceral  laj^er  of  the  tunica  vaginalis,  except  where  it 
is  in  contact  with  the  epididymis. 

The  Epididymis  is  adherent  to  the  posterior  and  inferior  part  of  the  testicle 
jiroper  and  inclines  slightly  to  the  outer  side.  It  is  enlarged  aliove  into  a  head  or 
globus  major,  and  below  into  a  tail  or  globus  minor,  the  intermediate  portion 
being  called  the  body. 

The  Tunica  Vaginalis  is  a  serous  sac  of  peritoneal  origin,  which  bears  to  the 
testicle  a  relation  similar  to  that  of  the  serous  pericardium  to  the  heart.  It  consists 
of  parietal  and  visceral  layers. 

The  visceral  layer  is  intimately  adherent  to  the  testicle  proper,  and  to  the  globus 
major  and  outer  part  of  the  Ijody  of  the  epididymis,  and  is  })rolonged  uinvards  for 
aljout  half  an  inch  upon  the  si)ermatic  cord.  On  the  outer  side  and  above,  it 
extends  into  a  dee})  de}jression,  the  digital  fossa,  between  the  testicle  and  epididy- 


THE  TESTICLES 


1025 


mis;  but  it  leaves  uncovered  nearly  the  whole  of  the  jiloi)\is  minor  and  the  internal 
and  posterior  surfaces  of  the  lx)dy  of  the  epididymis,  and  it  is  in  these  situations 
that  an  important  vascular  communication  is  estaldished  between  the  gland  and  its 
coverings. 

The  parietal  layer,  continut)Us  with  the  visceral  layer  at  the  posterior  and  inferior 
parts  of  the  testicle  and  at  the  point  of  reflexion  from  the  spermatic  cord,  becomes 
loosely  attached  to  the  internal  spermatic  fascia  ]:»y  means  of  a  })rolongation  f)f  the 
abdominal  subperitoneal  tissue.  It  contains  a  number  of  unstriped  muscular  fibres 
running  longitudinally  and  continuous  with  the  internal  cremaster.  Under  normal 
conditions,  the  two  serous  layers  are  in  contact,  the  serous  fluid  l)eing  secreted  only 
in  sufficient  quantity  to  moisten  tlie  opposed  surfaces.  An  undue  increase  of  the 
amount  constitutes  the  disease  known  as  vaginal  hydrocele. 


Fig.  622.— The  Left  Testicle  with  Vessels  and  Duct.    (After  Sappey.) 

flnh 


Spermatic  artery 


Spermatic  veins 


Branch  0/  spermatic  artery 


GLOBUS  MAJOR  OF  EPIDIDYMIS 


HYDATID  OF  MORGAGN 


OUTER  WALL  OF  BODY  OF  TESTIS 


VAS  DEFERENS 

with  deferential  artery 


VAS  DEFERENS 


DY  OF  EP;DIDYMIS 
Digital  fossa 


—    Vtestls  of  epididymis 


GLOBUS  MINOR 


The  testicle  is  occasionally  so  rotated  ujion  its  long  axis  that  the  epididymis 
becomes  turned  towards  the  front  of  the  scrotum.  In  this  case,  were  a  hydrocele 
to  occur,  the  sac  would  ju-oject  posteriorly.  The  side  to  which  a  detached  testicle 
Ijelongs  ma}'  be  distinguished  by  remembering  that  the  ei>ididymis  is  attached 
behind,  and  that  the  digital  fossa  of  the  tunica  vaginalis  lies  on  the  outer  side. 

In  order  to  understand  the  relations  of  the  organ  to  adjacent  structures  it  is 
necessary  to  learn  something  of  the  mechanism  of  its  descent.  The  testicle  is  at  first 
an  abdominal  organ  lying  below  the  kidney  and  invested  by  a  layer  of  peritoneum 
(mesorchium  )  which  is  firmly  adherent  to  its  surface  in  front  and  at  the  sides.  It 
is,  moreover,  connected  l)y  bundles  of  unstrii>ed  nuiscular  fil)res.  the  gubernaculum 
testis,  with  the  pillars  of  the  external  imruinal  rinir  and  with  the  dartos  at  the 
65 


1026  THE  MALE  REPRODUCTIVE  ORGANS 

bottom  of  the  scrotum.  It  begins  to  descend  in  the  early  i)art  of  the  third  month 
of  foetal  life,  reaching  the  internal  inguinal  ring  in  the  sixth  month.  It  then  passes 
obli(iUely  through  the  structures  of  the  abdominal  wall,  preceded  by  a  pouch  of 
peritoneum  and  ])ushing  l)efore  it,  in  succession,  the  subperitoneal  tissue,  an 
infundibuliform  prolongation  of  the  fascia  transversalis,  a  few  libers  of  the  internal 
ol)lique  (whieh  form  i)art  of  the  external  cremaster),  and  the  intercohmmar  fascia, 
which  braces  togetlier  the  pillars  of  the  external  inguinal  ring.  At  the  eighth 
month  it  appears  at  the  external  ring,  and  reaches  the  l)ottom  of  the  scrotum  shortly 
before  birth. 

The  cause  of  this  migration  is  still  uncertain.  The  theory  usually  adoi)ted  is 
that  the  descent  is  effected  partly  by  the  development  of  the  pelvic  and  lumbar 
regions  which  grow  upwards,  and  in  a  manner  leave  the  testicle,  fixed  by  the  guber- 
naculum,  Ijehind.  This  accounts  for  the  change  of  position  to  the  level  of  the 
inguinal  canal,  but  the  mechanism  of  the  further  descent  into  the  scrotum  is 
unknown.  It  was  formerly  attributed  to  the  progressive  shortening  of  the  gulier- 
naculum,  and  in  accordance  with  this  view,  the  unstriped  muscular  fibres  connect- 
ing the  bottom  of  the  gland  with  the  scrotum  are  regarded  as  the  remains  t)f  the 
central  and  principal  gubernacular  band,  while  the  lateral  bands,  ceasing  to  act  after 
the  testicle  has  reached  the  external  ring,  are  drawn  down  into  the  scrotum  and 
appear  as  scattered  groups  of  fibres,  the  internal  cremaster  of  Henle,  lying  around 
the  elements  of  the  spermatic  cord  (fig.  (526). 

In  certain  individuals,  the  descent  of  one  or  both  testicles  into  the  scrotum  is 
intercepted,  and  cryptorchism  results.  This  condition  is  normal  in  certain 
animals  (elephants,  cetacea,  etc.),  but  in  man  is  always  associated  with  defective 
evolution  of  the  organ,  and  consequent  suppression  of  function. 

The  peritoneal  sac  carried  with  the  testicle  is  at  first  continuous  with  the 
al)dominal  peritoneum.  In  most  cases  the  tul^e  of  communication  gradually 
narrows,  and  at  length,  within  a  few  days  after  birth,  becomes  entirely  closed. 
Sometimes,  however,  the  process  of  obliteration  is  more  or  less  incomplete. 
Should  it  fail  altogether,  a  portion  of  the  abdominal  viscera  may  pass  into  the 
tunica  vaginalis,  and  constitute  the  congenital  variety  of  inguinal  hernia  ;  or 
peritoneal  fluid  may  accumulate  in  the  testicular  sac  and  form  a  congenital 
hydrocele.  IVIore  frequently  the  continuity  of  the  tunica  vaginalis  with  the 
peritoneum  is  interrupted;  but  a  slender  pouch  of  peritoneum,  the  processus 
vaginalis,  may  run  into  the  inguinal  canal,  and  even  through  the  external  ring 
into  the  cord,  or  the  tunica  vaginalis  may  be  prolonged  upwards  uiH:»n  the  cord  for 
a  considerable  distance. 

Should  any  portion  of  the  abdominal  contents  enter  the  processus  vaginalis,  it 
may  pass  through  the  inguinal  canal  as  a  hernia,  and  descend  into  the  scrotum. 
If  at  the  same  time  the  upward  extension  of  the  tunica  vaginalis  be  present,  the 
hernia  with  its  sac  may  pass  within  it  or  invaginate  it,  and  a  surgeon  called  upon 
to  operate  in  such  a  case  would  pro!)ably  open  the  tunica  vaginalis  before  reaching 
the  peritoneal  sac,  and  thus  meet  with  three  layers  of  serous  memltrane  before 
exposing  the  extruded  intestine.  A  hernia  of  this  kind  is  called  '  infantile.'  Cystic 
tumors  may  !)e  formed  by  the  distension  of  small  unoliliterated  segments  of  the 
funicular  portion  of  the  tube,  and  are  called  encysted  hydroceles  of  the  cord. 

Structure  (fig.  623). — The  testicle  proper  consists  of  a  tul)ular  parenchyma 
enclosed  witliin  a  strong  fil)rous  tunic,  the  tunica  albuginea. 

The  tunica  albuginea  (figs.  621,  623)  is  a  dense,  white,  inelastic  capsule  of 
about  one-twenty-fifth  of  an  inch  (1  mm.)  in  thickness  in  the  greater  part  of  its 
extent,  but  reaching  two  or  three  times  this  admeasurement  beneath  the  epididymis 
where  it  forms  the  mediastinum  testis,  or  Corpus  Highmorianum,  It  is 
perforated  at  its  upper  and  1)ack  part  by  the  eft'erent  seminal  tul»es  which  go  to 
form  the  globus  major  of  the  epididymis,  and  from  its  inner  surface  })ass  a  number 
of  sustentacular  processes,  in  the  form  of  thread-like  fibro-museular  filaments  and 
delicate  septal  planes  of  connective  tissue,  the  trabeculae.  The  mediastinum 
extends  forwards  from  the  upper  half  of  the  posterior  border,  o('cu])ying  al)out  a 
fourth  of  the  sagittal  and  a  third  of  the  transverse  diameter  of  the  interior,  and  is 
tunnelled  by  lilood-vessels  and  a  network  of  seminal  tubes  (the  rete  testis).  The 
trabeculae   radiate  from  the  deep  aspect  of  the  mediastinum  to  the  inner  surface 


THE   TESTICLES 


1027 


of  the  tunica  albuginea,  and  subdivide  the  interior  of  the  capsule  into  a  number 
of  loculi  (150-200J. 

\\'itlnn  these  loculi  lie  tlie  testicuhii-  tubules,  su])ported  ))y  a  fine  retiforni 
conne(!tive  tissue,  whicli  becomes  condensed  into  a  hiiihly  vascular  lamina  called 
the  tunica  vasculosa,  where  it  is  in  contact  with  the  albujiinea.  The  i)roper 
secreting  substance  consists  of  fine  branching  and  anastomosing  canals,  the  tubuli 
seminiferi,  about  yVjith  of  an  inch  (.2  mm.)  in  diameter,  and  lined  witli  a  layer 
of  cul)i(al  cells  in  wliich  are  developed  the  spermatic  filaments  or  spermatozoa. 
The  tul)ules  are  collected  into  little  bundles,  called  lobules,  aliout  three  hundred 
in  number,  each  comprising  two  or  more  separate  tubes.  The  number  of  these 
loliuli's  is  variously  estimated  (300-400),  and  the  total  length  of  the  component 
tubules  has  been  calculated  roughly  at  al)Out  nine  hundred  yards.  By  the  union 
of  the  tul)ules  of  the  different  lobules  are  formed  a  number  of  larger  tubes,  the 
tubuli  recti,  which  converge  towards  the  mediastinum,  and  on  entering  it  l)reak  up 
into  a  plexus,  the  rate  testis  ;  from  the  rate  in  turn  spring  twelve  to  twenty  efferent 
tubes,  or  vasa  efferentia,  twice  or  three  times  as  large  as  the  tubules,  and  these, 
piercing  tlie  uj)per  and  back  part  of  the  albuginea,  end  in  the  head  of  the 
epididymis  ( fig.  623). 

The  epididymis,  representing  the  second  stage  in  the  course  of  the  seminiferous 

Fig.  623. — Dr.\oR.\M  of  tjie  Testicul.^r  Tubules. 


TUNICA  ALBUGINEA  RECEIVING  ATTACH- 
MENT OF  TRA8ECUL/E 


COLLECTING  TUBE 
COM  VASCULOSI 


VASA  EFFERENTIA 


RETE  TESTIS  IN  MEDIASTINUM  TESTIS 
TUBE  OF  EPIDIDYMIS 


CC^  y^>  ■   VAS  ABERRANS 


vessels,  is  invested  by  a  tunica  albuginea  continuous  with  that  of  the  testicle 
proper,  but  of  much  greater  tenuity.  The  vasa  efferentia,  after  their  escape  from 
the  testicle  proper,  form  each  a  tube  about  six  to  eight  inches  in  length,  lined  with 
ciliated  epithelium  and  coiled  in  such  a  manner  as  to  assume  the  form  of  a  conical 
mass,  the  conus  vasculosus,  with  the  apex  towards  the  albuginea.  The  coni 
vasculosi  groujx'd  together  constitute  the  globus  major,  and  their  respective 
tubulrs  arL-  collected  by  a  single  canal,  the  tube  of  the  epididymis,  which  l)v  its 
comi»lcx  coils,  fifteen  to  twenty  feet  in  length,  makes  up  the  l)ody  and  globus  minor 
of  the  epididymis,  and  finally  terminates  in  the  free  portion  of  thi'  (luct,  the  vas 
deferens.  It  presents  near  its  termination  one  or  more  diverticula,  the  largest  and 
most  constant  of  which,  the  vas  aberrans  of  Haller,  ranges  from  an  inch  and  a 
half  to  fifteen  inches  in  length,  and  runs  up  between  the  l)ody  of  the  eindidymis 
and  the  commencement  of  the  vas  deferens.  The  tube  of  the  ejiididymis,  like  those 
of  the  coni  vasculosi,  is  lined  with  ciliated  epithelium,  but  its  walls  are  thick,  and 
contain  two  layers  of  unstriped  nmscular  fibres. 

Two  little  l)odies  of  some  morphologieal  interest  are  to  be  found  api>en(led  to 
the  testicle  ])ro]»er  and  the  globus  major.  The  less  constant  of  these,  known  as  the 
hydatid  of  Morgagni,  is  a  pedieulated  sac  from  one-eightli  to  one-third  of  an  inch 
in    length,  dilated  at    its  free  extremity  and  containing  a  clear  fiuid;  the  other, 


1028 


THE  MALE  REPRODUCTIVE   ORGANS 


rarely  absent,  lias  about  the  same  dimensions,  but  is  usually  sessile  and  flattened, 
and  may  be  subdivided  into  two  or  three  lobes.  It  is  believed  to  correspond  to  the 
upper  end  of  the  Falloijian  tube,  and  to  be  a  relic  of  the  Miillerian  duct  (page 
1057),  the  fatal  structure  from  which  are  developed  the  most  important  parts  of  the 
internal  genitals  of  the  female. 

Another  relic,  called  the  paradidymis,  or  organ  of  Giraldes,  probal)ly  derived 
from  the  Wolfhan  body  (page  1056),  is  seen  over  the  lowest  portion  of  the 
spermatic  cord  immediately  above  the  head  of  the  epididymis.  It  consists  of  coiled 
tubules,  blind  and  dilated  at  both  ends,  lying  beneath  the  visceral  layer  of  the 
funicular  portion  of  the  tunica  vaginalis.  It  usually  has  the  appearance  of  a  white 
or  yellowish  irregular  patch  about  one-fifth  of  an  inch  in  diameter.  Any  of  these 
embryonic  structures  may  give  rise  to  cystic  tumors,  and  the  aberrant  tubes  are 
probably  not  an  uncommon  source  of  origin  of  true  spermatic  cysts  containing 
seminal  fluid. 


Fig.  624.— Vasa  Deferentia  and  Vesicul^  Semixales.     (After  Sappey. 


EJACULATORY  DUCT 
SINUS  POOULARIS 


VERUMONTANUM 
ORIFICE  OF  EJACULATORY  DUCT 


AMPULLA  OF  VAS  DEFERENS 


UNION  OF  VESICULA  WITH  VAS 


EJACULATORY  DUCT  ENTERING 
PROSTATIC  FISSURE 


MEMBRANOUS  URETHRA 


VAS  DEFERENS 


ORIFICE  OF  SINUS  POCULARIS 
LOWER  END  OF  VERUMONTANUM 

VESICULA  SEMINALIS 


The  testicle  remains  small  until  the  period  of  pubert}'-,  and  then,  together  Avith 
the  penis  and  prostate,  it  begins  to  undergo  rapid  development;  but  in  some  cases  its 
evolution  is  arrested  before  it  has  attained  its  full  dimensions,  and  this  is  particu- 
larly liable  to  occur  when  its  descent  into  the  scrotum  has  been  intercepted,  or  when 
a  varicose  dilatation  of  its  veins  appears  before  adolescence.  In  old  age  it  usually 
loses  much  of  its  functional  activity,  but  this  is  not  invariably  the  case. 

The  VAS  DEFERENS  is  the  continuation  of  the  tube  of  the  epididymis,  and 
extends  from  the  globus  minor  to  the  prostatic  portion  of  the  urethra.  In  the  lower 
part  of  its  course  it  is  slender  and  tortuous,  but  it  l)ecomes  thicker  and  straighter  as 
it  ascends  along  the  })ack  of  the  epididymis  (testicular  stage),  and  attains  its  full 
size  before  it  reaches  the  top  of  the  organ.  From  this  point  it  is  the  principal 
element  of  the  spermatic  cord,  and  runs  upwards  almost  vertically  as  far  as  the 
external  inguinal  ring  (funicular  stage);  entering  the  inguinal  canal,  it  runs 
obliquely  outwards,  upwards,  and  slightly  backwards  to  the  internal  ring  (inguinal 
stage).  It  then  quits  the  associated  vessels  of  the  cord,  and,  winding  around  the 
origin  of  the  deep  epigastric  artery  to  the  inner  side  of  the  external  iliac  artery  and 


THE  TESTICLES 


1029 


in  fnjut  of  the  external  iliac  vein,  enters  the  i)elvis  (pelvic  stage)  close  to  the  ilio- 
pubic suture,  and  runs  downwards  and  backwards  over  the  side  of  the  bladder, 
crossing  it  on  the  vesical  side  of  the  oljliterated  hypogastric  artery  and  ureter,  to 
reach  the  side  of  the  posterior  wall  of  the  viscus.  Here  it  lies  between  tlie  bladder 
and  the  second  stage  of  the  rectum,  and,  becoming  enlarged  and  sacculated,  j)asses 
downwards  and  inwards  towards  the  base  of  the  prostate,  where  it  narrows  and  is 
joined  by  tlie  lower  end  of  the  vesicula  seniinalis.  The  common  tube  descends  as 
the  ejaculatory  duct,  to  pierce  the  prostatic  fissure  and  open  into  tlie  prostatic 
])ortion  of  the  urethra.  The  two  vasa  deferentia,  where  they  lie  in  front  of  the 
rectum,  are  separated  by  a  triangular  interval,  the  apex  of  which  is  formed  by  the 
ap})roximation  of  the  ejaculatory  ducts,  and  lies  immediately  above  the  ])rostate. 
The  wliole  of  the  pelvic  portion  of  the  vas  is  subperitoneal  except  near  its  termina- 
tion, where  it  is  invested  only  by  recto- vesical  fascia  and  an  extension  of  subperi- 
toneal tissue. 


Fig.  625.— Vas  Deferens  and  "Vesicula  Semixalis  dissected.     (After  Sappey.) 


SACCULI  Of  AMPULU  OF  VAS 


SACCULUS  


JUNCTION  OF  VAS  AND  VESICULA 
EJAGUUTORY  DUCT 


The  entire  length  of  the  vas  deferens  averages  about  sixteen  inches  (40  cm.),  of 
which  an  inch  and  a  quarter  (3  cm.)  may  be  allotted  to  the  testicular  stage,  three 
inches  to  the  funicular  stage,  an  inch  and  three-quarters  to  the  inguinal  stage,  and 
the  rest  to  the  pelvic  stage.  It  is  cylindrical  and  of  uniform  diameter  (about  one- 
tenth  of  an  inch)  in  its  funicular,  inguinal,  and  })elvic  stages  down  to  the  retrovesical 
portion,  and  its  walls  are  of  great  thickness,  about  one-twenty-fifth  of  an  inch 
(1  mm. ),  while  its  calibre  is  extremely  small.  It  is  here  composed  of  an  outer  cellu- 
lar coat  containing  vessels  and  smooth  muscular  fibres,  a  threefold  muscular  coat 
with  external  and  internal  longitudinal  and  middle  circular  layers,  and  a  mucous 
membrane  lined  with  cylindrical  ei)itlu'lium.  The  am]>ullated  retrovesical  ])ortion 
differs  from  the  rest  in  the  thinness  of  its  walls  and  in  its  sacculation,  and  in  these 
resp<'cts  approximates  to  the  vesicuhe  seminales  (fig.  G25). 

The  VESlCULiE  SEMINALES  are  two  diverticular  reservoirs  situated  between 
the  bladder  and  rectum  external  to  the  anipulhe  of  the  vasa  deferentia. 


1030  THE  MALE  REPRODUCTIVE  ORGANS 

Each  vesicula  is  of  somewhat  tvian.uular  form,  its  liroad  uj^per  extremity  lying  be- 
neath the  peritoneum,  its  apex  joining  the  vas  deferens  at  the  base  of  the  prostate. 
It  averages  about  two  and  a  quarter  inches  (6  cm.)  in  length  and  half  an  inch  (12 
mm. )  in  diameter  at  its  base.  It  is  lolnilated  on  the  surface,  and  on  dissection  is 
found  to  consist  of  a  central  tube  from  three  to  five  inches  (8-12  cm. )  in  length,  with 
two  or  more  short  lateral  liranches.  It  is  related  in  front  to  the  posterior  wall  of  the 
bladder,  and  by  its  upper  extremity  overlajts  the  ureter;  posteriurli/  it  is  covered  by  tbe 
recto-vesical  pouch  of  jieritoneum,  for  a  short  distance  above;  and  below  this  point  it 
lies  in  direct  contact  with  the  front  of  the  rectum,  and  external  to  the  ami)ulla  of 
tlie  vas  deferens.  It  becomes  constricted  at  its  junction  with  the  vas.  Structurally 
it  consists  of  a  fibrous  external  coat,  a  middle  muscular  coat,  and  an  internal  mucous 
membrane.  The  muscularis  is  arranged  in  tln-ee  layers,  the  inner  and  outer  of 
which  are  longitudinal  in  direction,  the  intermediate  fibres  ])eing  transverse. 

The  mucous  membrane  is  plicated,  sacculated,  yellowish-brown  in  colour,  and 
lined  with  cylindrical  epithelium.  It  is  invested,  together  with  the  ampulla  of  the 
vas,  by  a  kind  of  sheath  of  fil:)rous  tissue  and  by  a  layer  of  smooth  muscular  fibres 
which  is  probably  accessory  in  function  to  the  contractile  element  of  the  proper 
wall  of  the  tubes. 

The  EJACULATORY  DUCT,  formed  on  each  side  by  the  union  of  the  vas  def- 
erens and  vesicula  seminalis,  is  an  infundiljuliform  tube  about  f  of  an  inch  in 
length,  and  about  ^  of  an  inch  (3  nnn.)  in  width  above,  narrowing  to  ^  of  that 
size  below,  Avhile  the  lumen  near  its  opening  is  not  more  than  -^  of  an  inch 
(O-o  mm.)  in  diameter.  The  two  ducts  converge  slightly  as  they  descend,  and 
finally,  passing  behind  the  so-called  '  middle  lobe,'  the  hinder  part  of  the  basal 
muscular  ring  of  the  prostate  (page  1022),  pierce  the  prostatic  fissure  and  open  on 
to  the  verumontanum  on  either  side  of  the  orifice  of  the  sinus  pctcularis  (fig.  624). 

Vessels  and  Nerves  of  the  testicle  and  its  appendages. — The  testicle  is 
supplied  with  blood  by  the  spermatic  and  deferential  arteries,  the  two  vessels 
anastomosing  with  each  other  and  with  the  scrotal  arteries  at  tliie  lower  extremity 
of  the  gland.  The  corresponding  veins,  spermatic  and  deferential,  form  like  com- 
munications and  run  up  in  two  separate  groups.  The  spermatic  veins,  large  and 
imperfectly  valved,  spring  from  the  upper  part  of  the  testicle,  and,  running  in  front 
of  the  deferential  veins  around  the  spermatic  artery,  are  connected  to  each  other  by 
means  of  short  transverse  branches;  finally,  the  right  ends  in  the  vena  cava,  the 
left  in  the  left  renal  vein.  The  lymphatics  of  the  vas  and  testicle  accompany 
the  veins.  The  former  terminate  in  the  pelvic  iliac  glands,  the  latter  in  the  lumbar 
glands. 

The  free  anastomosis  between  the  deferential,  spermatic,  and  scrotal  blood- 
vessels explains  why  the  ligature  or  excision  of  the  spermatic  veins  and  artery  in 
varicocele  leaves  the  nutrition  of  the  testicle  unimpaired;  while  the  intercommuni- 
cation of  the  testicular  and  scrotal  blood  and  h^mph  vessels  behind  the  epididymis 
accounts  for  the  extension  of  inflammatory  affections  of  the  epididymis  to  the 
scrotal  integument. 

The  Nerves  of  the  testicle  come  from  the  aortic,  renal,  and  hypogastric 
plexuses. 

The  vesicula  seminalis  is  supplied  by  the  deferential,  inferior  vesical,  and  middle 
hfiemorrhoidal  arteries :  its  veins,  large  and  numerous,  form  a  kind  of  plexus 
which  receives  some  of  the  vesical  veins,  and  communicates  below  and  in  front 
with  the  prostatic  jilexus:  its  lymphatics  end  in  the  pelvic  glands,  and  the  nerves 
are  derived  from  the  hypogastric  plexus. 


SPERMATIC  CORD 

The  spermatic  cord  is  the  elongated  pedicle  of  the  testicle.  It  extends  from 
the  internal  inguinal  ring,  where  its  component  structures  are  collected  together, 
through  the  inguinal  canal,  and  into  the  scrotum  as  far  as  the  summit  of  the 
testicle.      Its  constituent  elements  are  as  follow  (fig.  626). 

1.  The  vas  deferens,  lying  with  the  deferential  vessels  posterior  to  the  other 
structures,  and  recognisable  by  its  cord-like  resistance  to  pressure. 


SPERMATIC  CORD— THE  REMS 


1031 


2.  The  spermatic  artery. 

3.  Tlic  spermatic  veins,  or  {(aiupinitorm  plexus,  surroiindini:  the  artery. 

4.  Lymphatics  running  with  the  veins. 

5.  Sympathetic  nerves  accompanying  tlie  artery. 

6.  The  processus  vaginalis,  occa-sionally  seen  as  a  thread-like  relic  of  the 
tube  of  connuunication  l)et\vccn  the  tunica  vaginalis  and  peritoneum.  It  is  fre- 
quently patent  for  a  short  distance  near  the  internal  inguinal  ring,  and  probably 
accounts  in  great  })art  for  the  insidious  development  of  hernial  protrusions  in  this 
region. 

Flo.  626.- Skctikx  ok  tiik  Si-kumatic  Cokd.     (After  Henlc.) 


Small  artery 
Artery  of  vas 

Internal  eremaster 


VAS  DEFERENS  :- 

Mucous  membrane 
Internal  muscular  coat 

Middle  muscular  coat 

External  muscular  coat 


Internal  cremaster 
Deferential  vessels 


7.  The  internal  cremaster  of  Henle.  Scattered  l>inulles  of  smooth  muscular 
fibres,  said  to  re}trcsent  the  inverted  lateral  bands  of  the  gubernaculum  testis. 

8.  Fat  and  connective  tissue,  continuous  above  with  the  subperitoneal  planes 
of  fascia.  Inguinal  or  scrotal  lipomata  or  fibromata  may  take  origin  from  these 
elements  and  may  simulate  true  hernias. 

In  the  scrotum  these  various  structures  are  invested  by  coverings  identical 
with  those  of  tlie  testicle. 


THE   PEXIS 

The  penis  is  composed  of  three  rod-like  segments  of  erectile  tissue,  firmly 
united  together  and  invested  1)V  a  sheath  composed  of  integument,  dartos,  and 
fascia  (fig.  627). 

Of  these  three  erectile  segments,  two.  the  corpora  cavernosa,  are  placed 
side  by  side  above  or  dorsally;  the  third,  the  corpus  spongiosum,  is  perforated 
in  the  whole  length  by  the  urethral  canal,  and  lii's  on  tlir  ventral  aspect  of  the 
former,  except  where  it  expands  distallv  to  form  the  free  end  of  the  organ 
(fig.  B28). 

The  penis  as  a  whole  may  be  divided  into  a  root,  a  body,  and  a  terminal 
enlargement  or  glans;  the  root  is  attached  to  the  symphysis  and  pubic  arch;  the 
body,  prismatic,  with  rounded  angles  in  section,  forms  the  greater  part  of  the  free 
])ortion  of  the  organ;  and  the  glans  is  a  heart-shaped  expansion,  more  developed 
on  its  dorsal  than  on  its  ventral  aspect,  and  presenting  the  urethral  orifice  at  its 
distal  extremity.  The  body  and  glans  are  separated  by  a  constriction  called  the 
neck. 

The  coverings  of  the  penis  are  continuous  with  those  of  the  testicl(\  The 
skin,  like  that  of  the  scrotum,  is  pigmented  and  highly  elastic,  and  unlike  the  skin 


1032 


THE  MALE  REPRODUCTIVE  ORGANS 


over  the  rest  of  the  body,  is  devoid  of  smooth  muscular  fi})res  and  subcutaneous 
fat.  It  contains  large  sebaceous  glands,  which  in  the  neighliourhood  of  the  neck  of 
the  organ  secrete  a  whitish  fatty  odourous  substance,  the  smegma  praeputii.  It 
moves  freely  upon  the  subjacent  parts  except  over  the  glans,  where  it  is  tirmly 
adherent.  At  the  neck  it  becomes  peculiarly  redundant,  and  forms  a  fold,  the 
prepuce,  which  more  or  less  completely  conceals  the  glans.  The  deei)er  layer  of 
the  duplicature,  which  is  turned  towards  and  is  continuous  with  the  skin  of  the 
glans,  is  sometimes  termed  'mucous  membrane,'  which  it  resembles  only  in  the 
absence  of  hairs  and  sudoriparous  glands.  A  small  median  plication,  the  fraenum 
praeputii,  extends  from  the  prepuce  to  the  lower  surface  of  the  glans.  This 
contains  vessels  of  some  size,  and,  if  ruptured,  may  give  rise  to  considerable  loss  of 
blood.  The  preputial  orifice  is  usually  large  enough  to  allow  the  easy  retraction  of 
the  fold,  but  sometimes  is  congenitally  constricted,  and  prevents  the  exposure  of 
the  glans  (phimosis).  Owing  to  the  composition  of  the  prepuce  by  two  layers  of 
integument,  the  removal  of  a  complete  ring  as  in  the  ordinary  operation  for  phimosis 
impedes  the  passage  of  the  lymph  and  blood  from  the  portion  left  attached  to  the 
glans,  and  hence  considerable  infiltration  of  this  part  may  result. 

The  dartos  is  continuous  with  the  dartos  tissue  (page  1023)  of  the  scrotum,  and 
consists  of  smooth  muscle,  the  fibres  of  which  are  for  the  most  part  disposed  longi- 
tudinally.    It  enters  into  the  formation  of  the  prepuce,  and  according  to  Sappey 


Fig.  627. — Transverse  Section  through  the  Body  of  the  Penis. 

Superficial  dorsal  vein  of  penis 

fDeep  dorsal  vein 
Dorsal  artery 

SKIN 

DARTOS 

SEPTUM  PECTINIFORME 

CORPUS  CAVERNOSUM 

Fibrous  sheath   of  penis 

Vessels 


TUNICA  ALBUGINEA 


TUNICA  ALBUGINEA 


Artery 


Artery 
URETHRA 
CORPUS  SPONGIOSUM 


forms  a  kind  of  sphincter  around  the  preputial  orifice.  Beneath  the  dartos  is  a 
loose  elastic  connective-tissue  layer  containing  the  superficial  vessels  and  nerves 
of  the  penis,  and  very  liable  to  infiltration  in  inflammatory  or  dropsical  conditions 
and  in  urinary  extravasation.  Beneath  this  lies  the  fascial  sheath  of  the  penis,  a 
complete  and  highly  elastic  tunic  investing  the  entire  organ  as  far  as  the  base  of  the 
glans,  where  it  fuses  Avith  the  integument.  It  is  also  adherent  both  to  the  skin  and 
to  the  corjuis  spongiosum  along  the  ventral  raphe,  and  it  covers  the  deep  dorsal 
vessels  and  nerves  and  the  lateral  tributaries  Avhich  converge  to  the  dorsal  vein. 
This  sheath,  aided  by  the  dartos  and  certain  processes  from  the  bulbo-cavernosi  and 
ischio-cavernosi  muscles,  compresses  the  veins  of  the  penis. 

The  suspensory  ligament  of  the  penis  is  a  strong  band  of  fibrous  tissue  which 
passes  from  the  front  of  the  symphysis  to  the  subjacent  portion  of  the  organ,  blend- 
ing Avith  the  fascial  sheath  in  the  middle  line  and  at  the  sides,  and  continued  into 
the  septum  scroti  below.  The  angle  of  the  penis  corresponds  to  the  most  ante- 
rior point  of  sus{)ension  to  the  symphysis. 

The  corpora  cavernosa  ct)iistitute  the  dorsal  and  larger  part  of  the  penis. 
They  are  closely  united  in  the  greater  part  of  their  extent,  but  separate  a  short  dis- 
tance in  front  and  diverge  somewhat  widely  behind.  The  ])osterior  extremity  of 
each,  called  the  crus  penis,  at  first  enlarges  slightly,  but  tapers  as  it  approaches 
the  subpubic  arch;  then,  becoming  tendinous  and  somewhat  flattened,  is  strongly 


THE  PENIS 


1033 


attached  to  the  iscliio-jnibic  rami;  and  tlie  distal  end,  pointed  somewhat  lik(i  the 
tip  of  a  cigar,  is  plunged  into  the  substance  of  the  glans  (tig.  G28).  The  entire 
length  of  the  corpus  eavernosum  averages  about  six  inches,  and  its  Ijreadth  about 
half  an  inch,  l)ut  it  increases  in  size  i)y  one-third  or  more  when  its  vascular  spaces 
are  fully  distended. 

In  structure  it  consists  of  a  sponge-like  erectile  tissue  invested  by  a  strong  sheath 
or  tunica  albuginea.  The  sheath  is  about  a  line  in  thickness,  white,  remarkably 
tough,  and  consists  of  two  laminie,  an  external,  of  longitudinal  lil)r('s  common  to 
both  corpora  cavernosa;  and  an  internal,  of  circular  fibres  surrounding  each  corjnis 
and  forming  a  mesial  septum  pectiniforme  where  ttie  two  corpora  cavernosa  come 
into  contact.  The  framework  of  the  cavernous  structure  is  formed  by  a  reticular 
arrangement  of  tibro-nmscular  trabecular  bands,  starting  from  the  inner  surface  of 
tbe  all)Uginea  and  becoming  more  slender  as  they  approach  the  axis  of  the  body. 
The  branches  of  the  supplying  artery  run  in  the  trabecule  and  terminate  by  open- 
ing into  the  anastomosing  intertral)ecular  spaces  which  represent  the  widely  dilated 
capillaries  of  the  organ. 

The  corpus  spongiosum  lies  in  the  middle  line  and  below  the  united  corpora 
cavernosa.  Unlike  the  latter  it  has  no  direct  attachment  to  the  ])elvic  l)ones,  but 
terminates  at  each  end  in  a  l>ulbous  expansion.  It  may  be  divided  into  a  glans,  a 
l)ody,  and  a  bulb. 

The  anterior  enlargement,  or  glans,  is  somewhat  heart-shaped,  its  l>ase  extend- 
ing much  farther  over  the  dorsal  than  over  the  ventral  asi)eet  of  the  corpora  caver- 

FiG.  628.— Transverse  Section  of  the  Penis  through  the  Base  of  the  Glans. 


CORPUS  SPONGIOSUM  (GUNS) 


DISTAL  EXTREMITY  OF  CORPUS 
CAVERNOSUM 


CORPUS   SPONGIOSUM        Integument 


nosa,  and  showing  a  distinct  indication  of  division  into  two  lateral  lobes  in  the  latter 
situation.  The  most  prominent  i)art  of  the  base  is  called  the  corona  glandis,  and 
the  groove  behind  this  is  the  neck  of  the  penis  or  balano-preputial  furrow.  At  its 
tip  it  presents  a  vertical  fissure  about  one-third  of  an  inch  in  length,  the  external 
urinary  meatus  or  outlet  of  the  urethra. 

The  glans  is  composed  of  erectile  tissue  with  coarse  tral)ecula^,  and  is  covered 
with  a  firmly  adherent  layer  of  skin  continuous  Avith  the  inner  layer  of  the  prepuce. 
Its  cajiacity  for  vascular  engorgement  is  much  less  than  that  of  the  cor])Us  eaverno- 
sum or  the  rest  of  the  corpus  spongiosum,  and  it  does  not  attain  a  like  degree  of 
hardness  during  erection. 

The  structural  continuity  of  the  glans  with  tbe  cori)US  spongiosum  is  })ro])al)ly 
not  morphological.  The  recent  investigations  of  Retterer  indicate  that  the  greater 
I)ortion  of  the  glans  is  developed  sejjarately  as  a  part  of  the  cutaneous  and  fibrous 
envelope  of  the  penis,  and  becomes  erectile  as  a  later  change. 

The  body  of  the  corpus  spongiosum  is  cylindrical,  uniform  in  diameter,  and 
traversed  axially  in  its  whole  length  by  the  urethra  ;  it  is  lodged  above  in  a  groove 
Ix'tween  the  two  corj)ora  caviM'nosa,  while  its  ventral  aspect  is  subcutaneous  except 
where  it  corresponds  t<i  the  attachment  of  the  scrotum.  .Structurally  it  is  provided 
with  a  thin  albuginea,  between  which  and  tlie  urethra  lies  a  narrow  layer  of  erectile 
tissue. 

The  bulb  is  fi^rmed  l)y  an  expansion  of  the  erectile  structure,  and  the  jjortion 
of  the  urethra  bv  which  it  is  traversed  undergoes  a  well-marked  dilatation,  and  lies 


1034 


THE  MALE  REPRODUCTIVE   ORGANS 


nearer  its  upper  than  its  lower  surface.  It  is  about  an  inch  and  a  half  in  length, 
and  its  greatest  width  is  about  three-quarters  of  an  inch.  It  is  surrounded  by  the 
bulbo-cavernosi  muscles,  the  greater  part  of  the  filjres  of  Avhich  pass  between  it  and 
the  corpora  cavernosa  to  blend  together  in  the  middle  line  ;  and  it  rests  posteriorly 
ngainst  the  superficial  triangular  ligament  about  half  an  inch  in  front  of  the  anus. 
It  is  liable  to  considerable  enlargement  after  middle  age. 

Muscles. — The  muscles  of  the  penis  arc  three  on  each  side — the  ischio- 
cavernosus,  the  bull)o-cavernosus,  and  the  superficial  transversus  perinaei  (fig.  629). 

The  ischio-cavernosus  (erector  penis)  arises  from  the  inner  surface  of  the 
tuberosity  and  ramus  of  the  is(?hium,  from  the  pubic  ramus,  and  from  the  adjacent 
root  of  the  crus  penis,  and  is  inserted  into  the  surface  of  the  tunica  albuginea  of 

Fig.  629. — The  Male  Perix.eum.     (Modified  from  Hirschfeld  and  Leveille.) 

BULBO-CAVERNOSUS 

Superfloial  triangular  ligament 

ISCHIO-CAVERNOSUS 


Muscles  of  thigh 


INFEBIOR  PUDESDAL  NER\ 
SUPERFICIAL  PERINEAL  NERVE 

INFERIOR  HEMORRHOIDAL  NERVE 
CUTANEOUS  BRANCH  OF  FOURTH  SACRAL 


Gluteus  maximuB 

TUBEROSITY  OF  ISCHIUM 
Great  sacro-seiatie  ligament 
Levator  ani 
Superficial  transversus  perinaei 


Sphincter  ani 


the  corpus  cavernosum  near  the  point  of  attachment  of  the  suspensory  ligament. 
A  slip,  the  compressor  venae  dorsalis,  is  occasionally  detached  from  its  more 
distal  portion,  and  becomes  inserted  into  the  fascial  sheath  of  the  penis  over  the 
dorsal  vessels,  or  may  l)lend  with  its  fellow  in  a  narrow  tendon  in  this  situation. 

The  bulbo-cavernosus  (accelerator  urinae)  arises  from  a  median  raphe 
which  extends  froin  tlie  anterior  extremity  of  the  sphincter  ani  along  the  whole 
length  of  the  bulb  as  far  as  the  level  of  the  symphysis.  A  few  of  its  more  posterior 
fibres  pass  outwards  to  become  inserted  into  the  superficial  triangular  ligament  and 
into  the  bulb,  and  a  bundle  of  its  most  anterior  fibres,  muscle  of  Houston,  may, 
like  the  similar  sli])  from  the  ischio-cavernosus,  form  a  sling  around  the  corpora 
cavernosa  and  become  attached  to  the  fascial  sheath  of  the  penis,  or  it  may  be 
inserted  into  the  side  of  the  corpus  cavernosum  itself.      In  the  former  case  it  acts  as 


I 


PENIS  AND    URETHRA'  1035 

a  compressor  of  the  dorsal  vein.  The  rest  of  the  fil^res  pass  around  the  Vjulb  to 
become  lost  in  the  connective  tissue  on  the  dorsal  aspect  of  the  latter,  between  it 
and  the  corpora  cavernosa;  the  two  muscles  thus  practically  encircle  the  bullj,  and 
act  as  an  annular  sphincter  u]>on  the  contained  portion  of  the  urethra.  It  is  often 
joined  by  til)res  from  the  sphincter  ani  and  deej)  transversus  perina-i. 

The  superficial  transversus  perinaei  is  the  most  variable  of  all  the  perinatal 
muscles.  It  usually  arises  from  the  inner  surface  of  the  tuberosity  and  ramus  of 
the  ischium,  l)lendinji;  with  the  ori<!;in  of  the  ischio-cavernosus,  and  passes  inwards 
and  forwards  to  its  insertion  into  the  tendinous  centre  of  the  perineum,  interlacing 
with  the  posterior  fibres  of  origin  of  the  bulbo-cavernosus.  Some  of  its  fibres  may 
blend  with  those  of  the  sphincter  ani  and  levator  ani. 

These  three  pairs  of  muscles  possess  each  a  thin  fascial  sheath,  and  lie  in  the 
superficial  perinaeal  interspace  between  the  fascia  of  Colics  and  the  superficial 
triangular  ligament.  They  are  supplied  by  branches  of  the  deep  division  of  the 
sujjerticial  perineal  nerves  and  vessels. 

The  action  of  the  penile  muscles  is  not  very  ol)vious.  The  compressores  venae 
dorsalis  when  present  may  aid  in  erection  by  impeding  tlie  retvn-n  of  venous  blood 
from  the  organ,  but  there  is  no  reason  to  believe  that  any  disadvantage  attaches  to 
their  absence.  The  bulbo-cavernosus,  with  its  fellow,  is.  however,  of  value  as  a 
compressor  of  the  bulbous  portion  of  the  urethra,  and  thus  assists  in  the  ejaculation 
of  the  semen,  continuing  the  action  of  the  ejaculatory  fibres  of  the  prostate  and  of 
the  deep  transversus  perinaei;  and  it  may  also  be  of  service  in  expelling  the  last 
drops  of  the  urine.  The  compression  of  the  vessels  of  the  bulb  favours  the 
engorgement  of  the  rest  of  the  corpus  spongiosum. 

The  ischio-cavernosus  in  the  absence  of  its  dorsal  fasciculus  can  scarcely  justify 
its  older  name  of  erector  penis,  but  it  appears  to  have  the  power  of  impressing 
voluntary  movements  upon  the  turgid  organ.  The  superficial  transversus  perinaei 
is  accessory  to  the  bulbo-cavernosus,  fixing  the  raphe  from  which  its  fibres  arise,  and 
it  adds  slightly  to  the  strength  of  the  muscular  floor  of  the  jDclvis. 

Vessels  and  Nerves  of  the  Penis. 

Artery. — The  envelopes  of  the  penis  are  sujiplied  by  the  external  pudic,  the 
superficial  perinaeal,  and  the  dorsal  artery;  the  first  from  the  femoral,  the  others 
from  the  internal  pudic.  The  corpora  cavernosa  are  supplied  by  the  cavernous 
branch  of  the  pudic;  the  corpus  spongiosum  by  the  special  artery  of  the  bulb 
(internal  pudic)  and  the  dorsal  artery. 

Veins. — The  veins  of  the  coverings  of  the  penis  end  in  one  or  two  superficial 
dorsal  veins  which  run  in  the  connective  tissue  layer  between  the  dartos  and  fascial 
sheath,  and  end  in  the  long  saphenous  and  femoral  veins.  The  deep  veins  of  the 
corpora  cavernosa  and  corpus  spongiosum  terminate  partly  in  the  plexus  of 
Santorini  (chiefly  through  the  deep  dorsal  vein),  and  partly  in  the  internal  pudic. 
They  communicate  freely  with  each  other  and  with  the  superficial  veins. 

Lymphatics. — The  lym])hatics  run  with  the  veins,  those  of  the  coverings  being 
collected  by  superficial  dorsal  trunks  which  pass  to  the  inguinal  glands.  The  deep 
lymphatics  from  the  corpora  cavernosa  and  corpus  spongiosmii  for  the  most  ])art 
join  a  dorsal  cord  which  runs  with  the  deep  dorsal  vein  to  end  in  the  inguinal 
glands;  a  few  probably  reach  the  pelvic  and  lumbar  glands. 

Nerves. — The  integumentary  structures  are  supplied  by  the  genital  1)ranch  of  the 
genito-crural  and  the  superficial  perina'al  branches  of  the  pudic.  The  erectile  bodies 
receive  filaments  from  the  dorsal  nerve  of  the  penis,  the  suj^erficial  perina?al,  and 
the  hypogastric  plexus. 

THE   URETHRA 

The  urethra  is  the  mucous  canal  extending  from  the  bladder  to  the  extremity 
of  the  glans  penis.  In  its  course  it  j)ierces  the  ]>rostate  from  l)ase  to  ajiex.  the  deep 
and  superficial  triangular  ligaments  with  the  intervening  comjiressor  urethric,  and 
the  whole  length  of  the  corpus  spongiosum.  It  may  hence  be  divided  into  three 
segments: — (1)  Prostatic;  (2)  membranous  (the  ])ortion  lying  in  the  space  between 
the  two  transverse  ligaments);  and  (3)  spongy  (fig.  630). 

The   prostatic   portion    runs   almost  vertically  downwards   from    the   internal 


1036 


THE  MALE  REPRODUCTIVE   ORGANS 


urinary  meatus,  but  witli  a  sliglit  forward  inclination  l)elow;  the  membranous 
portion  and  the  posterior  i)art  of  the  spontrv  portion  as  far  as  the  anterior  border 
of  tlie  suspensory  Hgament  of  the  penis  describe  a  curve  beneath  the  symphysis; 
lastly,  the  jjortion  of  the  spongy  urethra,  beyond  the  penile  angle,  follows"  the 
direction  of  the  pendent  portion  of  the  penis  and  necessarily  follows  the  movements 
of  that  organ. 


Fig.  (530.— The  Male  Urethra,  cleft  dorsally  to  show  Ventral  Mrcous  "Wall. 

URETER -V 


Plica  uretica 

SECTION  OF  BLADDER 


INTERNAL  URINARY  MEATUS 


PROSTATIC  SINUS  WITH  OPENING  OF 

PROSTATIC   GLANDS  CwiKj  a*'^ 

SINUS  POCULARIS  ■  Mj  H.^ 

FOLLICULAR  GLANDS  OF  DORSAL  WALL 


COWPER'S  GLAND 


SEPTUM  PECTINIFORME 


THIN  LAYER  OF  CORPUS  SPONGIOSUM 
ORIFICE  OF  COWPER'S  GLAND 


Albuginea  of  corpora  cavernosa 


SECTION  OF  PROSTATE 
VERUMONTANUM 
EJACULATORY  DUCT 
PROSTATIC  GLANDS 


MEMBRANOUS  URETHRA 


SECTION  OF  CORPUS  CAVERNOSUM 


BULBOUS  PORTION  OF  URETHRA 


Mucous  membrane 


FOSSA  NAVICULARIS 


EXTERNAL  URINARY  MEATUS 


PREPUCE 
GLANS  PENIS 


Its  average  length  is  still  variously  stated  by  different  authorities,  but  the  inves- 
tigations of  Cazenave  and  Sappey,  confirmed  as  they  are  by  the  frozen  sections  of 
Braune  and  others,  set  the  matter  at  rest  so  far  as  the  pliysiological  condition  is 
concerned.  In  the  ordinary  relaxed  state  of  the  penis  the  distance  l)etween  the 
internal  and  external  meatus  does  not  usually  exceed  six  inches  and  a  half  (16 
CHL),  and  maybe  less  than  this  when  the  organ  is  contracted  to  its  mininunu 


THE   URETHRA  1037 

degree.  But  under  the  test  of  catheterism  the  length  of  the  canal  is  undoubtedly 
greater,  and  may  reach  seven  or  eight  inches  (18-20  cm.)  or  even  more,  owing  to 
the  traction  upon  the  penis  which  acconipunies  the  operation.  The  canal  mav  he 
greatly  lengthened  also  by  senile  hypertrophy  of  the  prostate,  which  carries'  the 
internal  meatus  ui)wards  towards  the  level  of  tiie  top  of  the  symphysis. 

The  diameters  (^f  the  passage  are  scarcely  ca))ableof  accurati!  measurement.  In 
the  ordinary  condition  it  is  rej>resented  by  a  lissure,  and  its  limits  of  safe  dilata- 
bility  can  only  be  api)roximately  "calculated.  Otis's  investigations  show  that 
these  limits  are  wider  tlian  was  formerly  believed  to  be  the  case,  and  he  has 
endeavoured  to  establisli  as  a  law  that  there  is  a  ratio  l^etween  the  maximum  circum- 
ference of  the  canal  and  that  of  the  penis,  of  four  to  nine.  Thus  a  penis  having 
in  its  ordinary  state  a  circumference  of  thirty-six  lines  should  possess  a  urethra 
capable  of  admitting  an  instrument  of  sixteen  lines.  The  sources  of  fallacy  in 
such  an  observation  are  not  inconsiderable,  but  they  do  not  destroy  its  value  as  a 
practical  guide  to  the  surgeon. 

The  prostatic  portion  is  about  an  inch  and  a  quarter  (3  cm.)  in  length,  wider 
in  the  middle  than  at  the  two  extremities,  and  almost  perpendicular  in  direction, 
with  a  slight  inclination  downwards  and  forwards  at  its  lower  end.  Its  anterior 
wall  is  concave  both  in  longitudinal  and  transverse  sections,  and  is  studded  with 
the  orifices  of  small  mucous  follicles;  the  posterior  w^all  presents  a  longitudinal 
ridge  called  the  colliculus  seminalis  or  verumontanum,  highest  near  the  middle 
and  gradually  diminishing  above  and  below.  A  little  above  the  centre  of  the  col- 
liculus may  be  seen  a  rather  large  opening  Avhich  leads  to  a  cul-de-sac  of  especial 
interest  for  the  morphologist,  the  sinus  pocularis  or  uterus  masculinus,  and  on 
the  lateral  margins  of  the  orifice  of  the  sinus  are  seen  two  small  ])uucta,  one  on 
each  side,  the  openings  of  the  ejaculatory  ducts.  The  sinus  pocularis  and  ducts 
may  be  traced  upwards  and  backwards  through  the  prostatic  cleft  and  behind  the 
sphincteric  fibres  which  constitute  the  prostatic  bar  or  middle  lobe  of  the  prostate. 

In  consequence  of  the  presence  of  the  colliculus  the  urethral  fissure  appears  on 
horizontal  section  as  a  U-shaped  curve  with  forward  convexity.  The  recesses  cor- 
responding to  the  extremities  of  the  U  are  sometimes  called  the  prostatic  sinuses, 
and  into  these  open  the  orifices  of  the  posterior  and  lateral  prostatic  glands. 

The  mucous  membrane  of  the  prostatic  urethra  is  lined  with  a  laminated  epithe- 
lium. Beneath  this  is  a  layer  of  erectile  tissue  which  constitutes  the  princi])al 
eleuicnt  of  the  colliculus,  and  is  in  turn  supported  by  a  layer  of  longitudinal  muscle. 

The  sinus  pocularis  is  believed  to  be  the  homologue  of  the  uterus.  It  is  about 
half  an  inch  in  length,  and  terminates  1)y  a  blind,  slightly  dilated  extremity.  Its 
walls  consist  of  connective  tissue  intermingled  with  smootli  muscular  fibres,  and 
covered  with  laminated  epithelium.  It  contains  a  few  simple  or  compound  glands, 
in  which  small  concretions  are  occasionally  found. 

The  membranous  portion,  bounded  above  and  below  by  the  superior  and 
inferior  triangular  ligaments,  is  about  half  an  inch  (12  mm.)  in  length;  it  is 
inclineil  downwards  and  somewhat  forwards,  and  lies  aliout  an  inch  (25  nnn.)  be- 
hind the  subpubic  ligament,  from  which  it  is  separated  l>y  the  nniscular  fibres  of 
the  dee])  transversus  jK-riuici  and  a  plexus  of  veins.  It  is  closely  related  on  either 
side  to  Cowper's  glands. 

The  mncovs  membrane  resembles  that  of  the  i)rostatic  urethra  in  its  epithelium 
and  erectile  layer  and  muscularis,  but  surrounding  these  structures  is  a  strong  annu- 
lar band  of  unstriped  muscle  continuous  with  thefil)res  of  the  prostate  and  forming 
a  sphincter  of  considerable  power.  This  in  turn  is  supi)orted  by  the  striated  fibres 
of  the  deep  transversus  perinsei.  The  glands  of  the  mucous  mend)rane,  simple  and 
racemose,  form  suite  with  tiiose  of  the  anterior  wall  of  the  prostatic  canal. 

The  spongy  portion  extending  to  the  extremity  of  the  penis  presents  two  dila- 
tations with  an  intermediate  ])ortion  of  narrow  but  uniform  dimensions.  The  ]tos- 
terior  expansion  (  pars  bulbosa  i  lies  in  the  bulb,  and  is  about  an  inch  (25  nnn.) 
in  length;  the  anterior  (fossa  navicularis)  is  of  nearly  the  same  extent,  and  is 
situated  within  the  glans.  The  penile  angle,  formed  wliere  the  flaccid  organ  falls 
from  the  point  of  suspension  at  tlie  piiKic  region,  lies  about  two  inches  (5  cm.)  in 
front  of  the  superficial  triangular  ligament;  and  the  portion  of  the  canal  behind  this 
is  almost  horizontal  in  direction,  but  with  a  slight  upward  concavity  (fig.  617). 


1038  THE  FEMALE  REPRODVCTIVE  ORGAXS 

The  miicons  memhrane  of  tlie  spongy  urethra  contains  a  large  quantity  of  elastic 
tissue  and  is  lined  hv  a  laminated  epithelium,  the  superficial  cells  of  which  are 
prismatic  in  ft>rm.  wlnle  the  (lee])er  lavers  cover  in  rows  of  more  or  less  longitudi- 
nallv  .lisposed  papilhe.  At  its  distal  extremity  tlie  integumental  covering  of  the 
glans  is  inflected  for  about  a  quarter  of  an  incli  ( (>  mm.),  the  line  of  demarcation 
between  the  cutaneous  and  mucous  structures  being  well  defined.  The  external 
meatus  is  represented  bv  a  vertical  slit  about  a  quarter  of  an  inch  ((imm.)  in 
length,  and  is  the  least  dilatable  part  of  the  canal;  hence  in  urethral  operations  it  is 
sometimes  necessary  to  enlarge  it  by  incision. 

An  examinatir»n*  of  the  mucous  surface  will  show  a  number  of  orifices  arranged 
in  three  longitudinal  rows  extending  along  the  dorsal  wall,  and  leading  to  short 
tul>ular  depressions  which  run  in  a  l)ackward  direction  (towards  the  bladder)  and 
are  called  the  lacun;v  of  Morgayni.  One  of  these,  termed  the  larvna  magna  or  sinus 
of  Giierin,  situated  in  the  mesial  line  about  an  inch  from  the  external  meatus,  is  of 
large  size,  and  may  arrest  the  point  of  an  instrument  during  catheterism.  It  is 
bounded  bv  a  little  fold  of  mucous  membrane,  the  valvule  of  Guerin,  and  may 
attain  a  depth  of  one-third  of  an  inch  (8  mm.).  In  addition  to  these  are  niany 
simple  and  compound  mucous  glands,  such  as  appear  in  the  prostatic  portion  of 
the  canal;  and  the  ducts  of  Cowper's  glands  open  into  the  anterior  portion  of  the 
bulb  on  the  ventral  wall. 

The  nuiscular  coat  consists  chiefly  of  longitudinal  fibres  continuous  with  those 
of  the  bladder,  but  a  circular  layer  prolonged  from  the  sphincteric  fibres  of  the 
membranous  urethra  extends  as  an  outer  layer  over  the  bulbous  portion  of  the 
canal  gradually  disap]iearing  beyond  this  point. 

As  alreadv  mentioned,  the  collapsed  urethra  is  represented  by  a  fissure.  This 
in  the  glans  penis  is  vertical  in  direction.  A  short  horizontal  branch  is  superadded 
at  the  upper  end  of  the  fossa  navicularis,  giving  the  fissure  the  aspect  of  an  in- 
verted T.  Above  this  point  the  horizontal  limb  progressively  elongates,  while  the 
vertical  limb  shortens  until  the  former  alone  is  left,  and  the  rest  of  the  spongy 
urethra  is  represented  by  a  transverse  fissure.  In  the  membranous  segment  the 
fissure  is  usually  stellate,  while  in  the  prostatic  region  the  presence  of  the  collicu- 
lus  gives  it  the  U-like  form  already  described.  This  progressive  change  of  shape 
involves  a  kind  of  rifling  of  the  tube,  and  prol)ably  accounts  for  the  spiral  form  of 
the  normal  stream  of  urine. 

The  muscular  tissue  of  the  urethra  appears  to  be  capable  of  a  peculiar  vermicu- 
lar contraction  by  which  a  catheter  left  within  the  urethra  is  gradually  expelled, 
and  an  example  is  known  in  which  an  elastic  instrument  insecurel}'  tied  in  situ 
found  its  way,  in  the  reverse  direction,  into  the  bladder,  and  formed  the  nucleus 
of  a  calculus. 

The  female  urethra  is  described  on  page  1041. 


THE  FEMALE   ORGAXS    OF    GENERATION 

The  female  genitals  may  be  divided  into  (1)  an  external  part,  the  vulva, 
representative  of  structures  found  in  a  more  highly  develoiKni  condition  in  the 
male;  (2)  a  vaginal  passage,  the  cavity  of  which  appears  as  a  fissure  in  its  ordinary 
c(Mulition,  but  is  ca])able  of  very  great  dilatation;  and  (3)  an  internal  ai)paratus 
comiu-ising  the  organs  of  ovulation  (ovaries)  with  their  ducts,  and  a  musculo- 
nuicous  sac  (uterus)  in  Mhich  the  ovum  undergoes  development,  and  by  which  the 
fcetus  is  ultimately  expelled.     The  vagina  and  internal  organs  are  intra-j^elvic. 

The  VULVA  consists  of  a  ]iair  of  integumentary  folds,  the  labia  majora;  two 
smaller  folds,  the  labia  minora ;  a  small  ])enile  appendage,  the  clitoris  ;  and  a 
short   passage,   the  vestibule,  leading  to  the  vaginal   orifice.     The  vestibule  is 


Tiih:  vri.vA 


1089 


flanked  on  cither  sidi^  hy  an  erertilc  l»)(ly,  tlie  hulhiis  vestibuli,  and  piereed  in  tlie 
middle  line  l»y  the  urethra  (fig.  031,  632). 

Till'  labia  majora  correspond  morphologically  to  the  scrotum  in  the  male. 
Thcv  are  two  folds  of  integument  ahout  thi'ce  inches  in  length,  continuous  ahove 
the  symphysis,  witli  an  eiidncnce  called  the  mons  Veneris,  and  meeting  helo^v  in 
a  posterior  commissure,  or  fourchette,  ahout  an  inch  in  front  of  the  anus.  Each 
laliium  has  two  surface's:  an  outer,  })igmcntcd  and  (;oyered  with  strong  cris])  liairs; 
an  inner,  in  contact  with  its  fellow,  smooth,  jtresenting  only  rudimentary  hairs, 
hut  hcset  with  large  sehaccous  follicles.  'V\\v.  fissure  hctween  the  two  lahia,  called 
the  rima  pudendi,  is  horizontally  placed  in  the  erect  posture. 

The  structures  forming  the  lal)ia  resemble  those  of  the  scrotum,  hut  the  dartos 
is  imperfectly  developed,  and  each  labium  contains  a  well-defined  encapsulated 
subcutaneous  mass  of  fat,  of  somewhat  ovoid  shape,  which  blends  above  with  the 


Fio.  <):{!.— The  ^xteunal  Genhals  ok  the  Fejiai.k. 


GUNS  CUTORIDIS 


MEATUS  URINARIUS  IN 
VESTIBULAR  SPACE 


CORPUS  CLITORIDIS 


LABIUM   MAJUS 


LABIUM   MINUS 


distal  extremity  of  the  round  ligament.  A  similar  mass  is  occasionally  found  in  the 
male  scrotum  as  a  fatty  tumour  of  the  cord,  and  may  simulate  an  inguinal  hernia. 

The  labia  minora,  or  nymphae,  are  folds  differing  from  the  lid)ia  majora  in 
their  relatively  small  size;  and  in  the  absence  of  hairs  and  fat.  The  two  ])lications 
unite  above,  embracing  the  clitoris  and  forming  the  praeputium  clitoridis  ;  below, 
they  diverge  and  terminate  opjiosite  to  or  a  little  behind  the  middh'  of  the  rima 
genitalis.  They  are  smooth  and  hairless  on  the  surface,  usually  of  a  ]iale  rose  colour, 
and  their  free  border,  whi(Oi  projects  for  a  very  varial)le  distance,  is  convex  and 
often  crenulate<l  or  lobed.  They  are  usually  concealed  by  the  lal)ia  majora,  except 
in  the  fu-tus;  but  are  sometimes  largely  develo]»ed,  and  may  jirojcct  beyond  the 
genital  lissure,  then  assuming  a  dry  ])igmcnted  asjiect.  The  sebaci'ous  glands  are 
large  and  oc(ni]\v  both  surfaces.  They  are  jtoorly  developrd  mitil  pu))erty.  and 
attain  their  greatest  size  and  actiyity  <luring  ])regnancy. 

The  vestibule   is  the  space  between   the  laliia  minora  and   the  vaginal  orifice. 


1040 


THE  FEMALE  REPRODUCTIVE   ORGANS 


Its  boundaries  are  ill  defined  posteriorly,  and  the  term  is  used  with  different 
signiticanee  by  different  anatomists.  Opening  into  it  are  the  urethra,  the  glands  of 
Bartholin,  and  a  few  glands  of  the  same  nature  as  those  of  the  urethra,  surround- 
ing the  external  mi'atus. 

"  The  glands  of  Bartholin  prol>ably  represent  Cowper's  glands  in  the  male,  but 
are  more  superticially  jilaced.  They  are  two  little  racemose  glands,  aljout  a  third 
of  an  inch  long,  situated  one  on  either  side  beneath  the  lateral  wall  of  the  vestibule 
and  behind  the  bulbi  vestibuli.  The  duct,  about  three-quarters  of  an  inch  in 
lengtli,  oju-ns  immediately  in  front  of  the  vaginal  orifice  opposite  its  meridian. 

Vessels. — The  vulvar  structures  are  supplied  by  branches  of  the  external  and 
internal  pudic  arteries.  The  veins  end  in  the  corresponding  trunks,  and  there  is 
in  addition  a  free  anastomosis  with  the  veins  of  the  round  ligament  in  the  sub- 
cutaneous fat  of  the  labium.  The  lymphatics  terminate  for  the  most  part  in  the 
inguinal  glands,  a  few  ])assing  to  the  femoral  glands.  About  the  vaginal  orifice  is 
a  neutral  territory  in  which  the  vulvar  and  vaginal  absorbents  intercommunicate. 

The  erectile  structures  of  the  vulva  correspond  morphologically  to  those  of  the 
male  organ;  the  corpora  cavernosa  are  represented  by  the  clitoris,  and  the  corpus 


Fig.  632.— Diagkammatic  Repre-sextatiox  of  the  Perix.eal  Structuees  ix  the  Female. 


ISCHIO-PUBIC  ARCri 


CSUS  CLITORIOIS  WITH 
13CHI0-CAVERNOSUS 


BULBO-CAVERNOSUS 
COVERING  BULBUS 
VESTIBULI 


Superficial  trian- 
gular ligament 


GLANS  CLITORIDIS 
WITH  PREPUCE 


PARS  INTERMEDIALIS 
Mucous  membrane 
of  vestibule 

MEATUS  URINARIUS 


BULBUS  VESTIBULI 


GLAND  OF  BARTHOLIN 


Sphincter  ani 


si)ongiosum,  cleft  in  the  female  by  the  vulvar  orifice,  appears  beneath  the  mucous 
membrane  of  the  vestibule  in  the  form  of  two  vascular  plexuses,  one  on  each  side, 
called  the  Ijulbi  vestibuli;  and  an  indistinct  mesial  band  extending  from  the  clitoris 
to  the  meatus  is  believed  by  Pozzi  to  represent  the  anterior  part  of  the  corpus 
spongiosum. 

The  CLITORIS  appears  as  a  diminutive  penile  appendage  at  the  upper  part  of 
the  vulva,  and  is  enil)raced  by  a  kind  of  prepuce  formed  by  the  union  of  the  two 
labia  minora.  It  is  composed  of  two  corpora  cavernosa  which  differ  from  the 
corresponding  masculine  structures  only  in  their  size  and  in  their  union  distally 
into  a  rounded  imperforate  extremity,  the  glans  clitoridis,  covered  by  a  layer  of 
integument.  The  crura  are  su]iported  dorsally  ])y  a  suspensory  ligament,  and  are 
attached  to  the  ischial  rami  in  the  same  manner  as  in  the  male. 

The  clitoris  is  relatively  smaller  in  the  adult  than  in  the  child,  and  is  almost 
always  concealed  within  the  rima  pudendi.  It  is  a  highly  sensitive  organ,  and  is 
capable  of  erection. 

The  bulbi  vestibuli  are  two  erectile  bodies  of  somewhat  pyriform  shape,  lying 
one  on  either  side  of  the  vestibule  beneath  the  mucous  membrane.     The  larger 


THE   rUTORIS 


KMl 


extremity  of  oach  is  posterior  and  cxtcmls  liaekwards  nearly  to  the  posterior  com- 
missure, toiiehinjf  the  <flan<l  of  IJartholiii.  Tlie  narro\v  anterior  extremity,  the 
pars  intermedialis  of  Kol)eh,  runs  forwards  to  meet  its  fellow  of  tiie  opjt(»site 
sidi-  Ix'neath  the  elitoris.  Superiorly,  it  is  tixed  to  the  supertieial  trianjiiular  lij^ament 
of  the  perinoeum,  while  it  is  in  relation  internally  to  the  urethral  and  vaginal 
orifices,  and  externally  is  invested  by  the  fibres  of  the  bulbo-cavernosus.  It 
consists  of  erectile  tissue,  enveloped  by  a  thin  tunica  albuginea.  During  the 
condition  of  engorgement  it  helps  to  narrow  the  vestibular  portion  of  the  vulva  and 
the  entrance  of  the  vagina. 

The  vessels  and  nerves  of  the  clitoris  and  bulbi  vestil)uli  are  the  same  as  those 
of  the  analogous  parts  of  the  male. 


Fig.  633. — Section  of  the  Female  Pelvis.     (Alter  Henle.) 
a- 


VESICAL  WALL 

CAVITY  OF  BLADDER 

Prevesical  fat 


Deep   tiansver 
sua  perinaei 


RECTUM 

COCCYX 

Reoto-coecy- 
geal   muscle 
POSTERIOR  LIP  OF  OS 

UTERI 
ANTERIOR  LIP 

VAGINA 

External 
sphincter  ani 

Internal 
sphincter  ani 


^'^if^^^rie^'^^' 


UBIUM  MAJUS  / 
TTnstriped  muscular  fibre 


URETHRA 

LAB'UM  MINUS 

Unstriped  muscular  fibre 

VAGINAL 


ANUS 

Internal  sphincter  ani 
Fart  of  external  sphincter  ani 


Vess-'l 

ORIFICE 


The  muscles  appendeil  to  the  erectile  structures  again  are  v«rv  similar  to  those 
descril>ed  in  coniiretion  with  tlie  penis.  The  ischio-cavernosi  are  itlentical  in 
attachments  with  the  erectores  ])enis;  but  the  bulbo-cavernosi  are  se))arated  in 
tile  middle  line  by  the  vulvar  fissure,  and  ap])ear  on  each  side  as  a  drlicate.  and 
sometimes  very  indistinct,  plane  of  muscular  fibres,  called  the  constrictor  vaginae, 
attached  behind  to  the  tendinous  centre  of  the  i)erina?um,  and  bnaking  u|>  in  front 
into  tendinous  slips  which  run  in  close  external  relation  to  the  bull)i  vestibuli, 
and  become  lost  above  and  below  the  clitoris.  Their  function  is  to  compress  the 
bulbs  and  to  constrict  the  vestibule  and  vaginal  orifice.  The  transversi  perinaei 
have  the  same  connections  as  in  the  male. 

THE  URETHRA  (figs.  G3o,  G34). — The  female  Urethra  represents  only  the  upper 
ti6 


1042  THE  FEMALE  REPRODUCTIVE  ORGANS 

part  of  the  male  canal,  and  is  similarly  related  to  tlie  su])erior  and  inferior  triangular 
ligaments.  It  is  about  an  ineli  and"  a  half  (37  nun.)  in  length,  and  is  directed 
ui)\vards  and  slightly  l)ackwards  to  open  into  the  bladder  about  an  inch  (25 
mm.)  behind  the  niiddle  of  the  symi)hysis.  Its  posterior  wall  is  in  contact  with 
the  vagina,  and  it  is  surrounded  in  front  and  at  the  sides  by  a  plexus  of  veins 
(plexus  of  Santorini).  The  posterior  margin  of  the  meatus  usually  i)resents  a 
tuliercular  i)rominence  by  which  the  position  of  the  orifice  may  be  distinguished 
during  catheterism. 

As  in  the  male  urethra,  the  narrowest  portion  of  the  canal  is  the  external  meatus, 
but  the  whole  tul)e  is  sutliciently  dilatable  in  most  cases  to  allow  the  careful  intro- 
duction of  the  linger  while  the  patient  is  under  an  anaesthetic.  A  case  is  recorded 
])V  William  Cowper  (1697)  in  which,  as  a  result  of  an  imperforate  condition  of  the 
hymen,  it  l)ecame  the  channel  of  sexual  congress. 

Structurally  it  consists  of  a  highly  elastic  mucous  membrane  and  a  strong  mus- 
cular coat.  The  mucosa  is  lined  with  three  or  four  layers  of  ei)ithelial  cells,  the 
more  superficial  of  which  are  prismatic  in  form,  and  presents  a  few  lacunar  and 
some  rudimentary  glandular  follicles.  The  muscular  coat  is  divisible  into  external 
circular  and  internal  longitudinal  layers,  both  intermingled  with  fibres  of  elastic 
tissue  and  with  large  venous  plexuses  which  may  undergo  varicose  dilatation  near 
the  external  orifice  and  form  a  pile-like  tumour.  The  circular  fibres  are  very 
strongly  develoj^ed  at  the  vesical  end  of  the  canal  and  constitute  a  powerful 
sphincter;  these  are  surrounded  by  a  quantity  of  striped  and  unstriped  fibres  which 
form  an  incomj)lete  ring,  deficient  only  in  its  posterior  or  vaginal  segment,  and 
proba])ly  represent  the  prostatic  fibres  and  the  deep  transversus  perinaei  of  the  male. 
It  is  surrounded  by  a  muscular  sphincter  composed  of  striped  and  unstriped  fibre 
corresponding  to  the  deep  transversus  perina?!  in  the  male,  and  partly,  perhaps,  to 
the  musculature  of  the  prostate. 


THE  VAGINA 

The  vagina  is  a  passage  which  extends  upwards  and  slightly  backwards  from 
its  external  opening  at  the  vestibule,  and  terminates  above  by  embracing  the  neck 
of  the  uterus.  Its  vulvar  aperture  is  guarded  in  the  virgin  b}^  a  fold  of  mucous 
memljrane  called  the  hymen. 

Form  and  direction  (figs.  633,  634). — In  its  ordinary  condition  the  vaginal 
canal  is  represented  by  a  fissure  which  in  horizontal  section  assumes  the  form  of 
the  letter  H,  with  a  transverse  limb  about  an  inch  in  length  and  two  short  verti- 
cal limbs  (fig.  633).  In  longitudinal  section  (fig.  633)  the  fissure  branches  above, 
a  short  limb  (occasionally  ill-marked  or  absent)  passing  in  front  of  the  anterior  lip 
of  the  OS  uteri,  a  much  longer  limb  extending  behind  the  os  to  end  about  three- 
quarters  of  an  inch  above  the  extremity  of  the  posterior  lip.  The  angle  of  reflexion 
of  the  vaginal  on  to  the  uterine  mucous  membrane  is  called  the  fornix.  The 
direction  of  the  passage  is  upwards  and  backwards,  forming  an  angle  of  about  30° 
with  the  long  axis  of  the  body,  and  usually  presenting  a  slight  posterior  concavity 
adapted  to  the  convexity  of  the  rectal  ampulla;  the  course  and  direction,  however, 
vary  with  the  degree  of  pelvic  inclination  peculiar  to  the  individual,  and  to  some 
extent  with  the  condition  of  the  bladder  and  rectum. 

The  two  walls  are  of  very  une(iual  length,  the  anterior  measuring  al)out  two 
inches  and  three-fjuarters  (7  cm.),  while  the  posterior  is  prolonged  ui)wards  nearly 
an  inch  (9..")  cm. )  furtbci-. 

Relations. — Anteriorly,  it  is  o])posed  to  the  urethra  and  posterior  wall  of  the 
bladder.  It  is  intimately  united  with  the  lower  two-thirds  of  the  urethra,  but  is 
separated  from  the  u})per  third  and  from  the  bladder  by  loose  connective  tissue 
continuous  with  the  sul)peritoneal  fascia.  The  canal  as  a  whole  is  narrowest  below, 
and  gradually  increases  as  it  ascends,  reaching  its  greatest  admeasurement  where  it 
surrounds  the  os  uteri.  Its  dilatability  is  enormous,  as  may  be  inferred  from  the 
passage  of  the  foetus  in  parturition.  The  ureters  pierce  the  Vesical  wall  in  fi-ont  of 
the  vagina  an  inch  and  a  (piarter  below  the  level  of  the  os  uteri.  Posteriorly,  it 
is  in  relation  with   the  rectum,  but  is   separated  from  it  above  for  about  three- 


THE    VAGIXA 


1043 


(|U;irtprs  of  an  inch  (18  mm.)  by  the  jjeritoneal  cul-de-sac  called  the  pouch  of 
Douglas,  in  the  middle  by  subperitoneal  connective  tissue,  and  bel(j\v  by  the 
tissues  of  the  ])eriiueal  l)ody.  In  the  latter  situation  the  two  canals  diverge,  anrl 
the  ])erinieal  body  hence  ai)pears  on  sagittal  section  as  a  triangle  the  base  of  which 
is  formed  by  the  integument.  Laterally,  it  is  in  contaet  with  the  vaginal  V)ranch 
of  the  uterine  artery,  and  a  venous  jiiexus  lying  in  the  subperitoneal  tissue  at  the 
base  of  the  broad  ligaments.  It  is  crossed  oljli(juely  in  its  upper  third  by  the  ure- 
ters, and  in  its  lower  two-thirds  by  the  anterior  borders  of  the  levatores  ani.  The 
finger  passed  within  the  passage  and  pressed  to  either  side  may  be  made. to  feel  the 
resistance  of  the  })elvic  wall,  and  to  distinguish  the  i)resence  or  absence  of  morbid 
growths  or  effusions.  The  cJuct  of  Gartner,  a  relic  of  the  Wolffian  duct,  may 
occasionally  be  found  by  the  side  of  the  uj)per  half  of  the  vagina  as  a  minute  tube 
or  fibrous  cord.  Two  orifices  which  open  into  the  vagina  near  the  meatus,  some- 
times called  .Skene's  tubes,  are  regarded  by  some  morphologists  as  the  terminations 
of  Gartner's  ducts. 

The  lower  end  of  the  vagina  })ierces  the  triangular  ligament,  and  it  is  here  that 


Fig.  634.— Horizontal  Section  of  Vagina  and  adjacent  rfruucTURES.     (After  Henle. ) 


Levator  ani 


the  resistance  to  dilatation  is  greatest.  The  inlet  may  be  temporarily  narrowed  by 
the  engorgement  of  the  buliji  vt'stibuli,  or  by  the  action  of  the  constrictor  vagiuic, 
and  perhaps  also  ]iy  that  of  the  levatores  ani. 

The  mucous  surface  of  the  lower  half  or  two-thirds  of  the  vagina  presents  on  the 
anterior  wall  a  median  longitudinal  ridge  or  carina,  and  on  the  posterior  wall  two 
ridges,  the  columnae  rugarum,  from  all  of  which  pass  a  number  of  transverse  rugae. 
These  markings  diminisli  in  distinctness  with  advance  in  age  and  with  successive 
parturitions.  The  membrane  is  of  a  pale  rose  colour  in  i)eriods  of  (juiescence,  but 
becomes  turgid  during  the  catamenial  period,  and  in  pregnancy. 

Tlie  hymen  has  been  a  subject  of  much  speculation  amongst  the  learned  and 
unlearned  of  all  ages.  Its  very  existence  was  at  one  time  denied  by  many  great 
authorities,  and  the  significance  to  be  attached  to  its  j)resence  or  absence  is  still  a 
question  in  medical  jurisprudence.  It  ajipears  in  the  virgin  as  an  imperfect  septum 
pierced  by  an  irregular  aperture  which  usually  reaches  to  the  anterior  vaginal  wall, 
and  leaves  a  fold  of  semilunar  form  behind;  but  it  may  be  represented  by  a  circular 
curtain  pierced  by  one,  two,  or  more  apertures.  It  varies  greatly  in  strength  and 
elasticity,  and  although  it  is  nearly  always  ruptured  by  the  first  act  of  sexual  con- 


1044  THE  FEMALE  REPRODUCTIVE   ORGANS 

gress,  it  may  remain  imbrokcii  until  i)arturiti()n.  An  imperforate  condition  of  the 
memljrane  is  occasionally  present,  and  may  necessitate  a  surgical  operation  at  the 
connnencement  of  the  menstrual  period. 

Structure. — The  vaginal  wall  is  composed  of  three  coats,  fil)rous,  muscular,  and 
mucous,  and  has  a  thickness  of  one-eighth  to  one-sixth  of  an  inch.  The  outer 
fibrous  coat  is  derived  from  the  recto- vesical  fascia,  and  holds  in  its  meshes  a  plexus 
of  veins.  The  muscular  coat  comprises  two  layers  of  strong  unstriped  fibres,  the 
outer  longitudinal,  continuous  above  with  the  uterine  muscle  and  with  the  utero- 
sacral  ligaments;  and  the  inner  circular  and  more  largely  developed  near  the  vulvar 
aperture. 

The  mucous  membrane  is  highly  elastic,  beset  with  papilla?  and  covered 
with  a  scpiamous  laminated  epithelium  continuous  with  that  of  the  os  uteri  and 
vulva.  It  has  no  glands,  and  hence  the  fluid  which  moistens  it  is  rather  of  the 
nature  of  a  transudation  than  of  a  secretion. 

Vessels  and  Nerves. — The  arteries  are  derived  from  an  inferior  branch  of 
the  uterine  and  from  the  internal  iliac,  communicating  below  wdth  branches  of  the 
external  pudic;  they  run  along  the  lateral  aspect  of  the  passage  and  give  twigs  to 
the  anterior  and  posterior  surfaces.  The  veins,  similarly  disposed,  form  a  rich 
network  in  the  muscular  and  mucous  coats,  and  terminate  in  the  vaginal  and 
uterine  trunks.  The  lymphatics,  arranged  in  two  intercommunicating  networks, 
mucous  and  muscular,  from  numerous  trunks  which  accompany  the  veins  and  ter- 
minate in  the  pelvic  glands,  a  few  from  the  neighbourhood  of  the  vestibule,  however, 
reaching  the  inguinal  glands.  A  small  gland  is  occasionally  found  between  the 
rectum  and  vagina. 

The  Nerves  come  from  the  hypogastric  plexus,  the  fourth  sacral,  and  the 
pudic. 

THE  UTERUS 

The  uterus,  or  womb  (figs.  635-638),  is  a  hollow  muscular  organ  lined  with 
mucous  membrane.  It  communicates  above  with  the  two  Fallopian  tubes,  and 
below  with  the  vagina,  and  lies  within  the  pelvic  cavity  between  the  bladder  and 
rectum,  fixed  in  its  place  by  folds  of  peritoneum  and  certain  bands  of  unstriped 
muscle.  It  varies  greatly  in  size  and  form  at  different  periods  of  life  and  under 
different  physiological  conditions. 

The  adult  uterus  is  flattened  from  before  backwards,  pyriform  in  its  outlines 
when  seen  from  the  front,  and  is  divided  into  tw^o  main  portions,  body  and  cervix, 
by  a  transverse  constriction,  the  isthmus.  The  isthmus  may  l3e  regarded  as  the 
weak  point  in  the  organ,  and  it  is  here  that  the  various  pathological  flexions  take 
place.  Its  position  in  the  virgin  uterus  is  about  midway  between  the  two  extremi- 
ties, but  it  lies  near  the  junction  of  the  middle  and  lower  thirds  in  women  who 
have  borne  children. 

The  u))per  ])ortion,  or  body,  presents  two  surfaces,  three  borders,  and  two 
angles.  The  anterior  surface  is  almost  flat,  and  is  covered  by  a  layer  of  peri- 
toneum which  is  reflected  at  the  level  of  the  isthmus  upon  the  bladder,  forming  a 
shallow  utero-vesical  pouch  which  is  occupied  by  coils  of  small  intestine.  The 
posterior  surface  is  distinctly  convex,  and  covered  in  its  whole  extent  by  a  layer 
of  peritoneum  which  is  prolonged  downwards  over  the  neck  and  for  a  short  distance 
upon  the  posterior  wall  of  the  vagina  before  undergoing  reflexion  U})on  the  rectum 
to  form  the  recto-vaginal  pouch,  or  pouch  of  Douglas.  The  superior  border, 
or  base,  is  thick  and  rounded,  and  is  covered  by  the  })eritoneum,  Avhich  passes  from 
the  anterior  to  the  ])osterior  surface.  The  lateral  borders,  slightl}'  convex  and 
miming  down-\vards  and  inwards,  correspond  to  the  line  of  attachment  of  the  peri- 
toneal folds  called  the  broad  ligaments.  The  superior  angles,  at  the  junction 
of  the  superior  with  the  lateral  Ixn-ders,  give  attachment  to  the  oviducts  or  Fallo- 
pian tubes.     The  term  fundus  is  loosely  applied  to  the  upper  part  of  the  body. 

The  cervix  is  cylindric-al  in  section,  wider  in  the  middle  than  above  or  below, 
and  may  be  divided  into  three  ])ortions, — an  U])])('r  supravaginal  zone,  a  middle 
zone  of  vaginal  attachment,  and  a  lower  intravaginal  zone,  tlie  os  uteri.  The 
supravaginal  zone,  representing  about  one-half  of  the  neck  behind  and  two-thirds 


THE    UTERUS 


1045 


in  front,  is  in  relation  anteriorly  with  the  I  (ladder;  ])osteriorly  it  is  covered  with 
the  peritoneum  of  the  anterior  wall  of  the  pouch  of  Douglas,  and  at  the  sides  it  is 
connected  with  the  hroad  ligament,  in  which  lie  the  uterine  vessels  and  the  ureter, 
the  latter  at  a  distance  of  a  little  over  half  an  inch.     The  zone  of  vaginal  attach- 


FiG.  635. — The  Female  Okuans  ok  Generation.     (Modilied  Iroin  Suppey.) 
(Vagina  divideil  and  laid  open  behind.) 

POSTERIOR  SURFACF  OF  BODY  OF  UTERUS 

Utero-ovorian  ligament 

OVARY 

FALLOPIAN  TUBE 

Broad  ligament 


FIMBRIATED  EXTREMITY 
OF  TUBE 
FIMBRIA  OVARICA 

Lower 
part  of  broad  ligament 

OS  UTERI 

OS  EXTERNUM 

VAGINAL  WALL,  DIVIDED  AND  REFLECTED 


VAGINA,  ANTERIOR  WALL 


Fig.  636. — The  PosTEnioR  Surface  of  the  Uterus.     (After  Sappey.) 


EXTRA-VAGINAL   CERVIX 


INTRA-VAGINAL  CERVIX 

OS 
VAGINAL  WALL 


—  FALLOPIAN  TUBE 


Fdge  or  peritoneum  of  Douglas's  poucb 


CERVICAL  ATTACHMENT  OF  VAGINA 


ment  i.-<  ol)li(|U('ly  set,  extending  higher  l)eliind  than  in  front,  and  has  a  de]ith  of 
ahout  one-tit'th  of  an  inch  (5  mm.).  The  intravaginal  zone,  or  os  uteri,  is 
covered  with  mucous  membrane  continuous  with  that  of  the  vagina.  It  jiresents 
the  external  ai»ertuiv  of  the  uteriiu-  eavity,  usually  in  tlie  form  of  a  transvei-se  fis- 


1046 


THE  FEMALE  REPRODUCTIVE  ORGANS 


sure,  about  a  quarter  of  an  inch  (6  mm.)  in  length,  bounded  by  two  prominent 
labia,  anterior  and  posterior,  both  of  which  are  in  contact  with  the  posterior  wall 
of  the  vagina.  The  anterior  lip  is  the  thicker,  the  shorter,  and  the  lower;  the  pos- 
terior Hp  is  louirer  on  account  of  the  greater  height  of  the  posterior  vaginal  fornix. 
After  childbirth  the  labia  usually  become  notched  and  irregular. 

Dimensions. — The  size  of  the  uterus  varies  within  wide  limits.     Its  average 


Fig.  637.— Frontal  Sectiox  of  thk  ViRaix  Utekus.     (After  Sappey.) 


,/^ 


UTERINE  WALL 
CAVITY  OF  BODY 


UTERINE  WALL 
CAVITY  OF  CERVIX  WITH  ARBOR  VIT/E 


OS  EXTERNUM 
VAGINAL  WALL 


\ks%j^ 

''        Mm 

1     m 

1     m 

1 1     ■  K 

^^^^^s 

/ 


length  in  the  nulliparous  adult  is  about  two  and  a  half  inches  (6  cm.)  and  its 
greatest  breadth  about  an  inch  and  a  half  (4  cm),  but  in  women  who  have  borne 
children  these  dimensions  are  about  one-fifth  greater.  Its  weight  averages  seven 
drachms  in  nulliparae,  nine  to  twelve  drachms  in  multiparse. 

Direction. — The  direction  of  the  uterine  axis  is  undoubtedly  variable,  and  it  is 

Fig.  638.— Sagittal  Section  of  the  Virgin  Uterus.     (After  Sappey.) 


CAVITY  OF  CERVIX 

POSTERIOR  FORNIX 
POSTERIOR  LIP 


CAVITY  OF  BODY 


REFLEXION  OF  PERITONEUM 


ANTERIOR  LIP 
ANTERIOR  FORNIX 


OS  EXTERNUM 


probable  that  observations  made  after  death  are  open  to  misinterpretation.  It 
appears  to  coincide  imder  ordinary  circumstances  Avith  the  long  axis  of  the  body, 
both  in  the  recumbent  and  erect  postures,  but  may  be  inclined  forwards  to  the 
extent  of  15°  or  20°  when  the  bladder  is  empty,  or  may  be  deflected  to  the  right 
when  the  rectum  is  full,  and  is  furthermore  affected  by  the  condition  of  the  neigh- 
bouring intestinal  coils. 


thf:  uterus  1047 

Variations  in  form  according  to  age. — Jn  young  cliildrcn  the  l)ody  is  but 
slightly  developed  in  proportion  to  the  cervix,  and  the  i)roniinence  of  the  intra- 
vaginal  segment  is  relatively  great.  In  the  virgin  uterus  ol  a  young  adult  the 
knigtli  is  al)out  equally  divided  between  body  and  cervix,  but  after  childlnrth  the 
body  never  returns  to  its  original  size,  and  its  length  Avhen  involution  is  complete 
is  nearly  double  that  of  the  neck.     In  old  age  the  entire  organ  undergoes  atrophy. 

The  cavity  of  the  uterus  is  reduced  to  a  fissure  b}'  the  antero-posterior  llattening 
of  the  walls.  It  is  divisible  into  two  segm(uits,  that  of  the  body  and  that  of  the 
neck.  The  shai)e  of  the  cavity  of  the  body  is  that  of  a  triangle  with  convex  sides 
(in  the  virgin)  and  three  open  angles.  At  the  two  superior  angles  are  the  orifices 
of  the  oviducts,  and  the  lower  angle  presents  the  os  uteri  internum  or  a])erture 
of  coinmunication  with  the  neck.  The  walls  are  smooth,  and  moistened  with 
mucus. 

The  average  length  of  the  cavity  in  the  nulliparous  adult  is  about  two  inches 
(5  cm.);  in  multipara?,  two  and  a  quarter  to  two  and  a  half  inches  (5 '5  to  6  cm,). 
The  greatest  transverse  diameter  is  a  little  less  than  half  of  these  measurements. 

The  cavity  of  the  neck  is  fusiform,  terminating  in  the  os  internum  al)Ove,  and 
in  the  os  externum  below.  The  sui)erior  opening  is  circular,  the  inferior  usually 
in  the  form  of  a  transverse  fissure.  The  mucous  lining  of  the  anterior  and  j)osterior 
walls  })resents  ridges  which  bear  some  resemljlance  to  those  of  the  vagina,  Init  are 
dependent  u])on  the  arrangement  of  the  innermost  layers  of  the  muscular  wall,  and 
not  upon  a  sim])le  plication  of  the  mucous  membrane.  The  whole  length  of  each 
wall  is  traversed  by  a  longitudinal  nearly  median  ridge  or  stem,  from  which  pass 
a  number  of  branches  in  an  outward  and  slightly  upward  direction.  The 
figure  formed  by  these  folds  is  designated  by  the  name  of  arbor  vitse  uterina  ;  it  is 
most  marked  in  the  young,  and  tends  to  effacement  after  repeated  parturitions. 
The  cavity  usually  contains  a  plug  of  alkaline  mucus. 

Structure. — The  uterus  is  composed  of  three  coats — an  outer  sero- fibrous,  a 
middle  muscular,  and  an  inner  mucous.  The  serous  membrane  covers  the  upper 
half  or  two-thirds  of  the  anterior  surface,  the  Avhole  of  the  supravaginal  portion  of 
the  posterior  surface,  and  the  summit.  The  lower  portion  of  the  anterior  wall  is 
separated  from  the  bladder  by  cellular  tissue  continuous  with  the  subperitoneal 
fascia,  and  a  thin  layer  of  the  same  structure  may  be  demonstrated  over  the  lower 
part  of  the  posterior  surface  and  laterally  into  the  base  of  the  broad  ligament  on 
either  side  between  the  two  peritoneal  lamina?.  Owing  to  this  dis])Osition  of  the  suV)- 
serous  tissue,  the  whole  of  the  cervix  uteri  may  be  amputated  without  encroaching 
upon  the  peritoneal  cavity. 

The  muscular  coat  constitutes  the  greater  part  of  the  thickness  of  the  organ. 
The  arrangement  of  the  fibres  is  very  com])lex,  but  a  fairly  satisfactory  division 
into  three  layers  may  be  demonstrated: — a  thin  outer  layer,  partly  longitudinal, 
l)artly  transverse  in  direction,  continuous  with  the  muscular  fibres  of  the  oviducts, 
vagina,  round,  ovarian,  and  utero-sacral  ligaments,  and  with  the  nmscular  expan- 
sion in  the  broad  ligaments;  a  middle  layer,  very  thick,  its  fibres  plexiform,  run- 
ning in  all  directions,  and  intermingled  with  large  venous  plexuses  in  the  body  of 
the  uterus,  the  innermost  strands  forming  s])hincteric  rings  around  the  os  internum 
and  around  the  orifices  of  the  oviducts;  and  a  thin  internal  layer,  longitudinal  in 
the  l)ody,  and  ]trodu(itig  the  ridges  of  the  arlx)r  vitic  in  the  cervix. 

The  mucous  membrane  of  the  body  is  smooth  and  pale,  lined  with  cylindrical 
ciliated  ei)itiielium,  and  pierced  by  innumerable  tubular  glands.  The  ciliary  motion 
is  from  within  outwards.  The  mucous  membrane  of  the  cavity  of  the  Dcrk  is 
thicker  and  is  plicated  in  the  maimer  already  described;  its  epithelium  is  ciliated 
down  to  the  external  opening,  but  there  undergoes  a  transition  into  the  squamous 
laminated  epithelium  which  covers  the  intravaginal  jiortion  of  the  os.  Many  tubu- 
lar and  racemose  mucous  glands  open  into  the  furrows  of  the  arbor  vitre.  and  these 
are  lialtle  to  pathological  changes  which  cause  them  to  assume  a  vesicular  charac- 
ter, when  tlu'v  are  sometimes  known  under  the  fanciful  name  of  ovula  Nabothi. 

Ligaments. — The  so-called  ligaments  of  the  uterus  are  of  two  kinds,  ])eritoneal 
and  nniscular. 

The  peritoneal  ligaments  are  six  in  numlter:  two  lateral,  two  anterior,  and  two 
posterior. 


1048 


THE   FEMALE   REPRODTTTTVE   ORGANS 


The  lateral  or  broad  ligaments  (lig.  6o9j,  called  als^o  alae  vespertilionis 
from  their  fancied  rer^enihhnue  to  the  wings  of  a  })at,  are  formed  l)y  a  duphcattu-e 
of  peritoneum  extending  from  the  sides  of  the  uterus  and  vagina  transversely  out- 
wards to  the  sides  of  tlie  pelvis.  The  two  layers  of  peritoneum  are  continuous 
above  and  form  the  free  border  of  the  fold,  V)ut  diverge  laterally  and  below,  where 
they  pass  on  to  adjacent  structures.  Each  ligament  presents  two  surfaces  and  four 
borders.  The  superior  or  free  border  is  represented  by  the  sunnnit  of  the  plica- 
tion, which  turns  around  the  oviduct  and  follows  a  sinuous  course  towards  the  side 
of  tiie  pelvis,  its  outermost  extremity  lying  external  to  the  fimbriated  extremity  of 
the  Fallo]iian  tube  and  forming  a  sliarp  fold,  the  ligamentum  infundibulo-pel- 
vicum,  which  conveys  the  ovarian  vessels.  The  internal  border  is  attached  to 
the  sides  of  the  uterus  and  vagina,  the  two  laminse  separating  to  transmit  the  utero- 
vaginal vessels,  and  muscular  bands,  wliich  ])ass  from  the  uterus  into  the  peritoneal 
fold.  The  inferior  border  is  attached  to  the  levator  ani  and  recto-vesical  fascia; 
its  laminae  are  separated  by  fat-bearing  cellular  tissue  (subperitoneal)  which  gives 
passage  to  vessels  and  nerves  and  to  the  ureter;  and  the  anterior  layer  is  much 
shorter  than  the  posterior,  owing  to  the  higher  level  of  its  point  of  reflexion.  The 
external  border  lies  against  the  obturator  fascia,  and  transmits  the  uterine  vessels 
and  the  round  ligament. 

Fig.  G39. — The  Broad  Ligamext  axd  its  Contexts,  seex  feom  the  Feoxt. 

(Alter  Sappey.) 

PAROVARIUM  * 

— ■ FALLOPIAN  TUBE 


AMPULLA  OF  FALLOPIAN  TUBE 


EXTERNAL  ANGLE  OF  UTERUS 


FIMBRIArED  EXTREMITY  OF  TUBE 

FIMBRIA  OVARICA 


Kound  ligament 
Ligament  of  ovary 


Anterior  peritoneal  lamina 


The  structures  enclosed  between  the  two  layers  of  the  broad  ligament 
are: — (1)  The  ovary  and  its  \igament,  the  former  ])r()iccting  from  the  posterior 
lamina  and  invested  by  a  modified  epithelium;  the  latter,  composed  of  unstriped 
muscular  fibre,  passing  between  the  side  of  the  uterus  and  the  inner  or  lower 
extremity  of  the  ovary.  (2)  The  Fallopian  tube,  lying  at  the  uj^per  margin  im- 
mediately beneath  the  point  of  continuity  of  the  two  laminae;  its  outer  fimbriated 
extremity  turned  backwards  and  inwards  to  the  ovary,  and  attached  by  one  of  the 
fringes  to  the  outer  or  lower  end  of  the  organ.  It  does  not  reach  quite  to  the  pelvic 
wall.  (3)  The  round  ligament,  a  muscular  band  running  dowuAvards  and  out- 
w^ards,  forming  a  ridge  beneath  the  anterior  lamina,  and  eventually  passing  to  the 
internal  inguinal  ring  and  through  the  inguinal  canal  into  the  labium.  (4)  Foetal 
relics:  (o)  the  epovarium,  or  epoophoron,  a  group  of  twelve  to  tAventy  effete 
tul)ules  of  the  Wolllian  liody  lying  close  lo  \\\v  attached  Ijorder  of  the  ovary,  bear- 
ing a  certain  reseml)lance  in  plan  to  the  vasa  efYercntia  of  the  testicle,  and  joining 
a  kind  of  collecting  tul»e  above,  {h)  The  duct  of  Gartner,  a  canal  representing 
the  lower  ])art  of  the  Wolfiian  duct,  is  constant  in  certain  animals  (cow,  etc.)  as  a 
tube  running  on  each  side  of  the  uterus  and  vagina,  and  opening  at  the  lower  end 


THE  UTERUS 


1049 


of  the  latter  passage.  In  the  luniiaii  subject  it  is  sometimes  found  in  the  form  of 
a  small  muscular  cord,  or  e})ithelial  canal,  near  the  cervix  uteri  or  ui)i)er  part  ai  the 
vagina.  According  to  some  anatomists,  its  lower  end  is  occasionally  found  as  a 
little  tube  opening  into  the  side  of  the  vulva  near  the  urinary  meatus,  but  it  is 
doubtful  -whether  the  tube  in  question  is  more  than  a  mucous  duct,  (c)  The  par- 
ovarium, or  paroophoron,  a  few  scattered,  imperfectly  devehjjted  tub\iles  in  the 
neiglil)ourhood  of  the  epoophoron,  also  representing  traces  of  the  \\'olfIian  body. 
They  are  usually  seen  as  small  wliitisli  or  yellowish  grains  in  the  infant,  but  are 
rarely  demonstrable  in  the  adult.  (//)  The  hydatid  of  Morgagni,  a  long  iK'dicu- 
lated  vesicle  of  the  size  of  a  millet  seed  or  pea,  occasionally  dcjiendent  from  the 
fimbriae  of  the  tuV)es,  is  believed  to  be  a  relic  of  the  Wolfhan  body,  (e)  Small 
pedunculated  cysts  often  found  on  the  posterior  layer  of  the  broad  ligament  and 
derived  from  the  parovarium.  (5)  The  uterine,  ovarian,  and  funicular  vessels, 
anastomosing  near  the  angle  of  the  uterus;  and  the  uterine  plexus  of  nerves.      (6j 

Fig.  640. — DiA«RAM>r.\Tic  Section  of  the  Broad  Ligament. 

PERITONEUM    REFLECTED   OVER  SUMMIT   OF  LIGAMENT 


POSTERIOR   SURFACE 


FALLOPIAN  TUBE 

TUBAL  BRANCH  OF  OVARIAN  VESSELS 
PAROVARIUM 


Ovarian  artery 


Hound  ligament  with 
funicular  veBselfc 


Connective  tissue  and  unstriped 
muscle    utero-pelvic  baudi 


I'terinf  reins 
Uterine  artery 


Base  of  ligament 


A  (juantity  of  loose  adipose  cellular  tissue  lying  between  the  muscular  and  other 
structures  and  the  serous  meml»rane,  and  in  continuity  with  the  subperitoneal 
fascia  of  the  pelvis.  (7)  Involuntary  muscular  fibres  passing  from  the  obturator 
fascia  to  become  attached  to  the  sides  of  the  uterus  and  vagina,  en.sheatliing  the 
ves.sels  and  serving  as  a  sup]jort  to  the  uterus.  They  may  be  com])ared  with  the 
fibro-muscular  subperitoneal  bands  sui)porting  the  third  stage  of  the  duodenum, 
the  transverse  colon  and  small  intestines,  and  are  essentially  sustentacular  in  rela- 
tion to  the  viscera  and  to  their  vessels  and  nerves. 

The  posterior  peritoneal  or  recto-uterine  ligaments  are  two  serous  folds 
which  run  I)a(kwards  from  the  intraperitoneal  iH.itioii  of  the  cervix  wXvx'x  and  vagina 
to  become  continuous  with  the  ])eritoneal  investment  of  the  secon<l  stage  of  the 
rectum.  They  form  the  lateral  l)oundaries  of  the  ])oueh  of  Douglas,  and  between 
their  layers  lie  muscular  utero-sacral  ligaments,  comparalde  t<t  the  expansion  in 
the  broad  ligaments,  with  l<>..se  connective  ti.->ue  and  a  number  of  anastomosing 
branches  of  the  uterine  and  lueninrrlioidal  vessels. 


1050 


THE  FEMALE  REPRODUCTIVE   ORGANS 


The  anterior  peritoneal  or  utero-vesical  ligaments  are  two  ill-defined  folds 
whieh  pass  one  on  eaeli  side  from  the  cervix  uteri  to  the  l)ladder. 

Tlw3  muscular  ligaments  lying  between  the  peritoneal  folds  are  four  pairs: 
three  in  the  broad  ligaments,  the  round  or  utero-inguinal,  the  utero-ovarian,  and 
the  utero-pelvic,  and  one  in  the  posterior  ligaments,  the  utero-sacral.  They  have 
already  lieen  l)rieriy  rt'ferrcil  to. 

The  round  or  utero-inguinal  ligament  (fig.  639)  is  a  cord,  about  five  inches  in 
length,  attached  to  the  uterus  just  below  the  Falloi)ian  tube,  and  there  continuous 
with  the  superficial  uterine  fibres.  From  this  point  it  runs  obliquely  downwards, 
outwards,  and  forwards,  innnediately  beneath  the  anterior  layer  of  the  broad 
ligament,  to  reach  the  pelvic  wall;  it  then  loops  around  the  curve  of  the  deep 
epigastric  artery  on  the  inner  side  of  the  external  iliac  artery,  and  enters  the  inguinal 
canal  at  the  internal  ring.  In  its  course  through  the  canal  it  is  supplemented  by  a 
set  of  striped  fibres,  some  derived  from  the  muscular  walls  of  the  abdomen,  others 
apparently  of  independent  origin;  and  it  may  be  accompanied  by  a  tube  of  peri- 
toneum, the  canal  of  Nuck,  which  is  constant  in  the  foetus  and  not  infrequently 
persistent  during  childhood  and  even  adult  life.     The  ligament  then  gives  off  a  few 


Fig.  641. — Section  of  the  Pelvis  showing  the  Ligaments  of  the  Uterus. 


SYMPHYSIS 
Prevesical  fat 
BLADDER  WALL 

VESICAL  CAVITY 


Obturator  internus 
Obturator  fascia 


Subperitoneal 
tissue 


Utero-pelvic 
ligament 


Peritoneum 


Saoro-soiatie 
ligament 


RECTUM 

Utero-sacral  ligament 
running  forward  into 
recto-uterine  liga- 
ment 


Peritoneum  of 
utero-vesical 
pouch 

Utero-vesical 
ligament 

—  Broad  ligament 


Recto-vaginal  pouch 
of  Douglas 


(*)^^_  }  '''"''* 


of  its  newly  acquired  striped  fibres  to  the  pillars  of  the  ring  and  to  the  pubic  spine, 
and,  emerging  from  the  external  ring,  finally  breaks  up  into  a  number  of  delicate 
fasciculi  which  become  lost  amongst  the  interlobular  connective  tissue  of  the  large 
pad  of  fat  which  occupies  the  labium  majus. 

In  structure  it  is  composed  of  unsti'iped  muscle  with  areolar  and  elastic  tissue, 
reinforced  in  the  inguinal  canal  by  striated  muscular  fibres  and  funicular  vessels 
and  nerves.  The  funicular  artery,  conveyed  by  the  round  ligament,  is  a  branch  of 
the  superior  vesical.  It  is  accompanied  by  a  plexus  of  veins,  and  anastomoses  in 
the  labium  with  branches  of  the  external  pudic,  and  at  the  superior  angle  of  the 
uterus  with  the  uterine  and  ovarian. 

The  utero-sacral  ligaments  (fig.  641)  are  flat  muscular  l)ands,  extending  from 
the  highest  part  of  the  cervix  uteri,  where  they  are  more  or  less  continuous  with 
the  uterine  fibres  in  the  recto-uterine  peritoneal  folds,  to  the  sides  of  the  sacrum 
opposite  the  loAver  border  of  the  sacro-iliac  synchondroses.  They  run  one  on  each 
side  of  tlie  rectum  near  the  junction  of  the  first  and  second  stages  of  this  portion  of 
the  intestine,  closely  connected  with  its  muscular  coat,  and  more  anteriorly  are  in 
lateral  relation  with  the  pouch  of  Douglas. 


Tin-:  FALJJ/I'IAX   TI'BES 


1051 


The  utero-pelvic  ligaments  (tig.  (341)  are  the  expansions  of  muscular  tissue 
already  deseril)ed  in  connection  with  the  broad  litrarnent.  They  radiate  from  the 
fascia  over  the  obturator  internus  to  the  sides  of  the  uterus  and  vairina,  and 
enslieathe  the  utero-vairinal  vessels  and  nerves. 

The  utero-ovarian  ligaments  (tig.  (339),  or  ligaments  of  the  ovaries,  are 
short  rounded  cords  continunus  with  the  uterine  fibres  at  the  superior  auL'le  of  the 
organ  l)ehind  the  Fallopian  tube,  and  joining  externally  the  inner  end  and  attached 
l)f)rder  of  each  ovary.  These  vari<)us  ligamentous  structures  all  serve  to  main- 
tain the  normal  ])Osition  of  the  uterus.  In  addition,  the  utero-ovarian  ligament 
aids  in  the  fixation  of  the  ovary,  and  the  round  and  utero-pelvic  ligaments  form 
protective  sheaths  for  vessels  and  nerves. 


THE  FALLOPIAN  TUBES  OR  OVIDUCTS 

The  Fallopian  tubes  (fig.  639)  represent  the  upper  extremities  of  the  ^rtillerian 
ducts,  and  may  ])rol)ably  be  regarded  as  cornua  uteri  both  in  structure  and  mor- 
phology.    They  are  two  trumpet-shaped  tubes  structurally   continuous   with   the 


Fig.  642. — The  Broad  Ligamext  and  its  Contexts,  seen  feom  the  Feoxt. 

( After  Sappe}'. ) 

PAROVARIUM 

FALLOPIAN  TUBE 
AMPULU  OF  FALLOPIAN  TUBE  I  EXTERNAL  ANGLE  OF  UTERUS 


FIMBRIATED  EXTREMITY  OF  TUBE 

FIMBRIA  OVARICA 


Round  ligament 
Ligament  of  ovary 


Anterior  peritoneal  lamina 


superior  angles  of  the  uterus,  and  running  between  the  two  layers  of  the  broad 
ligaments  to  become  closely  connected  with  the  ovaries,  partly  by  direct  attachment, 
])artly  by  a  peculiar  contiguity.  Each  duct  opens  internally  into  the  uterine  cavity, 
and  its  external  orifice  establishes  a  continuity  between  the  tubo-ovarian  mucous 
membrane  and  the  peritoneum,  but  under  normal  circumstances  is  closely  applied 
to  the  surface  of  the  ovary,  and  receives  the  ova  which  are  detached  from  the  gland, 
transmitting  them  to  the  uterine  cavity.  It  is  al)outfour  and  a  half  inches  (11  cm. ) 
in  length,  straight,  narrow,  and  somewhat  cord-like  at  its  uterine  end  for  a  distance 
of  about  an  inch  and  a  half;  flexuous,  and  irregularly  dilated  in  the  rest  of  its 
length  as  far  as  its  free  extremity,  where  it  becomes  exi)anded  into  a  truTn])et- 
shaped  mouth,  fringed  by  a  circle  f)r  circles  of  diverging  villous  processes  or  fimbriae, 
one  of  which,  the  fimbria  ovarica,  or  tubo-ovarian  ligament,  is  attached  to  the 
outer  extremity  of  the  ovary.  One  or  two  little  cystic  ju'dieulated  appendages,  like 
the  hydatid  of  Morgagni  in  the  testicle,  may  also  be  appen<led  to  the  mouth.  The 
aperture  (ostium  abdominale)  in  the  middle  of  this  exiiansion  is  very  small,  not 
more  than  half  a  line  or  a  line  in  diameter,  but  its  mucous  membrane  may  be 
prolonged  for  some  distance  along  a  furrow  in  the  tubo-ovarian  ligament. 

The  narrow  extremity,  or  isthmus,  has  a  diameter  of  about  an  eighth  of  an  inch 


1052  THE  FEMALE  REPRODUCTIVE   ORGANS 

(3  mm.),  the  dilated  portion  or  ampulla  measures  about  a  third  of  an  inch 
(8  mm. ),  and  the  terminal  expansion  exclusive  of  its  fringes  has  a  width  of  about 
a  quarter  to  a  third  of  an  inch,  the  free  fimbriti?  ranging  in  length  from  two-fifths 
to  three-fifths  (10  to  15  mm.)  of  an  inch,  while  the  fimbria  ovarica  attains  an 
inch  or  even  two  inches  (2  "5  to  5  cm.).  Accessory  fimbriated  extremities  are  occa- 
sionally met  with. 

The  direction  of  the  oviduct  traced  from  its  uterine  attachment  is  transversely 
outwards  as  far  as  the  middle  of  the  ovary;  beyond  this  point  the  tul)e  winds  in  a 
fiexuous  course  Ixickwards  and  inwards  around  the  gland  in  the  manner  described 
beldw. 

Structure. — The  tube  has  four  coats — serous,  cellular,  muscular,  and  mucous. 
The  serous  coat,  represented  by  the  fold  at  the  free  border  of  the  broad  ligament, 
is  incom})lete,  like  that  of  the  small  intestine,  the  muscular  tunic  being  micovered 
by  peritoneum  for  about  one-fourth  or  one-fifth  of  its  circumference  along  the  line 
of  attachment  of  the  two  serous  laminae,  and  hence  a  rupture  of  the  duct  may  lead 
to  an  escape  of  its  contents  either  into  the  peritoneal  cavity  or  into  the  interserous 
space.  The  cellular  coat  is  a  kind  of  adventitia,  rich  in  vessels,  and  continuous 
with  the  sul)i)eritoneal  tissue  of  the  broad  ligament.  The  muscular  coat,  about 
the  sixtieth  of  an  inch  in  thickness,  consists  of  circular  and  longitudinal  filjres;  the 
latter  for  the  most  part  sparingly  distributed  outside  the  former,  Init  near  the  outer 
extremity  of  the  tube  appearing  also  as  an  innermost  layer.  The  circular  layer 
is  most  attenuated  near  the  fimbriated  extremity.  The  mucous  membrane  is 
characterised  mainly  by  its  plications.  The  folds  are  longitudinal  in  direction,  and 
relatively  simple  in  the  isthmus,  where  the  cavity  appears  as  a  stellate  fissure  when 
cut  across;  but  in  the  ampulla  the  multiplication  of  surface  is  ver}'  complex,  and 
in  a  transverse  section  presents  a  deceptive  appearance  of  branching  tubular  glands 
within  the  depth  of  a  thick  mucosa.  At  the  fimbriated  extremity  of  the  tulje,  the 
jDlications  are  continued  on  to  the  fringes.  The  epithelium  is  cylindrical  and 
ciliated,  the  motion  being  towards  the  uterus.  At  the  trumpet-shaped  extremity  it 
passes  by  transition  into  the  pavement  epithelium  of  the  serous  memljrane.  The 
subepithelial  tissue  contains  a  longitudinal  muscularis  mucosa. 


THE   OVARIES 


The  ovary  (fig.  635)  is  a  paired  organ  which  projects  strongly  from  the  posterior 
surface  of  the  broad  ligament.  Its  longest  diameter  averages  an  inch  and  a  half,  its 
greatest  breadth  about  three-quarters  of  an  inch,  its  thickness  about  half  an  inch; 
and  its  weight  is  ordinarily  aljout  100  grains.  The  right  is  usually  a  little  larger 
than  the  left. 

Form,  position,  etc. — The  typical  shape  resembles  that  of  a  broad  almond. 
In  anatomical  preparations  it  appears  as  a  horizontal  appendage  to  the  back  of  the 
broad  ligament  with  an  anterior  attached  border,  a  posterior  free  border,  superior 
and  inferior  surfaces,  an  inner  extremity  connected  with  the  utero-ovarian  liga- 
ment, and  an  outer  extremity  receiving  the  fimbria  ovarica  of  the  Fallojuan  tube: 
it  is  most  probal)le  however  that  the  position  is  different  when  the  organs  are  in 
situ  under  normal  circumstances.  Symington  in  his  examination  of  frozen  sections 
in  children  found  the  ovary  lying  in  a  sagittal  plane  against  the  side  wall  of  the 
pelvis  with  its  long  axis  nearly  vertical,  so  that  its  surfaces  were  internal  and 
external,  its  borders  anterior  and  posterior,  and  its  extremiti(>s  upper  and  lower, 
while  the  Fallopian  tulje  ran  upwards  along  the  anterior  attached  border  of  the 
gland,  then  arching  l)ackwards  above  its  upjjer  extremity  to  end  in  the  fimbriae; 
and  where  the  fimbriae  are  fully  developed  they  may  embrace  the  ])osterior  free 
border,  and  thus  the  tube  is  wound  almost  completely  around  the  gland,  leaving 
only  the  lateral  surfaces  exposed.     The  external  surface  is  said  to  lie  against  the 


THE   OVARIES  1053 

pelvic  wall  in  a  hollf)\v  between  the  internal  iliac  artery  and  vein,  but  there  is  every 
reason  to  believe  that  it  is  very  varial>le  in  the  adult.  The  laxity  of  its  connections, 
the  liability  to  clianges  of  position  during  pregnancy,  and  the  changing  relations  of 
the  contiguous  viscera  make  it  dillicult  to  accept  any  one  of  the  many  views  as 
al)Solutely  correct.  The  organ  when  enlarged  may  be  felt  tlirough  the  vagina,  and, 
better,  through  the  rectum,  and  its  position  with  regard  to  tlie  surface  is  indicated 
by  a  point  al)out  two  inches  to  the  inner  side  oi  the  anterior  superior  spine  of  the 
ilium.  The  surfaces  and  free  border  are  of  a  dull  white,  and  after  puberty  are 
scarred  by  l>reachcs  of  surfaces  due  to  the  dehiscence  of  ripe  ova;  the  attached  Ijor- 
der  is  j)ierced  Ijy  the  ovarian  vessels  and  nerves  which  lie  between  the  layers  of  the 
broad  ligament,  and  their  point  of  entrance  is  termed  the  hilum. 

Structure. — The  ovary  consists  of  a  parenchyma  and  a  kind  of  capsule,  or 
tunica  albuginea.  The  latter,  unlike  the  tunica  albuginea  of  the  testis,  is  a 
modilication  of  the  stroma  of  the  gland,  and  does  not  exceed  the  two-hundred-and- 
fiftieth  of  an  inch  in  thickness;  it  is  crowned  with  an  epithelium  (columnar) 
differing  in  character  from  that  of  the  serous  membrane  with  which  it  is  connected. 
The  true  gland-structure  is  a  mass  of  connective  tissue  and  unstriped  muscle  with 
vessels  and  nerves.  It  is  very  vascular  in  the  neighbourhood  of  the  liilum,  where 
the  veins  are  peculiarly  large  and  closely  set,  and  is  condensed  into  a  kind  of  cortex 
beneath  the  albuginea.  The  cortex  is  about  half  a  line  in  thickness,  and  consists 
of  interlacing  bundles  of  white  fibrous  tissue,  which  pass  insensibly  into  the  faintly 
fibrillated  tunica  albuginea,  and  enclose  multitudes  of  small  vessels  called  ovisacs, 
or  Graafian  follicles,  in  which  the  ova  are  develojjed. 

The  majority  of  the  ovisacs  are  microscopic,  but  as  they  ripen  and  approach  the 
surface  they  increase  in  dimensions,  and  may  even  attain  the  size  of  a  large  white 
currant.  Their  rupture  leads  to  the  scarring  already  mentioned,  and  the  emi)ty 
capsule  slowly  disappears  when  impregnation  has  not  occurred;  Init  under  the 
influence  of  the  vascularisation  of  the  organs  during  pregnancy,  it  may  undergo 
a  renuirkal)le  development  and  form  a  yelloAV  plicated  body  known  as  the  corpus 
luteum. 


VESSELS  AND  NERVES  OF  THE  UTERUS  AND  ITS  APPENDAGES 

The  vessels  are  the  uterine,  ovarian,  and  funicular,  all  of  which  are  paired. 
The  uterine  artery  (fig.  643),  a  branch  of  the  internal  iliac,  runs  from  its  origin 
in  a  downward  direction  along  the  jjclvic  wall  as  far  as  the  base  of  the  broad  liga- 
ment; then,  crossing  horizontally  towards  the  cervix  uteri  in  front  of  the  ureter,  it 
gives  off  some  small  vaginal  and  vesical  branches,  and  runs  upwards  in  a  serpentine 
course  close  to  the  side  of  the  body  of  the  uterus,  supplying  transverse  branches  to 
the  anterior  and  posterior  walls  of  the  organ.  These  anastomose  with  their  fellows 
across  the  middle  line,  one  larger  branch  opi)osite  the  junction  of  the  liody  and 
cervix,  forming  with  the  corresponding  vessel  of  the  other  side,  the  *  arterial  circle 
of  Huguier. '  Finally  they  conmiunicate  at  the  upper  angle  with  the  terminal 
twigs  of  the  ovarian  and  funicular  arteries.  The  uterine  veins  are  of  very  large 
size,  and  on  leaving  the  uterus  form  a  plexus  in  the  muscular  tissue  of  the  broad 
ligaments,  at  length  joining  a  trunk  which  runs  side  l>y  side  with  the  artery  to  end 
in  the  internal  iliac  vein. 

The  ovarian  artery,  arising  from  the  aorta  (like  the  spermatic  in  the  male), 
crosses  the  coimnon  iliac  artery,  and  is  conducted  into  the  broad  ligament  by  the 
ligamentum  infundibulo-pelvicum  (page  104.S),  which  extends  to  the  outer  end  of 
the  oviduct.  It  breaks  up  into  two  divisions:  (1)  The  tubal,  which  runs  along  the 
lower  border  of  the  oviduct,  where  the  peritoneal  layers  of  the  tube  separate,  and 
sends  numerous  branches  to  it;  and  (2)  the  orarifin  jirnjter,  a  large  ser]»entine  vessel 
which  gives  off  many  large  branches  into  the  hilum  of  the  gland,  and  then  passes 
to  the  angle  of  the  uterus,  where  it  ends  by  anastomosing  with  the  uterine  and 
funicular  arteries. 

The  ovarian  veins,  very  largely  developed  about  the  hilum  of  tin*  ovary, 
appear  as  a  plexus  in  the  broad  ligament,  and.  reaching  the  margin  of  the  )>li  xus, 


1054 


THE  FEMALE  REPRODUCTIVE   ORGANS 


assume  a  pampiniform  arrangement  around  the  artery.  The  right  ends  in  the  vena 
cava,  the  kft  in  the  renal  vein. 

The  funicular  artery  is  an  offset  of  the  vesical.  It  joins  the  round  ligament 
at  the  internal  ring,  and  divides  into  ascending  and  descending  branches,  the  former 
running  backwards  in  the  substance  of  the  ligament  as  far  as  the  angle  of  the  uterus, 
Avhere  it  connnunicates  with  the  ovarian  and  uterine;  the  latter  passing  with  the 
hgament  through  the  inguinal  canal  into  the  labium,  there  anastomosing  with  the 
external  pudic.     It  is  accomiianied  by  its  vein. 

The  lymphatics  (fig.  643 )  of  the  uterus  and  Fallopian  tubes  form  plexuses  in 
the  mucous  membrane,  in  the  muscular  walls,  and  beneath  the  peritoneum.  Those 
of  the  ovary  originate  in  the  jierifollicular  tissue  around  the  Graafian  vesicles,  and 
escape  at  the  hilum.     The  efferent  vessels  from  these  three  organs  may  be  divided 


Fig.  643.— Diagram  of  the  Aktekies  and  Lymphatics  of  the  Female  Generative 

Oegaxs. 

Lymphnlics  of  hroatl  lignment 

{to  lumbar  yiantU)  OVARY 


FALLOPIAN  TUBE 


Funicular  lymphatics 
{to  inguinal  glands) 


Vttriiie  and  vaginal  lymphatic, 
(to pelvic  glands) 


Vulvar  lymphatics 
(to  inguinal  glands) 


Transverse periuaeal  artery 


into  three  groups  with  intercommunicating  territories.  (1")  The  first,  including 
those  of  the  body  of  the  uterus,  those  of  the  ovary,  and  those  of  the  Fallopian 
tube,  unite  l)y  the  side  of  the  ovarian  vessels  and  run  with  the  veins  to  terminate 
in  the  prevertebral  glands  in  front  of  the  aorta  and  vena  cava;  (2)  the  second, 
those  of  the  cervix  uteri,  form  two  trunks  which  run  along  the  base  of  the  broad 
ligament  with  the  uterine  vein  to  end  in  the  pelvic  glands  which  lie  beneath  the 
bifurcation  of  the  iliac  artery;  (3)  the  third,  those  of  the  round  ligament,  follow 
tliis  structure  and  end  in  the  inguinal  or  lower  iliac  glands.  Here  as  elsewhere  the 
lymphatics  are  collateral  with  the  veins. 

The  nerves  of  the  uterus  are  derived  from  the  third  and  fourth  sacral,  the 
hypogastric  ))lexus  of  the  sympathetic,  and  from  the  renal  plexus,  which  also  sup- 
plies the  ovaries  and  oviduct. 


DEVELOPMENT  OF  GEXITO-VRiyARY   OROAXS 


lOoo 


DEVELOPMENT  OF  THE  GENITOURINARY  ORGANS 

There  is  at  first  a  periud  in  tlic  f^rovvtli  uf  the  oiuhryo  duriii;,'  which  there  is  no  iixlication  of 
any  iirovision  either  for  the  irenerative  or  for  tlie  urinary  luuction.  A  little  later  tlie  rudiments 
of  a  genito-urinary  ajjparatus  are  laid  down,  but  there  is  as  yet  no  ai)i)c'aranee  oi"  sexual  differen- 
tiation. Finally,  a  third  stage  in  the  fomative  process  is  occupied  by  the  evolution  of  the  orL'ans 
characteristie  of  the  masculine  or  feminine  type,  and  the  completion  of  the  glandular  and  otlier 
structures,  which  provide  for  the  secretion,  storage,  and  ultimate  expulsion  of  the  urine  I'rom  the 
body.  It  will  be  seen  that  in  the  eour.se  ofthe.se  devclo]imental  changes  certain  of  the  .structures 
concerned  appear  and  a.><sunie  their  i)ermanent  characters  gradually  and  without  alteration  of 
plan;  others,  oiiginally  employed  lor  i)urposes  unconnected  with  "the  genito-urinary  system, 
become  adapted  to  take  their  place  in  this  section  of  the  economy  ;  others  belonging  to  the  .system 
from  the  first  are  brought  into  a  special  condition  of  i'unctional  activity  only  to  undergo  conversion 
to  a  different  use  later  on  ;  while  others  again  may,  according  to  the  sex  a.s.sumed  by  the  foetus, 
either  dwindle  into  u.selcss  relics  without  ever  taking  any  share  in  the  W(jrk  of  the  body,  or  may 
become  el:\borated  into  important  and  tfficient  parts  oi'  the  repntductive  organism. 


Fig.  644.— Diagram  of  the  Primitive  Gexito-ukixaky  Organs  before 
DiFFBKEXTlATiON  OF  Sex.     (After  Heule.) 


MULLER'S  DUCT 
GENITAL  GLAND 
WOLFFIAN  BODY 

(Tubular  structure  not  shown) 


Hound  ligament 

WOLFFIAN  DUCT 

UNITED  MULLERIAN  DUCTS 
OPENINGS  OF  WOLFFIAN  DUCT 

SINUS  URO-GENITALIS 
PENIS  CLITORIS 


URACHUS 

INTERIOR  OF  BUDDER 


OPENINGS  OF  URETERS 

URETHRA 

OPENING  OF  MULLERIAN  DUCT 


The  earliest  appearance  is  that  of  a  tube  called  the  Wolffian  duct,  which  opens  liy  its  hinder 
extremity  into  a  cloaca  or  common  "'itlet  lor  the  intestinal  and  urinary  pa.-sages.  From  the  fure 
juirt  of  this  duct  is  develojied  a  temj)orarj'  organ,  the  pronephros,  or  head-kidney,  in  the  iiiim 
of  vascular  glomeruli.  Bihind  this  soon  a|)pear  a  nuud>er  of  tulK>.  which  open  at  riLiht 
angles  inti>  the  mid  portion  oi'the  duet,  and  con.-titute  the  mesonephros,  mid-kidney,  or  Wolffian 
body.  Still  farther  back,  Irom  the  ]Mj:>teiior  end  of  the  duct,  springs  the  metanephros,  or  hind- 
kidney,  a  Hiesoblastic  growth  around  a  hollow  branching  iirotrusion  trom  the  duct,  with  which 
tubules  and  glomeruli  subsiMpiently  become  connected,  riie  pronephros  (|uickly  di>apiiears  in 
the  higher  vertebrates:  the  niesonephros,  which  reaches  its  maximum  development  by  the  sixth 
week,  soon  ceases  to  discharge  its  renal  i'unction,  and  either  becomes  a  u.sdess  relic  in  the  broad 
ligament  of  the  female  nelvis,  or  tuidergoes  transformatittn  into  an  essential  i)art  oi'  the  male 
generative  apparatus  ;  wliile  the  metanephros  becomes  developed  into  the  ])ernianent  kidney. 
The  ureter  and  Jirinii'erous  tubules  i)robably  originate  as  special  outirrowths  from  the  po.^terior 
part  of  the  Wolifian  duet.  The  luorpliolotry  of  the  suprarenal  body  is  somewhat  doubtiul.  but  it 
is  probable  that  the  medulla  is  a  derivative  of  the  synnpathetie  sy>tem.  and  hence  of  epiblastic 
origin  ;  while  the  cortex  is  a  me.sobla.stic  development  \n  conne<;tion  with  the  fore  end  of  the 
Wolffian  duct.     It  is  at  first  larger  than  the  kidney,  but  the  latter  attains  au  equal  bulk  by  the 


1056 


URIXAnV  AXD  REPRODUCTIVE   ORGANS 


tenth  week,  and  tlien  continues  to  increase,  becoming  con  side  rablj'  the  greater  by  the  end  of  foetal 
Hfe  ;  but  even  at  birth  the  suprarenal  bodies  are  proporti<jnally  much  hirger  thau  in  the  adult. 

The  urinary  bladder  apjK'ars  in  the  second  month  as  a  transformation  of  the  pedicle  of  the 
allantois,  a  structure  whicli  has  already  done  service  in  conveying  the  vessels  of  the  embryo  to 
the  placenta.  The  allantois  is  a  hypoblastic  sac  invested  by  a  layer  of  mesoblast,  and  communi- 
catinff  with  the  liind  trut.  That  'portion  of  it  which  lies  within  the  body  becorues  dilated  at  its 
central  part  into  the  urinarv  bladder,  but  remains  narrow  at  both  extremities,  forming  in  front 
the  urachus ;  and  behind,  "tlie  whole  urethra  in  the  female,  and  the  upper  part  of  the  pros- 
tatic urethra  in  the  male.  ,      TTT  ,«>         -1  ^    n  1  •      1 

The  generative  ai)i>aratus  is  developed  from  the  Wolffian  ducts  and  trora  two  other  paired 
structures  closely  related  to  these,  but  of  somewhat  later  Ibrmation — the  Miillerian  ducts  and  the 

genital  glands.  ,  .      ,  ,.         i    •      i  •,      ■,       ^    ^      n   ^ 

From  the  Wolffian  body  its  tubules  and  its  duct  are  tormed,  in  the  male,  the  whole  ot  the 


Fig    64.5  —Development  of  the  Ueixo-gexerative  Organs,  Female  Type. 

(After  Henle.) 

(The  parts  formed  from  the  Miillerian  duct  in  this  and  the  succeeding  diagram  are 

indicated  by  horizontal  shading  ;  those  formed  from  the  Wolffian 

body  and  duct,  by  diagonal  cross-hatching.) 


FALLOPIAN  TUBE 
PAROVARIUM 


Bound  ligament 


CRUS  CLITORIDIS 


BULBUS  VESTIBUU 
VULVAR  CLEFT 


URETHRA 

GLAND  OF  BARTHOLIN 

CLITORIS 


excretory  tubes  outside  the  body  of  the  testicle,  namely,  the  vasa  efferentia,  the  coni  vasculosi, 
the  tube  of  the  epididymis,  the  vas  deferens,  the  ejaculatory  duct,  and  the  paradidymis  (the  organ 
of  Giraldes).  In  the  female  the  structure  dwindles  away,  leaving  its  vestiges  as  the  jiarovarium 
and  the  duct  of  Gartner  (the  latter  being  occasionally  demonstrable  in  the  human  subject). 

The  genital  gland  arises  as  a  ridge,  partly  mesoblastic  and  partly  due  to  a  thickening  of  an 
ei)ithelial  layer,  the  germinal  epithelium,  on  the  inner  side  of  the  Wolffian  bodj'.  The  cells,  at 
first  indeterminate,  soon  become  differentiated  to  form  the  Graafian  follicles  and  ova  in  the  female, 
ami  the  ei)ithelium  of  the  seminiferous  tubes  in  the  male  ;  the  rest  of  the  ovary  or  testicle  being 
developed  from  the  mesoblast  of  the  ridge.  The  gland  is  at  first  attached  to  the  Wolffian  body. 
Tlie  latter  is  itself  fixed  to  the  posterior  wall  of  the  abdominal  cavity  l)y  a  dujilicature  of  pei'ito- 
neum  calleil  the  mesorchium,  or  mesovarium,  from  which  a  little  fold  containing  muscular  fibre 
is  prolonged  downwards  to  licconie  the  gul)frnaculum  testis  in  the  male,  or,  after  connection  with 
tlie  uterus,  the  round  ligament  in  the  female. 


DEVELOPMEXT  OF  GEXITO-URIXARY  ORGAXS 


1057 


The  Miillerian  duct  l)e<rius  as  a  slender  cord  lying  jiaralkl  to,  and  un  the  outer  side  ut',  the 
Wolffian  duet.  It  becomes  canalized  and  ojtens  distally  into  the  cloaca.  After  a  time  it  i'usos 
with  its  fellow  mesially  a  short  distance  above  the  terminal  aperture,  and  the  conjoint  tube  is 
bound  together  with  the  adjacent  Wolffian  ducts  into  a  kind  of  stem  called  the  genital  cord.  In 
tile  male  the  Miillerian  duct  never  appears  to  di.scharire  any  function,  and  its  useless  relics  are  to 
be  traced  in  the  sinus  pocularis  and  hydatid  of  Morgagni ;  but  in  the  female  it  gives  rise  to  nearly 
the  whole  of  the  internal  apparatus  of  generation  ;  its  upper  extremity,  above  the  line  of  fusion 
in  the  human  subject,  forming  the  oviiluct  and  its  hydatid  appendage,  the  conjoint  tube  develo|)- 
iuL'  the  uterus  and  vagina.  Variations  in  the  point  of  fusion  (jf  the  two  ducts  may  lead  to  the 
abnormality  of  a  two-horned  uterus,  or  even  a  double  uteiiis  and  vagina.  Exceptionally  Miiller's 
duct  may  firm  a  rudimentary  uterus  in  the  male.  In  .such  cases  the  testes  are  well  developed, 
but  the  penis  remains  very  small. 


Fig.  046.— Devi:lopment  of  the  Urino-gexekative  Organs,  Male  Type. 

(After  Henle.j 


BODY  OF  TESTICLE 

GUBERNACULUM 

VAS  DEFERENS 
URETER 

VESICULA  SEMINALIS 

SINUS  POCULARIS 

EJACULATORY  DUCT 

PROSTATE 

MEMBRANOUS  URETHRA 

BULB 


PROSTATIC  URETHRA 


CORPUS  SPONGIOSUM 
CORPUS  CAVERNCSUM 


The  external  genitals  are  developed  about  the  doacal  outlet  common  to  the  genito-urinary 
and  intestinal  canal:".  The  first  change  is  the  appearance  of  a  genital  eminence,  the  future  clitoris 
or  i>enis,  at  the  ventral  extremity  of  the  cloacal  fi.ssure  about  the  fifth  or  sixth  week.  A  fortnitrht 
later  the  cloaca  is  flivided  by  a  transverse  septum  into  two  jiarts,  a  dorsal  or  anal,  and  a  ventral  or 
uro-genital  (uro-genital  sinus);  the  se|itum  it.self  persisting  as  the  perinf\?al  Inidy  in  the  female, 
and  the  portion  of  the  perin.-vum  lying  between  the  scrotum  and  anus  in  the  male.  Its  ab.<ence 
or  incomplete  development  accounts  for  certain  congenital  malformations  well  known  to  teratolo- 
<:i-ts.  The  uro-genital  sinus  next  undergoes  changes  which  give  the  external  stain  j)  of  sex.  At 
first  the  urethra  ojiens  into  the  sirms  liehind  the  genital  prominence.  In  the  female  this  remains 
permanent,  the  lips  of  the  sinus  expand  into  the  labia  niajora  ;  two  ridges  within  the  sinus,  ex- 
tending one  on  each  side  as  high  as  the  genital  prominence,  form  the  nymjilifc  ;  and  a  little  .semi- 
lunar fold  at  the  entrance  of  the  vaerina  shows  itself  in  the  fifth  month  and  becomes  the  hymen  ; 
67 


1058  URIXARV  AXD  REPRODUCTIVE   ORGANS 

while  the  genital  eminence  ceases  to  enlarge  and  remains  as  the  clitoris.  In  the  male  the  evolu- 
tionary processes  go  farther.  The  margins  of  the  uro-genital  sinus  fuse  in  the  middle  line  to  close 
in  a  prolongation  of  the  urethra  on  the  ventral  aspect  of  the  genital  eminence  and  to  form  the 
scrotum,  the  i)rocess  being  concluded  about  the  fitteenth  week  ;  finally,  a  jujuch  of  jieritoneum 
makes  its  way  on  each  side  through  the  abdonjinal  wall  into  the  corresi)onding  half  of  the  scro- 
tum, and  into  this  the  testicle  ultimately  descends,  guided  by  the  gubernaculum  (page  1025). 
The  glands  of  Cowper  or  Bartholin  in  both  .sexes  are  formed  by  involutions  of  ei)ithelium  near 
the  root  of  the  rudimentary  clitoris  or  i)enis. 

Should  the  process  of  mesial  fusion  lail,  the  urethra  may  present  a  fistulous  opening  on  its 
ventral  side,  or  may  remain  cleft  from  the  meatus  upwards  for  a  greater  or  less  distance.  In  the 
more  aggravated  forms  the  defect  of  union  involves  the  scrotum  also,  and  leads  to  a  s]>urious 
liermaphrodism  in  which  is  perpetuated  a  superficial  resemblance  to  the  female  genitals,  the  sim- 
ulation being  made  greater  by  the  imperfect  descent  of  the  testicles.  All  these  congenital  defects 
are  clearly  accounteil  for  by  ascertained  facts  in  morphology  ;  but  there  is  a  malformation  which 
our  present  knowledge  does  not  satisfactorily  explain — that  known  as  'extroversion  of  the  blad- 
der,' in  which  a  non-closure  of  the  ventral  parietes  below  the  umbilicus  coincides  with  a  fis.sure 
in  the  anterior  wall  of  the  allantoic  bladder,  and  leads  to  an  extrusion  of  the  posterior  wall  of  the 
viscus.  Mr.  Shattock  suggests  that  the  condition  is  perhaps  the  result  of  an  undue  extension 
forwards  of  the  cloacal  fissure  ;  but  the  problem  cannot  yet  be  regarded  as  solved. 


TRF  PERINEUM 


The  term  perinaeum  {T^spi,  '^alm)  has  been  variously  applied  Vjy  anatomists — 
firstly,  in  its  original  and  general  meaning,  to  the  soft  parts  connected  with  the 
pelvic  outlet;  secondly,  to  the  anterior  or  genito-urinary  segment  only  of  these 
parts;  and  thirdly,  to  the  tissues  separating  the  vulvo-vaginal  and  ano-rectal 
passages.  It  is  here  employed  in  the  first  and  broader  sense,  the  expression 
'  perineum  proper '  being  used  for  the  second  application,  and  that  of  '  perinatal 
body  '  for  the  third. 

The  outlet  of  the  pelvis  is  a  lozenge-shaped  space  bounded  in  front  by  the 
symphysis  and  subpubic  ligament,  behind  by  the  tip  of  the  coccyx,  and  on  each 
side  by  the  conjoined  rami  of  os  pubis  and  ischium,  the  tuber  ischii,  and  the  inferior 
border  of  the  great  sacro-sciatic  ligament.  The  latter  structure  is  overlapj^ed  to  a 
variable  extent  by  the  gluteus  maximus,  which  also  covers  the  tuber  ischii  when 
the  thighs  are  extended;  but  the  glutei  are  merely  accessory  to  the  true  boundaries. 

The  dimensions  of  the  outlet  in  the  male  and  female  are  given  on  page  146. 
The  further  anatomy  of  the  parts  differs  in  the  two  sexes. 


THE  MALE  PERINyEUM 

The  integument  of  the  perinaeum  is  pigmented,  beset  with  scattered  hairs, 
and  provided  with  large  sebaceous  and  sudoriparous  glands.  Its  deeper  layers 
contain  an  abundance  of  smooth  muscular  fibre  continuous  with  the  dartos  of  the 
scrotum,  and  these  are  so  disposed  around  the  anal  margin  as  to  corrugate  the 
skin  into  radiating  folds  during  their  contraction. 

The  landmarks  of  the  region  are  for  the  most  part  well-defined.  Tlio  symphysis 
in  front  is  obscured  by  the  root  of  the  penis,  which  may  be  traced  backwards  as  a 
soft  median  prominence  as  far  as  a  point  an  inch  anterior  to  the  anus.  On  each 
side  the  pubic  and  ischial  rami  may  be  felt  running  outAvards  and  l)ackwards  to 
expand  into  the  ischial  tuberosity,  which  is  uncovered  by  the  gluteus  maximus 
when  the  thigh  is  flexed.  Extending  backwards  and  inwards  from  the  tuberosity 
may  be  detected,  in  thin  subjects,  the  resistance  of  the  great  sacro-sciatic  ligament; 
and  still  more  posteriorly  the  coccyx  is  felt  in  the  middle  line  immediately  beneath 
the  skin.  The  anal  ajierture,  surrounded  by  radiating  furrows,  lies  a  short  distance 
in  front  of  the  coccyx,  and  on  ench  side  of  it  is  a  depression  called  the  ischio- rectal 
fossa,  the  superficial  aspect  of  which  depends  upon  the  amount  of  fat  which  occu- 
pies it. 


THE  MALE  PERIXAJUM 


lUO'J 


The  perinaium  is  divided  url)itnirily  into  two  \K\viii  Ijy  a  line  drawn  transversely 
between  the  two  ischial  tu))erosities  an  inch  in  front  of  the  anus.  The  anterior 
portion  is  called  the  perintuuni  ])roper,  the  posterior  the  isehio-rectal  region.  Tliis 
line,  however,  does  not  coincide  exactly  with  the  true  anatomical  l»ound;iry  as 
revealed  l»y  dissection. 

The  isehio-rectal  region  comprises  the  parts  suiTouiiding  tlic  amis  and  the 
isehio-rectal  fossa*. 

The  removal  of  the  integument  exi)oses  the  si>hincter  muscle  of  the  anus  in  the 
middle  line,  and  on  each  side,  ht'tween  this  and  the  lateral  lioimdary  of  the  jieri- 
na-um.  the  external  ajx'rture  of  the  isehio-rectal  fossa. 

Tile  sphincter  ani  externus  is  a  voluntary  muscle  surrounding  the  anus,  and 


Fi(i.  047.— The  .Malic  PkuiX-EIM.     (Modified  from  Hirsclifeld  and  Lcveillt-.) 

BULBO-CAVERNOSUS 

Superflcial  triangular  ligament 
ISCHIO-CAVERNOSUS 


ISFERWR  PVDESDA  L  AVvA'  1 
•SLPERFKIAL  I'ERLWICAL  .SERVE 


INFERIOR  II.EMORRnori)AL  SERVE 
CUTASEOUa  BRASCH  OF  FOURTH  SACRAL 


Qluteus  maximus 
TUBEROSITY  OF  ISCHIUM 
I  Great  aacro-sciatic  ligament 

Levator  ani 
Superficial  transversus  perinci 
Sphincter  ani 


attached,  in  front  to  the  tendinous  centre  of  the  perina?um  (where  it  meets  the 
bulbo-cavernosi,  the  superficial  transversi  perina?i,  and  some  fasciculi  of  the  levatores 
ani);  V)ehind  to  the  tip  of  the  coccyx.  Its  fibres  are  closely  comiected  with  the 
skin,  and  sui)erHcial  bundles  pass  fol•^^•ards  by  the  sides  of  the  anus,  a  few  decus- 
sating with  each  other  acro.^^s  the  middle  line,  and  .some  ajtpear  to  cross  directly 
over  to  the  opposite  side,  and  around  the  anus  as  an  annular  sphincter.  They  are 
pierced  by  radiating  liands  of  the  longitudinal  layi-r  of  the  muscular  wall  of  the 
rectum,  which  l)ecome  lost  in  the  <lee]»  layers  of  the  integument. 

The  external  sphincter  is  in  relation  superli<-iallv  with  the  integument,  deeitly 
with  the  levatores  ani  and  internal  s]»]iincter;  on  the  outer  side  witli  the  fat  of  the 
isehio-rectal  fossa;  and  internally  with  the  lower  )»ortioni>f  the  'internal  sphincter' 
(a  thickening  of  the  cinular  muscle  of  the  rectum  ).  ami  to  a  small  extent  with  the 


10(30 


URINARY  AND  REPRODUCTIVE  ORGANS 


rectal  mucous  membrane.  It  is  supplied  by  the  inferior  ha?morrhoidal  branches 
of  the  internal  juidic  artery;  its  veins,  of  large  size  and  very  lial)le  to  varicose 
dilatation,  terminate  in  the  inferior  hsemorrlioidal  and  pudic  veins;  its  lymphatics 
open  into  the  inguinal  glands;  and  its  nerves  are  derived  from  the  perinseal,  the 
pudic,  and  the  fourth  sacral. 

Action. — The  external  sphincter,  by  virtue  of  its  elasticity,  gives  some  passive 
aid  to  the  internal  sphincter  in  maintaining  the  closure  of  the  anus  and  the 
retention  of  the  contents  of  the  rectal  ad-de-sac  under  ordinary  conditions;  but 
its  active  and  more  important  function  is  to  close  the  anal  aperture  firmly  during 
the  contraction  of  the  levatores  ani  and  other  constrictor  muscles  of  the  al)domino- , 
pelvic  cavity  in  powerful  muscular  efforts  not  connected  -with  defecation  (as  in 
vomiting,  urinaticm,  parturition,  expiration,  etc.).  This  it  effects  partly  through 
the  approximation  of  the  opposite  sides  of  the  anus  by  its  longitudinal  fibres,  and 
partly  by  the  ring-like  contraction  of  its  circular  fibres.  It  also  aids  in  flexing  the 
coccyx,  and  in  fixing  the  tendinous  centre  of  the  perina?um  during  the  contraction 
of  the  bulbo-cavernosi. 


THE  PELVIC   FASCI.E  AXD  MUSCLES 

In  order  to  understand  the  constitution  of  the  ischio-rectal  fossae  and  their 
relation  to  adjacent  parts,  it  is  necessary  to  review  the  muscular  elements  of  the 
pelvic  Avail,  and  the  arrangement  of  the  pelvic  fasciae. 


Fig.  648. — Diagram  of  the  Pelvic  Fascia. 


Transversalis  fascia 


Obturator  fascia 

'  White  line' 

Recto-vesical  fascia 


Obturator  fascia 
Ischio-rectal  fascia 


Alcock's  canal  with 
pudic  vessels 


Abdominal  muscles 


BORDER  OF  ACETABULUM 


Apex  of  ischio-rectal 
fossa 


Levator  ani 

ISCHIAL  TUBEROSITY 


Sphincter  ani 


The  osseo-ligamentous  framework  of  the  walls  of  the  true  pelvis  is  constituted 
by  the  two  ossa  innominata  below  the  ilio-pubic  line  and  posterior  border  of  the 
pubic  crest,  by  the  sacrum  and  coccyx,  and  by  the  sacro-sciatic,  sacro-iliac,  and 
interpubic  ligaments,  and  the  obturator  membrane.  Supplementing  these  struct- 
ures on  each  side  of  the  median  line,  are  four  muscles:  the  obturator  internus,  the 
pyriformis,  the  coccygeus,  and  the  levator  ani,  together  with  their  fascial  invest- 
ments. 

The  obturator  internus  and  pyriformis  have  already  been  described  (pages  355- 
358).  The  fascia  covering  the  inner  aspect  of  the  former  muscle  bears  a  very 
important  relation  to  the  intrapelvic  structures. 


PELVIC  FASCLE  AXD  MUSCLES 


1061 


The  obturator  fascia  (figs.  648,  650)  is  attached  abore  to  the  iHo-j»uhic  line, 
as  far  back  as  the  sacio-ihac  joint  and  to  the  posterior  lij)  of  the  crest;  helov:,  to 
the  l)ack  of  the  symphysis,  the  inner  lip  of  the  lower  border  of  the  isclno-i)ul>ic 
ramus,  and  the  inner  l>order  of  the  ischial  tuberosity;  and  behind  it  skirts  tlie 
osseous  border  of  the  great  sciatic  notch  as  far  as  tlie  ischial  spine,  but  at  the  lesser 
sciatic  notch  passes  out  of  the  i>elvis  with  the  muscle,  and  ajtpears  in  the  post- 
femoral  region  of  the  thigh.  At  its  Ijorders  it  is  closely  related  to  the  fascia  iliaca 
above,  the  fascia  of  the  pyriformis  behind,  and  the  dee})  triangular  ligament  below. 
Its  outer  surface  is  in  contact  with  the  muscular  fibres  of  the  obturator  intemus;  its 
inner  surfare  is  divided  into  tAvo  portions  by  a  curved  l)and  of  fibres  called  the 
'  white  line  '  or  arcus  tendineus,  extending  from  the  inner  aspect  of  the  ischial 
si)ine  to  tin-  back  of  the  os  i)ul»is,  a  little  external  to  the  symphysis.  The  upper 
or  pelvic  segment  above  the  white  line  is  separated  from  the  pelvic  viscera  by 
sul>peritoneal  tissue;  the  lower  or  ischio-rectal  segment,  Ijelow  the  line,  enters 
into  the  formation  of  the  outer  wall  of  the  ischio-rectal  fossa.  This  portion  forms 
a  sheath  (canal  of  Alcock)  for  the  pudic  vessels  and  nerves  about  an  incli  above 
the  inner  margin  of  the  tuber  ischii.     The  fascia  gives  oft"  from  its  inner  surface  at 


Fig.  649.— Muscles  of  the  Floor  of  the  Pelvis. 


PyriformiB 


Levator   ani     'divided 
below  the  "  white  line '  i 


Space  for  obturator 
intemus 


!'<i.isnge  for  gluteal 
vessels  and  nerve 

Pyriformis 
Passage  for  sciatic 

II nd  pudic  vessels 

and  nerve 

SCHIAL  SPINE 


;;occygeu8 
Callular  interval 
Levator  ani 


Capsule  of  prostate, 
and  pubo-prostatic 
ligaments 


the  white  line  two  thin  laminte:  one,  the  recto-vesical,  to  the  visceral  surface  of  the 
levator  ani;  the  other,  the  ischio-rectal,  to  the  parietal  aspect  of  the  same  nmscle. 

The  levator  ani  muscle  (figs.  648,  650),  with  its  fellow  of  the  opposite  side, 
constitutes  the  greater  part  of  the  muscular  floor  of  the  pelvis,  and  acts  as  a  septum 
between  the  pelvic  cavity  and  the  ischio-rectal  fossa.  It  arises  anteriorly  from  the 
back  of  the  os  pubis,  just  external  to  the  attachment  of  the  pubo-vesical  musrle, 
posteriorly  from  the  inner  side  of  the  ischial  spine  below  the  origin  of  the  coccyg- 
eus,  and  between  these  two  points  from  the  whole  length  of  the  "white  line.'  Its 
fibres  form  a  Hat  plane  of  consideraV>le  strength,  and  pass  downwards,  backwards, 
and  inwards  to  their  insertion,  the  most  posterior  into  the  tip  of  the  coccyx;  those 
next  in  order  joining  the  opposite  muscle  in  a  nu-dian  raphe  extending  from  tlie 
coccyx  to  the  tendinous  centre  of  the  perinanmi.  and  the  rest  becoming  lost  ujton  the 
side  of  the  rectum,  interlacing  with  the  longitudinal  layer  of  the  muscular  wall  of  the 
gut,  a  few  fil)res  perhajis  running  in  front  to  the  preanal  raphe.  Its  two  surfaces  may 
be  termed  visceral  and  ])arietal;  the  former,  looking  forwards  as  well  as  upwards,  is 
invested  by  a  layer  of  fascia,  the  recto-vesical,  and  is  further  separated  from  the 
lower  part  of  the  bladder  by  suliperitoneal  tissue;  the  parietal  surface,  covered  by 
a  fascia,  the  ischio-rectal  or  anal,  forms  the  greater  })art  of  the  outer  wall  of  the 
ischio-rectal  fos^a.     The  anterior  and  posterior  l)orders  of  the  muscle  are  free  (and 


1062 


UEIXABY  AXD   REPRODUCTIVE   ORGAXS 


here  the  two  investing  fascia?  become  continuous  Avith  each  other).  The  anterior 
l)order  crosses  the  side  of  the  prostate,  and  is  connected  with  the  corresponding 
})art  of  the  opjiosite  muscle  by  tibrous  and  smooth  muscuLar  tissue,  which  passes 
between  the  prostate  and  rectum.  The  posterior  border  is  separated  from  the  ante- 
rior margin  of  the  coccygeus  by  an  indistinct  celhilar  interspace. 

In  the  female  the  anterior  fibres  of  insertion  are  connected  with  the  side  of  the 
vagina,  interlacing  with  the  longitudinal  tilires  of  its  muscular  tissue  without  be- 
coming actually  inserted  into  the  passage. 

The  levator  ani  is  supplied  by  twigs  of  the  inferior  ha?morrhoidal  vessels  and 
nerves,  and  receives  also  l)ranches  from  the  fourth  and  fifth  sacral  nerves. 

Action. — The  special  action  from  which  the  muscle  derives  its  name  has  been 
questioned  by  Riidinger,  who  believes  that  its  essential  function  is  to  compress  the 
rectum.  A  studv  of  the  direction  of  the  fibres,  however,  leaves  little  doubt  that 
the  result  of  the  contraction  of  the  muscle  as  a  whole,  and  in  association  with  its 
fellow,  is  to  draw  forwards  the  coccyx  and  elevate  the  i)elvic  floor  and  viscera,  and 

Fig.  650. — Diagram  showixg  I.ixes  of  Attachment  of  the  Fasciae 

AND   MUSCI.es  of   THE   PELVIS.      (W.  A.) 


GREATER  SACRO-SCIATIC 
NOTCH 


ISCHIAL  SPINE  WITH  ATTACH- 
MENTS OF  COCCYGEUS  AND 
LEVATOR  ANI 

LESSER  SCIATIC  NOTCH 


Course  of  'white  line' 


Obturator  fascia 


Deep  triangular  ligament 

Posterior  border  of 
perinaeal  ledge 

Transversus  perinaei 


Obturator  fascia 


Levator  ani 


Subpubic  ligament 

Superficial  triangular 

ligament 
Fascia  of  Colles 


ISCHIO-CAVERNOSUS  AND  CRUS 


thus  lessen  the  long  diameter  of  the  abdomino-pelvic  cavity  and  aid  in  the  com- 
pression of  the  abdominal  and  pelvic  viscera.  Its  action  as  a  compressor  of  the 
rectum  is  probably  unimportant,  but  it  is  possible  that  it  exercises  some  influence 
upon  the  circulation  in  the  prostatic  plexus  and  in  the  large  pelvic  veins  ^-hich 
occupy  the  recess  betAveen  the  muscle  and  the  viscera,  and  may  also  assist  in  the 
expulsion  of  the  prostatic  secretion  by  direct  lateral  compression  of  the  organ.  In 
the  female  it  may  constrict  the  lower  end  of  the  vagina,  where  the  passage  lies 
between  the  free  borders  of  the  two  muscles. 

The  coccygeus  is  a  thin  and  rather  unimportant  plane  of  muscular  fibres, 
supported  I»y  and  V)lending  intimately  with  the  lesser  sacro-sciatic  ligament.  It 
arises  from  the  inner  surface  of  the  ischial  spine  above  the  levator  ani,  and  passes 
backwards  and  inwards,  expanding  to  Ijccome  inserted  into  the  sides  of  the  coccyx, 
the  lateral  sacro-coccygeal  ligament,  and  the  last  two  pieces  of  the  sacrum.  Its 
visceral  surface  looks  almost  directly  forwards  and  is  covered  by  a  continuation  of 
the  recto-vesical  fascia.    Its  parietal  surface  is  in  contact  with  the  lesser  sacro-sciatic 


PELVIC  FASCIA  AXD  MUSCLES 


10G3 


li<mment.  Its  superior  border  is  separated  from  the  inferior  border  of  the  pyrif(jr- 
niis  by  the  vessels  and  nerves  which  escape  from  the  ])elvis  heUnv  the  latter  muscle. 
Its  inferior  V)order  is  related  to  the  posterior  border  of  the  levator  ani.  The  muscle 
is  Often  pierced  V»v  lilaments  of  the  fourth  and  fifth  sacral  and  coccygeal  nerves, 
which  supply  it  and  form  a  kind  of  plexus  on  its  pelvic  surface.  It  aids  the  levator 
ani  in  drawinu  forwards  the  coccyx.  ,        ,     i   r  , 

The  recto-vesical  fascia  may  be  regarded  as  a  lannna  detached  from  the 
obturator  fasiia  at  the  level  of  the  upper 'l)order  of  the  '  white  line.'  From  this 
point  it  extends  upon  the  pelvic  surface  of  the  levator  ani  and  coccygeus  to  become 
reflected  ui)on  the  viscera  immediately  related  to  the  nmscular  floor  of  the  pelvis, 


Fig.  651.— Muscles  of  the  Flook  of  the  Pelvis.     (W.  A.^ 
(A  i)ortiou  of  the  ischial  and  pubic  houes  sawn  away.) 


Aperture  for 

superior  gluteal 
vessels  and  nerve 


Aperture  for 
sciatic  aiul  puJic 
vessels  and  nerve 


Coccygeal  fibres  of 
levator  ani 


Fibres  of  leva 
tor  ani 


Sphincter  ani 

RECTUM 


•  White  line '  of 
obturator  fascia 


Pubic  attachment 
of  levator  ani 


Tendinous  centre 
of  pennaeum 


namely,  the  prostate  and  bladder  (forming  the  capsule  of  the  former  and  the  'true 
ligaments  '  of  the  latter),  the  vasa  deferentia  and  vesifula3  seminales.  the  lower  part 
of  the  rectum,  and,  in  the  female,  the  vagina  and  uterus.  Its  visceral  portion  is 
easy  to  trace  in  the  immediate  neighbourhood  of  its  reflexion,  but  it  becomes  less 
distinct  as  it  rccedrs  from  this  ]ioint,  and  at  length  is  undcmonstrable. 

The  ischio-rectal  or  anal  fascia,  originating  at  the  white  line  Ix-low  the  fascial 
attaehment  of  tlu-  levator  ani,  closely  invests  the  parietal  or  ischio-rectal  surface 
of  this  muscle,  and  that  of  its  neighbour,  the  coccygeus.  to  blend  in  the  region  of 
the  anus  with  the  deej)  fascial  covering  of  the  external  sjihineter.  In  front  it  passes 
above  the  perina-al  structures,  ])ecoming  continuous  with  the  superior  triangular 
ligament  (a  prolongation  of  the  obturator  fascia),  and  meeting  with  the  recto-vesical 


1064 


URIXA R  Y  AND  REPR OD  VCTl  \ T  OR GAXS 


fascia,  at  tlie  anterior  border  of  tlie  levator  ani;  while  behind  it  extends  backwards 
for  a  variable  distance  to  join  again  with  the  obturator  fascia.  In  this  way  the  two 
fasciae,  obturator  and  ischio-rectal,  close  in  the  ischio-rectal  fossa  above,  in  front, 
and  l)ehind,  but  leave  it  widely  open  below. 


Fig.  652. — Sagittal  Section  through  the  Perix.t;ai.  Ledge  and  Ischiorectal  Fossa 
TO  the  Left  of  the  Middle  Line.     (Diagrammatic.)     (W.  A.) 

PyriformiB 


Obturator  fascia 


Subperitoneal  tissue  — 
Fascia  trausversalis 


OS  PUBIS 
Obturator  internua 


Fascia  lata  of  thigh 
Muscles  of  tliigti 


KER VES 

Great  sacro-sciatio 

ligament 

Lesser  saero-sciatic 

ligament 

Gluteus  mazimus 

Levator  ani  with  its 
fasciae 

Ischio-rectal  fossa 

Deep  periuaeal  interspace 
with  deep  transversus 
perinael 

Superficial  triangular 
ligament 


perfleial  periuaeal  interspace 
with  muscles  of  penis 


The  ischio-rectal  fossae  (figs.  647,  648,  652,  653)  are  two  deep  interspaces, 
one  on  each  side,  left  by  the  divergence  of  the  obliquely  directed  muscles  of  the 
pelvic  floor  (levator  ani  and  coccygeus)  from  the  vertical  pelvic  wall.     Each  fossa 


Fig.  653. 


-Section  showing  the  Ischiorectal  Fossa  in  its  Eelations  to  the 
Pelvic  Viscera.     (W.  A.) 


OS  PUBIS 
Muscles 


Levator  ani  with  reeto-vesical 
and  ischio-rectal  fasciae 


Obturator  internus 


Internal  pudic  vessels  and 
NER  VES  in  obturator  fa.icin 
TUBER  ISCHIl 
Ischio-rectal  fossa  with  its 
anterior  and  posterior  ex- 
tensions 

Gluteus  maximus 


-SYMPHYSIS  PUBIS 

Pubo-prostatie  ligaments 

Prostatic  plexus 
PROSTATE 

Capsule  of  prostate  formed 

by  reeto-vesical  fascia 
Fat 


RECTUM   INVESTED  BY  RECTO- 
VESICAL FASCIA 


is  bounded  externally  by  the  obturator  internus  below  the  level  of  the  white  line, 
the  corresponding  portion  of  the  obturator  fascia  (with  Alcock's  canal  and  the 
pudic  vessels  and  nerves),  and  the  os  innoniinatuni;  and  internally  hj  the  levator 
ani  and  coccygeus  and  the  ischio-rectal  fascia.     Superiorly,  the  vertical  outer  wall 


THE  FERLWEi'M  PROPER  1065 

is  joined  by  the  sloping  inner  wall  where  the  ischio-rectal  fascia  ji>ins  the  oljturator 
fascia,  so  that  the  space  is  angular  y\  in  outline  in  frontal  section.  ,So  far  all 
anatomists  are  agreed,  but  the  remaining  boundaries  rcijuire  further  investigation. 

If  the  linger  be  introduced  into  the  anterior  part  of  the  fossa,  it  will  meet  the  line 
of  junction  of  the  triangular  ligaments  with  the  fascia  of  Colics;  and  above  this  will 
be  found  an  anterior  recess  of  considerable  size  extending  forward  nearly  as  far  as 
the  symi)hysis,  between  the  superior  triangular  ligament  and  the  under  surface  of  the 
levator  ani,  and  limited  internally  by  the  prostate  and  pubo-prostatic  ligaments,  and 
externally  by  the  })ubic  and  ischial  rami.  At  the  l)ack  part  of  the  space  will  l)e  felt 
the  border  of  the  great  sacro-sciatic  ligament,  and  above  this  a  posterior  recess 
running  backwards  for  a  variable  distance  towards  the  sacrum.  Both  of  tlusr  deep 
extensions  are  lined  by  the  ischio-rectal  and  obturator  fasciae,  and  tilled  with  fat  and 
connective  tissue.  The  ischio-rectal  fossa  must  then  be  described  as  an  anvil-  or 
T-shaped  cavity  with  anterior  and  jjosterior  recesses  running  the  one  above  the 
perimeal  ledge,  the  other  above  the  sacro-sciatic  ligaments. 

Contents. — The  ischio-rectal  fossa  is  filled  with  loose  adipose  tissue  continuous 
with  the  subcutaneous  fat  of  the  buttock,  and  traversed  from  Avithout  inwards  l>y 
the  inferior  hiemorrhoidal  In-anches  of  the  pudic  artery,  and  by  the  associated  veins 
and  some  tAvigs  of  the  internal  pudic  nerve  passing  to  the  spliincter  ani  and  adjacent 
skin  and  mucous  meml)rane. 

The  veins  are  usually  somewhat  dilated  near  the  anal  margin,  and  when 
morl)idly  enlarged  constitute  the  condition  known  as  haemorrhoids  or  piles.  Near 
tiie  posterior  border  of  the  triangular  ligaments  the  pudic  vessels  and  nerves  give 
off  their  superficial  perinieal  branches,  which  almost  immediately  enter  the  sujjer- 
ficial  jterina^al  interspace. 

A  small  branch  of  the  fourth  sacral  nerve  may  be  seen  turning  over  the  back  of 
the  space  to  reach  the  anal  integument. 


THE  PERIX^UM  PROPER 

The  perinaeum  proper  (figs.  647,  652),  considered  apart  from  the  portion  of  the 
common  integument  wliich  covers  it  in,  is  a  curious  triangular  ledge  of  tissue 
stretched  almost  horizontally  across  the  angular  interval  between  the  two  ischio- 
pubic  rami.  It  is  pierced  Ijy  the  urethra  (and  also  by  the  vagina  in  the  female), 
and  comprises  three  strong  fascite  which  enclose  within  two  interfascial  spaces  the 
root  of  the  i)enis  with  the  muscles  appended  to  it,  the  compressor  urethra?  muscle, 
Cowper's  glands,  and  a  number  of  vessels  and  nerves.  Above  it  lie  the  prostate 
and  levatores  ani  with  their  fascia^,  and  the  anterior  recess  of  each  ischio-rectal 
fossa. 

The  perinai'al  integument  has  already  been  descriljcd.  On  removal  of  the  skin 
with  its  dartos  and  the  superficial  layers  of  superficial  fascia,  a  deeper  ])lane  of 
fascia  will  be  exposed,  connected  firmly  with  the  ischio-pubic  rami.  This  is  the 
fascia  of  Colles  (the  deep  layer  of  the  superficial  perinteal  fascia),  the  most  su])er- 
ficial  of  the  tliree  true  i>erina?al  fascia\ 

The  fascia  of  Colles  is  a  fibrous  lamina  of  considerable  strength.  It  is  attached 
on  each  side  to  the  lower  margin  of  the  ischio-pubic  ramus  and  to  the  ischial 
tuberosity;  behind,  it  turns  around  the  posterior  border  of  the  sujierficial  transversus 
l»erina'i  muscle  to  fuse  with  the  posterior  borders  of  the  sujierficial  and  deeji  tri- 
angular ligaments  and  form  the  free  border  of  the  '  perina'al  ledge ' ;  anteriorly,  it 
becomes  continuous  with  the  external  fascial  investment  of  the  scrotum  and  the 
fascial  covering  of  the  ])enis. 

It  is  l)etween  this  layer  and  the  inferi(^r  triangular  ligament  that  extravasation 
of  urine  is  esi)ecially  prone  to  occur  in  ru]>ture  of  the  urethra.  From  its  connec- 
tions it  will  be  seen  that  the  extension  of  the  fluid  would  l»e  arrested  ))osteriorly 
and  laterally  by  the  connection  of  the  fascia  of  Colles  with  the  triangular  ligaments 
and  with  the  ischio-pul)ic  rami;  but  it  spreads  freely  beneath  the  integuments  of 
the  scrotum  and  of  the  penis  as  far  as  the  neck  of  the  glans,  and  to  the  surface  of 
the  abdomen.  On  the  trunk,  it  may  run  in  an  upward  direction  even  to  the  axilla, 
but  it   is  prevented  from  descending  below  the   groin  by  the  connection   of  the 


1066 


URINARY  AND  REPRODUCTIVE   ORGANS 


abdominal  fascia  with  Poiipart's  ligament  and  to  the  margin  of  the  saphenous 
opening. 

Superficial  perinaeal  interspace  (figs.  647,  652,  654).— Detaching  the  fascia 
of  Colles  from  its  connections,  the  dissector  oi)ens  the  superficial  interfascial  space 
and  exposes  its  contents,  nameh^: — (1)  The  crura  of  the  corpora  cavernosa  Avith 
the  ischio-cavernosi ;  (2)  the  bulb  of  the  corpus  spongiosum  with  the  bulbo- 
cavernosi;  (3)  the  ca])riciously  scattered  fil)n'S  of  the  superficial  transversi 
perineei ;  (4)  the  arteries  of  the  corpora  cavernosa  and  the  dorsal  arteries  of 
the  penis  witli  their  associated  veins  and  lymphatics;  (5)  the  dorsal  nerves 
of  the  penis;  and  (6)  the  superficial  perinaeal  vessels  and  nerves.  The  roof 
of  the  space  (the  so-called  floor)  is  formed  by  the  inferior  triangular  ligament. 

The  transversi  perin^ei,  the  crura  penis  Avith  the  ischio-cavernosi,  and  the  bulb 
with  the  bulbo-cavernosi,  have  been  already  described  (pages  1034,  1035).  .Each  of 
the  muscles  named  has  a  fascial  sheath  of  its  own,  distinct  from  the  fascia  of  Colles. 

The  artery  of  the  corpus  cavernosum  enters  the  crus  immediately  after 
piercing  the  inferior  triangular  ligament;  the  dorsal  artery  of  the  penis,  reaching 
the  interfascial  space  more  anteriorly  with  the  dorsal  nerve,  runs  forwards  to  the 
dorsum  of  the  united  cor]iora  cavernosa  to  take  its  place  between  the  vein  and 
nerve;  the  superficial  perinaeal  vessels  and  nerve  given  off  from  the  internal 


Fig.  654. — Diagram  of  the  Superficial  and  Deep  Triangulae  Ligaments. 


Subpubic  ligament  with  aperture  for 
dorsal  vein  of  the  penis 

Apertures  for  dorsal  artery  and  ( 
nerve  of  the  penis  \ 


Crus  penis 
Aperture  for  artery  of  corpus 
carernosii/ii 
Superficial  triangular  ligament 
Ischio-eavernoBus,  or  erector  penis 
Aperture  for  artery 
to  bulb 
Urethral  aperture 
Aperture  for  Cow- 
per's  duct 
Position  of  bulb 


Apertures  for  super- 
ficial perineeal 
vessels  and  nerve 


Fascia  of  Colles. 
turned  backwards 


DORSAL  KERVE 
~__  Anterior  layer  of  triangular 
^«                      ligament 
— jS-  Dorsal  artery  of  penis 
\  Deep  triangu- 

lar ligament 
Artery  of  corpus 
cavernosum 

A  rten/  to  bulb 


Piidic  veins 
DORSAL  NERVE 

POSITION  OF  COWPER'S 
GLAND 

Tnternal  pudic  artery 


Posterior  border  of 
perinaeal  ledge 
(junction  of  trian- 
gular ligaments 
with  fascia  of 
Colles; 


pudic  trunks  in  the  ischio-rectal  fossa  enter  the  interfascial  space  near  the  free 
border  of  the  perinatal  ledge.  These  divide  into  two  sets  of  branches,  posterior  or 
deep,  to  the  penile  muscles,  and  anterior  or  superficial  to  the  scrotal  and  perina?al 
integument;  the  latter  piercing  the  fascia  of  Colles  and  the  scrotal  investment  con- 
tinuous with  it  to  reach  the  skin. 

The  superficial  perinteal  interspace  then  may  be  said  to  contain  the  root  of  the 
penis,  with  the  muscles,  vessels,  and  nerves  connected  with  it. 

Superficial  or  inferior  triangular  ligament  ( '  the  anterior  layer  of  the  triangu- 
lar hgainent ' )  (fig.  652). — On  removing  the  contents  of  the  superficial  interspace  the 
dissector  exposes  the  under  surface  of  the  inferior  or  superficial  triangular  ligament. 
This  structure  forms  almost  a  horizontal  plane  in  the  erect  posture  of  the  l)ody,  and 
consists  of  strong  bands  of  fi])rous  tissue,  running  for  the  most  part  in  a  transverse 
direction  across  the  sul)pubic  arch  to  be  attached  firmly  to  the  ischio-pul)ic  rami 
above  the  line  of  attachment  of  the  fascia  of  Colles  and  of  the  penile  muscles. 
Anteriorly,  it  is  separated  from  the  subpul)ic  ligament  l)y  an  interval  which  trans- 
mits the  dorsal  vein  of  the  penis;  posteriorly,  it  ])lends  with  the  fascia  of  Colles 
and  with  the  superior  triangular  ligament  to  form  the  hinder  border  of  the  perinaeal 
ledge;    and  superiorly  it  is  intimately  related  to  the   deep  transversus  perinsei 


THE  PERiy.EUM  PRO  PER 


1007 


muscle.  IXispicrcedhy: — (1)  Tlie  urethra,  aliout  an  inch  and  a  (juarter  Ixldw 
the  symphysis;  (2)  the  ducts  of  CowiDer's  ghmds,  one  on  each  side  of  the  posterior 
])art  of  the  urethral  openings;  (3)  the  arteries  of  the  hulh,  somewhat  external  to 
the  last;  (4)  the  arteries  to  the  corpora  cavernosa,  more  anteriorly  and  close  to  tlie 
lateral  attachment  of  the  ligament;  (5)  the  dorsal  arteries  and  nerves  of  the  penis, 
at  the  margins  of  the  ligament  near  its  apex.  The  dorsal  vein  with  some  accom- 
panying lymphatics  runs  through  the  interspace  between  the  triangular  and  subpubic 
ligaments  (fig.  654). 

Deep  pehnaeal  interspace  (figs.  620,  652,  654). — If  the  superficial  triangular 
ligament  be  now  detached,  the  deep  perinreal  interspace  will  be  laid  open.  This 
space  is  somewhat  wedge-shaped  in  sagittal  section,  in  consequence  of  the  manner 
in  which  the  two  triangular  ligaments  approach  each  other  before  their  union 
at  the  posterior  border  of  the  perinieal  ledge.  It  is  occupied  by  the  following 
structures : — 

(1)  The  membranous  urethra,  surrounded  by  its  annular  sphincter  of  smooth 
muscular  fibres. 

(2)  Cowper's  glands,  seen  as  two  white  pea-like  bodies,  one  on  each  side  of 
the  posterior  segment  of  the  urethra.     Their  ducts  pierce  the  superficial  ligament. 


Fig.  655. — Vertical  Frontal  Section  of  the  Pelvis,  showing  Fasci.e. 
(Modified  from  Braane.) 


UVUU  VESICA 

PROSTATE 
VERUMONTANUM 

Levator  ani 

MEMBRANOUS  URETHRA 

Pmlic  vessels 

PUBIC  ARCH 

Fascia  of  ischio- 


BULBO-CAVERNOSUS 

WITH   ITS  FASCIA 

Inteeument  of 

perinsEum 


Subperitoneal  fat 

Obturator  internus 
Isehio-reetal  fascia 

OS    NNOV^I^ATUM 
Recto-vesical  fascia, 
parietal  and  visce- 
ral layers 
Obturator  fascia 
Obturator  mem- 
brane 
ISCHO-RECTAL  FOSSA 

'i^ Deep  triangular  lig. 

Deep  transversus 

perinaei 
Superficial  triangu- 
lar ligament 

Muscles  of  thigh 

Ischio-cavernosus 


Muscles  of  thigh 


(3)  The  internal  pudic  arteries,  lying  close  to  the  ischio-pubic  rami  imbedded 
in  the  fibres  of  origin  of  the  compressor  urethrse  muscle,  giving  off  each  an  artery 
to  the  bulb  as  well  as  some  twigs  to  Cowper's  gland  and  to  the  muscular  tissue 
surrounding  the  urethra,  and  terminating  by  division  into  the  artery  of  the  corpus 
cavernosum,  and  the  dorsal  artery  of  the  penis.  These  branches  with  the  associated 
veins  have  been  seen  to  pass  through  the  superficial  triangular  ligament  intt^  the 
superficial  perinjeal  interspace. 

(4)  The  pudic  veins,  accompanying  the  arteries.  Their  tributaries  form  a 
plexus  around  the  urethra,  and  in  the  substance  of  the  fibres  of  the  deep  trans- 
versus perina-i.  This  plexus,  which  is  often  largely  developed  in  old  persons, 
receives  the  veins  of  the  corpus  spongiosum  and  corpora  cavernosa,  and  commu- 
nicates freely  with  the  dorsal  vein  of  the  penis,  and  through  this  with  the  prostatic 
plexus. 

(5)  The  pudic  lymphatics,  accompanying  the  veins  and  terminating  in  the 
pelvic  glands. 

(6)  The  dorsal   nerves  of  the  penis,  the  terminal  branches  of  the  internal 


1068  URINARY  AND  REPRODUCTIVE  ORGANS 

pudic  nerves,  accompany  the  arteries;  each  nerve  gives  off  filaments  to  the  deep 
transversus  perini^i,  and  tlien  pierces  the  fore  part  of  the  superficial  triangular 
ligament  Avith  the  dor.-^al  artery. 

(7)  The  deep  transversus  perinaei,  compressor  urethrae,  or  muscle  of 
Guthrie. — The  muscular  tissue  of  the  deej)  perinatal  space  has  l)een  a  source  of 
great  confusion  owing  to  the  multiplicity  of  the  names  which  liave  been  assigned 
to  various  portions  of  it;  but  the  description  given  ])y  Henle  may  ])o  accepted  as  at 
once  the  simi)lest  and  the  most  accurate.  The  transversus  perinaei  profundus 
of  Henle  is  closely  connected  with  the  superior  and  inferior  triangular  ligaments. 
It  arises  from  the  inner  surface  of  the  ischio-pubic  ranuis,  by  tendinous  bundles 
which  separate  to  form  a  kind  of  channel  for  the  pudic  vessels  and  dorsal  nerve  of 
the  penis,  close  to  the  bone.  From  this  origin  the  greater  part  of  the  fibres  run 
across  the  subpubic  angle  in  a  transverse  direction  in  front  of  and  behind  the  mem- 
branous urethra,  enclosing  Cowper's  glands  and  the  deep  veins  of  the  penis,  and 
join  a  more  or  less  indistinct  median  raphe;  while  others  pass  more  or  less 
obliquely  forwards  in  front  of  the  urethra  and  behind  the  dorsal  vein  to  become 
attached  to  the  pubic  ramus  on  the  side  opposite  to  the  bony  attachment.  A  small 
accessory  bundle  (the  '  sagittal  layer  '  of  Henle)  may  sometimes  be  found  running 
directly  forwards  to  become  inserted  into  the  upper  surface  of  the  bull)  and  into 
the  connective  tissue  between  the  corpora  cavernosa;  and  the  name  '  muscle  of 
Wilson '  has  been  given  to  a  few  fasciculi,  often  difficult  to  demonstrate,  running 
from  the  subpubic  ligament  to  the  membranous  urethra. 

The  arrangement  of  the  fibres  differs  considerably  in  different  sul)jects,  and 
much  complexity  has  l^een  introduced  into  the  study  of  the  muscle  by  the  artificial 
segregation  of  certain  of  its  parts  under  special  names,  such  as  levator  vn-ethra3, 
constrictor  urethra,  etc. 

Its  action  is  partly  to  compress  the  membranous  urethra  and  thus  assist  the 
expulsion  of  urine  and  semen,  and  partly  to  intercept  the  flow  of  blood  through 
the  veins  of  the  penis,  and  so  aid  in  erection.  It  also  exercises  compression 
upon  Cowper's  glands,  and  effects  the  discharge  of  their  secretion  during  seminal 
emission.     It  is  supplied  by  a  branch  from  the  dorsal  nerve  of  the  penis. 

The  deep  or  superior  triangular  ligament  (figs.  650,  652,  654)  is  in  some  sort 
a  prolongation  of  the  obturator  fascia  across  the  pubic  arch,  the  continuity  of  the 
two  fasciae,  however,  l?eing  interrupted  b}'  the  attachment  of  their  deep  fibres  to 
the  inner  edges  of  the  ischio-pul:)ic  rami.  Inferiorly  it  is  in  intimate  relation  with 
the  deep  transversus  perinaei;  while  superiorly  it  forms  on  each  side  the  floor  of 
the  anterior  extension  of  the  ischio-rectal  fossa;  and  in  the  middle  line  it  is  sepa- 
rated from  the  apex  of  the  prostate  by  a  prolongation  of  recto-vesical  fascia,  and  l)v 
a  layer  of  smooth  muscular  fibre,  the  prerectalis  of  Henle,  in  which  end  the 
greater  part  of  the  anterior  longitudinal  filires  of  the  rectum. 

It  is  pierced  by  the  pudic  artery  and  vein  and  the  dorsal  nerve  of  the  penis. 
The  dorsal  vein  of  the  penis  passes  between  it  and  the  subpubic  ligament. 


THE  FEMALE  PERINEUM 

The  female  perinaeum  (fig.  656)  differs  from  that  of  the  male,  partly  in  the 
perforation  of  the  whole  of  its  fascial  and  muscular  structures  in  the  middle  line  by 
the  vulvo-vaginal  passage,  and  partly  in  the  adaptation  of  the  perinatal  muscles  to 
the  modified  conditions  of  the  external  genital  apparatus.  The  corpora  cavernosa 
penis  are  represented  by  the  relatively  diminutive  corpora  clitoridis  ;  the  ischio- 
cavernosi  are  proportionately  reduced  in  size,  but  differ  in  no  otlier  material  respect; 
the  cor))US  spongiosum  is  divided  into  two  lateral  segments,  which  are  represented 
by  the  bulbi  vestibuli  and  partes  intermediales  ;  and  the  two  Inilbo-cavernosi 
are  sc])arate,  and  ajipear  in  an  atteininted  form.  s]n-ead  over  the  erectile  tissue  as 
an  attenuated  plane  of  filjres,  the  compressor  vaginae,  which  is  often  difficult  to 
recognise  on  dissection;  while  the  meilian  ra])he  uniting  tlie  two  nniscles  in  the 
male  gives  place  to  the  genital  fissure.  Tlie  superficial  transversi  perinaei 
differ  only  in  size  from  those  of  tlie  male;  1)ut  the  deep  transversus  perinaei  is 
of  course  cleft  by  the  vagina,  and  its  fil)res  are  relatively  thin   and  weak  and  in 


THE  MAMM.E 


1069 


great  ]t;irt  unstripi'il.    Th(^  glands  of  Bartholin,  althouj^h  morphologically  identical 
with  Cowpcr's  <rlaiKls,  arc  less  deeply  placed. 

The  greater  development  of  the  connective-tissue  structures  between  the  genital 
canal  and  the  third  stage  of  the  rectum,  leading  to  the  formation  of  the  perinaeal 
body,  is  also  a  peculiarity  of  the  female  (tig.  (>1*J).  The  perinatal  body  is  triangular 
in  sagittal  section,  and  l)ounded  in  front  l)y  the  vulvo-vaginal  wall,  behind  by  the 
anterior  wall  of  the  rectum,  and  below  Ity  tlie  integument  between  the  posterior 


Flo.  t;5().  — I)I.\GKA.MM.\TIC   REPRESEXT.VTION   OF  THE   PeRIN.EAL  StKUCTUKES  IX   THE  Fe.MAI.E. 


ISCHIO-PUBIC  ARCH 


CRUS  CUTORIDIS  WITH 
ISCHIO-CAVERNOSUS 


BULBO-CAVERNOSUS 
COVERING  BULBUS 
VESTIBULI 


Superficial  trian- 
gular ligament 


/  ^  I    ^  ;-;_    -. 


CLANS  CUTORIDIS 
WITH  PREPUCE 


PARS  INTERMEDIALIS 


'^        Mucous  membrane 
of  vestibule 


MEATUS  URINARIUS 


BULBUS  VESTIBUU 


GLAND  OF  BARTHOLIN 


Sphincter  ani 


vulvar  commissure  and  the  anal  aperture.  It  consists  of  a  strong  meshwork  of 
connective  tissue  freely  intermingled  with  fibres  of  elastic  tissue  and  un.^trijted 
muscle,  and  is  traversed  by  the  various  muscles  which  meet  at  the  tendinous 
centre  of  the  perinseum.  It  becomes  stretched  to  a  remarkable  degree  during  the 
]»as.sage  of  tlie  child's  head  in  labour,  but  is  saved  from  rupture  by  its  strength 
and  elasticity. 


THE  JIAJIJLE 


The  mammary  glands  are  two  ]tt<toral  organs  wliich  secrete  the  milk  in  tii<' 
female,  but  remain  permanently  rudimentary  and  functionless  in  the  male. 

The  female  mamma  Tin  which  tenn  is  included  the  gland  with  its  investing 
integumentary  structures)  is  .seen  in  its  typical  adult  form  as  a  more  or  less  hemi- 
spherical eminence  upon  the  front  wall  of  the  chest  over  the  third,  fourth,  hfth. 
and  sixth  ribs,  and  extending  transversely  from  the  border  of  the  sternum  to  the 
anterior  margin  of  the  axilla.  It  is  surmounted  near  its  middle  by  a  small  wart- 
like process,  the  mammilla  or  nipple,  which  lies  in  the  centre  of  a  circular  area 
of  altered  skin  call(  d  the  areola. 

The  secreting  organ  consists  of  an  aggregation  of  ten  to  sixteen  eom]»ound 
racemose  glands,  the  ends  of  which  oi)en  separately  upon  the  summit  of  the  nipple. 
These  component  elements  are  quite  distinct  in  the  di.-:sected   breast  as  so  many 


1070 


URIXARY  AXD  REPRODUCTIVE  ORGANS 


lobes  of  somewhat  ]iynniiidal  form,  with  their  bases  at  the  periphery  and  the  apices 
converging  towards  the  mannnilla.  They  are  held  together  and  sui)i)()rted  by  a 
fibrous  capsule,  whicli  sends  inwards  deep  interlobular  processes,  to  form  a  loculated 
framework  for  the  glandular  elements;  and  superficial  jn-ocesses  running  to  the 
skin  and  enclosing  supra-mammary  fat-containing  spaces  or  adipose  fossae.  The 
posterior  asjiect  of  the  capsule  also  encloses  other  fat-spaces  (retro-mammary)  and 
is  attached  to  the  deep  fascia  over  the  pectoralis  major  by  loose  connective  tissue, 
the  bands  of  which  may  be  separated  by  large  lymph-si)aces,  the  so-called  'sub- 
mammarv  liursre.'  Finally,  isolated  collections  of  fat  ( intra-mammary)  may  be 
found  buried  amidst  tlie  "lobules  of  the  gland.  It  is  the  fat  lying  in  the  sub- 
cutaneous adipose  fossic  and  between  the  gland  lo))ules  that  gives  smoothness  and 
uniformity  of  surface  to  the  breast,  and  when  it  becomes  al)sorl)ed  during  lactation 
or  in  conditions  of  emaciation,  the  lobular  structure  of  the  gland  is  distinctly 
manifest. 

Structurally  each  of  the  component  lobes  may  be  regarded  as  a  modified  sebaceous 
gland,  and  hence  an  appendage  of  the  skin.  Each  is  provided  with  a  single 
excretory  tube  (lactiferous  or  galactophorous  duct),  Avhich  on  approaching  the 


Fig.  657.— The  Female  Mamma  dueixg  Lactation.     (After  Luschka.) 


Ampulla  of  duct 


Acini  of  gland 


Y  Adipose  loculus 


Gland  loculus 


nii)ple  is  dilated  into  a  sinus  or  ampulla,  and  finally  ends  by  a  constricted  orifice 
at  the  ajiex  of  the  nipple.  The  acini  and  smaller  tubes  are  lined  with  cubical 
epithelium,  which  becomes  replaced  by  columnar  cells  in  the  excretory  ducts. 

Accessory  glands  of  small  size— half  a  line  to  two  lines  in  diameter,  and  to  the 
number  of  five  to  fifteen — are  normally  found  under  the  skin  of  the  areola,  and 
open  on  to  the  summit  of  the  nip|»le. 

The  gland  as  a  whole  is  not  circular  in  outline,  l)ut  usually  presents  three  cusjis 
— one  towards  the  sternum,  scmietimes  overlap])ing  the  bone;  the  others  towards 
the  axilla,  one  above  and  the  other  below;  smaller  extensions,  moreover,  pass  from 
the  base  of  tlio  gland  to  the  deep  fascia,  and  may  pierce  it  and  lie  upon  or  in  the 
fibres  of  the  pectoral  muscle  (Heidenhain).  These  processes  are  commonly  left 
behind  in  amputation  of  the  l^-east,  and  may  form  nuclei  for  recurrent  growth  in 
malignant  disease. 

The  mammilla  and  areola  are  specially  modified  ]iortions  of  the  mammary 
integument.  The  mammilla  is  placed  a  little  internal  and  inferior  to  the  centre 
of  the  gland,  and  ]K)ints  forwards  and  outwards.  It  is  of  somewhat  conical  form, 
averaging  about  half  an  inch  in  length,  and  terminating  bv  a  rounded  extremity 
which  is  pierced  by  the  orifices  of  the  lactiferous  ducts.     It"  is  of  pinkish  colour. 


THE  MAMM.E  ItDTl 

and  is  capable  of  a  kind  of  erection  undtr  the  influence  of  cold,  mechanical 
stimulus,  or  mental  emotion.  In  some  jjcrsons  it  is  normally  retracted  into  a 
dei»ression  of  the  integument,  and  only  projects  in  response  to  stimulation. 

The  areola  is  ahout  an  inch  in  diameter,  and  is  characterised  l»y  its  pifrmentation, 
the  delicacy  of  its  texture,  the  absence  of  subcutaneous  fat,  the  large  development 
of  its  sebaceous  and  accessory  milk  glands,  and  its  contractility  under  the  inllu- 
enees  wliich  produce  erection  of  the  nipple.  It  is  pink  in  the  virgin,  l)ut  during 
]»r<'gnancy  and  lactation  assumes  a  brownish  shade.  The  accessory  glands,  slightly 
marked  in  the  virgin,  form  distinct  prominences  after  impregnation  (tubercles  of 
Montgomery). 

The  contractility  of  tlie  nii)i)le  and  areola  is  due  t(^  the  presence  of  circular 
and  radiating  fibres  of  unstriped  muscle  in  the  subcutaneous  tissue,  the  former 
passing  into  the  substance  of  the  nipple,  and  forming  a  network  around  the  lactif- 
erous ducts.  The  circular  tibres  by  their  contraction  cause  the  nipple  to  project; 
the  radiating  filjres  retract  it. 

Variations  according  to  age  and  functional  activity. — At  birth  the  gland  is 
only  about  onivfifth  to  onc-tliinl  of  an  inch  in  diameter.  The  nipple  with  its 
dartos  is  well  formed,  and  the  secreting  structure  is  represented  by  slightly  ramified 
ducts  which  contain  a  milky  fluid.  Growth  is  slow  up  to  the  time  of  jaibcrty; 
after  tliis.  development  progresses  rapidly,  l)ut  no  distinct  indication  of  subdivision 
into  lobes  is  present  until  impregnation  takes  place.     Some  sliglit  engorgement  of 

Fig.  658.— Develop.mext  of  the  Mamma  of  the  Female  Embryo. 
(7  inches  in  length  X  70.)     (After  Langer.) 


j^m 


the  breast  may,  however,  occur  at  the  menstrual  i)eriod,  when  a  yellowish  glutinous 
secretion  may  sometimes  be  expelled  from  the  ducts.  In  pregnancy  and  during 
lactation  the  evolution  of  the  gland-structure  is  remarkably  active.  The  whole 
breast  enlarges,  the  superficial  fat  undergoes  alisorption,  the  vessels  become  dilated 
and  their  walls  thickened;  the  areola  and  nipple  increase  in  size,  and  the  former 
becomes  more  or  less  deeply  pigmented.  After  the  end  of  lactation  the  lireast 
l)ecomes  smaller,  but  seldom  resumes  its  original  condition  of  smoothness,  firmness, 
and  elasticity,  and  some  traces  of  the  pigmentation  of  the  areola  remain  permanent. 
In  old  age  the  glandular  structures  atn>phy. 

The  male  breast  diflfers  fn.m  that  of  the  female  in  the  early  arrest  of  its  ev(tlu- 
tion.  It  ranges  in  diameter  from  a  third  of  an  inch  to  an  inch,  and  posses.ses  an 
areola  and  a  nipple,  the  former  often  beset  with  hairs.  It  is  usually  jilaced  over  the 
fourtli  intercostal  sjjace,  a  little  internal  to  tiie  l»order  of  the  pecttjrahs  major,  but 
its  petition  is  very  variable,  and  the  two  glands  are  often  unsynnnetrical.  A  tem- 
])orary  engorgement  occasionally  appears  in  early  adult  life,  and  may  lead  to 
inHammatory  complications. 

Vessels  and  nerves. — The  arteries  are  derived  from  the  internal  mammary 
through  the  si'cond.  tliinl.  and  fourth  intercostal  spaces,  and  from  the  thoracic 
In-anches  of  the  axillary.  The  chief  supi)ly  is  given  to  the  perforating  branclu-s  of 
the  internal  mannnary,  but  the  external  mannnary  l)ranch  of  the  axillary  artery  may 
be  of  large  size  in  the  female. 


1072  URINARY  AXD  REPRODUCTIVE  ORGANS 

The  veins  terminate  in  the  corresponding  trunks.  The  superficial  veins  become 
visibly  enlarged  during  ])regnancy  and  lactation. 

The  lymphatics,  originating  in  the  cellular  interspaces  of  the  gland,  form 
trunks  which  accomi)any  the  veins;  the  majority  terminating  in  the  costal  group 
of  axillary  glands,  the  others  in  the  retrosternal  chain.  The  integument  of  the 
nipple  and  areola,  as  well  as  the  rest  of  the  skin  over  the  mamma,  is  richly  supplied 
Avith  lymphatics,  and  as  these  connnunicate  freely  with  the  vessels  of  the  other 
side  across  the  middle  line,  infection  may  be  conveyed  to  the  glands  of  the  side 
opposite  to  the  primary  seat  of  disease  (Volkmann).  In  cancer  of  the  breast  the 
deep  cervical  glands  about  the  subclavian  vessels  may  become  implicated  by  exten- 
sion from  the  axilla  as  the  disease  advances. 

The  nerves  are  derived  from  the  supraclavicular  branches  of  the  cervical  plexus, 
and  from  the  intercostals.  The  glandular  twigs  are  traced  by  Eckhard  'to  the 
fourth,  iifth,  and  sixth  intercostals. 

Development. — The  breast  appears  about  the  seventh  week  of  foetal  life  as  a  circular  epider-  ■ 

mic  riJge,  enclosing  a  central  depression,  the  cells  of  which  grow  inwards  and  form  branching  ■ 

tubular  ducts  that  radiate  beneath  the  nipple  (fig.  658).  * 

Abnormalities. — Small  supplementary  lacteal  glands,  in  addition  to  the  normal  accessory 
structures  beneath  the  areola,  are  frequently  present  around  the  margin  of  the  principal  gland, 
and  may  be  found  in  front  of  the  sternum,  in  the  axilla,  and  below  the  clavicle,  and  there  is  reason 
to  believe  that  many  of  the  adenomata  and  cancers  take  origin  in  these  redundant  structures 
(Roger  Williams).  Besides  these,  large  supernumerary  mammre,  having  all  the  characters  of  the 
typical  organs,  have  also  been  met  with  in  various  situations — in  the  axilla,  over  the  back,  the 
abdomen,  and  even  on  the  thigh.  These  are  in  all  probability  atavistic.  Absence  of  the  mamma 
is  extremely  rare. 

The  nipples  may  be  double,  or  even  triple  on  each  breast,  or  may  be  wanting  altogether. 

In  a  few  instances  an  abnormal  development  of  the  gland  tissue  has  been  known  to  occur  in 
the  male,  and  milk  has  been  secreted  in  suificient  quantity  to  nourish  an  infant.  A  slight  and 
temporary  enlargement  of  the  gland  about  the  period  of  puberty  is  not  infrequent. 


THE  SKIN 

Bv  WILLIAM  ANDERSON,  F.R.C.S. 


SURGEON    TO    AND    LECTURER    ON    ANATOMY    AT    ST.    THOMAS'S    HOSPITAL;    PROFESSOR    OF    ANATOMY    IN    TUE    ROYAL 

ACADEMY  ;    EXAMINER   IN   SURGERY    AT   THE   UNIVERSITY   OF   LONDON    AND   ROYAL 

COLLEGE  OF   SURGEONS  OF   ENGLAND 


The  skin  is  a  niemhranous  investment  forming  the  entire  external  surface  of  tlie 
body  and  its  memliers,  and  is  continuous  at  certain  points  with  the  internal  lining 
of  the  alimentary,  respiratory,  and  urinogenital  canals. 

Its  extent  has  been  estimated  at  al)OUt  15,0(X)  square  cm.  in  an  adult  malf  of 
medium  size  (.Sappey).  In  thickness  it  varies  considerably  in  different  ]K)rtioiis  of 
the  surface,  ranging  from  -V  to  tV  ^^  ^^i  inch  (0-5  to  2  nnn. ),  but  ap])ears  to  be  pro- 
portionate to  the  amount  of  pressure  or  friction  to  which  the  parts  are  habitually 
subjected.  Thus  it  is  thickest  ui)(m  the  nape,  back,  and  shoulders,  and  on  the 
palms  and  soles,  while  on  the  front  of  the  trunk  and  on  the  dorsal  as]X'ct  of  tlie 
hands  and  feet  it  is  relatively  thin.  It  is  highly  elastic  and  is  capable  of  stretch- 
ing to  a  considerable  extent  without  rui)ture  of  its  continuity,  and  of  regaining 
its  original  condition  when  the  extending  force  is  removed.  This  quality  is  es]H'- 
cially  remarkal)le  in  the  distension  of  the  integuments  over  a  slow-growing 
tumour.  Its  colonr  is  due  partly  to  pigmentation,  partly  to  the  blood  within  its 
vessels.  The  amount  of  ])igment  varies  with  race,  sex,  age,  and  with  ex])0sure  to 
sun  and  air;  and  is  normally  greater  in  certain  portions  of  tlie  skin  (axilla,  scrotum, 
vulva,  mammary  areola",  etc.  )  than  on  the  rest  of  the  sm-face,  besides  Iteing  subject 
to  ]>hysiological  and  pathological  variations.  Its  surface  is  for  the  most  jiart 
smooth,  but  is  diversitied  l)v  the  orifices  of  glands,  by  the  growth  of  hair,  and  bv 
various  furrows  and  elevations.  Permanent  linear  ridges  are  present  upon  the 
palms  and  soles,  and  flexor  surfaces  of  the  digits;  and  tem])orarv  pa])ular  elevations 
(' goose-rtesh  ' )  may  appear  in  the  positions  of  the  hair-foil iele<s  under  the  inthi- 
ences  of  cold  or  emotion.  The  ])ermanent  ridges,  corresponding  to  rows  of  dermic 
papilla',  have  an  arrangement  of  a  pecidiar  kind  over  the  front  of  the  terminal 
joints  of  the  lingers,  and  their  variations  liave  been  classified  in  such  a  manner  as  to 
prove  valuable  for  ])in"posesof  identiMc;iti<)n.  In  jirimitive  races  the  inqirint  of  the 
thumb  has  hern  usc(l  as  a  kimi  of  signature. 

Tile  furrows  or  depressions  are  of  several  kinds.  The  most  jiermanent  are 
those  which  separate  the  i)apillary  ridges  on  the]>alni.  IJelaxed  ])ortionsof  theskin, 
such  as  that  of  the  back  of  the  hand  during  extension  of  the  wrist  and  fingers,  are 
crossed  by  a  multitude  of  tine  decussating  wrinkles,  which  disajtpcar  when  the  sur- 
face is  stretched;  other  lines  of  a  more  constant  type  are  produced  l)y  joint  flexion, 
such  as  thovse  in  front  of  the  wrist;  others  are  caused  by  contraction  (»f  voluntary 
or  involuntary  muscles,  such  as  the  lines  of  exjiression  on  the  forehead  space,  the 
transverse  wrinkles  on  the  scrotum,  and  the  radiating  folds  around  the  anus,  the 
lines  then  running  at  right  angles  to  the  direction  of  the  muscular  fibres  by  which 
they  are  produced;  lastly,  a  complex  wrinkHng  of  the  skin  appears  in  old  age  or  in 
the  course  of  exiiausting  disease.««\  partly  as  a  result  of  lo.«s  of  elasticity  of  the 
structures  and  partly  from  altsorjition  of  the  cutaneous  and  subcutaneous  fat. 

In  addition  to  these  linear  depressions  are  more  rotuxled  forms,  called  dimples, 
68  1(>7"; 


1074  THE  SKIN 

some  of  wliich,  as  those  on  the  chin  and  cheeks  and  at  the  uhiar  liorder  of  tlie 
palm,  correspond  to  the  points  of  attachment  of  muscular  fibres  into  the  deep  sur- 
face of  the  skin,  and  are  made  evident  by  the  contraction  of  tliese  fibres;  while 
others  depend  upon  the  attachment  of  the  skin  by  fibrous  bands  to  the  l>ony  emi- 
nences, as  of  the  elbow,  shoulder,  vertel)ra3,  and  posterior  iliac  spines,  and  are  seen 
only  when  the  subcutaneous  adipose  tissue  is  well  developed. 

The  skin  is  separated  from  the  superficial  bones  and  muscles,  etc. ,  by  a  subcu- 
taneous structure,  comprising  white  fibrous  and  elastic  tissues,  fat,  and,  in  certain 
situations,  layers  of  striped  or  unstriped  muscle.  The  subcutaneous  fil)rous  tissue 
over  the  greater  part  of  the  liody  is  arranged  in  two  planes,  known  as  the  superficial 
and  deep  layers  of  the  superficial  fascia,  separated  by  a  layer  of  fat.  It  is  closely 
blended  with  the  deep  aspect  of  the  skin,  but  only  loosel}'  united  to  the  deep  -fascia 
investing  the  nuiscles,  and  permits  the  cutaneous  and  subcutaneous  structures  to 
move  more  or  less  freely  over  the  deep  parts.  In  some  situations,  moreover,  where 
the  integument  is  exposed  to  repeated  friction  over  sul)jacent  l)ones  or  other  hard 
structures,  its  movements  are  facilitated  by  the  development  of  sac-like  intersjnices 
in  the  subcutaneous  tissue,  called  bursse.  Exceptions  to  this  rule  of  mobility  of 
integument  are  found  in  the  head  and  face,  where  the  skin  is  intimately  con- 
nected with  the  subjacent  muscular  and  tendinous  tissues,  and  in  the  palms  and 
soles,  where  it  is  firmly  attached  to  the  deep  fascia. 

The  subcutaneous  fat  varies  considerably  in  amount  and  character  in  different 
parts  of  the  body.  It  is  entirely  absent  on  the  penis  and  scrotum  and  is  largely 
developed  over  the  nates,  palms,  and  soles,  where  it  serves  as  pads  or  cushions.  In 
the  scalp  it  appears  as  a  single  uniform  layer  of  ovoid  lobules  between  the  derm 
and  the  aponeurosis  of  the  occipito-frontalis  muscles;  on  other  parts  of  the  surface 
it  is  somewhat  unequally  distributed,  and  shows  a  tendency  to  accumulate  in  appar- 
ent disproportion  in  certain  localities,  as  on  the  abdomen,  over  the  symphysis 
pubis,  about  the  mammae  in  females,  etc.  Everywhere,  except  perhaps  on  the 
scalp,  it  may  undergo  rapid  and  visible  increase  or  decrease  under  the  influence  of 
changes  of  nutrition. 

The  subcutaneous  planes  of  striped  muscle  are  comparatively  scanty  in  man 
when  compared  wuth  the  great  panniculus  carnosus  of  the  lower  mammalia.  They 
are  best  represented  by  the  platysma  myoides  on  the  neck.  Unstriped  muscular 
fibre,  present  in  all  parts  of  the  skin  as  an  appendage  to  the  hair-follicles  and 
SL'l)aceous  glands,  is  found  also  in  some  parts  of  the  sul^cutaneous  tissue,  as  in  the 
scrotum  and  perinseum,  around  the  anus,  in  the  mammilla,  and  beneath  the 
mammary  areola. 

Structure  of  the  skin. — The  skin  is  separable  into  two  distinct  layers — a 
deeper,  the  derm,  cutis  vera,  or  corium;  and  a  more  superficial,  the  epiderm, 
cuticle,  or  scarf-skin.  The  latter,  morphologically  representing  the  epiblast,  is  a 
purely  epithelial  cell-growth,  while  the  derm,  which  is  developed  from  the  meso- 
blast,  is  of  highly  complex  organisation. 

The  derm  is  composed  of  elastic  fibrous  tissue  intermixed  with  fat  vesicles,  and 
])undles  of  un.striped  muscular  fibres,  traversed  by  a  rich  })lexus  of  blood  and 
lymph-vessels  and  of  nerves,  and  enclosing  hair  l)ull)s  and  seliaceous  and  sudor- 
iparous glands.  The  su]>erficial  layers  are  of  finer  structure,  free  from  fat,  and 
form  a  multitude  of  eminenc^es,  called  papillae,  Avhich  project  ujiwards  into  corre- 
sponding depressions  in  the  sul)stance  of  the  epiderm.  The  fil^rous  bands  compos- 
ing the  deeper  layers  are  coarser  and  less  compact,  intermingled  with  fat  lobules, 
and  pass  without  any  definite  line  of  demarcation  into  the  subcutaneous  tissue. 
The  muscular  fibres  ap])ear  as  appendages  to  the  hair  and  its  sebaceous  follicles, 
and  are  known  as  arrectores  pilorum.  Two  or  three  bundles  arc  attached  to 
each  hair-i^heath  below  tlie  scl)aceous  gland  opening  into  the  follicle,  and  are  so 
arranged  as  to  be  ca])alile  of  compressing  the  acini  of  the  gland,  and  of  rendering 
the  direction  of  the  hair-shaft  somewhat  more  per])en(Hcular  to  the  surface  from 
which  it  emerges.  This  latter  action  ])roduces  the  '  bristling  of  the  hair'  which  is 
believed  to  be  one  of  the  manifestations  of  extreme  terror,  but  which  occurs  in  many 
persons  in  association  with  mental  excitement  of  various  kinds. 

The  fibrous  tissue  runs  for  the  most  part  in  l)undles  parallel  to  the  surface, 
intercrossing  at  various  angles  in  a  manner  that  appears  to  be  regulated  upon  a 


.STRUCTURE   OF  THE  SKIX  1075 

definitL'  plan.  Lantror  and  otliers  have  shown  that  if  the  skin  is  jiuiKtun-d  hy  an 
awl,  tlie  ai)ertur(,'  k'ft  on  \vitli(h-a\vin<;  thi-  inijili  iiicnt  is  not  roinid,  hut  Hnear  or 
angular.  On  the  scalj),  forclu-ad,  cliin,  and  I'pigastriuni  a  trianguhir  or  raggcfl  hole 
is  produced,  while  over  the  rest  of  tiie  hcxly  the  '  cleavage '  is  linear,  the  lines 
affecting  a  direction  nearly  at  right  angles  to  the  long  axis  of  the  limbs,  and  on  the 
trunk  running  ol^licjuely  downwards,  and  outwards  from  the  H\nnv.  The  linear 
cleavage  indicates  that  tlie  bundles  run  mainly  in  one  directi(»n,  while  the  'incom- 
plete' cleavage  is  associated  with  a  crossing  in  all  directions.  Tiie  arrangement  of 
the  vessels  of  the  skin  is  said  to  l»e  governed  by  the  cleavage,  and  tiie  form  and 
distril>ution  of  certain  skin  erui)tioiis  are  ])robabiy  connected  witli  these  factors. 

The  papillae  are  very  closely  set — from  'My  to  i;50.  according  to  Sai»]»ev,  lying 
within  a  square  millimetre.  The  largest  are  found  in  the  palm  and  sole  and  under 
the  nail,  reaching  a  heiglit  of  half  a  line  or  a  line  (1  to  2  nnn.  );  the  smallest, 
distributed  over  the  face,  scrotum,  and  mamniilhr,  having  only  a  third  or  a  fourth 
of  these  dimensions.  The  forms  usually  assumed  are  those  of  sim])le  cones,  but 
some  are  slightly  l)ull)Ous  at  their  free  extremities;  others  have  dujilicated  apices, 
and  those  about  the  i)almar  and  plantar  surfaces  of  the  hands  and  feet  form  long 
curvilinear  ridges,  which  are  pierced  ])y  the  orifices  of  the  sweat  ducts,  and  separated 
from  each  other  l)y  furrows.  It  is  only  in  these  latter  situations  that  the  arrange- 
ment of  the  papillie  is  unconcealed  by  tlu'  e])idermis.  Structurally,  the  pajiilla 
consists  of  a  delicate  lil)rous  tissue  containing  vessels  and  nerves,  or,  in  certain 
situations,  a  special  tactile  body.  Its  sul)e])idermic  surface  and  that  of  the  inter- 
]iapillary  depressions  is  modified  into  a  delicate,  structureless  lamina,  called  the 
membrana  basilaris. 

The  epiderm,  or  cuticle,  is  a  layer  of  varying  dci)th,  the  tliickness  being  regu- 
lated chiefiy  by  the  amount  of  i)ressure  or  friction  to  which  the  ])art  is  habitually 
suV)jected.  Its  deep  aspect  is  moulded  to  the  papillary  layer  of  the  derm,  while  its 
free  surface  gives  little  or  no  indication  of  the  ])ai)illarv  eminences  except  f)n  the 
palms  and  soles,  l)ut  it  displays  numl)erless  apertures  of  glands  and  hair-follicles, 
which  it  lines  with  tubular  prolongations.  Structurally,  it  consists  entirely  of  e]ii- 
thelial  cells  of  various  shajx'S.  The  component  cells  may  l)e  divide(l  into  five  distinct 
layers,  arranged  from  within  outwards  in  the  following  order:  (1)  The  stratum 
basilare,  or  generative  layer,  consists  of  a  single  set  of  nucleated,  ]»rismatic  cells,  the 
denticulated  bases  of  which  rest  upon  the  l)asement  membrane  of  the  derm.  (2) 
The  stratum  Malpighii,  succeeding  this,  is  a  soft,  relatively  tliick  layer,  com])osed  of 
several  ranges  of  nucleated  cells,  i)olyhedral  in  shape,  denticulated  on  all  sides,  and 
separated  from  each  other  liy  fine  intercellular  channels,  in  which  may  be  lym]»h 
corpuscles- and  even  pigment.  The  cells  are  tlie  sent  of  tlic  i.ignicnt  granules  which 
give  to  the  .skin  a  portion  of  its  colour.  (3)  The  stratum  granulosum  coiniirises 
two  or  three  layers  of  transitional  cells,  resembling  tiiose  of  the  stratum  Malpighii 
in  the  denticulation  of  their  oj)posed  sides,  but  fiattened  in  the  direction  of  the 
surface  and  containing  a  number  of  minute  granules,  which  readily  take  the  stain 
of  carmine  or  logwood,  and  are  coni]H»sed  of  a  jx'culiar  substance,  called  eleidin, 
or  kerato-hyalin,  that  is  said  to  be  the  active  agent  in  the  keratinic  transformation 
of  the  more  superficial  cells,  and  is,  perhaps,  to  be  regarded  as  the  earliest  ])roduct  of 
the  retrograde  change  which  ends  in  keratinisation.  (4)  The  overlying  layer,  the 
stratum  lucidum  of  Ochl,  represents  the  first  stage  of  the  homy  change.  It  is 
seen  in  sections  of  the  skin  as  a  transparent  liand,  which  on  close  examination  is 
fi»und  to  be  made  up  of  colourless  cells  with  indistinct  marginal  denticulation  and 
atrophic  nuclei,  and  fiattcncd  in  the  direction  of  the  surface,  (o)  The  sui)erficial' 
layer,  the  stratum  corneum,  is  not  very  sharply  define(l  from  the  last,  and  shows 
a  further  advance  in  the  horny  degeneration,  if  such  a  term  may  be  apjilied  to  a 
jiurposcful  and  necessary  change.  The  cells  are  highly  keratini.sed.  and  ajiju-ar  as 
thin,  transparent  scales,  from  ■which  both  denticulation  and  nuclcatioii  have  dis- 
appeared, the  latter,  however,  still  Ixing  traceable  after  macerati<^n  in  dilute 
alkalies. 

The  life  history  of  theejiiilennis  appears  to  be  that  of  a  c<intinuous  genesis,  from 
the  stratum  basilare.  of  new  cells  which  rise  slowly  towanls  tlie  surface  to  a.<sume 
in  succession  the  characters  of  the  cells  in  the  older  stratmn  above,  nud  l»ecome  in 
turn  replaced  l)y  their  successors  from  below,  until,  having  ].assed  through  all  tlie 


1076  THE  SKIN 

grades  leading  to  complete  keratinisation,  their  career  is  ended  and  they  are  cast 
off  from  the  t^tratum  corneum.  Xo  vessels  exist  in  any  ])art  of  the  epiderm,  Imt 
nerve-tibrils  are  said  to  penetrate  as  far  as  the  stratum  Malpighii. 

In  the  more  recent  methods  of  skin-grafting  the  surgeon  takes  a  jjlane  which 
usually  includes  all  the  layers  of  the  epidermis,  and  even  the  extreme  tips  of  the 
papilla?  of  the  derm  (as  shown  by  the  minute  bleeding  points  left  on  the  surface 
from  Avhich  the  graft  has  been  cut).  The  absence  of  the  deeper  and  more  highly 
vitalised  epidermic  cells  in  the  pellicle  separated  by  a  blister  is  probably  responsible 
for  the  almost  uniform  failure  of  transplantation  of  this  material. 


VESSELS  OF  THE  SKIN 

The  arteries  of  the  skin  form  a  network  in  the  subcutaneous  tissue,  and  from 
this  arise  branches  which  })ass  outwards  into  the  derm,  and,  after  supplying  twigs 
to  the  glands  and  hair-bull)s,  unite  into  a  second  network  beneath  the  papillae, 
supplying  these  latter  with  tine  arterioles,  which  finally  break  up  into  a  capillary 
plexus.  The  veins  commencing  within  the  papillae  form  a  subpapillary  network 
which  ends  in  the  subcutaneous  veins.     The  hnnphatics  have  a  like  arrangement. 

Nerves. — The  skin  is  richly  supplied  with  nerves,  but  in  varying  degrees  in 
different  regions.  Everywhere  the  nerves  form  plexuses  in  the  derm,  the  network 
becoming  finer  as  it  approaches  the  epiderm,  forming  a  rich  subepithelial  network 
immediately  beneath  the  stratum  basilare.  From  this,  delicate  tiljrils  have  been 
traced  outwards  as  far  as  the  stratum  Malpighii,  where  they  terminate.  The  integu- 
mentary nerves  end  in  three  different  Avays — some  in  subcutaneous  bodies,  the  cor- 
puscles of  Pacini  or  Vater;  others  in  dermic  structures,  the  corpuscles  of  ]Meissner 
and  Krause;  and  a  third,  or  epidermic  set,  are  believed  to  terminate  in  minute 
bulbs. 

The  corpuscles  of  Pacini  may  be  found  attached,  like  berries,  to  the  nerve- 
stems  lying  in  the  subcutaneous  tissue  in  various  parts  of  the  surface,  but  most 
abundantly  on  the  digital  nerves.  They  are  not  confined  to  the  cutaneous  nerves, 
but  are  seen  also  upon  mixed  nerves,  such  as  the  intercostal;  upon  articular,  peri- 
osteal, and  other  nerves;  and  even  on  sympathetic  filaments,  such  as  those  of  the 
mesentery.  They  are  of  oval  form,  and  range  in  size  from  oV  to  i  of  an  inch 
(1  to  5  mm. ).  Structurally,  they  consist  of  a  connective-tissue  envelope  derived  from 
the  perineurium  and  a  series  of  thirty  to  sixty  concentric  fil^rous  tunics  each,  lined  on 
both  sides  by  endothelium;  within  is  a  central  structureless  core.  The  nerve-tibre 
pierces  one  of  the  poles  of  the  corpuscle  and  reaches  the  central  core,  Avhere  it  loses 
its  myelin  and  subdivides  into  delicate  ramilications,  which  end  in  small  bulbous 
enlargements.  Each  liody  is  supplied  by  a  set  of  vessels  that  form  plexuses  and 
loops  in  the  layers  of  the  capsule. 

The  tactile  corpuscles  of  Meissner  are  of  smaller  size  and  more  limited  dis- 
tribution than  the  Pacinian  bodies.  They  belong  almost  entirely  to  the  hands  and 
feet,  but  may  lie  found  also  over  the  radial  side  of  the  forearm,  in  the  mamnnlla 
and  the  red  l)order  of  the  lips,  as  well  as  in  the  free  border  of  the  conjunctiva  and 
in  the  mucous  meml)rane  of  the  tip  of  the  tongue.  They  are  particularly  numerous 
over  the  pulp  of  the  terminal  phalanges,  wdiere  the  sense  of  touch  is  most  acute. 
They  lie  within  certain  of  the  papillae,  which  they  occupy  to  the  exclusion  of  ves- 
sels, and  appear  as  solid,  olive-shaped  bodies  about  -^  of  an  inch  in  length  (tV  of 
a  mm. )  placed  with  their  long  axes  at  right  angles  to  the  surface.  Each  is  Joined 
at  its  deeper  extremity  by  one,  two,  or  more  nerves.  In  structure  the  corpuscle 
consists  of  a  connective-tissue  capsule,  like  that  of  the  Pacinian  body,  derived  from 
the  perineurium;  within  this  is  a  solid  cellular  structure,  in  wliich  the  nerve  cylin- 
der, deprived  of  its  myelin,  l)reaks  up  into  filaments,  to  end  either  in  bulbous 
or  discoid  enlargements. 

The  spheroidal  end-bulbs  of  Krause,  found  in  the  conjunctiva  and  mucous 
membrane,  and  in  a  modified  form  in  the  prepuce  and  glans  penis  and  clitoridis, 
bear  some  resemblance  to  the  tactile  corpuscles  and  to  the  central  core  of  the  Paci- 
nian bodies.  They  consist  of  a  connective-tissue  capsule  enclosing  a  cellular 
structure  in  which  the  nerve  terminates. 


APPENDAGES   OF  THE  SKLV  1077 


THE  APPENDAGES  OF  THE  SKIN 

Under  this  heading  are  included  sudoriparous  and  sebaceous  glands,  hair,  and 
nails.  The  sudoriparous  glands,  wliich  secrete  the  sweat,  and  pn.l.al.ly  a  certain 
amount  of  oilv  matter  in  addition,  have  their  origin  in  a  single  coiled  tui.e,  which 
forms  a  spheroidal  glomerulus  in  the  deeper  i)art  of  the  derm,  or  even  in  the  suhcu- 
taneous  tissue,  and  is  continued  into  an  excretory  duct  that  jjierces  tlie  interi)apillary 
spaces  of  the  derm,  and  traverses  tlie  epiderm  in  a  sinuous  or  sjiiral  course  to  oj)en 
on  the  surface.  They  are  most  numerous  on  the  jialms  and  soles,  least  so  on  the 
Iiack  of  the  neck  and'  trunk  and  on  the  lower  limbs.  Sai)i)ev  estimates  the  total 
number  over  the  whole  body  at  2,000,000.  The  glomeruli  'range  from  one  two- 
hundred  and  fiftieth  of  an  inch  (O'l  mm.)  to  a  line  (2  mm.)  in  diameter,  and  are 
largest  in  the  axilla  and  groin  and  about  the  mannnary  areola.  The  tube  wall 
consists  of  an  epithelial  layer  of  })rismatic  nucleated  cells,  sup])orted  ])artly  by  an 
incom])lete  layer  of  cells,  l)elieved  to  be  those  of  unstrij)ed  muscular  til)re,  ])arily 
by  a  structureless  membrana  proi)ria  lying  outside;  the  last  and  continuous  with  the 
basement  membrane  of  tlie  <lerm.  The  'nmscidar'  layer  is  ab.-cnt  in  the  excre- 
tory duct.  Allied  to  the  sudorii)arous  glands  are  the  ceruminous  glands  of  the 
external  auditory  meatus,  which  have  the  same  structure,  l)ut  jjrimitively  open  into 
the  hair-follicles;  and  the  ciliary  glands  of  Moll,  opening  on  the  free  border  of 
the  lids,  which  do  not  form  glomeruli. 

The  sebaceous  glands  are  found  over  the  whole  area  of  the  skin  except  on 
the  palms  and  soles.  They  difter  from  the  sudoriparous  glands  in  their  racemose 
form,  in  their  almo.st  constant  relation  to  the  hairs,  in  the  oily  nature  of  their 
secretion,  and  in  their  com})aratively  su])erficial  j)osition.  The  greater  number 
discharge  their  contents  into  the  hair- follicles,  one,  two,  or  more  Iteing  attached  to 
each  hair;  others  open  directly  on  to  the  surface,  and  either  present  a  rudimentary 
hair  emerging  from  the  excretory  duct  or  are  altogether  unconnected  with  hairs, 
as  in  the  labia  minora  and  mammary  areola.  It  is  these  last  which  attain  the 
greatest  size.  Their  acini  are  invested  by  bands  of  unstriped  muscles  which  aid  in 
the  exjiulsion  of  their  contents,  and  in  the  case  of  the  larger  hairs  act  as  '  arrectores 
pilorum.' 

The  nails  are  essentially  an  epidermic  specialisation.  Rudimentary  in  man, 
they  are  largely  developed  in  many  of  the  lower  animals,  taking  the  form  of  claws 
or  hoofs.  In  man  the  nail  ajjpears  as  a  horny  ]»late  on  the  dorsal  aspect  of  tlie 
terminal  ])halanx  of  the  digit;  it  is  straight,  or  nearly  so,  in  its  longitudinal  axis, 
but  curved  in  the  opposite  direction,  with  the  convexity  outwards.  The  entire  nail 
is  divided  into  a  root,  thin,  soft,  and  buried  in  a  fold  of  skin;  a  body,  hard  and 
keratinised,  longitudinally  ri<lged  on  its  dorsal  aspect,  and  extending  from  the 
root  to  the  line  at  which  the  ai)pendage  ceases  to  be  connected  with  the  skin;  and 
a  free  extremity,  which,  unless  restrained  by  artificial  means,  tends  to  grow  into' 
a  claw-like  form  and  may  curve  over  strongly  towards  the  pahiiar  surface  of  tlu- 
diiiit.     The  point  at  which  this  joins  the  i>ulp  of  the  finger  is  called  the  angle. 

The  colour  of  the  nail  varies  in  its  different  i)arts.  The  greater  i)art  of  tlie  body 
has  ai>inkish  tint  which  may  l)e  expelled  In' pressure,  and  deitends  u}>onthe  vessels 
lieneath;  Imt  near  the  root  is  a  white  crescent,  the  lunula,  most  largely  developed 
on  the  thumb,  least  on  the  little  finger,  where  it  is  often  concealed  liy  the  overlajv 
ping  border.     The  free  extremity  is  semitransparent  and  almost  colourless. 

The  surface  of  the  nail,  especially  that  of  the  thumb,  may  under  certain  <ir- 
cumstances  present  transverse  furrows  and  ridges  corres]ion<ling  to  irregularities  of 
nutrition;  and  as  the  growth  of  the  entire  length  of  tlie  nail  occujjies  on  the  average 
about  six  months,  it  is  sometimes  ])ossible  to  surmise  roughly,  by  an  ungual 
inspection,  the  jdiysical  history  of  the  person  within  that  ])eriod. 

Hairs. — Man,  like  the  rest  of  the  mammalia,  is  a  hairy  animal,  but  the  greater 
part  of  his  hirsute  covering  assumes  the  form  of  a  scarcely  visil>le  down.  It  attains 
a  considerable  develojtment  only  in  certain  regions,  and  it  is  lacking  on  tlie  llexor 
surface  of  the  hands  ami  feet  ami  their  digits,  on  the  back  of  the  terminal  phalanges, 
and  at  certain  rellections  of  the  integument,  as  the  )>re]>uce  and  glans  penis,  the 
inner  aspect  of  the  labia  majora  an<l  the  labia  minora.     The  distril>ution  of  larger 


1078  THE  SKIN 

and  smaller  hairs  in  the  two  sexes  is  too  familiar  to  require  description.  The 
direction  taken  by  the  hairs  in  the  various  parts  of  the  body  is  fairly  constant  and 
may  be  traced  in  each  region  to  or  from  certain  centres  or  vortices,  such  as  those 
upon  the  crown  of  the  head,  at  the  external  auditory  meatus,  in  the  axilla,  the 
fold  of  the  groin,  and  elsewhere. 

The  hair  not  only  varies  in  character  and  develo})nK'nt  in  difTerent  jiarts  of  the 
surface,  but  presents  considerable  racial  and  individual  variations  in  each  region. 
Taking  the  hair  of  the  head  as  a  type,  we  may  find  it  either  straight,  wavy,  curled 
into  incomplete  or  complete  spirals,  or  minutely  tufted  like  wool,  and  each  of  these 
varieties  is  associated  with  i)eculiarities  in  the  transverse  sectional  area;  thus,  in 
the  straightest  hair  the  section  is  circular  or  nearly  so,  while  in  the  wavy,  curly,  and 
woolly  hair  it  is  oval  or  elliptical,  the  greatest  difference  between  the  largest  .and 
smallest  diameters  being  found  in  the  woolly  hair  in  Avhich  the  radius  of  the  curve 
is  smallest.  In  length  the  highest  development  is  attained  in  straight  hair,  and  the 
growth  is  nearly  always  greater  in  the  female  than  in  the  male.  In  some  regions 
the  growth  becomes  luxuriant  from  infancy;  in  others,  as  upon  the  i)ubic  regions 
in  both  sexes  and  on  the  lips  and  cheeks  of  the  male,  its  full  development  is  deferred 
until  puberty  or  later.  As  age  advances,  the  hair-bulbs  are  liable  to  undergo  pre- 
mature atrophy  upon  the  sunmiit  of  the  head  in  men,  while  the  groAvth  may  con- 
tinue to  progress  in  other  parts  of  the  body,  even  to  extreme  senility;  and  a  loss 
of  pigment  in  the  hair,  usually  beginning  on  the  head  and  extending  later  in  a 
somewhat  capricious  way  to  the  other  regions  of  the  body,  is  another  sign  of  local 
failure  of  nutrition  which  may  or  may  not  be  associated  with  senile  degeneration 
of  the  tissues  generally.  Pathologically,  the  hair  is  subject  to  many  changes,  into 
which  it  is  not  necessary  to  enter  here. 

The  first  growth  of  hair  begins  about  the  fifth  month  of  fa^tal  life,  but  this  croj) 
(lanugo)  is  entirely  shed  within  a  few^  months  of  birth.  The  process  of  shedding 
and  new  formation  goes  on  throughout  life. 

The  typical  hair  has  its  root  in  a  dermic  papilla  sunken  at  the  bottom  of  a  deep 
follicle  which  runs  more  or  less  obliquely  through  the  whole  or  greater  part  of  the 
thickness  of  the  skin.  The  hair-follicle  is  cylindrical  or  oval  in  section  and  fairly 
uniform  in  diameter  in  the  greater  part  of  its  length,  but  expanding  below  where  it 
contains  the  bulb  of  the  hair.  Into  it  open  the  orifices  of  the  sebaceous  glands 
appended  to  the  hair;  very  rarely  also  the  duct  of  a  sweat-gland. 

Structurally,  the  follicle  consists  of  an  invagination  of  the  elements  of  the  skin, 
with  the  addition  of  a  partial  lining  derived  from  the  generative  papilliv  of  the  hair; 
and  its  wall  comprises  three  laminae.  The  external  or  dermic  coat  is  continuous 
Avith  the  derm,  and  is  composed  of  two  layers  of  fibrous  tissue,  the  more  external 
being  longitudinal  in  direction,  the  inner  transverse.  At  the  bottom  of  the  follicle 
it  is  reflected  upwards  as  the  papilla,  which  constitutes  the  essential  and  generative 
element  of  the  hair-root.  The  middle  or  hyaline  coat  is  an  invagination  of  the 
structureless  basement  meml^rane,  upon  Avhich  rest  the  deei)est  cells  of  the  epidermis. 
This  becomes  lost  upon  the  papilla.  The  internal  epithelial  coat  is  divided  into 
two  secondary  layers  called,  respectively,  the  outer  and  inner  root-sheaths.  The 
outer  root-sheath,  from  the  opening  of  the  folhcle  down  to  the  openings  of  the 
.sebaceous  ducts,  includes  all  the  layers  of  the  epidermis,  Init  lielow  this  i)oint  loses 
the  stratum  granulosum  and  the  stratum  conifmn,  and  is  reduced  to  the  stratum 
Malpighii  and  stratum  l)asilare.  The  inner  root-sheath,  unrei)resented  in  the 
ei)iderm  and  ])robably  a  derivative  of  the  hair-papilla,  consists  of  three  layers:  tlie 
layer  of  Henle,  formed  by  a  single  set  of  polyhedral  cells;  the  layer  of  Huxley, 
similarly  constituted,  but  with  the  component  cells  more  elongated  and  less  closely 
compacted;  and  the  cuticular  layer,  composed  of  a  single  set  of  tliin,  imbricating 
cells,  clear  and  transparent,  with  atrophic  nuclei. 

The  hair  proper  is  a  cylindrical  or  oval  shaft  ex])anded  l)elow  into  a  bulb, 
where  it  cai)S  the  pa])illa,  at  the  bottom  of  the  follicle.  Tlie  shaft,  fairly  uni- 
form in  diameter  in  the  scalp-hairs,  consists  of  a  medullary  axis,  surrounded 
by  a  cortical  coat  and  invested  by  a  cuticular  layer.  The  medulla,  constituting 
about  one-fourth  of  the  entire  diameter  of  the  hair,  is  a  solid  cylinder,  white  l»y 
reflected  light,  dark  by  transmitted  light,  and  is  composed  of  clf)sely  compacted 
nucleated  cells,  filled  with  pigmentary  and  fatty  granules  and  air-bui)bles.     It  is 


APPEXDAGES  OF  THE  Sk'/X  1079 

formed  below  1)V  a  layer  nf  cells  which  cnoloso  and  crown  the  ijajiilla.  Downy 
hairs  are  devoid  of  medulla.  The  cortex  consists  of  a  layer  of  fusiform  cells 
elongated  in  the  direction  of  the  hair,  and  these,  like  tlie  medullary  cells,  are 
nucleated  and  contain  pigmentary  granules.  The  epidermis  or  cuticle  is  a  layer 
of  scaly  epithelial  cells,  arranged  like  the  tiles  of  a  roof,  hut  with  the  overlapping 
edges  directed  upwards.  Owing  to  this  peculiar  imbrication  the  edges  of  the  cells 
of  the  buried  part  of  the  shaft  may  become  reversed  when  the  hair  is  pulled  out  of 
its  follicle,  and  may  then  present  a  deceptive  appearance  like  that  of  fusiform  fibres 
rolled  spirally  around  a  stem. 

As  the  shaft  structures  approach  the  papilla  they  gradually  change  their  char- 
acter. The  l)ulb  itself  consists  of  an  inner  layer  of  prismatic  cells  lying  directly 
in  contact  with  the  dermic  ])apilla,  an<l  rei»reseiiting  the  stratum  basilaii-  of  the 
epidermis;  a  middle  layer  of  pf)lyhedral  cells  like  those  of  the  stratum  Malpighii, 
and  an  outer  layer  of  keratinising  cells  corresponding  to  the  stratum  granulo.sum, 
but  devoid  of  eleidin. 

The  papilla  is  a  cone  of  connective  tissue  into  the  centre  of  which  is  prolonged 
a  vascular  looj)  from  the  subcutaneous  plexus.  Nerves  are  not  seen  in  the  papilla, 
but  fine  twigs  have  l)een  traced  into  the  deeper  part  of  the  follicular  wall,  there 
losing  their  myelin  and  forming  terminal  fibrils,  some  longitudinally,  some  circu- 
larly arranged,  outside  the  hyali!i  layer.  The  special  tactile  hairs  of  the  lower 
animals  present  a  more  complex  nervous  and  vascular  apparatus,  but  these  are  not 
represented  in  man. 


SECTION   X 

ON    SURGICAL 

AKD 

TOPOGRAPHICAL    ANATOMY 

By  W.  H.  a.  JACOBSON,  M.Ch.Oxon. 

ASSISTANT     SURGEON,    GUY'S     HOSPI-TAL 


SUPERFICIAL  ANATOMY  OF  THE  HEAD  AND  NECK 

THE  CRANIUM  AND  SCALP 

Bony  landmarks. — These  should  be  studied  with  the  aid  of  a  skull,  as  well 
as  on  the  living  subject.  In  the  middle  line,  behind,  is  the  external  occipital  pro- 
tuberance, or  inion,  the  thickest  part  of  the  vault,  and  corresponding  internally 
with  the  meeting-point  of  six  sinuses.  From  this  point  the  superior  curved  lines 
pass  out  towards  the  mastoid  processes,  and  indicate  the  first  part  of  the  course  of 
tlie  lateral  sinuses,  which,  after  running  horizontall}^  outwards,  turn  downwards  in 
the  mastoid  bone.  The  position  of  these  important  vessels  would  be  more  cor- 
rectly indicated  by  a  line  drawn  first  from  the  external  occipital  protuberance  to 
the  upper  border  of  the  mastoid  process,  one  inch  behind  the  external  auditory 
meatus.  This  line  gives  the  transverse  and  longer  part  of  the  sinus.  A  shorter  line, 
from  the  ending  of  the  first  to  tlie  i\])  of  the  mastoid,  will  indicate  by  its  upper 
two-thirds  the  sigmoid  portion  of  the  sinus  and  the  bend  by  wliich  it  communi- 
cates with  the  transverse  part  (Macewen).      (Fig.  660.) 

About  two  inches  and  three-quarters  (68  mm.)  above  the  external  occi])ital  pro- 
tuberance is  the  lambda,  or  meeting  of  the  sagittal  and  lambdoidal  sutures  (i)oste- 
rior  fontanelle,  small  and  triradiate  in  shape).  It  is  useful  to  remember,  as  guides 
on  the  scalp  to  the  al)ove  two  important  points,  that  the  lambda  is  on  a  level 
with  the  supraciliary  ridges,  and  the  external  occipital  protuberance  on  one  with 
the  zygomatic  arches. 

The  point  of  junction  of  the  lambdoidal  and  S(]uamous  sutures,  the  asterion, 
is  placed  about  three-cjuarters  of  an  inch  liehind  and  half  an  inch  above  the  upjicr 
part  of  the  posterior  border  of  the  mastoid  (fig.  659).  The  bregma,  or  junction 
of  the  coronal,  sagittal,  and,  in  early  life,  the  frontal  suture  (anterior  fontanelle, 
large  and  lozenge-shaped),  lies  just  in  front  of  the  centre  of  a  line  drawn  trans- 
versely over  the  cranial  vault  from  one  preauricular  point  to  the  other  (fig.  659). 
The  pterion,  or  junction  of  the  frontal,  parietal,  temporal,  and  sphenoid  bones, 
lies  in  the  temporal  fossa,  one  and  a  half  to  two  inches  behind  the  external  angular 
process  of  th-e  frontal,  and  about  the  same  distance  above  the  zygoma  (fig.  659). 
This  spot  also  gives  the  position  of  the  trunk  and  the  anterior  and  larger  division 
of  the  middle  meningeal  artery.     The  zvgoma  can  be  traced  backwards  to  its  roots 

1080 


CRANIUM  AND  SCALP 


1081 


in  front  of  the  oar,  while  fnun  its  anterior  extremity  the  fnifier,  carried  upwards 
along  the  outline  of  the  malar,  traces  the  temj>orai  ridge  along  the  side  of  the 
skull  which  marks  the  ui)per  limit  of  the  temporal  fossa,  and  the  attachments  of 
the  temporal  muscle  and  fascia.  In  tlu;  temporal  fossa  lie  the  muscle,  and  the 
deej)  temporal  vessels  and  nerves.  Al)Ove  the  zygoma  can  he  felt  the"  ccjntraction 
of  the  temporal;  and  below,  that  of  the  masseter  nmscle;  the  former  less  distinctly 
owing  to  its  covering  of  fascia,  attached  below  by  two  layers  to  the  U]»i)er  border 
of  the  zygoma.  In  the  zygomatic  fossa,  lying  inside  the  zygoma,  arc  the  lower 
part  of  the  temporal,  and  the  two  pterygoid  muscles,  together  with  the  internal 
maxillary  vessels,  and  the  mandibular  division  of  the  fifth  nerve,  an<l  their 
branches. 

The  anterior  inferior  angle  of  the  parietal  bone,  and  its  great  importance  as  a 


Fig.  659.— The  Skull. 

BREGMA 


GLABELLA   NAS 

(THE    POINTER 


landmark,  has  alreadv  been  given.  The  posterior  inferior  angle  of  this  V)one 
(grooved  l>v  the  lateral  sinus)  lies  a  little  above  and  behind  the  base  of  the 
nTastoid.  on  a  level  with  the  roots  of  the  zygoma  (tig.  055)).  Just  below  and  in 
front  of  the  tij)  of  the  mastoid  the  transverse  process  of  the  atlas  can  W  made  out 
in  a  spare  sul»ject.  ^  ,       ,  •     , 

The  average  thickness  of  the  adult  skull-cai>  is  about  one-lifth  of  an  mch 
(Holden).  The  thickest  i>art  is  at  the  external  occipital  j.rotubcrance,  where  the 
bone  is  often  three-quarters  of  an  inch  in  thickness.  The  thinnest  i)art  of  the  skull 
vault  is  over  the  temporal  part  of  the  sciuamous.  The  extreme  fragility  of  the 
skull  here  is  partlv  c<jmpensated  for  by  the  thickness  of  the  soft  parts;  (»f  these. 
the  pericranium  is  alone  thinner  than  elsewhere,  while  its  intimate  connection 
with  the  bones  make  cephallutmatoma  less  frequent  here  (Tillaux). 


1082 


SURGICAL  AXD   TOPOGRAPHICAL  ANATOMY 


In  front,  the  circumference  of  the  bony  orbit  can  be  traced  in  its  whole  extent. 
The  supraorbital  notch  lies  at  the  junction  of  tlie  inner  and  middle  thirds  of  the 
supraorbital  arch,  ^\llen  this  notch  is  a  complete  foramen,  its  detection  is  much 
less  easy.  Above  the  supraorbital  arch  is  the  supraciliary  ridge,  and  higher  still 
the  frontal  eminence.  From  the  supraorbital  notch,  a  line  drawn  downwards  and 
slightly  outwards,  so  as  to  run  between  the  two  bicuspid  teeth  in  each  jaw,  passes 
over  the  infraorbital  and  mental  foramina  (Holden).  The  infraorltital  foramen 
lies  about  a  quarter  of  an  inch  below  the  margin  of  the  orbit.  The  mental  foramen 
in  the  adult  is  placed  midway  between  the  upper  and  lower  margins  of  the  jaw, 
and  '  is  a  little  over  a  quarter  of  an  inch  below  the  cul-de-sac  of  mucous  mem- 
brane between  the  lower  lip  and  the  jaw  "  (Treves). 

THE  BONY  SINUSES. — The  frontal. — The  development  of  these  by  the  j:wen- 
tieth  or  twenty-fifth  year  may  render  a  fracture  here  much  less  grave  in  the  adult 
than  Avould  otherwise  be  the  case,  the  inner  table,  if  now  separated  from  the  outer, 
protecting  the  brain.  Mr.  Hilton  showed  that  the  absence  of  any  external  prom- 
inence here  does  not  necessarily  imph'  the  absence  of  a  sinus,  as  this  may  be  formed 


Fig.  660. — Temporal  Bone,  showing  Suprameatal  Triaxgle.     (Ban.) 


ROOT  OF  ZYGOMA 


LATERAL  SINUS 


SUPRAMEATAL 
TRIANGLE 


; 5 POSITION    FOR    PER- 

-^  FORATING  VERTICAL 


LINE  OF  FA- 
CIAL NERVE 


by  retrocession  of  the  internal  table.  In  old  people  these  sinuses  may  enlarge  by 
the  inner  table  following  the  shrinking  brain.  Again,  a  very  prominent  bump  here 
does  not  necessarily  point  to  the  existence  of  a  sinus  at  all,  being  due  merely  to  a 
heaping  up  of  bone. 

When  well  developed,  the  frontal  sinuses  may  reach  two  inches  npwards  and 
one  and  a  half  inches  outwards,  occupying  the  greater  part  of  the  vertical  jtortion 
of  the  frontal  bone.  When  very  small,  they  scarcely  extend  above  the  nasal 
process.  Even  when  present,  they  are  often  asymmetrical.  The  sinuses  are 
separated  by  a  septum.  Each  sinus  narrows  downwards  into  the  infundibulum. 
This  '  is  deeply  placed  behind  the  nasal  process  of  the  maxilla  and  near  the  inner 
wall  of  the  orbit.  Its  termination  in  the  middle  meatus  is  about  on  a  level  with  the 
pal))ebral  fissure'  (Thane  and  Godlee). 

The  communication  of  tlieso  sinuses  with  the  nose  accounts  for  tlie  frontal 
headaches  in  oz^ena,  and  the  fact  that  a  patient  with  a  C(jmpound  fracture  oi)ening 
up  the  sinuses  can  blow  out  a  flame  held  close  by. 

The  mastoid  sinuses  are  arranged  in  tAvo  groups,  of  the  utmost  importance  in 


CRAM  CM  AM)   SCAI.P 


10H3 


that  freqiiont  and  fatal  disease,  intlauiinatiou  of  tlic  iiiiddlc  car  : — (A)  Tlir  upper, 
or  '  antrum,'  ]ir(sc'nt  Woth  in  early  and  late  life,  lidrizontal  in  direetii.u.  rlds.lv 
adjacent  to  and  eonimunieating  with  the  tympanum.  (  W)  The  lower,  or  vertical. 
This  group  is  not  developed  in  early  life. 

A.  Mastoid  antrum  (figs.  (JGU  and  OGl ). — This  is  a  small  chaml»er  lying 
behind  the  tympanum,  into  the  ui)i>er  and  back  i»art  of  which  (tympanic  attic)  it 
opens.  Its  size  varies,  especially  with  age.  Present  at  birth,  it  readies  its  largest 
size  (that  of  a  pea)  about  the  third  or  fourth  year.  After  this,  its  size  usually 
diminishes  somewhat,  owing  to  the  development  of  the  encroacliing  lione  around 
it.  Its  roof,  the  tegmen  antri,  is  merely  the  backward  continuation  of  the  tegmen 
tympani.  The  level  of  this  is  indicated  l)y  the  posterior  root  of  the  zygoma. 
'The  level  of  the  lloor  of  the  adult  skull  at  the  tegmen  antri  is,  on  an  average,  legs 
than  one-fourth  of  an  inch  above  the  njof  of  the  external  osseous  meatus;  in  children 
and  adolescents,  from  one-sixteenth  to  one-eighth  of  an  inch  '  (Macewen), 

The  outer  wall  of  the  antrum  is  formed  V)y  a  plate  descending  from  the  squamous 
bone.  This  is  very  thin  in  early  life,  but  as  it  develops  ]>y  deposit  from  the  peri- 
osteum, the  depth  of  the  antrum  from  the  surface  increases.  Macewen  gives  the 
average  of  the  depth  as  varying  from  one-eighth  to  three-fourths  of  an  inch.  At  the 
junction  of  the  two  parts  of  the  outer  wall  of  the  mastoi«l  cells  is  the  masto-scjuanKisal 
suture,  often  i>resent  at  puberty.     Through  tlif  floor,  the  antrum  communicates 

Fig.  661. — Sagittal  Section  through  Roof  axd  Floor  of  Tympanic  Cavity. 

ANTRUM 


FENESTRA  OVALIS 
Canal  for  tensor  tympani  muscle 


■^f^ 


^•^:§if^.^^?  ^ 


OSSEOUS  EUSTACHIAN  TUBE 


FLOOR  OF  TYMPANUM 

FENESTRA  ROTUNDA 
CANAL  FOR  FACIAL  SERVE 


MASTOID  PROCESS 


with  the  lower  or  vertical  cells  of  the  mastoid.  This  floor  is  on  a  l<iwtr  Itvtl  than 
the  opening  into  the  tympanum,  and  thus  drainage  of  the  antrum  is  ditlicult.  fluid 
finding  its  way  more  readily  into  the  lower  cells.  Behind  the  mastoid  antrum 
and  cells  is  the  bend  of  the  sigmoid  jtart  of  the  lateral  sinus,  with  its  short  descend- 
ing portion  (fig.  ObU).  Macewen  gives  the  following  guides  for  tliis  part  <»f  th<> 
sinus  :  '  (1)  A  line  clrawn  from  the  parieto-S(iuamo-mastoid  junction  to  the  tip  of 
the  mastoid.  (2)  In  the  aduit,  a  vertu-al  line  drawn  one-lialf  of  an  inch  behind  the 
])Osterior  bony  wall  of  the  external  auditory  meatus,  and  between  the  levels  of  the 
roof  and  the  floor,  will,  in  the  majority  of  ca.'ses,  indicate  the  ]>osition  of  the 
anterior  convexity  of  the  signK)i<l  sinus.'  The  same  authority  gives  the  following 
directions  for  exploring  this  important  vessel  :  'An  opening  in  the  bone,  with  its 
posterior  margin  touching  the  line  drawn  from  the  parieto-squamo-mastoicl  junction 
to  the  ti))  of  the  mastoid,  and  within  the  jiarallcls  of  the  roof  and  floor  of  the 
external  auditory  meatus,  will  expose  the  part  of  the  sigmoid  sinus  most  often 
affected  with  septic  thromliosis. '  The  sinus  lies  more  sujterticially  than  tlie  antrum, 
being  usually  f»ne-fourth  of  an  inch,  occasionally  only  one-half  of  an  inch,  from 
the  surface. 

The  exact  position  of  the  antrum,  a  little  above  and  beliind  tlie  external  auditory 
meatus,  is  rejiresented  by  Macewen's  '  suprameatal  triangle."  This  is  a  triangle 
bounded  l>v  the  jiosterior  root  of  the  zygoma  above,  the  upper  and   posterior  seg- 


1084 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


ment  of  the  bony  external  meatus  l)elow,  and  an  imaginary  line  joining  the  above 
boundaries  (tig. '660).  'Roughly  speaking,  if  the  oritice  of  the  external  osseous 
meatus  be  bisected  horizontally,  the  ui)per  half  would  be  on  the  level  of  the  mastoid 
antrum.  If  this  segment  be  again  Isisected  vertically,  its  posterior  half  would  again 
corres]:>ond  to  the  junction  of  the  antrum  and  middle  ear,  and  immediately  behind 
this  lies  the  suprameatal  fossa'  (Macewen).  When  opening  the  antrum  through 
this  triangle,  the  operator  should  work  forwards,  and  inwards,  so  as  to  avoid 
the  sigmoid  sinus  (fig.  660);  while,  to  avoid  the  facial  nerve  (fig.  660),  he  should 
bring  the  root  of  the  zygoma  and  the  upper  part  of  the  bony  meatus  as  close  as 
possible.  The  level  of  the  base  of  the  lirain  will  be  a  few  lines  al)ove  the  posterior 
root  of  the  zvgoma  (fig.  659)  and  al)Out  one-quarter  of  an  inch  above  the  roof  of 
the  bon}'  meatus  (Macewen). 

B.  The  lower  or  vertical  cells  of  the  mastoid  are  developed  later  than  is 
the  antrum,  and  vary  much  in  their  contents.  In  only  about  twenty  per  cent,  do 
they  contain  air. 

The  veins  passim/  from  the  mastoid  cells  and  tym'panuin  fall  into  three  chief  groups 
— (a)  those  opening  into  the  lateral  sinus;  (6)  those  passing  through  the  mastoid 
foramen  into  the  occipital  and  scalp  veins;  (c)  those  running  through  the  petro- 
squamosal  suture  to  the  dura  mater.     As  all  these  veins  carry  connective-tissue 


Fig.  662. — Horizontal  Section  of  Left  Temporal  Bone,  showing  the  Various 

Parts  of  the  Ear. 


TYMPANIC  RING  TYMPANUM 


EXTERNAL  MEATUS 


FLOOR  OF  TENSOR  TYMPANI  CANAL 
EUSTACHIAN  TUBE 
COCHLEA 


MASTOID  AIR  CELLS 


CAROTID  CANAL 


INTERNAL  MEATUS 
VESTIBULE      I         AQUEDUCTUS  FALLOPII 

POINTER  PASSING  THROUGH  FENESTRA  OVALIS 


sheaths,  inflammation  may  reach — (a)  the  lateral  sinus,  causing  septic  phlebitis; 
(6)  the  soft  parts  outside,  causing  cellulitis,  periostitis,  etc. ;  (c)  the  dura  mater 
and  brain,  leading  to  meningitis  and  abscess. 

The  sphenoidal  sinuses  are  less  imj^ortant  surgically,  but  these  points  should 
be  remembered: — (1)  Fracture  through  them  may  lead  to  l)leeding  from  the  nose, 
which  is  thus  brought  into  communication  with  the  middle  fossa;  (2)  the  com- 
munication of  their  mucous  membrane  with  that  of  the  nose  may  explain  the 
inveteracy  of  certain  cases  of  ozsena;  (8)  here  and  in  the  frontal  sinuses  very 
dense  exostoses  are  sometimes  formed. 

THE  SCALP. — The  importance  of  the  scalp  is  best  seen  froui  an  examination 
of  its  layers  (fig.  663).  These  are — (1)  skin;  (2)  subcutaneous  fat  and 
fibrous  tissue  ;  (3)  the  occipito-frontalis  and  aponeurosis  ;  (4 )  the  sub- 
aponeurotic layer  of  connective  tissue;  (5)  the  pericranium  and  subpericranial 
connective  tissue. 

The  first  three  layers  are  connected  and  move  together.  (1)  The  union  of  the 
skin,  and  its  density,  are  to  enable  it  to  meet  pressure,  and  also  to  ]irevent  it 
rucking  into  folds.  Furthermore,  they  account  for  the  extreme  ])ain  of  inflamma- 
tion here,  and  the  diiUcult}'  of  raising  a  blister  on  the  scalp.     The  presence  of 


CRAMIM   AM)   SCALP 


10S5 


hairs  and  selmceous  glands  is  of  much  more  importance  than  ajtpears  at  lir-^t. 
Thus  the  rooting  of  the  former  is  so  firm  that  in  the  ease  of  young  women  tlie 
whole  scalp  may  he  torn  off  hy  mticliincry.  Tlie  sebaceous  glands  have  also 
grave  importance.  If  in  removing  them  the  aponeurosis  hcncath  is  pricked  or  the 
wound  hecomes  foul,  fatal  suppuration  in  the  '  chmgerous  area'  Iteneath  may 
follow.  (2)  The  subcutaneous  fat  is  arranged  much  as  in  tlie  ))alm.  viz.  t<^»ugh 
fatty  pellets  are  enclosed  in  lil)n)us  jtartitions,  dipping  from  the  skin  to  tlie  third 
layer,  and  thus  tying  the  three  layers  together.  (8j  The  occipito-frontalis  and 
its  aponeurosis  have  heen  fully  deserihed  elsewhere  (jtage  427).  (4)  The  sub- 
aponeurotic layer  of  connective  tissue.  The  characters  of  this  layer  are  ipiite 
opposed  to  those  of  the  layer  of  connective  tissue  above  the  aponeurosis.  It  is 
loose,  delicate,  and  fatless.  From  these  result  the  free  mobility  of  the  scalp,  the 
fact  that  it  can  he  torn  away,  and  (most  important  of  all)  the  facility  with  which 
inflammatory  jiroducts  can  s))read  in  this  layer.  Tiie  perils  of  pus  ])ent  up  hen; 
are  extreme,  viz.  sloughing  of  the  scalp,  or  necrosis  of  tin-  hones,  hlood-poisoning, 
and  meningitis,  from  miscliief  travelling  along  the  emissary  and  di})loic  veins 
(fig.  fiHo).  The  continuity  of  the  different  scalp  layers  hy  bands  of  connective 
tissue  passing  from   the  skin   to   the  occipito-frontalis,  and  thence  along  vesseL-^, 


Via.  fiO:?. — Section  TiiKor(;ii  thk  Scalp,  Skt-i-l.  and  Dika  Matkr.     (Tillaii.x.j 


Skin  and  superficial 
fascia  with 

HAR  BlLtS  ASO  SEBACEOUS 

GLANDS 
Fat  pelleta 

Ocoipito-frontalia 
aponeurOBlB 

Subaponeurotic  con- 
nective tiB8ue 

Pericranium 
Subpericranial  con- 
nective tissue 

SKULL:    DIPLOIC  TISSUE 


Dura  mater 
Skull  cavity 


emissarv  and  others,  into  the  venous  sinuses,  or  by  the  di)>loic  veins  within  the 
skull,  will  aeeount  fur  seal|)  inflammation  reaching  the  meninges. 

Of  the  vessels  of  the  scalp,  the  arteries  are  peculiar  in  their  jmsition.  Thus 
they  lie  superficial  to  the  deep  fascia,  which  is  here  rei)resented  l>y  the  aponeumsis 
(fig.  ()<)3).  From  this  position  arises  the  fact  that  a  large  flap  of  seal],  may  be  sep- 
arated without  })erishing.  as  it  carries  its  own  blood-vessels.  From  the  densitv  of 
the  layer  in  which  the  vessels  run  they  cannot  retract  and  are  <litlicult  t<»  seize, 
haemorrhage  thus  being  free.  Finally,  from  their  position  over  closely  adjacent 
bone.  ill-ai>i)lied  pressure  may  easily  lead  to  sloughing. 

The  emissary  veins. — These  are  communications  between  the  sinuses  witliin. 
and  the  veins  outside  the  cranium.  Most  of  tliem  are  temporary,  corresponding 
to  the  chief  period  of  growth  of  the  brain.  Thus  in  early  life,  when  the  develop- 
ment of  the  brain  has  to  be  very  rapid,  owing  to  the  api>roaching  closure  nf  its  vixnv, 
a  free  escape  of  blood  is  mostC.ssential.  especially  in  children,  with  their  su<lden 
explosions  of  laughter  and  passionate  crying. 

1.  Vein  throu'jh  the  foramen  ca'cum,  between  the"  anterior  extremity  of  the 
superior  longitu<linal  sinus  and  the  nasal  mui-ous  membrane.  The  value  of  this 
temporary  outlet  is  well  seen  in  the  timely  ]irofuse  ej.istaxis  of  children.  (Hher 
more  perinanent  connnunicati«»ns  between  the  skull  cavity  and  nasal  mucous  nu-ni- 


1086  SURGICAL   AXD   TOPOGRAPHICAL  AXATOMY 

brane  pass  through  the  etlimoid  and  internal  orbital  foramina.  The  fact  that  the 
nasal  mucous  membrane  is  loose  and  ill-su]>i)orted  on  the  turl)inated  bones  allows 
its  vessels  to  give  way  readily,  and  thus  forms  a  salutary  safeguard  to  the  brain, 
warding  off  many  an  attack  of  apoplexy. 

2.  Vein  thn)Ugh  the  mastoid  foramen,  between  the  lateral  sinus  and  the  pos- 
terior auricular  and  occipital  veins.  This  is  the  largest,  the  most  constant,  and  the 
most  superticial  of  the  emissary  veins.  Hence  the  old  rule  of  ai)i)]ying  blisters  or 
leeches  over  it  in  cereljral  congestion. 

3.  Vein  through  the  posterior  superior  angle  of  the  parietal  l)ctween  the  supe- 
rior longitudinal  sinus  and  the  veins  of  the  scalp. 

4.  Vein  through  the  posterior  condyloid  foramen  between  the  lateral  sinus  and 
the  deep  veins  of  the  neck. 

5.  Vein  through  the  anterior  condyloid  foramen  between  the  occipital  sinus  and 
the  deep  veins  of  the  neck. 

6.  Ophthalmic  veins  comn:iunicating  with  the  cavernous  sinus  and  the  angular 
vein.  These  veins  may  be  the  source  of  fatal  l)lood-poisoning,  hy  conveying  out  of 
reach  septic  material,  in  acute  periostitis  of  the  orbit,  or  in  osteitis,  of  dental  origin, 
of  the  jaws. 

7.  Minute  veins  tl:rough  the  foramen  ovale  l)etween  the  cavernous  sinus  and  the 
pharyngeal  and  pterygoid  veins. 

8.  Communications  between  the  frontal  diploic  and  supraorl)ital  veins,  between 
the  anterior  temporal  diploic  and  deep  temporal  veins,  and  between  the  posterior 
temjjoral  and  occipital  diploic  veins  and  the  lateral  sinus. 

The  gravity  of  these  emissary  veins  and  their  free  conanunications  with  others 
is  shown  by  the  readiness  with  which  they  l)ecome  the  seat  of  septic  thrombosis, 
and  thus  of  blood-poisoning,  in  cranial  injuries,  erysipelas,  suppuration  of  the  scalp, 
and  necrosis  of  the  skull. 

Structure  of  cranium. — Two  layers  and  intervening  cancellous  tissue. 
Each  layer  has  special  properties.  The  outer  gives  thickness,  smoothness,  and 
uniformity,  and,  above  all,  elasticity.  The  inner  is  whiter,  thinner,  less  regular-- 
e.g.  the  dej^ressions  for  vessels,  Pacchionian  bodies,  dura  mater,  and  brain.  Its 
cliief  characteristics  are  its  fragilit}'  (vitreous)  and  absolute  inelasticity.  The 
diploe,  formed  by  absorption  after  the  skull  has  attained  a  certain  thickness, 
reduces  the  weight  of  the  skull  without  proportionately  reducing  its  strength,  and 
provides  a  material  which  will  prevent  the  transmission  of  vibrations. 

Results  of  the  above  varying  elasticity. — A  ])low  on  the  head  may  fracture 
the  internal  table  only,  the  external  one  anil  diploe  escaping.  This  is  difhcult  to 
diagnose,  and  thus  it  is  impossible  to  judge  of  the  severity  of  a  fracture  from  the 
state  of  the  external  table.  This  may  be  whole,  or  merely  cracked,  while  the 
internal  shows  many  fragments,  which  may  set  up  meningitis,  or  other  mischief. 

Anatomical  conditions  tending  to  minimise  the  effects  of  violence 
inflicted  upon  the  skull. — (1 )  The  density  and  mobility  of  the  scalp.  (2) 
The  dome-like  shape  of  the  skull.  This,  like  an  egg-shell,  is  calculated  to  bear 
relatively  hard  l>lows  and  also  Id  allow  them  to  glide  off.  (3)  The  number  of 
bones  tends  to  break  u'p  the  force  of  a  blow.  (4)  The  sutures  interrupt  the 
transmission  of  violence.  (5)  The  internal  membrane  (remains  of  fo'tal  peri- 
osteum) acts,  in  early  life,  as  a  linear  l)uffer.  (6)  The  elasticity  of  the  outer 
table.  (7)  The  overlapping  of  some  bones,  e.g.  the  parietal  l)y  the  squamous; 
and  the  alternate  bevelling  of  adjacent  bones,  e.g.  at  the  coronal  suture.  (8)  The 
presence  of  ribs,  or  groins,  e.g.  (a)  from  the  crista  galli  to  the  internal  occipital 
protulK'rance;  (b)  from  the  root  of  the  nose  to  the  zygoma;  (c)  the  temporal  ridge 
from  orbit  to  mastoid;  (d)  from  mastoid  to  mastoid:  (c)  from  the  external  occipital 
protuberance  to  the  foramen  magnum.  (9)  Buttresses,  e.g.  malar  and  zygomatic 
processes,  and  the  greater  wing  of  the  sphenoid.  (10)  The  mobility  of  the  head 
upon  the  spine. 

CRAXIO-CEREBRAL  TOPOGRAPHY 

To  make  as  clear  as  possible  the  points  of  practical  importance  which  have,  of 
late  years,  been  put  on  a  definite  basis,  and  which  the  surgeon  may  have  to  recall 
and  act  upon  at  very  short  notice,  cranio-cerebral  topograi)liy  will  lie  s})oken  of 


CRANIO-CEREBRA L    TOPOGRA  I'll  Y 


10H7 


iindi-r  tlie  following  licailiuL^s:  A.  Relation  of  the  brain  as  a  whole  to  the 
skull.  15.  Relation  of  the  chief  sulci  and  convolutions  to  the  skull.  ('. 
Localisation  of  the  chief  sulci  and  convolutions,  iitlon-  alluding'  to  tin- 
above,  it  is  necessary  to  say  distinctly  that  tlie  following  surface-markings  and 
p(jints  of  guidance  are  only  approximately  reliable,  for  the  following  reasons:  (1) 
In  two  individuals  of  the  same  age  and  sex  the  sulci  and  convoluti<tns  an;  never 
])recisely  alike.  (2)  Tlie  relations  of  the  convolutions  and  sulci  to  the  surface 
vary  in  different  individuals.  (3)  That  as  the  surface  area  of  the  scalp  and  outer 
aspect  of  the  skull  are  greater  than  the  surface  area  of  the  brain,  and  as  the 
convexities  do  not  tally,  lines  drawn  on  the  seal})  or  skull  cannot  always  corres])ond 
preeisely  to  cerel)ral  convolutions  or  sulci.  It  results  from  the  above  tliat  when  a 
delinite  area  of  the  surface  is  said  to  correspond  accurately  in  any  individual  to  :i 
definite  area  of  the  brain  surface,  this  result  has  l)een  correlated  from  many 
examinations;   and  that  as  surface-markings,   shape,  and   })rocesses  of  skull   ai.d 


Fig.  664. 


-The  Outline  ok  tiik  liRAix  and  its  Fissttkks  in  Relation  to  the  RrTiHEs 
OF  THE  Skull.     (Cunningham.) 


V.  p.B./  l<>v ''"''' v„ 


% .sf : 


j-^ 


"cr^j 


s  M.  Supraciliary  niarfjin  of  the  oerehiiini.  i.l.m.  Iiirtro-lateral  margin  of  tlie  cen-hrnm. 
L.s.  Po.sition  of  higllt'St  part  of  the  arrli  ol  tile  lateral  sinus,  i:.  Fissure  of  Kolando.  s'.  Anterior 
horizontal  limb  of  .*>\ivian  lissure.  s^.  Anterior  ascending  limb  of  Sylvian  fissure,  .s^  I'osterior 
horizontal  limb  of  Sylvian  ti.s.sure.  P.H.  Pars  ba.silaris  of  the  inferior  frontal  convolution.  r.T. 
Pars  triangularis  of  the  inferior  frontal  convolution.  P.O.  Pars  orliitalis  of  the  inferior  frontal 
convolution. 


arrangement  of  brain  surface  are  all  liable  to  varintions  in  difTcrmt  individuals,  the 
sui-L't'on  must  allow  for  these  variations  by  removing  more  than  tliat  definite  area  of 
skull  which  is  said  to  corresjxMid  exactly  to  that  i>art  of  the  lirain  which  he  desires 
to   eXpo>t\ 

A.  Relation  of  the  brain  as  a  whole  to  the  skull  (figs.  (W)4  and  (\(\(\^. — 
Traced  from  bd'orr  backwards,  tJic  Ininr  Irn  I  oj'  oirli  rnrhml  htiiiLsjilH  ir  would  follow 
a  line  across  the  forehead,  slightly  curved  upwards  al)ove  the  eyebrows,  cr(»ssing 
from  the  forehead  to  the  temjile  immediately  above  the  external  angular  process  of 
th(^  frontal.  It  then  descends  slightly  alonga  line  now  convex  forwards  in  tlie  front 
of  the  tem]»oral  fo.'S.-ia  to  about  the  centre  of  tlie  upper  margin  of  the  zygomatic 
arch.  From  this  ]><»int  a  line  should  be  drawn  just  above  the  external  au<litory 
meatus  to  the  external  oceijiital  jirotubcrance.  To  trace  tJM'  lower  levd  of  the 
brain  more  jirecisclv  on  the  skull,  the  chalk  would  start  from  tiic  lower  ])art  of  the 
glabella;  thence  the  line  i)ursues  a  course,  slightly  curved  ui)wards,  about  a  third  of 


1088  SURGICAL  AXD    TOPOGRAPHICAL  ANATOMY 

an  inch  above  the  supraorbital  niar<iin;  next,  crossing  the  temporal  crest  about  half 
an  inch  above  the  external  angular  process,  it  passes  not  quite  horizontally,  but 
descending  slightly  to  a  point  in  the  temporal  fossa  just  below  the  tip  of  the  great 
wing  of  the  sphenoid  (pterion),  an  inch  behind  the  external  angular  process. 
From  this  point  the  line  of  the  level  of  the  brain,  now  convex  forwards  and  corre- 
sponding to  the  anterior  extremity  of  the  temporo-sphenoidal  lobe,  would  dip  down, 
still  within  the  great  wing  of  the  sphenoid,  to  about  the  centre  of  the  zygoma. 
Thence  the  line  would  travel  along  the  ujiper  border  of  this  process  about  a 
quarter  of  an  inch  above  the  roof  of  the  external  auditory  meatus,  and  thence  just 
above  the  base  of  the  mastoid  and  the  posterior  inferior  angle  of  the  parietal,  and 
so  along  the  superior  curved  line,  and  corresponding  to  that  of  the  tentorium  and 
horizontal  part  of  the  lateral  sinus,  to  the  external  occipital  protuberance. 

The  upper  margin  of  each  hemisphere  would  be  represented  by  a  line  drawn 
from  just  below  the  glabella,  suthciently  to  one  side  of  the  middle  line  to  allow  for 
the  falx  and  superior  longitudinal  sinus,  to  one  immediately  a))ove  the  superior 
external  occipital  protuberance  and  ini<»n  (p.  1091  ). 

B.  Relation  of  the  chief  fissures  and  convolutions  to  the  skull.  Local- 
ization of  the  chief  sulci  and  convolutions.  These  headings  will  be  taken 
together. 

It  will  be  well  to  first  indicate  the  position  of  the  chief  sutures  which  mark 
off  the  parietal  bone,  under  which  lies  that  part  of  the  brain  which  is  most  impor- 
tant to  the  surgeon — the  motor  area.  The  upper  limit  of  the  bone  will  be  indicated 
by  the  line  already  spoken  of  as  giving  the  upper  margin  of  the  hemisphere — the 
sagittal  line,  or  suture  (p.  1091).  The  anterior  limit  of  the  parietal  bone,  formed 
by  the  coronal  suture,  may  be  traced  thus:  The  point  where  it  leaves  the  sagittal 
suture  (the  bregma)  will  be  found  by  drawing  a  line  from  a  point  just  in  front  of 
the  external  auditory  meatus  (the  preauricular  point)  (p.  1091,  figs.  659  and  665) 
straight  upwards  on  to  the  vertex;  from  this  point  a  line  drawn  downwards  and 
forwards  to  the  middle  of  the  zygomatic  arch  would  indicate  that  of  the  coronal 
suture.  Under  this  suture  lie  the  posterior  extremities  of  the  three  lateral  frontal 
convolutions;  for  the  frontal  lobe  lies  not  only  under  the  frontal  bone,  but  extends 
backwards  under  the  anterior  part  of  the  parietal,  the  fissure  of  Rolando,  which 
separates  the  frontal  from  the  parietal  lobe,  lying  from  one  and  a  half  to  two  inches 
l:)ehind  the  coronal  suture. 

The  squarnoso-parietal  suture,  which  marks  the  lower  border  of  the  anterior 
two-thirds  of  the  parietal  bone,  is  not  so  easy  to  define,  owing  to  the  irregularity 
and  variations  of  its  curve.  Its  highest  point  is  usually  one  and  three-quarter 
inches  above  the  zygoma. 

The  lambdoid  suture,  which  forms  the  posterior  boundary  of  the  parietal 
bone,  will  be  marked  out  by  a  line  which  starts  from  a  point  (lambda)  two  and 
three-quarter  inches  above  the  external  occipital  protuberance,  and  runs  downwards 
and  forwards  to  a  point  on  a  level  with  the  z3'goma,  one  and  three-quarter  inches 
behind  the  meatus. 

The  })osition  of  the  chief  sulci  will  now  be  given: 

Sylvian  fissure  (figs.  664  and  665). — The  point  of  appearance  of  this,  on  the 
outer  side  of  the  brain,  practically  corresponds  to  the  i)terion  (fig.  659) — a  point 
which  lies  in  the  temporal  fossa,  about  an  inch  and  a  half  behind  the  external  an- 
gular process  and  about  the  same  distance  above  the  zygoma.  From  this  point  the 
Sylvian  fissure,  which  here  separates  the  frontal  and  parietal  from  the  temporo- 
sphenoidal  lobe,  runs  backwards  and  upwards,  ascending  gently,  at  first  in  the  line 
of  the  squamo-parietal  suture,  then  crossing  this  suture  about  its  centre,  and  thence, 
ascending  more  rapidly,  it  climbs  up  to  the  temporal  ridge,  to  end  three-quarters  of 
an  inch  l)elow  the  parietal  eminence.  Its  termination  is  surrounded  by  the  supra- 
marginal  convolution,  to  which  the  parietal  eminence  corresponds  with  sufficient 
accuracy.  Such  being  the  surface-marking  of  the  chief  or  ])osteri()r  borizontal  limb 
of  the  fissure  of  Sylvius  (s'^,  fig.  664),  it  remains  to  indicate  briefly  the  tAvo 
shorter  limbs  which  bound  the  inferior  frontal  convolution,  which,  on  the  left  side, 
contains  the  centre  for  speech  (Broca's  convolution).  Of  these,  the  anterior  hori- 
zontal (s^,  fig.  664)  runs  forwards  across  the  termination  of  the  coronal,  just 
above    the   line    of  the  spheno-parietal   suture.     The    ascending    limb    (s^,    fig. 


CRANIO-CKIIEBRAL   TOPOnL'APHY  10S9 

664)  runs  up^vards  fcr  al-ent  an  inch  just  l.cl.in.l  tli.- termination  of  tlic  con-nal 
suture,  or  two  nHlu'S  bchnul  the  extornal  angular  \mHv^^.  T..  indicate  the  ti^-ur.' 
of  ►"^.yjvms,  a  hne  should  l.e  (h-awn  from  a  point  corresix.nrlinf:  to  the  i.terion 
(p.  1081,  fig.  6o9)  backwards,  at  tirst  gently  and  th.-n  more  al.ruptlv  up- 
wards, to  one  three-(iuarters  of  an  inch  helow  the  j.arietal  eminence  '  The 
ascending  limb  will  start  from  a  point  two  inches  behind  and  slightly  above  tlie 
external  angular  process,  and  more  oblitiuelv  forwards  and  uj.wards  for  al>out  an 
mch. 

Fissure  of  Rolando.— This  most  important  fissure,  around  which  the  ux.tor 
area  is  grouped,  runs  downwards  and  forwards,  separatinu  the  frontal  and  parietal 
lobes  between  the  following  points:  The  upper  end  of  the  Hssure,  the  upper 
Rolandic  point,  will  be  found  about  half  an  inch  behind  the  centre  of  the  sagittal 


Fio.  6Go.— Drawixg  of  a  Cast  of  the  Head  of  ax  Adii.t  Mai.k. 
(Prepared  by  Professor  Cuuniugham  to  illustrate  crauio-cere))ral  topograpliy. ) 


FissrjiE  nr 

ROLASVO 


POSITION  OF 
FRONTAL  EMINENCE 


mini)  LP. 

TEMPIiHAL 
FlaSCHll 


line  Tp.  lOOO") — a  line  drawn  from  just  below  the  glabella  to  the  external  occijiital 
protuberance.  On  the  skull,  this  upj>er  Rolandic  jmint  will  be  nearly  tw..  inches 
behind  the  bregma.  The  lower  extremity  of  the  fissure,  inferior  Rolandic  point, 
would  be  about  half  an  inch  above  the  Sylvian  line  and  one  inch  Ixhind  the 
Sylvian  point  (fig.  666).  Owing  to  the  obiicpiity  of  the  fissure  of  Rolandi..  thi.s 
lower  point  will  be  nearer  tin-  ciinmal  suture  than  the  uppei-.  being  distaiU  fn>m  it 
about  «)ue  inch.  A  lin(>  drawn  between  the  ujiper  and  lower  Hnlandic  ])oints  (the 
Rolandic  line)  will  give  the  direction  of  the  fissure  of  Rolando  with  sufficient  accu- 
racy, when  the  two  genua,  the  upper  c<tncave  and  the  lower  convex  fonvards  (fig. 
664)  are  allowed  for.  The  Rolandic  line  forms  with  the  sagittal  line  an  angle 
anteriorly  of  6o°  to  70°;  if  jtrohmged  downwards  and  f<»rwards  t<»  the  zvgoma,  the 
line  would  reach  this  process  about  its  centre  (Le  Fort;. 
60 


1090 


SURGICAL   ASD    TOPOGRAPHICAL  AXATOMY 


To  find  the  fissure  of  Rolando  the  following  methods  have  been  emi)loyed.  In 
a  given  case  it  is  well  to  enipk)y  them  all,  so  that  any  error  in  one  may  be  checked 
b}'  another  measurement: 

I.  The  upper  and  lower  Rolandic  points  are  found  as  above  directed,  and  the 
Rolandic  line  is  drawn  between  them. 

II.  The  upper  Rolandic  point  is  taken  two  inches  behind  the  bregma,  or  junction 
of  the  coronal  and  sagittal  sutures.  The  position  of  the  lower  end  of  the  fissure  is 
thus  determined:  From  the  very  end  of  the  external  orbital  process,  where  this  rises 
up  to  join  the  temporal  crest,  draw  a  horizontal  line  two  and  a  quarter  inches  long, 
and  from  the  extreme  end  of  this  draw  a  vertical  line  of  a  little  over  one  inch. 
Between  these  upper  and  lower  Rolandic  points,  ])assing  rather  oljliquely  forwards, 
lies  the  fissure  of  Rolando  (Lucas,  Championniere). 

III.  Here  (1)  the  sagittal  line  is  taken;  (2)  and  (3)  at  a  right  angle  to  this 
two  lines  are  drawn  vertically  over  the  side  of  the  skull, — the  one  starting  from 
the  pre-auricular  point  (fig.  666),  the  other  at  the  level  of  the  posterior  border  of 
the  mastoid  process, — and  meeting  the  sagittal  line  about  two  inches  behind  the 
second;  (4)  from  the  junction  of  the  lines  1  and  3,  one  is  drawn  diagonally  down- 


FiG.  666. — Craxio-cerebral  Topography.     (Anderson  aud  Makins.) 

■  SQUAMOSAL  POINT 


Course  of  anterior  divi- 
sion of  middle  menin- 
geal artery 


ROLANDIC  FISSURE,  LOWER 
END 

Froiitdl  branch  of  iiiid- 

il/f  ini'tiiiu/fiil  iirtfri/ 

COMMENCEMENT  OF  SYLVIAN 

FISSURE 

ANGULAR  POINT 

GLABELLAR  POINT 


ANTERIOR  MENINGEAL 
POINT 


MID-SAGITTAL  POINT 
ROLANDIC  FISSURE,  UPPER 
END 


TERMINATION   OF    SYLVIAN 

FISSURE 
TERMINAL  ANGLE  OF  SYL- 
VIAN FISSURE 
LAMBDA  AND  EXTERNAL    PA- 

RIETO-OCCIPITAL  FISSURE 
POSTERIOR  MENINGEAL 
POINT 


MASTOID  ANTRUM 


Course  of  posterior  division 
of  middle  meningeal  artery 


POINT  OF  BIFURCATION  OF 
SYLVIAN   FISSURE 


PREAURICULAR  POINT 


wards,  reaching  2  about  two  inches  above  and  a  little  in  front  of  the  external 
auditory  meatus  (Reid  and  Godlee). 

I'-  The  fissure  of  Rolando  may  be  found  l)y  the  measurements  given  bv  INIakins 
and  /\nderson  (fig.  666). 

The  external  parieto-occipital  fissures. — The  upi)er  end  of  this  will  a})pear 
just  in  fr(.)nt  of  the  lambda. 

Before  leaving  this  subject,  the  attention  of  the  student  and  surgeon  is  drawn  to 
fig.  666  and  the  method  which  it  illustrates — that  of  Anderson  and  JNIakins.  As 
claimed  by  these  surgeons  and  anatomists,  their  method  fulfils  the  recjuirements  of 
any  ])ractical  scheme  of  cranio-cerebral  topography,  viz. :  (1)  The  cranial  landmarks 
employed  shall  be  distinct,  and  subject  as  little  as  possible  to  variations  in  rela- 
tion to  the  general  proportions  of  the  skull-cap;  (2)  that  the  guiding  lines,  drawn 
by  the  aid  of  these  landmarks,  shall  ada|)t  tlKMuselves  to  skulls  of  varying  size  and 
conformation;  and  (3)  that  no  special  aj^paratus  shall  be  rcipiired  for  the  localisa- 
tion. 

The  method  recommended    by  Anderson  and  ^Nlakins  is  the  following:    The 


TllK  FACE.  1().»1 

cranial  landmarks  (fif,'.  6G6)  are  (1)  the  glabellar  point,  in  the  midliuc  ..f  ili.* 
nasal  eminence,  on  a  level  with  the  ui)iter  margin  of  the  orbits;  (2)  the  inial  point, 
corresi)onding  to  the  external  occipital  protuherance;  (3)  the  mid-sagittal  point] 
midway  between  these;  (4)  the  pre-auricular  point,  in  front  of  the  tragus,  dii  a 
level  with  the  upper  border  of  the  external  auditory  meatus;  (5)  the  angular 
point,  over  the  external  angular  jjrocess,  on  a  level  with  the  upper  border  of  iIk 
orbit;  (6)  the  squamosal  point,  at  the  junction  of  the  middle  and  lower  thirds  of 
the  line  (Frontal  line)  lietwicn  the  i)re-auricular  and  mid-sagittal  points.  By  the 
aid  of  these  points,  three  lines  may  be  drawn  ujton  the  sliaven  scal]>  d<fiiiit<lv 
related  to  the  ])rincii)al  lissurcs  of  the  outer  surface  of  the  brain:  (1 )  The  sagittal 
line,  from  the  glabella  to  tiie  inion;  with  this  line  coincides  the  longitudinal  fissure. 
(2)  The  squamosal  line,  from  the  angular  to  tlie  squamosal  i)oint,  and  about  two 
inches  beyond;  in  this  line  and  its  continuation  lies  the  fissure  of  Sylvius.  (3)  The 
frontal  line,  from  the  pre-auricular  to  the  mid-sagittal  point.  The  fissure  of 
Rolando  crosses  this  line  at  an  acute  angle.  Its  upper  end,  carried  to  the  midline, 
lies  three-eighths  of  an  inch  l)ehind  the  mid-sagittal  point;  its  lower  end,  in  the 
squamosal  line,  three-eighths  of  an  inch  beyond  the  squamosal  point. 


THE  face; 

The  outline  of  the  different  bones — nasal,  upper  and  lower  jaws,  malar,  and 
zygoma — can  be  readily  traced. 

Arteries. — The  supraorbital  artery  can  be  felt  beating  just  above  its  notch 
(junction  of  inner  with  outer  two-thirds  of  supraorbital  arch);  the  temporal  itself 
can  be  felt  where  it  crosses  the  root  of  the  zygoma  just  in  front  of  the  tragus,  its 
anterior  branch  about  an  inch  and  a  (juarter  above  and  behind  the  external  angular 
process  of  the  frontal;  the  occipital  (p.  1102)  pulsates  near  the  middle  of  a  line 
draAvn  from  the  occipital  protuberance  to  the  mastoid  ])roc('ss:  the  posterior 
auricular  behind  the  apex  of  the  mastoid.  The  external  carotid  lies  l)eliiiid  tin- 
ascending  ramus  of  the  jaw.  The  facial  (fig.  667)  crosses  the  jaw  just  in  front  of 
the  masseter;  if  divided,  both  ends  nmst  be  secured  here.  It  can  be  felt  again  a 
little  behind  the  angle  of  the  mouth,  just  lieneath  the  mucous  membrane  (it  here 
gives  off  the  coronaries,  which  can  also  be  felt,  lying  deeply,  if  the  lip  is  taken 
between  the  finger  and  thumb);  and  again  by  the  side  of  the  nose,  as  it  runs  up  to 
the  tendo  oculi.  To  trace  the  course  of  the  facial  artery  a  line  should  be  drawn  from 
a  point  a  little  above  and  outside  the  tip  of  the  great  cornu  of  the  hyoid  to  the 
lower  ])art  of  the  anterior  })order  of  the  masseter.  and  thence  to  one  outside  and 
above  the  angle  of  the  mouth,  and  so  onwards,  external  to  the  angle  of  the  nose, 
up  to  the  inner  canthus.  The  litth-  frontal  artery  is  of  importance,  as  it  nourishes 
the  flap  when  a  new  nose  is  taken  from  the  forehead. 

A  line  drawn  from  the  tip  of  the  lol)ule  of  the  ear  to  a  point  midway  between 
the  nose  and  upper  lip  gives  the  level  of  the  parotid  duct,  which  o];ens  into  the 
mouth  opposite  the  second  upper  molar  tooth.  The  level  of  the  duct  would  be 
about  a  finger's  breadth  below  the  zygoma.  It  is  accomjjanied  by  the  transverse 
facial  artery  above,  and  the  infraorl)ital  branch  of  the  facial  nerve  below.  The 
sheath  of  the  parotid,  continuous  with  those  of  the  masseter  and  sterno-niastoid, 
is  strong  enough  to  cause  most  ex(iuisitely  painful  tension  when  inllannnation  of 
the  gland  is  ])resent. 

Tlu' parotid  region  would  be  thus  mapi>ed  out  (tig.  <".70).  Above  by  the  pos- 
terior twothirds  of  the  zygoma,  helmr  by  a  line  eorres])onding  to  the  posterior  belly 
of  the  <ligastric  (tig.  070);  bc/iind  are  the  external  auditory  meatus,  mastoid,  and 
sternomastoid.  In  front  the  gland  and  socia  parotidis  overlap  the  ])osterior  jiart  of 
the  masseter.  to  a  variable  degree  (fig.  670). 

The  proximity  of  the  parotid  to  the  styloid  process,  to  which  the  pharynx  is 
attached,  accounts  for  dee])  jiarotid  abscess  opening  into  the  pharynx.  Below  the 
ro<it  of  the  zvgoma.  when  this  process  is  traced  backwards,  will  be  felt  the  temporo- 
mantlibular  joint;  and  wlu-n  the  mouth  is  opened,  the  condyle  will  be  felt  to  glide 
forwards  upon  the  eminentia  articulari;?. 


1092 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


THE  EYELIDS  AND   LACHRYMAL  APPARATUS 

The  structure  of  the  Hds. — The  different  layers  are  of  much  practical  impor- 
tance. ( 1 ;  The  skin  is  delicate  and  fatless,  and  contains  pigment,  the  object  of 
this  being  to  protect  the  eye  from  bright  light.  It  helps  to  explain  the  '  dark 
circles'  of  later  life.     (2)  Areolar  tissue.     Owing  to  its  looseness  and  delicacy, 


Fig.  667. — Scheme  of  the  Facial  Aktery. 


Orbicularis  palpebrarum 
muscle 


Transverxe  facial  artery 

Zygomatieus  minor 
muscle 

Zygomatieus  major 
muscle 


Buccinator  muscle 
Masseteric  branch 
Masseter  muscle 


Siylo-pharyngeus 
muscle 
Stylo-glossus  muscle 

Ascendint)  palatine 
branch 
Tonsillar  branch 


Facial  artery 

External  carotid 

artery 

Posterior  belly  of 

digastric  muscle 

Lingual  arter 


Frontal  branch  of  ophthalmic 

artery 
Xasal  branch  of  ophthalmic 

artery 


Angular  artery 
Levator  labii  super- 
ioria    et    alse    naai 
muscle 
Iiifranrliital  artery 
Levator  labii  super- 

ioris  proprius 
Lateralis  nasi  artery 
Levator  anguli  oris 
muscle 

Artery  of  septum 

Superior  coronary 

artery 


Risorius  muscle 


Inferior  coronary  artery 

Mental  branch  of  inferior 
denial  artery 

Depressor  labii  inferioris 

muscle 
Iiiferiiir  labial  artery 
Depressor  anguli  oris 
muscle 

Submental  artery 
Branches  to  submaxillary 
gland 

Anterior  belly  of  digastric  muscle 
Mylo-hyoid  muscle 


Hyo-glossus  muscle 


HYPOGLOSSAL  NERVE 


this  is  very  liable  to  infiltration,  as  in   ascites  and  erysipelas.      (- 

Paralysis  of  this,  tlie  palpebral    portion,  leads  to  epi]")liora,  the  ].uiicta   bein^ 


0  Orbicularis. 

longer  kept  applied  against  the  eye.  (4)  Palpebral  ligament,  rcacliing  from  the 
orbit  to  the  tarsal  cartilage.  This  is  usually  strong  enough  to  i)revent  luemorrhage, 
due  to  fractured  base  of  skull,  Ijecoming  subcutaneous.  (5)  Levator  palpebrae. 
(6)  Tarsal  cartilage  ;  in  reality,  densely  felted  fibrous  tissue.      (7)  Meibomian 


EYELIDS  AND   LACHRYMAL   A  PI' A  R  ATI'S 


1003 


glands,  lashes,  and  sebaceous  follicles.  Localised  inflammation  starting  in 
any  of  tla'^t'  Ihive  structures,  especially  the  last,  will  cause  a  'stve.'  The  fre- 
quency with  which  the  lid-border  is  the  seat  of  that  most  troublesome  chronic 
inflammation,  blepharitis,  and  its  result  'blear  eye,'  is  explained  l»y  these  ana- 
tomical points.  Its  circulation  is  terminal  and  slow;  half  skin  and  half  mucous 
membrane,  it  is  moister  and  more  lial)le  to  local  irritation  than  the  skin;  while  its 
numerous  glands  readily  participate  in  any  intlanunation.  (.S)  The  conjunctiva. 
To  trace  this  important  membrane,  the  lids  should  be  everted,  when  tlie  following 
will  be  noted.  The  conjunctiva  over  the  tarsal  part  of  the  lid  is  closely  adlierent, 
and  through  it,  a  series  of  nearly  straight,  parallel,  light  yellow  lines  and  granules, 
the  Meibomian  glands,  can  be  seen.      Beyond  the  tarsi,  the  conjunctiva,  now  p;il- 


FlG. 


668.— Vertical  Traxsvkrsk  Skctiox  TiiKorcJH  the  Uppkk  EvKi,n>. 
(Alter  Wukk-yer  aud  Fucha.) 


Cutaneous  surface  just 
above  superior  palpe- 
bral fold 

Orbicularis  fibres,  out 
across 


FINE  HAiR  WITH  SEBACEOUS 
GUND  AT  ITS  BASE 


Orbicularis  fibres,  cut 
across 


MODIFIED  SWEAT  GLANO  OF 
MOLL 


#^  (I 


r-  CONJUNCTIVA  NEAR  FORNIX 


Anterior  layer  of  inser- 
tion of  levator  palpe- 
brae  superioris 

Superior  palpebral 

muscle  of  Muller 

Fibres  from  levator 
passinK  through 
orbicularis  to  skin 

Superior ratcular  arch, 
cut  across 


WALOEYER'S  GUNOS 


Conjunctival  papillae 
over  attached  border 
of  tarsus 


Posterior  edge  ot  lid- 
margtn 


OPENING  OF  DUCT  OF 
MEIBOMIAN   GUSO 


pebral,  is  thicker  and  freely  movable,  owing  to  the  abundant  submucous  tissue. 
Numerous  underlying  vessels  are  visil)le  here.  Tracing  the  ct.»njunctiva  onwanls 
over  the  .sclerotic,  the  former  becomes  thinner  anil  contains  very  few  vessels,  any 
present  still  moving  with  it  (conjunctival).  Occasional  vessels  seen  through  the 
sclerotic  conjunctiva  are  attached  to  the  sclerotic  itself  (anterior  ciliary).  At  the 
junction  of  the  palpeliral  and  ."clerotic  conjunctiv£e  is  the  reflexion  called  the 
fornix.  On  this  reflexion  in  the  upper  lid  open  the  lachrymal  ducts.  Traced 
onwards  over  the  cornea,  the  conjunctiva  becomes  thinned  down  to  a  mere 
epithelial  layer,  closely  adherent  to  tlie  subjacent  parts. 

The    differing   structure    of   the   )»alpebral   and   ocular  ])ortion   has   important 
bearings.     Thus  the  ])aliieViral  is  thick,  highly  vascular,  and  very  sensitive.     To 


1094 


SURGICAL  AXD  TOPOORAPHICAL  AXArOMY 


this  vascularity  we  owe  the  eheinosis,  or  hot,  red,  tense  swelling  of  ]>urulent 
ophthalmia.  The  exquisite  suffering  of  the  same  disease,  or  that  caused  hy  a 
foreign  l)ody,  is  explained  by  the  numerous  nerve-i»ai)illa'.  To  the  thickness  and 
abundance  of  the  connective  tissue  are  due  the  contraction  and  permanent  thicken- 
ing which  may  occur  in  granular  lids.  The  so-called  granulations,  met  with  in  this 
disease  on  the  palpebral  conjunctiva,  are  really  little  nodules  of  hypertrophied 
lymphoid  follicles,  or  mucous  glands,  which  abound  here. 

The  position  of  the  lachrymal  puncta  should  be  noted;  owing  to  their  back- 
ward direction,  the  lids  must  be  previcnisly  everted.  The  puncta  are  kept  open  by 
a  minute  fil^rous  ring. 

Each  is  situated  on  a  minute  i)apilla  at  the  junction  of  the  inner  and  straight 
third  of  the  lid  with  the  outer  curved  two-thirds.  Close  to  the  inner  canthus,  in 
addition  to  the  puncta  and  papilla?,  should  be  noted  the  caruncula  lachrymalis,"  with 


Fig.  669. — The  Lachkymal  Appaeatus  and  Nasal  Duct.     (Bellamy.) 
(Bristles  are  introdnced  into  the  pniicta  lachrymalia.) 


INNER  WALL  OF  ANTRUM 


,  LACHRYMAL  SAC 


.  Tendo  oculi 


Valvular  folds  in  nasal  duet 


LOWER  TURBINATED  BONE  Orifice  of  nasal  duct 


its  delicate  hairs,  and  the  plica  semilunaris,  which  corresponds  to  the  third  eyelid 
of  certain  birds. 

The  lachrymal  sac  is  the  most  important  of  the  lachrymal  apparatus,  from  its 
disfiguring  diseases;  it  lies  in  a  bony  groove,  between  the  nasal  process  of  the 
maxilla  and  the  lachrymal  bone.  The  tendo  oculi  crosses  it  a  little  above  its 
centre  (fig.  669).  Thus  two-thirds  of  the  sac  are  below  the  tendon,  and  in  sujipuration 
the  opening  is  made  Ijelow  it  also.  The  angular  artery  ascends  on  the  nasal  side  of 
the  sac.  The  manipulation  of  a  probe  along  the  lachrymal  passages  should 
thus  be  practised: — The  loAver  lid  l)eing  drawn  outwards  and  downwards  by  the 
thumb,  the  probe  is  passed  vertically  into  the  punctum,  then  turned  horizontally 
and  passed  on  till  it  reaches  the  inner  wall  of  the  sac.  It  is  then  raised  vertically, 
and  pushed  steadily  along  the  duct  downwards,  and  a  little  outwards  and  back- 
wards, till  the  floor  of  the  nose  is  reached. 

If  the  eyes  are  opened  naturally,  the  greater  part  of  the  cornea,  behind  it  tlie 
iris,  with  the  i)upil  in  the  centre,  on  either  side  of  the  cornea  some  of  the  sclerotic, 
the  semilunar  fold  and  caruncle  can  be  seen. 


THE  MOUTH 


1005 


THE  MorTH 

On  the  floor,  in  the  centre,  is  the  frtenuiu  Hnfrute.  In  (lividin-r  the  fraenum  for 
tongue-tie,  the  scissors  should  he  kept  close  to  the  bone,  so  as  to  avc.id  tin-  raninc 
vessels.  Of  these,  the  ranine  vein  can  he  seen  !.<  ncath  tlx-  nnuoiis  nMiiil)ranc;  the 
artery  lies  close  to  it,  l>ut  deeper. 

The  orifices  of  Wharton's  duet  open  on  minute  i)ai.illa'  situated  at  the  ends  of 
ridges  of  mucous  menihrane  whicii  curve  forwards  and  inwards  to  meet  in  tlie 
middle  line  a  Httle  behind  the  sym])liysis  of  the  jaw,  on  either  side  (.f  the  fnenum 
lingu;e  (fior.  670).  Togetiier  with  Wharton's  duet,  or  close  to  it,  opens  the  duct 
of  Jiartholin,  or  chief  duct  of  the  sublingual  gland.  If  the  above  folds  be 
traced  backwards  they  correspond,  as  they  diverge,  to  the  ranine  veins,  and,  more 
deeply,  to  Wharton's  duct  and  the  lingual  nerve  (fig.  670).     Under  these  ridges  lie 

Fig.  670.— Side  of  the  Face  and  Morrn  Cavity,  showixc;  thk  Tukkk 
Sai.ivakv  Glands. 


"S^^MMMi. 


SOCIA  PAROTIDIS 


DUCT  OF  SOCIA 
PAROTIDIS 


DUCT  OF  PAROTID 


Bristle  inserted 
into  duct 


Freenum  linguaB 


DUCT  OF  RIVINI 


SUBLINGUAL  6LAN0 


PAROTID  GUNO 


Maaseter  muscle 


Sterno-mastoid 
muscle 


Posterior  belly  of 
digastric  muscle 


SUBMAXILLARY  GLAND, 
DRAWN  BACKWARDS 


-  Loop  of  fascia 


DUCT  OF  SUBMAXILLARY 
GUND 
Mylo-hyoid  muscle 


Anterior  belly  of 
digastrio  muscle 


DEEP  PORTION  OF  SUBMAXILURY  GUNO 


the  sublingual  glands,  the  majority  of  whose  ducts  ojkh  on  tlif  surtaee  ot  the 
folds.  Dilatation  of  one  of  these  Kivinian  ducts,  more  fretjUently  dilatation  of  a  mu- 
ciparous gland, — and  much  more  rarely  dilatation  of  Wharton's  duct. — constitutes 
a  '  ranula.'  The  submaxillary  gland  can  be  felt  nearer  the  angle  of  the  jaw  lying 
Itetween  its  fossa  and  the  mucous  jiiembrain'.  ispecially  if  ])ressure  is  made  from 
outside.  The  attachment  of  the  genio-hyo-glossi  can  l>e  felt  luhind  the  sym- 
]>hysis:  the  division  of  the  muscles  allows  the  tongue  to  come  well  out  of  the 
mouth;  but  when  both  have  to  be  divided,  the  tongue  loses  much  of  its  steadiness, 
and  may  easily  fall  back  over  the  larynx  during  the  administration  of  the  anaw:- 
thetic  or,  later  on,  in  sleep.  It  should  therefore  be  secured  forwards  for  a  while 
with  silk.  While  the  mouth  is  widely  ojien,  the  pterygo-mandibular  ligament  can 
be  seen  and  felt  beneath  tlie  mucous  membrane,  behind  the  last  molar  tooth.  Just 
below  and  in  front  of  tlie  lower  attachment  of  this  ligament,  the  lingual  nerve  can 
be  felt  lying  close  to  the  bone  below  the  last  molar.  It  can  be  divided  here  to  give 
relief  from  pain  in  incuralde  cancer  of  the  tongue,  at  a  point  where  it  cros.<es  a  line 


1096 


SURGICAL  ASD   TOPOGRAPHICAL  AXATOMY 


drawn  from  the  last  molar  tooth  to  the  angle  of  the  jaw,  by  entering  a  knife  nearly 
three-quarters  of  an  inch  behind  and  below  the  tooth,  and  cutting  towards  it  on  the 
l)one  (Moore).  Another  and  far  simpler  and  surer  method  is  to  draw  the  tongue 
out  of  the  mouth  and  expose  the  nerve  where  it  lies  superficially  under  the  mucous 
membrane  thus  made  ]jrominent  between  the  side  of  the  tongue  and  gums,  the 
centre  of  the  incision  being  opposite  to  the  last  molar  tooth  (Roser,  Letievant). 

Behind  the  last  molar  tooth  can  be  felt  the  coronoid  process,  and  higher  up, 
just  behind  and  inside  the  tooth,  the  hamular  process  of  the  sphenoid.  This 
process  is  a  landmark  to  the  site  of  the  posterior  palatine  canal,  which  lies  just  in 
front  of  it,  and  which  transmits  the  posterior  and  descending  palatine  branch  of 
the  internal  maxillary,  together  with  the  anterior  or  great  palatine  nerve.  The 
vessel  and  nerve  run  forwards  in  grooves  towards  the  anterior  palatine  canal,  and 
their  position  must  be  remembered  in  raising  the  flaps  during  the  operation  for 


Fig.  671.— Sectiox  of  the  Skull  and  Bratx  ix  the  Median  Plane.     (Braiine.) 


PITUITARY  BODY 
OCCIPITAL  BONE 

EUSTACHIAN  TUBE 


Genio-hyo-glos8us 

Mylo-hyoid 


Arytenoideus  muscle 

RIMA  GLOTTIDIS 


THYROID  BODY 
Sterno-thyroid  muscle 


Falx  cerebri 

Superior  longitudinal 


L^      Inferior  longitudinal 
\  1   t  sinus 

'" —  Corpus  eallosum 

Optic  chiasma 
Corpus  mammiUai'e 

Posterior  lobe  of 

cerebrum 
Pons  Varolii 
Cerebellum 
Torcular  Herophili 

^lil*^  ^^vi-'//    '         Medulla 
— '•'•^'  ■   ' —   —    oblongata 

POSTERIOR  RING  OF  ATLAS 
DY  OF  AXIS 


BODY  OF  SECOND  THORACIC  VERTEBRA 


closure  of  a  cleft  in  the  hard  palate.      To  ensure  the  vitality  of  the  flaps  the 
incisions  must  be  made  close  to  and  parallel  with  the  ui)per  alveolus. 

On  the  inner  side  of  the  coronoid,  between  it  and  the  tuberosity  of  the  upjier 
jaw,  is  a  recess  where  a  temporal  abscess  will  point,  having  travelled  down  under 
the  fascia  and  zygoma.  When  a  patient  breathes  deeply  through  the  mouth,  and 
the  head  is  thrown  l)ack,  the  soft  palate  is  raised,  the  pillars  are  separated,  and  the 
uvula  and  fauces,  with  the  anterior  and  posterior  pillars,  the  tonsils,  and  the  back 
of  the  pharynx  are  exposed.  This  portion  of  the  pharyngeal  mucous  membrane 
would  lie  over  the  lower  ]iart  of  the  second  and  the  upper  ]iart  of  the  third  cervical 
vertebrae,  the  anterior  arch  of  the  atlas  corresponding  to  the  level  of  the  ]-)ostcrior 
nares,  and  the  body  of  the  axis  to  the  level  of  the  soft  palate  (fig.  671).  If  a 
finger  be  introduced  past  the  soft  palate  to  this  part  of  the  spine  and  turned 
upwards  and  downwards,  it  is  possible  to  examine  the  upper  four  or  five  and,  in 
children,  six  vertebrae,  as  far  as  the  anterior  surfaces  of  their  liodies.  '  The  part  of 
the  column  which  is  accessible  to  a  straight  instrument  introduced  through  the 


MO  I  'Til— PA  A.  1  TE—XOSE  1 097 

mouth  is  very  limited,  extending,  in  the  aduh.  from  the  lower  Lord,  r  of  tii.-  axis 
to  the  middle  or  lower  i)art  of  the  fourth  eervioal  vert(^l)ra;  in  the  child,  <»wing 
to  the  small  size  of  the  face,  it  comprises  the  bodies  (»f  tlie  axis  and  of  the  third 
cervical  vertebra.'      (Thane  and  (iodlcc.  from  Chipault. ) 

TONSILS. — The  relations  of  the  tonsils  sliouid  \n-  carefully  examined.  Tims, 
they  are  separated  externally  by  the  superior  constrictor  and  pharynjreal  aponeuro- 
sis from  the  ascendini^f  pharyiifical  and  internal  canttid  arteries.  Th<-  extent  to 
Avhich  the  tonsil  is  covered  by  the  anterior  pillar,  how  far  it  ])roject.<  U]iwards 
beneath  the  soft  palate  or  downwards  into  the  pharynx,  have  all  imi)ortant  bear- 
ings on  the  mode  of  removal.  Its  position  corre.«j)onds  to  the  angle  of  the  jaw. 
When  serious  haemorrhage  follows  oi)erations  on  the  tonsils,  it  usually  c<»mes  from 
one  of  the  numerous  tonsillar  arteries,  which  is  enlarged,  and  not  from  tlie 
ascending  pharyngeal  or  internal  carotid. 

The  finger  introduced  downwards  at  the  back  of  the  mouth,  especially  if 
the  parts  are  rendered  insensitive  by  cocaine,  feels  the  cinumvallate  jtapilhe,  the 
lingual  and  laryngeal  surfaces  of  the  epiglottis,  the  aryteno-ejiiglottidean  folds, 
with  the  cartilages  of  Wrisberg  and  l^antorini.  If  the  finger  be  moved  upwards 
behind  the  soft  palate  and  turned  upwards  to  the  base  of  the  .-kull.  and  tb.ii 
forwards,  it  will  impinge  on  the  posterior  nares.  se])arated  by  the  vomer,  and, 
within  each  nostril,  tlie  hinder  end  of  the  inferior  and  middle  spongy  bones;  above 
and  behind  is  felt  the  basilar  process  of  the  skull,  the  vault  of  pharynx,  and 
upper  cervical  spine  (fig.  671). 

The  size  of  the  nares,  one  inch  l)v  half  an  inch,  and  the  presence  of  any 
adenoids,  are  especially  to  l)e  noted.  The  richness  of  the  naso-pharynx  in 
glandular  structures,  its  proneness  to  inliamniatinu.  and  of  this  iiiliaiuiiKition  tn 
spread  to  other  parts, — e.g.  the  tympanum, — are  well  known.  The  tinger  should 
be  familiar  Avith  the  feel  of  adenoids — i.e.  hypertrophicd  post-nasal  lymphatic 
nodules — soft  bodies  of  irregular  shape  blocking  u])  the  naso-pharynx.  To  make 
out  how  far  this  is  the  case,  it  is  well  to  take  the  nasal  septum  as  the  starting-point. 


THE    PALATE 

Between  the  diverging  })illars  of  the  soft  ])alate  is  the  isthmus  faucium, 
bounded  above  by  the  free  margin  of  the  palate,  and  below  by  the  dorsum  f>f  the 
tongue.  Of  its  lateral  boundaries,  the  posterior  ]»illars  come  nearer  each  other 
than  tlu^  anterior.  In  paring  the  edges  of  a  cleft  soft  palate,  the  folloAving 
structures  would  be,  successively,  cut  through  :  i  1  i  <  )ral  muc<.us  hk mbram': 
(2)  submucous  tissue,  with  vessels,  nerves,  and  glands;  (o)  palato-glossus  muscle; 
(4)  aponeurosis  of  tensor  palati;  (5)  anterior  fasciculus  of  jtalato-pharyngeus; 
(6)  levator  palati  and  azygos  uvulae  muscles;  (7)  posterior  fasciculus  of  i>alato- 
pharyngeus;  (8)  submucous  tissue,  vessels,  nerves,  and  glands;  (9)  posterior 
mucous  membrane.  The  soft  ]ialate  is  thicker  than  it  seems,  the  average  in  an 
adult  being  a  <juarter  of  an  inch.  The  muscles  widening  a  cleft  are  the  tensor 
and  levator,  while  the  superior  constrictor  closes  it  in  swallowing.  Of  the 
arteries  to  the  palate,  the  largest  is  the  descending  jialatine  branch  of  the 
internal  maxillary.  This  emerges  from  the  posterior  )>alatine  canal  <lose  to  the 
inner  side  of  the  la.st  molar  tooth,  and  runs  forwaril  to  supply  the  hard  palate 
Cpaire  49G). 

THE   NO^JE 

On  the  face  the  outline  of  the  na.sal  bones  can  be  easily  traied,  an<l  l)elow  them 
the  upper  lateral  cartilages,  flat  and  also  somewhat  triangidar.  Below  these  are 
the  lower  lateral  cartilages,  curved  and  so  folde<l  back  that  each  forms  an  outer 
and  an  inner  plate.  Of  these  the  inner  meet  below  the  sej^tal  cartilage  to  f<irm  the 
ti]i  of  the  nose,  while  the  outer  curve  l)ackwards,  and.  togetlu-r  with  dense  nKi.>Jses 
of  cellular  tissue  and  fat  and  accessory  cartilages,  form  the  ake. 

With  the  sj^ecidum.  especially  if  the  head  be  thrown  back  and  tlie  tip  of 
the  nose  drawn  ui>.  the  lower  j)art  of  the  septum,  floor  of  the  nose,  and  gre.-iter 


1098 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


Fig.  672.— Sectiux  of  the  Nose,  .showing  the  Tirbixal  Boxes  axd  JIeatuses, 

WITH   the  OPEXIXGS   IX   DOTTED    OUTLIXE. 

Frontal  sinus 
Orifice  of  middle  ethmoidal  cells 

SUPERIOR  TURBINAL  BONE  /      .^.^-<r^\\\ 

Orifice  of  the  posterior  ethmoidal  cells 
Orifice  of  the  sphenoidal  sinus 
inus  \ 

V 


Sphenoidal  ai 


Orifice  of  frontal  sinus 


UPPER  ORIFICE  OF 
NASAL  DUCT 


ORIFICE  OF  EUSTACHIAN 
TUBE 


LOWER  ORIFICE  OF  NASAL  DUCT 
MIDDLE  TURBINAL  BONE 

INFERIOR  TURBINAL  BONE        ORIFICE  OF  THE  ANTRUM        ORIFICE  OF  INFUNDIBULUM 


Fig.  673. — Sectiok  showixg  Boxy  and  Caktilagixous  Septum. 
The  dotted  line  indicates  the  course  of  the  anterior  palatine  canal. 


Frontal  sinus 


Sphenoidal  sinus 


UPPER  LATERAL  CARTILAGE 

Groove  between  septal 
and  upper  lateral 
cartilage 


LOWER  LATERAL  CARTILAGE 


THICKENED  BORDER  OF  CARTILAGE  RESTING  ,  ,-o„nn  nr  „r,r,»,- 

UPON  ANTERIOR  NASAL  SPINE  Incisive  papilla      \  ei^rel^Vxy'^i^men-  I       ORIFICE  OF^E^USTACHIAN 

SEPTAL  CARTILAGE  ^o"'"  c^'^bX  SOFT  PALATE 


THE  XOSI-:  AM)   XFX'K  1091) 

portion  of  the  inferior  tur))inated  Ijonc  can  be  seen.  On  throwing:  the  head  further 
back,  witli  a  good  light  the  lower  margin  of  the  middle  turl)inatcd  bone  can  also  l)e 
made  out.  This  is  much  higlier  uj)  and  nearly  on  a  level  with  the  ro(tt  of  the  nasal 
bone.  The  septum  often  deviates  to  one  side.  The  mucous  membrane  over  it  is, 
in  health,  dull  red  in  colour;  that  over  the  inferior  turbinated  is  thicker.  The 
anterior  extremity  of  the  latter  l)one  is  about  three-cjuarters  of  an  inch  behind  tlie 
orifice,  while  the  opening  of  the  nasal  duct  is  about  one  inch  ))ehiii<l  and  about 
three-quarters  of  an  inch  al)ove  the  fioor.  The  (»pening  into  the  antrum  is  situated 
in  al)out  the  centre  of  the  middle  meatus  and  one  incli  al)ove  the  llo<tr. 

The  j)osterior  nares  should  be  examined  by  the  finger  passed  behind  the  soft 
palate.  Each  oval  aperture  measures,  in  the  adult  skull,  al>out  half  an  inch  trans- 
versely by  one  vertically.  In  life  the  al)ove  dimensions  are  somewhat  less,  owing  to 
the  presence  of  the  mucous  membrane.  The  l)oundaries  of  these  apertures  should 
be  identified,  viz. :  internally,  the  vomer;  externally,  the  internal  pterygoid  ))late 
and  palate  V)one;  above,  tlie  basisphenoid;  and  Ijelow,  the  ])osterior  lionler  of  the 
horizontal  plates  of  the  palate  bones  and  posterior  nasal  spine. 


THE  NECK 

Landmarks  in  the  middle  line. — Passing  from  the  symphysis  to  the  sujtra- 
clavicular  notch  is  the  body  of  the  hyoid,  which  is  nearly  on  a  level  with 
the  angles  of  the  jaw.  On  either  side  of  the  body  are  the  great  cornua.  The  upjjcr 
borders  of  these  are  the  guides  to  the  lingual  arteries.  Below  the  hyoid  is  the  thyro- 
hyoid space,  which  corresponds  with  the  epiglottis  and  the  upper  aperture  of  the 
larynx.  Thus,  if  the  throat  be  cut  aljove  the  hyoid,  the  mouth  will  be  ojtened  and 
the  tongue  cut  into;  if  the  thyro-hyoid  space  be  cut,  the  pharynx  would  be  ojiened 
and  the  epiglottis  wounded  near  its  base.  Behind  the  centre  of  the  anterior  margin 
of  the  thyroid  is  the  rima  glottidis.  The  projection  of  the  thyroid  notcli  is  much 
more  distinct  in  men  than  in  women  or  children.  It  does  not  ai)i)ear  liefore  puberty, 
and  thus  flatness  of  the  thyroid  must  be  expected  when  the  landmarks  for  traehe- 
otomy  are  sought  for  in  children  with  short  fat  necks.  The  cricoid,  on  the  other 
hand,  is  always  to  be  made  out.  It  corresponds  in  horizontal  i>lane  to  the  folknv- 
ing: — (1)  The  fifth  cervical  vertebra.  (2)  The  junction  of  pharynx  and  asopha- 
gus:  from  the  narrowing  of  the  tube  here,  foreign  bodies  may  lodge  at  this  ])oint 
and  cause  dyspnoea  by  pressing  on  the  air-tube  in  front.  The  cricoid  is  taken  as 
the  centre  of  the  incision  in  cesophagotomy,  and  also  for  ligature  of  the  common 
carotid.  (3)  The  junction  of  larynx  and  trachea.  (4)  The  crossing  of  the  omo- 
hyoid over  the  common  carotid.      (5)   The  middle  cervical  ganglion. 

The  distance  between  the  cricoid  and  the  manubrium  is  only  about  an  inch  and 
a  half.  When  the  neck  is  stretched,  about  three-quarters  of  an  inch  more  is  gained. 
Thus,  as  a  rule,  there  are  not  more  than  seven  or  eight  tracheal  rings  al)ove  tlie 
sternum.  Of  these,  the  second,  third,  and  fourth  are  covered  by  the  thyr(»id  ii^th- 
mus.  The  parts  met  with  in  the  middle  line — ('0  above,  and  (/>)  below  the  isth- 
mus— should  be  borne  in  mind:  (a)  Skin,  su]»erficial  fascia,  branches  of  transverse 
cervical  and  infra-mandilndar  nerves,  lym])hatics.  cutaneous  arteries,  anterior  jug- 
ular veins — with  their  transverse  branches  smaller  above. — deep  fascia,  sterno- 
hvoids,  cellular  ti.ssue,  sujierior  thyroid  vessels,  and  tracheal  layer  of  dceit  fascia. 
The  importance  of  this  last  is  two-fold,  as,  first,  the  tuln'  in  tradieotomy  may  be 
passed  between  it  and  the  trachea,  and  after  a  wound  in  this  region  this  layer,  con- 
tinuous with  the  pericardium,  may  conduct  discharges  into  the  mediastina.  (h) 
The  surface  structures  are  much  the  same,  but  the  anterior  jugular  veins  and  their 
transverse  branches  are  much  larger.  The  inferior  thyroid  veins  are  also  larger. 
A  thyroidea  ima  may  be  present,  and  the  innominate  artery,  which  often  cr(».<.<es 
the  trachea  above  the  sterno-davicular  joint,  may  do  so  as  high  as  the  seventli  tra- 
cheal ring.  The  trachea  is  also  smaller,  deeper,  and  less  stea(He<l  by  muscles.  Tiie 
thymus,  too,  in  young  children,  may  prove  a  difficulty.  Thus,  in  cliildren,  the 
high  operation,  incising  thi^  cricoid  and  crico-traciieal  membrane,  if  needful,  is  to 
be  ]irefcrrc(l. 

The  sterno-mastoid  is  the  landmark  for  several  important  operations.     Its 


1100 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


inner  border,  the  thicker  and  l)ctter  marked  of  the  two,  overlaps  the  carotids;  the 
common  carotid  corresi)onding,  as  far  as  tlie  upper  l)order  of  the  thyroid,  with  a 
Hne  drawn  from  the  sterno-clavicular  joint  to  midway  l^etween  the  mastoid  process 
and  the  angle  of  the  jaw.  The  artery  can  be  best  compressed  above  the  level  of  the 
cricoid,  as  here  it  is  less  deeply  covered.  The  transverse  process  of  the  sixth 
cervical  vertebra  is  called  the  carotid  tubercle,  after  Chassaignac,  who  advised  com- 
pression of  the  carotid  at  this  point.  This  process  lies  two  to  three  inches  above 
the  clavicle.  Compression  l)elow  it  will  command  the  vertebral  as  well.  The 
student  should  recall  the  deep   relations  of   the  sterno-mastoid,   which  he  may 

Fig.  674.— Thymus  Glaxd  in  a  Child  at  Bieth. 


Thyro-hyoid  membrane  ' 

THYROID  CARTILAGE  --jLA, 


Sterno-thyroid  muscle 
Crico-thyroid 
membiane 

Crioo-thyroid  muscle 

THYROID  GLAND 

Right  common  cat  olid 

arterti 
RIGHT  PSTT'MO- 
GASTRIC  ,\EBVE 
Right  internal  jiigvlai 
vfin 

Level  of  sternum 

SECTION   OF   CLAVICLE 
SECTION  OF   FIRST  RIB 


SECTION  OF  STERNUM 


,  ,"^-    Thyro-hyoid  muscle 

Lateral  portion  crico- 

/         thyroid  membrane 

IM»!L_-  Omo-hyoid  muscle 
*■     '-^  sterno-mastoid  muscle 


CRICOID  CARTILAGE 
FIRST  RING  OF  TRACHEA 


TRACHEA 

\ Left  suspensory 

,  ligament 

^       LEFT  KECI-RREST 
\  NEK  VE 

(Esophagus 

Left  innominate  vein 
LEFT  LOBE  OF  THYMUS 


Left  internal  manuiiary 
artery 


Pericardium 


SECTION  OF  FIFTH  COSTAL 
CARTILAGE 


ENSIFORM  CARTILAGE 


classify  as  vessels,  nerves,  muscles,  glands,  and  bones;  or,  according  to  their  posi- 
tion, (1)  those  above  the  level  of  the  angle  of  the  jaw;  (2)  those  between  the 
angle  of  the  jaw  and  the  omo-hyoid;   (3)  those  below  the  omo-hyoid. 

Of  the  two  lieads  of  the  sterno-mastoid,  the  sternal  is  the  thicker  and  more 
prominent,  the  clavicular  the  Avider.  A  stal)  through  the  space  (or  interval)  which 
lies  between  the  two  heads  would  wound  the  l)ifurcation  of  the  innominate  on 
the  right  side,  and  the  common  carotid  on  the  left. 

The  position  of  the  anterior  jugular,  curving  outwards  to  pass  beneath  l)oth 
origins  of  the  muscle  a  little  al)ove  tlie  clavicle,  and  the  external  jugular,  crossing 


THE  XECK 


1101 


at  a  varying  level  tlie  outer  l)or(ler  of  the  cLivicular  (iri.LMii.  n\\\>\  lie  reinciiilxTcil  in 
such  operations  as  tenotomy  liere.  These  veins  are  joined  Ity  numerous  transverse 
branches,  and  become  larger  Ijelow. 

The  anterior  jugular  vein,  commencing  in  the  submaxillary  regi(»n,  descends  a  little 
to  one  side  of  the  middle  line.  Just  above  the  clavicle  each  vein  turns  outwards 
and,  })iercing  the  deep  cervical  fascia,  passes  under  the  sterno-mastoid,  and  opens 
into  the  external  jugular  or  subclavian  vein.      It  has  no  valves. 

Behind  the  sterno-clavicular  joint  liis  the  commencement  of  the  innominate 
veins,  the  bifurcation  of  the  innominate  artery  on  the  right,  and  the  eomnifm 
carotid  artery  on  tlie  left;  dee])er  still  lie  the  pleura  and  hmg.  The  occasional 
high  position  of  the  innominate  on  the  trachea  may  be  a  point  of  importance  in 
tracheotomy,  both  at  the  time  of  the  o))eration  and  later  on,  from  the  fatal  facility 
with  which  a  metal  tube,  if  long  retained  after  a  low  tracheotomy,  may  ulcerate 
into  the  vessel. 

Fig.  675. — Axtekior  and  Latkkal  Ckuvual  Mu.scles. 


Stylo-glossus 


Hyo-gl08SU8 

Mylo-hyoid 

Anterior  belly  of 
digastric 

Eaphe  of  mylo- 
hyoid 


Thyro-hyoid 

Inferior  eoustrietor 

Anterior  belly  of  omo- 
hyoid 

Sterno-hyoid 
Steruo-thyroid 


Stylo-hyoid 

Posterior  belly  of  digastric 

Splenius  capitis 

Sterno-mastoid 

Levator  anguli  scapulae 

Scalenus  medius 
Trapezius 

Scalenus  posticus 


Posterior  belly  of 
omo-hyoid 


In  front  of  the  sterno-mastoid  is  the  anterior  triangle,  which  is  subdivided 
into  three  smaller  triangles  by  the  digastric  mu.^cle  above,  and  the  anterior 
bellv  of  the  omo-hyoid  below.  Thi'se  smaller  triangles  are  called,  from  aV)ove.  the 
subiiiaxillarv.  the  superior  and  inferior  carotid  triangles.  The  submaxillary  or 
supra-hyoid  triangle  is  bounded  above  l)y  the  jaw,  and  a  line  drawn  l«ack  t«i  the 
mastoid  process;  below,  by  the  digastric  and  stylo-hyoid  muscles;  and  in  front  by 
the  middle  line  of  the  neck.  This  space  contains  the  submaxillary  gland,  and 
embedded  in  the  gland  is  the  facial  artery;  deeper  than  the  gland  are  tiie  sub- 
mental vessels  and  the  mylo-hyoid  vessels  and  nerve.  Posteriorly,  and  separated 
from  the  above  structures  by  the  stylo-mamlibular  ligament,  is  the  upjier  ))art  of 
the  external  carotid  artery  which  is  embedded  in  the  parotid  glan<l.  where  it  gives 
off  its  two  terminal  and  the  posterior  aurii-ular  liranches.  More  deeply  lie  the 
internal  jugular  vein,  internal  carotid  artery,  and  the  vagus. 


1102  SURGICAL  AND    TOPOGRAPHICAL  A^ATOMY 

The  superior  carotid  triangle  is  Ixjundecl  above  by  the  di^rastiic,  Vjelow  by 
the  omu-hyoi(K  and  behind  l)y  tlie  sterno-niastuid.  It  contains  tlie  upper  part  of 
the  common  carotid  and  its  branches,  the  external  being  somewhat  anterior  to  the 
internal.  All  the  branches  of  the  external  carotid,  save  the  three  just  given,  are 
found  in  this  space,-  together  with  their  veins,  the  internal  jugular  vein,  the  vagus 
and  symi)athetic  nerves,  and,  for  a  short  distance,  the  spinal  accessory,  together 
with  those  nerves  which  lie  in  front  of  and  behind  the  carotids. 

The  inferior  carotid  or  tracheal  triangle  is  bounded  above  by  the  omo-hyoid, 
behind  by  the  sterno-mastoid,  and  in  front  ])y  the  middle  line  of  the  neck.  It 
contains  the  lower  part  of  the  carotid  sheath  and  its  contents,  with,  behind  it,  the 
inferior  laryngeal  nerve  and  inferior  thyroid  vessels,  and  to  the  inner  side  the 
trachea  and  thyroid  gland. 

The  position  of  the  branches  of  the  external  carotid  should  be  remembered. 
The  superior  thyroid,  arising  just  below  the  level  of  the  great  cornu  of  the  hyoid 
bone,  passes  downwards  and  forwards  to  the  back  part  of  the  thyroid  cartilage  and 
upper  part  of  the  thyroid  body.  Many  of  its  branches  are  important  in  surgery. 
The  superior  laryngeal  perforates  the  thyro-hyoid  membrane.  The  sterno- 
mastoid  passes  outwards  into  the  middle  of  the  muscle,  across  the  carotid  sheath. 
The  crico-thyroid  crosses  the  space  of  the  same  name  just  below  the  lower  border 
of  the  thyroid  cartilage.  The  little  hyoid  branch  runs  to  the  lower  border  of  the 
hyoid  bone.  The  lingual  artery  arises  from  the  j^arent  trunk,  opposite  the  tip  of 
the  great  cornu  of  the  hyoid,  and  passes  forwards  just  al)0ve  the  great  cornu,  and 
thence  to  the  side  of  the  tongue.  In  the  first  part  of  its  course,  before  it  reaches 
the  hyo-glossus,  it  is  curved,  at  first  ascending,  and  then,  having  ascended  slightly, 
before  it  reaches  the  hyo-glossus,  and  wdiile  it  lies  under  it,  its  curve  is  gentle,  with 
the  concavity  upwards;  beyond  the  hyo-glossus,  as  it  lies  on  the  muscles  of  the 
tongue  beneath  the  mucous  membrane,  it  is  tortuous.  The  lingual  vein,  it  Avill  be 
remembered,  does  not  run  with  its  artery,  but  lies  superficial  to  the  hyo-glossus.  It 
receives  the  two  small  venae  comites,  which  run  with  the  lingual  itself  just  before 
it  crosses  the  common  carotid.  The  line  of  the  facial  artery  (fig.  6b7),  which 
often  arises  with  the  lingual,  has  been  given  on  page  1091.  The  occipital  artery  (fig. 
667),  starting  on  the  same  level  as  the  facial  (i.e.  a  point  a  little  above  and  outside 
the  tip  of  the  great  cornu  of  the  hyoid  bone),  follows  a  line  drawn  upwards  and 
outwards,  first  to  the  interval  between  the  transverse  process  of  the  atlas  and  the 
mastoid  process,  the  former  bone  being  felt  just  below  and  in  front  of  the  tip  of  the 
latter;  thence,  lying  in  the  occipital  groove  of  the  mastoid,  the  artery  ascends 
gradually,  enters  the  scalp,  together  with  tlie  great  occijiital  nerve,  at  a  point 
about  midway  between  the  external  occipital  prominence  and  the  mastoid  process, 
to  follow,  tortuously  and  superficial  to  the  aponeurosis,  the  line  of  the  lamlidoid 
suture  (p.  1088). 

The  surface-marking  of  the  digastric  and  omo-hyoid,  which  subdivide  the 
anterior  triangle  into  the  three  smaller  sul^triangks  aliove  descril^ed,  should  be 
noted.  The  line  of  the  posterior  belly  of  the  digastric  corresponds  to  one 
drawn  from  the  apex  of  the  mastoid  |)rocess  to  a  j^oint  just  above  the  junction  of 
the  great  cornu  and  body  of  the  hyoid  bone;  and  from  this  spot,  Avhich  gives  the 
point  of  meeting  of  the  two  tendons,  one  slightly  curving  upwards  to  a  point  just 
behind  the  symphysis  menti,  would  give  that  of  the  anterior  belly. 

To  trace  the  omo-hyoid,  a  line  should  be  drawn  from  the  lower  margin  of 
the  side  of  the  hyoid  bone  ol)li(iuely  downwards,  so  as  to  cross  the  common 
carotid  oi)posite  the  cricoid  cartilage,  and  thence  curving  outwards  under  the 
sterno-mastoid  at  the  junction  of  its  middle  and  lower  thirds,  and  then  on- 
wards and  still  outwards,  parallel  with  and  a  little  above  the  clavicle,  as  far  as 
its  centre. 

Posterior  triangle. — This  shows  in  its- lower  part  a  wide  depression,  the  supra- 
clavicular fossa.  Here  the  brachial  plexus  may  be  felt,  and,  by  pressure  down- 
wards and  backwards,  just  outside  the  outer  margin  of  the  sterno-mastoid,  the 
pulsation  of  the  subclavian  artery  can  be  stopped  against  the  first  rib.  This  vessel 
curves  upwards  and  outwards  from  lieliind  the  sterno-clavicular  joint  to  disapi)ear 
behind  the  centre  of  the  clavicle,  the  highest  i)oint  of  the  curve  l)eing  half  an  inch 
to  an  inch  above  the  bone.     The  artery  on  the  left  side  lies  more  deeply  than  the 


THE  XFJK 


llOli 


right,  and  doos  not  rise  so  high  into  the  iwck.  The  sulxhivian  vein  hcs  ut  a  luwcr 
level  and  under  lover  of  the  elaviele.     Into  tiie  ahove  curve  rise  the  jileura  and  lung. 

The  suprascapular  and  transverse  cervical  vessels  run  outwards,  jiarallel 
with  the  clavicle.  The  former  lies  behind  the  bone  and  sidx  lavius;  the  hitter  alsn 
runs  transversely  outwards,  across  the  root  of  the  neck,  but  on  a  slightly  higher 
plane,  and  thus  a  little  above  the  clavicle. 

Crossing  the  sterno-mastoid  a  little  obli(juely,  in  a  line  drawn  from  the  angle 
of  the  jaw  to  the  centre  of  the  elaviele,  runs  the  external  jugular  vein.  About 
an  inch  and  a  half  aliove  the  clavicle  it  perforates  the  deej)  cervical  fascia,  its  coats 
l)eing  blended  with  the  opening.  The  dilated  ])art  between  this  pf)int  and  the 
subclavian  vein  is  called  the  sinus,  and  is  marked  by  two  valves,  neither  of  which 
is  usually  perfect.  Just  above  the  clavicle  the  })()sterior  and  sui)rascai)ular,  trans- 
verse cervical,  and  a  branch  from  the  eei)halic  veins,  form  a  plexus  over  the  third 
part  of  the  subclavian. 

Opening  into  the  external  jugular,  in  the  middle  or  lower  third  of  its  course,  is 


Fig.  676. — Keoiux  ok  the  TiiiRr*  P.vkt  ok  thic  Sibci..\.vian  Artery. 
(The  shoulder  represented  depressed.) 


(Bellamy.] 


Spleuius 

Levator  anguU  scapulae 

Scalenus  posticus 

A      SrPKRF/CIA  L      DE- 
SCEXD/XO       BRAXCH 
OF      THE      CERVICAL 
PLEXUS 
BRA  CI/Ll  L   PLEXUS 
Tiansvcr.salis  colli  artery 
(life),) 
First  serration  of  serratus 
magnus 


PIIREXIC  XERVE 
Scalenus  amicus 


..     oorration  of  serratus  magnus 
^   lit /lit  km   it;iii 
Sii/iriiscapulai   artery 
Snhclavian  artery 


Suprascnptilar  rein 
Coito-coracoid  membrane  and  rr/i/inlic  rein 


the  posterior  external  jugular,  a  vessel  which  l»egins  in  the  occipital  region 
superficially  and  runs  down  in  front  of  the  anterior  Itorder  of  the  tra}>ezius,  acro.ss 
the  ))osterior  triangle. 

The  spinal  accessory  enters  the  anterior  Itorder  of  the  sterno-mastoi<l  from 
one  to  one  and  a  half  inches  l)elow  the  a]>ex  of  tlie  mastoitl.  along  a  line  drawn 
downwards  and  outwards  from  the  angle  of  the  jaw.  Having  traversed  the  muscle 
obliciuely,  it  pursues  a  similar  course  acro.ss  the  posteri(»r  triangle,  disaitjtears  on  a 
level  with  the  sixth  or  seventh  cervical  spine  beneath  the  trapezius,  and  descends 
under  this  mu.«;cle  internal  to  the  vertebral  border  of  the  scapula  ((^odlee).  Just 
above  the  centre  of  the  sterno-mastoid,  the  small  occipital,  great  auricular,  and 
transverse  cervical  nerves  emerge,  the  first  passing  upwards  and  backwards  to 
the  scalp,  the  second  Upwards  and  forwards  across  the  upper  jxirt  of  the  sterno- 
mastoid  to  the  ear.  and  the  last  turning  straight  forwards  to  the  front  of  the  neck. 

The  phrenic  nerve,  taking  its  largest  root  fntm  the  fourtli  cervical,  would 
begin  deeply  about  the  level  of  the  hyoid  l)one;  thence  descending  under  the  sterno- 


1104 


SURGICAL  AXD    TOPOGRAPHICAL  ANATOMY 


mastoid,  and  passing  obliquely  inwards  across  the  scalenus  anticus  (the  posterior 
borders  of  the  above  two  muscles  roughly  correspond  to  each  other  in  the  lower 


Fig.  677.— The  Collaterai,  Circllatiox   after  Ligature  of  the  Commox  Carotid  and 

SuBCLAYiAX  Arteries. 

(A  ligature  is  placed  on  the  commou  carotid  aud  on  the  third  portion  of  the 
subclavian  artery.' 


Biffht  anterior  cerebral 

Internal   carotid 
Right  posterior  cerebral 


Occipital 
Princeps  cervicis 

External  carotid 

Superficial  branch  of  princeps  cervicis 
Deep  branch 

Ascending  cervical 


Transverse  cervical 

Posterior  scapular 

Acromial  branch 

Subscapular  branch 

Supraspinous 

branch 

Anterior  circumflex 

Infraspinous 

branch 

Posterior  cirtumfler 

Long  thoracic 

Subscapular 

Dorsal  scapulai 

Infrascapular 

Subscapului 


Superior  thyroid 


Left  anterior  cerebral 
Anterior  communicating 


Posterior  conununicaling 
Left  posterior  cerebral 

Basilar 


Anterior  spinal 


Inferior  thyroid 
Common  carotid 


Thyroid  axis 
Superior  intercostal 


Innominate 
Superior  intercostal 
Left  common  carotid 
Left  subclavian 
Short  thoracic 
Internal  mammary 


Anterior  intercostal 

First  aortic  inter- 
costal 

Second  aortic  inter- 
costal 


Anterior  intercostal 


Third  aortic  inter- 
costal 


part  of  the  neck),  it  descends  under  the  subclavian  vein  and  clavicle  to  enter  the 
thorax. 

The  level  of  the  brachial  plexus  (upper  border)  would  be  given   l)y  a  Jine 


THE  XECK 


11  Go 


drawn  from  the  cricoid  cartila^^es  to  tlio  centre  of  tlie  clavicl*-.  The  lowest  c(»rd 
(eighth  cervical)  is  just  ahovf  and  Ix'liind  th<'  sul»clavian  artt-rv. 

Collateral  circulation  after  ligature  of  the  common  carotid  (tig.  677). — 
This  takes  place  hy  means  (jf  (1)  tiie  free  connnunication  wiiich  exists  ])etween  tlici 
opposite  carotids,  both  witliout  and  within  the  cranivnn;  and  (2)  hv  cnlargenn-nt 
of  the  branches  of  the  subclavian  artery  on  the  same  side  as  that  on  which  the 
carotid  has  been  tied.  Thus,  outside  the  cranium,  the  su])erif>r  an<l  inferior 
tliyroids  are  the  chief  vessels  employed  (fig.  <>77).  Witliin  the  cranium  the 
vertebral  n-placcs  the  internal  enrotid. 

Collateral  circulation  after  ligature  of  the  second  and  third  parts  of  the 
subclavian  (tig.  677  j. — Here  the  following  three  sets  of  vessels  are  tho.se  chiefly 
employed: 

The   suprascapular,  the  posterior)  .,,         (The   acromio-th..racic.  infra-  aii.l 

-  ^         '  ^  "-        witli        -       subscapular,  and  dorsalis  scap- 

/       uhe. 


scapular, 


The  superior  intercostal,  the  aortic ') 
intercostals,  and  the  internal  - 
mammarv,  ) 


with 


f  Tlie  long  thoracic   and   scapular 
[      arteries. 


Numerous  unnamed  branches") 
passing  through  the  axilla  from  - 
branches  of  the  subclavian,         ) 


with 


Branches  of  the  axillarv. 


Deep  cervical  fascia. — The  arrangement  of  this  mu.st  be  remembered — {a) 
above,  and  {U)  l)elow.  the  hyoid  bone.     The  latter  is  far  the  more  important. 

(a)  Arrangement  above  the  hyoid  bone. — Here  two  chief  layers,  .superficial 

Fig.  r>78. — Di.\geam  of  the  Layers  of  the  Deep  Cervical  Fascia  ik  a.\  A.nteho- 
posTERioR  Section  opposite  to  the  Sternum.     (Tillaux.) 

^The  prevertebral  layer  can  be  seen  passing  down  in  front  of"  the  longiis  c-olli.) 


\  Superficial  layer  of  superficial 
faacia 


Sterno-clavicular  layer 

Reduplication  of  this  layer  pass- 
ing behind  the  sterno-thyrold. 
Tracheal  layer  separated  from 
the  trachea,  and  encloslDK  the 
left  innominate  vein,  and  be- 
coming continuous  with  the 
pericardium 

Space  occupied  by  aterno-byoid 


lyft  innominalf  irin 
—  Innominata 


Pericardium 


and  deep,  can  he  made  out: — (i)  The  superficial,  traced  ujiwards  from  the  hyoid 
bone,  encloi^es  the  submaxillary  gland,  jiassing  over  the  mylo-hyoid,  and.  a.^cending. 
gives  off  the  masseteric  and  parotid  fa.><cia-,  and  is  attached  to  the  lower  border  of 
the  zygoma,  fii)  The  deeper  layer,  which  forms  the  stylo-mandibular  ligament, 
is  important  in  its  i^wer  of  checking  over-action  of  the  external  jiterygoid.  (/<) 
Below  the  hyoid  bone. — The  imi»ortance  of  the  fascia  here  is  infinitely  greater. 
70 


1106 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


Four  layers  must  be  remembered:  (i)  Superficial,  or  subcutaneous ;  (ii) 
sterno-clavicular ;  (iii)  tracheal;  (iv)  prevertebral.  These  should  first  be 
traced  horizontally,  (i)  Superficial,  or  subcutaneous.  This  starts  from  the 
ligamentum  nucha?,  encases  the  trapezius,  forms  the  roof  of  the  posterior  triangle, 
where  it  is  perforated  by  branches  of  the  superficial  cervical  nerves  and  the  external 
jugular  vein.  Passing  on,  it  encloses  the  sterno-mastoid;  and,  passing  over  the 
anterior  triangle,  it  meets  its  fellow  in  the  middle  line.  Thin  behind,  it  is  thickened 
anteriorly,  where  it  is  united  to  the  next  layer.  Behind  this  thickened  union  lie 
the  anterior  jugular  veins,  (ii)  Sterno-clavicular.  This  is  best  marked  below. 
In  the  middle  line  it  meets  its  fellow,  and  blends  with  No.  i.  here  also.  Passing 
outwards,  it  encases  the  depressors  of  the  hyoid  bone,  finall}-  blending  with  No.  i. 
at  the  posterior  border  of  the  sterno-mastoid.  (iii)  Tracheal.  This  lies  under  the 
depressors  of  the  hyoid,  over  the  trachea,  also  encasing  the  thyroid  gland.  Farther 
out,  it  forms  the  carotid  sheath,  and,  blending  with  No.  iv.  over  the  anterior  scalene, 
is  thus  brought  into  continuity  with  Nos.  i.  and  ii.  also,  (iv)  Prevertebral.  This 
layer  passes  over  the  longus  colli  and  rectus  capitis  anticus  major. 

The  above  layers  should  also  be  traced  vertically,  with  especial   reference  to 


Fig.  679. — Diagram  of  the  Arrangement  of  the  Deep  Cervical  Fascia,  the 
Section  passing  through  the  Clavicle.     (TilUiux.) 


Sterno-clavicular  layer  of  deep 
oervical  fascia 


Subclaiian  artery ^^^sft] 

Vein 

Subclavius  — 


Superficial  layer 


Omo-hyoid 


their  relations  at  the  level  of  the  top  of  the  sternum  and  the  clavicle,  (a)  At  the 
level  of  the  top  of  the  sternum,  (i)  Superficial,  passes  over  the  sternum, 
(ii)  Sterno-clavicular  ;  this,  descending  in  front  of  the  depressor  muscles,  divides 
just  below  the  thyroid  cartilage  into  two  layers,  which  are  attached  to  the  front  and 
back  of  the  sternum.  Between  these  lie  some  fat  and  a  small  gland,  (iii)  Tra- 
cheal ;  this  passes  down  over  the  trachea  into  the  thorax  (middle  mediastinum). 
As  it  descends,  it  encases  the  left  innominate  vein,  and  ends  by  blending  with  the 
fibrous  layer  of  the  pericardium.  Mr.  Hilton  suggested  that  the  attachment  of  this 
fascia  above,  and  that  of  the  central  tendon  of  the  diaphragm  below,  to  the  peri- 
cardium served  to  keep  this  sac  duly  stretched,  and  so  prevented  any  pressure  of 
the  lungs  upon  the  heart,  (iv)  Prevertebral;  this,  descending  luOiindthe  oesoph- 
agus, dips  into  the  posterior  mediastinum.  (/S)  At  the  level  of  the  clavicle. 
Only  two  of  the  above  layers  are  met  Avith  so  far  outwards  as  tliis — (i)  Subcuta- 
neous, which  passes  over  the  clavicle;  (ii)  sterno-clavicular,  which,  liaving 
encased  the  omo-hyoid,  ])asses  behind  the  clavicle,  blends  with  the  sheath  of  the 
subclavius,  and  gives  a  sheath  to  the  subclavian  vein.  That  to  the  artery  is  derived 
from  No.  iii.  at  the  scalenus  anticus. 


rilE  SFJ'K 


11(1/ 


The  following  uses  ami  important  points  with  ivpinl  to  the  anatomy  nf  tin- 
deep  cervical  fascia  sliould  be  noted:  (Aj  It  forms  certain  definitely  enclosed 
spaces  in  which  pus  or  growths  may  form,  and  Ijy  tht-  walls  of  whicli  tlicse 
morbid  structures  may  be  tied  down  and  tlius  rendered  difficult  of  diagnosis,  wliile 
their  increasing  pressure  may  embarrass  the  air-passages,  etc.  Thus:  (1)  Jn  the 
first  si)ace,  which  hes  between  No.  1  and  the  skin,  the  structures  met  with,  the 
platysma  and  superficial  branches  of  the  cervical  jilexus,  are  unimportant.  Any 
abscess  here  is  pnjne  to  extend,  but  suj)erlicially.  ('1)  In  the  second  sj)ace, 
between  the  superficial  and  stcrno-clavicular  layers,  lies  a  narrow  space  containing 
loose  cellular  tissue  and  lymphatic  glands.  Sujtpuration  here  is  very  conuuon,  but 
usually  comes  forwards.  (8)  This  is  the  largest  and  most  important  of  all.  It  is 
bounded  in  front  by  the  sterno-clavicular,  and  behind  V)y  the  prevertebral  layer. 
Its  contents  are — larynx,  trachea,  a?sophagus,  thyroid,  carotid  sheath,  glands;  and 
))elow,  brachial  plexus,  subclavian  artery,  and  al)undant  loose  cellular  tissue  for 

Fig.  680. — Sectiox  of  Neck  thkough  the  Sixth  Ckevical  Yeeteuk.v.     (One-half.) 

(Braune.) 

RE<  l  RREST  LA  R  YXGAA  L  SER  VE 

PHARrNX  I  URYNX 

Thyro-arytenoid  muscle 

CRICOID  CARTILAGE  'and  omo-hyoid  muscles 

Bterno-hyoid  Just  posterior  are  been  the  thyro- 
Crico-arytenoideud  lateralis 

Muscular  process  of  ibe  thyroid  cartilage 


LonguB  colli  muscle  , 
Sii/jfriDr  thi/roiil  artery] 
-     DE^SCESDEXS  SUNl       ' 
VAGUS 
PIIREXIC  XER  VE 


Scalenus  anticus 
Sterno-oleido-mastoid 


B  RA '  nJA  L  PL  EX  I  '.S' 


Scalenus  mediua 

Ezterniil  jugular  leiit 


.SPIX.  I L  A  rcESSOR  1 
XER\'E 


Splenlua 

PART  OF  ARTICULAR  SURFACE  OF  SEVENTH  CERVICAL  VERTEBRA 

Beml-spiaalis  and  multifldus 

SIXTH  CERVICAL  VERTEBRA 


THYROID  GUND 

Common  carotid  artery 
Internal  Jiiffular  vein 

liliAflllAL    PLEXrs 
Scalenus  medius 
External  jni/nlai-  r^in 
Scalenus  posticus 

SPIXA  L  A  rCESStjR  Y 
XERVE 


Levator  anguli  scapulae 


Cervicalis  ascendens 


t  Transversalis  cervlcis  and  trachelo- 

Pro/iinda  cervicis  rtsetlt  mastoid 

Trapezius 


Biventer  cervicis  and  complexus 


the  movements  of  the  neck.  Su))))uration  is  somewhat  rarer  here:  but  either  jius 
or  growths,  if  confined  in  this  space,  may  have  banrful  efftcts.  from  )»nss\ire,  or 
from  their  tendency  to  travel  behind  the  "sternum.  (4)  This  si)acc.  between  the 
prevertebral  layer  in  front  and  muscles  behind,  is  very  limittMl.  Ketrojiharyngeal 
abscess  forms  here,  and  the  dysjuKea  it  causes  is  thus  explained.  (H)  The  deep 
cervical  fascia  gives  sheaths  or  canals  to  certain  veins  which  perforate  it.  e.g. 
the  external  jugular.  These  are  thus  kept  patent,  and  a  ready  ])assage  of  blood 
ensured  from  the  head  and  neck.  The  carotid  sheath  is  another  and  different 
instance.  (C)  It  helps  to  resist  atmospheric  pressure.  (D)  Mr.  Hilton's 
suggestion  as  to  its  action  on  the  pericardium  has  already  l)een  mentioned. 

T^efoiv  lenviiii:  this  region,  the  arrangement  of  the  lymphatic  glands  of 
the  head  and  neck  must  be  attended  t«>.  'i'hey  are  extnuielv  iininerniis.  and  are 
chietlv  arranged  in  the  following  .^ets:  (  1  i  Occipital,  or  suboccipital,  along  the 
attachment  of  the  occipitalis.  (2)  Tlie  posterior  auricular,  over  tlie  insertion 
of   the   stemo-mastoid.      (3)  The    parotid,  just    in    front-  of   the  ear,   partly  on 


1108  SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 

and  partly  in  the  substance  of  the  parotid  gland.  (4)  The  submaxillary,  under 
the  cervical  fascia,  in  the  digastric  triangle.  This  very  ini])ortant  group  receives 
lymph  from  the  lower  part  of  the  face,  lips,  front  of  tongue,  floor  of  mouth,  and 
all  the  salivary  glands.  Tliey  drain  into  the  superficial  and  deep  cervical  glands. 
(o)  Superficial  cervical  glands.  These  lie  along  the  external  jugular,  between  the 
platysma  and  deep  fascia.  They  receive  lymphatics  from  the  occipital,  posterior 
auricular  glands,  the  ear,  and  upper  neck,  and  also  some  of  those  from  the  parotid 
and  sulmiaxillary  regions.  They  drain  partly  into  the  deep  cervical,  partly  into  the 
axillary  glands.  (6)  Deep  cervical.  These  consist  of  two  sets, — upper  and  lower, 
— lying  along  the  carotid  sheath.  They  receive  lymph  from  the  superficial  cervical 
and  submaxillary  glands,  the  inside  of  the  cranium,  and  pterygoid  region,  deep 
muscles  of  neck,  palate,  tonsils,  larynx,  pharynx,  thyroid  body,  and  upper  part  of 
trachea  and  oesophagus.  The  deep  cervical  glands  empty  into  each  other  and  below 
into  the  mediastinal  and  axillary  lymphatics,  the  right  lymphatic  duct,  and  thoracic 
duct.  Two  other  groups  of  glands — the  one  superficial,  the  other  deep — must  be 
remembered.  (7)  The  suprahyoid  group  is  a  term  given  to  a  few  glands 
situated  in  the  middle  line  under  the  deep  fascia  below  the  chin.  (8)  Retro- 
pharyngeal glands.  These  lie  between  the  up])er  part  of  the  ])harynx  and  the 
rectus  capitis  anticus  major.  They  receive  lymph  from  the  naso-phar3'nx  and  drain 
into  the  deep  cervical  glands. 


SUPERFICIAL  ANAT03IY  OF  THE  THORAX 

Bony  points. — The  top  of  the  sternum  corresponds  (in  inspiration)  to  the 
fibro-cartilage  between  the  second  and  third  thoracic  vertebra^,  and  is  distant  aljout 
two  and  a  half  inches  from  the  spine.  If  traced  downwards,  the  sul^cutaneous 
sternum  presents  a  ridge  opposite  to  the  junction  of  the  manubrium  and  body,  and 
the  second  costal  cartilages  on  either  side.  At  its  lower  extremity  the  xiphoid  carti- 
lage usually  retires  from  the  surface,  presenting  the  depression  of  the  scrobiculus 
cordis,  or  '  pit  of  the  stomach. '  This  is  opposite  to  the  seventh  costal  cartilages 
and  the  expanded  upper  end  of  the  recti,  and  corresponds  to  the  ninth  thoracic 
verteljra  1  behind. 

Sterno-clavicular  joint. — The  expanded  end  of  the  clavicle  and  the  lack  of 
])roportion  between  this  and  the  sternal  facet,  on  which  largely  depends  the 
moliility  of  this,  the  only  joint  that  ties  the  ujiper  extremity  closely  to  the  trunk, 
can  be  easily  made  out  through  the  skin.  Behind  the  joint  lie,  on  the  right  side, 
the  innominate  artery,  right  innominate  vein,  and  pleura;  on  the  left,  the  left 
innominate  vein,  the  left  carotid,  and  the  pleura. 

Acromio-clavicular  joint. — On  tracing  the  clavicle  outwards,  it  is  found  to 
rise  somewhat  to  its  articulation  with  the  acromion.  This  joint  has  very  little 
mobility,  and  owes  its  protection  to  the  strong  conoid  and  trapezoid  ligaments  hard 
by.  Owing  to  the  way  in  which  the  joint-surfaces  are  bevelled,  that  of  the  clavicle 
looks  ol)li(iuely  downwards,  and  it  is  an  upward  disi)lacement  of  the  clavicle  which 
usually  takes  place  on  to  the  acromion. 

Ribs. — In  counting  these,  the  position  of  the  second  is  denoted  by  the  trans- 
verse line  at  the  junction  of  the  manubrium  and  body  of  the  sternum.  The  nipple, 
in  the  male,  lies  between  the  fourth  and  fifth,  nearly  an  inch  outside  their  cartilages. 
The  lower  border  of  the  great  pectoral  corresponds  to  the  fifth  rib.  The  seventh, 
the  longest  of  the  ribs,  is  the  last  to  articulate  with  the  sternum.  AMien  the  arm 
is  raised,  the  first  three  digitations  seen  of  the  serratus  magnus  correspond  to  the 
fifth,  sixth,  and  seventh  rihs.  The  ninth  rib  is  the  most  ol)li(jue.  The  eleventh 
and  twelfth  can  l)e  felt  outside  the  erector  s|)in{e.  Owing  to  the  ol)li(iuity  of  the 
ribs,  their  sternal  ends  are  on  a  much  lower  level  than  their  vertebral  extremities. 
'Thus  the  first  rib  in  front  corresponds  to  the  fourth  rib  behind,  the  second  to  the 


THE  THORAX 


1109 


sixth,  the  third  to  the  seventh,  tin-  f.,urth  to  th.-  ci-hth,  th.-  tifth  t.,  thi'  ninth  th.> 
sixth  to  the  tenth  and  the  seventh  to  the  eleventh.  If  a  Imrizuntal  line  h,-  drawn 
round  the  hodv  from  heiore  haekwards,  at  th.-  level  <,f  the  inferi.,r  ande  of  the 
seapula,  win  e  the  arms  arc  at  the  sides,  the  line  would  eut  the  sternum  in  fmnt 
between  the  fourth  and  fifth  rihs,  the  fifth  rib  at  the  nij,],!.-  line,  and  the  ninth  ril. 
at  the  vertebral  column'  (Treves).  Those  most  fre.juentlv  broken  are  the  nxth 
seventh,  and  eighth.     The  way  in  which  the  ribs  are  en.r.e.Me.l  in  the  >^oft  i)art>^' 


Fig.  681. 


RIGHT  UECrR. 

JiE.VT  LARyy- 

tiKAL  .VERVE 

TYaiisieise  cervical 

artery 

Rlyhl  common  carotid 

artery 
Suprascapular  artery 

Internal  jugular  vein 

PNEUifOGA  STRIC 
XER  VE 
Subclavian  vein 

Inferior  thyroid  vein 

PHRENIC  NERVE 

Left  innominate  vein 

Ascending  aorta 

Superior  vena  cava 
RIGHT  BRONCHUS 

Branch  to  superior  lol» 

of  lung 

Upper  branch  of  right 

pulmonary  artery 

Branch  to  miildle  hth' 

of  lung 
Right  pulmonary  i 

RIGHT  AURICLE 

Right  coronary  artery 
Lotnr  hranch  of  right 
liiitniunari/  arlen/ 
THORACIC  VERTEBRA 

Intercostal  vein 
Intercostal  artery 
Vena  azygos  major 

Intercostal  vein 
Intercostal  artery 

Intercostal  vein 
Intercostal  artery 


-The 
( From 


Akch  of  the  Aokta,  with  the  Pulmoxakv  Aktekv  and 
Chief  Buaxches  of  the  Aokta. 

a  dissection  in  St.  Bartholoiiu-w'.s  HospiUil  Sluseuin.  i 


THYROID  BODY 
LEFTRECVRRI:.\  I 
LARYSflEAl. 
NERVE 
I'NEl  MttfiASTRV ' 

NER  VE 
Lrjt  intentitt  jugutat 

vin 
I^ejt  cofnviou  carotid 

arlrri/ 
I^/t  subclat-iun  artery 

I^/l  mbclarinn  vein 

TRACHEA 

Inferior  thyroid  vein 

PHRENIC  NERVE 

(hookeil  aside) 
RECVRRENT 
LARYNUEM. 
NER  VE 
PNELMOGA  S  TRIi ' 

NERVE 
DUCTUS  ARTERIOSUS 

Left  pulmonary  artery 


^    Pulmonary  artery 


Right  putmotiary 
arl'-rg 

LEFT  BRONCHUS 

I^fl  coronary  artery 

I'pper  left  pulmonary 

vein 
RIGHT  VENTRICLE 

( Von  us  arleriuntit  i 
lAtwer  t^t  puliiiuniiry 

artery 
Ixtwer  left  pulmonary 

rein 
(ESOPHAGUS 
(hooked  aside) 


THORACIC  OUCT 
Thoracic  aorta 


and  the  fact  that  the  frafnnents  are  often  held  in  jilace  by  the  fteriosteum.  accounts 
for  the  ditliculty  which  is  often  met  with  in  detecting  Crepitus.  The  intercostal 
spaces  are  wider  in  front  than  behind.      The  three  upper  are  the  wide.<t  of  all. 

Structures  passing  through  the  upper  aperture  of  the  thorax.— If  a 
horizontal  section  is  made  jtassinir  throUirh  the  manul)rium  stenii.  upper  border  of 
the  first  rib.  and  upper  part  '>f  the  fii-st  thoracic  vertebra,  the  followinir  structures 
are  met  with: — (1)  In  the  middle  line.  Sterno-hyoid  an<l  .«terno-thyroid 
muscles,  with  their  sheaths  of  deep  cervical  fascia,  cellular  ti.s.sue  in  which  are  the 


1110 


SURGICAL  AND   TOPOGRAPHICAL  AX  ATOMY 


remains  of  the  thymus  gland,  the  inferior  thyroid  veins,  the  trachea  and  tracheal 
fascia,  the  oesopliagus  and  longus  colh  muscles,  l^etween  the  trachea  and 
(Bsophagus  are  the  recurrent  laryngeal  nerves.  (2)  On  each  side.  The  apex  of 
the  lung,  covered  by  pleura,  rises  about  an  inch  and  a  half  above  the  first  rib. 
Between  it  and  the  trachea  and  oesophagus  lie  the  following:  the  internal  mannnary 
artery,  the  phrenic  nerve;  on  the  right  side,  the  innominate  vein  and  artery,  with 
the  vagus  between  the  two,  the  cardiac  nerves,  and  the  right  lymphatic  duct.  On 
the  left  side  are  the  common  carotid  and  subclavian  arteries,  Avith  the  left  vagus 
between  them,  the  cardiac  nerves,  and  the  thoracic  duct.  Farthest  l)ack  and  on 
each  side  are  the  trunk  of  the  sympathetic,  the  superior  intercostal  artery,  and  the 
tirst  tlioracic  nerve. 

Structures  found  in  an  intercostal  space. — (1)  Skin;  (2)  superficial  fascia, 
with  cutaneous  vessels  and  nerves;  (3)  deep  fascia;  (4)  external  intercostal;  (5) 
cellular  interval  between  intercostals,  containing  trunks  of  intercostal  vessels  and 
nerves;  (6)  internal  intercostals;  (7)  thin  layer  of  fascia;  (8)  subpleural 
connective  tissue;   (9)  pleura  (fig.  682). 

The  mamma. — This  lies  partly  over  the  sheath  of  the  pectoralis  major  and 
partly  over  the  serratus  magnus.  It  is  usually  described  as  reaching  from  the  third 
to  the  fifth  or  sixth  rib,  and  from  the  sternum  to  the  anterior  border  of  the  axilla. 
It  is  most  important  to  remember  that  the  breast  is  often  a  much  more  extensive 
structure  than  would  be  included  in  the  above  very  limited  description.  Thus  ( 1 )  the 
breast  is  not  encapsuled  at  its  periphery,  its  tissue  branching  and  breaking  up  here 


Fjg.  682. 


-Section  of  the  Sixth  Left  Intercostal  Space,  at  the  Junction  of 
THE  Anterior  and  PosT^:RIOR  Tfiirds.     (Tillanx.) 


Intercostal  vein 

Intercostal  artery 

INTERCOSTAL  NERVE    — 

Serratus  magnus  — 

Its  aponeurosis  — 

Aponeurosis  covering  external  — 

intercostal  muscle 

External  intercostal  muscle 


_  Aponeurosis  covering  the  internal 
intercostal  muscle 
Internal  intercostal  muscle 


to  l)ecome  continuous  with  the  superficial  fascia  (Stiles).  (2)  The  ligamenta 
suspensoria  contain  breast  tissue.  (3)  There  is  a  lymphatic  plexus,  and,  often, 
minute  lobules  of  breast  tissue,  in  the  pectoral  fascia  (Heidenhain).  In  the  male 
the  nipple  is  placed  in  the  fourth  space,  nearly  an  inch  outside  the  cartilages  of 
the  fourth  and  fifth  ribs.  On  the  nipple  itself  open  the  fifteen  or  twenty  ducts 
which  dilate  beneath  it,  and  then  diverge  and  break  up  for  the  supply  of  the 
lobules.  The  skin  over  the  aieola  is  very  adherent,  pigmented,  and  fatless.  Here 
also  are  groups  of  little  swellings  corresponding  to  some  tAventy  large  sebaceous 
follicles.  The  skin  over  the  breast  is  freely  movable,  and  united  to  the  fascia 
which  encases  the  organ,  and  thus  to  the  interlobular  connective  tissue,  by  bands 
of  the  same  structure — the  ligamenta  suspensoria.  Under  the  l)reast,  and  giving  it 
its  mobilit}^  is  a  cellulo-fatty  layer,  the  seat  of  sulnnammary  abscess.  The  nerves 
which  supply  the  breast  are  the  anterior  cutaneous  branches  of  the  second,  third, 
f(jurth,  and  fifth  intercostal  nerves,  and  the  lateral  l>ranches  of  the  last  three.  The 
connection  of  these  trunks  serves  to'  explain  the  diffusion  of  the  pain  often  observed 
in  painful  affections  of  the  breast.  Thus  pain  may  be  referred  to  the  side  of  the 
chest  and  l)ack  (along  the  above  intercostal  trunks),  over  the  scapula,  along  the 
inner  side  of  the  arm  (along  the  intercosto-humeral  nerve,  a  branch  of  the  second 
intercostal),  or  up  into  the  neck,  probably  along  the  supra-clavicular  l)ranch  from 
the  cervical  plexus,  whicli  communicates  witli  the  second  intercostal  (Treves). 
The  gland  is  su])])lied  ])y  tlie  following  arteries  :  the  aortic  intercostals  of  the 
second,    third,   fourth,    and    fifth    spaces,    similar    intercostal    branches   from    the 


RELATIONS   OF  LUNGS   TO   CHEST-WALLS 


nil 


internal  manimary,  which  run  outwards,  two  small  lirancht-s  to  each  space,  per- 
foratini^  branches  from  the  same  vessel,  one  or  two  given  off  opi)osite  to  each  space, 
the  loni,'  tlioracic  and  external  mammary  (when  present)  from  the  axillary. 

The  lymphatics  may  be  divided  "into  two  sets— (A)  The  majority  which 
go  along  the  chief  v(>ssels  to  the  glands  in  the  axilla,  where  the  following  groujjs 
are  to  be  found:  (1)  Axillary;  (2)  subscapular;  (3)  pectoral,  along  the  long  tho- 
racic; (4)  subclavian,  or  infra-,  and  supraclavicular.  All  these  anastomose  with 
each  other,  and  also  with  (B)  a  much  smaller  set  of  lymphatics,  which  pass  from 
the  inner  part  of  the  breast,  through  the  anterior  ends  of  the  intercostal  space,  to 
the  internal  mannnary  or  anterior  intercostal  lymphatic  glands.  Thus  they  reach 
the  mediastinal  and  deeper  Ivniphalics. 

Parts  behind  manubrium. — There  is  little  or  no  lung  behind  the  first  bone  of 
the  sternum,  the  s])ace  being  occui)ie(l  by  the  trachea  and  large  vessels,  as  f(jllows: 
— The  left  innominate  vein  crosses  behind  the  sternum  just  below  its  upper  border. 
Next  come  the  great  })rimary  branches  of  the  aortic  arcli.      Deeper  still  is  the  tra- 


FiG.  683.— Outline  ok  the  Heakt,  its  Valves,  and  the  Llngs  (shaded).     (Holdeii.) 


chea,  dividing  into  its  two  bronchi  o])])Osite  to  the  junction  of  the  first  and  second 
bones  of  the  sternum.  Deepest  of  all  is  the  O'sophagus.  Al^out  one  inch  from  the 
upper  liorder  of  the  sternum  is  the  highest  ])art  of  the  aortic  arch,  lying  on  the 
bifurcation  of  tlu^  trachea  (Ilolden). 

Outline  of  the  lungs.  Their  relation  to  the  chest-wall. — The  a]>ex  of  the 
lung  rises  about  an  inch  and  a  half  (from  half  an  inch  to  an  inch  and  three-cjuar- 
ters)  above  the  first  rib  into  the  base  of  the  posterior  triangle  lying  behind  the  inner 
end  of  the  clavicle,  the  sterno-mastoid,  and  the  anterior  scalene,  covered  l)y  the 
pleura  and  deep  cervical  fascia,  and  having  the  subclavian  artery  arching  over  it. 
From  the  apices  the  thin  anterior  borders  converge  inwards  behind  the  sterno- 
clavicular joints,  and  the  first  piece  of  the  sternum  to  the  junction  of  this  with  the 
second,  almost  meeting  at  this  point.  Thence  the  two  borders  tlescend  parallel  and 
close  to  each  other  (the  right  sometimes  )>assing  just  beyond  the  middle  line),  and 
thus  covering  over  the  heart  and  larg(>  vessels,  to  a  jtoint  midway  between  the  fourth 
pair  of  costal  cartilages,  where  they  diverge,  l>ut  not  to  an  eijual  degree.     The  right 


1112 


SURGICAL  AXD   TOPOGRAPHICAL  ANATOMY 


descends  in  an  almost  straight  line  as  far  as  the  sixth  chondro-sternal  joint.  The 
left  is  deeply  notched  (incisura  cardiaca).  The  lower  borders  of  the  lung  pass 
downwards  and  outwards  across  the  sides  of  the  chest  from  the  sixth  chondro- 
sternal  joint  to  the  tenth  thoracic  spine.  In  the  nipi)le-line  the  lung  reaches  the 
sixth  ril),  in  the  ])osterior  fold  of  the  axilla,  the  eighth,  and  opposite  the  angle  of 
thescajnda  (the  arms  being  close  to  the  sides),  the  tenth  rib.  Thus,  to  map  out  the 
lung,  a  line  should  l)e  drawn  from  the  apex,  a  point  about  an  incli  and  a  half  above 
the  first  rib,  a  little  outside  the  sterno-mastoid  muscle,  obliquely  inwards,  behind 
the  sterno-clavicular  joint,  to  near  the  centre  of  the  junction  of  the  first  and  second 
bones  of  the  sternum.  Thence,  on  each  side,  a  line  should  be  draAvn  slightly  con- 
vex as  far  as  a  similar  point  on  the  sternum  lying  opposite  the  articulation  of  the 
fourth  chondro-sternal  joint.  On  the  right  side  the  line  may  be  dropped  as  low  as  the 
sixtli  chondro-sternal  joint;  on  the  left  (to  show  the  incisura  cardiaca)  a  line  should 
be  drawn  sloping  outwards  from  the  fourth  chondro-sternal  articulation  along  the 
lower  border  of  the  fourth  rib,  across  the  fourth  interspace,  to  a  point  about  an 
inch  and  a  half  lielow  the  left  nipple  (male)  and  an  inch  to  its  inner  side.  This 
point,  lying  in  the  fifth  space,  marks  the  apex  of  the  heart.  The  lower  border  of 
the  lung  will  be  marked  on  the  right  side  by  a  line  drawn  from  the  sixth  chondro- 


FlG. 


684. — Diagram  of  the  Relatioxs  of  the  Thoracic  Viscera  to  the 
Walls  of  the  Chest.     (Bellamy.) 


Superior  eul-de-sao  of  right  lung  — ___ 


RIGHT  AURICLE 
RIGHT  AURICULAR  APPENDAGE 
Kight  auriculo-ventrioular 
orifice 


Limit  of  diaphragm  in  com- 
plete respiration 

Limit  of  the  anterior  and  in- 
ferior border  of  right  lung 
in  complete  expiration 

Limit  of  right  lung  in 
inspiration 
Limit  of  diaphragm  in  com- 
plete inspiration 


Limit  of  pleura 


^_, —Superior  cul-de-sao  of  left  lung 


-U- LEFT  AURICLE 

X         _'  Pulmonary  orifice 

Left  auriculo-ventricular  orifice 
Orifice  of  aorta 


Limit  of  diaphragm  in 
complete  expiration 

Limit  of  the  anterior  and  infe- 
rior border  of  left  lung  in 
complete  expiration 


Limit  of  left  lung  in 
inspiration 


-  Limit  of  pleura 


sternal  articidation  across  the  side  of  the  chest  down  to  the  tenth  thoracic  si)ine.  The 
lower  border  of  the  left  lung  will  follow  a  similar  line,  starting  on  a  level  with  a  simi- 
lar joint  (sixth  chondro-sternal  joint),  but  much  farther  out  than  on  the  right  side, 
i.e.  in  the  lifth  space,  about  three  inches  to  the  left  of  the  middle  line,  or  a  point  corre- 
sponding to  the  heart's  apex.  This  margin  of  the  lung  descends  about  an  inch  and  a 
half  in  deep  inspiration,  according  to  Godlee.  The  position  of  the  great  fissure  in 
each  lung  may  be  ascertained  approximately  by  drawing  a  line  from  the  second  thora- 
cic spine  to  the  sixth  rib  in  the  nipple  line;  and  the  smaller  fissure  of  the  right  lung 
extends  from  the  middle  of  the  foregoing  to  the  junction  of  the  fourth  costal  car- 
tilage with  the  sternum.  It  will  be  seen  from  the  above  tliat  there  is  little  lung 
behind  the  manubrium.  The  connective  tissue  here  between  the  lung  margins 
contains  up  to  puberty  the  thymus,  and,  later,  its  remains.  The  pleura  reaches 
lower  down  than  the  lung.  Thus  its  lower  margin  reaches  along  the  seventh  ril) 
cartilage  near  the  sternum;  in  the  axillary  line  it  has  reached  the  lower  margin  of 
the  ninth  rib;  fartlier  ])ack  it  reaches  as  low  as  the  twelfth  rib,  or  the  eleventh  tho- 
racic spine.  Thus  it  may  be  o])ened  in  operations  in  the  loin,  e.g.  on  the  kidney, 
or  in  removing  the  twelfth  ril).  Mr.  Ilolden  thus  draws  attention  to  this  lower  level 
of  the  pleura:   'Since  the  j)l('ura  lines  the  inside  of  the  last  rib,  a  musket-ball  or 


RELATION  OF  HEART  TO    CI  I  EST- WALLS  lliy 

oilier  forei<rii  Ixxly,  loose  in  the  ])U'ural  sac  and  rolling  on  the  diaphragm,  might 
fall  to  the  lowest  part  of  the  sac,  which  would  he  between  the  eleventh  and  twelfth 
rihs.  The  ball  might  be  extracted  here.  The  chest  might  also  be  tai)ped  here,  but 
not  with  a  trocar,  since  a  trocar  would  j>enetrate  both  layers  of  jtleura  and  go 
through  the  diaphragm  into  the  abdomen.  The  operation  should  l)e  done  cautiously 
by  an  incision  beginning  about  two  inches  from  the  sjjine,  on  the  outer  border  of 
the  erector  s))in8e,  on  a  level  lietween  the  spines  of  the  eleventh  and  twelfth  thoracic- 
vertebriv.  The  intercostal  artery  will  not  be  injured  if  the  opening  be  made  below 
the  middle  of   the  s)»;iee,   wliieli  is  v<'rv  wide.' 

Outline  of  the  heart.  Its  relation  to  the  chest-wall. — The  upi)er  limit  of 
the  heart  (base)  will  be  defined  l»y  a  line  crossing  the  sternum  a  little  above  the 
upper  border  of  the  third  costal  cartilage,  reaching  about  half  an  inch  to  the  right 
and  al)out  one  inch  to  the  left.  Its  apex  corres])onds  to  a  point  in  the  fifth  space, 
about  two  inches  below  the  male  left  nipple,  and  an  inch  to  tlie  inner  side.  This 
point  will  be  about  three  inches  from  the  left  border  of  the  sternum.  The  right 
border  (right  auricle)  will  be  given  by  a  line,  slightly  convex  outwards,  drawn 
from  the  right  extremity  of  the  upjier  border  to  the  right  seventh  chondro-sternal 
joint.  If  another  line,  similarly  slightly  convex,  be  drawn  onwards  from  this  jjoint 
across  the  last  piece  of  the  sternum,  just  above  the  xiphoid  cartilage,  to  the  apex, 
it  will  give  the  lower  border  (right  ventricle),  which  rests  on  the  central  tendon  of 
the  diaphragm.  The  left  border  (left  ventricle)  will  be  given  by  a  line,  convex  to 
the  left.  i»assing  from  the  left  extremity  of  the  upper  border  to  the  apex,  well  insid*- 
the  nipple  line.  This  line  should  be  three  inches  from  the  middle  of  the  sternum 
at  the  level  of  the  fourth  costal  cartilage. 

If  a  circle  two  inches  in  diameter  be  described  around  a  point  midway  between 
the  left  nipple  and  the  lower  end  of  the  gladiolus,  it  Avill  define  with  sufficient 
accuracy  for  practical  purposes  that  part  of  the  heart  which  lies  innnediately 
behind  the  chest  wall,  and  which  is  uncovered  by  lung  or  pleura  (Latham). 

The  valves. — The  pulmonary  valves  (the  most  superficial)  lie,  in  front  of 
the  aortic,  bi-hind  the  left  clKMidro-stenial  joint,  and  opposite  to  the  U])per  border 
of  the  third  costal  cartilage.  The  aortic  valves  lie  behind  and  a  little  below 
these,  opposite  to  the  inner  end  of  the  third  intercostal  space,  and  on  a  level  with 
the  lower  border  of  the  third  costal  cartilage.  The  auriculo-ventricular  open- 
ings lie  at  a  somewhat  lower  level  than  that  of  the  aortic  and  i)ulmonary.  Thus 
the  tricuspid  valves  lie  behind  the  sternum  at  the  level  of  the  fourth  intercostal 
space;  and  the  mitral  valves,  the  most  deeply  placed  of  all,  lie  a  little  to  the  left 
of  these,  behind  the  left  edge  of  the  sternum  and  the  fourth  left  costal  cartilage. 

'  Thus  these  valves  are  so  situated  that  the  mouth  of  an  ordinary-sized  stetho- 
scope will  cover  a  portion  of  them  all,  if  placed  over  the  juncture  of  the  third 
intercostal  space,  on  the  left  side,  with  the  sternum.  All  are  covered  by  a  thin 
layer  of  lung;  tlierefore  we  hear  their  action  better  when  the  breathing  is  for  a 
nKjment  suspended  '  (  IIolden\ 

Relation  of  vessels  to  the  wall  of  the  thorax. — Aortic  arch, — The 
ascending  part  reaches  from  a  spot  behind  the  sternum,  a  little  to  the  left  of  the 
centre,  on  a  level  with  the  third  left  costal  cartilage,  to  the  upper  border  of  the 
second  right  cartilage;  thus  it  passes  upwards,  backwards,  and  to  the  right,  and  is 
about  two  inches  long.  The  transverse  part  then  crosses  to  the  left  behind  the 
sternum  (the  highest  part  of  the  arch  being  about  an  inch  l)elow  the  notch), 
reaching  from  the  second  right  costal  cartilage  to  the  lower  border  of  the  fourth 
thoracic  vertebra  on  the  left  side.  This  ])art  recedes  from  the  surface,  and,  with 
the  next,  cannot  be  marked  out  on  the  surface.  The  third,  or  descending  i)art,  the 
shortest  of  the  three,  reaches  from  the  lower  border  of  the  fourth  to  that  of  the 
fifth  thoracic  vertebra. 

Innominate  artery. — A  line  drawn  fnjm  the  toj)  of  the  arch,  aliout  an  inch 
below  the  sternal  notch,  and  a  little  to  the  right  of  the  centre,  to  the  right  sterno- 
clavicular joint,  will  irive  the  line  of  this  vessel. 

Left  common  carotid. — This  vessel  will  be  denoted  by  a  line  somewhat  sim- 
ilar to  the  al)ove.  jiassing  from  the  level  of  tlie  arch  a  little  to  the  left  of  the  last 
starting  point  to  the  left  .sterno-clavicular  joint. 

Left  subclavian  artery. — A  line  from  the  end  of  the  transverse  arch,  behind 


1114  SURGICAL   AXD   TOPOGRAPHICAL  ANATOMY 

the  left  of  the  sternum,  straight  upwards  to  the  clavicle,  delineates  the  vertical 
thoracic  c<»nrs(>  of  the  long  left  subclavian  artery  (Sheild). 

Innominate  veins. — The  left,  three  inches  long,  extends  very  oblicjuely  from 
the  left  sterno-clavicular  joint,  to  a  i)oint  half  an  inch  to  the  right  of  the  sternum, 
in  the  first  intercostal  sjtace.  The  right,  al)out  an  inch  long,  descends  almost 
vertically  to  the  above  ])(>int  from  the  right  sterno-clavicular  joint. 

Venae  cavae. — The  superior  descends  from  the  point  above  given  for  the 
meeting  of  the  innominate  veins  in  the  first  intercostal  space,  close  to  the  sternum, 
and  ]ierforates  the  right  auricle  on  a  level  with  the  third  costal  cartilage.  The 
inferior  vena  cava. —  The  opening  of  this  vein  into  the  right  auricle  lies  under  the 
middle  of  the  fifth  riglit  intersi)ace  and  the  adjacent  part  of  the  sternum. 

Internal  mammary  artery. — This  descends  l)ehind  the  clavicle,  the  costal 
cartilages,  and  the  first  six  spaces,  about  half  an  inch  from  the  edge  of  the 
sternum.  In  the  sixth  intercostal  space  it  divides  into  musculo-phrenic  and 
superior  epigastric  arteries. 


Till:   ABD03IEN 


Skin  markings ;  bones  and  muscular  landmarks. — The  linea  alba,  or 
meeting  of  the  aponeuroses  of  the  great  abdominal  muscles  over,  under,  and 
between  the  recti,  reaches  from  the  apex  of  the  xiphoid  cartilage  to  the  symphysis. 
It  is  best  marked  above  the  umbilicus.  Its  little  vascularity  and  comparative 
thinness  fit  this  line  for  the  point  of  election  for  many  of  the  operations  on  the 
abdominal  cavity.  In  the  linea  alba,  a  little  below  its  centre,  is  the  umbilicus. 
This  corresponds  to  the  level  of  the  fibro-cartilage  between  the  third  and  fourth 
lumbar  vertebrae,  the  tip  of  the  third  lumbar  spine  (Windle),  the  highest  point  of 
the  iliac  crests,  and  a  point  three-quarters  of  an  inch  to  one  inch  above  the  bifur- 
cation of  the  aorta. 

On  each  side  of  the  linea  alba,  and  about  two  and  a  half  to  three  inches  from 
it  (according  to  the  muscular  development),  a  line,  curved  with  a  slight  convexity 
outwards,  the  linea  semilunaris,  denotes  the  point  of  division  of  the  abdominal 
aponeuroses,  reaching  from  the  ninth  costal  cartilage  to  the  pubic  spine.  Between 
the  linea  alba  and  the  linea  semilunaris  run  the  three  linese  transversa^  of  which 
one  is  placed  at  the  uml^ilicus,  another  at  the  xiphoid  cartilage,  and  a  third  between 
the  two,  on  a  level  with  the  tenth  costal  cartilage.  There  is,  rarely,  a  fourth  below 
the  umbilicus. 

In  very  corpulent  subjects  two  deep  transverse  furrows  run  across  the  abdomen. 
One  runs  across  the  navel  and  completely  conceals  it;  the  other  is  lower  down, 
just  above  the  fat  of  the  pubes.  In  tapping  the  bladder  above  the  pubes  in 
such  a  case,  the  trocar  should  be  introduced  where  this  line  intersects  the  linea 
alba  (Holden). 

A  transverse  line  drawn  from  one  anterior  superior  spine  to  the  other  crosses  at 
about  the  level  of  the  top  of  the  promontory  of  the  sacrum.  Such  a  line  will 
always  show  whether  the  pelvis  is  horizontal  or  not  (Holden). 

Poupart's  ligament  corresponds  to  a  line  drawn  with  a  slight  curve  down- 
wards between  the  anterior  superior  spine  and  the  pubic  spine.  The  first  of  these 
bony  prominences  corresponds  to  the  starting-point  of  the  above  ligament,  the 
attachment  of  the  fascia  lata  to  the  ilium,  the  meeting  of  the  fieshy  and  aponeu- 
rotic parts  of  the  external  oblique  (denoted  by  a  line  drawn  upwards  from  this 
spine  to  the  ninth  costal  cartilage,  or  often  a  little  anteriorly  to  these  i)oints),  the 
point  of  emergence  of  the  external  cutaneous  nerve,  and  part  of  the  origins  of  the 
internal  oblique,  transversalis.  and  t(msi)r  vaginre  femoris.  The  pubic  spine  marks 
the  outer  pillar  of  the  external  abdominal  ring,  the  mouth  of  which  corresponds 
to  the  crest,  or  that  part  of  the  pubes  lying  between  the  spine  and  tlie  symphysis. 


I 


THE  ABDOMINAL   RINGS 


11 15 


The  ring,  and  especially  its  outer  pillar,  can  easily  be  felt  by  invaginatin<r  the 
scrotal  skin  with  a  linger,  and  pusliing  upwards  and  outwards.  In  a  female 
patient,  if  the  thigh  be  abducted,  the  tense  tendon  of  the  adductor  longus  will 
lead  up  to  the  site  of  the  ring.  The  internal  ring  is  situated  about  half  an  inch 
above  the  centre  of  Poupart's  ligament;  oval  in  shape,  and  nearly  vertical  in 
direction,  it  has  the  arching  fibres  of  the  transversalis  abovy  it,  and  to  its  inner 
side  the  deep  epigastric  artery.  The  canal  runs  obli(piely  downwards  and  for- 
wards between  the  two  rings.  In  the  adult  it  is  aixuit  an  inch  and  a  half  long,  but 
in  early  life,  and  in  adults  with  a  large  hernia  dragging  upon  the  i>arts,  the  two 
rings  are  much  nearer,  and  may  be  one  behind  the  other.  If  the  external  ring  lie 
exposed,  and  the  finger  thrust  carefully  up  tlu^  canal,  the  following  structures  will 
be  noted: — After  the  finger  has  carefully  dilated  the  canal,  its  tij)  will  l»e  prevented 
from  entering  the  abdomen  l)y  the  infundilndiform  fascia.  If  it  be  pressed  down- 
wards, it  will  feel  Poupart's  ligament,  which,  with  the  meeting  of  the  fascia  trans- 
versalis, forms  the  floor;  above,  it  will  be  arrested  by  the  arching  fibres  of  the 

Fk;.  «h.'). — oiu.K^ius  ExTEKXus  Axi)  Fascia  Lata. 


Intercolumnar 
flbrea 


Aponeurosis  — 
of  obliquus 
externuB 
SPERMATIC 
CORO 
Origin  of 
eremaster 
Triangular 
fascia 

Insertion  of 
eremaster 


External 
abdominal 
ring 

Saphenous 
opening 


internal  oblique  and  transversalis,  coming  down  to  the  })ectineal  line  to  form  the 
conjoined  tendon.  Towards  the  abdominal  wall  the  finger  will  feel  the  aponeurosis 
of  the  external  oblicjue  stretcliing  over  the  wliole  anterior  as})ect  of  the  canal;  if 
turned  tow^ards  the  belly  cavity,  the  finger  would  feel  less  resistant  layers,  viz. 
extra-peritoneal  fat  and  peritoneum,  and,  liehind  the  external  ring,  the  conjoined 
tendon.  The  finger  would,  of  course,  also  take  notice  of  the  spermatic  cord  in  the 
male  and  the  round  ligament  in  the  female,  and  investigate  any  alteration  in  the 
former,  and  isolate  the  vas  deferens. 

Vessels  in  the  abdominal  wall. — The  three  superficial  branches  of  the 
connnoii  femoral,  the  external  pudic  (superior  and  inferior),  epigastric  and  circum- 
flex iliac,  supply  the  lower  part  of  the  abdominal  wall  and  the  atljacent  groin  and 
genitals.  The  only  others  that  have  to  l)e  remembered  are  the  deep  epigastrics  and 
epigastric  branch  of  the  internal  mammary,  the  deep  circumflex  iliacs,  the  last  two 
intercostals,  and  the  abdominal  1  tranches  of  the  lumbar  arteries.  Of  these,  the  dee]» 
epigastric  is  the  most  ini]»ortant;  its  course  will  be  marked  out  l»y  a  line  drawn 
from   a  jtoint   just    internal   to  the    centre   of    Poupart's   ligament,    uitwards   and 


IIIG 


SURGICAL   AXD   TOPOGRAPHICAL  AXATOMY 


inwards  to  the  inner  side  of  the  internal  ring,  and  thence  to  a  point  about  midway 
between  the  pubes  and  iinibilicvis.  Here  the  vessel,  which  at  first  lies  between  the 
peritoneum  and  fascia  transversalis,  perforates  the  latter  and,  passing  over  the  fold 
of  Douglas,  enters  the  sheath  of  the  rectus.  It  then  runs  ui)wards,  closely  a]iplicd 
to  the  back  of  that  muscle,  and,  a  little  above  the  level  of  the  umbilicus,  divides 
into  liranches  which  anastomose  with  the  epigastric  or  abdominal  In-anch  of  the 
internal  mammary. 

Lymphatics. — It  is  sufficiently  correct  to  say  here  that  those  above  the 
umbilical  line  go  to  the  axillary,  and  those  beloAV  that  line  to  the  femoral 
glands. 

Nerves. — The  lower  seven  intercostals  and  the  ilio-hypogastric  and  ilio- 
inguinal su}>i)ly  the  abdominal  wall.     The  sixth  and  seventh  intercostals  supply 

Fig.  686. — The  Viscera  as  seen  ox  fully  opening  the  Abdomen  withoct 

DiSAKEANGEMENT  OF  THE   INTERNAL   PARTS.      (After  Sarazin.') 


Diaphragm 


REAT  OMENTUM 


SMALL  INTESTINE 


the  skin  over  'the  pit  of  the  stomach';  the  ciglilii  the  aiva  of  the  middle  linea 
transversa;  the  tenth  that  of  the  umbilicus;  the  last  thoracic,  ilio-inguinal,  and 
ilio-hypogastric,  the  region  above  Poupart's  ligament,  and  that  of  the  pubes.  The 
ilio-hypogastric  supplies  the  skin  over  the  external  ring;  the  ilio-inguinal  that 
over  the  cord  and  scrotum.  The  last  thoracic  and  ilio-hypogastric  cross  the  iliac 
crest  to  supply  the  skin  of  the  buttock. 

Viscera  and  visceral  regions. — The  general  form  of  the  abdominal  space, 
and  the  relations  of  llic  several  organs  before  they  are  disturbed  from  their  normal 
positions,  are  given  on  pages  959  and  960.  The  arbitrary  regions  into  which  the 
abdomen  is  usually  divided  are  described  at  the  end  of  this  article. 

The  diaphragm. — The  upper  limit  of  the  al)domen  rises  to  the  following  levels: 
Its  central  tendon  to  al)out  the  lower  end  of  the  sternum,  or  the  seventh  chondro- 


RELATION  OF  VISCERA    TO   ABDOMfXAL    WALLS 


1117 


eternal  joint;  tlic  ri^ilit  lialt"  t<»  al)()Ut  tlic  U'vel  of  the  iit'lli  rili,  or  about  one  inch 
below  the  nij)})le;  the  left  half  not  risin<i  (juite  so  high. 

Viscera  behind  the  linea  alba. — From  al)ove  downwards  there  are  the  folhjw- 
ing  (tig.  686): — (1)  Above  the  umbilicus — the  left  lobe  of  the  liver,  the 
stoniach,  the  transverse  <(iloii.  part  of  the  great  omentum,  the  pancreas  and  solar 
plexus.  (2)  Below  the  umbilicus — the  rest  of  the  great  omentum,  covering  in 
the  small  intestines  and  their  mesentery.  In  the  cliild,  the  l)ladder  occupies  a 
partly  abdominal  position;  and  in  tiie  adult,  the  same  viscus,  if  distended,  may 
rise  out  of  the  i)elvis  and  displace  the  above  structures,  raising  the  peritoneum 
until,  if  distended  half  way  to  the  uml)ilicus,  there  is  an  area  of  nearly  two  inches 
safe  for  operations  above  the  symphysis.  The  graviil  uterus  also  rises  along  the 
linea  all)a. 

The  liver  (figs.  579,  580,  and  581). — In  the  erect  position,  the  ante^-ior  thin 
edge  of  the  liver  projects  about  half  an  inch  below  the  costal  cartilages,  but  can 
only  be  made  out  with  difhculty  in  this  i)osition.  It  may  also  be  displaced  down- 
wards by  pleuritic  effusion  or  tight  lacing.  The  liver  is  also,  proportionately, 
much  larger  in  little  children. 

Fig.  687.— Sectiox  of  Abdomen  between  the  Third  and  Fourth  Lumbar 

Vertebrae.     (Braune.) 

UMBILICUS 


Rectus 
SYMPATHETIC  \ 


GREAT  OMENTUM 
URETER 


TRANSVERSE  COLON 


TranBversalis 

I  riternal  oblique 


ernal   oblique 


DESCENDING  COLON 
Quadratus  lumborum 

Psoas 

A  orta 

ARTICULAR  PROCESS  OF  THIRD  LUMBAR 


ASCENDING  COLON 


Psoas 
Vena  cai'a 


INTERVERTEBRAL  CARTILAGE 


Of  the  three  parts  of  the  liver  (according  to  the  regions  which  it  occupies),  that 
in  the  right  hypochondrium  corresponds  to  the  lower  margin  of  the  thorax;  but  in 
the  epigastric  region  the  anterior  margin,  ruiming  oblicpiely  across  from  the  ninth 
right  to  the  eighth  left  costal  cartilage,  crosses  the  middle  line  about  a  hand's 
breadth  below  the  sterno-xiphoid  articulation  (Godlee).  The  size  of  the  left  lobe 
varies.  In  infants  it  will  occu]>y  the  left  hypochondrium;  in  adults  its  extent  to 
tlie  left  will  vary  from  a  ])oint  an  inch  and  a  half  or  two  inches  beyond  the  sternum 
to  the  left  nipi)le  line.  The  level  of  the  U}>per  l)ordcr  varies  also  with  position, 
respiration,  etc.  It  may  be  rej^resented,  on  the  right,  by  a  line  drawn  about  one 
inch  below  the  nipple,  along  the  seventh  rib,  towards  the  middle  line,  the  fifth 
chondro-sternal  joint,  and  the  sterno-xiphoid  articulation  (or  central  tendon  of  the 
diaphragm);  on  the  left  side  it  does  not  reach  quite  so  high:  thus  its  level  would 
be  marked  by  the  sixth  chondro-sternal  joint.  Behind,  the  liver  would  be  below 
the  base  of  the  right  lung,  on  a  level  with  the  tenth  thoracic  spine  ( tigs.  708,  709, 
and  710). 

Gall-bladder. — Tlie  fundus  of  this,  situated  in  a  fossa  on  the  under  surface  of 


1118 


SURGICAL  AXD  TOPOGRAPHICAL  ANATOMY 


the  right  lobe  of  the  Uver,  and  having  the  quadrate  lobe  to  its  left,  lies  oi)i)osite  to 
the  right  ninth  costal  cartilage,  close  to  the  outer  edge  of  the  rectus.  It  is  in 
contact  with  the  hei)atic  flexure  of  the  colon  and  the  first  piece  of  the  duodenum. 
Stomach  (figs.  566-569,  p.  960). — This  organ  varies  in  position  more  than  any 
other,  owing  to  its  mobility,  save  at  the  cardiac  orifice,  and  to  its  varying  disten- 
sion. \\'hen  empty  and  contracted,  it  lies  far  back  in  the  abdomen,  under  the  left 
lobe  of  the  liver,  and  in  front  of  the  pancreas.  AMien  much  distended,  its  pyloric 
end  moves  to  the  right,  and  the  organ  comes  forwards,  pushing  against  the  liver 
and  alidominal  wall;  and  upwards,  against  the  diaphragm,  and  thus  against  the 
heart  and  left  lung.  If  moderately  distended,  the  cardia  will  be  found  under  the* 
seventh  left  chondro-sternal  joint,  about  one  inch  beyond  the  sternum.  The  pylorus 
is  very  moV)ile,  liut  a  spot  near  the  end  of  the  cartilage  of  the  eighth  rib  will  denote 
it  with  sufficient  accuracy.  It  is  on  a  deeper  plane  than  the  cardia.  By  joining 
these  two  points  with  lines  representing  the  lesser  and  greater  curvatures,  the 
stomach  can  be  marked  out  (figs.  708,  709).  The  usual  inaccuracies  committed  in 
delineating  the  stomach  are  as  follows:  The  viscus  is  marked  too  horizontally — 
students  forget  its  oblique  position.     The  greater  curvature  and  fundus  are  not 


Fig.  688.— Diageam  showing  Relation  of  Kidney  to  Capsule. 


TRANSVERSE  COLON 


DESCENDING  COLON 

PERITONEUM 

FATTY  CAPSULE 

KIDNEY   ^ 
PERITONEAL  CAVITY 


Diaphragmatic 
fascia 


Parietal  muscle 


Muscular  fibre  in 
subperitoneal 


Sup.  mesenteric  vein 
DUODENUM 


LYMPHATIC  GLAND 


LUMBAR  VERTEBRA 


SUBPERITONEAL  TISSUE         FATTY  CAPSULE 


bedded  in  snipe 


marked  high  enough  on  the  left  side.  They  are  placed  high  up  under  the  left  arch 
of  the  dia])hragm,  well  to  the  left  of  the  middle  line,  as  high  as  the  sixth  chondro- 
sternal  joint.  The  lesser  curvature  is  usually  made  too  curved  and  too  horizontal 
(Sheild). 

The  pancreas. — This  lies  a  little  obliquely  behind  the  stomach,  crossing  the 
aorta,  inferior  cava,  and  spine  about  the  junction  of  the  first  and  second  luml)ar 
vertebrae,  or  three  inches  above  the  umbilicus  (fig.  587,  p.  987,  and  fig.  710,  p. 
1147).  A  little  lower  is  the  third  piece  of  the  duodenum,  reaching  to  within 
an  inch  of  the  umbilicus  (Godlee). 

Intestines — (A)  Small. — The  only  parts  of  these  that  can  be  localised  at  all 
definitely  are  the  duodenum  and  its  junction  with  the  jejunum  and  the  ending  of  the 
ileum  in  the  cax-um.  The  first  piece  of  the  duodenum  lies  in  the  right  hyi)Ochon- 
drium.  usually  near  the  gall-bladder  (vide  ■•mprd)^  reaching  from  the  pylorus 
upwards,  backwards,  and  to  the  right.  This  is  the  most  mobile  of  the  three  parts. 
The  second,  or  descending,  is  in  relation  with  the  head  of  the  pancreas,  and  reaches 
the  right  lumbar  region,  descending  as  low  as  the  second  or  third  lumbar  vertebra. 
The  third,  or  oblique,  portion  passes  from  the  third  lumljar  vertebra  ol)liquely  from 
right  to  left  across  the  second,  and,  ascending,  ends  in  the  jejunum  on  the  left  side 


RELATION  OF  KIDNEYS   TO   ABDOMINAL    WALLS  1119 

of  the  spine.  This  portion  of  the  intestine  being  firmly  secured  in  place  by  fibres 
from  the  left  cms  of  the  diaphragm  and  the  connriencement  of  the  mesentery, 
accounts  for  rupture  of  the  intestine  usually  occurring  near  this  spot. 

Of  the  jejunum  and  ileum  it  may  be  .said  that,  if  undistended,  the  coils  of  the 
jejunmn  (about  eight  feet}  occui)y  rather  the  left  side,  and  that  of  the  ileum 
(twelve  feet),  the  right  side,  in  addition  to  the  central  regions,  where  the  jejuiuim 
would  be  chieHy  above,  and  the  ileum  below.  According  to  Mr.  Treves,  the  coils 
most  usually  found  in  the  pelvis  belong  to  the  terminal  jiart  of  the  ileum,  and  that 
])art  of  the  intestine  which  has  the  longest  mesentery,  viz. :  that  extending  between 
two  jioints  respectively  six  and  eleven  feet  fnjm  the  end  of  the  duodenum.  But  as 
there  is  no  definite  limit  between  the  jejunum  and  ileum,  so  is  there  no  regular 
arrangement  of  their  coils.  If  i>resent,  a  Meckel's  diverticulum  would  arise  from 
one  to  three  feet  from  the  termination  of  the  ileum. 

The  upper  limit  of  the  mesentery  would  be  marked  by  a  spot  about  three 
inches  above  the  umbilicus  and  a  little  to  the  left  of  the  centre  of  the  body  of  the 
second  lumbar  vertebra.  From  this  point  it  extends  obliquely  to  the  right  iliac 
fossa,  where  it  ends  in  the  ileo-ctecal  junction,  about  four  inches  above  the  centre 
of  Poupart's  ligament.      Its  average  length  is  about  eight  inches. 

(B)  Large  intestine. — The  caecum  measuring  about  two  and  a  half  inches 
both  in  its  vertical  and  transverse  diameters,  lies  in  front  of  the  ilio-psoas,  and 
should  be  so  mapped  out  behind  the  anterior  abdominal  wall  as  to  lie  above  the 
outer  half  of  Poupart's  ligament,  and  with  its  apex  or  lowest  point  projecting 
just  beyond  the  inner  border  of  the  psoas,  and  thus  corresponding  to  a  point  a 
little  to  the  inner  side  of  the  centre  of  Poupart's  ligament.  Not  unfrequently  it 
lies  more  external,  still  in  the  right  iliac  region,  but  entirely  on  the  iliacus.  The 
ileo-caecal  valve,  or  junction  of  the  small  and  large  intestines,  corresponds  to  a 
point  about  two  inchc^s  internal  to  and  a  little  above  the  anterior  superior  spine. 
The  l)ase  of  the  vermiform  appendix,  which  usually  comes  off  close  to  the  valve  on 
the  posterior  Avail  of  the  caecum,  would  be  represented  by  the  above  point  with 
sutlicient  accuracy.  The  appendix  itself,  averaging  four  inches  in  length,  of  the 
size  of  a  goose-quill,  and  usually  twisted  on  itself  owing  to  the  shortness  of  its 
mesentery,  generally  projects  behind  the  caecum,  ileum,  and  mesentery,  in  the 
direction  of  the  spleen  (Treves),  or  downwards  to  the  left,  so  as  to  approach  the 
l)rim  of  the  pelvis.  The  ascending  colon,  covered  by  small  intestine,  lies  deei)ly 
as  it  passes  up  over  the  kidney  through  the  right  luml)ar  region.  The  hepatic  and 
splenic  flexures  lie  deeply  also  in  the  hypochondriac  regions,  the  splenic  being 
higher  than  the  hepatic,  and  behind  the  stomach,  while  the  former  is  in  contact 
with  the  under  surface  of  the  liver.  Between  the  two  courses  the  transverse 
colon,  in  close  contact  with  the  great  curvature  of  the  stomach,  and  varying  in 
position  from  one,  two,  or  thnc  inches  above  the  umbilicns,  to  one  nearer  or  even 
below  this  point.  The  descending  colon  follows  a  similar  course  to  the  ascend- 
ing; and  the  sigmoid  flexure  occupies  the  left  iliac  fossa,  and  from  this  point 
passes  over  the  brim  of  the  i)elvis.  Except  at  its  hepatic  and  s])lenic  flexures,  the 
colon  can  be  examined  through  the  parietes,  aided  by  an  anaesthetic.  The  ca?cum 
is  the  most  superficial  of  all. 

Landmarks  for  lumbar  colotomy. — (A  )  The  lower  border  and  Uy  of  the  last 
rib,  which  varies  in  length;  (2)  a  point  half  an  inch  bchintl  the  centre  of  the  iliac 
crest,  this  point  being  found  by  accurate  measurement  along  the  crest  between  the 
anterior  and  po.'^terior  spines  (Allingham);  (o)  a  line  drawn  vertically  ujnvards 
from  the  last-mentioned  point  to  the  last  rib.  This  gives  with  sufficient  correct- 
ness the  line  of  the  outer  edge  of  the  quadratus,  and  the  position  of  a  normal 
colon. 

Iliac  or  anterior  colotomy. — The  incision  here,  whether  for  opening  the 
sigmoitl  flexure  or  the  ciecum,  is  one,  two  and  a  half,  or  three  inches  long,  made 
parallel  with  the  outer  part  of  Poupart's  ligament,  and  one  and  a  half  inches 
above  it. 

The  kidneys. — Tiie.se  lie  at  the  back  of  the  abdominal  cavity  so  deeply  in  the 
hypochondriac  and  epigastric  region  as  to  be  beyond  palpation.  unle.>;s  enlarged  or 
unduly  mobile.  The  lower  end  of  the  right  being  slightly  li»wer  than  its  fellow, 
encr<.>aclies  in  health  upon  the  lumbar  and  epigastric  region.     These  organs  lie  nnich 


1120 


SURGICAL  AND   TOPOGRAPHICAL  A.XATOMY 


higher  than  is  usually  supposed  to  be  the  case,  the  upper  two-thirds  of  the  right 
and  all  the  left  kidney  being  behind  the  ribs.  To  mark  them  in  from  the  front 
the  following  points  should  be  noted:  The  upper  extremity  should  reach  as  high 
up  as  the  seventh  costal  cartilage,  close  to  the  costo-chondral  junction.  The 
lower  end,  about  four  and  a  half  inches  below  this  point,  should  be  above  a 
line  drawn  horizontally  through  the  umbilicus,  though  it  is  to  be  remembered 
that  the  right  often  encroaches  upon  this  line.  Relatively  to  the  vertebriP,  the 
kidneys  lie  along  the  sides  of  the  last  thoracic  and  the  tirst  three  lumVjar.  A 
vertical  line  carried  up  to  the  costal  arch  from  the  centre  of  Poupart's  ligament  has 
one-third  of  the  kidney  to  its  outer  side,  and  two-thirds  to  its  inner  side,  i.e. 
between  this  line  and  the  median  line  of  the  body.  The  distance  between  the  two 
kidneys  and  between  each  viscus  and  the  middle  line  is  thus  given  by  Thane  and 
Godlee:  The  position  of  the  superior  pole  is  indicated  by  a  spot  about  two  'inches 
from  the  middle  line,  the  hilum  is  placed  at  the  same  distance,  and  the  inferior 
pole  about  two  and  a  half  to  three  inches  from  the  middle  line.  The  shortest  dis- 
tance between  the  two  kidneys,  'at  the  upper  part  of  their  mesial  borders,'  meas- 
ures about  two  and  a  half  inches. 

Fig.  689. — Transverse  Section  of  the  Abdomen  through  the  Kidneys  and 
Pancreas,  at  the  level  of  the  first  Lumbar  Vertebra.     (Biaune. ) 

Inferior  cava 


Bound  ligament 
Rectus     I 

EIGHTH  RIB         I        ' 


TRANSVERSE  COLON 
/  SEVENTH  RIB 

'  /     ASCENDING  COLON 


SIGMOID  FLEXURE 


DESCENDING  COLON 
External  oblique 


EIGHTH  RIB 
Obliquus  externuB 

NINTH  RIB 

PLEURA 
TENTH  RIB 


Splenic  vein 

Descending  aorta 
BODY  OF  FIRST  LUMBAR  VERTEBRA 


LIVER 
Diaphragm 


ELEVENTH  RIB 
TWELFTH  RIB 


On  the  posterior  surface  of  the  body  the  kidney's  boundaries  are  indicated  by 
the  following: — (1)  A  line  parallel  with,  and  one  inch  from,  the  spine,  between  the 
lower  edge  of  the  tip  of  the  spinous  process  of  the  eleventh  thoracic  and  the 
lower  edge  of  the  spinous  process  of  the  third  lumbar  vertebra;  (2)  and  (3)  lines 
drawn  from  the  top  and  bottom  of  this  line  outAvards,  at  right  angles  to  it,  for 
two  inches  and  three-(i[uarters;  (4)  a  line  parallel  to  the  first,  and  connecting  (2) 
and  (3).     Within  this  parallelogram  the  kidney  lies  (Morris). 

The  spleen  (figs.  588  and  589). — This  lies  very  obliquely  from  above  down- 
Avards,  and  from  within  outAvards,  in  the  left  hypochondrium:  thus  its  long  axis 
corresponds  closely  with  the  line  of  the  tenth  rib.  It  is  placed  opposite  the 
ninth,  tenth,  and  eleventh  ribs  externally,  being  separated  from  these  by  the  dia- 
])hragm;  and  internally  it  is  connected  with  the  great  end  of  the  stomach.  BeloAv, 
it  overlaps  slightly  the  outer  border  of  the  left  kidney  (figs.  690,  709,  710,  and 
711).  Its  highest  point  is  on  a  level  Avith  the  spine  of  the  ninth  thoracic,  and  its 
lowest  Avith  that  of  the  eleventh  thoracic  vertebra.  Its  inner  end  is  distant  about 
an  inch  and  a  half  from  the  median  plane  of  the  body,  and  its  outer  about  reaches 
the  mid-axillary  line  (Godlee).  In  the  natural  condition  it  cannot  be  felt;  but  if 
enlarged,  its  notched  anterior  margin  extends  doAvnwards  towards  the  umbilicus, 
and  is  both  characteristic  and  readily  felt. 


RELATION  OF  KIDNEYS   TO  ABDOMINAL    WALLS 


1121 


Aorta  and  iliac  arteries. — The  aorta  enters  the  abdomen  opposite  the  last 
thoracic  vertebra  (.a  point  live  to  six  inches  above  the  umbilicus,  or  rather  above 
the  mid-i)oint  between  the  infrasternal  depression  and  the  umbilicus  (Thane  and 
(iodlee),  and  thence,  lying  to  the  left  of  the  s])ine.  divides  into  the  two  common 
iliacs  opposite  the  disc  between  the  third  and  fourth  lumbar  vertebra?,  or  opposite 
the  body  of  the  fourth  lumbar  vertebra.  This  point  is  aljout  one  inch  below  and 
to  the  left  of  the  umbilicus,  and  on  a  level  with  a  line  drawn  across  the  highest 
part  of  the  iliac  crest.  A  line  drawn  from  this  point,  with  a  curve  slightly  out- 
wards, to  just  within  the  centre  of  Poupart's  ligament,  will  give  the  line  of  the 


Fig.  goo. —The  Abdomi.val  Aorta  axd  Ixfeuiuu  Vkxa  Cava. 


GALL  BUDDER 

HEPATIC  DUCT 

CYSTIC  DUCT 

COMMON  DUCT 

Portal  vein 

Gaslro-duodenal  br. 

Huperior  pyloric  br. 

Hepatic  artery 

Light  suprarenal  rein 
Inferior  suprarenal 
artery 
Renal  artery 

Renal  vein 

Inferior  rena  cava 
KIDNEY 


Right  spermatic  vein 


Right  spermatic  artery 

Quadratus  lumborum 

muscle 

Lumbar  artery  and  rein 

Ureteric  branch  of 
spermatic  artery 


Middle  sacral  vessels 


LEFT  LOBE  OF  LIVER 

(ESOPHAGUS 

Le/t  phrenic  artery 

Right  phrenic  artery 
Superior  suprarenal 
Gastric  artery 
—   Inferior  suprarenal 
Splenic  artery 

Left  phrenic  vein 
Left  suprarenal  vein 
jL\      Superior  mesenteric 
artery 
KIDNEY 

Ureteric  branch  of  renal 
Left  spermatic  vein 

URaER 

Left  spermatic  artery 


Inferior  mesenteric  artery 

Ureteric  branch  of 
spermatic 


Ureteric  branch  of 

common  iliac 
Common  iliac  artery 


External  iliac  artery 
Internal  iliac  artery 


iliac  arteries;  the  first  two  inches  (about)  gi\'ing  the  average  length  of  the  common 
iiiac. 

The  site  of  some  of  the  branches  of  the  aorta  may  be  thus  approximately 
■  remembert  <1. 

The  cceliac  axis  is  given  off  immediately  :.ft<r  the  aorta  has  perforated  the 
diaphragm;  directly  below  this  is  the  superior  mesenteric  artery.  About  one 
inch  lower  down,  or  three  inches  above  the  umbilicus,  the  renal  arteries  are  given 
off.  About  one  inch  above  the  imibilicus  would  be  the  level  of  the  inferior 
mesenteric  artery. 

Collateral    circulation    after    ligature    of   the    common    iliac. — The  chief 
vessels  here  are: — 
71 


1122 


SURGICAL  AXD    TOPOGRAPHICAL  ANATOMY 


ABOVE. 

BELOW. 

Internal  mamniarv  and  low 
tercostals 

er 

in- 

■} 

with 

Deep  epigastric. 

Lunil)ar 

with 

Ilio-lunibar  and  circumflex  iliac. 

Middle  sacral 

with 

Lateral  sacral. 

Superior  ha^niorrhoidal 

with 

f  Inferior     and     middle     ha?mor 
1       rhoidal. 

Collateral  circulation  after  ligature  of  the  external  iliac  :- 


Deep  epigastric 


with 


Deep  circumflex  iliac 

with 

Ci  luteal  and  sciatic 

with 

Comes  nervi  ischiadic! 

with 

Obturator 

with 

Internal  pudic 

with 

Collateral  circulation  after  ligat 

ure  o 

Sciatic 

with 

Hoemorrhoidal  arteries 

with 

Pul:)ic  l)ranch  of  obturator 

with 

Branches  of  pudic 

with 

Circumflex     and    perforating    of  \ 
profunda                                         j 

with 

Lateral  sacral 

with 

Circumflex  iliac 

with 

Internal  mammary,  lower   inter- 

costals,  and  lumbar. 
Ilio-lumbar,  lumbar,  and  gluteal. 
Internal  and  external  circumflex. 
Perforating  branches  of  profunda. 
Circumflex  and  epigastric. 
External  pudic. 


Branches  of  profunda. 
Inferior  mesenteric. 
Vessel  of  opposite  side. 
Branches  of  opposite  side. 

Sciatic  and  gluteal. 

Middle  sacral. 
Ilio-lumbar  and  gluteal. 


TRF   PERIN^U3I  AND    GENITALS 


Bony  boundaries. — These  are  the  same  in  either  sex.  Al)ove  and  in  front  is 
the  symphysis  pubis,  rounded  off  by  the  subpubic  ligament ;  diverging  downwards 
and  outwards  from  this  point  on  either  side  are  the  rami  of  the  pubes  and  ischium, 
ending  at  the  tuberosities  of  the  latter.  In  the  middle  line  behind  is  the  apex  of 
the  coccyx;  and  reaching  from  this  to  the  tuberosities  are  the  great  sacro-sciatic 
ligaments,  to  be  felt  by  deep  pressure,  with  the  lower  border  of  the  gluteus 
maximus  overlapping  them.  The  depth  of  the  peringeum  varies  greatly,  from 
two  to  three  inches  (30  to  75  mm.)  in  the  posterior  and  outer  part  to  one  inch  or 
less  in  front. 

In  the  middle  line,  extending  longitudinally  through  the  perinseum,  is  the 
raphe,  the  guide  to  the  urethra,  and  '  the  line  of  safety  '  (on  account  of  the  small 
size  of  the  vessels  here)  for  operations  on  it. 

An  imaginary  line  drawn  transversely  across  the  ^^crina'um  from  one  tul)er  ischii 
'to  its  fellow  divides  the  lozenge-shaped  space  into  two  triangles — (1 )  An  anterior, 
or  urethral ;  and  (2)  a  posterior,  or  rectal. 

The  central  point  of  the  perinaeum  is  in  the  adult  nearly  an  inch  (25  mm. )  in 
front  of  the  anus,  or  midway  between  the  centre  of  the  anus  and  root  of  the  scrotum. 
Here  the  following  structures  meet,  viz.,  the  sphincter  ani,  the  two  transverse  peri- 
natal muscles,  the  accelerator  urinse,  and  the  levator  ani.  It  also  corresponds  to  the 
centre  of  the  loAver  margin  or  base  of  the  triangular  ligament.  Its  development 
varies  much  in  different  bodies.  A  little  in  front  of  this  point  is  the  bulb,  with  the 
corpus  spongiosum  })assing  forwards  from  it.  This  would  also  be  the  level  of  the 
artery  of  the  l)ulb,  so  that  in  lithotomy  the  incision  should  always  begin  below 
this  point.     A  knife  introduced  at  the  central  ])oint,  and  carrietl  backwards  and 


THE  MALE  PERIX^EUM 


1123 


very  slightly  upwards,  shouM  enter  the  ineiuhninous  un-tlira  just  in  front  of  the 
prostate.  If  i)usln'(l  more  deeply,  it  would  enter  the  neck  of  the  l)ladder.  In  lateral 
lithotomy  the  knife  is  entered  an  inch  and  a  half  (  87  mm.  )  in  front  of  tlie  anus  and 
carried  downwards  and  outwards  for  two  and  a  half  or  tlnve  inches  (()2  to  75  mm.)  into 
the  ischio-reetal  fossa,  ending  a  little  helow  and  external  to  the  mid-i)()int  Ix.'twecn  the 
anus  and  tuher  ischii.  This  incision  hogins  deeply  and  ends  more  su])<>rficially.  In 
the  deeper  part  of  the  incision  the  knife  is  carried  along  the  staff  through  the  mem- 
hranous  urethra  into  the  hladder.  The  parts  divided  in  the  operation  are — skin, 
superiicial  fascia  (hoth  layers),  transverse  ])eriiueal  vessels  and  nerves,  sujjerficial 
perinteal  vessels  and  nerves,  inferior  Inemorrhoidal  vessels  and  nerves,  transversus 
perina'i  muscle,  hase  of  triangular  ligament  (anterior  layer),  memhranous  urethra 

Fiti.  Gyl.— Thk  Male  Perinmccm.     (Modified  from  Hirschfeld  aud  Leveille.) 

BUL80-CAVERN0SUS 

Superficial  triangular  ligament 
ISCHIO-CAVERNOSUS 

Muscles  of  thigh 


y 


IXFERIOR  PVDESDA  L  XER  I 
SLPERFICIAL  PERINEAL  NERVE 

INFERIOR  HMMORRUOIDAL  NERVE 
CUTANEOUS  BRANCH  OF  FOURTH  SACRA  I. 


Oluteus  masimua 

TUBEROSITY  OF  ISCHIUM 
Great  sacro-sciatic  ligament 
Levator  ani 
Superficial  transversus  perinaei 


Sphin'^ter  ani 


and  deep  muscles,  a  venous  plexus,  posterior  layer  of  triangular  ligament,  prostatic 
urethra,  and  left  lohe  of  i)rostate  and  its  cajisule  in  part,  with  some  of  the  til)res 
of  the  levator  j)rf)stata^.  In  median  lithotomy,  an  incision  an  inch  and  a  half  long 
is  made  through  the  central  tendinous  point  and  raphe,  so  as  to  hit  the  memhra- 
nous urethra.  The  following  structures  are  divided: — Skin  and  fascia^;  some  of  the 
most  anterior  fihres  of  the  sphincter  ani;  raphe  and  central  tendinous  point;  minute 
V)ranches  of  transverse  jierinteal  vessels  and  nerves;  hase  of  triangular  ligament  in 
centre;  membranous  urethra  and  compressor  urethra'. 

The  attachments  and  arrang(Miicnts  of  the  superficial  fascia  (fig.  G03)  must  he 
traced  and  remembered.  Of  the  two  layers  of  which  it  consists,  the  sujierficial 
alone  extends  over  both  urethral  rectal  triangles  alike,  and  is  continuous  with  the 
similar  structures  in  adjacent  regions,  the  only  difference  being  that,  if  tracecl  for- 


1124 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


wards  into  the  scrotum  and  penis,  it  loses  its  fat,  and  contains  dartos  fibres.  The 
deeper  layer,  found  only  over  the  urethral  triangle,  is  called  the  fascia  of  Colles 
(tig.  693).  Attached  at  the  sides  to  the  rami  of  the  pubes,  behind  to  the  base  of 
the  triangular  ligament,  and  open  in  front,  it  forms  a  somewhat  triangular  pouch, 
containing  the  sui)erficial  vessels,  nerves,  and  muscles,  the  bulb,  and  adjacent  part 
of  the  urethra.  Owing  to  this  space  being  closed  behind  and  open  in  front,  and  to 
its  containing  the  above  structures,  fluids  extravasated  within  this  space  will 
obviously  tend  to  make  their  way  forwards  into  the  scrotum,  penis,  and  lower  part 
of  the  al)dominal  wall.  * 

The  urethra. — This  can  be  examined  in  part  with  the  finger,  but  much  better 
with  the  aid  of  a  sound.  The  anterior,  or  penile,  part  is  movable;  the  posterior, 
or  deeper,  more  fixed.  It  is  narrowest  at  the  meatus  and  where  the  membranous 
urethra  passes  through  the  triangular  ligament.     It  is  widest  in  the  prostatic  part 

Fig.  692. — Deep  Dissection  of  Male  Perinjcum.     (Roser.) 

The  bulb  is  slightly  raised  and  the  rectum  drawn  backwards,  in  order  to  make  clear  the 
membranous  urethra  and  prostate,  which  are  shown  incised  as  in  the  lateral  operation  of 
lithotomy. 


Erector  pems^ 


Wilson's  m 

URETHRA  DIVIDED  A- 
THE  LATERAL  INCi- 

Artery  to  bulb  (abnorma! 

PROSTATE  GLAND,  WITH  ITS  — 
PLEXUS  OF  VESSELS 
S'iperficial  perinceal 

artery 
Levantor  aril,  its 
anterior  fibres  raised 
to  show  the  prostate 


Gluteus  maxim 


'imlinuation  of  internal 

piidir  artery 
^  Anterior  layer  of 
"    triangular  ligament 

1  /  tery  to  bulb 

-COWPER'S  GLAND 


INCISION  IN  THE  PROSTATE 
GLAND  AS  IN  THE  LATERAL 

OPERATION 
-TransversuB  perinaei 
muscle 


-  Trunk  oj  internal  pudic 

^RECTUM 

.External  sphincter 


and  the  fossa  navicularis.  One  of  the  most  important  landmarks  is  the  triangular 
ligament,  the  base  of  which  can  just  be  felt  in  a  thin  perinseum.  The  meml)ranous 
urethra  passes  through  this,  about  three-quarters  of  an  inch  above  the  central  jioint 
of  the  perina^um,  about  the  same  distance  below  the  subpubic  ligament,  or  an  inch 
below  the  symphysis.  Above  the  urethra  run  the  dorsal  vessels  and  nerves  of  the 
penis.  The  fixation,  undilatability,  surrounding  muscular  fibres,  and  close  neigh- 
bourhood of  a  large  amount  of  erectile  tissue  (the  bulb),  all  account  for  difficulties 
in  introducing  instruments  past  this  point.  It  is  here  also  that  the  urethra  is  most 
liable  to  be  damaged  by  a  fall  or  blow.  The  attachment  of  the  deep  layer  of 
superficial  fascia  to  the  base  of  the  triangular  ligament  accounts  for  the  fact  that 
urine  extravasated  from  a  ruptured  urethra,  or  through  an  opening  behind  a 
stricture,  passes  usually  not  backwards  into  the  anal  triangle,  but  forwards  into 
the  scrotum  and  abdominal  wall.  The  other  structures  in  relation  with  the  trian- 
gular ligament  are  shown  in  fig.  693. 


THE  MALE  PERINEUM 


1125 


Fig.  693. — The  Aktkries  ok  the  Perinjeum. 

On  the  rif^lit  side  of  the  periiUL-um  (left  .side  of  this  fijiiire)  Colles'.s  fascia  has  been  turned  back 
to  sliow  the  superficial  vessels.  On  the  left  side  the  superficial  vessels  have  been  cut  away  with  the 
anterior  layer  of  tlie  triangular  ligament  to  show  the  deep  ves.sels. 


Superficial  perinaal  vessels 


Accelerator  urinse 


CoUes'B  fascia,  turned  back 


Erector  penis 

TYansverse  perinceal  vessel.i 

Cut  edge  of  triangular 

ligament 

SUPERFICIA  L  PERiy.EA  L 

XERVE  GIVISG  OFF 

TRANS  VERSE  BRANCH 

Pudic  vessels 

Inferior  h(emorrhoidal  vessels 
and  nerves 


Dorsal  arlery  of  penis 
Artery  of  crits 


Great  sciatic  ligament 
Levator  ani 
External  sphincter 

Gluteus  maximus 


Fig.  G94. — Sagittal  Section  of  Male  Pelvls  in  the  Mesial  Line.     (One-third. 

(Brauue.) 


SYMPHYSIS  PUBIS 


POUCH  OF  DOUGUS 

RECTUM 

FOLD  OF  HOUSTON 


-  VESICUU  SEMINAUS 


DUCTUS  EJACUUTORIUS 
PROSTATE 

External  sphincter 
>  Internal  sphincter 

External  sphincter 


1126 


SURGICAL  AXD  TOPOGRAPHICAL  AX  ATOMY 


The  prostate  (figs.  692  and  694). — The  ivlations  of  this  important  organ 
should  be  studied,  whenever  possible,  with  the  finger  and  sound.  Koughly  eonii»ar- 
able  to  a  chestnut  in  form,  size,  and  dimensions,  its  base,  situated  below  the  neck 
of  the  l)ladder,  blends  by  its  muscular  tissue  with  this  organ.  As  the  long  axis  of 
the  })rostate  is  very  obli(iue,  the  base  will  be  directed  upwards  and  backwards  (fig. 
694).  The  apex,  resting  against  the  upper  or  deeper  layer  of  the  triangular  liga- 
ment, lies  about  half  an  inch  behind  the  sul)pubic  angle.  This  part  of  the  organ 
can  be  detected  by  the  finger  about  one  and  a  half  inches  above  the  anal  orifice, 
through  the  anterior  wall  of  the  rectum.  Continuous  Avith  tliis.  and  a  little  higher 
up,  the  posterior  surface  can  also  be  made  out  througli  the  second  part  of  the 
bowel.  The  anterior  surface  receives  the  pul>o-prostatic  ligaments,  and  on  this 
surface  lies  the  greater  part  of  the  prostatic  plexus  (fig.  696).  The  lateral  margins 
of  the  gland  are  embraced  b}'  the  anterior  borders  of  the  levatores  ani.  The  urethra, 
in  its  course  through  the  organ  from  base  to  apex  in  the  middle  line,  lies  rather 
nearer  to  the  anterior  than  the  posterior  surface.  The  ejaculatory  ducts,  as  they 
pass  obliquely  through  the  prostate  to  open  at  the  margins  of  the  sinus  i^ocularis, 
mark  off  a  portion  of  the  gland  which  lies  between  each  duct  lielow  and  the  neck 
of  the  bladder  above  (fig.   694).     It  is  obvious  tliat,  if  this  portion  be  enlarged, 


Fig.  690. — Scheme  of  the  Pidic  Artery  axp  its  Branches. 


Subpubic  ligament  with  aperture  for 
dorsal  vein  of  the  penis 

Apertures  for  dorsal  nrlery  and  ( 
nerve  of  the  penis  \ 


Crus  penis 
Aperture  for  artery  of  cur  pas 
carernosum 
Superficial  triangular  ligament 
lachio-eavernosuB,  or  erector  penis 
Aperture  for  artery 
to  bulb 
Urethral  aperture 
Aperture  for  Cow- 
per's  duet 
Position  of  bulb 


Apertures  for  super- 
ficial perinceal 
vessels  and  nerve 


Fascia  of  Colles, 
turned  backwards 


DORSAL  NERVE 

.r^—.  Anterior  layer  of  triangular 
"%  ligament 

-S-  Dursal  artery  of  penis 

Vi Deep  triangu- 
lar ligament 
Artery  of  curjius 
cavernosuin 

A  riery  to  bulb 

iidic  veins 
DORSAL  NERVE 

POSITION  OF  COWPER'S 
GLAND 

Internal  pudic  artery 


Posterior  border  of 
perinaeal  ledge 
'junction  of  trian- 
gular ligaments 
with  fascia  of 
Collesj 


obstruction  to  the  escape  of  urine  from  the  bladder  nuist  follow.  Up  to  puberty, 
the  prostate  is  imperceptible  per  rectum.  In  adolescence  the  organ,  while  to  be 
felt,  is  softer  and  more  rounded,  and  lacks  the  character  and  shape  which  distinguish 
the  organ  in  adult  life.  The  capsule  (fig.  696)  of  the  organ  must  be  rememl)cred. 
It  is  formed  l)y  a  layer  from  the  recto-vesical  fascia,  and  under  it,  es]iecially  on  its 
anterior  and  lateral  asi)ects  (fig.  696),  lies  the  jn-ostatic  plexus,  formed  chiefly  by 
the  breaking  up  of  the  dorsal  vein  of  the  penis. 

The  continuity  of  the  above  sheath  of  the  i)rostate  with  the  recto-vesical  fascia 
on  the  upper  surface  of  the  levator  ani  and  the  sides  of  the  bladder  forms  the  roof 
of  the  perinaeum  and  part  of  the  floor  of  the  pelvis.  If  by  mistake  an  incision,  as 
in  lithotomy,  is  carried  through  this  prostatic  sheath,  the  cavities  of  the  pelvis  Avill 
l)e  opened  and  extravasation  of  fluids  into  the  connective  tissue,  which  everywhere 
follinvs  the  layers  of  ])elvic  fascia,  will  follt)w.  Before  leaving  the  relations  of  the 
prostate,  the  render  should  consider  the  layers  which  will  be  met  with  in 
cutting  down  to  this  organ  from  the  surface.  The  f(»llo\\ing  fascia'  and  mus- 
cular layers  will  be  met  with  alternately  (Cunningham):  (1)  Skin  and  superiicial 
fascia;  (2)  fascia  of  Colles;  (3)  superficial  perina-al  muscles;  (4)  superficial  layer 
of  triangular  ligament;   (5)  compressor  uretln-a';   (6)  deep  layer  of  triangular  liga- 


ANUS— RECTUM 


112< 


ment;  (7)  levator  ani;  (8)  capsule  of  prostate.  Furtlicr.  these  fasciie  of  the  urethral 
triangle  (p.  1128)  are  so  arranged  as  to  form  a  superficial  deep  compartment, 
and  within  one  or  other  of  these  all  the  structures  of  this  most  inij.oriant  (Hvisioii 
of  the  perinteum  are  found.  Thus  the  superficial  compartment  is  hounded,  in 
front,  hy  the  fascia  of  Colics;  behind,  by  the  triangular  ligauient;  laterally,  Ijy 
the  attachment  of  these  to  the  margins  of  the  pubic  arch;  and,  l)ehind.  by  the 
blending  of  the  fascia  of  Colles  with  the  base  of  the  triangular  ligament.  The  c(tn- 
tents  of  this  compartment  are  given  elsewhere.  The  deeper  compartment  is  the 
interval  between  the  two  layers  of  the  triangular  ligament. 

Ischio-rectal  fossa. — Most  of  the  Itoundaries  of  this  space  (p.  1063)  can  be 
made  out  with  the  linger  in  a  tiiin  subject.  The  loose,  j)Oorly  vitalised  fat  which 
occupies  it,  the  dependent  position  of  the  i>art,  its  terminal  blood-supply,  its  expo- 
sure to  cold  and  damp,  and  the  close  vicinity  of  decomposing  ficces,  all  account  for 
the  frequency  of  abscess  here.  The  position  of  the  pudic  vessels  and  nerve  in  their 
sheath  of  obturator  fascia,  on  the  outer  wall,  aV)0ut  an  inch  and  a  half  above  the 
lower  margin  of  the  tuber  ischii,  must  be  remem])ered. 


Fig.  696. 


-Section  showixo  the  Isc.'hio  rectal  Fossa  ix  its  Relations  to  the 
Pelvic  Visceea. 


Levator  ani  v^ith  recto-vesioal 
and  iBchio-rectal  fasciae 


Obturator  internus 


I/ilenial  pudic  vessels  and 
XER  VES  in  ob/iirnlor  fusein 
TUBER  ISCHII 
Ischio-rectal  foasa  with  its 
anterior  and  t>08terior  ex- 
tensions 

Gluteus  mazimuB 


SYMPHVSIS  PUBIS 


Pubo-proBtatic  ligaments 
Proxlatic  plexus 

PROSTATE 

Capsule  of  prostate  formed 

by  recto-vesical  fascia 
Fat 


RECTUM  INVESTED  BY  RECTO- 
VESICAL FASCIA 


Anus. — The  tightly  closeel  (condition  of  this  oriliee  in  health  and  the  puekering 
of  the  skin  around,  due  to  the  sphincter  and  corrugator  cutis  ani,  are  characteristic. 
Dilated  veins,  external  piles,  or  tags  of  skin  resulting  from  the  shrinking  of  these, 
are  also  common.  A  white  line,  varying  in  distinctness  in  different  subjects, 
marks  the  junction  of  the  skin,  and  mucous  membrane,  and  the  interval  lietween 
the  external  and  internal  sphincters  .(Hilton).  Amongst  the  numerous  folds 
about  the  anal  orifice,  a  fissure  or  ulcer  may  be  hidden,  esjtecially  on  the  coccygeal 
aspect;  the  alumdant  nerve-supply  to  this  region  and  the  large  distribution  of  the 
])udic  nerve  to  the  genitals,  and  the  junction  of  this  nerve  with  other  branches  of 
the  sacral  plexus,  explain  the  acuteness  of  the  suft'ering,  and  its  wide  distril)Ution 
in  these  afifections  (Hilton). 

Rectum. — The  following  points  can  be  made  out  by  the  finger  introduced  here: 
(1)  The  thickened,  roll-like  feel  of  a  contracted  external  sphincter;  (2)  tlie  narrower, 
more  expanded,  internal  sphincter  extending  upwards  for  an  inch  from  this;  (3) 
the  condition  of  the  iseliio-rectal  fossa?  on  either  side;  (4)  the  membranous  urethra 
in  front,  especially  if  a  staff  has  been  introduced;  (5)  just  beyond  the  si)hincters, 
or  an  inch  and  a  half  within  the  anus,  lies  the  prostate:  (6)  converging  towards 
the  base  of  the  prostate,  and  forming  the  sides  of  the  triangular  space,  are  the  vesi- 


1128 


SURGICAL  AXD  TOPOGRAPHICAL  AXATOMY 


culse  seminales  and  ejaculatorv  ducts.  These  can  rarely  l)e  felt  unless  diseased 
and  enlarged;  (7)  it  is  within  this  triangular  space  that  a  distended  bladder  can  be 
felt,  and,  if  the  prostate  is  not  enlarged,  punctured,  the  trocar  being  driven  in  the 
direction  of  the  long  axis  of  the  distended  viscus,  i.e.  towards  the  umbilicus.  As 
a  rule,  the  recto-vesical  pouch  is  reflected  at  a  distance  of  three  and  a  half  or  even 
four  inches  (87  to  100  mm.)  from  the  anus.  In  the  female  the  distance  is  only 
tliree  inches,  or  even  less.  (8)  Sometimes  the  lowest  of  the  folds  of  Houston,  on 
al)()ut  the  same  level  as  the  prostate,  semilunar  in  form  and  about  half  an  inch  in 
width,  can  be  made  out  (fig.  694). 

The  position  of  this  and  the  other  two  folds  of  Houston  should  be  remembered, 
as  their  presence,  if  well  developed  and  if  the  liowel  be  empty,  may  interfere  with 
the  passage  of  instruments. 

In  addition  to  the  structures  which  can  be  felt,  those  which  can  be  seen 
with  a  speculum,  especially  if  the  body  be  seen  in  the  semiprone  or  genu- 
pectoral  position,  must  l)e  noted.  Starting  from  immediately  within  the  anus  are 
some  six  or  eight  vertical  folds  of  mucous  membrane,  the  columns  of  Glisson. 


Fig.  697. — Diagram  of  the  Pelvic  Fascle. 


Transversalis  fascia 


Obturator  fascia 

'  White  line' 

Becto-vesical  fascia 


Obturator  fascia 
Ischio-rectal  fascia 


Aleoek's  canal  writh 
pudic  vessels 


Abdominal  muscles 


Psoas 

BORDER  OF  ACETABULUM 


Apex  of  isehio-rectaf 
fossa 

Levator  ani 

ISCHIAL  TUBEROSITY 

Sphincter  ani 


Between  these  columns  lie  little  pockets  or  lacunae,  the  sinuses  of  Morgagni,  just 
above  the  external  sphincter.  In  the  above-mentioned  columns  the  hasmorrhoidal 
vessels  ascend  and  descend,  intercommunicating  l^y  numerous  transverse  branches. 
The  above  examination  refers  chiefly  to_  the  male.  It  remains  to  refer  to  rectal 
examination  in  the  female.  Anteriorly,  the  soft  perinatal  body  and  recto- 
vaginal septum  will  be  met  with,  and,  through  the  latter,  the  cervix  and  os  uteri, 
and,  higher  up,  the  lower  part  of  the  cervix  uteri.  ]More  laterally  tlie  ovaries  may 
be  felt,  but  the  Fallopian  tubes,  unless  enlarged  and  thickened,  are  not  to  be  made 
out.  The  student  should  he  familiar  with  the  feel  of  a  healthy  recto-uterine  or 
recto-vesical  pouch,  according  to  the  sex,  and  the  coils  of  intestine  which  it  may 
contain,  so  as  to  be  able  to  contrast  this  with  any  collection  of  inflammatory  or 
other  fluid  or  mischief  descending  from  the  upper  pelvis,  e.g.  from  the  vermiform 
ap]iendix.  Posteriorly,  certain  structures  are  met  with  in  either  sex.  After  a  very 
short  interval  (sphincter  and  ano-coccygeal  body),  the  finger  reaches  the  tip  of  the 
coccyx  and  explores  the  hollow  of  the  sacrum.  On  each  side  is  the  ischial  tuber- 
osity and  wall  of  the  true  }ielvis.     The  finger,  hooked  outwards  and  ujiwards,  comes 


FEMALE   fiEXfTAL    ORGAXS 


1129 


on  the  border  of  the  fakiforiu  jjiocess  of  the  great  sacro-sciatic  ligament  passing 
between  the  altove-mcntioned  bones. 

The  pelvic  fascia  and  its  chief  hiyers  are  shown  in  fig.  GOT.  These  are 
described  at  page  1060.  The  following  main  points  will  readily  be  seen:  That 
the  fascia  has  one  important  aspect  towards  the  pelvic,  and  another  towards  the 
ischio-rectal  fossa  and  periiiieum,  and  thus  may  be  interfered  with  during  opera- 
tions, or  affected  by  inflammation  arising  in  either  region.  That  its  numerous 
processes  and  sheaths,  while  tiiey  serve  to  isolate  different  structures,  are  continu- 
ous, and  that  thus  septic  mischief  may,  as  in  the  neck,  sjiread  most  widely.  With 
this  fact  go  two  other  points:  one,  that  with  the  ])lanes  of  this  fascia  run  layers  of 
connective  tissue;  the  other,  that  in  the  spaces  tightly  girt  by  this  fascia  lie  large 
venous  plexuses,  e.g.  vesical,  hiemorrhoidal,  i)r(;static.  and,  if  se])tic  mischief 
reach  these  plexuses,  it  is  out  of  reach  of  surgical  treatment.  The  closeness  of  the 
fascia  to  the  hip-joint  will  also  be  seen.  In  children  with  a  thin  acetabulum  and 
hi{)  disease  this  fascia  becomes  much  thickened,  thus  shutting  off  the  pelvic  cavity 
from  supj)uration  in  the  joint. 


FEMALE   EXTERNAL  GENITALS 

Under  the  above  heading  are  included,  for  convenience  sake,  the  hxhia  majora 
and  minora  at  the  sides;  and,  in  the  middle  line,  from  above  downwards: — (1)  The 
glans  clitoridis  with  its  prepuce;  (2)  the  vestibule;  (3j  the  urethral  orifice;  (4)  the 

Fig.  698. — Diagrammatic  Rkprksextatiox  ok  the  Peri.v.kal  Stkictt'res 

IX  the  Female. 


ISCHIO-PUBIC  ARCH 


CRUS  CLITORIDIS  WITH 
ISCHIO-CAVERNOSUS 


BULBO-CAVERNOSUS 
COVERING  BULBUS 
VESTIBUU 


Superficial  trian- 
gular ligament 


GLANS  CLITORIDIS 
WITH  PREPUCE 


PARS  INTERMEDIAL  3 


Mucous  membrane 
of  vestibule 


MEATUS  URINAR'-JS 


BULBUS  VESTlBULI 


_  GUND  OF  BARTHQLN 


Sphincter  act 


vaginal  orifice  with  the  hymen  or  its  remains;  (5)  the  fossa  navicularis;  (G)  the 
fourchette;  (7)  the  skin  over  the  base  of  the  perina?al  body. 

These  parts  have  l)een  described  elsewhere,  and  only  those  points  which  are  of 
importance  in  a  clinical  examination  will  be  alluded  to  here. 

The  labia  majora  are  two  thick  folds  of  skin,  covered  with  hair  on  their  outer 
surface,  especially  above  where  they  unite  (antirior  roij}mis.-<ure)  in  the  mons 
Veneris.  They  contain  fat,  vessels,  and  dartos,  but  become  rajndly  thinner  l>elow. 
where  thev  are  continuous  mtli  the  fourcliette  in  front  of  the  perinannu  (their 
posterior  commissure ). 

When  the  above  folds  are  drawn  aside,  the  labia  minora,  or  nymphae,  a])]>ear. 


1130 


SURGICAL  AXD  TOPOGRAPHICAL  AXATOMY 


not  projecting,  in  a  healthy  adiiU,  beyond  the  labia  majora.  They  are  small  folds 
of  skin,  which  meet  al)ove  in  the  prepuce  of  the  clitoris,  and  below  blend  with  the 
labia  majora  about  their  centre. 

The  glans  clitoridis,  covered  by  its  prepuce,  occupies  the  middle  line  above. 

Below  it  comes  the  vestibule,  a  triangular  smooth  surface  of  mucous  membrane, 
bounded  above  by  the  clitoris,  below  by  .the  upper  margin  of  the  vaginal  orifice,  and 
laterally  by  the  labia  minora.  In  the  middle  line  of  the  vestibule  and  towards  its 
lower  part,  about  half  an  inch  (12  mm.)  below  the  glans  clitoridis,  and  an  inch  (25 
mm.)  above  the  fourclu'tte,  is  the  meatus  or  opening  of  the  urethra  (figs.  G98,  699). 

The  vaginal  orifice  lies  in  the  middle  line  between  the  base  of  the  vestibule 


Fig.  699. — Section  of  the  Female  Pelvis.     (After  Henle.) 


VESICAL  WALL 

CAVITY  OF  BLADDER 

Prevesical  fat 


Deep   transver- 
Bus  perinaei 


LABIUM  MAJUS 
Unetriped  muscular  fibre 


URETHFA 
LABIUM  MINUS 
UuBtriped  muscular  fibre     '        I'essi-ls 
VAGINAL  ORIFICE 


ANUS 
Internal  sphincter  ani 
Part  of  external  sphincter  ani 


RECTUM 

COCCYX 

Recto-cocey- 
geal  muscle 

POSTERIOR  LIP  OF  OS 

UTERI 
ANTERIOR  LIP 

VAGINA 

External 
sphincter  ani 

Internal 
sphincter  ani 


above,  and  the  fossa  navicularis  below.  Its  orifice  is  partially  closed  in  the  virgin 
by  a  fold  of  mucous  membrane,  the  hymen  (fig.  631 ).  This  is  usually  crescentic  in 
shape,  attached  below  to  the  posterior  margin  of  the  vaginal  orifice,  and  with  a  free 
edge  toAvards  the  base  of  the  vestibule.  In  some  cases  it  is  diaphragmatic,  i.e. 
attached  all  around,  but  perforated  in  the  centre  (fig.  698). 

The  shrivelled  remains  of  the  hymen  ])robably  constitute  the  carunculae 
myrtiformes.  On  either  side  of  the  vaginal  orifice,  at  its  lower  ])avt.  he  the 
racemose,  muciparous  glands  of  Bartholin,  situated  beneath  tlie  sujierficial  ])erina>al 
fascia  and  sphincter  vaginae.  Their  ducts  run  slightly  ui)wards  and  open,  external 
to  the  attachment  of  the  hymen,  Avithin  the  labia  minora. 

Fourchette  and  fossa  navicularis. — The  fourchette,  as  stated  above,  is  the 
lower  commissure  of  the  labia  majora.     Normally  the  inner  aspect  of  this  is  in 


PARTS  CONCERNED  IN  INGUINAL  HERNIA  1131 

contact  with  the  lower  surface  of  the  hymen.  \\'hen  the  fourdiette  is  i)ullcil  down 
by  the  finger,  a  shallow'  depression  is  seen,  the  fossa  navicularis,  with  tin-  I'our- 
chette  for  its  ])osterior,  and  tiie  hymen  for  its  anterior  houndary. 

Examination  per  vaginam. — The  finger,  introduced  past  the  gluteal  cleft, 
perinjeuni,  and  fourchetle,  comes  \\\m\\  the  elliptical  orilice  of  the  vagina,  and  notes 
how  far  it  is  patulous  or  narrow;  the  ])resence  or  otlu-rwise  of  any  spasm  from  the 
adjacent  muscles;  then,  passing  into  the  canal  itself,  the  ]iresence  or  absence  of 
rugte,  a  naturally  moist,  or  a  dry  condition  are  observt-d.  In  the  anterior  wall  the 
cord-like  track  of  the  urethra  can  l)e  detected;  and  further  up  than  this,  if  a  sound 
be  j)assed,  the  posterior  wall  of  the  bladder.  The  anterior  wall  of  the  vagina  is  two 
to  two  and  a  half  inches  long.  The  posterior  wall,  three  inches  long,  forms  the 
recto-vaginal  septum,  and  through  it  any  fieces  present  in  the  lx)wel  are  easily  felt. 
The  cervix  uteri  is  next  felt  for  in  tlie  roof  of  the  vagina,  projecting  downwards  and 
backwards  in  a  line  drawn  from  the  umbilicus  to  the  coccyx.  Besides  its  direction, 
its  size,  shape,  mobility,  and  consistence  should  be  noted.  The  os  uteri  should  form 
a  dimi)le  or  hssure  in  the  centre  of  the  cervix.  Of  its  two  lips  the  posterior  is  the 
thicker  and  more  fleshy  feeling  of  the  two.  The  vaginal  culs-de-sac  or  fornices  are 
next  explored.  These  should  l)e  soft  and  elastic,  giving  an  impression  to  the  finger 
similar  to  that  when  it  is  introduced  into  the  angles  of  the  mouth.  Any  resistance 
felt  here  may  he  due  to  scars,  swellings  connected  with  the  uterus  (displacements,  or 
myomata),  effusions  of  blood  or  inflammatory  material,  and,  in  the  case  of  the 
lateral  culs-de-sac,  a  displaced  or  enlarged  ovary,  or  dilatations  of  the  Falloiiian 
tubes. 


HERNIA 

PARTS   CONCERNED   IN   INGUINAL   HERNIA 

In  inguinal  hernia,  as  in  femoral  and  umbilical,  there  is  a  weak  spot  in  the 
abdominal  wall — one  weakened  for  the  needful  passage  of  the  testicle  from  within 
to  outside  the  abdomen.  The  parts  immediately  concerned  are  the  two  abdominal 
rings,  external  and  internal,  and  the  canal.  Now,  it  must  be  remembered  at  the 
outset  that  the  rings  and  canal  are  only  potential — they  do  not  exist  as  rings  or 
canal  save  when  opened  up  by  a  hernia,  or  when  so  made  by  the  scalpel.  The 
canal  is  merely  an  ol)lique  slit  or  fiat-sided  passage.  The  external  and  internal 
rings  are  so  intimately  l)lended  with  the  structures  that  pass  through  them,  and  so 
filled  by  them,  that  they  are  potential  rings  only. 

EXTERNAL  RING. — This  is  usually  described  as  a  ring:  it  is  really  only  a 
separation  or  gap  in  the  aponeurosis  of  the  external  oblique,  by  which  in  the  male 
the  testicle  and  cord,  and  in  the  female  the  round  ligament  by  which  the  uterus  is 
kei)t  tilted  a  little  forwards,  pass  out  from  the  al)domen.  The  size  of  this  opening, 
the  development  and  strengtli  of  its  sides  or  pillars,  the  fascia  closing  the  ring — all 
vary  extremely.  Formation  :  by  divergence  of  two  fa.^ciculi  of  the  external  oblicjue 
aponeurosis.  Boundaries  :  two  pillars — (1)  Internal,  the  smaller,  attached  to  tlie 
symphysis  and  blending  with  the  suspensory  ligament  of  the  penis;  (2)  external, 
stronger,  attached  to  the  ]iubic  spine  and  blending  with  Pou]tart's  ligament,  and  so 
with  the  fascia  lata.  On  this  outer,  stronger  pillar  rests  th(;  cord  (and  so  the  weight 
of  the  testicle),  or  round  ligament.  Shape  :  triangular  or  elliptical,  with  the  base 
downwards  and  inwards  towards  the  jmliie  crest. 

Intercolumnar  fascia.  External  spermatic  fascia. — This,  derived  from  the 
lower  part  of  the  ai)oneurosis  of  the  external  oblitpie,  ties  th«'  two  ))illars  together, 
and,  l)eing  continuiMl  over  the  cord,  prevents  there  l)eing  any  ring  here,  unless 
made  with  a  scal})cl.  This  is  the  rule  in  the  l)ody:  when  any  structure  passes 
throutih  an  opening  in  a  rtl)rous  or  nuiscular  layer,  it  carries  with  it  a  coating 
of   tissue  from   that    layer;    e.g.    the  inferior  cava   passing  through   the  foramen 


1132 


SURGICAL  AND   TOPOGRAPHICAL  A^ATOMY 


quadratum  in  the  diaphragm,  and  the  membranous  urethra  through  the  triangular 
hgament. 

Effect  of  position  of  the  thigh  on  the  ring. — As  the  lower  pillar  is  blended 
with  Poupart's  ligament,  and  as  the  fascia  lata  is  connected  with  this,  movements 
of  the  thigh  will  aifect  tlie  ring  much,  making  it  tighter  or  looser.  Thus  extension 
and  abduction  of  the  thigh  stretch  the  pillars  and  close  the  ring.  In  llexion  and 
adduction  of  the  thigh  the  pillars  are  relaxed;  and  this  is  the  position  in  which 
reduction  of  a  hernia  is  attempted.  In  flexion  and  aV)duction  of  the  thigh,  the  ring 
is  open;  and  this  is  the  position  in  Avhich  a  patient  should  sit,  to  try  on  a  truss, 
and  cough.     If  the  hernia  is  now  kept  up,  the  truss  is  satisfactory. 

Helping  to  protect  this  most  important  spot,  and  preventing  its  being  more  than 
a  potential  ring,  are  not  only  the  two  pillars,  and  the  intercolumnar  fascia,  but  also 


Fig.  700. —The  Parts  coxcerxed  ix  Ixguixal  Herxia. 
(From  a  dissection  in  the  Hunterian  Museum.) 

External  oblique,  cut  and  turned  back  Internal  oblique  External  oblique 


Trausveraalia 


Fascia 

transveraalia 


Common  femoral 
vessels 


Triangular  fascia 


a  structure  which  has  been  called  a  third  or  posterior  pillar,  namely,  the  triangular 
fascia.  This  has  its  base  above  at  the  lower  part  of  the  linea  alba,  where  it  joins 
its  fellow  and  the  aponeurosis  of  the  external  oblique,  and  its  apex  downwards  and 
outwards,  where,  having  passed  behind  the  internal  pillar,  it  blends  with  Gimber- 
nat's  ligament.  Again,  the  conjoined  tendon  of  the  internal  oblique  and  trans- 
versalis  curving  inwards  and  downwards  to  be  attached  to  the  ilio-pectineal  line 
and  spine  is  a  most  powerful  protection,  behind,  to  what  is  otherwise  a  weak  spot 
and  a  potent ial  ring. 

INGUINAL  CANAL. — Tliis  is  not  a  canal  in  the  usual  sense,  Init  a  chink  or  flat- 
sided  passage  in  the  thickness  of  the  alxlominal  wall.  Tlie  descriptions  of  the 
canal  usually  given  apply  rather  to  the  diseased  than  to  the  healthy  state.  It  was 
a  canal  once,  and  for  a  time  only,  i.e.  in  the  later  months  of  fn^al  life.  It  remains 
weak  for  a  long  time  after,  but  only  a  vestige  of  it  remains  in  the  well-made  adult. 
On  the  inner  surface  of   the    abdomen  we    have    a   few  inconspicuous  inguinal 


INGUINAL   HERNIA 


1133 


fossettes;  on  the  outer  surface  a  separation  between  the  fasciculi  of  the  external 
oblique,  carefully  closed  and  protected;  in  the  interval  between  the  two  surfaces 
lies  the  cord  or  round  ligament,  in  the  thickness  f)f  tlie  abdominal  wall. 

Length. — In  very  early  life  there  is  no  canal;  one  ring  lies  directly  behind  tlie 
other,  so  as  to  facilitate  tiie  easy  passage  of  tin;  testis.  In  the  aduH  it  measures 
about  an  inch  and  a  half  (37  nnn.)  in  leiigtli.  tliis  lengthening  being  brought  al)out 
by  the  growth  and  separation  of  the  ahe  of  the  pelvis.  This  increased  obli(|uity 
gives  acMitional  safety. 

Direction, — Froni  internal  to  external  ring,  downwards,  forwards,  and  in- 
wards. 

Boundaries. — For  convenience  sake,  certain  limits  (largely  artificial)  have 
been  nanieil — 

(1)   Floor. — This  is  best  marked  near  the  outlet,  where  the  cord  rests  on  the 


Fig.  701. — Dissiccriox  of  Inguinal  Canal.     (Wood.) 


Ext.  oblique 
(turned  down' 


Rectus  abdominis 
iwith  sheath  opcned> 


Int.  oblique 


Transversalis 


Conjoined  tendou 
Triangular  fascia 
Cremaster 


grooved  upper  margin  of  Poupart's  ligament.     The  meeting  of  the  transversalis 
fascia  with  this  ligament  forms  the  floor. 

(2)  Roof. — The  apposition  of  the  muscles  and  the  arched  border  of  the  internal 
oblique  and  transversalis. 

(3)  Anterior  icall. — Skin,  superficial  fascia,  external  oblicjue  for  all  the  way. 
Internal  oblique,  i.e.  that  })art  arising  from  Poupart's  ligament,  for  the  outer  third 
or  so. 

{4)Posterior  uall. — For  the  whole  extent,  transversalis  fascia,  extra-peritoneal 
tissue,  and  peritoneum.  For  the  inner  two-thirds,  conjoined  tendon  of  internal 
oblique  and  transversalis,  and  tlie  outer  edge  of  the  triangular  fasiia,  when  devel- 
oped. Of  the  structures  forming  the  posterior  wall,  tlie  transversalis  fascia  is 
the  strongest.  It  is  thicker  and  better  marked  at  its  attachments  below;  these  are 
— (n)  externally,  to  inner  lip  of  iliac  crest;  (b)  to  Poupart's  ligament  between  the 
anterior  su})erior  spine  and  the  femoral  vessels:  here  it  joins  the  fascia  iliaca;   (r) 


1134 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


opposite  the  femoral  vessels  it  also  joins  the  fascia  iliaca,  and  forms  with  it  a 
funnel-shaped  sheath;  {d)  internal  to  the  femoral  vessels  the  fascia  transversalis  is 
attached  to  the  ilio-pectineal  line,  behind  the  conjoined  tendon,  with  which  it 
blends. 

INTERNAL  RING. — It  has  already  been  said  that  the  term  '  ring'  is  here  mis- 
applied except  in  an  artificial  sense,  as  when  an  opening  is  made  by  a  scalpel;  or 
in  a  i)athological  one,  as  when  a  hernia  is  making  its  way  by  opening  nj)  the  parts. 
The  terms  '  internal '  and  '  external '  are  also  misap]jlied  as  far  a-s  their  usual  a})})li- 
cation  to  the  middle  line  of  the  body  is  concerned.  The  terms  apply  to  depth  only. 
The  '  internal  ring '  is  not  a  ring  in  the  least,  but  merely  a  funnel-shaped  expansion 
of  the  transversalis  fascia,  which  the  cord  carries  on  with  it  as  it  escapes  from  the 
abdomen.  This  expansion  may  be  Aveakened,  but  it  is  never  an  opening  save  when 
made  so  artificially. 

Site. — ^Midway  between  the  anterior  superior  s^iine  and  spine  of  pubes.   Shape  : 


Fig.  702. 


-Dissection  of  the  Lower  Part  of  the  Abdominal  Wall  from  within, 
THE  Peritoneum  having  been  removed.     (Wood.) 


Fascia  trans- 
versalis 

Epigastric  artery- 


Internal  abdom-_ 
inal  ring 

VAS  DEFERENS >w\\ 

Spermatic \ 

vessels  ^ 


Border  of  the 
posterior  part 
of  the  sheath 
of  the  rectus 
(fold  of  Doug- 
las) 

Posterior  surface 
of  rectus 


Conjoined  tendon 
in  the  triangle 
of  Hesselbach 

Obhlrralfd  h>/j,n- 
gasti  ic  arterii 

Lymphatics  in 
crural  rings 


EilTnal  iliac  artery 


oval,  with  the  long  diameter  upwards.  Dimensions  :  one  inch  (25  mm.)  by  half 
an  inch.  Both  these  are  artificial.  Boundaries  :  centre  of  Poupart's  ligament, 
about  half  an  inch  below.  Internally,  the  deep  epigastric  artery  (fig.  702);  and 
thus  the  inner  side  seems  to  be  better  defined.  But  the  outer  side  is  really  the  better 
defined,  as  here  the  transversalis  fascia  is  descending  to  Poupart's  ligament,  to  form 
the  deep  '  crural '  arch,  and  to  help  to  close  in  the  great  gap  or  notch  betweini  Pou- 
part's ligament  and  tlie  innominate  bone.  Owing  to  the  artery  lying  to  the  inner 
side,  tlie  incision,  in  cutting  to  relieve  the  deep  constriction  of  an  inguinal  hernia, 
should  always  be  made  directly  upwards,  so  as  to  avoid  the  above  vessel. 
Coverings. — There  are  two  chief  forms  of  inguinal  hernia: — 

A.  The  common  form  :  external,  or  oblique. — External,  Ixx'ause  it  appears 
(at  the  internal  rhig)  external  to  the  deep  epigastric  artery.  Oblique,  because  it 
traverses  the  whole  of  the  inguinal  canal,  entering  it  at  its  inlet  and  leaving  it  at 
its  outlet. 

B.  Rarer  form  :  internal,  or  direct. — Internal,  because  it  appears  internal 


INGUINAL   HERNIA 


ii;j5 


to  the  deep  epigastric  artery.  Direct,  because,  instead  of  making  its  way  down 
the  whole  oblique  canal,  it  conies  by  a  short  cut,  as  it  were,  only  into  the  lower 
part  of  the  canal,  and  then  emerges  by  the  same  opening  as  the  other. 

A.  Oblique,  external  inguinal  hernia. — Tliis  contains  its  coverings  as 
follows: — 

(1)  At  the  internal  ring,  or  inlet,  it  obtains  three: — (a)  Peritoneum;  U>) 
extra-peritoiical  fat;  (c;  inluiidibuliform  faijcia,  or  the  layer  of  transversalis  fascia 
prolonge(l  at  tliis  spot  along  the  cord. 

(2)  In  the  canal  it  obtains  one.  As  it  emerges  beneath  the  lower  l>ord<r  of  the 
internal  (jljlique,  it  gets  some  tibres  from  the  cremaster. 

(3)  At  the  external  ring,  or  outlet,  the  liernia  obtains  three,  viz.:  (a)  Inter- 
colunmar  fascia;  (6)  superiicial  fascia;  and  (c)  skin. 

B.  Direct  or  internal  inguinal  hernia. — This  does  not  come  through  the 
internal  ring,  but,  making  its  way  through  the  posterior  wall  of  the  lower  third  of 
the  canal — i.e.  the  conjoined  tendon,  either  })Ushing  this  forward  or  sjditting  it — 
gets  its  coverings  only  from  structures  in  relation  to  this  part  of  the  canal.  They 
are — (1)    Peritoneum;   (2)  extra-peritoneal  fat;   (3)   transversalis  fascia   (not  the 


Fig.  703.— Veetical  Section  of  Pelvis  passing  through  the  Heads  of  the 
Thigh  Bones.     (Blandin.) 

Deep  epigastric  vesselsy 

\     INNER  BORDER  OF  INGUINAL  CANAL 
Internal  abdominal  ring 


Fascia  iliaca 

Ohiileraled  hijpognstric  artery 

External  iliac  vein 

ILIUM 

VAS  OEfERENS 

CRURAL  CANAL 

Pelvic  fascia 


Obturator  fascia 

'     '  '       RECTUM 

Levator  am/  ischiO-RECTAL  FOSSA 
Kecto-vesical  fascia 


ISTEIiy.iL  PI  Die  VES.SEL.'y  AXD 
y  Eli  YE 


specialised  part  at  the  internal  ring  or  infundibuliform  fascia);  (4;  conjoined 
tendon  of  internal  (jbli(|ue  and  transversalis.  At  the  outlet  of  the  external  ring  the 
coverings  obtained  are  the  same  as  in  the  oblique  hernia,  viz.  (5)  intercolumnar 
fascia;   ((j)  sujx'rticial  fascia;  (7)  skin. 

Hitherto  the  two  forms  of  inguinal  hernia  have  l)een  considered  from  the 
superficial  aspect,  that  in  which  they  an-  met  with  in  jn-actice.  The  inguinal 
region  should  also  be  studied  as  to  the  posterior  aspect  of  its  so-called  rings  and 
canal,  as  these  have  to  bear  the  early  stn  ss  of  a  commencing  hernia.  It  is  against 
this  aspect  that  a  piece  of  omentum  or  intestine  is  constantly  and  insidiously 
pressing,  and  endeavouring  to  make  its  way  out.  Furtliermore.  when  either  of  tiie 
above  constituents  of  hernia  have  made  their  way  a  little  farther,  and  got  out  into 
the  internal  ring  or  into  the  canal,  the  ])atient  is  no  longer  sound. 

On  the  posterior  wall  are  certain  conls  and  dejtressions,  marking  off  regions 
which  correspond  to  tliose  on  the  surface. 

Tlius,  there  are  three  prominent  cords,  and  three  fossae. 

Three  cords — ( 1 )  Median,  or  urachus  ;  (2)  lateral,  or  tlie  obliterated  hypo- 
gastric arteries. 


1136  SURGICAL  AND   TOPOGRAPHICAL  AXATOMY 

(1)  Median,  or  urachus;  This  interesting  fa?tal  relic,  the  intra-abdominal  part 
of  the  allantois,  passes  up  between  the  apex  of  the  bladder  and  the  umbilicus,  and 
by  so  doing — (a)  keej^s  the  bladder  up,  especially  in  early  life,  when  the  pelvic 
cavity  is  but  little  developed;  (6)  it  keeps  the  bladder  well  up  so  that  it  shall  be 
above  the  level  of  the  urethra,  and  so  more  easily  enii)tied;  (c)  it  provides,  by  thus 
keeping  up  the  bhukler,  that  it  shall  enlarge  in  a  diri'ction  which  will  admit  of  the 
greatest  amount  of  distension,  i.e.  one  between  the  lower  or  yielding  part  of  the 
abdominal  wall  and  the  hollow  of  the  rectum,  which  is  compressible. 

(2)  The  obliterated  hypogastric  arteries.  These,  the  remains  of  vessels  which 
during  fatal  life  carry  the  impure  blood  of  the  foetus  out  to  the  mother  through 
the  umbilicus,  run  up  and  join  the  urachus  at  the  umbilicus.  In  relation  to  these 
cords  are  the  following  fossae  :  (a)  An  internal  one,  between  the  urachus  and  the 
obliterated  hyj)()gastric  artery.  This  corresponds,  on  the  anterior  surface,  to  the 
external  al)dominal  ring.  Through  this  fossa  comes  direct  inguinal  hernia,  (b) 
Between  the  obliterated  hypogastric  artery  and  the  deep  epigastric  artery,  running 
u]) wards  and  inwards  to  form  the  outer  boundary  of  Hesselbach's  triangle,  is  a 
middle  fossa.  This  is  the  smallest  of  all.  (c)  The  external  fossa  is  outside  the 
det'p  epigastric  artery.  It  is  the  most  distinct  of  the  three,  from  the  way  in  which 
the  cord  or  round  ligament  passes  down  within  a  glove-like  process  of  the  trans- 
versalis  fascia.     This  fossa  corresponds  to  the  internal  ring. 

Varieties  of  inguinal  hernia  according  to  the  condition  of  the  vaginal 
process  of  peritoneum. — Inguinal  hernia?  have  above  been  classified  according 
to  thtiv  relation  to  the  deep  epigastric  artery.  It  remains  to  allude  to  the  arrange- 
iiicnt  of  these  same  hernia?  according  to  the  varying  condition  of  the  processus 
funiculo-vaginalis.  This  pouch  of  peritoneum,  which  paves  the  way  for  the  pas- 
sage of  the  testis  before  this  organ  makes  its  start,  eventually  becomes  the  tunica 
vaginalis  below,  in  this  fashion:  Ver}^  soon  after  birth  the  process  becomes  oblit- 
erated at  two  spots — one  near  the  internal  ring,  and  one  just  above  the  testicle.  The 
obliterative  process,  commencing  first  above  and  descending,  and  then,  ascending 
from  below,  the  shrivelling  continues  until  nothing  is  left  save  the  tunica  vaginalis 
below.  The  following  are  possible  outcomes  from  an  imperfect  obliteration  of  the 
process — the  first,  alone,  is  common: — 

(1)  If  the  process  does  not  close  at  all,  a  descending  hernia  is  called  congenital. 
This  may  make  its  way  into  the  scrotum.  The  testis  is  now  enveloi)ed  and  con- 
cealed by  the  hernia. 

(2)  If  the  process  is  closed  only  above,  i.e.  near  the  internal  ring,  the  hernia 
may  make  its  way  behind  the  unobliterated  processus  funiculo-vaginalis.  To  this 
variety  of  inguinal  hernia  the  name  infantile  has  been  given.  Its  only  importance 
is  that  during  any  operation  for  such  a  hernia  three  layers  of  peritoneum  would 
have  to  be  divided  before  the  hernial  contents  could  be  reached.  If,  again,  during 
some  exertion,  the  hernia  rupture  the  obliterating  septum  which  has  formed  above, 
the  condition  of  things  to  be  dealt  with  is  practically  that  of  a  congenital  hernia. 

(3)  If  the  processus  funiculo-vaginalis  be  closed  l)elow  and  not  above,  a  patent 
tul)ular  process  of  peritoneum  will  lead  down  as  far  as  the  top  of  the  testis.  Any 
liernia  into  this  process  is  called  a  hernia  into  the  funicular  process. 

Inguinal  hernia  in  the  female. — The  inguinal  canal  in  women  is  smaller  and 
narrower  than  in  men.  Inguinal  hernia  is,  therefore,  uncommon  in  the  female  sex, 
and  only  occurs  before  adolescence,  in  patients  who  happen  to  be  the  subjects  of  an 
unobliterated  processus  funiculo-vaginalis,  which  extends  for  a  varying  distance 
along  the  round  ligament,  and  is  called  the  canal  of  Nuck.  Inguinal  hernia  in  the 
female  is,  therefore,  always  congenital.  It  is,  practically,  always  of  the  oblique 
variety,  and  travels  along  the  round  ligament  towards  the  labium  majus.  Its  cov- 
erings will  be  the  same  as  those  of  the  oblique  variety  in  the  male,  save  that  the 
cremaster,  as  a  distinct  muscle,  is  absent,  and  any  fibres  of  the  internal  oblique 
which  may  be  present  are  but  little  developed. 

Causes  of  hernia. — It  will  he  well,  while  the  anatomy  of  hernia  is  being  con- 
sidered, to  refer  briefiy  to  the  causes,  as  many  of  these  are  intimately  bound  up 
with  the  anatomy  of  the  parts.     Amongst  the  chief  are  the  following: — 

(1)  Hereditary,  viz.  weakness  of  alxlominal  wall;  openness  of  rings. 

(2)  Weak  spots. — (a)  The  presence  of  the  cord;  (b)  deficiency  of  some  of  the 


FEMORAL  HERNIA  1137 

layers  below;  (c)  persistence  of  tlie  original  process  of  peritoneum;  (r/)  a  long 
mesentery  or  suspensory  ligament  of  the  intestines.  :Mr.  Lockwood  has  shown 
that  the  mesentery  is  relatively  larger  in  infancy,  and  that  there  is  a  rapid  decrease 
after  the  second  year.  In  adults  its  length  is  about  eight  inches,  and  any 
lengthening  of  the  mesentery  beyond  this  point  is  likely  to  be  combined  with  a 
protuberant  l)elly.  He  shows  further,  with  regard  to  the  range  of  descent  or 
the  excursus  of  the  intestines,  that  it  is  extremely  rare  to  find  a  mesentery  so  short, 
or  attached  so  high,  as  to  prevent  the  intestines'  escaping  or  being  drawn  from  the 
abdomen. 

The  long  mesentery  of  infancy  and  childhood  is  usually  associated  with  consid- 
eralde  downward  df^scent  of  the  intestine;  and  in  the  adult  it  is  quite  common  to 
tind  that  the  small  intestines  will  pass  an  inch  and  a  half  beyond  the  right  crural 
arch,  one  inch  l)eyond  the  pul)es,  and  up  to  the  left  crural  arch. 

(3)  Stretching  of  the  abdominal  walls  l)y  pregnancies,  etc. 

(4)  Increase  of  the  volume  and  weight  of  the  parts  within:  e.g.  omentum  by 
deposit  of  fat  in  it. 

(5)  Sex.  Thus,  men  have  larger  inguinal  rings.  Women  have  a  larger  femoral 
arch,  and  one  less  Avell  filled  in  by  muscles,  and  with  less  strong  fasciae  meeting, 
e.g.  iliac  and  transversalis. 

(6)  Cough,  asthma,  bronchitis,  habitual  fretfulness  or  crying. 

(7)  Straining  to  expel  urine,  as  with  phimosis,  stricture,  stone  in  bladder,  etc. 

(8)  Straining  in  defecation. 

(9)  Lifting  heavy  weights. 

(10)  Results  of  wounds  or  abscesses  which  have  weakened  the  abdominal  wall. 

(11)  Whatever  diminishes  the  abdominal  cavity,  e.g.  tight  lacing. 


FEMORAL  HERNIA 

As  many  of  the  parts  concerned  here  are  also  met  with  in  inguinal  hernia,  one 
description,  given  now,  will  suffice. 

\\\ih.  regard  to  descriptions  of  the  inguinal  and  femoral  regions,  it  is  always 
well  to  bear  in  mind  the  following: — (1)  That  the  so-called  rings  and  canals  are 
merely  weak  spots  in  the  inguinal  and  femoral  regions,  and  that  they  do  not  exist 
distinctly,  and  do  not  get  beyond  the  potential  stage,  unless  made  by  a  scalpel  or 
a  hernia;  (2)  that  at  the  fold  of  the  groin  most  of  the  layers  blend  together,  and 
that  descriptions  of  them  as  separate  layers,  for  convenience  sake  in  learning  them, 
are  more  or  less  artificial;  (3)  that  the  description  of  these  layers  has  been  most 
needlessly  complicated  by  the  number  of  terms  used,  many  of  which  are  simply 
substitutes  for  others;  (4)  many  of  these  terms  are  not  only  useless  but  incorrect, 
e.g.  saj)henous,  crural,  etc. 

Parts  concerned  in  femoral  hernia.  (1)  Skin  and  superficial  fascia  of 
groin. — The  latter  consists  of  two  layers:  (a)  Superficial  layer  of  superficial 
fascia. — Fatty,  met  with  over  the  whole  groin,  and  continuous  with  the  superficial 
fascia  of  the  rest  of  the  body.  (6)  Deep  layer  of  superficial  fascia. — Thin  and 
membranous,  only  met  with  over  the  lower  tliird  of  thi'  alxlominal  wall  and  to 
the  inner  side  of  the  groin.  It  is  continu<)Us  through  the  scrotum  with  the  deep 
layer  of  the  superficial  fascia  of  the  perinjeum.  Just  below  Poupart's  ligament  it 
is  joined  to  the  fascia  lata.  From  these  two  facts  it  results  that  in  ru])ture  or 
giving  way  of  the  urethra  the  extravasated  urine  may  come  forwards  by  way  of  the 
genitals  (page  1124)  and  from  the  continuity  of  the  fascia  make  its  way  on  to  the 
abdomen,  but  not  down  on  to  the  thigh. 

Between  the  two  layers  of  superficial  fascia  lie  the  superficial  glands  of  the 
groin,  the  superficial  branches  of  the  common  femoral  artery,  one  or  two  cutaneous 
nerves,  and  some  veins  descending  to  the  saphenous  opening  to  join  the  long 
saphena  vein. 

(2)  Poupart's  ligament. — This  is  also  known  as  the  crural  arcli,  a  misnomer, 
as  'crus'  means  leg.  A  description  of  its  .'^hape  and  attachments  is  given  on  page 
1114.  Owing  to  the  connection  of  the  fascia  lata  to  its  lower  l)order,  the 
'saphenous  opening,'  which  is  situated  in  tiie  fascia  lata,  and  has  its  upper  cornu 


1138  SURGICAL  AXD    TOPOGRAPHICAL  ANATOMY 

blending  with  Ponpart's  ligament,  will  be  affected  l)y  movements  of  the  thigh, 
much  as  is  the  external  abdominal  ring,  being  tightened  and  stretched  when  the 
hmb  is  extended  and  abducted,  relaxed  when  it  is  adducted  and  Hexed. 

The  parts  beneath  the  ligament  which  block  up  the  gap  between  it  and  the 
innominate  bone  are  of  the  utmost  importance  in  preventing  the  escape  of  a  femoral 
hernia. 

The  different  structures  are  arranged  in  three  compartments,  named  from  with- 
out inwards — A.  Outer,  or  iliac ;  B.  Central,  or  vascular ;  and  C.  Inner,  or 
pectineal.  Of  these,  the  tirst  is  the  largest;  the  second  or  central  one  lies  on  a 
j)lane  slightlv  more  superficial,  or  nearer  to  Ponpart's  ligament, than  the  other  two; 
wliile  the  innermost  compartment  differs  from  the  other  two  by  not  communicating 
with  the  pelvis,  being  closed  above  by  fascia  (vide  infra).  (A)  The  outer,  or 
iliac,  compartment  is  bounded  in  front  by  Ponpart's  ligament  and  the  iliqc  fascia, 
whicli  is  here  blending  with  it,  behind  bv  the  ilium,  externally  by  this  bone  and 
the  sartorius,  and  internally  by  the  ilio-pectineal  septum,  which,  descending  from 
the  Ijlending  of  the  iliac  fascia  and  Ponpart's  ligament  alcove,  passes  down  to  the 
ilio-pectineal  eminence,  and  thence  to  the  inner  aspect  of  the  front  of  the  capsule 
of  the  hip-joint.  This  compartment  transmits  the  ilio-psoas  and  anterior  crural 
and  external  cutaneous  nerves.  (B)  The  central,  or  vascular,  compartment  is 
bounded,  in  front,  by  Ponpart's  ligament  and  the  transversalis  fascia,  which  here 
blends  with  it,  forming  the  so-called  deep  crural  arch,  and  at  the  same  time 
descends  on  to  the  front  of  the  femoral  sheath.  The  posterior  boundary  is  formed 
by  the  meeting  of  the  ilio-pectineal  sejitum  externally  and  the  pectineal  fascia  oi 
sheath  from  within — internally  Gimbernat's  ligament,  and  externally  the  ilio- 
pectineal  septum.  This  central  compartment  transmits  the  external  iliac  vessels 
and  crural  branch  of  the  genito-crural  nerve.  This  lies  to  the  outer  side  of  the 
artery,  the  vein  internally.  Between  the  vein  and  the  base  of  Gimbernat's 
ligament  is  the  femoral  canal  (vide  infra).  (C)  The  innermost,  or  pectineal, 
compartment  is  bounded  by  the  pectineal  fascia  continuous  Avith  the  pubic  part 
of  the  fascia  lata,  and  behind  by  the  pubic  ramus.  It  lodges  the  upper  end  of  the 
peetineus  muscle,  and  the  handle  of  a  scalpel  passed  upwards  along  the  muscle 
would  be  prevented  from  passing  into  the  pelvis  by  Gimbernat's  ligament  and  the 
blending  of  the  pectineal  fascia  with  the  upper  border  of  the  pubic  ramus. 

(3)  Gimbernat's  ligament. — This  is  merely  the  triangular  internal  attach- 
ment of  Ponpart's  ligament.  Its  apex  is  attached  to  the  pubic  spine;  of  its  three 
borders,  the  base  is  free  towards  the  vein  and  the  femoral  canal.  Its  upper  border 
is  continuous  with  Ponpart's  ligament,  its  lower  is  attached  to  the  ilio-pectineal 
line. 

(4)  Fascia  lata. — Two  portions  are  described  over  the  upper  part  of  the 
thigh: — (a)  An  iliac,  external  and  stronger,  attached  to  Ponpart's  ligament  in  it? 
whole  extent  and  lying  over  the  sartorius,  ilio-psoas,  and  rectus,  (b)  A  pubic, 
internal,  weaker,  and  much  less  well  defined,  is  attached  above  to  the  ilio-pectinea 
line  and  the  spine  of  the  pubes.  The  upper  cornu  of  the  '  saphenous  opening  '  is 
at  Gimbernat's  ligament,  and  at  the  loAver  cornu  the  two  portions  of  the  fasci 
blend. 

Their  relation  to  the  femoral  vessels. — The  iliac   jiortion,   being  attached   alon 
Poupart's  ligament,  passes  over  these.     Tlie  pubic  portion,  fastened  down  over  the 
peetineus,  which  slopes  down  on  to  a  deeper  plane  than  the  adjacent  muscles,  passes 
behind  the  femoral  vessels  to  end  on  the  capsule  of  the  hip-joint. 

(5)  Saphenous  opening. — This  is  doubly  a  misnomer.  It  is  not  an  opening, 
but  an  oval  depression,  situated  at  the  spot  where  the  two  parts  of  the  fascia  lata 
diverge  on  different  levels.  As  without  dissection  it  is  not  an  opening,  but  an  oval 
depression,  fossa  ovalis  would  have  been  a  better  term,  were  it  not  otherwise 
employed.  Though  the  fascia  lata  is  wanting  here,  there  is  no  real  opening,  as  the 
deficiency  is  made  up  by  the  deep  layer  of  superficial  fascia,  or  cribriform  fascia, 
which  fills  up  the  opening.  The  term  'saphenous'  is  also  misapplied:  etymologi- 
cally,  it  means  '  very  evident.'  Now,  it  is  notorious  that  in  very  many  subjects  this 
opening  only  becomes  plain  when  rendered  an  artificial  one  by  dissection;  and  that 
thus,  with  the  limited  op])ortunities  of  one  or  two  subjects,  it  is  by  no  means  ea.sy 
to  verifv  the  details  about  it  which  have  been  described  as  constant. 


I 


FEMORAL    HERNIA  1139 

Uses  of  the  ^saphenous  openinf/.^ — Though  a  weak  spot,  it  is  so  on  purpose  to 
transmit  the  saphenato  the  femoral  vein,  and  the  su])erticial  to  the  deep  lympliaties. 
The  depression  is  present  in  order  to  allow  the  saphena  vein  to  he  ])rotected  from 
pressure  in  liexion  of  the  thi<rh. 

Site. — At  the  inner  and  njjper  part  of  the  thigh,  with  its  centre  an  inch  and  a 
half  l)elow  and  outside  the  spine  of  the  ])uhes. 

Diaineters. — One  inch  (25  mm. )  vertically,  hy  a  half  or  three-quarters  of  an  inch. 
Shape:  oval,  with  its  hnig  axis  downwards  and  outwards.  Two  extremities  or  conuia  : 
upper  Vjlending  with  Giml)ernat's  ligament;  lower,  where  the  twf)  j)artsof  the  fascia 
lata  meet.  Tuo  borders:  outer  also  known  as  the  ligament  of  Hey,  or  femoral  ligament, 
or  falciform  ])n)cess  of  Burns.  Semilunar  in  shape,  arching  downwards  and  out- 
wards from  Gimhernat's  ligament  to  the  inferior  cornu.  This  lies  over  the  femoral 
vessels,  and  is  adherent  to  them;  to  it  is  fixed  superficially  the  cribriform  fascia 
{vide  infra).  The  inner  border  is  much  less  prominent,  owing  to  the  weakness  oi 
the  pubic  })art  of  the  fascia  lata  which  forms  it. 

(6)  Femoral  sheath. — This  is  a  funnel-shaped  sheath,  carried  out  by  the 
femoral  vessels  under  Poupart's  ligament,  and  continuous  above  (in  front)  with  the 
transversalis  fascia  as  it  descends  to  the  ligament,  lining  the  inner  surface  of  the 
abdominal  wall,  and  (behind)  with  the  iliac  fascia,  and  below  continuous  with  the 
proper  sheath  of  the  femoral  vessels. 

It  is  not  only  funnel-shaped,  but  large  and  loose,  for  two  reasons:  (n  }  That  there 
be  plenty  of  room  for  the  femoral  vein,  and  the  slowly  moving  venous  current  in  it 
to  ascend  without  compression;  (//)  to  allow  of  all  the  movements  of  the  thigh 
taking  place — flexion  and  extension — without  undue  stretching  of  the  vessels.  By 
two  coimective  tissue  septa  the  sheath  is  divided  into  three  compartments — the 
outer  for  the  artery,  the  middle  for  the  vein,  and  the  internal  one  for  the  femoral 
canal  (vide  infra).  Thus  one  septum  lies  between  the  artery  and  vein,  and  another 
between  the  vein  and  the  femoral  canal. 

(7)  Femoral  canal. — Definition:  the  innermost  division  of  the  femoral  sheath. 
The  fascia  transversalis  and  fascia  iliaca  meet  directly  on  the  outer  side  of  the 
femoral  artery,  but  not  so  closely  on  the  inner  side  of  the  femoral  vein.  Hence  a 
space  exists  here,  perhaps  to  prevent  the  thin-walled  vein,  with  its  sluggish  current, 
Vicing  pressed  upon.  Thus,  a  slight  gap  exists  here — not  a  canal,  unless  so  made  by 
a  knife  or  by  the  dilating  influence  of  a  hernia.  Length  :  about  thrcf-quarters  of  an 
inch  (19  mm.).     IJmits :  Ijclow,  saphenous  opening;  above,  femoral  ring  (vide  infra). 

Boundarieii. — Externally,  a  septum  between  it  and  the  vein;  internally,  base  of 
Gimbernat's  ligament  and  meeting  of  fascia  iliaca  and  transversalis;  behind,  fascia 
iliaca;  in  front,  fascia  transversalis. 

Content.-^. — Cellular  tissue  and  fat,  continuous  with  extra-peritoneal  fatty  layi-r. 
A  lymphatic  gland,  which  is  inconstant.  Lymphatics  passing  from  superficial 
(groin)  glands  to  those  deep  in  the  iliac  fossa. 

(8)  Femoral  ring. — This  is  mainly  an  artificial  product.  It  is  the  upper  or 
abdominal  opening  of  the  femoral  canal.  Shape :  oval,  with  its  long  axis  trans- 
verse. It  is  larger  in  women.  Boundaries:  internally,  Gimhernat's  ligament; 
externally,  the  femoral  vein;  in  front,  Poupart's  ligament  and  the  thickening  of 
the  transversalis  fascia  attached  to  it,  and  called  '  the  deep  crural  arch  ' ;  behind,  the 
pectineus  and  the  ilio-pectineal  line.  It  is  closed  by  the  septum  crurale.  which  is 
a  barrier  of  fatty  connective  tissue,  continuous  with  the  extra-i)eritoneal  fatty  layer, 
perforatrd  ])v  Ivmpliatics  passing  from  the  superficial  to  the  deep  group. 

Position  oiF  vessels  around  the  ring. — Outside,  the  femoral  vein;  above,  the 
epigastric  vessels;  towards  the  inner  side  there  may  be  an  unim]>ortant  branch 
between  the  epigastric  artery  aV)ove  and  the  obturator  below. 

If,  instead  of  the  above  unimi>ortant  branch,  the  ol)turator  artery  comes  off 
abnormally  from  the  deep  e]>igastric.  it  will  descend,  and  usually  does  so,  close  to 
the  junction  of  the  external  iliac  and  connnon  femoral  vein,  and  thus  to  the  outer, 
and  so  the  safe,  side  of  the  ring  (fig.  704,  A).  In  a  very  few  cases  it  curves  more 
inwards,  close  to  Giml)ernat's  ligament,  an<l  thus  to  the  inner  side  of  the  ring,  and 
is  then  in  great  danger  (fig.  704,  B).  Sir  William  Lawrrncc  calculated  that  this 
took  ]ilace  once  in  a  hundred  cases. 

Course  of  femoral  hernia. — At  first  this  is  downwards  in  the  femoral  canal. 


1140 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


A  pouch  of  peritoneum  having  been  gradually,  after  repeated  straining,  coughing, 
etc.,  pushed  through  the  weak  spot,  the  femoral  ring,  further  weakened  perhaps, 
together  with  all  the  parts  in  the  femoral  arch,  by  child-bearing,  some  extra  efi'ort 
will  force  intestine  or  omentum  into  this  pouch  and  thus  form  a  hernia.  Thus 
formed,  femoral  hernia  passes  at  first  downwards  in  the  femoral  canal  as  far  as  the 
saphenous  opening,  but,  as  a  rule,  does  not  go  farther  downwards  on  the  thigh,  but 
mounts  forwards  and  upwards,  and  somewhat  outwards,  even  reaching  the  level  of 
Poupart's  ligament.  The  reasons  for  this  change  of  position  are — (1)  The  narrow- 
ing of  the  femoral  sheath,  funnel-like,  i.e.  wide  above  but  narrowed  below;  (2) 
the  unyielding  nature  of  the  lower  margin  of  the  saphenous  opening;  (3)  the  fact 
that  this  margin  and  the  outer  border  are  united  to  the  femoral  sheath;  (4)  the 


Fig.  704. — Irregularities  of  the  Obturator  Artery.     (After  Gray.) 
A 


Deep  circumflex  iliac  artery — ix 

Ejcternal  iliac  artery 
Ejcternal  iliac  vein 

Obturator  /oram,er> 


Internal  ring,  uith  spermatic 
vessels  cut  short  in  it 

De^p  epigastric  artery 


Lympliatic  gland  in  femoral 
ring 

The  obturator  artery,  given  off" 
from  the  external  iliac  uith  the 
deep  epigastric,  descends  to  gain 
the  obturator  foramen,  but  at  a 
safe  distance  from,  the  femoral 
ring 


B 


The  obturator  artery,  coming  off" 
from  the  deep  epigastric,  takes 
a  course  so  near  to  the  femoral 
ring  that  it  tvould  very  likely 
be  (lidded  by  the  bistonry  intro- 
ductil  from  n-ithout  to  divide 
the  base  of  Gimbernat's  liga- 
ment, the  cause  of  the  constric- 
tion 


constant  flexion  of  the  thigh;  (5)  the  fact  that  vessels  (chiefly  veins)  and  lym- 
phatics descend  to  the  sa})henous  opening,  the  veins  to  join  the  saphena  vein,  and 
the  lymphatics  to  join  the  deeper  group:  these  descending  vessels  serve  to  loop 
upwards  or  suspend  a  femoral  hernia,  and  thus  prevent  its  further  course  down- 
wards. 

Coverings  of  a  femoral  hernia. — (A)  At  the  upper  or  femoral  ring  it 
obtains  ])eritoneum,  extra-] )erit()neal  fat,  and  septum  crurale. 

(B)  In  the  canal,  a  coating  of  the  femoral  sheath. 

(C)  At  the  external  or  superficial  opening,  further  coverings  of  cribriform 
fascia,  skin,  and  superficial  fascia  are  added. 


UMBILICAL   HERNIA  1141 

Some  of  these  may  be  deficient  by  the  hernia  bursting  through  them,  or  they 
may  be  matted  together.  Sir  A.  Cooper  thought  this  especially  likely  to  occur 
with  the  layer  of  femoral  sheath  and  septum  crurale  to  which  he  gave  the  name 
of  fascia  lyropria. 


PARTS  CONCERNED  IN  UMBILICAL  HERNIA 

A  hernial  protrusion  at  the  umbilicus,  or  exomphalos,  may  occur  at  three  dis- 
tinct periods  of  life,  according  to  the  anatomy  of  the  part.  Any  account  of  umbil- 
ical hernia  would  be  incomplete  without  an  attempt  to  explain  how  this  region, 
originally  a  most  distinct  opening,  is  gradually  closed  and  changed  into  a  knotty 
mass  of  scar,  the  strongest  point  in  the  abdominal  wall. 

During  the  first  weeks  of  foetal  life,  in  addition  to  the  uraclius,  uml)ilical 
arteries,  and  vein,  some  of  the  membranes  and  a  portion  of  tlie  intestine  ])ass 
through  the  opening  to  join  that  part  of  the  digestive  tract  which  is  developed  out- 
side the  abdomen  up  to  a  certain  time,  and  then  re-enters  that  cavity.  Occasionally 
this  condition  persists,  owing  to  failure  of  development,  and  the  child  is  born  with 
a  large  hernial  swelling  outside  the  abdomen,  imperfectly  covered  with  skin  and 
peritoneum.  To  this  condition  the  term  congenital  umbilical  hernia  should  be 
applied. 

Later  on  in  fcetal  life  it  is  the  umbilical  vessels  alone  which  pass  through  this 
opening.  At  l>irth  there  is  a  distinct  ring,  Avhich  can  be  felt  for  some  time  after  in 
the  flaccid  Avails  of  an  infant's  belly.  If  this  condition  persist,  a  piece  of  intestine 
may  find  its  way  through,  forming  the  condition  which  should  be  known  as 
infantile  umbilical  hernia. 

This  condition  is  not  uncommon,  ^^'hy  it  is  not  more  fre(|uently  met  with  is 
explained  by  the  way  in  which  this  ring  of  infancy  is  closed  and  gradually  con- 
verted into  the  dense  mass  of  scar  tissue  so  familiar  in  adult  life.  This  is  l)rought 
about  (1)  by  changes  in  the  ring  itself;  (2)  by  changes  in  the  vessels  which  pass 
through  it. 

(1)  Changes  in  the  ring  itself. — The  umbilical  ring  is  surrounded  by  a 
sphincter-like  arrangement  of  elastic  filn-es,  best  seen  during  the  first  few  days  of 
fcetal  life,  on  the  posterior  wall  of  the  l)elly.  In  older  infants  these  fibres  lose  their 
elasticity,  become  more  tendinous,  and  then  shrink  more  and  more.  As  they  con- 
tract they  divide,  as  by  a  ligature,  the  vessels  passing  through  the  ring,  thus  account- 
ing for  the  fact  that  the  cord,  wherever  divided,  drops  off  at  the  same  spot  and 
without  bleeding. 

(2)  Changes  in  the  vessels  themselves. — When  blood  c<^ses  to  traverse 
these,  their  lumen  contains  clots,  their  muscular  tissue  wastes,  while  the  connective 
tissue  of  their  outer  coat  hypertrophies  and  thickens.  Thus,  the  umbilical  vessels 
and  the  umbilical  ring  are,  alike,  converted  into  scar-tissue,  which  blends 
together.  This  remains  weak  for  some  time,  and  may  be  distended  by  a  hernia 
(infantile). 

Finally,  we  have  to  consider  the  state  of  the  umltilicus  in  adult  life.  The  very 
dense,  unyielding,  fibrous  knot  shows  two  sets  of  fibres: — (1)  Those  decussating 
in  the  middle  line;  and  (2)  two  sets  of  circular  fibrous  bundles  Avhich  interlace  at 
the  lateral  boundaries  of  the  ring.  The  lower  part  of  the  ring  is  stronger  than  the 
upper.  In  other  words,  umbilical  hernia  of  adult  life,  when  it  comes  through 
the  ring  itself  and  not  at  the  side,  always  conies  tlirough  the  upper  ])art.  In  the 
lower  three-fourths  of  the  umbilicus  the  umbilical  arteries  and  urachus  are  fimdy 
closed  by  matting  in  a  firm  knot  of  scar-tissue;  in  the  upper  tliere  is  only  the 
uml)ilical  vein  and  weaker  scar.  To  the  lower  part  run  up  the  umbilical  arteries 
and  the  urachus.  Owing  to  the  rapid  growth  of  the  alKloniinal  wall  and  pelvis 
before  puberty,  and  the  fact  that  the  urachus  and  the  umbilical  arteries,  being  of 
scar-tissue,  elongate  with  difficulty,  the  latter  parts  depress  the  umlnlicus  l>y  reason 
of  their  intimate  connection  witii  its  lower  half. 

Coverings  of  an  umbilical  hernia. — These,  more  or  less  matted  together,  are: 
— (1)  Skin;  (2)  superficial  fascia,  which  loses  its  fat  over  the  hernia;  (3)  prolonga- 
tion of  scar-tissue  of  the  umbilicus  gradually  stretched  out;  (4)  transversalis  fascia; 


1142  SURGICAL  AXD  TOPOGRAPHICAL   AX  ATOMY 

(5)  extra-peritoneal  fatty  tissue;  (6)  peritoneum.  If  the  hernia  come  through 
above  the  umbilicus,  or  just  to  one  side,  the  coverings  will  be  much  the  same;  but, 
instead  of  the  layer  from  the  umbilical  scar,  there  ^vi]l  be  one  from  the  linea  alba. 


THE  BACK 

Median  furrow. — This  is  more  or  less  marked  according  to  the  muscular  devel- 
opment, lying  between  the  trapezii  and  complexi,  in  the  cervical  region,  and  the 
erectores  spinae  lower  down.  The  lower  end  of  the  furrow  corresponds  to  the 
interval  between  the  spines  of  the  last  lumbar  and  the  first  sacral  vertebrae 
(Holden). 

Vertebral  spines. — Those  of  the  upper  cervical  region  are  scarcely  to  be  made 
out  even  by  deep  pressure.  That  of  the  axis  may  be  detected  in  a  thin  subject. 
Over  the  spines  of  the  middle  three  cervical  vertebrae  is  normally  a  hollow,  owing 
to  these  spines  receding  from  the  surface  to  allow  of  free  extension  of  the  neck. 
The  seventh  cervical  is  prominent,  as  its  name  denotes.  Between  the  skull  and 
atlas,  or  between  the  atlas  and  axis,  a  sharp-pointed  instrument  might  penetrate, 
especially  in  flexion  of  the  neck. 

Of  the  thoracic  spines,  the  first  is  the  most  prominent;  the  third  should  be 
noted  as  on  a  level  with  the  inner  end  of  the  scapular  spine,  and  in  some  cases  with 
the  bifurcation  of  the  trachea;  that  of  the  seventh  with  the  lower  angle  of  the 
scapula;  that  of  the  twelfth  with  the  lowest  part  of  the  trapezius  and  the  head  of 
the  twelfth  rib.  The  obliquity  and  overlapping  of  the  thoracic  spines  is  to  be 
remembered. 

Of  the  lumbar  spines,  the  most  important  are  the  second,  which  corresponds  to 
the  termination  of  the  cord,  and  that  of  the  fourth,  which  marks  the  highest  ])art 
of  the  iliac  crests  and  the  liifurcation  of  the  abdominal  aorta.  The  lumliar  spines 
project  horizontally,  and  correspond  with  the  vertebral  bodies.  Tlie  third  is  a 
little  above  the  umbilicus. 

Owing  to  the  obliquity  of  the  thoracic  spines,  most  of  them  do  not  tally  with 
the  heads  of  the  corresponding  ribs.  Thus,  the  spine  of  the  second  corresponds 
Avith  the  head  of  the  third  rib;  the  spine  of  the  third  with  the  head  of  the  fourth 
rib;  and  so  on  fill  Ave  come  to  the  eleventh  and  twelfth  vertebrae,  Avhich  do  tally 
with  their  corresponding  ribs  (Holden). 

•  The  lower  ribs  may  be  felt  outside  the  erector  spinae,  but,  in  counting  them  from 
below,  it  must  be  remembered,  as  pointed  out  by  Holl,  that  in  quite  a  considerable 
percentage  the  last  rib  is  so  abnormally  short  that  it  does  not  reach  as  far  as  the 
outer  border  of  the  sacro-lumbalis;  or  so  rudimentary  as  to  more  resemble  a 
transverse  process.  In  these  cases  the  lower  end  of  the  pleura  may  pass  from  the 
lower  part  of  the  tAvelfth  thoracic  vertebra,  almost  horizontally  to  the  loAver  edge  of 
the  eleventh  rib. 

Muscles. — The  student  will  remember  the  great  number  and  complexity  and 
the  numerous  tendons  of  the  muscles  Avhich  run  up  on  cither  side  of  the  spine; 
the  firmness  and  inextensibility  of  their  sheaths;  the  large  amount  of  cellular 
tissue  betAveen  them;  and  the  fact  that  towards  the  nape  of  the  neck  these 
muscles  lie  exposed  instead  of  being  protected  in  gutters,  as  is  the  case  beloAv:  all 
these  anatomical  points  explain  the  extreme  painfulnoss  and  ol)stinacy  of  sprains 
here. 

Trapezius. — To  map  out  this  muscle,  the  arm  should  be  raised  to  a  right  angle 
Avith  the  spine.  The  external  occipital  protuberance  should  be  dotted  in,  and  the 
superior  nuchal  line  passing  out  from  this;  beloAv,  the  tAvelfth  thoracic  spine  should 
be  marked;  and  externally,  the  outer  third  of  the  clavicle  and  the  commencement 
of  the  sca])ular  spine.  Then  a  line  should  be  draAvn  from  the  protuberance  A-erti- 
cally  dowuAA'ards  to  the  twelfth  thoracic  spine;  a  second  from  al)0Ut  tlie  middle  of 


SURFACE  MARKINGS   OF  MUSCLES   OF  BACK 


1143 


the  superior  nuchal  line  to  the  posterior  and  outer  third  of  the  clavicle;  and  a  third 
from  the  last  thoracic  spine  upwards  and  outwards  to  the  spine  of  the  scaj^ula. 

Latissimus  dorsi.— The  arm  being  raised  above  a  riglit  angle,  the  spines  of 


Fig.  705.— Diagram  axd  Taisi.e  ."showing  the  Approximate  Relation  to  the  Spinal 
Nerves  OF  the  variois  Motor,  8en.sory,  and  Reflex  Functions  of  the  Spinal 
Cord.     (Arranged  by  Dr.  Gowers  4'rom  anatomical  and  patholodcal  data.) 


J.-^-, 


MOTOR 


IC 

-y   1 

'  .Sterno-mastoid 

4  f  Trapezius 

5  I     !•  Diaphragm 

I  Serratus 
C   ("Shoulder 


Hand 

(ulnar  lowest) 


Intercostal 
muscles 


pathological 
SENSORY 


>•  Neck  and  scalp 
>  Neck  and  shoulder 


Shoulder 
.  Ami 

Hand 


■  Front  of  thorax 
1 


Ensiform  area 


Abdomen 
(Umbilicus  10th) 


,  Buttock,  upper 
J   )  part 


(  Groin  and 

_'  I  frf.i 


scrotum 
(front) 
f  outer  side 


Thigh  ■{   front 


L  inner  side 
Leg,  inner  side 


REFLEX 


Scapular 


-  Epigastric 


f-  Abdominal 


Cremasteric 
Knee-joint 


f  Buttock,  lower  part     j"  Gluteal 


Back  of  thigh 

and  -except  inner 
.  foot )         part 

PerinKum  and  anus 


Skin  from  coccyx  to 
anus 


Fool  clonus 
Plantar 


the  sixth  thoracic  and  the  third  sacral  vertebrae  should  be  marked;  then  the  outer 
lip  of  the  crest  of  the  ilium,  the  lower  two  or  three  ribs,  the  lower  angle  of  the 
scapula,  and  the  posterior  fold  of  the  axilla,  and  finally  the  bicipital  groove  should 
all  be  marked. 


1144 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


Fig.  706. — Chief  Arterial  Anastomoses  on  the  Scapula. 
(From  a  dissection  in  the  Hunterian  Museum.) 

Supra-spinatus    SuprascaptUar  artery 
Posterior  scapular  artery  i       ,  Infra-spinatus 


Khomboideua  minor 
Levator  anguli  scapulae 


Triceps,  cut 

Deltoid,  insertion 
Deltoid 


Trapezius 
Hhomboideus  major 

Teres  major  muscles 


Deltoid  muscle 
Triceps 


Teres  major,  insertion 
Dorsalis  scapula  artery   Posterior  circumflex  artery 


Fig.  707. — Arrangement  of  Lumbar  Aponeurosis  at  Level  of  Third  Lumbar 

Vertebra. 


Sacro-lumbaljB 


Transversalis 


.   Internal  oblique 


External  oblique 


Latissimus  dorsi 


Quadratus  lumborum 
Longissimus  dorsi 
Psoas  magnus 


ORIGIN  OF  SPINAL  NERVES 


1145 


A  vertical  line  from  the  sixth  thoracic  to  the  third  sacral  spine  will  give  the 
spinal  origin  of  the  niuscle.  Another  from  the  third  sacral  spine  to  a  ])oint  on 
the  iliac  crest,  an  inch  or  more  outside  the  edge  of  the  erector  s)Mna',  will  give  the 
origin  of  the  muscle  from  the  sheatli  of  the  erector  spina?  and  the  ilium.  A  line 
from  the  sixth  thoracic  spine,  almost  transversely  at  first,  with  increasing  slight 
obliquity  over  the  inferior  angle  of  the  scapula  to  the  axilla  and  bicipital  groove, 
will  mark  the  upper  border  of  the  nmscle.  Another  very  oblicjue  line  from  the 
point  on  the  iliac  crest  upwards  and  outwards  to  the  axilla  will  give  the  lower 
border  and  the  tapering  triangular  apex  of  the  insertion.  The  muscle  may  \w 
attached  to  the  angle  of  the  scapula,  or  separated  from  it  by  a  bursa. 

Fig.  708.— Relations  of  the  Abdominal  Visceka  to  the  Antekiok  Parietes.     (Treves.) 


Triangle  of  Petit. — This  small  space  lies  above  the  crest  of  the  ilium,  at  about 
its  centre,  bounded  by  the  anterior  edge  of  the  latissimus  and  the  po.sterior  border 
of  the  external  oblique. 

Origin  of  spinal  nerves. — It  is  very  inq)<)rtant  to  remember  the  relations  of 
these  to  the  vertebral  spines,  in  determining  the  results  of  disease  or  injury  of  the 
cord  and  the  parts  thereby  affected.  The  above  relation  may  be  given  brietly  as 
follows : — 

The  origins  of  the  eight  cervical  nerves  correspond  to  the  cord  between  the  occi- 
put and  the  sixth  cervical  spine.  The  upper  six  thoracic  come  off  lietween  the 
above  spine  and  that  of  the  fourth  thoracic  vertebra.  The  origins  of  the  lower  six 
thoracic  nerves  correspond  to  the  interval  l)etween  the  fourth  and  the  tenth  thoracic 


1146 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


spines.  The  five  lumbar  arise  opposite  the  eleventh  and  twelfth  thoracic  spines; 
and  the  origins  of  the  live  sacral  correspond  to  the  tirst  lumbar  spines.  The  dia- 
gram and  table  (tig.  705),  arranged  by  Dr.  Gowers  from  anatomical  and  patho- 
logical data,  show  the  relations  of  the  origins  of  the  nerves  to  their  exits  from  the 
vertebral  canal,  and  the  regions  supplied  by  each. 

Scapula,  its  muscles  and  arterial  anastomoses. — Amongst  the  landmarks 
in  the  back,  the  student  should  be  careful  to  trace  the  angles  and  borders  of  the 
scapula  as  far  as  these  are  accessible.  The  upper  border  is  the  one  most  thickly 
covered.  With  the  hands  hanging  down,  the  upper  angle  corresponds  to  the  upper 
border  of  the  second  rib;  the  lower  angle  to  the  seventh  intercostal  space;  and  the 

Fig.  709. — Relations  of  the  Abdominal  Viscera  to  the  Posterior  Parietes.      (Treves.) 


root  of  the  spine  of  the  scapula  to  the  interval  betw^een  the  third  and  fourth  tho- 
racic spines.  Fig.  706  shows  the  chief  arteries  around  the  scapula.  The  anas- 
tomoses on  the  acromial  process  between  the  suprascapular,  acromio-thoracic,  and 
circumflex  arteries  are  not  shown. 

Lumbar  fascia. — In  the  loins,  the  muscles  which  fill  in  the  space  between  the 
last  rib  and  the  crest  of  the  ilium  should  be  carefully  noted,  owing  to  the  frequency 
of  operations  here.  When  the  latissimus  dorsi,  the  oblique,  the  transversalis,  the 
erector  spinas,  and  quadratus  have  been  described,  the  lumbar  fascia  (the  posterior 
aponeurosis  of  the  transversalis),  and  the  three  layers  into  which  it  divides  poste- 
riorly (fig.  707)  should  be  remembered. 

Viscera. — Several  of  these,  which  can  be  mapped  in  behind — viz.  the  kidneys, 


ABDOMINAL    VISCERA 


1147 


spleen,    etc.— have  been  already  mentioned  (pages  1119,    1120).      See  also  page 
1119  for  the  incision  for  hiiiibar  colotoniy. 

The  commencement  of  tlie  trachea  and  oesophagus  has  been  given  in  front  as 
corresponding  to  the  tiftli  cervical  vertebra.  If  examined  from  behind,  this  point, 
owing  to  the  obliquity  of  the  spines,  would  be  a  little  lower  down.  The  trachea, 
ibout  five  inches  long,  descending  in  the  middle  line,  bifurcates  opposite  to  the 


Fig.  710.— AiJUoMiNAL  Vi.scera,  from  behind.    (Rudinger.) 


DESCENDING   COLON  . 

inferior  mesenteric 
vein 


Diaphragm 


upenor  mesenteric 
vein 
'  ASCENDING  COLON 


interval  between  the  third  and  fourth  thoracic  spines.  The  bronchi  enter  the 
lungs  at  about  the  level  of  the  fifth  thoracic  spine,  the  right  being  the  shorter, 
wider,  and  more  horizontal.  The  oesophagus,  about  ten  inches  in  length,  starting 
in  the  middle  line,  curves,  at  once  gradually  to  the  left,  and  to  the  root  of  the 
neck;  from  this  point  it  tends  to  regain  the  middle  line  up  to  the  fifth  thoracic 
vertebra;  thence  finally  turns  again,  and  more  markedly  to  the  left,  and  passes 


1148 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


through  the  diaphragm  opposite  to  the  tenth  or  eleventh  thoracic  verteljra,  or  the 
ninth  or  tenth  thoracic  spine. 

The  aorta  reaches  tlie  left  side  of  the  vertebral  column,  with  its  arch 
just  above  the  fourtli  thoracic  si)ine,  and  thence  descends  on  the  front  of  the  col- 
unm,  with  a  sHght  tendency  to  the  left,  to  bifurcate  opposite  the  fourth  hnnbar 
spine. 

The  following  table,  from  Holden  and  "NVindle,  with  additions,  will  be  found 
very  useful  in  determining  the  relation  of  numerous  viscera  and  other  structures  to 
the  bodies  of  the  vertebra. 


Fig.  711. — View  of  the  Spleex,  etc.,  from  behind.     (Ruclinger.) 


1 


Cervical 

First.     Level  of  hard  palate. 

Second.     Level  of  free  edge  of  upper  teeth. 

Second  and  third.     Superior  cervical  ganglion  of  sympathetic. 

Fourth.     Hyoid  bone.     Upper  aperture  of  larynx. 

Fifth.  Middle  cervical  ganglion,  thyroid  cartilage,  and  rima  glottidis. 
Between  this  and  the  last  would  be  the  bifurcation  of  the  common  carotid. 

Sixth.     Cricoid  cartilage.     Ending  of  pharynx  and  larynx. 

Seventh.  Inferior  cervical  ganglion.  Apex  of  lung,  higher  in  the  female  than 
in  the  male.     Arch  of  thoracic  duct. 


THE  SHOULDER  1149 

Thoracic 

First.     Summit  of  arch  of  subclavian  (Godlee). 

Second.  Level  of  episternal  notch.  This  is  usually  opposite  the  fibro-cartilage 
l)et"\veen  the  second  and  third.      Bifurcation  of  innominate  (Ciodlee). 

Third.  Level  of  junction  between  the  manubrium  and  tlie  fjladiolus.  This  is 
sometimes  opposite  the  tifth.  Lowest  limit  of  superior  mediastinum.  Bifurca- 
tion of  trachea.     Beginning  of  superior  cava.     Highest  part  of  aortic  arch. 

Fourth.     Second  piece  of  aortic  arch  reaches  spine.    Arch  of  vena  azygos  major. 

Fifth.     Termination  of  tiiird  piece  of  aortic  arch. 

Fifth  to  eighth.     Base  of  heart. 

Sixth.  Pulmonary  and  aortic  valves.  Commencement  of  aorta  and  pulmonary 
artery.     End  of  superior  cava. 

Seventh.     Mitral  orifice. 

Eighth.     Tricuspid  orifice. 

Ninth.  Lower  level  of  manubrium.  Openings  in  diaphragm  for  inferior  vena 
cava  and  oesophagus.     Upper  limit  of  spleen. 

Tenth.  Level  of  tip  of  xiphoid  cartilage.  Lower  limit  of  lung  posteriorly. 
Upper  limit  of  liver  comes  to  the  surface  posteriorly.  (Esophagus  passes  through 
diaphragm.     Cardiac  orifice  of  stomach. 

ICleventh.     Lower  border  of  spleen.     Suprarenal  capsule. 

Twelfth.  Lowest  part  of  pleura.  Aorta  passes  through  diaphragm  (upper 
border).     Coeliac  axis  (lower  border).     Pylorus.     Upper  border  of  kidney. 

LUMB.\R 

First.     Pancreas.     Pelvis  of  kidney.     Renal  arteries  (ending). 

Second.  Spinal  cord  ends  at  junction  of  first  and  second.  Third  piece  of 
duodenum.     Receptaculum  chyli.     Lower  end  of  left  kidney. 

Third.  L^mbilicus,  opposite  fibro-cartilage,  between  this  and  fourth.  Lower 
end  of  right  kidney.     Lower  limit  of  liver  on  right  side. 

Fourth.      Bifurcation  of  aortic  arch.     Highest  part  of  iliac  crest. 

Fifth.     Commencement  of  superior  vena  cava. 

Sacral 

Third.     End  of  first  piece  of  rectum.     Lower  limit  of  spinal  membranes. 
Coccyx  (tip).     End  of  second  piece  of  rectum. 


SUPERFICIAL  AXATOMY  OF  THE  UPPER  LIMB 

THE  SHOULDER 

The  following  surface-marks,  of  the  greatest  importance  in  determining  the 
nature  of  shoulder  injuries,  can  be  made  out  \\vi\-  : — The  clavicle  in  its  whole 
extent,  the  acromion  process,  the  great  tuberosity,  and  upper  part  of  the 
shaft  of  the  humerus.  Much  h'ss  distinctly,  the  position  of  the  coracoid 
process  and  tlif  head  of  the  humerus  can  be  made  out.  The  anterior  margin 
of  the  clavicle,  convex  internally  and  concave  externally,  can  be  made  out  in  its 
whole  extent,  the  bone,  if  traced  outwards,  being  found  not  to  be  horizontal,  but 
rising  somewhat  to  its  junction  with  the  acromion.  The  tip  of  this  process,  when 
the  arm  hangs  by  the  side,  is  in  the  same  line  as  the  external  condyle  and  the 
styloid  process  of  the  radius.  On  the  inner  side,  the  head  and  internal  condyle  of 
the  humerus  and  the  styloid  process  of  the  ulna  are  in  the  same  line.     Thus  the 


1150 


SURGICAL  AND  TOPOGRAPHICAL  ANATOMY 


great  tuberosity  looks  outwards,  the  head  inwards,  and  the  lesser  tuberosity  some- 
what forwards.  Between  the  two  tuberosities  runs  the  bicipital  groove,  which, 
with  the  arm  in  the  above  position,  looks  directly  forwards.  In  thin  subjects  its 
lower  part  can  be  defined.  Besides  the  tendon  and  its  synovial  sheath,  the  inser- 
tion of  the  latissimus  dorsi,  the  humeral  branch  of  the  acromio-thoracic  artery,  and 
the  anterior  circumflex  artery  run  in  the  groove.  When  the  fingers  are  placed  on 
the  acromion,  and  the  thumb  in  the  axilla,  the  lower  edge  of  the  glenoid  cavity 
can  be  felt;  and  if  the  humerus  be  rotated  (the  elbow-joint  being  flexed),  the  head 
of  the  humerus  can  be  felt  also. 

The  characteristic  roundness  of  the  shoulder  is  due  to  the  deltoid,  supported 
by  the  head  of  the  humerus  and  the  tuberosities  (fig.  715).  Close  to  the  clavicle, 
between  the  contiguous  origins  of  the  pectoralis  major  and  deltoid,  is^  the  infra- 
clavicular fossa,  in  which  lie  the  cephalic  vein  and  the  humeral  branch, of  the 
acromio-thoracic  artery.  On  pressing  deeply  here,  the  coracoid  process  can  be 
made  out  if  the  muscles  are  relaxed  and  the  axillary  artery  compressed  against  the 
second  rib. 

On  raising  the  arm  and  abducting  it,  the  different  parts  of  the  deltoid  can  often 
be  made  out — viz.  fibres  from  the  lower  border  of  the  spine  of  the  scapula,  the 
outer  edge  of  the  acromion,  and  the  outer  third  or  more  of  the  front  of  the  clavicle; 


Fig.  712.— Transverse  Section  throx^gh  the  Right  Shoulder-joint,  showing 
THE  Structures  in  contact  with  it.     (Braune.) 


ACROMION 
Supra -spinatus 

Trapezius 
Infra-apinatus   - 

Teres  minor 

Teres  major 
Latissimus  dorsi 


Deltoid 
Pectoralis  major 


Axillary  vessels  and  NER  VES 


Tendon  of  subaoapularis  blended  with 
the  scapular  ligament 
Coraeo-braehialis  and  short  head  of  biceps 


the  characteristic  knitting  of  the  surface  owing  to  the  presence  of  muscular  bundles, 
separated  by  depressions  caused  by  the  tendinous  septa,  will  also  be  seen.  The 
muscle  will  be  marked  out  by  a  base-line  reaching  along  the  above  bony  points, 
and  two  sides  converging  from  its  extremities  to  the  apex,  a  point  on  the  outer 
surface  of  the  humerus,  about  its  centre.  To  map  out  the  pectoralis  major,  a 
line  should  be  drawn  down  the  lateral  aspect  of  the  sternum  as  far  as  the  sixth 
costal  cartilage,  and  then  two  others  marking  the  borders  of  the  muscle — the  upper 
corresponding  to  the  deltoid,  the  lower  starting  from  the  sixth  cartilage,  and  the 
two  converging  to  the  folded  tendon,  which  is  inserted  as  a  double  layer  into  the 
outer  Incipital  ridge.  The  pectoralis  minor  will  Ije  marked  out  by  two  lines,  from 
the  upper  border  of  the  third  and  the  lower  border  of  the  fifth  rib,  just  external  to 
their  cartilages,  and  meeting  at  the  coracoid  process.  The  lower  line  gives  the  level 
of  the  long  thoracic  artery;  the  upper,  where  it  meets  the  line  of  the  axillary 
artery,  that  of  the  acromio-thoracic. 

When  the  arm  is  abducted  and  the  humerus  rotated  a  little  outwards,  the  promi- 
nence of  a  well-developed  coraco-brachialis  comes  into  view;  a  line  drawn  from 
the  centre  of  the  clavicle  along  the  inner  border  of  this  muscle  to  its  insertion  into 
the  humerus  gives  the  line  of  the  axillary  artery. 

The  depression  of  the  axilla  is  best  marked  when  the  arm  is  raised   from  the 


THE  SHOULDER 


llol 


side  to  an  angle  of  about  45°,  and  when  the  muscles  bounding  it  in  front  and 
behind  are  contracted.  In  proportion  as  the  arm  is  raised,  the  hollow  becomes 
less,  the  head  of  the  humerus  now  projecting  into  it.     When  the  folds  are  relaxed 


Fig.  713. — The  Brachial  Artery. 
(From  a  dissection  iu  the  Mu.seuni  ol"  the  Koyal  College  of  Surgeons.) 
Suprascapular  artery  and  nerve 


Subscapular  vessels 


CIRCUMFLEX 
NERVE 


SUBSCAPl'LAR 
NERVE 


ULNAR  NERVE 
Triceps 

Jiifevior  profunda  artery 


INTERNA  L  CUTA  NEO  US 
NER  VE 

Brachial  artery 
MEDIAN  NERVE 


Ulnar  artery 


Biceps 


Axillary  artery  and 

vein 
MISCULO-CUTA- 
NEOVS  and  in- 
ternaUu  outt-r 
head  of  MEDIAN 
NER  VE 
One  of  the  brachial 
VPtns 

Coraeo-brachialis 


Cephalic  vein 
Anaslomolica  magna  artery 


MUSCUL  0-CUTA  NEO  US 
NERVE 


Supinator  longus 
Radial  rein 


Median  vein 


Radial  arlfni 


by  bringing  the  arm  to  the  side,  the  fingers  can  be  puslied  into  the  space  so  as  to 
examine  it. 

The  circumflex  nerve  and  posterior  circumflex  vessels  wind  round  the  humerus 
under  the  deltoid,  a  little  above  the  centre  of  this  muscle. 


1152 


SURGICAL   AXD    TOPOGRAPHICAL  AXATOMY 


To  trace  the  synovial  membrane  of  the  shoulder-joint  is  a  comparatively 
simple  matter  (fig.  715).  Covering  both  aspects  of  the  free  edge  of  the  glenoid 
ligament,  it  lines  the  inner  aspect  of  the  capsule  whereby  it  reaches  the  articular 


Fig.  714. — Sectiox  through  the  Middle  of  the  Right  Upper  Arm. 

( Heath. ) 


Cephalic  vein 

Ml'SCULO-CVTANEOUS 
NERVE 
Bracbialis  anticus 


MUSCULO-SPIRAL  NERVE 

Superior  profunda  vessels 


Triceps,  with  fibrous  intersection 


Biceps 

Brachial  vessels 

MEDIAN  NERVE 
ULNAR  NERVE 

Basilic  vein,  iiith  internal 
cutaneous  nerves 


Inferior  profunda  vessels 


margin  of  the  head  of  the  humerus;  there  is  a  distinct  reflection,  below,  from 
the  capsule  on  to  the  humeral  neck  before  the  rim  of  the  cartilage  is  reached. 
An  extensive  protrusion  of  synovial  membrane  takes  place  in  the  fonn  of  a  synovial 
bursa,  at  the  inner  and  anterior  part  of  the  capsule,  near  the  root  of  the  coracoid 


Fig. 


715. — Diagrammatic  Sectiox  of  Shouldee  through  Bicipital  Gkoove. 

(Anderson.) 


Deltoid 

SUBACROMIAL  BURSA 


CAPSULE  OF  SHOULDER-JOINT 
Long  tendon  of  biceps 


Synovial  membrane  lining 
oap3ul3  and  synovial 
membrane 


Extra-articular  portion  of 
biceps  tendon 


Glenoid  ligament 


GLENOID  CAVITY 


Glenoid  ligament 


Inner  fold  of  capsule  and 
synovial  membrane 


process  under  the  tendon  of  the  subscapularis.  Another  jirotrusion  takes  place 
between  the  two  tul)erosities  along  the  bicipital  groove,  as  low  as  the  insertion  of 
the  pectoralis  major.  A  third  synovial  protrusion  may  be  seen,  but  not  frequently, 
at  the  outer  or  posterior  aspect,  in  the  form  of  a  bursa,  under  the  infraspinatus 


THE  SHOULDER 


1153 


tondon.     Thus  the  continuity  of  the  capsule  is  interrupted  by  two  and  sometimes 
three  apertures. 

The  shaft  of  the  humerus  is  wt-ll  covered  by  muscles  in  the  greater  part  of 
its  extent,  especially  alxtve.  Below  tlie  insertion  of  the  deltoid,  the  outer  border 
of  the  bone  can  be  traced  downwards  into  tlie  external  supracondyloid  ridge.  The 
inner  border  and  ridge  are  less  prominent.  Attaeiied  to  these  ridges  and  borders 
are  the  intermuscular  septa,  each  lying  between  the  triceps  and  brachialis  anticus, 
and  the  outer  one  giving  origin  to  the  brachio-radialis  (supinator  longus;  and 
extensor  carpi  radialis  longior  as  well.      The  outer  septum  is  perforated  by  the 


Fig.  716.— Back  View  of  the  Scapular  Muscles  and  Triceps. 


Supra-spinatus 


Iafra-spiaatu3 
Teres  minor 


Teres  major 


Long  head  of  triceps 


Outer  head  of  triceps 


Inner  head  of 


superior  profunda  vessels  and  the  musculo-si)iral  nerve,  the  inner  by  the  inferior 
profunda  and  anastomotica  magna  arteries  and  tlie  ulnar  nerve.  On  either  side 
of  the  well-known  prominence  of  the  biceps  is  a  furrow.  Along  the  outer  ascends 
the  cephalic  vein.  The  inner  corresponds  t<»  the  line  of  the  basilic  vein  which  lies 
superficial  to  the  deep  fascia  below  the  middle  of  tlie  arm,  and  superficial  and 
internal  to  the  brachial  vessels  and  median  nen-e. 

A  line  drawn  along  the  inner  edge  tif   the    biceps  from  the  insertion  of  the 

teres  major  to  the  middle  of  the  bend  of  the  elbow  corresponds  to  the  brachial 

artery.     In  the  u]tper  two-thirds,  this  artery  can  be  comj^ressed  against  tlie  bone 

by  pressure  outwards;  in  its  lower  third   the  humerus  is  behind  it.  and  })ressure 

73 


1154 


SURGICAL  AXD    TOPOGRAPHICAL  ANATOMY 


should  be  made  Imckwards.  The  superior  piofunda  comes  off  from  the  liighest 
part  of  the  artery  and  courses  with  tlie  musculo-sj)iral  nerve  (tig.  714);  the 
nutrient  artery  arises  opposite  the  middle  of  the  humerus;  the  inferior  ]>rofunda 
below  the  middle,  and  courses  with  the  ulnar  nerve  through  the  intermuscular 
septum  to  the  l)ack  of  the  internal  condyle.  The  anastomotica  is  given  from 
one  to  two  inches  above  the  bend  of  the  ellM)W. 

The  centre  of  the  arm  is  a  landmark  for  many  anatomical  structures.  On  the 
outer  side  is  the  insertion  of  the  deltoid;  on  the  inner  that  of  the  coraco-brachialis. 
The  basilic  vein  and  the  nerve  of  Wrisberg  here  perforate  the  deep  fascia,  going  in 
reverse  directions.  The  inferior  profunda  is  here  given  off  from  the  Ijrachial;  the 
median  nerve  also  crosses  the  artery,  and  the  ulnar  nerve  leaves  the  inner  side  of 
the  vessel  to  pass  to  the  inner  aspect  of  the  limb. 

The  brachialis  anticus  can  be  mai3i)ed  out  by  two  pointed  processes  which 
surround  the  insertion  of  the  deltoid,  and  which  pass  downwards  into  lines  corre- 
sponding to  the  two  intermuscular  septa,  and  then  converge  over  the  front  of  the 
elbow  to  their  insertion  into  the  coronoid  process. 

The  median  nerve  can  be  traced  by  a  line  drawn  from  the  outer  side  of  the  third 
part  of  the  axillary  and  first  part  of  the  brachial  artery,  across  this  latter  vessel 
about  its  centre,  and  then  along  its  inner  border  to  the  forearm,  where  it  passes 
between  the  two  heads  of  the  pronator  radii  teres. 

The  ulnar  nerve  lies  to  the  inner  side  of  the  above  arteries  as  far  as  the  middle 
of  the  arm,  where  it  leaves  the  brachial  to  course  more  inwards  and  perforate  the 
internal  intermuscular  septum  and  get  to  tlie  l)ack  of  the  internal  condyle. 


Fig.  717.— Vertical  Sectiox  of  the  Elbow.     (One-half.)     (Braune. 


Tendon  of  biceps  -- 

Brachio-radialiB  _ 
RADIAL  SERVE  - 
Brachialis  anticus  -- 

Extensor  carpi  radialis  longior  - 


Pronator  teres 
MEDIAN  NERVE 

—  —  Flexor  carpi  radialis 

-' Internal  lateral  ligament 

'  —   ULNAR  NERVE 

OLECRANON 

Tendon  of  triceps 


I 


The  musculo-spiral  nerve  can  be  traced  by  a  line  beginning  behind  the  third 
part  of  the  axillary  artery,  then  carried  vertically  down  behind  the  uppermost  part 
of  the  brachial,  and  then,  just  below  the  posterior  border  of  the  axilla,  curving 
backwards  behind  the  humerus  and  slightly  downwards,  just  below  the  insertion  of 
the  deltoid.  Thus,  passing  from  within  outwards  and  from  before  backwards  in  its 
groove  Avith  the  superior  profunda  vessels,  it  again  comes  to  the  front  by  perforating 
the  external  intermuscular  septum  at  a  point  about  opposite  to  the  junction  of  the 
middle  and  lower  thirds  of  the  arm,  and  passes  down  in  front  of  the  external  supra- 
condyloid  ridge,  lying  here  between  the  brachio-radialis  and  brachialis  anticus.  to 
the  level  of  the  external  condyle,  where  it  divides  into  radial  and  posterior  inter- 
osseous. The  former  of  these  accompanies  the  radial  artery  to  the  front  of  the  arm, 
the  latter  travels  l)ackwards  to  the  back  of  the  forearm. 

On  the  back  of  the  arm  is  the  triceps  muscle,  with  its  three  heads  and  tendon 
of  insertion,  all  ])rought  into  relief  in  a  muscular  subject  when  the  forearm  is 
strongly  extended.  Of  the  three  heads,  the  inner  is  the  least  distinct,  arising  below 
the  musculo-si)iral  groove,  reaching  to  each  intermuscular  septum,  and  tapering 
away  above  as  higli  as  the  teres  major.  The  outer  head,  arising  above  the  groove 
as  high  as  the  great  tuberosity,  appears  in  strong  relief  just  below  the  deltoid; 
while  the  middle  or  long  head,  arising  from  the  scajiula  just  below  the  glenoid 
cavity,  appears  between  the  teres  muscles.  The  tendon  of  insertion,  passing  into 
the  upper  and  back  part  of  the  olecranon  over  a  deep  bursa,  is  shown  by  a  some- 
what depressed  area. 


THE  ELBOW 


1155 


THE  ELBOW 

The  bony  points,  condyles,  olecranon,  and  head  of  radius,  and  their  relation 
to  one  anotiur,  should  be  carefully  studied.   The  internal  condyle  is  the  more  ])roni- 


FiG.  718. — Longitudinal  Section  of  the  Elbow-joint.     (One  half.)    dirauue. ) 


Tricepa 


Extensor  carpi  ulnari^ 


Biceps 


Brachialia  amicus 


MUSCULO-SPIRAL  SER  VIC 
Brachio-radialis 

Supinator  brevia 

Extensor  carpi  radialis  longior 


Fro.  719. — Bend  ok  the  Elbow.     (Uue-luilf.)     (Blaudiu.) 

ISTERXAL  CUTANEOUS  NERVE 


Brachial  aponeurosis 
Basilic   vein  — 


Median  basilic  vein  — 


Epitrochlea  • — 
Abnormal  vessel  — 


Superficial  ulnar  vein 
Brachial  artery  and  renit  coiniles 


Bicipital  fascia 


Anti-brachial   aponeurosis  - 


Brachial  aponeurosis 


Ci-plialic  vein 


fUTANEOrS  BRANCH    OF 
MUSCULiJ-SPIRAL  NERVE 


Slip  of   brachial   aponeurosis 
^^      passing  to  muscles  attached 
to  external   condyle 

—  EXTERNAL  CUTANEOUS 
NERVE 

-  Abnormal  vessel 


Median  cephalic  vein 


up}       ■  Superficial  radial  vein 

—  A'ti-brachial  aponeurosis 


Deep  radial  vein       Meaian  vein 


inent  of  the  two.  is  directed  backwards  as  well  as  inwards,  and  lies  a  little  alwve  its 
fellow.      AV)ove  it  can  be  traced  ui)wards  the  suiiracondyloid  ridge  and  corresnond- 


1156 


SURGICAL  AXD    TOPOGRAPHICAL  AXATOMY 


ing  septum.  The  external  condyle  is  more  rounded,  and  thus  less  promineni;  below, 
and  a  little  behind  it,  the  head  of  the  radius  can  be  felt  moving  under  the  capi- 
tellum  when  the  forearm  is  supinated  and  flexed.  A  depression  marks  this  si)ot 
and  corresponds  to  the  interval  between  the  anconeus  and  brachio-radialis  and 
exterior  carpi  radialis  longior;  at  the  back,  the  upper  part  of  the  olecranon  is 
covered  by  the  triceps.  The  lower  is  subcutaneous,  and  separated  from  the  skin 
by  a  bursa.  If  the  thumb  and  second  finger  be  placed  on  the  condyles  and 
the  index  on  the  tip  of  the  olecranon,  and  the  forearm  completely  extended,  the 
tip  of  the  olecranon  rises  so  as  to  be  on  the  Hue  joining  the  two  condyles.     In 


Fig.  720. — The  Bexd  of  the  Elbow  with  the  Superficial  Veins. 
(From  a  dissection  by  Dr.  Alder  Smith  in  the  Museum  of  St.  Bartholomew's  Hospital.) 


MEDIAN  NER  \'E 

Posterior  branch  of 

anaslomotica  magna 

BRANCHES  OF      ' 

INTERNAL    CUT  A 

NEOUS  NERVE 

Posterior  ulnar  vein, 

Brachialis  antieus 

Anterior  branch  of 
iinastoniotica  magna 
Anterior  ulnar  vein, 

Median  basilic  vein 

MUSCULAR  BRANCH 
OF  MEDIAN  NER  VE 


Tendon  of  biceps 


Bicipital  fascia 


Brachialis  antieus 

Deep  median  vein 

Ulnar  artery 

Pronator  teres 


Radial  artery 


Biceps 

Internal  vena 
comes  of 
brachial  artery 
Basilic  vein 

Brachialis 
antieus 

Cephalic  vein 

Brachial  artery 
EXTERNA  L 

CUTANEOUS 

NERVE 

Miiscnio-spiral 
n.  and  ascending 
branch  of  railial 
reciirrint  artery 
Radial  vein 
Median  cephalic 

vein 
Ascending  br.  of 
radial  recurrent 
RADIAL 

NER  VE 
Radial  recurrent 

artery 
Supinator 

longus 
Descending  br. 

of  radial 

recurrent 
Median  vein 

RADIAL 
NER  VE 


flexion  at  a  right  angle,  the  olecranon  is  below  the  line  of  the  condyles,  and  in 
complete  flexion  (piite  in  front  of  them.  Between  the  inner  condyle  and  olecranon 
is  a  pit,  in  which  lie  the  ulnar  nerve  and  the  anastomosis  between  the  inferior 
profunda  and  the  posterior  ulnar  recurrent  arteries.  The  coronoid  process  is  so 
well  covered  by  muscles,  vessels,  and  nerves,  that  its  position  cannot  be  distinctly 
made  out. 

Swelling,  due  to  effusion  into  the  joint,  appears  on  either  side  of  the  triceps 
tendon,  and  soon  obliterates  tlie  depression  below  the  external  condyle.  A  super- 
ficial swelling  over  the  tip  of  the  olecranon  is  due  to  effusion  into  the  bursa  between 
the  soft  parts  and  tliat  bone.     A  deeper,  less  easily  detined,  swelling  in  the  same 


THE  ELBOW 


U" 


region  is  due  to  inllnniiiiation  of  the  hursa  betwoon  the  olecranon  and  the  triecps. 
A  swelling  on  the  iiuifr  side  of  the  elbow-joint,  if  painful  aud  acc<»ni|)anic<l  bv 
inrtanniiation  of  the  skin,  may  be  due  to  mischief  iu  the  epitrochlear  gland 
situated  just  above  the  internal  condyle,  and  reccnviug  ]ym])haties  from  the  inner 
border  of  the  forearm  and  the  two  imier  fingers. 

The  hollow  in  front  of  the  elbow, — The  delicacy  of  the  skin  liere  must 
always  be  borne  in  mind  in  tlie  apitlication  of  splints.  The  |\/|-like  arrangement 
of  the  superficial  veins  as  usually  deseril)ed  is  by  no  means  constant  (figs.  719, 
720).  The  median  basilic  is  the  vein  usually  chosen  for  venesection,  owing  to  its 
larger  size  and  its  being  firmly  supported  by  the  subjacent  bicipital  fascia  which 
sc^parates  it  from  the  brachial  artery;  but  the  median  cephalic  is  the  safer.  The 
median  basilic  is  crossed  l)y  l.)ranches  of  the  internal  cutaneous  nerve,  while  those 

Fig.  721. — The  Brachial  Artkry  at  thk  Bkxd  ok  the  Kf.bow. 


POSTERIOR    BRANCH 
OF  IMKRNAL 
CUTANEOUS  NERVE 
ANTERIOR    BRANCH 
OF  INTERNAL 
CUTANEOUS  NERVE 


Brachial  artery    — f 


BRANCH  TO 
PRONATOR  TERES 


Bicipital  fascia,  cut 


Pronator  radii  teres 
muscle 


MEDIAN  NERVE 


Ulnar  arUry 


Biceps  muscle 


IIRANCII  OF  MUSCULO- 
SPIRAL  NERVE  TO 
SUPINA  TOR  LONO  US 

RADIAL  NERVE 

Radial  recurrent  artery 

„,„l  POSTERIOR 

J. \TEl:  OSSEOUS 

NERVE 
Tendon  of  biceps 

.1/ 1  SCI  'L  0-CU  TA  NEO I  '.V 
NERVE 

Supinator  longus  muscle 


-   Radial  artery 


of  the  musculo-cutaneous  lie  under  the  median  cephalic.  In  the  semiflexed  position, 
the  fold  of  the  elbow  is  seen,  a  little  above  the  level  of  the  joint.  This  forms  the 
base  of  the  triangular  fossa  l)elow  the  elbow,  the  outer  side  corresi)onding  to  the 
brachio-radialis,  the  inner  to  the  pronator  radii  teres,  and  the  ajiex  to  the  meeting 
of  these  muscles.  The  tendon  of  the  bice])S  can  ])e  easily  made  out  in  the  centre 
of  the  fossa,  giving  off  al)ove  the  bicipital  fascia  from  its  inner  side  t(j  fasten  down 
the  flexors  of  the  forearm.  Under  the  tendon  on  its  inner  side  lie  the  brachial 
artery  and  the  median  nerve  for  a  short  distance.  The  musculo-spiral  lies  outside 
the  fossa,  between  the  brachio-radialis  and  the  brachialis  anticus.  The  brachial 
usually  bifurcates  opposite  to  the  neck  of  the  radius. 

The  arterial  anastomoses  about  the  elbow-joint  are  as  follow:  The  radial 
recurrent   runs   u})  under  cover  of   the  braehio-ratlialis  to  anastomose  with   the 


1158 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


superior  profunda.  The  anterior  ulnar  recurrent  ascends  on  the  brachialis  anticus 
to  join  the  anastomotica  magna  under  the  jironator  radii  teres.  The  posterior  uhiar 
recurrent  makes  for  the  interval  between  the  internal  condyle  and  the  olecranon,  to 
join  with  the  inferior  profunda  and  anastomotica  magna.  The  posterior  interosseous 
recurrent  ascends,  between  the  supinator  brevis  and  the  anconeus,  to  anastomose 
on  the  back  of  the  external  condyle  with  the  superior  profunda.  It  further  joins, 
by  a  large  anastomotic  arch  across  the  back  of  the  joint,  with  the  anastomotica 
magna  and  posterior  ulnar  recurrent. 

Fig.  722. — Diagram  of  the  Anastomoses  of  the  Brachial  Artery. 
(^MacConnac  ami  AiHler>ou. ) 


Anterior  circumflex 
Posterior  circumflex 


Superior  radial  collateral  {exces- 
sively large) 


Superior  profunda 


External  posterior  articular  branch 
of  superior  profunda 


External  ayiterior  articular  branch 
of  superior  profunda 


Posterior  interosseous  recurrent 


Padial  recurren 
Posterior  interosseous  recurrent 


Acroniio-lhoiacic 

Long  thoracic 

Subscapular 
Dorsalis  scapula 


Posterior  scapular 


Anasloniolica  magna 

Transverse  branch  of  anastomotica  magna 


tiiiasloynosis  of  anterior  ulnar  recurrent  tvith 
auastomolic 

Anastomosis  of  posterior  ulnar  rectirrent  with 

anastomotic 


Anterior  ulnar  recurrent 
Posterior  ulnar  recurrent 


I 


Posterior  interosseous  from  common  interosseotis  of  ulnar 


Tlie  following  table  of  the  vessels  anastomosing  on  the  front  and  back  of 
the  condyles  will  be  useful: — 


Internal  condyle 


r  Front. — Anastomotica    magna.       Anterior     ulnar     recurrent. 
j  Inferior  profunda. 

Back. — Anastomotica    magna.      Posterior    ulnar    recurrent. 
Inferior  profunda. 


C  Ffont. — Superior  profunda.      Radial  recurrent. 
External  condyle  -<  5ocA-. — Superior    profunda.     xVnastomotica    magna.      Inter- 
(,  osseous  recurrent. 


THE  FOREARM 


1159 


It  will  be  seen  that  the  anastomotica  magna  is  the  artery  most  largely  employed, 
distributing  branches  everywhere,  save  to  the  front  of  the  external  condyle. 


THE    FOREARM 

Bony  landmarks. — The  ulna  can  be  easily  traced  down  from  the  olecranon  to 
the  styloid  i)rocess;  the  bone  becomes  somewliat  rounded  below,  and  lies  between 
the  flexor  and  extensor  carpi  ulnaris.  The  tip  of  the  styloid  process  corresponds 
to  the  inner  end  of  the  line  of  the  wrist-joint.  The  radius  is  covered  above  by  the 
brachio-radialis  and  radial  extensors  of  the  carpus,  and  the  outline  of  the  bone  is 
less  easily  followed.  Its  styloid  process  is  readily  made  out  below,  a  finger's 
breadth  above  the  thenar  eminence.  It  is  placed  on  a  slightly  lower  level  than 
that  of  the  styloid  process  of  the  ulna.  Thus,  a  line  drawn  straight  between  the 
two  processes  would  fall  a  little  below  that  of  the  wrist-joint,  this  being  shown  l)y 
a  line  drawn  between  the  two  processes  forming  a  slight  curve,  with  its  concavity 


Fig.  723.~Section  THBouGn  the  >rinni.E  of  the  Right  Forearm.     (Heath.) 


Anterior  inter- 
osseous  ve^feU 
and  .VEUVE 

Radial  vesseU 
and  SERVE 


Pronator  teres 


Brachio-radialie 


Supinator  brevis 

Exiensor  carpi  radialis 
lougior  and  brevior 

Extensor  ossis  metacarpi 
pollicis 


Flexor  sublimis  digitorum 


Flexor  carpi  ulnaris 


Extensor  communis  digitorum      |       '  Ulnar  lessels  anil  SERVE 

Extensor  carpi  ulnaris       I  ^^^^^^  profundus  digitorum 

Posterior  interosseous  vessels  and  XERVE         VEDH  V  \ER\'E 
Extensor  secucdi  luternodii  pollicis 


downwards  (corresponding  to  the  concavity  of  the  lower  surface  of  the  radius  and 
fibro-cartilage)  aV)out  half  an  inch  (12  mm.)  above  the  straight  line  given  above. 

The  radial  styloid  process  is  covered  by  the  extensor  ossis  metacarpi  and 
primi  internodii  pollicis,  while  farther  out  lies  that  of  the  extensor  secundi.  The 
bones  are  nearest  to  each  other  in  complete  pronation,  and  farthest  apart  in  com- 
l)lete  supination.  On  section,  the  l)ones  are  found  at  every  point  nearer  to  the 
back  than  to  the  front  of  the  limb,  but  increasingly  so  above.  '  The  lower  the 
section  proceeds  down  the  limb,  the  less  will  the  bones  be  covered  at  the  sides,  and 
the  more  equally  will  the  soft  parts  be  distributed  about  the  anterior  and  posterior 
aspects  of  the  limb.  It  will  be  noticed  tliat  wliere  one  bone  is  the  most  substantial, 
the  other  is  the  more  slender,  as  near  the  ell)ow  and  wrist;  and  that  it  is  about  tlie 
centre  of  the  limb  that  the  two  are  most  nearly  of  equal  strength  '  (Treves).  "\\'h(n 
the  limb  is  pronated,  the  interosseous  space  is  narrowed;  in  supination  and  the  mid- 
position  it  is  widened  out.  In  pronation,  Vtoth  styloid  jiroeesses  can  be  distinctly 
made  out;  in  sui)ination,  that  of  the  radius  is  most  distinct,  as  now  the  skin  and 
soft  ])arts  are  stretched  and  raised  over  that  of  the  ulna. 


1160 


SURGICAL  AXD    TOPOGRAPHICAL  A.XATOMY 


Fig.  724. — The  Arteries  of  the  Forearm  with  the  Superficial  Palmar  Arch. 


Bicepa 


Brachialis  anticua 

Tendon  of  biceps 

Semilunar  fascia  of  biceps 

Radial  recurrent  artery 

Supinator  longus 

HA  DIAL  NERVE 
Radial  artery 


Flexor  longus  pollicia 


Pronator  quadratus 

Radial  artery  winding  to  back  of 
wrist  under  extensors  of  thumb 


Superficial^  vohe 


Superficial  palmar  arc /i  — k^— ^ 


Brachial  artery 
Basilic  rein 

ULNAR  KER  VE 

MEDIAN  NERVE 

Anastomotica  magna 
Brachial  artery 

INTERNAL  CONDYLE 


Ulnar  artery 

Pronator  radii  teres 

Flexor  carpi  ulnaris 

Flexor  sublimis  digitorum 
Flexor  carpi  radialis 
Palmaris  longus 

MEDIAN  NERVE 
Flexor  sublimis  digitorum 
Ulnar  artery 

PISIFORM  BONE 

Anterior  annular  ligament 
Palmaris  brevis 


THE  FOREARM 


llGl 


Soft  parts. — Along  the  outer  border  descend  the  brachio-radialis  and  radial 
extensors  of  the  carpus,  fleshy  above,  tendinous  below.  .  About  an  inch  and  a  half 
above  the  styloid  process  of  the  radius,  a  fleshy  swelling  directed  obliquely  down- 
wards and  forwards  from  behind,  across  this  outer  border  of  the  forearm,' denotes 
the  extensors  of  the  thumlj  crossing  those  of  the  carpus. 

Along  the  inner  border  is  the  fleshy  mass  of  the  i)ronator  teres  and  flexors,  the 
ulna  being  covered  by  the  flexor  carpi  ulnaris  and  flexcjr  profundus.  Tlip  tendon 
of  the  pronator  is  inserted  into  the  radius  a  little  below  its  centre — a  point  <^f 
importance  in  the  treatment  of  fractures,  and  in  amputation.  The  flexor  carpi 
ulnaris  tendon  can  ])e  felt  just  alwve  the  wrist  making  for  the  pisiform  bone;  and 
just  external  to  it  lies  the  ulnar  artery,  about  to   pass  over  the  anterior  annular 


Fig.  725.— Distribution  of  Cutaneous  Nekves  ox  thk  Anterior  and  Posterior  Aspects 

OF  THE  Superior  Extremity. 


J.VTESXAL 
CCTANEOUS  OF 
MCSCCLO- 
SPIRAL 


INTERNAL 
CUTANEOUS 


PALyfAR 

CUTANEOUS  OF 

MEDIAN 
PALMAR 

CUTANEOUS  OF 

ULNAR 


SUPRA- 

ACROMIAL 


CIRCUMFLEX 

ISTBRCOSTQ- 

HUMERAL 

CIRCUM-] 
TWIG  OF  FLEX     , 

INTERNAL 

CUTANEOUS 

BXTERXAL 
rCTAXEOUS  OF 

MUSCULO- 

SPIRAL 


MUSCULO- 
CUTANEOUS 


EXTERNAL 

CUTANEOUS 

OF 

MUSCULO- 

SPIRAL 


RADIAL 


PALMAR 

CUTANEOUS 
OF  RADIAL 


SUPRA- 
ACROMIAL 


INTERNAL 
CUTANEOUS  OF 

MUSCULO- 

SPIRAL 
INTERCOSTO- 

H  UMBRA  L 


NER VE  OF 
WRISIiERG 


INTERNA  L 
rUTANEOUS 


ligament.  The  course  of  the  artery  is  denoted  by  a  line  drawn  from  the  front  of 
the  internal  condyle  to  the  outer  edge  of  the  pisiform  bone.  If  it  be  drawn  from 
the  bifurcation  of  the  brachial,  this  line  must  in  its  upper  third  be  made  stronglv 
convex  inwards,  in  order  to  mark  the  upper  part  of  the  artery,  here  thickly  cov- 
ered by  muscles.  The  line  of  the  ulnar  nerve  is  one  drawn  from  the  interval 
between  the  internal  condyle  and  the  olicninon  to  the  inner  side  of  the  ulnar  arterv 
ju.st  above  the  wrist.  The  nerve  joins  the  artery  at  the  junction  of  the  upper  and 
middle  thirds  of  the  forearm.  The  median  nerve  runs  in  a  line  drawn  from  the 
inner  side  of  the  brachial  artery,  in  the  elliow  triangle,  to  a  point  beneath,  or  just 
to  the  inner  side  of,  the  palmaris  longus  just  al)Ove  the  wrist.  The  radial  artery 
will  be  marked  by  a  line  drawn  from  the  centre  of  the  bend  of  the  elljow  (where 
the  brachial  artery  divides  opposite  to  the  neck  of  the  radius)  to  a  point  just 


1162 


SURGICAL  AND  TOPOGRAPHICAL  ANATOMY 


internal  to  the  radial  styloid  process  descending  along  the  inner  edge  of  the  brachio- 
radialis.     The  radial  nerve  Avill  be  marked  by  the  same  line  (it  lies  just  external 


External  jvgular  vei:. 


Fig.  726.— Superficial  Veins  and  Lymphatics  of  the  Foreakm  and  Arm. 

Pectoralls  major,  hooked  up 

Supraclavicular  gland 
Jugulo-cephalic  vein 


Peetoralis  major 


Deltoid  muscle 


Lymphatics  from  side  of  chest 


Pectoral  glands 


Basilic  vein 


Epitrochlear  gland 

Posterior  superficial  ulnar 
rein 
Median  basilic  vein 
Inner  set  of  superficial  lym- 
phatics of  forearm 

Deep  median  vein 

JNTERXAL  CUTANEOUS 
XERVE 

Anterior  superficial  ttlnar 
rein 


Median  set  of  superficial  lym- 
phatics of  forearm 


Lymphatics  accompanying 
cephalic  vein 

Axillary  glands 


Cephalic  vein 


Lymphatic  vessels  of  inner 
side  of  arm 


Biceps,  exposed 

MUSCULO-CUTAXEO  US 
XERVE 

Brachial  artery 
Bicipital  fascia 
Median  cephalic  vein 

Superficial  radial  vein 
Superficial  median  vein 


Outer  set  of  superficia!  li/m- 
phatic  vessels  of  forearm 


to  the  artery)  for  its  upper  two-thirds;  it  then  leaves  the  artery  about  three  inches 
above  the  wrist-joint,  and  passes  to  the  back  of  the   forearm  under  the  tendon  of 


THE   WRIST  AXD   HAXD 


1163 


the  brachio-radialis.  The  anterior  interosseous  artery  runs  down  on  the  inter- 
osseous meml)rane  and  passes  to  tlie  back  of  the  forearm  h»y  perforating  it  below. 
The  posterior  interosseous  lies  between  the  su])erlicial  and  deej)  extensors. 
These  small  arteries  reinforce  the  palmar  through  the  carpal  arches,  and  thus  bring 
down  blood  after  ligature  of  the  trunks  above. 

The  front  of  the  forearm  is  supplied  by  the  nmsculo-cutaneous  on  the  outer,  and 
the  internal  cutaneous  on  the  inner  side;  just  above;  the  wrist  the  palmar  cutaneous 
branches  of  the  median  and  ulnar  perforate  the  deep  fascia  (fig.  725).  The  back 
of  the  forearm  is  supplied  by  the  musculo-spiral  and  posterior  branches  of  the 
musculo-cutaneous  externally,  and  the  posterior  branches  of  the  internal  cutaneous 
internally  (fig.  725).  The  arrangement  of  the  superficial  lymphatics,  shown  in  fig. 
726,  may  be  briefly  described  as  folloAvs: — 

The  lymphatics  of  the  upper  extremity  are  superficial  and  deep ;  the 
former  run  with  the  superficial  veins,  the  latter  with  the  dee])  vessels.  As  a  rule, 
there  are  no  glands  below  the  elbow.  The  majority  of  the  lymphatics  open  into 
the  axillary  glands,  and  terminate  on  the  left  side,  in  the  thoracic  duct,  on  the 
right,  in  the  right  lymphatic  duct.  A  few,  accomjianying  the  cephalic  vein,  reach 
the  subclavian  or  infraclavicular  glands,  and  thus  communicate  with  the  Ij'm- 
phatics  of  the  neck. 


Fig.  727. — Relation  of  the  Palmae  Arches  to  the  Folds  of  the  Palm.     (Tillaux.) 


Superficial  palmar  arch 

Deep  palmar  arch 

Superflcialis  voice 


Inferior  fold 

Middle  fold 
Superior  fold 


Radial  artery 


Ulnar  artery 


THE  WRIST  AND  HAND 

Bony  points. — On  the  inner  side,  the  styloid  process  and,  farther  outwards,  the 
head  of  the  ulna  can  be  made  out.  On  tlie  outer  side,  the  radial  styloid  process 
descends  about  half  an  inch  (12  mm. )  lower  than  that  of  the  radius,  and  is  somewhat 
anterior  to  it.  Abduction  of  the  hand  is  thus  less  free  than  adduction.  In  Colles' 
fracture,  the  line  of  fracture,  usually  transverse,  crosses  the  radius  aliout  an  inch 
above  the  apex  of  the  styloid  jn-ocess.  Between  the  apex  of  the  styloid  process 
and  the  ball  of  the  thuml)  a  bony  ridge  can  ])e  felt,  with  some  ditlieulty,  formed  by 
the  tubercle  of  the  scaphoid  and  the  ridge  of  the  trapezium.  At  a  corresjionding 
])oint  on  the  inner  side  the  pisiform  can  l)e  more  readily  distinguished.  On  the 
front  of  the  metacarpo-phalangeal  joint  of  the  thuml)  the  sesamoid  bones  can  be 
distinguished. 

At  the  back  of  the  wrist  and  hand  the  cuneiform  bone  can  be  felt  below  the 
head   of  the  ulna;  and  more  towards  the  middle  line  the  prominence  of  the  os 


1164 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


magnum,  which  supports  the  third  or  longest  digit,  and  is  the  bone  of  the  carpus 
most  exposed  to  injury.  A  line  drawn  from  the  base  of  the  fifth  metacarpal  bone 
to  the  radio-carpal  joint,  slightly  curved  downwards,  will  give  the  line  of  the 
carpo-metacarpal  joints  (Windle). 

When  the  lingers  are  flexed,  it  will  be  seen  that  in  each  case  it  is  the  proximal 
bone  which  forms  the  prominence;  thus,  the  knuckle  is  formed  by  the  head  of  the 
metacarpal  the  interphalangeal  prominence  by  the  head  of  the  first  phalanx,  and 


Fig.  728.— Axastomoses  and  DiSTRiBrriox  of  the  Aktkiues  of  the  Hand. 

7 


Anterior  interosseous 

Radial  artery 

Anterior  radial  carpal 


Svperficial  volar 
Posterior  radial  carpal 
Radial  artery  at  wrisi 


Dorsalis  polticis 

Metacarpal  or 

first  dorsal 

interosseous 

Princeps  pollicis 

Dorsalis  indicts 
Radialis  indici. 


First  dorsal  branch  of  collateral 
digital 


Second  dorsal  branch  o/  collateral 
digital 


Anastomosis  of  collateral  digital 
arteries  about  matrix  of  nail 
and  pulp  of  finger 


Ulnar  artery 

Anterior  ulnar 
carpal 

Posterior  ulnar 
carpal 


Deep  ulnar 
Superficial  arch 

Carpal  recurrent 

Posterior  communi- 
cating or  perforat- 
ing 

Palmar  interosseous 

Second,  third,  and 
fourth  palmar 
digital 

S-rond  and  third 
dorsal  interosseous 

First  palmar  digital 

A  uterior  communi- 
cating or  perforat- 
ing 


the  distal  one  by  the  head  of  the  second.  Thus,  the  joint  in  each  case  lies  below 
the  iirominence,  the  distal  joint  being  one-twelfth  of  an  incli  (2  mm.),  the  inter- 
phalangeal one-sixth  (4  mm.),  and  the  metacarpo-phalangeal  one-third  (8  mm.) 
below  its  i)r()ininence. 

Skin  folds.— Two  or  three  of  these  are  seen  on  the  palmar  surface  of  the  wrist; 
two  lower  down,  and  usually  close  together;  and  one  less  well  marked  a  little 
higher  up  upon  the  forearm.  None  of  these  correspond  exactlv  to  the  wrist-joint 
(page  1159).  The  lowest  '  precisely  crosses  the  arch  of  the  os  niasnum  in  the  line 
of  the  third  metacarpal  l^one'  (Tillaux),  and  is  not  quite  three-quarters  of  an  inch 


THE    WRIST  AXD   HA  XI) 


\\(\o 


(18  mm.)  Ix-low  the  arcli  of  the  wrist-jcint.  It  is  ab<.iit  lialf  an  iiidi  al.ov.- the 
carpo-nietacari-al  joint  line,  and  indicates  verv  fairlv  the  upper  harder  ..f  tlie 
anterior  annular  li<,'anient. 

The  thenar  and  hypothenar  eminences  are  separated  bv  a  triangular  interval 
A'ith  the  apex  U2)\\ards;  this  ai)ex  eorn-pnnds  to  the  upper  border  of  the  anterior 

Fig.  7-29.— Thk  Supkkficial  JIusti.Ks  ok  the  Pai.m  of  thk  Haxo. 


-  Flexor  carpi  radialis 


Extensor  ossis  metacarpi  pollicis 


Opponens  pcUicis 


Abductor  pollicis 


Flexor  brevis  pollicis 


Adductor  pollicis 


First  lum- 
bricalis 

First  dorsal 
interos- 
seous 


Ligamentum  vaginale 

Flexor  sublimis  digitorum 


Flexor  profundus  digitorum 


Flexor   profundus 
digitorum 


annular  ligament.  'Of  the  many  ereases  in  the  skin  of  the  i>aliii,  three  reipiire 
especial  notice.  The  first  starts  at  the  wrist,  between  the  thenar  and  liy]>othenar 
eminences,  and,  marking  of¥  the  former  eminence  from  the  jtalm.  ends  at  the  outer 
border  of  the  hand  and  at  the  ba.«e  of  the  index  finger.  The  second  fold  is  slightlv 
marked.      It  starts  from  the  outer  l)order  of  the  hand,  wliere  the  lirst  fr)ld  ends      It 


1166 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


runs  obliquely  inwards  across  the  palm,  with  a  marked  inclination  towards  the 
wrist,  and  ends  at  the  outer  limit  of  the  hypothenar  eminence.  The  third,  lowest, 
and  'best-marked  of  the  folds  starts  froin  the  little  elevation  opposite  the  cleft 
between  the  index  and  middle  fingers,  and  runs  nearly  transversely  to  the  ulnar 
border  of  the  hand,  crossing  the  hypothenar  eminence  at  the  upper  end  of  its  lower 
fourth.  An  unimportant  crease,  running  obli(iuely  from  the  third  to  the  second 
fold,  gives  to  these  markings  the  outline  of  the  letter  M.  The  first  fold  is  i)roduced 
by  the  adduction  of  the  thumb-  the  second,  mainly  by  the  bending  simultaneously 


Fig.  730.— The  Deepek  Muscles  of  the  Palm  of  the  Hand. 


Flexor  carpi 
ulnariB 


Abductor  minimi 
digiti 


Flexor  sublimia 
digitorum 


Flexor  brevis 
minimi  digiti 


Flexor  profundus 
digitorum 


Extensor  ossis  metacarpi  pollicis 
Flexor  carpi  radialis 
Extensor  brevis  pollicis 

Abductor  pollicis 


Opponens  pollicis 


Abductor 
pollicis 
Flexor  brevis 
pollicis 

Adductor 
pollicis 


of  the  metacarpo-phalangeal  joints  of  the  first  and  second  fingers;  and  tlic  third  by 
the  flexion  of  the  three  inner  fingers.  The  second  fold,  as  it  crosses  the  third 
metacarpal  bone,  about  corresponds  to  the  lowest  part  of  the  superficial  palmar 
arch.  The  third  fold  crosses  the  necks  of  the  metacarpal  bones,  and  indicates 
l)retty  nearly  the  upi)er  limits  of  the  synovial  sheaths  for  the  flexor  tendons  of  the 
three  outer  fingers.  A  little  way  below  this  fold,  the  palmar  fascia  breaks  up  into 
its  four  slips,  and  midway  between  the  fold  and  the  webs  of  the  fingers  lie  the 
metacarpo-phalangeal   joints.     Of   the   transverse   folds  across  the   fronts  of  the 


THE   WRIST  AND  HAND 


1167 


fingers,  corresponding  to  the  metacarpo-phalangeal  and  intcrphalangeal  joints,  the 
highest  is  placed  nearly  thnie-ciuarters  of  an  inch  (18  mm.)  below  its  correspond- 
ing joint.  The  middle  folds  are  multiple  for  all  the  fingers,  and  are  exactly 
opposite  to  the  first  intcrphalangeal  joints.     The  lowest  creases  are  single,  and  are 


Fio.  731.— Section  through  region  of  Wrist,  a  little  above  the  Joint.    Kight 
SIDE,  Ui'i'EK  Half  of  the  Section.     (Tillaux.) 


Flexor  carpi  radialis 

Radidl  (irlertj 


Brachio-radialis 


Flexor  longus  pollicia 
Flexor  sublimiB 

Flexor  profundus 

Pronator  quadratus 


RADIAL  NERVE 


Extensor  ossis  meta 

carpi  polliciB  ^-^ 

Extensor  primi       __\\\\ 
iuternodii  pollicis 


Extensor  carpi  radialis 

longior 
Extensor  carpi   radialis 

brevior 


Extensor  secundi  internodii 
pollicis 


Ulnar  artery,  wore 
inlervally    the    SERVE 

interior  internxseous 
artery 


Flexor  carpi  ulnaris 


Extensors  com- 
I     munis  and  indicis 


Extensor  carpi  ulnaris 
Extensor  minimi  digiti 


placed  a  little  above  the  corresponding  joints.  There  are  two  single  creases  on  the 
thumb  corresponding  to  the  two  joints,  the  higher  crossing  the  metacarpo-phalan- 
geal joint  ol)liquely.  The  free  edge  of  the  web  of  the  fingers,  as  measured  from 
the  i)almar  surface,  is  about  three-quarters  of  an  inch  (18  mm.)  from  the  meta- 
carpo-phalangeal joints  (Treves). 


Fig.  732. — Transverse  Section  of  the  Wrist,  through  the  Middle  or  the 

PisiFOEM  Bone. 

Sheath  of  flexores  sublimis  and  profundus  digitorum  and  flexor  longus  pollicis, 
enclosed  by  the  annular  ligament 


Cut  tendon  of  palmaris  longus 

SEMILUNAR  BONF 


Ur.X.il!  SERVE 
Ulnar  vessels 


Sheath  for  flexor  carpi  radialis -77 

Radial  origin  of  annular  ligament  -       yir  ^ilW 

Sheath  for  extensor  ossis  metaearpi A     -zn^l^ 

and  prim 


xiensor  OSSIS  meiaearpi ^-  r^ulLL. 

i  internodii  pollicis  ■'^fsffi^Tv^ 

RmVial  n-ssr/s  ■''  \mff,','i'^f^, 

xtensor  ossis  metaearpi  V   J f-'Ai- 


Sheath  for  extensor  ossis  metaearpi 
and  primi  internodii  pollicis 

OS  MAGNUM 
Sheath  of  extensor  secundi 
internodii  pollicis 


Sheath  of  extensor  carpi 
ulnaris 


Sheath  of  extensores  carpi  radialis,  longior  and  brevior  1  I  |  Sheith  of  extensor  m;nimi  digiti 

CUNEIFORM 
Sheath  of  extensor  communis  and  indicator      UNCIFORM 

SEMILUNAR 


The  superficial  palmar  arch,  formed  by  the  ulnar  anastomosing  with  the 
superficialis  vohv,  or  radialis  indicis,  will  be  shown  l)y  a  line  descending  to  the 
radial  side  of  the  pisiform  l)one,  and  then,  a  little  lower,  coming  across  the  ])alm 
on  a  line  with  the  thuml)  when  outstretched  at  right  angles  witii  the  index  finger. 
The  digital  arteries,  the  main   branches  of  the  superficial  arch,   run  downwards 


1168 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


along  the  interosseous  spaces,  and  liifuvcate  half  an  inch  above  the  webs  of  the 
fingers;  the  innermost  digital  does  not  bifurcate.  The  digital  arteries  then  descend 
along  the  sides  of  the  fingers  under  the  digital  nerves,  giving  off  twigs  to  the  sheath 
of  the  tendons,  which  enter  by  apertures  in  it,  and  run  in  the  vincula  vasculosa. 
It  is  owing  to  the  readiness  Avith  which  these  tiny  twigs  are  strangled  by  inflamma- 
tion that  slougliing  of  the  tendon  takes  place  so  readily  and  irreparal^ly.  The  deep 
palmar  arch,  formed  by  the  radial  and  communicating  branch  of  the  ulnar,  lies 
about  lialf  an  inch  nearer  to  the  wrist  than  the  superficial. 

Fasciae  and  sheaths. — The  two  annular  ligaments  bind  down  and  hold  in 
place  the  numerous  tendons  about  the  wrist.  The  anterior,  when  healthy,  cannot 
be  detected.  It  is  attached  to  the  pisiform  and  cuneiform  bones  on  the  inner,  and 
to  the  scaphoid  and  trapezium  on  the  outer,  side.  The  ulnar  nerve  and  vessels,  the 
superficialis  vola?,  and  palmar  cutaneous  branches  of  the  median  and  ulnar  pi^iss  over 


Fig.  733. — Diagram  ok  the  Geeat  Palmar  Bur.sa. 


triuar  portion  of  palmar  bursa 
Radial  portion  of  palmar  bursa 


Anterior  annular  ligament 


Lumbricalis 


Deep  transverse 
ligament 


Superficial  transverse  ligament 


it.  The  ulnar  artery  and  nerve  are  especially  ])r()teeted  l)y  their  position  between  the 
pisiform  and  hook  of  the  unciform,  and  also  l)y  a  process  of  the  flexor  carpi  ulnaris, 
which  passes  between  the  two  bones,  thus  forming  a  kind  of  tunnel.  The  flexor 
carpi  radialis  passes  through  a  separate  sheath  formed  by  the  ligaments  and  the 
groove  in  the  trapezium ;  while  beneath  the  ligament  lie  the  flexor  tendons,  the 
median  nerve,  and  accompanying  artery.  Attached  to  its  upper  border  is  the  deep 
fascia  of  the  forearm,  and  to  its  lower  the  palmar  fascia  and  the  palmaris  longus 
tendon,  while  from  the  outer  and  inner  parts  arise  some  of  the  thenar  and  hypo- 
tlienar  muscles.  The  U])per  ])or(ler  of  the  anterior  annular  ligament  corresponds 
to  the  lower  of  the  two  lines  wliich  cross  the  wrist  just  above  the  thenar  and  hypo- 
thenar  eminences.  The  large  synovial  sheath,  for  all  the  flexors  of  the  fingers, 
reaches  beneath  and  below  the  anterior  ligament  as  far  as  the  middle  of  tlie  palm, 
and  al)Ove  tlie  wrist  for  an  inch  and  a  lialf  or  two  inches  (37  to  50  mm.). 


THE    WRIST  AXD   HAXD 


1169 


The  posterior  annular  ligament  is  attached  to  the  back  of  the  outer  margin 
of  the  radius  above  the  styloid  process,  and  internally  to  the  Vjack  of  the  cuneiform 
and  pisiform.  It  contains  six  tendon-compartments,  of  which  four  are  on  the 
radius.  The  outermost  contains  the  two  first  extensors  of  the  thund);  the  second 
the  two  radial  extensors  of  the  carpus;  the  third,  the  extensor  secundi  internodii; 


Fig. 


734.— Section  of  Carpi-s,  THKorcwi  thk  Uncifoum  Bone^    (Two-thirds.) 
(Bellamy  after  Henle. ) 

.MEDIA  \  MCR  VE 


Flexor  longus  pollicis 
Flexor  carpi  radialis 
Thenar  muscles 
BASE  OF  FIRST  METACARPAL  BONE 


Flexores  sublimis  and  profundus 
Ulnar  itssels  and  y£Ji VE 


PalmariB  brevia 

Hypothenar  muscles 


Extensor  ossis 
metacarpi  pollieie- 
TRAPE2IUV 
Extensor  primi  internodii 
pollicis 

Radial  vesseW 


Extensor  carpi  radialis  longior 


Extensor  carpi  ulnaris 
TRAPEZOID  I  I  Extensor  minimi  digiti 

External  carpi  radialis  brevior  UNCFORV 

OS  MAGNUM  I  Extensor  communis  digitorum 
Extensor  indicis 


the  fourth  transmits  the  extensor  communis  and  extensor  indicis;  the  fifth,  lying 
between  the  radius  and  ulna,  the  extensor  minimi  digiti;  and  the  sixth,  lying- just 
outside  the  styloid  process  of  the  uhia,  the  extensor  carpi  ulnaris.  The  sheaths 
for  the  last  two  extensors  are  the  onlv  ones  which  follow  the  tendons  to  their  inser- 


FiG.  735. — Horizontal  Section  of  the  Hand  through  the  Carpo-metacabpal 
Joints.      (Bellamy  alter  Heule.j 

Volar  aponeurosis 
Flexor  tendon  in  the  sheath     InteroBseous 
Deep  volar  aponeurosis 

Lumbrieales 
Anterior  carpal  ligament 

Flexor  tendon  in  the  sheath 
Seep  volar  aponeurosis    I 
Lumbricalis 


Lumbrieales 
Flexor  tendon  in  the  sheath 

Lumbrieales 


Anterior  carpal  ligament 
I  Flexor  tendon  in  the  sheath 
Hypothenar  muscles 


tion,  the  others  ending  at  a  varying  distance  l)elow  the  annular  ligament.  The 
lower  border  of  the  posterior  corresjionds  to  the  upper  margin  of  tlie  anterior 
annular  ligament. 

The  palmar   fascia,  by  its  strength,  toughness,  numerous  attachment^;    .ind 
74 


1170 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


intimate  connection  -with  the  superficial  fascia  and  skin,  is  well  adapted  to  protect 
the  parts  beneath  from  pressure.  The  thenar  and  hypothenar  muscles  are  enclosed 
in  two  processes,  which  are  thinner  so  as  not  to  interfere  with  the  contraction  of 
the  subjacent  muscles.     The  central  part,  pointed  above  at  its  attachment  to  the 

Fig.  736. — Tendons  upon  the  Dorsum  of  the  Hand. 


Extensor  oasis  metacarpi 
pollicis 


Extensor  brevis  pollicis 


Posterior  annular  ligament 


Extensor  carpi 
radialis  brevior 


Extensor  carpi 
radialis  longior 


Extensor  longus 
pollicis 


First  dorsal 
interosseous 

Adductor  — ■/- 
pollicis 


Extensor  carpi  ulnaris 


Extensor  communis  digitorui: 


Extensor  minimi  digiti 


Extensor  indicis 


Attachment  of  extensor 
communis  digitorum 
to  second  phalanx 


Attachment  of  extensor 
communis  digitorum 
to  third  phalanx 


annular  ligaments,  spreads  out  fan-like  below,  and  gives  off  four  slips,  each  of  which 
bifurcates  into  two  processes,  which  are  attached  to  the  sides  of  the  first  phalanx 
of  each  finger  and  into  the  transverse  ligament  which  ties  the  heads  of  the  meta- 
carpal bones  together.  Transverse  fiV)res  ]iass  l)etween  the  processes  into  Avhich 
each  of  the  four  slips  bifurcates,  and  thus  form  the  beginning  of  the  theca,  which  is 


THE    WRIST  AND   HAND 


1171 


continued  down  to  the  finger  to  the  base  of  the  last  phalanx.  It  is  the  contraction 
of  the  palmar  fascia,  especially  of  the  slips  to  the  two  inner  fingers,  which  gives  rise 
to  Dupuytren's  contraction. 

Synovial  membranes.— Beneath  the  anterior  annular  ligament  lie  two  syno- 
vial sacs,  one  for  the  lk-.\or  longus  pollicis,  and  one  for  the  superficial  and  deep 
flexors  of  the  fingers.  They  extend  above  the  annular  ligament  to  from  one  anrl  a 
quarter  to  one  inch  and  a  half  (81  to  37  mm.)  below.  That  for  the  long  flexor  of 
the  thumlj  reaches  to  the  base  of  the  last  phalanx.    That  for  the  finger-flexors  gives 


Fkj.  7.37.— Diacijam  ok  a  Vertical  Section  through  the  Middle  of  the  Hand. 


Posterior  anuular  ligament 


Deep  transverse  ligament 
Attachmient  of  common  extensor 
to  first  phalanx 


Superficial  transverse  ligament 


Vincula  accessoria 


Attachment  of  common  extensor 
to  second  phalanx 


Attachment  of  common  extensor 
to  third  phalanx 


Qreat  palmar  bursa 


Anterior  annular  ligament 


Dorsal  interosseous 
Liumbricalis 
Palmar  fascia 

Flexor  profundus  digitorum 

Flexor  sublimis  digitorum 


Ligamentum  vaginale 
Vincula  accessoria 


off  four  processes.  The  one  for  the  little  finger  also  reaches  to  the  liaseof  the  last 
phalanx.  Those  for  the  index,  middle,  and  third  fingers,  end  aliout  tlu'  middle  of 
the  metacarpal  l)ones.  Traced  from  tlu'  insertions  of  the  flexor  ])rofundus.  the 
digital  synovial  sheaths  extend  upwards  into  the  palm  as  far  as  the  ))ifurcation 
of  the  palmar  fascia  (page  1169),  i.e.  into  a  point  al)out  opposite  to  the  necks 
of  the  metacarpal  bones,  denoted  on  the  surfice  by  the  crease  which  corresponds 
to  the  flexion  of  the  fingers.  Thus,  about  half  an  inch  (12  mm.)  separates  the 
sheaths  of  the  outer  three  fingei"s  from  that  large  synovial  sac  beneath  the  annular 
ligament.     There  is  no  synovial  sheath  beneath  the  pulp  of  the  fingers  or  thumb, 


1172  SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 

this  part  lying  on  the  periosteum  of  the  last  i)liahinx.  The  synovial  sheaths,  as 
they  pass  beneatli  the  annular  htrament.  are  sonu-what  eonstricted. 

Deeper  down  are  the  articular  synovial  sacs,  tive  in  number:  (1)  Between 
the  interarticular  cartilage  and  the  head  of  the  ulna;  (2)  between  the  radius  and 
the  interarticular  cartilage  above,  and  the  scai)hoid,  and  semilunar  and  cuneiform 
V)elow;  (3)  between  the  trapezium  and  first  metacarpal  bone;  (4)  between  the  jusi- 
form  and  the  cuneiform  bone;  (5)  between  the  two  rows  of  carpal  bones,  sending  two 
processes  upwards  between  the  three  bones  of  the  upper  row,  and  three  downwards 
lietween  the  four  of  the  lower  row;  these  three  processes  being  also  continued  below 
into  the  inner  four  carpo-metacarpal  and  three  intermetacarpal  joints. 

Beneath  the  palmar  fascia  covering  the  thenar  eminence  are  the  following  struc- 
tures:— Superticialis  volw,  abductor  pollicis,  opponens  pollicis,  radial  head  of  short 
flexor,  tendon  of  long  flexor,  ulnar  head  of  short  flexor,  princeps  polli(,-is,  and 
radialis  indicis  arteries,  metacarpal  bone  of  the  thumb,  with  the  tendon  of  the 
flexor  carpi  radialis  and  trapezium. 

Beneath  the  central  part  of  the  palmar  fascia  are  the  superficial  arch  and  its 
digital  branches;  the  ulnar  and  median  nerves,  with  their  branches;  the  flexors, 
superficial  and  deep,  Avith  their  synovial  sheath;  and  the  lumbricales;  then  a  layer 
of  connective  tissue  (the  only  structure  which  prevents  matter  pent  in  by  the  palmar 
fascia  from  making  its  way  back  out  through  the  dorsum),  the  deep  arch,  the 
interossei,  and  the  metacarpal  bones. 

In  the  hypothenar  eminence  under  the  fascia  are  part  of  the  ulnar  artery  and 
nerve,  the  abductor  and  flexor  brevis  minimi  digiti,  the  opponens,  the  deep  branch 
of  the  ulnar  artery  and  nerve,  and  the  fifth  metacarpal  bone. 

The  back  of  the  wrist  and  hand. — The  posterior  annular  ligament  has  already 
been  described  with  the  anterior.  On  the  outer  side  is  the  so-called  '  snuff-box 
space'  (tabatlere  anatomique  of  Cloquet),  a  triangular  hollow,  bounded  towards 
the  radius  by  the  two  first  extensors  of  the  thumb,  and  tow'ards  the  ulna  by  the 
extensor  secundi  internodii.  The  scaphoid  and  trapezium,  with  their  dorsal  liga- 
ments, form  the  floor.  In  the  roof  lie  the  radial  vein  and  branches  of  the  radial 
nerve.  More  deeply  is  the  artery  following  a  line  from  the  apex  of  the  styloid  pro- 
cess to  the  back  of  the  interosseous  space.  The  different  tendons  have  already  been 
given.  Between  the  first  two  metacarpal  bones  is  the  first  dorsal  interosseous 
muscle,  which  forms  a  fleshy  projection  against  the  radial  side  of  the  index  meta- 
carpal, when  the  thumb  and  index  are  pressed  together.  On  its  palmar  aspect  is 
the  adductor  pollicis.  Wasting  of  the  former  muscle  is  a  ready  indication  of  injury 
or  disease  of  the  ulnar  nerve. 


TIIi:   LOWER    EXTREMITY 


THE   THIGH 

Bony  landmarks. — Many  of  these,  such  as  the  anterior  superior  spine  of 
the  ilium  and  the  spine  of  the  pubes,  have  already  l)een  mentioned. 

The  head  and  shaft  of  the  femur  are  well  covered  in,  save  in  the  emaciated. 
The  head  lies  just  below  Poui)art's  ligament,  under  the  ilio-psoas  and  a  little  to  the 
outer  side  of  the  centre  of  that  ligament.  The  outline  of  the  condyles  can  be 
traced  when  the  knee  is  flexed,  and.  on  the  outer  side,  a  small  portion  of  the 
shaft  is  accessible  between  the  biceps  and  vastus  externus. 

Trochanter  major. — This  most  valuable  landmark  is  most  ])rominent  when 
the  limb  is  rotate*!  inwards  or  adducted;  it  lies  at  the  bottom  of  a  depression  when 
the  femur  is  everted.  The  only  structures  of  importance  Ix'tween  it  and  the  skin 
are  the  expanded  insertion  of  the  gluteus  maximus  and  the  bursa  beneath  the 
muscle.     This  is  often  multilocular.     The  top  of    the  great  trochanter  is  about 


rilE   THIGH 


1173 


three-quarters  of  an  inch  (18  mm.)  lielow  the  level  of  the  femoral  head,  and,  Avhen 
the  femur  is  extended,  is  a  little  below  the  centre  of  the  hip-joint.  This  part  of 
the  bone  is  covered  by  the  gluteus  medius.  The  slightness  of  the  prominence  of 
the  great  trochanter  in  the  living  subject  compared  with  that  in  the  skeleton  is 
explained  by  fig.  738,  which  shows  how  the  descending  gluteus  medius  and 
minimus  fill  up  the  space  between  the  ilium  and  trochanter. 

Nelaton's  line. — This  most  useful  guide  is  a  line  drawn  from  the  anterior 
superior  sj)iiie  to  the  most  prominent  part  of  the  tuberositv  of  the  ischium.  In 
normal  limbs,  the  top  of  the  great  trochanter  just  touches  this  line.  In  dislocation, 
fractures  of  the  neck,  and  in  wasting  of  the  neck,  as  in  osteo-arthritis,  the  relation 
of  the  trochanter  to  Nelaton's  line  becomes  altered. 

The  top  of  the  great  trochanter  is  a  guide  in  Mr.  Adams's  operation  for  division 


Fig.  73s.— Transverse  Sectiox  of  the  Hip-joint  and  its  Relations. 

(One  third.)      (P.raune.) 


AyTERIOR  CRURAL 
yERVE     IX     SCB- 

STANCE    OF  ILIA- 

CUS  IXTERNUS 
External  iliac  artery  — 

ILIUM  '-- 


Obturator  internus 


Adductor  magnus  ~ 


Obturator  externus 


Adductor  longus  ~ 
Adductor  brevis  - 


Gluteus  minjmua 
Gluteus  medius 


Ilio-paoaj 


of  the  neck  of  the  femur,  the  puncture  being  made  and  the  saw  entered  one  inch 
(25  nnn. )  above  and  about  one  inch  in  front  of  this  point. 

Bryant's  triangle. — Mr.  Bryant  makes  use  of  the  following  in  deciding  the 
position  of  the  great  trochanter.  The  i)atient  being  flat  on  his  l)ack.  (1)  a  line  is 
dropped  vertically  on  to  the  couch  from  the  anterior  sui»erior  s])ine;  (2)  from  the 
top  of  the  great  trochanter  a  straight  line  in  the  long  axis  of  the  thigh  is  drawn  to 
meet  the  first;  (3)  to  complete  the  triangle,  a  line  is  drawn  from  the  anterior 
superior  spine  to  the  top  of  the  trochanter.  This  line  is  practically  Nelaton's. 
The  second  line  will  be  found  diminished  on  the  damaged  or  diseased  side. 

Muscular  prominences. — The  tensor  vagina?  femoris  (ilio-aponeurotic  muscle) 
forms  a  prominence  beginning  just  outside  the  sartorius  and  reaching  downwards 
and  somewhat  backwards  to  the  strong  fascia  lata,  three  to  four  inches  (7o  to  100 
mm.)  below  the  great  trochanter.  Below  this  jxiint.  as  far  as  the  outer  tuberosity 
of  the  tibia,  the  strong  ilio-til)ial  band  can  be  felt.     The  sartorius,  the  chief  land- 


1174 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


mark  of  the  thigh,  forming  a  l)oiindary  of  Scarpa's  triangle,  Hunter's  canal,  and 
the  popliteal  space,  can  be  readily  brought  into  view  by  the  patient's  raising  his 
limb.  In  the  middle  line  the  rectus  muscle  stands  out  in  bold  relief,  with  its 
tendon  of  insertion  and  the  patella,  when  the  leg  is  extended.  On  either  side  of 
this  muscle  is  a  furrow,  and  on  either  side,  again,  of  this  furrow  the  vasti  become 
prominent.  Between  the  vastus  internus  and  adductor  muscles  is  a  depression 
indicating  Hunter's  canal.  At  the  upper  and  inner  third  of  tlie  tliigh,  if  the  limb 
be  abducted,  the  upper  part  of  the  adductor  longus  comes  into  strong  relief.     On 


Fig.  739. — The  Muscles  attached  to  the  Pcbes.     (From  a  dissection  in  the 

Hniiterian  Museum.) 


External  otlique 


Bectus  abdominis 


Adductor  longus 


CORPORA  CAVERNOSA 
Adductor  brevis  ; 
below  it  and  exter- 
nally are  adductor 
magnus  and  ob- 
turator externua 

CORPUS  SPONGIOSUM 


Accelerator  urinae 
Raphe 


QuadratuB  femoris 

Semi-tendinosus 
and  biceps  be- 
low. (The  line 
has  by  mistake 
been  drawn  be- 
yond the  semi- 
tendinosus  to 
point  to  the 
lowest  fibres  of 
the  adductor 
magnus.) 


Rectus  abdominis 
Peetineus 


Adductor  longus 
Adductor  brevia 


rator  externus 
1  Adductoi   magnus 
Gracilis 
Erector  penis 


Transversus  periueei 


Central  tendinous  point 


Sphincter  ani 


the  inner  side  below,  a1)0ve  the  knee-joint,  tlie  vertical  fil>res  of  the  adductor 
magnus  end  in  a  iwwerful  tendon  coming  down  to  the  adductor  tul>ercle  (tig.  752). 
This  replaces  here  the  internal  intermuscular  septum,  and  the  insertion  of  the 
tendon  marks  the  level  of  the  lower  ei)iphysial  line  of  the  femur.  At  tlie  outer 
and  Ijack  part  of  the  thigh  the  vastus  externus  is  separated  from  the  l)iceps  by  a 
groove  wliicli  indicates  the  external  intermuscular  sei)tum. 

Poupart's  ligament. — The  abdomen  is  se]iarated  from  the  thigli  l)y  a  fold, 
best  marked  in  flexion — the  inguinal  furrow.  In  this,  pressure  detects  the  meeting 
of  the  aponeurosis  of  the  external  oblique  and  the  fascia  lata,  i.e.  Poupart's  liga- 


THE   THIGH 


1175 


ment,  extending  between  the  anterior  superior  spine  of  the  iHum  and  the  spine  of 
the  pubes.  The  Hne  representing  it  should  be  drawn  sHghtly  convex  downwards, 
owing  to  the  attachment  of  the  deep  fascia.  It  forms  the  base  of  Scarpa's  triangle; 
its  inner  attachment  blends  with  the  triangular  Ginil»ernat's  ligament.  The  parts 
passing  under  Poupart's  ligament  and  their  arrangement  have  been  given  elsewhere. 
Scarpa's  triangle  (fig.  741). — Immediately  below  Poupart's  ligament,  a  hollow 
is  seen  eorre^fpunding  to  this  region,  the  outer  and  inner  boundaries  of  which  are 


Fig.  740.— Diagram  of  Auterie.s  ok  Thigh. 

lli(t-liimhar  artery 


Deep  circumflex  iliac,  anastomoning  with 
ilio-lumbar  of  internal  iliac 


Common  femoral 


Deep  femoral   (profunda').       [Should    be 

larger  at  origin.) 
Descending  branch  of  external  circumflex 


Popliteal 


Superior  external  articular,  anastomosing 
with  external  circumflex,  etc. 


Inferior  external  articular 

Posterior  tibial  recurrent  (from  anterior 

tibial) 

Anterior  tibial  recurrent 

Superior  fibular 

Anterior  tibial 


Common  iliac  artery 

Deep  epigastric 

Internal  iliac,  dividing  into  anterior  and 
posterior  trunks 

External  iliac 
Obturator 

Sciatic 

Internal  pudic 

Lower  terminal  branch  of  internal  cir- 
cumflex 

Superficial  femoral  (muscular  branches 
omitted) 


Perforating  branches  of  deep  femoral, 
forming  anastomotic  loops  and  supply- 
ing posterior  muscles 


Anastomotica  magna 


Popliteal,  giving    off  superior   muscular 
branches 


Superior  internal  articular 


Inferior  internal  articular  (sural  arteries 

arising  below  this  omitted) 
Posterior  tibial 


brought  into  view  when  the  limb  is  raised,  the  adductor  longus  especially  when 
the  limb  is  abducted,  and  the  sartorius  where  the  thigh  is  Hexed  and  adducted  and 
carried  towards  its  fellow.  Lving  superficially  in  the  base  of  the  triangle,  the  lym- 
phatic glands  can  be  detected'  in\i  thin  person  (fig.  769).  They  lie  in  two  groui)s 
—(a)  One  horizontal  in  a  line  with  Poui)art's  ligament,  and  receiving  lymph  from 
the  genitals,  the  lower  part  of  the  abdominal  wall,  and  the  inner  aspect  of  the 
buttock;   (6)  a  vertical  set  lving  along  the  great  vessels  receiving  lymph  from  the 


Fig.  741.— Section'  of  the  Right  Thigh  at  the  Apex  of  Scarpa's 
Teiangle.     (Heath.) 

Femoral  vessels 


Sartorius 
EXTERNAL  CUTAXEOUS  NERVE 


Profunda  vessels 

Adductor  longua 


Rectus  femoris 

ANTERIOR  CRURAL 

NERVE 

External  circumflex 

vessels 

Tensor  fasciae  femoris 

Vastus  intemua  and 
erureus 


Vastus  eiternus 


ULI'ERFICIAL  PART  OF  OBTURATOR 
NER  VE 


■^    Gracilis 
Peetineus 


Adductor  brevis 
DEEP  PART  O'F  OB- 
TURATOR NFRVE 
Adductor  magnus 

Semi-membranosus 


Biceps  femoris  I  I    Semi-tendinosus 

'    SMA  LL  SCI  A  TIC  NER  VE 
GREA  T  SCI  A  TIC  NER  VE 


Fig.  742.— Superficial  Dissection  of  the  front  of  the  Thigh. 
(Hirschfeld  and  Leveille.l 


Poupart's  ligament  -^ 

EXTERNAL  CUTANEOUS  NEJ:  i 
MIDDLE  CUTANEOUS  NER  : 
OUTER  DIVISION  OF  INTERNA 
CUTANEOUS  NERVE 


MIDDLE  CUTANEOUS  NERVi: 
BRANCH  TO  SARTOR  J I 

EXTERNAL  CUTANEOUS  NER  \  1 


S  UBS  A  R  TORI  A  L  PL  EN  I 
OUTER  DIVISION  OF  INTERNAL 
CUTANEOUS  NERVE 


OUTER  DIVISION  OF  INTERNAL 
CUTANEOUS  NERVE 


MIDDLE  CUTANEOUS  NER\ 


Superficial  branches  of  femoral 

artery 
Femoral  artery 
Femoral  vein 
INNER  DIVISION  OF  INTERNAL 
CUTANEOUS  NERVE 


— '  %  Saphena  vein 


INNER  DIVISION  OF  INTERNAL 
CUTANEOUS  NERVE 

CUTANEOUS  BRANCH  OF 
OBTURATOR  NERVE 


INNER  DIVISION  OF  INTERNAL 
CUTANEO  US  NER  I E 


PATELLAR  BRANCH  OF  LONG 
SA  PIIENA 


OJTf       LONG  OR  INTERNAL  SAPHENOUS 

1176 


NER  VE 


THE  THIGH 


1177 


limb.  According  to  Mr.  Treves,  a  few  of  the  superficial  genital  lymphatics,  and 
all  those  from  the  ]»t'rina'um.  go  into  the  vertical  grouj). 

Saphenous  opening. — The  depression  corre.^^ponding  to  this  is  placed  just 
below  Giiubernat".s  ligament,  with  which  its  upper  extremity  blends.  Its  centre  is 
about  an  inch  and  a  half  (37  mm.)  below  and  al.^o  external  to  a  line  dropped  ver- 
tically from  the  pul)ic  .spine.  This  and  the  other  structures  concerned  in  femoral 
hernia  are  fully  descril)ed  under  this  section  (ride  .<<iij,ra,  ])age  113H). 

Line  of  femoral  artery. — A   line  drawn   from   the   mid-point  i)etwe<-n   the 


Fig.  743.  -  AxTKUioK  Ckikai.  and  Obtluatuu  Nekve.s.     (Ellis.) 

Femora!  vein  Femoral  nrlrry 


Pectineus 
OB TL 'RA  TOR  {A XTKRIOR  DIW)     \ 

OBTURATOR  (POSTERIOR 
DIVISIOX) 


Adductor  longua    — 


Adductor  breviB 


(iHTVRATOR     /.—> 

\ ANTERIOR  '   4 

lUVI.SIOS)  ■  / 


LOSG  SAPHESors 


NERVE  TO  VASTUS 
lyTERSUS 


Adductor  ma^rnuB 

GESirULA  TE 
BR  A  yen  OF 
OBTURATOR 

Semi-membranosus 


Adductor  loneus 


Anastomoticn  arlfri/ 


PA  TELLAR  BRANCH  OF 
LONG  SAPHENOUS 


anterior  superior  spine  and  the  symi)hysis  pubis  to  the  adductor  tubercle  will 
correspond  with  the  course  of  this  vessel.  The  sartorius  usually  crosses  it,  three 
to  four  inches  (100  mm.)  below  Poupart's  ligament.  The  profunda  artery  arises 
an  inch  and  a  half  to  two  inches  below  Poupart's  ligament.  Therefore  the  incision 
for  tying  the  femoral  in  Scarpa's  triangle  should  be  al»out  three  inches  long,  in 
the  line  of  the  artery,  and  begin  about  three  inches  below  Poupart's  liganu-nt.  and 
run  over  the  apex  of  the  triangle.  The  vein  lies,  below  Poujiart's  ligament,  imme- 
diately to  the  inner  side  of  the  artery.  From  tliis  ])oint  the  vein  gt'ts  on  to  a  .some- 
what deeper  plane,  though  still  very  close  to  the  artery,  and  gradually  inclining  back- 


1178 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


wards,  lies  behind  its  companion  at  the  apex  of  the  triangle,  and  below  lies  some- 
what to  its  outer  side. 

From  the  apex  of  Scarpa's  triangle  a  depression  runs  down  along  the  inner 
aspect  of  the  thigh,  corresponding  to  the  groove  already  mentioned  (page  1175) 
between  the  vastus  internus  and  the  adductors.  Along  this  groove  lies  the  sartorius, 
and  beneath  it  Hunter's  canal.  The  vein  has  here  got  somewhat  to  the  outer 
side.  The  long  saphenous  nerve  lies  also  in  the  canal,  but  not  in  the  sheath.  The 
above-mentioned  space  terminates  at  about  the  junction  of  the  middle  and  lower 
thirds  of  the  thigh,  in  the  opening  in  the  adductor  magnus  by  which  the  artery 
enters  the  upper  and  inner  part  of  the  popliteal  space.  The  long  saphenous,  the 
largest  branch  of  the  anterior  crural  nerve,  having  crossed  the  femoral  vessels 
from  without  inwards,  accompanies  them  as  far  as  the  opening  in  the  adductor 

Fig.  744— Section  of  Thigh  through  lppee  part  of  Hunter's  Canal.     (W.  A.) 


Lymph  spaces 


LONG  SAPHE- 
NOUS NERVE 

Femoral     artery,    vitk 

small     ven(e     comites 

( femoral  vein  deeper) 

Shealh  of  vessels 


Long  saphenous  vein 


Lymph  spaces 
Superficial  fascia 


Deep  fascia  contin- 
ued over  back  of 
Thigh  as  superfi- 
cial layer  of  deep 
fascia 


Middle  layer  of 
deep  fascia 


Deep  layer  of  deep 
fascia  (muscular 
aponeurosis; 


GREA  T  SCI  A  TIC  NER  VE      Vein 


magnus.  Here  it  perforates  the  aponeurotic  roof,  and  is  prolonged  under  the 
sartorius,  accompanied  by  the  superficial  part  of  the  anastomotic  artery,  to  per- 
forate the  fascia  lata  between  the  sartorius  and  gracilis,  and  run  with  the  long 
saphena  vein  at  the  upper  and  inner  part  of  the  leg. 

Pressure  may  be  applied  to  the  femoral  artery — (1)  Immediately  below  Poupart's 
ligament:  it  should  here  be  directed  backwards  so  as  to  compress  the  vessel  against 
the  brim  of  the  pelvis  and  the  capsule  of  the  hip-joint;  (2)  at  the  apex  of  Scarpa's 
triangle,  the  pressure  here  being  directed  outwards  and  a  little  backwards,  so  as  to 
command  the  vessel  against  the  bone;  (3)  in  Hunter's  canal  the  pressure  should 
be  directed  outwards  with  the  same  object.  Care  must  be  taken,  especialh''  above, 
to  avoid  the  vein,  Avhich  lies  very  close  to  the  artery,  and  also  the  anterior  crural 
nerve,  which  enters  the  thigh  a])OUt  half  an  inch  (12  mm.)  outside  the  artery,  and 
at  once  breaks  up  into  its  branches,  superficial  and  deep. 


THE   THIGH 


1179 


Fig.  74r>. — Superficial  Mrsci.Es  of  tiik  Eack  of  tiik  Tnu.n  and  Leg. 


Gluteus   mediuB 


Aponeurosis  of  gluteus  mazimus   m\ —      ^ 


Gluteus  mazlmuB 


Semi-membranosuB 


Biceps 


Vastus  extemus 


3emi-tendinosu3 

Gracilis 

Tendon  of  semi-membranosus 


dartorius 


Gastrocnemius 


Flexor  longuB  dlgitorum 


Peroneus  longus 


Tendo  Achillis 


1180 


SURGICAL  AND  TOPOGRAPHICAL  ANATOMY 


THE  BUTTOCKS 

Bony  landmarks. — The  finger  readily  traces  the  whole  oiitlme  of  the  iliac 
crest.  Behind,  it  terminates  in  the  posterior  superior  spine,  which  corresponds  in 
level  to  the  second  sacral  spine  and  the  centre  of  the  sacro-iliac  joint  (Holden). 

The  third  sacral  sjnne  marks  the  lowest  limit  of  the  spinal  membranes  and  the 
cerebro-spinal  Huid;  it  also  corresponds  to  the  upper  border  of  the  great  sacro- 
sciatic  notch. 

The  first  piece  of  the  coccyx  corresponds  to  the  spine  of  the  ischium  (Windle). 
Its  apex  is  in  the  furrow  just  behind  the  last  piece  of  the  rectum. 


Fig.  746.— Positiox  and  Direction  of  the  Superficial,  In'cisioxs  which  must  be 

MADE  IN   order  TO  REACH   THE  GLUTEAL,    SCIATIC,    AND   PUDIC  ARTERIES. 

A.B.  Ilio-trochanteric  line  divided  into  thirds,  and  corresponding  in  direction  with  the  line  of  the 
gluteus  maxinius.  The  incision  to  reach  the  gluteus  niaximus  is  indicated  by  the  dark  part  of  the 
line.  Its  centre  is  at  the  jjositiou  of  the  upper' and  middle  thirds  of  the  ilio-trochauteric  line,  and 
corresponds  with  the  point  of  emergence  of  the  artery  from  the  great  sciatic  notch. 

A.C.  Ilio-ischiatic  line.  The  incision  to  reach  the  sciatic  or  pudic  artery  is  indicated  by  the  lower 
dark  line.  This  is  also  to  be  made  in  the  direction  of  the  fibre  of  the  gluteus  maximus.  Its  centre 
corresponds  to  the  position  of  the  loAver  and  middle  thirds  of  the  ilio-ischiatic  line. 


ANTERIOR  SUPEHIOR  ILIAC  SPINE  (» 


GREAT  TROCHANTER  (Bj 


.1)  POSTERIOR  SUPERIOR  ILIAC  SPINE 


(Cj  TUBEROSITY  OF  ISCHIUM 


The  tuberosities  of  the  ischium  are  readily  felt  by  deep  pressure  on  either  side 
of  the  anus.  In  the  erect  position  they  are  covered  by  the  lower  margin  of  the 
gluteus  maximus.  In  sitting  they  are  protected  by  tough  skin,  fascia?,  with  coarse 
fibrous  fat,  and  often  by  a  bursa  known,  according  to  the  patients  in  whom  it 
becomes  enlarged,  as  'weaver's,  coachman's,  lighterman's,  drayman's'  bursa. 

Gluteus  maximus. — The  '  fold  of  the  buttock  '  neither  corresponds  accurately 
to,  nor  is  caused  by,  the  lower  margin  of  this  muscle.  It  is  really  due  to  creasing 
of  the  skin  adherent  here  to  the  coarsely  fibro-fatty  tissue  over  the  tuber  ischii 
during  extension.  But  in  early  hip  disease,  in  which  flexion  of  tlie  joint  is  almost 
unvaryingly  present,  both  the  fold  and  the  gluteus  maximus  disappear  with  char- 
acteristic rapidity.     The  prominence  of  the  luittock  is  mainly  due  to  the  gluteus 


THE  BUTTOCKS 


11.^1 


maximus,  especially  behind  and  below,  and  in  less  degree  to  the  other  two  ^dutei 
in  front.  Under  the  lower  edge  of  the  gluteus  maximus  the  edge  of  the  great  sacro- 
sciatic  ligament  can  be  felt  on  deep  ])ressure'. 

Nerves  and  vessels. — The  following  superficial  nerves  can  Ije  marked  in 
over  the  buttock  (fig.  770).  Behind  the  gnat  troclianter,  branclies  of  the  external 
cutaneous.  Coming  down  over  the  crest,  the  lateral  cutaneous  l>ranch  of  the  last 
dorsal  (aljout  in  a  line  with  the  great  trochanter),  and  ])eliind  this  the  lateral 
branch  of  the  ilio-liypogastric.  Two  or  three  offsets  of  the  posterior  primary 
branches  of  the  lumbar  nerves  cross  the  hinder  part  of  the  iliac  crest  at  the  outer 
margin  of  the  erector  spinte.  Two  or  three  twigs  from  the  posterior  divisions  of 
the  sacral  nerves  pierce  the  gluteus  maximus  close  to  the  coccyx  and  sacrum,  and 
ramify  outwards.  Finally,  over  the  lower  border  of  the  gluteus  maximus  turn 
upwards  branches  of  the  small  sciatic  and  inferior  jtudendal  and  fourth  sacral 
nerves. 

Great  sciatic  nerve  (figs.    748,    749). — The  point  of   emergence  below  the 


Fig.  747.— Sectiox  through  the  Hip  and  Gliteal  Region.     (Oue-third.) 


SartoriuB 

Refieeted  tendon 

rectus 
Psoas  and  iliacus 

and  bursa         ^s         ^^  \ 
AyTERIOR       ,  ^-^^      y-] 
CRURAL  SERVE  ""---.[^n/' 
Cnmmon  feinonil  ~^^       //  Ij  i» 
arleri/  "/^/'fr 

Cumiiton  femoral  rein  ^^   '/     \  ry/ 

Profimria  vessrls  ■^^%.    'f  *^ 

Semi-membranoBUB  •^.^~^- 
Adductor  brevis  z£.^/-\ 
Semi-tendlnosuB  ■'-- 
Obturator  exteruus  -- 
Adductor  longus  -'■ 
Adductor  magnus 


Gluteus  maximus 
Gluteus  mediuB 


-    Gluteus  minimus 


Pyrlformls 
GREA  T  SCIA  TIC 

SERVE  and  sciati 

res.sf'ts 
Obtura'or  internus 
Gemelli 

Biceps 
Quadratus  femoris 


gluteus  maximus  and  the  track  of  this  nerve  will  be  given  by  a  line  drawn  from  a 
spot  a  little  internal  to  the  middle  of  the  space  between  the  great  trochanter  and  the 
tuber  ischii  to  the  lower  part  of  the  back  of  the  thigh.  The  inferior  pudendal 
perforates  the  deep  fascia  about  an  inch  (25  nun.)  in  front  of  the  tuber  ischii,  antl 
turns  forwards  to  su})i)ly  the  genitals. 

Gluteal  artery. — If  a  line  be  drawn  from  the  posterior  superior  si)ine  to  the 
apex  of  the  great  trochanter,  the  limb  being  slightly  flexed  and  rotated  inwards, 
the  point  of  emergence  of  the  artery  from  the  upper  part  of  the  great  sacro-sciatic 
notch  will  correspond  with  the  junction  of  the  upper  and  middle  third  of  this  line 
(fig.  746)  (MacCormac).  The  gluteal  nerve  emerges  immediately  below  the 
artery,  and  sends  branches  with  the  deeper  portion. 

Sciatic  and  pudic  arteries. — The  limV>  l>eing  rotated  inwards,  a  line  is  drawn 
from  the  ])()st<,'rior  superior  sjiinc  to  the  outer  ])art  of  the  tuber  ischii.  The  ]»oint 
of  exit  of  the  above  arteries  will  correspond  to  the  junction  of  the  middle  and 
lower  thirds  of  this  line  (MacCormac). 


1182 


SURGICAL   Ayn   TOPOGRAPHICAL  A^,^ATOMr 


THE  KNEE 

Bony  landmarks. — The  patella,  the  condyles,  the  tuberosities  of  the  tibia,  the 
tulieTcle  (.)f  the  til)ia,  the  head  of  the  tibula. 

The  patella. — The  limb  l^eing  sui)ported  in  the  straight  position,  and  the 
extensor  muscles  relaxed,  the  numerous  longitudinal  stria.'  or  sulci  on  the  anterior 
surface  of  this  bone  can  be  detected.  In  these  are  embedded  tendinous  l)undles  of 
the  rectus,  so  as  to  give  firmer  leverage.    The  fact  that  these  fibres,  thus  tied  down, 


Fig.  748. — The  Gluteal  Kegion,  with  the  Gluteal,  Sciatic,  and  Pudic  Akteeiks. 

(From  a  dissection  by  W.  J.  Walsham  iu  St.  Bartholomew's  Hospital  Museum.) 

The  inferior  gluteal  branch  of  the  sciatic  artery  has  been  drawn  inwards  over  the  tuber  ischii  with  the 
reflected  origin  of  the  gluteus  niaximus  muscle. 


Gluteus  mediUB,  turned  up 


INFERIOR  GLUTEAL  NERVE 
Gluteus  maximus,  cut 
Internal  circumjiei  artery 
Obturator  externus 


Insertion  of  gluteus  medius 


External  circumflez  artery 


Gluteus  minimus 

Muscular  branches  of  sciatic  artery 
Deep  branch  of  gluteal  artery 

SUPERIOR  GLUTEAL  SER\E 


Pyriformis  perforated  by  peroneal 
portion  of  sciatic  nerve 


Cut  edge  of  gluteus  maximus 


Insertion  of 
gluteus  maximus 

First  perfnratiiKj  iirlery 

Quadratus"  femoris 


J'lidir  a  I  ten/  and  nerve 
Sciatic  artery 


Branch  of  internal  circumflex  rirteri/ 
Obturator  internus  with  the  two  gemelli 


Pemi-tendinosus 
Semi-membranosus 


LESSER  SCIATIC  NERVE 
Arteria  comes  neri'i  ischiatici 
PO  PL  I  TEA  L  PORTION  OF  GREA  T  SCI  A  TIC  NER  VE 
LONG  PUDENDAL  NERVE 
PERONEAL  PORTION  OF  GREA  T  SCIA  TIC  NER  VE 


are  liable  to  fold  in  between  the  ends  of  the  boiic  after  fracture,  is  a  ready  explana- 
tion of  the  difficulty  of  ensuring  bony  union  here  (Macewen).  The  j^atella  is 
separated  from  the  tiljia  by  a  pad  of  fat  and  a  deep  bursa,  save  at  its  insertion.  It 
has  the  following  relation  to  the  femur  in  different  ])Ositions: — (1)  In  extension, 
the  patella  rises  over  the  condyles,  and  in  full  extension  only  the  lower  third  of 
its  articular  surface  rests  upon  that  of  the  condyles;  its  upper  two-thirds  lies  upon 
the  bed  of  fat  Avhich  covers  the  lower  and  front  part  of  the  femur.  (2)  In  extreme 
flexion,  as  the  prominent  anterior  surface  of  the  condyles  affords  leverage  to  the 


THE  KXEE 


1183 


quadriceps,  the  patella  needs  to  project  very  little;  thus,  only  its  upper  third  is  in 
contact  with  the  femur,  its  lower  two-thirds  now  resting  on  the  pad  of  fat  between 
it  and  the  tibia.  (3)  In  semiflexion  the  middle  third  of  the  patella  rests  upon 
the  most  prominent  part  of  the  condyles  (Humi)hry).  While  the  bone  now 
affords  the  greatest  amount  of  leverage  to  the  ((uadricejjs,  it  is  also  submitted  to 
the  greatest  amount  of  strain  from  this  muscle,  Avhich  is  acting  almost  at  a  right 
angle  to  the  long  axis  of  the  patella.  Tliis  position  may  therefore  V)e  called  'the 
area  of  danger,'  as,  in  a  sudden  and  violent  contraction,  the  patella  may  be  snapped 


Fig. 


749. — Deep  Dissection  of  the  Gluteal  Region'. 
the  Hunteriau  Mu.seuiu.) 


(From  a  preparation  iu 


Gluteus  medius 


Gluteus  minimus 

Pyriforinis,  divided 

into    two    by    the 

great  sciatic  nerve 

GREAT  TROCHANTER 


Obturator  eiternus         '^g. 


Quadratus  femoris  '^^ 


Fascial  insertion  of 
gluteus  maximus 


Horizontal  fibres  of 
adductor  magnus 


Fleshy  insertion   of 
gluteus  maximus 


GREAT  SACftO-SCIATiC 
FORAMEN 

GLUTEAL  NERVE 
SVPPLYISG  FOR- 
TIO.WS  OF  G  LU- 
TE IS  MEDIUS 

Gluteus  maximus 


Obturator  internus. 
Below  is  the  infe- 
rior gemellus.  The 
superior  gemellus 
is  absent 


BRAyCHES  OF  IS- 
FERIOR  PUUES- 
DAL  yERVE 


GREA  T  SCL4  TIC  yER  VE. 
I'nder  it,  obliqiip  fibres  of 
:iikiuct«r  niagniis  are  set-ii 


SMA  LL  SCI  a  TIC  yER  VE 


across  by  muscular  action,  aided  by  the  resistance  given  by  the  condyles,  in  the 
same  way  as  a  stick  is  snapped  across  the  knee.  Below  its  articular  surface  for  the 
femur  it  is  separated  from  the  tibia  l)y  a  pad  of  fat  and  a  deep  bursa,  save  at  the 
apex  to  which  the  ligamentum  ])atell»  is  attached,  ^^'hen  the  knee-joint  is  bent,  the 
trochlear  surface  of  the  former  can  ])e  made  out,  with  some  dithculty,  underneath 
the  quadriceps  expansion.  The  upper  and  outer  angle  of  this  surface  forms  a 
useful  landmark  (Godlee),  as  a  line  drawn  from  it  to  the  adductor  tubercle  marks 
the  level  of  the  lower  epiphysis  of  the  femur. 


1184 


SURGICAL  AND  TOPOGRAPHICAL  ANATOMY 


Dislocation  of  the  patella. — The  followinfi^  anatomical  facts  account  for  this 
taking  jjlace  much  more  frequently  outwards: — (1)  The  inner  edge  of  tlie  jjatella 
is  more  prominent,  and  thus  more  exposed  to  injury;  it  is  also  well  supi)orted,  as 
is  seen  when,  the  parts  ))eing  relaxed,  the  fingers  are  insinuated  beneath  each 
border.  (2)  The  pull  of  the  extensor  uj^on  the  patella,  ligamentu.m  patellse,  and 
tibia  is  somewhat  outwards,  as  the  tibia  is  directed  a  little  outwards  to  the  femur, 
to  meet  the  inward  direction  of  this  bone;  the  femora  being  directed  inwards  here, 
to  bring  the  knee-joints  nearer  the  centre  of  gravity,  and,  so,  counterbalance  their 
wide  separation  above  at  the  pelvis.  The  outward  pull  of  the  quadriceps  upon  the 
patella  is,  in  all  normal  action  of  the  muscle,  counteracted  by  the  space  taken  in 
the  trochlear  surface  by  the  external  condyle,  this  being  wider  and  creeping  uj) 
higher,  and  having  a  more  prominent  and  thus  protective  lip.  In  violent  contrac- 
tion, however,  these  counteracting  points  may  be  overcome. 

The  condyles  and  tuberosities. — It  should  be  noted  that  on  the  inner  side 
the  ])rominence  of  the  internal  condyle  is  well  marked,  and  that  of  the  tiltial  tuber- 
osity is  less  so,  while  on  the  outer  side  this  condition  is  reversed.  Descending  to 
the  outer  tuberosity,  the  ilio-tibial  band  of  the  fascia  lata  can  be  traced.  The  more 
distinct  outer  tuberosity  is  a  good  landmark  for  opening  the  joint  in  amputation 
and  excision.  It  also  indicates  the  lower  level  of  the  synovial  membrane  of  the 
knee-joint.     Farther  back  is  the  biceps  and  long  external  lateral  ligament.     The 

fio.  750.— Horizontal  Section  of  the  Knee-joint.     (One-half.) 


PATELLA 
Synovial  membrane 


Capsule  - 

FEMUh- 


Crueial  ligaments 

Biceps 

Outer  head  of  gastrocnemius 

Po/i/'/i'al  iirlery 

EXTERXAL  POPLITEAL  NERVE 

I'lipliteal  vein 

INTERNA L  I'OPLITEAL  NERVE 

External  sa/Jitna  rein 


.jy —  Inner  head  of  gastrocnemius 

^^ Sartnriiis 


Sartorius 
' Gracilis 


Semi-membranosus 
Semi-tendinosus 


gap  on  the  inner  side  between  condyle  and  tuberosity  is  the  place  for  feeling  for 
a  displaced  internal  fibro-cartilage  in  '  internal  derangement '  of  the  knee.  On 
each  condyle,  posteriorly,  in  a  thin  subject  can  be  felt  its  tubercle,  which  gives 
attachment  to  the  lateral  ligament.  .  Owing  to  their  being  placed  behind  the  centre 
of  the  bone  these  ligaments  become  tight  in  extension.  On  the  upper  part  of  the 
internal  condyle  the  adductor  tubercle  and  the  vertical  tendon  of  the  adductor 
magnus  can  be  felt  during  flexion.  This  bony  point  is  a  guide  to  the  lower  epi])h- 
ysis  of  the  femur,  one  of  the  latest  to  join,  uniting  Avith  the  shaft  about  the 
twenty-first  year.  Here  the  exostoses  in  adolescents  arise.  The  inner  aspect  of 
this  condyle  faces  ])ractically  in  the  same  direction  as  the  head  of  the  femur. 

Ligamentum  patellae  and  tubercle  of  tibia. — These,  in  a  well-formed  leg, 
should,  with  the  centre  of  the  ankle-joint,  lie  all  in  the  same  straight  line,  a  useful 
point  in  the  adjustment  of  fractures  (Holden).  Behind  the  upper  half  of  the 
ligament  is  the  synovial  membrane  of  the  knee-joint;  below,  the  lower  is  separated 
from  the  tibia  by  a  deep  bursa.  In  connection  with  all  the  posterior  surface  is  fat, 
which  serves  as  a  useful  packing  in  the  different  movements  of  flexion  and  ex- 
tension.    The  tubercle  of  the  tibia  is  on  a  level  with  the  head  of  the  fibula. 

Prepatellar  bursa. — This  usually  protects  the  patella  and  u})per  j)art  of  the 
ligamentum  jiatella).  It  is  liable  to  be  enlarged  in  those  who  ha1)itually  kneel 
much.  Its  close  connection  with  the  patella  and,  at  the  sides,  with  the  joint  itself 
is  to  be  remembered   in  inflaimnations  of  the  bursa.     Usually,  two  processes  of 


THE  KNEE 


1185 


fascia  lata  passing  off  from  the  sides  of  the  j.at.lhi  upwards  to  the  tliigh  and  down- 
wards to  the  Ictr,  serve  to  conduct  inflanimation  awav  from  tlie  joint 

Synovial   membrane   (fig.  751).— To  trace  thi's,   the  largest  of  the  synovial 
membranes,  the  linger  would  start  from  the  to])  of  the  i)atella,  where  it  forms  a 
short  rul-de-mc  between  the  .puuh-ieeps  extensor  and  the  front  of  the  femur   this 
process  reachmg  al)out  an  ineli  (25  mm.)  above  the  trochlear  surface  of  the  fennu- 
At  Its  highest  ponit  this  cul-de-mc  communicates  with  another  synovial  bursa-like 


Fig.  751.— Vertical  Section  of  the  Knee-joint  in  the  Anteeo-posteeiob  Direction. 

(The  .synovial  bursa  usually  present  above  the  upper  synovial  eul-ih-mc  is  not  shown.) 

(The  bones  are  somow1l.^t  drawn  apart.) 


Fatty  tissue 
Opening  in  synovial 
membrane    behind 
crucial       ligament 
leading  into  inner 
half  of  joint 
Synovial  membrane  re- 
fleeted  off  crucial  liga- 
ments 
Cut  end  of  anterior  cru- 
cial ligament 
Posterior  crucial  liga- 
ment 
Ligament  of  vyinslow 


Muscular  fibres  of  quadriceps 
extensor 


ension  of  synovial  sac  of  knee 
upon  femur 


Tendon   of   quadriceps   extensor, 
forming  fibrous  capsule  of  joint 


PATELLA 

Pre-patellar  bursa 
CONDYLE  OF  FEMUR  (INNER) 
liigamentum  mucosum 


Fatty  tissue  between 
ligamentum  patellae 
and  synovial  sac 


Bursa  beneath  ligamentum 
patellae 


sac  lying  between  the  quadriceps  and  front  of  the  femur.  Thus,  synovial  mem- 
brane will  usually  be  met  with  two  and  a  half  inches  (62  mm.)  above  the  trochlear 
surface  or  the  upper  border  of  the  patella  when  tlie  limb  is  extended.  Flexing  the 
joint  draws  the  membrane  down  very  slightly.  During  extension,  the  al)ove  pouch 
is  supported  by  the  subcrureus.  At  the  sides  the  synovial  membrane  extends  up 
under  the  vasti  for  about  three  inches  (75  mm.)  on  the  inner  and  rather  less  on 
the  outer  side.  Traced  downwards,  the  membrane  lines  the  caiisule.  lateral  and 
posterior  ligaments.  '  It  passes  over  the  greater  portion  of  the  erucial  ligaments, 
75 


1186  SURGICAL  AND    TOPOGRAPHICAL  AXATOMY 

but  the  posterior  surface  of  the  posterior  crucial,  which  is  connected  by  means  of 
fibro-areolar  tissue  to  the  front  of  the  hganientuni  ])OSticuni,  and  the  lower  portions 
of  both  crucial  ligaments,  where  they  are  united  together,  of  course  cannot  receive  a 
complete  covering  from  the  membrane '  (Morris).  From  the  above  ligaments  the 
membrane  is  conducted,  lining  the  lower  part  of  the  capsule  and  other  ligaments, 
to  the  semi-lunar  cartilages,  first  over  their  upper  surfaces  to  their  free  borders,  and 
then  along  their  under  surfaces  to  the  tibia.  Between  the  outer  of  these  and  the 
upper  and  l^ack  i)art  of  the  tibia  is  a  prolongation  of  the  synovial  mcm])rane  to 
facilitate  the  play  of  the  popliteus  tendon.  Special  folds,  with  their  packing  of  fat, 
the  ligamenta  alaria  and  mucosa,  pass  l)etween  the  femur  and  patella. 

The  following  bursae  about  the  knee-joint  must  be  remembered.  Some,  it 
will  be  seen,  are  much  more  constant  than  others: — 

A.  In  front. — (1)  One  between  the  patella  and  skin,  the  bursa  prepatellaris 
(fig.  751);  (2)  a  deeper  one  between  the  ligamentum  patellae  and  the  upper  part  of 
the  tibia;  (3)  between  the  skin  and  the  lower  part  of  the  tubercle  of  the  tibia. 
This  is  not  constant. 

B.  On  the  inner  side. — (1)  One  between  the  inner  head  of  the  gastrocnemius 
and  inner  condyle,  often  extending  between  the  above  muscle  and  the  semi-mem- 
branosus.  This  is  the  largest  of  the  burste  about  the  knee-joint,  and,  after  adult 
life,  usually  communicates  with  the  knee-joint;  (2)  one  superficial  to  the  internal 
lateral  ligament,  between  it  and  the  tendon  of  the  sartorius,  gracilis,  and  semi- 
tendinosus;  (3)  one  beneath  the  ligament,  between  it  and  the  tendon  of  the  semi- 
membranosus; (4)  one  between  the  inner  tuberosity  of  the  tibia  and  the  semi-mem- 
branosus;  (5)  one  between  the  semi-membranosus  and  semi-tendinosus.  Of  the 
above  bursae,  the  first  two  alone  are  constant.  The  second  and  third  are  often  one 
bursa  prolonged. 

C.  On  the  outer  side. — (1)  One  between  the  outer  head  of  the  gastrocnemius 
and  the  condyle;  (2)  one  superficial  to  the  external  lateral  ligament  between  it 
and  the  biceps  tendon;  (3)  one  under  the  ligament  between  it  and  the  popliteus 
tendon;  (4)  one  between  the  popliteus  tendon  and  the  outer  condyle  of  the  femur. 
This  is  usually  a  diverticulum  from  the  synovial  membrane. 

The  following  explanations  may  be  given  of  an  inflamed  knee-joint  usually 
taking  the  flexed  position:  (1)  By  experimental  injections,  Braune  found  that  the 
capacity  of  the  synovial  sac  reaches  its  maximum  with  a  definite  degree  of  flexion, 
i.e.  at  an  angle  of  twenty-five  degrees.  (2)  As  the  same  nerves  supply  the 
synovial  membrane  and  the  muscles  which  act  upon  the  joint,  the  flexors  being 
more  powerful  than  the  extensors,  will  help  to  explain  the  flexed  position 
(Hilton). 

Anastomoses  around  the  front  and  sides  of  the  knee-joint. — The  most 
im2)ortant  of  these  take  the  form  of  three  transverse  arches.  (1)  The  highest 
passes  through  the  quadriceps  fibres  just  above  the  upper  edge  of  the  patella.  It 
is  formed  by  a  branch  from  the  deep  division  of  the  anastomotica  and  one  from 
the  superior  external  articular.  The  middle  and  lowest  arches  lie  under  the 
ligamentum  patellae.  (2)  The  middle  arch,  formed  by  branches  from  the  anasto- 
motica and  superior  internal  articular  on  the  inner  side,  and  the  inferior  external 
articular,  on  the  outer,  runs  in  the  fatty  tissue  close  to  the  apex  of  the  juitella.  (3) 
The  lowest  arch  lies  on  the  tibia  just  al:)ove  its  tulierele,  and  results  from  the 
anastomosis  of  the  recurrent  tilnal  and  the  inferior  internal  articular.  Six  arteries 
thus  take  place  in  this  series  of  anastomoses. 


POPLITEAL  SPACE 

In  flexion,  th(>  hollow  of  this  space  appears;  in  extension  it  is  obliterated  and 
its  boundaries  are  ill-defined,  the  only  one  now  to  be  made  out  being  the  semi- 
tendinosus  and  the  l>iceps. 

Popliteal  tendons. — When  the  knee  is  a  little  bent,  and  the  foot  rests 
on  tlie  ground,  the  following  can  l)e  made  out:  At  the  outer  side,  behind  the 
ilio-tibial  band,  and  descending  to  the  head  of  the  fil)ula,  is  the  tendon  of  the 
biceps.      Parallel    and    close   to   its   inner   border,    the    external    popliteal   nerve 


POPLITEAL  SPACE 


1187 


descends,  as  a  rounded  cord,  to  cross  the  neck  of  tlic  lilmla  and  enter  the  jxToncus 
longus.  In  tenotomy  of  the  biceps,  the  knife  sliould  bu  introduced  between  the 
nerve  and  the  tendon,  and  made  to  cut  from  within  outwards,  and  thus  away  from 
the  nerve.  On  the  inner  side  tlie  tendons  are  thus  arran^a-d:  Nearest  to  the  iniddle 
of  the  poi)Uteal  space  is  the  long  and  more  slender  tendon  of  the  semi-tendinosus; 
next,  the  thicker  tendon  of  the  semi-mend)ranosus;  this  and  the  gracilis,  which' 
comes  next,  appear  as  one  tendon,  but  by  a  little  manipulation  the  finger  can  be 
made   to   sink  into  the  interval   between  the  semi-mem branosus,   with   its  thick 

Fig.  752. — SiDK  Vikw  of  the  Popliteai,  Akteky. 
(From  a  dissection  in  the  lluiiterian  Museum.) 


Ffinoral  artery  and  vein 

BRA.\r/fES  OF  THE 
lyTERSAL  CUTA- 
NEOUS NERVE 


Aponeurotic  covering 
of  Hunter's  canal 


Aiiaslomolica  magna 
artery 


LONG  SAPHENOUS 
NERVE 


Vertical  fibres  of  the 
adductor  magnus 

Popliteal  artery 


VaatuB  internuB 
Cut  ed^e  of  fascia  lata 


BRANCH  OF  SAPHE- 
NOUS NERVE  TO 
PATELLAR  PLEXUS 


SMALL  SCIATIC 
NERVE 


Adductor  magnus 


Internal  snjihenous  vein 


Part  of  Bemi- 
tendinoaut) 


X 


\ 


rounded  border  externally  and  the  gracilis  inli  rnally.  The  sartorius  can  easily  be 
thrown  into  relief  on  the  inner  side  of  the  joint  by  telling  the  i)atient  to  cross  one 
leg. 

Popliteal  vessels. — The  artery  traverses  this  space  from  above  downwards, 
api)earing  l)eneath  the  semi-meml)ranosus,  a  little  to  the  inner  side  of  the  mi»ldle 
line,  and  then  ]>assing  down  in  the  centre  of  the  space  to  the  interA'al  between  the 
gastrocnemii.  Its  course  corresponds  with  a  line  drawn  from  the  inner  side  of  the 
hamstrings  to  the  centre  of  the  lower  part  of  the  space.  The  artery  bifurcates  on  tlie 
level  of  a  line  corresponding  to  the  tubercle  of  the  tibia.  It  lies  on  the  popliteal 
surface  of  the  femur,  the  posterior  ligam<mt,  and  the  ]>opliteus.      It  is  the  second 


1188 


SURGICAL  AND  TOPOGRAPHICAL  AXATOMY. 


of  these  structures,  which  usually  prevents  popliteal  aneurism  and  abscess  from 
making  their  way  into  the  joint.  The  popliteal  vein,  intimately  adherent  to  the 
artery,  lies  to  the  outer  side  above,  but  crosses  to  its  inner  side  below.  The  walls 
of  this  vein  are  thicker  and  denser  than  those  of  any  other  vein  (Tillaux).  The 
popliteal  sheath  is  also  unusually  strong.  The  internal  popliteal  nerve  crosses  the 
artery  in  the  same  direction  as  the  vein  by  which  it  is  separated  from  the  artery. 
This'nerve  is  the  direct  continuation  of  the  great  sciatic  nerve  (fig.  753). 

The  superior  articular  arteries  course  outwards  and  inwards  immediately 
above  the  condyles;  the  inferior  ones  lie  just  above  the  head  of  the  fibula  and 
below  the  internal  tuberosity  of  the  tibia  (fig.  756).  The  deep  part  of  the  anasto- 
motic artery  runs  in  front  of  the  tendon  of  the  adductor  magnus;  the  superficial 
with  the  internal  saphenous  nerve. 

Fig.  753. — Deep  View  of  the  Popr,iTEAi.  Space.     (Hirsclifeld  and  Leveille.) 


Adductor  magnus    yj 

Popliteal  Tfiii 

Popliteal  artei  ii 

INTERNAL  POPLITEAL  NERVl 

Vastus  internus 

Superior  internal  articular  artei  i 

Tendon  of  semi-membranosus 

Inner  head  of  gastrocnemius  J^f — ] 

Inferior  internal  articular  artfi  v 
Popliteal  vmi 

Popliteua   "^J' 


Tendon  of  plantari 


'iTO  Vastus  externus 

GPEA  T  SCIA  TIC  NER  VE 

hort  head  of  biceps 

'-EXTERNAL  POPLITEAL  NERVE 


Long  head  of  biceps,  cut 
Outer  head  of  gastrocnemius 


r  ( <>  VMUNICANS  PERONEI  NER  VE 


ibtrocnemiuB 


External  saj)he_nou-i  rein  and  nerre 

The  external  saphenous  vein  perforates  the  roof  of  the  popliteal  space  in  its 
lower  part.     As  a  rule,  it  is  not  visible  unless  enlarged. 

The  popliteal  glands  are  not  to  be  felt  unless  enlarged. 

Bursae  in  the  popliteal  space. — These  have  been  already  spoken  of  (page 
1187). 


THE   LEG 

Bony  landmarks. — From  the  tubercle  of  the  tibia  descends  the  anterior  border 
or  'shin.'  This  soon  becomes  sharp,  and  continues  so  for  its  upper  two-thirds; 
in  the  lower  third  it  disappears,  to  be  overlaid  by  the  extensor  tendons.  It  is 
curved  somewhat  outwards  above,  and  inwards  below.  The  inner  border  can  also 
be  felt  from  the  inner  tuberosity  to  the  internal  malleolus.  Between  these  two 
borders  lies  the  internal  surface,  subcutaneous,  save  above,  where  it  is  covered  by 
tlie  three  tendons  of  insertion  of  the  gracilis  and  semi-tendinosus,  and,  overlying 
them,  that  of  the  sartorius.     The  tibia  is  narrowest  and  weakest  at  the  junction  of 


THE  LEG 


1189 


the  middle  and  lower  thirds,  the  most  common  site  of  fracture.  Beliind  the 
internal  malleolus,  part  of  the  groove  for  and  the  tendon  of  the  til)ialis  posticus 
can  he  felt. 

The  head  of  the  libula  can  be  felt  distinctly,  but  the  shaft  soon  becomes  buried 
amongst  muscles  till  about  three  inches  above  the  external  malleolus,  where  the 
l)one  expands  into  a  lar^e  triangular  subcutaneous  surface.  This  lies  between  the 
peroneus  tertius  and  the  other  two  jjeronei.  The  peroneus  longus  overlaps  the 
brevis,  especially  in  the  upper  two-thirds  of  the  leg.     In  the  lower  third  the  brevis 


Fig.  754. — Anasto.moses  of  Tihiai,  Arteries. 


Anterior  tibial  recurrent  ■ 


^^^i  v> 


Posterior  tibial,  giving  off  muscular  and 
viedullary  branches 


Anaslumosis  0/  internal  malleolar  of  anterior i 

tibial  uith  posterior  internal  malleolar 


Internal  calcanean  . 
Internal  and  external  plantar 


Pllh 


'/:  ^: 


/ 


Popliteal 

A  nterior  tibial,  giving  off  posterior  tibial 
recurrent  and  .luperior  fibular  before 
pirrcing  interosseous  membrane  and 
anterior  tibial  afterwards 


Peroneal 


A  nterior  peroneal 
Posterior  peroneal 

--  Oommunicating 


■External  malleolar  of  anterior  tibial  joining 
posterior  peroneal 


-  ASTRAGALUS 

■  External  calcanean 


■CALCANEUM 


tends  to  become  anterior  (fig.  756).  Behind  the  external  malleolus  these  tendons 
descend  to  the  foot  in  very  close  relation  to  the  bone.  The  shaft  of  the  fibula  is 
placed  on  a  plane  posterior  to  that  of  the  tibia,  and  curves  backwards  in  a  direction 
reverse  to  that  of  the  tibia. 

Muscular  prominences. — The  space  between  the  tibia  and  fibuhv  is  mainly 
occupied  by  the  fleshy  belly  of  the  tibialis  anticus;  outside  this,  and  much  less 
prominent,  is  the  narrower  extensor  longus  digitorum;  outside  this,  again,  are  the 
peronei  longus  and  brevis.     Lower  down,  in  an  interval  l)etween  the  til)ialis  and  tlie 


1190 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


extensor  of  the  toes,  the  extensor  halkicis,  here  ahnost  entirely  tendinous,  comes 
to  the  surface.     Behind,  the  prominence  of  the  calf  is  mainly  formed  l)y  the  gas- 

FiG.  755. — The  Anterior  Tibial  Artery,  Dorsal  Artery  of  the  Foot,  and  Anterior 
Peronkal  Artkry,  and  their  Branches. 


Superior  internal  articular  artery 


Injerior  internal  articular  artery 


Anterior  tibial  recurrent  artery 


Anterior  tibial  arter 


Tibialis  amicus  musel 


ANTERIOR  TIBIAL  SERVE 


Extensor  longus  halluei 


Internal  malleolar  arter 


Anterior  annular  ligament 

Dorsalis  pedis  artery 

Innermost  tendon  of  extensor 
brevis  digitorum 

Communicating  branch 

Dorsalis  hallucis  arler 


Superior  external  articular  artery 
Inferior  external  articular  artery 


Extensor  longus  digitorum 


Extensor  longus  digitorum, 
turned  back 


Peroneus  tertius 


A  nterior  peroneal  artery 
External  malleolar  artery 

Peroneus  brevis  tendon 

Extensor  brevis  digitorum,  cut 
External  tarsal  branch 
Metatarsal  branch 
Dorsal  interosseous  artery 


trocnemius.  On  the  patient's  rising  on  tiptoe,  the  tendo  Achillis  starts  into  relief 
from  about  the  middle  of  the  leg.  Of  the  two  heads  of  the  gastrocnemius,  the  inner 
is  seen  to  be  the  larger.     On  either  side  of  the  tendon,  but  more  distinctly  on  the 


rilE  LE(i  11  id 

outer  side  where  it  is  less  overlapped  by  the  gastrocnemius,  the  soleus  comes  into 


view. 


Vessels.— The  saphena  veins  should  be  carefully  traced,  owing  to  the  ten- 
dency of  these   and   their   branches   to  become  varicose.      The  internal,  having 

Fig.  7.56.— Kelatio.\8  ok  tiif.  Popi.ite.vl  .\rtekv  to  r>oXK.s  Axn  Mlhcles. 


Sufierior  exiemal  arlicilar  arleri/ 

POPLITEA  L  XER  VE 

External  lateral  ligament 

Inferior  external  articular  artery  ■ 

Popliteus  • 

Muscular  branch  to  soleus  ■ 
Soleus  ' 
Anterior  tibial  arleni 


■I 


Siiiicrior  internal  artuu/ar  arleri/ 
P'l/iliteal  arleri/ 

Posterior  ligament  of  knee 

A:;/f/os  articular  arleri/ 
SEMI-MEMBRAN0SU3 

Inferior  internal  articular  artery 
Muscular  branch 


Peroneus  lougus  

Peroneal  arteni  _ 


BRA  XCH  OF  POSTERIOR  TIBIA  L 
SERVE   TO   FLEXOR    LONGUS' 
HALLL'CIS 

Plexor  longus  hallucis 


Cutaneous  branch  of  peroneal  artery 


Feroneus  brevis 
Continuation  of  peroneal  artery 


Tibialis  posticus 

POSTERIOR  TIBIAL  SERVE 


MUSCULAR  BRA  sen  OF  POS- 
TERIOR TIBIAL  SERVE  TO 
PLEXOR  LOSOUS  DIOITORUM 


Flexor  longus  digitorum 


Posterior  tibial  artery 


Tibialis  posticus 


<  ommunicatinri  branch 
Internal  annular  ligament 


^^1 


Internal  calcaneal  artery 


passed  from  the  arch  on  the  dorsum  uvir  the  internal  malleolus,  runs  up  the  inner 
side  of  the  leg,  along  the  inner  border  of  the  tibia,  to  the  back  of  the  internal  con- 
dyle, and  then  upwards  along  the  tliigh.  over  the  roof  of  Hunter's  canal,  to  the 


1192 


SURGICAL  AND  TOPOGRAPHICAL  ANATOMY 


saplienous  opening  (page  1138  and  fig.  769),  where  it  joins  the  femoral.  The 
internal  saphenous  nerve  joins  it  below  the  knee,  having  been  under  the  sar- 
torius  above  this  point  (page  1178  and  fig.  752).  The  external  saphenous  vein 
passes  behind  the  external  malleolus,  runs  upwards  over  the  nnddle  of  the  calf, 
and  joins  the  popliteal  by  ]ierforating  the  deep  fascia  in  the  lower  part  of  the 
popliteal  space.  This  vein  is  also  accompanied  by  a  nerve  of  the  same  name 
throughout  its  course. 

The  popliteal  artery  bifurcates  at  the  lower  border  of  the  popliteus,  about  on 
a  level  with  the  tubercle  of  the  tibia.  About  two  inches  lower  down  the  peroneal 
artery  comes  off  from  the  posterior  tibial  (fig.  756). 

The  course  of  the  posterior  tibial  corresponds  with  a  line  drawn  from  the 
centre  of  the  lower  part  of  the  popliteal  space  to  a  point  midway  between  the  tip 
of  the  internal  malleolus  and  the  inner  edge  of  the  calcaneum.  In  the  lower 
third,  the  artery  becomes  somewhat  superficial,  passing  from  beneath  the  calf 
muscles,  together  with  the  tendons  of  the  tibialis  posticus  and  the  flexor  longus 
digitorum;  and  in  a  thin  person  it  can  be  felt  beating  in  the  hollow  on  the  inner 
side  of  the  tendo  Achillis  (fig.  756). 


I 


Fig.  757. — Sectiox  of  the  Right  Leg  in  the  Upper  Third.     (Heath.) 


Tibialis  amicus 
Extensor  longus  digitorum 
Anterior  tibial  t;essels  arid  NERVE 
Peroneus  longus 

Flexor  longus  hallucis 
Soleus  with  fibrous  intersection 

Gastrocnemius 


Tibialis  posticus 
Flexor  longus  digitorum 

Internal  saphenous  vein 


COMMUNICANS  PERONEI  NER  VE 


Tendon  of  plantaris 


Peroneal  vessels\      Posterior  tibial  vessels  and  XERVE 
External  saphenous  vein  and  SERVE 


The  course  of  the  anterior  tibial  artery  corresponds  with  a  line  drawn  from  a 
point  midway  between  the  outer  tuberosity  of  the  head  of  the  tibia  and  the  head  of 
the  fibula  to  one  on  the  centre  of  the  ankle-joint.  This  line  corresponds  to  the 
outer  border  of  the  ti!)ialis  anticus  and  the  interval  between  it  and  the  extensor 
longus  digitorum  (figs.  755  and  758).  This  is  shown  when  the  first  of  these  mus- 
cles is  thrown  into  action. 

The  peroneal  artery,  given  off  from  the  posterior  tibial  about  an  inch  below 
the  popliteus,  or  three  inches  below  the  head  of  the  fibula,  runs  deeply  along  the 
inner  border  of  this  bone,  covered  by  the  flexor  longus  hallucis.  It  gives  oft'  the 
anterior  peroneal  to  the  front  of  the  limb  about  an  inch  above  the  level  of  the  ankle- 
joint. 

The  nutrient  artery  of  the  tibia  arises  from  the  ])Osterior  tibial  near  its  com- 
mencement. It  is  the  largest  of  all  the  nutrient  arteries  to  the  shafts  of  long 
bones. 

As  a  general  rule,  in  amputation  one  inch  below  the  head  of  the  fibula,  only 
one  main  artery — the  pojjliteal — is  divided.  In  amputations  two  inches  below  the 
head   of    the  fibula,    two  main  arteries — the   anterior  and   posterior  tibials — are 


THE   LEG 


1193 


divided.     In  amputations  three  inches  below  tlie  head,  three  main  arteries— the 
two  tibials  and  the  peroneal — are  divided  (liolden). 

In  an  amputation  through  the  middle  of  the  leg,  the  anterior  ti))ial   artcry 


FiG.  758.— Bkancuks  of  tuk  Extkknal  PoHLrrKAL  Nkkvk. 

/.     i      t  III 


EXTERNAL  POPLITEAL 

NERVE 

RECURRENT  ARTICULAR 


MUSCULO-CUTANEOUS 

BRANCH  TO  PERONEUS 
LONG  US 


BRANCH  TO  EXTENSOR    

LONG  US  DIGITORUM 


BRANCH  TO  PERONEUS 
B RE  VIS 


MUSCULO-CUTANEOUS 


MUSCULO-CUTA  NEO  US 
{OUTER  DIVISION) 


SHORT  SAPHENOUS 


COLLATERAL 
BRANCHES  OF  EX- 
TERNA L  S.  1  PHENO  US 

AND  Mrscrio-  I 

CUTANEOUS  TO  TOES  L 


ANTERIOR  TIBIAL 
NEB  VE 


Anterior  libiiil  mtTu 


Tibialis  anticus 


'J 


ANTERIOR  TIBIAL 
NER  VE 

MUSCULO-CUTANEOUS 
(INNER  DIVISION) 


ANTERIOR  TIBIA/. 

(OUTER  DIVISION) 
ITS  DISTRIBUTION  TO 

EXTENSOR  BR E VIS 

DIGITORUM 

A  N  TERIO  R  TIBIA  L 
(INNER  DIVISION) 


COLLATERAL 
URANd/ES  OF 
Ml  S(  I  I.  O-CU  TA  NEO  US 
LO  TOES 


would  be  found  cut  .>n  the  interosseous  men.branc  l.etweeu  ^^^^^^^'^  ^^^^  ^^^ 
the  extensor  longus  hallucis,  its  nerve  lymg  to  its  nmer  side.     ^  |.^^ ,  ^^f,  /V;^ J  ^'^^^^ 
would  be  between  the  superficial  and  deep  muscles  at  the  back  ot  the  leg  l>ing  on 


1194  SURGICAL   AXD  TOPOGRAPHICAL  AXATOMY 

the  tibialis  posticus,  its  nerve  being  to  the  outer  side.    The  peroneal  would  be  close 
to  the  fibula  in  the  flexor  longus  hallucis. 

The  musculo-cutaneous  nerve,  having,  passed  through  the  peroneus  longus, 
and  then  between  the  peroneus  longus  and  peroneus  brevis,  perforates  the  deep 
fascia  in  the  lower  third  of  the  leg  in  the  line  of  the  se])tum  between  the  peronei 
and  extensors.     Directly  after,  it  divides  into  its  two  terminal  branches. 


THE  ANKLE 

Bony  landmarks. — Malleoli. — The  following  are  the  differences  between 
them:  The  internal  is  the  more  prominent,  shorter,  and  is  placed  more  anteriorly 
than  the  outer,  being  a  little  in  front  of  the  centre  of  the  joint.  The  external 
descends  lower  by  a  half  to  three-quarters  of  an  inch,  and  thus  securely  locks  in 
the  joint  on  this  side;  it  is  opposite  to  the  centre  of  the  ankle-joint,  being  placed 
abovit  half  an  inch  behind  its  fellow.  Owing,  however,  to  the  greater  width  of  the 
internal  malleolus,  its  posterior  border  is  on  a  level  with  that  of  its  fellow.  The 
anterior  margin  of  the  lower  end  of  the  tiljia  can  be  traced  above  the  ankle-joint, 
crossed  l^y  the  tendons  given  Ijelow.  Owing  to  the  external  malleolus  descending 
lower  than  the  inner,  in  Syme's  and  Pirogoff's  amputations  the  incision  should  run 
between  the  tip  of  the  external  malleolus  and  a  point  half  an  inch  below  that  of 
the  internal  one.  When  a  fracture  is  set,  or  a  dislocation  adjusted,  the  inner  edge 
of  the  patella,  the  internal  malleolus,  and  the  inner  side  of  the  great  toe  are  useful 
landmarks  and  should  be  in  the  same  vertical  plane,  regard  being  paid  at  the  same 
time  to  the  corresponding  points  in  the  opposite  limb  (Hold en). 

Tendons. — (A)  In  front  of  ankle. — From  Avithout  inwards  are — (1)  The 
tibialis  anticus,  the  largest  and  most  internal.  This  tendon  appears  in  the  lower 
third  of  the  leg,  lying  just  under  the  deep  fascia,  close  to  the  tibia;  then,  crossing 
over  the  lower  end  of  this  and  the  ankle-joint,  it  passes  over  the  inner  side  of  the 
tarsus,  to  be  attached  to  the  inner  and  lower  part  of  the  internal  cuneiform  and  the 
adjacent  part  of  the  first  metatarsal.  (2)  The  extensor  proprius  hallucis.  This 
tendon,  concealed  above,  appears  low  down  in  a  line  just  external  to  the  last,  and 
then,  crossing  over  the  termination  of  the  anterior  tibial  vessels  and  nerves  (to 
which  its  muscular  part  lies  external),  it  descends  along  the  inner  part  of  the 
dorsum  to  l)e  attached  to  the  base  of  the  last  phalanx  of  the  great  toe.  (3)  and 
(4)  The  extensor  longus  digitorum  and  peroneus  tertius  enter  a  common  sheath  in 
the  anterior  annular  ligament.  The  former  then  divides  into  four  tendons,  which, 
joined  on  the  first  phalanx  by  slips,  three  from  the  extensor  brevis,  and,  a  little 
later,  by  slips  from  the  lumbricales  and  interossei,  are  inserted  into  the  second  and 
last  phalanges,  as  in  the  fingers.  The  peroneus  tertius  is  inserted  into  the  up^jer 
surface  of  the  base  of  the  fifth  metatarsal  bone. 

(B)  Behind. — The  tendo  Achillis,  the  thickest  of  all  tendons,  begins  near  the 
middle  of  the  leg,  in  the  junction  of  the  tendons  of  the  gastrocnemii  and  soleus. 
Very  broad  at  its  commencement,  it  gradually  narrows  and  becomes  very  thick. 
About  an  inch  and  a  half  from  the  heel,  or  about  the  level  of  the  internal 
malleolus,  is  its  narrowest  point.  After  this  it  again  expands  slightly,  to  be 
attached  to  the  middle  of  the  back  part  of  the  calcaneum.  The  long  tendon  of  the 
plantaris  runs  along  its  inner  side,  to  l)lcnd  with  it  or  to  be  attached  to  the  calca- 
neum. On  either  side  of  the  tendo  Achillis  are  well-marked  furrows  beloAv.  Along 
the  inner,  the  tendon  of  the  tibialis  posticus  and  the  posterior  tibial  vessels  and 
nerve  come  nearer  the  surface.  Along  the  outer,  the  external  saphenous  vein 
(more  superficially)  ascends  from  behind  the  external  malleolus. 

(C)  On  the  inner  side. — The  tendon  of  the  tibialis  posticus,  which  has 
previously  crossed  from  the  interspace  between  the  bones  of  the  leg  to  the  inner 
side,  lies  behind  the  inner  edge  of  the  tibia  above  the  internal  malleolus,  being 
under  the  flexor  longus  digitorum,  the  two  tendons  here  becoming  su])erlicial  on 
the  inner  side  of  the  tendo  Achillis.  It  then  passes  forwards  close  below  the  sus- 
tentaculum tali  and  the  head  of  the  astragalus,  and  then  very  close  to  the  inferior 
calcaneo-scaphoid  ligament  (vide  infra),  and  so  to  its  insertion,  by  numerous  slips, 
into  the  tarsus  and  metatarsus,  especially  the  tubercle  of  the  scaphoid.     The  tendon 


THE  AXKLE 


1195 


of  the  flexor  longiis  hallucis  cannot  be  felt.     Having  passed  internally  from  the 
fibula,  it  crosses  the  lower  end  of  the  tibia  in  a  separate  furrow,  then  grooves  the 


Fig.  759. — The  Muscles  of  the  Fijoxt  ok  the  Leg. 


Ligamentum  patellae 


CJastroenemius   — 


Extensor  propriuB  hallueis 


Dorsal  luterossei 


PeroneuB  longus 


Tibialis  anticua 


Peroneua  tertius 


Extensor  longus  digitorum 


Peroneus  tertius 


Extensor  brevis  digitorum 


back  of  the  astragalus,  and  passes  under  the  sustentaculum  tali  on  its  way  to  its 
insertion.  The  arrantrement  of  the  structures  at  the  inner  ankle  from  above  down- 
wards, and  from  within  onwards,  is  as  follows  (fig.  701):— tibialis  posticus,  flexor 


1196 


SURGICAL  AND    TOPOGRAPHICAL  AyATOMY 


longus  digitorum,  companion  vein,  posterior  tibial  artery,  companion  vein,  posterior 
tibial  nerve,  flexor  longus  halliicis. 

(D)  Tendons  at  outer  ankle. — The  tendons  of  the  two  peronei,  which  arise 
from  the  fibula  l)etween  the  extensor  longus  digitorum  and  flexor  longus  hallucis, 
pass  behind  the  external  malleolus,  the  brevis  being  nearer  to  the  lione  (fig.  75H). 
Tliey  then  pass  forwards  over  the  outer  surface  of  the  calcaneum,  separated  by  the 


Fig. 


roo. — Tr.^xsverse  Section  through  the  Lower  Third  of  the  Left  Leg, 

IMMEDIATELY   ABOVE  THE   AXKI.E.TdlXT.       (BraUUe.) 


Extensor  longus  digitorum  — 


Peroneus  longus 

Peroneus  brevis 

Flexor  longus  hallucis 


EXTERNAL  CUTANEOUS  NEE  IE  - 


Tibialis  antieus 

Extensor  proprius  hallueia 


Tibialis  posticus 
Flexor  longus  digitorum 


peroneal  tubercle  when  present,  and  diverge.  The  brevis — the  upper  one — passes 
to  the  projection  at  the  base  of  the  fifth  metatarsal;  the  longus,  lying  below  the 
brevis  on  the  calcaneum,  winds  round  the  outer  border  of  the  foot,  grooving  the 
outer  border  and  under  surface  of  the  cuboid.  Finally,  crossing  the  sole  obliquely 
forwards  and  inwards,  it  is  attached  to  the  adjacent  parts  of  the  internal  cuneiform 
and  the  back  part  and  under  surface  of  the  first  metatarsal.     While  in  connection 

Fig.  761. — Kelatioxs  of  Parts  behind  the  Ixxer  Malleoi.is.     (Heath.) 

^Tendo  Achillis 


Tibialis  posti 


Tibialis  posticus 
Tibialis  antieus  - 


-'  riexor  longus  digitorum 

pisffrior  tibia!  arl'-rii 

1" INTERIOR  TIBIAL  NERVE 


Flexor  longus  digitorum 


with  the  under  surface  of  the  cuboid,  this  tendon  is  covered  in  by  a  sheath  from 
the  long  plantar  ligament,  and  often  contains  a  sesamoid  bone. 

Annular  ligaments  and  synovial  membranes  of  tendons. — These  strap-like 
bands  of  deep  fascia,  which  serve  to  keep  the  above  tendons  in  position,  are  three 
in  number,  viz. : — 

(A)   External. — This  extends  from  the  tip  of  the  external  malleolus  to  the 


THE  AXKLE  1197 

outer  surface  of  the  calcaneum.  It  keeps  the  two  peronei  in  place,  and  surrounds 
them  behind  the  fibula  in  one  sheath  with  a  single  synovial  sac,  which  extends 
upwards  into  the  leg  for  an  inch  and  a  half,  and  sends' two  prtK-esses  into  the  two 
sheatlis  in  Avhich  the  tendons  lie  on  the  calcaneum.  Farther  on,  while  in  relation 
with  the  cul)oid,  the  peroneus  longus  has  a  second  synovial  sheath. 

(  H)  Internal. — This  crosses  from  the  internal  malleolus  to  the  inner  surface  of 
the  calcaneum.  Beneath  it  are  the  following  canals:  (1)  For  the  tibialis  posticus. 
This  tendon-sheath  is  lined  by  a  synovial  memljrane  extending  from  a  point  an 
inch  and  a  half  above  the  malleolus  to  the  scaphoid.  (2)  For  the  flexor  longus 
digitorum.  The  synovial  sheath  of  this  tendon  is  separate  from  that  of  the  closely 
contiguous  til)ialis  posticus.  It  extends  upwards  into  the  leg  about  as  high  as  the 
sheath  just  given.  It  reaches  down  into  the  sole  of  the  foot;  but  where  the  tendon 
subdivides  to  enter  the  thecse,  each  of  these  is  lined  by  a  se[)arate  synovial  sheath. 
Next  comes  (3)  a  wide  space  for  the  posterior  tibial  vessels  and  nerve;  and,  lastlv, 
(4)  a  canal,  like  the  otlier  two,  with  a  separate  synovial  sheath,  for  the  tendon  of 
the  flexor  longus  hallucis. 

(Cj  Anterior  annular  ligament. — This  is  a  double  structure.  (1)  Upper, 
above  the  level  of  the  ankle-joint,  and  tying  the  tendons  down  to  the  lower  third 
of  the  leg,  it  passes  transversely  between  the  anterior  crest  of  the  tibia  and  fibula. 
Here  is  one  sheath  only,  with  a  synovial  membrane  for  the  tibialis  anticus. 
(2)  Lower,  over  the  ankle-joint.  This  band  is  arranged  like  the  letter  •<, 
placed  thus  (fig.  759;.  It  is  attached  by  its  root  to  the  calcaneum,  and  by  its 
bifurcations  to  the  internal  malleolus  and  the  fascia  of  the  sole.  This  arrange- 
ment of  the  branches  of  this  ligament  is  not  constant.  In  this,  the  lower  annular 
ligament,  there  are  usually  three  sheaths  with  separate  synovial  membranes — the 
innermost  (the  strongest  in  each)  for  the  tibialis  anticus,  the  next  for  the  extensor 
proprius  hallucis,  and  the  third  common  to  the  extensor  cornnumis  and  peroneus 
ti-rtius. 

Points  in  tenotomy  and  guides  to  the  tendons. — The  tendo  Achillis 
sliould  be  divided  about  an  inch  and  a  half  above  its  insertion,  its  narrowest  point, 
which  is  about  on  a  level  with  the  internal  malleolus.  The  knife  should  be  intro- 
duced on  the  inner  side  and  close  to  the  tendon,  so  as  to  avoid  the  posterior  tiljial 
artery  (fig.  756). 

The  tibialis  anticus  is  often  cut  about  an  inch  above  its  insertion  into  the 
internal  cuneiform,  a  point  whicli  is  below  the  level  of  its  synovial  sheath.  The 
tendon  has  here  the  dorsalis  pedis  on  its  outer  side,  but  scjiarated  Ijy  the  tendon  of 
the  extensor  proprius  hallucis.     The  knife  is  introduced  on  this  side. 

The  tibialis  posticus. — The  usual  rule  for  dividing  this  tendon  is  to  take  a 
spot  two  inches  above  the  internal  malleolus,  and  as  accurately  as  possiljle  midwav 
between  the  anterior  and  internal  borders  of  the  leg.  This  point  will  give  the  inner 
margin  of  the  tibia,  in  close  apposition  to  which  the  tendon  is  lying,  and  is  a  point 
at  which  the  tendon  is  rather  farther  from  the  artery  than  it  is  below,  and  is  also 
above  the  commencement  of  its  synovial  sheath.  A  sharp-pointed  knife  is  used 
first  to  open  the  sheath  freely,  and  then  a  blunt-pointed  one  to  divide  the  tendon. 
The  fiexor  longus  digitorum  is  usually  cut  at  the  same  time. 

Owing  to  the  great  difficulty  in  making  sure  of  dividing  the  tibialis  posticus 
tendon  at  this  spot,  and  the  risk  of  cutting  the  posterior  tibial  artery  (fig.  756),  it 
has  been  advised  of  late  years  (Parker)  to  divide  this  tendon  together  with  that  of 
the  anticus  simultaneously  by  an  incision  a  little  below  and  anterior  to  the  tip  of 
the  internal  malleolus.  Other  guides  are  the  position  of  the  astragalf>-sca})hoid 
joint,  and,  where  the  deformity  is  of  gome  standing,  the  crease  wliich  denotes  the 
inversion  of  the  foot.  The  position  of  the  two  tibial  arteries  should  be  noted,  and 
also  the  lines  along  which  the  tendons  are  converging — the  one  across  the  lower 
end  of  the  tibia,  the  other  from  behind  tlie  tibia  and  below  the  sustentaculum  tali 
to  the  line  of  the  scaphoid  and  internal  cuneiform.  Mr.  R.  W.  Parker  has  nanu-d 
this  operation  syndesmotomy,  as  he  rightly  considers  that  the  astragalo-scaphoid 
ligaments  require  division  at  the  same  time. 

Peronei. — The  peronei,  longus  and  brevis,  may  be  divi<leti  two  inches  above  the 
external  malleolus,  so  as  to  be  above  the  level  of  their  synovial  sheath.  The  knife 
should  be  inserted  verv  close  to  the  bone,  so  as  to  i)ass  between  the  fibula  and  the 


1198 


SURGICAL  AND    TOPOGRAPHICAL  ANATOMY 


tendons.  Division  below  the  external  malleolus  is  somewhat  easier,  but  as  this 
opens  their  synovial  sheath  or  sheaths  {vide  supra,  page  1197),  it  requires  scrupu- 
lous care  as  to  cleanliness. 

THE  FOOT 

Bony  landmarks. — The  following  are  of  the  greatest  practical  importance 
owing  to  the  operations  which  are  jjerformed  upon  the  foot. 

(A)  Along  the  inner  aspect  of  the  foot  are  the  following: — 

(1)  Internal  tuberosity  of  the  calcaneum;  (2)  internal  malleolus;  (3)  one  full 
inch  below  the  malleolus,  the  sustentaculum  tali;  (4)  about  an  inch  in  front  of 
the  internal  malleolus,  and  a  little  lower,  is  the  tubercle  of  the  scaphoid,  the  gap 
between  it  and  the  sustentaculum  ])eing  filled  by  the  calcaneo-scaphoid  ligament 
and  the  tendon  of  the  tibialis  posticus,  in  which  there  is  often  a  sesamoid  Ixnie; 
(5)  the  internal  cuneiform;  (6)  the  base  of  the  first  metatarsal;  and  (7)  the  head 
of  the  same  bone,  with  its  vSesamoid  bones  below  (Holdenj. 

(B)  Along  the  outer  aspect  are — (1)  The  outer  tuberosity  of  the  calcaneum; 


Fig.  762. — Articulations  of  the  Foot,  Dorsal  Aspect.     (Bellamy.) 


TUBERCLE  OF  SCAPHOID 


l;ne  of  hey  -' 


LINE  OF  CHOPART 


TUBERCLE  OF  FIFTH    METATARSAL 


(2)  the  external  malleolus;  (3)  the  peroneal  tubercle  of  the  calcaneum  (when 
present),  one  inch  below  the  malleolus,  with  the  long  peroneal  tendon  below  it,  and 
the  short  one  above;  (4)  the  projection  of  the  anterior  end  of  the  calcaneum, 
and  the  calcaneo-cuboid  joint,  midwa}^  between  the  tip  of  the  external  malleolus 
and  the  base  of  the  fifth  metatarsal  bone;  (5)  the  base  of  the  fifth  metatarsal  bone; 
(6)  the  head  of  this  bone. 

Levels  of  joints  and  lines  of  operations. — In  Syme's  amputation  through 
the  ankle-joint,  the  incision  starts  (say  in  the  case  of  the  left  foot)  from  the  tip  of 
the  external  malleolus,  and  is  then  carried,  pointing  a  little  ])ackwards  towards  the 
heel,  across  the  sole  to  a  point  half  an  inch  below  the  internal  malleolus. 

In  Pirogoff's  amputation  the  incision  begins  and  ends  at  the  same  points,  but 
is  carried  straight  across  the  sole.  In  each  am})Utation  the  extremities  of  the  above 
incision  are  joined  by  one  going  straight  across  the  ankle-joint,  which  lies  about 
half  an  inch  above  the  tip  of  the  internal  malleolus. 

In  Chopart's  medio-tarsal  amputation  (fig.  762),  which  passes  between  the 
astragalus  and  the  sca})hoi(l  on  the  inner  side,  and  the  calcaneum  and  the  cuboid 
on  the  outer,  the  line  of  the  joints  to  be  opened  would  be  one  drawn  across  the 
dorsum  from  a  point  just  behind  the  tuberosity  of  the  scajthoid  to  a  i)oint  corre- 


thp:  foot 


HDD 


spending  to  the  calcaneo-cuboid  joint,  just  midway  between  the  tiji  of  tin-  t-xternal 
malleolus  and  the  haso  of  the  fifth  metatarsal  I)()n"e. 

In  Lisfranc's,  (ir  Key's,  or  tlie  tarso-metatarsal  amputation,  the  Imses  of 
the  fifth  and  first  metatarsals  must  he  defined.  Tlie  first  of  tliese  ean  always  he 
detected,  even  in  a  stout  or  swollen  foot;  on  the  inner  side  the  joint  between  the 
internal  cuneiform  and  the  first  metatarsal  bone  lies  an  inch  and  a  half  in  front  of 
the  sca])hoid  tubercle.  In  oj)eninf;  the  joint  l)etween  the  second  metatarsal  and 
the  middle  cuneiform,  its  position  (the  base  of  the  former  bone  projecting  upwards 
on  to  a  level  one-third  or  one-fourth  of  an  inch  aljove  the  others),  and  the  way 
in  which  it  is  locked  in  between  its  fellows  and  the  cuneiform  bones,  must  l)e 
remembered. 

In  marking  out  the  flaps  for  the  amputation  of  the  great  toe,  the  large  size 
of  the  head  of  the  first  metatarsal,  and  the  im})urtance  of  leaving  tliis  so  as  not  to 
diminish  its  supporting  power  and  the  treading  Avidth  of  the  foot,  and  thus  of 
marking  out  flaps  suthciently  long  and  large,  must  be  l)orne  in  mind.  In  amputa- 
tion of  the  other  toes,  the  line  of  their  metatarso-i)halangeal  joints  lies  a  full  inch 
above  the  web. 

Bursae  and   synovial  membranes. — The  synovial  sheath  of  the   extensor 


Fig.  763.— Vertical  Section  THROUon  the  Ci-neiform  and  Cuboid  Bones.     (One-half.) 

Dorsiilis  peili.s  vessuls  and  SERVE 
Extensor  proprius  hallucia 

INTERNAL  CUNEIFORM         |      MIDDLE  CUNEIFORM 


Tibialis  amicus 


EXTERNAL  CUNEIFORM 

Extensor  brevis  digitorum 
Dorsal  aponeurosis 


Peroneus  tertius 


Abductor  hallucis 
Internal  plantar  ivj.v.sr/*  mid  SEE  VE 
Abductor  hallucis 

Flexor  longus  halluots 

Plantar  fascia 
Flexor  longus  digitorum 

Flexor  brevis  digitoruin 


Abductor  minimi  digiti 


Erlerniit  jdnntar  ressels  and  SEE  VE 
Tendon  of  peroneus  longus 


proprius  hallucis  extends  from  the  front  of  the  ankle,  over  the  inste]).  as  far  as  the 
metatarsal  bone  of  the  great  toe.  There  is  generally  a  bursa  over  the  in-^teji.  above, 
or  it  may  be  below,  the  tendon.  There  is  often  an  irregular  Imrsa  between  the 
tendons  of  the  extensor  longus  digitorum  and  the  jirojecting  end  of  the  astragalus 
over  which  the  tendons  play.  There  is  much  friction  here.  It  is  well  to  l)e 
aware  that  this  bursa  sometimes  communicates  with  the  joint  of  the  head  of  the 
astragalus  ('Holden).  There  is  a  deep  synovial  bursa  between  the  tendo  Achillis 
and  the  calcaneum.  Numerous  other  bursa?  may  appear  over  any  of  the  bony 
l)oints  in  the  foot,  especially  when  they  are  rendered  over-prominent  by  morbid 
conditions. 

Synovial  membranes. — In  addition  to  that  of  the  ankle-joint,  there  are  six 
synovial  iiienil)ranes  in  the  tarsus,  viz.: — (1)  Posterior  calcaneo-astragaloi<K 
peculiar  to  these  bones;  (2)  anterior  calcaneo-astragaloid,  common  to  these  bones 
and  the  scaphoid;  (3)  between  the  calcaneum  and  the  cuV)oid;  (4)  between  the 
cuboid  and  the  outer  two  metatarsals;  (5)  between  the  internal  cuneiform  and  the 
first  metatarsal;  (6)  a  complicated  and  extensive  one.  which  l)ranches  out  between 
the  scaphoid  and  cuneiform  ])ones;  between  the  cuneiforms;  between  the  external 
cuneiform  and  the  cuboid;  between  the  middle  and  outer  cuneiform  and  the  second 


1200 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


and  third  metatarsal  bones;  and  between  the  second  and  tlnrd.  and  the  third  and 
fourth  metatarsal  bones  (fig.  762). 

Dorsal  artery. — The  line  of  this  is  from  the  centre  of  the  ankle-joint  to  the 
upper  part  of  the  first  interosseous  space.  On  its  inner  side  is  the  tendon  of  the 
extensor  proprius  hallucis;  on  its  outer,  the  innermost  tendon  of  the  extensor 
longus  digitorum.  It  is  crossed  by  the  innermost  tendon  of  the  extensor  brevis. 
The  origin  of  this  muscle  should  be  marked  on  the  outer  and  fore  part  of  the 
calcaneum. 


Fig.  7fi4.— Superficial  Nera'es  in  the  Sole  of  the  Foot.     (Ellis.) 


Abductor  hallucis 


Flexor  brevis  digitorum 

JSTERXAL  PLANTAR 
SERVE 
Internal  plantar  arteri; 


BRANCH  OF  INTER- 
NA L  PLANTAR 
NERVE  TO  INNER 
SIDE  OF  HALL  rx 


MMl"  i    k 


Abductor  minimi  digiti 


External  plantar  artery 

EXTERNAL  PLANTAR 
NER  VE 


DIGITAL  COLLATERAL 
BRANCHES  OF  EX- 
TERNAL PLANTAR 


DIGITAL  COLLATERAL 
BRANCHES  OF  INTER- 
NAL PLANTAR 


Cutaneous  nerves  (figs.  764,  770). — The  sites  of  these,  numerous  on  the 
dorsum  of  the  foot,  are  as  follows: — The  musculo-cutaneous  nerve,  having 
l)erforated  the  fascia  in  the  lower  third  of  the  leg,  divides  into  two  chief  branches, 
inner  and  outer,  which  supply  all  the  toes  save  the  outer  part  of  the  little,  and 
the  adjacent  sides  of  the  first  and  second.  The  anterior  tibial  l)ecomes  cutaneous 
in  the  first  space,  and  is  distributed  to  the  contiguous  sides  of  the  above-mentioned 
toes.  Tlie  external  saphenous  nerve  runs  with  its  vein  below  the  malleolus, 
and  supplies  all  the  outer  l)ordi'r  of  the  foot  and  the  outer  side  of  the  little  toe. 
The  internal   saphenous   nerve,  coursing  with  its  vein  in  front  of  the  internal 


THE  FOOT 


1201 


Fig.  705. — Pl.^xt.^r  Aeteeie-s  (Deep). 
(From  a  dissection  in  the  Hunterian  Museum.) 


Internal  calcanean  branc/i 
of  posterior  tibial 


Posterior  tibial  artery 


Abductor  hallucis,  cut 


Internal  plantar  artunj 


Inner  head  of  flexor 
accesaorius 


Flexor  longus  hallucis 

External  plantar  artery 

Adductor  hallucis 

Flexor  brevis  hallucis 


Princeps  hallucis  artery  


Flexor  tendons, 
cut  short 

Collateral  diyital  branch  of 
princeps  lialhicis  to  inner 
side  oj  great  toe 


Cutaneous  and  anastomotic 
branches  of  external 
plantar 

Outer  head  of  flexor 
accesBorius 


Abnormal  muscular  slip 
Muscular  branch 
Cutaneous  branch 

Collateral  digital  artery  to 
outer  side  of  little  toe 

Second  digital  artery 

Third  digital  artery 

Fourth  digital  artery 


Fig.  766. — Loxgitudixal  Section  of  Foot.     (One-third.)     (Braune.) 

Tendo  Achillis 
Posterior  tibial  vessels 
ASTRAGALUS  and  NER  VE 

SCAPHOID 
INTEBNAL  CUNEIFORM 

£zteBSor  propriuB  hallucis 


CAICANEUU 
Abductor  minimi  digit! 
External  plantar  vessels  and  SERVE 
Accesaorius 

Flexor  brevis  digitorum      Flexor  communis  diirltorum 
IXTERSAL  I'LAMAR  SERVE 


Flexor  longus  hallucis 

Flexor  brevis  hallucis  | 

Lumbricalis 


1202 


SURGICAL   AXD    TOPOGRAPHICAL  ANATOMY 


malleolus,   supplies   tlie   inner   border  of   the  foot  as  far  as  the  middle  of   the 
inste]>. 

Plantar  arteries. — The  line  of  the  internal  would  be  one  drawn  from  the 
])ifureation  of  the  posterior  tibial,  or  about  midway  between  the  tip  of  the  internal 
malleolus  and  the  inner  border  of  the  heel,  to  the  middle  of  the  plantar  surface  of 
the  great  toe.  The  course  of  the  external  plantar  runs  in  a  line  drawn  from  the 
l>ifurcation,  first  obliijUely  across  the  foot  to  a  i)oint  a  little  internal  to  the  inner 
side  of  the  base  of  the  tifth  metatarsal,  and  thence  obliciuely  across  the  foot  till  it 
reaches  the  first  space  and  joins  with  a  communicating  branch  from  the  dorsal 
artery.  It  thus  crosses  the  foot  twice.  In  the  first  part,  it  is  more  superficial,  in 
the  second  very  deep;  it  here  forms  the  plantar  arch,  and  is  only  separated  from 
the  bases  of  the  metatarsals  bv  the  interossei. 


ARCHES   OF   THE   FOOT 

These  are  two — the  longitudinal  and  the  transverse. 

(A)  Longitudinal  arch  (figs.  766,  767,  and  76S). — This  is  by  far  the  most 
important.  Extent :  From  the  heel  to  the  heads  of  the  metatarsal  l:)ones.  The  toes 
do  not  add  much  to  the  strength  and  elasticity  of  the  foot  (Humphry).  They  en- 
large its  area  and  adapt  it  to  inequalities  of  the  ground,  are  useful  in  climbing,  and 


Fig.  767.— The  Aech  in  the  Ordixaey  Posmox  of  Standing.     (Ellis,  of  Gloucester, 


Muscles  going  to  form  the 
teudo  Achillis 


Tibialis  posticus 


'in  giving  an  impulse  to  the  step  before  the  foot  is  taken  from  the  ground,  in  the  third 
stage  of  walking.  Two  pillars. — Professor  Hum]iliry  lays  stress  on  the  important 
diflferences  between  these  two:  (1)  Posterior  pillar;  This  consists  of  the  calca- 
neum  and  hinder  part  of  the  astragalus,  viz.  only  two  bones  in  order  to  secure 
solidity,  and  to  enable  the  calf-muscles  to  act  directly  upon  the  heel,  without  any 
of  that  loss  of  ])ower  whidi  would  be  brought  ai)out  by  many  moving  joint- 
surfaces.  (2)  Anterior  pillar :  Here  there  are  many  liones  and  joints  to  jirovide 
(a)  elastic  springiness,  and  (h)  width.  This  anterior  pillar  may  again  l)e  divided 
into  two:  (a)  An  inner  pillar,  very  elastic,  consisting  of  the  astragalus,  scaphoid, 
three  cuneiforms,  and  three  inner  metatarsals,  (b)  An  outer,  formed  l)y  the 
cuboids  and  two  outer  metatarsals.  This  is  stronger  and  less  elastic,  and  tends  to 
buttress  up  the  inner  pillar.  Keystone  :  This  is  represented  by  the  summit  of 
the  trochlear  surface  of  the  astragalus.     It  differs  from  the  keystones  in  ordinary 


ARCHES   OF  THE  FOOT 


1203 


arches  in  the  following  important  particulars  (Hunii>hry):  {a)  in  not  being 
wedge-shaped;  (/v)  in  not  being  so  placed  as  to  su])port  and  receive  support  from 
the  two  halves  of  the  arch:  in  front  tlie  astragalus  does  fulHl  this  condition  1)V 
fitting  into  the  scaphoid;  behin<l,  it  overlaps  the  ealcaneum  without  at  all  sup])(.i-t 
hig  it;  (c)  this  areh  and  the  su])i)()rt  of  its  keystone  largely  depend  on  ligaments 
and  tendons;  (//)  it  is  a  mobile  keystone:  to  give  it  chances  of  shifting  its  i)ressure, 
and  so  ol)taining  rest,  its  e(piilil)riuni  is  not  always  maintained  in  one  jjosition. 

(B)  Transverse  arch  (fig.  708). — This  is  best  marked  about  the  centre  of  the 
foot,  at  the  instep,  ah  nig  the  tarso-metatarsal  joints.  This,  as  well  as  the  longitu- 
dinal arch,  yields  in  walking,  and  so  gives  elasticity  and  spring. 

Uses  of  the  arches. — (1)  They  give  combined  elasticity  and  strength  to  the 
tread.  Thus  they  give  firmness,  free  (piickness,  and  dignity,  l)oth  in  standing  and 
walking,  instead  of  what  we  see  in  their  absence,  viz.  the  lameness  of  an  artificial 
limb,  and  the  shuifling  or  hobbling  which  goes  with  tight  l)00ts,  deformed  toes, 
fiat-foot,  bunions,  corns,  etc.;  (2)  they  protect  the  plantar  vessels,  nerves,  and 
muscles;   (o)  they  add  to  man's  height;   (4)  they  make  his  gait  a  i)erfect  combina- 

FiG.  7(5S.— This  shows  the  Effect  of  Muscular  Action  in  thkowixg  up  the  Arch. 


Tendo  Aehillis 


Tibialis  posticus 


Flexor  longus  halluces 


tion  of  plantigrade  and  digitigrade,  as  is  seen  in  man's  walking,  wlien  he  uses  first 
the  heel.  tlii'U  all  the  foot,  and  then  the  toes  (Humphry). 

Maintenance  of  the  arch. — (1)  Plantar  fascia. — This  is  (a)  a  binding  tie 
between  tlie  pillars  of  the  longitudinal  arch;  (/>)  it  protects  the  structures  beneath; 
(c)  it  is  a  self-regulating  ligament  and  protection.  Thus,  having  a  quantity  of 
muscular  tissue  attached  to  its  ui)i)er  and  back  part,  it  constantly  responds  by  the 
contraction  of  this,  to  the  amount  of  any  i)ressure  made  upon  the  foot.  (2) 
Calcaneo-scaphoid  ligament. — This  is  a  thick  plate  of  fibrous  tissue,  partly 
elastic,  attached  to  the  under  surface  of  the  ealcaneum,  sustentaculum  tali,  and 
scaphoid.  It  is  thickest  at  its  inner  side,  where  it  blends  with  the  anterit»r  part  of 
the  deltoid  ligament,  and  where  the  tibialis  posticus  jiasses  into  the  sole,  giving 
much  sui)port  to  the  head  of  the  astragalus,  ami  assisting  the  jiower  and  s])ring  of 
this  ligament  {vide  infra).  (3)  Calcaneo-cuboid  ligaments,  (n')  Long;  (h) 
short. — These  ligaments  are  the  main  su]>port  i>t'  the  outer,  firm,  and  less  elastic 
part  of  the  longitudinal  arch.  (4)  Tibialis  posticus. — The  reason  of  this  muscle 
having  so  manv  insertions  below  is  to  l»race  together  the  tarsal  bones,  and  to  jirevent 


1204 


SURGICAL  AND   TOPOGRAPHICAL  ANATOMY 


Fig.  769.— The  Superficial  Veixs  and  Lymphatics  of  the  Left  Lower  Limb. 


Superficial  epigastric  vein 


Lymphatics  from  penis  and 
scrotum 
Common  femoral  vein 

Superficial  femoral  lymphatic 

glands 
Superficial  external  pudic  vein 


Internal  femoral  cutaneous  vein  , 


Lon,g  saphenous  vein 


INTERNAL  MALLEOLUS 
Dorsal  venous  arch 


Superficial  lymphatics  from 
lateral  wall  of  abdomen 

Superficial  lymphatics  from 
lower  and  anterior  walls 
of  abdomen 


Superficial  inguinal 

lymphatic  glands 

Superficial  circujnflex 

iliac  vein 


External  femoral 
cutaneous  vein 


ARCHES   OF  THE  FOOT 


1205 


their  separation  when,  in  treading,  the  ehistic  anterior  i)illar  tends  to  widen  out.  Of 
these  numerous  offsets,  that  to  tlie  scaphoid  is  the  most  important.  Thus  it 
strengthens  the  cakaneo-scaphoid  ligament  hy  blending  with  it,  and  thus  suj)])orts 
the  arch  at  a  trying  time.  By  coming  into  action  when  the  heel  is  raised  (fig.  TGS), 
this  tendon  helps  the  calcaneo-scaphoid  ligament  to  su}»port  the  head  of  the 
astragalus,  and  to  maintain  the  arcii  of  the  foot  when  tlie  weight  of  the  body  is 
thrown  forward  on  to  the  instep.  In  other  words,  the  tibialis  ])Osticus  comes  into 
play  just  when  the  heaviest  of  its  duties  is  devolving  upon  this  ligament,  viz.  when 
the  heel  is  being  raisetl,  and  the  Ixxly-weight  is  being  thrown  over  tlie  instep  on  to 
the  op})osite  foot.  (5  )  Peroneus  longus. — This  raises  the  outer  jiillar,  and  steadies 
the  outer  side  of  the  arch.      Further,  by  its  strong  process  attached  to  the  first 


Fig.  770. — Distribution   of  Cl'taneous  Nerves  on  the  Posterior  and  Anterior 
Aspects  of  the  Inferior  Extremity. 


LAST 
THURA  CIC 
ILIO-HYPO- 
GASTRIC 


EXTERNA  L 
CUTANEOLS 


EXTERNAL 
CUTAXEOVS 


COMMVNI- 

CANS 
FIBULA  RI^ 


SHORT 
SAPHENOUS 


POSTERIOR 
BRAXrHE^ 

OF  /.i:vn.\R 

IfER  VES 

PfisTEnroB 

BKASnlES 
OF  SM/tAL 
XEIl  VES 

PERFORA TIKG 
CVTASEOCSOF 
FOCRTH    SAC- 
RAL 


BRASORES  OF 
UMALI. 
SCI  A  TIC 

OBTCRATOB 


POSTERIOR 
BRA.Vr/f  OF 
ISTERSAL 
rUTASEorS 

coMXirsi- 
rA.\s 
TIBIALIS 


ILIO- 
INGUINAL 


TWIO 
FROM  IN- 
TERNAL 
rUTA- 
NEO  US 


INTERNAL 
CUTA- 
NEOUS 


PATELLAR 
BRANiH 

OF  Losn 

SAPHE- 
NOUS 

LONG 
SAPHE- 
NOUS 


TWIGS  FROM 
LONG 
SAPHENOUS 


INTERNA  L 
CALCANEAN 


ANTERIOR 
TIBIA  L 


EXTERNAL 
CUTA- 
NEOUS 


GEN  I  TO- 
CRURAL 


MIDDLE 
CUTA- 
NEOUS 


CUTA- 
NEOUS 
BRA  NCH  OF 
EXTERNA  I. 
POPLITEAL 


MUSCULO- 
CUTA- 
NEOUS 

SHOE  T 

SAPHi:- 

NOUS 


metatarsal  bone,  it  keeps  the  great  toe  strapped  down  firmly  against  the  ground; 
thus,  keeping  down  the  anterior  pillar  of  the  longitudinal  arch,  it  aids  the  firm- 
ness of  the  tread  (Humphry).  (6)  Tibialis  anticus. — This  braces  up  the  key- 
stone of  the  arch.  Thus,  by  keeping  up  the  internal  cuneiform,  it  maintains 
the  scaphoid,  and  so  indirectly  the  astragalus,  in  situ. 

(7)  Dr.  Ellis  (of  Gloucester)  has  drawn  especial  attention  to  the  action  of  the  long 
flexors  as  bow-strings  or  tie-rods  as  they  tighten  in  their  contraction,  and  so 
diminish  the  distance  between  their  jioints  of  attachments  to  the  toes  and  the  sjtot 
where  the  tendons  pass  round  the  os  calcis.  thus  bracing  up  the  arch.  Of  these 
flexors  the  flexor  longus  hallueis  has  especial  influence,  as  shown  by  the  stage- 
dancer,  who  supports  herself  literally  on  one  toe.  The  flexor  longus  digitorum, 
while   of  less  influence  than  the   flexor  longus   hallueis,   serves  two   important 


1206  SURGICAL  AND   TOPOGRAPHICAL  AXATOMY 

purposes,  one  of  ])assing  beneath  and  thus  picking  up  the  other  one,  the  flexor 
longus  halhicis.  Further,  it  draws  the  four  smaller  toes  firmly  against  the  ground, 
the  object  of  the  smaller  toes  being,  as  far  as  possible,  to  grip  the  ground.  (8) 
Tlie  same  authority  points  out  that  the  possession  by  the  great  toe  of  two  phalanges 
only  is  to  enable  it  to  form  a  firm  solid  base,  on  which  not  only  the  flexor  longus 
haliucis  and  the  peroneus  longus  act, but  also  the  smaller  muscles,  by  holding  this 
toe  down  and  keeping  it  straight  in  all  its  length.  The  two  heads  of  the  short 
flexor,  the  abductor  and  adductor,  '  one  pulling  one  way  and  one  in  the 
opposite  direction,  and  like  the  two  reins  of  a  bridle  when  both  are  jiulled  together, 
have  a  joint  or  a  collective  action.'  The  above  three  short  muscles  are  to  l)e 
regarded  as  one  set  of  flexor  muscles  whose  ol>ject  is  to  hold  down  the  first  phalanx 
finnly,  so  that  the  powerful  flexor  longus  haliucis,  acting  on  the  second,  exerts  all 
its  influence  on  a  straight  great  toe. 

Fig.  769  is  introduced  here  to  remind  the  student  of  the  ari-angement  of  the 
superficial  lymphatics  of  the  lower  extremity. 

These  folloAV  chiefly  the  saphena  veins,  and  enter  the  inguinal  (page  667)  and 
popliteal  glands.  The  superficial  lymphatics  of  the  buttock  enter  the  outer,  and 
those  over  the  adductor  muscles  the  innermost  group  of  the  inguinal  glands. 

The  deep  lymphatics  of  the  loAver  limb,  comparatively  few  in  number,  follow 
the  course  of  the  deeper  vessels.  After  passing  through  some  four  or  five  glands 
deeply  placed  about  the  popliteal  vessels  (these  glands  also  receive  the  lymphatics 
along  the  external  saphenous  vein)  the  lymph  is  carried  up  by  lymphatics  along 
the  femoral  artery  to  the  deep  femoral  or  inguinal  glands.  These  are  found 
around  the  upper  part  of  the  femoral  vessels;  one  verv  often  occupies  the  femoral 
canal. 

Fig.  770  shows  the  distribution  of  the  superficial  nerves  on  both  aspects  of 
the  limb. 


TRU  REGIONS  OF  THE  ABD03IEN 

By  WILLIAM  AXDERSOX,  F.R.C.S. 

As  the  plan  of  segmenting  the  ventral  surface  of  the  abdomen  by  means  of  two 
horizontal  and  two  vertical  or  nearly  vertical  lines,  has  survived  the  test  of  tiine, 
it  might  be  assumed  that  it  is  a  resource  of  some  practical  value  to  the  physician 
and  surgeon.  It  is,  however,  a  curious  fact  that,  although  the  nine  historical 
regions  of  the  abdomen  have  been  universally  accepted  in  British  and  continental 
schools  for  at  least  forty  years,  and  may  be  traced  back  to  a  very  much  more 
remote  period,  no  attempt  has  ever  been  made  to  secure  uniformity  in  the  plan  of 
their  delimitation.  Almost  every  anatomical  writer  has,  in  fact,  elected  to  follow  a 
system  of  his  own,  with  the  result  that  there  are  at  the  present  moment  nearly  a 
score  of  different  schemes  in  our  recognised  text-books.  There  is  little  doubt  that 
it  were  better  to  abandon  altogether  the  pretence  of  a  regional  subdivision  than  to 
employ  terms  which  have  no  scientific  meaning,  but  it  may  be  hoped  that  some 
accord  will  soon  be  arrived  at. 

Whatever  system  be  adopted,  it  is  necessary  that  the  boundary  '  lines '  should 
lie  converted  into  planes  carried  through  the  wdiole  depth  of  the  abdomen,  and 
defined  on  the  dorsal  as  well  as  on  the  ventral  surface  of  the  trunk,  and  that  the 
structures  cut  tlirough  by  these  planes  should  be  noted,  as  well  as  those  comprised 
within  the  regions  which  they  separate.  It  should,  of  course,  be  recognised  that 
the  relations  so  defined  can  only  be  approximate,  on  account  of  the  wide  range  of 
physiological  variation  in  the  position  of  the  al)dominal  contents;  hut  this  being 
understood,  a  regional  type  Avould  be  of  material  service  in  medical  education. 

If  we  retain  the  subdivision  into  nine  segments,  it  remains  only  to  consider  the 


THE  REGIOXS   OF  THE  ABDOMEN 


120- 


method  of  delimitation.  Firstly,  for  the  hif/her  horizontal  plane,  the  mo^ft  suitable 
level  appears  to  be  the  lowest  point  of  the  tenth  costal  cartilage.  This  plane  passes 
through  the  second  lumbar  vertebra  posteriorly,  and  lies  about  two  inches  above 
the  umbilicus  in  front.  It  cuts  through  the  stomach,  the  transverse  colon,  the 
ascending  and  descending  colon,  the  duodenum  (lower  curvature j  and  small 
intestine,  and  the  kidneys.  For  the  lower  horizontal  jtlane  Ave  have  the  choice  of 
two  levels — that  of  the  anterior  superior  iliac  spine,  whidi  lies  about  an  inch  below 
the  level  of  the  sacral  promontory,  and  that  of  the  tuljcrculum  crista',  recently 
proposed  by  Professor  Cuuningluim. 

The  plane  of  the  tuberculum  cristse  (intertuberculous  plane)  has  been  adopted 
by  Quain  and  Cunningham;  but  the  lower  of  the  two  alternative  planes,  that  of 
the  anterior  iliac  spines,  seems  the  more  definite  and  convenient  for  clinical  demon- 
stration. 

This  interspinous  pdane,  carried  horizontally  V>ackwards  from  the  symphysis  into 
the  true  pelvis,  cuts  the  small  intestine,  the  caecum  or  lower  part  of  the  ascending 
colon,  the  sigmoid  flexure,  the  upper  end  of  the  rectum,  the  fundus  uteri,  the 
ovaries  and  Fallopian  tubes,  and  the  distended  bladder,  and  hence  forms  a  valuable 
guide  to  the  surgeon. 


Fig.  771. — Diagram  <»f  the  Abdomixal  Regiox.s. 


Joint    between     meso-ster- 
num  and  ensiform  cartilage 


Tip  of  ensiform  cartilage 
Cosiai  border 


UPPER  HORIZONTAL  PUNE 


LOWER  HORIZONTAL  PLANE  A,  AT 
LEVEL  Of  TUBERCLES  OF  IL'AC 
CREST 

LOAER  HOmZONTAL  PUNE  B,  AT 
LEVEL  OF  ANTERIOR  ILIAC  SPINES 


VERTICAL  PLANE  A,  FROM  UIDDLE  OF 
POUPARTS  LIGAMENT 


VERTXAL  PLANE  B.  AT  OUTER  BOR- 
DER OF  RECTUS  iSEMILUNAR  LINE) 


SUMMIT  OF  SVMPHrSIS  PUBIS 


For  the  longitudinal  plane  on  each  side,  that  corresjtonding  to  the  '  vertical  line' 
of  Quain,  running  upwards  parallel  to  the  mesial  line  from  the  middle  of  Poupart's 
ligament,  is  already  familiar  to  the  greater  number  of  observers;  but  it  has  the 
disadvantage  of  making  the  mesial  regions  very  large  in  proportion  to  the  lateral 
regions,  the  upper  lateral  regions  being  still  further  reduced  in  women  owing  to  the 
narrowness  of  the  chest  when  compared  with  the  widtli  of  the  pelvis.  As  an  aher- 
native,  the  outer  border  of  the  rectus  would  be  ]>referable.  as  it  is  usually  to  be 
locaUsed  without  difficulty  by  the  lateral  infracostal  furrow  above,  and  by  the 
pubic  spine  below;  and  when  these  points  are  indistinct,  the  breadth  of  the  patient's 
hand  at  the  head  of  the  metacarpal  bones  may  be  taken  as  equal  to  the  lireadth  of 
the  rectus  in  its  upper  two-thirds.  This  jdane.  while  reducing  the  width  of  the 
middle  zone  without  interfering  materially  with  existing  indications  of  contents, 
leaves  an  inguinal  region  that  includes  the  whole  of  the  inguinal  canal.  Each  plane 
cuts  the  kidney,  transverse  colon,  and  small  intestine,  and  the  ovaries  lie  at  or  near 
its  intersection  with  the  lower  horizontal  (interspinous)  plane;  the  right  plane  cuts 
also  the  gall  bladder,  iind  sometimes  the  ctecum;  the  left  cuts  the  sigmoifl  flexure, 
the  stomach  (great  cul-de-sac),  the  pancreas,  and  the  spleen.  The  subjoined  table 
will  show  the  contents  of  the  regions  adjusted  according  to  this  scheme.     If  the 


1208 


SURGICAL  AND  TOPOGRAPHICAL  ANATOMY 


vertical  plane  from  the  middle  of  Poupart's  ligament  be  preferred  to  that  here 
adopted,  the  name  of  ^ iliac'  region  must  rej^lace  that  of  ^inguinal,'  and  the  two 
inguinal  canals  would  be  transferred  to  the  hypogastric  region.  The  choice  of  the 
intertuberculous  plane  in  place  of  the  interspinous  plane  affects  the  table  chiefly  in 
bringing  the  lower  part  of  the  ascending  colon  into  the  right  '  iliac '  region. 

The  subjoined  diagram  shows  the  two  principal  schemes,  and  the  table  offers  a 
summary  of  the  visceral  contents: 


I 

1 


77ie  Abdominal  Viscera  regionally  arranged. 


Right 


Hypochondriac  \ 

Liver :  portion  of  right  lobe  I 

(gall   bladder    usually  cut  ■§ 

bj'  longitudinal  line).  ^ 

Kidney :    upper    and    outer  ? 

part.  "I 

Colon  :  hepatic  flexure   and  -f 

part  of  ascending  colon.  -S 


Middle 

Epigastric 

Liver :     quadrate,    caudate, 

Spigelian,  and  greater  part 

of  left  lobes  (gall  bladder 

usually  cut  by  longitudinal 

line). 
Pancreas  :  head  and  body. 
Spleen :    upper     and    inner 

part. 
Kidneys :    upper    and    inner 

part  of  each,  with  pelves. 
Suprarenal  bodies. 
Stomach :  middle  and  pyloric 

regions,  cardiac  and  pyloric 

orifices. 
Duodenum:  first  and  second 

portions  and  termination  of 

third  portion. 
Small   intestine :   transverse 

colon,  variable  portion. 


Left 


Hypochondriac 

Liver  :  portion  of  left  lobe. 
Spleen:    lower    and    outer 


part. 
Pancreas . 
Kidney : 

part. 
Stornach . 


tail, 
upper 


and    outer 


great  cul-de-sac- 


Colon :  splenic  flexure. 


•Upper  horizontal  plane  at  level  of  lowest  point  of  costal  border- 


I/umbar 

Kidney :    lower    and    outer 

part. 
Ascending  colon. 
Ccecum :  portion  or  whole. 
Small     intestine :        chiefly 

ileum. 


Umbilical 

Kidneys :  lower  and  inner  por- 
tion of  each,  with  ureters. 

Duodenum:  lower  flexure 
and  part  of  third  portion. 

Jejunum  and  ileum. 

Transverse  colon :  portion. 

Sigmoid  flexure  and  com- 
mencement of  rectum. 


Lumbar 

Kidney :  lower  and  outer 
part. 

Small  intestine:  chiefly  jeju- 
num. 

Descending  colon  and  portion 
of  sigmoid  flexure. 


'Lower  horizontal  plane  at  level  of  anterior  superior  iliac  spines  carried  into  true  pelvis- 


Inguinal 

Small  intestine. 
Ccecum :  lower  portion,  occa- 
sionally. 
Inguinal  canal. 


Hypogastric 

Small  intestine. 

Sigmoid  flexure  and  rectum 
(portion). 

Ccecum :  lower  portion,  occa- 
sionally. 

Ureters. 

Bladder :  in  children,  and 
distended  bladder  in  adults. 

Fundus  uteri  and  append- 
ages. 


Inguinal 

Small  intestine. 
Sigmoid  flexure :  portion. 
Inguinal  canal. 


SECTION'   XI 

VESTIGIAL   AXD    ABNORMAL 
STRUCTURES 

By  ARTHUR  ROBIXSOX.  M.D.M.R.C.S. 

LECTURER   ON  ANATOMY  IX   TUE   MIDDLESEX    HOSPITAL    MEDICAL  SCHOOL;    EXAMINER    IN   ANATOMY    FOR  THE   CON- 
JOINT  BOARD  OF   ENGLAND 


The  vestigial  structures  met  -with  in  the  human  body  may  be  classified  in 
two  groups: — 

(1)  Renniants  of  organs  which  phiyed  an  important  part  during  fietal  life. 

(2)  Structures  which  appear  regularly  in  the  human  body,  but  which  possess  little 
or  no  function,  Ijeing  merely  vestiges  of  organs  which  are  much  better  devel- 
oped in  some  of  mankind's  ancestors. 

The  abnormal  structures  which  occasionally  appear  in  the  human  subject  are 
produced  by  retardation  or  excess  of  ordinary  develojunental  i)rocesses,  1)V  the  non- 
union of  parts  Avhicli  usually  fuse  together,  by  the  fusion  of  parts  which  usually 
remain  separate,  or  the  formation  of  organs  not  usually  develoi)ed  in  man.  ])Ut 
which  are,  however,  frecjuently  met  Avith  in  some  of  his  more  or  less  remote  ances- 
tors; organs  of  the  latter  class  are  of  atavistic  nature,  tliat  is,  they  are  due  to  a 
'reappearance  of  a  more  primitive  organisation,  or  a  reversion  to  a  i)rimary  state.' 


THE  SKELETON 


THE  SKULL 

The  epipteric  bone. — This  term  wa.«  applie<l  by  Professor  Flower  to  a  small 
bone  occasionally  found  at  the  bottom  of  the  temporal  fossa,  separating  the  great 
wing  of  the  s])h('noid  from  the  anterior  inferior  angle  of  the  parietal  Ixme.  It  is  of 
the  nature  of  a  \\'ormian  l)one,  and  is  due  to  the  apjiearance  of  a  centre  of  ossifica- 
tion in  the  region  usually  occupied  by  a  portion  of  the  jiarietal  l)one  or  the  great 
wing  of  the  sjthcnoid. 

The  interparietal  bone,  or  os  Incae,  and  the  praeinterparietal  bone.— The 
posterior  section  of  the  occipital  bone,  the  stjuama  occii»italis,  is  usually  deveiope<l 
from  at  least  three  pairs  of  centres,  which  are  superposed.  As  a  rule,  each  pair  of 
centres  soon  fuses  into  a  sinsle  nucleus  of  ossification,  and  the  three  segments  of 
bone  formed  from  the  three  pairs  of  centres  fuse  together  to  complete  the  squama 
occipitalis. 

Occasionallv,  liowever,  the  two  upper  segments  may  unite,  but  remain  separate 
from  the  lower  segment,  and  then,  in  the  adult,  a  V)one  is  found  lying  between  the 

1209 


1210  VESTIGIAL  AND  ABNORMAL  STRUCTURES 

parietal  bones  and  aV)ove  the  occipital.  This  bone  is  known  as  the  interparietal 
bone,  or,  because  it  appears  more  frequently  in  ancient  Peruvian  skulls  (tive  to  six 
j)er  cent.)  than  in  European  skulls  (one  to  two  per  cent.),  it  is  also  called  the  os 
Inc^. 

The  interparietal  bone  may  consist  of  lateral  halves,  a  condition  produced  by 
the  centres  on  each  side  failing  to  unite  across  the  middle  line. 

In  a  relatively  small  niunber  of  cases  the  upper  segment  alone  may  remain 
separate  in  adult  life  as  a  pne-interparietal  bone,  which  corresponds  in  position  with 
the  apex  of  the  occipital  bone;  this  also  may  consist  of  two  lateral  segments.  In  a 
still  smaller  numlier  of  cases  both  interparietal  and  i)ra?-interparietal  bones  may  be 
present  in  the  same  skull. 

The  interparietal  bone  appears  first  among  mammals,  and  is  best  developed  in 
some  of  the  lower  forms.  The  prae-interparietal  bones  are  only  constantly. present 
in  the  horse. 

Fontanelle  bones. — Accessory  centres  of  ossification  occasionally  appear  in 
the  membranous  wall  of  the  skull  in  the  regions  of  the  anterior  and  posterior 
fontanelles,  where  they  give  rise  to  small  segments  of  bone,  which  remain  separate 
throughout  life.  The  anterior  fontanelle  bone  lies  in  the  region  of  the  bregma, 
l)etween  the  parietals  and  the  frontal,  and  the  posterior  fontanelle  lione  is  situated 
at  the  lambda,  between  the  parietals  and  the  occipital.  Both  are  of  the  nature  of 
Wormian  ])ones,  and  the  posterior  fontanelle  bone  must  not  be  confounded  with  the 
pne-interparietal  l:)one. 

Os  Japonicum. — This  term  has  been  apiDlied  to  a  malar  bone,  which  consists 
of  two  separate  fragments,  under  the  idea  that  a  bifid  condition  of  that  bone  is  more 
common  in  the  Japanese  than  in  other  races;  but  a  double  malar  bone  is  not  unfre- 
quently  met  with  in  other  races,  and  its  significance  is  not  at  present  thoroughly 
understood. 

THE  STERNUM 

Cleft  sternum. — Occasionally  the  sternum,  instead  of  being  a  single  median 
bone,  consists  of  two  lateral  parts,  each  part  being  connected  Avith  the  cartilages  of 
the  true  ribs  of  its  own  side.  This  condition  is  due  to  the  persistence  of  one  of  the 
embryological  phases  through  which  the  sternum  normally  passes,  for  in  the  early 
periods  of  development  each  half  of  the  sternum  is  formed  by  the  fusion  of  the 
cartilaginous  extremities  of  the  upper  nine  ribs,  and  thereafter  the  two  cartilaginous 
bars  thus  produced  fuse  together  to  form  the  single  median  sternum  with  which  the 
eighth  and  ninth  ribs  subsequently  lose  their  connection.  If  the  fusion  of  the  two 
halves  of  the  cartilaginous  sternum  does  not  occur,  ossification  proceeds  in  each  half, 
and  the  condition  of  cleft  sternum  is  j^roduced. 

Perforated  sternum. — Xot  unfrequently  an  aperture,  of  larger  or  smaller  size, 
is  found  in  the  lower  part  of  the  body  of  the  sternum.  It  is  filled,  in  the  recent 
condition,  by  fibrous  tissue  or  by  cartilage,  and  it  is  due  to  the  non-union  of  the 
lateral  centres  of  ossification  from  which  the  loAver  part  of  the  sternum  is  ossified. 

Ossa  suprasternalia. — The  two  small  bones  or  round  nodules  of  cartilage 
which  are  known  as  the  ossa  suprasternalia,  or  Brecht's  cartilages,  are  found,  one 
on  each  side,  above  the  sternum  and  immediately  internal  to  the  sterno-clavicular 
joint.  They  are  to  be  looked  upon  as  rudiments  of  the  episternal  bone,  which  is 
met  with  in  so  well-develoi»cd  a  form  in  the  ornithorhynchus. 


THE  RIBS 

Additional  ribs. — There  are  usually  twelve  pairs  of  ribs  in  the  human  subject, 
but  there  is  embryological  evidence  to  show  that  man  has  inherited  a  larger 
number  from  liis  ])redecessors.  Therefore  the  occurrence  of  additional  ribs  is  an 
atavistic  phenomenon.  In  the  embryo  rudiments  of  additional  ribs  are  found  both 
at  the  upper  and  lower  ends  of  the  ordinary  series, — at  the  up]ier  end  in  connection 
with  the  last  two  cervical  vertel^nc,  and  at  the  lower  end  in  connection  with  all  the 
hniibar  and  sacral  vertebra\     In  the    adult,   however,    additional    rilis   are  only 


THE  SKELETON  AND   NERVOUS  SYSTEM  1211 

met  with  in  connection  with  the  last  cervical  an<l  the  first  lunil)ar  vertebra'.  The 
cervical  rib  has  been  found  extending  from  tlie  seventli  cervical  vertebra  to  the 
sternum.  As  a  general  rule,  however,  it  terminates  anteriorly  by  joining  the  first 
ril),  or  only  its  anterior  and  i)osterior  ends  are  formed,  the  two  parts  lu-ing  coimected 
l)y  a  i)and  of  fibrous  tissue.  Tlie  lumbar  ril»,  when  it  appears,  always  terminates 
by  a  free  end  in  the  body  wall. 


UPPER  LIMB 

Humerus 

The  supracondylar  process  and  foramen. — ^\']len  it  is  present,  the  supra- 
condylar j)rocess  springs  from  the  inner  surface  of  the' humerus,  a  few  centimetres 
al)ove  the  internal  condyle;  it  turns  downwards,  and  is  united  to  the  humerus  at  a 
lower  level  ))y  a  l)and  of  fibrous  tissue, which  is  sometimes  rt'placed  by  lione.  In  the 
latter  case,  a  distinct  supracondylar  foramen  is  formed,  through  which  the  meflian 
nerve  passes.  This  foramen  is  very  common  in  the  lower  mannnals,  in  am})hibians, 
reptiles,  and  in  their  fossil  ancestors. 

The  supratrochlear  foramen. — This  foramen  is  formed  when  the  septum 
between  the  coronoid  and  olecranon  fossae  is  not  developed.  It  is  frequent  in  the 
lower  races  of  mankind,  especially  in  the  8outh  African  natives  and  in  the 
Veddahs.  It  also  occurs  in  skeletons  belonging  to  the  Stone  Age,  in  the  gorilla,  the 
orang,  and  the  lower  apes. 

The  OS  centrale. — The  os  centrale  is  occasionally  found  as  a  separate  bone  in 
the  carpus,  lying  in  an  interval  between  the  scaphoid,  the  os  magnum,  and  the 
trapezoid  and  trapezium.  Its  cartilaginous  rudiment  is  always  present  at  the  second 
month  of  fcetal  life,  but  in  the  second  half  of  the  third  month  it  usually  fuses  with 
the  scaphoid,  and  it  is  only  when  the  cartilage  remains  distinct  and  undergoes 
separate  ossification  that  an  os  centrale  is  present  in  the  adult. 

The  OS  centrale  is  a  normal  component  of  the  carpus  of  the  orang;  it  is  present 
in  most  monkeys,  and  it  is  a  regular  carpal  element  in  many  of  the  lower  verte- 
brates. 

THE   LOWEPv   LIMB 

The  third  trochanter. — In  about  thirty  per  cent,  of  European  skeletons  the 
U])j)er  part  of  the  gluteal  ridge  is  developed  into  a  prominent  third  trochanter. 
This  prominence  is  more  rare  in  negroes  and  anthropoid  apes,  but  it  is  very  fre- 
quently present  in  lemurs.  It  is  well  developed  in  many  of  the  lower  mammals, 
and  it  forms  a  prominent  projection  on  the  femur  of  the  hare. 


THE   MUSCULAR  SYSTEM 
{A  List  of  Abnormal  Muscles  tcill  be  found  on  page  IfbS. ) 


THE  NERVOUS  SYSTE.U 


The  filum  terminale. — Extending  from  the  end  (tf  the  conus  medullaris  of 
the  spinal  cord  to  the  liack  of  the  coccyx  there  is  a  thin,  cord-like  structure,  the 
filum  terminale;  it  forms  part  of  the  cauda  equina,  and  is  the  lower,  non-functional 
portion  of  the  spinal  cord.  It  does  not  exist  before  the  third  month  of  fivtal  life, 
for  up  to  that  period  the  spinal  cord  is  coextensive  with  the  spinal  canal.     After 


1212  VESTIGIAL  AXD  ABNORMAL  STRUCTURES 

the  tliird  montli,  however,  the  lower  part  of  the  spinal  cord  ceases  to  develoj)  in 
the  same  matter  as  the  upper  part;  at  birth  the  functional  part  of  the  spinal  cord 
terminates  at  the  third  lumbar  vertebra,  and  in  the  adult  it  ends  at  the  level  of  the 
second  lumbar  vertebra,  the  terminal  or  caudal  portion  of  the  cord,  which  is  better 
developed  in  many  vertebrates,  being  represented  in  man  b}'-  the  tilum  terminale. 
This  retrogression  of  the  lower  part  of  the  cord  is  not,  however,  contined  to  man, 
for  it  is  present  also  in  other  mammals,  and  it  is  particularly  well  marked  in  the 
hedgehog,  the  filum  terminale  commencing  in  this  animal  in  the  anterior  part  of 
the  thoracic  region. 

In  the  human  adult  the  filum  terminale  is  about  23  cm.  (9  inches)  lopg,  and 
it  is  divisible  into  two  parts — an  upper,  about  14  to  15  cm.  (6  inches)  long,  which 
lies  in  the  subdural  space,  and  a  lower  part,  about  7  cm.  (3  inches)  long,  which  is 
closely  invested  by  a  covering  of  dura  mater.  The  first  part  consists,  at  its  com- 
mencement, of  an  outer  layer  of  nerve-fibres,  the  fibres  of  the  coccygeal  and  acces- 
sory coccygeal  nerves  (thirty-first,  thirty-second,  and  thirty-third  pairs  of  nerves), 
a  small  amount  of  grey  matter,  some  substantia  gelatinosa  centralis,  and  the  lower 
part  of  the  central  canal.  The  central  canal  terminates  about  4  cm.  beneath  the 
conus  medullaris,  the  grey  matter  al^out  8  cm.  beloAV  the  same  point,  and  the 
remainder  of  the  first  part  of  the  filum  consists,  therefore,  merely  of  a  few  nerve- 
fibres  and  connective  tissue.  The  nerve-fibres  of  the  thirty-second  and  thirty-third 
pairs  of  nerves  are  quite  functionless,  and  they  disappear  after  a  very  short  course 
in  the  second  part  of  the  filum,  the  lower  portion  of  which  consists  entirely  of 
strands  of  connective  tissue  more  or  less  separated  from  each  other,  and  attached 
at  intervals  to  the  back  of  the  coccyx. 

The  pineal  body. — This  structure,  which  appears  at  an  early  period  in  the 
development  of  the  foetus,  is  a  diverticulum  from  the  roof  of  the  primitive  fore- 
brain,  or  thalamencephalon;  it  grows  backwards,  and  in  the  adult  lies  between 
the  splenium  of  the  corpus  callosum  and  the  anterior  quadrigeminate  bodies, 
embedded  in  a  fold  of  pia  mater.  It  never  attains  a  high  grade  of  development  in 
man,  nor,  in  him,  does  it  appear  to  possess  any  special  functions,  but  in  some  of  the 
lower  vertebrates  it  appears  to  serve  the  purpose  of  an  unpaired  median  eye,  and, 
reaching  the  surface  of  the  body,  it  is  en^edded  in  the  parietal  foramen  in  the 
skull  wall.  In  the  higher  vertebrates,  however,  including  man,  it  is  displaced  from 
a  supertieial  position  liy  the  great  development  of  the  cerebral  hemispheres. 

The  pituitary  body. — The  pituitary  body  is  connected  in  the  adult  with  the 
floor  of  the  third  ventricle,  and  it  is  embedded  in  the  pituitary  fossa  of  the 
sphenoid  bone.  It  consists  of  two  lobes — an  anterior,  of  somewhat  glandular 
nature,  and  a  posterior,  in  which  remains  of  nervous  structures  can  sometimes  be 
recognised.  The  posterior  lobe  is  formed  by  an  outgrowth  from  the  floor  of  the 
thalamencephalon,  and  in  man  and  other  mammals  the  anterior  lobe  is  a  diver- 
ticulum from  the  roof  of  the  stomatoda^um,  or  primitive  mouth,  but  in  the  lower 
vertebrates  the  anterior  lobe  is  formed  by  a  diverticulum  from  the  olfactory 
depression,  and  consequently  its  origin  in  man  is  a  secondary  one. 

The  history  of  the  pituitary  body  has  not  yet  been  fully  elucidated,  but  it  is 
])elieved  that  it  represents  the  remains  of  the  ancestral  mouth,  and  that  the  mouth 
which  is  now  formed  has  been  developed  by  the  fusion  of  a  pair  of  gill  clefts. 


THE  EYE 

The  canal  of  Cloquet  or  Stilling. — Almost  in  the  axis  of  the  eyeball  there  is 
a  fine  canal  passing  througli  tlie  vitreous  body  from  the  ojjtic  papilla  to  the  back  of 
the  capsule  of  the  lens;  this  is  the  canalis  hyaloideus,  or  the  canal  of  Cloquet  or 
Stilling.  It  is  lined  by  a  fine  homogeneous  membrane,  and  in  the  adult  it  may 
possibly  serve  as  a  lymph  passage,  but  in  the  foetus  it  transmitted  the  capsular 
branch  of  the  central  artery  of  the  retina  from  the  optic  papilla  to  the  back  of  the 
lens  capsule,  which  at  that  time  was  a  very  vascular  structure. 


VASCULAR  SYSTEM  1213 

The  plica  semilunaris.— At  the  inner  cantluis  of  the  palpebral  fissure  there  is 
a  small  fold  of  conjunctival  membrane,  the  plica  semilunaris.  In  many  ne«rroes  it 
contains  a  small  plate  of  cartilage,  and  it  rei)resents  the  third  evelid,  or  nfctating 
membrane,  of  Ijirds,  many  reptiles,  and  some  amphibians.  The  function  of  the 
third  eyelid  is  to  cover  and  cleanse  the  front  of  the  eveball,  but  this  function  is 
performed  in  man  by  the  upjjer  eyelid,  and  consequently  the  nictating  membrane 
remains  as  a  rudimentary  fold. 


VASCULAR  SYSTEM 


The  foramen  ovale. — This  aperture  is  found  in  the  interauricular  septum, 
at  the  \\\)\)v\-  i.art  of  the  fo.ssa  ovalis.  It  is  a  remnant  of  a  much  larger  aperture, 
Avhich  existed  before  birth  for  the  passage  of  l)lood  from  the  inferior  vena  cava 
directly  into  the  left  auricle.  At  birth,  when  the  lungs  become  functional,  the 
inferior  vena  cava  blood  is  diverted  into  the  right  ventric-le,  and  in  the  majority  of 
cases  the  foramen  ovale  soon  closes,  but  in  one  case  in  five  the  upjier  part  remains 
open  in  adult  life. 

The  sulcus  terminalis  and  crista  terminalis. — Upon  the  anterior  surface  of 
the  riglit  auricle  there  is  a  shallow  sulcus,  the  svdcus  terminalis,  which  extends 
from  the  front  of  the  lower  end  of  the  sui)erior  vena  cava  to  the  right  of  the  termi- 
nation of  the  inferior  vena  cava,  and  upon  the  inner  surface  of  the  auricular  wall, 
in  a  similar  position,  there  is  a  ridge,  the  crista  terminalis,  in  which  the  upper 
ends  of  the  musculi  i:»ectinati  terminate.  Both  these  structures  indicate  the  line  of 
union  of  the  posterior  portion  of  the  primitive  heart,  the  saccus  reuniens  or  sinus 
venosus,  with  the  second  portion  or  auricle. 

The  ligamentum  arteriosum. — This  term  is  applied  to  a  fibrous  cord  which 
connects  the  root  of  the  left  pulmonary  artery  to  the  under  surface  of  the 
arcli  of  the  aorta,  intervening  between  the  superficial  cardiac  plexus  on  the  inner 
side  and  the  left  recurrent  laryngeal  nerve  on  the  outer  side.  It  is  the  remnant  of 
the  dorsal  part  of  the  left  fifth  aortic  arch,  one  of  a  series  of  vessels  arranged  in 
pairs  between  the  ventral  and  dors^al  parts  of  the  aorta  of  the  foetus.  AMien  the 
foetal  blood-channels  are  transformed  into  the  permanent  vessels  of  the  adult,  the 
ventral  parts  of  the  fifth  arches  become  the  roots  of  the  pulmonary  arteries,  the 
dorsal  part  on  the  left  side  soon  disappears,  but  the  dorsal  part  on  the  right  side 
persists  till  birth,  and  through  it  blood  passes  from  the  right  ventricle  into  the 
aorta.  After  birth,  Avhen  the  blood  of  the  right  ventricle  is  diverted  into  the 
lungs,  the  dorsal  part  of  the  left  fifth  arch  loses  its  lumen  and  is  converted  into  a 
fibrous  cord. 

The  obliterated  hypogastric  arteries. — The  filirous  cords  which  are  known 
as  the  obliterated  hypogastric  arteries  are  easily  seen  when  the  aVtdomen  is  opened 
and  the  intestines  are  lifted  out  of  the  pelvis.  Each  cord  extends  from  the  anterior 
part  of  the  upper  extremity  of  the  internal  iliac  artery,  under  cover  of  the  perito- 
neum, and  beneath  the  ureter  and  the  vas  deferens,  or  the  round  ligament  of  the 
uterus,  according  to  the  sex,  to  the  posterior  surface  of  the  anterior  wall  of  the 
abdomen,  where  it  ascends  with  an  inward  inclination  across  Hessell)ach"s  triangle 
and  behind  the  lower  part  of  the  rectus  abdominis  muscle,  to  join  the  urachus  a 
short  distance  above  tlie  apex  of  the  l)ladder;  both  the  cords  then  ascend  witli  the 
urachus  to  the  umbilicus,  where  they  terminate  in  the  cicatrix.  They  are  the 
remnants  of  the  ventral  portions  of  two  large  arteries,  the  umbilical  arteries,  which 
conveyed  blood  to  the  placenta  and  which  formed  during  the  greater  i>art  oi  inter- 
uterine  life  the  main  continuations  of  the  aorta.  Tlie  dorsal  j^ortions  of  the 
umbilical  arteries  become  the  common  and  internal  iliac  arteries,  and  after  birth, 
when  the  placental  circulation  ceases,  the  ventral  parts  are  converted  into  fibrous 
cords. 

The  round  ligament  of  the  liver.— This  ligament  is  a  round,  fibrous  cord, 
which  extends  from  the  umbilical  cicatrix  along  the  lower  or  free  border  of  the 


1214  VESTIGIAL  AND  ABNORMAL  STRUCTURES 

falciform  ligament  to  the  anterior  end  of  the  longitudinal  fissure,  and  thence  along 
tlie  anterior  part  of  the  longitudinal  fissure  to  the  left  extremity  of  the  transverse 
fissure,  where  it  terminates  l^y  fusing  with  the  anterior  Avail  of  the  left  branch  of 
the  })ortal  vein.  It  is  the  remains  of  the  left  division  of  the  umbilical  vein,  a 
large  vessel  which  returns  the  blood  from  the  })lacenta  anil  which  divides  at  its 
entrance  into  the  body  into  right  and  left  branches;  the  right  branch  disap})ears  at 
an  early  period  of  development,  but  the  left  persists  until  the  })lacental  circulation 
terminates  at  birth,  when  it  is  converted  into  a  solid  fibrous  cord. 

The  ligamentum  venosum. — The  ligamentum  venosum  is  a  fil^rous  cord 
situated  in  the  posterior  part  of  the  longitudinal  fissure  of  the  liver.  It  sjirings 
from  the  posterior  wall  of  the  left  branch  of  the  portal  vein,  somewhat  to  the 
right  of  the  termination  of  the  round  ligament  anteriorly,  and  it  terminates 
above  in  the  inferior  vena  cava.  It  is  the  remains  of  a  channel,  the  ductus 
venosus,  which  persists  until  birth  for  the  transmission  of  the  greater  part  of  the 
placental  l)lood  dii-eetly  from  the  left  umbilical  vein  to  the  inferior  vena  cava. 

The  vestigial  fold  of  the  pericardium. — The  vestigial  fold  of  the  i)eri- 
cardium,  wdiich  was  first  described  by  Marshall,  extends  from  the  left  branch  of 
the  pulmonary  artery  to  the  left  superior  pulmonary  vein.  It  contains  a  fibrous 
cord  which  represents  the  lower  part  of  the  left  superior  vena  cava,  a  vessel  which 
is  very  common  in  mammals  generally,  but  which  is  generally  absent  in  man. 


GENITO-  URINAR  Y  SYSTEM 


FEMALE 

The  round  ligament  of  the  uterus  and  the  ligament  of  the  ovary. — When 

the  ovary  is  developed,  in  the  lumbar  region  of  the  abdomen,  it  is  connected  with 
the  labium  majus  and  the  lower  j^art  of  the  anterior  abdominal  wall  by  a  musculo- 
fibrous  cord,  tlie  gubernacular  cord  of  the  ovary,  which  corresponds  with  the 
gubernacular  cord  of  the  testicle  in  the  male.  The  male  gubernacular  cord  com- 
pletely disappears  when  the  testicle  is  pulled  down  into  the  scrotum,  but  the 
gubernacular  cord  in  the  female  contracts  to  a  smaller  extent,  and  the  ovary  is  only 
pulled  down  to  the  back  of  the  broad  ligament.  As  soon  as  the  contraction  has 
proceeded  to  this  extent,  the  gubernacular  cord  becomes  attached  to  the  side  of  the 
uterus  below  the  Fallopian  tube,  the  portion  of  the  cord  in  front  of  the  attachment 
becoming  the  round  ligament  of  the  uterus,  whilst  that  behind  is  converted  into  the 
ligament  of  the  ovary. 

The  hydatid  of  Morgagni. — The  hydatid  of  Morgagni  is  a  small  pyriform 
vesicle  attached  to  the  upper  herder  of  the  broad  ligament  of  the  uterus,  or  to  one 
of  the  fimbriae  of  the  Fallopian  tube,  by  a  slender  pedicle.  It  is  usually  filled  with 
clear  fluid,  and  it  is  the  modified  remnant  of  one  of  the  Wolffian  tubules  of  the 
primitive  kidney. 

The  epoophoron,  epovarium,  or  organ  of  Rosenmiiller. — This  rudiment  of 
the  primitive  kidney,  or  Wolffian  Ijody,  lies  in  the  broad  ligament  of  the  uterus, 
between  the  ovary  below  and  the  Fallopian  tube  alcove.  It  consists  of  a  series  of 
from  twelve  to  twenty  vertical  tubules,  which  commence  below  in  or  near  tlie  hilum 
of  the  ovary,  and  terminate  above  in  a  horizontal  tubule  which  lies  i)aralh'l  with, 
and  a  short  distance  below,  the  Fallopian  tube.  The  vertical  tubules  are  remains 
of  the  upper  Wolffian  tubules,  and  they  correspond  with  the  vasa  recta  and  the 
vasa  eft'ercntia  of  the  testicle.  The  horizontal  tube  is  a  remnant  of  the  upper  part 
of  the  Wolffian  duct,  and  it  therefore  corresponds  with  tlie  tube  of  the  epididymis 
in  the  male. 

The  paroophoron,  or  parovarium. — Tlie  ])ar()<)|>hor()n  lies  in  the  l)road 
ligament  of  the  uterus  to  tlie  inner  side  of  the  e])oophoron  and  the  ovary.  It 
consists  of  a  munl)er  of  yellow  cords,  the  renniants  of  some  of  the  lower  Wolffian 


a 

I 


GEXITO-URINARY  SYSTEM  1215 

tubultvs,  iiiid  it  is  liomolofioiis  with  the  oriraii  of  (iiraldes  in  the  male  It  ('aniiot 
always  he  recojiiiiscd,  and  as  a  rule  it  is  only  prcst-nt  durinir  ciiildhood,  (lisaj»i (far- 
ing bet'orc  adult  life  is  attained. 

The  duct  of  Gartner. — The  duet  of  (Jiirtner  is  a  small  tube,  blind  at  both 
extremities,  which  is  occasionally  found  at  the  side  of  the  neck  of  the  uterus 
and  the  up))er  i)art  of  the  vagina.  It  represents  a  section  of  the  lower  part  of 
the  A\'olthan  duct,  and  corresponds  with  a  i)ortion  of  the  vas  deferens  of  the 
male. 

MALE 

The  hydatids  of  Morgagni. — Two  hydatids  of  Morgagni  are  met  with  in  the 
male — the  petlunculated  and  the  sessile.  The  former  is  very  inconstant;  when 
l)resent  it  is  an  oval  or  i)yriform  vesicle,  filled  with  clear  fluid,  which  is  attached 
by  a  slender  pedicle  to  the  globus  major  of  the  epididymis.  It  corresponds  with 
the  hydatid  of  Morgagni  met  with  in  the  female,  and  it  is  the  renniant  of  one  of 
the  iijjper  ^\'olttian  tubules.  The  sessile  hydatid  is  more  frecjuently  ]>resent.  It 
is  also  an  ovoid  vesicle,  which  is  attached  by  its  small  end  to  either  the  U)>])er 
extremity  of  the  testicle  or  to  the  groove  l)etween  tlic  testicle  and  the  globus  major. 
It  corresponds  with  the  timjjriated  end  of  the  Fallo])ian  tube  in  the  female,  for  it 
is  a  remnant  of  the  ui)per  end  of  the  JSliillerian  duct  from  which  the  Fallopian 
tube  is  developed. 

The  organ  of  Giraldes,  or  parepididymis. — This  organ  is  a  remnant  of 
some  of  the  lower  Wolttian  tubules,  and  it  corresi)onds  with  the  i)arovarium  of  the 
female.  It  lies  in  front  of  the  lower  part  of  the  spermatic  cord,  aliove  the  epidid- 
ymis, and  either  behind  the  up})er  part  of  the  tunica  vaginalis  or  just  above  it. 
The  tubules  of  which  it  consists  are  small,  yellowish  in  colour,  and  they  are  coiled 
together,  forming  a  small  body,  which  is  from  5  to  14  nun.  in  diameter  (^  of  an 
inch). 

Vasa  aberrantia. — When  the  tube  of  the  ei)ididymis  is  uncoiled;  several  l)lind 
diverticula  arc  found  connected  with  it.  They  constitute  the  vasa  aberrantia,  and 
the  largest  of  them,  which  is  usually  found  in  the  region  of  the  globus  minor,  is 
known  as  the  vas  aberrans  of  Haller.  It  varies  in  length  from  4  to  37  cm.  (1^  to  15 
inches),  and  it  is  coiled  into  the  form  of  a  small  mass  2  to  6  cm.  (f  to  3  inches)  long, 
which  lies  between  the  body  of  the  ei)ididymis  and  the  vas  deferens.  The  exact 
significance  of  the  vasa  aberrantia  is  not  certain,  l)Ut  they  are  jirolxdjly  the  remains 
of  some  of  tlic  \\'olthaii  tubules. 

The  uterus  masculinus,  or  sinus  pocularis. — The  uterus  masculinus  lies  in 
the  floor  of  the  prostatic  jwrtion  of  the  urethra,  where  it  oi>ens,  innnediately  in 
front  of  the  highest  point  of  the  verumontanum,  by  an  oval  ojiening.  It  is  a 
small  cavity,  6  to  12  mm.  Q  to  ^  of  an  inch)  long,  narrow  at  its  opening  into  the 
urethra,  but  it  widens  considerably  towards  its  l)lind  extremity.  It  lies  behind 
the  middle  lobe  of  the  prostate  gland  and  between  the  lateral  lobes  and  the  common 
ejaculatory  ducts.  It  is  a  renmant  of  the  lower  parts  of  the  Miillerian  ducts,  from 
which  the  uterus,  vagina,  and  the  Fallopian  tubes  are  developed  in  the  female,  and 
it  corresponds,  therefore,  with  the  vagina,  and  possil)ly  with  the  uterus  of  the 
female. 

INTECiUMENT 

Hypertrichosis. — The  condition  of  excessive  hairiness  to  which  the  term 
hypertrichosis  is  ai)]>lied  only  occurs  occasionally,  and  it  may  be  due  cither  to  the 
excessive  develojmient  of  the  secondary  hairy  covering  which  <levclops  after  birth. — 
hvpertrichosis  vera, — or  to  the  ])ersistence  and  growth  of  the  w(»olly  covering  or 
lanugo  which  is  formed  over  the  surface  of  the  body  during  intrauterine  life,  ami 
which  is  usually  cast  off  to  make  way  for  the  secondary  hairs.  This  latter  condition 
is  called  ])S(Midohv]iertrichosis  lanuginosa. 

Supernumerary  breasts  and  teats. — The  occurrence  of  additional  teats — 
polvthelv — and  additional  niannna — i)olyma.sty — is  by  no  means  uncommon,  the 
])ercentage  of  cases  of  additional  mannnary  structures  varying  in  diflferent  districts 
from  one-half  to  thirty  per  cent. 


1216 


VESTIGIAL  AXD  ABNORMAL  STRUCTURES 


To  understand  the  position  in  -which  the  majority  of  additional  mammary 
organs  are  found,  it  must  l)e  remembered  that  in  many  mammals  the  mammary 
glands  are  developed  as  thickened  ridges  of  epithelium,  which  extend  from  the 
axilla3  to  the  groin.  .Subsequently  the  ridges  are  broken  up  into  separate  patches, 
each  of  which  is  capable  of  development  into  a  distinct  gland. 

Embryonic  mammary  ridges  have  not  yet  been  found  in  human  eml^ryos,  but 
the  majority  of  additional  mammae  appear  along  lines  extending  from  the  axillae 
to  the  groins, — that  is,  along  the  lines  where  we  should  expect  the  mannnary  ridges 
to  be  formed  during  embryonic  life, — and  additional  mammary  glands  or  nipples 
appearing  along  these  lines  must  be  looked  upon  as  of  atavistic  nature,  inasmuch 
as  they  are  indications  of  a  reversion  to  a  more  primitive  organisation.  By  the 
careful  observation  of  a  large  number  of  cases  it  has  been  shown  that  along  a  line 
running  from  the  axilla  to  the  groin,  on  each  side,  ten  mammary  glands  may  be 
found  in  the  human  suliject,  and  of  these  the  normal  gland  is  the  sixth.  The 
complete  series  does  not  occur  in  any  one  case,  and  more  than  half  the  numl^er  of 
accessory  mammary  organs  which  have  been  observed  appear  below  the  normal 
nipple. 

In  addition,  however,  to  atavistic  mammary  organs  appearing  along  the  lines 
indicated,  mammary  glands  are  occasionally  found  on  the  thigh,  shoulder,  neck, 
and  cheek.  Such  glands  are  most  probably  developed  in  situ  by  the  abnormal  modi- 
fication of  cutaneous  glands,  and  in  connection  with  the  formation  of  such  abnormal 
structures  it  must  not  be  forgotten  that  all  mammary  glands  are  merely  modified 
sebaceous  glands. 


I 


INDEX 


[The  principal  authority  for  the  derivatioriH  of  the  anatomical  terms  f/ivcn  in  this  Judex 
is  HyrtVs  '  Onomatologia  Anatomica,'  Vienna,  1880.] 


ABD 
Abdomex  [from  abdo,  I  hide  ;  or,  more  prob- 
ably from  adrpn,  fat :  as  if  for  adipomen, 
fat  belly  of  swine],  the.  95i) 
contents  seen  on  opening  the,  9G0 
lymphatics  of,  parietal,  660 
visceral,  662 
lynipli  glands  of,  parietal,  661 
vLsceral,  662 
regions  of,  1206 
surgical  anatomy  of,  1114 
veins  of,  630 
Abdominal  aorta,  550  ;  branches,  parietal,  553  ; 
visceral,  555  ;  variations,  552 
muscles,  401-411 
nerves  of  vagus,  773 
parietes,  structure   of,  401  ;   topography  of 

vessels  and  nerves  in,  1115 
portion  of  ureter,  1052 
ring,  external,  405,  1114 

effect  of  position  on,  1132 
internal,  411,  1115,  1134 
viscera.  954  ;  regionally  arranged,  1206 
lymphatics  of.  662 
Abducent  [ab,  from  ;  duco,  I  lead],  or  sixth  cra- 
nial, nerve,  760 
Abduction,  179 

Abductor  hallucis  \_hanux,  great  toe]  muscle,  378  ; 
variations,  379 
minimi  digiti  mu.ecle  of  hand,  343 

of  foot,  379  ;  variations,  381 
osfiis  melatarfii  quint i  muscle,  45H 
poUicis  [poltex,  thunil)]  muscle,  339  ;  varia 
tions,  340 
Abnormal  muscles,  458-460 

and  vestigial  structures,  1209 
Accelerator  urin;c  [from  its  action  in  ha.stening 
the  expulsion  of  the  urine]  or  bulbo-cavcr- 
nosus  muscle,  1024 
Accessorius  [accedere,  to  be  added   to]  ad   ilio- 

costalem  (vel  sacro-lumbalem),  416 
Accessory  artery,  pudic,  570 

band  of  atlanto-axoidean  capsules,  185 
cartilages  of  nose  (quadrate),  891 
lachrymal  glands,  867 
nerve,  ol)tnrator.  805 
spinal,  773 


ALA 

Accessory  nucleus  of  auditory  nerve,  766 
of  trigeminal  nerve,  749 
sensory,  of  trigeminal  nerve,  741) 
palatine  canals.  59 
portion  of  spinal  accessory  nerve,  773 
process  of  lumbar  vertebra,  13 
suprarenal  bodies,  1013 
vein,  hemiazygos.  608 
Acervulus  [dim.  of  acervus,  a  heap]  cerebri,  or 

brain  .sand,  706 
Acetabulum  [a  vessel  for  holding  vinegar],  the 

1.38,  143 
Acromial  artery  of  acromio-thoracic,  521 

of  posterior  circumflex,  .526 
of  suprascapular,  514 
end  of  clavicle,  110 
Acromioclavicular  articulation,  219,  1108 
Acromio-thoracic  artery,  521 

vein,  643 
Acromion    [uKpni',    a   summit ;    'juo^,    shoulder] 

process,  112  ;  ossification  of,  115 
Adduction  {_ad,  to  ;  duco,  I  lead],  179 
Adductor  brevis  muscle,  359  ;  variations  of  the, 
360 
hallucis   [hallux,    great   toe]    muscle,    383 ; 

variations,  3rt4 
longus  muscle,  358  ;  variations,  358 
magnus  mn.scle.  361  ;  variations,  362 
poUicis  [poller,  thumb]  mu.scle.  342  ;  varia 
tions.  343 
obli(juus  mu.scle,  341 
tubercle  of  femur,  150 
Adipose  fos-stc  of  breast,  1070 
Age,  variations  of  brea.'it  according  to,  1071 

variations  in  form  of  uterus  according   to, 
1047 
Ala  [a  wing]  cinerea  [ash-coloured],  719 
Ahe  of  cerebellum,  714 
ofno.se,  889 
of  sacrum,  16 

of  sphenoid,  greater  and  lesser,  31 
of  tliyroid  cartilage,  901 
vespertilionis.  104!^ 
of  vomer,  54 
Alar  [ahi,  a  wing]  ligaments  of  knee,  259 
.spine,  32,  73 


The  names  of  Abnormal  .Vnseles  are  printed  in  itnlies. 

1217 


1218 


INDEX 


ALA 

Alar  [alaris  is  a  contraction  of  axillaris]  thoracic 
artery,  524 
vein,  643 
Alcock's  canal,  813,  1061 
Alimentary  tube,  the  simple,  993 
Ali-spheuoid  bones,  31  ;  at  birth,  93 
Allan tois  [a//df,  gen.  d'/.'/.dvrog,  a  sansage],  the, 

1056 
Alveolar  artery,  495 

nerves,  759 

point  of  skull,  81 

ridge  of  maxilla,  57 
Alveolus  [a   small   hollow  vessel]  of  mandible 
(inferior  maxilla),  63 

of  maxilla  (superior  maxilla),  57 
Amphiarthrosis  [("'P',  both  ;  apHpov,  a  joint],  177 
Ampulla  [a  wine-jug]  of  Fallopian  tube,  105'2 

of  galactophorousduct,  1070 

of  semicircular  canals,  41,  917 

of  Yater,  984 
Amputation  of  great  toe,  incisions  for,  1198 

Hey's,  incisions  for,  1198 

of  leg.  arteries  divided  in,  1192 

Lisfranc's,  incisions  for,  1198 

S3'me's,  incisions  for,  1196 
Amygdala  [a/zi'}  fid/.?/,  an  almond]  of  cerebellum, 

715 
Amygdaloid  nucleus  of  cerebrum,  700 

tubercle  of  cerebrum,  700 
Anal  tascia,  1063 

Anastomotic  \_dvaar6uuai(:,  an  outlet]    artery  of 
deep  cervical,  519 

of  external  plantar,  593 

of  internal  plantar,  596 

of  middle  meningeal,  494 

of  sciatic,  573 
Anastomotica   magna   of  brachial   artery,   530  ; 
variations,  530 

of  superficial  femoral,  585 
Anatomical  neck  of  humerus,  115 
Anatomy    [di'd,    a  part;    rf/n'w,    I   cut],    Topo- 
graphical and  Surgical,  1080 
Anconeus  [d}  /cwi',  the  elbow]  muscle,  327  ;  nerve 

to,  795 
Andersch,  ganglion  of,  768 
Angle,  craniofacial,  81 

nasal,  of  maxilla.  57 

of  neck  of  femur,  152 

of  penis,  1037 

of  pubes,  143 

of  rib,  98 

anterior,  98 

sacro-vertebral,  199 

of  scapula,  113 

subcostal,  109 
Angular  artery,  485,  488 

centre  of  ossification,  of  mandible,  65 

gyrus,  685 

movement,  179 

processes  of  frontal,  47 

vein,  612 
Ankle-joint,  arrangement   of    tendons    around, 
1194 

arterial  and  nerve  supply  of,  268 

ligaments  of,  266 

movements  of,  268 

surgical  anatomy  of,  1194 
Annectaut  [connecting]  gyri,  687 
Annular  \_(innulus,  a  ring]  ligaments  of  ankle, 
1196  ;  anterior,  368  ;  external  and  inter- 
nal, 369 

of  wrist,   anterior,  311  ;   surgical   anatomy 
of,  1168 


Annular  ligament  of  wrist,  posterior,  311  ;  sur- 
gical auatomy  of,  1169 
Annulus  [a  ring]  ovalis,  931 
Anomalus  muscle,  458 
Ansa  [a  loop]  hypoglossi,  775,  785 
leuticularis,  738 
peduncularis,  738 
Vieussenii,  830 
Anti-clinal  vertebra,  12 
Antihelix    [dvri^  opposite  ;   k^.i^,  a  spiral],  the, 

871 
Antitragicus  muscle,  872 
Antitragus  [dvri^  against ;  rpdyog^  a  goat],  the, 

871 
Antral  arteries  of  posterior  dental,  496< 
Antrum    [a    cavern    or   cavity],    mastoid,    40, 
1083 
maxillary  (of  Highmore),  55,  57 
aperture  of,  57,  80 
Anus,  the,  975 

surgical  auatomy  of,  1127 
Aorta  [from  df/pw,  I  take  up,  or  carry],  466 
abdominal,  550  ;  branches,  parietal,  553 
visceral,  555 
topography  of,  1121 
variations,  552 
arch  of,  467  ;  branches  of,  471 
divisions  of,  ascending,  468 
descending,  470 
transverse,  469  ;  branches, 
472 
topography  of,  1113 
variations  of,  471 

of  branches,  472 
foramen  for,  in  diaphragm,  400 
orifice  of,  933  ;  topograph}'  of,  935,  1113 
thoracic,  descending,  545 

branches,  parietal,  548  ;  visceral,  545 
relations,  545 
Aortic  intercostal  arteries,  548 
isthmus,  470 

lymphatic  glands,  lumbar,  662 
orifice,  933  ;  topography  of,  935,  1113 
plexus  of  sympathetic,  835 
spindle,  470 

valves,  933  ;  topography  of,  934,  1113 
Apertura  scaliB  vestibuli,  879 
Aperture  of  larynx,  superior,  910 
palpebral,  839 

of  thorax,  inferior,  899  ;  superior,  898 
Apex  of  antrum,  57 
of  lieart,  963 
of  lung,  960 
of  orbit,  76 

of  petrosal  portion  of  temporal,  :>5 
of  prostate,  1021 

of  sacrum,  17  i 

Aponeurosis    [dTrd,   from ;   vEvpov,    a   nerve :    sa| 
called  from  a  formerly  existing  confusion  ' 
between    nerves    and    tendons]    of    dia- 
phragm, 400 
epicranial,  427 

of  exterual  oblifiue  muscle,  404 
of  internal  oblique  muscle,  406 
lumbar,  408 

occi  pi  to-frontal  or  epicranial,  427,  1085 
pharyngeal,  949 
transversalis,  409,  411 
vertebral,  408,  413 
Aponeurotic  patch  in  trapezius  muscle,  explana- 
tion of,  290 
Apophysis  [d-6,  from  ;  (pi'u,  I  grow],  152 
Appendices  epiploicaj,  970 


INDEX 


1219 


Appendicular  elements  of  skull,  24 

of  chondral  skull,  H9 
Appendix,  auricular,  92^ 

vermiform,  971 
Aquit'ductus  [a  couduit]  cochlea-,  ;!7,  7.> 
Fallopii,  157 
vest i bull,  'Mi,  879 
Aqueduct  of  Sylvius,  670,  708 

grey  matter  of,  706 
Aqueous  chamber  of  eye,  850 

humour  of  eye,  850 
Arachnoid  [/i/tdvi"/,  a  spider's  web  ;  e'u^or^  I'J^^]} 
cranial,  676 
si>iual,  733 
Arantius,  ventricle  of,  719 
Arbor  vitaj  uteriua,  1047 
Arch  of  aorta,  467.     See  Aorta 

of  atlas,  anterior  and  posterior,  7 
carpal,  anterior,  535  ;  posterior,  541 
crural,  deep,  1139  ;  superficial,  1138 
palmar,    deep,    543;   surgical   anatomy   of, 
1168  ;  variations,  543 
superficial,    536  ;  surgical   anatomy  of, 
1167  ;  variations,  537 
plantar,  593 
pubic,  146 

of  vertebrje,  neural,  6 
Arches  of  foot,  1202 

function  and  maintenance  of,  1203 
Arciform  \_<ircus,  a  bow]  fibres  of  medulla,  deep, 

722 ;  external,  722  ;  siiperficial,  722 
Arcus  [a  bow]  tendineus,  1061 
Areola  [a  small  open  space]  of  breast.  1069 
Arm,    central   point    of,    surgical  anatomy  of, 
1154 
cutaneous  nerves  of,  823 
fasciae  of,  306 
surgical  anatomy  of,  1152 
veins  of,  deep,  643 

superficial,  639 
Arnold,  ganglion  of  (otic),  760 

nerve  of,  772 
Arrangement  of   peritoneum  in   human  body, 

explanation  of,  991 
A.rrectores  pilorum,  1074 
Arteria  aberrans  of  aortic  intercostal,  550 
of  superior  intercostal,  519 
centralis  retime,  500,  851 
comes  nervi  ischiadici,  573 
mediani,  533 
phrenici,  516 
receptaculi,  499 
septi  narium,  488 
thyroidea  ima,  475 
Arterial  side  of  heart,  927 

Artery,  or   Arteries  [npr^p,  a  strap  or  suspen- 
der :    a   term   applied  originally   Ut    the 
trachea,  which  suspends  the  lungs],  the 
462 
accessors'  pudic,  570 
acromial,  of  acromio-thoracic.  521 
of  posterior  circumfiex,  526 
of  suprascapular,  514 
acromio-thoracic  or  thoracic  axis,  521 
alar  thoracic,  524 
alveolar,  496 

anastomotic,  of  external  plantar,  594 
of  internal  plantar,  596 
of  middle  meningeal,  494 
of  sciatic,  573  ' 

anastomotica     magna,    of    brachial,     530  ; 
variations,  530 
of  femoral,  585  I 


Artery,  or  Arteries — 
angular,  485,  488 

anterolateral,  of  middle  cerebral,  503 
antral,  495 
articular  azygos,  590 
articular,  oi'  external  plantar,  594 

of  internal  circumfiex,  584 

of  internal  plantar,  oOfJ 

of  interosseous  recurrent,  543 

of  jtopiiteal,  588 

of  posterior  circumflex,  526 

of  sciatic,  573 

of  superior  profunda,  529 

of  supr;iscai»ular,  515 

of  temiKjial,  491 
ascending  cervical,  514 

of  external  circumflex,  584 

frontal,  504 

palatine.  486 

pharyngeal,  481 

septal,  of  sphenopalatine,  496 

tricipital,  of  sujierior  ))rofunda,  529 
auditory,  internal,  511,  'j20 
auricular,  anterior,  491 

deep,  493 

left,  473 

posterior.  490 

right.  472,  936 

of'occipital,  490 

of  stylo-mastoid,  490 
axillary,  520;  line  of,  1150 

variations,  521 
azygos  articular,  590 

vaginal,  570 
basilar,  511 

l)icipital,  of  anterior  circumflex,  525 
brachial,   526  ;  surgical  anatomy  of,  1153; 

variations,  528 
brachio-cephalic   (innominate),  474  ;  varia- 
tions, 474 
bronchial,  left  and  right,  545.  962 
buccal,  of  facial,  487 

of  internal  maxillary,  495 

of  ijosterior  dental,  496 
to  bulb,  575 
calcanean,  external  and  internal,  592 

of  external  plantar,  593 
calloso-niarginal  of  anterior  cerebral,  503 
ciipsular,  perirenal,  560 

suprarenal,  inferior,  560  ;  middle,  561  ; 
superior,  553 
cardiac,  of  gastric,  556 

carotid,  common,  475  ;  in  thorax  (letll, 
475  ;  in  neck,  476  :  collateral  circu- 
lation, 479  :  variations,  479 

external,  4"^0  ;  variations,  480 

internal,  497 
carpal,  radial,  541 

rete,  anterior,  534.  5.35 
posterior,  534,  541 
ulnar,  535 
caudate,  of  middle  cerebral,  503 
caval,  of  right  jihrenic,  553 
central,  of  retina.  500,  a87 
cerebellar,  inferior,  anterior,  512 
posterior.  511 
superior,  512 
cerebral,  anterior,  503,  513 

ha'morrhage,  artery  of.  503 

middle.  503.  513 

posterior,  512.  513 
cervical,  ascending,  514 

deep,  518 


1220 


INDEX 


I 


Artery,  or  Arteries — 

cervical,  superficial,  516 
transverse,  514 
of  uterine,  570 
choroid,  anterior,  502 

posterior,  512 
ciliary,  501,  888 

circumflex,      of    axillary,    anterior,      525  ; 
variations,  526 
posterior,  526  ;  variations,  526 
iliac,  deep,  578  ;  variations,  578 

superficial,  583 
of  thigh,  external,  584  ;  variations,  584 
internal,  584  ;  variations,  584 
clavicular,  523 
coccygeal,  572 
coeliac,  555  ;  variations,  555 
colic,  left,  562  ;  middle,  559  ;  right,  559 
collateral  digital,  of  fingers,  538 
of  toes,  595 
iutei'costals,  549 
commissural,  of  anterior  cerebral,  503 
communicating,  of  brain,  anterior,  503 
posterior,  502 
of  dorsalis  pedis,  601 
of  occipital,  490 
of  palm,  545 
of  peroneal,  592 
of  posterior  tibial,  592 
coronary,  of  heart,  left,  473,  936 
right,  472,  936 
of  lips,  inferior,  487  ;  superior,  487 
of  stomach,  556 ;  variations,  556 
of  corpus  cavernosum,  576,  1066 
cortical,  of  anterior  cerebral,  503 
of  middle  cerebral,  504 
of  posterior  cerebral,  512 
of  renal,  1011 
costo  cervical,  518 
cremasteric,  of  deep  epigastric,  577 

of  spermatic,  561 
cricothyroid,  483 
to  crus  clitoridis,  576 

penis,  573 
cystic,  557 

deferential,  or  artery  to  the  vas,  570 
dental,  anterior,  496 

inferior  (mandibular),  494 
posterior,  495 
descending,  of  external  circumflex,  584 
palatine,  496 
pharyngeal,  496 
diaphragmatic,  550 
digital,  of  foot,  collateral,  595 
dorsal,  600,  601 
plantar,  594,  601 
superficial,  596 
of  hand,  collateral,  538 
dorsal,  542 
palmar,  5.38 
diploic,  500 

dorsal,  of  aortic  intercostal,  549 
digital,  of  foot,  600,  601 

of  hand,  542 
of  foot,  600 
^ — ~  interosseous,  of  radial,  541 
of  lumbar,  554 
of  penis,  576,  1066 
scapular,  525 
twelfth  (subcostal),  550 
dorsalis  hallucis,  601 
indicis,  543 
lingufe,  484 


Artery,  or  Arteries — 
dorsalis  pedis,  600 

poUicis,  543 
epididymal,  of  spermatic,  561 
epigastric,  deep,  or  inferior,  577  ;  variations, 
578 

superficial,  583 

superior,  518 
epiploic,  of  left  gastro-epiploic,  558 

of  right  gastro-epiploic,  557 
ethmoidal,  anterior  and  posterior,  501,  897 
Eustachian,  of  pterygo-palatine,  496 

of  Vidian,   496 
facial,  485 

transverse,  491  • 

Fallopian,  of  ovarian,  562 
femoral,  common,  579  ;  variations,  581 

deep,  583 

superficial,   579  ;  surgical  anatomy  of, 
1214  ;  variations,  581 
of  frtenum  linguae,  485 
funicular,  1088,  1092 
ganglionic,  of  anterior  cerebral,  503 

of  internal  carotid,  499 

of  middle  cerebral,  503 

of  posterior  cerebral,  512 
Gasserian,  of  internal  carotid.  499 

of  middle  meningeal,  494 
gastric,  or  coronary,  5.'.6  ;  variations,  556 

greater  anterior,  556 

lesser  anterior  and  posterior,  556 

of  left  gastro-epiploic,  558 

of  right  gastro  epiploic,  557 
gastro-duodenal,  557 
gastro-epiploic,  lell,  558 

right,  557 
gingival,  496 

glandular  (submaxillary),  487 
Glaserian,  of  internal  maxillary,  493 
gluteal,  569  ;  surgical  anatomy  of,  1181 

inferior,  of  sciatic,  572 
gustatory  (lingual),  of  inferior  dental,  495 
hsemorrhoidal,  inferior,  or  external,  574 
middle,  570 
superior,  562 
hemispheral,  of  inferior  cerebellar,  511 

of  superior  cerebellar,  512 
hepatic,  556  ;  variations,  557 

of  gastric,  556 

of  phrenic,  553 

of  superior  epigastric,  518 
humeral,  of  acromio  thoracic,  523 

transverse,  514 
hyoid,  of  lingual,  484 

of  superior  thyroid,  482 
hypogastric.  569 
ileo-colic,  559 

iliac,  circumflex,  deep,  .578  ;  variations,  578 
superficial,  583 
common,  564  ;    collateral  circulation, 

565  ;  variations,  565 
external,   .576  ;  collateral   circulation, 

577  ;  variations,  577 
internal,  566  ;  variations,  567 
of  ilio-lumbar,  567 
of  obturator,  571 
ilio-lumbar,  567 
incisive,  495 
infracostal,  lateral,  518 
infra-hyoid,  482 
infra-orbital,  496 
infrascapular,  525 
infraspinous,  of  posterior  scapular,  516 


LXDEX 


1221 


^ 


Arter3%  or  Arteries — 

infraspiiious,  of  suprascapular,  515 
iunoiiiiuate,  474  ;  variations,  475 
intercostal,  anterior,  of  int.  maniniary,  517 
of  muse. -phrenic,  518 
aortic,  54^ 
first,  519 
superior,  518 
interosseous,  of  arm,  common,  533 
anterior,  533 
posterior,  534 
recurrent,  535 
of  foot,  600 
of  hand,  dorsal,  541  — 

palmar,  544   -  '    - 
interventricular,  anterior,  473,  936 
posterior,  473,  937 
intestinal,  560 
labial,  inferior,  487 
lachrymal,  499 

of  middle  meningeal,  494 
of  nasal,  502 
recurrent,  499 
laryngeal,  inferior,  of  inferior  thyroid,  514 
of  superior  thyroid,  483 
superior,  of  superior  thyroid,  482 
lenticulo-striate,  503 
ligamentous,  of  ovarian,  562 
lingual,  483,  1102 

of  mandi))ular  (inferior  dental),  495 
lumbar,  553  ;  variations,  554 

of  ilio-lumbar,  567 
malleolar,  external,  of  anterior  tibial,  598 
internal,  of  anterior  tibial,  59"< 
of  posterior  tibial,  593 
mammary,  external,  523 
glandular,  550 
internal,  516 
mandibular  (inferior  dental).  494 
marginal,  of  coronary,  left,  473,  936 

right,  473,  936 
margino-frontal,  503 
masseteric,  of  facial,  487 

of  internal  maxillary,  495 
of  temporal,  491 
mastoid,  middle,  4S2 
of  occipital,  490 
of  posterior  auricular,  491 
of  stylomastoid,  490 
maxillary,  external  (facial),  485 

internal.  492 
meatal,  of  stylomastoid,  490 
median,  533 
mediastinal,  or  thymic,  517 

posterior,  545 
medullary,  of  peroneal,  592 
of  posterior  ti})ial,  592 
of  renal,  1049 
meningeal,  anterior,  of  internal  carotid,  499 
of  ascending  pharyngeal,  482,  713 
of  ethmoidals,  501,  674 
middle  or  great,  493,  674 
posterior,  of  occipital.  489 

of  vertebral,  511,  674 
•small.  495,  674 
niental,  of  facial,  4^7 

of  mandibular.  495 
mesenteric,  inferior,  562  ;  variations,  563 

superior,  558  ;  variations,  560 
metacarpal,  542 
metatarsal,  600 
musculo-))iirenic,  518 
mylo-hyoidean,  495 


Artery,  or  Arteries — 

ua.sal,  of  infra-orbital,  496 

lateral,  488 

of  ophthalmic,  502 

transverse,  502 

of  spheno-jialatine,  49(> 
of  nasal  fossie,  897 
na.so-palatine,  496,  897 
of  luise,  893 
nutrient,  of  clavicle,  514 

of  femur,  .585 

of  fibula,  592 

of  humerus,    530  ;   greater   tuberosity. 
526 ;  upper  end, 530 

of  ilium,  572 

of  radius,  533 

of  tibia,  592 

of  ulna,  .533,  535 
obturator,  571 
occipital,  488 

of  posterior  auricular.  491 
cesophageal,  of  aorta,  548 

of  gastric,  556 

of  inferior  thyroid,  514 

of  left  phrenic,  5.53 
omental,  of  hepatic,  557 
ophthalmic,  499,  899 
orbital,  of  anterior  cerebral,  503 

of  infra-orbital,  496 

of  middle  meningeal,  494 

of  temporal,  491 
orbito-frontal,  504 
ovaiian,  562.  1053 
palatine,  inferior  or  ascending.  4^6 

posterior  or  descending.  496 

of  ascending  pharyngeal.  482  \    '"^ 

palmar  arch,  deep,  543  ;  variations,  543  '        /^ 

superficial,  536  ;  variations.  537 
palpebral.  502 

of  lachrymal.  500 

of  supra-orbital,  500 
pancreatic,  of  hepatic,  556 

of  splenic,  558 
pancreaticoduodenal,  inferior,  558 
superior.  557 
parietal,  of  middle  cerebral.  504 

ascending,  504 
parieto-temporal.  .504 
l)arotid,  of  posterior  auricular,  490 

of  temporal.  491 
pectoral,  of  acroinio-thoracic,  523 

of  anterior  circumflex.  525 
perforating,  of  foot,  594 

of  hand.  545 

of  internal  mammary.  517 

of  middle  meningeal,  494 

of  i)rofunda  femoris.  584 

of  s])heno-palatine,  497 

of  snbmental.  4*^7 
pericardiac,  of  internal  mainiiiary.  517 

of  ])hrenic,  inferior.  553 

of  thoracic  aorta,  545 
perinaeal,  superficial,  574,  lOfiiJ 

transver.se,  575 
perirenal,  560 
peritoneal,  of  common  iliac.  .565 

of  superior  epigastrii-,  5ls 
peroneal,  591 

anterior,  592 

|K»sterior,  592 
petro&il,  494,  915 
pharyngeal,  ascending.  481 

of  pterygo-palatine,  496 


1222 


INDEX 


Artery,  or  Arteries — 

pharyngeal,  of  sphenopalatine,  49(5 

of  Vidian,  496 
phrenic,  inferior,  left,  553 
right,  553 

of  inferior  thyroid,  514 

of  musculo-phrenic,  518 

superior,  51(i 

of  superior  epigastric,  518 
pituitary,  499 
plantar  arch,  593 

digitals,  594,  GOl 

external,  593 

internal,  59() 
pleural,  550 
pontal,  511 
popliteal,  58G ;  surgical  anatomy  of,   1186  ; 

variations,  586 
postero-lateral,  of  posterior  cerebral,  512 
posterio-mediau,  of  posterior  cerebral,  512 
preventricular,  473,  936 
prevertebral,  481 
princeps  cervicis,  490 

hallucis,  601 

poUicis,  543 
profunda,  of  brachial,  inferior  and  superior, 
530  ;  variations,  530 

of  femoral,  583 
pterygoid,  external  and  internal,  495 
pterygo-palatine,  496 
pterygo-pharj'ugeal,  496 
pubic,  of  epigastric.  577 

of  obturator,  572 
pudic,  accessory,  570 

external,  deep,  583 

superficial,  583 

internal,  573,  1067  ;  surgical  anatomy 
of,  1126 
pulmonary,  462,  923 

left,  466 

right,  466 
pyloric  inferior,  557 
superior,  556 
quadrate,  503 
radial,  538 

in  forearm,  538  ;  variations,  540 

in  palm,  543  ;  variations,  543 

at  wrist,  541 

carpal,  anterior  and  posterior,  541 

recurrent,  540 
radialis  indicis,  544 
ranine,  485 
rectal,  of  lateral  sacral,  568 

of  middle  sacral,  564 
recurrent,  of  deep  palmar  arch,  545 

interosseous  posterior,  535 

radial,  540 

tibial,  anterior  and  posterior,  598 

ulnar,  anterior  and  posterior,  533 
renal,  560  ;  variations,  560 
sacral,  lateral,  567 

middle,  563  ;  variations,  564 
scapular,  dorsal,  525 

posterior,  516 
sciatic,  572  ;  surgical  anatomy  of,  1181 
septum,  artery  of,  496 
sigmoid,  562 

spermatic,  561  ;  variations,  561 
sphenoidal,  of  pterygo-palatine,  496 

of  spheno-])alatine,  496 
spheno-palatine,  496,  897 
si)ina],  anterior,  511 

of  inferior  thyroid,  514 


Artery,  or  Arteries — 

spinal,  of  intercostals,  548 
lateral,  510 
of  lateral  sacral,  568 
posterior,  511 
splenic,  557  ;  variations,  558 

of  left  ithrenic,  553 
stapedic,  490 
sternal,  517 
sterno-mastoid,  of  occipital,  489 

of  superior  thyroid,  482 

inferior,  of  suprascapular,  514 
stylo-mastoid,  490,  878 
subclavian,  505  ;  variations,  508      ' 

of  suprascapular,  514 
subcostal,  550 
sublingual,  485 
submaxillary,  487 
submental,  487 
subscapular,  524  ;  variations,  525 

of  posterior  scapular,  516 

of  suprascapular,  514 
suprahyoid,  484 
supra-orbital,  500,  1091 
suprarenal,  inferior,  560,  1051 

middle,  561,  1051 

superior,  553,  1051 
suprascapular,  514 
supraspinous,  of  posterior  scapular,  516 

of  suprascapular,  515 
supiasternal,  514 
sural,  588 

tarsal,  external  and  internal,  600 
temporal,  of  posterior  cerebral,  512 

deep,  anterior  and  posterior,  495 

middle,  491 

superficial,  491 
temporo-occipital,  512 
testicular,  561 
thalamic,  middle,  502 
thoracic,  acromial,  521 

alar,  524 

axis,  521 

long,  523 

short  or  superior,  521 

twelfth  (subcostal),  548 
thymic,  517 
thyroid  axis,  513 

inferior,  514 

superior,  482 
thjToidea  ima,  475 
tibial,  anterior,  596 

posterior,  590  ;  surgical  anatomy  of,  1183 
tonsillar,  of  facial,  487 

of  inferior  palatine,  487 
tracheal,  514 
trausversalis  colli,  515 

humeri,  514 
transverse,  of  basilar,  511 

cervical,  515 

of  external  circumflex,  584 

f\\cial,  491 

humeral,  514 

nasal,  502 

perinseal,  575 

of  right  coronary,  473 
tricipital,  of  posterior  circumflex,  526 

of  sujierior  profunda,  529 
tubal.  1092 
tympanic,  of  ascending  pharyngeal,  482 

of  internal  maxillary,  493,  915 

of  middle  meningeal,  494 

of  stylomastoid,  491 


INDEX 


1223 


Artery,  or  Arteries — 

tympanic,  of  Vidian,  496 
ulnar,  51}  1 

in  forearm,  531  ;  variations,  532 
in  palm,  53(}  ;  variations,  537 
at  wrist,  535 

carpal,  anterior  and  posterior,  535 
recurrent,  anterior  and  posterior,  533 
uncinate,  of  posterior  cereWral,  512 

of  posterior  communicating,  502 
uracheric,  570 
uretal,  of  ovarian,  562 
of  renal,  560 
of  spermatic,  561 
ureteric,  of  common  iliac,  565 

of  superior  vesical,  570 
uterine,  570,  1053 

of  ovarian,  562 
vaginal,  571 

azygos,  571 
vas,  artery  to,  570 
vasa  brevia,  558 
vermiform,  inferior,  511 

superior,  512 
vertebral,  509  ;  variations,  510 
vesical,  inferior,  mifldle,  and  superior,  570 

of  obturator,  572 
vestiV)ular,  491 
Vidian,  496 
volar,  superficial,  541 
xiphoid,  518 
zygoniatico-orbital,  491 
Artlirodia  [^fifnijiudia^  a  shallow  joint],  177 
Articular    [nrlicuhts,    a   joint  ;    dim.    of    arias, 
limb]— 
arteries,  of  circumflex,  posterior,  526 
of  interosseous  recurrent,  535 
of  plantar,  external,  594  ;  internal,  596 
of  popliteal,  588 
azygf)s,  590 

of  profunda,  superior,  529 
of  sciatic,  573 
of  suprascapular,  514 
of  temporal,  491 
eminence,  35,  70 
nerves,  of  auriculotemporal,  758 
of  circumflex,  789 
of  crural,  anterior,  807 
of  interosseous,  posterior,  795 
of  median,  791 
of  obturator,  805 
of  popliteal,    external,    814  ;    internal, 

817 
of  tibial,  anterior,  815  ;  posterior,  818 
recurrent,  of  external  popliteal,  815 
ulnar,  794 
process,  of  atlas,  8  ;  of  axi.s,  9  ;  of  coccyx, 
17  ;  of    fifth    lumbar   vertebra,   13  ;  mor- 
phology of,  23  ;  of  .sacrum,  15  ;  of  twelfth 
dorsal  vertebra,  12  ;  of  typical  vertebra, 
6  ;  of  typical  cervical  vertebra,  7  ;  of  typical 
lumbar  vertelira.  12 
surface,  of  acromion,  112 
of  head  of  tibia,  153 
vein  of  tempoial,  615 
Articulations    [arficitlus.    a   joint],     structures 
entering  into  the  formation  of,  176 
tabular  classification  of,  178 
varieties  of,  177,  178 
acromio  clavicular,  219 
of  ankle,  266 

of  articular  processes  of  vertebra-,  191 
astragalo-scaphoid,  273 


AKY 

Articulations — 

atlanto-axoidoan,  185 

of  auditory  ossjclcs,  877 

of  bodies  of  the  vertclira-,  190 

calcaneoa.stragaloi<l,  'i(i\) 

calcaneoculKjid,  274 

carpal,  237 

carpo-metacarpal,  240 

cliondrosternal.  212 

CO raco  clavicular,  220 

costo-central,  2flM 

costo-clioudral,  212 

costo-trans verse,  210 

crico-arytenoid,  906 

cricothyroid,  906 

cubo  cuueil'orin,  272 

cubo  metatarsal,  278 

cubo-scaphoid,  271 

of  elbow,  227 

of  heads  of  metacarpal  bones,  243 
of  metiitansal  bones,  279 

of  hip,  246 

of  incus  with  stapes,  877 

interchondral,  214 

intercoccygeal,  205 

intercuneiform,  272 

intermetacarpal.  242 

intermetatarsal,  279 

interphalangeal  of  fingers,  245 
of  toes,  280 

interpubic,  205 

intersternal,  212 

of  knee,  253 

of  the  lamina;  of  the  vertebrae,  194 

of  larynx,  906 

of  malleus  with  incus,  877 

medio-carpal,  238 

medio-tarsal,  273 

metacarpophalangeal,  243 

metatarso-phalangeal,  279 

occipito-atlantal,  183 

occipito-axoidean,  188 

of  the  pelvis,  200 

of  the  pelvis  with  the  .spine,  198 

of  pisiform  bone  with  the  carpus,  237 

radiocarpal,  233 

radioulnar,  inferior,  232 

middle  and  superior,  230 

of  radius  with  ulna,  229 

of  ribs  with  the  vertebrie,  208 

sacrococcygeal,  204 

sacro- iliac,  200 

scapho-cuneiform,  272 

scapular  ligaments  projier,  221 

scapuloclavicular  union,  219 

of  shoulder,  222 

of  skull,  179 

of  spinous  i)roce.sses  of  vertebrae,  195 

of  stapes  with  fenestra  ovalis,  877 

sterno  clavicular,  216 

tarso  nietatarsjil.  external,  277  :  internal, 
277  ;  middle.  277 

temporo-mandibular  (maxillary),  180 

tibio-tibular,  inferior  and  middle,  264,  265 
sujierior,  263 

of  the  transverse  proces.<ies,  197 

of  the  trunk,  classification  of.  19(> 

of  the  vertebral  column,  classification,  190 
Aryteno-epiglottidean  folds,  90.5 
Aryteno-epiglottideus  muscle,  910 
Arytenoid  [<ii>irnna,  a  pitcher;  fif5of,  like]  <'arti- 

lages,  904 
Arvteuoideus  muscle,  910 


1224 


INDEX 


Ascending  branch,  of  ext.  circumflex  artery,  584 
of  superior  cervical  ganglion,  828 
of  superior  profunda  arterj',  529 
branches  of  cervical  plexus,  783 

of  Meckel's  ganglion,  755 
cervical  artery,  514 
frontal  artery.  504 

convolution,  ()84 
palatine  artery.  486 
parietal  convolution,  684 
pharyngeal  artery,  481 
root  of  glosso-pharyugeal  nerve,  767 

of  trigeminal  nerve,  750 
septal  artery,  496 
Asterion  [affrz/p,  a  star  :  from  the  radiating  man- 
ner in  which  the  sutures  diverge  at  this 
spot],  the,  71,  1080 
Astragalo-scaphoid  articulation,  arterial  supply 
of,  276 
ligaments  of,  274 

movements  and  nerve-supply  of,  276 
Astragalus  [ficrpaya'Aoc^  a  die  ;  these  bones  were 
used  by  the  ancients  for  a  game  like  dice], 
the,  159 
articulations  of,  162 
ossification  of,  163 
OS  trigonum  of,  162 
Atlanto-axoidean     articulations,     arterial     and 
nerve-snpply  of,  185 
ligaments  of,  185 
movements  of,  187 
Atlas  [r'/Mu,  I  sustain,  from  its  support  to  the 
head],  the,  7 
muscles  attached  to,  11 
ossification  of,  20 
Atrium  [a  forecourt]  of  heart,  928 
Attic  of  tympanum.  40 

AttoUens  [atfollo,  I  raise]  aurem  muscle,  431 
Attraheus    [aliraho,    I    draw    forward]    aurem 

muscle,  431 
Auditory  [audio,  I  hear]  artery,  511,  883 
meatus,  external,  38,  73,  872 

internal,  36,  86,  96 
nerve  (eighth  cranial),  766  ;  branches,  767, 
883  ;  roots,  766 
Auricle  \_ai(iicula,  a  little  ear]  of  ear,  871 
nmscles  of,  extrinsic.  431 
intrinsic,  872 
of  heart,  left,  933 
right,  928 
Auricular  appendix,  928 
artery,  anterior,  491 

of  coronary,  left,  473  ;  right,  472 
deep,  493 
of  occipital,  490 

posterior,  489  ;  topography  of,  1090 
of  stylomastoid,  491 
canaliculus,  37 

cartilage,  of  .sacro-iliac  articulation,  202 
fissure,  37,  73 

lymphatic  glands,  po.sterior.  649 
muscles,  extrinsic,  431 

intrinsic,  872 
nerve,  anterior,  758 
great,  784 

of  lesser  occipital,  784 
posterior,  763 
of  vagus  (Arnold's),  772 
point  of  skull,  71 
portion  of  foetal  heart.  939 
process  of  inferior  turbinal  bone,  53 
septum,  931 
surface  of  ilium,  139 


BAS 

Auricular  veins,  of  ear.  616.  625 

of  heart,  left,  610.  937  ;  right,  610 
Auriculotemporal  nerve,  758 
Auriculo- ventricular  groove,  927 

openings,  928,  932  ;  topography  of,  1113 
Axes  of  skull,  81 
Axilla,  surgical  anatomy  of.  1150 
Axillary  artery,  520  ;  variations  of,  521 
border  of  scapula,  113 
fascia,  294 
lymphatic  glands,  655 

trunk,  656 
nerves,  of  brachial  plexus,  788 
vein,  643 
Axis  (vertebra)   [.so   called   from   its   pivot-like 
articulation  with  tlie  atlas],  the,  9 
muscles  attached  to,  11 
ossification  of,  20 
basi-bregmatic,  of  skull,  81 
basicranial,  of  skull,  si 
basi-facial,  of  skull,  81 
central,  of  cochlea,  881 
coeliac,  555  ;  variations,  555 
of  pelvis,  146 
sagittal,  of  eyeball,  843 
thoracic,  521 
thyroid,  513 
Axons,  740 

Azygos  [aCvj'Of,  single]  artery,  articular,  590 

vaginal.  570 
muscle,  pJtaryngix,  458 

uvuhc,  946 
veins,  major,  606 

minor  and  tertia,  607 


Back,  surgical  anatomy  of  the,  1142 
Band,  furrowed,  715 

iliofemoral,  247 

llio-tibial,  345 

ischio-femoral,  247 

moderator,  of  heart,  931 

pectineo-femoral,  248 

sterno-pericardial,  925 

tendino-trochanteric,  248 
Bars,  branchial,  90 

hyoid,  90 

mandibular,  90 

thyroid,  90 
Bartholin,  duct  of,  949 

glands  of,  1040,  1069 
Basal  ganglia  of  cerebral  hemispheres,  699 

grey  commissure,  707 

ridge  (cingulum)  of  tooth,  87 
Base  of  antrum,  57 

of  brain,  680 

of  epididymis,  1024 

of  heart,  926 

of  lung,  921 

of  petrosal  portion  of  temporal  bone,  35 

of  sacrum,  16 

of  skull,  exterior,  72  ;  interior,  82 

of  thorax,  898 
Ba.si-bregmatic  axis  of  skull,  81 
Basi-cranial  axis  of  skull,  81 

region  in  chondral  skull,  89 
Basi-facial  axis  of  skull,  81 
Basi  hyal  bone,  or  body  of  hyoid,  66 

centre  of  ossification.  95 
Basilar  \_l»isis,  the  base]  artery,  511 

bones,  24 

sinus  (transverse),  621 

suture,  86 


INDEX 


1225 


BAS 

Basilar  vein,  624  ;  tributaries,  624 
Basilic  [according  to  Hyrtl,  from   the    Arabic 
al-banilik,  the  inner  (vein)]  vein,  641 
median,  641 
Basi-otcipital  bone,  24  ;  at  l)irtli,  5)2 
Basion  [lidoK;,  l)ase]    the,  73,  81 
Basi-sphenoul  nucleus,  34 
Bertin,  bones  ol',  51 

columns  of,  1010 
Biceps  [bis,  twice  ;  caput,  a  head] — 

llexor  cubiti  muscle,   307,  1153;  nerve  to, 

791  ;  variations,  308 
flexor  fenioris  muscle,  363  ;  variations,  363 
Bicipital  artery  of  anterior  circumflex,  525 
groove  of  humerus,  116,  1150 
rib,  103 

tuberosity  of  radius,  12 
Bicuspid  [i/,s-,  twice  ;  cuspis,  a  point  or  projec- 
tion] teeth,  88 
valve  of  heart  (mitral),  934  ;  topography  of, 
931 
Bifid  [/y/.s,  twice  ;  Jindo,  I  cleave]  cervical  spinous 
processes,  10 
metasteruum  (xiphoid),  107 
Bile  duct,  common,  984 
Bipeuniform  \^penna,  a  feather]  muscles,  283 
Biventral  [&/s,  twice;  venter,  belly]  lobe  of  cere- 
bellum, 715 
Bladder,  gall,  the,  983  ;  duct  of,  984  ;  structure 
of,  985;  topography  of,  1117 
urinary,  the,  1016 

effects  of  distension  on,  1018 
female  and  infantile,  1020 
form  of,  1016 
ligaments  of,  1018 
lympliatics  oi',  662 
relations  of,  1016 
structure  of,  1018 
vessels  and  nerves  of,  1020 
Blood-vessels,   see   Arteries  and  Veins  ;  and  for 
the  vascular  supply  of  the  various  organs, 
see  those  organs 
Bochdalek,  ganglion  of,  754 
Body,  cutaneous  nerves  of,  822 
Bone,  or  Bones,  cancelli  [lattices]  of,  4 
compound,  1 
interparietal,  1209 
marrow  of,  3 
medullary  cavity  of,  4 
mode  of  development  of,  2 
pnc  interparietal,  1209 
l)ressure  and  tension  carves,  4 
shafts  of,  3 
structure  of,  3 
individual — 

iustragalus,  159 
atlas,  7 
axis,  9 
l)asilar,  24 
of  Bertin,  51 

calcaneum,  or  os  calcis,  163 
carpal,  128 

central,  of  carpus,  132 
clavicle.  109 
coccyx,  17 
cotyloid,  143 
cuboid,  165 

cuneiform,  of  carpus,  130 
of  tarsus,  167 
epipteric,  4s,  1209 
episternal,  113 
ethmoid,  49 
femur,  147 


Bone,  or  Bones,  individual — 
fibula,  158 
of  foot,  159 
frontal,  46 
of  hand, 128 
of  head,  24 
flip  bone,  138 
humerus,  115 
hyoid,  iiii 
ilium,  139 
incus,  67 
innominate,  138 
ischium.  139 
lachrymal,  53 
lingual  I  hyoid),  66 
magnum,  132 
malar,  61 
malleus,  67 

mandible,  or  inferior  maxilla,  62 
maxilla,  or  superior  maxilla,  55 
metacarpal,  VS.'> 
metatarsal,  169 
nasal,  54 
occipital,  24 
palate,  58 
parietal,  44 
patella,  152 
pelvis,  145 
phalanges,  of  foot,  172 

of  hand,  137 
pisiform,  131 
pubic,  142 
radius,  126 
ribs,  98 
sacrum,  15 
scaphoid,  of  carpus,  129 

of  tarsus,  16() 
sciipula.  111 
semilunar,  129 
sesamoid,  of  foot,  280 

of  hand,  245 
of  skull,  24 
sphenoid,  29 
sphenoidal  turbinal,  51 
stajies,  68 
sternum,  98 
styloid,  of  carpus,  137 

proce,ss,  67 
tarsal,  159 
temporal.  35 
tibia,  153 
trapezium,  141 
trapezoid.  131 
turltinal.  inferior,  52 

sphenoidal.  51 
ulna,  122 
unciform.  133 
vertebra  promineus,  9 
vertebrtc.  5 

cervical.  7 

dorsiil,  or  thoracic.  12 

lumbar,  12 

sacral  and  coccygeal,  14 
vestigial.  159 
vomer,  53 
Wormian,  48 
Boundary  zone  of  Lissauer,  740 
Bowman's  membrane,  846 
Brachia  [ Jon^v'"''.  an  arm]  of  nates,  710 

of  testes,  710 
Brachial  artery,  526  ;  surgical  anatomy  of.  1 153 
variations.  528 
plexus,  7>'6  ;  brauciics  uImivc  clavicle,  787 


1226 


INDEX 


Brachial  plexus,  branches  below  clavicle,  788 

vense  comites,  643 
Brachialis  auticus  muscle,  308,  1154 

nerves  to,  309,  791,  795 
Brachio-cephalic  [,Jpaj/wi',  the  arm  :  «fon/.//,  the 
head :   so   called   from   its   distributiou] 
See  Inuomiuate 

artery,  474 

vein,  603 
-Brachio-radialis  (supinator  longus)  muscle,  323  ; 

variations,  321 
Brain,  the,  679 

basal  ganglia  of,  G99 

base  of,  (i79 

epencephalon,  713 

hemispheres  of.  681 

lymphatics  of,  678 

meninges  of  672 

mesencephalon,  710 

metencephalon,  720 

sinuses  of,  619,  711 

thalamencephalon,  704 

topography  of,  10>*7 

weight  and  specific  gravity  of,  727 
Brain  sand  (acervulus  cerebri),  706 
Branchial  [,3pa>  J'«,  gills]  bars,  90 
Breast,  female,  1069.     See  Mamma 

male,  1072 
Breasts,  supernumerary,  1215 
Bregma  [/3/)fAw,  I  moisten],  the,  69,  81,  1080 
Broad  ligament,  of  liver,  the,  982 

of   uterus,    1048  ;    structures   between 
layers  of,  1048 
Broca's  olfactory  area,  692 
Bronchi  [  3/)6}_Y"f,  the  windpipe],  915 
Bronchial  [3/jdyjof,  the  windpipe]  artery,  545, 
925 

lymphatic  glands,  658 

nerves,  925 

veins,  609,  925 
Bronchioles  [dim.  of  bronchi'],  the,  915 
Broucho-mediastiual  lymph  trunk,  6.57 
Bruch,  membrane  of  846 
Brunuer's  glands,  969 
Bryant's  triangle,  1173 
Buccal  {_bitcc(t,  mouth]  artery  of  iacial,  487 
of  internal  maxillary,  495 
of  posterior  dental,  495 

fat  pad,  436 

lymphatic  glands,  649 

nerve  of  facial,  765 
long,  757 

orifice,  942 

portion  of  pharynx,  949 

vein,  614,  616 
Buccinator  [hiiccina,  a  trumpet  ;  from  its  use  in 

l)lowing  that  instrument]  muscle,  436 
Bulb,  the  (medulla  oblongata),  720 

artery  of,  575 

of  cornu  of  lateral  ventricle,  696 

olftrctory,  745 

ovarian,  633 

urethral,  1033 
Bulhi  [hnlhiis,  a  bulb]  vestibuli,  1040,  1068 
Bulbo  cavernosus,  or  accelerator  urina;  muscle, 

1U34,  1079 
Bundle,   ground,   of   spinal  cord,    anterior   and 
posterior,  741 

longitudinal,    of    cms    cereViri,    posterior, 
709 

of  Vicq  d'Azyr,  702,  707 
Burdach's  column,  of  spinal  cord,  741 
Burns,  falciform  process  of,  1138 


Bursa  [a  sac],  great  palmar,  317 

pharyngeal,  952 

prepatellar,  1184 
Bui-sjB  of  foot,  1199  ;  popliteal,  1188 
Buttocks,  surgical  anatomy  of  the,  1180 


Cecum  [ccTCK.s,  blind],  the,  970  ;  variations  of, 

970 
Calcauean  l_calx,  the  heel]  artery,  external,  .592 

internal,  593 
of  external  plantar,  593 
nerve,  internal,  818 
Calcaneo-astragaloid  joint,  anterior,  270 
posterior,  269 
movements  of  270 
Calcaneo-cuboid  joint,  ligaments,  274 
functions  of,  1203 

nerve-supply  and  movements  of,  276 
Calcaneo-plantar  cutaneous  nerve,  819 
Calcaneo-scaphoid  ligament,  external,  270 
inferior,  273  ;  functions  of,  1203 
Calcaneum  [c((/.r,  the  heel],  the,  163 
articulations,  164 
ossification,  165 
Calcar   [a   spur]    avis    [of   a   bird],    or   hippo- 
campus minor,  the,  696 
Calcarine  fissure,  the,  689 

Calcis  lc(d.i%  the  heel],  os,  163.     See  Calcaneum 
Calices  [coZ/.r,  a  cup]  of  kidney,  1006,  1010 
Callosal  fissure,  690 
Calloso- marginal  artery,  503 

fissure,  689 
Calyciform    (circumvallate)  papillae  of  tongue, 

884 
Canal,  Alcock's,  813,  1061 
carotid,  37 

central,  of  cochlea,  881 
clavicular,  110 
of  Cloquet,  851,  1212 
cranio-pharyngeal.  30  ;  at  birth,  93 
dental,  anterior,  55,  77 
inferior,  63,  97 
ethmoidal.  46,  50,  78,  82,  97 
Fallopian,  37,  41,  912 
femoral,  1139 
of  Huguier,  38,  73,  97 
of  Hunter,  1178 
hyaloid,  851 
infra-orbital,  55,  97 
inguinal,  1132 
lachrymal,  77,  868 
malar,  61,  97 
mandibular,  63,  97 
menibranons,  of  cochlea,  883 
neuro-enteric,  707 
of  Nuck,  1050 
palatine,  accessory,  59 

anterior,  56,  79 
external,  59 
posterior,  59,  70,  97 
of  Petit,  850 
petro-mastoid,  40 
pterygo-palatine,  33,  59,  70,  97 
spiral",  880 

Vidian,  32,  70,  97  ;  at  birth,  93 
of  Wirsung,  987 
Canaliculi  [dim.  of  canaZis,  a  canal]  hiclirymales, 

867 
Canaliculus,  auricular,  37 

tympanic,  37,  7:5 
Caualis  musculo-tubarius,  40,  73 
reunieus,  881 


LXIJEX 


1227 


Canals,  gubernacular,  72 
hepatic,  983 
portal,  983 
semicircular,  879 
Stenson's,  57 
Canine  [c«>i/.s,  a  dog  ;  because  the  canine  teeth 
are  most  prominent  in  the  dog] — 
eminence,  55 
fossa,  55 
teeth,  87 
Canthns  [Kavftog,  the  angle  of  the  eye],   inner 

and  outer,  S^IO 
Capitellum  [dim.  of  caput,  the  head],  the,  120 
Capsular  [dim.  of  capsa,  a  bo.\]  artery,  or  peri- 
renal, 56U 
or   suprarenal,    inferior,    560  ;  middle, 
561  ;  superior,  553 
ligament  of  acromio-clavicular  articulation, 
219 
of  atlanto-odontoid  articulation,  186 
of  carpo-metacarpid  joint  ol'  tliumb,  242 
■     of  costo-central  articulation.  208 
of  costo-trausverse  articuhition.  210 
of  crico-arytenoid  articulation,  907 
of  crico-thyroid  articulation,  907 
of  elbow-joint,  227 
of  hip-joint,  246 

of  inco-stapedial  articulation,  877 
of  interchondral  articulation,  214 
of  knee-joint,  256 
of  lateral   atlanto  axoidean  articulation, 

185 
of  malleo-incal  articulation,  877 
of  occipito-atlantal  articulation.  183 
of  pisiform-cuneiform  articulation,  237 
of  shoulder-joint,  222 
of  sterno-clavicular  articulation,  216 
of  superior  tibiofibular  articulation,  264 
of   tempf)ro-mandibular   (maxillary)     ar- 
ticulation, 180 
of  vertebral  articular  processes,  194 
vein  (suprarenal),  632,  1051 
Capsule  of  cerebrum,  external,  702 
internal,  701 
Glis.son's,  983 
of  spleen,  989 
of  Tenon.  860 

For   capsule   of  joints,    see  Capsular   liga- 
ments 
Capsules,  Bowman's.  1010,  1011 
Caput  coli  [the  caecum].  970  :  variations.  970 
Cardiac  \_Kap6'ia,  heart]  arterj'  of  gastric,  556 
ganglion  of  Wrisberg,  939 
lymph  glands  [superior  mediastinal],  658 
nerves  of  pneumogastric,  773 

of  sympathetic.  830 
orifice  of  stomach,  960 
plexuses,  superficial  and  deep,  834,  939 
veins,  anterior  and  posterior,  610,  937 
great,  610.  937 
smaller.  610 

anterior,  611 
Carina  [a  keel]  of  vagina,  1043 
Carotico-clinoid  ligament,  34 
Carotid  [Kap6u,  I  iuduce  sleep  :  pressure  on  them 
was  .supposed  to  cause  sleep] — 
artery,  common.  475  ;  collateral  circulation. 
479  :  relation  of  left  artery  to  chest- 
wall,  110.5,  1113  ;  variations,  479 
external,    480  ;    surgical    anatomy    of, 

1102  ;  variations,  480 
internal,  497 
canal,  37,  73 


Carotid  gland,  478 

lol)e  of  parotid  gland,  947 

plexus  of  sympathetic,  H-J- 

triangle.s,  surgical  anatomy  oi,  llirj 
Carpal  [Mi/i-i/r,  the  wrist]  aicli,  we  Carjial  rete 

artery,  radial,  anterior  and  posterior,  541 
ulnar,  anterior  and  |K)sterior,  535 

l)ones,  sec  Carpus,  bones  of 

joints  of  first  row,  2:57 

of  secon<l  row,  237 

ligaments,  2.37,  240 

rete  [a  net],  or  carpal  arch,   anterior  and 
posterior,  534 
Carpometacarpal  joints  of  fingers,  240 
of  thumb,  242 

ligaments,  241 
Carpus  [KUfjTTur,  wrist],  bones  of  the,  128  ;  ossifi- 
cation of,  133 

medio-carpal  joint,  ligaments  of,  2.39 

movements  of  carpal  joints,  240 
Cartilage,  articular,  of  shoulder-joint,  22.5 

costal,  102  :  development  of,  103 

cricoid,  903 

periotic,  of  chondro-cranium,  89 

pre-coracoid,  11.5 

spheuotic  [aoi/i',  a  wedge  ;  oi'f,  the  ear],  89 

tarsal,  429,  HCH 

thyroid,  901 

See  also  Fibro-cartilage 
Cartilages,  accessory  quadrate,  891 

arytenoid,  904 

cuneiform,  905 

Jacobsonian,  891 

of  larvnx,  901 

of  nose,  890 

lateral,  890  ;  origin  of,  96 
septal,  891  ;  origin  of,  96 

sesamoid,  H83 

of  Santoriui,  905 

of  Wrisberg,  905 
Cartilaginous  cranium,  the.  89  ;  remnants  of,  95 

framework  of  ear,  871 

portion  of  Eustachian  tube,  876 

of  external  auditory  meatus,  673 
of  nose,  889 

rings  of  trachea,  913 
Cartilago  triticea  [like  a  wheat  grain],  905 
Caruncle,  la<hrynial,  840,  843 
Caruncula?   [dim.    of   cam,   fiesli]   myrtiformes 

[>H.i/;/i/s,  myrtle],  1130 
Cauda  equina  [a  horse's  tail],  the,  732,  777 
Caudal  aorta.     See  Coccygeal  glomerulus 
Can<late  lobe  of  liver,  978 
Cava  [liollow],  vena,  inferior,  631 

tributaries,  ()31  ;  variations,  633 

sui)erior,  603 
Caval  artery  of  right  phrenic,  553 
Cavernous  groove,  31 

nerves  of  ]ienis,  large  and  small,  838 

plexus,  oJ  svmpathetic,  82-; 

sinus,  622 
Cavities  of  heart,  928 
Cavity,  cotyloid,  138,  143 

sigmoid.  *)f  radius,  127 

of  ulna,  greater,  122:  les^<ir.  123 

of  true  pelvis,  145 

of  uteru.s,  1047 
Cavum  [a  hollow]  Retzii,  lol7 
Cells,  etlunoidal,  50,  80  ;  development  of.  ,50 

fronto-ethmoidal.  .'>0 

lachrymo-cthnioidal.  .50 

mastoid.  40.  1(K{ 

maxillo-ethmoidal.  50 


1228 


INDEX 


Cells,  palato-etliinoidal,  50 
spheuo-ethinoidal,  50 
Central  artery  of  anterior  cerebral,  503 
of  tiie  retina,  500,  851 
axis  of  cochlea,  881 
canal  of  cochlea,  881 

of  spinal  cord,  738 
connective  tissue  of  orbit,  866 
element  (l)oiie)  of  carpus,  133 
<rrey  matter  of  third  ventricle,  705 
lobe  of  cerebrum,  680 
odontoid  ligament,  188 
point  of  arm,  topography  of,  1154 

of  the  perinanim.  1122 
sulcus  (fissure  of  Rolando),  682 
tendon  of  diaphragm,  400 
vein,  cerebral  (ganglionic,  or  deep),  624 
of  retina,  626 
Centres  of  ossification.     See  Ossification,  centres 

of 
Centrum    [centre]  of  typical  vertelira,  5  ;    mor- 
phology of,  22 
of  axis,  9 

of  fifth  lumbar,  13 
ovale  majus  et  minus,  6«9 
of  typical  cervical  vertebra,  7 
lumbar  vertel)ra,  12 
Cephalic  [according  to  Hyrtl,  from  the  Arabic, 
al-kifoQ  vein,  641 

median,  641 
Cerato-hyals  [^f'p"f,    a  horn  ;    and  t',  the  letter 

upsilon],  66 
Cerebellar  arteries,  anterior,  or  ant.  inferior,  512 
posterior  inferior,  511 
superior,  512 
commissure,  741 
peduncle,  superior,  713 
root  of  trigeminal  nerve,  750 
tract  of  spinal  cord,  direct,  741 
veins,  inferior,  624  ;  superior,  624 
Cerebellum  [dim.  of  cereirum'\.  670.  713 
fibres  of,  741 

grey  matter  in  interior  of,  716 
white  matter  of,  716 
Cerebral  arteries,  anterior,  503,  513 
middle,  503,  513 
posterior,  512,  513 
distribution  of,  513 
hemorrhage,  artery  of,  503 
hemispheres.  670,  681 

convolutions  and  fissures  of,  684 
topography  of,  727 
lymphatics,  deep,  651 
veins,  623 
vesicles,  669 
Cerurainous  glands,  1077 

Cervical  {^cervix,  the  neck]  artery  of  uterus,  570 
deep,  of  superior  intercostal,  518 
superficial,  516 
transverse,  515 
cardiac  nerves  of  sympathetic,  830 

of  vagus,  772 
enlargement  of  spinal  cord,  734 
fascia,  deep,  444,  1105;  functions  of,  1134 
ganglion,  inferior,  830 
middle,  830 
superior.  827 
lymphatic  glands,  deep,  653 

superficial  chain.  650 
nerve,  superficial,  783 

transverse,  topography  of,  1103 
nerves,  anterior  primary  divisions  of,  782 
posterior  primary  divisions  of,  778 


Cervical  nerves,  relation  of.  to  the  nuisdes  of  the 
upper  extremity,  798 
plexus,  783 

branches,  deep,  785 

superficial,  783 
to  hypoglossal  from.  775 
portion  of  gangliated  cord  of  svmpathetic, 

827 
rib,  103 

tubercles  of  femur,  147 
vein,  deep,  614,  628 
transverse,  617 
vertebra,  typical  characters,  7 
peculiar  vertebrae,  7 
seventh,  9  ;  muscles  attached  to,  15 
Cervicalis  ascendeus  muscle,  417 
Cervico-basilar  ligament,  188 
Cervico-facial  division  of  facial  nerve,  765 
Cervix  "[neck]  of  uterus,  1044  ;    cavity  of,  1045 
Chambers  of  eyeball,  850 
Characters,  general,  of  foetal  skull,  90 
of  t^'pical  rib,  99 
of  vertebra,  5 
Check  (lateral  occipito-odontoid)  ligaments,  188 
Cheeks,  the,  942 
Chiasma  \ x'ai^'-',  I  cross],  optic,  708,  746 

fibres  of,  746 
Chin,  the,  62 

Chondro-cranium  [joi'''pof,  cartilage],  the,  sO 
Chondro-epitrochlenris  muscle,  458 
Chondro-glossus  (hyo-glossus)  muscle,  452 
Chondro-sterual  articulation,  211 

movements  of,  214 
Choudro-xiphoid  ligament,  214 
Chopart's  amputation,  incision  for,  1198 
Chorda  [jop<S;;,  a  cord]  tympani,  762 
Chord je  tendineai,  931,  933 
Chorio-capillaris,  842,  847 

Choroid  [xopmv,  the  chorion  ;  e^i^oc,  like  :  from 
its  vascularity],  the,  845,  847 
artery,  anterior,  502 

posterior,  512 
plexu-ses,  698,  704,  718 
vein,  624 
Ciliary  \_ciliiun,  an  eyelash],  853 
arteries,  501,  852 

of  lachrymal,  500,  853 
body,  847 
ganglion,  752,  864 
glands  of  Moll.  1077 
muscle,  845,  846 
nerves,  long,  752,  850 

short,  753,  850,  864 
processes,  845 
veins,  anterior  and  posterior,  625 

lower  jwsterior,  626 
zone  of  iri.s,  842 
Cingulum  [a  girdle]  of  gvrus   fornicatus,  689, 
694 
of  teeth,  87 
Circle  of  Will  is.  504 
Circular  sinus  of  cranium,  621 

inferior  (of  Winslow),  621 
Circulation,  ftttal,  course  of,  939 

organs  of,  925 
Circulus  iridis,  major  et  minor,  852 
Circumduction  [t'/>T«»(,  around  ;  duio,   I  lead], 

179 
Circumference  of  average  skull,  W) 
Circumflex    \_circum,  around  ;  Jhx'to,  I   bend] — 
artery,  anterior.  525  ;  variations,  526 
external,  584  ;  variations,  584 
internal,  584  ;  variations,  584 


INDEX 


1229 


Circuiiirtex  artery,  iwslerior,  526  ;  variations,  5'2() 
iliac,  deep,  578  ;  variations,  57^ 
superticiai,  583 
nerve,  789 

vein,  iliac,  deep,  647  ;  superficial,  6;J1,  644 
Circunitlcxus  palati  muscle,  ;;;5,  944 
Cireunivallate  [circitmvallaiua,  trenched  around] 

papilhe  ol' tongue,  884 
Cistern  of  Pecquet,  or  receptaculuni  chyli,  659 
Cisterna  magna  otciauial  meninges,  677 

pontis,  678 
Clarke's  column  of  spinal  cord,  737 
Ciaustruni  [rlmtilo.  I  shut],  tiie,  7(10 
Clava  [a  club],  the,  722  ;  nucleus  of,  72() 
Clavicle  [dim.  of  clavii<,  a  key  :  from  its  shape], 
the,  109 
blood-supply  and  ossification  of,  111 
Clavicular  artery  of  acromio-thoracic,  521 

canal,  110 
Clavi-pectoral  fascia,  294 
Cleft  sternum,  108 
CU'iilo-Itfioid  muscle,  458 

Cleido-occijutal  [^/f/r,  a  kev  ;  f^'or^  like]  mus- 
cle, 446 
Cleido-occipilalis  muscle,  458 
Clinoid  [n'/iii/,  a  bed  ;  f/A'f,  like  :  from  their  re- 
semblance  to  the   four   ix)sts  of  a  bed] 
processes,  anterior,  middle,  and  jjosterior, 
30,  83 
Clitoris  [K/ei(j,  I  shut  up],  the,  1040 
dorsal  artery  of,  576 
nerve  of,  814 
Clivus  [a  slope],  the,  86 
Cloaca  [a  sewer],  the  primitive,  1055 
Clociuet.  canal  of,  850 
Coats  of  eyeball,  inner  or  nervous,  848 
middle  or  vascular.  847 
outer  or  fibrous,  846 
of  Fallopian  tube,  1051 
of  intestine,  large.  969 

small.  968 
of  stomach,  962 
Coccygeal  aorta,  see  Middle  sacral  artery 
artery,  572 
coruua,  17 
nerve,  810 

primarj'  divisions  of,  anterior,  810 
posterior,  781 
plexus  (nerve),  809 
vertebra?,  14,  17  ;  ossification  of,  22 
Cocoygeus  muscle,  1062  ;  nerve  to,  809 
Coccyx  [kokkv^j  a  cuckoo  :  from  its  fancied  like- 
ness to  a  cuckoo's  beak,  17 
ossification  of.  22 
Cochlea  [ko.\>oc,  a  shell  fish],  41,  8s() 
Cochlear  nerve,  767 

Cieliac    [Koi'/ia.    the   belly]    artery    (axis).  555 ; 
topography  of.  1121  ;  variations,  555 
lymph  glands,  662 
plexus,  835 
Colic  Iku/ov^  the  large  intestine]  area  of  anterior 
surface  of  kidney,  10(t9 
arteries,  left,  562  ;  middle.  559  ;  right,  5.59 
Collateral  arteries,  digital,  of  fingers.  538 
of  toes.  595 
intercostal,  549 
eminence,  690 
fissure,  68B,  690 
Collecting  tubes  of  kidney,  1011 
Colles,  fascia  of,  1065 

Colliculus  [dim.  of  cnlli!<.  a  hill]  seminalis,  1(I37 
Colon  [Ku/or,  the  large  intestine],  972 
ascending,  972 


CON 

Colon,  blood -su PI )ly  of,  975 
descending,  97.3 
nerves  and  lymphatics  of,  975 
sigmoid  llcxure  of,  973 
structure  of,  975 
transverse,  972 
Coiotomy,  hunbar,  landmarks  leu,  lliy 
Columella,  tlie,  880 
Columuic  Hertini,  1010 
carncic,  9.31,  O.'i.J 
rugarum  of  vagina.  1043 
Columns  of  cord,  liurdach's.  741 
Clarke's.  737 
(ioll's,  741 
of  medulla,  lateral,  722 
Comes  [a  companion]  nervi  i.schiadici,  573 
inediani.  533 
phrenici,  516 
Comma-shaped  tract,  741 
Commissura  [coti,  together  ;  mitto,  I  .send]  mollis, 

705 
Commissura'  ad  flocculos,  757 
Commissural  branches  of  anterior  cerebral  arterv, 

503 
Commissure  [union]  of  cerebellum,  great  ante- 
rior. 716' 
of  cerebrum,   anterior  (white),   701  ;   b:isal 
(grey),  70(i  ;  middle  (tjrey),  705  ;  poste- 
rior (white).  704,  706,  716 
Gudden's,  747 
Meynert's,  747 
optic,  708,  746  ;  fibres  of,  746 
of  %'agina,  posterior,  1039 
Common  bile  duct.  984 

carotid  arteries,  475  ;  branches  and  varia- 
tions.   479 ;    collateral    circulation    after 
ligature,  479 
femoral  artery,  579  ;  variations,  581 

vein,  646  ;  variations,  647 
iliac  arterv,  564  ;  ct)llateral  circulation,  565  ; 
variations,  565 
veins,  634  ;  variations,  634 
pelvis  of  kidney,  1014 
Communicans  peronei  nerve,  813 

tibialis  nerve.  817 
Communicantes  hypoglossi,  785 
Coniplexus  muscle.  420 
Compressor  nariuni  mu.scle,  432,  891 
minor  muscle,  892 
sacculi  laryngis  muscle,  911 
urethra'  muscle,  1068 
vagina"  muscle,  1069 
venie  dors;ilis  penis  muscle.  1034 
Conarium  [c'on«.s,  a  fir  cone]  or  pineal  body.  7<i6 
Concha  [^•C/  V'/,   a  shell],  the,  871 
Conductor  .sonorus.  of  fourth  ventricle.  71,  774 
Condylar  lines,  inner  and  outer,  of  femur,  150 

ridge,  external.  118 
Condyle  [koiiSi/oc,   knuckle],  tertiary  occipitil, 
'  28 

of basioccipital,  28,  73 

of  femur  (internal  ami  external),  l.'><i  ;  surgi- 
cal anatomy  of,  1184 
of  humerus,  internal  (ulnar),  120 

external  (radial).  120 
of  mandible  (lower  jaw).  63  ;  neck  of,  64 
miniature,  of  phalanges  (finger  i,  137 
Condyloid  [koii'i /.of,  a  knuckle  ;  f'/('"f,  like]  fora- 
men, anterior,  26.  73,  86,  96 
I>osterior.  28,  73 
centre  of  ossification  of  mandible,  65 
fos.s;i.  jMisterior.  28 
tubercle  of  mandible,  65 


1230 


INDEX 


CON 

Conical,  or  filiform,  papillie  of  tongue,  885 
Coujoiut  tendon,  407 

Conjugate   diameter  of  pelvis,    145  ;    measure- 
ments of,  14(5 
Conjunctiva  \^con,  together  ;   jutiffo,  I  join],  ocu- 
lar. 841 
palpebral,  840,  867 
surgical  anatomy  of,  1093 
Conjunctival  sac,  841 
Connective  tissue,  central,  of  orbit,  865 

subaponeurotic,  of  scalp,  1085 
subperitoneal,  958 
Conoid  [K(jri)(;^  a  cone  ;  ti(W,  like]  ligament,  220 
Constrictor  muscles  of  nose,  892 

of  pharynx,  950 
vaginae  muscle,  1041 
Conus  arteriosus  [Kwi'of,  a  cone],  462,  931 
medullaris,  734 
vasculosus,  1027 
Convolution,  post-parietal,  686 
Convolutions   [con,  together;    rolvo,    I   roll]    of 
cerebrum,  Broca's,  685 
dentate,  691,  698 

frontal,  ascending,  6S4  ;  inferior,  684  ;  mid- 
dle, 684  ;  superior,  684 
infra-marginal,  688 
marginal,  690 

occipital,  inferior,  687  ;  middle,  687  ;  supe- 
rior, 687 
orbital,  anterior,  685  ;  internal,  685  ;  poste- 
rior, 685 
parietal,  ascending,  686 
straight,  685 
supramarginal,  686 

temporal,  inferior,  688  ;  middle,  688  ;  supe- 
rior, 688  ;  transverse,  688 
Coracoacromial  ligament,  221 
Coraco-brachialis  muscle,   305  ;    nerve  to,   790  ; 

surgical  anatomy  of,  1150 
Coraco-clavicular    ligament,   220  ;    origin    from 
subclavius.  281 
union,  arterial  and  nerve  supply  and  move- 
ments of,  220  ;  ligaments  of,  220 
Coraco-humeral  ligament,  224 

origin  from  pectoralis  minor,  281 
Coracoid    [/lopnf,   a  raven  ;    euhc,   like :    from   a 
laucied  resemblance  to  a  raven's  beak]  (or 
transverse)  ligament,  221 
process,  113 
Cord,  gangliated.  of  sympathetic,  826  ;  cervical 
and  cranial  ijortion  of.  826  ;  lumbar  and 
sacral,  833  ;  thoracic  (dorsal),  830 
genital,  1094 

spermatic,  1030  ;  constituents  of,  1030 
spinal,  731  ;  deep  origin  of  nerves  of,  737  ; 
external  characters,  734  ;  internal  struc- 
ture, 737  ;    meninges  of,  731  ;   tracts  of, 
738 
Cornea  [conieiis,  horny],  the,  846 

lymphatic  spaces  of,  852 
Cornicula  [dim.  of  cornu,  a  horn]  larj'ngis,  or 

cartilages  of  Pantorini,  905 
Cornu  [a  horn]  Animonis  (from  its  likeness  to 
the  horns  on  the  .statue  of  .lujiiter  Am- 
nion), or  hippocampus  major,  697 
Coruua,  coccygeal,  17 

of  fascia'lata  of  thigh.  1166 

of  hvoid  bone,  66  ;  centres  of  o.ssification  for, 

95 
of  lateral  ventricles,  anterior  and  posterior, 

696  ;  inferior  or  descending,  697 
.sacral,  15 
of  thyroid  cartilage,  iuferioraud  superior,  904 


Corona  [a  crown]  ciliaris,  847 
glandis,  1033 

of  the  optic  thalamus,  784 
radiata,  the,  709 
Coronal  [corona,  a  crown]  section  of  brain,  671 
of  skull,  81 
suture,  44 
Coronary  arteries  [co)o)io,  a  crown  or  circlet  :  so 
called    because    they   encircle  the 
heart]  of  heart — 
left,  course  and  branches,  473,  973 
right,  course  and  branches,  472,  972 
variations  of,  473 
of  stomach,  556 

branches  and  variation^,  556 
of  lips,  inferior,  487  ;  superior,  487 
ligaments  of  knee,  259 
of  liver,  982 
plexus,  right  and  left,  839,  939 
sinus,  610,  929,  937 

vein,  cardiac,  610,  973  ;  anterior  and  poste- 
rior,    611,    974;     great,     610,     973; 
smallest,  611 
gastric,  674 
labial,  613 
Coronoid  centre  of  ossification  for  mandible,  64 
fossa  of  humerus,  120 
process  of  mandible,  64,  1096 
of  ulna,  122 
Corpora   [plural   of  corpus,  a   body]    albicautia 
[albico,  I  become  white],  702,  707 
clitoridis,  1068 

quadrigemina  [quadrigemhms.   four,  placed 
in  two  pairs],  708,  710 
Corpus  [a  body]  Arantii,  932 

callosum  [callus,  hard],  670,  692 
cavernosum     [caverna,    a     cavern],     1032 ; 

artery  of.  576 
dentatum  [dentatus,  toothed],  716 
fimbriatum  [fimbria,  a  fringe].  697 
geniculatum  [dim.  of  genul  externum,  710 

internum,  710 
Highmorianum.  1026 
luteum  [yellow],  1053 
spongiosum  [sponr/ia.  a  sponge].  1031 
striatum  [dria,  a  streak],  699 
trapezoides  [rpaTre^a,  a  table  ;  f(f5of,  like]. 
720,  766 
Corpuscles  of  Pacini,  1076 

tactile,  of  IMeissner,  1076 
Corrugator     [corrugare,    to    wrinkle]     supercili'' 
muscle  (the  muscle  that  wrinkles  the  eye- 
brows), 430 
Cortex  [the  rind]  of  kidnev,  1010 
of  lens,  850 
of  olfactory  tract,  744 
Cortical  arteries  of  kidney,  1011 

hemispheral,  of  anterior  cerebral,  503 
of  middle  cerebral,  504 
of  posterior  cerebral,  512 
veins  of  brain,  superior  and  inferior,  623 
Cortico-medullary  arches  of  kidney,  1011 
Costal  [costa,  a  rib]  cartilages,  102 
Costo-central   articulation,    arterial    and    nerve 
supply  of,  209 
ligaments  of,  208 
movements  of,  210 
Costo-cervical  artery  (superior  intercostal),  518 
Costo-choudral  articulation,  210 
Co.sto-clavicular  (rhomboid)  ligament,  218 
Costo-colic  ligament,  973 
Costo-coracoid  ligament,  origin  of,  115 
membrane,  294 


IXDEX 


1231 


cos 

Codo-fascinlis  nmscle,  408 

Costo- transverse  articulation,  arterial  auil  nerve 
supply  ol",  211 
ligaments  of,  210 
movements  of",  211 
Costovertebral  groove,  108 
Cotunuius,  nerve  of,  755 

Cotyloid  \_K<iTi'/!j^  a  cup  ;  fMoc,  like]  Iwne,  U:{ 
cavity  (acetaV)ulum"),  138,  143 
foramen,  143 
notch,  143 
Cowper's  glands,  1067  ;  development  of,  105'^ 
Cranial  \_Ki)aviov,  the  skull]  fossa,  anterior,  82 ; 
middle,  83  ;  iwsterior,  86 
nerves,  743  ;  general  distrihution,  745 
superficial  and  deep  origins  of,  744 
sinus,  definition  of,  711 
sinuses,   venous,    619.     See  aho   Sinus,    for 
individual  sinuses 
Craniocerebral  topography,  1086 
Cranio-facial  angle,  81  ;  measurement  of,  86 
Cranio-pharyngeal  canal,  30  ;  at  biitli,  93 
Cranium  [/cpawor,  the  skull],  capacity  of,  aver- 
age, 86 
cartilaginous,  the,  89  ;  remnants  of,  95 
measurements  of,  average,  83,  86 
membranous,  the,  89 
results  of  elasticity  of,  1086 
structure  of.  1086 
Cremaster  \_KpEuni.>,  I  suspend  :  from  its  action  ou 

the  testis]  muscle,  407 
Cremasteric  artery  of  deej)  epigastric,  577 
of  spermatic,  561 
fascia  (or  middle  spermatic),  1024 
Crest,  falciform,  36 

of  ilium  (iliac),  139 
malar,  of  sphenoid,  32 
obturator,  143 

occipital,  external,  25  ;  internal,  26,  86 
of  pubes,  143 
of  scapular  spine,  112 
sphenoidal.  30 
supramastoid,  35 
of  tibia.  153 

turbinated,  inferior  and  superior,  56 
Cribriform   [^crihrum,  a  sieve]  area,  middle  and 
superior,  36 
fascia,  346 
plate  of  ethmoid,  49 
tract,  spiral.  36 
Cricoarytenoid  joints,  911 

(or  transverse)  ligament,  911 
posterior,  911 
Cricoars'tenoideus  lateralis  muscle,  912 
posticus  muscle,  912 
Crico-thyroid  artery,  483 
joints,  911 
membrane,  910 
muscle.  910 
Cricoid  [/i/j(/ior,  a  ring  ;  n^oc,  like]  cartilage,  910 
Crista  [a  crest]  vestibuli,  41 

galli  {gall us,  a  cock],  49,  82 
terminalis,  1213 
Crown,  of  teeth,  86  ;  relation  of  upi>er  to  lower 

tooth  crowns,  89 
Crucial    {crux,  a  cross]   anastomosis  of  femur, 
573,  584 
ligament  of  central  atlanto-axoidean  joint, 
186 
of  knee-joint,  257 
ridges  of  occipital  bone,  25 
Crura  {crus.  pi.  crura .  leg]  cerebri,  752 
of  diaphragm,  399 


Crura  of  facial  nerve,  761 

of  stapes,  68 
Crural  arch,  1138;  deep,  411,  1139 
nerve,  anterior,  MO6 

of  geiiito  crural,  804 
septum,  1138 
Crnreus  muscle,  367 
Cms,  artery  of  tiie,  576 
clitoridis.  1040 
penis,  1032 
Cru8t;i  [the  rind,  or  crust],  the,  of  crura  cerebri, 

711 
Cr\'.stainne  lens,  the,  849 

Cubo-cuneiform  joint,  arterial  ami  nerve  supply 
and  movements  ot,  272 
ligaments  of.  272 
Cubo-metatarsal  joint,  278 

Culw-scaphoid  joint,  arterial  and  nerve  sujjplv 
of,  271 
ligaments  of,  271 
movements,  273 
Cuboid  [m  ^"f,  a  cube  ;  ti'Soc,  like],  the,  165 

articulations,  ligaments,  attachment  of  mus- 
cles, and  ossification,  166 
Culmen  [a  roof],  the,  of  cerebellum,  714 
Cnneate  [cuneus,  a  wedge]  lobule  of  cerebrum, 

691 
Cuneiform  [oMHeH*,  a  wedge]  bone,  carpal,  130  ; 
ossification,  133 
tarsal,  external,  168  ;  ossification,  169 
internal,  167  ;  ossification,  168 
middle,  167  ;  ossification.  168 
cartilages  of  Wrisl)erg,  943 
Cuneus  [a  wedge],  or   cuneate  lobnle  of  cere- 
brum, 691 
Cupula  [a  vault]  of  cochlea,  881 
Currator  cocci/gifi  muscle.  458 
Cushion  of  the  epiglottis,  905 
Cutaneous  branches  of  sensorv  and  mixed  nerves, 

819 
Cystic  [Kicrrff,  a  bladder  or  bag]  artery.  557 
duct,  984 

plexus  (nerve),  637 
vein,  636 


Dartos  [f5nprof,  flayed]  of  penis,  1032 

of  scrotum,  1023 
Date  of  ossification  of  bones  of  foot,  175 

of  hand,  133 
Declive,  the,  of  cerebellum,  714 
Decussatio  lemnisci  [/'/uviokoi;,  a  band].  726 
Deferential  arter>'  (artery  to  vas  delerens).  604 
Deiter's  nucleus  of  auditory  nerve,  765 
Deltoid  [i^'/ra,  the  letter  i  :  ''«''•":,  like  :  from  its 
shape]  ligament  of  ankle,  267 
muscle,  300  :  surgical  anatomy  of,  1151 
tubercle,  109 
Dendrites,  740 

Dental  [dtiio.  a  t4K)th]  artery,  anterior,  496 
inferior  (or  mandibular),  494 
posterior,  495 
canals,  anterior,  55,  77,  97 
formula,  adult,  86  :  temjiorary,  89 
nerves,  inferior  (mandibular),  758 

superior,  754 
veins,  inferior  (mandibular),  616 
p«isterior,  616 
Dentary  centre  of  ossification  iu  mandible,  65 
Dentate  convolution.  691.  69s 
fascia  (convolution*,  691,  698 
fissure,  691 


1232 


INDEX 


1 


Depression  for  Gasserian  ganglion,  83 

lateral,  of  middle  fossa  basis  crauii,  83 
rhomboid,  of  clavicle,  110 
Depressor  alte  nasi  muscle,  433,  930 
anguli  oris  muscle,  438 
labii  inferioris  muscle,  439 
thyroidea  muscle,  4r)8 
Derm,  1074 

Descemet"s  membrane,  846 
Descendens  bypoglossi  nerve,  775 
Descending  branch  of  external  circumflex  arterv, 
584 
branches  of  cervical  plexus,  784 
of  Meckel's  ganglion,  756 
colon,  1009 

coruu  (inferior)  of  lateral  ventricle,  697 
palatiue  arteries,  496 
pharyngeal  arteries,  496 
ramus  of  pubes,  142 
root  of  optic  nerve,  747 

of  trigeminal  nerve,  749 
Development  of  geuito-urinary  organs,  1055 

For  bones,  see  Ossification,  centres  of 
Diameters  of  pelvis,  145 
Diaphragm  [cS/a^payun,  a  partition],  the,  399 
opening  in,  400 
surgical  anatomy  of,  1116 
Diaphragma  sellae,  673,  675 

Diaphiagmatic  arteries  of  aortic  iutercostals,  550 
lymphatics,  656 
plexus  (nerve),  835 
Diartbrosis  [(5'a,  between  ;  apOpov^  a  joint],  defi- 
nition and  examples  of,  177 
subdivisious  of,  177 
Digastric  [(5'C,  twice  ;  yacrijp^  belly]  fossa,  63 
groove,  37,  73 
muscle,  449 
tendon,  450 
Digestion,  orgaiss  of,  942 
Digital  arteries  of  fingers  of  palmar  arch,  538 
collateral,  538 
dorsal,  542 
of  toes,  collateral,  595 

dorsal,  of  dorsal  interosseous, 
600 
of  dorsalis  hallucis,  601 
plantar   (connnunicating),    of 
dorsalis  pedis,  601 
of  external  plantar,  594 
fifth    (priuceps  pollicis), 
001 
superficial,  of  internal  plantar, 
596 
fossa  of  tunica  vaginalis,  1024 
nerves  of  toes,  819 

of  fingers,  795 
phalanges  of  foot,  172 

of  hand, 137 
veins  of  foot,  644 
of  hand,  640 
Dilatator  naris  anterior  muscle,  433 

posterior  muscle,  433,  891 
Dimensions  of  kidney,  1042 
of  ovaries,  1090 
of  uterus,  1084 
Dimples,  1073 

Diploe  ['5'T/oof,  double],  veins  of,  618 
Diploic  artery,  500 
Direction  of  inguinal  canal,  1161 

of  uterus,  1084 
Disc,  optic,  842 

Distal  row  of  carpus,  bones  of,  128 
surface  (of  tooth),  86 


Diverticulum  [^diverto,  I  turn  aside],  Meckel's, 

967 
Dorsal  arterv  of  clitoris,  576 
of  penis,  576,  1066 

branch  of  aortic  intercostal  artery,  549 
of  ulnar  (posterior)  nerve,  794 

digital  arteries  of  fingers,  542 
of  toes,  600 

integument  of  hand,  nerve  supply  o*",  797 

interosseous  arteries  of  foot,  600 
of  hand,  54 i 

nerve  of  clitoris,  814 

of  penis,  806,  1067 

(or  thoracic)  ve~tebra,  peculiar,  12 
typical,  12    , 

scapular  artery,  525 

spinal  plexus  (venous),  628 

vein  of  x^enis,  6.38 

venous  plexus  of  hand,  640 
Dorsalis  hallucis  artery,  601 

indicis  artery,  543 

lingute  artery,  484 

pedis  artery,  600  ;  surgical  anatomy  of,  1242 

pollicis  artery,  543 
Dorso-epitrochlearift  muscle,  458 
Dorsum  ephippii  [i<{)i7vmor^  a  saddle,  30,  83  ;  at 
birth,  93 

ilii,  139 

of  scapula.  111 

of  tongue.  884 
Douglas,  fold  of,  410 

pouch  of,  1043,  1044 
Duct,  Bartholin's,  949 

common  bile,  984 

cvstic,  984 

ejaculatory,  1030  ;  orifice  of,  1033 

of  Gartner,  1043,  1214 

hepatic,  984 

lachrymal,  55,  77 

Miillerian,  1055 

na.sal,  80,  906 

of  pancreas,  987 

of  parotid.  948  ;  surgical  anatomy  of,  1091 

renal  (ureter),  1014 

Rivini's,  949 

of  sublingual  gland,  949 

W'alther's,  949 

Wharton's  (submaxillary),  948 

Wolffian,  1055 
Ducts,  galactophorous  lydTia,  milk  ;  ofpw,  I  carry] 
(lactiferous)  [/«c,  milk  ;  fero,  I  bear],  1070 
Ductus  [dnco,  I  lead]  arteriosus  (Botalli),  940 

cochlearis,  883 

communis  choledochus  l,\o/J/,  bile  ;  <^t:xo/mi, 
I  receive],  984 

endolymphaticus,  36 

perilymphaticus,  37.  73 

venosus,  635,  978  ;  fi.ssure  of,  979 
Duodenal  fold,  evolution  of,  1003 
Duodeno-jejunalis,  ibssa,  966 
Duodenum  [ditodeni,  twelve],  the,  964 
Dura  [hard]  mater  [mother],  the,  of  brain,  672 

of  spinal  cord,  731  ;  differences  between  it 
and  cranial  dura  mater,  732 


Ear,  the  external,  870  ;  ligaments  and  muscles 
of,  870  ;  vessels  and  nerves  of,  871 

internal,  879 

middle,  873.     S'ee "Tympanum 

veins  of  the,  625 
Ear-shaped  cartilage  of  sacroiliac  joint,  202 
Ehrenritter,  ganglion  of,  768 


IXDEX 


12:33 


Eighth  cranial  (auditory)  nerve,  7U.")  ;  roots,  766  ; 

brandies,  7(i7 
Kjaculatory  chut,  1029  ;  orifice  of,  1033 
Elastic  fibres  (yellow)  of  trachea,  914 
lamina  (posterior)  of  cornea.  H46 
Elasticity  of  cranium,  results  of,  UK! 
Ell)0\v,  arrangement  of  superficial  veins  in  front 
of,  11. ".7 
hollow  in  front  of,  11,57 
sur<;ical  anatomy  of,  1155 
Elbow-joint,  ana.stomoses  round,  11.57 

arterial   and   nerve  supply  and  move 

ments  of,  229 
lifiaments  of,  227 
Eleidin,  1075 
f]leventh  cranial  (spinal  acceasory)  nerve,  819 

rib,  102 
Eminence,  articular,  35,  70 
canine,  55 
frontal,  47,  73 
na.sjil,  47 
olivary,  30.  83 
parietal,  44 
Eminences,  h3'pothenar,  muscles  of,  343 
surgical  anatomy  of,  1199 
thenar,  muscles  of.  339 

surgical  anatomy  of,  1199 
Eminentia  articularis,  35,  70 
collateralis.  690,  697 
teres,  719 
Emissary  veins  of  cranium,  672 

of  scalp,  1116 
Emulgeut  {^cmulgeo,  I  drain  out]  or  renal  arteries, 
560 
veins,  631 
Enarthrodia  [f  i',  in  ;  apOpov^  a  joint],  definition 

and  examples  of,  177 
Enceplialon  [Jr,  in  ;  /ceoa//;,  the  head],  the,  679  ; 

grey  and  white  matter  of,  679 
End-bulbs  of  Kranse,  1076 
Endocardium  [I'wW,  within;  Kapdia,  the  heart], 

the,  92-S 
Eiiencei)hal()n  [em,  upon  ;  KEipa/.i/^  the  head],  the, 

670,  713 
Ependyina  [f^'  ;  iv6vfia,  clothing],  the,  670 
Epicerebral  spaces,  678 

Epicranial   [fV/,  upon  ;  Kpaviov,  the  skull]  apo- 
neurosis, 427 
Epiderm,  1075 
Epididymal  artery,  561 

Epididvmis   {^~',    upon  ;  ^idvuoc,   the   testicle], 
the,  1024 
tube  of,  1027 
Epigastric   [*-',    upon  ;    }(wrr/p,    the    .stomach] 
artery,  deep.  577  ;  variations,  578 
superficial,  583 
superior,  518 
lymphatic  glands,  657 
region,  1208 

vein,  deep,  647  ;  superficial.  631,  644 
Epiglottis  [f~',  upon  ;  y/iJiTig^  the  glottis],  the, 

905  ;  cushion  of  the,  905 
Epiotic  [f  rr/,  npon  ;  o!r^  gen.  «J"of,  the  ear]  centre 

of  ossification,  43 
Epiphyses  [i-(,  uixm  ;  <pio),  I  grow],  rules  con- 
cerning, 2 
unossified  (costal  cartilages),  102 
Epiphysial  cartilages,  1 

linos,  1 
Epiphysis  cerebri  f  pineal  body),  705 
Epiploic   [t-i,   upon  ;   rr/fw.    I  sail]    (ascending 
omental  I  artery  of  right  gastro-epiploic, 
557 


Epiploic   (descending  omental)    artery    of   left 

gastro-epipioic,  558 
Epipteric  [tm,   upon  ;  -rtpvi,   a   wing]   os.sicle, 

71,  1209 
Epispinal  spaces,  (i78 
Epistcrnal  l)ones,  105 

Epithelium  [fT/,  upon  ;  Or/'/.//^  papilla],  germinal, 
10.-.5 
sulxapsular.  8.')0 
Epitrocbleur  gland.  1157 
Kjiilroclil(o-nnc'iiitii>i  muscle,  458 
Ei)oiiplioron,  1214 
Epovarium,  1048,  1214 
Erpiator  of  eyeball,  h43 

Erector  [eriijrrc,   to  raise]    penis  (ischio-caver- 
nosusi  muscle.  1034 
spina-  muscle,  415 
Ethmoid   [//''/^«f,  a  sieve  ;  lUSn^,  like  :  from  the 
perforations  in  its  horizontal  plate]  lx)ne, 
49  ;  o.ssification,  50 
at  birth,  94 
Ethmoidal  arteries,  anterior  and  posterior,  532 
canals,  46.  49,  78,  82,  97 
cells,  50,  80 
fissure,  49,  82 
foramina.  49,  82 
grooves,  49 
notch,  46 

spine  of  sphenoid,  30,  83 
veins,  anterior  and  posterior,  626,  934 
Ethmo-laclirymal  suture,  78 
Ethmo-sphenoidal  suture,  82 
Ethmo-turbinals,  50 
Ethmo- vomerine  region  of  chondral  skull,  89 

plate  (at  birth),  96 
Eustachian  arteries  of  ptery go- palatine,  496 
of  Vidian,  496 
tnbe,  876 

valve,  929  ;  in  foetus,  977 
Evolution  of  jteritoneum,  991 
Ex  occipital  Itones,  24  ;  at  birth,  92 
Excretory  dnct  of  kidney,  1051 
Extensor    [(.riouh),     I    stretch    out]     annulitris 
mu.scle,  45S 
brevis  digitorum  muscle,  .391 
maniis  muscle,  458 
pollicis  muscle,  330 
carpi  radialis  brevior  muscle.  323 
iiccesMoriiis  muscle,  458 
longior  muscle,  323  ;  nerve  to,  795 
ulnaris  muscle,  327 
cocci/gis  muscle,  458 
communis  digitorum  muscle,  324 
indicis  muscle,  332 
longus  dinitorum  muscle,  389 

pollicis  muscle,  331 
meilii  dii/ili  muscle.  459 
minimi  digiti  mu.scle.  .326 
ossis  metacarpi  jwllicis  muscle.  .329 

uutnldrsi  hullnrin  mns<le,  45S 
primi  iiiternodii  hdlliiria  loiigux  muscle,  458 
propnua  hallucis   [proprius,   l>elonging  to; 
hiillitj;  great  toe]  muscle,  387 
Exterior  of  the  skull,  (>9 
Extraspiual  veins,  629 

Extrinsic    [t.rlriiiKfcH:<,     outward]     muscles    of 
auricle,  H71 
of  larvnx,  945 
of  toiigne,  888 
Eye,  the,  839 

Eyeball,  the,  examination  of,  843 
equator  of,  843 
general  surface  view  of,  839 


1234 


LXDEX 


Eyelids,  the,  902 

blood-vessels  of,  865 
glands  of,  865 
lymphatics  of,  865 
uerves  of,  865 
surgical  anatomy  of,  1092 

Face,  cutaneous  uerves  of,  819 

surgical  anatomy  of,  1091 
Facet  Ifiicettt',  a  little  face],  patellar,  of  femoral 
condyle,  151 
pyriform,  of  astragalus,  159 
triangular,  of  astragalus,  159 
Facial  artery,  485 

transverse,  491 
bones,  24 

lymphatic  glands,  deep,  653 
vessels,  superficial,  649 
nerve,  761 

segment  of  chondro-cranium,  90,  890 
skeleton  at  birth.  92 
vein,  common,  61 15 

communicating,  614 
transverse,  615  ;  variations,  614 
Falciform  [_fiilx,  a  sickle]  ligament  of  fascia  lata 
of  thigh,  345 
of  Burns,  1166 
lobe  of  cerebrum.  683,  691 
process  of  temporal  bone,  36 
Fallopian  [from  Fallopius,  the  anatomist]  artery, 
562 
canal,  37,  41,  876 

tube,  1051  ;  position  of,   1051  ;  lymphatics 
of,  662,  1054  ;  structure  of,  1052  ;  vessels 
and  nerves  of,  1054 
False  ligaments  of  bladder,  1018 
ribs,  98 

vocal  cords,  911 
Falx  [a  sickle  ;  from  its  shape]  cerebelli,  675 

cerebri,  674 
Fascia  [a  bundle],  anal,  1063 
axillary,  294 
clavi- pectoral,  294 
of  CoUes,  1065 

cremasteric  (or  middle  spermatic),  1024 
cribriform,  346 
dentate  (dentate  convolution  of  cerebrum), 

691,  69H 
endothoracic,  399 
of  the  forearm,  deep.  311 
of  groin,  superficial,  1165 
of  the  hand,  dor,sal,  332 

palmar,  333  :  surgical  anatomv 
of,  1206 
hypothenar,  333 
thenar.  333 
of  head  and  neck,  deep  (cervical),  444 

superficial,  425 
iliac,  .348 

of  fascia  lata  of  thigh.  11.38 
iufundibuliform  (propria),  407,  411.  1024 
intercolumnar,  406,  1023,  1131 
ischio-rectal,  1102 
of  the  leg,  deep,  367 
lumbar,  408,  1146 
masseteric,  440 
of   muscles   from   scapula  to   upi)er    limb, 

superficial  and  deep.  300 
of  muscles  passing  from  trunk  to  upper  ex- 
tremity, anterior  division  (superficial), 
293 
posterior  division  (superficial  and  deep), 
288 


Fascia,  obturator.  1061 
orbital,  858 

palmar,  333  ;  surgical  anatomy  of,  1169 
palpebral,  858 
parotid,  440 
pectoral,  294 
pelvic,  1060 

surgical  anatomy  of,  1129 
perinatal,  1065 
plantar,  377 
prevertebral,  444,  1106 
propria  (infundibnliform),  407,  411,  1024 
pubic,  of  fascia  lata  of  thigh,  1119 
recto-vesical,  101b,  1063 
spermaric,  external,  405,  1023,  1131 

internal  and  middle,  1024 
temporal,  440 
of  the  thigh,  deep  (fascia  lata),  344,  1116 

superficial,  344 
tibial,  deep,  373 
transversalis,  411 

triangular,  of  external  oblique,  404,  1132 
of  the  upper  arm,  deep,  306 
Fascise  of  orbit,  857 

pelvic,  1060 
Fascial  sheath  of  penis,  1032 
Fasciculus  (dim.  of  fascia)  arcuatus,  786 
garland-like,  of  cerebellum,  717 
longitudinalis,  inferior,  786 
oblique,  of  pons,  720 
perpendicular  occipital.  787 
teres  of  fourth  ventricle,  719 
uncinatus,  786 
Fa.sciola  [dim.  of  fascia'}  cinerea  [grey],  698 
Fauces  [fax-i;  the  throat],  the,  944 
isthmus  of,  944 
pillars  of,  944 
Female  bladder,  the,  1019 

genitals,  external,   1038  :  surgical  anatomv 

of,  1129 
mamma,  1069 

development  and  abnormalities,  1072 
variations  according  to  age,  &c.,  1071 
vessels,  nerves,  and  lymphatics,  1071 
pelvis,  146 
perina^um,  1068 
urethra,  1041 
Femoral  [femur,  the  thigh]  artery,  579 
branches  and  variations,  581 
line  of,  1175 

surgical  anatomy  of,  1176 
deep  (prolunda),  583 
canal,  1139 
condyles  and  tuberosities,  surgical  anatomv 

of,  1183 
hernia,  parts  concerned  in,  1137 
course  of,  1139 
covering  of,  1140 
ligament,  1138 
lymphatic  glands,  deep,  668 

superficial,  667 
ring,  1139 

position  of  vessels  around,  1139 
sheath.  1139 
vein,  646 

common,  647 
variations,  ()47 
deep  (profunda).  647 
Femur  [the  thigh],  the,  147 
blood  -su  ppl  y ,  1 52 
ossification  of,  152 
Fenestra  [a  window]  ovalis,  39,  875,  879 
rotunda.  39,  875 


LXDEX 


1235 


Ferrein,  pj- ram  ids  of,  1011 
Fibres  of  medulla,  arcilbrm,  7'.':.' 
of  cereljellum,  710 
of  cortex  eerebri,  iutrabemispheric,  long  aud 

short,  786 
of  optic  chiasma,  746 
of  pons  Varolii,  GUI,  716 
of  trachea  (yellow  elastic),  914 
Fibro  cartilage,  cotyloid,  of  hip,  249 
of  knee,  external,  257 
internal,  "ioS 
interarticular,    of  acromio-clavicuhir  joint, 
219 
of  sterno-davicular  joint,  218 
of  temporo-mandihular  articulation,  180 
intervertebral,  190 
pul)ic,  207 

triangular,  of  wrist,  2U2 
Fibrous  coat  of  eyeball,  845 
layer  of  pericardium,  925 
membrane  of  trachea,  913 
Fibula  [a  clasp],  the,  158 

development  of,  l.')9 
Fifth  (trigeminal)  cranial  nerve,  749 
divisions  of,  ophthalmic,  750 

mandibular  (inferior  maxillary),  756 
maxillary  (sup.  maxillary),  753 
foramen  for,  83 
Figures,  stellate,  of  lens,  850 
Filiform  [filttm,  a  thread],  or  conical  papillne  of 

tongue,  885 
Fillet  of  crus  cerebri,  710.  782 

tract  of  the.  782 
Filuni  [a  thread]  termiuale  of  pia  mater,  734, 

1211 
Fimbria  [a  fringe],  or  corpus  fimbriatum,  697, 
701 
ovarica.  1051 
Fimbriae  [  fimbria,  a  fringe]  of  Fallopian  tubes, 

1051 
First  cervical   nerve,  anterior  primary  division 
of,  782 
posterior  primary  division  of,  780 
cranial  or  olfactory  nerve,  745 
rib,  100 
Fissure  [Jijido,  I  cleave]  of  auricle,  Sautorini's, 
871 
of  bone,  auricular,  38,  73 
ethmoidal,  49,  82 
Glaserian,  35,  73,  97 
maxillary,  56 

ptervgo-maxillary,  70,  78,  97 
sphenoidal,  31,  78,  83,  97 
spheno-malar,  78 
spheno-maxillary,  70,  78,  97 
of  cerebellum,  great  horizontal,  714 
of  cerebrum,  calcarine,  689 
caliosal,  690 
calloso-raarginal,  689 
collateral,  688,  690 
dentate,  or  hippocampal,  690 
frontal,  inferior  and  superior,  684 
great  longitudinal,  681 

transverse,  681 
hippocampal,  or  dentate,  690 
interlobar,  681 
intraparietal,  686 
occipital,  inferior,  middle,  superior,  aud 

transverse,  6^'7 
parallel,  68^^ 
parieto-occipital,  external  and  interual, 

681,  689 
perpendicular,  internal,  689 


Fissure  of  Kolando,  683,  1089 
getiua  of,  683 
origin  of,  6h;{ 
of  Sylvius,  682,  1089 
temiMtral,  iiil'erior  and  middle,  687 
tri radiate,  6h5 
genital,  female,  1068 
of  liver,  of  ductus  venosus,  979 
longitudinal,  977,  979 
transverM',  or  }M)rtal.  979 
umbilical,  977,  979 
for  vena  cava,  979 
of  medulla  oblongata,  anterior  and  posterior, 

721 
prostatic,  1021 

ol  si)inal  cord,  an.ero-lateral.  postero  lateral, 
and  longitudinal,  anterior  and  posterior, 
734 
Flexor  [jlcctere,  to  bend]  acces.sorius  digitoruni 
pedis  muscle,  3H1 
(icrcssoriiis  loiif/iis  muscle.  459 
brevis  digitorum  jjedis,  or  flexor  perforatus 
muscle,  379  • 

liallucis    [li<illu.r,    great    toe]    muscle, 

3S2 
minimi  (manus)  digiti  muscle,  343 

pedis  digiti  muscle,  384 
pollicis  [})olle.r,  thumb]  muscle,  311 
pedis,    or     flexor    brevis    hallucis, 
muscle,  382 
carpi  radialis  muscle,  313  ;  nerve  to,  793 
lirrcis  vcl  profmuhis  muscle,  459 
ulnaris  mu.scle,  315;  nerve  to,  794 
longus  digitorum  muscle,  374 
hallucis  muscle.  375 
jKillicis  muscle.  320 
ossis  metacarpi  pollicis  mus<le,  341 
perforatus  muscle,  or  flexor  brevis  digitorum 

pedis.  :579 
profundus  digitorum  mu.scle,  318  :  nerve  to, 

794 
sublimis  digitorum  muscle,  315:  nerve  to, 

791 
tendons  of  hand,  sheaths  of  (thecaj).  3:1.3 
Floating  ribs.  98 
Floccular  fos-iia,  37 
Flocculus  [dim.  of  foetus,  a  lock  of  wool],  of 

cerebellum,  715 
Floor  of  descending  cornu  of  lateral  ventricle, 
structures  in,  697 
of  fourth  ventricle,  structures  in.  719 
of  third  ventricle,  structures  in,  705 
Fluid,  cerebro-spinal,  678 
Foetal  circulation.  939 

heart,  jteculiarities  of,  9.39 

position  and  weight.  939 
skull,  general  cliaracters  ol,  90 
Fold,  arvteno-epiglottidean,  905 
of  Douglas.  410 

ducMlenal,  966  ;  evolution  of.  1003 
glosso-epiglottidean,  8s4,  905 
pali)ebral,  superior  and  interior.  840 
pharvngo-epiglottidean,  905 
semilunar,  of  conjunctiva.  ^<43 
vestigial,  of  ]>ericardium,  926 
Folds  or  creiises  of  palm,  surgical  anaiomv  oi, 

1165 
Folia  of  cerelwllum,  711 
Folian  or  slender  prmess  of  malleus.  <J7 
Folium  [a  leaf]  cacuminis  [cactiiiHii.  the  sum- 
mit] of  cerebellum.  713 
Folli<les  [dim.  of  j'ollis,  a  bag].  Gr.aalian.  lOiK) 
Meibomian.  846 


123G 


INDEX 


FON 

Foutanelles  [dim.  of  funn,  a  loiiutain],  anterior 
ami  posterior,  !»lt 
anterior  and  jKisterior  lateral,  !)1 
Foot,  the  l)ones  ot  the,  lo9 

arehes  of,  V20-2  ;  kevstone  of,   V202  ;  pillare 

of,  V202 
hnrsic  of,  1199 

dorsal  artery  of,  surjiieal  anatomy  of,  1200 
levels  of  joints  of,  119s 
surgical  anatomy  of,  1198 
synovial  membranes  of,  1199 
veins  of,  646 
Foramen    [foro,    I   pierce]    for    aorta   (in    dia- 
phragm). 400 
anditory  (internal  auditory  meatus),  96 
ca-cum,'  46,  49,  82 
anterius,  706 

posterius  (of  Vicq  d'Azyr),  721 
of  tongue,  884 
centrale  cochleare,  37 
commune  anterius,  670,  697 
condyloid,  anterior,  26,  73,  83,  96 

•  posterior,  28,  73 
oosto  transverse,  of  atlas,  9 
of  cervical  vertebrae,  7 
of   seventh    cervical   (vertebra    promi- 

uens),  9 
of  typical  vertebia.  7 
dental,  inferior  (mandibular),  63,  97 
ethmoidal,  49,  82 
explanation  of  term,  5 
for  tifth  cranial  nerve,  83 
infra-orbital,  55.  97 

for  internal  carotid  artery  (occasional),  83 
jugular,  73,  86,  96 
lacerum  medium,  73,  83 
for  lesser  petrosal  nerve,  37,  83 
magnum,  26,  73,  86,  96 
of  Majendie,  718 

mandibular  (inferior  dental),  63,  97 
mastoid,  73,  86 
mental,  62 
obturator,  138,  143 
for  oesophagus  (in  diaphragm),  400 
optic,  30,  76,  83,  96 
ovale,  32,  70,  83,  96 

of  foetal  heart,  940,  1213 
valve  of,  940,  1213 
palatine  accessory,  anterior  and  external,  72 
parietal,  49 

petro-sphenoidal,  36,  83,  96 
rotundum,  32,  70,  83,  96 
sacro-sciatic,  great  and  small,  202 
sclertu,  845 
singulare,  36 
spheno-malar,  71,  78,  97 
spheno-palatine.  59,  70,  80,  97 
sphenotic,  73,  83 
spinosum,  32,  71,  83 
stylo-mastoid,  37,  73,  97 
supra-orbital,  47 
suprasca])ular,  113 
supratrochlear,  120 
for  third  cranial  nerve,  83 
thyroid  ["'/'",  an  opening]  (obturator),  138, 

143 
trigeminal,  36.  96 

for  vena  cava  (inferior  in  diaphragm),  400 
Vcsalii,  32,  h:'. 
of  Wiuslow,  95.') 
Foramina  of  skull,  ](rimary  nerve  foramina,  96 
secondary  n.  foramina.  96 
transmitting  brs.  of  facial  u.,  97 


FOS 

Foramina  of  skull,  transmitting  branches  of  fifth 
nerve,  9(! 

of  Key  and  Ketzius,  709 

papillaria,  1010 

sacral,  anterior  and  posterior,  15 

Scarpa's,  57,  72,  97 

spinal,  7 

Stenson's,  72 

Thehesii,  929,  £33 
Forceps,  major,  of  corpus  callosum,  689,  694 

minor,  689,  694 
Forearm,  cutaneous  nerves  of,  IKJ.'? 

muscular  prominences  of,  1161 

surgical  anatomy  of,  1159 
Formatio  reticularis,  721,  724,  737         ' 
Fornix  [an  arch],  the,  701 

conjunctival,  840 

vagin;e,  1042 
Fossa  [a  ditch  or  depression] — 

adipose,  1070 

of  antihelix,  871 

of  base  of  skull,  anterior,  82 
middle,  83 
posterior,  86 

canine,  55 

condyloid,  posterior,  28 

coronoid,  120 

digastric,  6:5 

digital,  of  tunica  vaginalis,  1024 

duodeuo-jejunalis,  966 

floccular,  37 

of  gall  bladder,  977 

glenoid,  35,  73 

of  helix,  871 

ileo-csecal,  970 

iliac,  139 

incisive,  of  mandible,  62 
of  maxilla,  55 

iufraspinous,  111 

innominata,  of  larynx,  911 

intersigmoid,  974 

ischio-rectal,  1074,  1127 
contents  of,  1075 

jugular,  37,  73 

lachrymal,  47,  77 
■     malleolar,  of  libnla,  158 

nasal,  79 

navicularis,  of  urethra,  1037,  1130 

olecranon,  120 

ovalis,  of  auricular  septum,  930 

palatine,  anterior,  57 

pituitary,  30 

pterygoid,  33,  73 

Rosenmliller's.  952 

scaphoid,  33,  73 
of  auricle,  871 

sigmoid,  greater,  122 
lesser,  123 

spheno-maxillary,  70 

sublingual,  ()3 

submaxillar}'.  63 

subscapular,  111 

supraspinous,  111 

supratrochlear,  47 

Sylvii,  682.  688 

temporal,  70 

triangular,  of  auricle,  871 

trochanteric,  147 
vermiform,  26,  86 

zygomatic,  70 
Fosste,  adipose,  of  female  breast,  1069 

on  posterior  surface  of  abdominal  parietes, 
1136 


i 


INDEX 


1237 


Fossula  [dim.  oi  fossn']  coclilearis,  36 

vestil)nlaris,  '^G 
Fonrcliette  [a  fork]  of  vagina.  10H9.  11:50 
Fourth  or  troclilear  cranial  nerve,  863 

saeral  nerve,  80H 
Fovea  [a  pit]  centralis  of  retina,  843,  848 

IicMiit'lliptica,  41,  875 

liciuisplicrica,  41,  875 

inferior  and  superior,  of  fourth  ventricle,  719 
Fra'nuin  [a  curl*  or  bridle],  artery  of,  485 

epiglottulis,  884 

lingnie,  884,  1095 

pneputii,  1032 
Frennlnni  [dim.  of //vphhhi]  veil,  710 
Frontal  [//o?;,"*,  frontin,  forehead]  artery,  502 
of  anterior  ethmoidal,  501 

bone,  46  ;  ossification  of,  48 
at  birth,  94 

convolutions  of  cerebrum,  684 

eminence,  47,  73 

fissures  of  cerebrum,  684 

lobe  of  cerebrum,  684 

uerve,  752,  864 

operculum,  683 

process  of  malar  bone,  61 

sinu.ses,  47,  1082;  developmeut  of,  47 

vein,  649 

of  diploe,  618 
Frontalis  muscle,  428 
Frouto-ethmoidal  tells,  50 

suture,  83 
Fronto-nasal  plate  of  chondro  cranium,  89 
Frouto-parietal  vein  of  diploe,  618 

operculum,  682 
Fronto-sphenoidal  vein  of  diploe,  618 
Frontosciuamosal  suture,  38,  71 
Fundus  [the  bottom]  of  uterus,  1044 
Fungiform    [fuuf/us,    a   mushroom]    papillae   of 

tongue,  885 
Funicular  [dim.  of  funis,  a  cord]  artery,  1050, 

1054 
Funiculus  [dim.  of /m?i!S,   a  cord],   anterior,  of 
medulla.  722 

cu  neat  us.  722 

gracilis,  722 

sol  i  tar i  us,  766 
Furrow,  median,  of  back,  1142 

sciuamo-mastoid,  38 
Furrowed  baud,  715 


Galactophorous  [yd/f,  milk  ;  <pfpo),  I  carry] 

or  lactiferovis  ducts,  1070 
Galen,  vein  of,  cardiac,  611,  937 

cerebral,  624 
Gall  bladder,  the,  983 

fo.ssa  of,  977 

structure  of,  985 

topography  of,  1117 
Ganglia  [;rt;7A/or,  a  swelling],  basal  cranial,  699 

cranial,  of  sympathetic,  827 

of  glossopharyngeal  nerve,  768 

lumbar,  833 

mesenterica,  836 

of  pneuraogastric  nerve,  770 

prostatica.  837 

sacral,  833 

semilunar,  835 

of  spinal  nerves,  776 

of  sympathetic  nerves,  826 

thoracic,  830 
Gangliated  cords  of  sympathetic,  826 
cervical  portion,  826 


GEN 

Gangliated  cord,  cranial  portion,  826 
lumbar  portion,  826 
.■^ac  lal  portion,  83.3 
thoracic  portion,  830 
Ganglion  [j"}7^""',  an  enlargement] — 
Andei-sch's,  768 
Arnold's,  or  otic,  760 
Hochdalek's,  754 
cervical,  inferior,  830 
middle,  830 
superior,  828 
ciliary,  or  lenticular,  7.52,  865 
diaphragmaticum,  786,  835 
Ehrenritter's,  768 

Gas.scrian,  37,  750  ;  depression  for,  83 
geniculate,  762 
inipar  [unccpial],  833 
int(!rcaroticum,  478 
.jugular,  768 
lenticular,  752,  865 
Meckel's,  or  nasal,  755 
()])lithalniic,  or  lenticular,  752,  865 
otic,  760 
petrous,  7''8 
of  pneumogasfric  root,  770 

trunk,  770 
spheno-palatine,  or  Meckel's,  755 
stelhitum,  832 
sublingual,  7()0 

submandibular,  or  subma.\illarv,  7(»0 
Valentin's,  754 
of  Wrisberg,  cardiac,  039 
Ganglionic  artery,  of  anterior  cerebral,  503 
of  middle  cerebral,  503 
of  posterior  cerebral,  512 
veins,  623 
Gartner,  duct  of,  1043,  1214 
Gasserian  artery,  of  middle  meningeal,  493 
branches  of  carotid  plexus,  83U 
ganglion,  37,  750 
Gastric   [iaa-r/p,   the  stomach]   area  of  anterior 
surface  of  kidney,  1009 
artery  (coronary),  556  ;  variations,  556 
of  gastro-epiploic,  left,  55'^ 
right,  557 
lymphatic  glands,  inferior,  (i64 
superior,  6(i3 
lymphatics,  inferior  and  superior,  663 
nerve  ple.xus,  835 
vein,  636 
Gastrocnemius   [■}na-r/ft,    the   belly;   ni'ifuj^    the 

calf]  muscle,  369;  variations,  371 
Gastro-dnodenal   [)'nff"'//»,  the  belly  ;  duodtnum'] 

artery,  557 
Gastro-epiploic  [)0(Tr7//),  the  belly  ;  fT/T/ooi,  the 
omentum]  artery,  left.  558 
right,  557 
lymphatic  glands,  664 
nerve  jdexu.s,  left,  835  ;  right,  835 
vein,  left.  637  :  right,  637 
Gastro-heiiatic,  or  le.^ser  omentum,  958 

evolution  of,  1000 
Ga.stro-phrenic  [0/>'/i',  diaphragm]  liganif  nt,  958 
Gastrosplenic  omentum.  9.58 

evolution  o\\  1003 
Gemellus  [a  twin]  inferior  muscle,  356  ;  varia- 
tions, 3.57 
superior  mn.'scle,  3.57  ;  variations.  3.57 
Genial  [yivnor,  the  chin]  tubercles  62 
Geniculate  [dim.  of  grnn,  a  knee]  ganglion,  762 
Genio-hyo-glossus  [;fi'f<or,  the  chin  :  iV>f»'/,c.  the 
hyoid  Iwne  ;  y^ijoon,  the  tongne]  musc-le, 
452 ;  nerve  to,  775 


1238 


INDEX 


Geuio-hyoid  muscle,  451  ;  nerve  to,  775 
Geuital  bruncli  ol'  geuito-crural  nerve,  804 
conl,  1055 

fissure  in  female,  10<58 
gland,  1055 
Genitals,  external,  development  of,  1057 
female,  10:58,  1129 
male,  1021 
Geuito-crural  nerve,  804 

Genitourinary  organs,  development  of,  1055 
Genu  of  corpus  callosum,  692 
of  inner  capsule,  701 
nervi  facialis,  761 
Genua   [^genu,  a  knee]  of   fissure  of   Rolando, 

683 
Germinal  epithelium,  1055 
Gimberuat's  ligament,  404,  1188 
Gingival  [(/higivie,  the  gums]  arteries  of  posterior 

dental.  496 
Ginglymo-arthrodial  joints,  178 
Gingrynms  [}'<}; /■i',""?,  a  door  hinge],  177 
Giraldes,  organ  of,  1028,  1215 
Girdle,  pectoral,  morphology  of,  115 
Glabella   [dim.  of  (/laber,  fern,  glabra,   smooth], 

47,  81,  767 
Gladiolus  [dim.  of  ghidiut^,  a  sword]  sterni,  104 
Gland,  carotid,  478 
genital,  1055 
lachrymal,  867 
mammary,  of  female,  1069 

development  and  abnormalities,  1072 
variations  according  to  age,  &c.,  1071 
vessels,  nerves,  and  lymphatics,  1071 
of  male,  1109 
parotid,  946 
sublingual,  949,  1095 
submaxillary,  948 
thymus,  918 
thvroid,  915 
Glands' of  Bartholin,  1040,  1070 
of  Bruuner,  969 
ceruminous,  1077 
ciliarv,  1077 
of  Cowper,  1069 
of  eyelids,  866 

Ivmphatic.  see  Lymphatic  glands 
of  Nuhn,  886 
salivary,  the,  946 
sebaceous.  1077 
of  soft  palate,  946 
solitary,  of  intestine,  968 
sudoriparous,  1077 
Glandular  (or  submaxillary)  artery,  487 

vein,  614 
Glans  [an  acorn]  clitoridis,  1040 

penis,  1031,  1033 
Gla.serian  artery,  493 
fissure,  35,'  73,  97 
Gleno-humeral  bands,  224 

ligament,  224  ;   origin  from  subclavius,  281 
Glenoid  [y'Ar/r>/,  a  shallow  socket ;    fifSof,    like] 
cavitj'  of  scapula,  113 
fos.sa,  35,  73 
fossic  of  finger  phalanges,  137 

of  toe  phalanges,  172 
ligament  of  interphalangeal  joints  of  foot, 
280 
of  interphalangeal  joints  of  hand,  245 
of  meta(;arjio-iihalangeal  joints,  243 
of  shoulder-joint,  225 
lobe  of  parotid  gland,  947 
Glissou's  capsule,  983 
Globus  [a  ball]  major  et  minor,  1024 


OKO 

Globus  pallidus,  699 

Glosso-epiglottideau  [y/ioaaa,   the  tongue  ;   f""*, 
upon  ;  yXuT-ig,  folds],  864,  905 
pouch,  884 
Glossopharyngeal  [}/wfT(7n,  the  tongue;  (t>dpv)$, 
pharynx]  or  ninth  cranial  nerve,  767 
branches,  768  ;  roots,  767 
communicating  branch  from  superior  cervi- 
cal ganglion  to,  768,  828 
from  vagus  to,  768,  781 
Glottis  [}>.w7r/f,  the  mouthpiece  of  a  wind  in.stru- 

ment],  the,  909.     See  Larynx 
Gluteal  [}/oi'r(ir,  the  buttock]  artery,  569 
topographj'^  of,  1181 
inferior,  572 
lymphatics,  660,  667 
nerves,  inferior,  810 
superior,  810 
ridges  of  femur,  147 

of  ilium,  139 
veins,  638 
Gluteus  [y'/.ovTo^,  the  buttock]  maximus muscle, 
351  ;  surgical  anatomy  of,  1180 
medius  muscle,  353 
minimus  muscle,  354 
quarius  muscle,  459 
GoU's  column,  741 
Gouion,  the,  81 

Gower's  tract  of  spinal  cord,  781 
Graafian  follicles,  1053 
Gracilis  {^gracilis,  slender]  muscle,  362 
Great  auricular  nerve,  784  ;  topographj"^  of,  1103 
cardiac  vein,  937 
deep  petrosal  nerve,  755,  828 
horizontal  fissure  of  cerebellum,  714 
longitudinal  fissure  of  cerebrum,  681 
occipital  nerve,  779 
omentum,  958  ;    evolution  of,  1000  ;   length 

of,  958 
(anterior)  palatine  nerve,  756 
palmar  bursa,  317 
prevertebral  plexuses,  833 
(posterior)  sacro-sciatic  ligament,  202 
origin  from  biceps  femoris,  281 
falciform  process  of,  202 
sciatic  nerve,  814  ;  topograph^'  of,  1180 
splanchnic  nerve,  832 
superficial  petrosal  nerve,  755 
toe,  incisions  for  amputation  of  1199 
transverse  fissure  of  cerebrum,  682,  702 
Greater  anterior  gastric  artery,  556 
cornua  of  hyoid,  66 

centres  of  ossification  for,  95 
sac  of  peritoneum,  955 
sciatic  notch,  140 
sigmoid  cavity  of  ulna,  122 
trochanter,  147 
tubero.sity  of  humerus,  115 
wing  of  sphenoid,  31 
Grey  commissure  of  cerebrum,  704 
matter  of  coid,  737 

of  encephalon,  679 
in  interior  of  cerebellum,  716 
in  medulla,  arrangement  of,  724 
of  Sylvian  aqueduct,  710 
tubercle  of  Rolando,  723 
Groin,  superficial  fascia  of,  1119 
Groove,  antcro-lateral,  of  spinal  cord,  73.'/ 
anriculoventricuhir,  927 
bicipital,   IKi,  1150 
cavernous,  31 
costo- vertebral,  108 
digastric,  37   73 


INDEX 


1239 


GEO 

Groove,  ethmoidal,  49 

lurni-orbital,  55 

iuterveutricular,  927 

lachrymal,  78 

lateral,  of  cms  cerebri,  711 

for  middle  meuinyeal  artery,  83 

musculo-spiral,  119 

mylo-hyoid,  63 

naso-palatiiie,  54 

obturator,  140 

occipital,  37,  73 

oeulo  motor,  of  crus cerebri,  711 

optic,  30,  83 

peroneal,  of  cuboid  bone,  165 

postero-lateral,  of  spinal  cord,  735 

pterygo-palatiue,  33 

sesamoid,  of  fust  metacarpal,  134 
of  first  metatarsal,  170 

subcostal,  99 

for  superior  longitudinal  sinus,  26,  82 

uncinate,  of  uncinate  gyrus,  691 
Groups  of  motor  cells  in  spinal  cord,  737 
Gubernacular  canals,  72 
Gubernaeulum  [a  rudder]  testis,  the,  1025 

development  of,  1057 
Gudden's  commissure,  746 
Guerin,  sinus  of,  1038 
Gums,  the,  943 

Gustatory  [f/uslo,  I  taste]  artery,  495 
Guthrie,  muscle  of,  1068 
Gyrl  [>t'pof,  a  riug],  annectant,  687 

operti,  688 
Gyrus,  angular,  685 

foruicatus,  or  gyrus  cinguli,  690 

rectus  (straight  convolution),  684 

uncinate,  683 


ILemorrhoidaT.   [aiua,   blood  ;    /'fw,  I  flow] — 
arteries,  inferior  (external),  574 
middle,  570 
superior,  562 

(rectal)  of  middle  sacral,  564 
nerve,  inferior,  813 
plexus,  venous.  639 

nerve,  middle,  837 
veins,  639 
Hair-follicle,  1078 
Hairiness.  1215 
Hairs,  1077 

Half-vertebra  (occasional),  12 
•Hamular  [hamus,  a  hook]  process.  33,  72 

surgical  anatomy  of,  1096 
Hamulus  [dim.  of  hamus,  a  hook],  33,  72 
of  cochlea,  42,  880 
of  lachrymal  bone,  53 
Hand,  the,  nerve-supply  to  integument  of  dor- 
sum of,  747 
skeleton  of,  128 
surgical  anatomy  of.  1163 
of  back  of  hand,  1174 
of  fasciiie  and  sheaths  of,  1169 
skin  folds  or  creases  of,  1164 
synovial    membranes    of    tendons     of, 
1171 
of  joints  of,  1173 
thenar  and   hypotheuar   tiuint  ncos  of, 
1164 
Handle  of  malleus,  67 
Hard  palate,  the,  943 

Head  and  face,  sinuses  of,  1093  ;  surgical  anatomy 
of,  1091 


Head  and  neck,  lymi)hatics  of,  648 
veins  of,  deep,  617 

sui)erticial,  611 
of  astragalus,  161 
of  caudate  nucleus,  699 
of  femur,  147 
of  fibula,  loH 
of  humerus,  1 15 
of  malleus,  67 

of  metacarpal  bone.  133  ;  first,  134 
of  metatarsal  bone,  169  ;  first,  170 
of  OS  magnum.  132 
of  pancreas,  986 
of  radius,  126 
of  ribs,  98 
of  stapes,  68 
of  tibia,  153 
of  ulna  (lower  end),  125 
Head-kidnev,  or  pronephros,  1055 
Heart,  the,  926 

cavities  of,  928 

ftetal,  peculiarities  of,  939 

lymphatics  of,  658 

openings  and  their  valves,  932 

topography  of,  935 
position  of,  926 
relation  to  chest  wall,  1113 
size  and  weight,  927 
veins  of,  610 

vessels  and  nerves.  633,  936 
Height  of  average  skull,  86 
Helicis  major  et  minor  muscles,  872 
Helicotrenia  [f^'f,  a  spiral  ;  rpf/fia,  a  hole],  the, 

881 
Helix  [f-/ti.  a  spiral],  the,  870 
Hemiazygos  vein,  608 

accessory,  608 
Hemispherai  branches  of  cerebellar  arteries,  511, 
512 
of  anterior  cerebral  artery,  503 
of  middle  cerebral,  504 
of  posterior  cerebral,  512 
Henle,  layer  of,  1078 
looped  tube  of,  1011 
accessory  lachrymal  glands  of,  866 
Hepatic  [i/TrariKO^,  of  the  liver]  artery,  556 
variations,  557 
of  epigastric,  superior,  518 
of  gastric,  556 
of  right  phrenic,  553 
canals,  983 
duct,  984 

lymphatic  glands,  665 
vessels,  664 
plexus  (nerve),  835 
veins,  633,  982 
Hernia  [fpiv^,  a  branch] — 

parts  concerned  in  femoral,  1137 
inguinal,  1131 
umbilical.  1141 
See  also  Femoral,  Inguinal,  and  Umbilical 
Hey.  ligament  of,  1138 
Hey's  amputation,  incisions  for,  1199 
Hiatus  [a  cleft]  diaphragmaticus,  1008 
Fallopii.  37,  8[i 
sacralis,  15 
Hilton,  laryngeal  muscle  of,  911 
Hilum  of  corpus dentatum,  716 
of  kidney.  1(K)5 
of  ovary,  1053 
Hind-kidnev,  1055 
Hind-limb.  "1211 
Hip  (innominate)  bone,  the,  138 


1240 


INDEX 


Hip-houe.  developnieut  ami  blood-supply  of,  144 
Hip-joint,  arterial  aud  nerve  supply  ;ind  move- 
ments of.  2'A 
ligaments  of,  ^Ut 
mustles  in  relation  to,  251 
Hii>p()iampal  tissure,  tJQO 

Hippocampus   [('-rroKau-of,   a  sea  horse]  major 
(cornu  Ammonis),  696 
minor  (calcar  avis),  (il)? 
Horizontal  fissure,  great,  of  cerebellum,  714 
ramus  of  pubes,  143 
section  of  brain,  definition  of,  761 
of  skull.  8-J 
Horner's  muscle,  867 
Huguier,  canal  of  (iter  chordae  auterius),  38,  73, 

97 
Humeral  artery  of  acromio-thoracic.  523 
Humerus  [the  shoulder],  the,  115 
ossification  of,  121 
topography  of,  1153 
Humour,  of  eye,  aqueous,  850 
vitreous,  850 
Hunter's  canal,  1178 

Hyaloid  {^in/oc,  glass  ;  flf^of,  like]  canal,  850 
Hydatid  of  Morgagni,  1027,  1215 
Hymen  [*'"'/*',  a  membrane],  the,  1043 
Hyo-epiglottideau  ligament,  905 
Hyo-epigJottideus  muscle,  459 
Hyo-glossus   [from    attachment   to   hyoid    and 
tongue,    }/ wCTffo]    muscle,  452  ;    nerve  to, 
822 
Hyoid  [!',  the  Greek  letter  ;  e/r^of,  like]  artery, 
of  lingual  [supra-hyoid],  484 
of  superior  thyroid  [infra-hvoid],  482 
bar,  90 
bone,  66 

at  birth,  95 
origin,  89 
ossification.  67 
Hypertrichosis,  1215 
Hypochondriac  region,  1208 

Hypogastric  [r-d.  under ;  jaarz/p,  the  stomach] 
artery,  569,  1135 
obliterated,  1213 
branch  of  ilio-hypogastric  nerve.  803 
plexus  (nerve),  837 
region,  1208 
Hypoglossal   [i-6,  under  ;  }?ojaan^  the  tongue] 
or  tv\-elfth  cranial  nerve,  774 
communicating  branch  to,  from  vagus.  772 
from  superior  cervical  ganglion,  828 
membrane.  888 
Hypophysis  [i'~d,    under ;    6r(T/f,    from    ^I'w,    I 

grow]  cerebri  (pituitary  body),  707 
Hypothenar   [iVd,   under  ;  divnp^    the  palm] — 
eminence,  .343  ;  surgical  anatomj'  of,  1165  ; 
fascia  of  hand,  333 


Ileocecal  fossa,  971 

valve,  971 
Ileo-colic  artery,  559 
Heum  [f.'/f(j,  I  twist],  the.  967 
Iliac   [ilia,    the   flanks]    artery  of   iliolumbar, 
567 
of  obturator,  .572 

common,    561  ;    collateral    circulation, 
.565,  1121;  topography  of,  1121  ;  varia- 
tions, 565 
external,  576  ;  collateral  circulation  and 

variations,  577,  1122 
internal,  566  ;  variations,  567 
bone,  139 


IX  F 

Iliac  branch  of  ilio  hypogastric  nerve,  803 
of  last  dorsal  nerve,  801 

crest,  139 

fascia,  348 

fossa,  139 

lymphatic  glands,  internal  and  external,  661 

notches,  139 

portion  of  fascia  lata  of  thigh,  1138 

spines,  139 

tuberosity,  139 

veins,  common,  634  ;  tributaries,  634  ;  varia- 
tions, 634 
external,  647  ;  tributary,  647 
internal,  638  ;  tributaries,  638 
Iliacus  muscle,  348  :  nerve  to,  807 

minor,  or  ilio-capsula>is  muscle,  459 
Ilio-costalis  (sacro-lumbalis)  muscle,  415 
Ilio  femoral  band,  247 
Iliohypogastiic  nerve,  802 
Ilioinguinal  nerve,  803 
Ilio  lumbar  artery,  567 

ligament,  199 

vein,  634,  638 
Ilio-pubal  ridge,  1.39,  143,  146 
Ilio- tibial  band,  345 
Ilio-trochantenc  band,  248 
Ilium  [ilia,  the  flanks],  the,  139 

development  and  blood-suppl}^  of,  144 
Impressio  colica,  978 

duodenalis,  978 

gastrica,  977 

petrosa,  691 

renalis,  978 

suprareualis,  979 
Incisive  artery  of  mandibular,  495 

fossa  of  maxilla  (superior  maxilla),  55 
of  mandil)le  (inferior  maxilla),  62 

nerve  of  mandibular,  758 
Incisor  teeth,  87 
Incisura  [a  notch]  intertragica,  871 

marsupialis,  714 

temporalis.  691 
Incus  [an  anvil],  67  ;  origin  of,  90 
Infantile  bladder,  the,  1021 

hernia,  1026 
Infraclavicular  lymphatic  glands,  655 
Infracostal  artery,  lateral,  518 
Infracostales  (subcostales)  [infia,  below  ;  cosfa, 

a  rib]  muscles,  399 
Infra-hj^oid  artery,  482 

Inframandibular  (inframaxillary)  nerve,  766 
luframarginal  (superior  temporal)   convolution 

of  cerebrum,  688 
Infra-orbital  artery,  496 

canal,  55,  97 

foramen,  55,  97 

groove,  55 

nerve,  764 

plexus  (nerve),  755,  765 
Infrarimal   [rima,   a  chink]   portion  of  larvnx, 

911,  913 
Infra.scapular  artery  of  dorsal  scapular,  525 
Infra-spinatus  mu-scle,  .302 
Infraspinous  artery  of  posterior  .scapular,  516 
of  snpra.scapular,  515 

fossa.  111 
Infratrochlear  nerve.  752 
Infundibula  [infundibuhtm,  a  funnel]  of  kidnev, 

1014 
Infundibuliform   or  internal    spermatic    fascia, 

407,  1024 
Infundibnlum   [a  funnel],  or  conns  arteriosus, 
80,  9.31 


INDEX 


1241 


Infundibuimn  of  braiu,  707 
of  cochlea,  881 
of  ethmoid,  50 
Inguinal  \_inguen,  the  groin]  canal,  1132 
hernia,  causes  of,  1136 

coverings  of,  1 1 32 
parts  concerned  in,  1 131 
lymphatic  glands,  deep,  668 

superficial,  667 
region,  1208 
Inion  [ii'/oi',  the  occiput],  the,  70,  1080 
Inlet  of  pelvis,  145 

thoracic,  108 
Innominate  artery,   474;  topography  of,    1114; 
variations,  474 
bone  (see  Hip-bone),  138 
veins,  right  and  left,  603  ;  variations,  605  ; 
topography  of,  1113 
Interarticular  fibro-cartilage  of  acromio-clavicu- 
lar  joint,  219 
of  knee-joint  (semilunar),  258 
of  sternoclavicular  joint,  218 
of      temporo-mandibular       (maxillarv 
joint),  180 
ligament  of  choudro-stemal  joints,  214 
of  costo-central  joints.  208 
Intercavernous  sinuses  of  cranium,  621 
Interchondral  articulations,  214 
Interclavicular  ligament,  217 
muscle,  459 
notch,  104 
Interclinoid  ligament,  33 
Inter<!occ\geal  articulations,  205 
Intercolumnar  or  external  spermatic  fascia,  406, 
1023,  1131 
fibres  of  external  abdominal  ring,  406 
Intercondyloid  notch  of  femur,  150 
Intercostal   \^iuter,    between  ;    cosia,   a   rib]    ar- 
teries— 
anterior,  of  internal  mammary,  517 

of  musculophrenic,  518 
aortic,  548 

collateral,  of  aortic,  549 
superior,  518 

first,  of  superior,  519 
Ij'mphatics,  656 
lymphatic  glands,  657 
muscles,  external.  395 
internal,  395 
action  of,  396 
nerves,  lower,  801  ;  upper,  795 
space,  structures  in,  1110 
veins,  left  lower  superior,  605,  608 
left  upper  superior,  608 
right  superior,  lower  and  upper,  608 
Intercuneiform  joints,  272 
Interior  of  skull,  81 
Interlobar  fi.ssures  of  cerebrum,  681 
Intermetacarpal  articulations,  242 
Intermetatansal  articulations,  279 
Intermuscular  septa  of  the  sole,  377 
of  upper  arm,  306 
Interossei  \^inter,  between  ;  os,  a  lx»ne]  muscles 
of  foot,  dorsal,  385 

plantar,  385 
of  hand,  dorsal,  338 
palmar,  337 
Interosseous  artery,  anterior  and  posterior,  533 
surgical  anatomy  of,  1163 
common,  533 
dorsal,  of  foot.  600 

of  band,  541 
palmar,  544 


Intero.sseou3  artery,  recurrent,  535 

curtilage  of  sacro  iliac  synchondrosis,  202 

of  symi»liysis  i)ul)is,  207 
fibro-cartilages  of  carpal  joints,  2!{7 
ligaments  of  calcaneo-astragaloid  joint,  ante- 
rior and  posterior,  269 
of  calcaneo-cuboid  joint,  274 
of  c;ir])o-nieta(arpal  joints,  241 
of  carpus,  238 

of  cubo-cuueiform  joints,  272 
of  culw-metatarsiil  joint,  228 
of cuVjoscajjlioid  union,  272 
of  intercuneiform  joints.  272 
of  intermetacarpal  joints,  243 
of  intermctatarsal  joints,  279 
of  middle  tarsometatarsal  joint,  277 
of   outer  tarsometatarsal   (cubo-meta- 

tai-sal  joint),  278 
of  inferior  tibio-fibular  joint  (inferior 

intero-sseous  ligament),  266 
of  superior  tibiofibular  joint  (superior 
interos-seous  ligament),  264 
membrane,  radio  ulnar,  231 

tibio-lit)ular,  264 
nerve,  anterior,  792 

posterior,  795 
ridge  of  fibula,  158 
Interosseuis  prmua  i-ohirix  muscle,  459 
luterparietid  segment  of  squamo-occipital  bone, 

25,  1209 
Interphalangeal  joints,  245,  280 
Intersigmoid  fos.sa,  974 
Interspace,  perinical,  deep,  1067 

superficial,  1066 
Interspinales  muscles,  423 
Interspinous  ligaments,  196 
Intertransversales  muscles,  423 
Intertransverse  ligaments  of  coccyx,  205 

of  spine.  197 
Intertrochanteric  line,  anterior,  147 
posterior.  147 
Interventricular  aitery,  anterior,  473.  9:>7 
posterior,  473.  937 
groove,  927 
vein,  anterior,  610 

posterior.  610,  937 
Intervertebral  substance  of  sacro-coccvgeal  joint. 
204 
of  spine,  190  ;  oriirin  from  noto- 
chord,  281 
Intestinal  arteries  of  superior  mesenteric,  560 
canal,  rotati()n  of,  995 
lymphatic  glands,  663 

trunk,  664 
lymphatics  (iacteals),  664 
Intestine,  large,  969 

Citcuni,  970 
ileocacal  valve,  971 
vermiform  appendix,  971 
colon,  972 

rectum  and  anus.  974 
blood   supply  an<l    structure   of, 
975 
small,   964 

blo«)d  supply  of,  969 
(luoilenum,  964 
jejunum  and  ileum,  967 
lymjihatit'S  of,  969 
nerves  of,  969 
structure  of.  96'^ 
Intestines,  topograjihy  of  lllH 
Intrahemis])lu>rii-  nerve  fibres,  7"^6 
Intraparietal  fissure  of  cerebrum,  686 


1242 


ISDEX 


Intraspinal  veins,  62ii 
Intrinsic  muscles  of  larynx.  908 
of  tongue,  888 
Iris  ['P'f,  the  rainbow],  tlie,  848 

lymphatic  spaces  in,  853 

zones  of,  84*2 
Ischial  [tax'of,  the  hip]  ramus,  141 

tuberosity,  141 
Ischiatic  spine,  140 
Ischio-cavernosus  (erector  penis)  muscle,  1034, 

1079 
Ischio-femoral  baud.  247 
Ischio-rectal  (or  anal)  fascia,  1063 

fossie.  10(j4  ;  surgical  anatomy  of,  1127 

region,  1058 

segment  of  obturator  fascia,  1061 
Ischium  [/(TV'or,  the  hip],  the,  139 

development  of,  144 
Island  of  Eeil,  688 

Isthmic  border  of  thyroid  cartilage,  902 
Isthmus  [a  ueck]  of  Fallopian  tube,  1051 

of  fauces,  944,  1097 

of  gyrus  furnicatus,  691 

of  middle  fossa  of  base  of  skull,  83 

of  thyroid,  916 

of  uterus,  1044 
Iter  [a  route]  e  tertio  ad  quartum  veutriculum, 
710 

chordae  auterius  (Huguier),  97,  875 
postering,  41,  97,  875 


Jacobson,  nerve  of  (tympanic,  of  glosso-pharyn- 

geal),  768,  891 
Jacobsouian  cartilages  of  nose,  891 
Jaw,  lower,  see  Maudible 

upper,  .toe  Maxilla 
Jejunum  {^jejunus,  empty],  967 
Joints,  movements  of,  179 

structures  entering  into  formation  of,  176 
varieties  of,  177 

See  Articulation,  for  individual  joints 
Jugular  [jugulum,  the  throat]  foramen,  73,  86, 
96 
fossa,  37,  73 

ganglion  of  glosso- pharyngeal,  768 
process  of  ex-occipital,  26 
surface  of  temporal  bone.  37 
veins,  anterior,  617,  1100 

external,  616  ;  variations,  617  ;  topog- 
raphy of,  1103 
internal,  627 
posterior,  617 
Jugulo-cephalic  vein,  643 
Jugum  [a  yoke]  sphenoidale,  34 


Kerato-hyalix,  1075 

Kerntothyroid  muscle,  459 

Key  and  Ketzins.  foramina  of,  718 

Kidney,  the,  1005 

excretory  duct  of,  1014 
head-,  or  pronephros,  1055 
hind-,  or  metanephrf)S,  1055 
investment  and  fixation  of,  1006 
lymphatics  of,  665 
mid-,  or  mesoncphros,  1055 
nerves  of,  1012 
physical  characters  of,  1005 
position  and  relations  of,  1006 
structure  of,  1010 
topography  of,  1119 
varieties  of.  1012 


LAR 

Kidney,  vessels  of,  1011 

Knee-joint,  arterial  and  nerve  supply  of,  259 

ligaments  of,  254 

movements  of,  260 

surgical  anatomy  of,  1182 

sjMiovial  membrane  of,  extent,  «S:c.,  1185 
Krause,  eud-bulbs  of,  1076 


Labia  [plural  of  labium,  a  lip]  of  cervix  uteri, 
1046 
majora,  1038,  1129 
minora,  1038,  1129 
Labial  artery,  inferior,  487 
nerves  of  maxillary,  754 
vein,  inferior  and  superior.  613 
Labyrinth  [Aa/3l'jO^^■f^of,  a  maze],  or  internal  ear, 
879 
membranous,  881 
osseous,  879 

(lateral  mass)  of  ethmoid,  49 
Lacerated  [lacenim,  ragged]  foramen,  middle,  or 

sphenotic,  83 
Lachrymal  [lachrynui,  a  tear]  artery,  499 
of  middle  meningeal,  494 
of  nasal,  502 
bones,  53 
canal,  868 
canaliculi,  868 
caruncle,  840 
duct,  55,  76 
fossa,  47,  77 
gland,  868 

accessory  (Henle),  867 
nerve.  752,  865 
papilla,  840 

passages,  method  of  probing,  1095 
process  of  inferior  turbiual,  53 
puucta,  840,  868 

position  of,  1094 
sac,  868  ;  surgical  anatomy  of,  1094 
sulcus,  53,  78 
tubercle,  57 
vein,  626 
Lachrymo-ethmoidal  cells,  50 
Lacteals  \_lac,  milk],  the  (intestinal  lymphatics), 

664 
Lactiferous  [Jac,  milk  ;  fero,   I  bear]  or  galac- 

tophorous  ducts,  1070 
Lacuna  [Jaais,  a  lake]  magna  of  urethra,  1038 
Lacunaj  of  urethra,  1038 
Lambda  [A,  the  Greek  letter],  the,  69,  1080 
Lambdoid  [from  its  resemblance  to  the  Greek 

letter  A  ;  ddog,  like]  suture,  44 
Lamina  [a  layer]  cinerea,  708 

cornea  of  lateral  ventricle,  700 
cribrosa  of  eye,  842,  845 
elastic,  posterior,  846 
quadrigemina,  708 
spiralis,  880,  881 
terminalis,  670 
Lamiufp  of  cervical  vertebra?,  7,  1 1 
of  lumbar  vei'tel)ra\  12 
of  sacrum,  15 
of  typical  vertebraj,  6 
Laminated  tubercle  (or  nodule)  of  cerebellum, 

715 
Lanugo,  1078 

Large  cavernous  nerve,  838 
intestine,  969 

lymphatics  of,  664 
Laryngeal  arteries  of  inferior  thyroid,  inferior, 
514 


INDEX 


1243 


Laryngeal  arteries  of  superior  th^-roid,  superior 
and  iul'erior,  482,  483 
Ij'mpliatics,  deep,  65'2 
nerves,  inferior  or  recurrent,  772 

superior,  772 
pouch,  911 
veins,  627 
Larynx  [/tipi'};,  the  larynx],  the,  901 
cartilages  of,  901 
interior  of.  910 
joints  of,  907 
lineaments  of.  900 
lymphatics  of,  652,  913 
mucous  membrane  of,  910 
nerves  and  blood-ves.sels  of,  913 
supra-  and  infra  rimal  portions  of,  911 
ventricle  of,  911 
Lateral  area  of  medulla  oblongata,  722 
cartilages  of  nose,  890 
column  of  medulla  oblongata.  722 
cutaneous  arteries  of  aortic  intercostal,  550 
nerves  of  abdomen,  800 
of  thorax,  800 
depressions  of  middle  fossa  of  skull,  83 
groove  of  eras  cerebri,  711 
ground  bundle  of  spinal  cord,  738 
horn  of  spinal  cord,  737 
ligaments  of  ankle-joint,  267 
of  elbow-joint,  227 
of  interphalangeal  joints  of  fingers,  245 

of  toes.  280 
of  knee  joint,  254 
of  liver,  982 

of  metacarpo-phalangeal  joints,  243 
of  metatarsophalangeal  joints,  279 
occipito-atlantal.  183 
occipito-odontoid.  1^8 
of  temporo-mandibular  (maxillary)  ar- 
ticulation, 180 
of  uterus,  1048 
vertebral  (short)  194 
of  wrist-joint,  235 
mass  of  atlas,  7 

of  ethmoid,  49 
mixed  zone  of  spinal  cord,  738 
nasal  artery,  488 

cartilages,  927  ;  origin  of,  96 
pyramidal  tract  of  cord,  737 
root  of  auditory  nerve,  766 
sacral  arteries,  superior  and  inferior,  567 
of  middle  sacral,  564 
veins,  638 
sinuses  of  cranium,  621 
spinal  arteries  of  vertebral,  510 
ventricles,  694 
Latissimus    [broadest]     dorsi     (of    the    back) 

muscle,  292,  1142 
Leg,  cutaneous  nerves  of,  823 
surgical  anatomy  of,  1188 
veins  of,  646 

vessels  of,  topography,  1191 
Lens  [a  lentil],  crystalline,  the,  845,  849 
capsule  of,  845 
e(}uator  of,  849 
poles,  849 
Lenticular  [/^hs,  lentis,  a  lentil]  ganglion,  752, 

H63 
Lesser  anterior  gastric  artery,  556 
cornua  of  hyoid.  66 
occipiti^l  nerve,  783 
omentum,  958 
pancreas,  986 
posterior  gastric  artery,  556 


Les.ser  .lac  of  jieritoneum,  935,  9.")7 
sigmoid  cavity  of  ulna,  123 
splanchnic  nerve,  831 
suifcrlicial  petroi<al  nerve,  762 
trochanter,  147 
tuberosity  of  humerus,  115 

centre  of  ossification  for,  121 
wing  of  sphenoid,  31 
Levator  [/ew/r,  to  lift  up]  anguli  oris  muscle, 
437 
anguli  .scapula}  muscle,  290 
ani  mu.scle,  1061  ;  nerve  to,  808 
cliiriciiln'  mu.scle,  460 
r/lauduliv  thuioidae  muscle,  460 
labii  superioris  mu.scle,  438 

akeque  nasi  muscle,  438,  891 
menti  \^mentum,  the  cliin],  or  levator  labii 

inferioris  muscle,  44U 
palati  muscle,  944 
pal pebne  superioris  muscle.  856 
Levatores  costarum  mu.scles,  397 
Lieutaud,  uvula  of,  1019 
Ligament,  or  Ligaments  \_li(/are,  to  bind] — 
alar,  of  the  knee,  259 

annular,  of  ankle  ;  anterior,  368  ;  external, 
3(i9  ;  internal,  369 
of    wrist,    anterior,   311  ;    surgical 
anatomy  of,  116-^  ;  posterior,  311  ; 
surgical  anatomy  of,  1166 
astragalo  scaphoid,  274 
of  astragalus,  162 
atlanto-axoidean,    anterior,    185 ;   posterior, 

185  ;  transverse,  186 
of  auricle,  anterior  and  posterior,  871 
of  bladder,  false  and  true,  1018 
broad,  of  liver,  982 

of  uterus,  1048 
calcaneo-astragaloid,    antero-internal,   270  ; 
external,  270;    internal,  269;    interos.se- 
ous,  269  ;  posterior,  269 
calcaneocuboid,   inferior   (long  and   .short) 

and  internal,  274 
calcaneo-scai)hoid,  external,  270 
inferior,  273 
of  calcaneum,  164 
capsular,  see  Capsular  ligament 
carotico-clinoid,  of  sphenoid,  34 
carpal  dorsal,  237 

palmar,  237,  238 
carpo-metacarpal,  dorsal  and   palmar.  241, 

242 
cervico-basilar,  188 
check,  of  eyeball,  external  and  internal,  h60 

of  spine,  188 
chondro-sternal,  anterior,  213 

posterior,  inferior,  and  superior,  213 
chondro  xiphr)id,  212 
of  clavicle,  HI 

common,  of  vertebnc,  anterior,  193 
posterior,  193 
conoid,  220 
cora<o-acromial,  221 
coraco-clavicular.  220 
coraco-humeral,  224 
coracoid,  221 
coronar^',  of  knee,  259 
of  liver,  982 
costo-central  (or  stellate),  anterior,  208 
costo-davicular,  or  rhonilwid,  218 
costo-colic,  973 

costo-coracoid.  294  :  origin  of,  115 
costotransverse,     middle,    211  ;    posteiior, 
211  ;  superior,  211 


1244 


INDEX 


Ligament,  or  Ligaments — 
cotyloid,  *24i) 
cricothyroid,  }K)t> 
crucial,  of  central  atlaiito-axoidiau  joint,  186 

of  kuee-joint,  26T     . 
cubo-cuneiforni,    dorsal,    interosseous,    and 

plantar,  272 
cubo-metatarsal,  dorsal,  278  ;  plantar,  278  ; 

interosseous,  278 
cubo-scaphoid,     dorsal,     interosseous,     and 

plantar.  271,  272 
of  cuboid,  !()() 
deltoid,  of  ankle,  2G7 
dorsal,  of  carpus,  "I'M 

falciform,  of  fascia  lata  of  thigh,  345,  1138 
femoral,  1138 
of  lemur,  152 
of  fibula,  159 
gastro-phrenic,  958 
of  Gimbernat,  404.  1138 
glenoid,  of  interphalangeal  joints  of  foot, 
280 

of  hand,  245 

of  metacarpo-phalangeal  joints,  243 

of  shoulder-joint,  225 
gleno-humeral,  224 
of  Hey,  1138 
of  hip-boue,  143 
of  humerus,  120 
hyo  epiglottidean,  905 
ilio-femoral,  247 
ilio  lumbar,  199 
ilio-trochanteric,  248 
of  incus,  39,  877 
iufrapubic,  200 

interarticular,  of  costocentral  articulation, 
208 

of  choudro-st^erual  articulation,  214 
interclavicular,  217 
interclinoid,  of  sphenoid,  33 
intercuneiform,    dorsal,    interosseous,    and 

plantar,  272 
intermetacarpal,  dorsal,  and  palmar,  242 
intermetatarsal,   dorsal,     interosseous,    and 

plantar,  279 
interosseous,   of  calcaneo-astragaloid  joint, 
anterior,  270 
posterior,  269 

of  calcaueo-cuboid  joint,  274 

of  carpo-metacarpal  joint,  241 

of  carpus,  238 

of  costo-transverse  articulation,  211 

of  cubo-cuueifurm  joints,  272 

of  cubo-metatarsal  joints,  278 

of  cubo-scaphoid  union,  272 

of  intercuneiform  joints,  272 

of  intermetacarpal  joints,  243 

of  intermetatarsiil  joints,  279 

of  sacro-iliac  joint,  202 

of  tarso-metatarsal  joint,  middle,  277 
outer,  278 

of  tibio  tibular  joints,  inferior,  260 
superior,  264 
interi)halangeal.  of  lingers,  245 

of  toes,  280 
intersi)inous.  196 
intertransverse  of  cocc3'x,  205 

of  sjiine.  197 
intervertebral,  190 

of  larynx,  extrinsic  and  intrinsic,  905 
lateral,  of  ankle.  267 

of  elbow,  227 

of  interphaliingeal  joints  of  foot,  280 


Ligament,  or  Ligaments — 

lateral,  of  interphalangeal  joints  of  hand,  245 

of  knee-joint,  254 

of  liver,  982 

of  metacarpo-phalangeal  joints,  243 

of  metatarsophalangeal  joints,  279 

of  temporomandibular  (maxillary)  ar- 
ticulation. 180 

of  uterus,  1048 

of  vertebra?  (short  vertebral).  194 

of  wrist  or  radio-carpal  joint,  235 
of  liver,  982 

medio-carpal,  anterior  and  posterior,  239 
metiicarpal,  243 
nietacarpo-phalangeal,  243 
metatarsal,  278 
nietatarso-phalangeal ,  279 
oblique,  of  middle  radio-ulnar  articulation, 

230 
obturator,  of  stapes,  878 
occipito-atlantal.  anterior,  183 ;  oblique,  183 ; 

lateral,  183;  posterior,  183 
occipitocervical,  188 
occi  pi  to-odontoid,  see  odontoid 
odontoid,  central  or  suspensor3',  188 

check  or  lateral,  188 
orbicular,  of  radius,  230 
orl)ito-tarsal,  858 
of  OS  calcis,  164 
of  the  ovaries,  1051,  1214 
palmar,  of  carpus,  237,  238 
palpebral,  867 
petro  sjihenoidal,  39 
phreno-colic,  958 
plantar,  long  and  short,  275 
posterior,  of  ankle,  267 

of  carpus,  237,  239 

of  elbow,  227 

of  knee.  255 

of  wrist,  234 
of  Poupart,  404,  1114,  1138 

surgical  anatomy  of,  1174 
proper,  of  the  scapula,  221 
pterygo-spinous,  of  splienoid,  34 
pubic,    anterior,    206  ;    inferior,    206  ;    pos- 
terior, 205 ;    superior,  205 
pubo-prostati  c,   1018 
radiocarpal,  anterior  and  jiosterior,  234 
radio-ulnar,  anterior  and  posterior,  232 
of  radius,  128 
recto  uterine,  1049 
rhomboid,  or  costo-clavicular,  218 
round,  of  liver,  982.  1213 

of  uterus,  1050,  1214 
sacro  coccygeal,  anterior,  204  ;  posterior,  205 
sacro-iliac,  201 
sacro-lunibar,  199 
sacro-sciatic,  great,  or  posterior,  202 

small.  202 
scapho-cuneiform,  272 
of  scaphoid  (tarsal)  bone,  167 
of  scapula,  114,  221 
of  sphenoid,  34 

spheno-mandibnlar  (maxillary),  180 
spino-glenoid,  222 

stellate,  or  anterior  costo  central,  208 
sterno-clavicular,    anterior,  217  ;   posterior, 

216 
sternopericardial,  925 
of  sternum,  106 
stylo-hyoid,  3!» 

stylo-mandibular  (maxillary),  180 
suiiracoruual,  of  coccyx,  205 


I 


INDEX 


1245 


Ligament,  or  Ligameuts — 

suprascapular,  or  transverse,  2:21 
supraspinous,  of  coccyx,  205 

of  vertebr.T,  195 
suspensory,  central  odontoid,  188  ;  origin  of, 
28i 
of  eyeball,  858 
of  lens,  845,  850 
of  malleus,  67,  877 
of  penis,  1032 
of  thyroid  gland,  917 
tarsal,  external,  429 

internal  [teudo  ocnli],  429 
tarso-metatarsal,  277 

tiiyro-arytenoid,  inferior  and  superior,  906 
thyro-epiglottidean,  905 
tliyro-hyoid,  90(3 
of  tibia,  15() 

tibio-fibular,  anterior  and  posterior,  264 
anterior  and  posterior  inferior,  266 
transverse,  of  central  atlauto  axoidean  joint, 
186 
dorsal,  of  medio-carpal  joint,  2'59 
of  heads  of  metacarpals,  243 

of  metatarsals,  279 
of  liip,  249 
humeral,  225 
of    inferior    tibiofibular    articulation, 

266 
of  knee-joint,  259 
of  larynx,  or  crico-arytenoid,  906 
of  scai)ula,  221  ;  inferior,  222 
superficial,  of  palmar  fascia,  333 
of  plantar  fascia,  1062 
trapezoid,  220 

triangular,    of    urethra,    inferior    (anterior 
layer  of),  1066 
superior  or  deep  (posterior 
layer),  1068 
of  ulna,  125 
utero-inguinal,  1050 
ntero-pelvic,  l(i51 
utero-sacral,  949,  1051 
11  tero- vesical,  1049 
of  uterus,  muscular,  1050 
peritoneal,  1047 
of  Winslow,  255 
Ligamenta  brevia  of  band,  333 
longa  of  fingers,  333 
subllava  of  spine,  194  ;  functions  of,  198 
vaginalia  of  lingers,  333 
Ligamentous  artery  of  ovarian.  562 
Ligamentum  arcuatum  externum,  :W9,  408 
internum,  399 
denticulatum,  733 
ductus  arteriosus,  1213 

venosus,  1214 
infundibulopelvicum,  1048 
latum  pulmonis,  921 
mucosum,  259 
nucliiu,  196,  288,  1250 
patellic,  367;  surgical  anatomy  of,  11  "^4 
pectinatum  iridis,  846 
teres  [round],  249  ;  origin  of,  281 
Winslowii,  255 
Liguhe  of  fourtb  ventricle,  718 
Limbic  lobe  of  cerebrum,  692 
Limbus  [a  border],  corneal,  846 
Limen  [a  threshold]  insula-,  (\r^>^ 
Line,  condylar,  of  femur,  inner  and  outer,  15(1 
intertrochanteric,   of  femur,   anterior,    147; 

posterior,  147 
naso-lambdoidal,  727 


Line,  Nelaton's,  1173 
nuciial,  inferior,  *. 


5  ;  middle,  25  ;  superior. 


oblique,  of  chivicle.  109 

of  mandible  (inferior  maxilla),  (J2 
of  radius,  126 
spiral,  of  feuiiir,  1  17 
white,  of  obturatdv  fascia,  1061 
Linea  [a  line]  alba  [wliitd.  4(ll,  1111:  viscfir. 
behind,  1117 
aspera  [rough],  147 
(juadrata  [s(|uare],  147 

semilunaris.  407;  surgical  anatomy  of,  1114 
splendens  [shining],  729 
Linea;  transversa',  403 

Lingual  \_lin(jii<t,  the  tongue]  artery,  483,  1102 
of  mandi})ular  (inferior  dental),  495 
bone  (wr  Hyoid),  66 
glands  of  mucous  membrane,  885 
lymphatic  glands.  6.52 

nerve  [gustatory],  759  ;  methods  of  divid- 
ing, 1095 
of  facial,  765 
of  glosso  pharyngeal,  769 
vein,  627 

Lingualis  muscle,  superior  and  inferior,  t^f^S ' 

Lingula  [dim.  ot  U>i//ua,  a  tongue]  of  cerebellum, 
714 
of  sphenoid,  31  :  at  birth,  93 
Lips,  the  upper  and  lower,  942 
of  bicipital  groove,  116 
of  iliac  crest.  139 
Lisfrancs  amputation,  incisions  for,  1199 

tubercle  on  first  rib,  100 
Lissauer,  boundary  zone  of  741 
Lithotomv,   lateral,   parts  cut  during  operation 

of, '1123 
Liver,  the,  976 

])lood- vessels,  982 
general  |M>sition,  979 
ligaments,  9'^2 
lymphatics  of,  deep,  704 

superficial,  7(.)3 
relations,  981 
structure.  983 
topography  of,  1117 
varieties,  986 
weight  of,  976 
Lobes  of  cerebellum,  biventral,  715 
llocculns,  715 
posterior.  714 
([tiadrate,  714 
slender,  714 
tonsillar,  715 
of  cerebrum,  884 

central  (island  of  Reil).  (»>*8 
falciform,  691 
frontal.  6>*4 
limbic,  692 
occipital,  686 
olfaitory,  (i-<4 
parietal,  685 

temiM)ral  (temporo-spheuoidal),  687 
of  liver,  caudate,  979 
(juadrate,  977 
Spigelian,  979 
of  lung,  92:J 
of  thyroid.  915 
Lobule  of  cerebellum,  (|Uadratcand  posterior.  714 
of  cerebrum,  cuneate  U'uneusi,  691 
paracentral.  ()9() 
quadrate  (pracuneus),  691 
superior  parietal.  6H(j 


1246 


IXDEX 


Lobule  of  ear,  i^07 
of  testis.  1027 
Lobulus  centralis  of  cerebellum,  714 
gracilis  of  cerebellum,  714 
lingualis,  ()91 
Locus  [a  spot]  cieruleus  [blue]  of  Aturtli  ven- 
tricle, 719 
Loug  buccal  nerve,  757 
ciliary  nerves.  752 
(or  middle)  subscajnilar  nerves,  788 
(or  terminal)  branches  of  brachial  plexus, 

788 
(or  internal)  saphenous  nerve,  808 
pudendal  nerve,  812 

root  (sensory)  of  lenticular  ganglion,  752 
thoracic  artery,  .523 
Longissimus    [longest]     dorsi     [of    the    back] 

muscle,  417 
Longitudinal  bundle  of  mesencephalon — 
posterior.  713 
superior,  715 
fissure,  great,  of  cerebrum,  681 

of  liver,  977 
sinuses  of  cranium,  inferior  (inferior  sagit- 
tal), 921 
superior  (superior  sagittal),  619 
spinal  veins,  anterior  and  posterior,  630 
Longus  colli  muscle,  457  ;  nerves  to,  785,  788 
Looped  tube  of  Henle,  1011 
Lower,  tubercle  of,  930 
Lumbar  arteries.  553  ;  variations,  554 
of  iliolumbar,  567 
colotomy,  landmarks  for,  1119 
ealargement  of  cord,  734 
fii.scia.  408,  1146 
lymphatic  glands,  661 

trunk,  662 
nerves,  anterior  primary  divisions  of,  802 

posterior  primary  divisions  of,  781 
plexus,  802  ;  branches.  802 
portion  of  gaugliated  cord,  833 
region,  1208 
ribs,  103 
veins,  633 

ascending,  633 
vertebrae,  12,  13 

ossification  of,  21 
Lumbricales  [lumbricKx,  an  earthworm]  muscles 
of  foot.  382 
of  hand,  335 
Lung,  the,  920 

lymphatics  of,  658 
relations  to  chest-wall,  1111 
root  of,  structures  forming,  923 

relation  of  structures  in,  923 
structure  of,  924 

vessels,  nerves,  and  lymphatics  of,  924 
weight,  923 
Lunulaj  [dim.  of /una,  the  moon],  the,  932 
Lymphatic   {lympha,    water]    duct,    right,    648, 
653 
glands  of  abdomen  and  pelvis,  parietal,  661, 
662 
visceral,  661 
aortic,  or  median  lumbar,  662 
auricular,  posterior,  649,  1107 
axillary,  655 
bronchial,  658 
buccal,  649 
cardiac,  658 
cervical,  upper  and  lower,  653 

superficial  chain,  650 
cceliac,  662 


Lymphatic  glands,  epigastric,  657 
epitrochlear,  655 
of  extremity,  lower,  deep,  668 

superficial,  66'3 
upper,  deep,  655 

superficial,  655 
facial,  deep,  653 
femoral,  deep,  668 

superficial,  667 
gastric,  inferior,  664 

superior,  663 
gastro  epiploic,  664 
of  liead  and  neck,  deep,  652 

superficial,  649 
hepatic,  665 

iliac,  internal  and  external,  661 
infraclavicular,  655 
inguinal,  deep,  668 

oblique  and  vertical,  667 
intercostal,  anterior  and  posterior,  651 
lingual,  6.52 

lumbar,  median  and  lateral,  662 
niammarj',  internal,  657 
maxillary,  internal,  653 
mediastinal,  658 
mesenteric,  664 
nicso-colic,  664 
occipital.  649,  1107 
parotid,  649 
pectoral,  6.55 

popliteal,  668  ;  surgical  anatomy,  1206 
post-pharyngeal,  653 
psoas,  or  transverse  lumbar.  662 
pulmonarj',  658 
sacral.  661 

saphenous,  or  superficial  femoral.  667 
splenic,  665 

sternal,  or  anterior  intercostal,  6.57 
or  anterior  mediastinal,  658 
sterno-mastoid,  649 
of  stomach,  663,  999 
subclavian,  6.55 
submaxillary.  650 
suboccipital,  649,  1107 
subscapular,  655 
suprahyoid,  650,  1108 
of  thorax,  parietal,  6.57 
visceral,  658 
tracheal,  658 
system  (or  spaces)  of  eyeball,  861 
of  orbit,  864 
Lymphatics,  the,  648 

of  abdomen  and  pelvis,  parietal,  deep,  661 
superficial,  660 
visceral,  662 
of  bladder,  662 
of  brain,  651,  678 

broncho-mediastinal  trunk,  657,  658 
diaphragmatic,  656 
of  extremity,  lower,  deep,  668 

superficial,  667 
upper,  deep,  655 

superficial,  655 
of  eyeball,  861 
of  eyelids,  867 
of  face,  649 

of  Fallopian  tubes,  662,  1054 
gluteal,  660,  667 
of  head  and  neck,  deep.  651 

superficial,  649 
of  heart.  658 
intercostal.  656 
intestinal  trunk.  664 


INDEX 


1247 


Lymphatics — 

ot"  intestine,  large,  6G4,  !)7.5 
small,  fiG4,  !»7() 

of  kidneys,  665,  101:5 

of  larynx,  652,  912 

of  liver,  deep,  665,704 

snperllcial,  664,  7o:} 

of  lung,  658,  924 

of  mammary  gland,  656 

meningeal,  651 

of  mouth  and  tongue,  (i52 

of  neck,  649 

of  nose,  651,  897 

of  (esophagus,  653,  658 

of  orbit,  651 

of  ovaries,  GQ'i.  1054 

of  pancreas,  665,  987 

of  pelvis,  661 

of  i)enis,  661,  1035 

of  pericardium,  658 

of  perinaeum,  661 

of  pliarynx,  652 

of  prostate,  1023 

pudic,  1067 

of  rectum,  662 

of  scalp,  649 

of  scrotum,  661,  1024 

of  spinal  cord,  678 

of  spleen,  665,  990 

of  stomach,  663,  964 

of  suprarenals,  665,  1014 

of  temporal  fossa,  651 

of  testicle,  662,  1030 

of  thorax,  parietal,  deep,  656 

superficial,  656 
visceral,  658 

of  thymus,  658 

of  thyroid,  652 

of  tongue,  652 

of  tracliea,  652 

of  ureters.  685,  1016 

of  uterus,  662,  1054 

of  vagina,  662 

of  vas  del'erens,  1031 

of  zj'goraatic  fossa,  651 
Lymphoid  tissue  of  tongue,  887 
Lyre,  the,  of  fornix,  701 


Macula  [a  spot]  lutea  [yellow],  844 
Magnum  [great],  foramen,  27 

OS,  132 
Majendie,  foramen  of,  677,  718 
Malar  [mala,  the  cheek]  — 
bone,  61 

ossification  of,  62  ;  at  birtli,  95 
canals,  61,  97 

centre  of  ossification  of  maxilla,  58 
nerve  of  temporo-facial,  764 
of  temporo-malar,  754 
process  of  maxilla,  57 
Male  breast.  107 
pelvis,  146 

reproductive  organs,  1021 
Malleolar  arteries  of  anterior  tibial,  598 
of  posterior  tibial,  593 
fossa  of  fibula,  158 
Malleolus  [dim.  oimaUeua,  a  hammer]  of  fibula, 
external,  158  ;  development  of,  159  ;  sur- 
gical anatomy  of,  1194 
of  tibia,  internal,  153,  156 
Malleus  [a  hammer],  the,  67  ;  origin  of,  90 
Malo-maxillary  suture,  77 


Malpighi,  pyramids  of,  1010 

ManiMiu  [the  breast],  the  female,  1069 

di!veli)pnicut  antl  abnormalities,  1072 
lymi)hati(s  of,  <J56,  1071 
surgical  anatomy  of,  1110 
variations  aicoKling  t<)  age,  ^Vic,  loTl 
v('s.sels  and  nerves,  1071 
male,  1070 

lymphatic-sof,  '556,  1071 
Mamm;c,  supernumerary,  1215 
Mammarv  arterv,  external,  523 

internal,  516,  1114 
glandular  arteries  of  aortic  intercostals,  5.50 
lymjjhatic  glands,  internal,  ()57 
veins,  internal,  605 
Mammilla  [nipple],  1069  ;  abnormalities.  1071 
Mammillary  processes  of  vertebue,  12 
Mandible  (or  inferior  maxilla),  62 
ossification,  64 
at  birth.  95 
Mandibular  \_mnn<hi,   I  clicw]  artery,  or  interior 
dental,  494 
bar,  90 
canal,  63 

division  of  fifth  nerve,  756 
foramen,  63 

gland  (submaxillary).  949 
nerve,  or  inferior  dental,  758 
.spine.  (i3 
vein,  616 
Manubrium  [a  handle]  of  malleus,  67 

of  sternum,  104;  structures  behind,  1111 
Marginal  arteries,  right  and  left.  936 
convolution  of  cerebrum.  690 
sinuses  of  cranium.  620 
veins,  right  and  left,  611,  937 
Margino-frontal  artery  of  anterior  cerebral,  503 
Margo  [margin]  acutus  [sharji]  of  heart.  931 

obtusus  [blunt],  928 
Marshall,  obli(jue  vein  of,  926,  939 
Masseter  \_itapa<tr,iiai^  to  chew]  muscle,  441 
Masseteric  artery  of  facial,  4h7 

of  int€rnal  maxillary,  495 
of  temporal,  491 
fascia,  440 
nerve,  757 
vein,  614,  616 
Mastoid  [//o<T7of,  a  nipi)le  ;  f '"''"f,  like]  antrum, 
40,  1083  ;  develo])ment  of,  44 
arterj',  middle,  4h2 
of  occipital,  490 
of  posterior  auricular.   19<» 
of  stylomastoid,  490 
cells,  40  ;  emissary  veins  from,  1(M4 
tbramen,  73,  8() 
nerve  of  lesser  occipital,  7'^3 
process,  37.  73  ;  development  of,  44 
.sinuses,  the,  1082 
vein  (emi.«sary),  622.  672 
Maxilla  [cheek  Iwne],  or  suiH-rior  maxilla.  55 
ossification.  58 
at  l)irth,  95 

For  Inferior  maxilla,  sie  Mandible 
Maxillary  antrum.  55 

artery,  external  (facial),  4^*5 

internal.  492 
centre  of  ossification,  58 
fissure,  56 
inferior  (mandibular)  division  of  filth  nerve, 

756 
lymphatic  glands,  internal,  653 
nerves,  re<urrent,  753 
process  of  inferior  turbinal  lx)ne,  53 


1248 


LXDEX 


Maxillary  process  of  malar  bone,  61 
of  palate  lK)ne,  59 
sinns  (antrum),  57 
(superior  maxillarv)  division  of  tifth  nerve, 

753 
tuberosity,  55,  72 
veiu,  anterior,  (il  I 
iuterual,  (J  15 
Maxillo-premaxillary  suture,  5(>.  7"3 
Meatal  Imeaius,  a  passage]  artery,  490 

uerves,  758 
Meatus,  auditory,  external,  38,  73,  909 
interual,  3(5.  8(),  9(J 
uriuarj',  external.  1033,  10.'!8 
internal,  1018,  1037 

relation  to  pelvic  wall.  1018 
Meatuses  of  nose,  57,  894  ;  orifices  iu,  80 
Meckel's  cave,  37 

diverticulum  [divoio,  I  turn  aside],  967 
ganglion  [na.sal  or  sphenopalatine],  756 

roots  and  branches,  756 
space,  in  dura  mater,  673 
(Median  arterj'  [comes  nervi  mediant],  533 
furrow  of  back,  1142 
lymphatic  glands  (aortic  lumbar),  662 
nerve,  790 

inarm,  surgical  anatomy  of,  1154 
in  forearm,  surgical  anatomy  of,  1161 
plexus,  venous,  anterior,  641 
raphe  of  tongue,  884 
Median  [from  Arabic  al-madjan,  vein  of  Madjan] 
vein,  deep,  641,  643 
superficial,  641 
basilic.  641 
cephalic.  641 
Mediastinal,  or  thymic  arteries,  517 
lymphatic  glands,  658 
veins,  434 
Mediastinum  [«h(//«.s,  the  middle  ;  sto,  I  stand] 
of  thorax,  anterior,  901 
middle,  901 
posterior,  901 
superior,  900 
testis,  1026 
Medio-tarsal  joints,  273  ;  movements  of,  276 
Medulla    [marrow,    from    medius,    middle]    of 
kidney,  1010 
oblongata,  the,  fi70,  720 
fissures  of,  721 
internal  .structure  of,  724 
veins  of,  625 
Medullary  laminai  of  lenticular  nucleus,  699 
veins,  630 

velum,  inferior,  715,  718 
superior,  718 
Medulli-spinal  veins,  630 
Meibomian  follicles,  840 
Mei.ssner,  tactile  corpuscles  of,  1076 
Membrana    [the  skin  of    an  animal]  basilaris, 
1075 
of  cochlea,  883 
Shrapnelli,  874 
snprachoroidea,  845,  846 
tympani,  873  ;  structure  of,  874 
Membrane,  Bowman's,  846 
of  Bruch,  846 
crico-thyroid.  906 
Descemet's,  846 
hypoglo.s.sal,  888 
of  Reissner,  883 
Schneiderian,  893 
thyro-hyoid,  905 
of  trachea,  913 


Membranous  canal  of  cochlea.  883 
cranium,  89 
labvrinth,  the,  881 
urethra,  1037,  1106 
Meningeal    ['"/";  ^,    a    membrane]    artery    of 
ascending  ])haryngeal,  4H2,  673 
of  etlimoidals,  501,  673 
middle  or  great,  493,  673  ;  grooves  for, 

83 
posterior,  of  occipital,  489 
of  vertebral,  511,  673 
small,  495 
lymphatic  vessels,  651 
nerves  of  glosso  pharj'ngeal,  768 
of  hypoglossal,  775 
of  vagus,  772 
veins,  middle,  616 

extra- medullary,  629 
Meninges  [/"/i"}f,  a  membrane]  of  brain,  670 

of  spinal  cord,  731 
Meningo-rachidan  [Imx'C,  the  spine]  veins,  629 
Meniscus  [dim.  of  fi'/v?/,  the  moon]  of  malleo- 

iucal  joint,  876 
Mental  [mcntum,  the  chin]  artery  of  facial,  487 
of  mandibular,  495 
foramen,  62 

nerve  of  mandibular,  759 
protuberance,  62 
3Tento-hyoidcus  muscle,  460 

Mento-Meckelian  centre  of  ossification  in  man- 
dible, 64 
Mesencephalon  [t}A.f'9a/oi',  brain],  the,  670,  710 
Mesenteric  [/;f  aof,  middle  ;  ivTepov^  an  intestine] 
artery,  inferior,  562  ;  variations,  563 
superior,  558  ;  variations,  560 
topography  of,  1121 
lymphatic  glands,  664 

plexuses  (nerve),  superior  and  inferior,  835 
veins,  inferior,  637 

superior,  636  ;  tributaries,  636 
Mesentery  [t'lTf/joi',  intestine],  the,  967 

evolution  of,  998 
Mesethmoid  [v^/'Of,  a  sieve],  49 

origin  of.  96 
Mesial  [/"oof,  middle]  root  of  auditory  nerve,  765 
Meso-colic  lymphatic  glands,  664 
Meso-colon,  the,  evolution  of,  998 
Meso-gaster   [//taof,  middle;   )«'^"'/p,  st<imach], 

the,  1000 
Meso  palatine  suture,  57.  72 
Meso-steruum  [(rr/ynoj',  chest],  104 
Mesouephros  [/'*(Tof,  middle  ;  ve^ipof,  the  kidney], 

the,  1055 
Mesorchium  [wfdof,   middle  ;    op^V'f,  ^  testicle], 

1025,  1055 
Mesovarium,  1055 

Metacarpal  artery  (first  dorsal  interosseous),  542 
bones,   133 

ossification  of,  137 
union  of  heads  of.  243 
Metacari)o-phalangeal  joint  of  thumb,  244 

joints  of  four  inner  lingers,  243 
Metacar}ius  [/>';/;7ro(;,  wrist],  bones  of  the,  133 
Metanephros   [/vfTfi,   beyond  ;    vE(pp6g,    the   kid- 
ney], 1055 
Metasternum  [/'fd,  beyond  ;  aripvov,  the  chest], 

104 
Metatarsal  artery,  600 
bones,  169 

ossification  of,  172 
union  of  heads  of,  279 
Metatarsophalangeal   joints,    279  ;    movements 
of,  280 


LXDEX 


1249 


Metatarsus   [,"erd,  beyoud  ;  Tu/iaoi;^  the  instep], 

the,   1U9 
Metencephahn),  the.  670,  7-20 
Methods  of  detfrmiuiug  deep  origin  of  spiual 

nerves,  TSH 
Metopic  [ut'rwTToi',  the  forehead]  suture,  47 
Meynert's  commissure,  747 
Mid-kidney,  the,  1055 
Milk  teeth,  89 

Miniature  condyles  of  (finger)  phalanges,  K57 
Mitral  (bicuspid)  valve,  933 

topography  of,  933,  1113 
Moderator  band,  931 
Modiolus  [the  nave  of  a  -wheel],  41,  880,  881 

central  canal  of,  881 
Molar  liiiotd,  a  mill :  from  their  grinding  action] 
teeth,  upper  and  lower,  88 
third  (wisdom),  88 
Moll,  ciliary  glands  of,  1077 

modified  sweat  glands  of,  866 
Mons  [a  mountain]  Veneris,  the,  1039 
Montgomery,  tubercles  of,  1070 
Monticulus  [wno/s,  a  mountain]  cerebelli,  715 
Morgagni,  hydatid  of,  1027,  1215 

sinus  of.  951 
Morphological  neck  of  humerus,  121 

relation  of   patellar  facet  to  articular  por- 
tions of  femoral  condyles,  152 
Morphology  ["o/^^//,   form  ;    '/dyog,    discourse] — 
nature  of,  1 
of  pectoral  girdle,  115 
of  sca]iula,  115 
of  skull,  89 
of  spine,  22 

of  transverse  ligaments   of  heads  of  meta- 
tarsal bones,  281 
Motor  Imoveo,  I  move]  nerves  of  evelids,  867 

of  orbit,  863 
nucleus  of  glosso-pharyngeiil,  767 

of  trigeminal,  750 
root  of  lenticular  ganglion,  752 
of  otic  ganglion,  760 
Mouth,  the,  942 

lymphatics  of,  652 
surgical  anatomy  of,  1095 
vestibule  of,  942 
Mucous  membrane  of  bladder,  1019 
of  Fallopian  tube,  1052 
of  larvnx,  910 
of  nose,  892 
of  cesophagus.  953 
of  pharvTix,  949 
Schneiderian,  893 
of  small  intestine,  969 
of  soft  palate,  946 
of  stomach,  964 
of  tongue,  884 
of  ureter,  1015 
of  uterus,  1047 
of  vagina.  1044 
surface  of  vagina,  1044 
Mliller,  orbital  muscle  of,  858 

superior    i)alpebral    muscle    of,    856,    859, 
866 
Miillerian  duct,  1055 
Multifidus  [multus,  many  ■,Jindo,  I  cleave]  spina} 

muscle,  422 
Muscle,  or  Muscles — 

actions  of,  284 ;  advantages  of  oblique  attach- 
ment of  tendons.  2-^7  ;  arrectores  pilorum, 
1074  ;  constrictor  vaginie.  1041  ;  division 
of  muscles  into  the  three  orders  of  levers, 
285  ;    importance  of  the  direction  of  the 

79 


MUS 

tendon  at  its  point  of  insertion,  2H6;  of 
muscles  passing  over  more  than  one  joint. 
28(J 
Muscle  attachments,  nature  of,  283  ;  of  tendons, 
modes    of,    283  ;     of    bipenniform    [bix, 
twice  ;    pnina,   a   feather]    mu.scle.s,  283 ; 
of  biventral  [his,  and  rniln;  a  belly]  mus- 
cles,   2m:{  ;    of    multipcnniform     [mullnn, 
many]  muscles,  2K{ ;  of  penniform  [jicniia, 
a  feather]   muscles,  283  ;   functions  of  a 
central  tendon,  284 
of  Gutiirie,  1068 
metamorphosis  of,  into  ligaments,  2h1 

into  tendons,  281 
migration  of,  281 
nerve-sujiply  of,  284 
nomenclature  of.  reasons  for,  282 
shape  of,  varieties  in,  282 
structure  of,  283 
abductor  hallucis,  378 

longus  i>ollicis,  or  extensor  ossis  meta- 

carpi  poUicis,  329 
minimi  digiti,  foot,  379 

hand,  343 
Ofsis  mitalarsi  quinti,  458 
>)llici.s,  339 
abnormal,  458 

accelerator  urime  (bullK)  cavernosus),  1034 
accessorius  ad  ilio-costalem,  416 
adductor  brevis,  369 
hallucis,  383 
longus,  3.i8 
magnus,  361 
ossis  metatarsi  quinti,  458 
pollicis,  or  adductor  pollicis  transver- 
sus,  342 
obliquus,  341 
anconeus,  327 
anonialiis,  458 
antitragicus,  872 
aryteno-epiglottideus.  910 
arytenoideus,  91(1 
attollens  aurem.  431 
attrahens  aurem.  431 
azygos  pha/\i/)igis,  458 

uvula;,  981 
of  back,  classification  of,  414 
biceps  fiexor  cubiti,  307  ;  surgical  anatomy 
of,  1154 
femoris.  363 
brachialis  anticus.  308 

surgical  anatomy  of,  1156 
brachio-radialis,  or  supinator  longus,  321 
buccinator.  436 

bulbo-cavernosus  (accelerator  urina-i,  ]n34 
cervicalis  ascendens.  417 
chondro-rpitrovfilairis,  458 
cbondro-glo.ssus,  452 
ciliary.  H45,  847 

circumllexus  palati  (tensor  palati),  33,  945 
vlcido-lif/oi<l,  458 
cli'ido-ovcipitalis,  446,  458 
coccygeus,  l(i(!2 
com  plexus.  420 
compressor  nariuni,  432,  892 
minor,  h92 
s;icculi  laryngis.  91 1 
urethra?,  1(M)7 
vagina-.  1068 
venie  dorsalis  j)enis,  lo34 
constrictor,  of  pharynx,  interior.  950 
midille.  951 
suiH-'rior,  951 


1250 


IXDEX 


Mascle,  or  Muscles — 

coraco-bracbialis,  '.iUi>  ;  surgical  auatomy  of, 

1153 
corrugator  supercilii,  AM) 
cosfo-fascialis,  4riS 
creiuastcr,  407 

internal  (llenle),  1026 
crico-arvtenoitleus  lateralis  et  posticus,  910 
crico-th^'roid,  910 
crureus,  367 
curiaior  coccyyis,  4o8 
deltoid,  300  ;  surgical  anatomy  of,  ll.ll 
depressor  ahc  nasi,  433,  892 
anguli  oris,  438 
labii  iuferioris,  439 
i/ii/)()idc(t,  458 
diaphragm,  399.     See  Diaphragm 
digastric,  449 

dilatator  naris,  anterior,  433,  892 
posterior,  433,  892 
dorso-epiirocJtlcaris,  458 
of  ear,  external,  extrinsic,  431 
intrinsic,  872 
middle,  878 
epitrochleo-anconcus,  458 
erector  penis  (ischio-cavernosus),  lft34 

spinjE,  415 
extensor  annularis,  458 

brevis  digitorum  manus,  458 
pedis,  391 
pollicis,  or  extensor  primi  internodii 
pollicis,  330 
carpi  radialis  accessorius,  458 
brevior,  323 
longior,  323 
ulnaris,  327 
coccyijis,  458 

communis  digitorum,  324 
indicis,  332 
longus  digitorum  (pedis),  389 

pollicis,  or  extensor  secuudi  inter- 
nodii pollicis,  331 
viedii  dif/iti,  459 
minimi  digiti,  326 
ossis  metacarpi  pollicis,  329 

metatarsi  hollucis,  458 
primi   internodii   pollicis,    or  extensor 
brevis  pollicis,  330 
liaHucis  lonyus,  458 
proprius  hallncis,  387 
secundi  internodii  pollicis,  or  extensor 
longus  pollicis,  331 
flexor  accessorius  digitorum  pedis,  381 
Jongus,  459 
brevis  digitorum  pedis,  379 

hallucis  (pollicis  pedis),  382 
minimi  digiti  (hand),  343 

pedis,  384 
pollicis,  341 
carpi  radialis,  313 

hrevis  rcl  profundus,  459 
ulnaris,  315 
lougus  digitorum  (pedis",  374 
hallucis,  374 
pollicis,  320 
ossis  metacarpi  pollicis,  341 
perforatus,  379 
profundus  digitorum,  318 
snbliniis  digitorum,  315 
frontalis,  428 
gastrocnemius,  369 
gemellus  inferior,  357 
superior,  357 


MI'S 

Muscle,  or  Muscles — 

genio-bj'o-glossus,  452 
genio-byoid,  451 

gluteus  maximus,  351  ;  surgical  anatomy  of, 
1180 
medius,  353 
minimus,  354 
quartus,  459 
gracilis,  362 

helicis  major  et  minor,  872 
of  Hilton,   or  compressor  sacculi   larvngis, 

912 
hyo-epigloitideus,  459 
hyo-glossus,  452 
iliacus,  348 

minor,  or  ilio-capsularis,  459 
ilio-costalis  (or  sacro  lumbalis),  415 
incisivi  (muscnli),  435 
infracostales,  399 
infraspinatus,  302 
inierclaricular,  459 
intercostal,  external,  395 
internal,  395 
interossei,  of  foot,  dorsal,  385 
palmar,  385 
of  hand,  dorsal.  338 
palmar,  337 
interosseus  primus  volar  is,  459 
interspiuales,  423 
intertrausversales,  423 

iscbio-cavernosus  (erector  penis),  1034,  1041 
kerato-thyroid,  459 

of  larynx,  extrinsic  and  intrinsic,  908 
latissimus  dorsi,  292  ;  surgical  anatomy  of, 

1142 
levator  anguli  oris,  437 

scapulaj,  290 
ani,  1061 
claviculcc,  460 
glnndulir  thyroideee,  460 
labii  iuferioris,  440 

superioris  (proprius"),  439 
ala?que  nasi,  438 
menti,  440 
palati,  944 

palpebne  superioris,  856 
levatores  costarum,  397 
lingualis,  888 
longissimus  dorsi,  417 
longus  colli,  457 
lunibricales,  of  foot,  382 

of  baud,  335 
masseter,  441 
me7ito-hyoideus,  460 
of  mouth,  classification  of,  434 
of  Miiller,  orbital,  858 

superior  palpebral,  856,  859 
multilidus  spinae,  422 
mylo-glossus,  460 
raylo  hyoid,  450 
obliijue,  of  eye,  inferior,  856 
superior,  855 
obliquus  abdominis  externus,  404 
internus,  408 
auris,  872 

capitis,  inferior,  424 
su])eri<)i',   125 
obturator  exteriuis,  362 
internus,  356 
occipitalis,  427 
occipito-frontalis,  427 
occipUo-hyoid,  460 
occijyito-scapular,  292,  461 


t 

I 


J 


INDEX 


1251 


Mus(!le,  or  Muscles — 
omohyoid,  447 
opponens  minimi  digiti,  344 

poUicis,  34 1 
orbiciihuis  oris,  434 

));ilpebr;utim,  4'29 
orl)ito-i);ilpol)r:il  (Sappey),  858 
of  palate,  soft,  943 
palato-filossus,  453,  944 
palato-pliaryngeus,  944,  952 
palmaris  brevis,  :?34 

loiif^us,  314 
pectiuetis,  350 

pectoralis  major,  294  ;  surgical  anatomy  of, 
1153 

minor,  298  ;  surgical  anatomy  of,  1153 
pcroneo-cnlcnncuH  internus,  460 
pcroneo-tihiftHn,  460 
peroueus  brevis,  393 

longus,  392 

(/iKnius,  460 

ijuiiiti  di(/ili,  460 

tertins,  391 
of  pharynx,  950 
plantaris,  371 
platysma  myoides,  426 
popliteus,  371 

minor,  460 
prserectalis  (Henle),  1068 
pronator  radii  quadratus,  321 

teres,  313 
psoas  niagnus,  346 

2}arrHn.  348,  460 
pterygoid,  external,  442 
internal,  444 
pterygoideuH  propriua,  460 
pterygo-spin otts,  460 
pyramidalis  abdominis,  402 

nasi,  432,  891 
pyriformis,  355 
quadratus  fenioris,  358 

luniborum,  410 

meuti,  439 
quadriceps  extensor  femoris,  365 
recti,  of  eye,  856 
rectus  abdominis,  402 

capitis  anticus  major.  456 
medius,  461 
minor,  457 
lateralis,  425 
posticus,  major,  424 
minor,  424 

femoris,  366 

sfernalis,  461 
retraheus  aurem,  432 
rhninbo-dtloidens,  461 
rhoraboideus  major,  292 
minor,  292 
risorius,  437 
rotator  humeri,  460 
rotatores  spina;,  423 
sacro-lunibalis  (ilio-costalis),  416 
salpingo-pharyugens,  944 
sartorius,  350 
scalenus  anticus,  454 

medius,  455 

posticus,  455 
semi-membranosus,  364 
semispinal  is  colli,  422 

dorsi,  420 
senii-tendinosus,  3()4 
serratus  magniis,  298 

posticus  inferior,  413 


Muscle,  oi-  Muscles — 

serratus  ]K)sticus  superior.  41 1 

soleus,  :{72 

sphincter  ani,  external,  1059 

internal,  975,  1059 

vesica;  internus,  1019 
spinalis  dorsi,  419 
spU-uius  capitis,   114 

colli,  414 
staiicdius,  878 
sternal  is,  461 
sterno-deido-niastoid,  445 

sur>!;ical  anatomy  of,  1099 
sterno-hyoid,  447 
stcrno-thyroid,  448 
stylo-glossns,  453 
stylo-hyoid,  450 
stylo-pharyngeiis,  951 
subanconeus,  310 
subdavius,  296 
subcostals,  399 
subcrurcus,  ;5(i7 
subscapularis,  30.'' 
supinator  radii  lircvis,  328 
longus,  321 
su])ra-cl(tciciil(iris,  461 
supra-spinatns,  301     <^  '■ 
temporal,  441 
tensor  palati,  945 

tarsi,  430 

tympaui,  878 

vagina;  femoris,  352 
teres  niajor,  304 
minor,  303 
tliyro  arytouoideus.  909 
thyro-epiglottideus,  910 
thyro-hyoid,  448 
tibialis  anticus,  387 

jiosticus,  376 
libiofdscialix  aiiiicii-'i.  461 
tradiealis,  914 
trachelo-mastoid,  419 
tragicus,  872 
transversalis  abdominis,  408 

colli  (cervicis),  418 
transversus  auris,  872 

nucJix,  290,  461 

pedis,  3h4 

perina'i,  deep,  1068 

superficial,  1034,  106H 
trapezius,  288  :  surgical  anatomy  of,  1142 
triangularis  sterni,  398 

triceps  extensor  cnbiti,  309  ;  surgical  anat- 
omy of,  1154 

sura;,  369 
triticeo-glon.siii<,  461 
of  tympanum,  878 
vastus  extcrnus,  366 

internus,  367 
vesicopubic,  lOl'^ 
zygomaticus  major,  4.!7 

minor,  439 
Muscidar  ligaments  of  uterus,  1049 
Musculi  incisivi,  435 
papillares,  9:!1,  933 
jR'ctinati,  930 
Musculo-cutaneous  nerve  of  arm,  790 

of  leg,  Hl,->.  12(K) 
5rusculo-i)hrenic  artery,  518 
Musculo-spiral  gi-oove,  119 

nerve,  795  ;  surgical  anatomy  oi.  1154 
Muscnlus  ciliaris  Hioiani,  H(!5 
privroctalis  (Henle),  1068 


1252 


INDEX 


Musoulus  siispeusorius  duodeni,  966 
Jli/h-tjlossiis  muscle,  460 
Mylo-hyoid  [m/.v,  a  mill]  artery,  495 

groove,  (>3 

muscle,  4a() 

uerve,  759 

ridge,  63 


Nails,  1077 .  .  ,  ^ 
Nares,  posterior,  size  of,  1097 
Narial   [nares,  the  nostrils]  orifices,  anterior  and 

posterior,  80 
Xasal  [h«ai(s,  the  nose]  angle  of  maxilla,  57 
artery  of  ethmoidals.  501 
of  infra-orbital,  496 
lateral,  488 
of  ophthalmic,  502 
of  spheno-palatine,  496 
transverse,  502 
hones,  54 

at  birth,  95 
ossification,  55 
cartilages,  lateral,  origin  of,  96 
duct,  80,  868 
eminence,  47 
fossse,  79  ;  at  birth,  92 
ganglion  (Meckel's),  755 
lymphatics,  651 
lierve,  752,  864,  896 
inferior,  756 
superior,  755 
of  anterior  dental,  754 
of  maxillary,  754 
notch,  47 

portion  of  pharynx,  949 
process  of  maxilla,  57 
sinuses,  73,  79 
spine,  anterior,  47,  80 
posterior,  59,  80 
veins,  612,  625 

transverse,  613 
Nasion  [h«s«6-,  the  nose],  81,  728 
Xaso-lambdoidal  line,  729 
Naso-palatine  artery,  496 
groove,  54 

uerve  [nerve  of  Cotunnius],  755 
Nates  of  corpora  (juadrigemina,  710 
Neck,  cutaueous  nerves  of,  821 
lymphatics  of,  650 
surgical  anatomy  of,  1099 
triangles  of,  anterior,  1101 

carotid,  inferior  and  superior,  1102 
posterior,  1102 
submaxillary,  1101 
supra-hyoid,  1101 
tracheal,  or  inferior  carotid,  1102 
veins  of,  deep,  627 

superficial,  616 
N^lat(m's  line.  1173 

Nerve-fibres,  functions  and  structure  of,  671 
foramina  of  skull,  primarv  and  secondary, 

96 
roots,  spinal,  739 

tracts  in  thalamencephalon  and  prosenceph- 
alon, 717 
Nerve,  or  Nerve.s — 

abdominal,  of  vagus,  773 
abducent,  or  sixth  cranial,  760 
alveolar,  of  mandibular,  759 
Arnold's,  772 

articular,  see  Articular  nerves 
auditory,  or  eighth  cranial,  765 


Nerve,  or  Nerves — 

auricular,  anterior,  758 

great,  783 

of  lesser  occipital,  783 

posterior,  763 

of  vagus  (Arnold's),  772 
auriculo-temporal,  758 
axillary,  of  brachial  plexus,  788 
buccal,  of  facial,  765 

long, 757 
calcaneau,  internal,  818 
calcaneo-plautar  cutaneons,  818 
cardiac,  of  sympathetic,  830 

of  vagus,  cervical  and  thoracic,  773 
cavernous,  838 

cervical,  primary  divisions,  anterior,  782 
posterior,  779 

superficial,  783 
cervico-facial,  of  facial,  765 
chorda  tympani,  763 
ciliary,  long  and  short,  753,  850,  864 
circumflex,  788 

coccygeal,  divisions  of,  anterior,  809 
posterior,  782 
cochlear,  of  auditory,  767 
communicantes  hypoglossi,  784 
of  Cotunnius,  755 
cranial,  743.     See  Cranial  nerves 
crural,  anterior,  806 

of  genito-crural,  804 
cutaneous,  of  abdomen,  801 

calcaneo-plantar,  818 

external,  806 

of  hand,  797 

internal,  of  arm,  790 
of  leg,  807 
lesser,  789 

middle,  807 

of  musculo-spiral,  796 

palmar,  of  median,  793 
of  ulnar,  794 

perforating,  of  fourth  sacral,  808 

of  popliteal,  external,  814 
internal,  815 

of  pudic,  814 

of  thorax,  801 
dental,  inferior  (mandibular),  759 

superior,  754 
descendens  hypoglossi,  775 
dorsal,  of  clitoris,  813 

of  penis,  813,  1067 
fiicial,  or  seventh  cranial,  761 

of  great  auricular,  783 
frontal,  of  ophthalmic,  751,  8()4 
genital,  of  genito-crural,  804 
genito-crural,  804 

glosso-pharyngeal,  or  ninth  cranial,  767 
gluteal,  superior,  810 
inferior,  810 
ha^morrhoidal,  inferior,  813 
hyi)ogastric,  of  ilio-hyjiogastric,  803 
hypoglossal,  or  twelfth  cranial,  774 
iliac,  of  iliohypogastric,  803 

of  Inst  dorsal,  801 
iliohypogastric,  803 
ilio-iiiguinal,  801 
incisive,  of  mandibular,  758 
inframandihular  (inframaxillary),  765 
infra  or})ital,  of  facial,  764 
infratrochlear,  of  nasal,  752 
intercostal,  upper,  799 
lower,  800 
intercosto-humeral,  800 


INDEX 


12.')3 


Nerve,  or  Nerves — 

interosseous,  anterior.  792 
posterior,  795 
Jaeobson's,  768 
labial,  of  luaxillarv,  754 
lachrymal,  of  oplithalnne,  751 
laryngeal,  superior  and  inlerior,  762 
lingual  (or  gustatt)ry),  759 

of  facial,  764 

of  glosso-])haryngeal,  769 
lumbar,  primary  divisions  of,  anterior,  801 

posterior,  781 
malar,  of  facial,  764 

of  or])ital,  754 
mandibular  (inferior  dental),  758 
masseteric,  of  mandibular,  757 
mastoid,  of  great  auriciUar,  784 

of  lesser  occi))ital,  783 
meatal,  of  auriculotemporal,  757 

of  mandibular,  758 
median,  790,  1154 
meningeal,  of  glossopharyngeal,  768 

of  hypoglossal,  775 

recurrent,  of  mandibular,  756 
of  maxillary,  753 
of  vagus,  772 
mental,  759 
musculo-cutaneous,  of  arm,  791 

of  leg,  815 
musculo-spiral,  795 
mvlo-hvoid,  of  mandibular,  759 
misal,  752,  864.  896 

inferior,  756 

superior,  755 

of  anterior  dental,  754 

of  maxillary,  754 
naso-palatiue,  of  Meckel's  ganglion,  755 
obturator,  805 

accessory,  805 
occipital,  great,  779 
lesser,  783 
smallest,  779 
oculo-motor,  or  third  cranial,  747 
oesophageal,  of  vagus.  773 
olfactory,  or  first  cranial,  745 
optic,  or  second  cranial,  746 
orbital,  of  maxillary,  753 

of  IMeckel's  ganglion.  755 
orbito- temporal,  of  maxillary,  753 
palatine,  anterior  (great),  756 

external,  756 

posterior  (small',  756 
palmar  cutaneous,  of  median,  792 

of  ulnar,  794 
palpebral,  755 

parotid,  of  auriculo- temporal,  758 
patellar,  of  long  saphenous,  808 
pectineus,  807 

perforating  cutaneous,  of  fourth  .sacral,  808 
periuical,  of  fourth  sacral,  8u8 

of  pudic,  813 

superficial,  813,  1066 
petrosal,  deep,  great,  755,  828 
small,  828 

superficial,  external,  762 

great,  755,  762,  879 
lesser,  762 
pharyngeal,  of  glosso-pharyngeal,  769 

of  Meckel's  ganglion,  756 

of  symiiathetic,  828 

of  vagus,  772 
phrenic,  785,  1103 

communicating  branch  to,  787 


Nerve,  or  Nerve.s — 

plantar,  external  and  internal,  819 

digitals,  819 
pneumogastric,  or  tenth  cranial,  769 
iwpliteal,  external,  hi  } 
internal,  815 
pterygoid,  external.  756 
internal,  757 
pudendal,  long,  812 
pudic,  812 

pulmonarv,  of  vagus,  773 
radial,  795 

recurrent  articular,  of  popliteal,  ^15 
(inferior)  laryngeal,  772 
meningeal,  of  mandibular,  756 
of  maxillary,  753 
of  vagus,  772 
sacral,  primary  <Hvisions  of.  anterior,  ^08 
l>osterior,  7H2 
fourth,  808 
saphenous,  external  or  .short,  817 
long  or  internal,  808 
sciatic,  great,  814 

small,  813 
septiil,  of  Meckel's  ganglion,  755 

of  nasal,  752 
of  Soemmerring,  812 
of  soft  palate,  946 
spheno-palatine,  of  maxillary,  754 
.spinal,  776 

dee|)  origin  of,  737 
general  distribution  of,  778 
roots  of,  73H,  776 

topography  of,  1145 
spinal  acce.ssorv,   or  eleventh  cranial,   773, 

1103 
.splanchnic,  great,  831 
lesser,  831 
smallest,  831 
stapedial,  763 
stylo  pharyngeal,  769 

subscapular,  lower,  middle,  and  u]>per.  788 
supra-acromial,  784 
supraclavicular,  784 
sui)ramandibular  (supramaxiliary  i,  765 
supra-orbital,  of  ophthalmic,  751 
sujjrasi'apular,  787 
suprasternal,  784 

supratrochlear,  of  ophthalmic,  751 
symi)athetic,  826 

gaugliated  cords  of,  8.37 

cranial  and  cervical  jwrtiou,  827 
lumbar  portion,  KV.\ 
sacral  iK)rtion,  833 
thoracic  portion,  830 
plexuses  of,  xre  Plexuses,  nerve 
temporal,  of  facial,  764 
of  mandibular,  757 
of  orbital,  753 
suju'rlicial,  758 
teniporo-facial,  of  facial,  7(i4 
temporo-malar.  753 

thoracic,  anterior,  external  and  int.,  788 
]x)steriov.  7^7 
(or  dorsal)  spinal,  799 
spinal,  primary  divs.,  anterior.  h(H 
posterior,  781 
first,  798 
la.st,  801 
tibial,  anterior,  815 
lM)stcrior,  818 
tonsillar,  769 
trigeminal,  or  fifth  cranial,  749 


1254 


INDEX 


Nerve,  or  Nerves — 

trigeminal,  divisions  oi,  inandibular,  756 
maxillary,  753 
ophthalmic,  750 

trochlear,  or  fourth  cranial,  748 

tympauic,  of  glosso-pharvngeal,  768,  879 
of  sympathetic,  828,  879 

ulnar,  794,  11 5*4 

of  uterus,  838,  1053 

vagus,  or  pneumogastric,  769 

to  vas  deferens,  838 

vestibular,  of  auditory,  777 

Vidian,  755 

of  Wrisberg,  789 
Nervous  coat  of  eyeball,  848 
Nervuli  [dim.  of  nervus,  a  nerve]  gingivales  of 
maxillary,  754 

of  mandibular  (inferior  dental),  758 
Nervus  coraniunicans  pcrouei,  815 
tibialis,  817 
recurrens  rami  primi  (Luschka),  751 
'"Nervus  furcalis,''  810 
Neural  arch,  5  ;  morphology  of,  23 
Neuro-central  [vfiyjor,  a  nerve]  suture,  20 
Neuro-enteric  canal,  707 
Neuroglia  \_i'tvi)oy,  a  nerve  ;  }/'",  glue],  671 
Neuron,  738 
Ninth  cranial  (glossopharyngeal)  nerve,  726 

roots,  726 
Nipple,  1069  :  abnormalities  of,  1071 
Nipples,  supernumerary,  1215 
Notlule  [dim.  of  nodus,  a  knot]  of  cerebellum, 

715 
Nose,  the,  889.  1097 

cartilages  of,  889 

floor  of,  79 

meatuses,  894 

mucous  membrane,  893 

muscles  of,  892 

roof,  79,  893 

septum,  79,  891 

vessels  and  nerves,  893,  894 
Notch,  cotyloid,  of  acetabulum,  143 

ethmoidal,  46 

iliac,  anterior  and  posterior,  139 

interclavicular,  104 

intercondyloid,  of  femnr,  150 

nasal,  47 

ptervgoid,  33 

of  Rivini,  40,  874 

scapular,  111 

sciatic,  greater  and  lesser,  140 

sigmoid,  of  mandible,  64 

spheno-palatine,  60 

supra-orVjital,  47 

supra-scapular,  113 

trigeminal,  36 
Notochordal    [kj^oc,   the   back  ;   X"P^'i,  a  cord] 

region  in  the  chondral  skull,  89 
Nuchal    [Arabic    niiqrah,    hollow    at    nape    of 

neck]   lines,  25 
Nuck,  canal  of,  1050 
Nucleus  [a  kernel] — 

accessory,  of  auditory  nerve,  766 
of  trigeminal  nerve,  750 

sensorj',  of  trigeminal  nerve,  750 

ambiguus  of  medulla,  726 

amygdaloid,  700 

caiidatus,  699 

of  the  clava.  727 

cuneatus,  727 

of  descending  root  of  fifth  nerve,  709 

emboliformis  of  cerebellum,  716 


OCC 

Nucleus — 

of  lacial  nerve,  761 
fastigii  of  cerei)ellum,  716 
funiculi  teretis,  766 
gloliosus  of  cerebellum,  716 
large-celled    (Deiter's)    of   auditory   nerve, 
765 
(motor,  or  nucleus  ambiguus),  of  glosso- 
pharyngeal, 767 
lateralis  of  medulla,  726 
of  lens,  850 
lenticularis,  699 
motor,  of  trigeminal  nerve,  751 
olivary,  727 

small-celled  (chief)  of  auditory  nerve,  764  ; 
(sensory,    or    accessorio  -  vago  -  glosso  - 
pharyngeal)    of    glosso  -  pharvngeal, 
767 
tegmental  (red),  710 
of  third  and  fourth  nerves,  709 
Nuhn,  gland  of,  886 
Nutrient  artery  of  clavicle,  514 
of  iemur,  585,  1192 
of  humerus,  greater  tuberosity,  526 
shaft,  530 
upper  end,  530 
of  ilium,  572 
medullary,  of  tibnla,  592 

of  tibia,  592 
of  radius,  533 
of  ulna,  535 
Nymphse  [riw©;/,  a  bride],  or  labia  minora,  1039 


Obelion  [6/3e/oc,  an  arrow],  the,  70 
Obex  [a  bar],  the,  718 
Oblique  diameter  of  pelvis,  146 

measurement  of,  146 
fasciculus  of  pons  Varolii,  720 
line  of  clavicle,  109 
of  tibula,  158 

of  mandible   (inferior  maxilla),  exter- 
nal and  internal,  62,  63 
of  radius,  126 
muscles  of  orbit,  inferior,  857 
superior,  856 
ridge  of  scapula.  111 
of  tibia,  156 
of  ulna,  125 
sinus,  925 

vein  of  heart  (Marshall's),  610,  926,  936 
Obliquus  auris  muscle,  872 

capitis  inferior  muscle,  424 

superior  muscle,  425 
extern  us  abdominis  muscle,  404 
intern  us  muscle,  406 
Obturator  [ohturo,  I  stop  up]  artery,  571,  1140 
crest,  143 
fascia,  1061 
foramen,  138,  143 
groove,  140 

ligament  of  stapes,  878 
muscle,  exteruus,  362 

interaus,  356  ;  nerve  to,  812 
nerve,  805 

accessory,  805 
vein,  638 
Occipital  [oh,  against  ;  capid.  head  :  the  part  of 
the  head  opposite  the  forehead]  — 
artery,  488;  topography  of,  1102 

of  po.sterior  auricular,  491 
bone,  24  ;  at  birth,  92 

development  of,  29 


I 


INDEX 


1255 


Occipital — 

condyles,  28,  73 
convolutions  of  cerebrum,  687 
crest,  external,  25 

internal,  26,  86 
fissures  of  cerebrum,  687 
groove,  37,  73 
lobe  of  cerebrum,  686 
lymphatic  glands  (suboccipital),  649 
nerves,  great,  779 

small,  783  ;  topography  ol",  11U3 
smallest,  779 
point,  70,  Hi 

protuberance,  external,  25 
internal,  25 
sinus  of  cranium,  62U 
suture,  69 
vein.  614 

of  diploe,  619 
Occipitalis  muscle,  427 
Occipito-atlantal  articulation,  183 
Occipitocervical  ligament,  188 
Occipito-frontalis,  aponeurosis,  427,  1085 

muscle,  427 
Occipito-hyokl  muscle,  460 
Occipito-mastoid  suture,  86 
OccipHo-scapiihir  muscle,  461 
Occipito-temporal     convolutions    of    cerebrum, 

superior  and  inferior,  691 
Ocular  conjunctiva,  840 

muscles,  insertions  of,  844 
actions  of,  856 
Oculo-motor  groove  of  cms  cerebri,  710 
nerve  (third  cranial!,  747 
divisions  of,  747 
Odontoid  [or)o;r,  a  tooth  ;  elisor,  like]  ligament 
(central  occipito-odontoid),  188 
process,  9  ;  morphologA-  of,  22 
rEsophageal  [oiw,  oiau,  I  carry  ;  ^ajfh',  to  eat] — 
arteries  of  aorta,  548 

of  gastric  (coronary^,  550 
of  inferior  thyroid,  514 
of  left  phrenic,  553 
of  right  gastro-epiploic,  557 
Ij'raphatics,  upper.  652 

thoracic,  658 
nerves  of  vagus,  773 
plexus  (nerve),  773 
veins,  609 
(Esophagus   [0(0),   I  carry  ;  (payelVj  to  eat],  the, 
952 
relations  of,  in  neck,  952 

in  thorax,  953 
structure,  953 
Olecranon  [(J/fi;/,  the  elbow  ;  /cpav/oj',  the  head], 
the.  122 
fossa,  120 
process,  122 
Olfactory  [olfacere.  to  smell]  bulb,  745 
lobe  of  cerebrum,  684 
nerve,  745,  896 
sulcus  [straight],  685 
tract,  745 
Olivary  eminence  of  sphenoid,  30.  83 

process,  30,  83 
Olive,  superior,  766 

Omental  (epiploic)  arteries  of  right  gastro-epip- 
loic,  557 
(descending   epiploic)   of   left    gastro- 
epiploic, 558 
Omentum  [the  caul  enclosing  the  bowels],  ga.s- 
tro-.spleuie,  959  :  evolution  of,  1003 
great,  958  ;  evolution  of,  li>00 


Omentnm,  great,  length  of,  958 

lesser,  or  ga-stro- hepatic,  958  ;  evolution  of, 
1000 
Omo-hyoid  ['V^  a  .shoulder]  muscle,  447 
Opening,  .saphenou.s,  surgical  anatoniv  of,  121:5 
Operculum  [a  lid],  the,  6H2 
Opbryon  [oopiV,  eyebrow],  81 
Ophthalmic  [uipOn'/.fior^  the  eye]  artery,  499 

division  (first)  of  fifth  cranial  nerve,  751 

ganglion  (riliaiy  or  lenticular),  752 

veins,  common,  625 

inferior,  616,  626  ;  tributaries,  625 
superior,  625  ;  tributaries,  664 
Opisthion  [oTriaHioc,  hinder],  73 
Opisthotic  [^f>Tnalhv^  behind  ;  oi'c,  gen.  i^ror^  the 

ear]  centre  of  (>.ssifi(ati<tn,  43 
Opponens  [opposing]  minimi  digiti  muscle,  344 

poUicis  mu.scle,  341 
Optic  [i>-Toii(u,  I  sec]  chiasma,  70h,  746 

commissure,  7(IH,  746 
peduncles  of  717 

disc,  842 

foramen,  30,  76,  83,  96 

groove,  30,  83 

nerve,  746 

siieaths  of,  746 

radiation,  746 

thalamus,  705 

corona  radiata  of  717 

tract,  746 
Ora  [ora,  an  edge]  serrata,  845 
Orbicular  bone.  H77 

ligament,  230 

tubercle  of  incus,  68 
Orbicularis   oris    [nrhicithts,   a    little  circle  ;   os, 
oris,  mouth]  muscle,  434,  964 

palpebrarum  [palpcbra,  eyelid]  muscle,  429 
Orbiculus  ciliaris,  846 
Orbit  [orhitd.  a  circle],  the,  73 

arrangement  of  contents  of,  854 

arteries  of  H62 

fascia>  of,  857 

lymphatics  of  the,  651 

muscles  of,  855 

muscular  attachments  in,  79 

nerves  of,  863 

veins  of  the,  625.  863 
Orbital  artery  of  ant<'rior  cerebral,  503 
of  infra-orbital,  496 
of  JuiddJe  meningeal,  494 
of  temporal.  491 

convolutions  of  cerebrum,  685 

curve,  !r<64 

fascia,  85H 

margin  of  fronted  lobe,  684 

muscle,  858 

nerve,  or  teni]X)ro-malar,  754 

from  Meckel's  ganglion,  755 

oi)erculum,  683 

periosteum,  H5H 

plate,  of  frontal,  4(5 

process  of  malar  hone.  «il 
of  palate  bone,  60 

vein,  615 
Orbito-froutal  artery  of  middle  cerebral.  504 
Orbito-i)alpebral  muscle,  K")9 
Orbito-sphenoids.  31 
Orbito-tarsal  ligament.  8.5R 
Oman  of  (iinildes.  Ki-.'h.  1215 
Orifices  of  ejaculatory  ducts,  1041 
Os  ['w,  ossis.  a  bone]  conlis,  934 

calcis.  Hcc  Calcaneuin 

magnum.  132 


1256 


LXDEX 


OS 

Os  planum  of  ethmoid,  49 

trigouum,  1(W  ;  developmeut  of,  163 
Os  [os,  oris,  mouth]  i-eutrale.  Till 

inta;,  1209 

jai»onit'um,  1210 

ut^ri,  iutenmm  et  externum,  1047 
Ossa  snprasterualis,  1210 
Osseous  spiral  lamina,  41 

labyrinth,  879 

portion  of  Eustachian  tube,  876 

portion  of  external  auditory  nieatus,  873 
Ossicles  [ossiculum,  a  little  Ijone],  epipteric.  48, 
71 

auditory,  67,  (i>^  ;  origin  of,  90 
Ossification,  centres  of,  in — 

astragalus,  163 

atlas,  20 

axis.  20 

calcaueura,  or  os  calcis,  165 

carpal  bones,  133 

clavicle,  111 

cuboid,  166 

cuneiform  bones  of  tarsus,  external,  169 
internal,  168 
middle,  168 

ethmoid,  50 

femur,  152 

fibula,  159 

frontal,  48 

hip  bone,  144 

humerus,  121 

hyoid,  95 

lachrymal,  53 

malar,  62 

mandible,  or  inferior  maxilla,  64 

maxilla,  or  superior  maxilla,  58 

metacarpus,  137 

metatai-sus,  172 

nasal,  55 

occipital .  29 

palate,  60 

parietal,  46 

patella,  153 

phalanges,  of  foot,  175 
of  hand,  138 

radius.  128 

ribs.  103 

scaphoid,  of  tarsus.  167 

scapula,  114 

sphenoid,  34 

sternum,  107 

styloid  process,  90 

temporal,  43 

tibia,  157 

turbinals,  inferior,  53 

sphenoidal,  52 

tympano-hyal,  90 


ulna,  125 
vertebr£e.  cervical. 


21 


sixth  or  seventh, 
coccygeal,  22 
lumbar,  21 
sacral.  22 
typical,  19 
vomer,  54 
Osteogenesis  [o(7rfor.  abone;7i'i'f(T'f,  formation],  1 
Ostium   [an  opening]  abdominale  of  Fallopian 

tube,  1051 
Otic  [oi'r,  the  ear]  ganglion  [Arnold's],  760 
Outlet  of  pelvis,  146,  1096  :  dimensions  of.  146 
Ovarian  [ovum,  an  egg]  arteries,  562,  1053 
bulb,  633 
lymphatics,  662 
veins,  633,  1054 


Ovaries  [ovum,  an  egg],  the,  1052 
Oviducts  (or  Fallopian  tubes),  the,  1051 
Ovisacs,  or  Graafian  Ibilicles,  1053 
Ovula  [dim.  of  ontui]  Nabothi,  1047 


Pacchioxiax  glands,  677  ;  structure  of,  678 
Pacini,  corpuscles  of,  1076 
Pacinian  corpuscles,  784 
Palate,  the,  943 

arterial  and  nerve  supply  of,  946 

mucous  membrane  of,  946 

muscles  of,  944 

structures  cut  in  paring  edges  of  cleft, 

1097 
surgical  anatomy  of,  1097 
bone,  the,  58 

ossification  of,  60 
at  birth,  95 
Palatine  artery,  ascending  or  inferior,  486 
of  ascending  pharyngeal,  482 
descending  or  posterior,  496 
canals,  accessorv',  59 

anterior.  56,  80 
external,  59 
posterior,  59,  70 
foramina,  72 
fossa,  anterior,  57 
nerves,   anterior  (great),   jwsterior  (small), 

and  external,  756 
sutures,  72 

vein,  inferior  or  descending,  614 
sujierior,  616 
Palato-ethmoidal  cells,  50 
Palato-glossus  muscle.  453,  943 
Palato-pharyngeus  muscle,  944,  952 
Palato-quadrate  bone,  representative  of,  in  man, 

90 
Palmar  arch,  deep,  543 

branches  and  variations,  543 
surgical  anatom}' of,  1168 
sniierficial,  536 

surgical  anatomj^  of,  1167 
variations,  537 
bursa,  great,  317,  1170 
cutaneous  nerve  of  median.  793 

of  ulnar,  795 
fascia,  333  ;  surgical  anatomy  of,  1169 

superficial  transverse  ligaments  of,  333 
Palmaris  brevis  muscle,  334 

longus  muscle,  314  ;  nerve  to,  791 
Palpebral  [palpehra,  eyelid]  aperture,  768 
artery,  502 

of  lachrymal,  500 
of  supra-orbital,  500 
conjunctiva,  840,  866 
fascia,  858 

folds  or  grooves,  inferior  and  superior,  840 
ligament,  inner  (or  tendo  oculi),  839,  867 

outer,  867 
muscle,  inferior,  86() 

superior,  857,  859,  867 
veins,  inferior,  614 
superior,  613 
Pampiniform  [piimpinus,  a  tendril]  plexus,  632 
Pancreas  [irdi',  all  ;  Kptni;,  flesh],  the,  98() 
blood-sup]ilv  of,  987 
duct  of,  987 
lesser,  986 

lymphatics  and  nerves  of,  665,  987 
topography  of.  1118 
Pancreatic  area  of  anterior  surface  of  kidney, 
1009 


INDEX 


\-2oi 


Pancreatic  artery,  j^reater,  of  splenic,  558 
lesser,  of  hepatic,  55(j 
of  splenic,  557 
lymphatics,  665 
plexus  (nerve),  835 
raucreatico-duodenal  artery,  inferior,  558 
superior,  557 
plexus  (nerve),  835 
vein,  636 
Papilla  [a  teat],  lachrymal,  840 

optic,  842 
Papilhe  of  kidney,  1010 
of  the  skin,  1075 
of  tongue,  884 
Paracentral  lobule,  690 
Paradidvniis  [-apa,  beside  ;  6ii)vuoq,  the  testicle], 

1028 
Parallel  fissure  of  cerebrum,  688 
Parenchyma  of  lung,  924 
Parepididymis,  1215 
Parietal  {^paries,  a  wall]  artery,  504 
bone,  44 

ossification,  46 
at  birth,  94 
convolution,  ascending,  686 
eminence,  44 
lobe  of  cerebrum,  685 
lobule,  superior,  686 
lymphatic  glands  of  pelvis.  660 

of  thorax,  superficial  and  deep,  656 
lymphatics  of  pehis.  660 

of  thorax,  656 
vein  of  diploe,  external,  618 
Parieto-mastoid  suture,  71,  86 
Parietooccipital  fissure,  682,  690 

vein  of  diploe,  619 
Parieto-temporal  artery,  504 
Parotid  ["«/«',  near  ;  olr,  the  ear]  artery  of  jxts- 
terior  auricular,  490 
of  temporal,  491 
fascia,  440 
gland,  the,  946 

duct  of,  948  ;  surgical  anatomy  of,  1091 
vascular  and  nervous  supply,  948 
lymphatic  glands,  superficial,  649 
nerves  of  auriculo-tenii>oral,  803 
vein,  614,  615 
Paroiiphoron,  1049,  1214 
Parovarium,  the,  104H,  1214 
Pars  basilaris  of  inferior  frontal  convolution,  685 
bulbosa  of  urethra,  1037 
ciliaris  retinue,  845,  848 
frontalis,  of  central  lobe,  688 
intermedia  of  Wrisberg,  761 
intermedialis  (Kobelt)  of  vagina,  1041 
orbitalis  of  inferior  frontal  convolution.  685 
parieto-talciformis,  of  central  lobe,  (\>i>i 
temporo-parietalis,  of  central  lobe,  689 
triangularis  of  inferior  frontal  convolution, 
685 
Patella  [a  small  pan],  the.  152 

dislocation  of,  mechanism,  1184 
ossification  of.  153 
relations  to  femoral  condyles,  1184 
surgical  anatomy  of,  1182 
Patellar  branches  of  long  saphenous  nerve,  808 
facet  on  femoral  condyle,  151  :  morphologi- 
cal relation  to  articular  jwrtious  of  the 
condyles,  153 
rete  [a  net],  589 
Pecquet,  cistern  of  (receptaculum  chyli),  659 
Pectineo-femoral  baud.  248 
Pectineus  \^pecten,  the  pubic  bone]  muscle.  350 


Pectineus,  nerve  to,  785 

Pectoral  {^pichis,  the  breast]  aiu-iy  oi  ;i<  lumm- 
tliora<ic,  521 
of  anterior  circumflex,  525 
fa.scia,  294 

girdle,  mor])hology  of.  115 
lymphatic  glaiuls.  655 
Pectoralis  major  muscle,  291  ;  surgical  auat<Mnv 
of,  11.53 
minor  muscle,  298  ;   surgical   ana'oniv  of, 
1153 
Peculiar  ribs,  100,  103 
vertebra;,  7,  12,  13 
Pedicle  \_pes,  a  foot]  of  vertebrae,  5,  9,  12,  14 
Peduncles,  cerebellar.  714,  717 
of  optic  thalamus,  717 
of  pineal  body,  705,  706 
Pelvic  fa.sci;e,  1060  ;  surgical  anatomy  of,  1129 
plexus  (nerve),  837 
portion  of  ureter,  1015 
segment  of  obturator  fa.'^ci a,  1061 
vi.scera,  lymphatics  of,  662 
Pelvis  [a  ba.sin],  the,  145 
axis  of,  146 
diameters  of,  145 
false,  145 
fascia-  of,  1060 
inlet  of,  145 

lymi)liatic  glands  of,  parietal.  661 
l^'inphatics  of,  660 
measurements  of,  146 
outlet  of,  146,  1058;  dimensions  of,  146 
po.sition  of.  146 
sex  dilTerences,  146 
true.  145 
veins  of,  ti38 
Pelvis  of  kidney,   superior,  inferior,  and   cum 

nion,  1014 
Penile  \^peni»,  a  tail]  angle,  the,  1037 
Penis  [a  tail],  the.  1031 ' 
coverings  of,  1031 
cutaneous  nerves  of.  823 
dorsal  artery  of  576,  1066 

nerves  of  10()7 
lymphatics  of  661 
structure  of,  1033 
suspensory  ligament  of  1032 
Perforated  space,  anterior,  699  ;  posterior.  6^*0 
Perforating   arteries,  anterior,  of  plantar   digi- 
tals, 595 
lateral,  of  internal  mammary.  517 
of  middle  meningeal,  494 
of  ])almar  arch,  deeji,  545 
posterior,  of  external  plantar,  594 
of  profunda  femoris,  584 
of  submental,  4'^7 
cutaneous  nerve  of  fourth  .sacral,  809 
Pericardiac  artery  of  internal  mammary,  517 
of  j>breni<'  arteries.  553 
of  thoracic  aorta,  545 
veins,  605 
Pericardium   ["•,",  around  :  ^<//>'*(o,   the  lieait], 
the,  925 
lymphatics  of,  658 
relations  of,  926 
ve.s.<els  of  926 
vestigial  fold  of  926,  1214 
Periglotlis.  the,  905 
Perilym])h,  the.  h8I 
Perina*al  arteries,  snperticial,  574 
transverse,  575 
body  (in  female i,  1(M;9 
fascia,  <leep,  anterior  layer,  1067 


1258 


IXDEX 


Perinaeal  fascia,  deep,  posterior  (superior),  1068 
superficial,  deep  layer  of  [Colics'],  1066 
interspace,  superficial,  contents  of",  1066 

deep,  contents  of,  1U67 
lymphatics,  superficial,  661 
nerves,  tbe,  813 

branch  of  fourth  sacral,  809 
Perina?iiai  [~f/>',  arounil  :    ifl'w,  I  am  situated], 
central  point  of,  1122 
female,  1068 
male,  1058 
proper,  106") 

surgical  anatomy  of,  1122 
triangles  of,  1122 
Periorbita,  858 
Periosteal  [~fp',  around  :  oariov^  a  boue]  artery 

of  supra-orbital,  500 
Periosteum,  orbital,  858 

Periotie   [t^^P',  around  ;   oir,  the   ear]   capsule, 
89 
cartilages,  89 
Perirenal,  or  capsular  arteries,  560 
Peritoneal  artery  of  conmiou  iliac,  565 

of  superior  epigastric,  518 
ligaments  of  bladder,  1018 
of  liver,  982 
of  uterus,  1048 
Peritoneum    [-ep/,    about  :    reivu,    I    stretch], 
arrangement  of,  explained,  991 
evolution  of,  991 
final  changes  in,  997 
general  characters  of,  954 
greater  and  lesser  sacs  of,  955,  957 
recto-vaginal  pouch  of,  957 
recto-vesical  pouch  of,  957 
traced  in  longitudinal  section  of  the  body, 
957 
in  transverse  section,  955 
Peroneal    [-f/jor?/,  the   pin  of  a  buckle]  artery, 
592 
anterior,  592 
posterior.  592 
surgical  anatomy  of,  1192 
groove  of  calcaneum  163 

of  cuboid,  165 
nerve  [external  iwjiliteal],  815 
tubercle  of  cakaneum,  163 
Peronei  tendons,  where  divided,  1197 
I'eroneo-cnIcnneuH  iniernuK  muscle,  460 
Pooneo-fibialis  muscle,  460 

Peroneus  [-fpoi;/,   the  pin  of  a  buckle,  or  the 
fibula]  brevis  muscle,  393 
lougus  muscle,  392  ;  action  upon  arches  of 

foot,  1205 
quartus  muscle,  460 
quhiti  dif/iii  muscle,  460 
tertius  [the  third]  muscle,  391 
Perpendicular  fissure,  internal,  682 

plate  of  ethmoid,  49 
Pes  [a  foot]  or  crusta  of  crus  cerebri,  711 
anserinns  [titn^ir,  a  goose],  764 
hippocampi,  697 
Petit,  triangle  of,  1145 
Petro-mastoid  canal,  40 
Petro-occipital  suture.  86 
Petro-sphenoidal  foramen,  3(!,  86,  96 
ligament,  39 
notch,  86 
process,  36 
suture,  83 
Petro-sr|uamosal  suture.  36 
Petrosquamous  sinus  of  cranium,  619,  623 
Petrosal  [-irpa,  a  rock]  artery,  494,  878 


Petrosal  nerve,  deep,  great,  755,  828 
small,  828 
superficial,  external,  762 

great,  755,  762,  879 
lesser,  762 

foramen  for,  37,  83 
portion  of  temporal  bone,  35  ;  at  birtli,  93 
sinuses,  superior  and  inferior,  (i22 
Petrous  ganglion  of  glosso-pharyngeal,  768 
Peyer's  patches,  969 

Phalanges   [G«/rt}^.    a   rank  of   soldiers:    from 
tiieir  regularity]  of  fingers,  137 
ossification  of,  138 
of  toes.  172 

ossification  of,  175 
Pharyngeal    [oi/pi'jf,    the    throat]    aponeurosis, 
949 
arteiy,  ascending,  481 

of  pterygo-palatine,  496 
of  spheno-palatine,  496 
of  Vidian,  496 
bursa,  952 
lymphatics,  652 
muscles,  949 

nerves  of  glosso-phar^'ngeal,  769 
of  Meckel's  ganglion,  756 
of  superior  cervical  ganglion,  828 
of  vagus,  772 
recess,  952 
tonsil,  952 
tubercle,  73 
veins.  626 
Avails,  950 
Pharyngoepiglottidean  fold.  905 
Phaiynx  [(papv};,  the  throat],  the,  949 
divisions  of  (buccal  and  nasal),  949 
interior  of,  951 
muscles  of,  950 
Phrenic   [i?/"/!',   the  mind  :  the  diaphragm  was 
supposed  to  be  the  seat  of  the  mind] — 
artery,  inferior,  553  ;  variations,  553 
of  inferior  thyroid,  514 
of  musculo-phrenic,  518 
of  superior  epigastric,  518 
superior,  516 
nerve,  the,  785,  1103 

communicating   branch   from   brachial 
plexus  to,  786 
veins,  inferior,  633 
Phreno-colic  ligament,  958 
Pia  [tender]  mater  [mother],  cerebral,  677 

spinal,  732 
Pillars  of  the  external  abdominal  ring,  406,  1131 
of  the  fauces,  944 

of  the  fornix,  anterior  and  posterior,  701 
Pineal  [pinus,  a  fir-cone]  body,  705,  1212 
Pinna  [a  feather],  the,  870 

cutaneous  nerves  of,  821 
Pirogofif's  amputation,  1198 
Pisiform  bone  [  jii.'^iiw,  a  pea],  131 

articulations  with  carpus,  237 
Pituitarv    [pituita,    the   nasal   secretion]    bod\ 
(gland),  707,  1212 
membrane  (Schneidorian),  7H3 
Plantar  [  phinia,  the  sole]  arch,  629 
arteries,  external,  593 
internal,  596 
surgical  anatomv  of,  1202 
digital,  594,  601 
fascia,  .377;  functions  of,  1203 
nerves,  external  and  internal,  819 
digitals,   819 
Plantaris  [  plniita,  the  .sole]  muscle,  371 


i 


I 


I 


I 


L\Di:x 


1259 


Plate    of    lateral    nasiil    cartilages,    inner    and 
outer,  81)0 
fronto- nasal,  89 

ptervgoid,  internal  and  external,  33  ;  origin 
of,  90 
Platysina  niyoides    [-/uTivua.   a   jilate  ;  /nr,    a 

muscle  ;  e'uhg,  like]  muscle,  42<) 
Pleura  [T/.ei'p«,  the  side],  the,  920 
relation  to  chest-wall,  1112 
costalis,  920 
lymphatics  of,  658 
pnlnionalis,  920 
Pleural  arteries,  550 
Plexus,  nerve,  cranial  or  spinal — 
brachial,  l>^(i 
cervical,  783 
coccygeal,  809 
gnla;,  773 

infra-orbital,  755,  7fi5 
lumbar,  802 
patellse^  807 

pulmonary,  posterior,  773 
sacral,  809 
subsartorial,  807 
subtrapezial,  785 
sympathetic — 
aortic,  835 

cardiac,  super6cial  and  deep,  834,  939 
carotid,  828 
cavernous,  828 
cceliac,  835 
coronary  (gastric),  835 

(cardiac)  left  and  right,  h34,  t»77 
cystic,  835 
diaphragmatic,  835 
gastroepiploic,  right  and  left,  835 
hiemorrhoidal,  middle,  837 
hepatic,  835 
hypogastric,  837 

mesenteric,  superior  and  inferior,  835 
pancreatic,  835 
pancreatico-duodenal,  835 
pelvic,  837 

prevertebral .  great,  834 
prostatic,  837 
pyloric,  835 
renal,  835 
solar,  835 
spermatic,  837 
splenic,  835 
suprarenal,  835 
uterine,  838 
vaginal,  838 
vesical,  837 
venous — 

anterior  median,  of  forearm,  fitl 
choroid,  of  lateral  ventricles,  698 
of  fourth  ventricle,  718 
of  third  ventricle.  703 
dorsal,  of  hand,  640 
htemorrhoidal,  639 
pampiniform,  6.32 
prostatico- vesical,  639 
ptervgoid,  615 

of  Santorini  (female  nretlira\  1042 
spinal,  anterior  and  posterior.  628 
vesical.  639 
Plica  [a  fold]  semilunaris,  407.  840,  1212 

ureterica,  1019 
Plica?  ciliares,  845 

Pneumogastric  [-vEVfjuv,  the  lung;  -jdorr/p,  the 
stomach]  nerve  (vagus,  or  tenth 
cranial),  769 


Pneumoga>!tric  nerve,  twig  to,  from  facial,  763 

origin,  7(i9 
Poles,  of  eveball,  843 

of  lcn.s,  849 
Ponmm  [an  apple]  Adami,  902 
Pons  [a  bridge]  hejiatis  ['/~«/^  the  liver],  978 
Varolii,  671,  719 
fibres  of,  670 
veins  of,  (i25 
PoDtal  [  pouM,  ponlis,  a  bridge]  arteries,  51 1 
Popliteal  [po])lts,  the  ham]  artery,  the,  .5^6 
surgical  anatomy  of,  1187,  1192 
variations,  586 
bursa',  1226 

lymph  glands,  668  ;  surgical  anatonn-,  1188 
nerves,  external,  814 
internal,  817 
.space,  surgical  anatomy  of,  1186 
vein,  646;  surgical  anatomy  of,  1188 
variations,  647 
Popliteus  [pop/is,  the  ham]  muscle,  371 

minor  muscle,  460 
Portal  [porta,  a  gate]  vein,  634  ;  sinus  of,  (i.35 
tributaries,  6:56 
canals,  983 

li.ssure,  or  transverse,  of  liver.  979 
Portio    [a  part]  major   et    minor  ot"  trigeminal 

nerve,  749 
Post-central  sulcus  of  cerebrum,  68(> 
Posterior  olfactory  lobule,  692 
Postero-lateral  arteries  of  posterior  cerebral,  512 
Postero-median  arteries  of  anterior  cerebral,  513 
['ost-glenoid  tubercle,  35 
Post-olivary  sulcus  of  medulla  oblongata,  721 
Post-parietal  convolution,  686 
Post-]iharyngeal  lymphatic  gland.  653 
Post-sphenoid  centres  of  ossification.  34 

at  birth.  92 
Post-ventricular  veins.  939 
Pouch  of  Doiiglas,  9.">7,  1043,  1044 
laryngeal,  911 
recto-vaginal,  9.")7,  1044 
recto- vesical,  957 
Poupari's  ligament,  404,  1114,  1137.  1174 
Pra'central  sulcus  of  cerebrum,  684 
Pra'cuneus  or  <|Uadrate  lobule  of  cerebrum,  68^J 
Pneinterparictal  bone.  1209 
Prieputium  ditoridis,  1039 
Prajrectalis  muscle  of  Heule,  1068 
Pre-coracoid  cartilage,  115 
Pre-maxillary  centre  of  os.sifi<-ation,  58 
Pre-molar  teeth  (bicuspids),  88 
Pre-i>alatine  centre  of  ossilication.  5*^ 
Pre-patellar  bursa,  surgical  anatomy  of   lls4 
Prepuce,  the,  1033 
Pre-sphenoid  bone.  31;  at  birth.  9:! 

centres  of  ossilication.  34 
Presternum,  104 

Pressure  curves  in  <'ancellous  1>ones.  4 
Preventricular  artery,  473,  936 

veins,  611,  937 
Prevertebral  arterv  of  a.seending  pharyngeal,  481 
fascia,  441,  1106 
plexuses,  great,  834 
Princeps  cervicis  artery,  490 
hallueis  artery,  60l 
pollicis  artery,  543 
Process,  acromion,  112 

angular,  external  and  internal,  47 
auricular  lear-shajwd)  of  sacrum.  17 
of  inferior  tnrbinal  Ixme.  "v? 
clinoid,  anterior,  middle,  and  posterior,  32 
92 


1200 


INDEX 


Process,  ooracoid,  114 

corouoid,  of  ulna,  Vl'l 

of  mandible,  (J4  ;  topography  of,   109G 
costiil,  of  atlas,  8 
of  axis,  9 

of  cervical  vertebrae,  7 
of  seventh  cervical,  lU 
of  s;icrum,  15 
ethmoidal,  of  inferior  tnrbiiial  bone,  53 
falciform,  of  Burns,  llli>< 
frontal,  of  malar  bone,  (Jl 
bamular,  'S.^,  72;  topogiaphy  of,  1096 
of  incus,  long  and  short.  67 
lachrymal,  of  inferior  turbinal  bone,  53 
malar,  of  maxilla,  57 
of  malleus,  Folian,  sliort  and  slender,  67 
mammilhiry  [dim.  of  mamma,  breast],  12 

morphology  of,  24 
mastoid,  37,  73 

maxillary,  of  inferior  turbinal  bone,  53 
of  malar  bone,  <>! 
of  palate  bone,  59 
nasal,  of  maxilla,  57 
odontoid.  9 
olecranon.  122 
olivary,  30.  83 
orbital,  of  malar  bone,  60 

of  palate  bone,  (iO 
petro  sphenoidal,  36 
sphenoidal,  of  palate  bone.  59 
styloid,  37,  67,  73  ;  at  birth.  90 

of  base  of  third  metacarpal,  135 
of  fibula,  158 
of  radius,  127 
of  ulna,  124 
supracondyloid.  119 

of  thyroid  gland,  middle  or  pyramidal,  916 
turbinal,  of  lachrymal  bone,  53 
tympano-hyal,  at  birth,  90 
uncitbrm,  of  ethmoid,  50 

of  unciform  bone,  133 
vaginal,  of  temporal  bone,  38,  73 
vermiform,    of    cerebellum,    superior    and 

inferior,  714 
zygomatic,  of  malar  bone,  61 
Processes,  articular,  of  vertebrae.  5,  6,  8,  9,  12,  13, 
15,  17 
morphology  of,  23 
ciliary,  880 
spinous,  of  vertebra;,  5,  6,  9,  10,  12,  13, 15 

bifid,  11 
transverse,  of  vertebrae,  5,  7,  8,  12,  13,  16, 

17 
morphology  of.  23 
Piocessus  co(;hleariformis,  40 
fuui(;ulo-vaginalis.  1 136 
gracilis  of  malleus,  67 
reticularis  of  cord,  719 
vaginalis  of  peritoneum,  1026,  1031 
Profunda  [j)rofitmhis,  deep]  artery  of  femoral, 
583' 
of  brachial,  inferior  and  superior,  529 
variations,  530 
vein,  647 
Promontory  of  sacrum,  15 
of  tympanum,  39,  912 
Pronator    [])ronus,   face   downwards]  (niadrafus 
[square]  mnsde,  321 
radii  teres  muscle,  313  ;  nerve  to,  791 
Pronephros    [~/>o,   befoie  ;    vnf>i>6(;,  the    kiduev], 

1055 
Pro  otic  ["/'«.  before  ;  olr.  the   ear]     centre   of 
ossification,  43 


Pro.sencephalon,  670  ;  nerve  tracts  in,  717 
Prostate  [~po,  belbre  ;  'iari//ii,  I  .stand],  the.  1021 

sti  ucture  and  functions.  1022 

surgical  anatomy  of,  1126 

veasels  and  nerves  of,  1023 
Prostatic  fissure,  1021 

plexus,  nerve,  837 
venous,  677 

sinu-ses,  1022,  1037 

urethra.  lo37 
Prostatico-vcsical  venous  plexus,  639 
Protuberance,  occipital,  exterual,  25 
internal,  25 
Psoas  [iW",  the  loin]  lymjjh  filands,  662 

(magnus)  nui.scle,  34<i  ;  nerve  to,  8(J2 

parvus  muscle,  348,  460 
Pterion  [--f'/"'^',  a  wing],  the,  48,  71,  1080 
Pterotic  centre  of  ossification ,  43 
Pterygoid  [-rtpif ,  a  wing]  artery,  495 

Ibssa,  33,  59.  73 

muscle,  external,  442  ;  nerve  to,  758 
internal,  444  ;  nerve  to,  757 

notch,  33 

plates,  33  ;  origin  of,  90 

plexus  (venousj,  615 

ridge,  32,  70 

veins,  615 
Plerygoideus proprhis  muscle,  460 
Ptery go-maxillary  fissure.  70 
Pterygopalatine  artery,  496 

canal,  33,  59,  70,  97 

groove,  33 
Pterygo-pharyngeal  artery,  496 
Pterj'go  spinous  ligament,  34 
Fterijffospi)i(>U!<  muscle,  460 
PuVjes  [pi(b('>i(:cns,  covered  with  hair],  the,  142 
Pubic  arch,  146 

artery,  of  deep  epigastric,  578 
of  obturator,  572 

ligaments,  205,  206 

portion  of  fascia  lata  of  thigh,  1119 

spine,  143 
Pnbo-prostatic  ligaments,  1018 
Pudendal  [piidco,  I  am  ashamed]  nerve,  long, 

812 
Pudic  Ipudeo,  I  am  ashamed]  arteiy,  accessory, 
570 
external,    superficial     and    deep,    583, 

1126 
internal,  573,  1067  ;  topography  of,  1181 

lymphatics,  106? 

nerve,  812 

vein,  6:58,  1067 
Pulmonaiy  [piilmo,  lung]  artery,  462,  923 
orifice  of,  935 
topography  of,  935 
in  foetus,  463 
after  birth.  463 

lymph  glands,  <>58 

nerves,  anterior,  773 

plexvis,  ])osterior,  773 

sinuses  (of  Valsalva!,  468,  932 

valves,  932;  topography  of  935,  1113 

veins,  the,  602 
Pulvinar  [a  (cushion],  705 
Puncta  cruenta  (vel  va.sculosa),  689 

lachrymalia,  867 
Punctum  [a  i)oint]  lachrymale,  875 
Pupillary  /one  of  iris,  810 
Putamen  [a  shell  or  husk],  699 
Pyloric  artery,  inferior.  5.')7 
superior,  556 

orifice  of  stomach,  960 


INDEX 


1261 


Pyloric  plexus  (nerve),  835 

vein,  636 
Pylorus  [irv/upui:,  a  gatekeeper],  the,  960 
Pyramid  of  cerebellum,  715 

of  tympanum,  posterior,  40,  876 
Pyramidal   l)()dy  of  medulla,  722 

process  of  thyroid,  916 

tracts  of  cord,  auterior  and  lateral,  741 
Pyramidalis  abdominis  muscle,  402 

nasi  muscle,  432,  892 
Pyramids  of  Ferrein,  1011 

of  Malpighi,  1010 
P3'rilbrmis  \_pirus,  a  i>ear]  muscle,  355 


Quadrate  artery  of  anterior  cerebral,  503 
cartilage  of  nose,  accessory,  891 
lobe  of  cerebellum,  754 

of  liver,  978 
lobule  of  cerebrum  (prajcuueus),  714 
Quadratus  [square]  femoris  muscle,  358 

lumt)orum  muscle,  410;  nerve  to,  803,  810 
mcnti    {^quadnitus,    square ;    mcntum,    chin] 
(depressor  labii  iuferioris),  439 
Quadriceps  extensor  femoris  muscle,  365 
nerve  to,  808 


Radial  artery,  in  forearm,  538 

surgical  anatomy  of,  1161 
variations,  540 
in  the  palm  (deep  pahnar  arch),  543 

variations,  543 
at  the  wrist,  541 
carpal,  anterior  and  posterior,  541 
recurrent,  540 
condyle  (external)  of  humerus,  120 
nerve,  796;  surgical  anatomy  of,  1162 
vein,  superficial.  641 
Radialis  indicis  artery,  .544 
Radio  carpal  joint,  ligaments  of,  234 

movements  of,  235 
Radio-ulnar  joints,  inferior,  232 
middle.  230 
superior,  230 
Radius  [a  spoke],  the,  126 
ossification  of,  128 
movements  of,  on  ulna,  233 
Rami  [plural  of  ramits]  commuuicantes  of  gan- 
glia ted  cord,  lumbar,  833 
thoracic,  832 
of  middle  and  inferior  cervical  ganglia,  830 
of  superior  cervical  ganglion,  828 
of  sympathetic  system,  white  and  grey,  827 
Ramus  [a  branch]  of  ischium,  141 
of  mandible,  63 
occipitalis  of  cerebrum,  686 
parietalis  of  occipital  artery,  674 
of  pubes,  descending,  142 
horizontal.  143 
subcutaneous  malic,  754 
Ranine  [rana,  a  frog]  artery,  485 
Raphe  [Ano//,  a  .seam]  of  corpus  callosum,  693 
median,  of  tongue,  884 
of  the  scrotum,  1023 
Receptaculum  [a  vessel]  chyli  [^i'/ or,  juice],  659 
Recess  of  ischio  rectal  tbssae,  anterior  and  pos- 
terior, 10(5.3 
pharyngeal.  951 
tonsillar.  944 
Recessus  in  fundi  bnli,  708 

Rectal   (hiemorrhoidal)  artery  of  lateral  sacral, 
567 


Rectal  arterv,   middle  (middle  ha.'morrhoidal), 
570 
of  middle  sacral,  56:5 
examination  in  the  female,  1128 
triangle,  1122 
Recti  [rictus,  straight]  muscles  of  orbit,  856 
Recto-uterine  ligaments,  1049 
Recto-vaginal   p()ucli  of  |)eritontum.  975,  1044 
Recto-vesic:il   fiuscia,  IOIh 

pouch  of  peritoneum,  975 
Rectum  [rrdnn,  straight],  the,  974 
lymi»hati(s  of,  662 
surgical  anatomy  of,  1127 
Rectus  abdominis  muscle.  402  ;  sheath  ol,   110 
capitis  auticus  major  muscle,  456 
nerve  to.  7^5 
vieiliun  muscle,  461 
minor  nuiscie,  457 
nerve  to.  785 
lateralis  mu.scle,  425 

nerve  to,  785 
posticus  major  muscle,  424 
minor  mu.scle,  424 
femoris  muscle.  36() 
stcrnalia  nui.scle,  461 
Recurrent  arteries  of  deep  palmar  arch,  545 
interosseous,  535 
radial,  540 

tii>ial,  anterior  and  posterior,  598 
ulnar,  anterior  and  jiosterior,  5.3.3 
nerves,  articular,  of  external  popliteal,  815 
laryngeal,  772 

meningeal,  of  mandibular.  756 
of  maxillary,  754 
of  vagus,  772 
Recussus  [rccutio.  a  recoiling]  piuealis,  706 
Red  (tegmental)  luuleus,  711 
Regions  of  the  abdomen,  1206 
Keissner,  membrane  of,  883 
Renal  [_rin,  the  kidney]  arteries,  .560 
variations,  560 
topograi>hy  ot,  1121 
of  lumbar,  554 
duct,  1014 
lymphatics,  665 
plexus  (nerve),  835 
veins,  631 
Reproductive  organs  in  the  female,  1038 

in  the  male,  1021 
Respiration,  organs  of,  920 
Kestiform  [reslix.  a  cord]  bo<ly  of  iKins,  72.3 
Rete  [a  net],  carpal,  anter.  and  i>osterior.  534 

testis,  1026 
Retina  [rete.  a  net],  844,  848 
Retinacula  [rctinere,  to  hold  back]  of  capsule  of 

hip,  247 
Retinal  arteries,  851 

pigment  layer,  844 
Retrahens  [retraho,  I  draw  back]  aurem  muscle, 

432 
Revehent  nerve  (grey  ramus  communicans),  826 
Rhinencejihalon.  684 
Ilhomho-iilloidcus  muscle,  461 
Rhomboid  [/»o//,3"f.  a  rhomb]  depression,  110 
ligament,  218  ;  origin  fr<)msubclavius,  281 
Rhomboideus  major  mustlf,  292 
minor  muscle,  292 
Rhomboids,  nerve  to,  787 
Ribs,  the,  98 

bicipital.  104 

cervical.  1(13  ;  variations  in,  104 

devtlopment  of,  103 

lumbar,  104 


1262 


INDEX 


Ribs,  peculiar,  100 

variations  in  number  and  sbape,  103,  1210 
Kidge,  basixl,  of  teetb,  87 

external  condylar,  118 

gluteal,  of  femur,  147 
of  hip  bone,  139 

ilio-pubal,  139,  143,  146 

interosseous,  of  tibula,  I.kS 

oblique,  of  iufraspiuous  fossa,  111 
of  ulna,  125 
of  tibia,  156 

supracondyloid,  119 

of  trapezium,  132 
Rinia  [a  chink]  glottidis,  911 

pudendi,  l(t.')9 
King,   abdominal,   external,   1114,  1131  ;    effect 
of  position  on,  1132 
internal,  1115,  1134 

femoral,    1139 ;    position  of  vessels  round, 
1139 
Rings,  cartilaginous,  of  trachea,  913 
Risorius  [rWfo,  I  laugh]  muscle,  437 
Rivini,  notch  of,  40,  874 
Kivinian  segment  of  tympanum,  874 
Riviuus,  duct  of,  949 
Rolandic  point,  inferior,  1089 
Rolando,  fissure  of,  682,  1089 ;  development  of, 
682 

tubercle  of,  723 
Roof  bones  of  skull,  24 
Roots  of  auditory  nerve,  765 

of  glosso-pharj'ugeal  nerve,  767 

of  lenticular  ganglion,  752 

of  lung,  structures  forming,  960 

of  Meckel's  ganglion,  755 

of  olfactory  nerve,  745 

of  optic  nerve,  746 

of  otic  ganglion,  760 

of  penis,  1031 

of  spinal  nerves,  740,  776 

of  tooth,  86 

of  trigeminal  nerve,  749 
Rosenmiiller,  fossa  of,  952 

organ  of,  1214 
Rostrum  [a  beak]  of  corpus  callosum,  693 

of  sphenoid,  30 
Rotation  of  intestinal  canal,  995 
Rotator  humeri  muscle,  461 
Rotatores  spinse  muscles,  423 
Round  ligament  of  liver,  982,  1213 

of  uterus,  1050,  1213 
Rugae  [wrinkles]  of  vagina,  1043 


Sac,  lachrymal,  868 
pleural,  920 
of  peritoneum,  greater,  955 

lesser,  955,  957 
Saccule  [dim.  of  saccus,  a  bag],  the,  881 
Sacral  [sacer,  sacred]  aorta,  see  Sacral  arteries, 
middle 
arteries,  lateral,  superior  and  inferior,  567 
of  middle  sacral,  563 
middle,  564  ;  variations,  564 
cornua,  15 
foramina,  15 
groove,  16 
lymph  glands,  661 
nerves,  fourth,  809 
plexus,  809 

primary  divisions  of,  anterior,  809 
posterior,  782 
portion  of  gangliated  cord,  833 


Sacral  promontory,  15 
veins,  lateral,  638 
middle,  634 
vertebiic,  24 
Sacro-coccygeal  articulation,  204 

ligaments  of,  204  ;  morphology  of,  281 
Sacro-iliac   articulation,  or  synchondrosis   [oi'v, 

together;  ,i:"»"W>  cartilage],  200 
Sacro-lumbalis  (ilio-costalis)  muscle,  415 
Sacro-lumbar  ligament,  199 
Sacro-vertebral  angle,  199 

diiTerences  in  male  and  female,  200 
measurements  of,  200 
Sacrum  [aacer,  sacred  :  the  bone  was  offered  as  a 
sacrifice  by  the  ancients],  the,  14' 
morphology  of,  24 
ossification  of,  22 
sexual  diflereuces  in,  17 
Sagittal    [saffitta,   an  arrow  :    from   its   straight 
direction]  axis  of  eyeball,  843 
layer  of  trans  versus  perimei  muscle,  1106 
section  of  brain,  definition  of,  671 

of  skull,  81 
sinuses   (longitudinal)  of  cranium,  inferior, 

619  ;  superior,  618 
suture,  44 
Salivary  glands,  the,  946 
Santorini,  cartilages  of,  905 
fissures  of,  871 

plexus  of  (female  urethra),  1042 
Saphenous  [from   Arabic  al-srifiti,    hidden  ;   less 
probably  from  aa<pt/v//g,  manifest]   artery, 
585 
lymph  glands  (superficial  femoral),  667 
nerve,  long  or  internal,  808 

sliort  or  external,  817  ;  varieties,  817 
opening,  345,  1138,  1177 
veins,  long  (internal),  644 
short  (external),  644 
topography  of,  1191,  1188 
Sappey,  orbito-palpebral  muscle  of,  859 
Sartorius  [sartor,  a  tailor]  muscle,  350  ;  nerve  to, 

808 
Scala  [a  staircase]  tympani,  42,  881 

vestibuli,  42,  881 
Scaleni,  nerve  to,  785,  788 

Scalenus    [aKa},7)v6c,    of  unequal   sides]    anticus 
muscle,  454 
medius  muscle,  455 
posticus  muscle,  455 
Scalp,  lymphatics  of,  superficial,  649 
surgical  anatomy  of,  10H4 
topography  of  vessels  of,  1085 
Scalp    and     face,     superficial     veins 
anterior,    612  ;     lateral,    615  ; 
614 
cutaneous  nerves  of,  819 
Scapho-cuneiform  articulation.  272 
Scaphoid  [aKCKpij,   a  boat  ;    cidor^   like  :  from  its 
sha])e]  carpal  bone,  129 
fossa,  33,  73 

of  helix  of  auricle,  871 
tarsal  bone,  166  ;  ossification,  167 
Scapula  [probably  from  aKarravr/,  a  spade],  the, 
111 
arterial  anastomoses  of,  1146 
morphology  of,  115 
muscles  of,  surgical  anatomy  of,  1146 
ossification  of,  114 
Scapular  ligaments,  221 

notch,  111 
Scarpa's  foramina,  57,  72,  97 

triangle,  surgical  anatomy  of,  1175 


of.     611  ; 
posterior. 


I 


LXDEX 


1263 


Schneiderian  meiiil)iane,  Hi);i 
Sciatic  ['ffV'oi',  the  liip]  artery,  (Ml  ■  tDpognipliv 
of,  1181 
nerve,  great.  814  ;  topography  of,  llsi 

small,  sll 
notch,  gi-eater.  14tt 

lesser,  1  lU 
veins,  6;i8 
Scleral  sulcus,  841 
Sderotit;  [aK/i/jmr^  hard],  the,  845 
Scrotum  [a  skin],  cutaneous  nerves  of,  S'l'.i 
integument  of,  1U23 
Ij'mphatics  of,  (j(jl 
septum  of,  \{)'2:i 
vessels  and  nerves  of,  1024 
Sebaceous  glands,  1077 

Second  cervical  nerve,  anterior  primarv  division 
of,  782 
posterior  primary  division  of,  7S0 
cranial  (optic)  nerve.  746 
division  (maxillary)  of  fifth  nerve,  7"):} 
rib,  101 
Semicircular  canals,  external,  40,  41 ,  880 
posterior,  41,  880 
superior,  .■)7,  41,  880 
Semilunar  bone,  120 

cartilages  of  knee,  external,  258 
internal,  258 
fold  of  conjunctiva,  84:5 
ganglia,  8:J5 

valves,  aortic,  93'.i  ;  topography  of,  Ool? 
pulmonary,  932  ;  topography  of,  034 
Semi-membranosus  muscle,  3(54 
Semi-spinalis  colli  muscle,  422 

dorsi  muscle,  420 
Semi  tend inosus  muscle,  364 
Sensory  nucleus  of  glosso-pharyngeal  nerve,  767 

accessory,  of  trigeminal,  750 
Septal  artery,  ascending,  496 
cartilage,  H91 

nerve  of  i\Ieckel's  ganglion,  755 
of  nasal,  752 
Septum  {_sepio,  I  hedge  in],  auricular,  931 
artery  of,  496 
fibrous,  of  tongue,  888 
lucidum,  702 
nasi,  79,  891 
pectiniforme,  1033 
posticum,  of  spinal  arachnoid,  774 
scroti,  1023 
ventricular,  968 
Serratus  [serra,  a  saw]  magnus  inuscle,  298 
posticus  inferior  muscle,  413 
superior  muscle,  411 
Sesamoid  [_a>'/aafioi\  a  small  seed,  .sesame  ;  f((Sof, 
like]  bones  of  great  toe,   280 
bones  of  interphalangeal  joint  of  great  toe, 
2H0 
of  thumb,  245 
cartilages  of  nose.  891 
grooves  on  head  of  first  metacarpal,  134 
of  first  n\etatarsal,  170 
plate,  plantiir,  279 
Seventh  cranial  (facial)  nerve.  7(il 
Sheath,  femoral,  1139 

of  optic  nerve  in  orbit,  861 
of  parotid,  1091 
Shoulder  joint,  ligaments  of,  222 
movements  of,  22(i 
muscles  in  relation  to,  225 
relation  of  bicei)s  tendon  to,  226 
cause  of  roundness  of,  1150 
surface  markings  of.  1149 


SKL' 

Sigmoid  [from   its  likeness  to  the  (ireek  letter 
N/V/m/(]  artery,  562 

cavity  of  radius,  127 

of  ulna,  greater.  122 
le.s.ser.  123 

fiexure  of  colon.  973 

notch  of  mandible,  (!1 

sinus,  622 
Sinus  [a  hollow]  ul;e    jmrvie.  m  >|.hiii(i  u.n  iiiaj, 
623 

of  aorta,  46H 

basilar,  621,  (i72 

cavernous,  660,  (i72 

circular,  621,  672 

inferior,  of  Winslow,  621 

coronary,  of  heart.  929,  937 

of  galactoi)horous  ducts,  1072 

of  (iuerin,  1o:{m 

jugulari.s,  622 

of  kidney,  lo05  ;  structures  Iving  in.  lOlO 

lateral,  (J21,  672 

longitudinal,  inferior,  620,  672 
sui)erior,  619,  672 

of  Morgagui,  951 

oblique,  of  heart.  925 

obli(|uus,  or  straight.  620.  672 

occipital,  620,  (J72 

pedis,  163 

perpeudicularis,  or  straight.  (i20.  672 

petro.sal,  inferior  and  superior,  (i22,  711 

petrosquamous,  623 

])ocularis,  1037,  1215 

of  ])ortal  vein.  ()34 

jjviiformis  of  larynx,  910 

rectus,  or  straight,  620,  (J72 

rhomboidalis,  737 

sagittal,  or  longitudinal,  inferior,  619.  672 
superior,  618,  672 

.sigmoid,  622 

spheno-parietal,  623,  672 

straight,  620,  672 

teutorii,  or  straight,  620,  672 

transverse.  621.  672 

uro-genital,  1055 

venosus,  or  atrium,  928 
Sinuses,  ethmoidal  tcells),  50 

frontal,  47,  1082 

intercavernous,  621 

marginal,  620 

mastoid  (cells),  40,  1082 

nas;il,  73,  79 

prostatic,  1021,  1037 

sphenoidal,  30,  80,  1083 

of  Valsalva,  or  pulmonary,  4(>8,  932 

venous,  of  cranium,  619 
Sixth  cranial  (abducent)  nerve.  760.  863 
Skin,  1073 

api)endages  of,  1077 

nerves  and  ves.sels  of,  1076 

structure  of.  1074 
Skull,  anterior  aspect  of,  73 

base  of,  exterior,  72 
regions  of,  73 

8ub<ninial,  73 
subocciiiital.  7:*. 
zygomatic,  7:{ 

at  birth.  90 

bones  of  (cla&sificationl.  24 

exterior  of.  ()9 

lateral  asj>oct  of,  70 
jtosterior  asjK»ct  of,  70 
superior  asjicct  of,  6'9 

interior  of.  81 


1204 


INDEX 


Skull,  interior  of.  base  of  (floor),  82 
fossa;  of,  anterior,  ^"2 
micWle,  83 
posterior,  86 
section  of,  coronal,  81 
horizontal,  i^'i 
sagittal,  81 
fcetal,  general  characters  of,  90 
nerve  tbraniina  of,  9() 
Skull-cap,  average  thickness  of.  1093 

nieasureaicnts  of  (average),  H6 
Slender  lobe  of  cereV)elluni,  715 

process  of  malleus,  67 
Small  lavernous  nerve,  S\iS 
deep  petrosal  nerve,  828 
intestines,  lymphatics  of,  664,  969 
blood-supply.  969 
nerve-supph',  969 
structure  of,  968 
occipital  nerve,  783:  topography  of,  1103 
(posterior)  palatine  nerve,  756 
sacro-sciatic    ligameut,    202  ;    origin    from 

coccygens,  2'^1 
sciatic  nerve.  811 
Smallest  splanchnic  nerve,  831 
Smegma  prteputii,  1032 
Snutf-box  space  of  hand,  1172 
Socia  [a  companion]  parotidis,  947 
Soemmerring,  nerve  of,  or  long  pudendal,  812 
Soft  palate,  943 

parts  cut  in  paring  edges  of  cleft,  1097 
Solar  [.so/,  the  sun]  plexus,  835 
Soleus  [w/«j,  asoletish]  muede,  372 
Solitary  glands  of  intestine,  968 
Space,  epicerebral,  678 
epispinal,  678 

intervaginal,  of  optic  nerve,  861 
Meckel's,  673 
perforated,  anterior,  706 
posterior,  679 
subarachnoid,  670,  678 
of  optic  nerve,  861 
subdural,  675,  678 

of  optic  nerve,  861 
Tenon's,  860 
Spaces,  lymphatic,  of  eyeball,  862 
of  Fontana,  846 
of  orbit,  864 
Spermatic    [cr-tpaa,    seed]   artery,   561  ;    varia- 
tions, 561 
cord,  1030  ;  constituents  of,  1030 
fascia,  middle  and  internal,  1023,  1024,  1131 
plexus  (nerve),  837 
veins,  6.32 
Spermatozoa   [c-ip/ia,  seed  ;   C"ov,  an  animal], 

1027 
Spheno-etlimoidal  cells,  50 

Sphenoid  [^yp'/i;  a  wedge  ;  e'li^og,  like  ;  from  its 
wedging   in   the  other  bones  of  the 
skull]  bout",  the,  29 
o.ssification  of.  34 
at  birth,  92 
Sphenoidal  artery  of   pterygo-palatine,  496 
of  .spheno-paiatine,  496 
crest,  30 

fissure,  31,  77,  83,  97 
process  of  palate,  59 
sinuses,  30,  80,  10H3 
turbinal  bones,  51  ;  at  birth,  94 
Spheno-malar  fissure,  78 
foramina,  71,  78,  97 
suture,  71 
Spheno-mandibular  (maxillary)  ligament,  180 


Spheno-maxillary  fissure,  70,  78,  97 
fossa,  70 
ligament,  180 
Spheno-paiatine  arterj',  896 
foramen,  59,  70,  80,  97 
ganglion  (Meckel's),  755 
nerves,  754 
notch,  60 
vein,  616,  896 
Sphenoparietal  sinus  of  cranium,  623,  672 

suture,  71,  83 
Sphenotic  [aoi/v,  a  wedge  ;  ovg,  the  ear]  cartilage, 
89 
foramen,  73,  83 
Sphincter  [aciiyyu,  I  bind]  ani  extern  us,  .1059 
ani  internus,  975,  1059 
iridis,  848 
Sphincter  vesica*  internus,  1019 
Spigelian  lobe  of  liver,  1078 
Spinal  accessory  nerve,  773  ,  topography  of,  1103 
arteries,  anterior,  lateral,  and  posterior,  511 
of  aortic  intercostals,  549 
of  deep  cervical,  519 
of  inferior  thyroid,  514 
of  lateral  sacrals,  568 
column,  17  ;  curves  of,  19 

os.siticatiou,  19 
cord,  the,  731 

arachnoid  of,  732 
dura  mater  of,  731 
external  character  of,  734 
internal  structure  of,  737 
pia  mater  of,  733 
tracts  of,  737 
nerves.  776 

classification  and  number,  778 
deep  origin  of,  736 
general  distribution,  778 
primary  divisions,  anterior,  782 
posterior,  779 
roots  of,  737,  776 
topography  of,  777,  1145 
plexus,  venous,  anterior  and  posterior,  629 
portion  of  spinal  acces.sory,  773 
veins,  628 

longitudinal,  anterior  and  posterior,  630 
Spinalis  doi-si  muscle,  419 
Spine,  alar,  32,  73 
bones  of  the,  5 
ethmoidal,  30,  83 
frontal,  anterior,  47,  80 
posterior,  59,  80 
iliac,   anterior    and   posterior   inferior   and 

superior,  139 
mandibular,  03 
nasal,  44 

of  palate  bone,  59,  80 
pubic,  143 
of  scapula,  112 
of  tibia,  153 
Spino-glenoid  ligament,  222 
Spiral  canal  of  modiolus,  42,  880 
lamina,  osseous,  41 
line  of  femur,  147 
Splanchnic   [a-Aayx'or,  a  viscus]   nerve,  great, 
831 
lesser,  831 
smallest,  831 
Spleen  la-'/./jr,  the  spleen],  the,  988 
size  and  vaiieties  of,  990,  991 
structure,  relations,  and  blood-  and  nerve- 
supply,  991 
topography  of,  1120 


I 


A 


LXDEX 


1265 


SPL 

Splenial  [splenium,  a  pad]  centre  of  ossification 

iu  mandible,  64 
Splenic  artery,  'h)7  ;  variations,  ooS 
of  left  phrenic,  ooIJ 

lymphatics,  665 

nerve  plexus,  833 

vein,  637 
Splenium  [a  pad]  of  corpus  oallosum,  692 
Splenius  [a-'/Jiviov,  a  bandajie  :   from  its  binding 
down  other  muscles]  capitis  muscle,  414 

colli  muscle,  414 
Spongy  i)ortion  of  urethra,  1037 
Spot,  yellow,  of  eye,  >S43 
Squamo-mastoid  furrow,  38 
Squaino-occipital  bone,  25 
Squamo-sj)lienoidal  suture,  71,  83 
Squamosiil  portion  of  temporal  tjone,  35 

at  birth,  93 
Squamous  {^squama,  a  scale]  suture.  44,  71,  83 
Stapedic  [stujjes.  a  stirrup]  artery,  490 
Stapedius  muscle,  878  ;  mrve  to,  763 
Stapes  [a  stiirup],  68  ;  origin  of,  90 
Stars  of  Verlieyen,  1011 
Stellate  figures  of  lens,  849 

(anterior  costo  central)  ligament,  208 
Stenson's  canals,  57 

duct,  949 

foramina,  72 
Stephanion  [crr/oaioc,  a  crown],  71 
Sternal  abnormalities,  107 

artery  of  internal  mamniarj',  517 

end  of  clavicle,  110 
of  ribs.  98 

lymphatic  glands,  657 
Sternal i.i  muscle,  461 
Sternebiaj,  104 

Sterno-davicular  articulation,    216 ;    structures 
behind,  1108 

layer  of  deep  cervical  fiiscia,  1100 
Sterno-cleido-mastoid    [^■/.e''f,   a    key,    clavicle] 
muscle,  445  ;  nerve  to,  785 
surgical  anatomy  of,  1099 
Sternohyoid  muscle,  447 

Sterno-mastoid  artery,  inferior,  of  suprascapular, 
514 
of  occipital,  489 
of  superior  thyroid,  482 

lymphatic  glands,  649 
Sterno  periciirdial  bands  or  ligaments,  925 
Sterno-thyroid  muscle.  448 
Sternum  [crrtin'ov,  the  breast  or  chest],  the,  104 

blood-supply  and  development  of,  106 

cleft,  108,  1210 

ossification  and  abnormalities  of,  107 

in  the  young  subject,  104 
Stomach,  the,  960 

alterations  of  position,  962 

lymphatics  of,  662,  964 

nerves  and  blood-supply  of,  964 

structure,  963 

topography  of,  1118 
Straight  convolution  (gyrus  rectus),  685 

sinus  of  cranium,  620 

sulcus  (olfactorj-l,  685 
Stratum  basilare,  1075 

corneum,  1075 

granulosum.  1075 

lucidum,  1075 

IMalpighii,  1075 

zonale,  743 
Stria  [a  stripe  or  streak]  pinealis,  705,  747 

terminalis,  700 
Strii«  acustica;,  719 

80 


Striic  longitudinalcs,  734 

medullares,  719 
Styloglossus  muscle  [from  attachment  to  styloid 

and  tongue,  yz-ojaaal^,  453 
Stylo-hyoid  muscle,  450 ;  nerve  to,  76 1,  775 
Styloid  [Tri/oij  a  pen  ;  «('!of,  like]  Imne  of  car- 
pus (occasional),  137 
process,  37,  67,  73 
at  birth,  90 

morphology  and  development  of,  90 
segments  of  67 

of  base  of  third  metacarjjal,  135 
of  fibula,  158 
of  radius,  127 
of  ulna,  125 
Stylo-mandibular  (maxillary)  ligament,  180 
Stylo-mastoid  artery,  490,  878 

foramen,  37,  73,  97 
Stj'lo-maxillary  (mandibular)  ligament,  180 
Stylo-pharyngeus  muscle,  951  ;  nerve  to,  769 
Subanconeus  muscle,  310 

Subaponeurotic  connective  tissue  of  .'^calp,  1084 
Subarachnoid  space,  cerebral.  676,  678 
spinal,  734 
tissue,  cerebral,  676 
.spinal,  734 
Subcapsular  epithelium  of  lens,  850 
Subclavian  artery,  the,  505.  1113 
first  iwrtion,  505 
second  portion,  506 
third  portion,  507 
variations,  508 
of  suprascapular,  514 
lymphatic  glands.  655 
vein,  643  ;  variations  and  tributaries,  643 
Subclavius  muscle,  296  ;  nerve  to,  788 
Subcostal  angle,  109 

arterj^  (last  dorsal),  550 
groove,  99 
vein,  60H 
Subcranial  region  of  basis  cranii,  73 
Subcrureus  muscle,  367 
Subdural  space,  675.  678 
Sublingual  artery,  4K5 
duct  (Riviuf's),  949 
fossa.  63 
ganglit>n.  760 
gland,  949,  1085 
Submandibular  (submaxillary)  ganglion,  760 
Submaxillary  artery,  4^7 
duct  (Wharton's),  948 
fossa,  63 

ganglion  (submandibular).  760 
gland  (submandibular),  948 

viv«cular  and  nerve  supply  of,  948 
lymph  glands.  6.")0 
triangle  of  neck,  1101 
vein,  614 
Sabment;il  artery,  487 

vein,  614 
Subnasal  point,  81 
Suboccipital  lymphatic  glands,  649 

region  of  basis  cranii.  73 
Subperitoneal  artery-  of  <'onimon  iliac,  565 

connective  tissue.  958 
Subsartorial  nerve  plexus,  807 
Subscapular  artery,  524  ;  variations,  525 
of  j>osterior  scapular.  516 
of  .suprascapular.  515 
fossa,  111 

lymphatic  glands,  655 
nerves,  lower,  middle,  and  upjur,  788 
vein,  64.3 


1266 


L\DEX 


SUB 

Substapnlaris  muscle,  o03 
Substantia  lenugiuea,  719 
gelatiuosa  centralis,  738 

Rolamli,  737 
nigra  of  crura  cerebri,  G7i 
reticularis  alba,  GUI 
spongiosa,  "i'.W 
Subthalamic  body,  710 
Subtrapezial  nerve  plexus,  785 
Sudoriparous  glands,  1077 
Sulcus  [a  I'urrow] — 

of  cerebellum,  cerebelli  superior,  715 
lateralis  dorsalis,  7'-Jl 
ventral  is,  72 1 
longitudiualis  medianus,  719 
paramedianus  doi-salis,  721 
parapyramidalis,  721 
post-olivary,  721 
of  cerebrum,  central,  (i82 
centralis  insulae,  688 
choroideus,  705 
circularis  Keilii.  688 
fronto-marginalis,  684 
occipitalis  anterior,  728 
oltactory  (straight),  685 
paracentral  is,  689 
ix»st-central,  686 
prae-central,  684 
subparietalis,  685,  689 
lachrymal,  53 
scleral,  84 
of  spinal  cord,  longitudinalis  posterior,  734 

paramedianus  dorsalis,  734 
termiualis,  1213 
Superciliary  IsupeiciUuin,  eyebrow]  ridge,  47,  73 
Supinator  [sj(j>(H«s,  face  upwarcTs]  longus  muscle, 
(see  Brachio-radialis),  321  ;  nerve  to,  795 
radii  brevis  muscle,  328 
Supra-acromial  nerves,  784 
Supraclavicular  nerves,  784 
Supraclavicuhiris  muscle,  461 
Supracondyloid  process,  119,  1211 

ridge,  119 
Supracornual  ligament  of  coccyx,  205 
Supra-hj'oid  lymphatic  glands,  650 

triangle,  1101 
Supramandibular  (supramaxillary)  nerve,  765 
Supramarginal  convolution,  686 
Supramastoid  crest,  35,  37 
Supra-occipital  segment  of  squamo-occipital  bone, 

25 
Supra-orbital  artery,  500 
foramen,  47 
nerve,  796 
notch,  47 
ridges.  47 
vein,  613,  616 
Suprarenal  arteries,  inferior,  560,  561,  1014 
middle,  561,  1014 
superior.  553.  1014 
bodies,  1013 

accessory,  1013 
structure,  1014 
vessels  and  nerves,  1014 
lymphatics,  665 
nerve  plexus,  835 
veins,  632,  1014 
Suprarimal  portion  of  lar^'nx,  911 
Supra.scapular  artery,  514 
foramen,  113 

ligament  (transverse),  221 
nerve,  787 
notch,  113 


Suprascapular  vein,  617 
Supra-spinatus  muscle,  301 
Supraspinous  artery  of  iwsterior  scapular,  516 
of  suprasc;ipular,  515 
fossa,  111 
ligaments  of  coccyx,  205 

of  vertebric,  195 
Suprasternal  artery  of  suprascapular,  514 

nerves,  784 
Supratrochlear  artery,  514 
foramen,  120,  1211 
fossa,  47 
nerve,  752 
Sural  [sura,  the  calf  of  leg]  arteries,  588 
Surgical  neck  of  humerus,  117 
Surgical  and  topographical  anatomy  of — 
abdomen,  the,  1114;  regions  of,  1206 
abdominal  ring,  external,  404,  1114,  1132 

effect  of  position  on,  1132 
internal.  411,  1115 
amputations  of  leg,  arteries  cut  in,  1192 
ankle,  the,  1198 
annular  ligaments  of  ankle,  1196  ;  of  wrist, 

anterior,  1168  ;  posterior,  1169 
anterior  tibial  artery,  1192 
nerve,  1200 
anus,  1127 

aorta  and  iliac  arteries,  1121 
arches  of  the  foot,  1200 
arm,  the,  1152 
axilla,  1150 
back,  the,  1142 

of  wrist  and  hand,  1172 
biceps  muscle,  1153 
l)icipital  groove,  1150 
brachial  arterj^  1153 
brachialis  auticus  muscle,  1154 
bursa;  of  foot,  1 1 99 
buttocks,  the,  1180 
cceliac  artery,  1121 
coraco-brachialis  muscle,  1150 
crural  arch  (Poupart's  ligament),  1137 
cutaneous  nerves  of  forearm,  1163 
deep  cervical  fascia,  1103 

crural  arch,  1138 
deltoid  muscJe,  1151 
diaphragm,  1116 
dorsal  artery  of  foot,  1200 
elbow,  the,  1155 

arterial  anastomoses  around,  1157 
veins  in  front  of,  arrangement  of,  1157 
eyelids  and  lachrymal  apparatus,  1092 
face,  1090 
fascia  lata  of  thigh,  1116 

pubic  and  iliac  portions  of,  1119 
fascisE  and  sheaths  of  hand,  1169 
female  external  genitals,  1129 
femoral  arterv,  1175 
canal,  1139 
ring,  1139 

position  of  vessels  around,  1139 
sheath,  1139 
foot,  the,  1198 
forearm,  the,  1159 
fossa;    on    jiosterior   surface    of   abdominal 

parietes,  1117 
gall  bladder,  1117 
gluteal  artery,  1181 
great  sciatic  nerve,  1181 
head  and  face,  1091 
heart,  relation  to  the  chest  wall,  1113 
hernia,  femoral,  course  of,  1139 
coverings  of,  1140 


IXDKX 


12(;7 


Surgical  and  topographical  auatomy  of — 
hernia,  parts  concerned  in,  li:{7 
inguinal,  coverings  of,  1134 

causes  of,  1136 

parts  concerned  in,  1131 
unil)ilical,  coverings  of,  1141 

parts  concerned  in,  1141 
hypogastric  arteries  (obliterated),  1135 
inguinal  canal,  1115,  1132 
interosseous  arteries  of  arm,  1163 
intestines,  large  and  small,  111- 
iscliio-rectal  fossa,  1127 
jugular  vein,  external,  1103 
kidneys,  1119 
knee,  "the,  1182 
latissimus  dorsi  muscle,  1142 
leg,  the,  1188 
linea  alba,  1114 

semilunaris,  1114 
Lisfranc's  or    He\ 's    amputation,    lines   of 

incision  for,  119!) 
liver,  1117 

lower  extremity,  1172 
lumbar  fascia,  1146 
lungs,  outlines  and  relations  to  chest  walls, 

1111 
mamma,  the,  1110 
manubrium,  parts  behind,  1111 
median  nerve,  1154,  1161 
mesenteric  arteries,  1121 
mouth,  the,  1095 

musculocutaneous  nerve  on  foot,  1200 
musculo  spiral  nerve,  1154 
nares.  posterior,  1097 
neck,  the,  1099 

triangles  of,  anterior,  1101 

carotid,  inferior  and  superior,  1102 

posterior,  1102 

submaxillary  (supra-hyoid),  1101 
nose,  1097 
palate,  soft,  1097 
palmar  arch,  deep,  1168 

superficial,  1167 
fascia,  1169 
pancreas,  1118 
parotid  gland,  1091 
patella,  the,  1182 

pectoralis  major  et  minor  muscles,  1150 
pelvic  fascia,  1129 
periuseum  and  genital.s,  1122 

triangles  of,  1122 
peroneal  arterj',  1188 
peronei  muscles,  1197,  1205 
plantar  arteries,  1202 

fascia,  functions  of,  1203 
pleura,  relations  to  chest  wall,  1112 
popliteal  space,  1186 

vessels,  1187 
Poupart's  ligament,  1116,  1137 
prostate,  1126 
pudic  arteiy,  1181 
radial  artery,  1161 

nerve,  1162 
rectum,  1127 
saphena  veins,  1181 
saphenous  nerves,  1200 
scalp,  the,  1084 
scapula,  muscles  and  arterial  anastomoses, 

1146 
sciatic  artery,  1181 
shoulder,  the,  1149 

skin  folds  or  creases  of  the  palm,  1165 
spinal  accessor}'  nerve,  1103 


Surgical  and  tojxjgraphical  anatomy  of— 
.spinal  nerves,  origin  of,  1145 
spleen,  1120 
sternoclavicular  joint,    structures   behind, 

1108 
sterno-mastoid  muscle,  1099 
stomach,  1118 

Syme's  amputation,  lines  of  incision,  1198 
synovial  membranes  ol  loot,  1199 
of  hand,  1171 
of  knee,  1185 
of  shoulder,  1152 
tendo  Achillis.  where  divided,  1197 
tendons  around  ankle,  arrangement  of,  1194 
tenotomy,  guides  tor,  at  ankle,  1197 
thenar  and  hyj^jthenar  eminences,  1165 
thigh,  the,  1172 

thoracic  vessels,  relations  tochest  wall,  1114 
thorax  (superficial),  1109 
tibial  artery,  posterior,  1192 
tibialis  anticus  nuiscle,  1205 
tendon,  1197 
lX)sticus  muscle,  1203 
tendon,  1197 
toes,  great,  lines  for  amputation  of,  1200 
tonsils,  1097 
trapezius  mu.scle,  1142 
triangle  of  Petit,  1145 
triceps  muscle,  1154 
ulnar  artery  in  tbrearm,  1161 

nerve,  11.54,  1161 
umbilical  hernia,  congenital,  1141 
inlantile,  1141 
of  adult  life,  1141 
ring,  changes  in  adult  life,  1141 
vessels,  changes  in  adult  life,  1141 
urachus,  1135 
urethra,  the,  1124 

valves  of  heart,  topography  of,  1113 
viscera  and  visceral  regions.  1116 
behind  linea  alba,  1117 
relations  of,  to  vertebra?,  1146 
wrist  and  hand,  the,  1163 
Suspensory   \^mb,   under;    pnulo,  I  hang]    liga- 
ment, central  odontoid,  188 

origin  from  sheath  of  uotochord,  281 
of  eyeball,  858 
of  lens,  844,  850 
of  malleu.s,  67,  877 
of  ])cnis,  1032 
of  thyroid,  917 
Sustentiicnlum  {^^ustento,  I  supiwrt]  hepatis,  972 
lienis,  973 

tali  [/fl/H.i,  thea'itragalus],  163 
Sutures  [*M/«/rt,  a  seam],  varieties  of,  true,  false, 
and  gr(H)ved,  177 
basilar,  86 
coronal,  44,  69 
ethmo-lachrymal.  78 
ethnio-sphenoidal,  82 
frontal,  or  metopic,  47,  69 
fronto-ethmoidal,  H2 
fronto-parietal,  or  coronal,  44,  69 
fronto-s(|uamosal,  38,  71 
interj)arietal,  or  sagittal,  44,  69 
lamlMloid,  44,  69 
nialoinaxiliarj-,  77 
maxillo-premaxillary,  56,  72 
meso- palatine,  57,  72 
luetojiic,  47,  69 
neurocentral,  20 
occipital,  69 
occii)ito-niastoid,  ■<6 


1268 


INDEX 


Sl'R 

Surgical  and  topographical  auatxiniy  of — 
occipito-parietal,  or  lambiloid,  44,  ()9 
paricto-iiiastoid,  71,  8G 
petro  occipital,  86 
jtetro-sphenoidal,  83 
petro-S(iuaniosal,  35 
sagittal,  44,  (19 
sphcno-nialar,  71 
spheno-parietal,  71,  83 
s«juaino-si)lieiioidal,  71,  83 
squamous,  44,  71,  83 
trausverse,  80 

palatine,  72 
zygomatic,  71 
Sweat-glamls,  1077 
Sylvian  point  of  skull,  708 
Sylvius,  acpieduct  of,  708 
fissure  of,  082 
fossa  of,  682,  (588 
ventricle  of,  702 
Syme's  araputjvtion,  incisions  for,  1198 
Sympathetic,  gangliated  cords  of,  826 

cervical  portion  of,  827 
cranial  portion  of,  827 
lumbar  portion  of,  833 
sacral  portion  of.  833 
thoracic    (dorsal)    portion     of, 
830 
nerves,  the,  826.     See  also  Plexus,  sympa- 
thetic 
of  orbit,  864 
root  of  lenticular  ganglion,  752 
of  otic  ganglion,  828 
Symphysis  [<t(i',  together;  <pvu,  I  gro\v]  pubis, 

the,  205 
Synarthrosis   \_ahv,  together ;    ap6poi>,    a   joint], 
classes  of,  178 
definition  of,  177 
examples  of,  177 
Synchondrosis   [ohv ;  jjfoi'dpof,  cartilage],    sacro- 
iliac, 200 
Synovial  membrane  of  acromlo-clavicular  articu- 
lation, 219 
of  ankle  joint,  268,  1196 
of  astragalo-scaphoid  joint,  274 
of  atlauto-axoideau  joint,  central,  187 
lateral,  185 
of  calcaneo-astragaloid  joint,  anterior, 
271 
posterior,  270 
of  calcaneo-cuboid  joint,  276 
of  carpo-metacarpal  joints,  241 

joint  of  thumb,  242 
of  carpus,  240 

of  costo  central  articulation,  209 
of  costo-transverse  articulation,  211 
of  cubo-metatarsal  (outer  tareo-metatar- 

sal)  joint,  278 
of  elbow  joint,  229 
of  hip  joint,  250 

of  interchondral  articulation,  214 
of  intermetatarsal  joints,  279 
of  interphalangeal  joints,  245 
of  ^nee  joint,  259  ;  surgical  anatomy  of, 

1185  ■ 
of  metacarpo  phalangeal  joints,  243 
of  <»ccii)ito  atlantal  articulation,  183 
of  radio  carpal  joint,  235 
of  radio-ulnar  joint,  superior,  230 
of  shoulder  joint,  225,  1152 
of  sterno  clavicular  articulation,  218 
of  tarsometatarsal  joints,  middle,  278 
outer  (cubo-metatarsal),  278 


TEM 

Synovial  membrane  of  temporo-mandil)ular  (max 
illary  -  articulation,  180 
of  tibiofibular  joint,  inferior,  266 
superior,  2(i4 
of  vertebral  articular  processes,  194 
membranes  of   foot,    surgical   anatomy  of, 
1199 
of  joints  of  hand,  surgical  anatomy  of, 

il72 
of  tendons  of  hand,  surgical   anatomy 
of,  1171 
Systemic  arteries,  the,  466  ;  veins,  602 


Tabatikre  [snuflf-box]  anatomique,  1172 
Tactile  corpuscles  of  Meissner,  1076 
Ticuia  [raivid^  a  band]  hippocampi,  697 

semicircularis,  701 
Taeniae  tecta'  [tectus,  roofed],  693 
Tail  of  nucleus  caudatus,  699 

of  pancreas,  987 
Tapetum  [tapete,  a  carpet],  694 
Tarsal  arteries,  internal  and  external,  600 
cartilages,  866 

ligament  (palpebral),  external,  429,  867 
internal,  429,  867 
Tarso  metatarsal  joints,  internal,  277 
middle,  277 

outer  (cubo-metatarsal,  278 
Tarsus  [rapaog^  a  broad  surface],  bones  of,  159 

of  eyelids,  840,  866 
Teats,  supernumerary,  1215 
Teeth,  the,  86 
milk,  89 
permanent,  86 

relations  of  crowns  of  upper  to  lower,  89 
Tegmen  [a  roof]  tympani,  37,  39,  83 

of  crura  cerebri,  711 
Tegmental,  or  red  nucleus,  711 

region  of  pons,  720 
Tela  [a  web]  choroidea,  inferior,  676,  718 

superior,  702 
Temporal  [tempora,  the  temples]  artery  (super- 
ficial), 491 
deep,  anterior  and  posterior,  495 
middle,  491 

of  posterior  cerebral,  512 
bone,  35 

ossification  of,  42  ;  at  birth,  93 
convolutions  of  brain,  688 
fascia,  440 

fissures  of  brain,  687 
fossa,  70 

lobe  of  cerebrum,  687 
lymphatic  vessels,  653 
muscle,  441 
nerves  of  facial,  764 

of  mandibular  division,  757 
superficial,  of  auriculotemporal,  758 
of  temporo-malar,  754 
operculum,  682 
ridges,  44,  70 
veins,  common,  615 
deep,  616 
middle,  615 
.sui)erficial,  615 
of  diploid,  618 
Temporo- facial  division  of  facial  nerve,  764 
Temporo-malar  nerve,  754 
Temporo-raandibular   (maxillary)    articulation, 

180 
Temporo-maxillary  vein,  616 
Temporo-occipital  artery,  512 


INDEX 


i2(;o 


Tendino-troclianteric  baud,  'lAs 
Teudo  [tcndcrc,  to  stretch]  Acliillis,  :{7:{  ;  where 
divided,  1197 
Ofuli,  429,  839,  867 
Tenon's  capsule,  878 

space,  878 
Tenotomy,  guides  for  operation  at  ankle,  1197 
Tension  curves  of  cancellous  hone,  1 
Tensor  palati  muscle,  945 
tarsi  muscle,  430 
tynipaiii  muscle,  978 
vagiiuc  femoris  muscle,  3.v2 
Tenth  cranial  (pneumogastric)  nerve,  769 

rib,  102 
Tentorial  groove  of  uncinate  gyrus,  691 

surface  of  cerebral  hemispheres,  689 
Tentorium  [a  tent]  cerebelli.  675 
Teres  [round]  major  muscle,  304 

minor  muscle,  303 
Testes  of  corpora  quadrigemina,  710 
Testicles  [dim.  of  testis'],  the,  1024 
lymi)hatics  of,  662 
structure,  1026 
vessels  and  nerves  of,  1030 
Testicular  artery  of  spermatic,  561 
Thalamencephalon,  the,  670,  704 

nerve  tracts  in,  717 
Tlialamic  [dd/anot;,  a  l)ed]  arteries,  middle,  502 
Thebesius,  foramina  of,  929,  933 

valve  of.  929 
Thecaj  [^'/k//,  a  case]  of  flexor  tendons  of  hand, 

333 
Thenar  [pivap,  the  palm  of  the  hand]  eminence, 
muscles  of,  339 
surgical  anatomy  of,  1165 
fascia,  333 
Thighs,  ]nu.scles  and  fascia?  of,  344 
surgical  anatomy  of,  1172 
Third  cranial  (oculoMuotor)  nerve,  747 
foramen  for,  83 
trochanter,  147 
Thoracic  artery,  acromial,  521 
alar,  524 
axis,  521 
long,  523 

.short  or  su])erior,  521 
twelfth  or  subcostal,  548 
duct,  648,  659  ;  variations,  660 
inlet,  108 
lymphatics,  656 

nerves,  anterior,  external  and  internal,  788 
posterior,  788 
cardiac,  773 

spinal,    primary    divisions    of,   an- 
terior, 796 
posterior,  781 
first,  796  ;  variation,  796 
last  or  twelfth,  801 
portion  of  gangliated  cord,  830 
veins,  602,  643 

twelfth,  609 
ves.sels,  relations  to  chest-wall,  1114 
Thorax  [«fjpaf,  a  breastplate],  the,  898 
aperture  of,  lower,  899 
upper.  898 

structures  passing  through,  1109 
niediastina  of,  899 
movements  of,  215 
skeleton  of,  108 

surgical  anatomy  of,  superficial,  1109 
viscera  contained  in,  89;J 
Thymic  art«ries,  517 
veins,  005 


TRA 

Thymus  [thyme]  body  or  gland,  918 
lymphatics  of,  65H 
structure  of,  919 
ve&sels  and  nerves  of,  658,  920 
Thyro-arytcnoid   ligaments,    inferior  (true)  and 
superior  (false  vocal  cords),  906 
nui.scle,  909 
Thyro-ejjiglottidean  ligament,  905 
Thyro-epiglottideus  mu.scle,  910 
Thyro-glossal  duct,  917 
Thyro-hyal  centre  of  o.ssilication,  95 
Thyro  hyals,  (JO 
Thyro-hyoid  ligaments,  90() 
membrane,  906 
nui.scle,  448  ;  nerve  to,  775 
Thyroid  [Wiyjeor,  a   shield]   artery,    inferior,  513 
superior,  482  ;  branches.  4M2 
axis,  513 
bar,  90 

i)ody,  or  gland,  915 
ligaments  of,  917 
structure  of,  917 
vessels  and  nerves,  830,  918 
cartilage,  901 

Ibramen  (obturator),  138,  143 
lymphatics,  652 
veins,  mid(lle,  627 

inferior,  right  and  left,  628 
superior,  627 
Thyroidea  ima  [itnti,  lowest]  artery,  475 
Tibia  [a  pipe  or  (lute],  the,  153 
o.ssilication  of,  157 
surgical  anatomy  of,  1184 
Tibial  arteries,  anterior,  596  ;  surgical  anatomy 
of,  lia8 
posterior,  590  ;  surgical  anatomy 

of,  11M8 
recurrent,  anterior  and  posterior, 
599 
nerves,  anterior,  815  ;  branches,  815 
posterior,  816;  branches,  816 
Tibialis  anticus  muscle,  .387 

tendon,  ellect  on  plantar  arch,  1205 
where  divided,  1197 
po.sticns  muscle,  .376 

tendon,  effect  on  plantar  arch,  1203 
where  divided,  1197 
Tihio-fifscitilis  (mtieus  muscle,  461 
Tongue,  the,  884 

arteries  and  nerves  of,  888 
lymphatics  of,  652 

mucous  memltrane  and  papilla'  of,  Ht<A 
muscles  of,  888 
.septum  of.  888 
Tonsillar  arteries  of  ascending  palatine.  487 
of  lacial,  487 
lobe  of  cerebclliiMi.  715 
nerves  of  glosso  pli.irynueal,  769,  982 
recess,  944 
Tonsils,  the,  946 

surgical  anatomy  oi.  lo;i7 
vas<ular  and  nerve  suj>ply.  9 16 
l>harvngeal,  951 
T(K)th.  component  jiarts  of,  H6 
Topographical   Anatomy,  «<•  Surgical  and  topo 

gr.i)>hical  anatomy 
Toimgraphy,  cranio  cerebral,  1086 
of  spinal  nerves.  777 
Torcular  [a  wine  ]>riss]  Ht-rophili.  26 
Trabecuhv  [dim.  of  //v(^.<i,  a  lieam]  olt«'stis.  10"2H 
Trabecular  region  in  thechondnil  skull,  89 
Trachea  ["/"M'C,  rough],  the  !)13 
structure  of,  913 


1270 


INDEX 


TRA 

Trachea,  vascnlar  and  nervous  supply,  914 
Tracheal  artery  of  inferior  thyroid,  514 
layer  of  deep  cervical  lascia,  HOG 
lymphatic  jilauds,  658 
vessels,  652 
triangle,  or  inferior  carotid,  1102 
Trachealis  muscle,  914 
Trachelo-mastoid  {jpaxif/oc^  the  neck]  muscle, 

419 
Tract,  or  Tracts,  direct  cerebellar,  741 
of  the  fillet,  782 
frontal  pontine,  785 
Gower's,  781 

nerve-,  in  thalamencephalon  and  prosence- 
phalon, 717 
olfactory,  745  ;  cortex  of,  745 
pyramidal,  anterior  and  lateral,  741 
of  spinal  cord,  737 
uveal,  846 
Tractus  intermedio-lateralis.  737 
spiralis  foraminulentus,  808 
Tragicus  muscle.  872 
Tragus  [r/xj^of.  a  goat],  the,  871 
Transversalis  abdominis  muscle,  408 

colli  artery  (.scr  Transverse  cervical),  515 

muscle,  418 
fascia,  411 

humeri  artery  (see  Subscapular),  514 
Transversus  auris  mirscle,  872 
nuchte  muscle,  290,  461 
pedis  muscle,  384 
perinaei  muscle,  deep,  1068 

superficial,  1034,  1068 
Trapezium  [r/jti-fCrt,  a  table],  the,  131 

of  the  pons,  720 
Trapezius  muscle,  288  ;  nerve  to,  785 

surgical  anatomy  of,  1142 
Trapezoid  [rpdTre^'a,  a  table  ;  fIJof,   like]   bone, 
132 
ligament,  220 
Triangle,  Brj^ant's,  1173 
of  neck,  anterior.  1101 

carotid,  superior  and  inferior,  1102 
posterior,  1102 
submaxillary.  1101 
of  periureum,  rectal,  1122 

urethral,  1122 
of  Petit,  1145 

Scarpa's,  surgical  anatomy  of,  1175 
Triangular  fa.scia,  404,  1132 

fibro-cartilage  of  wrist,  232 
fossa  (fossa  of  autihelix),  871 
ligament,  inferior  (anterior  layer),  1066 

superior  or  deep  (posterior  layer),  1068 
space  at  base  of  bladder,  1017 
Triangularis  sterni  muscle,  398 
Triceps  [Ires,  three  ;  caput,  head]  extensor  cubiti 
muscle,  309  ;  nerve  to,  795 
surgical  anatomy  of,  1154 
surae  muscle,  369 
Tricipital  artery  of  posterior  circumflex,  526 
Tricusi>i(l   [<res,  three ;    chn/x's,  a  point]   valve, 

932  ;  topography  of,  1113 
Trigeminal  foramen,  36,  96 
nerve  (fifth  cranial),  749 
notch,  36 
Trigone  [~f>e'i<:,  three  ;  yuvia,  an  angle],  the,  1019 
Trigonum  habeniilic  [dim  of  habenu,  a  rein],  705 
hypoglossi,  719 
ol factor! uni,  692 
OS.  162 
vagi,  719 
Triradiate  fissure  of  cerebrum,  685 


TUB 

Triticeo-glossiis  muscle,  461 

Trochanteric  fossa,  147 

Trochanters  [r/jov'"^,  I  roll]  of  lemur — 

greater,  147  ;  surgical  anatomy  ol",  1172 

lesser,  147 

third,  147 
Trochlea  [rfioxi^ia,  a  pulley],  the,  120 

of  superior  oblique  muscle,  857 
Trochlear  artery  of  lachrymal,  500 

nerve,  or  fourth  cranial,  74H 
Trochoides  [rpoxoc,  a  wheel],  definition  and  ex- 
amples of,  178 
True  ligaments  of  bladder,  1018 

pelvis,  145 

ribs,  98 

vocal  cords,  911 
Tubal  artery,  1054 
Tube,  collecting,  of  kidney,  1011 

of  epididymis,  1027 

looped,  of  Henle,  1011 
Tuber  cinereum,  707 

omentale  of  liver,  979 

valvular,  715 
Tubercle,  accessory,  of  lumbar  vertebrae,  12 

adductor,  150 

of  atlas,  anterior  and  posterior,  8 
for  transverse  ligament,  8 

of  calcaneum,  anterior,  inner  and  outer,  163 

cervical,  of  femur,  superior  and  inferior,  147 

condyloid,  of  mandible,  64 

deltoid,  of  clavicle,  110 

genial,  62 

lachrymal,  57 

laminated,  of  cerebellum,  715 

Lisfranc's,  100 

of  Lower,  931 

mammillary,  of  lumbar  vertebrae,  12 

of  optic  thalamus,  anterior  and  posterior,  705 

orbicular,  of  incus,  68 

peroneal,  of  calcaneum,  163 

pharyngeal,  of  basi-occipital,  27,  73 

post-glenoid,  35 

of  rib.  98 

of  Rolando,  723 

of  tibia,  153  ;  surgical  anatomy  of,  1184 
Tubercles  of  Montgomery,  1070 
Tuberculum  [dim.  of  tubei']  acusticum,  719,  766 
Tuberosity,  bicipital,  126 

of  clavicle,  109 

of  fifth  metatarsal,  172 

of  humerus,  greater  and  lesser,  115 

of  ilium,  139 

of  ischium,  139 

of  maxilla,  55,  72 

of  palate  bone,  59 

of  scaphoid,  carpal,  129 
tarsal,  166 

of  tibia,  153 
Tubules,  uriniferous,  1011 
Tubuli  recti  of  testis,  1027 

.seminiferi,  1027 
Tunica  albuginea  of  ovaiy,  1053 
of  penis,  1032 
of  testis,  1026 

propria  of  kidney,  1010 

vaginalis,  1024 

vasculosa  of  testicle,  1027 
Tiirbinal  process  of  lachrymal,  53 
Turbinals  [lurho,  a  whirl]  (ethmo-turbinals), 

inferior,  52  ;  ossification  of,  53 
at  birth,  95 

sphenoidal,  51  ;  at  birth,  94 

superior,  49 


INDEX 


1271 


Turl)iuate(l  [turho,   a  whirl  :    iVom  their  coiled 
nature]  crests  of  maxilla,  5(J 

of  palate  bone,  58 
Twelfth  (last)  dorsal  artery,  ooO 

cranial  or  hviioglossal  nerve,  774 
rib,  102 
Tympanic  artery  of  ascendin<^  pharyngeal,  482 
of  internal  maxillary,  493,  878 
of  middle  meningeal.  41)1 
of  stylo-mastoid,  A\)\ 
of  Vidian,  49G 
canaliculus,  37,  73 
cavity,  875 

nerve    of     glosso  pharvngeal   (Jacobson's), 
768,  87!) 
or  small  deep  petrosal,  828,  879 
plate,  37,  73 
plexus,  879 

portion  of  temporal  bone,  35  ;  at  birth,  93 
vein,  615 
Tvmpano-lival    process,    90  :  centre  of  ossifica- 
tion, })0 
Tympanum  \_7i ii-nvor,  a  drum],  the,  39 
measurements  of,  42 
muscles  of,  877 
ossicles  of,  87(> 
promontory  of,  39 
proper,  40 
roof  of,  83 

vessels  and  nerves  of,  878 
vestibule  and  semicircular  canals  of,  41 


Ulna  [ii'Ah'r],  the  elbow],  the,  122 

ossification  of,  125 
Ulnar  arterj',   531  ;  surgical  anatomv  of,   llGl, 
1154 
in  forearm,  531  ;  variations,  531 
in   the    palm    (superficial    palmar 

arch),  536  ;  variations,  537 
at  the  wrist,  535 
carpal,  anterior  and  posterior,  535 
recurrent,  anterior  and  posterior,  533 
condyle  of  humerus  (internal),  120 
nerve,  794  ;  surgical  anatomy  of,  1161 
vein,    superficial,    anterior    and    posterior, 
641 
Umbilical  fissure  of  liver,  978,  979 
hernia,  coverings  of,  1141 

parts  concerned  in.  1141 
varieties  ot",  1141 
region,  1208 

ring,  changes  in,  in  adult  life,  1141 
vein,  638 

vessels,  changes  in,  in  adult  life,  1141 
T'mbilicus,  402 
Umbo  [the  boss  of  a  shield]  of  membrana  tym- 

pani,  873 
Unciform  [uncus,  a  hook]  l)one,  the,  133 
process  of  ethmoid,  50 

of  unciform  bone,  133 
Uncinate  artery  of  posterior  cerebral,  512 
of  posterior  communicating,  502 
convolution  (or  gyrus),  691 
Uncus  [a  hook]  of  uncinate  gyrus,  691 
Ungual    \_iuuinis,  a   nail]    ])halanj:es  of  fingers, 
i:58  ;  ossificaticm  of,  138 
of  toes,  174  :  ossification  of,  175 
Uracheric  artery  of  superior  ve.sicnl,  570 
Urachus  [orpov,  urine  ;  'V'-',  I  hold],  the.  1135 
Uretal  artery  (ureteric)  of  common  iliac,  566 
of  ovarian,  562 


Uretal  artery,  of  renal,  560 
of  spermatic,  5(i1 
(ureteric)  of  superior  vesical,  570 
Ureter  [oi'y,^,,,  \  jja.ss  water].  1014 
lymphatics  of,  1015 
structure,  1015 
varieties,  1015 
vessels  and  nerves,  1015 
Unthra  ['(('poi',  urine],  the  female,  1041 

male,  10.35;  surgical  anatomy  of.  1124 
Urethral  triangle  of  periiucum,  1122 
Urinary  bladder,  the.  1016 

meatus,    internal,    relation    to    p.lvii-    umII, 
1018 
external,  10.3H 
Uriniferous  tubules,  1011 
Uro-genital  sinus,  1057 
Uterine  artery,  605,  1053 
of  ovarian,  562 
j)lexus  (nerve),  838,  1054 
vein,  10.")3 
Utero  inguinal  (ronnd)  ligament,  1050 
Uteroovarian  ligaments,  1051 
Utero-])elvic  ligaments,  1051 
Utero-sacral  ligaments,  1049.  1050 
Utero-vesical  ligaments.  1049 
Uterus  [the  womb],  the,  1044 
ligaments,  1047 
lymphatics  of,  662 
nerves  of,  838,  1053 
structure  of,  1047 
variation  according  to  age,  1047 
masc-ulinus.  1037,  1215 
Utricle  [dim.  of  iiterui<],  the.  881 
Uveal  [i/m.  a  grape]  tract,  846 
Uvula  [dim.  of  «(y/]  of  cerebellum,  715 
of  Lieutaud.  1019 
of  palate,  944 


VAfJiXA  [a  sheath],  the.  1042 
ibrm  and  direction,  1042 
lymphatics.  (i(i2,  1044 
relations,  1043 
structure.  1044 
vessels  and  nerves,  1044 
Vaginal  arteries,  571 
azygos  artery,  571 
examination,  topography,  1131 
plexus  (nerve).  i-'3h 
process  of  temporal  l)one,  40,  73 
Vagus  [ivf/70,  I  wander]  (pneumogastric)  ner^■e. 

76!) ' 
Valentin,  ganglion  of,  754 
Vallecula  of  cerebellum,  714 

of  tongue,  884 
Valsalva,  sinuses  of,  468,  932 
Valve.  Eustachian,  929  :  in  fretus.  910 
of  foramen  ovale  (in  fietus),  !)40 
ileo-cacal,  !)72 
of  Thebe-sius,  !)29 
of  Vieu8.sens,  717 
Valves  of  heart,  bicuspid'(or  mitrari,  934 
semilunar,  aortic,  !».■{.{ 

pulmonary.  932 
tricuspid.  5)32:  topography  oi.  lli:^ 
Valvuljp  conniventes   [lying  close  together]   of 
intestine.  !»(iH 
(luerin,  103H 
Vas  [a  vesw'l]  aberrans.  of  Ilaller.  lo*.»7 
deferens,  the,  102m 
artery  to,  570 
I  nerves  to,  837 


1272 


INDEX 


VAS 

Vasa  aberrantia,  1215 

brevia  of  splenic  artery,  558 

veius,  <J;i7 

eft'erentia,  1()"J7 

iutestini  tenuis,  560 

Vascular  coat  of  eyeball,  847 

Vastus  extern  us  muscle,  3(iti 

internus  and  crureus,  :5G7  ;  division  between 
the  two  muscles,  367 
Vater,  ampulla  of,  984 
Vein,  or  Veius,  divisions  of  the,  602 
of  abdomen,  630 
acromial  thoracic,  643 
angular,  613 

auricular,  anterior  and  posterior,  616 
of  heart,  left,  610,  937 
right,  610 
axillary,  643 
azygos  major,  606 

minor  et  tertia,  607 
basilar,  624 
basilic,  641 
brachial,  643 

median,  641 
brachiocephalic,  602  ;    variations,  606 
of  brain,  623 
bronchial,  609,  925 
buccal,  614,  616 

capsular,  or  suprarenal,  632,  1051 
cardiac,  anterior,  610,  937 
great,  610.  937 
posterior,  610,  938 
small,  610 

smaller  anterior,  611 
central,  of  retina,  626 
cephalic,  641 
cerebellar,  inferior,  624 
superior,  624 
cerebral,  623 

central  or  deep,  624 
cortical,  623 
cervical,  deep,  614,  628 
transverse,  617 
choroid,  624 
ciliary,  anterior  and  posterior,  625 

lower  posterior,  626 
circumflex  iliac,  deep,  647 

superficial,  631,  644 
of  shoulder,  643 
coronary,  of  heart,  609,  9:57 

of  lips,  inferior  and  superior,  613 
of  stomach,  636 
of  cranium,  see  Sinuses 
cystic,  G36 
dental,  inferior  (mandibular),  616 

posterior,  616 
diaphragmatic,  or  phrenic,  633 
digital,  of  foot.  644 
of  hand,  640 
of  diploe,  618 
dorsal,  spinal,  629 
of  penis,  638 
of  ear,  625 
emissary,  of  cranium,  672 

of  mastoid,  622,  672 
emulgent,  631 
epigastric,  deep.  647 

superficial.  631,  644 
ethmoidal,  anterior  and  posterior,  626,  897 
extra-spinal,  629 
facial,  common,  613 

communicatinii,  613.  614 
transverse,  615  ;  variations,  614 


Vein,  femoral,  common,  647 

cutaneous,  external  and  internal,  644 
deep.  647 
of  foot  and  leg,  646 
frontal,  612 

of  diploe,  618 
fronto-sphenoidal,  of  diploid,  618 
of  Galen,  of  brain.  624,  702 

of  heart.  611,  9.30,  937 
gastric  (coronary),  636 
gastro-epiploic,  left,  637 

right,  637 
glandular  (submaxillary),  614 
gluteal,  638 

ha'uiorrhoidal,  639  ' 

of  head  and  neck,  deep,  617 

.superficial,  611 
of  heart,  609 
hemiazygos,  607 

acce.ssoria,  608 
hepatic,  633,  982 
iliac,  common.  634  ;  variations,  634 

external,  647 

internal,  638 
ilio-lumbar,  634,  638 
innominate,  603  ;  variations,  605 
intercostal ,  superior,  604,  608 
interventricular,  anterior,  610 

posterior,  610,  937 
intra-spinal,  629 
jugular,  anterior,  617,  1100 

external,  616  ;  variations,  617 

internal,  627 

posterior  external,  617 
jugulo-cephalic,  643 
labial,  inferior  and  superior,  614 
lachrymal,  626 
laryngeal,  627 
lingual,  627 
of  lower  extremity,  deep,  646 

superficial,  644 
lumbar,  633 

a.scending,  633 
mammary,  internal,  605 
mandibular,  616 

marginal,  left  and  right,  610,  937 
masseteric,  614,  615 
mastoid  emissary.  622.  672 
maxillary,  internal,  615 

anterior,  614 
median  basilic,  641 

cephalic,  641 

deep,  641, 643 

superficial,  641 
mediastinal,  605 
of  medulla  oblongata,  625 
medullary  or  medulli-spinal.  630 
meningeal  cranial,  middle,  616 

spinal,  extra-medullary,  629 
mesenteric,  inferior,  637 

superior,  636 
nasal,  625 

lateral,  superior  and  inferior,  613 

transverse,  613 
of  neck,  deep,  627 

superficial,  616 
oblique,  of  Marshall,  610 
obturator,  638 
occipital,  614 

of  diploe,  619 
(Esophageal,  609 
ophthalmic,  common,  625 

inferior,  616,  626 


INDEX 


127:^ 


Vein,  ophthalmic,  superior,  (J25 
ol'  orbit,  025,  8(j;j 
orbital,  G15 
ovarian,  633,  1053 
palatine,  inferior  or  descending,  «14 

superior,  <jl(J 
palpebral,  inferior,  614 

suj)erior,  613 
pancreatic,  637 
pancreaticoduodenal,  637 
parietal,  external,  of  diploe.  618 
parieto-occipital,  of  diploe,  619 
Itarotid.  614,  615 
of  pelvis,  638 
pericardiac,  605 
peroneal.  686 
pharyngeal,  626 
phrenic,  inferior,  633 
plexuses  of,  see  Plexuses,  venous 
of  pons  Varolii,  625 
popliteal,  646  ;  surgical  anatomy-  of,  1188 

variations,  646 
portal,  634 
post-ventricular,  939 
preventricular,  611,  937 
profunda.  647 
pterygoid,  615 
pudic,  638,  1067 
pulmonary,  602 
pyloric,  636 
radial,  superficial,  641 
renal.  631 

sacral,  middle,  634  ;  lateral,  638 
saphenous,  long  or  internal,  644  ;  surgical 
anatomy  of,  1191 
short  or   external,  644  ;  surgical  anat- 
omy of,  1188,  1191 
of  scalp  and  face,  superficial,  611 
sciatic,  638 
spermatic,  632 
spheno-palatine,  616,  897 
spinal,  628 
of  spinal  cord,  630 
splenic,  637 

subclavian,  643  ;  variations,  643 
subcostal,  609 
submaxillary,  614 
submental,  614 
subscapular,  643 
supra-orbital,  612,  616 
suprarenal,  632,  1051 
supriiscapular,  617 
systemic,  602 
temjwral,  common,  615 
deep,  616 

middle  and  superficial,  615 
of  diploe.  618 
temporo-iuaxillary,  616 
thoracic,  long,  643 
of  thorax,  602 
thymic,  605 
thyroid,  628 
tibial,  646 
tympanic,  615 
ulnar,  superficial,  641 
umbilical,  63h 
of  upper  extremity,  deep,  643 

superficial,  639 
uterine,  1053 

vasa  brevia,  of  splenic,  637 
of  vertebne  (bodies),  630 
vertebral,  628 
Vesalian,  616 


Vena  azygos  major,  606 
minor,  607 
tertia,  608 
cava  inferior,  631 

fissure  in  liver  for,  979 
variations,  633 
superior,  603;  to|x)graphy  of   1114 
variations,  605 
corporis  striati,  624 
Galeni  (cardiac),  611,  937 
hemiazygos,  607 

acces.soria,  (i08 
magna  Galeni  (cerebral),  6-24,  7(i> 
portie,  see  Portal  vein 
salvatella,  641 
Vena'  basis  vertebne,  630 
comites,  brachial,  643 

tibial,  646 
cordis  minima',  609,  929 

parva',  611 
vorticosa-  [vorhx,  a  whirlpool],  845,  853 
Velum  [a  veil]  interpo.«itum,  702 

medullary,  of  cerebellum  inferior,  715,  717 
superior,  717 
Venous  side  of  heart,  927 

Ventricle  [dim.  of  iT«^t>r,  the  belly]  of  Arautius 
718 
of  brain,  lateral,  670,  694 
fifth  (Sylvian  1,  670,  701 
fourth,  67(»,  717 
third,  670,  704 
of  heart,  left,  933 

right,  931 
of  larynx.  911 
Ventricular  walls  of  foetal  heart,  977 
Ventriculus  terininaiis  of  cord,  737 
Verheyen,  stars  of,  1011 
Vermiform  [vermis,  a  worm]  appendix,  971 
artery  of  jwsterior  inferior  cerebellar,  511 

of  superior  cerebellar,  512 
fossa  (basis  cranii),  26,  86 
process  of  cerebellum,  inferior,  715 
superior.  714 
Vertebra  [vertcre,    to   turn  :    irom   its   rotatory 
motion],  anticlinal,  12 
body  of,  mor])hoIogy  of.  22 
cervical,  peculiar,  8";  typicixl,  7 
half  vertebra,  12 

lumbar,  peculiar.  13  :  typical,  12 
neural  arch  of,  morphology  of,  23 
o&siHcation  of,  19 
prominens,  9;  muscles  attached  to,  11 

ossification  of,  19 
sacral  and  coccygeal,  14,  17 
thoracic  or   dorsal,   peculiar,    12;    typiciil, 

typical,  5 
Vertebral  aponeurosis,  408 

artery.  509;  variations.  510 

branches   to,    from    middle    cervical 
ganglion.  KV2 
of  deep  cervieal,  519 
of  lumbar.  554 
column,    arterial    and    nerve    supply     and 

movements  of,  197 
ribs,  Jt8 

spines,  tojwgraphy  of,  1142 
veins,  628 
Vertebro  chondral  ribs,  98 
Vertebro  sternal  ribs,  98 
Verumontiinum  [veru,  a  ridge],  1037 
Vesaliau  vein,  616 
Vesical  {t-esica,  a  bladder]  arteries,  569 


1274 


IXDEX 


Vesical  arteries  of  obturator  artery.  5T2 

lymphatics,  662 

nerves,  837 

plexus,  nerve,  837 
venous.  G'Ai) 

portion  of  ureter,  1015 
Vesicles  [dim.   of  veaica,   a  bladder],  cerebral, 

anterior,  middle,  and  posterior,  669 
Vesico-pubic  muscle.  1019 
Vesiculae  [dim.  of  vesica,  a  bladder]  seminales, 

1029 
Vestibular  artery  of  stylo- mastoid,  491 

nerve,  767 
Vestibule  of  labvrinth,  41,  *79 

of  mouth.  942 

of  nostrils,  1^89,  fi93 

of  vagina,  1039 
Vestigial  and  abnormal  structures,  1209 

bones  (e.g.  fibula),  159 

fold  of  pericardium.  926 
Vicq  d'Azyr,  bundles  of,  702,  707 

foramen  caecum  of,  721 
Vidian  artery,  496 

canal,  33,  70  ;  at  birth,  93 

nerve,  755 
Vieussens,  valve  of,  717 
Villi  [villus,  shaggy]  of  sinall  intestine,  968 
Vincula  [small  chains]  atcessoria,  333 
Viscera  [i/scM.s,  pi.  visccia,  an  organ],  abdominal, 
the,  954,  1116 

relations  of,  to  vertebrae,  1146 
Visceral  branches  of  abdominal  aorta,  555 
of  sacral  plexus,  810 

lymphatic-s  of  pelvis,  662 
of  thorax,  658 
Vitreous  [vitrum,  glass]  humour,  850 
Vocal  cords,  true  and  false,  912 
Volar  [vola,  the  palm]  artery,  superficial,  541 
Vomer  [a  ploughshare],  53 

ossification  of,  54 

at  birth,  95 
Vulva  [volvere,  to  roll],  the,  1038 


W.\LDEYERS  glands  of  evelids,  866 
Walther,  ducts  of,  949 


"Wharton's  (submaxillary)  duct,  848 
"White  line  of  obturator  fascia,  1061 

matter  of  cerebellum.  716 
of  eucephalon,  679 
"Wings  of  sphenoid,  greater  and  le.s.ser,  31 
AVinslow,  foramen  of,  955 
Wirsung,  canal  of,  987 
"\i\'^i.sdom  teeth,  88 
"Wolfliau  body,  1055 

duct,  1055 
Womb,  the,  1044.     See  Uterus 
"Wormian  bones,  48 
"Wrisberg,  cardiac  ganglion  of,  939 

cartilages  of,  905 

nerve  of,   1189 
"Wrist,  surgical  anatomy  of,  1163 

joint,  the,  sec  Radio-carpal  articulation 

skin-folds  of,  1164 


Xiphoid  [ii<poc,  a  sword  ;   enJof,  like]  artery  of 
superior  epigastric,  518 
cartilage,  104 


Yellow  elastic  fibres  of  trachea,  914 
spot  of  eye,  843 


Zeiss's  glands  of  eyelids,  866 
Zone,  boundary  of  Lissauer,  741 

mixed  lateral,  of  spinal  cord,  741 
of  uterus,  intra  vaginal,  1044 
supravaginal,  1044 
of  vaginal  attachment,  1044 
Zygoma  [Ct'}'<>c,  a  yoke  :  the  union  between  the 
facial  bones  and  those  of  the  side  of  the 
head],  the,  35 
relation  of,  to  cranial  contents,  727 
Zygomatic  Ibssa,  70  ;  lymphatics  of,  651 
process  of  malar  bone,  61 
region,  71 
suture,  70 
Zygomatico-orbital  artery,  491 
Zygomaticus  major  muscle,  431 
minor  muscle,  439 


I 


i 


Date  Due 

1 

[••J                             CAT.    NO      ?3    233                             PRINTED    IN    U.S.A. 

IlillllllllllllltllllPI  "I  111  Ml"'!!"" 


D  000  223  858  2 


Morris . 

Human  anatomy 


QSU 

M8T6h 

1898 


Morrir . 

Hiomf-n  anatomy 


M8T6h 
1898 


CALIFORNIA  COLLEGE  OF  MEDICINE  LIBRARY 

UNIVERSITY  OF  CALIFORNIA.  IRVINE 

IRVINE,  CALIFORNIA  92664 


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MHTTO   IM   U   •.* 


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